CN112301422B - Substrate stripping method based on laminated mask substrate - Google Patents
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- 239000000758 substrate Substances 0.000 title claims abstract description 93
- 238000000034 method Methods 0.000 title claims abstract description 60
- 150000004767 nitrides Chemical class 0.000 claims abstract description 62
- 239000000463 material Substances 0.000 claims abstract description 43
- 238000002248 hydride vapour-phase epitaxy Methods 0.000 claims abstract description 24
- 238000005516 engineering process Methods 0.000 claims abstract description 19
- 230000008569 process Effects 0.000 claims abstract description 15
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 claims abstract description 12
- 239000013078 crystal Substances 0.000 claims description 27
- 230000006911 nucleation Effects 0.000 claims description 8
- 238000010899 nucleation Methods 0.000 claims description 8
- 238000000407 epitaxy Methods 0.000 claims description 7
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 3
- LKJPSUCKSLORMF-UHFFFAOYSA-N Monolinuron Chemical compound CON(C)C(=O)NC1=CC=C(Cl)C=C1 LKJPSUCKSLORMF-UHFFFAOYSA-N 0.000 claims description 2
- 238000005553 drilling Methods 0.000 claims description 2
- 229910002059 quaternary alloy Inorganic materials 0.000 claims description 2
- 229910002058 ternary alloy Inorganic materials 0.000 claims description 2
- 238000001816 cooling Methods 0.000 abstract description 9
- 238000004519 manufacturing process Methods 0.000 abstract description 7
- 238000000926 separation method Methods 0.000 abstract description 6
- 239000010408 film Substances 0.000 description 62
- 229910002601 GaN Inorganic materials 0.000 description 18
- 230000035882 stress Effects 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 7
- 238000010586 diagram Methods 0.000 description 7
- 239000010409 thin film Substances 0.000 description 7
- 230000008901 benefit Effects 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 238000001000 micrograph Methods 0.000 description 3
- 229910052594 sapphire Inorganic materials 0.000 description 3
- 239000010980 sapphire Substances 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- BNOODXBBXFZASF-UHFFFAOYSA-N [Na].[S] Chemical compound [Na].[S] BNOODXBBXFZASF-UHFFFAOYSA-N 0.000 description 2
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- 239000002070 nanowire Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
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- 230000008646 thermal stress Effects 0.000 description 2
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- 238000010420 art technique Methods 0.000 description 1
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- 238000006243 chemical reaction Methods 0.000 description 1
- 230000032798 delamination Effects 0.000 description 1
- 238000001534 heteroepitaxy Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
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- 239000002994 raw material Substances 0.000 description 1
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- C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
- C30B25/02—Epitaxial-layer growth
- C30B25/04—Pattern deposit, e.g. by using masks
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- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/01—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes on temporary substrates, e.g. substrates subsequently removed by etching
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/04—Coating on selected surface areas, e.g. using masks
- C23C16/042—Coating on selected surface areas, e.g. using masks using masks
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
- C23C16/301—AIII BV compounds, where A is Al, Ga, In or Tl and B is N, P, As, Sb or Bi
- C23C16/303—Nitrides
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- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/40—AIIIBV compounds wherein A is B, Al, Ga, In or Tl and B is N, P, As, Sb or Bi
- C30B29/403—AIII-nitrides
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Abstract
The present invention relates to a substrate peeling method based on a laminated mask substrate. The method includes 1) growing a group III nitride material on a three-dimensional laminated mask substrate using MOCVD technology to form a group III nitride material film, 2) growing a group III nitride material on the continuous film using HVPE technology to form a group III nitride material thick film, and 3) creating stress between the three-dimensional laminated mask substrate and the group III nitride material thick film by cooling to thereby achieve self-separation. The method can separate from the substrate in the cooling process due to weak connectivity with the substrate, avoids using expensive technologies such as laser stripping and the like, saves process steps and time, remarkably improves the production yield and improves the product quality, and the adopted special three-dimensional laminated mask substrate can be matched with MOCVD to grow a high-quality film so as to be capable of extending out a high-crystal-quality thick film through HVPE.
