Metal corrosion method suitable for coating PI product and nickel-silver metal corrosion liquid

Abstract

The invention discloses a metal corrosion method suitable for coating a PI product and nickel-silver metal corrosion liquid. The metal corrosion method comprises the following steps: evaporating an aluminum layer on the surface of a silicon wafer for preparing a transistor, corroding the aluminum layer by using an aluminum corrosive liquid, corroding a pattern, carrying out alloying treatment on the aluminum layer to obtain an aluminum-silicon alloy, carrying out PI (Polyimide) covering on the wafer, then carrying out developing treatment, and sequentially evaporating thin layers of a metal titanium layer, a nickel layer and a silver layer, and etching the nickel layer and the silver layer by using a nickel-silver metal corrosive liquid, and corroding the titanium layer by using a hydrofluoric acid aqueous solution. The nickel-silver metal corrosion liquid suitable for coating the PI product is mainly prepared by mixing glacial acetic acid, nitric acid and water. The metal surface quality of the transistor can be improved, the problem that PI is prone to falling off is solved, and the production cost is reduced.

Description

Technical Field

[0001] The invention belongs to the field of transistor preparation, and in particular relates to a metal corrosion method suitable for coating PI products and a nickel-silver metal corrosion solution. Background Art

[0002] In the existing metal corrosion process, a high concentration of nitric acid is used to remove the silver layer, and then a mixed solution of nitric acid and hydrofluoric acid is used to corrode the metal nickel and titanium layers. However, high concentration nitric acid is highly corrosive to photoresist and PI, causing excessive lateral corrosion, making the corrosion rate difficult to control, and causing PI to fall off.

[0003] In view of the above-mentioned defects of the prior art, it is necessary to develop new titanium, nickel, silver metal etching liquids and corresponding process flows. Summary of the invention

[0004] The purpose of the present invention is to provide a metal corrosion method suitable for coating PI products based on the prior art.

[0005] Another object of the present invention is to provide a nickel-silver metal etching solution that can be used to coat PI products.

[0006] The purpose of the present invention can be achieved by the following measures:

[0007] A metal corrosion method suitable for coated PI products, comprising the following steps:

[0008] S1, evaporating an aluminum layer on the surface of a silicon wafer used to prepare a transistor;

[0009] S2, etching the aluminum layer using an aluminum etching solution to etch out a pattern;

[0010] S3, performing alloy treatment on the aluminum layer after step S2 to obtain an aluminum-silicon alloy;

[0011] S4, after step S3, the wafer is covered with PI, and then subjected to development treatment;

[0012] S5, sequentially evaporating a thin layer of a titanium layer, a nickel layer and a silver layer on the aluminum layer;

[0013] S6, etching the nickel layer and the silver layer using a nickel-silver metal etching solution; the nickel-silver metal etching solution is mainly composed of a mixture of glacial acetic acid, nitric acid and water;

[0014] S7, using a hydrofluoric acid aqueous solution to corrode the titanium layer.

[0015] The present invention also includes a nickel-silver metal etching liquid suitable for coating PI products, which is mainly a mixture of glacial acetic acid, nitric acid and water. The corrosion rate of the metal etching liquid is stable and easy to control, and the lateral drilling corrosion is within about 10um, which can significantly improve the metal surface quality and solve the problem of PI shedding.

[0016] In a preferred embodiment, the thickness of the aluminum layer in S1 is 2 μm.

[0017] In a preferred embodiment, the nickel-silver metal etching solution comprises 40-50% glacial acetic acid, 20-30% nitric acid, and the remainder water.

[0018] In another preferred embodiment, the nickel-silver metal etching solution comprises 40-50% glacial acetic acid, 20-30% nitric acid, and the remainder water.

[0019] In a preferred embodiment, the mass ratio of hydrofluoric acid to water in the hydrofluoric acid aqueous solution is 1:40.

[0020] In step S5 , the thickness of the titanium layer is 0.1 μm, the thickness of the nickel layer is 0.3 μm, and the thickness of the silver layer is 1.2 μm.

[0021] Beneficial effects of the present invention:

[0022] The present invention provides a nickel-silver metal etching liquid suitable for coating PI products, and a corresponding metal etching method. The present invention solves the insufficiency of the existing process manufacturing capacity, develops a new metal etching liquid, and formulates a new process flow corresponding thereto. The metal etching liquid of the present invention has the advantages of stable and easy-to-control corrosion rate, lateral drilling corrosion within about 10um, small lateral drilling corrosion, can reduce the corrosion to the glue, make the graphic lines straighter, can significantly improve the metal surface quality, and solve the problem of PI falling off. Through the technical solution of the present invention, the metal surface quality of the transistor is greatly improved, the problem of PI easy falling off is solved, and the production cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the distribution structure of a transistor metal layer in the prior art;

[0024] In the figure: 1 - aluminum metal layer; 2 - titanium metal layer; 3 - nickel metal layer; 4 - silver metal layer; 5 - passivation and PI covering layer. DETAILED DESCRIPTION

[0025] The present invention can be better understood according to the following examples. However, it is easy for those skilled in the art to understand that the contents described in the examples are only used to illustrate the present invention, and should not and will not limit the present invention described in detail in the claims.

