CN114594119A - Method for detecting dislocation condition of gallium nitride crystal - Google Patents
Method for detecting dislocation condition of gallium nitride crystal Download PDFInfo
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- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 title claims abstract description 102
- 229910002601 GaN Inorganic materials 0.000 title claims abstract description 101
- 239000013078 crystal Substances 0.000 title claims abstract description 80
- 238000000034 method Methods 0.000 title claims abstract description 77
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 54
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 52
- 239000002253 acid Substances 0.000 claims abstract description 51
- 238000005530 etching Methods 0.000 claims abstract description 51
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 46
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 26
- 238000001514 detection method Methods 0.000 claims abstract description 14
- 238000009826 distribution Methods 0.000 claims abstract description 12
- 238000002156 mixing Methods 0.000 claims abstract description 7
- 238000004458 analytical method Methods 0.000 claims abstract description 5
- 238000004140 cleaning Methods 0.000 claims description 19
- 238000001035 drying Methods 0.000 claims description 15
- 239000000463 material Substances 0.000 abstract description 5
- 239000004065 semiconductor Substances 0.000 abstract description 4
- 239000000243 solution Substances 0.000 description 85
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 36
- 239000007788 liquid Substances 0.000 description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 18
- 238000010438 heat treatment Methods 0.000 description 15
- 239000008367 deionised water Substances 0.000 description 14
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- 230000000052 comparative effect Effects 0.000 description 12
- 239000000126 substance Substances 0.000 description 9
- 238000012360 testing method Methods 0.000 description 7
- 238000002441 X-ray diffraction Methods 0.000 description 6
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- 238000004364 calculation method Methods 0.000 description 4
- 238000012512 characterization method Methods 0.000 description 3
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- 230000000694 effects Effects 0.000 description 2
- 238000010884 ion-beam technique Methods 0.000 description 2
- UNYOJUYSNFGNDV-UHFFFAOYSA-M magnesium monohydroxide Chemical compound [Mg]O UNYOJUYSNFGNDV-UHFFFAOYSA-M 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
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Abstract
The invention relates to the technical field of semiconductor materials, in particular to a method for detecting dislocation condition of gallium nitride crystal. The method comprises the following steps: according to the formula (1.1-2.9): (0.1-1.9): 1, mixing a sulfuric acid solution, a hydrochloric acid solution and a phosphoric acid solution to prepare a mixed acid solution; immersing a gallium nitride sample in the mixed acid solution at the temperature of 250-400 ℃, etching for 5-60 min, and preparing a sample to be observed; and carrying out scanning electron microscope analysis on the surface of the sample to be observed to obtain the dislocation condition of the gallium nitride crystal. The invention can obtain the dislocation with micro-scale or nano-scale small size by etching, can directly, quickly and accurately observe the size, form, distribution, density and the like of the dislocation of the gallium nitride crystal for representation, and meets the conventional detection conditions.
Description
Technical Field
The invention relates to the technical field of semiconductor materials, in particular to a method for detecting dislocation condition of gallium nitride crystal.
Background
Gallium nitride (GaN) is a semiconductor material with a wide bandgap, has the characteristics of high critical breakdown electric field intensity, high saturated electron drift velocity, small dielectric constant, good chemical stability and the like, and can meet the requirements of next-generation electronic equipment on high power, high frequency, small volume and high-temperature work, so that the gallium nitride material becomes a research hotspot in the semiconductor industry.
Because large gallium nitride crystals are difficult to obtain, the existing gallium nitride crystals can only be epitaxially grown on heterogeneous substrates such as Si, SiC, sapphire and the like, and finally a gallium nitride epitaxial layer is obtained on the surface of the substrate. Due to the difference of lattice constants of crystals generated by heterogeneous growth, lattice mismatch is generated in the crystals, so that a large amount of dislocation exists in the surface of the gallium nitride epitaxial layer, and the performance and the application of the material are seriously influenced. Therefore, dislocation detection is carried out on the heterogrowth gallium nitride crystal, the size, the quantity and the distribution condition of dislocation in the gallium nitride crystal are represented, the quality evaluation method of gallium nitride can be perfected, and the optimization of the preparation process of gallium nitride and the improvement of product quality can be promoted.
