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Technique for Selectively Removing Geometries From a Lithographically Defined Pattern Using a Modified Image Reversal Process

IP.com Disclosure Number: IPCOM000037133D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Tornello, JA: AUTHOR

Abstract

Disclosed is a process for subtracting geometries defined by one lithography mask from another lithography mask, where the two intersect using a modified Image Reversal Process (IRP).

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Technique for Selectively Removing Geometries From a Lithographically Defined Pattern Using a Modified Image Reversal Process

Disclosed is a process for subtracting geometries defined by one lithography mask from another lithography mask, where the two intersect using a modified Image Reversal Process (IRP).

The IRP permits the use of a positive photoresist with a negative mask.

The modified IRP involves doping a positive resist with a material to thermally degrade the dissolution enhancer. The modified IRP photoresist forms a substitute after exposure and bake. The substitute acts as a dissolution inhibitor to become insoluble in developer.

This is the area defined by the first dark field lithography mask. The photoresist is then exposed using the second dark field lithography mask, causing previously unexposed regions to become soluble in developer.

(Image Omitted)

The modified

IRP is described in the following steps: 1. Prepare the Image Reversal Photoresist by doping

the positive photoresist.

2. Prepare the wafers to promote adhesion.

3. Coat wafers with primer.

4. Coat wafers with Image Reversal Photoresist.

5. Pre-expose bake.

6. Expose first dark field mask (Fig. 1).

7. Hard bake wafers (Fig. 2).

8. Expose second dark field mask (Fig. 3).

9. Develop wafers. Rinse and dry wafers (Fig. 4).

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