Method for rapidly and accurately detecting dislocation of aluminum nitride wafer at room temperature and application of method

Abstract

The invention belongs to the technical field of crystal detection, and relates to crystal dislocation detection, in particular to a method for rapidly and accurately detecting dislocation of an aluminum nitride wafer at room temperature and application of the method. Specifically, the method comprises the following steps: adding the AlN crystal into a reaction reagent, carrying out oxidation reaction for 1-2 minutes, and detecting the surface dislocation of the crystal after reaction treatment by using an atomic force microscope. According to the invention, the AlN crystal can be processed at room temperature, and the dislocation density of the AlN crystal can be detected by observing the processed dislocation pit through a microscope. The detection method provided by the invention not only can be used as a substitute for a high-temperature corrosion method, but also has great advantages for rapidly and accurately detecting the dislocation density of the AlN crystal at room temperature, so that the detection method can be used for quality control of the AlN crystal, and has good practical application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of crystal detection, and relates to the detection of crystal dislocations, and specifically to a method for quickly and accurately detecting dislocations of aluminum nitride wafers at room temperature and an application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] The third-generation semiconductor material aluminum nitride (AlN) has excellent properties such as ultra-wide bandgap, good ultraviolet transmittance and high thermal conductivity. It has broad application prospects in the fields of ultraviolet optoelectronic devices, solar-blind photodetector devices, and high-voltage power electronic devices. AlN single crystals have huge market value and broad application prospects. At present, the preparation of 2-inch AlN single crystal substrates has been achieved in China, but problems such as crystal size, defect density, yield and preparation cost still need to be solved. Combined with crystal growth technology, studying the properties and structure of the material can provide an important basis for improving growth technology and improving crystal quality.

[0004] At present, the research on AlN dislocation detection is far from sufficient. Chinese patent CN 105483833A discloses a method for dislocation corrosion of AlN single crystals, which uses molten sodium hydroxide and potassium hydroxide to corrode AlN single crystals at 300-400°C for 3-20 minutes, and observes the hexagonal dislocation diagram under an optical microscope. The strong alkali used not only causes serious damage to the AlN single crystal, but also has adverse effects on the environment and operators. In addition, the degree of high-temperature corrosion is difficult to control. When the corrosion time is short, small-sized dislocations fail to appear. When the corrosion time is too long, the corrosion pits expand and merge, resulting in inaccurate dislocation density. At the same time, there are problems such as equipment loss, energy consumption, and safety risks. Chinese patent CN

[0005] 106971954B discloses a method for calibrating screw dislocations of a III-nitride semiconductor material, wherein nanomaterials are grown on the III-nitride semiconductor material to be tested, and then observed by a scanning electron microscope (SEM) to obtain the screw dislocation position and screw dislocation density of the III-nitride semiconductor material. However, the growth of nanomaterials still requires heating conditions, and the reaction time is as long as 1-3 hours, which is not conducive to the detection of AlN dislocations.

[0006] Unlike gallium nitride, under certain conditions, water molecules adsorbed on the surface of AlN will react with AlN to generate ammonia and hydrogen, and the nitrogen atoms inside may also react with water molecules. The above phenomenon will be exacerbated under heating conditions, so the contact between AlN and water molecules and high temperature conditions should be avoided or reduced as much as possible during testing, processing, transportation and application. Summary of the invention

[0007] Based on the above-mentioned deficiencies in the prior art, the present invention provides a method for quickly and accurately detecting dislocations of aluminum nitride wafers at room temperature and its application. Specifically, the present invention can process crystals (especially AlN) at room temperature, and observe the dislocation pits after treatment under a microscope to detect the dislocation density of the crystal (especially AlN). The detection method provided by the present invention can not only serve as a substitute for high-temperature corrosion methods, but also has great advantages for quickly and accurately detecting the dislocation density of crystals (especially AlN) at room temperature. Based on the above research results, the present invention is completed.

[0008] In order to achieve the above technical objectives, the present invention relates to the following technical solutions:

[0009] One aspect of the present invention provides a method for quickly and accurately detecting dislocations of aluminum nitride wafers at room temperature, the method comprising: adding a crystal to be tested into a reaction reagent for treatment for 1 to 2 minutes at room temperature, and detecting the surface dislocation density of the crystal after the reaction; wherein the reaction reagent comprises a reactant and a promoter.

