U.S. patent application number 15/083664 was filed with the patent office on 2016-11-03 for apparatus and method of cleaving thin layer from bulk material.
The applicant listed for this patent is Silicon Genesis Corporation. Invention is credited to Francois J. HENLEY.
Application Number | 20160319462 15/083664 |
Document ID | / |
Family ID | 48945785 |
Filed Date | 2016-11-03 |
United States Patent
Application |
20160319462 |
Kind Code |
A1 |
HENLEY; Francois J. |
November 3, 2016 |
APPARATUS AND METHOD OF CLEAVING THIN LAYER FROM BULK MATERIAL
Abstract
Embodiments relate to use of a particle accelerator beam to form
thin layers of material from a bulk substrate. In particular
embodiments, a bulk substrate (e.g. donor substrate) having a top
surface is exposed to a beam of accelerated particles. In certain
embodiments, this bulk substrate may comprise a core of crystalline
sapphire (Al.sub.2O.sub.3) material. Then, a thin layer of the
material is separated from the bulk substrate by performing a
controlled cleaving process along a cleave region formed by
particles implanted from the beam. Embodiments may find particular
use as hard, scratch-resistant covers for personal electric device
displays, or as optical surfaces for fingerprint, eye, or other
biometric scanning.
Inventors: |
HENLEY; Francois J.; (Aptos,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Silicon Genesis Corporation |
Santa Clara |
CA |
US |
|
|
Family ID: |
48945785 |
Appl. No.: |
15/083664 |
Filed: |
March 29, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13766522 |
Feb 13, 2013 |
9336989 |
|
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15083664 |
|
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61598283 |
Feb 13, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C30B 33/00 20130101;
Y10T 428/31515 20150401; C30B 33/04 20130101; Y10T 156/1052
20150115; C30B 29/20 20130101; Y10T 428/24479 20150115; H01J 37/31
20130101; H01J 2237/3109 20130101; C30B 33/06 20130101 |
International
Class: |
C30B 33/04 20060101
C30B033/04; H01J 37/31 20060101 H01J037/31; C30B 29/20 20060101
C30B029/20 |
Claims
1. An apparatus comprising a cleaved single crystal sapphire layer
having a thickness of between about 5 .mu.m to about 100 .mu.m.
2. An apparatus as in claim 1 further comprising a laminated
structure including an optical blank and an index matching material
positioned between the cleaved single crystal sapphire layer and
the optical blank.
3. An apparatus as in claim 2 wherein the cleaved single crystal
sapphire layer is free standing.
4. An apparatus as in claim 3 wherein the optical blank and index
matching material comprise a support.
5. An apparatus as in claim 2 wherein: the index matching material
comprises an index-matching fluid; and the optical blank comprises
quartz.
6. An apparatus as in claim 5 wherein an index of refraction of the
index-matching fluid results in an internal reflection at the
quartz/sapphire interface of less than 1%.
7. An apparatus as in claim 5 wherein: an index of refraction of
the index-matching fluid results in an internal reflection at the
quartz/sapphire interface of greater than 1%; and the index
matching material further comprises a dielectric stack matching
material.
8. An apparatus as in claim 2 wherein a surface of the cleaved
single crystal sapphire layer is defined by a fracture plane
resulting from hydrogen implantation.
9. An apparatus as in claim 8 wherein a Total Thickness Variation
(TTV) of the cleaved single crystal sapphire layer is +/-0.02
.mu.m.
10. An apparatus as in claim 9 wherein a roughness of the cleaved
single crystal sapphire layer is about 6 nm Ra.
11. An apparatus as in claim 9 wherein the fracture plane results
from hydrogen implantation by a linear accelerator at an energy of
1.75 MeV or greater.
12. An apparatus as in claim 9 wherein the laminated structure has
a thickness of between 400-600 .mu.m.
13. An apparatus as in claim 2 wherein the cleaved single crystal
sapphire layer reproduces a pseudo-square shape of a bulk core.
14. An apparatus as in claim 2 further comprising: a second cleaved
single crystal sapphire layer positioned on an opposite side of the
optical blank from the cleaved single crystal sapphire layer; and a
second index matching material positioned between the optical blank
and the second cleaved single crystal sapphire layer.
15. An apparatus as in claim 1 wherein the cleaved single crystal
sapphire layer is characterized by a miscut angle from a major
crystallographic axis.
16. An apparatus as in claim 15 wherein the cleaved single crystal
sapphire layer comprises c-cut oriented material.
