CN115637499A - Gallium nitride semiconductor material and chemical etching method thereof - Google Patents
Gallium nitride semiconductor material and chemical etching method thereof Download PDFInfo
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- CN115637499A CN115637499A CN202211286389.1A CN202211286389A CN115637499A CN 115637499 A CN115637499 A CN 115637499A CN 202211286389 A CN202211286389 A CN 202211286389A CN 115637499 A CN115637499 A CN 115637499A
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Abstract
The invention discloses a gallium nitride semiconductor material and a chemical etching method thereof, comprising the following steps: carrying out ICP-RIE etching on the gallium nitride material; (2) Adding 0.01wt% of polyethylene glycol octyl phenyl ether into 2wt% -30wt% of tetramethyl ammonium hydroxide solution to prepare etching solution; (3) Placing the gallium nitride material etched by ICP-RIE into etching liquid, heating to 30-100 ℃ for chemical etching, wherein the heating time is 30min; (4) Adopting ultraviolet light at 30mW/cm while carrying out chemical etching 2 Irradiating the gallium nitride material and the etching solution by light intensity to increase the etching speed; (5) And taking out the gallium nitride material, washing with pure water and spin-drying. The invention has the beneficial effect that the side wall which is completely superposed with the m surface can be obtained by combining ICP-RIE etching and tetramethylammonium hydroxide chemical etching.
Description
Technical Field
The invention relates to a gallium nitride material growth technology, in particular to a chemical etching method of a gallium nitride semiconductor material.
Background
Gallium nitride (GaN) is a typical representative of wide-bandgap semiconductor materials, has a wide energy gap (not less than 3.4 eV), a high saturated electron drift rate, a large breakdown voltage, a small dielectric constant, and a good thermal conductivity, and has advantages that first-generation and second-generation semiconductor materials do not have, thereby becoming a research front in rapid development. The gallium nitride material has the characteristics of more stable chemical property, high temperature resistance and corrosion resistance, and is very suitable for manufacturing electronic devices with radiation resistance, high frequency, high power and high density integration. In addition, since gallium nitride is a direct band semiconductor, it has also found wide applications in the field of optoelectronics, such as light emitting diodes and semiconductor lasers.
The etching method for the gallium nitride material comprises dry etching and wet etching. Due to the stable chemical property of gallium nitride, the general wet etching solution cannot be well applied to the industrial processing of gallium nitride materials. The industrial preparation of the gallium nitride-based device at the early stage mainly depends on a physical dry etching technology, but the dry etching technology has higher equipment cost, needs to use toxic gas, and inevitably damages a processing surface by using high-energy etching to influence the final performance of the device. In order to reduce the cost and the operation complexity, the industry is moving to an improved wet etching method for etching gallium nitride material.
The chemical stability of gallium nitride also presents a particular challenge to wet etching, and it is crucial to find an etchant that is sufficiently safe, inexpensive, and environmentally friendly.
For example, chinese patent publication No. CN104716198B discloses a thin film transistor, a method for manufacturing the same, and a display device, wherein the etching solution (i.e., an electrolyte solution in which the two materials undergo a battery reaction) is an alkaline solution, such as a sodium hydroxide solution, a potassium hydroxide solution, or a tetramethylammonium hydroxide solution.
Chinese patent publication No. CN115036220A discloses a gallium nitride electronic device and a method for manufacturing the same, wherein an etching solution used in the wet etching method includes any one or a combination of two or more of tetramethylammonium hydroxide (TMAH), a potassium hydroxide solution, and a sodium hydroxide solution.
In the preparation process of the gallium nitride power device, it is important to obtain a smooth nonpolar side wall, and the side wall obtained by etching by using dry ICP-RIE is not vertical enough and cannot be completely along the direction of an m surface.
Disclosure of Invention
The invention provides a chemical etching method for a gallium nitride semiconductor material, aiming at solving the technical problem that the side wall of the existing gallium nitride device is not vertical enough.
The technical scheme of the invention is as follows: a chemical etching method of gallium nitride semiconductor material,the method comprises the following steps: carrying out ICP-RIE etching on the gallium nitride material; (2) Adding 0.01wt% of polyethylene glycol octyl phenyl ether into 2wt% -30wt% of tetramethyl ammonium hydroxide solution to prepare etching solution; (3) Placing the gallium nitride material etched by ICP-RIE into etching liquid, heating to 30-100 ℃ for chemical etching, wherein the heating time is 30min; (4) Adopting ultraviolet light at 30mW/cm while carrying out chemical etching 2 The gallium nitride material and the etching liquid are irradiated by light intensity, so that the etching speed is increased; (5) And taking out the gallium nitride material, washing with pure water and drying by spinning.
