Semiconductor silicon wafer etching liquid, preparation method and application thereof

Abstract

The present invention provides a semiconductor silicon wafer etching solution, a preparation method and application thereof. The semiconductor silicon wafer etching solution of the present invention comprises the following components in weight proportion: 1-6 parts of inorganic acid; 7-20 parts of ammonium salt; 30-40 parts of organic acid; 30-60 parts of ultrapure water. The preparation method of the semiconductor silicon wafer etching solution of the present invention comprises the following steps: weighing each component according to the weight proportion; first adding ultrapure water into a container, and then adding other components into the container, stabilizing the temperature of the container within 20-40° C. under stirring until all components are completely dissolved, the solution is colorless or light yellow, and a semiconductor silicon wafer etching solution is prepared. The semiconductor silicon wafer etching solution of the present invention is a safe, environmentally friendly and efficient etching solution, the etching rate of the etching solution is stable, the etching surface is flat, and the rough silicon surface has a chemical polishing effect, can be applied in the semiconductor field, and can solve the problem of thinning the silicon substrate of the chip.

Description

Technical Field

[0001] The invention relates to etching technology, and in particular to a semiconductor silicon wafer etching solution, a preparation method and application thereof. Background Art

[0002] Traditional silicon etching solutions often use HNO 3 -HF system is widely used in the manufacturing process of semiconductor chips to etch silicon. The disadvantages are that the etched surface is rough, the subsequent process has a heavy load on the surface treatment, and the etching solution often contains phosphine components, which has a great impact on the environment, especially water bodies.

[0003] At present, some silicon etching solutions are disclosed, such as:

[0004] US20100120248A1 discloses an etching solution comprising water, nitric acid, hydrofluoric acid and sulfuric acid. More specifically, it contains 15 to 40% by weight of nitric acid, 10 to 41% by weight of sulfuric acid and 0.8 to 2.0% by weight of hydrofluoric acid. The etching solution is used for etching silicon and for an etching method for silicon wafers.

[0005] KR1020220043520A discloses an etching solution composition for silicon layer and a method for forming a pattern using the etching solution composition, wherein the etching solution composition contains: hydrofluoric acid, nitric acid, a benzenesulfonic acid compound containing an alkyl group having 4 to 16 carbon atoms, a silicon additive and water. The pattern forming method using the composition can provide an effect of inhibiting corrosion and damage of silicon nitride film while increasing the etching rate of polysilicon film.

[0006] CN111019659B discloses a selective silicon etching solution and a method of using the same. The etching solution is used to selectively remove undoped silicon on a p-type silicon substrate, and is composed of nitric acid (or a mixture of nitric acid and nitrate), nitrite, hydrofluoric acid or hydrofluoric acid, a silicon additive, a boron additive, and a solvent. The etching solution uses nitrate and nitrite to oxidize silicon into silicon dioxide; uses hydrofluoric acid to etch away silicon dioxide; the silicon additive is used to adjust the etching rate of silicon; and the boron additive inhibits the etching solution from etching p-type silicon, so that the etching solution has a faster etching rate for undoped silicon than for p-type silicon.

[0007] The above silicon layer etching solution still has some problems, such as rough etching surface and serious pollution caused by etching solution discharge. Therefore, it is still necessary to develop an etching solution that is safe, environmentally friendly and efficient for etching silicon wafers to solve the problem of thinning the silicon substrate of the chip. Summary of the invention

[0008] The purpose of the present invention is to provide a semiconductor silicon wafer etching solution to solve the problems of rough etching surface and serious pollution of etching solution discharge in traditional silicon layer etching solution. The etching solution is safe, environmentally friendly and efficient. The etching rate of the etching solution is stable, the etching surface is flat, and the rough silicon surface has a chemical polishing effect. The etching solution can be used in the semiconductor field and can solve the problem of thinning the chip silicon substrate.

[0009] To achieve the above object, the technical solution adopted by the present invention is: a semiconductor silicon wafer etching solution, comprising the following components in weight proportions:

[0010]

[0011] Furthermore, the pH of the etching solution is less than 4.

[0012] Furthermore, the etching solution preferably has a pH value <1.

