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Rework Process of Cured Polyimide

IP.com Disclosure Number: IPCOM000052152D
Original Publication Date: 1981-May-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Couyras, JP: AUTHOR [+4]

Abstract

Polyimide is used as an insulating layer on certain integrated circuit devices. The polyimide is applied by spinning it onto the device structure, baked to remove solvents, and then pattern defined by photolithographic techniques. The polyimide is then cured in a two-step bake process. If problems are observed in the polyimide layer before the first bake of the cure, the polyimide can be removed by dissolution and a new layer applied without harming the functionality of the integrated circuit chips. If the problem is not discovered until after the first or second bake step, the polyimide is in a cured state and cannot be readily removed up until that time without harming the substrate layers below.

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Rework Process of Cured Polyimide

Polyimide is used as an insulating layer on certain integrated circuit devices. The polyimide is applied by spinning it onto the device structure, baked to remove solvents, and then pattern defined by photolithographic techniques. The polyimide is then cured in a two-step bake process. If problems are observed in the polyimide layer before the first bake of the cure, the polyimide can be removed by dissolution and a new layer applied without harming the functionality of the integrated circuit chips. If the problem is not discovered until after the first or second bake step, the polyimide is in a cured state and cannot be readily removed up until that time without harming the substrate layers below.

One example of a method of removing the polyimide in the cured state without harming the substrate is as follows:
1) Subject the cured (after either the first or second bake step) polyimide to an oxygen plasma for ashing under the following conditions: 500 watts RF power

200 cc O(2) flow

45 min. time.
2) After the wafer is ashed, it is cleaned by dipping in:

a) .29M KOH for 1 sec.,

b) 5 min. in deionized water,

c) 5 min. in 0.5% acetic acid, and

d) 5 min. in deionized water and dry.
3) The wafer can now be recoated with polyimide.

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