Description
Technical Field
The invention belongs to the technical field of semiconductors, and particularly relates to a substrate stripping method based on a laminated mask substrate.
Background
Through the research of nearly twenty-three years, gaN, alN, inN, alGaN, inGaN and other III nitride materials as the third-generation semiconductors show a plurality of excellent physical and chemical properties, and are considered as a semiconductor material with very high application value. HVPE is a common method in the growth art of self-supporting single crystal group III nitride materials because of the difficulty of single crystal growth of the group III nitride materials. HVPE is an abbreviation for Hydride Vapor Phase Epitaxy and refers to hydride vapor phase epitaxy. The HVPE preparation of self-supporting group III nitride thick films has two main problems, namely, serious warpage of the group III nitride thick films caused by heteroepitaxy and how to separate the epitaxial group III nitride thick films from the substrate. The first problem arises from stress. Because of the large lattice and thermal mismatch between the III-nitride material and the commonly used substrate materials sapphire and silicon, stress builds up with increasing thickness due to lattice mismatch during growth and further during cooling due to the different coefficients of thermal expansion from the substrate material. Thus, for thick film group III nitrides, severe warpage will occur due to too large stress, even resulting in breakage of the entire thin film, severely reducing the production yield of HVPE in industrial production. For batch production of group III nitride self-supporting thick films by HVPE technology, the first problem to be solved is the warpage problem. The second problem is the problem of the ill-nitride material peeling from the substrate. Since group III nitrides are tightly bonded to the substrate, they are very difficult to strip, and various stripping methods, such as laser stripping, have been developed for this industry.
Taking GaN as an example, the prior art has mainly the following drawbacks:
(1) The existing methods for growing the self-supporting GaN single crystal mainly comprise an ammonothermal method, a sodium-sulfur method and an HVPE method. The growth rate of the ammonothermal method and the sodium-sulfur method is low, so that the production cost is high, a high-pressure environment is needed, and the danger coefficient of equipment is high. While the HVPE method grows at a faster rate, the yield is very low, less than 20%. Most disintegrate during cooling. Even without chipping, delamination from the substrate is very difficult. After the peeling, the GaN film is warped and twisted due to the overlarge stress when growing on the substrate, and after the GaN film is flattened by a CMP process, the crystal orientation of the surface is not uniform, and a plurality of subsequent problems exist when the GaN film is used as the substrate.
(2) In other technical schemes which are easy to separate through porous structures or nanowire mats, etc., since GaN is not grown on a regular lattice-matched substrate, the growth quality of the early MOCVD layer is not high. The HVPE technology is used for epitaxially thickening the film, and the defect density is reduced, but the reduction degree is limited, so that the whole crystal quality of the finally grown thick film product is low, and the use value is low.
(3) The technology of growing the first layer GaN film by using the patterned substrate or the common lateral epitaxy technology has the advantages that the common patterned substrate or the lateral epitaxy technology has concentrated and large amount of dislocation generation in a window area, so that the overall crystal quality is improved, but the improvement degree is limited. And because the wing area extending from the common side direction can be tilted, a large number of defects, including dislocation, holes and the like, are generated in the folding area, the overall quality is seriously affected, and the crystal quality in the local area is only improved. These high density defect regions can degrade device performance when the device is epitaxially grown, and thus such techniques still do not fully meet industry requirements.
Disclosure of Invention
The invention aims to solve the problems that a group III nitride thick film grown by the HVPE technology is fragile and difficult to peel off from a substrate.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
A substrate peeling method based on a laminate mask substrate, comprising the steps of:
1) Growing a III-nitride material on the three-dimensional laminated mask substrate by using MOCVD technology to form a III-nitride material film;
2) Growing a group III nitride material on the continuous thin film using HVPE techniques to form a thick film of group III nitride material;
3) Self-separation is achieved by creating stress between the three-dimensional stack mask substrate and the thick film of group III nitride material by cooling.
Further, in the step 1), the thickness of the group III nitride material film is 1-20 micrometers.
Further, in the step 2), the thickness of the thick film of the group III nitride material is 20-500 micrometers.
