Browse Prior Art Database

Silicon ION Beam Extraction Grids

IP.com Disclosure Number: IPCOM000045337D
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Speidell, JL: AUTHOR

Abstract

State of the art extraction grids for ion-beam sources are fabricated from stainless steel sheet graphite and molybdenum. These grids are manufactured by serial mechanical methods which present several disadvantages. For example, large amounts of time are consumed, making the final product expensive. Also, the mechanical machining induces stress into the grids. This stress causes the grids to distort when it is used on an ion source because of the heat generated by the filament and the plasma. Grid distortion causes a non-uniform beam profile which results in nonuniform ion treatment of the substrates.

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Silicon ION Beam Extraction Grids

State of the art extraction grids for ion-beam sources are fabricated from stainless steel sheet graphite and molybdenum. These grids are manufactured by serial mechanical methods which present several disadvantages. For example, large amounts of time are consumed, making the final product expensive. Also, the mechanical machining induces stress into the grids. This stress causes the grids to distort when it is used on an ion source because of the heat generated by the filament and the plasma. Grid distortion causes a non- uniform beam profile which results in nonuniform ion treatment of the substrates.

The present process fabricates silicon ion source grids which are a direct replacement for the current graphite units. The required substrate 10 is a single crystal silicon wafer of (100) orientation and a resistivity of 1 ohm-cm or less. This substrate is then thermally oxidized to form oxide layers 12 and 14 of 0.5 micrometer (Fig. 1). A photoresist layer 16 is then deposited on one side of the substrate, and a pattern which defines the support ring and mounting holes is photolithographically formed in this layer (Fig. 2). This pattern is next transferred into the underlying oxide layer 12 using a suitable wet chemical etchant (Fig. 3).

The photoresist is then removed and placed into an anisotropic silicon etching solution. This solution contains ethylene diamene, pyrazine, pyrocathecol and water. With the patterned oxide layer...