Method for rapid and accurate detection of dislocations in aluminum nitride wafer at room temperature and application thereof

Abstract

The application belongs to the technical field of crystal detection, and relates to detection of crystal dislocation, in particular to a method for rapidly and accurately detecting dislocation of an aluminum nitride wafer at room temperature and application thereof. Specifically, the method comprises: adding AlN crystal into a reaction reagent for oxidation reaction for 1-2 minutes, and then detecting the surface dislocation of the crystal after reaction treatment by using an atomic force microscope. The application can process AlN crystal at room temperature, and detect the dislocation density of the AlN crystal by observing the dislocation pits after treatment through a microscope. The detection method provided by the application 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 application can be used for quality control of the AlN crystal and has good practical application value.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of crystal detection, and relates to detection of dislocations of crystals, in particular to a method for rapidly and accurately detecting dislocations of aluminum nitride wafer at room temperature and application thereof. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing the understanding of the background of the present application and should not be taken as an acknowledgement or any form of suggestion that this information forms prior art that is already commonly known in the art.

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

[0004] At present, the research on AlN dislocation detection is still far from enough. Chinese patent CN 105483833A discloses a dislocation etching method of AlN single crystal, which uses molten sodium hydroxide and potassium hydroxide to etch AlN single crystal at 300-400℃ for 3-20min, and observes the hexagonal dislocation schematic diagram under an optical microscope. The strong base used not only causes serious damage to the AlN single crystal, but also has adverse effects on the environment and the operating personnel. In addition, the high-temperature etching degree is difficult to control, and when the etching time is short, small-size dislocations cannot be shown, and when the etching time is too long, the etching pits expand and converge, resulting in inaccurate measured dislocation density. At the same time, there are problems such as equipment loss, energy consumption, safety risk, etc. Chinese patent CN

[0005] 106971954B discloses a calibration method of screw dislocations of III-nitride semiconductor material, which grows nanomaterials on the III-nitride semiconductor material to be measured, and then observes 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 1-3h, which is not conducive to the detection of AlN dislocations.

[0006] Different from gallium nitride, under certain conditions, water molecules adsorbed on the surface of AlN will react with AlN to generate ammonia and hydrogen, and the internal nitrogen atoms may also react with water molecules. The above phenomenon will be more serious 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 detection, processing, transportation and application. SUMMARY

[0007] Based on the shortcomings of the prior art, the present application provides a method for rapidly and accurately detecting dislocations of an aluminum nitride wafer at room temperature and its application. Specifically, the present application can process crystals (especially AlN) at room temperature, and observe the dislocation pits after processing through a microscope to detect the dislocation density of the crystals (especially AlN). The detection method provided by the present application not only can be used as an alternative to the high-temperature corrosion method, but also has great advantages for rapidly and accurately detecting the dislocation density of crystals (especially AlN) at room temperature. Based on the above research results, the present application is completed.

[0008] To achieve the above technical purposes, the present application relates to the following technical solutions:

[0009] In one aspect of the present application, a method for rapidly and accurately detecting dislocations of an aluminum nitride wafer at room temperature is provided, which comprises: adding a crystal to be detected into a reaction reagent at room temperature for 1-2 min, and detecting the surface dislocation density of the crystal after reaction; wherein the reaction reagent comprises a reaction agent and a promoter.

[0010] Specifically, the reaction agent comprises any one or more of persulfate, perborate and percarbonate, and the mass concentration thereof is controlled to be 0.1-5%. Further, the persulfate, perborate and percarbonate are sodium salts; and the promoter comprises transition metal salts such as nickel sulfate, cobalt sulfate and iron sulfate, and the mass concentration thereof is controlled to be 0.01-3%.

[0011] The AlN crystal is treated by a persulfate reaction agent and a transition metal salt promoter to generate persulfate radicals with extremely high oxidation capacity (the oxidation potential of persulfate radicals is 2.5-3.1 V), which can rapidly oxidize the crystal at room temperature. Since (1) the lattice at the dislocation is twisted and more active than the surrounding lattice; and (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, the dislocation is easily oxidized to form a dislocation pit, and the dislocation distribution and dislocation density can be understood and calculated by observing the dislocation pit through a microscope.

[0012] The present application uses a reaction system with high oxidation potential to rapidly treat AlN crystals at room temperature (about 1 min), which greatly reduces the hydrolysis of AlN crystals. In addition, the problem of difficult control in the high-temperature corrosion process is avoided, and independent and clear dislocation pits are obtained, thereby more accurately calculating the dislocation density.

[0013] In the present application, the surface dislocation density of the crystal after the reaction can be detected by a microscope, especially an atomic force microscope (AFM).

