Browse Prior Art Database

Formation of a Complementary Resist Image

IP.com Disclosure Number: IPCOM000060714D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Kaufman, FB: AUTHOR [+2]

Abstract

A method is described whereby a delineated resist pattern is replaced by a complementary resist pattern having different resist properties. A first resist layer having optimum imaging characteristics is deposited, imaged, developed and then covered with a second resist layer having optimum processing characteristics, such as good thermal stability, dry etch resistance, adhesion, etc. The upper portion of the two layer resist structure is then removed by chemical or mechanical polishing until the first resist pattern is once again uncovered. The first resist pattern is then selectively removed to leave a complementary pattern composed of the second resist material. For integrated circuit fabrication, a resist that is easy to image may not possess other desirable processing characteristics.

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Formation of a Complementary Resist Image

A method is described whereby a delineated resist pattern is replaced by a complementary resist pattern having different resist properties. A first resist layer having optimum imaging characteristics is deposited, imaged, developed and then covered with a second resist layer having optimum processing characteristics, such as good thermal stability, dry etch resistance, adhesion, etc. The upper portion of the two layer resist structure is then removed by chemical or mechanical polishing until the first resist pattern is once again uncovered. The first resist pattern is then selectively removed to leave a complementary pattern composed of the second resist material. For integrated circuit fabrication, a resist that is easy to image may not possess other desirable processing characteristics. For example, PMMA is a good resist for deep-UV, E-beam, X-ray, and ion-beam exposures. High-aspect ratio images can be delineated. However, its flow temperature at about 110OEC is too low for many ion implant, sputter cleaning, reactive ion etching, or high temperature evaporation applications. The dry etch resistance of PMMA is often lower than many other resists. To wet etch certain materials, such as SiO2, the adhesion of PMMA is marginal. In addition, a large exposure dosage is required to achieve a high-aspect-ratio profile. Other PMMA copolymers and terpolymers show similar problems. It is the purpose of the disclosed method to circumvent these problems by replacing a delineated resist image with its complementary image formed with a material of desirable pattern transfer characteristics so that the pattern transfer tool sees only the pattern formed by the new material, whereas the imaging tool only sees the original imaging material. The procedure is illustrated in Fig. 1. A resist image is first delineated in a good imaging resist such as PMMA using known techniques, such as single layer im...