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Browse Prior Art Database

Registration to Field Writing Correlation in E Beam System

IP.com Disclosure Number: IPCOM000088044D
Original Publication Date: 1977-Apr-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 3 page(s) / 38K

Publishing Venue

IBM

Related People

Michail, MS: AUTHOR [+2]

Abstract

In the microfabrication of semiconductor devices or masks, it is essential to accurately control an electron (E) beam. As described in U. S. Patent 3,644,700, various factors result in differences between the ideal registration and writing fields and the actual fields.

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Registration to Field Writing Correlation in E Beam System

In the microfabrication of semiconductor devices or masks, it is essential to accurately control an electron (E) beam. As described in U. S. Patent 3,644,700, various factors result in differences between the ideal registration and writing fields and the actual fields.

It is noted that in addition to determining differences between ideal and actual registration mark locations and ideal and actual writing field locations, it is necessary to correlate the two sets of errors. Differences between the registration and writing field location errors are caused by a difference in the deflections, different circuits, and different deflection speeds. It is, therefore necessary to relate the beam position and speed during scanning to locate the registration marks to the position the beam will have at any point during field writing. The need for this correlation procedure is essentially independent of the method employed for registration or writing. In order to achieve accurate overlay, this correlation procedure should be very accurate so it contributes minimum error to the overlay accuracy.

Referring to the drawing, a calibration grid 8 with marks is placed in the target area and scanned by an E-beam. The back scattered electrons are detected and transmitted by means of a feedback circuit 10 to a computer. The computer performs a number of major functions, as symbolized by the internal block diagram. Means 12 are provided for collecting the registration and writing deflection data. Means 14 are provided for editing and filtering the data. Means 16 are provided for generating the differences between registration and writing fields. Means 18 are provided for updating the deflection control commands to compensate for the differences between the registration and writing fields.

The computer output is provided to a digital control unit (DCU) which includes a control memory 20 for storing deflection commands, circuitry...