InAs / GaSb superlattice detector epitaxial wafer back substrate thinning and planarization processing method

Abstract

The invention provides an InAs / GaSb superlattice detector epitaxial wafer back substrate thinning and planarization processing method, relates to the technical field of infrared detector manufacturing, and aims at solving the technical problem that in a traditional infrared detector manufacturing process, due to the fact that a substrate is too thick, infrared attenuation and surface damage are caused, and the performance of a detector is affected. According to the method, the InAs / GaSb II type superlattice detector epitaxial wafer is subjected to front surface wax sealing protection, back surface substrate grinding and thinning, back surface planarization polishing, back surface chemical cleaning and dewaxing cleaning, 80%-90% of the thickness of the back surface GaSb substrate of the InAs / GaSb II type superlattice detector epitaxial wafer is removed, and planarization of the back surface of the epitaxial wafer can be realized. The surface damage is effectively removed, the surface roughness is reduced, the infrared transmittance of medium waves and long waves of the detector is improved by 60% and 20% or above respectively, and therefore the technical problem that in a traditional technology, the performance of the detector is affected by infrared attenuation and surface damage due to the fact that the substrate is too thick is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared detector manufacturing, and more specifically, to a method for thinning and planarizing the back substrate of an InAs / GaSb superlattice detector epitaxial wafer. Background Art

[0002] The InAs / GaSb type-II superlattice material has become the core material for the next generation of infrared detectors to replace mercury cadmium telluride due to its tunable energy band (0 - 0.8 eV), low Auger recombination rate, and high uniformity. The InAs / GaSb type-II superlattice detector chip is made by epitaxially growing an InAs / GaSb superlattice structure material on a GaSb substrate and belongs to a back-illuminated device. The InAs / GaSb superlattice detector and the readout circuit form an infrared detector chip in a flip-chip interconnection form. After the infrared light passes through the GaSb substrate, it is absorbed by the InAs / GaSb superlattice material and converted into an electrical signal; after being read out, converted, amplified, and noise-reduced by the interconnection circuit, the signal is output. Therefore, the stronger the infrared light incident on the superlattice material, the stronger the electrical signal output by the detector, and the better the imaging effect of the detector. The InAs / GaSb superlattice detector is a cooled detector with an operating temperature of 77 K. At this temperature, a relatively thick GaSb substrate will reduce the infrared transmittance and thus affect the imaging quality of the detector. In addition, it is inevitable to cause damage on the substrate surface during the detector preparation process, and these damages will also affect the detection effect of the device. Therefore, it is necessary to thin the back substrate of the detector and perform planarization treatment to remove the surface damage. Summary of the Invention

[0003] In view of this, the present invention provides a method for thinning and planarizing the back substrate of an InAs / GaSb superlattice detector epitaxial wafer, aiming to solve the technical problems of infrared attenuation caused by an overly thick substrate and surface damage affecting the detector performance in the traditional infrared detector manufacturing process.

[0004] One aspect of the present invention provides a method for thinning and planarizing the back substrate of an InAs / GaSb superlattice detector epitaxial wafer, including: obtaining an InAs / GaSb type-II superlattice detector epitaxial wafer; performing wax sealing protection treatment on the front surface of the InAs / GaSb type-II superlattice detector epitaxial wafer, where the front surface represents the superlattice structure layer; performing grinding and thinning treatment on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer, where the back surface represents the GaSb substrate; performing planarization treatment on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after the grinding and thinning treatment; performing chemical cleaning treatment on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after the planarization treatment; and performing dewaxing and cleaning treatment on the InAs / GaSb type-II superlattice detector epitaxial wafer to complete the thinning and low-damage surface planarization treatment of the GaSb substrate.

[0005] According to an embodiment of the present invention, the wax sealing protection treatment on the front surface of the InAs / GaSb type-II superlattice detector epitaxial wafer includes: placing the hot-melt solid bonding wax on a heating platform and heating it to 180°C to 200°C to completely melt the bonding wax, where the melting point of the bonding wax is 155°C to 200°C; using a dispensing machine to uniformly coat the molten bonding wax on the surface of the ceramic fixing plate in a spiral path, where the thickness of the wax layer is controlled to be 180 μm to 230 μm; slowly pressing the front surface of the InAs / GaSb type-II superlattice detector epitaxial wafer onto the wax-coated surface of the ceramic fixing plate, applying a pressure of 10 N to 20 N to remove air bubble residues and make the bonding uniform; cooling it at a rate of 2°C / min to 4°C / min to 40°C, and then naturally cooling it to room temperature for curing.