The conventional crystal dislocation detection methods include the following methods:
one method is to cut the crystal with a focused ion beam to obtain a sample of a specific area and then observe the appearance of dislocations with a transmission electron microscope. However, the method is not suitable for conventional detection because the sample preparation process is complex, high in cost and long in period.
The other method is to obtain the XRD pattern of the crystal phase by X-ray diffraction, then to perform peak shape fitting to the diffraction pattern to obtain the positions and half-height widths of the diffraction peaks of different diffraction surfaces, then to perform pattern and multi-step fitting, and finally to calculate the dislocation density by mathematical formula. However, the dislocation in the crystal cannot be directly observed by adopting an X-ray diffraction method, and the characteristics such as the type, the form, the distribution and the like of the dislocation cannot be characterized.
And the other method is to place the gallium nitride epitaxial layer in KOH etching solution, introduce a Cd-He laser to provide laser irradiation for etching, and finally observe dislocation by adopting an atomic force microscope to realize calculation of dislocation density of the gallium nitride epitaxial layer. However, the photo-assisted wet etching technique requires a specific light source for irradiation in the test process, and has high requirements on equipment and experimental conditions, so that the photo-assisted wet etching technique is not suitable for the conventional detection of the dislocation density of the gallium nitride crystal.
And in the other method, molten KOH and MgOH mixed etching solution is adopted to etch the epitaxial layer for 2-4 min at the etching temperature of 400-600 ℃ so as to obtain the dislocation density. However, this method firstly needs to heat the solid mixed alkali to a molten state, and the actual corrosion process is not easy to control due to the high heating temperature; in addition, the method has a general effect on the corrosion of the dislocation in a small size range, and the appearance of the small dislocation is difficult to corrode.
There is also a method of counting the number of dislocations by observing spots formed by light reflected from the dislocation pits using a fluorescence microscope. However, the light spot of the small-sized dislocation is difficult to observe, the method is not suitable for detecting the small-sized dislocation, and the dislocation form cannot be observed by the method.
Disclosure of Invention
Based on the above, the invention provides a method for detecting dislocation condition of gallium nitride crystal, which avoids the disadvantages of the above method, can obtain micro-scale or nano-scale small-size dislocation by etching, can directly, rapidly and accurately observe the size, form, distribution, density and the like of dislocation of gallium nitride crystal for representation, and meets the conventional detection conditions.
The technical scheme of the invention is as follows:
a dislocation condition detection method of gallium nitride crystal comprises the following steps:
according to the formula (1.1-2.9): (0.1-1.9): 1, mixing a sulfuric acid solution, a hydrochloric acid solution and a phosphoric acid solution to prepare a mixed acid solution;
immersing a gallium nitride sample in the mixed acid solution at the temperature of 250-400 ℃, etching for 5-60 min, and preparing a sample to be observed;
and carrying out scanning electron microscope analysis on the surface of the sample to be observed to obtain the dislocation condition of the gallium nitride crystal.
In one embodiment, the volume ratio of the sulfuric acid solution to the hydrochloric acid solution to the phosphoric acid solution is (1.2-1.5): (0.5-0.8): 1.
in one embodiment, the sulfuric acid solution is 95-98% sulfuric acid aqueous solution by mass fraction.
In one embodiment, the hydrochloric acid solution is 36-38% by mass.
In one embodiment, the phosphoric acid solution is a phosphoric acid aqueous solution with a mass fraction of not less than 85%.
In one embodiment, the dislocation conditions include dislocation distribution, dislocation morphology, dislocation density, and dislocation size.
In one embodiment, the temperature of the mixed acid solution is 250-350 ℃.
In one embodiment, the etching time is 20min to 50 min.
In one embodiment, before immersing the gallium nitride sample in the mixed acid solution at the temperature of 250 ℃ to 400 ℃, the method further comprises the step of performing surface cleaning treatment on the gallium nitride crystal.
In one embodiment, the surface cleaning treatment method is to clean the gallium nitride crystal with ethanol and water in sequence and dry the gallium nitride crystal.
