U.S. patent number 3,885,158 [Application Number 05/408,836] was granted by the patent office on 1975-05-20 for specimen block and specimen block holder.
This patent grant is currently assigned to Harris Corporation. Invention is credited to Richard William Belcher, Richard Edward Flutie.
United States Patent |
3,885,158 |
Flutie , et al. |
May 20, 1975 |
Specimen block and specimen block holder
Abstract
A specimen block which supports a specimen during inspection by
both an optical and a scanning electron microscope, and further
supports the specimen during a coating operation to enhance
secondary electron and X-ray emission, has a planar base and an
inclined surface upon which the specimen is to be mounted. During
inspection by the scanning electron microscope, the specimen block
is held by a standard specimen block holder and the specimen is
held at the angle of the inclined surfaces with respect to the base
of the holder. During the optical inspection and coating
operations, the specimen block is held by a special holder having
obliquely bored holes into which the specimen block will fit to
compensate for the inclined surface and hold the specimen parallel
to the base of the holder. In an alternate mode, the special holder
can be used to hold a standard specimen block so that its specimen
is at an angle with respect to the holder's base, for inspection by
a scanning electron microscope.
Inventors: |
Flutie; Richard Edward
(Melbourne Beach, FL), Belcher; Richard William
(Indialantic, FL) |
Assignee: |
Harris Corporation (Cleveland,
OH)
|
Family
ID: |
23617980 |
Appl.
No.: |
05/408,836 |
Filed: |
October 23, 1973 |
Current U.S.
Class: |
250/440.11 |
Current CPC
Class: |
H01J
37/20 (20130101) |
Current International
Class: |
H01J
37/20 (20060101); H01j 037/20 () |
Field of
Search: |
;250/440,441,442,443,310,311 ;350/86 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lawrence; James W.
Assistant Examiner: Church; C. E.
Attorney, Agent or Firm: Fidelman, Wolffe & Leitner
Claims
What is claimed is:
1. A specimen block holder and a specimen block for holding a
specimen in a selected plane for use in optical microscopes and for
use in specimen coating operations comprising:
a block holder having a first planar base surface for resting said
holder on a supporting surface;
at least one cavity extending downward into a portion of said
holder, said cavity having a linear axis which forms a first acute
angle with respect to said first planar base surface and;
a cylindrical specimen block having a second planar base surface,
and a third planar specimen mounting surface inclined at a second
acute angle with respect to said second planar base surface to form
said selected plane said cylindrical block extending into said
cavity and resting therein in such a manner that said third planar
specimen mounting surface is substantially parallel to said first
planar base surface.
2. A specimen block holder and a specimen block as set forth in
claim 1 wherein said first acute angle is between 10.degree. and
60.degree. and said second acute angle is the complement of said
first acute angle.
3. A specimen block holder and a specimen block as set forth in
claim 2 wherein said first acute angle is 30.degree. and said
second acute angle is 60.degree..
4. A specimen block holder and a specimen block as set forth in
claim 1 wherein said cylindrical specimen block is a truncated
right circular cylinder with said third planar specimen mounting
surface forming the plane of truncation.
5. A specimen block holder and a specimen block as set forth in
claim 1 wherein the cross-section of said cavity taken
perpendicular to said linear axis is circular.
6. A specimen block holder and a specimen block as set forth in
claim 5 having a second cavity extending into a portion of said
holder in a direction opposite to that of said first cavity, said
second cavity having a second linear axis which forms a third acute
angle with respect to said first planar base surface.
7. A specimen block holder and a specimen block as set forth in
claim 6 wherein said third acute angle is equal to said first acute
angle.
8. A specimen block holder and a specimen block as set forth in
claim 7 wherein said cross-section of said second cavity taken
perpendicular to said second linear axis is circular.
9. a specimen block holder and a specimen block as set forth in
claim 1 wherein said specimen block holder and said specimen block
are made of an opaque material.
10. A specimen block holder and a specimen block as set forth in
claim 9 wherein said opaque material is aluminum.