[0026] Example 1: Metal corrosion method suitable for coating PI products

[0027] The following Figure 1 Taking the graphic structure in as an example, the metal corrosion method suitable for coated PI products of the present invention is described, which comprises the following steps:

[0028] S1, first evaporate a layer of aluminum on the surface of the silicon wafer used to prepare the transistor, the thickness of the aluminum layer is 2μm;

[0029] S2. Use aluminum etching liquid to etch the evaporated aluminum layer to etch out a pattern; the aluminum etching liquid can use the aluminum etching liquid available on the market.

[0030] S3, performing alloy treatment on the aluminum layer after step S2 to obtain an aluminum-silicon alloy;

[0031] S4, after step S3, the wafer is covered with PI, and then subjected to development treatment;

[0032] S5. Sequentially evaporate thin layers of a titanium layer, a nickel layer and a silver layer on the aluminum layer; the thickness of the titanium layer is 0.1 μm, the thickness of the nickel layer is 0.3 μm, and the thickness of the silver layer is 1.2 μm.

[0033] S6, etching the nickel layer and the silver layer using a nickel-silver metal etching solution;

[0034] S7, using a hydrofluoric acid aqueous solution to corrode the titanium layer.

[0035] This method can effectively improve the lines of the metal contact area and prevent PI from being eroded and falling off.

[0036] The nickel-silver metal etching solution in the method has a mass composition of 40-50% glacial acetic acid, 20-30% nitric acid, and the balance of water. The corrosion rate of the metal etching solution is stable and easy to control, and the lateral drilling corrosion is within about 10um, which can significantly improve the metal surface quality and solve the problem of PI shedding.

[0037] Example 2

[0038] The invention discloses a nickel-silver metal etching liquid suitable for coating PI products, which comprises the following components by weight: 40-50% glacial acetic acid, 20-30% nitric acid, and the balance water.

[0039] It should be specially pointed out here that this new metal etching solution is not limited to etching transistors coated with PI products, and the metal etching of conventional products also belongs to the technical concept of the present invention.

[0040] 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, a person skilled in the art should understand that it is still possible to modify the technical solutions described in the aforementioned embodiments, or to perform equivalent replacements on some of the technical features therein. 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 metal corrosion method suitable for coating PI products, characterized in that It includes the following steps: S1, evaporating an aluminum layer on the surface of a silicon wafer used to prepare a transistor; S2, etching the aluminum layer using an aluminum etching solution to etch out a pattern; S3, performing alloy treatment on the aluminum layer after step S2 to obtain an aluminum-silicon alloy; S4, after step S3, the wafer is covered with PI, and then subjected to development treatment; S5, sequentially evaporating a thin layer of a titanium layer, a nickel layer and a silver layer on the aluminum layer; S6, etching the nickel layer and the silver layer using a nickel-silver metal etching solution; the nickel-silver metal etching solution is mainly composed of a mixture of glacial acetic acid, nitric acid and water; S7, using a hydrofluoric acid aqueous solution to corrode the titanium layer.

2. The method according to claim 1, characterized in that In S1, the thickness of the aluminum layer is 2 μm.

3. The method according to claim 1, characterized in that The nickel-silver metal etching solution comprises: 40-50% glacial acetic acid, 20-30% nitric acid, and the balance water.

4. The method according to claim 3, characterized in that The nickel-silver metal etching solution comprises: 40-50% glacial acetic acid, 20-30% nitric acid, and the balance water.

5. The method according to claim 1, characterized in that In S7, the mass ratio of hydrofluoric acid to water in the hydrofluoric acid aqueous solution is 1:

40.

6. A nickel-silver metal etching solution suitable for coating PI products, characterized in that It is mainly composed of a mixture of glacial acetic acid, nitric acid and water.

7. The metal corrosive liquid according to claim 6, characterized in that Its mass composition is: 40-50% glacial acetic acid, 20-30% nitric acid, and the balance is water.

8. The metal corrosive liquid according to claim 7, characterized in that Its mass composition is: 40-50% glacial acetic acid, 20-30% nitric acid, and the balance is water.

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