Preparation method of aluminum nitride template and aluminum nitride template

Abstract

The application discloses a preparation method of an aluminum nitride template and the aluminum nitride template. The preparation method of the aluminum nitride template comprises the following steps: performing preset temperature cleaning treatment on an original substrate; performing aluminum paving on the original substrate to form an aluminum nitride nucleation layer after ammonia treatment; performing epitaxial growth of an unintentionally doped aluminum nitride epitaxial layer on the aluminum nitride nucleation layer, wherein the thickness of the unintentionally doped aluminum nitride epitaxial layer is 0-2 um; and performing patterning treatment on the unintentionally doped aluminum nitride epitaxial layer to form an aluminum nitride template with a required pattern. The above scheme solves the problem that the crystal quality of a growth material is not high due to a huge stress difference between subsequent nitride epitaxial growth and a substrate.

Description

TECHNICAL FIELD

[0001] The application relates to the field of semiconductor materials, and particularly relates to a preparation method of an aluminum nitride template and the aluminum nitride template. BACKGROUND

[0002] With the further development of microelectronic technology and optoelectronic technology, the first generation of semiconductor silicon material cannot meet the ever-changing needs of people in some fields due to the performance of the material itself. Therefore, people are constantly looking for other new semiconductor materials to achieve new functions in different scenarios, and then turn their attention to the second generation of semiconductors represented by gallium arsenide, indium arsenide and indium phosphide. They can be applied in high-speed integrated circuits, laser optoelectronic devices because of their direct band gap and high electron mobility. In the 1990s, the third generation of semiconductor materials represented by AlN, InN and GaN has broad application prospects in super-speed microelectronic devices, super-high frequency microwave devices and optoelectronic devices due to their higher electron mobility and wide wavelength coverage, which has attracted great interest from scholars. Aluminum nitride material is the third generation of semiconductor materials and can be widely used in piezoelectricity, LED, communication and other fields. As a wide band gap semiconductor, aluminum nitride has broad application prospects in the development of high-temperature, high-frequency and high-power microwave devices, radiation-resistant devices, ultraviolet detectors and short-wave light-emitting diodes.

[0003] AlN, InN and GaN materials are generally epitaxially grown on silicon, sapphire and silicon carbide substrates. Due to the lattice mismatch between the growth material and the substrate, there is a large stress difference when N compounds are epitaxially grown, which makes it difficult to obtain high-quality N compound materials, and to some extent, restricts the wide application of nitride materials. Therefore, how to solve the problem of the large stress difference between the substrate and the epitaxial material has become an urgent problem for N compound epitaxial growth. SUMMARY

[0004] The application aims to provide a preparation method of an aluminum nitride template and the aluminum nitride template, and solve the problem of low crystal quality of the growth material caused by the large stress difference between the subsequent nitride epitaxial growth and the substrate.

[0005] The application discloses a preparation method of an aluminum nitride template, which comprises the following steps:

[0006] The original substrate is subjected to a preset temperature cleaning treatment;

[0007] Aluminum is laid on the original substrate, and an aluminum nitride nucleation layer is formed after ammonia treatment;

[0008] An unintentionally doped aluminum nitride epitaxial layer is epitaxially grown on the aluminum nitride nucleation layer, wherein the thickness of the unintentionally doped aluminum nitride epitaxial layer is 0-2 um;

[0009] The non-intentionally doped aluminum nitride epitaxial layer is subjected to a patterning process to form an aluminum nitride template with a desired pattern.

[0010] Optionally, the preset temperature in the step of performing the preset temperature cleaning process on the original substrate is 1100-1200℃.

[0011] Optionally, the step of forming the aluminum nitride nucleation layer on the original substrate by aluminum deposition and ammonia treatment comprises:

[0012] The temperature of the original substrate is rapidly decreased to 900-960℃, and the gas pressure in the reaction chamber is controlled at 50-80mbar.

[0013] The trimethylaluminum is first introduced into the reaction chamber, and then the ammonia gas and the trimethylaluminum are simultaneously introduced to grow the aluminum nitride nucleation layer on the original substrate.

[0014] Optionally, the thickness of the aluminum nitride nucleation layer is 30-50nm.

[0015] Optionally, the step of epitaxially growing the non-intentionally doped aluminum nitride epitaxial layer on the aluminum nitride nucleation layer comprises:

[0016] The temperature of the original substrate is increased to 1100-1250℃, and the gas pressure in the reaction chamber is controlled at 20-40mbar.