In one embodiment, after the etching, the method further comprises the steps of cleaning and drying.
In one embodiment, the cleaning method is to sequentially clean the etching substances by using ethanol and water.
Compared with the traditional scheme, the invention has the following beneficial effects:
dislocations are the boundaries of local slip regions in a crystal, i.e., are a type of line defect in a crystal. It is the basic factor for determining the mechanical properties of metal and other crystals, and has serious influence on other properties of the crystals (including crystal growth). According to the invention, by means of mixed acid liquid etching, gallium nitride crystals are directly etched by using the mixed acid liquid at a high temperature, and then the characteristics of micron-scale or nano-scale dislocation size, form, distribution, density and the like can be observed rapidly and accurately through a scanning electron microscope, so that the method is suitable for characterization of small-size dislocation. The observation instrument used by the invention can meet the conventional detection conditions, and has the advantages of simple steps, high test efficiency and high convenience.
Drawings
FIG. 1 is an SEM photograph of the dislocation situation of the surface of gallium nitride of example 1;
FIG. 2 is an SEM image of dislocations on the surface of gallium nitride of example 2;
FIG. 3 is a graph showing the relationship between etching time and dislocation density in example 3;
FIG. 4 is an SEM photograph of the dislocation condition of the gallium nitride surface of comparative example 1;
FIG. 5 is an SEM photograph of the dislocation condition of the gallium nitride surface of comparative example 2;
FIG. 6 is an SEM photograph showing dislocations on the surface of gallium nitride of comparative example 3;
fig. 7 is an SEM image of the dislocation condition of the gallium nitride surface of comparative example 4.
Detailed Description
The present invention will be described in further detail with reference to specific examples. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Term(s) for
Unless otherwise stated or contradicted, terms or phrases used herein have the following meanings:
as used herein, the term "and/or", "and/or" includes any one of two or more of the associated listed items, as well as any and all combinations of the associated listed items, including any two of the associated listed items, any more of the associated listed items, or all combinations of the associated listed items.
In the present invention, "one or more" means any one, any two or more of the listed items. Wherein, the 'several' means any two or more than any two.
In the present invention, the terms "combination thereof", "any combination thereof", and the like include all suitable combinations of any two or more of the listed items.
In the present invention, "optionally", "optional" and "optional" refer to the presence or absence, i.e., to any one of two juxtapositions selected from "present" and "absent". If multiple optional parts appear in one technical scheme, if no special description exists, and no contradiction or mutual constraint relation exists, each optional part is independent.
In the present invention, "preferred" is only an embodiment or an example for better description, and it should be understood that the scope of the present invention is not limited thereto.
In the present invention, the technical features described in the open type include a closed technical solution composed of the listed features, and also include an open technical solution including the listed features.
In the present invention, the numerical range is defined to include both end points of the numerical range unless otherwise specified.
In the present invention, the percentage content refers to both mass percentage for solid-liquid mixing and solid-solid phase mixing and volume percentage for liquid-liquid phase mixing, unless otherwise specified.
In the present invention, the percentage concentrations are referred to as final concentrations unless otherwise specified. The final concentration refers to the ratio of the additive component in the system to which the component is added.
In the present invention, the temperature parameter is not particularly limited, and the treatment is allowed to be performed at a constant temperature or within a certain temperature range. The constant temperature process allows the temperature to fluctuate within the accuracy of the instrument control.
The conventional crystal dislocation detection methods include the following methods:
one method is to cut the crystal with a focused ion beam to obtain a sample of a specific area and then observe the appearance of dislocations with a transmission electron microscope. However, the method has complex sample preparation process, high cost and long period. And thus is not suitable for conventional detection.
Another method is to use X-ray diffraction to obtain XRD pattern of crystal phase, then to make peak shape fitting to the diffraction pattern to obtain position and half-height width of diffraction peak of different diffraction surfaces, then to make fitting of pattern and multi-step, finally to calculate dislocation density by mathematical formula. However, the dislocation in the crystal cannot be directly observed by adopting an X-ray diffraction method, and the characteristics such as the type, the form, the distribution and the like of the dislocation cannot be characterized.