Further, for the self-separated group III nitride material thick film, a self-supporting stress-free single crystal wafer is obtained through surface leveling process.
Further, the three-dimensional laminated mask substrate in the step 1) comprises a substrate, a bottom mask layer and a top mask layer are sequentially arranged on the substrate, the bottom mask layer is provided with windows which are distributed periodically, symmetry of patterns of the windows in a plane is consistent with or is a subset of crystal symmetry of hexagonal III-nitride materials, the patterns of the top mask layer and the windows of the bottom mask layer are identical, positions of the windows are staggered, and the top mask layer is connected with the bottom mask layer through a dielectric layer.
Further, the pattern of the window is one of a bar, a regular triangle, and a regular hexagon.
Further, the top and bottom mask layers are SiN x and the dielectric layer is SiO 2.
Further, step 1) includes:
a) Forming nucleation points of III-nitride on the surface of the substrate exposed by the bottom mask window in the low-temperature nucleation stage, and starting to form island-shaped structural atomic groups of the III-nitride by taking the nucleation points as the center;
b) Raising the temperature, carrying out III nitride growth under the normal III nitride growth parameter condition, and drilling a channel to expose a top mask window to form a protruding shape by the grown III nitride with the increase of time;
c) After the channel is drilled and a certain height is formed outside the top layer window, the growth parameters are switched, the MOCVD lateral epitaxy technology is adopted to enable the lateral growth rate to be far greater than the vertical growth rate, and the growth is always carried out until the III-nitride is folded into a flat large plane, namely the III-nitride film is formed.
Further, step 3) is assisted in achieving substrate lift-off using a laser lift-off technique.
Further, the group III nitride material is GaN, alN, inN or a ternary or quaternary alloy formed by them.
Compared with the prior art, the invention has the following two remarkable advantages:
1. Due to the weak connectivity with the substrate, it is possible to separate from the substrate during cooling, avoiding the use of expensive techniques such as laser lift-off to separate the group III nitride thick film from the substrate. The III nitride thick film and the substrate can be separated without laser stripping and other steps, so that the process steps and time are saved, the production yield is greatly improved, the crystal distortion is avoided, the warped crystal is not required to be ground by using a grinding process, the comprehensive cost is effectively reduced, and the product quality is improved. This is a key point for large scale application of group III nitride high quality homosubstrates.
2. Since the special three-dimensional laminated mask substrate can be matched with MOCVD to grow high-quality thin films, the high-crystal-quality thick films can be epitaxially grown by the HVPE as the preamble process step of the HVPE. Taking GaN material growth as an example, the invention can prepare the self-supporting GaN substrate with dislocation density of 10 5/cm2 at lower cost, which is obviously superior to the existing other methods.
Drawings
Fig. 1 is a schematic diagram of stress twist for a planar substrate grown III-nitride self-supporting thick film, where (a) is compressive and (b) is tensile.
Fig. 2 is a schematic diagram of the self-separation principle of growing thick film group III nitrides using a custom three-dimensional stack mask substrate of the present invention.
Fig. 3 is a graph showing the effect of microscopic observation of the separation of a 20 μm thick GaN thick film from a custom stack mask substrate during cooling.
FIG. 4 is a schematic view of a three-dimensional structure of a stripe-shaped substrate, wherein the stripe-shaped substrate comprises a 1-top mask layer, a 2-substrate, a 3-top window, a 4-bottom window, a 5-bottom mask layer and a 6-dielectric layer connecting the top mask layer and the bottom mask layer.
Fig. 5 is a diagram having the same symmetry as the gallium nitride crystal structure, wherein the (a) diagram, (b) diagram, and (c) diagram are bar, triangle, hexagon in this order.
Fig. 6 is a schematic plan view of a strip, triangle, or hexagon graphic substrate design, wherein (a) drawing, (b) drawing, and (c) drawing sequentially represent strip, triangle, or hexagon windows, dotted lines represent lower layer windows, and solid lines represent upper layer windows.
Fig. 7 is a scanning electron microscope image of gallium nitride grown on different patterned substrates, wherein (a) image, (b) image and (c) image sequentially show the scanning electron microscope image of gallium nitride grown on triangular, hexagonal and bar-shaped patterned substrates. The figure shows the intermediate growth state, and continued growth will form a closed film.