[0010] Among them, the reactant specifically includes any one or more of persulfate, perborate, and percarbonate, and its mass concentration is controlled to be 0.1-5%. Further, the persulfate, perborate, and percarbonate are sodium salts; the accelerator includes transition metal salts such as nickel sulfate, cobalt sulfate, and iron sulfate, and its mass concentration is controlled to be 0.01-3%.

[0011] Using persulfate reactants and transition metal salt promoters to treat AlN crystals, persulfate radicals with extremely high oxidizing ability are generated (the oxidation potential of persulfate radicals is 2.5-3.1V), which can quickly oxidize the crystal at room temperature. Because (1) the lattice at the dislocation is distorted and more active than the surrounding lattice; (2) the atomic spacing at the dislocation is shorter than that in the surrounding perfect lattice, and the bonding force between atoms is weaker, the dislocation exhibits higher reactivity. Therefore, it is easy to oxidize dislocations to form dislocation pits, and the dislocation distribution and dislocation density can be understood by microscopic observation.

[0012] The present invention uses a high oxidation potential reaction system to quickly (~1 min) treat AlN crystals at room temperature, which greatly reduces the hydrolysis of AlN crystals. In addition, it avoids the problem of difficult control of high-temperature corrosion process, obtains independent and clear dislocation pits, and thus more accurately calculates dislocation density.

[0013] In the present invention, the surface dislocation density of the reacted crystal can be detected using a microscope, especially an atomic force microscope (AFM).

[0014] The second aspect of the present invention provides application of the above method in quality control of aluminum nitride wafers.

[0015] The AlN wafer processed by the present invention has independent dislocation pits, and compared with the intersection and expansion of dislocation pits after etching, has a more real and accurate dislocation density.

[0016] Beneficial technical effects of one or more of the above technical solutions:

[0017] 1. The above technical solution uses a reaction system with a high oxidation potential to treat AlN crystals, which reacts quickly (~1 min) at room temperature, thus avoiding the influence of hydrolysis on AlN crystals to a great extent.

[0018] 2. The above technical solution processes AlN crystals at room temperature, the reaction degree is easy to control, and independent and clear dislocation pits are easily formed, which is conducive to the accurate calculation of dislocation density, thereby facilitating the quality control of AlN crystals, and therefore has good practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0020] Figure 1 is an AFM image of the AlN wafer after the reaction in Example 1 of the present invention, where the scale is 2.5 μm;

[0021] Figure 2 is an AFM image of the AlN wafer after the reaction in Example 2 of the present invention, where the scale is 2.5 μm;

[0022] Figure 3 is an AFM image of the AlN wafer after the reaction in Example 3 of the present invention, where the scale is 2.5 μm;

[0023] Figure 4 This is a SEM image of the AlN wafer after etching in Comparative Example 1 of the present invention, with a scale of 20 μm. DETAILED DESCRIPTION

[0024] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0025] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments of the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0026] As mentioned above, the high temperature corrosion process used in the prior art is difficult to control, and it is difficult to make all surface dislocations appear while avoiding the intersection and expansion of the dislocation pits that appeared first. The method of heating the growth of nanomaterials to detect screw dislocations requires heating conditions, and the adverse effects of AlN wafer hydrolysis cannot be ignored. At the same time, there are problems of energy consumption and high cost.

[0027] In view of this, the present invention provides a method for quickly and accurately detecting dislocations of AlN wafers at room temperature. Specifically, the method comprises: adding a crystal to a reaction reagent for reaction treatment for 1 to 2 minutes, and then detecting the surface dislocation density of the crystal after the reaction; wherein the reaction reagent comprises a reactant and a promoter.

[0028] Among them, the reactant specifically includes any one or more of persulfate, perborate, and percarbonate, and its mass concentration is controlled to be 0.1-5%. Further, the persulfate, perborate, and percarbonate are sodium salts; the accelerator includes transition metal salts such as nickel sulfate, cobalt sulfate, and iron sulfate, and its mass concentration is controlled to be 0.01-3%.