[0017] The aluminum nitride material is grown on the aluminum nitride nucleation layer without intentional doping.

[0018] The temperature is gradually increased during the growth of the aluminum nitride material, so that the aluminum nitride material gradually changes from three-dimensional growth to two-dimensional growth, thereby forming the non-intentionally doped aluminum nitride epitaxial layer.

[0019] Optionally, the original substrate is formed by one or more of silicon, sapphire, silicon carbide, and zinc oxide.

[0020] Optionally, the non-intentionally doped aluminum nitride epitaxial layer is formed by MOCVD, MBE or HVPE method in the step of epitaxially growing the non-intentionally doped aluminum nitride epitaxial layer on the aluminum nitride nucleation layer.

[0021] Optionally, the patterning process in the step of forming the aluminum nitride template with a desired pattern on the non-intentionally doped aluminum nitride epitaxial layer comprises wet etching, dry etching or growing N-compound epitaxial growth stop layer material.

[0022] Optionally, the patterning process is growing N-compound epitaxial growth stop layer material, and the N-compound epitaxial growth stop layer material comprises silicon dioxide N-compound epitaxial stop layer or silicon nitride N-compound epitaxial stop layer.

[0023] The application also discloses an aluminum nitride template formed by using the preparation method of the aluminum nitride template.

[0024] The application releases stress between the aluminum nitride and the original substrate by performing a patterning process on the non-intentionally doped aluminum nitride epitaxial layer. When the N compound is subsequently epitaxially grown, the previous substrate is covered by the aluminum nitride, so that the lattice mismatch can be reduced to a certain extent, and the aluminum nitride template is subjected to the patterning process, and the stress existing in the aluminum nitride template is also released to a certain extent, which is beneficial to the subsequent epitaxial growth of the N compound. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings included are intended to provide a further understanding of the embodiments of the application, and constitute a part of the specification, and are used to illustrate the embodiments of the application together with the text description, and to explain the principles of the application. Obviously, the accompanying drawings in the following description only show some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings. In the drawings:

[0026] Figure 1 is a schematic diagram of steps of a preparation method of an aluminum nitride template of the application;

[0027] Figure 2 is a schematic diagram of a cross section of the aluminum nitride template of the application;

[0028] Figure 3 is a schematic diagram of a top view of the aluminum nitride template of the application.

[0029] It is shown in the figure that: 1, a substrate; 2, an aluminum nitride nucleation layer; 3, a non-intentionally doped aluminum nitride epitaxial layer; 4, a subsequent epitaxial layer. DETAILED DESCRIPTION

[0030] It should be understood that the terms used herein, the disclosed specific structures and functional details, are only for the purpose of describing specific embodiments, and are representative, but the application can be embodied in many alternative forms, and should not be interpreted as being limited to the embodiments described herein.

[0031] In the description of the present application, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating relative importance, or implying the number of the indicated technical features. Therefore, unless otherwise specified, the features defined with "first", "second" can explicitly or implicitly include one or more of the features; the meaning of "multiple" is two or more. The term "comprise" and any variation thereof means non-exclusive inclusion, and one or more other features, integers, steps, operations, units, components and / or combinations thereof can exist or be added. The specific meaning of the above terms in the present application can be understood according to the specific circumstances by those skilled in the art.

[0032] The present application will be described in detail below with reference to the accompanying drawings and optional embodiments.

[0033] Figure 1 is a schematic diagram of a step of a preparation method of an aluminum nitride template of the present application, as shown, the preparation method of the aluminum nitride template comprises the steps of: Figure 1

[0034] S1: performing a preset temperature cleaning treatment on the original substrate;

[0035] S2: performing aluminum paving on the original substrate to form an aluminum nitride nucleation layer after ammoniation;

[0036] S3: epitaxially growing an unintentionally doped aluminum nitride epitaxial layer on the aluminum nitride nucleation layer, wherein the thickness of the unintentionally doped aluminum nitride epitaxial layer is 0-2um;

[0037] S4: performing a patterning treatment on the unintentionally doped aluminum nitride epitaxial layer to form an aluminum nitride template with a desired pattern.