And the other method is to place the gallium nitride epitaxial layer in KOH etching solution, introduce a Cd-He laser to provide laser irradiation for etching, and finally observe dislocation by adopting an atomic force microscope to realize calculation of the dislocation density of the gallium nitride epitaxial layer. However, the photo-assisted wet etching technique requires a specific light source for irradiation in the test process, and has high requirements on equipment and experimental conditions, so that the technique is not suitable for conventional detection of dislocation density of gallium nitride crystal.
And in the other method, molten KOH and MgOH mixed etching solution is adopted to etch the epitaxial layer for 2-4 min at the etching temperature of 400-600 ℃ so as to obtain the dislocation density. However, this method firstly needs to heat the solid mixed alkali to a molten state, and the actual corrosion process is not easy to control due to the high heating temperature; in addition, the method has a general effect on the corrosion of the dislocation in a small size range, and the appearance of the small dislocation is difficult to corrode.
There is also a method of counting the number of dislocations by observing spots formed by light reflected from the dislocation pits using a fluorescence microscope. However, the light spot of the small-sized dislocation is difficult to observe, the method is not suitable for detecting the small-sized dislocation, and the dislocation form cannot be observed by the method.
The invention provides a method for detecting dislocation condition of gallium nitride crystal, which avoids the disadvantages of the method and adopts the technical scheme that:
a dislocation condition detection method of gallium nitride crystal comprises the following steps:
according to the formula (1.1-2.9): (0.1-1.9): 1, mixing a sulfuric acid solution, a hydrochloric acid solution and a phosphoric acid solution to prepare a mixed acid solution;
immersing a gallium nitride sample in the mixed acid solution at the temperature of 250-400 ℃, etching for 5-60 min, and preparing a sample to be observed;
and carrying out scanning electron microscope analysis on the surface of the sample to be observed to obtain the dislocation condition of the gallium nitride crystal.
Dislocations are the boundaries of local slip regions in a crystal, i.e., are a type of line defect in a crystal. It is the basic factor for determining the mechanical properties of metal and other crystals, and has serious influence on other properties of the crystals (including crystal growth). According to the invention, by means of mixed acid liquid etching, gallium nitride crystals are directly etched by using the mixed acid liquid at a high temperature, and then the characteristics of micron-scale or nano-scale dislocation size, form, distribution, density and the like can be observed rapidly and accurately through a scanning electron microscope, so that the method is suitable for characterization of small-size dislocation. The observation instrument used by the invention can meet the conventional detection conditions, and has the advantages of simple steps, high test efficiency and high convenience.
In the present invention, the dislocation situation includes dislocation distribution, dislocation morphology, dislocation density, and dislocation size.
In the invention, the composition of the mixed acid liquid, the temperature of the mixed acid liquid and the etching time all influence whether the outcrop (corrosion pit) of the dislocation with small size can be observed by a scanning electron microscope.