11. In a microscope including a specimen stage the improvement
comprising:
a specimen block holder and a cylindrical specimen block for
holding a specimen in a selected plane;
said specimen block holder having a first planar base surface, said
first planar base surface being positioned to rest on said specimen
stage;
a first cavity extending downward into a portion of said holder,
said cavity having a linear axis which forms a first acute angle
with respect to said first planar base surface;
a second cavity extending downward into a portion of said holder in
a direction opposite to that of said first cavity, said second
cavity having a second linear axis which forms a second acute angle
with respect to said first planar surface; and
said cylindrical specimen block having a second planar base
surface, and a third planar specimen mounting surface inclined at a
third acute angle with respect to said second planar base surface
to form said selected plane, said cylindrical block extending into
one of said first and second cavities and resting therein in such a
manner that said third planar specimen mounting surface is
substantially parallel to said first planar base surface.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to devices for holding specimens
for examination with both optical and scanning electron microscopes
and for holding specimens during coating operations and relates
more particularly to devices for holding specimens at a desired
angle of tilt for inspection with scanning electron microscopes and
for holding specimens in a horizontal position for inspection with
optical microscopes and during coating operations.
2. Prior Art
In the manufacture of miniature electronic components, it is
necessary to closely examine a manufactured specimen to determine
if the specimen meets various design criteria. In the course of
this examination, several commercially available instruments, such
as optical microscopes, scanning electron microscopes and X-ray
spectrometers are utilized. Because of the structural design of
these various instruments, it is necessary to hold the specimen in
two different positions during the examination process. For
example, it is well known that when examining a specimen with a
scanning electron microscope, it is desirable to tilt the specimen
with respect to the path of incoming electrons to increase electron
emission and facilitate detection of the emitted electrons. To
accomplish this tilting, various adjustable platforms have been
developed. These prior art adjustable tilting platforms are of a
relatively complex construction and as a result are costly to
manufacture and purchase and somewhat time-consuming to
operate.
Before examining a specimen with a scanning electron microscope, it
is a common practice to coat the specimen with a uniform layer of
metal to increase secondary electron emission and thus allow higher
resolution inspection. When performing this coating operation, it
is desirable to hold the specimen in a flat rotating plane to
achieve a uniform coating of metal.
Likewise, when examining a specimen with an optical microscope, due
to the construction of most commercially available models, it is
desirable to hold the specimen in a plane parallel to the base of
the microscope.
SUMMARY OF THE INVENTION
Briefly, the invention provides a specimen block for holding a
specimen in a selected plane for inspection with both an optical
and a scanning electron microscope and for use in specimen coating
operations, which specimen block is in the shape of a cylinder
having a first planar base surface and having a second planar
specimen surface forming the selected plane, inclined at an acute
angle with respect to the first planar base surface. The specimen
is mounted on the inclined planar specimen surface of the specimen
block. The invention further provides a specimen block holder for
holding a standard specimen block at an angle for use in a scanning
electron microscope and for holding the inventive specimen block in
a selected position for use in optical microscopes and for use in
specimen coating operations, which specimen block holder comprises
a body having a planar base surface and having at least one cavity
extending downward into a portion of the body at an acute angle
with respect to the planar base surface. The invention further
contemplates the insertion of the inventive specimen block into the
cavity in the specimen block holder in such a manner that the
inclined planar specimen mounting surface on the specimen block
will be parallel to the planar base surface of the specimen block
holder and the insertion of a standard specimen block into the
cavity to incline its planar specimen mounting surface with respect
to the planar base of the specimen block holder.
OBJECTS OF THE INVENTION
An object of the present invention is the provision of a novel
specimen block which is capable of being inserted into both a
standard specimen block holder and a novel specimen block holder of
the present invention.
Another object of the present invention is the provision of a novel
specimen block which is capable of holding a mounted specimen at a
selected angle of tilt when the specimen is being inspected by a
scanning electron microscope.
A further object of the present invention is the provision of a
novel specimen block which is capable of effectively extending the
range of tilt of a standard tilting platform.
A further object of the present invention is the provision of a
novel specimen block holder capable of holding the novel specimen
block of the present invention at a selected angle of tilt to
compensate for the angle of tilt built into the novel specimen
block and thus hold the specimen in a horizontal position for
examination with an optical microscope and for coating
operations.
Yet another object of the present invention is the provision of a
novel specimen block holder capable of holding a standard specimen
block at a specified angle of tilt when the specimen is being
inspected by a scanning electron microscope.
Another object of the present invention is the provision of a novel
specimen block for holding a specimen in a selected plane which is
simple, inexpensive to manufacture, and easy to use.
A still further object of the present invention is the provision of
a novel specimen block holder for holding a specimen block in a
selected position which is simple, inexpensive to manufacture, and
easy to use.
