CN109585615B - Method for stripping gallium nitride epitaxial layer from substrate - Google Patents
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- CN109585615B CN109585615B CN201811473218.3A CN201811473218A CN109585615B CN 109585615 B CN109585615 B CN 109585615B CN 201811473218 A CN201811473218 A CN 201811473218A CN 109585615 B CN109585615 B CN 109585615B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
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- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/005—Processes
- H01L33/0093—Wafer bonding; Removal of the growth substrate
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
- H01L21/6835—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
- H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
- H01L21/7806—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices involving the separation of the active layers from a substrate
- H01L21/7813—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices involving the separation of the active layers from a substrate leaving a reusable substrate, e.g. epitaxial lift off
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2221/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
- H01L2221/67—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere
- H01L2221/683—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping
- H01L2221/68304—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
- H01L2221/68381—Details of chemical or physical process used for separating the auxiliary support from a device or wafer
- H01L2221/68386—Separation by peeling
Abstract
The present disclosure relates to a method for stripping a gallium nitride epitaxial layer from a substrate, the method comprising: growing a gallium nitride epitaxial layer on the patterned sapphire substrate in an MOCVD or MBE deposition mode; adhering a support sheet with the area equal to or larger than that of the gallium nitride epitaxial layer on the upper surface of the gallium nitride epitaxial layer through an adhesive and carrying out curing treatment; peeling the gallium nitride epitaxial layer and the support chip from the patterned sapphire substrate integrally by applying stress to an interface between the gallium nitride epitaxial layer and the patterned sapphire substrate; and separating the gallium nitride epitaxial layer from the support sheet by heating the adhesive at the interface between the gallium nitride epitaxial layer and the support sheet so that the adhesive melts.
Description
Technical Field
The present disclosure relates to a semiconductor device and a method for manufacturing the same, and more particularly, to a method for stripping an epitaxial layer of gallium nitride.
Background
However, the separation of a large area wafer from a substrate can cause local damage to the wafer, which can lead to a relatively high defect rate in the subsequent dicing of the wafer.
Disclosure of Invention
The present disclosure is directed to solving the above and/or other technical problems and to providing a method for peeling off a gallium nitride epitaxial layer from a substrate, the method comprising: growing a gallium nitride epitaxial layer on the patterned sapphire substrate in an MOCVD or MBE deposition mode; adhering a support sheet with an area equal to or larger than that of the gallium nitride epitaxial layer to the upper surface of the gallium nitride epitaxial layer by using an adhesive; peeling the gallium nitride epitaxial layer and the support chip from the patterned sapphire substrate integrally by applying stress to an interface between the gallium nitride epitaxial layer and the patterned sapphire substrate; and separating the gallium nitride epitaxial layer from the support sheet by heating the adhesive at the interface between the gallium nitride epitaxial layer and the support sheet so that the adhesive melts.
A method for stripping a gallium nitride epitaxial layer from a substrate according to the present disclosure, further comprising: before a support sheet is adhered to the upper surface of the gallium nitride epitaxial layer by an adhesive, the gallium nitride epitaxial layer is subjected to a thinning process by a chemical-mechanical polishing (CMP) method to obtain a gallium nitride epitaxial layer of a predetermined thickness.
A method for stripping a gallium nitride epitaxial layer from a substrate according to the present disclosure, further comprising: the gallium nitride epitaxial layer and the patterned sapphire substrate are separated by applying a horizontal lateral physical stress to the sides of the interface therebetween.
A method for stripping a gallium nitride epitaxial layer from a substrate according to the present disclosure, further comprising: and separating the gallium nitride epitaxial layer and the patterned sapphire substrate by irradiating the interface between the gallium nitride epitaxial layer and the patterned sapphire substrate with laser from one side of the patterned sapphire substrate.
The method for peeling off a gallium nitride epitaxial layer from a substrate according to the present disclosure, wherein the adhering a support sheet having an area equal to or larger than an area of the gallium nitride epitaxial layer to an upper surface of the gallium nitride epitaxial layer with an adhesive comprises: coating a layer of wax or low-melting-point metal in a molten state on the upper surface of the gallium nitride epitaxial layer; attaching a support sheet to the wax layer or the low-melting-point metal layer; placing the gallium nitride epitaxial layer, the support sheet and the wax layer or the low-melting-point metal layer in an inert gas environment and keeping the temperature of the wax layer or the low-melting-point metal layer at a temperature enabling the wax layer or the low-melting-point metal layer to be in a molten state for 3-10 minutes; and reducing the ambient temperature to solidify the wax layer or the low melting point metal layer.