17. An apparatus as in claim 1 wherein the cleaved single crystal
sapphire layer has other than a planar shape.
18. An apparatus as in claim 17 wherein the cleaved single crystal
sapphire layer is curved to match a lens profile.
19. An apparatus as in claim 1 wherein the apparatus comprises a
part of a cover for a display screen.
20. An apparatus as in claim 1 wherein the apparatus comprises an
optical surface of a biometric recognition device.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 13/766,522, filed Feb. 13, 2013, which claims priority to
U.S. Provisional Application No. 61/598,283, filed Feb. 13, 2012,
(Attorney Docket No. 83020-027600US-8319987), commonly owned,
incorporated by reference herein for all purposes.
BACKGROUND OF THE INVENTION
[0002] Embodiments of the present invention relate generally to
techniques including methods and apparatuses for forming layers
from a bulk material. Certain embodiments may employ an accelerator
process for the manufacture of films in a variety of applications
calling for a hard, scratch-resistant surface exhibiting
transparency to incident light, including but not limited to camera
lens covers, personal electric device display covers, and
fingerprint or eye biometric scan optical surfaces. But it will be
recognized that the invention has a wider range of applicability;
it can also be applied to opto-electronic devices such as light
emitting diodes (LEDs) and semiconductor lasers, three-dimensional
packaging of integrated semiconductor devices, photonic or
photovoltaic devices, piezoelectronic devices, flat panel displays,
microelectromechanical systems ("MEMS"), nano-technology
structures, sensors, actuators, integrated circuits, biological and
biomedical devices, and the like. It can also be used as a
protective laminate offering protection in harsh chemical and
temperature environments.
[0003] Certain embodiments may include methods and apparatuses for
cleaving films from material in bulk form, such as sapphire,
silicon carbide (SiC) or GaN ingots or cores. Conventionally, such
films can be manufactured by techniques involving the sawing of
bulk material. One example of sawing involves the use of a wire
("wiresaw").
[0004] However, such materials suffer from material losses during
conventional saw manufacturing called "kerf loss", where the sawing
process eliminates as much as 40% and even up to 60% of the
starting material in singulating the material from a core or boule
into an individual layer. This is an inefficient method of
preparing films from expensive starting materials. The brittle and
hard nature of many of these materials makes the manufacture of
large area thin layers particularly challenging.
[0005] From the above, it is seen that techniques for forming
suitable substrate materials of high quality and low cost are
highly desired. Cost-effective and efficient techniques for the
manufacture of hard, scratch-resistant films are also
desirable.
BRIEF SUMMARY OF THE INVENTION
[0006] Embodiments relate to use of a particle accelerator beam to
form thin layers of material from a bulk substrate. In particular
embodiments, a bulk substrate (e.g. donor substrate) having a top
surface is exposed to a beam of accelerated particles. In certain
embodiments, this bulk substrate may comprise a core of crystalline
sapphire (Al.sub.2O.sub.3) material. Then, a thin layer of the
material is separated from the bulk substrate by performing a
controlled cleaving process along a cleave region formed by
particles implanted from the beam. Embodiments may find particular
use as hard, scratch-resistant covers for personal electric device
displays, or as optical surfaces for fingerprint, eye, or other
biometric scanning.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a simplified process flow illustrating an
embodiment of a method.
[0008] FIG. 2A shows a photo of a 20 .mu.m thick silicon wafer
formed according to an embodiment.
[0009] FIG. 2B shows a photo of a 50 .mu.m thick silicon wafer
formed according to an embodiment.
[0010] FIG. 3 shows a sapphire laminated optical window according
to an embodiment.
[0011] FIG. 4 shows a cleave range for sapphire according to an
embodiment.
[0012] FIG. 5 is a table showing estimated cost of cleaving as a
function of a diameter of a sapphire core.
[0013] FIG. 6 shows a simplified view of an embodiment of a rig 600
for processing sapphire.
DETAILED DESCRIPTION OF THE INVENTION
[0014] According to embodiments of the present invention,
techniques including a method for forming substrates are provided.
More particularly, embodiments according to the present invention
provide a method to form a layer of hard, scratch-resistant layer
from a bulk material. In a specific embodiment, the layer of
material is provided using a plurality of high energy particles to
cause a formation of a cleave plane in the semiconductor substrate.
Methods according to embodiments of the invention can be used in a
variety of applications, including but not limited to transparent
coverings for optical displays, fingerprint or eye biometric scan
optical surfaces, optoelectronic devices, semiconductor device
packaging, photovoltaic cells, MEMS devices, and others.