Other objects, advantages and novel features of the present
invention will become apparent from the following detailed
description of the invention when considered in conjunction with
the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram of the cross-section of an electron optical
system, specimen chamber and X-ray spectrometer;
FIG. 2 is a side view of a specimen block holder constructed in
accordance with the present invention;
FIG. 3 is a top view of the specimen block holder of FIG. 2;
FIG. 4 is a front view of the specimen block holder of FIG. 2
including a partial cutaway and a side view of a specimen block
constructed in accordance with the present invention;
FIG. 5 shows the specimen block of FIG. 4 held by a standard
specimen block holder;
FIG. 6 shows a standard specimen block held by a standard specimen
block holder;
FIG. 7 shows a standard specimen block held by the specimen block
holder of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In order to facilitate a better understanding of the invention, it
will be helpful to consider the environment in which the invention
is to be used. FIG. 1 shows a diagram of the cross-section of a
prior art electron optical system, specimen chamber and X-ray
spectrometer, manufactured by Japan Electron Optics Laboratory Co.,
Ltd. The components of the scanning microscope, generally indicated
at 10, are a high voltage input cable 12, an electron gun 13, an
anode 14, a gate valve 15, a condenser lens 16, a pole piece 17 and
an objective lens 18. A detector 11 is provided to measure electron
emission. The unit further includes an X-ray spectrometer 19 and an
optical microscope 20. A specimen stage 22 is situated at the base
of the unit and supports a standard specimen block holder 50. The
present invention is used in conjunction with, and as, a substitute
for, the specimen block holder 50.
Thus, it is evident from FIG. 1 that a stream of electrons emitted
by the gun 13 follows a vertical path to the anode 14, through the
valve 15, and the lenses 16 and 18 to a specimen (not shown) held
in the holder 50. Since the electron emission detector 11 is
positioned off to the side of the microscope 10, it is well known
that tilting the specimen with respect to the incoming vertical
stream of electrons improves secondary electron collection by
deflecting the emitted electrons in the direction of the detector.
On the other hand, since the optical microscope 20 can be
positioned directly over the specimen holder 50, it is most
desirable to hold a specimen in a horizontal position when
inspecting the specimen with the optical microscope 20.
With reference to FIGS. 2, 3, 4 and 5, the invention will be
described in detail. A specimen 60, which is ready for inspection,
is mounted on the surface 41 of a specimen block 40. The specimen
block 40 may be formed of any metal, e.g., cast aluminum, or any
other material suitable for use in electron and X-ray environments,
and is illustrated as a partially truncated right circular
cylinder. The plane of truncation creates a specimen mounting
surface 41 on specimen block 40 and forms an acute angle .alpha.
with respect to the planar base 42 of specimen block 40. The angle
.alpha. is preferably 60.degree., but may lie in the range of
30.degree. to 80.degree.. The specimen block may take other shapes
as long as it has a planar base and a planar inclined specimen
mounting surface.
After the specimen 60 has been mounted on planar specimen mounting
surface 41, it is desirable to inspect the specimen with an optical
microscope. Because of the characteristics of most commercially
available optical microscopes, the specimen 60 should be held in a
horizontal position. Thus, the present invention further provides a
specimen block holder 30 to hold the specimen block 40 in such a
manner as to place the planar specimen mounting surface 41 in a
horizontal plane. The specimen block holder 30 is a solid block or
body and may be formed of any metal, e.g., cast aluminum, or any
other material suitable for use in electron and and X-ray
environments. The body contains two cavities 31 and 32 which are
formed by drilling holes of circular cross-section about linear
axes 33 and 34, respectively, into the top of the specimen block
holder 30 at an angle .beta. with respect to the planar base 35 of
specimen block holder 30. The angle .beta. is preferably
30.degree., but may lie in the range of 10.degree. to 60.degree..
It should be noted, however, that angles .alpha. and .beta. must be
complementary in order to hold the specimen 60 in a horizontal
plane. The specimen block holder 30 is illustrated as containing
two cavities 31 and 32 so that two specimen blocks may be held
simultaneously; however, the number of cavities in the specimen
block holder is purely a function of space limitations and more
could be added if space were available.
