Silicon wafer cleaning etching liquid and its application in inhibiting silicon wafer surface oxidation

Abstract

The application relates to the technical field of electronic chemicals, and particularly discloses a silicon wafer cleaning etching liquid and application thereof in inhibiting oxidation of a silicon wafer surface. The etching liquid contains, in percentage by mass, 0-10% of hydrofluoric acid, 0-30% of ammonium fluoride and 0.001-1% of an additive, and the rest is water; the additive is a compound containing olefins and amides. In the application, the cleaning system is composed of hydrofluoric acid and ammonium fluoride, and a compound containing olefins and amides is introduced as the additive, so that free radicals on the surface of the silicon wafer are modified, the natural oxidation of the surface of the silicon wafer after cleaning can be effectively inhibited, and the stability and precision of subsequent manufacturing processes are ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic chemicals, in particular to a silicon wafer cleaning etching liquid and its application in inhibiting the oxidation of the surface of a silicon wafer. BACKGROUND

[0002] Functional electronic chemicals refer to special chemicals matched with the electronic industry, which are often used in the cleaning and etching processes in the manufacturing process of integrated circuit structures; the chemicals for wet cleaning and etching have high quality requirements, strong functionality and high product precision.

[0003] With the rapid development of integrated circuits, the manufacturing precision of the GATE region of IGBT and MOSFET processes is increasingly high. With the increase of the manufacturing line width, the natural oxide layer has a significant influence on the electrical signal conduction of the chip, and it is increasingly important to avoid the natural oxidation of the silicon wafer, which is a very key link for the reliability of microelectronic integrated circuits. SUMMARY

[0004] The present application provides a silicon wafer cleaning etching liquid and its application in inhibiting the oxidation of the surface of a silicon wafer, which is used for cleaning the surface oxide layer of a base silicon in semiconductor manufacturing and can effectively inhibit the natural oxidation of the surface of a silicon wafer after cleaning.

[0005] The technical solution of the present application is to provide a silicon wafer cleaning etching liquid, which contains, by mass percentage, 0.1-10% of hydrofluoric acid, 1-30% of ammonium fluoride and 0.001-0.5% of an additive, and the rest is water; the additive is a compound containing olefins and amides.

[0006] Optionally, the content of hydrofluoric acid is 0.1-5% by mass percentage.

[0007] Optionally, the hydrofluoric acid is of an electronic grade and has a mass concentration of 48-50%.

[0008] Optionally, the content of ammonium fluoride is 1-20% by mass percentage.

[0009] Optionally, the ammonium fluoride is of an electronic grade and has a mass concentration of 48-50%.

[0010] Optionally, the compound containing olefins and amides is any one or a combination of butenamide, octenamide, dodecenamide, undec-10-enamide and arachidonamide.

[0011] Optionally, the additive is added in an amount of 0.05-0.2%.

[0012] Optionally, the water is ultrapure water, and the resistivity thereof is ≥18 megaohms at 25℃.

[0013] The application also relates to application of the silicon wafer cleaning etching liquid in inhibiting natural oxidation of a silicon wafer surface after cleaning.

[0014] The application has the following beneficial effects:

[0015] In the application, the cleaning system is composed of hydrofluoric acid and ammonium fluoride, the hydrofluoric acid is used for cleaning the oxide layer film, the ammonium fluoride is used for providing fluorine ions to stabilize the cleaning etching liquid, and the cleaning etching liquid can effectively remove impurities and the oxide layer on the surface of the silicon wafer; meanwhile, the compound containing olefin and amide is introduced into the cleaning etching liquid as an additive, the free radicals on the surface of the silicon wafer are modified, the natural oxidation of the silicon wafer surface after cleaning can be effectively inhibited, and the stability and precision of the subsequent manufacturing process can be ensured. DETAILED DESCRIPTION

[0016] In the following examples, the experimental methods are conventional methods, and the raw materials, reagent materials and the like used in the following examples are commercially available products, unless otherwise specified.

[0017] The application provides a silicon wafer cleaning etching liquid, which contains 0.1-10% of hydrofluoric acid, 1-30% of ammonium fluoride and 0.001-0.5% of an additive according to mass percentage, and the rest is water; the additive is a compound containing olefin and amide.

[0018] The hydrofluoric acid is electronic grade, and the mass concentration is 48-50%; the etching liquid preferably contains 0.1-5% of the hydrofluoric acid. The ammonium fluoride is electronic grade, and the mass concentration is 48-50%. The etching liquid preferably contains 1-20% of the ammonium fluoride. Specifically, the compound containing olefin and amide is preferably any one or a combination of butenamide, octenamide, dodecenamide, undec-10-enamide and arachidonamide, and the addition amount is preferably 0.05-0.2%.

[0019] The water is ultrapure water, and the resistivity is greater than or equal to 18 megaohms at 25 DEG C.

[0020] The application will be described in detail below in combination with specific examples. The examples are implemented on the premise of the technical scheme of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following examples.

[0021] Example 1

[0022] The composition of the silicon wafer cleaning etching liquid is as follows: 0.5wt% of hydrofluoric acid, 5wt% of ammonium fluoride, 0.1wt% of octenamide, and the rest is water.