[0038] The present application releases a certain stress between the aluminum nitride and the original substrate by performing a patterning treatment on the unintentionally doped aluminum nitride epitaxial layer. When epitaxially growing a N compound later, since the previous substrate is covered by the aluminum nitride, the lattice mismatch can be reduced to a certain extent, and the stress existing in the aluminum nitride template is also released to a certain extent, which is beneficial to the subsequent epitaxial growth of the N compound.

[0039] Specifically, the preset temperature in the step of performing a preset temperature cleaning treatment on the original substrate is 1100-1200℃. The original substrate is formed by one or more materials selected from the group consisting of silicon, sapphire, silicon carbide, and zinc oxide. The silicon substrate is taken as an example in the embodiments of the present application. The silicon substrate is cleaned at high temperature to remove impurities and oxides on the surface of the silicon substrate. The specific reaction conditions are performed in an epitaxial growth reaction chamber, that is, the silicon substrate is placed in the epitaxial growth reaction chamber, and the temperature of the original substrate is raised to 1100-1200℃ under a hydrogen atmosphere. ​

[0040] Specifically, the step of S2: forming an aluminum nitride nucleation layer on the original substrate after aluminum deposition and ammonia treatment comprises:

[0041] S21: rapidly lowering the temperature of the original substrate to 900-960℃, and controlling the gas pressure in the reaction chamber to 50-80mbar;

[0042] S22: first introducing trimethylaluminum into the reaction chamber, and then simultaneously introducing ammonia and trimethylaluminum to grow an aluminum nitride nucleation layer on the original substrate.

[0043] Specifically, the thickness of the aluminum nitride nucleation layer is 30-50nm.

[0044] Specifically, the step of S3: epitaxially growing an unintentionally doped aluminum nitride epitaxial layer on the aluminum nitride nucleation layer comprises:

[0045] S31: raising the temperature of the original substrate to 1100-1250℃, and controlling the gas pressure in the reaction chamber to 20-40mbar;

[0046] S32: growing an aluminum nitride material on the aluminum nitride nucleation layer without intentional doping;

[0047] S33: gradually raising the temperature during the growth of the aluminum nitride material, so that the aluminum nitride material gradually changes from three-dimensional growth to two-dimensional growth, forming an unintentionally doped aluminum nitride epitaxial layer.

[0048] In this embodiment, the temperature is gradually raised during the growth of the material, so that the aluminum nitride material gradually changes from three-dimensional growth to two-dimensional growth, and the dislocations caused by the lattice mismatch between the previous substrate and the substrate are merged. The patterned processing on the unintentionally doped aluminum nitride epitaxial layer can release some stress between the aluminum nitride and the original substrate. When the N compound is subsequently epitaxially grown, the previous substrate is covered by the aluminum nitride, so that the lattice mismatch is reduced to a certain extent, and the stress existing in the aluminum nitride template is also released to a certain extent, which is beneficial to the subsequent epitaxial growth of the N compound.

[0049] Specifically, the step of epitaxially growing an unintentionally doped aluminum nitride epitaxial layer on the aluminum nitride nucleation layer uses MOCVD or MBE or HVPE method to form an unintentionally doped aluminum nitride epitaxial layer. Epitaxy is a process in which atoms or molecules of a certain substance are arranged in a regular manner and grow directionally on the surface of a substrate. A continuous, complete single crystal layer with a corresponding relationship with the lattice structure of the substrate is obtained, which is called an epitaxial layer, and the process is called epitaxial growth.

[0050] MOCVD (Metal-organic Chemical Vapor Deposition) is a new type of vapor phase epitaxial growth technology developed on the basis of VPE (Vapor Phase Epitaxy). MOCVD is a vapor phase epitaxy on a substrate using thermal decomposition reaction of organic compounds of group III and group II elements and hydrides of group V and group VI elements as crystal growth source materials to grow thin layer single crystal materials of various group III-V and group II-VI compound semiconductors and their multi-element solid solutions. Crystal growth in the MOCVD system is usually carried out in a cold-wall quartz (stainless steel) reaction chamber under normal pressure or low pressure (10-100 Torr) with H2, the substrate temperature is 500-1200℃, and a direct current heating graphite susceptor (substrate is above the graphite susceptor) is used, and H2 carries metal organics to the growth zone by temperature controllable liquid source bubbling. Molecular beam epitaxy (MBE) is a newly developed epitaxial film forming method, which is also a special vacuum coating process. In an ultra-high vacuum condition, the vapor generated by heating the furnace containing various required components is collimated into a molecular beam or an atomic beam through a small hole, which is directly sprayed onto a single crystal substrate at an appropriate temperature. By controlling the scanning of the molecular beam on the substrate, molecules or atoms can be "grown" on the substrate to form a thin film layer by layer according to the crystal arrangement.

