U.S. patent application number 14/212492 was filed with the patent office on 2014-09-18 for sapphire ribbons and apparatus and method for producing a plurality of sapphire ribbons having improved dimensional stability.
This patent application is currently assigned to Saint-Gobain Ceramics & Plastics, Inc.. The applicant listed for this patent is Saint-Gobain Ceramics & Plastics, Inc.. Invention is credited to Jan J. Buzniak, Joseph M. Collins, Abbie M. Jennings, Christopher D. Jones, John Walter Locher, Guilford L. Mack, III, Marc Ouellette.
Application Number | 20140272413 14/212492 |
Document ID | / |
Family ID | 51528384 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140272413 |
Kind Code |
A1 |
Ouellette; Marc ; et
al. |
September 18, 2014 |
Sapphire Ribbons and Apparatus and Method for Producing a Plurality
of Sapphire Ribbons Having Improved Dimensional Stability
Abstract
The present disclosure is directed to an apparatus and method
for forming sapphire ribbons via Edge-Defined Film-Fed Growth
(EFG). Further, the present disclosure is directed to a plurality
of concurrently grown sapphire ribbons having features such as a
low dimensional variability and elimination of voiding between the
sapphire ribbons concurrently grown in a batch.
Inventors: |
Ouellette; Marc; (Nashua,
NH) ; Collins; Joseph M.; (Dublin, NH) ;
Locher; John Walter; (Amherst, NH) ; Mack, III;
Guilford L.; (Manchester, NH) ; Jennings; Abbie
M.; (Milford, NH) ; Buzniak; Jan J.; (Solon,
OH) ; Jones; Christopher D.; (Amherst, NH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Saint-Gobain Ceramics & Plastics, Inc. |
Worcester |
MA |
US |
|
|
Assignee: |
Saint-Gobain Ceramics &
Plastics, Inc.
Worcester
MA
|
Family ID: |
51528384 |
Appl. No.: |
14/212492 |
Filed: |
March 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61791364 |
Mar 15, 2013 |
|
|
|
61857988 |
Jul 24, 2013 |
|
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Current U.S.
Class: |
428/399 |
Current CPC
Class: |
C30B 15/34 20130101;
C30B 29/20 20130101; Y10T 428/2976 20150115; C01F 7/02 20130101;
Y10T 117/1044 20150115 |
Class at
Publication: |
428/399 |
International
Class: |
C01F 7/02 20060101
C01F007/02 |
Claims
1. A batch of at least six concurrently EFG grown sapphire ribbons,
wherein at least six of the at least six EFG grown sapphire ribbons
have a total thickness variation of no greater than 10%.
2. A batch of at least six concurrently EFG grown sapphire ribbons,
wherein at least six of the sapphire ribbons in the batch are
essentially free of voids.
3. The batch of claim 1, wherein at least six of the sapphire
ribbons in the batch have an average width of at least about 101.6
mm.
4. The batch of claim 1, wherein at least six of the sapphire
ribbons in the batch have an average length of at least about 152.4
mm.
5. The batch of claim 1, wherein at least six of the sapphire
ribbons in the batch have an average thickness in a range of from
about 0.1 mm to about 100 mm.
6. The batch of claim 1, wherein at least six of the sapphire
ribbons in the batch have a Total Thickness Variation (TTV) of no
greater than 2 mm.
7. The batch of claim 1, wherein two sapphire ribbons grown from
outer dies in the batch have a Total Thickness Variation (TTV) of
no greater than 1.2 mm.
8. The batch of claim 1, wherein at least six of the sapphire
ribbons in the batch have a Total Thickness Variation (TTV) of no
greater than 2 mm, and wherein the TTV is determined without
including any voids.
9. The batch of claim 1, wherein at least six of the sapphire
ribbons in the batch have a Total Thickness Variation (TTV) of no
greater than 1.2 mm, and wherein the TTV is determined without
including any voids.
10. The batch of claim 1, wherein the variability of total
thickness variation between the total number of concurrently formed
ribbons is no greater than about .+-.50%.
11. The batch of claim 1, wherein the variability of total
thickness variation between the total number of concurrently formed
ribbons is no greater than about .+-.10%.
12. The batch of claim 1, wherein each of the at least six of the
at least six EFG grown sapphire ribbons have a total thickness
variation of no greater than 5%.
13. The batch of claim 1, wherein at least six of the sapphire
ribbons in the batch have a maximum low spot thickness of at least
about 1 mm.
14. The batch of claim 1, wherein at least six of the sapphire
ribbons in the batch have a maximum low spot thickness of at least
about 0.5 mm.
15. The batch of claim 1, wherein the one or more sapphire ribbons
in the batch have a C-axis, an A-axis, M-axis or an R-axis
orientation substantially perpendicular to the sapphire ribbon's
major surface.
16. The batch of claim 1, wherein the one or more sapphire ribbons
have an A-axis orientation substantially perpendicular to the
sapphire ribbon's major surface.
17. The batch of claim 1, wherein the batch comprises at least 8
sapphire ribbons.
18. The batch of claim 1, wherein the batch comprises at least 10
sapphire ribbons.
19. A sapphire ribbon grown from an outer die in an EFG growth
apparatus configured to simultaneously produce at least six
sapphire ribbons, wherein the sapphire ribbon grown from the outer
die has a thickness variation within 10% of the average thickness
of each inner sapphire ribbon produced simultaneously with the
sapphire ribbon grown from the outer die.
20. The sapphire ribbon of claim 19, wherein the sapphire ribbon
grown from an outer die is essentially free of voids.
Description
FIELD OF THE DISCLOSURE
[0001] The present disclosure is directed to sapphire ribbons and
apparatuses and methods for forming sapphire ribbons particularly
by Edge-Defined Film-Fed Growth (EFG).
RELATED ART
[0002] Sapphire crystals are used in a variety of applications. For
example, sapphire ribbons can be used for various demanding, high
performance commercial applications, such as wafers and screen
protectors for mobile phones. Further improvement of sapphire
ribbons, in particular production of a plurality of sapphire
ribbons grown concurrently with improved dimensional stability
variation between the ribbons is desired.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] Embodiments are illustrated by way of example and are not
limited in the accompanying figures.
[0004] FIG. 1 includes an illustration of an EFG apparatus
according to an embodiment of the present disclosure.
[0005] FIG. 2 includes an illustration of an arrangement of dies in
an EFG apparatus according to another embodiment of the present
disclosure.
[0006] FIG. 3 includes an illustration of a sapphire ribbon.
[0007] FIG. 4 includes an image of a batch of sapphire ribbons
produced in an example (Batch A).
[0008] FIG. 5 includes an image of a batch of sapphire ribbons
produced in an example (Batch B).
[0009] FIG. 6 includes an image of a batch of sapphire ribbons
produced in an example (Batch C).
[0010] Skilled artisans appreciate that elements in the figures are
illustrated for simplicity and clarity and have not necessarily
been drawn to scale. For example, the dimensions of some of the
elements in the figures may be exaggerated relative to other
elements to help to improve understanding of embodiments of the
invention.
DETAILED DESCRIPTION
[0011] The following description in combination with the figures is
provided to assist in understanding the teachings disclosed herein.
