U.S. patent application number 10/431495 was filed with the patent office on 2004-09-23 for fabrication of a blade from a wafer having a blade separation structure.
Invention is credited to Barnes, Stephen Matthew, Smith, Norman Frank, Sniegowski, Jeffry Joseph.
Application Number | 20040182824 10/431495 |
Document ID | / |
Family ID | 32987539 |
Filed Date | 2004-09-23 |
United States Patent
Application |
20040182824 |
Kind Code |
A1 |
Barnes, Stephen Matthew ; et
al. |
September 23, 2004 |
Fabrication of a blade from a wafer having a blade separation
structure
Abstract
A method for fabricating a cutting blade (56) from a wafer (130)
is disclosed. The wafer (130) is etched to define part of the
perimeter of the blade (56). This etch also defines a blade support
(131) that maintains a structural interconnection between the blade
(56) and the wafer (130). A score (132) is formed across at least
part of the blade support tab (131). Fracturing the blade support
tab (131) at least generally along the score (132) at some point in
time after the completion of the etch facilitates the separation of
the blade (56) from the wafer (130).
Inventors: |
Barnes, Stephen Matthew;
(Albuquerque, NM) ; Sniegowski, Jeffry Joseph;
(Tijeras, NM) ; Smith, Norman Frank; (Albuquerque,
NM) |
Correspondence
Address: |
MARSH, FISCHMANN & BREYFOGLE LLP
3151 SOUTH VAUGHN WAY
SUITE 411
AURORA
CO
80014
US
|
Family ID: |
32987539 |
Appl. No.: |
10/431495 |
Filed: |
May 7, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10431495 |
May 7, 2003 |
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10390484 |
Mar 17, 2003 |
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10431495 |
May 7, 2003 |
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10390357 |
Mar 17, 2003 |
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10431495 |
May 7, 2003 |
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10390353 |
Mar 17, 2003 |
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10431495 |
May 7, 2003 |
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10390488 |
Mar 17, 2003 |
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Current U.S.
Class: |
216/83 |
Current CPC
Class: |
B26B 9/00 20130101; A61F
9/013 20130101; A61F 9/0133 20130101; B26B 29/06 20130101; Y10T
29/49885 20150115; A61B 17/3211 20130101 |
Class at
Publication: |
216/083 |
International
Class: |
C23F 001/00 |
Claims
What is claimed is:
1. A method for fabricating a blade from a substrate, comprising
the steps of: executing a first etching step comprising etching
said substrate to define a first cutting edge surface for a first
blade; and executing a second etching step comprising etching said
substrate to define a first score, wherein said first blade may be
separated from said substrate at least substantially along said
first score.
2. A method, as claimed in claim 1, wherein: said substrate is
ceramic.
3. A method, as claimed in claim 1, wherein: said substrate is
silicon.
4. A method, as claimed in claim 1, wherein: said substrate is
quartz.
5. A method, as claimed in claim 1, wherein: said substrate is a
single crystal material.
6. A method, as claimed in claim 1, wherein: said first and second
etching steps are simultaneously executed with a single
etchant.
7. A method, as claimed in claim 6, wherein: said single etchant is
an anisotropic etchant.
8. A method, as claimed in claim 1, wherein: said first and second
etching steps are each a chemical etch.
9. A method, as claimed in claim 1, further comprising the step of:
defining a first cutting edge for said first blade using said first
etching step, wherein said first cutting edge is parallel with a
length dimension of said first score.
10. A method, as claimed in claim 1, further comprising the step
of: executing a third etching step comprising etching through said
substrate to define a first portion of a perimeter of said first
blade, and etching through said substrate to define a first blade
support tab interconnecting said first blade with a remainder of
said substrate, wherein said first score extends across at least a
portion of said first blade support tab.
11. A method, as claimed in claim 10, wherein: said first, second,
and third etching steps are simultaneously executed with a single
etchant.
12. A method, as claimed in claim 10, wherein: said first score
extends across only a portion of said first blade support tab.
13. A method, as claimed in claim 10, wherein: said first score
comprises first and second ends, wherein said first and second ends
are spaced inwardly from first and second edges, respectively, of
said first blade support tab.
14. A method, as claimed in claim 10, wherein: said third etching
step comprises etching through said substrate to define a pair of
notches on a first perimeter wall of said first blade, wherein said
first blade support tab extends between said pair of notches, and
wherein said first score is located so that said pair of notches
are disposed beyond said first score.
15. A method, as claimed in claim 10, wherein: said second etching
step comprises locating said first score at a minimum width
location along said first blade support tab.
16. A method, as claimed in claim 1, wherein: said second etching
step comprises etching into said substrate a first amount that is
within a range of about 2% to about 75% of a thickness of said
substrate.
17. A method, as claimed in claim 1, wherein: said second etching
step comprises etching into said substrate a first amount that is
within a range of about 2% to about 5% of a thickness of said
substrate.
18. A method, as claimed in claim 1, wherein: said second etching
step comprises etching into said substrate a first amount that is
within a range of about 10 microns to about 30 microns.
19. A method, as claimed in claim 1, wherein: said second etching
step comprises etching through only a portion of a thickness of
said substrate.
20. A method, as claimed in claim 1, wherein: said second etching
step comprises etching said substrate to define first and second
planar score surfaces that intersect along a first line.
21. A method, as claimed in claim 19, wherein: said first line is
aligned with a crystallographic plane of said substrate.
22. A method, as claimed in claim 1, wherein: said second etching
step comprises aligning said first score with a crystallographic
plane of said substrate.
23. A method, as claimed in claim 1, wherein: said first score
comprises a first score surface that is parallel with said first
cutting edge surface.
24. A method, as claimed in claim 1, further comprising the steps
of: forming a first masking layer on said substrate; and
transferring a blade mask onto said first masking layer, wherein
each of said first and second etching steps are executed through
openings in said first masking layer in accordance with said blade
mask.
25. A method, as claimed in claim 24, wherein: a first portion of
said transferring step is selected from the group consisting of
photomasking, masking, photolithography, and microphotolithography
said first masking layer in accordance with said blade mask, and
wherein a second portion of said transferring step is selected from
the group consisting of wet chemical etching, plasma etching,
reactive ion etching, and ion beam milling said first masking layer
in accordance with said blade mask.
26. A method for fabricating a blade from a substrate, comprising
the steps of: executing a first etch comprising etching through a
substrate to define a first perimeter portion of a first blade,
wherein said first perimeter portion extends between first and
second ends such that said first blade remains part of said
substrate between said first and second ends; executing a second
etch comprising etching through said substrate to define a first
blade support tab, wherein a first free end of said first blade
support tab merges into said first blade between said first and
second ends; and executing a third etch comprising etching a first
score across at least a portion of said first blade support
tab.
27. A method, as claimed in claim 26, wherein: said substrate is
ceramic.
28. A method, as claimed in claim 26, wherein: said substrate is
silicon.
29. A method, as claimed in claim 26, wherein: said substrate is
quartz.
30. A method, as claimed in claim 26, wherein: said substrate is a
single crystal material.
31. A method, as claimed in claim 26, wherein: said first, second,
and third etches are simultaneously executed with a single
etchant.
32. A method, as claimed in claim 31, wherein: said single etchant
is an anisotropic etchant.
33. A method, as claimed in claim 26, wherein: said first, second,
and third etches are each a chemical etch.
34. A method, as claimed in claim 26, wherein: said first etch
comprises defining a first cutting edge for said first blade,
wherein said first cutting edge is parallel with a length dimension
of said first score.
35. A method, as claimed in claim 26, wherein: said first score
extends across only a portion of said first blade support tab.
36. A method, as claimed in claim 26, wherein: said first score
comprises first and second ends, wherein each of said first and
second ends are spaced inwardly from first and second side edges of
said first blade support tab.
37. A method, as claimed in claim 26, wherein: said first etch
comprises etching through said substrate to define a pair of
notches on a first perimeter wall of said first blade, wherein said
first blade support tab extends between said pair of notches, and
wherein said first score is located so that said pair of notches
are disposed beyond said first score.
38. A method, as claimed in claim 26, wherein: said third etch
comprises etching into said substrate a first amount that is within
a range of about 2% to about 75% of a thickness of said
substrate.
39. A method, as claimed in claim 26, wherein: said third etch
comprises etching into said substrate a first amount that is within
a range of about 2% to about 5% of a thickness of said
substrate.
40. A method, as claimed in claim 26, wherein: said third etch
comprises etching into said substrate a first amount that is within
a range of about 10 microns to about 30 microns.
41. A method, as claimed in claim 26, wherein: said third etch
comprises etching through only a portion of a thickness of said
substrate.
42. A method, as claimed in claim 26, wherein: said third etch
comprises etching said substrate to define first and second planar
score surfaces that intersect along a first line.
43. A method, as claimed in claim 42, wherein: said first line is
aligned with a crystallographic plane of said substrate.
44. A method, as claimed in claim 26, wherein: said third etch
comprises aligning said first score with a crystallographic plane
of said substrate.
45. A method, as claimed in claim 26, wherein: said first score
comprises a first score surface that is parallel with a first
cutting edge surface of said first blade defined by said first
etch.
46. A method, as claimed in claim 26, wherein: said third etch
comprises locating said first score at a minimum width location
along said first blade support tab.
47. A method, as claimed in claim 26, further comprising the steps
of: forming a first masking layer on said substrate; and
transferring a blade mask onto said first masking layer, wherein
each of said first, second, and third etches are executed through
openings in said first masking layer in accordance with said blade
mask.
48. A method, as claimed in claim 47, wherein: a first portion of
said transferring step is selected from the group consisting of
photomasking, masking, photolithography, and microphotolithography
said first masking layer in accordance with said blade mask, and
wherein, a second portion of said transferring step is selected
from the group consisting of wet chemical etching, plasma etching,
reactive ion etching, and ion beam milling said first masking layer
in accordance with said blade mask.
49. A method for fabricating a blade from a substrate, comprising
the steps of: creating at least one opening that extends completely
through said substrate, wherein said creating step comprises
defining a first perimeter portion of a first blade, wherein said
first perimeter portion extends between first and second ends such
that said first blade remains part of said substrate between said
first and second ends; and defining a first score having first and
second ends, wherein each of said first and second ends are spaced
from any said opening from said creating step.
50. A method, as claimed in claim 49, wherein: said substrate is
ceramic.
51. A method, as claimed in claim 49, wherein: said substrate is
silicon.
52. A method, as claimed in claim 49, wherein: said substrate is
quartz.
53. A method, as claimed in claim 49, wherein: said substrate is a
single crystal material.
54. A method, as claimed in claim 49, wherein: said creating step
comprises etching.
55. A method, as claimed in claim 54, wherein: said etching step is
an anisotropic etch.
56. A method, as claimed in claim 49, wherein: said defining a
first perimeter portion step comprises defining a first cutting
edge, wherein said defining a first score step comprises disposing
said first score in parallel relation with said first cutting
edge.
57. A method, as claimed in claim 49, wherein: said defining a
first perimeter portion step comprises defining a planar first
cutting edge surface, wherein said defining a first score step
comprises defining a planar first score surface, wherein said first
cutting edge surface and said first score surface are parallel.
58. A method, as claimed in claim 49, wherein: said creating step
further comprising defining a first blade support tab that
interconnects said first blade with a remainder of said substrate,
wherein said first score extends across at least a portion of said
first blade support tab.
59. A method, as claimed in claim 58, wherein: said first score
extends across only a portion of said first blade support tab.
60. A method, as claimed in claim 58, wherein: said first and
second ends of said first score are spaced inwardly from first and
second side edges, respectively, of said first blade support
tab.
61. A method, as claimed in claim 58, wherein: said defining a
first perimeter portion step comprises defining a pair of notches
on a first perimeter wall of said first blade, wherein said first
blade support tab extends between said pair of notches, wherein
said first score is located so that said pair of notches are
disposed beyond said first score.
62. A method, as claimed in claim 58, wherein: said defining a
first score step comprises locating said first score at a minimum
width location along said first blade support tab.
63. A method, as claimed in claim 49, wherein: said defining a
first score step comprises etching.
64. A method, as claimed in claim 49, wherein: said defining a
first score step comprises extending said first score to a depth
within said substrate that is within a range of about 2% to about
75% of a thickness of said substrate.
65. A method, as claimed in claim 49, wherein: said defining a
first score step comprises extending said first score to a depth
within said substrate that is within a range of about 2% to about
5% of a thickness of said substrate.
66. A method, as claimed in claim 49, wherein: said defining a
first score step comprises extending said first score to a depth
within said substrate that is within a range of about 10 microns to
about 30 microns.
67. A method, as claimed in claim 49, wherein: said defining a
first score step comprises extending said first score through only
a portion of a thickness of said substrate.
68. A method, as claimed in claim 49, wherein: said defining a
first score step comprises defining first and second planar score
surfaces that intersect along a first line.
69. A method, as claimed in claim 68, wherein: said first line is
aligned with a crystallographic plane of said substrate.
70. A method, as claimed in claim 49, wherein: said defining a
first score step comprises aligning said first score with a
crystallographic plane of said substrate.
71. A method, as claimed in claim 49, wherein: said creating step
and said defining a first score step each comprise etching said
substrate.
72. A method, as claimed in claim 71, further comprising the steps
of: forming a first masking layer on said substrate; and
transferring a blade mask onto said first masking layer, wherein
said etching step is executed through openings in said first
masking layer in accordance with said blade mask.
73. A method, as claimed in claim 72, wherein: a first portion of
said transferring step is selected from the group consisting of
photomasking, masking, photolithography, and microphotolithography
said first masking layer in accordance with said blade mask, and
wherein a second portion of said transferring step is selected from
the group consisting of wet chemical etching, plasma etching,
reactive ion etching, and ion beam milling said first masking layer
in accordance with said blade mask.
74. A method for fabricating a blade from a substrate, comprising
the steps of: creating at least one opening that extends completely
through said substrate, wherein said creating step comprises
defining a first perimeter portion of a first blade, wherein said
first perimeter portion extends between first and second ends such
that said first blade remains part of said substrate between said
first and second ends; and defining a first score on said substrate
that is associated with said first blade, wherein said defining a
first score step comprises using a same technique as said creating
step, and wherein said first blade may be separated from a
remainder of said substrate using said first score.
75. A method for fabricating a blade from a substrate, comprising
the steps of: creating at least one opening that extends completely
through said substrate, wherein said creating step comprises
defining a first perimeter portion of a first blade, wherein said
first perimeter portion extends between first and second ends such
that said first blade remains part of said substrate between said
first and second ends; and defining a first score on said substrate
that is associated with said first blade, wherein said defining a
first score step is executed during said creating step, and wherein
said first blade may be separated from a remainder of said
substrate using said first score.
76. A method for fabricating a blade from a substrate, comprising
the steps of: creating at least one opening that extends completely
through said substrate, wherein said creating step comprises
defining a first perimeter portion of a first blade, wherein said
first perimeter portion extends between first and second ends such
that said first blade remains part of said substrate between said
first and second ends, wherein said first perimeter portion
comprises a first cutting edge and an oppositely disposed rear end;
and defining a first score on said substrate that is associated
with said first blade, wherein said first score is located between
a rearwardmost portion of said rear end and said first cutting
edge, and wherein said first blade may be separated from a
remainder of said substrate using said first score.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is a continuation of, and claims
priority under 35 U.S.C. .sctn.120 to, U.S. patent application Ser.
No. 10/390,484, that is entitled "ALIGNMENT OF MICROKERATOME BLADE
TO BLADE HANDLE," and that was filed on Mar. 17, 2003; U.S. patent
application Ser. No. 10/390,357, that is entitled "MOUNTING A BLADE
HANDLE ON A MICROKERATOME BLADE", and that was filed on Mar. 17,
2003; U.S. patent application Ser. No. 10/390,353, that is entitled
"SEPARATING A MICROKERATOME BLADE FROM A WAFER", and that was filed
on Mar. 17, 2003; and U.S. patent application Ser. No. 10/390,488,
that is entitled "MULTI-FIXTURE ASSEMBLY OF CUTTING TOOLS", and
that was filed on Mar. 17, 2003. The entire disclosure of each of
the above-noted patent applications is incorporated by reference in
their entirety herein.