[0014] In a second aspect of the present application, the above method is applied in the quality control of the aluminum nitride wafer.

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

[0016] The above one or more technical solutions have the following beneficial technical effects:

[0017] 1. The above technical solution uses a high oxidation potential reaction system to treat the AlN crystal, and the reaction is fast at room temperature (about 1 min), which greatly avoids the influence of hydrolysis on the AlN crystal.

[0018] 2. The above technical solution treats the AlN crystal at room temperature, and the reaction degree is easy to control, which is easy to form independent and clear dislocation pits, and is conducive to accurate calculation of the dislocation density, thereby being conducive to the quality control of the AlN crystal, and thus having good practical application value. BRIEF DESCRIPTION OF DRAWINGS

[0019] The drawings accompanying the specification of the present application form a part thereof and serve to provide further understanding of the present application, the exemplary embodiments of the present application and its description serve to explain the present application, and do not constitute an improper limitation on the present application.

[0020] Figure 1 is the AFM image of the AlN wafer after the reaction in Example 1 of the present application, and the scale in the figure is 2.5 μm;

[0021] Figure 2 is the AFM image of the AlN wafer after the reaction in Example 2 of the present application, and the scale in the figure is 2.5 μm;

[0022] Figure 3 is the AFM image of the AlN wafer after the reaction in Example 3 of the present application, and the scale in the figure is 2.5 μm;

[0023] Figure 4 is the SEM image of the AlN wafer after etching in Comparative Example 1 of the present application, and the scale in the figure is 20 μm. DETAILED DESCRIPTION

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

[0025] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0026] As described above, the high-temperature etching 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 first appearing dislocation pits. The method of detecting screw dislocations by heating and growing nanomaterials requires heating conditions, and the adverse effects of hydrolysis of the AlN wafer cannot be ignored, and there are problems of energy consumption and high cost.

[0027] Therefore, the present application provides a method for rapidly and accurately detecting dislocations of an AlN wafer at room temperature, and specifically, the method comprises: adding a crystal to a reaction reagent for reaction and treatment for 1-2 min, and then detecting the surface dislocation density of the crystal after reaction; wherein the reaction reagent comprises a reaction agent and a promoter.

[0028] The reaction agent specifically comprises any one or more of persulfate, perborate, and percarbonate, and the mass concentration thereof is controlled to be 0.1-5%, and further, the persulfate, perborate, and percarbonate are sodium salts; and the promoter comprises transition metal salts such as nickel sulfate, cobalt sulfate, and iron sulfate, and the mass concentration thereof is controlled to be 0.01-3%.

[0029] The present application uses a reaction reagent with high oxidation ability to treat an AlN wafer, and the reaction is rapidly carried out at room temperature, and then the distribution and density of dislocation pits are observed by AFM. Compared with high-temperature etching, the present application has the advantage of easy control of the treatment process. Compared with the growth of nanomaterials on screw dislocations under heating conditions, the present application can effectively reduce the degree of hydrolysis of the AlN wafer at room temperature and for a short time (about 1 min).

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

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

[0032] Meanwhile, in order to avoid the influence of the pollutants attached to the surface of the crystal on the reaction efficiency and accuracy, in some specific embodiments of the present application, the crystal is subjected to cleaning treatment before being added into the reaction reagent, and in order to avoid the hydrolysis of the AlN crystal, an organic reagent is preferably used for cleaning.

[0033] In another specific embodiment of the present application, the organic solvent includes but is not limited to ethanol and acetone, so as to facilitate the cleaning of the pollutants on the surface of the AlN wafer, including organic matters, metal ions, etc.

[0034] In another specific embodiment of the present application, ultrasonic-assisted cleaning is adopted. More specifically, the ultrasonic frequency is 25-30 kHz, the ultrasonic time is 5-60 min, and the repetition number is 2-5 times. By prolonging the ultrasonic time and increasing the repetition number, a clean surface of the AlN wafer can be obtained.

[0035] Specifically, after cleaning, the inert gas (such as nitrogen) gun is used for drying. Other drying methods are avoided to introduce impurities, so as to affect the detection accuracy of the dislocation pits.

[0036] In another specific embodiment of the present application, cleaning treatment is performed before detection after the reaction treatment is completed. The cleaning treatment can be the same as the cleaning treatment method before the reaction treatment described above.

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

[0038] The present application is further explained and described by the following examples, but does not constitute a limitation on the present application. It should be understood that these examples are only used to illustrate the present application and do not limit the scope of the present application.

[0039] Example 1

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

[0041] Step 1: The AlN wafer (0.2011 g) is placed in 50 mL of ethanol and subjected to ultrasonic treatment at a frequency of 28 kHz for 15 min, and after repeating 3 times, the surface of the AlN wafer is dried by a nitrogen gun.