[0013] Furthermore, the inorganic acid comprises a component A and a component B, the component A is hydrofluoric acid, and the component B is one or more of hydrochloric acid, hydrobromic acid, iodic acid, sulfuric acid, phosphoric acid, nitric acid and perchloric acid.

[0014] Furthermore, the weight ratio of component A to component B is 5:1-1:2.

[0015] Furthermore, the weight ratio of the component A to the component B is preferably 3:1-1:1.

[0016] Furthermore, the inorganic acid is preferably hydrofluoric acid and nitric acid.

[0017] Furthermore, the weight ratio of the hydrofluoric acid to the nitric acid is 5:1-1:2.

[0018] Furthermore, the weight ratio of the hydrofluoric acid to the nitric acid is preferably 3:1-1:1.

[0019] Furthermore, the weight ratio of the hydrofluoric acid to the nitric acid is most preferably 2:1.

[0020] Furthermore, the inorganic acid is 3-5 parts.

[0021] The semiconductor silicon wafer etching solution of the present invention uses a composite etching system of nitric acid and hydrofluoric acid, and the etching solution has excellent etching performance, can achieve excellent etching effect, has a stable etching rate, and has a smooth etching surface.

[0022] Furthermore, the ammonium salt is one or more of ammonium bifluoride, ammonium bromide, ammonium iodide, ammonium hydrogen sulfate and ammonium dihydrogen phosphate.

[0023] Furthermore, the ammonium salt is preferably diammonium phosphate.

[0024] Furthermore, the ammonium salt is 10-15 parts.

[0025] Furthermore, the organic acid is one or more of benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, trimesic acid, pyromellitic acid, malonic acid, succinic acid, citric acid, tartaric acid, squaric acid, alanine, 2-mercaptoethanesulfonic acid and ethylenediaminetetraacetic acid.

[0026] Furthermore, the organic acid is preferably trimesic acid and 2-mercaptoethanesulfonic acid.

[0027] Furthermore, the weight ratio of trimesic acid to 2-mercaptoethanesulfonic acid is 3:1-1:3.

[0028] Furthermore, the weight ratio of trimesic acid to 2-mercaptoethanesulfonic acid is preferably 2:1-1:2.

[0029] Furthermore, the weight ratio of trimesic acid to 2-mercaptoethanesulfonic acid is most preferably 1:1.

[0030] Furthermore, the organic acid is 30-35 parts.

[0031] The present invention adopts 2-mercaptoethanesulfonic acid to replace organic weak acid, which does not contain phosphine, is not easy to volatilize, and is environmentally friendly. 2-mercaptoethanesulfonic acid has the function of stabilizing pH, thereby improving the stability of etching effect of etching solution on Si. At the same time, the multi-carboxyl structure of specific scale and 2-mercaptoethanesulfonic acid can specifically chelate Si atoms dissolved at the protrusions of the rough Si surface, promote the mass transfer process in the area, and make the coordination effect of the inorganic acid component more inclined to be carried out at the protrusions of the rough surface, thereby playing the role of chemical polishing.

[0032] The semiconductor silicon wafer etching liquid of the present invention uses a composite functional agent of 2-mercaptoethanesulfonic acid and trimesic acid. The surface of the silicon wafer does not need to be polished during the etching process. The cut and doped silicon wafer can be etched to obtain a flat and smooth surface, which is easy to use and saves the cost of subsequent processes.

[0033] Furthermore, the ultrapure water is 40-50 parts.

[0034] Another object of the present invention is to disclose a method for preparing a semiconductor silicon wafer etching solution, comprising the following steps:

[0035] Step 1: Weigh each component according to the weight ratio;

[0036] Step 2: First add ultrapure water into the container, and then add other components into the container. While stirring, stabilize the temperature of the container at 20-40°C until all components are completely dissolved and the solution is colorless or light yellow, thereby preparing a semiconductor silicon wafer etching solution.

[0037] Another object of the present invention is to disclose a use of a semiconductor silicon wafer etching solution in the field of etching semiconductor silicon wafers.