[0006] According to an embodiment of the present invention, the grinding and thinning treatment on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer includes: using a first diamond grinding wheel thinning machine to roughly grind and thin the GaSb substrate on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer, grinding and removing 60% to 65% of the thickness of the GaSb substrate on the back surface, where the grinding wheel grit of the first diamond grinding wheel thinning machine used for rough grinding and thinning is #320, and the rough grinding rate is 10 μm / s; using a second diamond grinding wheel thinning machine to finely grind and thin the GaSb substrate on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer, grinding and removing 10% to 20% of the thickness of the GaSb substrate on the back surface, where the grinding wheel grit of the second diamond grinding wheel thinning machine used for fine grinding and thinning is #2000, and the fine grinding rate is 2 μm / s.

[0007] According to an embodiment of the present invention, the planarization process for the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after grinding and thinning treatment includes: using a first silica polishing liquid to perform rough polishing on the GaSb substrate on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after grinding and thinning treatment through chemical mechanical polishing, wherein the rough polishing removes 5% of the thickness of the back GaSb substrate, and the roughness < 10 nm; using a second silica polishing liquid to perform fine polishing on the GaSb substrate on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after rough polishing through chemical mechanical polishing, wherein the fine polishing removes 5% of the thickness of the back GaSb substrate, and the roughness < 0.5 nm.

[0008] According to an embodiment of the present invention, the particle size of the first silica polishing liquid is 80 nm to 100 nm, and the pH value is 10 to 10.5.

[0009] According to an embodiment of the present invention, the particle size of the second silica polishing liquid is 25 nm to 50 nm, and the pH value is 10 to 10.5.

[0010] According to an embodiment of the present invention, the chemical cleaning process for the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after planarization treatment includes: using a mixed solution of hydrofluoric acid, phosphoric acid, and citric acid to perform chemical flushing on the GaSb substrate on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after planarization treatment to remove surface residual particles and metal ions, wherein the volume ratio of the hydrofluoric acid, phosphoric acid, and citric acid mixed solution is 3:1:1; using deionized water to perform secondary flushing on the GaSb substrate on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after chemical flushing to remove chemical reagent residues, and drying with nitrogen.

[0011] According to an embodiment of the present invention, the flushing temperature required for the chemical flushing process is 15°C to 20°C, and the flushing time is 10 s to 20 s.

[0012] According to an embodiment of the present invention, the flushing temperature required for the secondary flushing process is 15°C to 20°C, and the flushing time is 20 s to 30 s.

[0013] According to an embodiment of the present invention, the dewaxing and cleaning treatment of the InAs / GaSb type-II superlattice detector epitaxial wafer includes: immersing the ceramic fixing plate and the InAs / GaSb type-II superlattice detector epitaxial wafer in trichloroethylene reagent and heating to 40°C to 50°C to dissolve and separate the bonding wax from the InAs / GaSb type-II superlattice detector epitaxial wafer and the ceramic fixing plate; immersing the InAs / GaSb type-II superlattice detector epitaxial wafer in acetone and ethanol in sequence for ultrasonic cleaning treatment, wherein the ultrasonic frequency is 40 kHz to 80 kHz, and the ultrasonic cleaning time is 5 min to 10 min; taking out the InAs / GaSb type-II superlattice detector epitaxial wafer from ethanol and drying it with nitrogen.

[0014] Compared with the prior art, the method for thinning and planarizing the back substrate of the InAs / GaSb superlattice detector epitaxial wafer provided by the embodiment of the present invention has at least the following beneficial effects:

[0015] The method for thinning and planarizing the back substrate of the InAs / GaSb superlattice detector epitaxial wafer provided by the embodiment of the present invention, through five process treatments of front wax sealing protection, back substrate grinding and thinning, back planarization polishing, back chemical cleaning and dewaxing cleaning on the InAs / GaSb type-II superlattice detector epitaxial wafer, removes 80% to 90% of the thickness of the GaSb substrate on the back of the InAs / GaSb type-II superlattice detector epitaxial wafer, and can achieve the planarization of the back of the epitaxial wafer, effectively remove surface damage, reduce surface roughness, so that the mid-wave and long-wave infrared transmittances of the detector are increased by more than 60% and 20% respectively, thus solving the technical problems of infrared attenuation caused by too thick substrate and surface damage affecting the performance of the detector in the traditional process. Description of the Drawings