[0029] The present invention uses a high-oxidizing agent to treat the AlN wafer, reacts quickly at room temperature, and then uses AFM to observe the distribution and density of dislocation pits. Compared with high-temperature corrosion, it has the advantage of easy control of the treatment process. Compared with growing nanomaterials on screw dislocations under heating conditions, room temperature and short time (~1 min) can effectively reduce the degree of hydrolysis of the AlN wafer.

[0030] The AlN wafer processed by the present invention has independent dislocation pits, and compared with the intersection and expansion of dislocation pits after etching, has a more real and accurate dislocation density.

[0031] In the present invention, the surface dislocation density of the crystal after the reaction can be detected by a microscope, especially an atomic force microscope (AFM). The persulfate and transition metal salt system can be used to treat the AlN wafer with high chemical bond energy, and an independent dislocation pit image can be obtained under the AFM lens.

[0032] At the same time, in order to prevent pollutants attached to the crystal surface from affecting the reaction efficiency and accuracy, in some specific embodiments of the present invention, the crystal is preferentially cleaned before adding the reaction reagent. At the same time, in order to prevent hydrolysis of the AlN crystal, it is preferably cleaned with an organic reagent.

[0033] In another specific embodiment of the present invention, the organic solvent includes but is not limited to ethanol and acetone, which is beneficial to cleaning pollutants on the surface of the AlN wafer, including organic matter, metal ions, etc.

[0034] In another specific embodiment of the present invention, ultrasonic assisted cleaning is used. More specifically, the ultrasonic frequency is 25-30 khz, the ultrasonic time is 5-60 minutes, and the number of repetitions is 2-5 times. Prolonging the ultrasonic time and increasing the number of repetitions are conducive to obtaining a clean AlN wafer surface.

[0035] Specifically, after cleaning, an inert gas (such as nitrogen) gun is used to blow dry the sample, so as to avoid other drying methods from introducing impurities, thereby affecting the accuracy of detecting dislocation pits.

[0036] In another specific embodiment of the present invention, a cleaning process is performed after the reaction process is completed, and then the detection is performed. The cleaning process can be the same as the cleaning process before the reaction process.

[0037] In another specific embodiment of the present invention, application of the above method in quality control of aluminum nitride wafers is provided.

[0038] The present invention is further explained by the following examples, but they are not intended to limit the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0039] Example 1

[0040] The method for rapidly and accurately detecting dislocation of an aluminum nitride wafer at room temperature comprises the following steps:

[0041] Step 1: Place an AlN wafer (0.2011 g) in 50 mL of ethanol and ultrasonicate at a frequency of 28 kHz for 15 min. Repeat this three times and then blow dry the surface of the AlN wafer with a nitrogen gun.

[0042] Step 2: Place the AlN wafer in a glass dish, add 2 mL of 1% sodium persulfate solution and 1 mL of 0.5% ferrous sulfate solution, respectively, and take out the AlN wafer after standing for 1 minute.

[0043] Step 3: Repeat step 1 and use AFM to detect the dislocation pits on the surface of the AlN wafer.

[0044] Example 2

[0045] The method for rapidly and accurately detecting dislocation of an aluminum nitride wafer at room temperature comprises the following steps:

[0046] Step 1: Place the AlN wafer (0.2301 g) in 50 mL of ethanol and ultrasonicate at a frequency of 28 kHz for 15 min. Repeat this three times and then blow dry the surface of the AlN wafer with a nitrogen gun.

[0047] Step 2: Place the AlN wafer in a glass dish, add 2 mL of 0.5% sodium perborate solution and 1 mL of 0.3% ferrous sulfate solution, respectively, and take out the AlN wafer after standing for 2 minutes.

[0048] Step 3: Repeat step 1 and use AFM to detect the dislocation pits on the surface of the AlN wafer.

[0049] Example 3

[0050] The method for rapidly and accurately detecting dislocation of an aluminum nitride wafer at room temperature comprises the following steps:

[0051] Step 1: Place an AlN wafer (0.2101 g) in 50 mL of ethanol and ultrasonicate at a frequency of 28 kHz for 15 min. Repeat this three times and then blow dry the surface of the AlN wafer with a nitrogen gun.