[0038] Furthermore, the method for etching a semiconductor silicon wafer with the semiconductor silicon wafer etching solution comprises the following steps:

[0039] The semiconductor silicon wafer etching solution is used to soak a semiconductor silicon wafer to obtain a soaked semiconductor silicon wafer; the soaked semiconductor chip is placed in ultrapure water and rinsed at least twice to complete the etching of the semiconductor silicon wafer.

[0040] Furthermore, the soaking temperature is 20-50°C.

[0041] Furthermore, the soaking time is 5-15 minutes.

[0042] The semiconductor silicon wafer etching solution, preparation method and application thereof of the present invention have the following advantages compared with the prior art:

[0043] 1) The semiconductor silicon wafer etching solution of the present invention uses a composite functional agent of 2-mercaptoethanesulfonic acid and trimesic acid. The surface of the silicon wafer does not need to be polished during the etching process. The silicon wafer after cutting and doping can be etched to obtain a flat and smooth surface, which is easy to use and saves the cost of subsequent processes.

[0044] 2) The semiconductor silicon wafer etching solution of the present invention uses a composite etching system of hydrofluoric acid and nitric acid in a specific weight ratio. The etching solution has excellent etching performance, can achieve excellent etching effect, has a stable etching rate, and a smooth etching surface.

[0045] 3) The semiconductor silicon wafer etching solution of the present invention has no special requirements for etching of silicon wafers, and etching can be performed after the surface is cleaned with ultrapure water, spun dry or blown dry.

[0046] 4) The components of the semiconductor silicon wafer etching solution of the present invention are environmentally friendly, pollution-free, and have low volatilization loss. After etching, the silicon wafer only needs to be rinsed with pure water, which does no harm to the environment.

[0047] Therefore, the etching solution of the present invention has very good application prospects and large-scale industrial promotion potential in the field of semiconductor chip etching. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a microscope picture of the silicon wafer before etching, magnified 164 times;

[0049] Figure 2 This is a microscope picture of a silicon wafer after being etched using the etching solution prepared in Example 1, magnified 164 times;

[0050] Figure 3This is a microscope picture of a silicon wafer after being etched using the etching solution prepared in Comparative Example 1, magnified 164 times. DETAILED DESCRIPTION

[0051] The present invention is further described below in conjunction with embodiments:

[0052] Examples 1-14

[0053] Examples 1-14 disclose a variety of semiconductor silicon wafer etching solutions, the components and weight ratios of which are shown in Table 1, and the preparation methods thereof are as follows:

[0054] Step 1: Weigh each component according to Table 1;

[0055] Step 2: First add ultrapure water into the container, and then add other components into the container. Stabilize the temperature of the container at 40°C while stirring until all components are completely dissolved and the solution is colorless or light yellow, thereby preparing a semiconductor silicon wafer etching solution.

[0056] Table 1 Components and weight ratios of semiconductor silicon wafer etching solutions of Examples 1-14

[0057]

[0058]

[0059] Comparative Examples 1-5

[0060] Comparative Examples 1-5 disclose a variety of etching solutions, the components and weight ratios of which are shown in Table 2, and the preparation methods thereof are the same as those of Example 1.

[0061] Table 2 Components and weight ratios of etching solutions of Comparative Examples 1-5

[0062]

[0063] Performance Testing

[0064] Next, various properties of the above-mentioned polishing fluids were tested, as follows.

[0065] Figure 1 This is a microscope picture of the silicon wafer before etching, magnified 164 times; Figure 2 This is a microscope picture of a silicon wafer after being etched using the etching solution prepared in Example 1, magnified 164 times; Figure 3 The microscopic picture of the silicon wafer after etching with the etching solution prepared in Comparative Example 1 after magnification 164 times is shown. It can be seen that the surface soaked in the example has a significant polishing effect, and its surface is flat and has low roughness. The surface soaked in the comparative example has a poor effect compared with the example, and the surface is rough.

