Method for anisotropic etching of graphical polyimide layer

Abstract

The invention provides a method for anisotropic etching of a graphical polyimide layer. The method includes the following steps: main etching is carried out: the main thickness layer of a polyimide layer needing to be removed on a bottom circuit is etched by a first mixed gas containing oxygen, carbon and fluorine in plasma form, wherein the ratio of the number of carbon atoms to the number of fluorine atoms in the first mixed gas is greater than or equal to 2:1 so that the side wall of polyimide can be protected; and over etching is carried out: the remaining thickness layer of the polyimidelayer on the bottom circuit is etched by a second mixed gas containing oxygen and carbon and not containing fluorine in plasma form until the polyimide layer is etched completely and patterned. The side wall is protected by a gas with high carbon-to-fluorine ratio during main etching, so that transverse drill-etching of the PI layer is controlled, and the deviation from the design dimension is reduced. The gas for over etching contains carbon but does not contain fluorine, so that the side wall morphology is ensured, the bottom SiN and SiO2 are not basically damaged by etching, the structure is well protected, and the etching process window is expanded.

Description

technical field [0001] The invention relates to a semiconductor manufacturing process method, in particular to a method for anisotropically etching a patterned polyimide layer. Background technique [0002] Polyimide (Polyimide, referred to as PI) material is an organic polymer material with excellent comprehensive properties. Well, the thermal conductivity is very small, reaching 2.5E-4 cal / cm sec ° C, very suitable as a thermal insulation cushion for some microstructures; 3, electrical insulation, is a non-conductive material; 4, using dry oxygen plasma Etching, ashing removal, etc. can be performed. Based on the above advantages, it is often used as a sacrificial layer material of an uncooled infrared bolometer. [0003] PI is typically coated on SiN or SiO with underlying infrared detector processing circuitry 2 On the surface, dry anisotropic etching is required to obtain the support of the device and the top infrared radiation and contact holes. In order to control...

AI Technical Summary

Problems solved by technology

In order to control the anisotropic etching morphology of PI, it is often necessary to 2 Increase the side wall protective gas in the current open patent or the scheme reported in the literature is O 2 CHF 3 or CF 4 etc. This method can obtain a certain degree of anisotropy control of the morphology, but because it contains F, it is difficult for SiN or SiO 2 The selection ratio is not high, resulting in greater damage to related materials, that is, it is impossible to take into account the etching morphology and etching selection ratio

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