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Removal of Contamination Reaction Residues from Palladium Films

IP.com Disclosure Number: IPCOM000052164D
Original Publication Date: 1981-May-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Flederbach, D: AUTHOR [+4]

Abstract

An undesirable film is formed as a result of an interaction between a palladium film and contamination introduced on a silicon wafer surface prior to the palladium deposition. The improved process makes it possible to etch the unreacted palladium by breaking the chemical bond between the palladium film and its underlying substrate. The process does not attack the palladium silicide (PdSi(2)) contact to the silicon.

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Removal of Contamination Reaction Residues from Palladium Films

An undesirable film is formed as a result of an interaction between a palladium film and contamination introduced on a silicon wafer surface prior to the palladium deposition. The improved process makes it possible to etch the unreacted palladium by breaking the chemical bond between the palladium film and its underlying substrate. The process does not attack the palladium silicide (PdSi(2)) contact to the silicon.

The improved process is as follows:
1. Palladium contact surface pretreatment is effected by using a 50:1 buffered hydrofluoric acid (BHF) at room temperature for 50 seconds.
2. Palladium deposition is made using the conditions:
a) resistive heated tungsten filament,
b) 450 angstroms to 550 angstroms in 1 to 2 minutes of

palladium evaporation,
c) no substrate heat, and
d) 3 x 10/-6/ torr pumpdown prior to evaporation.
3. The film is sintered at 400 degrees C in forming gas for 20 minutes to form PdSi(2) in contacts.
4. The structure is either (a) etched in 50:1 BHF at room temperature for 20 seconds or (b)etched in HCl solution (10cc of HCl per liter of water to 100cc of HCl per liter of water).
5. Any unreacted palladium which may not have been removed in step
(4) above is now etched away using a standard etchant.
6. The structure is soaked in methanol (CH(3)OH) for 5 minutes to quench wafers subsequent to KI I(2) DIH(2)O etch.

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