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Producing Alloy Contacts on Nonsemiconductor Bodies

IP.com Disclosure Number: IPCOM000092705D
Original Publication Date: 1967-Feb-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 78K

Publishing Venue

IBM

Related People

Wustenhagen, J: AUTHOR

Abstract

This method provides ohmic alloy contacts at closely spaced N and P regions on the same surface of semiconductor bodies. The N and P-type regions are contacted with different appropriately doped metals. The latter alloy with the semiconductor material at different eutectic temperatures and alloy with each other only above the lower of these two temperatures. The metal alloying at the higher temperature is first deposited and alloyed with the contact area of one conductivity type. Then an undoped layer of the same material is evaporated at the eutectic temperature of the other material. The second metal appropriately doped is then deposited and alloyed to the contact area of the other conductivity type.

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Producing Alloy Contacts on Nonsemiconductor Bodies

This method provides ohmic alloy contacts at closely spaced N and P regions on the same surface of semiconductor bodies. The N and P-type regions are contacted with different appropriately doped metals. The latter alloy with the semiconductor material at different eutectic temperatures and alloy with each other only above the lower of these two temperatures. The metal alloying at the higher temperature is first deposited and alloyed with the contact area of one conductivity type. Then an undoped layer of the same material is evaporated at the eutectic temperature of the other material. The second metal appropriately doped is then deposited and alloyed to the contact area of the other conductivity type.

The steps of the method shown in A and B are performed on GaAs wafer 1 in which a P region 2 and an N region 3 are formed. The upper surface of the body is initially covered with layer 5 of SiO(2). Then the following steps are performed.
a) 13y evaporation and etching, Cr layers are formed in the contact strip patter 6 and 7. b) Aperture 8 is etched for the base contact. c) Layer 9 of Ag+2%Mg is evaporated and the base contact 10 if formed by alloying at 620 degrees C. d) Undoped Ag layer 11 is evaporated at 450 degrees C. e) Aperture 12 for the emitter is etched. f) Layer 13 of Au+ 2%Te is evaporated and the emitter contact 12 is alloyed at 450 degrees C. g) Au layer 15 is evaporated at 300 degrees C. h) The cont...