[0051] Specifically, in the step S4 of performing a patterning process on the unintentionally doped aluminum nitride epitaxial layer to form an aluminum nitride template with a desired pattern, the patterning process includes wet etching, dry etching, or growing N-compound epitaxial growth termination layer material.

[0052] In the patterning process step, a photoresist layer is first formed on the unintentionally doped aluminum nitride epitaxial layer, and the photoresist is exposed to light through a mask or mask plate to form a photoresist with a predetermined pattern. The unintentionally doped aluminum nitride epitaxial layer not covered by the photoresist is etched or RIE or ICP etching means to etch the pattern to be removed.

[0053] Specifically, the patterning process is to grow N-compound epitaxial growth termination layer material, and the N-compound epitaxial growth termination layer material includes silicon dioxide N-compound epitaxial termination layer or silicon nitride N-compound epitaxial termination layer.

[0054] For the patterning process on the unintentionally doped aluminum nitride epitaxial layer, the etching depth can be judged by etching time to avoid etching the aluminum nitride nucleation layer below the unintentionally doped aluminum nitride epitaxial layer.

[0055] In another embodiment, a detection device can also be added in the reaction chamber, which mainly emits polarized light to detect the refractive index of the film layer on the substrate. Since the non-intentionally doped aluminum nitride epitaxial layer adopts a three-dimensional to two-dimensional growth mode, the refractive index of the film layer of the non-intentionally doped aluminum nitride epitaxial layer will change all the time, but the refractive index of the film layer of the aluminum nitride nucleation layer in the non-intentionally doped aluminum nitride epitaxial layer is constant. Therefore, in this embodiment, by setting the detection device, during the step of patterning the non-intentionally doped aluminum nitride epitaxial layer, specifically during the etching process, the refractive index of the etched film layer is detected in real time. When the refractive index of the film layer continues to change, the etching continues. When the refractive index of the film layer no longer changes, the etching is stopped. When the refractive index of the film layer no longer changes, it means that the non-intentionally doped aluminum nitride epitaxial layer has been etched completely, and the film layer of the aluminum nitride nucleation layer has been exposed. Therefore, etching does not need to continue.

[0056] Figure 2 is a schematic view of the cross section of the aluminum nitride template of the present application, as shown in Figure 2 The preparation method of the aluminum nitride template corresponds to the following steps:

[0057] The silicon substrate is placed in the epitaxial growth reaction chamber, and the temperature of the silicon substrate 1 is raised to 1100-1200°C in a hydrogen atmosphere. The silicon substrate is high-temperature cleaned to remove impurities and oxides on the surface. Then, the temperature of the silicon substrate is quickly reduced to 900-960°C, the gas pressure is controlled at 50-80 mbar, trimethylaluminum is first introduced into the reaction chamber, and then ammonia and trimethylaluminum are introduced at the same time to grow an aluminum nitride nucleation layer on the substrate, with a thickness of 30-50 nm. Then, the temperature of the silicon substrate is raised to 1100-1250°C, and the gas pressure is controlled at 20-40 mbar. The aluminum nitride layer is grown without intentional doping, with a thickness of 0-2 um. The temperature is gradually increased during the growth of the non-intentionally doped aluminum nitride epitaxial layer. Then, the silicon substrate for growing aluminum nitride is taken out, and periodic patterning of the target pattern is performed using photolithography and other methods. Then, the patterns that need to be removed are etched by RIE or ICP etching method. Finally, the photoresist is removed by developing, and the schematic view of the aluminum nitride template as shown in Figure 2 is obtained. Finally, the aluminum nitride template is cleaned and placed in the reaction chamber to grow the desired nitride material on the aluminum nitride template.

[0058] As shown in Figure 2 , the aluminum nitride template includes a silicon substrate 1, an aluminum nitride nucleation layer 2, and a non-intentionally doped aluminum nitride epitaxial layer 3. The aluminum nitride template is cleaned and placed in the reaction chamber to grow the desired nitride material 4 on the aluminum nitride template. Figure 3 is a top view schematic view of the aluminum nitride template, Figure 3 in which no nitride material 4 is formed on the aluminum nitride template.