Wherein the mixed acid liquid is prepared from (1.1-2.9): (0.1-1.9): 1 sulfuric acid solution, hydrochloric acid solution and phosphoric acid solution. It is understood that the volume ratio of the sulfuric acid solution, the hydrochloric acid solution, and the phosphoric acid solution includes, but is not limited to, 1.1:1.9:1, 1.1:1.5:1, 1.1:1:1, 1.1:0.5:1, 1.1:0.1:1, 1.5:1.9:1, 1.5:1.5:1, 1.5:1:1, 1.5:0.1:1, 2:1.9:1, 2:1.5:1, 2:1:1, 2:0.5:1, 2:0.1:1, 2.5:1.9:1, 2.5:1.5:1, 2.5:1:1, 2.5:0.5:1, 2.5:0.1:1, 2.9:1.9:1, 2.9:1.5:1, 1.9: 1.1, 1.5:1.9:1, 1.1, 1.9:1, 1.1.1, 1.9: 1.1, 1.1.9: 1, 1.1, 1.1.1.9: 1, 1.1.9: 1, 1.1, 1.1.1.9: 1.1, 1, 1.1.1.9: 1, 1.1.1.1.9: 1.1, 1.9:1, 1.1.1.1.1.9: 1.1, 1.9: 1.1.1.1, 1.9:1, 1.9: 1.1.9: 1, 1.1.1, 1.1.9: 1, 1.9: 1.1.1.9: 1.9:1, 1.1.1.1.1.9: 1, 1.1.1.1, 2.9: 1.1.1.9: 1, 1.9:1, 1.1.1.9: 1.1, etc. Preferably, the volume ratio of the sulfuric acid solution to the hydrochloric acid solution to the phosphoric acid solution is (1.2-1.5): (0.5-0.8): 1. including but not limited to 1.2:0.8:1, 1.2:0.7:1, 1.2:0.6:1, 1.2:0.5:1, 1.3:0.8:1, 1.3:0.7:1, 1.3:0.6:1, 1.3:0.5:1, 1.4:0.8:1, 1.4:0.7:1, 1.4:0.6:1, 1.4:0.5:1, 1.5:0.8:1, 1.5:0.7:1, 1.5:0.6:1, 1.5:0.5: 1. More preferably, the volume ratio of the sulfuric acid solution, the hydrochloric acid solution and the phosphoric acid solution is 1.2:0.8:1 or 1.3:0.7:1 or 1.4:0.6:1 or 1.5:0.5: 1.
Compared with the single use of a sulfuric acid solution, a hydrochloric acid solution and a phosphoric acid solution, the use of the mixed acid solution can etch the small-size dislocation, and is suitable for characterization of the small-size dislocation.
Optionally, the sulfuric acid solution is a 95-98% sulfuric acid aqueous solution in mass fraction.
Optionally, the hydrochloric acid solution is a hydrochloric acid solution with a mass fraction of 36% -38%.
Optionally, the phosphoric acid solution is a phosphoric acid aqueous solution with a mass fraction of not less than 85%.
After preparing the mixed acid liquid, immersing the gallium nitride sample in the mixed acid liquid at the temperature of 250-400 ℃ and etching for 5-60 min. It can be understood that the temperature of the mixed acid solution can be raised to 250 ℃ to 400 ℃, and then the gallium nitride crystal is put into the mixed acid solution, or the gallium nitride sample can be immersed into the mixed acid solution and then the temperature is raised to 250 ℃ to 400 ℃. It is further understood that the mixed acid solution is maintained at a temperature of 250 ℃ to 400 ℃ during the etching process.
In one embodiment, the temperature of the mixed acid solution is increased to 250-400 ℃, the mixed acid solution is kept warm for 2-10 min, then the gallium nitride crystal is placed, and the gallium nitride sample is immersed in the mixed acid solution.
Preferably, the temperature of the mixed acid solution is 250-350 ℃. More preferably, the temperature of the mixed acid solution is 280-320 ℃.
Preferably, the etching time is 20min to 50 min. More preferably, the etching time is 35min to 45 min.
Optionally, before immersing the gallium nitride sample in the mixed acid solution at the temperature of 250 ℃ to 400 ℃, the method further comprises a step of performing surface cleaning treatment on the gallium nitride crystal.
In one embodiment, the surface cleaning treatment method is to clean the gallium nitride crystal with ethanol and water in sequence and dry the gallium nitride crystal. It is understood that the method of drying includes, but is not limited to, drying with a blower.
Optionally, after the etching, the method further comprises the steps of cleaning and drying.
In one embodiment, the cleaning method comprises sequentially cleaning with ethanol and water to remove the etching substances, and drying. It is understood that the method of drying includes, but is not limited to, drying with a blower.
The invention can rapidly detect the crystal dislocation in the gallium nitride epitaxial layer, accurately research the crystal dislocation appearance and distribution of the gallium nitride epitaxial layer and determine the dislocation density. The method has a great application prospect in the aspects of crystal growth quality evaluation, reliability evaluation, failure analysis and the like. In addition, the invention has the advantages of lower test cost, simple test steps, high test efficiency and higher application value.
In the following, the raw materials referred to in the following specific examples are commercially available, unless otherwise specified, the equipment used, and the processes referred to, unless otherwise specified, are all routinely selected by those skilled in the art.
