Selective etching solution for metal tungsten and copper

Abstract

The invention discloses an etching solution capable of selectively etching metal copper and metal tungsten. The etching solution comprises an oxidant, an organic acid, a chelating agent, a pH regulator and a copper etching inhibitor. According to the selective etching solution for the metal copper and the tungsten disclosed by the invention, the low etching rate of the metal copper can be guaranteed while the metal tungsten is efficiently etched, and etching of the metal copper is avoided to the maximum extent. In the etching process, the pH regulator such as imidazole stabilizes the pH value of the etching solution, and large fluctuation of the pH value of the etching solution is avoided, so that large fluctuation is caused to the etching rate and the etching stability of metal copper and tungsten; the chelating agent and copper ions generated in the etching solution rapidly form coordination bonds to be chelated, and decomposition of an oxidizing agent hydrogen peroxide and stability of a hard etching solution caused by accumulation of the copper ions in the etching solution are avoided; in the etching process of copper ion etching inhibitors such as aminotetrazole, etching of copper ions is inhibited, and high-selectivity etching of metal tungsten relative to copper is guaranteed.

Description

technical field [0001] The present invention relates to the processing of a semiconductor substrate formed with a tungsten film, especially the processing of a semiconductor substrate provided with copper (Cu) wiring, and mainly relates to an etchant for a tungsten film. Background technique [0002] For silicon wafer-based equipment related to semiconductors, it is necessary to design patterns, superimpose various metal layers through sputtering or other processes, and etch with wet chemical liquid to form wiring according to the difference in function and application. or protrusions. [0003] Tungsten (W) or tungsten alloys are commonly used in gate electrodes, lines, and barrier layers of thin film transistors, or for filling contact holes or via holes in PRAM and other semiconductor devices. [0004] Examples of etching solutions for tungsten-based metal films include acid etching solutions such as hydrogen peroxide etching solutions, hydrofluoric acid-hydrogen peroxide...

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Problems solved by technology

[0005] Yet for hydrogen peroxide solution, if contain such as metals such as copper, silver, gold, then can promote the decomposition of hydrogen peroxide, not only can shorten the life-span of etching solution, also have difficulty in controlling the concentration of hydrogen peroxide in etching solution, etch Slow down etc.