CN-119614203-B - Etching solution for selectively etching silicon nitride and silicon oxide and titanium nitride

Abstract

The invention relates to an etching solution for selectively etching silicon nitride, silicon oxide and titanium nitride, which comprises phosphoric acid, a surfactant, an etching inhibitor and ultrapure water. The etching solution and the processing conditions have higher etching selectivity and stable etching rate for etching silicon nitride, silicon oxide and titanium nitride. The surfactant can improve the solubility of a solvent in the etching solution, reduce the tension of a solid-liquid phase interface in the solution and promote the transfer rate of interphase substances, thereby improving the selection ratio of silicon nitride to silicon oxide, and finally the selection ratio is more than 100, and the etching inhibitor can form a layer of film on the surface of titanium nitride in a coordination bond form with metal, so that the etching rate of the etching solution to the titanium nitride is greatly reduced, and the etching selection ratio is more than 20. The etching solution can inhibit the etching rate of titanium nitride under the condition of higher etching rate of silicon nitride, and can ensure that the requirements of high selectivity of silicon nitride, silicon oxide and titanium nitride are met.

Inventors

• LI FEI
• XU ZE
• HUANG LI
• HE ZHAOBO
• FENG KAI
• Ban Changsheng
• LI SUYUN
• Su Zhangxuan
• LUO JIAYANG
• YAN FAN
• Fan si

Assignees

• 湖北兴福电子材料股份有限公司

Dates

Publication Date

20260512

Application Date

20241125

Claims (8)

1. 1. The selective etching solution for silicon nitride, silicon oxide and titanium nitride is characterized by comprising, by mass, 10-45% of acidic substances, 0.01-1.8% of oxidizing agents, 0.1-7% of titanium etching inhibitors, 0.5-2.5% of metal complexing agents and the balance of deionized water; the acidic substance comprises one or more of phosphoric acid, acetic acid, nitric acid and sulfuric acid; The oxidant is one or the combination of more of hydrogen peroxide, sodium hypochlorite and potassium permanganate; the titanium etching inhibitor is one or a combination of more of tebufenimidazole, imidazole gray, fenbuimidazole, 1- (3-fluorophenyl) imidazole, N-pentafluorophenoxyimidazole, 5, 6-dibromobenzotriazol and 4-phenyl-1, 2, 3-triazol; The metal complexing agent is one or a combination of more of glycylglycine, triethylenetetramine hexaacetic acid, glycine tert-butyl ester and choline bitartrate.
2. 2. The selective etching solution of silicon nitride, silicon oxide and titanium nitride according to claim 1, wherein the selectivity of the etching solution is greater than 15 and the selectivity of the etching solution is greater than 100.
3. 3. Use of a selective etching solution of silicon nitride and silicon oxide, titanium nitride according to claim 1 for etching semiconductor materials containing silicon nitride, titanium nitride and silicon oxide.
4. 4. The method of claim 3, wherein the selective etchant is used for selectively etching silicon nitride in etching silicon nitride-silicon oxide-containing semiconductor material and silicon nitride-titanium nitride semiconductor material.
5. 5. The use according to claim 4, wherein the etching of the silicon nitride-silicon oxide containing semiconductor material has a selectivity of greater than 100; The etching of the silicon nitride-titanium nitride containing semiconductor material has a selectivity greater than 20.
6. 6. The use according to claim 5, wherein the etching of the silicon nitride-silicon oxide containing semiconductor material has a selectivity of greater than 200; The etching of the silicon nitride-titanium nitride containing semiconductor material has a selectivity greater than 30.
7. 7. The use of claim 6, wherein the etch silicon nitride-silicon oxide-containing semiconductor material has a selectivity greater than 300; The etching of the silicon nitride-titanium nitride containing semiconductor material has a selectivity greater than 100.
8. 8. The use of claim 7, wherein the etch silicon nitride-silicon oxide-containing semiconductor material has a selectivity greater than 400.