[0015] According to certain embodiments, beam-induced cleave
technology may be used for the preparation of thin sapphire
laminated windows. According to particular embodiments, a 20 .mu.m
sapphire laminate (c-cut or a-cut) may be bonded to a suitable
optical blank. Examples of such optical blanks include but are not
limited to, polymers, glass, or quartz. If two-sided sapphire is
appropriate, a second sapphire laminate can be bonded to the
backside of the blank.
[0016] An objective is to substitute a potentially more efficient
and cost-effective kerfless wafering technology than current
wiresawing approaches. Single crystal sapphire core diameters of
2'', 3'', 4'', 6'', 8'' and 12'' in c-cut, a-cut, m-cut, or r-cut
orientations, comprise possible starting crystalline materials.
[0017] The above represent some of the main crystallographic
orientations of single crystal sapphire. For example, a c-cut
crystal means that the large face is parallel (cut) along the c
plane where the c-axis is perpendicular to the crystal surface.
Off-axis cuts are possible and are usually characterized by a
miscut angle from the major crystallographic axes. Accordingly,
certain embodiments may comprise material having an orientation
corresponding predominantly, but not exactly, to a cut orientation
of a major crystallographic axis. Since beam-induced cleaving is a
surface referenced method, cleaves will occur at a predefined depth
parallel to the crystal face.
[0018] Incorporated by reference herein for all purposes, is
Azhdari and Nemat-Nasser, "Experimental and computational study of
fracturing in an anisotropic brittle solid", Mechanics of
Materials, Vol. 28, pp. 247-262 (1998). That paper discusses the
structure of single crystal sapphire, including the orientations of
various possible cleave planes of that bulk material.
[0019] Since 1997, Silicon Genesis Corp. ("SiGen") has reported the
development and use of cleaving processes utilizing implanted
particles (including but not limited to protons). Incorporated by
reference herein for all purposes, is U.S. Pat. No. 6,013,563
describing various aspects of certain cleaving processes.
Embodiments described herein may share one or more characteristics
described in that patent.
[0020] According to particular embodiments, a surface of a bulk
starting material may be subjected to implantation with accelerated
particles, to form a cleave region. In certain embodiments, this
cleave region may lie at a depth of between about 10-20 .mu.m
underneath the surface of the bulk material. Formation of a cleave
region depends upon such factors as the target material, the
crystal orientation of the target material, the nature of the
implanted particle(s), the dose, energy, and temperature of
implantation, and the direction of implantation. Such implantation
is discussed further in detail below, and may share one or more
characteristics described in detail in connection with the
following patent applications, all of which are incorporated by
reference in their entireties herein: U.S. patent application Ser.
No. 12/789,361; U.S. patent application Ser. No. 12/730,113; U.S.
patent application Ser. No. 11/935,197; U.S. patent application
Ser. No. 11/936,582; U.S. patent application Ser. No. 12/019,886;
U.S. patent application Ser. No. 12/244,687; U.S. patent
application Ser. No. 11/685,686; U.S. patent application Ser. No.
11/784,524; U.S. patent application Ser. No. 11/852,088.
[0021] Since 2008, SiGen has reported the development and use of a
new beam-induced cleave process using a high-energy and high
fluence proton beam and a proprietary cleaving system technology to
initiate and guide a fracture for efficient kerf-free wafering of a
thickness of crystalline material. Incorporated by reference herein
for all purposes are the following U.S. Patent Publications
describing aspects of certain cleaving processes: 2008/0206962;
2008/0128641; 2009/0277314; and 2010/0055874.
[0022] Announced for the preparation of single-crystal silicon
solar PV wafers, the process is called PolyMax.TM. using Direct
Film Transfer (DFT) technology. The kerf-free, dry wafering process
uses a 2-step implant-cleave method shown in FIG. 1 where
high-energy proton irradiation first forms a cleave plane followed
by advanced controlled cleaving to initiate and propagate a
fracture plane in a controlled manner along the cleave plane to
release a large-area wafer from a shaped ingot.
[0023] The ion beam-induced cleaving process has been used to
demonstrate the slicing of full mono-crystalline silicon wafers
ranging in thickness from 20 .mu.m to 150 .mu.m with excellent
material quality (electrical, Total Thickness Variation (TTV),
surface roughness, mechanical strength).
