Browse Prior Art Database

Aqueous-Base Developable, Three-Component Resist Systems for Thick Resist Applications

IP.com Disclosure Number: IPCOM000036459D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Ito, H: AUTHOR [+2]

Abstract

In thick resist imaging with the use of photoresist systems consisting of a novolac resin and diazoquinone, the concentration of the photoactive compound must be reduced to allow penetration of the exposing UV light through the thick resist film for proper imaging. Since the photo-active compound functions as a dissolution inhibitor of the novolac matrix, the reduction of the diazoquinone concentration to decrease the UV absorption results in decreased sensitivity and increased dissolution rates of the unexposed areas. In consequence, when the resist film becomes very thick, a scheme that increases the resist contrast may have to be incorporated in the process, which further reduces the resist sensitivity.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 1

Aqueous-Base Developable, Three-Component Resist Systems for Thick Resist Applications

In thick resist imaging with the use of photoresist systems consisting of a novolac resin and diazoquinone, the concentration of the photoactive compound must be reduced to allow penetration of the exposing UV light through the thick resist film for proper imaging. Since the photo-active compound functions as a dissolution inhibitor of the novolac matrix, the reduction of the diazoquinone concentration to decrease the UV absorption results in decreased sensitivity and increased dissolution rates of the unexposed areas.

In consequence, when the resist film becomes very thick, a scheme that increases the resist contrast may have to be incorporated in the process, which further reduces the resist sensitivity.

The above-mentioned dichotomy arises from the dual role the diazoquinone must play in the two-component design; dissolution inhibition and photosensitivity. The two functions can be separated in three-component resist systems. Polyphthalaldehyde (PPA), absorbing only below 300 nm, efficiently inhibits dissolution of a novolac resin in aqueous base but does not participate in the initial photochemistry. "Onium salt" cationic photoinitiators absorb UV light and generate strong acids that catalytically depolymerize the dissolution inhibiting PPA. Although triphenylsulfonium and diphenyliodonium salts are good dissolution inhibitors, red-shifted sulfonium salts such as 4- thiopheno...