[0016] Through the following description of the embodiments of the present invention with reference to the drawings, the above and other objects, features and advantages of the present invention will become clearer. In the drawings:

[0017] Figure 1 Schematically shows a flowchart of the method for thinning and planarizing the back substrate of the InAs / GaSb superlattice detector epitaxial wafer according to an embodiment of the present invention;

[0018] Figure 2 Schematically shows a topographic map of the back of the InAs / GaSb superlattice detector epitaxial wafer before thinning according to an embodiment of the present invention;

[0019] Figure 3 Schematically shows a topographic map of the back of the InAs / GaSb superlattice detector epitaxial wafer after thinning and planarizing treatment according to an embodiment of the present invention;

[0020] Figure 4 Schematically shown is a diagram demonstrating the roughness effect after thinning and planarization treatment on the back side of an InAs / GaSb superlattice detector epitaxial wafer according to an embodiment of the present invention. Detailed implementation manners

[0021] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In the following detailed description, for the sake of explanation, numerous specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, obviously, one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of the present invention.

[0022] The terms used herein are merely for describing specific embodiments and are not intended to limit the present invention. The terms "including", "comprising", etc. used herein indicate the presence of features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0023] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0024] In cases where expressions similar to "at least one of A, B, and C, etc." are used, generally, it should be interpreted according to the meaning commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include, but is not limited to, a system having only A, having only B, having only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0025] InAs / GaSb type-II superlattice materials, with their tunable energy bands (0 - 0.8 eV), low Auger recombination rate, and high uniformity, have become the core materials for next-generation infrared detectors to replace mercury cadmium telluride. The InAs / GaSb type-II superlattice detector chip is made by epitaxially growing InAs / GaSb superlattice structure materials on a GaSb substrate and belongs to a back-illuminated device. The InAs / GaSb superlattice detector and the readout circuit form an infrared detector chip in a flip-chip interconnection form. After infrared light passes through the GaSb substrate, it is absorbed by the InAs / GaSb superlattice material and converted into an electrical signal; after being read out, converted, amplified, and noise-reduced by the interconnection circuit, the signal is output. Therefore, the stronger the infrared light incident on the superlattice material, the stronger the electrical signal output by the detector, and the better the imaging effect of the detector. The InAs / GaSb superlattice detector is a cooled detector with an operating temperature of 77 K. At this temperature, the relatively thick GaSb substrate will reduce the infrared transmittance and thus affect the imaging quality of the detector. In addition, it is difficult to avoid damage on the substrate surface during the detector fabrication process, and these damages will also affect the detection effect of the device. Therefore, it is necessary to thin the back substrate of the detector and perform planarization treatment to remove surface damages.

[0026] Based on this, an embodiment of the present invention provides a method for thinning and planarizing the back substrate of an InAs / GaSb superlattice detector epitaxial wafer, aiming to solve the technical problems of infrared attenuation caused by too thick a substrate and surface damage affecting the detector performance in traditional infrared detector manufacturing processes.

[0027] Figure 1 Schematically shows a flowchart of the method for thinning and planarizing the back substrate of an InAs / GaSb superlattice detector epitaxial wafer according to an embodiment of the present invention.

[0028] As Figure 1 shown, the method for thinning and planarizing the back substrate of the InAs / GaSb superlattice detector epitaxial wafer in this embodiment may include operations S1 - S6, for example.

[0029] In operation S1, an InAs / GaSb type-II superlattice detector epitaxial wafer is obtained.

[0030] In operation S2, wax sealing protection treatment is performed on the front surface of the InAs / GaSb type-II superlattice detector epitaxial wafer, where the front surface represents the superlattice structure layer.

[0031] In operation S3, grinding and thinning treatment is performed on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer, where the back surface represents the GaSb substrate.

[0032] In operation S4, planarization treatment is performed on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after grinding and thinning treatment.

[0033] In operation S5, chemical cleaning treatment is performed on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after planarization treatment.