[0052] Step 2: Place the AlN wafer in a glass dish, add 2 mL of 1% sodium persulfate solution and 1 mL of 0.5% ferrous sulfate solution, respectively, and take out the AlN wafer after standing for 3 minutes.

[0053] Step 3: Repeat step 1 and use AFM to detect the dislocation pits on the surface of the AlN wafer.

[0054] Comparative Example 1

[0055] The method for detecting dislocation of aluminum nitride wafer by high temperature corrosion comprises the following steps:

[0056] Step 1: Place an AlN wafer (0.2121 g) in 50 mL of ethanol and ultrasonicate at a frequency of 28 kHz for 15 min. Repeat this three times and then blow dry the surface of the AlN wafer with a nitrogen gun.

[0057] Step 2: Place the AlN wafer in molten potassium hydroxide at 310°C and take it out after etching for 6 minutes.

[0058] Step 3: Repeat step 1 and use SEM to detect the dislocation pits on the surface of the AlN wafer.

[0059] Figure 1 is an AFM image of the AlN wafer after reaction treatment in Example 1, Figure 4 This is the SEM image of the AlN wafer after etching in Comparative Example 1. Figure 1The dislocation pits in the middle are presented in a clear and independent state, and the calculated dislocation density is 5.6*10 7 / cm 2 . Figure 4 The two dislocation pits shown have intersected (in the white circle), and the calculated dislocation density is 2.0*10 6 / cm 2 Compared with the dislocation density calculated in Example 1, it is one order of magnitude smaller, which indicates that there are still some small-sized dislocations that have not been presented. However, further extending the corrosion time or increasing the corrosion temperature will lead to more serious intersections of dislocation pits, which will also affect the accuracy of the dislocation density. Figure 2 This is the AFM image of the AlN wafer after the reaction treatment in Example 2. Independent and clear dislocation pits can also be observed. The dislocation density is calculated to be 3.1*10 7 / cm 2 , which is in the same order of magnitude as the result in Example 1. Figure 3 This is an AFM image of the AlN wafer after the reaction treatment in Example 3. In the figure, it can be seen that some dislocation pits are merged (in the white circle), which means that the reaction time of 3 minutes is too long and is not suitable for detecting dislocations in the AlN wafer.

[0060] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to perform equivalent replacements on parts thereof. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention. Although the above describes the specific implementation methods of the present invention, it is not intended to limit the protection scope of the present invention. Those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or deformations that can be made by those skilled in the art without creative labor are still within the protection scope of the present invention.

Claims

1. A method for rapidly and accurately detecting dislocations in AlN wafers at room temperature, characterized in that: The method comprises: adding crystals to a reaction reagent for reaction treatment for 1 to 2 minutes, and then detecting the surface dislocation density of the crystals after the reaction; wherein the reaction reagent comprises a reactant and a promoter; wherein the reactant specifically comprises any one or more of persulfate, perborate and percarbonate, and the promoter comprises any one or more of nickel sulfate, cobalt sulfate and iron sulfate.

2. The method according to claim 1, characterized in that The mass concentration of the reactant is controlled to be 0.1-5%. Furthermore, the persulfate, perborate and percarbonate are sodium salts.

3. The method according to claim 1, characterized in that The mass concentration of the accelerator is controlled to be 0.01-3%.

4. The method according to claim 1, characterized in that The surface dislocation density of the reacted crystal was detected using atomic force microscopy.

5. The method according to claim 1, characterized in that Before adding the reaction reagent to the crystal, a cleaning treatment is performed, preferably using an organic reagent for cleaning.

6. The method according to claim 5, characterized in that The organic solvent includes ethanol and acetone.

7. The method according to claim 5, characterized in that The cleaning process adopts ultrasonic assisted cleaning; preferably, the ultrasonic frequency is 25-30 khz, the ultrasonic time is 5-60 min, and the number of repetitions is 2-5 times.

8. The method according to claim 5, characterized in that After cleaning, use an inert gas gun to blow dry.

9. The method according to claim 1, characterized in that After the reaction process is completed, cleaning treatment is performed first, and then detection is performed.

10. Application of the method according to any one of claims 1 to 9 in quality control of aluminum nitride wafers.

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