Chromium and chromium alloy etching solution

Abstract

The invention relates to a chromium and chromium alloy etching solution which comprises the following components in percentage by mass: 15-25% of ceric ammonium nitrate, 10-15% of acid, 1-5% of oxidant, 1-5% of stabilizer and the balance of deionized water, and the acid is one or more of nitric acid, acetic acid and phosphoric acid; the oxidizing agent is one or more of potassium dichromate, ceric sulfate and potassium permanganate; the stabilizing agent is one or more of 2-phosphoric acid-1, 2, 4-tricarboxylic acid butane, 2-mercaptobenzothiazole, 1-hydroxyethyl-2-oleyl imidazoline and dodecyl imidazoline, and the stabilizing agent is one or more of 2-phosphoric acid-1, 2, 4-tricarboxylic acid butane, 2-mercaptobenzothiazole, 1-hydroxyethyl-2-oleyl imidazoline and dodecyl imidazoline. According to the etching solution, the ammonium ceric nitrate and the oxidizing agent can have a certain etching effect on a chromium layer under the acidic condition, and the stabilizing agent also serves as a corrosion inhibitor, so that the etching rate can be effectively adjusted, and the service life of the etching solution is prolonged. The etching solution has etching controllability while stably and quickly etching chromium and chromium alloy, hardly corrodes silicon and silicon dioxide substrates, and can prevent a photoresist layer from being degraded.

Description

Technical Field

[0001] The invention belongs to the technical field of etching in the semiconductor industry, and in particular relates to a chromium and chromium alloy etching solution. Background Art

[0002] In the semiconductor manufacturing process, wet etching is one of the more important technologies. Chromium is widely used in electrodes and wiring materials due to its excellent conductivity, stability, and good metal adhesion. Introducing various other alloys on the chromium layer can form low-resistance thin film materials, which is a hot topic for future research.

[0003] The current chromium etching solutions are mainly composed of ammonium cerium nitrate and nitric acid. The etching rate of the etching solution is slow and the stability is poor. Long-term immersion may cause the photoresist to detach, resulting in poor etching effect. The etching rate is even slower when etching chromium silicon, chromium silicon nitrogen and other alloys. Therefore, it is urgent to develop a chromium and chromium alloy etching solution with a faster etching rate, stable and controllable rate, and no etching of substrate silicon and silicon dioxide substrates. Summary of the invention

[0004] To overcome the deficiencies of the prior art, the main purpose of the present invention is to provide a chromium and chromium alloy etching solution, which can stably and quickly etch chromium and other chromium alloys such as chromium nickel, chromium silicon, etc.

[0005] To achieve the above object, the technical solution adopted by the present invention is: A chromium and chromium alloy etching solution comprises: 15% to 25% by mass of ammonium cerium nitrate, 10% to 15% by mass of acid, 1% to 5% by mass of oxidant, 1% to 5% by mass of stabilizer, and the balance being deionized water.

[0006] Furthermore, the acid is one or more of nitric acid, acetic acid, and phosphoric acid.

[0007] Furthermore, the oxidant is one or more of potassium dichromate, ceric sulfate, and potassium permanganate.

[0008] Furthermore, the stabilizer is one or more of 2-phospho-1,2,4-tricarboxylic acid butane, 2-mercaptobenzothiazole, 1-hydroxyethyl-2-oleyl imidazoline, and dodecyl imidazoline.

[0009] The present invention also provides an etching method of the chromium and chromium alloy etching solution, which comprises bringing the etching solution into contact with a substrate containing a thin film of Cr, NiCr, CrSi, CrSiN or the like.

[0010] Furthermore, the contacting is to immerse the substrate containing a thin film such as Cr, NiCr, CrSi, CrSiN, etc. in the etching solution, the contact time is 3-8 minutes, the contact temperature is 20°C-50°C, and the stirring rate during contact is 300r / min-500r / min.