The improvement of the scheme is that the surface of the gallium nitride material is cleaned by using a cleaning solution before the step (1).
In the scheme, the cleaning liquid is any one of deionized water, alcohol, isopropanol, acetone, concentrated sulfuric acid + hydrogen peroxide + water, ammonia water + hydrogen peroxide + water, hydrochloric acid + hydrogen peroxide + water, hydrofluoric acid + ammonium fluoride, citric acid + hydrogen peroxide + water and nitric acid.
In the scheme, the etching solution further comprises 5wt% -30wt% of isopropanol.
In the above scheme, the etching solution further comprises sodium dodecyl sulfate.
The gallium nitride material is prepared by the scheme.
The method has the beneficial effects that the etching speed of tetramethyl ammonium hydroxide on the N surface, the a surface and the m surface of the gallium nitride substrate is different, and the etched surface is in a hexahedral pyramid structure. The appearance is beneficial to the uniform absorption of infrared light in the epitaxial process, and the temperature uniformity of the substrate is improved; by combining ICP-RIE etching and tetramethylammonium hydroxide chemical etching, a sidewall that is completely coincident with the m-plane can be obtained.
Drawings
FIG. 1 is an SEM photograph of an etched N-side of a gallium nitride substrate of the present invention;
FIG. 2 is an optical microscope photograph of the etched N-side of the gallium nitride substrate of the present invention;
FIG. 3 is a SEM photograph of gallium nitride after etching using ICP-RIE;
fig. 4 is a SEM photograph of gallium nitride obtained using the method of the present invention.
Detailed Description
The technical scheme in the embodiment of the invention is clearly and completely described below with reference to the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments based on the embodiments in the present invention, without any inventive work, will be apparent to those skilled in the art from the following description.
A chemical etching liquid for gallium nitride semiconductor material comprises: 2 to 30 weight percent of Tetramethylammonium hydroxide (TMAH), the solvent is water, and the pH value of the etching solution is alkaline. Preferably, 5 to 30wt% of isopropyl alcohol (IPA) and a small amount of ionic or nonionic surfactant such as Sodium Dodecyl Sulfate (SDS), polyethylene glycol octylbenzene and ether (Triton X-100) may be added to the etching solution, and the content of the polyethylene glycol octylbenzene and ether (Triton X-100) is approximately equivalent to the content of Sodium Dodecyl Sulfate (SDS).
The invention also discloses a processing method for etching the gallium nitride material, which comprises the following steps: (1) And cleaning the gallium nitride material to be etched to remove pollutants on the surface so as to avoid influencing the etching uniformity. The cleaning solution can be selected according to the surface pollution condition, such as any one or more of deionized water, alcohol, isopropanol, acetone, concentrated sulfuric acid + hydrogen peroxide + water, ammonia water + hydrogen peroxide + water, hydrochloric acid + hydrogen peroxide + water, hydrofluoric acid + ammonium fluoride, citric acid + hydrogen peroxide + water, nitric acid, and the like. (2) And immersing the cleaned gallium nitride material into the chemical etching liquid, heating the whole chemical etching liquid at the temperature of between 30 and 100 ℃, and selecting the heating temperature according to the required etching speed. (3) And optionally utilizing Photoelectrochemical (PEC) etching, namely irradiating the etching sample and the etching solution with ultraviolet light while etching to increase the etching speed.
The etching of the gallium nitride material is carried out by adopting a tetramethyl ammonium hydroxide solution, and the anisotropy of the tetramethyl ammonium hydroxide solution to the etching speed of different crystal faces of the gallium nitride material is mainly utilized. I.e. the etch rate is different for different crystallographic planes.
Example one:
in the application of the gallium nitride material as the substrate of the blue-green laser, wet etching needs to be performed on the back (N surface) of the gallium nitride substrate to remove a surface damage layer formed in a processing engineering, and the uniformity of temperature in an epitaxial process is favorably controlled.
The preparation and use method comprises the following steps:
(1) And cleaning the surface of the sample to be processed to remove pollutants on the surface so as to avoid influencing the etching uniformity. And one or more of the cleaning solutions are adopted as the cleaning solution according to the surface cleaning condition of the sample to be processed.
(2) Preparing a chemical etching liquid:
to a 25wt% tetramethylammonium hydroxide solution, 10wt% IPA and 0.01wt% Triton X-100 were added.
(3) And immersing the cleaned gallium nitride material into the chemical etching liquid, heating the chemical etching liquid to 80 ℃, and keeping the temperature for 60min.
(4) Adopting ultraviolet light at 30mW/cm while etching 2 The light intensity irradiates the etching sample and the etching liquid to increase the etching speed.