The following discussion will focus on specific implementations and
embodiments of the teachings. This focus is provided to assist in
describing the teachings and should not be interpreted as a
limitation on the scope or applicability of the teachings. However,
other embodiments can be used based on the teachings as disclosed
in this application.
[0012] As used herein, the term "C-plane sapphire" refers to
substantially planar single crystal sapphire, the C-axis of which
is substantially normal (.+-.10 degrees) to the major planar
surface of the material. Typically, the C-axis is less than about 1
degree from the major planar surface.
[0013] As used herein, the term "A-plane sapphire" refers to
substantially planar single crystal sapphire, the A-axis of which
is substantially normal (.+-.10 degrees) to the major planar
surface of the material. Typically, the A-axis is less than about 1
degree from the major planar surface.
[0014] As used herein, the term "R-plane sapphire" refers to
substantially planar single crystal sapphire, the R-axis of which
is substantially normal (.+-.10 degrees) to the major planar
surface of the material. Typically, the R-axis is less than about 1
degree from the major planar surface.
[0015] Each of the crystallographic planes in sapphire discussed
herein are as is commonly known in the art. It is to be understood
that as used herein, mention of a particular orientation of a
crystal sheet to a specific plane include all off-angle or
mis-angle, miscut, or the like orientations in which the reference
plane is tilted to another plane. For example, it is often
desirable to product crystal sheets having a general A-plane or
C-plane orientation, but include a desired tilt or miscut angle
toward the M-plane. Accordingly, use of the phrase "A-plane" or
"C-plane" for example, include this plane as the general reference
plane with any desired offcut or misangle orientation.
[0016] The following table below illustrates the miller indices and
d spacing of the common crystallographic planes in sapphire:
TABLE-US-00001 TABLE A Plane Miller Indices d Spacing a (11-20),
(-12-10), (-2110) 2.379 .ANG. (-1-120), (1-210), (2-1-10) m
(10-10), (01-10), (-1100) 1.375 .ANG. (-1010), (0-110), (1-100) c
(0001) 2.165 .ANG. r (1-102), (01-12), (-1012) 1.964 .ANG. n
(11-23), (-12-13), (-2113) 1.147 .ANG. (-1-123), (1-213), (2-1-13)
s (10-11), (-1101), (0-111) 1.961 .ANG.
[0017] As used herein, the phrases "outer ribbons", "outer die",
"outer sapphire ribbons" , "outer crystal ribbons" and the like
include all ribbons except the most inner 4 ribbons if the total
number of ribbons being concurrently grown is even or the most
inner 5 ribbons if the total number of ribbons being concurrently
grown is odd. For example, in an EFG apparatus adapted to
concurrently grow 10 or 11 ribbons, the outer ribbons would include
the 3 most outer ribbons on each side. Similarly, and as another
example, in an EFG apparatus adapted to concurrently grow 6 or 7
ribbons, the outer ribbons would include only the outermost ribbon
on each side.
[0018] The terms "comprises," "comprising," "includes,"
"including," "has," "having" or any other variation thereof, are
intended to cover a non-exclusive inclusion. For example, a method,
article, or apparatus that comprises a list of features is not
necessarily limited only to those features but may include other
features not expressly listed or inherent to such method, article,
or apparatus. Further, unless expressly stated to the contrary,
"or" refers to an inclusive-or and not to an exclusive-or. For
example, a condition A or B is satisfied by any one of the
following: A is true (or present) and B is false (or not present),
A is false (or not present) and B is true (or present), and both A
and B are true (or present).
[0019] Also, the use of "a" or "an" is employed to describe
elements and components described herein. This is done merely for
convenience and to give a general sense of the scope of the
invention. This description should be read to include one, at least
one, or the singular as also including the plural, or vice versa,
unless it is clear that it is meant otherwise. For example, when a
single item is described herein, more than one item may be used in
place of a single item. Similarly, where more than one item is
described herein, a single item may be substituted for that more
than one item.
[0020] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. The
materials, methods, and examples are illustrative only and not
intended to be limiting. To the extent not described herein, many
details regarding specific materials and processing acts are
conventional and may be found in textbooks and other sources within
the crystal and particularly sapphire crystal arts.
[0021] The following disclosure describes apparatuses and methods
to form a plurality of sapphire ribbons which have consistent
characteristics between each concurrently produced ribbon. For
example, it has heretofore been unknown how to form a multitude of
sapphire ribbons, and particularly at least six sapphire ribbons,
having consistency between the ribbons, and particularly the outer
ribbons as described herein. The concepts are better understood in
view of the embodiments described below that illustrate and do not
limit the scope of the present invention.
[0022] FIG. 1 illustrates an apparatus 5 for growing a plurality of
crystal ribbons 7, in particular a sapphire crystal ribbons, via
Edge-Defined Film-Fed Growth (EFG) according to a first aspect of
the disclosure. As illustrated in FIG. 1, the apparatus 5 can
include a melt source 10; a plurality of dies 20 in communication
with the melt source; a plurality of first regions 30 adjacent the
plurality of dies; and a heat reflective shield 50. The heat
reflective shield 50 can be angled with respect to the horizontal
plane. The horizontal plane refers to the plane perpendicular to
the two vertically extending side surfaces 28 of the die tip. As
used herein, a heat reflective shield angled with respect to the
horizontal plane includes all orientations other than perpendicular
and parallel with the horizontal plane.
[0023] In certain embodiments, the heat reflective shield 50 can be
disposed adjacent to at least part of both the die tip 22 and the
first region 30. The heat reflective shield 50 can include a first
surface 52 facing the die and a second surface 54 opposite the
first surface 52. The heat reflective shield 50 can be configured
to direct (or reflect) heat energy contacting the first surface 52
of the heat reflective shield towards a region of lower
temperature, such as in a second region 32, above the first region
30. Reflecting heat radiating from the first region 30 to a region
of lower temperature can increase the thermal gradient in the first
region 30 above the die relative to an apparatus having a heat
shield parallel to the side surface of the die tip. As such, the
heat reflective shield 50 can be configured to control a first
thermal gradient from reflected heat in both a lateral direction
and a vertical direction. This in contrast with a heat shield which
is perpendicular to the horizontal plane (or parallel with the side
surface of the die tip), which reflects most of its heat in the
lateral direction thereby not enabling control of the thermal
gradient from reflected heat in a vertical direction. By angling
the heat shield with respect to the horizontal plane, a significant
amount of the radiated heat can be reflected to an area different
from which it originated.
[0024] As used herein, "thermal gradient" refers to the average
change in temperature of the crystal ribbon over a distance between
two locations in an EFG growth apparatus. The distance between the
two locations is measured on a line along which the single crystal
sapphire advances during the production process. For example, in an
EFG technique, the temperature difference may be 50 degrees Celsius
between a first position in the apparatus and a second position in
the apparatus. Thermal gradient units may be, for example, "degrees
per cm" or "degrees per inch." If not specified, the temperature
change is from a higher temperature to a lower temperature as the
sapphire crystal passes from the first location to the second
through the gradient. In particular embodiments, the first thermal
gradient can extend along the forming plane for a distance of at
least about 10 mm, at least about 20 mm, at least about 30 mm, at
least about 50 mm, or even at least about 100 mm.
[0025] Further, a second thermal gradient can be located adjacent
to the first thermal gradient. The second thermal gradient can be
further away from the die opening than the first thermal gradient.