The method for peeling a gallium nitride epitaxial layer from a substrate according to the present disclosure, wherein the adhesive heating of the interface between the gallium nitride epitaxial layer and the support sheet is heated by directly placing the gallium nitride epitaxial layer and the support sheet on a hot plate. .
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure.
FIG. 1 is a schematic cross-sectional view of a composition containing an epitaxial layer of gallium nitride to be separated according to an embodiment of the present disclosure;
FIG. 2 shows a scanning electron micrograph of a composition containing an epitaxial layer of gallium nitride to be separated according to the present disclosure;
fig. 3 is a schematic view showing the separation of the entirety of a composite containing an epitaxial layer of gallium nitride to be separated from a substrate according to the present disclosure.
Fig. 4 is a schematic diagram illustrating a separation support sheet in a composite containing a gallium nitride epitaxial layer to be separated according to the present disclosure.
Detailed Description
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.
The terminology used in the present disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. Unless defined otherwise, all other scientific and technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. As used in this disclosure and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.
It should be understood that, although the terms "parallel" or "perpendicular" are used in this disclosure, they are not intended to be perfectly theoretically parallel or perpendicular, but rather are intended to be in a parallel relationship (e.g., within 10 millidegrees of an angle therebetween) or perpendicular relationship (e.g., within 10 millidegrees of error from 90 degrees of an angle therebetween) within a reasonable range. The spatial designations "top," "bottom," "upper," "lower," "vertical," "horizontal," and the like may be used when referring to the drawings in the following detailed description. For example, "vertical" may be used to refer to a direction perpendicular to the substrate surface, and "horizontal" may be used to refer to a direction parallel to the substrate surface, when referring to the drawings. "upper," "top," or "above" may be used to refer to a vertical direction away from the substrate, while "lower," "bottom," or "below" may be used to refer to a vertical direction toward the substrate. Such references are for teaching purposes and are not intended to be an absolute reference to the specific device. The embodied devices may be spatially oriented in any suitable manner, which may vary from the orientation depicted in the figures. The word "if" as used herein may be interpreted as "at …" or "when …" or "in response to a determination", depending on the context.
For a better understanding of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.
As shown in fig. 1, an epitaxial layer 120 is grown on a patterned sapphire substrate 110 having an array of trenches and stripes patterned across the surface of the sapphire substrate 110. The trapezoidal stripe array includes a plurality of generally planar surfaces, at least some of which are covered with a mask material that prevents crystal growth from sapphire (not shown). The surfaces of the groove and fringe arrays may be oriented in different directions. The crystal growth surface may be substantially parallel to the c-plane facets of sapphire according to some embodiments. Gallium nitride semiconductors may be grown continuously from the crystal growth surface 115 at different locations until the separated pieces of gallium nitride merge on the patterned features on the sapphire substrate to form a continuous first gallium nitride epitaxial layer 120, as shown in fig. 1. The gallium nitride semiconductor may extend partially or fully across the sapphire substrate and form a "flat" to-be-processed surface "on the substrate 110, on which epitaxial growth may continue to obtain an integrated device.
The trapezoidal stripes of the patterned sapphire substrate 110 are formed by etching in a conventional manner. For example, a patterned resist (e.g., a soft resist, a polymer resist, or, for example, a hard resist, a patterned inorganic material) is formed on top of the patterned sapphire substrate 110 in alignment with the crystal orientation of the sapphire substrate. The PSS substrate 110 used in the present disclosure may be patterned as disclosed in chinese patent publication No. CN106233429A with the sapphire substrate 110 patterned, after which the resist is removed after it is patterned. For good crystal growth, selected surfaces of the sapphire substrate may be masked with a high temperature conformal coating (not shown) formed by silicon dioxide or silicon nitride deposition by CVD or PECVD. A high temperature conformal coating, typically about 10nm to about 50nm, may be formed on selected surfaces of the patterned sapphire substrate 110. A resist layer (not shown) is then formed on the high temperature conformal coating by photolithography or by shadow evaporation using a shadow method, thereby forming a resist layer on the high temperature conformal coating except the c-plane surface. Subsequently, the high temperature conformal coating at the surface not masked by the resist is etched away by a selective anisotropic dry etching method, exposing the crystal growth surface of the sapphire substrate. The etchant is then removed elsewhere. Thus, only the crystal growth surface is exposed and the other parts are covered by the high temperature conformal coating. The fabrication of the PSS substrate for use in the present disclosure is a prior art and therefore not described in detail herein.