Detailed Description
The present invention will be further described in detail with reference to the following examples and drawings, so that the above objects, features and advantages of the present invention can be more clearly understood.
The invention aims to solve the problems that a group III nitride thick film grown by the HVPE technology is fragile and difficult to peel off from a substrate. By using the substrate and the growth process provided by the invention, the self-separation of the complete III-nitride thick film and the substrate is realized, the production yield is improved, and the high-quality self-supporting single-crystal III-nitride thick film is obtained. The high-quality self-supporting III nitride single crystal substrate and the epitaxially grown III nitride layer to be used for device preparation have no lattice mismatch and thermal mismatch, so that the crystal quality of the epitaxial layer is greatly improved, the performance of the device is closer to the theoretical limit of materials, the performance is improved, and the service life of the device is prolonged, so that the high-quality device for epitaxial growth is the best choice. However, it is difficult to prepare high-quality self-supporting group III nitride single crystal substrates at present, mainly the yield is low, the cost is high, and the time consumption is long. The invention has the important purpose of improving the preparation yield of the III-nitride self-supporting thick film, reducing the cost, improving the crystal quality and the process stability and providing raw material supply for the III-nitride related industry.
As shown in fig. 1, the conventional method for growing a group III nitride thick film causes warpage of the substrate and the thin film due to excessive stress, and the thermal stress aggravates the warpage during cooling, thereby causing cracks or even chipping of the thin film. Even if the thick film material is peeled off by the laser peeling technology, the thick film material still needs to be subjected to a grinding process, and the grinding process is just to grind the surface, so that the problem of lattice distortion still exists, and the quality of the thick film is low. It is difficult to obtain a high quality free standing group III nitride thick film in whole large sheets because of the low yield.
In the invention, a special three-dimensional laminated mask substrate is used, the growth method is divided into two steps, firstly, MOCVD equipment/technology is used for growing III nitride materials on the mask substrate to form a high-quality continuous film with the thickness of 1-20 microns, on the basis, the HVPE technology is used for growing III nitride, the growth rate of the III nitride film is accelerated by the advantage of high growth rate, and a III nitride thick film with the thickness of 20-500 microns is grown. MOCVD can grow higher quality group III nitrides directly on sapphire or silicon substrates, but at a slower growth rate. HVPE has difficulty in growing high quality single crystals of group III nitride directly on substrates such as sapphire and silicon, but can grow high quality single crystals on group III nitride layers and at a faster growth rate. The group III nitride thick film growth step is therefore generally divided into two steps, which enables high quality crystals to be obtained. Because of the special structure of the mask substrate, no chemical bond is formed between the mask layer and the III-nitride, and the III-nitride film is combined by weak Van der Waals force, so that the direct connection part of the III-nitride film and the substrate is less, and the III-nitride film can be broken under huge stress. During the growth process, the thermal stress between the substrate and the thick film is not reflected due to the high temperature of the growth condition, and during the cooling process, the great stress is generated due to the large difference of the thermal expansion coefficients between the substrate and the thick film of the III-nitride, so that the weakest channel is connected by twisting, and the self-separating effect is achieved, as shown in fig. 2.
After the surface planarization process, the self-supporting stress-free monocrystalline wafer can be obtained for the self-separated thick film III nitride, and the self-supporting stress-free monocrystalline wafer can be used for various researches and device production of the III nitride related industry.
The experimental case of fig. 3 shows the self-separating effect, but is not self-supporting after self-separation due to insufficient film thickness, and is easily broken. The integrity of the self-separated film can be maintained by optimizing the growth conditions to planarize the surface and thickening the film by using the HVPE technique.
The key point of the invention is to use a custom three-dimensional stacked mask substrate to grow a group III nitride thick film that can self-separate. The use of a specially-made three-dimensional laminated mask substrate is the most critical point, because the substrate can weaken the direct connection strength of a film and the substrate, achieve the effect of easy stripping, and maintain very high crystal quality when an initial film layer is grown by MOCVD, so that the overall crystal quality of the film which is epitaxially thickened by using an HVPE method is very high, and the dislocation density can be lower than 10 5/cm2.