In particular embodiments, the second thermal gradient can be less
than the first thermal gradient. For example, as the sapphire
ribbon is formed, it can be cooled faster in the first region 30
than the second region 32 such that the second thermal gradient in
the second region 32 is less than the first thermal gradient in the
first region 30.
[0026] Referring again to FIG. 1, the plurality of dies can each
have a die opening 24. The die openings 24 can have a width of at
least about 101.6 mm, at least about 152.4 mm, at least about 203.2
mm, or even at least about 304.8 mm. Moreover, in certain
embodiments, the die openings 24 can have a thickness of at least
about 0.3 mm, at least about 0.5 mm, at least about 1.0 mm, at
least about 2.0 mm, or even at least about 2.5 mm. The dimensions
of the die opening 24 can determine the desired dimensions (width
and thickness) of the ribbon formed through the die openings. A
particular advantage of the present disclosure is the ability to
form sapphire ribbons with a low variance between die openings 24
and the average thickness of each of the sapphire ribbons 7
concurrently formed within the same EFG growth apparatus 5. For
example, in particular embodiments, a ratio of the average
thickness of the outer ribbons (and even each of the concurrently
produced ribbons) to the thickness of the die opening can be at
least about 0.95:1.
[0027] Referring now to FIG. 2, there is illustrated a sketch of
one embodiment of the arrangement of die openings 25, 27, 29 within
an EFG apparatus. As illustrated, the plurality of dies can be
arranged such that at least one of the plurality of die openings
25, 27, 29 are at a different height in relation to another one of
the plurality of die openings 25, 27, 29. For example, the die
openings 25 of the outer dies can be higher than the die openings
29 of the inner dies. Further, the most inner dies can have the
lowest die openings 29 of the plurality of die openings 25, 27, 29.
In certain embodiments, the most outer die openings 25 can have a
height which is at least about 0.254 mm, at least about 1.27 mm, at
least about 2.54 mm, or even at least about 3.81 mm higher than the
most nearest adjacent die opening 27.
[0028] Further, each of the plurality of dies can be spaced apart
from an adjacent die in a horizontal direction of no greater than
609.6 mm, no greater than 508 mm, no greater than 406.4 mm, no
greater than about 304.8 mm, no greater than about 254 mm, no
greater than about 203.2 mm, no greater than about 152.4 mm, no
greater than about 127 mm, no greater than about 101.6 mm, no
greater than about 76.2 mm, no greater than about 50.8 mm, no
greater than about 25.4 mm, no greater than about 19.05 mm, no
greater than about 12.7 mm, or even no greater than about 6.35 mm.
The spacing is measure from the center of one die tip to the center
of an adjacent die tip.
[0029] Referring again to FIG. 1, the vertical heat shield 55 can
be disposed further away from angled heat reflective shield 50. In
certain embodiments, the EFG apparatus can include both a vertical
heat shield 55 and the angled heat reflective shield 50. In other
embodiments, only the angled heat reflective shield 50 may be
present.
[0030] In certain embodiments, the heat reflective shield 50 can
have an angle a with the horizontal plane of no less than about 1
degree, no less than about 2 degrees, no less than about 3 degrees,
no less than about 4 degrees, no less than about 5 degrees, no less
than about 10 degrees, no less than about 15 degrees, no less than
about 20 degrees, no less than about 25 degrees, no less than about
30 degrees, no less than about 35 degrees, no less than about 40
degrees, no less than about 45 degrees, no less than about 50
degrees, no less than about 55 degrees, no less than about 60
degrees, no less than about 65 degrees, no less than about 70
degrees, no less than about 75 degrees, no less than about 80
degrees, or even no less than about 85 degrees. In further
embodiments, the heat reflective shield can have an angle a of no
greater than about 88 degrees, no greater than about 85 degrees, no
greater than about 80 degrees, no greater than about 75 degrees, or
even no greater than about 70 degrees with horizontal plane. In
still further embodiments, the heat reflective shield can have an
angle a in a range of any of the maximum and minimum values
described herein.
[0031] The heat reflective shield 50 can be constructed from any
material that can manipulate the flow of heat radiation within the
EFG apparatus. In certain embodiments, the heat reflective shield
50 can be constructed from a metal, such as for example, a
refractory metal.
[0032] FIG. 3 illustrates a sketch of a sapphire ribbon 100. The
sapphire ribbon 100 includes a length L, a width W, and a thickness
T. The length can be greater than or equal to the width. The length
and the width can be greater than thickness. It is to be understood
that all dimensional values for the one or more ribbons including
length, width, thickness, thickness variation, etc. that are
described herein are measured on the "virgin" ribbon, i.e. before
any finishing operation such as grinding or polishing, unless
expressly stated otherwise. Further, it is to be understood that
all dimensional values for the one or more ribbons including
length, width, thickness, thickness variation, etc. that are
described herein are measured for the full width section. As used
herein, the "full width" occurs when the ribbon achieves a width
within 95% of the width of the die.
[0033] In certain embodiments, a sapphire ribbon described herein,
and even at least six or still even all of the concurrently
produced sapphire ribbons can have a width of at least about 101.6
mm, at least about 152.4 mm, at least about 203.2 mm, or even at
least about 304.8 mm. In further embodiments, a sapphire ribbon
described herein, and even each concurrently produced sapphire
ribbon can have a width of no greater than about 2540 mm, no
greater than about 1219.2 mm, no greater than about 914.4 mm, no
greater than about 762 mm, no greater than about 609.6 mm, or even
no greater than about 457.2 mm. In still further embodiments, a
sapphire ribbon described herein, and even each concurrently
produced sapphire ribbon can have a width in a range of any of the
maximum and minimum values described herein.
[0034] In further embodiments, a sapphire ribbon described herein,
and even at least six or still even all of the concurrently
produced sapphire ribbons can have a length of at least about 152.4
mm, at least about 304.8 mm, at least about 609.6 mm, at least
about 762 mm, at least about 914.4 mm, at least about 1066.8 mm, or
even at least about 1219.2 mm. In further embodiments, a sapphire
ribbon described herein, and even at least six or still even all of
the concurrently produced sapphire ribbon can have a length of no
greater than about 5080 mm, no greater than about 3810 mm, or even
no greater than about 2540 mm. In even further embodiments, a
sapphire ribbon described herein, and even at least six or still
even all of the concurrently produced sapphire ribbons can have a
length in a range of any of the maximum and minimum values
described herein.
[0035] In still further embodiments, a sapphire ribbon described
herein, and even at least six or still even all of the concurrently
produced sapphire ribbons can have an average thickness of at least
about 0.1 mm, at least about 0.5 mm, at least about 0.8 mm, at
least about 1 mm, at least about 1.3 mm, at least about 1.5 mm, at
least about 1.7 mm, at least about 2.0 mm, or even at least about
2.3 mm. In further embodiments, a sapphire ribbon described herein,
and even at least six or still even all of the concurrently
produced sapphire ribbons can have an average thickness of no
greater than about 100 mm, no greater than about 75 mm, no greater
than about 50 mm, no greater than about 35 mm, no greater than
about 25 mm, no greater than about 15 mm, no greater than about 10
mm, or even no greater than about 5 mm. Further, a sapphire ribbon
described herein, and even at least six or still even all of the
concurrently produced sapphire ribbons can have an average
thickness within a range between any of the maximum and minimum
values described herein. As used herein, "average thickness" refers
to the mean average thickness of all thickness measured in a
thickness map having measurements taken every square inch in the
full width section. In particular, measurements of the thickness
and generation of the thickness map can be conducted through
ultrasonic measurements as is standard in the art.
