Acid polishing solution and application thereof in indium antimonide surface polishing

Abstract

The invention belongs to the technical field of chemical machinery, and discloses an acidic polishing solution and application thereof in indium antimonide surface polishing. The acidic polishing solution comprises 5 to 15 wt% of acidic silica sol, 0.1 to 2 wt% of an oxidant, 0.01 to 1 wt% of a polishing accelerator, 0.01 to 1 wt% of a surfactant and the balance of water. The preparation method of the acidic silica sol comprises the step of exchanging alkaline silica sol through cation exchange resin to obtain the acidic silica sol. The polishing solution provided by the invention is suitable for InSb surface polishing, the indium antimonide surface polished by the polishing solution is good in state and free of surface defects such as scratches and pits, and the surface roughness Ra measured by AFM can reach about 1 nanometer or below; meanwhile, the polishing solution has the characteristics of high polishing removal rate, stable polishing performance, greenness, environmental protection and no pollution, and the polishing removal rate can reach more than 0.2 micron / minute.

Description

Technical Field

[0001] The invention relates to the technical field of chemical mechanical polishing, in particular to an acid polishing liquid and application thereof in polishing the surface of indium antimonide. Background Art

[0002] With the continuous progress of the information society, the interaction of technologies has become closer. Almost every modern project cannot do without various sensors. Sensors have long been infiltrated into extremely wide fields such as industrial production, space development, ocean exploration, environmental protection, resource investigation, medical diagnosis, bioengineering, and even cultural relics protection. The sensitive materials and sensitive film preparation technologies that play a decisive role in sensors have attracted more and more attention. Indium antimonide (InSb) is widely used in optoelectronic components, magnetoresistive components, Hall elements, and transistor structure devices because of its special properties such as extremely high electron mobility and extremely small electron mass. These components are used in military and civilian fields such as astronomical observation, guidance, and gas detection. Indium antimonide is still the most widely used medium-wave infrared detection material.

[0003] Because InSb material is relatively soft, scratches, roughness and flatness on the surface will greatly affect the performance of InSb devices. Therefore, InSb wafers usually use chemical mechanical polishing (CMP) process to remove surface damage through a combination of chemical and mechanical grinding to achieve surface flatness. The CMP polishing process of InSb material is usually divided into three steps: rough polishing, medium polishing and fine polishing: rough polishing usually uses diamond polishing liquid, which has a fast removal rate and can quickly thin the wafer; the removal rate of medium polishing is lower than that of rough polishing, repairing most of the scratches caused by rough grinding and flattening the surface; the removal rate of the fine polishing process is very low, which will completely repair the unrepaired and newly generated scratches in rough polishing, and further optimize the surface quality of the polished wafer. Compared with other semiconductor materials such as silicon, InSb is soft and brittle, with a Mohs hardness of only about 4, and its surface properties are active and easily oxidized. The surface quality after polishing is difficult to control, so this material is difficult to process.

[0004] At present, there are relatively few studies on the polishing of InSb in China, and most of them focus on the optimization of the polishing process. Although the negative pressure vortex stirring method (patent: CN102020923A) and the two-step polishing method of laser polishing + chemical mechanical polishing (patent: CN112216602A) can obtain InSb wafers with good surface, the equipment used is complex; the three-step method of rough, medium and fine polishing (patent: CN114800058A) has complex steps and long cycles; the two-step rough and fine polishing usually uses aluminum oxide or cerium oxide system for rough polishing, and the removal rate is much lower than that of the diamond system, and the surface after polishing is much worse than the medium polishing surface, and the subsequent fine polishing takes a long time, which is not suitable for mass production in industrial manufacturing.

[0005] Since the currently commonly used InSb wafer polishing process is complicated, the polishing effect of the polishing liquid is not ideal and it takes a lot of time, we urgently need to develop a silica sol polishing liquid with high removal rate and good surface quality to meet the higher demands of the next generation of electronic device manufacturing. Summary of the invention

[0006] The purpose of the present invention is to provide an acidic polishing liquid and its application in the surface polishing of indium antimonide, so as to solve the problem that the removal rate and surface quality of the existing InSb wafers are difficult to balance during the polishing process and cannot be applied to large-scale industrial manufacturing.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides an acidic polishing liquid, comprising the following raw materials in percentage by mass:

[0009] Acidic silica sol or alkaline silica sol 5-15wt%,

[0010] Oxidant 0.1~2wt%,

[0011] Polishing accelerator 0.01~1wt%

[0012] Surfactant 0.01~1wt%

[0013] Water balance;

[0014] The method for preparing the acidic silica sol comprises the following steps:

[0015] The alkaline silica sol is exchanged with a cation exchange resin to obtain an acidic silica sol.

[0016] Preferably, in the above-mentioned acidic polishing liquid, the oxidant is hydrogen peroxide.

[0017] Preferably, in the above-mentioned acidic polishing liquid, the polishing accelerator is an acidic compound.