FIELD OF THE INVENTION
[0002] The present invention generally relates to the fabrication
of one or more cutting blades from an appropriate substrate and,
more particularly, to the use of a score to facilitate the
separation of these blades from a remainder of the substrate at the
appropriate time.
BACKGROUND OF THE INVENTION
[0003] Many types of blades exist for many types of applications.
Blades are used for cutting biological materials of various types
and for various applications. One application that is becoming
quite prevalent is the cutting of human eye tissue in relation to a
LASIK eye procedure. Here the blade is used in an automated
instrument that is commonly referred to as microkeratome or the
like. The blade is used to cut a thin protective layer of corneal
tissue from the patient's eye. Typically the cut is made such that
this tissue remains attached to the patient's eye, and thus it is
commonly referred to as a "flap." Positioning the flap away from
the underlying area (e.g., by a pivotal-like motion about the
remaining interconnection with the patient's eye) exposes the
desired portion of the patient's cornea. A laser is then used to
remove tissue from the patient's cornea or to otherwise "shape" the
cornea to address associated refractive errors. Thereafter the flap
is placed back in its original position. Within a few minutes the
flap reattaches to the patient's eye, without the use of
sutures.
[0004] Conventional microkeratome blades are stainless steel. There
are a number of issues with these types of blades. One is that the
blade edge is typically examined under a microscope before being
used in a LASIK procedure in an attempt to identify deficiencies in
the blade edge. Various discontinuities (e.g., burrs) may exist
along the blade edge based upon the way in which the blade edge is
formed (e.g., mechanical grinding, polishing) and the material from
which the blade is formed, as well as because of the vulnerability
of the cutting edge after being formed. Certain deficiencies
associated with the blade edge may adversely affect the performance
of the blade in cutting the eye flap for a LASIK procedure. Another
is that the blade edge of conventional stainless steel
microkeratome blades will typically degrade after cutting a single
eye flap. Nonetheless, a common practice is to use the same
microkeratome blade to cut a flap on both of the patient's eyes in
a single office visit where the LASIK procedure is performed on
each eye.
[0005] Most microkeratome blades are mounted on a blade handle,
that is in turn mounted on a head assembly of the microkeratome.
How the microkeratome blade is aligned to the blade handle can have
a significant impact on the blade's cutting performance when
installed on the microkeratome. Certain conventional stainless
steel microkeratome blades have a mark on a surface thereof where
the blade handle must be optically aligned therewith. Other
conventional stainless steel microkeratome blades have holes that
extend through the body of the blade. The corresponding blade
handle has pins that are disposed within these holes. How these
alignment marks or holes are formed on the cutting blade may have
an impact on the accuracy with which the cutting edge of the blade
is disposed relative to a reference surface of the blade handle.
This in turn will affect the accuracy of the positioning of the
blade's cutting edge when installed in the microkeratome.
[0006] Other types of microkeratome blades have been proposed. One
is diamond in which a crystal is typically cleaved to define a
cutting edge. Another is silicon. Both isotropic and anisotropic
etches have been suggested as options for fabricating a cutting
edge for a microkeratome blade or the like from a silicon wafer.
Notwithstanding the recognition of these various types of options
in the art, stainless steel microkeratome blades still dominate the
market. In fact, the inventors associated with the subject patent
application do not have knowledge of any silicon microkeratome
blade that is commercially available.
[0007] There are of course many other types of applications where a
blade is used to cut biological tissue (e.g., hand-held surgical
instruments, scalpels), as well as many other types of
non-biological cutting applications. One or more of these cutting
applications may benefit from the ability to effectively fabricate
cutting blades in a batch-type process using an anisotropic etch.
Certain cutting applications may benefit from the ability to more
accurately align the blade's cutting edge to an alignment surface
on a blade handle to which the blade is mounted. Still other
cutting applications may benefit from the ease with which a blade
angle may be selected for the desired application and then
fabricated using an anisotropic etch.
BRIEF SUMMARY OF THE INVENTION
[0008] A first aspect of the present invention generally relates to
using an etch to define at least part of at least one cutting blade
from a substrate, as well as to define at least one score on this
substrate for separating its corresponding blade(s) from the
substrate. More specifically, at least one cutting edge surface for
a first blade is defined by etching the substrate. Multiple cutting
edge surfaces may be formed in association with any particular
blade, each of which may have the characteristics of or relating to
a first cutting edge surface to be described herein in relation to
the first blade. It should be appreciated that multiple blades may
be formed from the same substrate as well, each of which may have
the characteristics of or relating to the first blade to be
described herein. At least one score that is associated with the
first blade is also defined by etching this same substrate
(hereafter a "first score", although multiple scores may be formed
in association with the first blade, and each of which may have the
characteristics of or relating to the first score to be described
herein). This first score may be used to facilitate the separation
of the first blade from the substrate at the appropriate time,
although this separation is not a requirement of the first
aspect.
[0009] Various refinements exist of the features noted in relation
to the first aspect of the present invention. Further features may
also be incorporated in the first aspect of the present invention
as well. These refinements and additional features may exist
individually or in any combination. Any suitable substrate may be
utilized by the first aspect, for instance a wafer that is
appropriate for use in semiconductor processing. Representative
suitable materials for the substrate include ceramic, silicon, and
quartz. Single crystal materials in general are desirable for the
substrate in the case of the first aspect (e.g., single crystal
silicon; single crystal quartz). Utilizing a single crystal
material for the substrate, where there is at least one etchant
that is selective to at least one crystal plane of the particular
single crystal material, allows for a desirable formation of the
first cutting edge surface that may define a cutting edge for the
first blade, as well as possibly other features of the first blade
(e.g., at least one registration feature for the first blade). That
is, those single crystal materials that may be etched to a
particular crystal plane, and have the etch in effect stop after
reaching this particular crystal plane, may be particularly suited
for use in the fabrication of the first blade in accordance with
the first aspect.
[0010] The first blade may remain part of or interconnected with
the substrate for some time after its first cutting edge surface is
defined by an etch in the case of the first aspect. For instance,
the substrate with this first blade as a part thereof may be
transferred from an etch bath to a first fixture to allow a first
blade handle to be attached to the first blade while still attached
to the substrate. The substrate may then be transferred from this
first fixture to a second fixture where the first blade may be
separated from the substrate. Separation again may utilize the
first score formed by an etch in accordance with the first aspect.
For instance, the substrate may be fractured at least generally
along the first score to facilitate the separation of the first
blade from the substrate.
[0011] The etching of the first cutting edge surface and the first
score in accordance with the first aspect may be executed at the
same time using a single etchant. In one embodiment, an anisotropic
etch is used. It should be appreciated that although the same etch
may be used, the time required to completely define each of the
various structures may not necessarily be the same. The
corresponding etch that defines the first cutting edge surface and
the first score each may be in the form of a chemical etch. The
same etch that defines the first cutting edge surface for the first
blade may also simultaneously define other aspects of or structure
associated with the first blade. For instance, this etch may define
a first cutting edge for the first blade that uses the first
cutting edge surface. In one embodiment, the first score is etched
so as to be parallel with this first cutting edge. The etch that
defines the first cutting edge surface for the first blade may also
define a first perimeter portion of the first blade (i.e.,
something less than the entire perimeter of the first blade, so
that it remains attached to the substrate at least at one location)
by etching through the entire vertical extent or thickness of the
substrate in accordance with a desired pattern.
[0012] At least one blade support tab that maintains a structural
interconnection between the first blade and the substrate
(hereafter a "first blade support tab", although multiple blade
support tabs may be formed in relation to the first blade, and each
of which may have the characteristics of or relating to the first
blade support tab to be described herein) may also be defined by an
etch in the case of the first aspect. A pair of spaced openings
that extend down through the entire vertical extent of thickness of
the substrate may be created by an etch to define this first blade
support tab. The corresponding etch that defines the first cutting
edge surface, the first score, and the first blade support tab may
be executed at the same time (although not necessarily of the same
duration) using a single etchant (e.g., by immersing the substrate
within an appropriate etch bath, with appropriate openings having
previously been formed in an etch mask that is on the substrate).
This etch may define the entire perimeter of the first blade except
where the first blade support tab merges into the first blade. The
remainder of the perimeter of the first blade may be defined by the
separation of the first blade from the substrate along the first
score formed on the first blade support tab.
[0013] The first score may be etched in the substrate so as to
extend across at least a portion of the above-noted first blade
support tab in accordance with the first aspect. In one embodiment,
the first score is disposed along the length dimension of the first
blade support tab at a location where the first blade support tab
is of its minimum width (e.g., so that the shape of the first blade
support tab acts as a stress concentrator, to cause the greatest
stress to occur at the location of the first score to further
facilitate the fracture). The first blade support tab may be shaped
to generate the greatest stress at the location of the first score
to further facilitate the fracture. In another embodiment, the
first score extends across only part of the first blade support tab
(e.g., the first score does not extend across the entire width of
the first blade support tab in this case). Preferably, the pair of
opposite ends of the first score (the distance between which
defines a length dimension for the first score) are each spaced
from one of the two sides or side edges of the first blade support
tab (the distance between the two sides defining the width
dimension of the first blade support tab). Another way to
characterize this first score is that it has a pair of ends that do
not intersect with any opening that extends completely through the
substrate. Openings that extend completely through the substrate
again may be used to define a portion of a perimeter of the first
blade and also may be used to define the first blade support
tab.
[0014] The first blade may have a pair of notches formed on a first
perimeter wall of the first blade (e.g., a wall that defines at
least part of the perimeter of the first blade) in the case of the
first aspect. This first perimeter wall may be disposed at any
appropriate location along the perimeter of the first blade. The
above-noted first blade support tab may merge into the first blade
at a location that is between this pair of notches. The first score
may be positioned at a location anywhere along a length dimension
of the first blade support tab, but the first score is preferably
offset from other portions of the first perimeter wall of the first
blade having these notches. Any jagged edges or the like that
remain after separating the first blade from the substrate using
the first score will then be recessed relative to other portions of
the first perimeter wall of the first blade. That is, when
disposing the first perimeter wall of the first blade on a flat
supporting surface, the surface defined by fracturing the first
blade support tab along the first score preferably will be spaced
from this supporting surface. Separating the first blade from the
substrate at least generally along the first score may then serve
to interconnect the noted pair of notches to define one larger
notch on the first perimeter wall of the first blade. The first
score may extend entirely through the substrate, but more
preferably only extends through a portion of the thickness of the
substrate in accordance with the first aspect. In one embodiment,
the first score is etched so as to have a depth that is within a
range of about 2% to about 75% of the thickness of the substrate.
In another embodiment, the first score is etched so as to have a
depth that is within a range of about 2% to about 5% of the
thickness of the substrate. In yet another embodiment, the first
score is etched so as to have a depth that is within a range of
about 10 microns to about 30 microns.
[0015] The first score that is etched in accordance with the first
aspect may be of any appropriate configuration, but is preferably
configured so as to allow the fracture to occur in an at least
generally predetermined manner. In one embodiment, the first score
is etched to produce first and second planar score surfaces that
intersect along a first line. The first planar score surface may be
parallel with the first cutting edge surface that is also defined
by an etch in accordance with the first aspect. Alignment of the
first score with a crystallographic plane of the substrate may
enhance the separation of the first blade from the remainder of the
substrate, including aligning the intersection of the above-noted
first and second planar score surfaces with such a crystallographic
plane.
[0016] The etching of the first cutting edge surface and the first
score in accordance with the first aspect may utilize an
appropriate etch mask or the like as generally noted above. In one
embodiment, a first masking layer is formed on the substrate. A
blade mask may then be transferred onto the first masking layer.
Appropriate openings may be defined in the first masking layer in
accordance with the blade mask to allow for the etching of the
substrate to define both the first cutting edge surface and the
first score. In one embodiment, the blade mask is transferred onto
the first masking layer using photomasking, masking,
photolithography, or microphotolithography, and openings in the
first masking layer are defined in accordance with the blade mask
by wet chemical etching, plasma etching, reactive ion etching, or
ion beam milling the first masking layer.
[0017] A second aspect of the present invention generally relates
to using an etch process to define at least part of at least one
cutting blade from a substrate (hereafter a "first blade" although
multiple cutting blades may be formed from the same substrate, and
each of which may have the characteristics of or relating to the
first blade to be described herein), to define at least one blade
support tab that maintains an interconnection between this first
blade and a remainder of the substrate (hereafter a "first blade
support tab", although multiple blade support tabs may be formed in
relation to the first blade, and each of which may have the
characteristics of or relating to the first blade support tab to be
described herein), and to define at least one score on this
substrate for facilitating the separation of the first blade from
the substrate(hereafter a "first score", although multiple scores
may be formed in relation to the blade support tab, and each of
which may have the characteristics of or relating to the first
score to be described herein). A first perimeter portion of the
first blade is defined by etching through the substrate. The first
blade support tab is also defined by etching through the substrate,
and functions to structurally interconnect the first blade with a
remainder of the substrate. The first score is etched across at
least a portion of the first blade support tab. This first score
may be used to facilitate the separation of the first blade from
the substrate at the appropriate time, although this separation is
not a requirement of the second aspect.
[0018] Various refinements exist of the features noted in relation
to the second aspect of the present invention. Further features may
also be incorporated in the second aspect of the present invention
as well. These refinements and additional features may exist
individually or in any combination. Any suitable substrate may be
utilized by the second aspect, for instance a wafer that is
appropriate for use in semiconductor processing. Representative
suitable materials for the substrate include ceramic, silicon, and
quartz. Single crystal materials in general are desirable for the
substrate in the case of the second aspect (e.g., single crystal
silicon; single crystal quartz). Utilizing a single crystal
material for the substrate, where there is at least one etchant
that is selective to at least one crystal plane of the particular
single crystal material, allows for a desirable formation of at
least one planar cutting edge surface that may define a cutting
edge for the first blade, as well as possibly other features of the
first blade (e.g., at least one registration feature for the first
blade). That is, those single crystal materials that may be etched
to a particular crystal plane, and have the etch in effect stop
after reaching this particular crystal plane, may be particularly
suited for use in the fabrication of the first blade in accordance
with the second aspect.
[0019] The first blade may remain part of or interconnected with
the substrate through the first blade support tab for some time
after being defined by an etch in the case of the second aspect.
For instance, the substrate with the first blade and first blade
support tab formed therefrom may be transferred from an etch bath
to a first fixture to allow a first blade handle to be attached to
the first blade while still attached to the substrate through the
first blade support tab. The substrate may then be transferred from
this first fixture to a second fixture where the first blade may be
separated from the first blade support tab, and thereby the
substrate. Separation again may utilize the first score formed by
an etch in accordance with the second aspect. For instance, the
substrate may be fractured at least generally along the first score
to facilitate the separation of the first blade from its
corresponding first blade support tab.
[0020] The first perimeter portion associated with the first blade
in the case of the second aspect may define the entire perimeter of
the first blade, except for that which is defined by separating the
first blade from the first blade support tab at least generally
along the first score. Consider the case where the first blade
support tab merges into the first blade along a portion of a
perimeter wall of the first blade (hereafter a "first perimeter
wall"). The remainder of the entire perimeter of the first blade
may be defined by an etch. Therefore, the first perimeter wall of
the first blade in this case will have two textures of sort--one
being defined by an etch and the other being defined by the
fracturing of the substrate at least generally along the first
score.