Wherein the concentration of the sulfuric acid solution is 95-98%, and the sulfuric acid solution is from Guangdong reagent science and technology limited; the concentration of the hydrochloric acid solution is 36-38%, and the hydrochloric acid solution is from Guangdong reagent science and technology limited company; the concentration of the phosphoric acid solution is not less than 85 percent and is from Guangdong reagent science and technology limited in Guangdong province.
Example 1
The present embodiment provides a method for detecting dislocation of a gallium nitride crystal, which includes the following steps:
1. and cleaning the gallium nitride sample by using ethanol and deionized water in sequence, and then blowing the sample by using a blower for later use.
2. Preparing a mixed acid solution of a sulfuric acid solution, a hydrochloric acid solution and a phosphoric acid solution in a volume ratio of 1.5:0.5:1,
pouring the prepared mixed acid liquid into a beaker, placing the beaker in a constant-temperature heating stirrer, heating to 300 ℃, preserving heat for 5min, placing a gallium nitride sample into the mixed acid liquid, and etching for 20min at 300 ℃.
3. And cleaning the etched sample by sequentially adopting ethanol and deionized water, removing the etching substances, and drying to obtain the sample to be observed.
4. And observing the sample to be observed by using a Scanning Electron Microscope (SEM), and acquiring the dislocation characteristics of the gallium nitride crystal, as shown in figure 1. From fig. 1, the true morphology of gallium nitride crystals can be visually observed, knowing dislocation distribution, dislocation morphology, dislocation density, and dislocation size. In this embodiment, the dislocation pits have a size of about 200nm to 250nm, the peripheries of the dislocation pits are hexagonal, and the pits are mainly in the shape of inverted hexagonal pyramids. The dislocation density calculation was performed for the dislocations in FIG. 1, and the result was 7.97X 108Per cm2。
Example 2
The present embodiment provides a method for detecting dislocation of a gallium nitride crystal, which includes the following steps:
1. the same gallium nitride sample as in example 1 was washed with ethanol and deionized water in sequence, and then dried by a blower for further use.
2. Preparing a mixed acid solution of a sulfuric acid solution, a hydrochloric acid solution and a phosphoric acid solution in a volume ratio of 1.2:0.8: 1.
Pouring the prepared mixed acid liquid into a beaker, placing the beaker in a constant-temperature heating stirrer, heating to 400 ℃, preserving heat for 10min, placing a gallium nitride sample into the mixed acid liquid, and etching for 30min at 400 ℃.
3. And cleaning the etched sample by sequentially adopting ethanol and deionized water, removing the etching substances, and drying to obtain the sample to be observed.
4. MiningAnd observing the sample to be observed by using a Scanning Electron Microscope (SEM), and acquiring the dislocation characteristics of the gallium nitride crystal, as shown in figure 2. The dislocation density calculation was performed for the dislocations in fig. 2, and the result was 9.70 × 108Per cm2。
Example 3
The present embodiment provides a method for detecting dislocation of a gallium nitride crystal, which includes the following steps:
1. in parallel, 7 parts of the same gallium nitride sample as in example 1 was taken, washed with ethanol and deionized water in sequence, and then dried by a blower for further use.
2. 7 parts of mixed acid solution of sulfuric acid solution, hydrochloric acid solution and phosphoric acid solution in a volume ratio of 1:1:1 are parallelly configured.
And respectively pouring the prepared 7 parts of mixed acid liquor into beakers, placing the beakers in a constant-temperature heating stirrer to heat to 300 ℃, preserving the heat for 10min, respectively placing 7 parts of gallium nitride samples into the 7 parts of mixed acid liquor, and respectively etching the 7 parts of gallium nitride samples at 300 ℃ for 5min, 10min, 20min, 30min, 40min, 50min and 60 min.
3. And cleaning the etched sample by using ethanol and deionized water in sequence, removing an etching object, and drying to obtain 7 parts of sample to be observed.
4. And observing the sample to be observed by adopting a Scanning Electron Microscope (SEM), and obtaining 7 parts of dislocation characteristics of the gallium nitride crystal. The dislocation density was calculated at 7 parts from the dislocations in the SEM images.