[0036] Further, a sapphire ribbon described herein, and even at
least six or still even all of the concurrently produced sapphire
ribbons can have a total thickness variation (TTV) of no greater
than 2 mm, no greater than 1.8 mm, no greater than 1.6 mm, no
greater than 1.4 mm, no greater than 1.2 mm, no greater than 1.0
mm, no greater than 0.8 mm, no greater than 0.7 mm, no greater than
0.6 mm, no greater than about 0.5 mm, no greater than about 0.4 mm,
or even no greater than about 0.3mm. Total thickness variation is
measured by subtraction of the minimum thickness of a ribbon from
the maximum thickness of a ribbon. As used herein, both the minimum
thickness of a ribbon and the maximum thickness can be determined
by ultrasonic measurement at an interval of 1 measurement per
square inch. In particular embodiments, the TTV can be as described
above, and if any voids are present, the thickness measurements in
and about the void are not included in the determination of the
TTV. In other words, the minimum thickness, for the purposes of a
TTV calculation, can be the minimum, non-zero thickness. In such
embodiments, any zero measurements determined in the thickness maps
are not used as the minimum thickness for the purposes of a TTV
calculation.
[0037] Moreover, a particular advantage of the present disclosure
is the ability to concurrently form a plurality of sapphire, with
the outer ribbons, at least six ribbons, or even all of the
plurality of concurrently produced sapphire ribbons have the total
thickness variation (TTV) described above. Such a characteristic
can be quantified by the variability of total thickness variation
between each of the plurality of concurrently formed sapphire
ribbons. The variability of total thickness variation can be
determined by the following formula:
VTTV=((TTV.sub.i-TTV.sub.AVG)/(TTV.sub.AVG))*100%
[0038] wherein VTTV represents the variability of total thickness
variation; TTV.sub.i represents the total thickness variation of
the sapphire ribbon of interest and TTV.sub.AVG represents the mean
average of the total thickness variation of all concurrently
produced sapphire ribbons in a batch. Again, each total thickness
variation measurement is determined by subtracting the minimum
thickness value from the maximum thickness value within a ribbon.
In particular embodiments, the variability of total thickness
variation can be no greater than about .+-.50%, no greater than
.+-.40%, no greater than .+-.30%, no greater than .+-.15%, no
greater than about .+-.10%, no greater than about .+-.7%, no
greater than about .+-.5%, no greater than bout .+-.3%, or even no
greater than about .+-.2%.
[0039] In still further embodiments, a sapphire ribbon described
herein, and even at least six or still even all of the concurrently
produced sapphire ribbons can have a maximum low spot thickness (or
minimum thickness) of at least about 2.0 mm, at least about 1.8 mm,
at least about 1.6 mm, at least about 1.4 mm, at least about 1.2
mm, at least about 1.0 mm, at least about 0.8 mm, at least about
0.7 mm, at least about 0.6 mm, or even at least about 0.5 mm. In
particular embodiments, a sapphire ribbon described herein, and
even at least six or still even all of the concurrently produced
sapphire ribbons can have a maximum low spot thickness of at least
about 1.0 mm, and in even more particular embodiments, at least
about 0.5 mm. The maximum low spot thickness is a measurement of
the lowest thickness on the entire sapphire ribbon in the
measurement zone. The maximum low spot thicknesses are measured by
standard techniques for thickness, such as calipers, drop gauges,
micrometers, or ultrasound. Moreover, another particular advantage
of the present disclosure is the ability to concurrently form a
plurality of sapphire ribbons, with the outer ribbons and even all
of the plurality of sapphire ribbons having the maximum low spot
thickness described above. A maximum low spot thickness of 0 would
indicate a void present in the ribbon.
[0040] In still further embodiments, a sapphire ribbon described
herein, and even each concurrently produced sapphire ribbon can
have a standard deviation from planar of no greater than 2 mm, no
greater than 1.8 mm, no greater than 1.6 mm, no greater than 1.4
mm, no greater than 1.2 mm, no greater than 1.0 mm, no greater than
0.8 mm, no greater than 0.7 mm, no greater than 0.6 mm, no greater
than about 0.5 mm, no greater than about 0.4 mm, or even no greater
than about 0.3 mm. The standard deviation from planar is a
measurement of the variance from a planar orientation in the
sapphire ribbon. The standard deviation from planar can be measured
by standard techniques for thickness, such as calipers, drop
gauges, micrometers, or ultrasound. Moreover, another particular
advantage of the present disclosure is the ability to concurrently
form a plurality of sapphire ribbons, with the outer ribbons and
even all of the plurality of sapphire ribbons having the standard
deviation from planar described above.
[0041] A particular advantage of the present disclosure is the
ability to concurrently form a plurality of sapphire ribbons, where
each of the plurality of sapphire ribbons, and particularly the
outer ribbons are essentially free of voids. As used herein,
"voids" refers to a defect in a single crystal ribbon in which
there is a gap or aperture within the ribbon. Further, as used
herein, "essentially free of voids" refers to a single crystal
ribbon in which there is no discontinuation of sapphire across the
width of the crystal, that is the crystal has a thickness greater
than 0. It has heretofore been unknown how to concurrently form a
plurality of sapphire ribbons, where each of the sapphire ribbons
is essentially free of voids. For example, as will be described in
more detail below in the EXAMPLE section, adding dies to a
traditional EFG apparatus produced crystal ribbons on the outer
dies with substantial voiding and inconsistent dimensional
stability. Without wishing to be limited by theory, it is believed
that in a traditional EFG growth apparatus, the temperature and the
thermal gradient on the outer ribbons is different than the inner
ribbons. It is believed that the inconsistent thermal gradient
between ribbons may cause defects such as voiding and variation in
total thickness variation, particularly in the outer ribbons.
Accordingly, in certain embodiments described herein, each
concurrently formed sapphire ribbon can be essentially free of
voids, and in particular embodiments, the outer ribbons, at least
six ribbons, or even all of the concurrently produced ribbons can
be essentially free of voids.
[0042] According to another embodiment of the present disclosure, a
method of concurrently forming a plurality of sapphire ribbons can
include providing an EFG apparatus having a plurality of dies;
crystallizing the plurality of ribbons, particularly sapphire
ribbons above each of the plurality of dies; and cooling the
plurality of sapphire ribbons. Cooling the plurality of sapphire
ribbons can include controlling a first thermal gradient in a first
region adjacent the die and controlling a second thermal gradient
in a second region adjacent the first region and further away from
the die than the first region. The second thermal gradient can be
lower than the first thermal gradient such that the ribbons are
cooled faster in the first region than in the second region. The
thermal gradients in the first or second region can be partially
controlled with a heat reflective shield. In certain embodiments,
the heat reflecting shield can be angled with respect to the
horizontal plane as described above.
