Application of electron beam lithography to replace photolithography process in fabrication of integrated circuits is discussed. Procedure for using electron beam lithography equipment is described. Diagram of electron micropattern generator is provided

Malmberg, P. R.

Okeeffe, T. W.

English

NASA Technical Reports Server

October 1972	 B72-10646 
NASA TECH BRIEF 
Marshall Space Flight Center 
NASA Tech Briefs announce now technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Dual Field Alignment Display and Control for
Electron Micropattern Generator 
.
The photolithography process used in the fabrication 
of integrated circuits may soon be replaced by electron 
beam lithography. Two principal electron beam systems 
used in the new process will be the electron micropattern 
generator for generating device patterns and the electron 
image projection system for reproducing these patterns. 
The electron micropattern generator (EMG) is an adapta-
tion of a scanning electron microscope to digital or 
computer control to generate the patterns. 
Planar devices such as integrated circuits require 
successive patterns to be precisely positioned with refer-
ence to each other. Thus, adequate registration is of prime 
importance when generating or duplicating the patterns. A 
method has been developed to align an electron micro-
pattern generator that is used to write device patterns at 
final scale with a computer controlled electron beam. In 
this method two digitally prescribed index addresses for
the pattern are aligned with a pre-existing index or with 
fiducial feature on the target substrate. An alignment 
oscilloscope simultaneously displays the index on the 
target and the alignment index. Pattern position, rotation, 
and size are adjusted electronically so that accurate 
registration is obtained. Figure 1 is a block diagram of the 
display system, and Figure 2 illustrates how the indexes 
are used to align the patterns. This adjustment is greatly 
facilitated by the simultaneous display of both alignment 
areas. 
Completely automatic alignment is required for un-
attended electron micropattern generator operation; how-
ever, the manual method requires less hardware ana is 
useful for both limited pattern production during device 
and process development studies and as an independent 
check on alignment quality when using an automatic 
method. The alignment is automated by the substitution 
Video 
Subraster 
Align	
J	
a
	
fiAmP1ifieifier Generator
X z 
LX,zY 
Rotation	
Attenuator I 
Position	 Scale 
	
Subraster 
Size 
Digital Control	 X V 
and DIA Interface
V 
Alignment	
SEM I Scope
 Column 
Deflection 
Amplifiers
Output 
Figure 1. EMG Pattern Alignment Display System
(continued overleaf) 
This document was prepared underthe sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19720000645 2020-03-17T03:41:26+00:00Z
(A.)	 Misaligned	 (B.)	 Aligned in
	 (C.)	 Aligned in 
Rotation and Scale
	
	 X-Y Position, 
Rotation and Scale 
Figure 2. Pattern Alignment Scope Presentation 
of alignment error-controlled, up-down counters coupled 
to digital/analog converters for the position-rotation-size 
controls currently used. 
Notes: 
1. Information concerning this innovation may be of 
interest to manufacturers of solid state devices such as 
integrated circuits, high frequency transistors, and high 
density memory arrays. 
2. Requests for further information may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Code A&PS-TU 
Marshall Space Flight Center, Alabama 35812 
Reference: B72-10646
Patent status: 
Inquiries concerning rights for the commercial use of 
this invention should be addressed to: 
Patent Counsel 
Marshall Space Flight Center 
Code A&PS-PAT 
Marshall Space Flight Center, Alabama 35812 
Source: P. R. Malmberg and T. W. O'Keeffe of

Westinghouse Electric Corporation

under contract to

Marshall Space Flight Center

(MFS-221 18) 
B72-10646	 Category 01, 02


Dual field alignment display and control for electron micropattern generator

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