Dislocation density of gallium nitride crystals was plotted as a function of etching time, as shown in fig. 3. As can be seen from fig. 3, the dislocation density of the gallium nitride crystal increases and then decreases with the etching time, and the possible reasons are: due to different difficulty degrees of dislocation etching of different types, the dislocation density can be increased along with the increase of etching time in the initial etching stage; and the substrate is corroded due to the overlong etching time, the appearance of the dislocation pit is gradually covered, and the dislocation density is reduced. More dislocation exposure points can be observed after 30min of etching, which indicates that the etching time is better.
Comparative example 1
The present comparative example provides a method for detecting dislocation of gallium nitride crystal, which is different from example 1 mainly in that: the method uses mixed acid liquid with different volume ratios of the components and comprises the following steps:
1. the same gallium nitride sample as in example 1 was washed with ethanol and deionized water in sequence, and then dried by a blower for further use.
2. Preparing a mixed acid solution of a sulfuric acid solution, a hydrochloric acid solution and a phosphoric acid solution in a volume ratio of 0.5:0.5: 2.
Pouring the prepared mixed acid liquid into a beaker, placing the beaker in a constant-temperature heating stirrer, heating to 300 ℃, preserving heat for 5min, placing a gallium nitride sample into the mixed acid liquid, and etching for 20min at 300 ℃.
3. And cleaning the etched sample by sequentially adopting ethanol and deionized water, removing the etching substances, and drying to obtain the sample to be observed.
4. And observing the sample to be observed by using a Scanning Electron Microscope (SEM), and acquiring the dislocation characteristics of the gallium nitride crystal, as shown in FIG. 4. As can be seen from fig. 4, the dislocations appear as small dots with a circular shape, and the morphology of the gallium nitride dislocations cannot be accurately fed back.
Comparative example 2
The present comparative example provides a method for detecting dislocation of gallium nitride crystal, which is mainly different from example 1 in that: the method uses mixed acid liquid with different volume ratios of the components and comprises the following steps:
1. the same gallium nitride sample as in example 1 was washed with ethanol and deionized water in sequence, and then dried by a blower for further use.
2. Preparing a mixed acid solution of a sulfuric acid solution, a hydrochloric acid solution and a phosphoric acid solution in a volume ratio of 1:1: 2.
Pouring the prepared mixed acid liquid into a beaker, placing the beaker in a constant-temperature heating stirrer, heating to 300 ℃, preserving heat for 5min, placing a gallium nitride sample into the mixed acid liquid, and etching for 20min at 300 ℃.
3. And cleaning the etched sample by sequentially adopting ethanol and deionized water, removing the etching substances, and drying to obtain the sample to be observed.
4. And observing the sample to be observed by using a Scanning Electron Microscope (SEM), and acquiring the dislocation characteristics of the gallium nitride crystal, as shown in FIG. 5. It can be seen from fig. 5 that the dislocations are in the form of small dots, and the number of dislocations is small.
Comparative example 3
The present comparative example provides a method for detecting dislocation of gallium nitride crystal, which is mainly different from example 1 in that: phosphoric acid is used to replace the mixed acid solution, and the steps are as follows:
1. the same gallium nitride sample as in example 1 was washed with ethanol and deionized water in sequence, and then dried by a blower for further use.
2. And pouring the phosphoric acid solution into a beaker, putting the beaker into a constant-temperature heating stirrer, heating to 300 ℃, preserving heat for 5min, putting a gallium nitride sample into the phosphoric acid solution, and etching for 20min at 300 ℃.
3. And cleaning the etched sample by sequentially adopting ethanol and deionized water, removing the etching substances, and drying to obtain the sample to be observed.
4. And observing the sample to be observed by using a Scanning Electron Microscope (SEM), and acquiring the dislocation characteristics of the gallium nitride crystal, as shown in FIG. 6. No significant dislocation morphology was observed from fig. 6.
Comparative example 4
The present comparative example provides a method for detecting dislocation of gallium nitride crystal, which is mainly different from example 1 in that: sulfuric acid is used to replace the mixed acid solution, and the method comprises the following steps:
1. the same gallium nitride sample as in example 1 was washed with ethanol and deionized water in sequence, and then dried by a blower for further use.
