Browse Prior Art Database

Lift Off Process

IP.com Disclosure Number: IPCOM000081655D
Original Publication Date: 1974-Jul-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Hagmann, D: AUTHOR [+2]

Abstract

To eliminate the problems encountered during the production of a lift-off mask, the areas to be subsequently covered by the desired pattern are exposed only after the lift-off mask is finished.

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Lift Off Process

To eliminate the problems encountered during the production of a lift-off mask, the areas to be subsequently covered by the desired pattern are exposed only after the lift-off mask is finished.

The cross-sectional view in Fig. 1 shows a semiconductor structure at the stage where a contact hole is etched into an isolation structure, consisting of two oxide layers 1 and 3 with an intermediate nitride layer 2, all of which are supported on a semiconductor substrate 4. A thin oxide layer 5 is grown on the semiconductor surface exposed in the contact hole (Fig. 2).

In the next step, lift-off mask 6, consisting of photoresist and corresponding to the desired pattern, is produced (Fig. 3). Contaminations are indicated in the contact hole and on the surface of the isolation structure. Then the structure is subjected to an oxide etch process during which all exposed oxide surfaces are attacked, until the thin oxide layer 5 at the bottom of the contact hole has been removed (Fig. 4).

Along with the oxide the contaminations are eliminated, so that they do not become trapped when metal 7 is evaporated over the full area of the structure. The resulting structure is shown in Fig. 5. Finally, the photoresist pattern 6 is stripped off, while the metal 7 outside the desired pattern is lifted off.

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