Browse Prior Art Database

Fast Slow Level Control for Focal Plane Registration

IP.com Disclosure Number: IPCOM000051757D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Admirand, DJ: AUTHOR [+3]

Abstract

A control system permits wafers to be leveled in the focal plane of a projection printing apparatus within 0.5 micron. By providing a slow driver control when the wafer approaches a level condition, the response of the non-contact focal registration (NCFR) is made compatible with the response of the pressure differential switch.

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 100% of the total text.

Page 1 of 2

Fast Slow Level Control for Focal Plane Registration

A control system permits wafers to be leveled in the focal plane of a projection printing apparatus within 0.5 micron. By providing a slow driver control when the wafer approaches a level condition, the response of the non-contact focal registration (NCFR) is made compatible with the response of the pressure differential switch.

The fast-slow driver control is achieved by adding a voltage switching circuit 1 to each of the three driver boards of the NCFR. The circuit monitors the wafer position low sense line 2 and the retract command (CMD) line 3. As the electrical level of low sense line 2 changes from low to high, which occurs when the wafer is near the level condition, the speed of the corresponding driver changes from high to low. The retract CMD signal overrides the low sense so that high speed retract is obtained.

With the reduction of the focal plane registration from 1 micron to 0.5 micron, more uniform resolution is obtained across the wafer.

1

Page 2 of 2

2

[This page contains 2 pictures or other non-text objects]