[0018] Preferably, in the above-mentioned acidic polishing liquid, the acidic compound is one or more of nitric acid, phosphoric acid, sulfuric acid, citric acid, oxalic acid, ethylenediaminetetraacetic acid, oxalic acid, succinic acid, malonic acid, tartaric acid, benzoic acid, and 2-hydroxysuccinic acid.

[0019] Preferably, in the above-mentioned acidic polishing liquid, the surfactant is a phosphate or phosphonate compound.

[0020] Preferably, in the above-mentioned acidic polishing liquid, the phosphate or phosphonate compound is one or more of potassium phosphate, dipotassium hydrogen phosphate, potassium methyl phosphate, potassium tripolyphosphate, potassium dihydrogen phosphate, ethyl methanol phosphate, diethyl phosphate, triethyl phosphate, fatty alcohol polyoxyethylene ether phosphate, and alkylphenol polyoxyethylene ether phosphate.

[0021] Preferably, in the above-mentioned acidic polishing liquid, the number of exchanges is 3 times.

[0022] The invention also provides application of an acidic polishing liquid in polishing the surface of indium antimonide.

[0023] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention provides an acidic polishing liquid, which comprises acidic silica sol, an oxidant, a polishing accelerator, a surfactant and water, wherein the acidic silica sol is obtained by exchanging alkaline silica sol with a cation exchange resin, the pH of the acidic silica sol is about 4, the Zeta point is -8 to -12, the average particle size of the acidic silica sol is 70 to 120 nm, and it can be stably stored at room temperature for one year, the oxidant is hydrogen peroxide, the polishing accelerator is an acid compound, the surfactant is a phosphate or phosphate ester compound, and the acidic silica sol is a soft abrasive, and the surface is not easy to cause scratches during polishing. The surfactant can improve dispersibility and stability. The oxidant can cause an oxidation reaction in the material during processing, so as to achieve a more efficient improvement of the surface quality and provide a good polishing environment. The surface roughness of indium antimonide treated with the polishing liquid can be effectively improved.

[0025] The polishing liquid provided by the present invention is mainly suitable for polishing the surface of InSb in the manufacture of infrared detectors, sensors and optoelectronic devices. The surface state of indium antimonide after polishing is good, without surface defects such as scratches and pits, and the surface roughness Ra measured by AFM can reach less than about 1 nanometer; at the same time, it has the characteristics of high polishing removal rate, stable polishing performance, green environmental protection and no pollution, and the polishing removal rate can reach more than 0.2 micrometers / minute. DETAILED DESCRIPTION

[0026] The present invention provides an acidic polishing liquid, comprising the following raw materials in percentage by mass:

[0027] Acidic silica sol or alkaline silica sol 5-15wt%,

[0028] Oxidant 0.1~2wt%,

[0029] Polishing accelerator 0.01~1wt%

[0030] Surfactant 0.01~1wt%

[0031] Water balance.

[0032] In the present invention, the mass percentage of the acidic silica sol is preferably 5 to 15 wt %, more preferably 7 to 12 wt %, and even more preferably 9 to 11 wt %.

[0033] In the present invention, the mass percentage of the oxidant is preferably 0.1 to 2 wt %, more preferably 0.5 to 1.5 wt %, and even more preferably 0.8 to 1 wt %.

[0034] In the present invention, the mass percentage of the polishing accelerator is preferably 0.01 to 1 wt %, more preferably 0.1 to 0.8 wt %, and more preferably 0.5 to 0.7 wt %.

[0035] In the present invention, the mass percentage of the surfactant is preferably 0.01 to 1 wt %, more preferably 0.1 to 0.8 wt %, and even more preferably 0.5 to 0.7 wt %.

[0036] In the present invention, the method for preparing the acidic silica sol comprises the following steps:

[0037] The alkaline silica sol is exchanged with a cation exchange resin to obtain an acidic silica sol.

[0038] In the present invention, the number of exchanges is preferably 3 times.

[0039] In the present invention, after the exchange is completed, the process further comprises: filtering the obtained product through a 1 μm filter element to obtain an acidic silica sol.

[0040] In the present invention, the oxidant is preferably hydrogen peroxide.

[0041] In the present invention, the polishing accelerator is preferably an acidic compound.

[0042] In the present invention, the acidic compound is preferably one or more of nitric acid, phosphoric acid, sulfuric acid, citric acid, oxalic acid, ethylenediaminetetraacetic acid, oxalic acid, succinic acid, malonic acid, tartaric acid, benzoic acid, and 2-hydroxysuccinic acid.

[0043] In the present invention, the surfactant is preferably a phosphate or phosphonate compound.

[0044] In the present invention, the phosphate or phosphonate compound is one or more of potassium phosphate, dipotassium hydrogen phosphate, potassium methyl phosphate, potassium tripolyphosphate, potassium dihydrogen phosphate, ethyl methanol phosphate, diethyl phosphate, triethyl phosphate, fatty alcohol polyoxyethylene ether phosphate, and alkylphenol polyoxyethylene ether phosphate.