[0021] The etching of the first perimeter portion of the first
blade, the first blade support tab, and the first score in
accordance with the second aspect may be executed at the same time
using a single etchant (e.g., an anisotropic etch). For instance,
the substrate may be immersed in an appropriate etch bath, with
appropriate openings having previously been formed in an etch mask
that is on the substrate. It should be appreciated that although
the same etch may be used, the time required to completely define
each of the various structures may not necessarily be the same. The
corresponding etch that defines the first perimeter portion of the
first blade surface, the first blade support tab, and the first
score each may be in the form of a chemical etch. The same etch
that defines the first perimeter portion for the first blade may
also simultaneously define other aspects of or structure associated
with the first blade. For instance, this etch may define a first
cutting edge surface and a corresponding first cutting edge. In one
embodiment, the first score is etched so as to be parallel with
this first cutting edge.
[0022] The first score may be etched in the substrate so as to
extend across at least a portion of the first blade support tab in
accordance with the second aspect. In one embodiment, the first
score is disposed along the length dimension of the first blade
support tab at a location where the first blade support tab is of
its minimum width (e.g., so that the shape of the first blade
support tab acts as a stress concentrator, to cause the greatest
stress to occur at the location of the first score to further
facilitate the fracture). The first blade support tab may be shaped
to generate the greatest stress at the location of the first score
to further facilitate the fracture. In another embodiment, the
first score extends across only part of the first blade support tab
(e.g., the first score does not extend across the entire width of
the first blade support tab in this case). Preferably, the pair of
opposite ends of the first score (the distance between which
defines a length dimension for the first score) are each spaced
from one of the two sides or side edges of the first blade support
tab (the distance between the two sides defining the width
dimension of the first blade support tab). Another way to
characterize this first score is that it has a pair of ends that do
not intersect with any opening that extends completely through the
substrate. Openings that extend completely through the substrate
again may be used to define a portion of a perimeter of the first
blade and may be used to define the first blade support tab.
[0023] The first blade may have a pair of notches formed on a first
perimeter wall of the first blade (e.g., a wall that defines at
least part of the perimeter of the first blade) in the case of the
second aspect. This first perimeter wall may be disposed at any
appropriate location along the perimeter of the first blade. The
first blade support tab may merge into the first blade at a
location that is between this pair of notches. The first score may
be positioned at a location anywhere along a length dimension of
the first blade support tab, but the first score is preferably
offset from other portions of the first perimeter wall of the first
blade having these notches. Any jagged edges or the like that
remain after separating the first blade from the remainder of the
substrate using the first score will then be recessed relative
other portions of the first perimeter wall of the first blade. That
is, when disposing the first perimeter wall of the first blade on a
flat supporting surface, the surface defined by fracturing the
first blade support tab along the first score preferably will be
spaced from this supporting surface. Separating the first blade
from the substrate at least generally along the first score may
then serve to interconnect the noted pair of notches to define one
larger notch.
[0024] The first score may extend entirely through the substrate,
but more preferably only extends through a portion of the thickness
of the substrate in accordance with the second aspect. In one
embodiment, the first score is etched so as to have a depth that is
within a range of about 2% to about 75% of the thickness of the
substrate. In another embodiment, the first score is etched so as
to have a depth that is within a range of about 2% to about 5% of
the thickness of the substrate. In yet another embodiment, the
first score is etched so as to have a depth that is within a range
of about 10 microns to about 30 microns.
[0025] The first score that is etched in accordance with the second
aspect may be of any appropriate configuration, but is preferably
configured so as to allow the fracture to occur in an at least
generally predetermined manner. In one embodiment, the first score
is etched to produce first and second planar score surfaces that
intersect along a first line. The first planar score surface may be
parallel with a first cutting edge surface for the first blade that
also may be defined by an etch in accordance with the second
aspect. Alignment of the first score with a crystallographic plane
of the substrate may enhance the separation of the first blade from
the remainder of the substrate, including aligning the intersection
of the above-noted first and second planar score surfaces with such
a crystallographic plane.
[0026] The etching of the first perimeter portion of the first
blade, the first blade support tab, and the first score in
accordance with the second aspect may utilize an appropriate etch
mask or the like as generally noted above. In one embodiment, a
first masking layer is formed on the substrate. A blade mask may
then be transferred onto the first masking layer. Appropriate
openings may be defined in the first masking layer in accordance
with the blade mask to allow for the etching of the substrate to
define the first perimeter portion of the first blade, the first
blade support tab, and the first score. In one embodiment, the
blade mask is transferred onto the first masking layer using
photomasking, masking, photolithography, or microphotolithography,
and openings in the first masking layer are defined in accordance
with the blade mask by wet chemical etching, plasma etching,
reactive ion etching, or ion beam milling the first masking
layer.
[0027] A third aspect of the present invention generally relates to
the fabrication of at least one blade from a substrate (hereafter a
"first blade", although multiple blades may be formed from the same
substrate, and each of which may have the characteristics of or
relating to the first blade to be described herein). At least one
opening down through the entire vertical extent or thickness of
substrate is created. A continuous opening of this type may be in
accordance with a pattern that defines a first perimeter portion of
the first blade. That is, the entire perimeter of the first blade
is not initially defined in accordance with the third aspect. In
this regard, at least one score (hereafter a "first score",
although multiple scores may be formed in relation to the first
blade, and each of which may have the characteristics of or
relating to the first score to be described herein) is defined on
the substrate. This first score may be used to facilitate the
separation of the first blade from the substrate at the appropriate
time, although this separation is not a requirement of the third
aspect. The first score is defined such that its pair of ends do
not intersect with any opening.
[0028] Various refinements exist of the features noted in relation
to the third aspect of the present invention. Further features may
also be incorporated in the third aspect of the present invention
as well. These refinements and additional features may exist
individually or in any combination. Any opening of the type
utilized by the third aspect may be defined in any appropriate
manner. The first score associated with the third aspect also may
be defined in any appropriate manner. In a preferred embodiment, at
least one of these openings is defined by an etch, as is the first
score. The various features discussed above in relation to the
first and second aspects may be utilized by this third aspect,
individually or in any combination.
[0029] A fourth aspect of the present invention generally relates
to the fabrication of at least one blade from a substrate
(hereafter a "first blade", although multiple blades may be formed
from the same substrate, and each of which may have the
characteristics of or relating to the first blade to be described
herein). At least one opening down through the entire vertical
extent or thickness of substrate is created. A continuous opening
of this type may be in accordance with a pattern that defines a
first perimeter portion of the first blade. That is, the entire
perimeter of the first blade is not initially defined in accordance
with the fourth aspect. At least one score (hereafter a "first
score", although multiple scores may be formed in relation to the
first blade, and each of which may have the characteristics of or
relating to the first score to be described herein) is also defined
on the substrate. In one embodiment, the first score is formed
during the time that the opening(s) are being defined. Another
embodiment has the first score being defined by the same technique
that defines the opening(s). Yet another embodiment has this first
score recessed from an adjacent perimeter wall. In any case, the
first score may be used to facilitate this separation of the first
blade from the substrate at the appropriate time, although this
separation is not a requirement of the fourth aspect.
[0030] Various refinements exist of the features noted in relation
to the fourth aspect of the present invention. Further features may
also be incorporated in the fourth aspect of the present invention
as well. These refinements and additional features may exist
individually or in any combination. Any opening of the type
utilized by the fourth aspect may be defined in any appropriate
manner. The first score associated with the fourth aspect also may
be defined in any appropriate manner. In a preferred embodiment, at
least one of these openings is defined by an etch, as is the first
score. The various features discussed above in relation to the
first and second aspects may be utilized by this fourth aspect,
individually or in any combination.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0031] FIG. 1 is a side view of one embodiment of a
microkeratome.
[0032] FIG. 2A is a top-based perspective view of a cutting blade
of the cutting tool utilized by the microkeratome of FIG. 1.
[0033] FIG. 2B is a top view of the cutting blade of the cutting
tool utilized by the microkeratome of FIG. 1.
[0034] FIG. 2C is a plan view of a modified registration cavity
that may be used by the cutting blade of FIGS. 2A-B.
[0035] FIG. 3A is a cross-sectional view of the cutting blade of
FIG. 2B take along line 3-3.
[0036] FIG. 3B is a cross-sectional view of an alternative
embodiment of a cutting blade, namely in relation to the definition
of its cutting edge in relation to that illustrated in FIG. 3A.
[0037] FIG. 4 is a side-based perspective view of the cutting tool
utilized by the microkeratome of FIG. 1.
[0038] FIG. 5 is a top-based perspective view of the cutting tool
utilized by the microkeratome of FIG. 1.
[0039] FIG. 6 is a bottom-based perspective view of the cutting
tool utilized by the microkeratome of FIG. 1.
[0040] FIG. 7 is an exploded, perspective view of the cutting tool
utilized by the microkeratome of FIG. 1.
[0041] FIG. 8A is a cutaway, bottom view illustrating one
registrant of the blade handle of the cutting tool utilized by the
microkeratome of FIG. 1, while engaging a registration surface of
the cutting blade.
[0042] FIG. 8B is a cutaway, side view illustrating a registrant of
a blade handle of the cutting tool utilized by the microkeratome of
FIG. 1, while engaging a registration surface of the cutting
blade.
[0043] FIG. 8C is a cutaway, side view illustrating an alternative
embodiment of a registrant of the blade handle of the cutting tool
utilized by the microkeratome of FIG. 1, while engaging the
registration surface of the cutting blade.
[0044] FIG. 8D is a cutaway, side view illustrating yet another
alternative embodiment of a registrant of the blade handle of the
cutting tool utilized by the microkeratome of FIG. 1, while
engaging the registration surface of the cutting blade.
[0045] FIG. 9A is a cross-sectional view of a pair of masking
layers formed on opposing surfaces of a substrate or wafer.
[0046] FIG. 9B is a cross-sectional view after a cutting blade mask
has been transferred onto one of the masking layers of FIG. 9A,
along with the resulting openings in the masking layer.
[0047] FIG. 9C is a top plan view of the openings in the masking
layer illustrated in FIG. 9B
[0048] FIG. 9D is a cross-sectional view after the substrate/wafer
has been etched to define the cutting blade of the cutting tool
utilized by the microkeratome of FIG. 1.
[0049] FIG. 10 is a flowchart illustrating one method of
fabricating multiple blades from a wafer, including steps that
correspond with FIGS. 9A-D.
[0050] FIG. 11 is a plan view of a wafer with alignment slots
etched therein for aligning a blade mask relative to the wafer.
[0051] FIG. 12 is a plan view of a wafer having a plurality of
cutting blades fabricated therefrom in accordance with the protocol
of FIG. 10.
[0052] FIG. 13A is an enlarged, plan view of the interconnection
between a single cutting blade and the wafer from FIG. 12.
[0053] FIG. 13B is an enlarged, cutaway view of one embodiment of a
blade separation score that is only schematically illustrated in
FIG. 13A and which is used to separate the cutting blade from a
corresponding blade support tab of the wafer.
[0054] FIG. 13C is an enlarged, plan view of a portion of the rear
of the cutting blade of FIG. 13A after its separation from the
wafer along the score of FIG. 13B.
[0055] FIG. 13D is a plan view of a blade mask perimeter profile
and one embodiment of an actual perimeter profile produced when
anisotropically etching a wafer based upon this blade mask
perimeter profile.
[0056] FIG. 14 is a perspective view of one embodiment of a fixture
and base plate for installing blade handles on the cutting blades
from the wafer of FIG. 12.
[0057] FIG. 15 is an exploded, perspective view of the blade handle
mounting fixture and base plate of FIG. 14.
[0058] FIG. 16 is a perspective view of an upper surface of the
blade handle mounting fixture of FIG. 14.
[0059] FIG. 17 is a perspective view of a lower surface of the
blade handle mounting fixture of FIG. 14.
[0060] FIG. 18 is an enlarged, perspective view of a portion of the
upper surface of the blade handle mounting fixture of FIG. 14 that
would interface with one of the cutting blades.
[0061] FIG. 19 is an enlarged, perspective view of a portion of the
upper surface of the blade handle mounting fixture of FIG. 14 when
supporting one of the cutting blades.
[0062] FIG. 20 is a perspective view of one embodiment of a blade
separation fixture for separating blades from the wafer of FIG.
12.
[0063] FIG. 21 is an exploded perspective view of the blade
separation fixture of FIG. 20.
[0064] FIG. 22 is an enlarged perspective view of a portion of one
of the cutting edge cavities and one of the registrant/pivot
cavities used by the blade separation fixture of FIG. 20.
[0065] FIG. 23 is an enlarged perspective view of one of the
cutting tools from the wafer of FIG. 12 being positioned over the
cutting edge cavity and registrant/pivot cavity illustrated in FIG.
22.
DETAILED DESCRIPTION OF THE INVENTION
[0066] The present invention will now be described in relation to
the accompanying drawings which at least assist in illustrating its
various pertinent features. A schematic of one embodiment of a
microkeratome 4 that may be used to perform a LASIK procedure on a
patient's eye (not shown) is illustrated in FIG. 1. The
microkeratome 4 generally includes a head assembly 10 having a
presser 6, a cut flap receiver 8, and a cutting tool receiver 12
with a cutting tool 20 disposed therein. Generally, the presser 6
pushes down on the front of the patient's eye while the cutting
tool 20 is brought into engagement with and cuts a flap from the
patient's eye. Cutting operations generally entail moving the
cutting tool 20 in an appropriate manner relative to the patient's
eye (e.g., by oscillation of the cutting tool 20 relative to the
head assembly 10 in a direction that is parallel with a cutting
edge 80 associated with the cutting tool 20 (in and out of the page
in the view presented in FIG. 1), as well as by a movement of the
head assembly 10 in the direction of the arrow A). In any case, the
resulting eye flap (with a portion typically still remaining
attached to the patient) is then directed into the cut flap
receiver 8 formed in the head assembly 10 of the microkeratome
4.
[0067] There are two primary components of the cutting tool 20,
namely a blade handle 24 and a cutting blade 56. The cutting blade
56 includes the above-noted cutting edge 80. This cutting edge 80
is formed on its forward end. The blade handle 24 interfaces with
the cutting blade 56 so as to desirably align or register the
position of the cutting edge 80 of the blade 56 with a
microkeratome registration surface 28 of the blade handle 24 with
enhanced accuracy. This microkeratome registration surface 28 in
turn interfaces with a cutting tool registration surface 14
associated with the head assembly 10 of the microkeratome 4. More
specifically, the cutting tool 20 is disposed within a cutting tool
receiver 12 formed within the head assembly 10. A pair of support
surfaces 13 of the head assembly 10 engage corresponding portions
of a bottom surface 64 of the cutting blade 54 to "vertically"
support the cutting blade 54 (shown in slightly vertically spaced
relation in FIG. 1 for clarity), while other portions of this
bottom surface 64 of the cutting blade 54 are disposed and
maintained in spaced relation to the underlying portion of the head
assembly 10. Moreover, the microkeratome registration surface 28 of
the blade handle 24 engages the cutting tool registration surface
14 of the head assembly 10 of the microkeratome 4. Because the
position of the cutting edge 80 is registered relative to the
microkeratome registration surface 28 of the blade handle 24, and
because the position of the microkeratome registration surface 28
of the blade handle 24 is registered relative to the cutting tool
registration surface 14 of the head assembly 10 of the
microkeratome 4, the position of the cutting edge 80 of the blade
56 is likewise registered relative to this cutting tool
registration surface 14. Enhancing the accuracy of the positioning
of the cutting edge 80 for a LASIK procedure is of course very
desirable.