[0034] In operation S6, dewaxing and cleaning treatment is performed on the InAs / GaSb type-II superlattice detector epitaxial wafer to complete the thinning of the GaSb substrate and the surface low-damage planarization treatment.

[0035] The method for thinning and planarizing the back substrate of the InAs / GaSb superlattice detector epitaxial wafer provided by the embodiment of the present invention, through five process treatments of front surface wax sealing protection, back substrate grinding and thinning, back surface planarization polishing, back surface chemical cleaning, and dewaxing and cleaning on the InAs / GaSb type-II superlattice detector epitaxial wafer, removes 80% - 90% of the thickness of the GaSb substrate on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer, and can achieve the planarization of the back surface of the epitaxial wafer, effectively remove surface damage, reduce surface roughness, so that the mid-wave and long-wave infrared transmittance of the detector are respectively increased by more than 60% and 20%, thus solving the technical problems of infrared attenuation caused by too thick substrate and surface damage affecting the performance of the detector in the traditional process.

[0036] According to the embodiment of the present invention, in operation S1, an InAs / GaSb type-II superlattice detector epitaxial wafer is obtained. For example, taking a 2-inch InAs / GaSb type-II superlattice detector epitaxial wafer as an example, the thickness of the GaSb substrate on the back surface of the 2-inch InAs / GaSb type-II superlattice detector epitaxial wafer is 500 μm.

[0037] According to the embodiment of the present invention, in operation S2, wax sealing protection treatment is performed on the front surface of the InAs / GaSb type-II superlattice detector epitaxial wafer. For example, it may include:

[0038] (1) Wax melting: Place the hot-melt solid bonding wax on the heating platform and heat it up to 180°C - 200°C to completely melt the bonding wax. Among them, the melting point of the bonding wax is 155°C - 200°C.

[0039] As a preferred embodiment, specifically, the hot-melt solid bonding wax can be heated up to 190°C.

[0040] (2) Wax coating: Use a dispensing machine to evenly coat the molten bonding wax on the surface of the ceramic fixing disk in a spiral path. Among them, the thickness of the wax layer is controlled at 180 μm - 230 μm.

[0041] As a preferred embodiment, during the waxing process, the thickness of the wax layer can be controlled within 200 ± 20 μm.

[0042] (3) Bonding: Slowly press the front side of the InAs / GaSb type-II superlattice detector epitaxial wafer onto the waxed surface of the ceramic fixing disk, and apply a pressure of 10 N to 20 N to remove residual air bubbles and make the bonding uniform.

[0043] As a preferred embodiment, slowly press the front side of the 2-inch InAs / GaSb type-II superlattice detector epitaxial wafer onto the waxed surface, and specifically, a pressure of 20 N can be applied to remove residual air bubbles and make the bonding uniform.

[0044] (4) Cooling and curing: Cool at a rate of 2 °C / min to 4 °C / min to 40 °C, and then naturally cool to room temperature for curing.

[0045] As a preferred embodiment, it can be specifically cooled to 40 °C at a rate of 4 °C / min.

[0046] According to the embodiment of the present invention, operation S3 performs a grinding and thinning process on the back side of the InAs / GaSb type-II superlattice detector epitaxial wafer, which may include, for example:

[0047] (1) Coarse grinding and thinning: Use a first diamond grinding wheel thinning machine to coarsely grind and thin the GaSb substrate on the back side of the InAs / GaSb type-II superlattice detector epitaxial wafer, and grind and remove 60% to 65% of the thickness of the back side GaSb substrate. Among them, the grinding wheel grit of the first diamond grinding wheel thinning machine used for coarse grinding and thinning is #320, and the coarse grinding rate is 10 μm / s.

[0048] As a preferred embodiment, use a first diamond grinding wheel thinning machine with a grit of #320 to coarsely grind and thin the GaSb substrate on the back side of the 2-inch InAs / GaSb type-II superlattice detector epitaxial wafer, and specifically, 300 μm of the back side substrate thickness can be ground and removed.

[0049] (2) Fine grinding and thinning: Use a second diamond grinding wheel thinning machine to finely grind and thin the GaSb substrate on the back side of the InAs / GaSb type-II superlattice detector epitaxial wafer, and grind and remove 10% to 20% of the thickness of the back side GaSb substrate. Among them, the grinding wheel grit of the second diamond grinding wheel thinning machine used for fine grinding and thinning is #2000, and the fine grinding rate is 2 μm / s.

