# US 6,243,487 B1 · Pattern exposure method using electron beam

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- Number: US 6,243,487 B1
- Document ID: US6243487B1
- Status: Granted
- Kind: B1
- Application number: 09/050,355
- Filed: 1998-03-31
- Granted: 2001-06-05
- Earliest claimed: 1997-03-31
- Assignees: NEC Corporation
- Inventors: Ken Nakajima
- Web page: https://patentgrep.com/patent/US6243487B1

## CPC

- H01J 37/3174: {Particle-beam lithography, e.g. electron beam lithography}
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- B82Y 40/00: Manufacture or treatment of nanostructures
- H01J 2237/31771: using multiple exposure
- Y10S 430/133: Binder-free emulsion
- Y10S 430/143: Electron beam
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

Disclosed is a pattern exposure method for conducting an overlay exposure to a base pattern previously formed by using electron beam, which has the steps of: 1) dividing a group of patterns formed on the base pattern into arbitrary regions; 2) calculating an area density of the base pattern in each of the arbitrary regions; 3) generating a pattern according to the area density; 4) conducting sub-exposure using the pattern; and 5) conducting main exposure to expose a desired pattern.

## Claims

### Claim 1

A pattern exposure method for conducting an overlay exposure to a base pattern previously formed by using an electron beam, comprising the steps of:
1) dividing a group of patterns formed on said base pattern into arbitrary size regions;
2) calculating an area density of said base pattern in each of said arbitrary size regions;
3) generating a first pattern according to said area density of said base pattern in each of said arbitrary size regions;
4) conducting sub-exposure using said first pattern; and
5) conducting main exposure using a second pattern to expose a desired pattern,
wherein exposure quantity is set by subtracting an exposure quantity of energy intensity accumulated by said sub-exposure from the optimum exposure quanity of the second pattern.

### Claim 2 (depends on 1)

A pattern exposure method according to claim 1, wherein: in step 2) for calculating an area density of said base pattern in each of said arbitrary regions, area densities of a plurality of base patterns previously formed are calculated to make an area density map of each of said base patterns previously formed.

### Claim 3 (depends on 1)

A pattern exposure method, according to claim 1, wherein:
in step 3) for generating a first pattern according to said area density, a rectangular pattern according of said area density to each of said divided regions is disposed at the center of each of said divided regions to make a group of patterns for sub-exposure.

### Claim 4 (depends on 3)

A pattern exposure method, according to claim 3, wherein:
said rectangular pattern disposed in said group of patterns for sub-exposure is exposed with a same exposure quantity depending on a kind of film to form said base pattern.

### Claim 5 (depends on 1)

A pattern exposure method, according to claim 1, wherein:
in step 3) for generating a first pattern according to said area density, a rectangular pattern with an arbitrary same size to each of said divided regions is disposed at the center of each of said divided regions to make a group of patterns for sub-exposure.

### Claim 6 (depends on 5)

A pattern exposure method, according to claim 5, wherein:
said rectangular pattern disposed in said group of patterns for sub-exposure is exposed with an optimum exposure quantity depending on the area density of each of said divided regions.

### Claim 7 (depends on 1)

A pattern exposure method, according to claim 1, wherein:
in step 5) for conducting main exposure to expose a desired pattern, the main exposure is conducted subtracting an exposure quantity depending on the base structure and the exposure quantity of sub-exposure.

### Claim 8 (depends on 1)

A pattern exposure method according to claim 1 wherein said steps 1), 2), 3) and 4) are repeated N times for N base patterns previously formed, and wherein N is an integer greater than or equal to 2.