Browse Prior Art Database

Exposure Field Alignment System

IP.com Disclosure Number: IPCOM000038786D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Babinski, JP: AUTHOR [+2]

Abstract

Advantage is taken of beneficial features of both broadband illumination microscope alignment and of exposure wavelength, through-the-lens alignment to achieve accurate alignment of exposure fields independent of process variations. As shown in the figure, two reference markers L and R, which provide high contrast images in both single wavelength (exposure wavelength) and broadband illumination alignment detection systems, are made a part of wafer chuck 2. Wafer chuck 2, containing wafer-notch locating pin 4 and wafer-edge locating pin 6, is mounted on an X-Y- theta table in a wafer exposure system. An in-process wafer 8 is placed on wafer chuck 2, as shown, for a next level alignment and exposure.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 69% of the total text.

Page 1 of 2

Exposure Field Alignment System

Advantage is taken of beneficial features of both broadband illumination microscope alignment and of exposure wavelength, through-the-lens alignment to achieve accurate alignment of exposure fields independent of process variations. As shown in the figure, two reference markers L and R, which provide high contrast images in both single wavelength (exposure wavelength) and broadband illumination alignment detection systems, are made a part of wafer chuck 2. Wafer chuck 2, containing wafer-notch locating pin 4 and wafer-edge locating pin 6, is mounted on an X-Y- theta table in a wafer exposure system. An in-process wafer 8 is placed on wafer chuck 2, as shown, for a next level alignment and exposure. A broadband illumination microscope system is used to determine the location of a left alignment mark in each exposure field on the wafer 8 relative to chuck reference marker L in either Cartesian or polar coordinates. This data is fed to a computer and is used to first calculate difference in present wafer or chip position (X, Y, and theta) relative to a design wafer or chip position to which chuck alignment marks L and R are referenced. A through-the-lens, exposure wavelength alignment system, also incorporated in the aligner, is next used to align on reference marker L to minimize lens errors and establish initial position. The previously calculated theta correction is applied, and calculated motion to a best overlay position of a fir...