[0068] Additional views of the cutting blade 56 are presented in
FIGS. 2A-B and 3A. The cutting blade 56 includes a top wall or
surface 60 and a bottom wall or surface 64. A pair of side walls or
surfaces 68 of the cutting blade 56 are laterally spaced from a
central, longitudinal reference axis 58 associated with the cutting
blade 56. Herein, the term "laterally" spaced, extending, or the
like means being at least generally in or along a direction that is
perpendicular to the central, longitudinal reference axis 58 of the
blade 56. Longitudinally spaced from the cutting edge 80 of the
cutting blade 56 is a rear wall or surface 106. Herein, the term
"longitudinally" spaced, extending, or the like means being at
least generally in or along a direction that is collinear with or
parallel to the central, longitudinal reference axis 58 of the
blade 56. Both the side surfaces 68 and the rear surface 106 extend
between and interconnect the top surface 60 and bottom surface 64
of the blade 56. The distance between the top surface 60 and the
bottom surface 64 thereby defines a thickness of the cutting blade
56. In one embodiment, the thickness of the cutting blade 56 is
within a range of about 230 microns to about 250 microns.
[0069] The rear surface 106 of the blade 56 includes a notch or
recess 110 that is centrally disposed relative to the central,
longitudinal reference access 58. In this regard, the rear surface
106 includes what may be characterized as a pair of first sections
112, a second section 114 that is longitudinally spaced from the
first section 112 in the direction of the cutting edge 80, and a
pair of laterally spaced third sections 116 that interconnect the
second section 114 with one of the first sections 112. Generally,
the configuration of the rear surface 106 facilitates the removal
of the cutting blade 56 from a wafer from which a plurality of
cutting blades 56 may be fabricated in a batch process. This will
be discussed in more detail below.
[0070] In the illustrated embodiment of the cutting blade 56: 1)
each side surface 68 includes a first section 69 that extends
rearwardly from the cutting edge 80 perpendicularly thereto, as
well as a second section 70 that extends rearwardly from its
corresponding first section 69 and at least generally toward the
central, longitudinal reference axis 58; 2) the pair of first
sections 112 and the second section 114 associated with the notch
110 on the rear surface 106 are all parallel with the cutting edge
80; and 3) the pair of laterally spaced (relative to the central,
longitudinal reference axis 58) third sections 116 associated with
the notch 110 are parallel with the central, longitudinal reference
axis 58. Other configurations for the cutting blade 56 may be
appropriate depending upon the application, as well as other
configuration/orientatio- ns for the various parts thereof unless
otherwise noted herein as being required.
[0071] A planar first cutting edge surface 72 is disposed at an
angle relative to the top surface 60 of the blade 56 and intersects
with this top surface 60 at an upper edge 76. The first cutting
edge surface 72 extends between this upper edge 76 and the cutting
edge 80 of the cutting blade 56. In the illustrated embodiment, the
first cutting edge surface 72 also intersects with the bottom
surface 64 of the cutting blade 56. As such, that portion of the
bottom surface 64 of the cutting blade 56 that is adjacent to the
cutting edge 80 and intersects with the first cutting edge surface
72 may be characterized as a second cutting edge surface 66 for the
cutting blade 56. The first cutting edge surface 72 is disposed at
an angle .theta. (FIG. 3A) relative to the second cutting edge
surface 66, and this may be characterized as the blade angle
.theta.. Any appropriate blade angle .theta. may be utilized by the
cutting blade 56 and which may depend upon the application in which
the blade 56 is to be used. In one embodiment for the case of
biological applications (e.g., cutting tissue, such as a human
eye), the blade angle .theta. is preferably within a range of about
15.degree. to about 25.degree..
[0072] Other options exist for defining the cutting edge 80 and the
blade angle .theta. of the cutting blade 56. One example is
presented in FIG. 3B where the cutting edge 80' is defined by a
second cutting edge surface 66' that is disposed at an angle
relative to the bottom surface 64 of the blade 56' and that
intersects with the first cutting edge surface 72'. This of course
disposes the cutting edge 80' at what may be characterized as an
"intermediate elevation" between the elevation of the top surface
60 and the elevation of the bottom surface 64 of the cutting blade
56'.
[0073] Features are incorporated into the structure of the cutting
blade 56 for purposes of registering or aligning the cutting edge
80 to a particular position when installed on the microkeratome 4.
These same features are incorporated in each cutting blade 56 so
that the cutting edge 80 of each cutting tool 20 that is installed
in the microkeratome 4 is registered or aligned to the same
position, preferably within a tolerance of 25 microns. That is, the
variance of the position of the cutting edge 80 relative to the
desired position is no more than about 25 microns in any dimension
for each cutting tool 20 that may be installed in the microkeratome
4. This variation principally relates to the geometry of the blade
handle 24 and the adhesion of the blade handle 24 to the cutting
blade 56.
[0074] The cutting blade 56 includes a pair of registration
cavities 84 that interface or cooperate with the blade handle 24 in
a manner so as to register or align the cutting edge 80 to the
desired position when installed in the microkeratome 4. Any
appropriate number of registration cavities 84 may be utilized and
disposed in any appropriate position on the cutting blade 56.
However, utilizing a pair of registration cavities 84 in the
position of the illustrated embodiment provides a number of
advantages, including facilitating parallel orientation of the
blade handle 24 relative to the cutting edge 80 of the blade
56.
[0075] Both registration cavities 84 of the cutting blade 56 are
identical. Only one registration cavity 84 then need be described
herein. The registration cavity 84 extends through the entire
thickness of the cutting blade 56 in the illustrated embodiment,
although such may not be required for all applications that may
utilize the blade 56 or cutting tool 20. For instance, the
registration cavity 84 could be formed on the top surface 60 of the
blade 56 and extend down toward, but not to, the bottom surface 64.
However, preferably the "bottom" of the registration cavity 84
(more specifically a lower edge 102 of a registration wall or
surface 94 associated with the registration cavity 84) and the
cutting edge 80 are disposed at the same elevation or distance from
the top surface 60 (measured perpendicularly to the top surface
60). In any case, the registration cavity 84 may be characterized
as being at least generally concave or "upwardly open" in relation
to the top surface 60 of the cutting blade 56 (e.g., accessible
through the top surface 60 of the blade 56).
[0076] Each registration cavity 84 includes a front wall 92, a rear
wall or registration surface 94 that is longitudinally spaced from
the front wall 92, and a pair of laterally spaced side walls 88
that extend between and interconnect the front wall 92 with the
registration surface 94. Generally, the front wall 92 and side
walls 88 of the registration cavity 84 may be of any appropriate
shape/configuration/orientation, as it is the registration surface
94 that provides the desired registration in relation to the
cutting edge 80. How far the registration surface 94 and the
corresponding front wall 92 should be longitudinally spaced
(represented by distance "S" in FIG. 8B) is at least by a distance
that would allow the blade handle 24 to first be installed on the
cutting blade 56, and then moved parallel with the top surface 60
of the cutting blade 56 to register or align the blade handle 24
relative to the cutting blade 56 using the registration surface(s)
94. The spacing between the side walls 88 of the registration
cavities 84 may provide a "lateral" registration feature for the
blade handle 24 relative to the cutting blade 56 as will be
discussed in more detail below.
[0077] Registration or alignment of the cutting edge 80 relative to
the microkeratome registration surface 28 of the blade handle 24,
and thereby relative to the cutting tool registration surface 14 of
the head assembly 10 of the microkeratome 4, is provided in the
case of the cutting blade 56 by having the registration surface 94
be a planar surface that is parallel with the planar first cutting
edge surface 72. That is, the registration surface 94 of each
registration cavity 84 utilized by the cutting blade 56 is a planar
surface that extends from an upper edge 98 (at the intersection
with the top surface 60 in the illustrated embodiment) to a lower
edge 102 (at the intersection with the bottom surface 64 in the
illustrated embodiment) in the same orientation that the planar
first cutting edge surface 72 extends from its upper edge 76 to the
cutting edge 80. The lower edge 102 of each registration cavity 84
is parallel with the cutting edge 80. In the illustrated
embodiment, the upper edge 76 of the first cutting edge surface 72
and the upper edge 98 of each registration surface 94 are disposed
within a first reference plane that is parallel with a second
reference plane, that in turn contains the cutting edge 80
associated with the first cutting edge surface 72 and the lower
edge 102 of each registration surface 94 (and parallel with the top
surface 60 and bottom surface 64 of the blade 56 for that matter).
Moreover, the pair of registration surfaces 94 of the registration
cavities 84 are disposed within a common reference plane. As such,
the registration cavities 84 are disposed equidistantly from the
cutting edge 80, as are their corresponding registration surfaces
94.
[0078] One preferable way to fabricate the cutting blade 56 is by
using an anisotropic etch, at least for purposes of defining the
first cutting edge surface 72 and the registration surface 94 of
each registration cavity 84. Preferably the entire cutting blade 56
is defined by a single anisotropic etch. This allows the various
structures to be very precisely positioned. For instance, the
registration cavities 84 may be very precisely positioned relative
to the cutting edge 80. The maximum variation in the location of
the cutting edge 80 relative to the lower edge 102 of each
registration cavity is about 6 microns. This variation may be
influenced by a number of factors. Referring to FIG. 2A, the upper
edge 76 of the first cutting edge surface 72 and the upper edge 98
of each registration cavity 84 are formed to within a tolerance of
1 micron or better. This is due to the fact that they may be
defined using the same photolithographic mask as will be discussed
in more detail below in relation to FIGS. 9A-D and FIG. 10. FIGS.
9A-D and FIG. 10 are specifically directed to the fabrication of
the cutting blade 56. Any variation in the location of the first
cutting edge surface 72 relative to the registration surface 94 of
each registration cavity 84 would be due to errors in the position
of one or more of the upper edge 76 of the first cutting edge
surface 72 and the upper edge 98 of each registration cavity 84,
coupled with errors associated with the etch process. However, any
variation in the location of the first cutting edge surface 72
relative to the registration surface 94 of each registration cavity
84 should be no more than about 2 microns. This in turn will then
influence the location of the cutting edge 80 relative to the lower
edge 102 of each registration cavity 84, as will the geometry of
the planes that intersect to form the edges 80, 76, 98, and 102.
Once again, the maximum variation between the location of the
cutting edge 80 relative to the lower edge 102 of each registration
cavity 84 should be no more than about 6 microns for a blade angle
.theta. of 19 degrees that will be discussed in more detail below
(e.g., 2 microns, divided by the sine of 19 degrees).
[0079] It should be appreciated that the structure of the blade 56
set forth herein is "idealized" in accordance with its
corresponding blade mask as noted above, and therefore that the
resulting shape of the various components of the blade 56 may not
conform exactly to the illustrations provided herein. For instance,
FIGS. 2A-B illustrate the shape of the registration cavities 84 in
accordance with the blade mask. The anisotropic etch may actually
produce a profile that is illustrated in FIG. 2C, where a "single
prime" designation again is used to identify an alternative
configuration for the registration cavity 84' (along with its
corresponding upper edge 98', registration surface 94', lower edge
102', side walls 88', and front wall 92').
[0080] There are a number of features of the cutting blade 56 that
accommodate or relate in at least some manner to using an
anisotropic etch fabrication technique for the blade 56. One that
is key in relation to the above-described registration feature is
that the first cutting edge surface 72 and the registration surface
94 of each registration cavity 84 should be coplanar or parallel
with a common crystal plane that the selected anisotropic etchant
will etch to, but not through. In one embodiment where the
anisotropic etchant is KOH and where the cutting blade 56 is etched
from single crystal silicon, the first cutting edge surface 72 and
the registration surface 94 of each registration cavity 84 are
coplanar or parallel with a plane in the {111} family of planes
(which includes both the positive and negative intercepts). That
is, a plane within the {111} family of planes in effect is an etch
stop for the anisotropic etch. Other crystal planes could be
selected for the first cutting edge surface 72 and the registration
surface 94 of each registration cavity 84. However, an appropriate
anisotropic etchant must of course be selected for the material
being etched and the crystal plane that is to be used to define the
orientation of the first cutting edge surface 72 and the
registration surface 94 of each registration cavity 84 in the
described manner.
[0081] Both the top surface 60 and the bottom surface 64 of the
cutting blade 56 should be planar surfaces, including for purposes
of accommodating using an anisotropic etchant to define the first
cutting edge surface 72 and the registration surface 94 of each
registration cavity 84. Flexibility in relation to the definition
of the cutting edge 80, more specifically in relation to its
associated blade angle .theta. (FIG. 3A), may be realized by
forming the top surface 60 and bottom surface 64 of the cutting
blade 56 in a certain manner. At least one Miller index of the set
of three Miller indices that define the top surface 60 and the
bottom surface 64 of the cutting blade 56 should have an absolute
value greater than "3" and be within the family of planes defined
by the set of three Miller indices {ABC}, where "A", "B", and "C"
each represent one Miller index, where at least one of the three
indexes has an absolute value greater than "3", and where "A", "B",
and "C" each include both the positive and negative intercepts.
[0082] Each of the side surfaces 68 of the cutting blade 56, the
front wall 92 and pair of side walls 88 of each registration cavity
84, and the rear surface 106 of the cutting blade 56 may be of any
orientation relative to the top surface 60 and bottom surface 64 of
the blade 56. In one embodiment and for the case where the cutting
blade 56 is fabricated from single crystal silicon: the front wall
92 of each registration cavity 84 and the rear surface 106 of the
cutting blade 56 are both perpendicular to the top surface 60 and
bottom surface 64 of the blade 56, and further are coplanar with or
parallel with a crystal plane in the {111} family of planes
(including both the positive and negative intercepts); and the side
surfaces 68 of the cutting blade 56 and the side walls 88 of each
registration cavity 84 are not perpendicular to the top surface 60
and bottom surface 64 of the blade 56, and are not necessarily
coplanar with a crystal plane in the {111} family of planes
(including both the positive and negative intercepts).
[0083] Cooperation between the cutting blade 56 and the blade
handle 24 of the cutting tool 20 is at least one component of
registering or aligning the cutting blade 56 in a desired position
relative to a patient when installed in the microkeratome 4, more
specifically its cutting edge 80. Various features of the blade
handle 24 are presented in FIGS. 4-7 for the case of the
configuration of the head assembly 10 utilized by the microkeratome
4 of FIG. 1. It should be appreciated that other configurations for
the blade handle 24 may be required for different applications of
the cutting blade 56, different types of microkeratomes 4, or
different head assemblies. Moreover, not all applications of the
cutting blade 56 will necessarily require an "intermediate" blade
handle.
[0084] The blade handle 24 is attached or anchored to the cutting
blade 56 so that there is no substantial movement therebetween.
Stated another way, the blade handle 24 and the cutting blade 56
function as a single unit and move together during operation of the
microkeratome 4. Any appropriate way of maintaining the blade
handle 24 in a fixed relative positional relationship with the
cutting blade 56 may be used, including any appropriate adhesive
(e.g., an epoxy; a UV curable epoxy; an epoxy with spacing
spheres), or by deforming some portion of the handle 24 by melting
or heat-staking.
[0085] Features may be incorporated into the structure of the blade
handle 24 for interfacing with the head assembly 10 of the
microkeratome 4 or otherwise. The blade handle 24 includes a pair
of laterally spaced guide rails 52 in the illustrated embodiment
that are disposed along a portion of the side surfaces 68 of the
cutting blade 56 (more specifically the second sections 70) when
the blade handle 24 is mounted on the cutting blade 56. In one
embodiment, the surface 54 of each of the guide rail 52 that
projects toward the corresponding portion of the side surface 68 of
the cutting blade 56 is planar and disposed in parallel relation
with the corresponding portion of the side surface 68 of the
cutting blade 56. Other profiles may be appropriate. There may be a
space between at least a portion of this surface 54 of the guide
rails 52 and their corresponding side surface 68 when the blade
handle 24 is registered or aligned with the cutting blade 56.
[0086] Registration or alignment of the cutting edge 80 of the
cutting blade 56 in the desired position in the microkeratome 4
utilizes the microkeratome registration surface 28 of the blade
handle 24. This microkeratome registration surface 28 again
interfaces with the cutting tool registration surface 14 on the
head assembly 10 of the microkeratome 4. Although the cutting tool
registration surface 14 is disposed on the "foreword" end of the
blade handle 24, it may be disposed in any appropriate position so
as to cooperate with a corresponding registration surface on the
head assembly 10 of the microkeratome 4.