[0043] A particular advantage of the present disclosure is the
ability to control the first and second thermal gradients (most
importantly the first thermal gradient) such that the thermal
gradients are consistent or have a low variability between the
plurality of sapphire ribbons. For example, in a traditional EFG
growth apparatus, it has not been possible to control the first
thermal gradient such that each of the first thermal gradients in
each of the concurrently formed sapphire ribbons are greater than
about 1.5.degree. C./cm, greater than about 2.degree. C./cm,
greater than about 3.degree. C./cm, greater than about 5.degree.
C./cm, 10.degree. C./cm, greater than about 20.degree. C./cm,
greater than about 50.degree. C./cm, greater than about 100.degree.
C./cm, greater than about 200.degree. C./cm, greater than about
500.degree. C./cm or even greater than about 1000.degree.
C./cm.
[0044] In particular embodiments, the sapphire ribbons can have a
dwell time of at least about 10 minutes in the first region. As
used herein, "dwell time" refers to the length of time a point on
the ribbon spends within a region of the EFG apparatus. As
discussed above, the first region is between the die opening and
the second region.
[0045] In an EFG apparatus, the plurality of ribbons are "pulled"
from the melt and crystallized above the die to form the ribbons.
The rate at which the ribbons are pulled from the melt is referred
to the draw rate. In certain embodiments, the draw rate of each of
the plurality of ribbons can be the same or at least one can be
different. In particular embodiments, the sapphire ribbons can be
drawn at a rate of 0.5 cm/hr, 1.0 cm/hr, 1.5 cm/hr, 2.0 cm/hr, 2.5
cm/hr, at least 5 cm/hr, or even at least 10 cm/hr.
[0046] As used herein, "spread" or "spreading" refers to the
forming of the width dimension of the crystal ribbon during
crystallization and cooling. Without wishing to be bound by theory,
it is believed controlling the thermal gradients can, in part,
control the spreading of the crystal ribbon. A particular advantage
of the present disclosure is the ability to achieve a consistent
spread width between each of the plurality of sapphire ribbons
produced in a batch.
[0047] Further in certain embodiments, the method can include
controlling the spread length of the plurality of crystal ribbons
such that the plurality of crystal ribbons have a maximum spread
length variability of no greater than about 25%, no greater than
about 20%, no greater than about 18%, no greater than about 15%, no
greater than about 10%, or even no greater than about 5%. As used
herein, "spread length" refers to the distance between the seed and
the full width section. Maximum spread length variability is
determined by the following equation:
SLV.sub.MAX=((SL.sub.MAX-SL.sub.MIN)/((SL.sub.MAX+SL.sub.MIN)/2))*100%
[0048] wherein SLV.sub.MAX refers to the maximum spread length
variability; SL.sub.MAX refers to the maximum spread length of one
of the plurality of sapphire ribbons produced in a batch; and
SL.sub.MIN refers to the minimum spread length of one of the
plurality of sapphire ribbons produced in a batch. A particular
advantage of the present disclosure is the ability to achieve a
consistent spread length between the plurality of sapphire ribbons
produced in a batch.
[0049] According to certain embodiments, the plurality of sapphire
ribbons produced by the methods described herein can have the
characteristics described herein such as the total thickness
variation, variability of total thickness variation, maximum low
spot thickness, standard deviation from planarity, etc. A
particular advantage of the present disclosure is the ability to
concurrently form a plurality of sapphire ribbons, with each of the
sapphire ribbons have the characteristics described herein. In
particular, the method described herein can be used to concurrently
form at least 3, at least 4, at least 5, at least 6, at least 7, at
least 8, at least 9, at least 10, at least 11, at least 12, at
least 13, at least 14, at least 15, or even at least 16 sapphire
ribbons, where each of the ribbons has the characteristics
described herein. Further, in certain embodiments, the method
described herein can be used to concurrently for no more than 50,
no more than 25, or even no more than 20 sapphire ribbons in the
same growth apparatus.
[0050] In fact, it has never before been possible to concurrently
produce 6 or more sapphire sheets in the same growth apparatus with
each of concurrently produced ribbons having the dimensional
stability described herein. Accordingly, certain embodiments
described herein are directed to producing 6 or more ribbons,
wherein at least 6 of the 6 or more ribbons have the
characteristics described herein, such as total thickness variation
and variability of total thickness variation.
[0051] Furthermore, embodiments of the present disclosure are
further directed to a batch of sapphire ribbons. As used herein, a
"batch" refers to a plurality of sapphire ribbons concurrently
(simultaneously) formed in the same growth apparatus. For example,
a batch can include at least 3, at least 4, at least 5, at least 6,
at least 7, at least 8, at least 9, at least 10, at least 11, at
least 12, at least 13, at least 14, at least 15, or even at least
16 sapphire ribbons that are concurrently formed in the same growth
apparatus. Further, in certain embodiments, a batch can include no
more than 50, no more than 25, or even no more than 20 sapphire
ribbons that are currently formed in the same growth apparatus.
[0052] In particular embodiments, each of the sapphire ribbons in
the batch can have the characteristics described herein such as
total thickness variation, variability of total thickness
variation, maximum low spot thickness, standard deviation from
planarity, be essentially free of voids, etc. A particular
advantage of the present disclosure is the ability to form a batch
of sapphire ribbons, with each of the sapphire ribbons in the batch
having the characteristics described herein.
[0053] The sapphire ribbons described herein can be further
processed to form a multitude of various products. In particular
embodiments, the sapphire ribbons can be cut to form wafers, and
particularly a batch of wafers. As used herein a "batch of wafers"
refers to wafers formed from a plurality of concurrently formed
sapphire ribbons. Moreover, in still further embodiments, a light
emitting device can be formed from the wafer, or a plurality of
light emitting devices can be formed from the batch of wafers.
[0054] In even further embodiments, a protector screen for mobile
devices can be formed from the sapphire ribbon described herein.
The formation of the protector screen can be performed according to
any method known in the art.
[0055] In even further embodiments, a transparent window that
transmits in the visible spectra may be formed from the sapphire
ribbon described herein.
[0056] The EFG apparatus, and the sapphire ribbons produced
therefrom can have any desired crystal orientation. In certain
embodiments, the sapphire ribbons can have a C-axis, an A-axis, an
R-axis, a M-axis, a N-axis, or an S-axis orientation substantially
perpendicular to the sapphire ribbon's major surface. In certain
particular embodiments, the sapphire ribbons can have a C-axis, an
A-axis, or an R-axis orientation substantially perpendicular to the
sapphire ribbon's major surface. In particular embodiments, the
sapphire ribbons have a C-axis orientation substantially
perpendicular to the sapphire ribbon's major surface. In other
particular embodiments, the sapphire ribbons have an A-axis
orientation substantially perpendicular to the sapphire ribbon's
major surface. The crystal orientation can be determined by seeding
a melt fixture with a seed having known, desired orientation
substantially perpendicular to a longitudinal axis of a die
opening. The thus formed ribbon will then have a corresponding
orientation substantially perpendicular to the sapphire ribbon's
major surface.