After preparing the PSS substrate as described above, the first gallium nitride epitaxial layer 120 may be performed using MOCVD. The temperature in the reaction chamber may be ramped to a higher temperature to anneal the buffer layer for a period of time before beginning to grow the first gallium nitride epitaxial layer 120. In some embodiments, the temperature may be raised to a value between about 1000 ℃ to about 1100 ℃. The annealing time may be from about 1 minute to about 10 minutes. In some cases, the temperature may be raised to a value between 1000 ℃ and 1100 ℃, and the annealing time may be about 1 minute to about 10 minutes.
Subsequently, epitaxial growth of the first gallium nitride epitaxial layer 120 is performed using metal organic chemical vapor deposition (MOVCD). In some embodiments, Molecular Beam Epitaxy (MBE) methods, out of vapor phase, may be usedEpitaxial (VPE) method or atomic layer deposition. The growth of the first gallium nitride epitaxial layer 120 may be performed at a temperature of about 1000 ℃ to about 1100 ℃, for example, may be performed at a temperature of about 1030 ℃. The chamber pressure may be maintained at about 100 mbar to about 250 mbar during growth of the first gallium nitride epitaxial layer 120. Mother material NH3May be about 1slm to about 4slm, and the parent material trimethylgallium (TMGa) may be about 30sccm to about 50 sccm.
In order to reduce the number of defects on the surface of the first gallium nitride epitaxial layer 120. One would typically prepare a buffer layer on the exposed crystal surface to form integrated circuit grade GaN before growing the first gallium nitride epitaxial layer 120 on the PSS substrate 110. According to some embodiments, the PSS substrate 110 may be grown with a GaN or AlN buffer layer at low temperature, e.g., below about 600 ℃, after cleaning. The cleaning process is carried out in a conventional manner. The process of the specific buffer layer is not described in detail, and can be performed with reference to the prior art. Note that the buffer layer is not an essential constituent of the present disclosure.
Subsequently, the growth of the group III nitride material is continued on the flat surface of the first gallium nitride epitaxial layer 120 to epitaxially grow a second gallium nitride epitaxial layer (not shown). In order to facilitate the subsequent process, the second gallium nitride epitaxial layer is grown by a Hydride Vapor Phase Epitaxy (HVPE) method, so that the second gallium nitride epitaxial layer which grows thicker can be better grown. The HVPE equipment has the advantages of simple equipment and high growth speed (the rate is as high as 700-800 mu m/h), and can grow uniform and large-size GaN thick films (the dislocation density is only 10)4/cm2). The present disclosure employs conventional Hydride Vapor Phase Epitaxy (HVPE) methods for growth. Since the second gallium nitride epitaxial layer is grown on the first gallium nitride epitaxial layer 120, the occurrence of cracks during the increase in thickness by the conventional Hydride Vapor Phase Epitaxy (HVPE) method is rare. The thickness of the second gallium nitride epitaxial layer grown by a Hydride Vapor Phase Epitaxy (HVPE) method is not less than 100 microns. However, the thickness of the second gallium nitride epitaxial layer 130 is not less than 200 μm in order to facilitate the subsequent processing steps. Alternatively, the thickness of the second gallium nitride epitaxial layer is not less than 500 μm. Alternatively, the first and second electrodes may be,the thickness of the second gallium nitride epitaxial layer may be up to 1 mm or even thicker.
Alternatively, in order to improve the growth environment of the second gallium nitride epitaxial layer, the surface of the first gallium nitride epitaxial layer 120 may be planarized before the growth of the second gallium nitride epitaxial layer 130, thereby obtaining a favorable growth surface for the second gallium nitride epitaxial layer. For example, chemical-mechanical polishing (CMP) may be used to planarize the surface of the epitaxial first gallium nitride epitaxial layer 120 layer. The planarization may remove about 10% to 20% of the first gallium nitride epitaxial layer 120. For example, the first gallium nitride epitaxial layer 120 may be grown to a thickness of 30 microns and about 3 microns to about 6 microns removed using chemical-mechanical polishing (CMP). In a sense, the first gallium nitride epitaxial layer 120 may be a sacrificial layer of a component of the present disclosure. Thus, the thickness of the first gallium nitride epitaxial layer 120 may be less than 10 microns. To reduce the generation of surface errors due to extensive removal, it is therefore not necessary to perform extensive polishing removal at this point to avoid potential sub-surface damage caused by the polishing process. Experimental evidence indicates that the depth of polishing damage in GaN is in the range of less than about 1.5 μm to about 2.6 μm for a typical CMP process. Thus, according to some embodiments, an initial epitaxial layer thickness of about 30 microns and CMP removal of about 3 microns to about 6 microns may provide suitable material quality on the processing surface of GaN.
