Browse Prior Art Database

Strategy for High Throughput, High Resolution Electron Beam Lithography

IP.com Disclosure Number: IPCOM000105574D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 98K

Publishing Venue

IBM

Related People

Brand, JL: AUTHOR

Abstract

Described is a strategy for high throughput, high resolution electron beam lithography. The strategy uses an array of individually microfabricated electron beam sources on a source wafer. A target wafer is raster-stepped across the source array. Each electron beam source is fired at the correct time in order to expose a pixel on the target wafer. This strategy achieves the high throughput with the large number of independent electron sources operating in parallel. The high resolution is achieved due to the nature of the microfabricated field emission sources and the integral lens system.

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Strategy for High Throughput, High Resolution Electron Beam Lithography

      Described is a strategy for high throughput, high resolution
electron beam lithography.  The strategy uses an array of
individually microfabricated electron beam sources on a source wafer.
A target wafer is raster-stepped across the source array.  Each
electron beam source is fired at the correct time in order to expose
a pixel on the target wafer.  This strategy achieves the high
throughput with the large number of independent electron sources
operating in parallel.  The high resolution is achieved due to the
nature of the microfabricated field emission sources and the integral
lens system.

Electron beam lithography is traditionally performed in two ways.
The first method uses a single electron beam source which can be
focused electrostatically to very small dimensions.  Writing on a
wafer is performed by rastering the electron beam across the wafer.
This approach to e-beam lithography permits lines to be written with
small dimensions, but it suffers from very slow throughput.

The second approach is to use a contacting or nearly contacting mask
placed on the wafer.  A large electron source floods the mask with
electrons.  Only the regions of the wafer under the voids in the mask
get exposed to the electrons.  This method works well for high volume
applications.  However, the dimensions are limited to the size of the
voids in the mask.  Current technology allows masks with only about 1
micron linewidths.  There are also a number of problems with mask
cleanliness, fragility, and charging.

Electron beam lithography for chip production suffers from either low
throughput or relatively large linewidths.  Electron beam strategies
need to be developed which solve the problems of throughput and
resolution.  This disclosure describes a strategy for combining known
technologies to achieve high throughput, high resolution electron
beam lithography.

In order to improve the throughput of electron beam lithography, many
individual electron beams can be employed.  Each electron beam,
focused to a small spot, can be individually controlled.  The
combination of a large number of electron beams and small spot sizes
achieves the high throughput, high resolution lithography.

An array of microfabricated electron beam sources are produced on a
"source" wafer.  Each electron beam source can be individually turned
on and off.  Each electron beam source has its focus the same
distance from the source wafer.  A target wafer with photoresist is
placed the focal length away from the source wafer.  If all of the
electron beam sources on the source wafer were turned on at the same
time, the target wafer would then have an array of small spots
exposed in the photoresist.  In a processing mode, the target wafer
(or the source wafer) would be translated in front of the source
wafer maintaining the focal length distancing between the tw...