Description

Etching solution for selectively etching silicon nitride and silicon oxide and titanium nitride Technical Field The invention belongs to the field of electronic chemicals, and particularly relates to a 3D DRAM etching solution. Background Titanium nitride is widely used in the semiconductor industry as a hard mask, metal barrier layer, conductive electrode, metal gate, etc. because of its good metal diffusion barrier properties and low resistivity after annealing. Some other advanced process chip configurations use titanium nitride to improve transistor performance. Silicon nitride, which has excellent thermal stability, mechanical properties and chemical stability, is widely used in high-temperature, high-power and high-frequency electronic devices. It has a wide energy gap, and its conductivity can be adjusted by doping, and is thus regarded as an important semiconductor material. In recent years, DRAM dynamic random access memory is a memory technology widely used in various fields of computers. As transistor sizes shrink, the capacity evolution of DRAM faces challenges. First, leakage current problems are becoming increasingly serious due to the shrinking transistor dimensions (SHRINKING FACTOR). Second, as the capacitance of the memory cells becomes smaller, read and write operations become more difficult, which also increases the bit error rate. The transistors densely arranged in the traditional DRAM cause the problems of current leakage, interference and the like on a two-dimensional plane, and the 3D DRAM effectively increases the interval between the transistors by stacking the transistors in layers, thereby remarkably reducing the risk of leakage and crosstalk and providing an innovative approach for solving the problems. With the continued shrinkage of semiconductor devices and feature sizes, the electronic chemical industry has grown very rapidly. Etching techniques have long been used by the industry as the most stable, effective and widespread technique for semiconductor materials. However, as the requirements of the semiconductor industry on the product yield are higher and higher, how to improve the etching rate of the etching solution on the silicon nitride and simultaneously inhibit the etching of the barrier layer titanium nitride becomes a problem to be solved in the field. On the premise of ensuring the etching stability and uniformity, the etching time is better controlled for the etching solution with larger selection ratio of silicon nitride, titanium nitride and silicon oxide, the production period is shortened, the product yield is improved, and the production cost of semiconductor products is saved. Therefore, development of a high selectivity etching solution having excellent performance is particularly urgent. The etching solutions and etching conditions described herein provide high etch selectivity of silicon nitride and titanium nitride materials that can partially or completely remove silicon nitride structures without significantly damaging the titanium nitride structures. Disclosure of Invention The invention aims to provide an etching solution for selectively etching silicon nitride, silicon oxide and titanium nitride, which not only can ensure the stability and uniformity of etching, but also has higher etching selectivity to the silicon nitride, the silicon oxide and the titanium nitride, and can partially or completely remove the silicon nitride structure without obviously damaging the silicon oxide and the titanium nitride structure, thereby improving the yield of semiconductor products and saving the production cost of the products. In order to achieve the above object, there is provided a method for producing an etching solution for selectively etching silicon nitride, silicon oxide and titanium nitride, comprising the steps of: An etching solution for selectively etching silicon nitride, silicon oxide and titanium nitride is prepared from phosphoric acid, oxidant, etching inhibitor and ultrapure water. The titanium etching inhibitor comprises 10-45% of acidic substances, 0.01-1.8% of oxidizing agents, 0.1-7% of titanium etching inhibitors, 0.5-2.5% of metal complexing agents, and the balance of deionized water and ultrapure water. Preferably, the acidic substance comprises one or more of phosphoric acid, acetic acid, nitric acid and sulfuric acid. The phosphoric acid in the etching solution is electronic grade phosphoric acid with the mass concentration of 70-95%. Preferably, the oxidant in the etching solution is one or a combination of more of hydrogen peroxide, sodium hypochlorite and potassium permanganate. Preferably, the etching inhibitor in the etching solution is one or more than two of tebubendazole, flumazenil, imidazole gray, fenflumidazole, 1- (3-fluorophenyl) imidazole, N-pentafluorophenoxyimidazole, 5, 6-dibromobenzotriazol and 4-phenyl-1, 2, 3-triazole. Preferably, the metal complexing agent is one or a combination of a plurality of glycylglycine, t