EXAMPLES
Example 1
[0057] Three batches of C-plane sapphire ribbons and one batch of
A-plane ribbons were produced. The first batch (Batch A; C-plane)
was produced using an EFG growth apparatus depicted in FIG. 1
except with a vertical heat shield. The second batch (Batch B;
C-plane) was produced using the EFG growth apparatus depicted in
FIG. 1 with a heat shield have an angle of 62 degrees with the
horizontal plane. A third batch (Batch C; C-plane) was produce
using the same EFG growth apparatus for Batch B except the height
of the most outer dies was lowered by 0.635 mm and the dies
adjacent the most outer dies was raised by 0.635 mm. The fourth
batch (Batch D; A-plane) was produced using the same EFG growth
apparatus as Batch C except that an A-plane sheet was grown using a
seed orientated in the A-plane. Each apparatus was configured with
10 dies and each run produced a batch of 10 C-plane or A-plane
sapphire ribbons. All other conditions parameters for growth were
identical except for minor adjustments to accommodate A-plane
growth.
[0058] For each of the batches, the crucible and die is heated
until the top of the die is greater than 2100 degrees C. Alumina
pellets are loaded into the crucible through a tube that extends
outside of the furnace and is protected by an inert atmosphere,
such as argon. Once the melt level is higher than about half of the
die height, a seed having a C-axis (or A-axis for A-plane)
orientation perpendicular to the growth direction is lowered to the
die tips. The temperature of the die is lowered, and the seed is
pulled vertically away from the die at a rate of 27.94 mm/hr. The
temperature is controlled as function of the mass. Once the crystal
is at full width, and the temperature remains constant until the
desired length has been achieved.
[0059] Various characteristics of each of the sapphire ribbons in
the batches were measured and the following results were
obtained:
TABLE-US-00002 TABLE 1 Property Batch A Batch B Batch C Batch D
Mean Average Length 434.34 mm 457.2 mm 609.6 mm 760 mm Mean Average
Width 157.48 mm 147.32 mm 157.48 mm 157.48 mm (after spreading)
Mean Average Thickness 2.5146 mm 2.4892 mm 2.667 mm 2.819 mm
Maximum Thickness 2.9718 mm 2.8956 mm 2.8956 mm 3.023 mm Minimum
Thickness 0 mm 2.159 mm 2.0828 mm 2.540 mm Maximum Width 157.48 mm
157.48 mm 157.48 mm 157.48 mm Minimum Width 157.48 mm 139.7 mm
157.48 mm 157.48 Maximum Total 2.7178 mm 0.6096 mm 0.381 mm 0.406
mm Thickness Variation Mean Average Total 0.7112 mm 0.381 mm 0.254
mm 0.254 mm Thickness Variation Maximum Variance in 2.5654 mm
0.4826 mm 0.254 mm 0.406 mm Total Thickness Variation Maximum
Spread 254 mm 254 mm 203.2 mm 208.3 mm Length (ribbon #1) (ribbon
#7) (#8,9) (#9) Minimum Spread Length 177.8 mm 152.4 mm 152.4 mm
152.4 mm (ribbon #4,5,6) (ribbon #1,10) (#4,5,6) (#2, #5) Maximum
Spread 76.2 mm 101.6 mm 50.8 mm 50.8 mm Length Variability Presence
of Voids in Yes No No No Outer Ribbons
[0060] Each of the thickness measurements and values discussed in
Table 1 above are determined from a generated thickness map. To
produce the thickness map, the thickness of the ribbon is measured
every square inch and mapped on an image of the ribbon as described
in more detail above and understood by one of ordinary skill in the
art. The table above indicates that Batch C resulted in the best
results with the most consistency in the dimensional control
between the C-plane sapphire ribbons. Batch D indicates that
A-plane ribbons also benefit from the changes incorporated in the
die for Batch C, as results similar to Batch A would be obtained
for A-plane ribbons using the Batch A die configuration.
[0061] Pictures of each of the C-plane sapphire ribbons were taken
on graph paper to show dimensions of the ribbons and thickness maps
of each of the ribbons were produced. FIG. 4 illustrates a
photograph of each of the ribbons produced in Batch A. FIG. 5
illustrates a photograph of each of the ribbons produced in Batch
B; FIG. 6 illustrates a photograph of each of the ribbons produced
in Batch C. Voids were visually apparent in the outer dies of Batch
A, but no voids existed in the ribbons of Batch B or C.
Example 2
[0062] The same apparatus and method provided for Batches C and D
above were used in an EFG growth apparatus with 16 dies. Similar
results to that achieved with Batches C and D were present in the
sapphire sheets, and particularly the outer sapphire sheets, when
growing 16 concurrent sapphire sheets.
[0063] Many different aspects and embodiments are possible. Some of
those aspects and embodiments are described below. After reading
this specification, skilled artisans will appreciate that those
aspects and embodiments are only illustrative and do not limit the
scope of the present invention. Embodiments may be in accordance
with any one or more of the items as listed below.
[0064] Item 1. An apparatus for forming a sapphire ribbon via
Edge-Defined Film-Fed Growth (EFG), the apparatus comprising a heat
reflective shield angled with respect to a horizontal plane,
wherein the heat reflective shield is configured to control a
thermal gradient from reflected heat in a lateral direction and a
vertical direction.
[0065] Item 2. An apparatus for concurrently forming at least six
sapphire ribbons, wherein at least six of the at least six sapphire
ribbons are essentially free of voids.
[0066] Item 3. An apparatus for concurrently forming at least six
sapphire ribbons, wherein at least six of the at least six sapphire
ribbons have an average width of at least 101.6 mm.
[0067] Item 4. An apparatus for forming a sapphire ribbon, the
apparatus comprising: [0068] a melt source; [0069] a die adjacent
the melt source; [0070] a first region adjacent an opening of the
die; and [0071] a heat reflective shield adjacent at least a
portion of the die and at least a portion of the first region,
wherein the heat reflective shield comprises a first surface facing
the die and a second surface opposite the first surface, wherein
the heat reflective shield is configured to direct heat energy
contacting the first surface of the heat reflective shield towards
a region of lower temperature.
[0072] Item 5. An apparatus for concurrently forming at least six
ribbons comprising sapphire, the apparatus comprising: [0073] a
melt source; [0074] at least six dies adjacent the melt source,
wherein each die has a length and a width; [0075] at least three
first regions adjacent each opening of the at least three dies,
wherein the at least three first regions have a width and a
thickness corresponding to a width and thickness of the die
opening, and wherein each of the at least three first regions has a
corresponding first thermal gradient across the thickness of the
first region, and wherein each of the at least three first thermal
gradients have a temperature gradient of at least 1.5 .degree.
C./min.
[0076] Item 6. A method of concurrently forming at least six
ribbons comprising sapphire, the method comprising: [0077]
crystallizing the at least six ribbons of crystal above at least
six dies, and [0078] cooling the at least six ribbons of crystal in
a first region adjacent the at least six dies, wherein cooling
comprises controlling a thermal gradient across a thickness of the
at least six ribbons of crystal such that each of the at least six
ribbons have a total thickness variation of no greater than 5%
after cooling has finished.
[0079] Item 7. A method of concurrently forming at least six
ribbons comprising sapphire, the method comprising: [0080] a.
crystallizing the at least six ribbons above at least six dies, and
[0081] b. controlling the spread length of each of the sapphire
ribbons such that a maximum spread length variability of at least
six of the at least six ribbons is no greater than about 25%.
[0082] Item 8. A batch of at least six concurrently EFG grown
sapphire ribbons, wherein at least six of the at least six EFG
grown sapphire ribbons have a total thickness variation of no
greater than 10%.
