RF Vacuum Microelectronics
Quarterly technical rept. no. 1, 20 Apr-30 Jun 1992
HUGHES AIRCRAFT CO TORRANCE CA ELECTRON DYNAMICS DIV
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Since this is the first quarterly progress report, a brief review will be given of the basic Hughes process as developed up through 1990 to create FEAs. Uniform pyramidal tips are defined when a 100 Si substrate is etched through a Si3N4 mask using KOH. The width of the opening determines the depth of this self-limiting etch. The result is a crystallographically sharp pyramidal hole formed by the 111 planes. Any desired array pattern of these holes can be formed. These holes are subsequently thermally oxidized to produce a thin oxide etch barrier, and this etched Si wafer then becomes a mold or negative of the desired array of tips. Polysilicon is deposited into the mold and built up to a self-supporting thickness. The mold is then etched away leaving a array of uniform polysilicon tips on a self-supporting polysilicon substrate.
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