[0050] As a preferred embodiment, use a second diamond grinding wheel thinning machine with a grit of #2000 to finely grind and thin the GaSb substrate on the back side of the 2-inch InAs / GaSb type-II superlattice detector epitaxial wafer, and specifically, 100 μm of the back side substrate thickness can be finely ground and removed.

[0051] According to an embodiment of the present invention, operation S4 performs a planarization process on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after grinding and thinning treatment. For example, it may include:

[0052] (1) Coarse polishing: Using a first silica polishing liquid, the GaSb substrate on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after grinding and thinning treatment is coarsely polished by chemical mechanical polishing. Among them, the coarse polishing treatment removes 5% of the thickness of the back GaSb substrate, and the roughness < 10 nm.

[0053] The particle size of the first silica polishing liquid is 80 nm to 100 nm, and the pH value is 10 to 10.5.

[0054] As a preferred embodiment, specifically, a silica polishing liquid with a particle size of 100 nm can be used to coarsely polish the GaSb substrate on the back surface of a 2-inch InAs / GaSb type-II superlattice detector epitaxial wafer by chemical mechanical polishing. The coarse polishing removes 25 μm of the back substrate thickness.

[0055] (2) Fine polishing: Using a second silica polishing liquid, the GaSb substrate on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after coarse polishing treatment is finely polished by chemical mechanical polishing. Among them, the fine polishing treatment removes 5% of the thickness of the back GaSb substrate, and the roughness < 0.5 nm.

[0056] The particle size of the second silica polishing liquid is 25 nm to 50 nm, and the pH value is 10 to 10.5.

[0057] As a preferred embodiment, specifically, a silica polishing liquid with a particle size of 25 nm can be used to finely polish the GaSb substrate on the back surface of a 2-inch InAs / GaSb type-II superlattice detector epitaxial wafer by chemical mechanical polishing. The fine polishing removes 25 μm of the back substrate thickness.

[0058] According to an embodiment of the present invention, operation S5 performs a chemical cleaning process on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after planarization treatment. For example, it may include:

[0059] (1) Chemical cleaning: Using a mixed solution of hydrofluoric acid, phosphoric acid, and citric acid to chemically rinse the GaSb substrate on the back surface of the InAs / GaSb type-II superlattice detector epitaxial wafer after planarization treatment to remove surface residual particles and metal ions. Among them, the volume ratio of the mixed solution of hydrofluoric acid, phosphoric acid, and citric acid is 3:1:1.

[0060] The rinsing temperature required for the chemical rinsing treatment is 15°C to 20°C, and the rinsing time is 10 s to 20 s.

[0061] As a preferred embodiment, a mixed solution of hydrofluoric acid, phosphoric acid, and citric acid at 20 °C (volume ratio: 3:1:1) can be specifically used to chemically rinse the GaSb substrate on the back of a 2-inch InAs / GaSb type-II superlattice detector epitaxial wafer for 15 s to remove surface residual particles and metal ions.

[0062] (2) Secondary rinsing: Deionized water is used to perform secondary rinsing on the GaSb substrate on the back of the InAs / GaSb type-II superlattice detector epitaxial wafer after chemical rinsing to remove residual chemical reagents, and nitrogen is used to blow it dry.

[0063] The rinsing temperature required for the secondary rinsing process is 15 °C to 20 °C, and the rinsing time is 20 s - 30 s.

[0064] As a preferred embodiment, deionized water at 20 °C can be specifically used to rinse the GaSb substrate on the back of a 2-inch InAs / GaSb type-II superlattice detector epitaxial wafer for 30 s to remove residual chemical reagents, and nitrogen is used to blow it dry.

[0065] According to an embodiment of the present invention, operation S6 performs dewaxing and cleaning treatment on the InAs / GaSb type-II superlattice detector epitaxial wafer, for example, it can include:

[0066] (1) Dewaxing: Immerse the ceramic fixing disk and the InAs / GaSb type-II superlattice detector epitaxial wafer in trichloroethylene reagent and heat it to 40 °C to 50 °C to dissolve and separate the bonding wax from the InAs / GaSb type-II superlattice detector epitaxial wafer and the ceramic fixing disk.

