Browse Prior Art Database

Two Resist Layers Lift Off Process

IP.com Disclosure Number: IPCOM000080364D
Original Publication Date: 1973-Dec-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Bergasse, G: AUTHOR

Abstract

Electron-beam systems for exposing photoresist layers in the course of standard photoengraving steps, are considered to be very valuable tools in the semiconductor industry.

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Two Resist Layers Lift Off Process

Electron-beam systems for exposing photoresist layers in the course of standard photoengraving steps, are considered to be very valuable tools in the semiconductor industry.

After exposition and development, the shape of the openings formed in the hardened photoresist layer is very appropriate in the so-called lift-off technique, to provide good metal interconnection patterns. However, the use of an electron- beam system is rather complex and expensive. Therefore, an alternative is proposed to obtain the same good results, but avoiding the need for implementing such an electron-beam system.

According to the drawings, a silicon substrate 10 which must be provided with an aluminum contact is represented. The process involves the deposition of a thick layer 11 of a photoresist material over the silicon substrate 10. The thickness of layer 11 is typically in the range of 15,000 angstroms (Fig. A).

A thin layer of chromium 12 is then flash deposited over the photoresist layer (Fig. B). According to standard photoengraving techniques, using an additive photoresist layer 13, an opening is made in the chromium layer 12 to expose the underlying initial photoresist layer 11, as represented in Fig. C.

To obtain an opening in the initial photoresist layer 11 similarly shaped to the one provided by the electron-beam system, it is important to expose this layer with a variable angle incident light beam exposing device like a rotating prism. A...