[0083] Item 9. A batch of at least six concurrently EFG grown
sapphire ribbons, wherein at least six of the at least six EFG
grown sapphire ribbons in the batch are essentially free of
voids.
[0084] Item 10. A batch of at least six concurrently EFG grown
sapphire ribbons, wherein at least six of the at least six EFG
grown sapphire ribbons in the batch have a maximum spread length
variability of no greater than about 20%.
[0085] Item 11. A batch of at least six concurrently EFG grown
sapphire ribbons, wherein at least six of the at least six EFG
grown sapphire ribbons in the batch have an average width of at
least 101.6 mm.
[0086] Item 12. A sapphire ribbon grown from an outer die in an EFG
growth apparatus configured to simultaneously produce at least six
sapphire ribbons, wherein the sapphire ribbon grown from the outer
die have a thickness variation within 10% of the average thickness
of each of the sapphire ribbons produced simultaneously with the
sapphire ribbons grown from the outer dies.
[0087] Item 13. A crystal ribbon grown from an outer die in an EFG
growth apparatus configured to simultaneously produce at least
eight crystal ribbons, wherein the crystal ribbon is essentially
free of voids.
[0088] Item 14. A wafer cut from an outer sapphire crystal ribbon
grown concurrently with at least 6 sapphire crystal ribbons.
[0089] Item 15. A light-emitting device made from the sapphire
wafer of item 14.
[0090] Item 16. A sapphire protector screen for mobile devices
formed from an outer crystal ribbon grown concurrently with at
least 6 crystal ribbons.
[0091] Item 17. The apparatus, method, batch or ribbon of any one
of the preceding items, wherein the crystal ribbons have an average
width of at least about 101.6 mm, at least about 152.4 mm, at least
about 203.2 mm, or even at least about 0.304.8 mm.
[0092] Item 18. The apparatus, method, ribbon, or batch of any one
of the preceding items, wherein the crystal ribbons have an average
length of at least about 152.4 mm, at least about 304.8 mm, at
least about 609.6 mm, or even at least about 762 mm.
[0093] Item 19. The apparatus or method of any one of the preceding
items, wherein the heat reflective shield is angled with respect to
a forming plane.
[0094] Item 20. The apparatus, method, ribbon, or batch of any one
of the preceding items, wherein the one or more sapphire ribbons
have an average thickness of at least about 0.1 mm, at least about
0.5 mm, at least about 0.8 mm, at least about 1 mm, at least about
1.3 mm, at least about 1.5 mm, at least about 1.7 mm, at least
about 2.0 mm, or even at least about 2.3 mm.
[0095] Item 21. The apparatus, method, ribbon, or batch of any one
of the preceding items wherein the one or more sapphire ribbons
have an average thickness of no greater than about 100 mm, no
greater than about 75 mm, no greater than about 50 mm, no greater
than about 35 mm, no greater than about 25 mm, no greater than
about 15 mm, no greater than about 10 mm, or even no greater than
about 5 mm.
[0096] Item 22. The apparatus, method, ribbon, or batch of any one
of the preceding items, wherein each sapphire ribbon has a Total
Thickness Variation of no greater than 2 mm, no greater than 1.8
mm, no greater than 1.6 mm, no greater than 1.4 mm, no greater than
1.2 mm, no greater than 1.0 mm, no greater than 0.8 mm, no greater
than 0.7 mm, no greater than 0.6 mm, no greater than about 0.5 mm,
no greater than about 0.4 mm, or even no greater than about 0.3
mm
[0097] Item 23. The apparatus, method, ribbon, or batch of any one
of the preceding items, wherein each sapphire ribbon has a Total
Thickness Variation of no greater than 2 mm, no greater than 1.8
mm, no greater than 1.6 mm, no greater than 1.4 mm, no greater than
1.2 mm, no greater than 1.0 mm, no greater than 0.8 mm, no greater
than 0.7 mm, no greater than 0.6 mm, no greater than about 0.5 mm,
no greater than about 0.4 mm, or even no greater than about 0.3 mm,
and wherein the TTV is determined without including any voids.
[0098] Item 24. The apparatus, method, ribbon, or batch of any one
of the preceding items, wherein the variability of total thickness
variation between the total number of concurrently formed ribbons
can be no greater than about .+-.50%, no greater than .+-.40%, no
greater than .+-.30%, no greater than .+-.15%, no greater than
about .+-.10%, no greater than about .+-.7%, no greater than about
.+-.5%, no greater than bout .+-.3%, or even no greater than about
.+-.2%.
[0099] Item 25. The apparatus, method, ribbon, or batch of any one
of the preceding items, wherein each sapphire ribbon has a maximum
low spot thickness of at least about 2.0 mm, at least about 1.8 mm,
at least about 1.6 mm, at least about 1.4 mm, at least about 1.2
mm, at least about 1.0 mm, at least about 0.8 mm, at least about
0.7 mm, at least about 0.6 mm, or even at least about 0.5 mm.
[0100] Item 26. The apparatus or method of any one of the preceding
items, wherein the heat reflective shield forms an angle with a
forming plane of no greater than about 85 degrees, no greater than
about 80 degrees, no greater than about 75 degrees, or even no
greater than about 70 degrees.
[0101] Item 27. The apparatus or method of any one of the preceding
items, wherein the heat reflective shield forms an angle of no less
than about 1 degrees, no less than about 2 degrees, no less than
about 3 degrees, no less than about 4 degrees, no less than about 5
degrees, no less than about 10 degrees, no less than about 15
degrees, no less than about 20 degrees, no less than about 25
degrees, no less than about 30 degrees, no less than about 35
degrees, no less than about 40 degrees, no less than about 45
degree, no less than about 50 degrees, no less than about 55
degrees, or even no less than about 60 degrees.
[0102] Item 28. The apparatus or method of any one of the preceding
items, wherein the heat reflective shield comprises a metal, in
particular a refractory metal.
[0103] Item 29. The apparatus or method of any one of the preceding
items, wherein the heat reflective shield is positioned such that a
significant portion of heat radiating laterally from the first
region is reflected toward an area of lower temperature.
[0104] Item 30. The apparatus or method of any one of the preceding
items, wherein the heat reflective shield is disposed adjacent to
the first region.
[0105] Item 31. The apparatus or method of any one of the preceding
items, wherein the first thermal gradient extends along the forming
plane for a distance of at least about 1 cm, at least about 2 cm,
at least about 3 cm, at least about 5 cm, or even at least about 10
cm.
[0106] Item 32. The apparatus or method of any one of the preceding
items, further comprising a second thermal gradient adjacent to the
first thermal gradient, wherein the second thermal gradient is
further away from the die opening than the first thermal gradient,
and wherein the second thermal gradient is less than the first
thermal gradient.
[0107] Item 33. The apparatus or method of any one of the preceding
items, wherein the die opening has a width of at least 25.4 mm, at
least 50.8 mm, at least 76.2 mm, at least 101.6 mm, at least 152.4
mm, or even at least 203.2 mm.
[0108] Item 34. The apparatus or method of any one of the preceding
items, wherein the die opening has a thickness of at least 0.3 mm,
at least 0.6 mm, at least 0.75 mm, at least about 1 mm, at least
about 1.5 mm, at least about 2 mm, at least about 2.5 mm, at least
about 2.8 mm, at least about 3 mm, or even at least about 3.5
mm.