[0024] FIGS. 2A-2B show 125 mm pseudo-square substrates made using
the PolyMax.TM. process. The substrate of FIG. 2A has a thickness
of 20 .mu.m. The substrate of FIG. 2B has a thickness of 50
.mu.m.
[0025] A system according to certain embodiments may allow the
cleaving of 20 .mu.m to 150 .mu.m thick silicon wafers directly
from CZ boules of silicon. However, this technology may also be
adapted to kerfless wafering of other types of crystalline bulk
materials, including but not limited to sapphire, Group III/V
materials such as GaN, SiC, and others.
[0026] The higher density of sapphire (3.98 g/cm.sup.3) versus that
of single crystal silicon (2.3 g/cm.sup.3) will lower the cleave
depth at a given energy of implanted particle. If adapted to work
with sapphire, a DFT system may cleave sapphire wafers between
5-100 .mu.m in thickness. Examples of sapphire layer thicknesses
cleaved according to various embodiments include but are not
limited to 5 .mu.m, 10 .mu.m, 15 .mu.m, 20 .mu.m, 25 .mu.m, 30
.mu.m, 35 .mu.m, 40 .mu.m, 45 .mu.m, 50 .mu.m, 55 .mu.m, 60 .mu.m,
65 .mu.m, 70 .mu.m, 75 .mu.m, 80 .mu.m, 85 .mu.m, 90 .mu.m, or 100
.mu.m. Greater thicknesses of cleaved materials are possible,
depending in part upon the energy to which the implanted particle
is able to be accelerated and its stopping range in the target
material.
[0027] Such a thin layer thickness could be used directly as a
lower cost alternative substrate to a 400-600 .mu.m sapphire
High-Brightness Light-Emitting Diode (HB-LED) starting substrate.
The kerf-free nature of the process in combination with lower
sapphire material utilization could substantially lower one of the
highest costs in GaN LED manufacturing. The same principle could be
applied to SiC and other starting growth substrates.
[0028] In order to create a material having a greater thickness
(e.g. 400-600 .mu.m), a laminated structure may be adopted. An
embodiment of a proposed laminated structure is shown in FIG. 3.
Depending on the particular application, one or two sapphire
laminates may be affixed onto an optical blank of approximately 400
.mu.m in thickness.
[0029] An index-matching interface layer may be used to affix the
laminates onto the blank. The final choice of the optical blank and
index-matching interface layer materials can be dependent on the
desired use.
[0030] For example, depending on the application's temperature
range, the interface layer can be an index-matching fluid, epoxy,
or some other material. Thus a quartz blank used in a wide
temperature range application, may employ an optical index-matched
fluid instead of an epoxy.
[0031] This would allow for differential thermal expansion
mismatch, and reduce the possibility of stress-induced fractures.
For the quartz example, its large differential thermal expansion
mismatch with sapphire would necessitate careful stress engineering
and possibly the use of an index matching fluid. Their respective
index of refraction would correspond to an internal reflection at
the quartz/sapphire interface of less than 1%. If this level is
unacceptable for the application, a quarter-wave or dielectric
stack matching coating in combination with the index-matching
interface layer could be applied to reduce internal reflections to
a desirable level.
[0032] If a laminated structure is used, FIG. 4 shows cleaving of
thinner wafers of about 20 .mu.m in thickness using a lower energy
and more compact implanter configuration. The chosen energy is
about 1.75 MeV to release approximately 20 .mu.m of material. An
operating energy of about 1.75 MeV would allow laminates of 20
.mu.m thickness to be released with little loss of material.
[0033] Use of a laminate window according to an embodiment may
offer one or more possible benefits versus a solid monolithic
sapphire layer. Examples of such possible benefits are provided
below.
A laminate window may require much smaller (about 30x less)
utilization of relatively expensive sapphire material per window.
The cost of kerf-free wafering is lower on an area basis, and may
be especially attractive with larger sapphire core diameters (6''
and up). The TTV of the laminate may be on the order of about
+/-0.02 By contrast, a solid sapphire window formed by conventional
wiresawing can exhibit a TTV greater than the proposed laminate
thickness (>+/-20 .mu.m) The as-cleaved roughness is expected to
be approximately 6 nm Ra. The smoothness of this material would not
demand substantial additional polishing steps.
[0034] Cost savings may be a function of the area of cleaving, and
is estimated in the table of FIG. 5. Using modified implant systems
developed for cleaving silicon substrates for the solar
photovoltaic industry, costs are estimated to be $0.05/cm.sup.2,
but can be modified by the packing density of the cores within the
scanned implant area of approximately 1 m.times.1 m.