[0087] Multiple features of the blade handle 24 relate in at least
some manner to the accurate positioning of the cutting edge 80 of
the cutting blade 56 relative to the blade handle 24, more
specifically its microkeratome registration surface 28. One is a
planar bottom surface 48 of the blade handle 24 that interfaces
with the planar top surface 60 of the cutting blade 56. This
provides what may be characterized as a "vertical" registration
feature between the blade handle 24 and cutting blade 56. Both a
lateral and a longitudinal or "fore/aft" registration feature
between the blade handle 24 and the cutting blade 56 may be
provided by the blade handle 24 including at least one registrant
32. Each registrant 32 extends or projects at least generally
downwardly from the planar bottom surface 48 of the blade handle
24. A pair of registrants 32 are utilized by the blade handle 24 in
the illustrated embodiment, one for each registration cavity 84 of
the cutting blade 56. These registrants 32 are disposed along a
common line that is parallel with the cutting edge 80 of the blade
56 when the blade 56 is properly registered to the blade handle
24.
[0088] Each registrant 32 includes a peripheral wall 36 that
intersects with a bottom wall 40. Four side walls or surfaces 37a-d
(FIGS. 8A-B) define the peripheral wall 36 in the illustrated
embodiment, with the side walls 37a and 37c being parallel with
each other, and with the side walls 37b and 37d being parallel with
each other. In the illustrated embodiment, the bottom wall 40 is
rectangular. These four side walls 37a-d of the peripheral wall 36
of each registrant 32 are disposed perpendicular to the bottom
surface 48 of the blade handle 24 in the illustrated embodiment.
Lateral registration of the blade handle 24 relative to the cutting
blade 56 may be provided by the having the side walls 37b and 37d
of each registrant 32 be spaced apart the same distance as the side
walls 88 of the corresponding registration cavity 84 in which the
registrant 32 is disposed. This will then dispose the side walls
37b, 37d of a given registrant 32 in interfacing or at least
closely spaced relation with the corresponding side wall 88 of the
corresponding registration cavity 84. Other
configurations/orientations of the peripheral wall 36 for each
registrant 32 may be appropriate and provide at least a degree of
lateral registration. Longitudinal registration of the blade handle
24 to the cutting blade 56 is provided by cooperation between each
registrant 32 and its corresponding registration surface 94, namely
that which is associated with the registration cavity 84 in which
the registrant 32 is disposed.
[0089] Mounting the blade handle 24 on the cutting blade 56 may
generally entail disposing an appropriate adhesive on at least one
of the top surface 60 of the cutting blade 56 and the bottom
surface 48 of the blade handle 24. A light curable epoxy is a
particularly desirable way to attach the blade handle 24 to the
cutting blade 56. Each registrant 32 on the bottom surface 48 of
the blade handle 24 is then disposed within its corresponding
registration cavity 84 on the cutting blade 56. Although only
relative movement is required, in one embodiment the blade handle
24 is advanced toward a stationary cutting blade 56. In any case,
preferably the registrants 32 are initially disposed within the
corresponding registration cavity 84 so as to not contact its rear
wall or registration surface 94. This may be utilized to seat the
planar bottom surface 48 of the blade handle 24 on the planar top
surface 60 of the cutting blade 56. The cutting blade 56 is now
supporting the blade handle 24 by itself. The blade handle 24 may
then be moved relative to the cutting blade 56 so as to increase
the spacing between the microkeratome registration surface 28 of
the blade handle 24 and the cutting edge 80 of the cutting blade
56, or stated another way so as to increase the spacing "S" between
the registrant 32 of the blade handle 24 and the front wall 92 of
its corresponding registration cavity 84 on the blade 56.
Preferably, the bottom surface 48 of the blade handle 24 is
maintained in interfacing relation with the top surface 60 of the
cutting blade 56 during this movement. Stated another way, the
noted relative movement between the blade handle 24 and cutting
blade 56 is in a direction that is at least generally parallel with
the top surface 60 of the cutting blade 56 and the bottom surface
48 of the blade handle 24. The blade handle 24 is moved relative to
the cutting blade 56 in this manner until each registrant 32
cooperates with its corresponding registration surface 94, more
typically a portion thereof. This then registers or aligns the
cutting edge 80 of the cutting blade 56 relative to the
microkeratome registration surface 28 of the blade handle 24, which
in turn registers or aligns the cutting edge 80 of the cutting
blade 56 in a desired position within the microkeratome 4. In one
embodiment, each registrant 32 is separated from its corresponding
front wall 92 by a distance of at least about 1 millimeter when the
registrant 32 is interfacing with its corresponding registration
surface 94.
[0090] The blade handle 24 is fixed to the cutting blade 56 when in
the above-noted registered position. This emphasizes the
desirability of using a light curable epoxy, including a UV curable
epoxy. That is, a light curable epoxy allows the blade handle 24 to
be mounted on the blade 56 in the above-noted manner so as to
register the position of the blade handle 24 relative to the
cutting blade 56 before the light curable epoxy sets. An
appropriate light source (e.g., UV) may then be directed at the
light curable epoxy to cure the same (in less than 10 seconds in
the case of at least certain UV curable epoxies) and thereby fix
the position of the blade holder 24 relative to the cutting blade
56. Having the position of the cutting edge 80 of the blade 56
registered relative to the microkeratome registration surface 28 of
the blade handle 24 registers the position of the cutting edge 80
when installed in the microkeratome 4. Once again, the
microkeratome registration surface 28 of the blade handle 24 is
registered or aligned relative to the cutting tool registration
surface 14 of the head assembly 10 of the microkeratome 4.
[0091] Any appropriate cooperation between a given registrant 32 of
the blade handle 24 and its corresponding registration surface 94
of the cutting blade 56 may be utilized that provides the desired
registration or alignment of the cutting edge 80 of the cutting
blade 56 relative to the microkeratome registration surface 28 of
the blade handle 24 in the longitudinal or fore-aft dimension. In
one embodiment, the contact between a registrant 32 and its
corresponding registration surface 94 is limited to being at least
generally along a line. Stated another way, the interface between a
given registrant 32 and its corresponding registration surface 94
is limited to a "line contact" in one embodiment. This may be
provided in any number of manners. Three options are illustrated in
FIGS. 8B-D. FIG. 8B illustrates that the registrant 32 actually
extends below the bottom surface 64 of the cutting blade 56, such
that the lower edge 102 of the registration surface 94 engages a
portion of the peripheral wall 36 of the registrant 32, namely the
side wall 37c. FIG. 8C illustrates that the lower edge 102 of the
registration surface 94 engages a registrant 32' of the blade
handle 24' at least generally at the intersection between the
peripheral wall 36 and the bottom wall 40 of the registrant 32.
FIG. 8D illustrates that the intersection between the peripheral
wall 36 and the bottom wall 40 of the registrant 32 engages its
corresponding registration surface 94 somewhere between the lower
edge 102 of the registration surface 94 and the upper edge 98 of
this registration surface 94. Preferably, the registrant 32
interfaces with its corresponding registration surface 94 closer to
the lower edge 102 than its upper edge 98, and including at the
intersection between the bottom surface 64 of the blade 56 and the
corresponding registration surface 94.
[0092] Standard semiconductor processing techniques may be utilized
to fabricate the cutting blade 56 of the cutting tool 20. One
significant advantage of using this technique is the accuracy with
which the cutting blade 56 may be fabricated, particularly the
accuracy of the position of the cutting edge 80 relative to the
position of the registration surface 94 of each registration cavity
84 of the cutting blade 56. FIGS. 9A-D illustrate a number of steps
in one method by which the cutting blade 56 may be fabricated using
standard semiconductor processing techniques. Initially, a suitable
material is selected for the fabrication of the cutting blade 56.
Suitable materials for fabrication of the cutting blade 56 using
the process described herein include without limitation single
crystal silicon, single crystal quartz, and potentially other
single crystal material having suitable crystal-plane selective
etchants. Those materials that are suitable for fabrication of the
cutting blade 56 generally are those that may be etched so that the
etch will stop at a predetermined place/position within the
material (e.g., at a particular crystal plane within the same
material, that in effect acts as an etch stop), and further where
the same etch behavior exists regardless of the location of the
opening in the mask being utilized for the etch. Regarding the
latter characterization, the material must be such that a
particular etchant will behave the same anywhere within the
material that is to be etched. It is really the combination of the
material and the selected etchant that allows the etchant to
anisotropically etch the material in the desired manner to define
the cutting blade 56.
[0093] The material from which the cutting blade 56 is fabricated
in accordance with FIGS. 9A-D generally may be characterized as a
substrate 130, and will more typically be in the form of a wafer
130. It should be appreciated that wafers that are "commonly
available" for the fabrication of semiconductor devices (e.g.,
silicon wafers having top and bottom surfaces parallel with either
the (110) and (100) crystal planes) may not be suitable in relation
to defining the desired blade angle .theta. for one or more
applications of the cutting blade 56. In any case, masking layers
118, 126 are defined on an upper surface 134 and a lower surface
138, respectively, of the wafer 130 using conventional
semiconductor processing techniques. This is illustrated in FIG.
9A. The masking layers 118, 126 may be formed on the corresponding
surface 134, 138 of the wafer 130 in any appropriate manner (e.g.,
chemical vapor deposition, physical vapor deposition, or thermal
growth in the case of silicon dioxide on silicon). Any material
that may be patterned for a subsequent selective etching of the
wafer 130 may be utilized by the masking layers 118, 126 (e.g.,
silicon nitride, silicon oxide).
[0094] What may be characterized as a blade mask is transferred
onto the upper masking layer 118 in a manner known in the art for
purposes of defining the cutting blade 56 and as illustrated in
FIGS. 9B-C. Multiple masking layer openings or apertures 122a-c are
formed on the upper masking layer 118 to define each cutting blade
56 that is to be fabricated from the wafer 130. These masking layer
apertures 122a-c extend entirely through the upper masking layer
118 to expose desired, selective portions of the upper surface 134
of the wafer 130. Any appropriate technique may be utilized for
transferring the blade mask onto the upper masking layer 118,
including, photomasking, masking, photolithography,
microlithography, which is then followed by a suitable technique of
etching the pattern into the upper masking layer 118 by means of
wet chemical etching, plasma etching, reactive ion etching, or ion
beam milling. The creation of the hard mask can also be
accomplished using a dual step process of using the photoresist to
define the pattern into an intermediate layer of silicon dioxide.
Once the photoresist is stripped, the silicon dioxide is then used
as an etch mask layer to define the silicon nitride by means of hot
phosphoric acid.
[0095] The masking layer aperture 122a is sized and configured to
define the first cutting edge surface 72 of the cutting blade 56
and the perimeter of the cutting blade 56 (the cutting edge 80,
side surfaces 68, and rear surface 106). Each masking layer
aperture 122b is "interiorly" disposed (inwardly of what will
ultimately be the perimeter of the cutting blade 56) and is sized
and configured to define a registration cavity 84 for the cutting
blade 56. A masking layer aperture 122c is also formed through the
upper masking layer 118 to define a score or score line within the
wafer 130 to facilitate the removal of the cutting blade 56 from
the wafer 130 after the blade 56 has been fabricated by an
anisotropic etch (identified by reference numeral 132 in FIGS. 12
and 13A). This score need not, but may, pass through the entire
vertical extent of the wafer 130.
[0096] No portion of the lower surface 138 of the wafer 130 needs
to be patterned to fabricate the cutting blade 56 from the wafer
130. As such, no portion of the lower surface 138 needs to be
exposed to an etchant for the fabrication of the cutting blade 56.
However, a masking layer opening or aperture would be formed in the
lower masking layer 126 in order to define the second cutting edge
surface 66' of the cutting blade 56' of FIG. 3B.
[0097] After the upper masking layer 118 (and lower masking layer
126 if required by the desired cutting edge configuration) has been
processed to define the desired configuration for the cutting blade
56 and the various individual surfaces thereof, the wafer 130 is
exposed to a suitable etchant. One way to execute the desired
etching operation is to dispose the wafer 130 in an etchant bath.
In any case, those portions of the upper surface 134 of the wafer
130 that are exposed to the etchant will have material removed to
define the configuration illustrated in FIG. 9D, which corresponds
with the cutting blade 56. The etchant simultaneously defines the
first cutting edge surface 72 and the registration surface 94 of
each registration cavity 84 utilized by the blade 56, and also
defines the perimeter of the cutting blade 56. A small portion of
the cutting blade 56 remains attached to the wafer 130 in the form
of a blade support tab at this time (see FIG. 12 to be discussed
below, where this blade support tab is identified by reference
numeral 131). This blade support tab is disposed under the portion
of the upper mask 118 identified by reference numeral 119 in FIG.
9C. The etchant also etches are least partially through the wafer
130 through the mask aperture 122c to define a score (see FIG. 12
to be discussed below, where this score is identified by reference
numeral 132). Generally, the cutting blade 56 is thereafter
separated from the remainder of the wafer 130 by fracturing or
breaking the wafer 130 along this score.
[0098] As noted above, an anisotropic etchant is utilized to
fabricate the cutting blade 56. The anisotropic etchant
simultaneously forms the first cutting edge surface 72 and the
registration surface 94 of each registration cavity 84 as planar,
parallel surfaces. This is done by selecting an anisotropic etchant
that will in effect stop etching when reaching a certain crystal
plane that defines the desired orientation for the first cutting
edge surface 72 relative to the top surface 60 of the cutting blade
56. Generally, the material defining the wafer 130 and the selected
etchant must be such that the behavior of the etchant is the same,
regardless of the location of any mask aperture in the upper
masking layer 118 (or the lower masking layer 126 for that matter).
For the case of the wafer 130 being single crystal silicon and the
first cutting edge surface 72 and the registration surface 94 of
each registration cavity 84 being parallel with a {111} crystal
plane, an appropriate anisotropic etchant for simultaneously
defining the first cutting edge surface 72 and each registration
surface 94 is KOH. That is, the KOH etchant will etch to, but not
through, the first (111) crystal plane that is disposed under the
edge of the upper masking layer 118 (corresponding with the upper
edge 76 and the upper edge 98).
[0099] Fabricating the cutting blade 56 in the above-noted manner
provides a number of advantages. Initially, the position of the
cutting edge 80 relative to the position of each registration
surface 94 can be done with a very high degree of accuracy due to
the high degree of accuracy with which mask apertures can be formed
in a mask in accordance with the foregoing. Moreover, the first
cutting edge surface 72 is simultaneously formed with the
registration surface 94 of each registration cavity 84, and this is
done so that the cutting edge surface 72 and the registration
surface 94 of each registration cavity 84 are disposed in parallel
relation to a high degree of accuracy. As noted above, the
anisotropic etch will proceed to the same exact crystal plane when
defining each of the first cutting edge surface 72 and the
registration surface 94 of each registration cavity 84. The etch
will then have the same effect on both the first cutting edge
surface 76 and the registration surface 94 of each registration
cavity 84. Each of these factors contributes to being able to
enhance the precision with which the cutting edge 80 of the blade
56 is disposed relative to a particular structure.
[0100] FIG. 10 depicts one embodiment of a protocol 140 for
fabricating one or more cutting blades 56 from the wafer 130. This
protocol 140 utilizes the basic steps/results that are illustrated
in FIGS. 9A-D. Step 142 of the protocol 140 is directed to forming
a masking layer on a wafer (e.g., wafer 130). In the illustrated
embodiment, what is commonly referred to in the art as a "hard
mask" will ultimately be formed from this particular masking layer.
Silicon nitride is used for the masking layer by step 142, although
other materials may be appropriate. Any appropriate way of forming
the silicon nitride masking layer on the wafer may be utilized by
step 142.
[0101] A first photoresist layer is formed on the silicon nitride
masking layer in accordance with step 146 of the protocol 140.
