New technique for forming continuous, smooth, and uniform ultrathin (3 nm)PtSi layers

An interfacial intermixed Pt-Si layer formed during Pt sputtering at room t emperature, and a subsequent selective etch step are found to be the keys f or formation of continuous and uniform ultrathin PtSi layers. The etching, performed after the metal deposition, removes Pt at very fast rates. The et ch rate is slowed when the Pt- Si interfacial layer is reached and an oxide is formed on top of the intermixed Pt-Si layer, which prevents further etc hing. During this process, a short- range diffusion mechanism is believed t o transform the intermixed Pt-Si layer into a 3 nm thick continuous PtSi fi lm. A subsequent annealing results in a more uniform grain size distributio n, without changing the other characteristics of the film. Moreover, the si licide formed is insensitive to sputter conditions such as sputter power an d time. (C) 1999 The Electrochemical Society. S1099- 0062( 98) 10- 119- 0. All rights reserved.