Growth Kinetics of Low Pressure Chemically Vapour Deposited Selective Tungsten Films in WF sub 6 --Si and WF sub 6 --H sub 2 Systems

• Published in: Thin solid films Vol. 221; no. 1-2; pp. 191 - 195
• Main Authors: Turtsevich, A S, Krasnitsky, V Y, Granko, V I, Lesnikova, V P, Smal, I V, Sarychev, O E, Nalivaiko, O Y, Kravtsov, S V
• Format: Journal Article
• Language: English
• Published: 10.12.1992
• ISSN: 0040-6090

Characteristic properties of tungsten deposition by silicon and hydrogen reduction of WF sub 6 have been investigated. Apparent activation energy values for these reactions have been determined. It has been established that W growth in the process of WF sub 6 reduction by silicon was self-limiting but the thickness of the W film increased monotonically with deposition temperature. On the basis of scanning electron microscopy, X-ray diffractometry and secondary ion mass spectroscopy results it has been shown that deposited films had a microporous structure with the pores serving as channels for WF sub 6 transportation and reaction product removal. With elevation of the temperature, W film growth was provided not only by WF sub 6 transportation through the growing film pores to the bottom interface but also by opposing Si diffusion to the film surface. In the process of W deposition by H reduction of WF sub 6 , Si reduction of WF sub 6 predominated in the initial stage but then, as pores became closed during the film growth, the subsequent deposition process basically occurred through H reduction of WF sub 6 . Under conditions of considerable excess of H, Si consumption was significantly reduced and, as a result, the lateral encroachment of W in the contact hole region was effectively suppressed.