Either a positive-acting or negative-acting photoresist material
may be used by step 146. Any appropriate way of forming the first
photoresist layer on the silicon nitride masking layer may be
utilized by step 146. What may be characterized as an alignment
slot mask is then transferred onto the first photoresist layer
through execution of step 150. Generally, this alignment slot mask
is used to define certain structures on the wafer to thereafter
align what may be characterized as a "blade mask" to the wafer in a
certain manner, more specifically to align the blade mask to a
certain crystal orientation associated with the wafer. This "blade
mask" is that which has a layout of masking layer openings
extending therethrough such that selected portions of the wafer
will be etched in a manner so as to simultaneously fabricate/define
a plurality of cutting blades 56.
[0102] Step 154 of the protocol 140 indicates that the first
photoresist layer is developed in accordance with the alignment
slot mask to create a plurality of openings that extend completely
through the first photoresist layer in a layout that will be
discussed in more detail below in relation to FIG. 11. "Developing"
the first photoresist layer includes both exposing portions of the
first photoresist layer to an appropriate type of light (either
that portion of the first photoresist material that is to be
removed in the case of a positive-acting photoresist material, or
that portion of the first photoresist layer that is to remain in
the case of a negative-acting photoresist material), and thereafter
exposing the "light treated" first photoresist layer to an
appropriate developer to remove portions of the first photoresist
layer in accordance with the alignment slot mask. Openings in
accordance with the desired/required layout are formed through the
entire vertical extent of the first photoresist layer to expose the
underlying silicon nitride masking layer.
[0103] Appropriate openings are next etched through the entire
vertical extent of the silicon nitride masking layer in accordance
with step 158 of the protocol 140. The layout of these openings is
in accordance with the openings in the first photoresist layer, and
thereby in accordance with the alignment slot mask. In one
embodiment, a reactive ion etch is used to define the openings in
the silicon nitride masking layer in the layout required by the
alignment slot mask. Other types of etches may be appropriate. In
any case, this then exposes selected portions of the upper surface
of the underlying wafer. The first photoresist layer is then
stripped (step 162) from the now patterned silicon nitride masking
layer, and another etch is initiated to form alignment slots that
extend within, but typically not through, the wafer. In one
embodiment, the etch from step 166 of the protocol 140 is a KOH
etch. Other etches may be appropriate. The etch from step 166
reaches the wafer through the openings in the silicon nitride
masking layer associated with step 158 of the protocol 140, and
thereby in accordance with the alignment slot mask of step 150.
[0104] The alignment slots on the wafer formed in accordance with
steps 146-166 of the protocol 140 are analyzed to determine which
alignment slot(s) is suitably aligned with a particular crystal
orientation associated with the wafer. This is represented by step
170 of the protocol 140 of FIG. 10. The alignment slot(s) that are
aligned with a particular crystal orientation associated with the
wafer are then identified (step 174 of the protocol 140) for
subsequent use in aligning/orienting the blade mask to the
wafer.
[0105] FIG. 11 illustrates one way in which the alignment slots
referred to by the protocol 140 of FIG. 10 may be formed on the
wafer 130 to orient the blade mask relative to the wafer 130. The
wafer 130 includes a flat 206 that is disposed at the 6:00 o'clock
position. A reference axis 218 extends from the 3:00 o'clock
position to the 9:00 o'clock position, through a center 212 of the
wafer 130. Generally, a plurality of alignment slots 210a-k are
formed on one side of the wafer 130, while a plurality of alignment
slots 214a-k are formed on an opposite side of the wafer 130. Any
number of alignment slots 210a-k, 214a-k may be utilized. The
alignment slot 210a corresponds with the alignment slot 214a, the
alignment slot 210b corresponds with the alignment slot 214b, and
so forth. Corresponding alignment slots 210a-k/214a-k are disposed
along a common axis that extends through the center 212 of the
wafer 130. That is, the alignment slots 210a, 214a are positioned
along a common axis that extends through the center 212 of the
wafer 130, the alignment slots 210b, 214b are positioned along a
common axis that extends through the center 212 of the wafer 130,
and so forth. The axes along which corresponding slots 210a-k,
214a-k are disposed are preferably equally spaced about the center
212 of the wafer 130. That is, the axis along which the alignment
slots 210b, 214b are disposed is rotated counterclockwise a
predetermined amount from the axis along which the slots 210a, 214a
are disposed, the axis along which the alignment slots 210c, 214c
are disposed is rotated counterclockwise this same predetermined
amount from the axis along which the slots 210b, 212b are disposed,
and so forth.
[0106] The alignment slots 210a-k, the alignment slots 214a-k, or
both may be analyzed to identify which corresponding pair of
alignment slots (e.g., (210a, 214a); (210b, 214b); (210c; 214c),
etc) may be used to align the blade mask to the wafer 130 for
purposes of step 182 of the protocol 140 of FIG. 10. This analysis
may be done in any appropriate manner, including optically. This
analysis is undertaken pursuant to step 170 of the protocol 140 of
FIG. 10 that was discussed above. Generally, the alignment slot
210a-k that is narrowest or of the smallest width ("width" being
the dimension that is perpendicular to its length dimension, which
is along a radius extending from the center 212 of the wafer 130)
is that which is most closely aligned with a predetermined crystal
plane of the wafer. The same is true for the alignment slots
214a-k.
[0107] Once a corresponding pair of alignment slots 210, 214 has
been identified as being suitably aligned with a predetermined
crystal plane of the wafer (if one alignment slot 210 is
identified, its corresponding alignment slot 214 will also be of
the narrowest width from the group of alignment slots 214a-k, and
vice versa), this pair of alignment slots 210, 214 is "selected" as
noted by step 174 of the protocol 140 of FIG. 10. That is, the
location of this particular pair of alignment slots 210, 214 is
noted such that alignment marks on the blade mask may be aligned
thereto in accordance with step 182 of the protocol 140. More
specifically, a second photoresist layer is formed on the silicon
nitride masking layer in accordance with step 178 of the protocol
140 and in any appropriate manner. Either a positive-acting or
negative-acting photoresist again began may be utilized. In any
case, the blade mask is aligned with the selected alignment slots
in accordance with step 182 of the protocol 140, and the blade mask
is thereafter transferred onto the second photoresist layer in
accordance with step 186. The blade mask is such that the alignment
slots 21 0a-k, 214a-k will not interfere with the fabrication of
the individual cutting blades 56 (e.g., the alignment slots 210a-k,
214a-k are disposed beyond the region of the wafer on which cutting
blades 56 are fabricated).
[0108] Step 190 of the protocol 140 indicates that the second
photoresist layer is developed in accordance with the blade mask to
create openings that extend completely through the second
photoresist layer. "Developing" the second photoresist layer
includes both exposing portions of the second photoresist layer to
an appropriate type of light (either that portion of the second
photoresist material that is to be removed in the case of a
positive-acting photoresist material, or that portion of the second
photoresist layer that is to remain in the case of a
negative-acting photoresist material), and thereafter exposing the
"light treated" second photoresist layer to an appropriate
developer to remove the desired portions of the second photoresist
layer. Openings in accordance with the desired/required layout are
formed through the entire vertical extent of the second photoresist
layer to expose the underlying silicon nitride masking layer.
[0109] Appropriate openings in accordance with the blade pattern
are next etched through the entire vertical extent of the silicon
nitride masking layer pursuant to step 194 of the protocol 140. The
layout of these openings is in accordance with the openings in the
second photoresist layer, and thereby in accordance with the blade
mask. In one embodiment, a reactive ion etch is used to define
these openings in the silicon nitride masking layer required by the
blade mask. Other types of etches may be appropriate. In any case,
this then exposes selected portions of the upper surface of the
underlying wafer. The second photoresist layer is then stripped
(step 198) from the now patterned silicon nitride masking layer,
and another etch is initiated through step 202 of the protocol 140.
This particular etch defines the various blades 56 that are
included in the blade mask associated with step 186 of the protocol
140, and the result of which corresponds with FIG. 9D. In one
embodiment, the etch of step 202 is a KOH etch. Other etches may be
appropriate.
[0110] Any number of blades 56 may be simultaneously fabricated in
accordance with the protocol 140 of FIG. 10, depending of course on
the size of the blades 56 and the size of the wafer 130 from which
the blades 56 are fabricated. One blade pattern that may be
utilized by the protocol 140 results in the layout illustrated in
FIG. 12. Here, a number of rows and columns of blades 56 have been
fabricated on the wafer 130 utilizing the protocol 140 of FIG. 10.
Each blade 56 remains attached to the wafer 130 by at least one
blade support tab 131 of the wafer 130 at this point in time (more
than one blade support tab 131 could be provided for each blade 56,
and the blade support tab(s) 131 for a particular blade 56 may be
disposed at any appropriate location along the perimeter of the
corresponding blade 56). This is the only "interconnection" between
each blade 56 and the wafer 130 at this time, and which is the
result of the etch of step 202 of the protocol 140. All portions of
the wafer 130 other than the blades 56 and their corresponding
blade support tabs 131 may be characterized as a frame or skeleton
128 of the wafer 130 (e.g., a remainder). As such, a blade 56 may
be characterized as being attached to its blade support tab 131,
that in turn is attached to the frame 128.
[0111] Referring now to FIGS. 12 and 13A-B and as previously noted,
a score 132 is formed on each blade support tab 131 to facilitate
the removal of the corresponding blade 56 from the remainder of the
wafer 130 in a manner that will be discussed in more detail below.
Any appropriate number of scores 132 could be used in relation to
each blade support tab 131. Each score 132 may, but preferably does
not, extend through the entire vertical extent of the wafer 130. In
one embodiment, the depth of each score 132 is within a range of
about 2% to about 75% of the thickness of the wafer 130. In another
embodiment, the depth of each score 132 is on the order of about
10-30 microns, where the thickness of the wafer 130 is about 240
microns.
[0112] A pair of planar score surfaces 133a, 133b intersect at a
location identified by reference numeral 133c in FIG. 13B
(hereafter "intersection 133") to define the corresponding score
132 in the illustrated embodiment (e.g., a V-shaped configuration).
The planar score surfaces 133a, 133b may each be disposed in any
appropriate angular orientation. In the illustrated embodiment, the
planar score surface 133a is parallel with the cutting edge surface
72, while the planar score surface 133b is perpendicular to the top
surface 60 and bottom surface 64 of the blade 56. Other
configurations may be appropriate for the score 132 and yet still
facilitate separation of the cutting blade 56 from the wafer 130 in
a desired manner.
[0113] It should be noted that the score 132 associated with each
blade 56 preferably does not extend across the entire lateral
extent of its corresponding blade support tab 131. That is, each
score 132 preferably does not extend up to and intersect with that
portion of the second section 114 of the notch 110 that is defined
by the etch associated with step 202 of the fabrication protocol
140 of FIG. 10. One benefit of this preferred configuration is that
it enhances the structural integrity of the blade support tabs 131.
Stated another way, having each score 132 extend all the way across
its corresponding blade support tab 131 could possibly weaken the
interconnection between the blade support tab 131 and its
corresponding blade 56. That is, in a situation where the score 132
did extend across the entire lateral extent of the blade support
tab 131 (not shown), the etch associated with step 202 of the
fabrication protocol 140 of FIG. 10 may further reduce the lateral
extent of that end of the blade support tab 131 that interfaces
with its corresponding blade 56. This could weaken the "joint"
between the blade support tab 131 and its corresponding blade 56 to
the point of being susceptible to premature separation of the
corresponding cutting blade 56 from the remainder of the wafer 130.
The depth of the score 132 may also of course have an effect on the
structural integrity of the blade support tab 131, or stated
another way on the ability for the blade 56 to remain attached to
the wafer 130, including while mounting a blade handle 24 thereon.
In one embodiment, a portion of the blade support tab 131 is
disposed beyond each end of the score 132 such that the score 132
does not extend across the entire width or lateral extent of the
blade support tab 131, and the score 132 is about 2%-5% of the
thickness of the blade 56. This provides sufficient structural
integrity for the blade 56 to remain attached to the wafer 130
during handling and while mounting the handle 24 on the blade 56,
and yet still facilitates separation of the blade 56 from the wafer
130 at least substantially along the score 132 at the desired
time.
[0114] The configuration of the blade support tab 131, the location
of the score 132 along the blade support tab 131, or both also may
have an influence on how the fracture occurs. In one embodiment,
the score 132 is disposed along the length dimension of the blade
support tab 131 at a location where the blade support tab 131 is of
its minimum width (e.g., so that the shape of the blade support tab
131 acts as a stress concentrator, to cause the greatest stress to
occur at the location of its corresponding score(s) 132 to further
facilitate the fracture). The blade support tab 131 may be shaped
to generate the greatest stress at the location of the
corresponding score(s) 132 to further facilitate the fracture.
[0115] There are a number of other characteristics of note in
relation to the scores 132. Initially, each score 132 is preferably
aligned with a crystallographic plane such that the separation of
the blades 56 occurs at least substantially along a
crystallographic plane, and in one embodiment the intersection 133c
of the planar score surfaces 133a, 133b of a given score 132 is
aligned with a crystallographic plane. Moreover, preferably each
score 132 is parallel with its corresponding cutting edge 80.
Another is that the scores 132 are longitudinally offset from their
corresponding first sections 112 of the rear surface 106 of the
corresponding blade 56. That is, the scores 132 are "longitudinally
recessed" relative to the rear edge of the corresponding cutting
blade 56. Other configurations of the rear surface 106 of the blade
56 may be utilized and still provide this "longitudinally recessed"
feature. That is, what is of importance is that the score 132 be
positioned at a location that is longitudinally recessed from a
most rearwardly disposed portion of the rear surface 106 of the
blade 56. Stated another way, the score 132 is preferably disposed
closer to the cutting edge 80 than the most rearwardly disposed
portion of the rear surface 106 of the blade 56 (both measured
along/parallel to the central, longitudinal reference axis 58
associated with the blade 56). This may be of benefit if one or
more sharp edges develops during the separation of the blade 56
from the wafer 130 at least generally along its corresponding score
132.
[0116] Separation of the cutting blade 56 from the remainder of the
wafer 130 utilizing the score 132 produces the configuration that
is illustrated in FIG. 13C. Locations A and B correspond with the
locations where the blade support tab 131 had previously merged
with the cutting blade 56. It can be seen that the planar score
surface 133b of the score 132 has become part of the cutting blade
56. This also illustrates the preferred approach where the score
132 and the portion of the second section 114 of the notch 110 on
the opposite sides thereof are both defined by an etch, and thereby
are similarly shaded. In contrast, the region that is bounded by
the pair of dashed lines, and further that does not include planar
score surface 133b, is defined by fracturing the wafer 130.
Reference numeral 133d identifies this fracture region and utilizes
a different shading than the surfaces defining the planar score
surface 133b and the second section 114. The fracture region 133d
is longitudinally spaced from the rear-most portion of the cutting
blade 56. In one embodiment, the fracture region 133d is coplanar
with the second section 114, and may be considered as part thereof.
In another embodiment, the fracture region 133d is parallel to, but
longitudinally offset from, the second section 114 of the blade 56
(not illustrated). In this latter instance, the fracture regions
133d desirably still does not define the most rearwardly disposed
portion of the cutting blade 56.
[0117] As noted above, there may be some variation between the
blade mask and the resulting configuration of the blade 56 when
etched from the wafer 130. For instance, FIG. 13D includes a
reference numeral 57a that represents the blade mask perimeter
profile for the blade 56. The entire blade mask perimeter profile
57a for a blade 56 is illustrated in FIG. 13D, as well as a portion
of its corresponding blade support tab 131. Reference numeral 57b
in FIG. 13D represents an actual perimeter profile of a blade 56
when fabricated from the wafer 130 by an anisotropic etch. That is,
the actual perimeter profile 57b is that which is actually achieved
when using an anisotropic etch from a blade mask have the blade
mask perimeter profile 57a. Only a portion of the actual perimeter
profile 57b is illustrated in FIG. 13D for convenience.