After obtaining the first gallium nitride epitaxial layer 120 or the second gallium nitride epitaxial layer (in the case of the second gallium nitride epitaxial layer), wax or a low melting point metal in a molten state is applied to the outer surface of the gallium nitride epitaxial layer. The melting point of such waxes or low melting point metals is typically between 60 ℃ and 90 ℃. The coating process is carried out in a nitrogen atmosphere and is maintained at a temperature slightly above the melting point of the wax or low melting metal by about 5-10 c so that the viscosity coefficient is not so low that it flows to a point where it cannot be applied, for example between 100 and 200 mPa. After the upper surface of the first gan epitaxial layer 120 is coated with the adhesive layer 126, the surfaces of the support sheet 130 and the adhesive layer 126 are provided with a temperature and pressure at the side of the support sheet 130 opposite to the adhesive layer 126 so that the support sheet is bonded to the device wafer 120 through the adhesive layer. The material of the support sheet 130 preferably has a thermal expansion coefficient close to that of the first gallium nitride epitaxial layer 120 to avoid adverse mechanical effects due to the different thermal expansion coefficients between the two materials bonded to each other. In some cases, glass may be advantageous for delivering laser light during subsequent laser fusion stripping. The support sheet may also be a metallic material or a dielectric material or a semiconductor material, such as the exact same semiconductor material of the first gallium nitride epitaxial layer 120.
For bonding, temperature and pressure are applied after the support sheet 130, the adhesive layer 126, and the first gallium nitride epitaxial layer 120 are combined. The bonding temperature may be lowered below the computer capacity of the adhesive 126, for example between 50 ℃ and 60 ℃, and the pressure may be between 0.18MPA and 0.20 MPA. The duration of the bonding treatment is between 5 and 9 minutes. During the bonding process, the assembly may be placed in a nitrogen atmosphere. Or may be placed in an air environment. The assembly is then cooled and the shear strength of the adhesive layer 126 in the cooled assembly is above 30 MPa.
In summary, the step of adhering the support sheet 130 having an area equal to or larger than the area of the first gallium nitride epitaxial layer 120 to the upper surface of the first gallium nitride epitaxial layer 120 by the adhesive 126 includes: coating a layer of wax or low-melting-point metal in a molten state on the upper surface of the first gallium nitride epitaxial layer 120; attaching the support sheet 130 to the wax layer or the low melting point metal layer 126; placing the first gallium nitride epitaxial layer 120, the support sheet 130 and the wax layer or low-melting-point metal layer 126 in an inert gas atmosphere and keeping them at a temperature at which the wax layer or low-melting-point metal layer is in a molten state for 3-10 minutes; and reducing the ambient temperature to solidify the wax layer or the low melting point metal layer.
Fig. 2 shows a scanning electron micrograph of a combination comprising a first gallium nitride epitaxial layer 120, a support sheet 130, and an adhesive layer 126 formed on a PSS substrate according to an embodiment of the disclosure. As shown in fig. 2, it clearly shows the first gallium nitride epitaxial layer 120 grown on the PSS substrate 110. The first gallium nitride epitaxial layer 120 is coated with an adhesive layer 126. The support sheet 130 is adhered to the upper surface of the adhesive layer 126.