[0011] In the technical solution of the present invention, ammonium cerium nitrate and an oxidant work together to oxidize a metal element, which then reacts with an acid to form metal ions, and the metal ions are more easily reacted with the acid, thereby achieving etching of chromium; the acid provides an acidic environment, reduces the pH, accelerates the etching rate of chromium or its alloy, and prevents the hydrolysis of ammonium cerium nitrate from causing a reduction in the oxidant, and the presence of the acid can achieve the recycling of tetravalent cerium ions; the stabilizer also acts as a corrosion inhibitor, and can stabilize the rate and life of the etching solution.

[0012] The beneficial effects of the present invention are as follows: the etching solution of the present invention can not only etch chromium but also has an etching effect on other chromium alloys without etching substrate silicon and silicon dioxide; the etching rate of chromium can be controlled by adjusting the ratio of ammonium cerium nitrate and the oxidant, thereby achieving a fast and stable etching rate. DETAILED DESCRIPTION

[0013] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0014] The etching solution of the present invention can be prepared by simply and evenly mixing the components described in Table 1.

[0015] Table 1 shows the components and contents of the etching solutions in the examples and comparative examples.

[0016] Cut the test piece Cr into 1.6*1.6cm 2 The fragments of different sizes were immersed in the etching solution described in the embodiment and the comparative example, heated to 25-50°C, and etched for 5 minutes at a stirring rate of 400 r / min. After the etching, they were rinsed with ultrapure water, dried with nitrogen, and then the thickness before and after etching was measured with a probe to obtain the etching rate. The results are shown in Table 2.

[0017] Table 2 Etching effects of examples and comparative examples

[0018] It can be seen from the above examples that the etching rate of the etching solution of the present invention is stable and controllable, and the selectivity for Si and its oxides is relatively high. The etching rate of the etching solution of the present invention for substrate silicon and silicon dioxide is relatively slow, and there is almost no effect on the substrate in a short time. It can be seen from Example 7 and Comparative Examples 1-2 that nitric acid and ammonium cerium nitrate in the present invention have a greater effect on the etching rate; it can be seen from Examples 7-8 and Comparative Examples 3-4 that the addition of an oxidant can effectively increase the etching rate, and an increase in temperature can accelerate the etching rate, but it will reduce the selectivity; while no stabilizer is added in Comparative Example 5, and the etching rate of this system drops sharply after a period of time, and the selectivity is also affected, indicating that the stabilizer affects the etching rate.

[0019] From the above results, it can be seen that the etching solution provided by the present invention, by controlling the content of each component, can achieve a controllable etching rate while stably and quickly etching chromium and chromium alloys, has a lower etching rate for silicon and silicon dioxide, and can prevent degradation of the photoresist layer.

[0020] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A chromium and chromium alloy etching solution, It is characterized in that The etching solution comprises: 15% to 25% by mass of ammonium cerium nitrate, 10% to 15% by mass of acid, 1% to 5% by mass of oxidant, 1% to 5% by mass of stabilizer, and the balance being deionized water.

2. The etching solution according to claim 1, It is characterized in that The acid is one or more of nitric acid, acetic acid and phosphoric acid.

3. The etching solution according to claim 1, It is characterized in that The oxidant is one or more of potassium dichromate, ceric sulfate and potassium permanganate.

4. The etching solution according to claim 1, It is characterized in that The stabilizer is one or more of 2-phosphoryl-1,2,4-tricarboxylic acid butane, 2-mercaptobenzothiazole, 1-hydroxyethyl-2-oleyl imidazoline and dodecyl imidazoline.

5. A method for etching chromium and chromium alloys, It is characterized in that The method comprises: bringing the etching solution according to any one of claims 1 to 4 into contact with a substrate comprising a thin film of Cr, NiCr, CrSi, CrSiN or the like.

6. The etching method according to claim 5, It is characterized in that The contacting is to immerse the substrate containing the thin film of Cr, NiCr, CrSi, CrSiN, etc. in the etching solution, the contact time is 3-8 minutes, the contact temperature is 20°C-50°C, and the stirring rate during contact is 300r / min-500r / min.