[0066] Table 3 is the performance test data of Examples 1-14 and Comparative Examples 1-5. It can be seen that each embodiment has a strong selective etching ratio, but the selectivity of the embodiment that does not select the compound organic weak acid is weak. The etching rate of Comparative Example 1 is not much different from that of the embodiment, but there is no difference in etching rate, and the surface is rough. It can be seen that the importance of weak acids and combinations disclosed in this patent to etching selectivity and chemical polishing performance. The number of hydrofluoric acid + nitric acid in Comparative Example 2 is large, its rate is too large, and the etching selectivity effect decreases. There is an etching selectivity difference in Comparative Example 3, and the etching effect of this group deteriorates after being placed for a period of time. Comparative Examples 4 and 5 have an incomplete system of hydrofluoric acid + strong acid, and only hydrofluoric acid or nitric acid exists, and their etching rates are extremely low, so it can be considered that there is no obvious etching effect on the silicon wafer.

[0067] Table 3 Test results of Examples 1-14 and Comparative Examples 1-5

[0068]

[0069]

[0070] in:

[0071] Performance 1 The test method for etching effect is:

[0072] A heavily doped silicon wafer is selected and the etching solution of the above embodiment and comparative example of the present invention is used to etch the silicon wafer. The etching method comprises the following steps:

[0073] Step 1: Immerse the silicon wafer in an etching solution at 25° C. for 20 minutes to obtain an immersed silicon wafer;

[0074] Step 2: Rinse the soaked silicon wafer in ultrapure water three times to complete the cleaning process of the silicon wafer.

[0075] The ultrapure water used in steps 1 and 2 is deionized water with a resistance of at least 18 MΩ.

[0076] After cleaning, the surface flatness of the silicon wafer is observed using an optical microscope, and the surface roughness is measured using a roughness meter.

[0077] The test method for performance 2 etching selectivity is:

[0078] Lightly and heavily doped silicon wafers are selected, wherein the resistivity of the lightly doped sample is 1-10Ω·cm, and the resistivity of the heavily doped sample is 0.001-0.005Ω·cm. The etching solution of the above embodiment and comparative example of the present invention is used to etch the silicon wafer. The etching treatment method comprises the following steps:

[0079] Step 1: Immerse the lightly doped and heavily doped silicon wafers in an etching solution at 25°C for 20 minutes to obtain soaked silicon wafers;

[0080] Step 2: Rinse the soaked silicon wafer in ultrapure water three times to complete the cleaning process of the silicon wafer.

[0081] The ultrapure water used in steps 1 and 2 is deionized water with a resistance of at least 18 MΩ.

[0082] Before etching and after cleaning, the thickness of the silicon wafer is measured using a thickness meter. The difference is the etched thickness of the silicon wafer, which is divided by the etching time to get the etching rate.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A semiconductor silicon wafer etching solution, characterized in that: The composition includes the following components in weight ratio: 1-6 parts of inorganic acid; 7-20 parts of ammonium salt; 30-40 parts of organic acid; 30-60 parts of ultrapure water; The inorganic acid comprises component A and component B, wherein component A is hydrofluoric acid, and component B is one or more of hydrochloric acid, hydrobromic acid, iodic acid, sulfuric acid, phosphoric acid, nitric acid and perchloric acid; The organic acids are trimesic acid and 2-mercaptoethanesulfonic acid.

2. The semiconductor silicon wafer etching solution according to claim 1, characterized in that: The pH of the etching solution is less than 4.

3. The semiconductor silicon wafer etching solution according to claim 1, characterized in that: The inorganic acids are hydrofluoric acid and nitric acid.

4. The semiconductor silicon wafer etching solution according to claim 3, characterized in that: The weight ratio of the hydrofluoric acid to the nitric acid is 5:1-1:

2.

5. The semiconductor silicon wafer etching solution according to claim 1, characterized in that: The ammonium salt is one or more of ammonium bifluoride, ammonium bromide, ammonium iodide, ammonium hydrogen sulfate and ammonium dihydrogen phosphate.

6. A method for preparing the semiconductor silicon wafer etching solution according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Weigh each component according to the weight ratio; Step 2: First add ultrapure water into the container, and then add other components into the container. While stirring, stabilize the temperature of the container at 20-40°C until all components are completely dissolved and the solution is colorless or light yellow, thereby preparing a semiconductor silicon wafer etching solution.

7. Use of the semiconductor silicon wafer etching solution according to any one of claims 1 to 5 in the field of etching semiconductor silicon wafers.

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