Subsequent to optical inspection of the specimen 60, but before
examination with a scanning electron microscope, it is desirable to
coat the specimen with a thin layer of metal, such as gold, having
a thickness on the order of 200 angstroms to increase secondary
electron emission and to improve X-ray emission if an X-ray
spectrometer is used. To produce a uniform metal coating, it is
once again desirable to hold the specimen block 40 in such a manner
as to place the planar specimen mounting surface 41 in a horizontal
plane. Thus, for the coating operation, the specimen block 40 is
held by the specimen block holder 30. After coating, the specimen
60 may again be examined with an optical microscope and maintained
in a horizontal position.
For examination with a scanning electron microscope as explained in
connection with FIG. 1, it is helpful to tilt the specimen with
respect to the path of incident electrons 25. Thus, with the
present invention, the specimen block 40 is held in a vertical
position and the planar specimen mounting surface 41 becomes the
tilted surface. For examination with a scanning electron
microscope, the specimen block 40 is held by a standard specimen
block holder 50, well known in the prior art, which holds a
specimen block in a vertical position. The planar specimen mounting
surface 41 is thus tilted with respect to the path of incident
electrons 25 by the angle .beta.. The specimen block is prevented
from rotating by tightening a set screw 52.
It is also possible to utilize the specimen block 40, when held by
the specimen block holder 50, in conjunction with a standard
tilting stage such as the stage symbolically indicated at 22. Thus,
if the stage 22 were capable of being tilted 45.degree., the
tilting range could be extended to 45.degree.+.alpha. by utilizing
the specimen block 40 in conjunction with the stage 22.
Thus, it is apparent that the use of the specimen block and
specimen block holder of the present invention greatly facilitates
optical microscope inspection and insures more uniform metal
coatings of a specimen by holding the specimen in a horizontal
position. The present invention further saves time in the
inspection of a specimen since the specimen may remain mounted on
the specimen block throughout the entire operation. The specimen
block need only be moved once and that is from the specimen block
holder 30 to the standard holder 50.
With reference to FIGS. 6 and 7, an alternate embodiment of the
invention will be described. A specimen 61, which is to be
inspected, is mounted on surface 71 of a standard specimen block 70
which is in the shape of a right circular cylinder. The specimen
mounting surface 71 is the top of the cylinder and is parallel to
the base surface 72. As discussed earlier, for optical microscope
inspection, the specimen 61 should be held in a horizontal
position. Thus, a standard specimen block holder 50 has been used
to hold the standard specimen block 70 for optical inspection of
the specimen 61. Furthermore, when coating the specimen 61 with a
thin layer of metal as discussed in connection with FIGS. 2-5, the
specimen 61 should be maintained in a horizontal plane and as a
result the specimen block 70 is again held by a standard specimen
block holder 50. To this point, what has been described is
illustrated in FIG. 6 and is part of the prior art and comprises no
part of the present invention.
For examination of the specimen 61 with a scanning electron
microscope, it is necessary to tilt the specimen 61 with respect to
the path of incident electrons. Known methods of tilting the
specimen 61 frequently involved remounting the specimen 61 on a
special device or the use of relatively complex and expensive
tilting platforms. However, by utilizing the specimen block holder
30 of the present invention, the specimen block 70 need merely be
transferred from the standard holder 50 to one of the cavities 31
or 32 in the specimen block holder 30. The specimen mounting
surface 71 is thus tilted with respect to the path of incident
electrons 25 by the angle .beta..
Some standard specimen blocks may be too short to be held by the
specimen block holder 30. Thus, it is important to select a block
of sufficient height to be securely held by the holder 30.
Therefore, it is apparent that the use of the specimen block holder
of the present invention further greatly facilitates scanning
electron microscope inspection of a specimen mounted on a standard
specimen block.
While there has been described what is at present considered to be
the preferred embodiment of the invention, it will be obvious to
those skilled in the art that various changes and modifications may
be made therein without departing from the scope of the invention.
For example, the specimen block 40 need not be shaped as a right
circular cylinder, but may assume any convenient shape that will
keep the specimen mounting surface in the desired position.
Likewise, the cavities in the specimen block holder 30 need not be
of circular cross-section but may be of any shape capable of
holding a specimen block in a desired position. Additionally, the
cavities 31 and 32 may include a keying or locking mechanism to
prevent relative movement between the specimen block and the
specimen block holder. Furthermore, the specimen block holder 30
need not be in the shape of a rectangular parallelepiped as
illustrated, but may take on any shape that will hold a specimen
block in the desired position. It is therefore aimed in the
appended claims to cover all such changes and modifications as fall
within the true spirit and scope of the invention.
* * * * *