[0042] Step 2: The AlN wafer is placed in a glass dish, 2 mL of 1% sodium persulfate solution and 1 mL of 0.5% ferrous sulfate solution are added respectively, and after standing for 1 min, the AlN wafer is taken out.

[0043] Step 3: After repeating the operation of Step 1, the dislocation pits on the surface of the AlN wafer are detected by AFM.

[0044] Example 2

[0045] A method for rapid and accurate detection of dislocations on an aluminum nitride wafer at room temperature, comprising the following steps:

[0046] Step 1: Place the AlN wafer (0.2301 g) in 50 mL of ethanol and sonicate for 15 min at a frequency of 28 kHz, repeat 3 times, and then dry the surface of the AlN wafer with a nitrogen gun.

[0047] Step 2: Place the AlN wafer in a glass dish and 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 2 min of reaction.

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

[0049] Example 3

[0050] A method for rapid and accurate detection of dislocations on an aluminum nitride wafer at room temperature, comprising the following steps:

[0051] Step 1: Place the AlN wafer (0.2101 g) in 50 mL of ethanol and sonicate for 15 min at a frequency of 28 kHz, repeat 3 times, and then dry the surface of the AlN wafer with a nitrogen gun.

[0052] Step 2: Place the AlN wafer in a glass dish and 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 3 min of reaction.

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

[0054] Comparative Example 1

[0055] A method for detecting dislocations on an aluminum nitride wafer at high temperature corrosion, comprising the following steps:

[0056] Step 1: Place the AlN wafer (0.2121 g) in 50 mL of ethanol and sonicate for 15 min at a frequency of 28 kHz, repeat 3 times, and then 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 6 min of corrosion.

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

[0059] Figure 1 is the AFM image of the AlN wafer after reaction in Example 1, Figure 4 is the SEM image of the AlN wafer after corrosion in Comparative Example 1. It can be seen that Figure 1The dislocation pits are clear and independent, and the calculated dislocation density is 5.6*10 7 / cm 2 . Figure 4 The two dislocation pits have already intersected (in the white circle), and the calculated dislocation density is 2.0*10 6 / cm 2 . Compared with the calculated dislocation density in Example 1, it is one order of magnitude smaller, which indicates that there are still some small size dislocations that have not been presented, but continuing to extend the etching time or increasing the etching temperature will lead to more serious intersection of dislocation pits, which will also affect the accuracy of the dislocation density. Figure 2 is the AFM image of the AlN wafer after the reaction treatment in Example 2, and the independent clear dislocation pits can also be observed, and the calculated dislocation density is 3.1*10 7 / cm 2 , which is in the same order of magnitude as the result of Example 1. Figure 3 is the AFM image of the AlN wafer after the reaction treatment in Example 3, and it can be seen from the figure that some dislocation pits have already intersected and fused (in the white circle), which indicates that the reaction time of 3 min has been too long, and it is not suitable for detecting the dislocation of the AlN wafer.

[0060] Finally, it should be noted that the above only describes the preferred embodiments of the present application, and is not used to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, and for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of them. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application. Although the specific embodiments of the present application have been described above, it is not a limitation on the protection scope of the present application, and those skilled in the art should understand that various modifications or deformations made by those skilled in the art on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.

Claims

1. A method for room temperature rapid and accurate detection of dislocations in AlN wafer, characterized in that, The method comprises: adding the crystal into a reaction reagent for reaction treatment for 1-2 min, and then detecting the surface dislocation density of the reacted crystal; wherein the reaction reagent comprises a reaction agent and a promoter; the reaction agent 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; The mass concentration of the reaction agent is controlled to be 0.1-5%; The mass concentration of the promoter is controlled to be 0.01-3%; The detection of the surface dislocation density of the reacted crystal is performed by using an atomic force microscope.

2. The method of claim 1, wherein, The persulfate, perborate and percarbonate are sodium salts.

3. The method of claim 1, wherein, Before the crystal is added into the reaction reagent, organic reagent cleaning treatment is performed.

4. The method of claim 3, wherein, The organic solvent comprises ethanol and acetone.

5. The method of claim 3, wherein, The cleaning treatment is performed by using ultrasonic auxiliary cleaning.

6. The method of claim 5, wherein, The ultrasonic frequency is 25-30 kHz, the ultrasonic time is 5-60 min, and the repetition number is 2-5 times.

7. The method of claim 5, wherein, After cleaning, the inert gas gun is used for blowing dry.

8. The method of claim 1, wherein, After the reaction treatment is completed, the cleaning treatment is performed first, and then the detection is performed.

9. Application of the method according to any one of claims 1-8 in the quality control of aluminum nitride wafer.

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