[0109] Item 35. The apparatus or method of any one of the preceding
items, wherein a ratio of the average thickness of the sapphire
ribbon to the thickness of the die opening is at least about
0.95:1.
[0110] Item 36. The method of any one of the preceding items,
wherein the dwell time of a specific point on the sapphire ribbon
in the first region is at least 10 minutes.
[0111] Item 37. The method of any one of the preceding items,
further comprising drawing the sapphire ribbon at a rate of at
least 0.5 cm/hr, at least 1.0 cm/hr, at least 1.5 cm/hr, at least
2.5 cm/hr, at least 5 cm/hr, or even at least 10 cm/hr.
[0112] Item 38. The apparatus or method of any one of the preceding
items, wherein the outer die openings are disposed higher than at
least one die opening between the outer die openings.
[0113] Item 39. The apparatus or method of any one of the preceding
items, wherein at least one die openings is disposed at a different
height than the other die openings.
[0114] Item 40. The apparatus, method, batch, or ribbon of any one
of the preceding items, wherein the one or more sapphire ribbons
have a C-axis, an A-axis, M-axis or an R-axis orientation
substantially perpendicular to the sapphire ribbon's major
surface.
[0115] Item 41. The apparatus, method, batch, or ribbon of any one
of the preceding items, wherein the one or more sapphire ribbons
have a C-axis orientation substantially perpendicular to the
sapphire ribbon's major surface.
[0116] Item 42. The method of any one of the preceding items,
further comprising seeding a melt fixture with a seed having an
A-axis, a C-axis, M-axis or a R-axis orientation substantially
perpendicular to a longitudinal axis of a die opening; and wherein
the sapphire ribbon has a corresponding A-axis, C-axis, M-axis or
R-axis orientation substantially perpendicular to the sapphire
ribbon's major surface.
[0117] Item 43. The method of any one of the preceding items,
further comprising seeding one or more melt fixtures with a seed
having a C-axis orientation substantially perpendicular to a
longitudinal axis of a die opening; and wherein the one or more
sapphire ribbons have a corresponding C-axis orientation
substantially perpendicular to the one or more sapphire ribbon's
major surface.
[0118] Item 44. A batch of at least six concurrently EFG grown
sapphire ribbons, wherein at least six of the at least six EFG
grown sapphire ribbons have a total thickness variation of no
greater than 10%.
[0119] Item 45. A batch of at least six concurrently EFG grown
sapphire ribbons, wherein at least six of the sapphire ribbons in
the batch are essentially free of voids.
[0120] Item 46. The batch of any one of the preceding items,
wherein at least six of the sapphire ribbons in the batch have an
average width of at least about 101.6 mm.
[0121] Item 47. The batch of any one of the preceding items,
wherein at least six of the sapphire ribbons in the batch have an
average length of at least about 152.4 mm.
[0122] Item 48. The batch of any one of the preceding items,
wherein at least six of the sapphire ribbons in the batch have an
average thickness in a range of from about 0.1 mm to about 100
mm.
[0123] Item 49. The batch of any one of the preceding items,
wherein at least six of the sapphire ribbons in the batch have a
Total Thickness Variation (TTV) of no greater than 2 mm.
[0124] Item 50. The batch of any one of the preceding items,
wherein two sapphire ribbons grown from outer dies in the batch
have a Total Thickness Variation (TTV) of no greater than 1.2
mm.
[0125] Item 51. The batch of any one of the preceding items,
wherein at least six of the sapphire ribbons in the batch have a
Total Thickness Variation (TTV) of no greater than 2 mm, and
wherein the TTV is determined without including any voids.
[0126] Item 52. The batch of any one of the preceding items,
wherein at least six of the sapphire ribbons in the batch have a
Total Thickness Variation (TTV) of no greater than 1.2 mm, and
wherein the TTV is determined without including any voids.
[0127] Item 53. The batch of any one of the preceding items,
wherein the variability of total thickness variation between the
total number of concurrently formed ribbons is no greater than
about .+-.50%.
[0128] Item 54. The batch of any one of the preceding items,
wherein the variability of total thickness variation between the
total number of concurrently formed ribbons is no greater than
about .+-.10%.
[0129] Item 55. The batch of any one of the preceding items,
wherein each of the at least six of the at least six EFG grown
sapphire ribbons have a total thickness variation of no greater
than 5%.
[0130] Item 56. The batch of any one of the preceding items,
wherein at least six of the sapphire ribbons in the batch have a
maximum low spot thickness of at least about 1 mm.
[0131] Item 57. The batch of any one of the preceding items,
wherein at least six of the sapphire ribbons in the batch have a
maximum low spot thickness of at least about 0.5 mm.
[0132] Item 58. The batch of any one of the preceding items,
wherein the one or more sapphire ribbons in the batch have a
C-axis, an A-axis, M-axis or an R-axis orientation substantially
perpendicular to the sapphire ribbon's major surface.
[0133] Item 59. The batch of any one of the preceding items,
wherein the one or more sapphire ribbons have an A-axis orientation
substantially perpendicular to the sapphire ribbon's major
surface.
[0134] Item 60. The batch of any one of the preceding items,
wherein the batch comprises at least 8 sapphire ribbons.
[0135] Item 61. The batch of any one of the preceding items,
wherein the batch comprises at least 10 sapphire ribbons.
[0136] Item 62. A sapphire ribbon grown from an outer die in an EFG
growth apparatus configured to simultaneously produce at least six
sapphire ribbons, wherein the sapphire ribbon grown from the outer
die has a thickness variation within 10% of the average thickness
of each inner sapphire ribbon produced simultaneously with the
sapphire ribbon grown from the outer die.
[0137] Item 63. The sapphire ribbon of item 62, wherein the
sapphire ribbon grown from an outer die is essentially free of
voids.
[0138] Note that not all of the activities described above in the
general description or the examples are required, that a portion of
a specific activity may not be required, and that one or more
further activities may be performed in addition to those described.
Still further, the order in which activities are listed is not
necessarily the order in which they are performed.
[0139] Benefits, other advantages, and solutions to problems have
been described above with regard to specific embodiments. However,
the benefits, advantages, solutions to problems, and any feature(s)
that may cause any benefit, advantage, or solution to occur or
become more pronounced are not to be construed as a critical,
required, or essential feature of any or all the claims.
[0140] The specification and illustrations of the embodiments
described herein are intended to provide a general understanding of
the structure of the various embodiments. The specification and
illustrations are not intended to serve as an exhaustive and
comprehensive description of all of the elements and features of
apparatus and systems that use the structures or methods described
herein. Separate embodiments may also be provided in combination in
a single embodiment, and conversely, various features that are, for
brevity, described in the context of a single embodiment, may also
be provided separately or in any subcombination. Further, reference
to values stated in ranges includes each and every value within
that range. Many other embodiments may be apparent to skilled
artisans only after reading this specification. Other embodiments
may be used and derived from the disclosure, such that a structural
substitution, logical substitution, or another change may be made
without departing from the scope of the disclosure. Accordingly,
the disclosure is to be regarded as illustrative rather than
restrictive.
* * * * *