[0067] As a preferred embodiment, the ceramic fixing disk and the epitaxial wafer can be specifically immersed in trichloroethylene reagent and heated to 50 °C to dissolve and separate the bonding wax from the epitaxial wafer and the ceramic fixing disk.

[0068] (2) Removal of residual wax: Immerse the InAs / GaSb type-II superlattice detector epitaxial wafer in acetone and ethanol in sequence for ultrasonic cleaning treatment, wherein the ultrasonic frequency is 40 kHz to 80 kHz, and the ultrasonic cleaning time is 5 min to 10 min.

[0069] As a preferred embodiment, a 2-inch InAs / GaSb type-II superlattice detector epitaxial wafer is immersed in acetone and ethanol in sequence for ultrasonic cleaning. The ultrasonic frequency can be specifically 40 kHz, and the ultrasonic cleaning time can be specifically 10 min.

[0070] (3) Drying: Take out the InAs / GaSb type-II superlattice detector epitaxial wafer from ethanol and blow it dry with nitrogen.

[0071] After all the above operations, the thickness of the back substrate of the 2-inch InAs / GaSb superlattice detector epitaxial wafer is thinned to 50 μm, and the thinning removal rate reaches 90%.

[0072] Figure 2 Schematically shows the morphology diagram of the back side of the InAs / GaSb superlattice detector epitaxial wafer before thinning according to an embodiment of the present invention.

[0073] As Figure 2 shown, before thinning, there are obvious scratches and unevenness on the back side of the 2-inch InAs / GaSb superlattice detector epitaxial wafer.

[0074] Figure 3 Schematically shows the morphology diagram of the back side of the InAs / GaSb superlattice detector epitaxial wafer after thinning and planarization according to an embodiment of the present invention.

[0075] As Figure 3 shown, after thinning and planarization, the back side of the 2-inch InAs / GaSb superlattice detector epitaxial wafer is smooth and without damage.

[0076] Figure 4 Schematically shows the roughness effect display diagram of the back side of the InAs / GaSb superlattice detector epitaxial wafer after thinning and planarization according to an embodiment of the present invention.

[0077] As Figure 4 shown, after detection by a microscope and a profilometer, the back side of the thinned 2-inch InAs / GaSb superlattice detector epitaxial wafer is flat and without damage, and the roughness is 0.333 nm.

[0078] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagram may represent a module, a segment of a program, or a portion of code that contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions noted in the blocks may occur in a different order than that noted in the accompanying drawings. For example, two consecutive blocks shown may actually be executed substantially in parallel, or they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram or flowchart, and combinations of blocks in the block diagram or flowchart, can be implemented by a dedicated hardware-based system that performs the specified functions or operations, or by a combination of dedicated hardware and computer instructions. Those skilled in the art will understand that the features described in the various embodiments of the present invention can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features described in the various embodiments of the present invention can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present invention.

[0079] The embodiments of the present invention have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Although the embodiments have been described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and all such substitutions and modifications should fall within the scope of the present invention.

Claims

1. A method for thinning and flattening the back substrate of an InAs / GaSb superlattice detector epitaxial wafer, characterized in that: The method comprises: Obtain InAs / GaSb type II superlattice detector epitaxial wafers; Performing wax sealing protection treatment on the front side of the InAs / GaSb type II superlattice detector epitaxial wafer, wherein the front side represents the superlattice structure layer; Grinding and thinning the back side of the InAs / GaSb type II superlattice detector epitaxial wafer, wherein the back side represents the GaSb substrate; Flattening the back side of the InAs / GaSb II type superlattice detector epitaxial wafer after grinding and thinning; Chemically cleaning the back side of the planarized InAs / GaSb type II superlattice detector epitaxial wafer; The InAs / GaSb type II superlattice detector epitaxial wafer is subjected to a dewaxing and cleaning treatment to complete the thinning of the GaSb substrate and the low-damage flattening of the surface.

2. The method according to claim 1, characterized in that The wax sealing protection treatment of the front side of the InAs / GaSb type II superlattice detector epitaxial wafer comprises: Placing hot-melt solid adhesive wax on a heating platform and heating it to 180°C to 200°C to completely melt the adhesive wax, wherein the melting point of the adhesive wax is 155°C to 200°C; The molten adhesive wax is evenly coated on the surface of the ceramic fixed plate in a spiral path by using a dispensing machine, wherein the thickness of the wax layer is controlled to be 180 μm-230 μm; Slowly press the front side of the InAs / GaSb II type superlattice detector epitaxial wafer onto the wax-coated surface of the ceramic fixing plate, applying a pressure of 10N to 20N to eliminate residual bubbles and ensure uniform bonding; Cool to 40℃ at a rate of 2℃ / min ~4℃ / min, and then cool naturally to room temperature for solidification.