2. Pouring the sulfuric acid solution into a beaker, placing the beaker in a constant-temperature heating stirrer, heating the beaker to 300 ℃, preserving heat for 5min, placing a gallium nitride sample into the sulfuric acid solution, and etching the sample at 300 ℃ for 20 min.
3. And cleaning the etched sample by sequentially adopting ethanol and deionized water, removing the etching substances, and drying to obtain the sample to be observed.
4. And observing the sample to be observed by using a Scanning Electron Microscope (SEM), and acquiring the dislocation characteristics of the gallium nitride crystal, as shown in FIG. 7. No significant dislocation morphology was observed from fig. 7.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A dislocation condition detection method of a gallium nitride crystal is characterized by comprising the following steps:
according to the formula (1.1-2.9): (0.1-1.9): 1, mixing a sulfuric acid solution, a hydrochloric acid solution and a phosphoric acid solution to prepare a mixed acid solution;
immersing a gallium nitride sample in the mixed acid solution at the temperature of 250-400 ℃, etching for 5-60 min, and preparing a sample to be observed;
and carrying out scanning electron microscope analysis on the surface of the sample to be observed to obtain the dislocation condition of the gallium nitride crystal.
2. The method for detecting dislocation of gallium nitride epitaxial layer according to claim 1, wherein the volume ratio of the sulfuric acid solution, the hydrochloric acid solution and the phosphoric acid solution is (1.2-1.5): (0.5-0.8): 1.
3. a method for detecting dislocation of gallium nitride crystal according to claim 1, wherein the sulfuric acid solution is 95-98% by mass aqueous sulfuric acid solution.
4. The method for detecting dislocation of a gallium nitride crystal according to claim 1, wherein the hydrochloric acid solution is a 36% to 38% aqueous hydrochloric acid solution by mass fraction.
5. A dislocation situation of a gallium nitride crystal according to claim 1, wherein said phosphoric acid solution is an aqueous phosphoric acid solution with a mass fraction of not less than 85%.
6. A method for detecting a dislocation situation in a gallium nitride crystal according to any one of claims 1 to 5, wherein the dislocation situation includes dislocation distribution, dislocation morphology, dislocation density and dislocation size.
7. A method for detecting a dislocation situation in a gallium nitride crystal according to any one of claims 1 to 5, wherein the temperature of the mixed acid solution is 250 to 350 ℃.
8. A method for detecting dislocation of gallium nitride crystal according to any of claims 1-5, wherein the etching time is 20-50 min.
9. A method for detecting dislocation of gallium nitride crystal according to any one of claims 1 to 5, wherein said method further comprises the step of subjecting said gallium nitride crystal to surface cleaning treatment before immersing said gallium nitride sample in said mixed acid solution at a temperature of 250 ℃ to 400 ℃.
10. A method for detecting dislocation of gallium nitride crystal according to any of claims 1-5, further comprising the steps of cleaning and drying after said etching.
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| JP2009008500A (en) * | 2007-06-27 | 2009-01-15 | Mitsubishi Chemicals Corp | Method for evaluating dislocation of crystal, method for evaluating crystal growth method, and crystal growth method |
| CN104502351A (en) * | 2014-10-16 | 2015-04-08 | 广东德豪润达电气股份有限公司 | GaN-based epitaxial material dislocation defect determination method |
| CN112067402A (en) * | 2020-09-23 | 2020-12-11 | 广东省科学院半导体研究所 | Dislocation defect analysis method |
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| JP2009008500A (en) * | 2007-06-27 | 2009-01-15 | Mitsubishi Chemicals Corp | Method for evaluating dislocation of crystal, method for evaluating crystal growth method, and crystal growth method |
| CN104502351A (en) * | 2014-10-16 | 2015-04-08 | 广东德豪润达电气股份有限公司 | GaN-based epitaxial material dislocation defect determination method |
| CN112067402A (en) * | 2020-09-23 | 2020-12-11 | 广东省科学院半导体研究所 | Dislocation defect analysis method |
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