FIG. 3 is a schematic diagram illustrating a process for peeling a composite containing an epitaxial layer of gallium nitride from a PSS substrate according to an embodiment of the present disclosure. As shown in fig. 3, the composite comprising the first gallium nitride epitaxial layer 120 is stripped from the PSS substrate 110. The stripping process can adopt a laser irradiation mode, a cavity-assisted physical stripping mode and a thermal stress stripping mode. Specifically, the connection interface between the first gallium nitride epitaxial layer 120 and the PSS substrate 110 is melted at high temperature by irradiating laser light from the lower part of the PSS, thereby separating the first gallium nitride epitaxial layer 120 from the PSS substrate 110. Alternatively, as shown in fig. 1, during the growth of the first gallium nitride epitaxial layer 120, a cavity is formed between the first gallium nitride epitaxial layer 120 and the PSS substrate 110, and therefore, the connection between the first gallium nitride epitaxial layer 120 and the PSS substrate 110 is weak due to the cavity, and the first gallium nitride epitaxial layer 120 can be glassed off the PSS substrate 110 by applying a physical force along the interface of the first gallium nitride epitaxial layer 120 and the PSS substrate 110. Alternatively, a certain thermal stress may be applied between the first gallium nitride epitaxial layer 120 and the PSS substrate 110 so that the two are separated.
Alternatively, the lower surface of the first gallium nitride epitaxial layer 120 may be polished by chemical-mechanical polishing (CMP) to form a flat lower surface. Due to the support sheet, the first gan epitaxial layer 120 is not damaged during the polishing process.
FIG. 4 is a schematic diagram illustrating a process for peeling a composite containing an epitaxial layer of gallium nitride from a PSS substrate according to an embodiment of the present disclosure.
Specifically, since the melting point temperature of the bonding wax is relatively low, the combination of the gan epitaxial layer 120, the bonding layer 126, and the support sheet 130 can be directly placed in high-temperature hot water or sprayed with high-temperature steam, and the three can be naturally separated. Alternatively, the external force may be applied directly from the side of the support sheet 130, such that the external force generates a shear strength between the contact surfaces of the adhesive layer 126 and the support sheet 130 greater than the shear strength, for example, 35-40MPa, to separate the support sheet 130 from the gallium nitride epitaxial layer 120. Alternatively, in the case where the support sheet 130 is made of transparent glass or the same material as the gallium nitride epitaxial layer 120, the support sheet 130 may be separated from the gallium nitride epitaxial layer 120 by heating and melting the adhesive layer 126 by irradiating laser light from the side of the support sheet 130 opposite to the adhesive layer 126. Alternatively, the outer surface of the support sheet 130 in the combination of the gallium nitride epitaxial layer 120, the bonding layer 126, and the support sheet 130 may be placed on a hot plate at a temperature above the melting point of the bonding layer 126, and the combination is heated from the side of the support sheet 130, thereby melting and flowing out the bonding layer 126 layer, thereby separating the support sheet 130 from the gallium nitride epitaxial layer 120.
The wax or low-melting metal used may be a commercially available laminated wax or the like. The melting point of these waxes is generally between 60 and 90 ℃. The wax is suitable for bonding various materials such as glass, hard plastic, brass, silicon wafers, quartz crystals and metal, and does not need special treatment on the surface of a workpiece. And can maintain a firm bond even during the grinding or polishing of the gallium nitride epitaxial layer 120, are widely used for fixing thin sheet members, such as adhesion of semiconductor crystals or crystal blanks. Due to the good thermoplastic adhesion of the bonding wax 126, the formed working layer is thin, so that the gallium nitride epitaxial layer 120 can be ensured not to be distorted and deformed, the flatness of the gallium nitride epitaxial layer 120 is maintained, and the material structure of the gallium nitride epitaxial layer 120 cannot be affected during bonding or separation under the condition that the wax with a lower melting point, such as 65 ℃, is selected.
After the support sheet 130 is separated from the gan epitaxial layer 120, it is easy to clean because of its low melting point and water solubility. Plasma water can be used for cleaning, and no residue is left on the surface of the wafer.
The process of separating the (2021) GaN epitaxial wafer from the substrate is described above by way of specific embodiments. The solution described herein may be implemented as a method, in which at least one embodiment has been provided. The actions performed as part of the methods may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts concurrently, even though shown as sequential acts in illustrative embodiments. Further, the method may include more acts than those shown in some embodiments, and fewer acts than those shown in other embodiments.
Although the figures generally show small portions of epitaxially grown GaN layers, it should be understood that a large area or the entire substrate may be covered with such epitaxially grown layers. Furthermore, integrated circuit devices (e.g., transistors, diodes, thyristors, light emitting diodes, laser diodes, photodiodes, etc.) may be fabricated using epitaxially grown materials. In some embodiments, the integrated circuit device may be used in consumer electronics devices, such as smart phones, tablets, PDAs, computers, televisions, sensors, lighting, displays, and application specific integrated circuits.