3. The method according to claim 1, characterized in that The grinding and thinning process of the back side of the InAs / GaSb type II superlattice detector epitaxial wafer comprises: The GaSb substrate on the back side of the InAs / GaSb type II superlattice detector epitaxial wafer is rough-ground and thinned by a first diamond grinding wheel thinning machine, and 60% to 65% of the thickness of the GaSb substrate on the back side is removed by grinding, wherein the grinding wheel grit size of the first diamond grinding wheel thinning machine used for rough grinding and thinning is #320, and the rough grinding rate is 10 μm / s; The GaSb substrate on the back side of the InAs / GaSb type II superlattice detector epitaxial wafer is finely ground and thinned by a second diamond grinding wheel thinning machine, and 10% to 20% of the thickness of the back GaSb substrate is removed by grinding. The grinding wheel grit size of the second diamond grinding wheel thinning machine used for fine grinding and thinning is #2000, and the fine grinding rate is 2 μm / s.

4. The method according to claim 1, characterized in that: The planarization process of the back side of the InAs / GaSb type II superlattice detector epitaxial wafer after grinding and thinning comprises: The first silicon dioxide polishing liquid is used to perform a rough polishing process on the GaSb substrate on the back side of the InAs / GaSb type II superlattice detector epitaxial wafer after grinding and thinning by chemical mechanical polishing, wherein the rough polishing process removes 5% of the thickness of the GaSb substrate on the back side, and the roughness is less than 10 nm; The second silicon dioxide polishing liquid is used to perform fine polishing on the GaSb substrate on the back side of the InAs / GaSb type II superlattice detector epitaxial wafer after the rough polishing through chemical mechanical polishing, wherein the fine polishing removes 5% of the thickness of the back side GaSb substrate and the roughness is less than 0.5 nm.

5. The method according to claim 4, characterized in that The particle size of the first silicon dioxide polishing liquid is 80 nm-100 nm, and the pH value is 10-10.

5.

6. The method according to claim 4, characterized in that The particle size of the second silicon dioxide polishing liquid is 25 nm-50 nm, and the pH value is 10-10.

5.

7. The method according to claim 1, characterized in that The chemical cleaning process of the back side of the planarized InAs / GaSb type II superlattice detector epitaxial wafer comprises: The GaSb substrate on the back of the planarized InAs / GaSb II superlattice detector epitaxial wafer is chemically rinsed with a mixture of hydrofluoric acid, phosphoric acid and citric acid to remove residual particles and metal ions on the surface, wherein the volume ratio of the mixture of hydrofluoric acid, phosphoric acid and citric acid is 3:1:1; The GaSb substrate on the back side of the InAs / GaSb type II superlattice detector epitaxial wafer after chemical rinsing was rinsed twice with deionized water to remove chemical reagent residues, and then dried with nitrogen.

8. The method according to claim 7, characterized in that The chemical flushing treatment requires a flushing temperature of 15°C to 20°C and a flushing time of 10s to 20s.

9. The method according to claim 7, characterized in that: The secondary flushing treatment requires a flushing temperature of 15°C to 20°C and a flushing time of 20s to 30s.

10. The method according to claim 2, characterized in that The dewaxing and cleaning process of the InAs / GaSb type II superlattice detector epitaxial wafer comprises: Immersing the ceramic fixing plate and the InAs / GaSb II superlattice detector epitaxial wafer in a trichloroethylene reagent and heating to 40° C. to 50° C., so that the bonding wax is dissolved and separated from the InAs / GaSb II superlattice detector epitaxial wafer and the ceramic fixing plate; The InAs / GaSb type II superlattice detector epitaxial wafer is sequentially immersed in acetone and ethanol for ultrasonic cleaning, wherein the ultrasonic frequency is 40 kHz to 80 kHz and the ultrasonic cleaning time is 5 min to 10 min; The InAs / GaSb type II superlattice detector epitaxial wafer was taken out from the ethanol and dried with nitrogen.

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