FIG. 4 is a schematic diagram of the structure of a custom three-dimensional laminated mask substrate of the present invention. The top mask layer 1 and the bottom mask layer 5 on the substrate 2 are provided with strip-shaped windows which are periodically distributed, namely a top window 3 and a bottom window 4, but are staggered with each other. The top mask layer 1 and the bottom mask layer 5 are connected through a dielectric layer 6. The materials of the top mask layer 1 and the bottom mask layer 5 may be SiN x, etc., and the materials of the dielectric layer 6 may be SiO 2, etc.
The bottom mask layer is provided with special pattern windows which are distributed periodically, and besides the strips in fig. 4, the special pattern windows can also be regular triangles and regular hexagons, as shown in fig. 5. The symmetry in the plane is consistent with the symmetry of the crystal of III nitride materials such as GaN or a subset thereof, and the use of the patterns with special symmetry enables the preparation of continuous and flat III nitride films such as high-quality epitaxial layers of GaN and the like which are paved on the whole substrate surface, and can be more fully compatible with subsequent device processes. The top mask layer is the same pattern as the bottom mask layer but is offset from each other as shown in fig. 6, where the dashed lines represent the lower windows and the solid lines represent the upper windows.
The growth process of group III nitride on the 3D stack mask substrate structure of the present invention is as follows:
1) At the outset, a low temperature nucleation stage is required, through which III-nitride nucleation sites form on the exposed substrate surface of the underlying mask window. With these points as the center, the group III nitride starts to form island-like structural radicals.
2) The temperature is then raised and the III-nitride growth is performed under normal III-nitride growth parameters, and over time the grown III-nitride drills out the channel, exposing the top mask window, forming a protruding shape.
3) After the trench is drilled and a certain height is formed in the top-level window, the growth parameters are switched, and lateral epitaxy techniques (such as the MOCVD lateral epitaxy technique described herein before) are used, so that the lateral growth rate is much greater than the vertical growth rate. The growth is continued until the group III nitride is folded into a flat large plane, thereby forming the group III nitride film according to the present invention.
Fig. 7 is a scanning electron microscope image of gallium nitride grown on different pattern substrates, showing the intermediate growth state, and continuing to grow will form a folded film.
In addition to being fragile, conventional methods for growing group III nitride thick films on planar substrates require laser lift-off techniques to separate the group III nitride thick films from the substrate. The technical difficulty of laser stripping is also great, and the process is further reduced in yield and longer in time consumption, so that the cost is high. The method has the beneficial effects that the effect of separating the III-nitride thick film from the substrate can be achieved without a laser stripping step, the process steps and time are saved, the production yield is greatly improved, the yield of the stripped thick film is expected to exceed 90%, and no crystal distortion exists. Not only greatly reduces the comprehensive cost, but also improves the product quality, which is the key point of large-scale application of the III-nitride high-quality homogeneous substrate. Once high quality homogeneous group III nitride substrates are applied on a large scale, many long standing industry problems will be solved and the performance of the devices produced will be greatly improved. In the field of power electronic devices, the voltage withstand value of the device can be improved, and the heat loss of the device can be reduced. In the field of radio frequency devices, the power density and the radio frequency conversion efficiency can be improved, the working voltage is reduced, and the frequency application range is enlarged. In the field of photoelectric devices, the device with a vertical structure can be used, so that the luminous efficiency is greatly improved, and the complexity of a driving circuit is reduced.
Some prior art techniques are currently capable of producing self-stripping effects. For example, nanowires are paved on a plane substrate, so that the connection strength of the grown III-nitride film and the substrate is weakened, and the effect of easy stripping is achieved. There is also a method of weakening the bonding strength of a substrate to a thin film by first preparing a porous group III nitride on a planar substrate. The method also uses a common pattern substrate to grow, and aims to weaken the connection strength of the substrate and the gallium nitride film, so as to achieve the effect of easy stripping. However, these methods are not high in quality of the part of the group III nitride thin film before using HVPE technique, so are not high in quality of thick film crystal finally obtained by HVPE epitaxy. Taking GaN material growth as an example, a common patterned substrate can make the overall dislocation density close to 10 6/cm2, but the defect density is still very high in the concentrated region due to non-uniformity. By the technology of the invention, the self-supporting GaN substrate with dislocation density lower than 10 5/cm2 can be prepared, which is obviously superior to other existing methods.