[0118] Blades 56 are separated from the remainder of the wafer 130
generally by first mounting a blade handle 24 on an individual
cutting blade 56 in the above-noted manner so as to properly
register the blade handle 24 to the cutting blade 56. Once the
adhesive has cured an appropriate amount or once the blade handle
24 is otherwise sufficiently fixed to an individual blade 56, the
blade handle 24 is moved (e.g., manually) relative to the wafer 130
so as to cause the wafer 130 to fracture along its corresponding
score 132. In the illustrated embodiment, blade handles 24 are
attached to each of the individual blades 56 on a wafer 130 while
in a blade handle mounting fixture 224 (FIGS. 14-19). The wafer 130
with the blade handles 24 mounted on its various blades 54 is then
transferred to a blade separation fixture 300 where the individual
blades 56, with a blade handle 24 mounted thereon, are separated
from the remainder of the wafer 130 (FIGS. 20-23).
[0119] FIGS. 14-19 illustrate a desirable configuration for
allowing blade handles 24 to be mounted on individual cutting
blades 56 while still attached to and thereby part of the wafer
130. A base plate 220 is appropriately attached to a bottom surface
278 of a blade handle mounting fixture 224. One or more appropriate
fasteners (not shown) are directed through mounting holes 222 in
the base plate 220 and into mounting holes 296 formed on the bottom
surface 278 of the blade handle mounting fixture 224. Any
appropriate way of interconnecting the base plate 220 with the
blade handle mounting fixture 224 may be utilized.
[0120] The base plate 220 generally cooperates with the blade
handle mounting fixture 224 to define a vacuum chamber 284 (FIG.
17). More specifically, an annular groove 288 is defined on the
bottom surface 278 of the blade handle mounting fixture 224. An
annular seal ring 292 is disposed within this annular groove 288
and seats against an annular portion of a inner surface 223 of the
base plate 220 that projects toward or faces the bottom surface 278
of the blade handle mounting fixture 224. The perimeter of the
vacuum chamber 284 thereby corresponds with the annular seal ring
292, while the top and bottom of the vacuum chamber 284 are defined
by the bottom surface 278 of the blade handle mounting fixture 224
and the inner surface 223 of the base plate 220, respectively.
[0121] A vacuum is generated within the noted vacuum chamber 284 by
fluidly interconnecting a vacuum pump or the like (not shown) to a
vacuum pull-down port 276 associated with the blade handle mounting
fixture 224. This vacuum pull-down port 276 extends within the body
of the fixture 224 and intersects with a vacuum linking port 280.
This vacuum linking port 280 is disposed inwardly of the annular
seal ring 292 and intersects with the bottom surface 278 of the
fixture 224 so as to be fluidly interconnected with the vacuum
chamber 284. A plurality of vacuum holes 268 are also disposed
inwardly of the annular seal ring 292 so as to interface with the
vacuum chamber 284. These vacuum holes 268 extend from the bottom
surface 278 of the blade handle mounting fixture 224 to an upper
surface 228 of the fixture 224 on which the wafer 130 is
disposed.
[0122] The upper surface 228 of the blade handle mounting fixture
224 is configured to suitably support the wafer 130 and maintain
the same in a fixed position while installing the blade handles 24
on the individual blades 56 when still part of the wafer 130.
Generally, less than the entirety of the lower surface 138 of the
wafer 130 is in actual contact with the upper surface 228 of the
fixture 224. Moreover, the upper surface 228 of the fixture 224 is
configured so as to reduce the potential for damage to the cutting
edge 80 of each blade 56 while mounting the blade handles 24 on the
individual blades 56 the wafer 130. The upper surface 228 of the
fixture 224 is also configured so as to allow the bottom surface 48
of each blade handle 24 to properly seat on the top surface 60 of
its corresponding blade 56 (e.g., so as to be in interfacing
relation, or at least in closely spaced and parallel relation).
When adhesives are used, there will of course be a bond line
between the blade handle 24 and the blade 56. Finally, the blade 56
itself is directly supported by the fixture 224 (in one embodiment
in coplanar relation with non-blade portions of the wafer 130 and
including at least part of the above-noted frame 128), preferably
in a manner such that the net moment about the corresponding score
132 is zero (i.e., no torque) when mounting a blade handle 24 on
the cutting blade 56.
[0123] The upper surface 228 of the blade handle mounting fixture
224 includes a recess 232 having a base 236 that is vertically
offset from an annular perimeter portion 230 of the upper surface
228. This base 236 includes a planar wafer supporting surface 238,
a plurality of cutting edge cavities 244, and a plurality of
registrant cavities 256. An annular side wall 240 of the recess 232
extends from the lower elevation wafer supporting surface 238 of
the base 236 of the recess 232 to the higher elevation annular
perimeter portion 230 of the upper surface 228 of the fixture 224.
This annular side wall 240 at least substantially approximates a
perimeter of the wafer 130. Preferably, the annular side wall 240
and the perimeter of the wafer 130 are disposed in closely spaced
relation (e.g., such that there is no more than about a 1
millimeter gap between any portion of the annular side wall 240 and
a corresponding portion of the perimeter of the wafer 130).
[0124] At least one notch 272 is formed on the upper surface 228 of
the blade handle mounting fixture 224. Each notch 272 has a base
274 that is vertically offset from the wafer supporting surface 238
of the base 236 of the recess 232. The base 274 of each notch 272
is disposed at a lower elevation than the wafer supporting surface
238 of the base 236 of the recess 232. There is thereby a space
between the wafer 130 and the base 274 of each notch 272. This
space facilitates installation of the wafer 130 within the recess
232 of the blade handle mounting fixture 224, as well as the
removal of the wafer 130 from the blade handle mounting fixture
224. Both manual (e.g., human operator) and a machine(s) are
contemplated for one or both of the installation and removal of the
wafer 130 relative to the blade handle mounting fixture 224.
[0125] Multiple features are incorporated in the configuration of
the base 236 of the recess 232 that is formed on the upper surface
228 of the blade handle mounting fixture 224 for receipt of the
wafer 130. One is that the various vacuum holes 268 intersect with
the base 236 of the recess 232. Preferably these vacuum holes 268
intersect with the wafer supporting surface 238 of the base 236 of
the recess 232 (FIG. 16). The wafer supporting surface 238
interfaces with the lower surface 138 of the wafer 130 to
vertically support the wafer 130 while on the fixture 224. When the
wafer 130 is disposed within the recess 232, a vacuum is pulled
through the various vacuum holes 268 against the overlying wafer
130, through the vacuum chamber 284, through the vacuum linking
port 280, and through the vacuum pull-down port 276 by an
appropriate source. Suction forces thereby retain the lower surface
138 of the wafer 130 against the planar wafer supporting surface
238 of the base 236 of the recess 232. Exactly how the suction or
vacuum force is generated and transferred to the wafer 130 to
retain the same against the fixture 224 is not of particular
importance. Other configurations may be utilized to generate this
type of retention force for the wafer 130 on the fixture 224.
[0126] Another feature of the base 236 of the recess 232 formed on
the upper surface 228 of the blade handle mounting fixture 224 is
that it includes multiple cutting edge cavities 244. Each cutting
edge cavity 244 is defined by a base 248 that is vertically spaced
from the wafer supporting surface 238, and a side wall 252 that
extends from the lower elevation base 248 to the higher elevation
wafer supporting surface 238 (e.g., FIG. 18). In the illustrated
embodiment, at least part of the side wall 252 of each cutting edge
cavity 244 is disposed in perpendicular relation to the adjacent
portion of the wafer supporting surface 238 of the base 236 of the
recess 232. Any appropriate orientation of the side wall 252 of the
various cutting edge cavities 244 may be utilized.
[0127] What is of principal importance in relation to each cutting
edge cavity 244 is that they be sized and oriented on the upper
surface 228 of the fixture 224 such that the cutting edge 80 of
each blade 56 will be disposed over one of the cutting edge
cavities 244 when the wafer 130 is disposed within the recess 232
of the fixture 224. That is, the cutting edge 80 of each blade 56
is disposed in vertically spaced relation to the blade handle
mounting fixture 224. Preferably, the cutting edge 80 of each blade
56 never contacts the fixture 224 while the wafer 130 is positioned
thereon. In the illustrated embodiment, a given cutting edge cavity
244 accommodates the cutting edge 80 for multiple blades 56. More
specifically, a plurality of the cutting edge cavities 244 are
disposed in equally spaced rows along the base 236 of the recess
232. A given cutting edge cavity 244 accommodates all of the blades
56 in a corresponding row on the wafer 130 (i.e., provides a space
below the cutting edge 80 of each blade 56 in a given row on the
wafer 130) in the illustrated embodiment. It should be appreciated
that the base 236 of the recess 232 could be configured such that
the cutting edge 80 of each individual blade 56 has its own
individual cutting edge cavity 244 (not shown).
[0128] Multiple registrant cavities 256 are also formed on the base
236 of the recess 232 of the blade handle mounting fixture 224.
Generally, these registrant cavities 256 are sized so that the
registrants 32 on the bottom surface 48 of the blade handle 24 do
not contact the fixture 224 while mounting a blade handle 24 on a
particular cutting blade 56. Each registrant cavity 256 is defined
by a base 260 that is vertically spaced from wafer supporting
surface 238, and a side wall 264 that extends from the lower
elevation base 260 to the higher elevation wafer supporting surface
238 (e.g., FIG. 18). In the illustrated embodiment, at least part
of the side wall 264 of each registrant cavity 256 is disposed in
perpendicular relation to the adjacent portion of the wafer
supporting surface 238 of the base 236 of the recess 232. Any
appropriate orientation of the side wall 264 of the various
registrant cavities 256 may be utilized.
[0129] What is of principal importance in relation to each
registrant cavity 256 is that they be sized and oriented on the
upper surface 228 of the blade handle mounting fixture 224, such
that each registration 84 of each blade 56 will be disposed over
one of the registrant cavities 256 when the wafer 130 is disposed
within the recess 232 on the fixture 224. More specifically, each
registrant cavity 256 should be sized and oriented on the upper
surface 228 of the fixture 224 such that a registrant cavity 256 is
disposed below each registrant 32 of each blade handle 24 to keep
the bottom wall 40 of each registrant 32 of each blade handle 24 in
vertically spaced relation to the blade handle mounting fixture
224. In the illustrated embodiment, some registrant cavities 256
(those on an end of a row of registrant cavities 256) accommodate a
single registrant 32 from a single blade handle 24, while other
registrant cavities 256 accommodate a registrant 32 from a pair of
blade handles 24 mounted on adjacently disposed blades 56 within a
given row on the wafer 130. Although a plurality of rows of
registrant cavities 256 could be utilized and spaced such that a
given single registrant cavity 256 accommodated the registrant 32
of each blade handle 24 mounted on all of the blades 56 within a
given row on the wafer 130 (not shown), the illustrated
configuration is advantageous in relation to how the wafer 130 is
supported by the fixture 224 for installation of the blade handles
24.
[0130] Appropriate support of the wafer 130 is provided by the
illustrated configuration of the blade handle mounting fixture 224
when installing the blade handles 24 on the individual blades 56
that are still attached to and part of the wafer 130. Portions of
the wafer supporting surface 238 that are disposed under, interface
with, and support the representative blade 56 illustrated in FIG.
19, are shown by the dashed lines in FIG. 19. In this regard, each
blade 56 of the wafer 130 is supported by the blade supporting
surface 238 of the fixture 224 across the entire width of the blade
56 over a region that is spaced back from its cutting edge 80,
which again is disposed over one of the cutting edge cavities 244
so as to be spaced from the fixture 224. Each blade 56 is also
supported by the blade supporting surface 238 of the fixture 224
across the entire width of the blade 56 at or toward the rear of
the blade 56 (e.g., proximate the rear surface 106). Finally, the
blade 56 is also supported by the blade supporting surface 238 of
the fixture 224 under its corresponding blade support tab 131 and
along a longitudinally extending region between the registrant
cavities 84. Therefore, the blades 56 do not tend to deflect
downwardly a significant degree when installing blade handles 24 on
the blades 56 at a time when these blades 56 are still attached to
and part of the wafer 130. As noted above, preferably the blade 56
itself is directly supported by the fixture 224 (in one embodiment
in coplanar relation with non-blade portions of the wafer 130), in
a manner such that the net moment about the corresponding score 132
is zero (i.e., no torque) when mounting a blade handle 24 on the
cutting blade 56.
[0131] Summarizing the manner in which blade handles 24 are mounted
on the blades 56, the wafer 130 with the blades 56 formed thereon
is disposed within the recess 232 of the blade handle mounting
fixture 224 in the manner illustrated in FIG. 14. A vacuum is drawn
so as to retain portions of the wafer 130 against the wafer
supporting surface 238 associated with the fixture 224. An
appropriate adhesive may be applied on at least one of the top
surface 60 of one or more of the cutting blades 56 and the bottom
surface 48 of a corresponding number of blade handles 24. Each
registrant 32 on the bottom surface 48 of a particular blade handle
24 is then disposed within a corresponding registration cavity 84
on a particular blade 56 by moving the blade handle 24 toward the
fixture 224. Preferably, the registrants 32 of this blade handle 24
are initially disposed within the corresponding registration cavity
84 of the particular blade 24 so as to not contact its rear wall or
registration surface 94. This may be utilized to seat the planar
bottom surface 48 of the blade handle 24 on the planar top surface
60 of the cutting blade 56. The blade handle 24 may then be moved
generally rearwardly until each registrant 32 cooperates with its
corresponding registration surface 94, more typically a portion
thereof. This then registers or aligns the cutting edge 80 of the
particular cutting blade 56 relative to the microkeratome
registration surface 28 of its corresponding blade handle 24, which
in turn registers or aligns the cutting edge 80 of the cutting
blade 56 in a desired position within the microkeratome 4. Once
again, the microkeratome registration 28 of the blade handle 24 is
registered or aligned relative to the cutting tool registration
surface 14 of the head assembly 10 of the microkeratome 4.
[0132] Multiple cutting blades 56 may be formed on the wafer 130
prior to being positioned on the blade handle mounting fixture 224.
A blade handle 24 may be mounted on each cutting blade 56 in the
above-described manner. Blade handles 24 may be sequentially
mounted on the various individual cutting blades 56, multiple blade
handles 24 may be simultaneously mounted on multiple cutting blades
56, or blade handles 24 may be simultaneously mounted on all
cutting blades 56 formed on the wafer 130. Regardless of how many
cutting blades 56 are formed on the wafer 130 and the sequence of
installing any blade handle(s) 24 thereon, the wafer 130 may be
removed from the fixture 224 with a blade handle 24 being mounted
on at least one cutting blade 56 and with the cutting blade(s) 56
remaining part of the wafer 130. That is, after a blade handle 24
has been mounted on at least one cutting blade 56, the wafer 130
may be removed from the fixture 224 and without having separated
any such cutting blade 56 (with a blade handle 24 mounted thereon)
from the wafer 130. Thereafter, the various individual cutting
blades 56 with a blade handle 24 mounted thereon may be separated
from the remainder of the wafer 130.
[0133] FIGS. 20-23 illustrate a desirable configuration for
allowing blades 54 and their corresponding blade handles 24 to be
separated from the wafer 130. Various characteristics of one
configuration of a blade separation fixture 300 is disclosed by
FIGS. 20-23. Initially, the wafer 130 is retained on the blade
separation fixture 300 using a vacuum in the same manner discussed
above in relation to the blade handle mounting fixture 224 of FIGS.
14-19. Therefore, the bottom surface of the blade separation
fixture 300 will similarly include an annular groove and an annular
seal ring of the type used by the blade handle mounting fixture
224, so that the base plate 220 may be attached to the fixture 300
in the same manner as the blade mounting fixture 224 to define a
vacuum chamber. The blade separation fixture 300 will then also
include a vacuum pull-down port, a vacuum linking port, and vacuum
holes (not shown) of the type used by the blade mounting fixture
224 to draw a vacuum for retaining the wafer 130 on the fixture
300. Additional vacuum ports may be included on the upper surface
304 of the fixture 300 so as to retain the cutting tool 20 against
the fixture 300 after its corresponding blade 56 has been separated
from the remainder of the wafer 130 (e.g., by including vacuum
ports on a blade interface wall 352 of the fixture 300).