[0045] The present invention also provides a method for preparing an acidic polishing liquid, comprising the following steps:

[0046] The acidic silica sol, the oxidant, the polishing accelerator, the surfactant and water are physically mixed.

[0047] The invention also provides application of an acidic polishing liquid in polishing the surface of indium antimonide.

[0048] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] The alkaline silica sol described in the following examples and comparative examples was purchased from Fuso NS-104.

[0050] The preparation method of the acidic silica sol in the following embodiment comprises the following steps:

[0051] The alkaline silica sol was exchanged three times with a cation exchange resin and then filtered through a 1 μm filter element to obtain an acidic silica sol.

[0052] The detailed raw material ratios of the acidic polishing liquids in Examples 1 to 8 and the polishing liquids in Comparative Examples 1 to 2 are shown in Table 1.

[0053] Table 1 Detailed proportions of raw materials for the preparation of acidic polishing liquids in Examples 1 to 8

[0054]

[0055]

[0056] The acidic polishing solutions of Examples 1 to 8 and the polishing solutions of Comparative Examples 1 to 2 were respectively used for polishing indium antimonide, and the polishing conditions were as follows:

[0057] Polishing machine: Shenyang Kejing 1200S single-sided polishing machine;

[0058] Polished wafer: 2-inch indium antimonide wafer;

[0059] Polishing pad: black damping pad;

[0060] Polishing pressure: 100 g / cm2;

[0061] Workpiece speed: 40 rpm;

[0062] Lower plate speed: 50 rpm;

[0063] Polishing liquid flow rate: 10 ml / min

[0064] Polishing time: 20 minutes

[0065] After polishing, the indium antimonide surface was washed and dried, and then the removal rate and surface quality of the thick film were measured. The weight difference of the wafer before and after polishing was measured with a high-precision electronic balance, and the weight was converted into the ratio of the removed thickness to the polishing time to calculate the removal rate; the surface roughness Ra was measured using an atomic force microscope (AFM).

[0066] The removal rate and surface roughness of indium antimonide after polishing with the acidic polishing solutions in Examples 1 to 8 and the polishing solutions in Comparative Examples 1 to 2 are shown in Table 2.

[0067] Table 2 Removal rate and surface roughness of indium antimonide after polishing with the acidic polishing liquids of Examples 1 to 8 and the polishing liquids of Comparative Examples 1 to 2

[0068]

[0069]

[0070] It can be seen from Table 2 that, compared with the polishing liquids of Comparative Examples 1 to 2, the acidic polishing liquids of Examples 1 to 8 have a much higher removal rate of indium antimonide by the acidic polishing liquids made from acidic silica sol than by the polishing liquids made from alkaline silica sol, and the polishing removal rate can reach more than 0.2 μm / min. The surface of indium antimonide polished with the acidic silica sol polishing liquid is ultra-smooth without surface defects such as scratches and pits, and the surface roughness Ra measured by AFM can reach about 0.8 nanometers.

[0071] In summary, the use of the polishing liquid of the present invention for ultra-fine surface polishing of indium antimonide has the characteristics of high removal rate and no surface damage; the polished surface is ultra-smooth, without defects such as scratches and pits, and the surface roughness Ra can reach about 0.8 nanometers, which can be used for the manufacture of infrared detectors and optoelectronic devices.

[0072] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An acidic polishing liquid, characterized in that: The preparation material comprises the following mass percentages: Acidic silica sol or alkaline silica sol 5-15wt%, Oxidant 0.1~2wt%, Polishing accelerator 0.01~1wt% Surfactant 0.01~1wt% Water balance; The method for preparing the acidic silica sol comprises the following steps: The alkaline silica sol is exchanged with a cation exchange resin to obtain an acidic silica sol.

2. The acidic polishing liquid according to claim 1, characterized in that The oxidant is hydrogen peroxide.

3. The acidic polishing liquid according to claim 2, characterized in that The polishing accelerator is an acidic compound.

4. The acidic polishing liquid according to claim 3, characterized in that The acidic compound is one or more of nitric acid, phosphoric acid, sulfuric acid, citric acid, oxalic acid, ethylenediaminetetraacetic acid, oxalic acid, succinic acid, malonic acid, tartaric acid, benzoic acid, and 2-hydroxysuccinic acid.

5. The acidic polishing liquid according to claim 3 or 4, characterized in that: The surfactant is a phosphate or phosphonate compound.

6. The acidic polishing liquid according to claim 5, characterized in that The phosphate or phosphonate compound is one or more of potassium phosphate, dipotassium hydrogen phosphate, potassium methyl phosphate, potassium tripolyphosphate, potassium dihydrogen phosphate, ethyl methanol phosphate, diethyl phosphate, triethyl phosphate, fatty alcohol polyoxyethylene ether phosphate, and alkylphenol polyoxyethylene ether phosphate.

7. The acidic polishing liquid according to claim 6, characterized in that The number of exchanges is 3 times.

8. Use of the acidic polishing liquid according to any one of claims 1 to 7 in polishing the surface of indium antimonide.

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