Plasma etching method and plasma etching unit

Abstract

The present invention is a plasma etching method including: an arranging step of arranging a pair of electrodes oppositely in a chamber and making one of the electrodes support a substrate to be processed in such a manner that the substrate is arranged between the electrodes, the substrate having a silicon film and an inorganic-material film adjacent to the silicon film; and an etching step of applying a high-frequency electric power to at least one of the electrodes to form a high-frequency electric field between the pair of the electrodes, supplying a process gas into the chamber to form a plasma of the process gas by means of the electric field, and selectively plasma-etching the silicon film of the substrate by means of the plasma; wherein a frequency of the high-frequency electric power applied to the at least one of the electrodes is 50 to 150 MHz in the etching step.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a plasma etching method and a plasma etching unit of plasma-etching a silicon film formed on a substrate to be processed such as a semiconductor wafer, which has the silicon film and an inorganic-material film adjacent to the silicon film. DESCRIPTION OF THE RELATED ART [0002] In a manufacturing step of a semiconductor device, a multilayer film including a silicon film, such as a poly-silicon film, and insulating films is formed on a semiconductor wafer, and then a plasma-etching process is conducted in order to form a predetermined wiring pattern. [0003] In order to conduct the plasma-etching process, various kinds of units are used. Among them, a capacitive-coupling type of parallel-plate plasma etching unit is used mainly. In the capacitive-coupling type of parallel-plate plasma etching unit, a pair of parallel-plate electrodes (upper electrode and lower electrode) are arranged in a chamber, a process gas is introduce...

AI Technical Summary

Benefits of technology

[0007] This invention is developed by focusing the aforementioned problems in order to resolve them effectively. An object of the present invention is to provide a plasma etching method and a plasma etching unit that can etch a silicon film adjacent to an inorganic-material film with a high etching selective ratio and a good etching geometric control performance.

Problems solved by technology

However, when the etching process is conducted under the conventional relatively high pressure, although the etching selectivity of the silicon film with respect to the inorganic-material film is enhanced, an etching geometric control performance is not good.

This problem is arisen not only in the case using the mask of the inorganic-material film, but also in another case wherein an inorganic-material film is formed as a base of the silicon film.

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