[0134] An upper surface 304 of the blade separation fixture 300 is
configured to suitably support the wafer 130 and maintain the same
in a fixed position while separating blades 56 from the remainder
of the wafer 130 using the blade handle 24 previously mounted
thereon (e.g., in accordance with FIGS. 14-19). Generally, less
than the entirety of the lower surface 138 of the wafer 130 is in
actual contact with the upper surface 304 of the fixture 300.
Moreover, the upper surface 304 of the fixture 300 is configured so
as to reduce the potential for damage to the cutting edge 80 of
each blade 56 while separating blades 56 from the remainder of the
wafer 130. Finally, the upper surface 304 of the fixture 300 is
configured so as to allow the bottom surface 48 of each blade
handle 24 to remain properly seated on the top surface 60 of its
corresponding blade 56 and in spaced relation to the fixture 300
(e.g., so as to be in interfacing relation, or at least in closely
spaced and parallel relation).
[0135] The upper surface 304 of the blade separation fixture 300
includes a recess 312 having a base 320 that is vertically offset
from an annular perimeter portion 308 of the upper surface 304.
This base 320 includes a planar wafer supporting surface 324 (which
includes a blade support tab section 326 for interfacing with and
supporting each blade support tab 131 of the wafer 130, which again
provides the interconnection between the blades 56 and the
remainder of the wafer 130), a plurality of cutting edge cavities
328, and a plurality of registrant/pivot cavities 340. An annular
side wall 316 of the recess 312 extends from the lower elevation
wafer supporting surface 324 of the base 320 of the recess 312 to
the higher elevation annular perimeter portion 308 of the upper
surface 304 of the fixture 300. This annular side wall 316 at least
substantially approximates a perimeter of the wafer 130.
Preferably, the annular side wall 316 and the perimeter of the
wafer 130 are disposed in closely spaced relation (e.g., such that
there is no more than about a 1 millimeter gap between any portion
of the annular side wall 316 and a corresponding portion of the
perimeter of the wafer 130).
[0136] At least one notch 305 is formed on the upper surface 304 of
the blade separation fixture 300. Each notch 305 has a base 306
that is vertically offset from the wafer supporting surface 324 of
the base 320 of the recess 312. The base 305 of each notch 304 is
disposed at a lower elevation than the wafer supporting surface 324
of the base 320 of the recess 312. There is a thereby a space
between the wafer 130 and the base 306 of each notch 305. This
space facilitates installation of the wafer 130 within the recess
312 of the blade separation fixture 300, as well as the removal of
the wafer 130 from the blade separation fixture 300. Both manual
(e.g., human operator) and a machine(s) are contemplated for one or
both of the installation and removal of the wafer 130 relative to
the blade separation fixture 300.
[0137] Multiple features are incorporated in the configuration of
the base 320 of the recess 312 that is formed on the upper surface
304 of the blade separation fixture 300 for receipt of the wafer
130. One is that the various vacuum holes (not shown) intersect
with the base 320 of the recess 312. Preferably these vacuum holes
intersect with the wafer supporting surface 324 of the base 320 of
the recess 312. The wafer supporting surface 324 interfaces with
the lower surface 138 of the wafer 130 to vertically support the
wafer 130 while on the fixture 300. When the wafer 130 is disposed
within the recess 312, a vacuum is pulled against the lower surface
138 of the wafer 130 through the various vacuum holes, through the
vacuum chamber, through the vacuum linking port, and through the
vacuum pull-down port by an appropriate source and in the same
manner discussed above in relation to the blade handle mounting
fixture 224. Suction forces thereby retain the lower surface 138 of
the wafer 130 against the planar wafer supporting surface 324 of
the base 320 of the recess 312. Exactly how the suction or vacuum
force is generated and transferred to the wafer 130 to retain the
same against the fixture 300 is not of particular importance. Other
configurations may be utilized to generate this type of retention
force for the wafer 130 on the fixture 300.
[0138] Another feature of the base 320 of the recess 312 formed on
the upper surface 304 of the blade separation fixture 300 is that
it includes multiple cutting edge cavities 328. Each cutting edge
cavity 328 is defined by a base 332 that is vertically spaced from
the wafer supporting surface 324, and a side wall 336 that extends
from the lower elevation base 332 to the higher elevation wafer
supporting surface 328 (e.g., FIG. 22). In the illustrated
embodiment, at least part of the side wall 336 of each cutting edge
cavity 328 is disposed in perpendicular relation to the adjacent
portion of the wafer supporting surface 324 of the base 320 of the
recess 312. Any appropriate orientation of the side wall 336 of the
various cutting edge cavities 328 may be utilized.
[0139] What is of principal importance in relation to each cutting
edge cavity 328 is that they be sized and oriented on the upper
surface 304 of the fixture 300 such that the cutting edge 80 of
each blade 56 will be disposed over one of the cutting edge
cavities 328 when the wafer 130 is disposed within the recess 312
on the fixture 300. That is, the cutting edge 80 of each blade 56
is disposed in vertically spaced relation to the blade separation
fixture 300. In the illustrated embodiment, a given cutting edge
cavity 328 accommodates the cutting edge 80 for multiple blades 56.
More specifically, a plurality of the cutting edge cavities 328 are
disposed in equally spaced rows along the base 320 of the recess
312. A given cutting edge cavity 328 accommodates all of the blades
56 in a corresponding row on the wafer 130 (i.e., provides a space
below the cutting edge 80 of each blade 56 in a given row on the
wafer 130) in the illustrated embodiment. It should be appreciated
that the base 320 of the recess 312 could be configured such that
the cutting edge 80 of each individual blade 56 had its own
individual cutting edge cavity 328 (not shown).
[0140] Multiple registrant/pivot cavities 340 are also formed on
the base 320 of the recess 312 of the blade separation fixture 300.
Each registrant/pivot cavity 340 is defined by a base 344 that is
vertically spaced from wafer supporting surface 324, a side wall
348 that extends from the lower elevation base 344 to the higher
elevation wafer supporting surface 324 (e.g., FIG. 22), and a blade
interface wall 352. In the illustrated embodiment, at least part of
the side wall 348 of each registrant/pivot cavity 340 is disposed
in perpendicular relation to the adjacent portion of the wafer
supporting surface 324 of the base 320 of the recess 312. Any
appropriate orientation of the side wall 348 of the various
registrant/pivot cavities 340 may be utilized. The blade interface
wall 352 defines the forward boundary of the corresponding
registrant/pivot cavity 340 and is configured to interface with the
bottom surface 64 of a blade 56 after being separated from the
wafer 130 in a manner that will be discussed in more detail
below.
[0141] What is of principal importance in relation to each
registrant/pivot cavity 340 is that they be sized and oriented on
the upper surface 304 of the fixture 300 such that each
registration cavity 84 of each blade 56 will be disposed over one
of the registrant/pivot cavities 340 when the wafer 130 is disposed
within the recess 312 on the fixture 300. More specifically, each
registrant/pivot cavity 340 should be sized and oriented on the
upper surface 304 of the fixture 300 such that the registrant/pivot
cavity 340 is disposed below each registrant 32 of each blade
handle 24 to keep the bottom wall 40 of each registrant 32 of each
blade handle 24 in vertically spaced to the blade separation
fixture 300. In the illustrated embodiment, a given
registrant/pivot cavity 340 accommodates the registrants 32 of
multiple cutting tools 20. More specifically, a plurality of the
registrant/pivot cavities 340 are disposed in equally spaced rows
along the base 320 of the recess 312. A given registrant/pivot
cavity 340 accommodates all of the blades 56 in a corresponding row
on the wafer 130 (i.e., provides a space below the registrant
cavities 84 of each blade 56 in a given row on the wafer 130) in
the illustrated embodiment. It should be appreciated that the base
320 of the recess 312 could be configured such that each individual
blade 56 had its own registrant/pivot cavity 340 (not shown).
[0142] The various blades 56 of the wafer 130 are suspended above
the upper surface 304 of the blade separation fixture 300. That is,
the blades 56 are disposed in vertically spaced relation to the
underlying base 320 of the recess 312 of the blade separation
fixture 300. Those portions of the wafer 130 that are disposed
between the rows of blades 56, as well as the outer perimeter of
the wafer 130 (e.g., the above-noted frame 128), interface with and
are supported by the wafer supporting surface 324 of the fixture
300. Part of the wafer supporting surface 324, namely structures in
the form of a plurality of blade supporting tab sections 326,
interfaces with and supports the various blade support tabs 131
that interconnect each of the blades 56 with the remainder of the
wafer 130. Each blade support tab section 326 extends toward, but
not beyond, the score 132 of the corresponding blade support tab
131. Preferably, the distal end of each blade support tab section
326 is vertically aligned with a score 132.
[0143] A blade supporting surface 356 is located under the various
blades 56 in a given row of the wafer 130 at a location that is
longitudinally between the corresponding cutting edge cavity 328
and the corresponding registrant/pivot cavity 340. This blade
supporting surface 356 is a planar surface, is parallel with the
wafer supporting surface 324, and is recessed relative to the wafer
supporting surface 324. That is, the blade supporting surface 356
is disposed at a lower elevation than the wafer supporting surface
324. Overlying blades 56 are thereby initially separated from the
corresponding blade supporting surface 356 by a space when the
wafer 130 is in the fixture 300. The above-noted blade interface
wall 352 extends from the blade supporting surface 356 down to the
base 344 of the corresponding registrant/pivot cavity 340. This
blade interface wall 352 is a planar surface and is disposed at an
angle .alpha. (FIG. 22) that is preferably within a range of about
15 degrees to about 30 degrees.
[0144] Summarizing the manner in which blades 56 are separated from
the remainder of the wafer 130, the wafer 130 is disposed within
the recess 312 on the blade separation fixture 300 and in the
manner illustrated in FIG. 20. Blade handles 24 typically will have
been mounted to each of the blades 56 of the wafer 130 (utilizing
the blade handle mounting fixture 224 discussed above in relation
FIGS. 14-19) at this time, although any number of blades 56 may
have a blade handle 224 mounted thereon and still utilize the blade
separation fixture 300. A vacuum is drawn so as to retain portions
of the wafer 130 (e.g., its frame 128) against the wafer supporting
surface 324 associated with the fixture 300 by "pulling down" on
portions of the wafer 130.
[0145] An at least generally downwardly directed force is then
exerted on a particular blade handle 24 to separate its
corresponding blade 56 from the wafer 130 in one embodiment. In
another embodiment, this force is exerted directly on the blade 56.
In either case, this may be done manually (e.g., by hand) or by a
machine(s) (e.g., manually activated or in an automated manner). In
one embodiment, this force is directed so as to be least generally
perpendicular to the top surface 60 of the corresponding cutting
blade 56. In any case, this type of force will cause the cutting
blade 56 to deflect down toward the underlying blade supporting
surface 356 a sufficient degree to cause the blade 56 (with its
blade handle 24 mounted thereon) to separate from the remainder of
the wafer 130 at least generally along its corresponding score 132.
This separation preferably occurs before the blade 56 contacts the
upper surface 304 of the fixture 300. The cutting edge 80 moves
toward, but does not contact, the underlying fixture 300 during
this deflection. One benefit of the configuration of the rear
surface 106 of the cutting blade 56, namely by having the score 132
disposed within the notch 110 on the back surface 106 of the blade
56, is that even if the fracture does not occur exactly along the
score 132, the wafer surface exposed by the fracture should still
be longitudinally offset or spaced relative to the first sections
112 of the rear surface 106 of the blade 56.
[0146] Once the blade 56 has separated from the wafer 130 in the
above-noted manner, the now separated blade 56 will continue in a
downward direction until it contacts the underlying blade
supporting surface 356. Since the force is being exerted on the
blade 56 through its corresponding blade handle 24, the bottom
surface 64 of the blade 56 will tend to move toward and most likely
interface with an underlying blade interface wall 352. As noted
above, suction forces or a vacuum may be used to retain the bottom
surface 64 of each cutting blade 56 against an underlying blade
interface wall 352 after being separated from the remainder of the
wafer 130 in the above-noted manner. In any case, this of course
moves its corresponding cutting edge 80 further away from the blade
separation fixture 300 (e.g., by a pivoting or pivotal-like motion)
so as to further reduce the potential for the cutting edge 80 being
damaged during separation of the blade 56 from the wafer 130. A
given cutting edge 80 thereby first moves at least generally toward
the underlying fixture 300, and then at least generally away from
the fixture 300.
[0147] The blade 56 again preferably moves into contact with the
fixture 300 only after separating from the wafer 130. It initially
does so by landing on the blade supporting surface 356 of the
fixture 300. This blade supporting surface 356 is in effect a
laterally extending beam about which the blade 56 pivots into
contact with the inclined blade interface wall 352. Therefore, the
cutting edge 80 first moves toward, but not to, the fixture 300
when the blade 56 is being separated from the wafer 130. When the
cutting blade 56 does contact the fixture 300 after separation from
the wafer 130 (the noted blade supporting surface 356), the cutting
edge 80 of the blade 56 is still spaced from the fixture 300 by
being over/within a cutting edge cavity 328. The blade 56 then
pivots in a direction to move the cutting edge 80 away from the
fixture 300, and in turn move its rear edge toward the fixture 300
(e.g., a teeter-totter-like action). The bottom surface 64 of the
blade 56 will then interface with the inclined blade interface wall
352 such that the rear surface 106 of the blade 56 (or an
associated edge) is disposed on the base 352 of the
registrant/pivot cavity 340 (e.g., projecting at least generally
downward) and further such that its cutting edge 80 is projecting
at least generally upward and in spaced relation to the fixture
300. Therefore, the cutting edge 80 also preferably never contacts
the fixture 300.
[0148] It is contemplated that each of the blades 56 may be
sequentially removed from the remainder of the wafer 130 in the
above-described manner (that is, one at a time), in one or more
groups, or all simultaneously. In this regard, multiple cutting
blades 56 may be formed on the wafer 130 prior to being positioned
on the blade separation fixture 300. A blade handle 24 may be
mounted on each cutting blade 56 as well before the wafer 130 is
positioned on the fixture 300. Cutting blades 56 may be
sequentially separated from the remainder of the wafer 130 in the
above-noted manner, multiple cutting blades 56 may be
simultaneously separated from the remainder of the wafer 130 in the
above-noted manner, or all cutting blades 56 formed on the wafer
130 may be simultaneously separated from the remainder of the wafer
130 in the above-noted manner. Regardless of how many cutting
blades 56 are formed on the wafer 130 and the sequence of
separating cutting blades 56 from the remainder of the wafer 130,
the wafer 130 may be removed from the fixture 300 after at least
one cutting blade 56 has been separated from the remainder of the
wafer 130. All cutting blades 56 are preferably separated from the
wafer 130 prior to removing the wafer 130 from the fixture 300.
However, any cutting blade 56 that has been separated from the
remainder of the wafer 130 may be removed from the fixture 300
prior to or after the wafer 300 is removed from the fixture
300.
[0149] The foregoing description of the present invention has been
presented for purposes of illustration and description.
Furthermore, the description is not intended to limit the invention
to the form disclosed herein. Consequently, variations and
modifications commensurate with the above teachings, and skill and
knowledge of the relevant art, are within the scope of the present
invention. The embodiments described hereinabove are further
intended to explain best modes known of practicing the invention
and to enable others skilled in the art to utilize the invention in
such, or other embodiments and with various modifications required
by the particular application(s) or use(s) of the present
invention. It is intended that the appended claims be construed to
include alternative embodiments to the extent permitted by the
prior art.
* * * * *