Browse Prior Art Database

Flash Etch Technique for Polyimide Insulated Double Metal Contact

IP.com Disclosure Number: IPCOM000088604D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Cook, HC: AUTHOR [+3]

Abstract

This technique eliminates irregularities formed in a polyimide insulation when via holes are etched to form a contact between first and second level metallurgy.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 70% of the total text.

Page 1 of 2

Flash Etch Technique for Polyimide Insulated Double Metal Contact

This technique eliminates irregularities formed in a polyimide insulation when via holes are etched to form a contact between first and second level metallurgy.

The use of cured polyimide as an insulating layer in integrated-circuit components is well known. Fully cured polyimide layers are extremely difficult to etch, a necessary requirement if via holes through the polyimide are required for contact holes. Normally, a two-step curing technique is used in which uncured resin is applied and heated as a first curing step in order to drive off the solvent prior to masking and etching of via holes defined by a layer of photoresist. Etching of the partially cured resin is usually accomplished by an organic base solution such as potassium hydroxide.

This etchant although capable of removing the partially cured resin does so by a process which modifies the composition of the incompletely cured resin to produce a flash or irregularity which projects above the original level of the partially cured resin. Subsequent removal of the masking photoresist and final curing is followed by a second metal deposition. The flash causes metal voids to form which can be enlarged when the second metal layer is etched, causing reliability problems. This technique provides a simple way to eliminate the problem.

Fig. 1 shows a section of a component including a substrate 10, first metal layer 12, partially cured polyimide r...