[0023] Example 2

[0024] The composition of the silicon wafer cleaning etching liquid is as follows: 1wt% of hydrofluoric acid, 5wt% of ammonium fluoride, 0.1wt% of octenamide, and the rest is water.

[0025] Example 3

[0026] Composition of the silicon wafer cleaning etching solution: 0.5 wt% hydrofluoric acid, 10 wt% ammonium fluoride, 0.1 wt% octenylamide, and the balance water.

[0027] Example 4

[0028] Composition of the silicon wafer cleaning etching solution: 0.5 wt% hydrofluoric acid, 5 wt% ammonium fluoride, 0.05 wt% dodecenylamide, and the balance water.

[0029] Example 5

[0030] Composition of the silicon wafer cleaning etching solution: 0.5 wt% hydrofluoric acid, 5 wt% ammonium fluoride, 0.2 wt% butenylamide, and the balance water.

[0031] Example 6

[0032] Composition of the silicon wafer cleaning etching solution: 0.5 wt% hydrofluoric acid, 5 wt% ammonium fluoride, 0.1 wt% arachidonamide, and the balance water.

[0033] Comparative Example 7

[0034] Composition of the silicon wafer cleaning etching solution: 0.5 wt% hydrofluoric acid, 5 wt% ammonium fluoride, 1 wt% arachidonamide, and the balance water.

[0035] Comparative Example 8

[0036] Composition of the silicon wafer cleaning etching solution: 15 wt% hydrofluoric acid, 5 wt% ammonium fluoride, 0.1 wt% butenylamide, and the balance water.

[0037] Comparative Example 9

[0038] Composition of the silicon wafer cleaning etching solution: 0.5 wt% hydrofluoric acid, 35 wt% ammonium fluoride, 0.1 wt% octenylamide, and the balance water.

[0039] Comparative Example 10

[0040] Composition of the silicon wafer cleaning etching solution: 0.5 wt% hydrofluoric acid, 5 wt% ammonium fluoride, 0.1 wt% butene, and the balance water.

[0041] Comparative Example 11

[0042] Composition of the silicon wafer cleaning etching solution: 0.5 wt% hydrofluoric acid, 5 wt% ammonium fluoride, and the balance water.

[0043] The above examples and comparative examples were used for cleaning test of silicon wafer. After 5*5cm Si wafer was soaked in 500ml cleaning etching solution for 30min, it was taken out, washed with water, dried with nitrogen, and placed in natural environment for 2h. The thickness of natural oxide layer on the surface was measured by ellipsometer. The specific results are shown in Table 1.

[0044] Table 1

[0045] Table 1. Thickness of natural oxide layer on the surface of silicon wafer after cleaning

[0046]

[0047] From Table 1, it can be seen that the thickness of initial oxide layer on the surface of silicon wafer cleaned by the etching solution in Examples 1-6 was 0.01nm, and the thickness change of natural oxide layer after 2h was not more than 0.15nm. Although the change of natural oxide layer in Comparative Example 7 was small, the additive was completely dissolved, the solution was turbid, and the cleaning of the surface of silicon wafer was not uniform, which caused the problem of uneven natural oxide layer on the surface. In Comparative Example 8, the etching solution was too acidic, which provided more hydrogen ions to form free radicals on the surface of silicon wafer, leading to easier formation of natural oxidation. In Comparative Example 9, the solution was too alkaline, which caused corrosion of silicon and increased the surface roughness, promoting surface oxidation. In Comparative Example 10, the additive lacked amide groups, which failed to inhibit the natural oxidation of the surface of silicon wafer. In Comparative Example 11, no additive was added, and the oxidation degree of the surface of silicon wafer after cleaning was the most serious.

[0048] The above examples describe the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including combination of various technical features in any other way. These simple modifications and combinations should also be considered as disclosed by the present application, and belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A silicon wafer cleaning and etching solution, characterized in that, The etching solution contains, by mass percentage, 0.1-10% hydrofluoric acid, 1-30% ammonium fluoride, and 0.001-0.5% additives, with the remainder being water; the additives are compounds containing olefins and amides; the hydrofluoric acid is electronic grade with a mass concentration of 48-50%; the ammonium fluoride is electronic grade with a mass concentration of 48-50%; the compounds containing olefins and amides are any one or a combination of butenamide, octenamide, dodecenamide, undec-10-enamide, and arachidonicamide.

2. The etching solution according to claim 1, characterized in that: The hydrofluoric acid content is 0.1-5% by mass percentage.

3. The etching solution according to claim 1, characterized in that: The ammonium fluoride content is 1-20% by mass percentage.

4. The etching solution according to claim 1, characterized in that: The amount of the additive added is 0.05~0.2%.

5. The etching solution according to claim 1, characterized in that: The water is ultrapure water with a resistivity ≥18 megohms at 25℃.

6. The application of the silicon wafer cleaning and etching solution according to any one of claims 1 to 5 in suppressing natural oxidation of the silicon wafer surface after cleaning.

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