While at least one illustrative embodiment of the invention has been described herein, many alternatives, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description is by way of example only and is not intended as limiting. The invention is limited only as defined in the following claims and the equivalents thereto.
Claims (6)
1. A method for stripping an epitaxial layer of gallium nitride from a substrate, the method comprising:
growing a first gallium nitride epitaxial layer on the patterned sapphire substrate in an MOCVD (metal organic chemical vapor deposition) or MBE (molecular beam epitaxy) deposition mode, forming a cavity between the first gallium nitride epitaxial layer and the patterned sapphire substrate, and growing a second gallium nitride epitaxial layer on the upper surface of the first gallium nitride epitaxial layer;
adhering a support sheet with the area equal to or larger than that of the second gallium nitride epitaxial layer on the upper surface of the gallium nitride epitaxial layer through an adhesive and carrying out curing treatment;
peeling the first and second gallium nitride epitaxial layers and the support sheet integrally from the patterned sapphire substrate by applying a horizontal lateral physical stress to a side of an interface between the first gallium nitride epitaxial layer and the patterned sapphire substrate; and
separating the second gallium nitride epitaxial layer from the support sheet by heating the adhesive at the interface between the second gallium nitride epitaxial layer and the support sheet such that the adhesive melts.
2. The method for stripping a gallium nitride epitaxial layer from a substrate according to claim 1, further comprising:
before a support sheet is adhered to the upper surface of the second gallium nitride epitaxial layer through an adhesive, the second gallium nitride epitaxial layer is subjected to a thinning treatment through a chemical-mechanical polishing method to obtain a gallium nitride epitaxial layer with a predetermined thickness.
3. The method for peeling off a gallium nitride epitaxial layer from a substrate according to claim 1, wherein the step of adhering a support sheet having an area equal to or larger than that of the second gallium nitride epitaxial layer to an upper surface of the second gallium nitride epitaxial layer with an adhesive comprises:
coating a layer of wax or low-melting-point metal in a molten state on the upper surface of the second gallium nitride epitaxial layer;
attaching a support sheet to the wax layer or the low-melting-point metal layer;
placing the first and second gallium nitride epitaxial layers, the support sheet, and the wax layer or the low-melting-point metal layer in an inert gas atmosphere and maintaining them at a temperature such that the wax layer or the low-melting-point metal layer is in a molten state for 3 to 10 minutes; and
and reducing the ambient temperature to solidify the wax layer or the low-melting-point metal layer.
4. The method for peeling off a gallium nitride epitaxial layer from a substrate according to claim 1, wherein the adhesive heating of the interface between the second gallium nitride epitaxial layer and the support sheet is heated by directly placing the first and second gallium nitride epitaxial layers and the support sheet on a hot plate.
5. The method for peeling off a gallium nitride epitaxial layer from a substrate according to any one of claims 1 to 4, wherein the curing treatment process is performed in a nitrogen atmosphere.
6. The method for peeling off a gallium nitride epitaxial layer from a substrate according to claim 5, the melting point of the binder being in the range of 60 ℃ -90 ℃.
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|---|---|---|---|---|
| CN1779900A (en) * | 2004-11-23 | 2006-05-31 | 北京大学 | Large-area and low-power laser stripping method for GaN-base epitaxial layer |
| CN101555627A (en) * | 2009-04-30 | 2009-10-14 | 苏州纳晶光电有限公司 | Laser peeling method of gallium nitride-based epitaxial film |
| CN103021946A (en) * | 2012-12-05 | 2013-04-03 | 北京大学 | Method of preparing GaN monocrystal substrate in mechanical removal way |
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2018
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1779900A (en) * | 2004-11-23 | 2006-05-31 | 北京大学 | Large-area and low-power laser stripping method for GaN-base epitaxial layer |
| CN101555627A (en) * | 2009-04-30 | 2009-10-14 | 苏州纳晶光电有限公司 | Laser peeling method of gallium nitride-based epitaxial film |
| CN103021946A (en) * | 2012-12-05 | 2013-04-03 | 北京大学 | Method of preparing GaN monocrystal substrate in mechanical removal way |
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Denomination of invention: Method of peeling gallium nitride epitaxial layer from substrate Effective date of registration: 20230828 Granted publication date: 20200724 Pledgee: China Construction Bank Corporation Xi'an Chang'an Road Branch Pledgor: XI'AN SAIFULESI SEMICONDUCTOR TECHNOLOGY CO.,LTD. Registration number: Y2023980054100 |