Theodorus Gerardus Maria Oosterlaken

Influence of SiH2 CI 2 on the Kinetics of the Chemical Vapor Deposition of Tungsten by SiH4 Reduction of WF 6

The influence of adding dichlorosilane (SiH 2 Cl 2 ) to the silane (SiH 4 )-based reduction reaction of tungsten hexafluoride (WF 6 ) has been investigated to enhance the properties of this chemical vapor deposition process, especially the control of the growth rate. The growth rate of tungsten by the reduction reaction based on SiH 4 and SiH 2 Cl 2 has been measured. It is shown that the kinetics of the silane-dichiorosilane process can he characterized by a surface reaction limitation. The sole effect of the SiH 2 Cl 2 in the process is blocking of surface sites by preferential absorption, thereby reducing the growth rate of the tungsten film.

The Effect of Doping Atoms on the Kinetics of Self‐Limiting Tungsten Film Growth on Silicon by Reduction of Tungsten Hexafluoride

The reaction of WF 6 with a Si substrate plays an important role in the metallization of Si active areas by tungsten chemical vapor deposition (W-CUD). At typical low pressure W-CUD conditions, this reaction leads to self-limiting growth of a W film. The reaction, which takes place at the film surface, is maintained by Si diffusion through the W film, and stops when the (rapid) supply of silicon becomes rate limiting. Although the mechanism controlling the reduction of WF 6 by intrinsic Si is reasonably understood, little is known about the influence of doping atoms in the Si substrate. In this paper we describe the effect of doping atoms on the growth kinetics of tungsten films deposited by the reaction of WF 6 with highly doped Si at temperatures ranging from 275 to 360 o C. Doping atoms can have a large effect on the self-limiting time of the WF 6 /Si reaction, the self-limiting thickness of the W film, and the rate of the WF 6 /Si reaction. Similar to undoped Si substrates, depositions on As-doped n + Si are controlled by WF 6 gas-phase diffusion and the self-limiting effect occurs earlier than on undoped Si; the W growth rate on N + Si is linear in WF 6 pressure and almost independent of temperature. On B doped p + Si the WF 6 /Si reaction rate is decreased to such an extent that this surface reaction becomes rate limiting, instead of the WF 6 gas-phase diffusion; the W growth rate on p + Si is thermally activated and independent of the WF 6 pressure. The results obtained with the doped Si substrates are discussed in the light of a model for self-limiting W film growth on undoped Si substrates