Browse Prior Art Database

Electron Beam Registration

IP.com Disclosure Number: IPCOM000092427D
Original Publication Date: 1966-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Hatzakis, M: AUTHOR

Abstract

In the fabrication of microcircuits of limited field size, i.e, 5-10 thousandths of an inch, via electron beam exposure of resists, it is imperative to obtain accurate registration of the beam on a point outside the field prior to exposure. This registration point is also used for the subsequent stages of fabrication. It should be able to withstand all the processes involved in the fabrication such as etching, heating, diffusion, etc.

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Electron Beam Registration

In the fabrication of microcircuits of limited field size, i.e, 5-10 thousandths of an inch, via electron beam exposure of resists, it is imperative to obtain accurate registration of the beam on a point outside the field prior to exposure. This registration point is also used for the subsequent stages of fabrication. It should be able to withstand all the processes involved in the fabrication such as etching, heating, diffusion, etc.

Present registration points consist of an 8 x 8 microns square etched through the silicon dioxide. This, when scanned with the beam, provides a secondary electron image or signal that can be used for registering the beam. The signal- to-noise ratio obtained with this method is very small and unsatisfactory for automatic or manual registration.

This method consists of using a metallic square as a registration mark deposited on top of the silicon dioxide prior to coating with resist. The metal deposition can be achieved by evaporating a suitable metal over the entire wafer surface. Then, through the use of a standard resist, the required registration squares are etched. Metals with high atomic number and high melting point are suitable for both resistance to the processes involved during fabrication and high output signal. Silver squares approximately 0.3 microns thick on silicon dioxide result in an increase of about ten times the signal-to-noise ratio obtained by a cut on the silicon dioxide.

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