(5) And after 60min, taking out the sample, washing with pure water and drying by spinning.
As shown in fig. 1-2, because the etching speed of tetramethylammonium hydroxide on the N-plane, the a-plane and the m-plane of the gallium nitride substrate is different, and the etching speed on the m-plane is the slowest, the m-plane will be exposed as the etching proceeds, and the etched surface has a hexahedral pyramid-like structure. The shape is beneficial to the uniform absorption of infrared light in the epitaxial process, and the temperature uniformity of the substrate is improved.
In the second embodiment, it is important to obtain smooth non-polar sidewalls in the process of manufacturing the gan power device, and the sidewalls obtained by dry ICP-RIE etching are not sufficiently vertical and cannot be completely along the direction of the m-plane. And etching the sample subjected to the ICP-RIE etching processing again by using the etching solution to obtain the side wall which is completely overlapped with the m surface.
The preparation and use method comprises the following steps: (1) And cleaning the surface of the sample to be processed to remove pollutants on the surface so as to avoid influencing the etching uniformity. Depending on the surface cleaning of the sample to be processed, one or more of the aforementioned cleaning solutions may be used, but a step involving cleaning with a dilute hydrochloric acid solution is required.
(2) Preparing a chemical etching liquid:
0.01wt% Triton X-100 was added to 25wt% tetramethylammonium hydroxide solution.
(3) And immersing the cleaned gallium nitride material into the chemical etching liquid, heating the chemical etching liquid to 80 ℃, and keeping the temperature for 30min.
(4) Adopting ultraviolet light at 30mW/cm while etching 2 The light intensity irradiates the etching sample and the etching liquid to increase the etching speed.
(5) After 30min, the sample was taken out, rinsed with pure water and spun-dried.
The third embodiment is different from the second embodiment in that the chemical etching solution is heated to 30 ℃ in the step (3);
example four: the difference from the second embodiment is that in the step (3), the chemical etching solution is heated to 100 ℃;
example five: the difference from example two is that in step (2), 0.01wt% Triton X-100 was added to a 30wt% tetramethylammonium hydroxide solution.
Example six: the difference from example two is that in step (2), 0.01wt% Triton X-100 was added to a 2wt% tetramethylammonium hydroxide solution.
As shown in FIG. 3, the SEM pictures of the samples etched by ICP-RIE and not etched by the etching solution show that the side wall inclination is larger, as shown in FIG. 4, after the treatment method of the invention, namely, after the samples are etched by ICP-RIE and then etched by the etching solution, the verticality of the side wall is obviously improved.
Claims (6)
1. A chemical etching method of gallium nitride semiconductor material is characterized in that: bag (bag)The method comprises the following steps: carrying out ICP-RIE etching on the gallium nitride material; (2) Adding 0.01wt% of polyethylene glycol octyl phenyl ether into 2wt% -30wt% of tetramethyl ammonium hydroxide solution to prepare etching solution; (3) Placing the gallium nitride material etched by ICP-RIE into etching liquid, heating to 30-100 ℃ for chemical etching, wherein the heating time is 30min; (4) Adopting ultraviolet light at 30mW/cm while carrying out chemical etching 2 Irradiating the gallium nitride material and the etching solution by light intensity to increase the etching speed; (5) And taking out the gallium nitride material, washing with pure water and spin-drying.
2. A chemical etching method for gallium nitride semiconductor material according to claim 1, wherein: and (2) cleaning the surface of the gallium nitride material by using a cleaning solution before the step (1).
3. A chemical etching method for gallium nitride semiconductor material according to claim 2, wherein: the cleaning liquid is any one of deionized water, alcohol, isopropanol, acetone, concentrated sulfuric acid, hydrogen peroxide and water, ammonia water, hydrogen peroxide and water, hydrochloric acid, hydrogen peroxide and water, hydrofluoric acid and ammonium fluoride, citric water, hydrogen peroxide and water and nitric acid.
4. A chemical etching method for gallium nitride semiconductor material according to claim 1, wherein: the etching liquid also comprises 5wt% -30wt% of isopropanol.
5. A chemical etching method for gallium nitride semiconductor material according to claim 1 or 4, wherein: the etching liquid also comprises sodium dodecyl sulfate.
6. Gallium nitride semiconductor material, characterized by: prepared by the chemical etching method of gallium nitride semiconductor material according to any one of claims 1-5.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211286389.1A CN115637499A (en) | 2022-10-20 | 2022-10-20 | Gallium nitride semiconductor material and chemical etching method thereof |
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| CN202211286389.1A CN115637499A (en) | 2022-10-20 | 2022-10-20 | Gallium nitride semiconductor material and chemical etching method thereof |
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