[0059] Specifically, after etching the part of the unintentionally doped aluminum nitride epitaxial layer, the exposed aluminum nitride nucleation layer, the growth rate of the nitride material on the part of the aluminum nitride nucleation layer is very slow. The etching affects the original crystal structure, so that the growth rate of the nitride material on the aluminum nitride nucleation layer is greatly reduced. The growth rate of the nitride material on the unintentionally doped aluminum nitride epitaxial layer is faster, and then the aluminum nitride template and the schematic diagram of growing the nitride material as shown in FIG. 4 are formed. Figure 2

[0060] It should be noted that the inventive concept of the present application can form a very large number of embodiments, but the length of the application file is limited and cannot list them one by one, so the above-described embodiments or technical features can be combined to form new embodiments without conflict. The combination of each embodiment or technical feature will enhance the original technical effect.

[0061] The above is a further detailed description of the present application in combination with specific optional embodiments, and it cannot be considered that the specific implementation of the present application is limited to these descriptions. For ordinary skilled persons in the art to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be considered as falling within the scope of protection of the present application.​

Claims

1. A method for preparing an aluminum nitride template, characterized in that, Including the following steps: The original substrate is cleaned at a preset temperature. Aluminum is deposited on the original substrate and then ammonited to form an aluminum nitride nucleation layer. An unintentionally doped aluminum nitride epitaxial layer is grown on an aluminum nitride nucleation layer, wherein the thickness of the unintentionally doped aluminum nitride epitaxial layer is 0 μm to 2 μm. Patterning is performed on an unintentionally doped aluminum nitride epitaxial layer to form an aluminum nitride template with the desired pattern; The step of patterning an unintentionally doped aluminum nitride epitaxial layer to form an aluminum nitride template with the desired pattern includes: Etching of unintentionally doped aluminum nitride epitaxial layers; The refractive index of the etched film is monitored in real time. Etching continues as the refractive index of the film changes continuously, and stops when the refractive index of the film no longer changes. The aluminum nitride nucleation layer is exposed at the etched location; The preset temperature in the step of cleaning the original substrate at a preset temperature is 1100℃~1200℃. The step of depositing aluminum on the original substrate and forming an aluminum nitride nucleation layer after ammoniation includes: The temperature of the original substrate was rapidly reduced to 900℃~960℃, and the gas pressure in the reaction chamber was controlled at 50mbar-80mbar. First, trimethylaluminum is introduced into the reaction chamber, and then ammonia and trimethylaluminum are introduced simultaneously to grow an aluminum nitride nucleation layer on the original substrate. The step of epitaxially growing an unintentionally doped aluminum nitride epitaxial layer on the aluminum nitride nucleation layer includes: The temperature of the original substrate is raised to 1100℃-1250℃, and the gas pressure in the reaction chamber is controlled at 20mbar-40mbar. Aluminum nitride material is grown on aluminum nitride nucleation layers without intentional doping; During the growth of aluminum nitride material, the temperature is gradually increased, causing the aluminum nitride material to gradually change from three-dimensional growth to two-dimensional growth, forming an unintentionally doped aluminum nitride epitaxial layer.

2. The method for preparing the aluminum nitride template according to claim 1, characterized in that, The thickness of the aluminum nitride nucleation layer is 30~50nm.

3. The method for preparing the aluminum nitride template according to claim 1, characterized in that, The original substrate is formed from one or more materials selected from silicon, sapphire, silicon carbide, and zinc oxide.

4. The method for preparing the aluminum nitride template according to claim 1, characterized in that, In the step of epitaxially growing an unintentionally doped aluminum nitride epitaxial layer on the aluminum nitride nucleation layer, the unintentionally doped aluminum nitride epitaxial layer is formed using MOCVD, MBE, or HVPE.

5. The method for preparing the aluminum nitride template according to claim 1, characterized in that, In the step of patterning an unintentionally doped aluminum nitride epitaxial layer to form an aluminum nitride template with the desired pattern, the patterning process includes wet etching, dry etching, or growth of a nitrogen oxide epitaxial growth termination layer material.

6. The method for preparing the aluminum nitride template according to claim 5, characterized in that, The patterning process involves growing a Nibium epitaxial growth termination layer material, which includes a silicon dioxide Nibium epitaxial termination layer or a silicon nitride Nibium epitaxial termination layer.

7. An aluminum nitride template, characterized in that, It is formed using the aluminum nitride template preparation method according to any one of claims 1-6.

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