[0035] The 8'' and 12'' cost range given in FIG. 5 is due to the
lower packing density of the large round cores within the implant
scan area. The lower number is for a squared core shape. Even with
rounded cores, the lower number may be approached using a patterned
beam scan that avoids the inter-core gaps. Using a 6'' core form
factor as an example, the cost comparison between wiresaw and DFT
windows can be estimated.
[0036] The table of FIG. 5 reflects a number of assumptions,
including a core cost of $150/mm, a wiresaw window core use of 600
.mu.m, and a DFT window core use (one side) of 20 .mu.m. Wiresaw
cost estimation was based upon: window cost=material cost
($90)+wiresaw cost+rough/fine/touch polish cost. The wiresaw cost
would include not only the actual sawing but the various clean and
singulation steps.
[0037] The DFT cost estimation was based upon: window cost=material
cost ($3)+cleave cost ($9)+touch polish cost+optical blank
cost+index-matching interface layer cost. This illustrates the
substantial cost reduction potential of the technology.
[0038] While the above description has focused upon a single
crystal layer of material having a planar shape, this is not
required. Alternative embodiments could form a single crystal layer
having other than a planar shape. For example, the single crystal
layer could be curved in order to match a profile of a lens such as
a cylindrical or spherical lens.
[0039] The various physical properties of sapphire, as contrasted
with other materials, may involve the use of one or more
techniques. For example, sapphire exhibits a low emissivity at
temperatures below about 800.degree. C. This makes detecting the
temperature of the bulk material during processing steps such as
implant and/or cleaving, difficult at lower temperatures.
[0040] Accordingly, FIG. 6 shows a simplified view of an embodiment
of a rig 600 for processing sapphire. In particular, the bulk
sapphire core 601 is supported by process chuck 602 within vacuum
chamber 604. Beam 606 of accelerated particles from source 607 is
implanted into the top surface 608 of the sapphire core.
[0041] On its bottom surface 610, the core bears a coating 612
comprising a material whose emissivity renders it suitable for
thermal measurement over the full range of temperatures expected to
be experienced during processing. Examples of such coatings include
but are not limited to metal or carbon. Accordingly the process rig
also includes a thermal detector 614 in communication with the
coating.
[0042] The emissive coating 612 may perform functions other than
temperature detection. For example, the coating may allow thermal
control over the bulk material by radiative cooling.
[0043] Indeed, such radiative cooling by a coating may offer a
practical cooling mechanism available to a sapphire core undergoing
processing (such as particle implantation) at temperatures of about
650-850.degree. C. Specifically as implantation is performed in a
vacuum environment, cooling by convection is not an option.
Moreover, the chuck may be selected to not have an appreciable
cooling path for the sapphire core undergoing implantation, thereby
substantially reducing or eliminating entirely the possibility of
cooling the sapphire core via conduction. If the implant heat flux
is matched to the coating's radiation cooling flux when the implant
surface reaches the desired implant temperature, the coating can
serve to control the implant at high temperatures without
additional complex and costly cooling methods.
[0044] U.S. Pat. No. 6,458,723 titled "High Temperature Implant
Apparatus", is hereby incorporated by reference in its entirety for
all purposes. One or more concepts disclosed in that patent may
find use according to various embodiments here. It is noted that
depending upon the particular material and the specific conditions
under which implantation occurs, the temperature could lie in a
range between about 50-900.degree. C. For implantation of sapphire,
the temperature range at implantation may range between about
650-850.degree. C.
[0045] Still another function that may be performed by a coating
due to its absorptive nature for heating the sapphire for annealing
and cleaving. Specifically, once particles have been introduced by
implantation, additional energ(ies) may need to be applied in order
to permit initiation and/or propagation of the cleaving process. In
certain embodiments, such energ(ies) may be provided in the form of
luminance, with the coating serving to absorb the applied light and
convert it into the thermal energy responsible for cleave
initiation and/or propagation.
[0046] Accordingly, the process rig may further comprise a source
616 of electromagnetic radiation, which may be applied to the
coating. Examples of such sources include but are not limited to
lamps such as QTH (Quartz Tungsten Halogen) flashlamps and
lasers.
