Browse Prior Art Database

New Projection System for Optical Lithography Systems

IP.com Disclosure Number: IPCOM000016044D
Original Publication Date: 2002-Aug-25
Included in the Prior Art Database: 2003-Jun-21
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Abstract

Currently all Lithography machines (Steppers, Mask aligners) are working with a Mask, a Projection System transfers the image of the Mask onto the wafer.

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New Projection System for Optical Lithography Systems

Currently all Lithography machines (Steppers, Mask aligners) are working with a Mask, a Projection System transfers the image of the Mask onto the wafer.

The mask contains the image which is desired on the wafer. To project the image onto the wafer in the desired position an alignment of the wafer is necessary:
1. The Stepper is searching for alignment marks on the wafer
2. If the alignment marks are found, the wafer is moved the desired position which has to be very precise (alignment step).
3. In the exposure step the image of the mask is transferred onto the photoresist on the wafer.

The disadvantage of these systems are:
1. Every new structure or modification of the currently used structure results in the fabrication of a new mask which is expensive
2. The alignment needs a very precise mechanical movement which is very expensive

The new idea is that instead using a mask, to use a high resolution CCD Chip and or other pixel arrays which are used e.g. in projection beamers. The basic technique should work as follows:

1. The wafer is moved into the stepper/aligner and is aligned roughly. The whole area on the wafer which will be exposed is photographed (e.g. with a high resolution ccd camera).
2. The image is then processed in a computer where the actual position and or defects and possible different positions of the wafer is determined.
3. Instead of a reticule, a kind of projection chip (lcd or mirror arrays)...