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Method for Forming Palladium Silicon Contacts and Electrodes on Silicon Semiconductor Devices

IP.com Disclosure Number: IPCOM000051960D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Anantha, NG: AUTHOR [+3]

Abstract

Hydrogen gas has the ability to reduce silica (SiO(2)) in the presence palladium (pd) at temperatures of about 725 degrees C. This action is exploited in producing thin SiO(2) layers of different thicknesses and in making ohmic and Schottky contact to silicon surfaces through different thicknesses of intervening SiO(2).

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Method for Forming Palladium Silicon Contacts and Electrodes on Silicon Semiconductor Devices

Hydrogen gas has the ability to reduce silica (SiO(2)) in the presence palladium (pd) at temperatures of about 725 degrees C. This action is exploited in producing thin SiO(2) layers of different thicknesses and in making ohmic and Schottky contact to silicon surfaces through different thicknesses of intervening SiO(2).

Two different oxide thicknesses are required in the fabrication of C:CD (charge control device) memory devices. This is achieved by covering a silicon wafer with 1000 angstroms of SiO(2), as shown in Fig. 1, and then selectively placing Pd over the areas of the oxide where reduced oxide thickness is desired. The resulting structure is heated in an H(2) atmosphere at about 725 degrees C. Pd Si is formed, and the oxide is thinned because of the reduction of SiO(2) by atomic hydrogen in the areas originally covered by Pd. Palladium has the ability to dissolve appreciable amounts of H(2) as elemental hydrogen (H) to supply the latter to the Pd-Si interface, causing the SiO(2) to be reduced to Si at temperatures as low as 725 degrees C.

The same reduction action is used in making ohmic and Schottky contacts to the structure shown in Fig. 3. About 2000 angstroms of Pd is deposited directly on the emitter surface 1, on the 1600 angstroms of SiO(2) covering the base area 2 and the 800 angstroms SiO(2) covering the collector are 3. After heat treatment in H(2) at...