The above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and those skilled in the art may modify or substitute the technical solution of the present invention without departing from the principle and scope of the present invention, and the protection scope of the present invention shall be defined by the claims.
Claims (6)
1. A substrate peeling method based on a laminate mask substrate, comprising the steps of:
1) Growing a III-nitride material on a three-dimensional laminated mask substrate by using an MOCVD technology to form a III-nitride material film, wherein the thickness of the III-nitride material film is 1-20 microns;
2) Growing a III-nitride material on the III-nitride material film by using an HVPE technology to form a III-nitride material thick film, wherein the thickness of the III-nitride material thick film is 20-500 micrometers;
3) The method comprises the steps of 1) forming a three-dimensional laminated mask substrate and a III-nitride material thick film, wherein the three-dimensional laminated mask substrate comprises a substrate, a bottom mask layer and a top mask layer are sequentially arranged on the substrate, the bottom mask layer is provided with windows which are periodically distributed, the symmetry of patterns of the windows in a plane is consistent with or is a subset of the symmetry of crystals of a hexagonal III-nitride material, the patterns of the top mask layer and the windows of the bottom mask layer are the same, the positions of the windows are staggered, and the top mask layer is connected with the bottom mask layer through a medium layer;
The window graph is a triangle window and a hexagon window as shown in (b) and (c) of fig. 6, the dotted line represents a lower window, and the solid line represents an upper window.
2. The method of claim 1, wherein the self-supporting, stress-free single crystal wafer is obtained by a surface planarization process for a thick film of self-separated group III nitride material.
3. The method of claim 1, wherein the top mask layer and the bottom mask layer are SiN x and the dielectric layer is SiO 2.
4. The method according to claim 1, wherein step 1) comprises:
a) Forming nucleation points of III-nitride on the surface of the substrate exposed by the bottom mask window in the low-temperature nucleation stage, and starting to form island-shaped structural atomic groups of the III-nitride by taking the nucleation points as the center;
b) Raising the temperature, carrying out III nitride growth under the normal III nitride growth parameter condition, and drilling a channel to expose a top mask window to form a protruding shape by the grown III nitride with the increase of time;
c) After the channel is drilled and a certain height is formed outside the top layer window, the growth parameters are switched, the MOCVD lateral epitaxy technology is adopted to enable the lateral growth rate to be far greater than the vertical growth rate, and the growth is always carried out until the III-nitride is folded into a flat large plane, namely the III-nitride film is formed.
5. The method of claim 1, wherein step 3) is performed using laser lift-off techniques to assist in substrate lift-off.
6. The method of claim 1, wherein the group III nitride material is GaN, alN, inN or a ternary or quaternary alloy formed from them.
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| CN101488475A (en) * | 2009-02-20 | 2009-07-22 | 中国科学院上海微系统与信息技术研究所 | Implementing method for self-stripping thick film gallium nitride from substrate sapphire |
| CN101685768A (en) * | 2008-09-23 | 2010-03-31 | 北京大学 | Method for preparing self-supporting mono-crystal gallium nitride substrate |
| CN101764055A (en) * | 2009-10-19 | 2010-06-30 | 金柯 | Epitaxy-based method for improving the quality of GaN films |
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| CN1381870A (en) * | 2002-05-31 | 2002-11-27 | 南京大学 | Technology for obtaining large-area high-quality GaN self-supporting substrate |
| CN101685768A (en) * | 2008-09-23 | 2010-03-31 | 北京大学 | Method for preparing self-supporting mono-crystal gallium nitride substrate |
| CN101488475A (en) * | 2009-02-20 | 2009-07-22 | 中国科学院上海微系统与信息技术研究所 | Implementing method for self-stripping thick film gallium nitride from substrate sapphire |
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