[0047] It is further noted that certain electrical properties of
sapphire may dictate its being subjected to implantation at
elevated temperatures. Specifically, the electric field breakdown
strength of sapphire at room temperature may be insufficient to
withstand the high buildup of local electrical fields resulting
from the implantation of charged particles, without exceeding a
breakdown electric field strength (E.sub.BD). However it is known
that the resistivity (.rho.) of sapphire decreases with increasing
temperature (approximately 1.times.10.sup.16 .OMEGA.-cm at room
temperature to 1.times.10.sup.6 .OMEGA.-cm at 1000.degree. C.), and
thus material breakdown can be avoided by increasing the
temperature until the following equation is satisfied:
.rho.(T)<E.sub.BD/I.sub.a
where I.sub.a is the current per area being implanted in
amperes/cm.sup.2
[0048] Given an estimated sapphire E.sub.BD of about
4.8.times.10.sup.5 V/cm and an implant flux of 2.5 .mu.A/cm.sup.2,
the maximum resistivity permitted to avoid material breakdown is
about 2.times.10.sup.11 .OMEGA.-cm. This resistivity occurs at
about 500.degree. C., therefore it is expected that increasing the
temperature of a sapphire core above 500.degree. C. prior to
commencing implantation may be useful to avoid breakdown of the
material. Accordingly, it may be desirable to employ a coating for
the purpose of radiative heating of the sapphire core prior to its
implantation with charged particles for this purpose.
[0049] Certain thermo-mechanical properties of a sapphire core may
enhance its ability to be cleaved into individual layers according
to various embodiments. Specifically, within its expected
implantation temperature range (e.g. 650-850.degree. C.), sapphire
also exhibits a relatively high coefficient of thermal expansion,
together with a relatively low degree of thermal conductivity.
Furthermore, the application of accelerated particles for
implantation may occur as a scanned beam, with a relative dwell
time at any point of as little as 80 .mu.s.
[0050] The resulting rapid pulse heating of sapphire is contained
near surface areas of the core receiving the beam by the sapphire's
low thermal conductivity. Accordingly, at temperatures of about
800.degree. C., regions of a few tens of microns proximate to the
implanted surface of the core will be expected to undergo repeated
thermal expansion, followed by rapid contraction as excess heat is
removed by conductive cooling to the rest of the sapphire bulk. The
resulting stresses in the surface regions of the implanted core may
serve to provide energy for cleave initiation and/or
propagation.
[0051] For example, using a 2 cm beam of 15 kW power scanned over a
50 cm.times.50 cm area with a beam velocity of 250 m/s, a thickness
of about 30 .mu.m beneath the implant surface undergoes a
temperature rise of about 70.degree. C. within 80 .mu.s. This is
followed by cooling to bulk temperature within a few milliseconds.
During that brief time, surface compressive shear stresses
exceeding 150-200 MPa are developed that can augment the cleave
plane chemical stresses to help prepare the implanted layer for
cleaving.
[0052] Although the above description has been primarily in terms
of a sapphire bulk material, other substrates may also be used. For
example, the substrate can be almost any monocrystalline,
polycrystalline, or even amorphous type substrate. One example of a
suitable material is silicon carbide (SiC). Additionally, the
substrate can be made of III/V materials such as gallium arsenide
(GaAs), gallium nitride (GaN), and others. A multi-layered
substrate can also be used according to various embodiments. The
multi-layered substrate includes a silicon-on-insulator substrate,
a variety of sandwiched layers on a semiconductor substrate, and
numerous other types of substrates.
[0053] Embodiments may employ pulsed energy in addition to, or in
place of, scanned energy, to initiate or propagate a controlled
cleaving action. The pulse can be replaced or supplemented by
energy that is scanned across a selected region of the substrate to
initiate the controlled cleaving action. Energy can also be scanned
across selected regions of the substrate to sustain or maintain the
controlled cleaving action. One of ordinary skill in the art would
easily recognize a variety of alternatives, modifications, and
variations, which can be used according to the present
invention.
[0054] While the above is a full description of the specific
embodiments, various modifications, alternative constructions and
equivalents may be used. Although the above has been described
using a selected sequence of steps, any combination of any elements
of steps described as well as others may be used. Additionally,
certain steps may be combined and/or eliminated depending upon the
embodiment. Furthermore, the particles of hydrogen can be replaced
using co-implantation of helium and hydrogen ions or deuterium and
hydrogen ions to allow for formation of the cleave plane with a
modified dose and/or cleaving properties according to alternative
embodiments. Still further, the particles can be introduced by a
diffusion process rather than an implantation process. Of course
there can be other variations, modifications, and alternatives.
[0055] Therefore, the above description and illustrations should
not be taken as limiting the scope of the present invention which
is defined by the appended claims.
* * * * *