| Adhesion and leakage current characteristics of selective CVD W by SiH₄ reduction on the Si substrate have been investigated. Adhesion of the W film on to the Si substrate (damaged by ion implantation) turned out to be very poor. Adhesion property also appears to depend on W film thickness. In the case of the W film with the thickness of 1500Å, adhesion is poor even after removing all the implantation damage from the Si substrate. Two-step deposition process of W film for enhancing adhesion have been investigated. For the two-step deposition process where H₂ reduction is used in the first step and SiH₄ reduction is used in the second step, leakage current due to encroachment phenomena is very high. On the other hand, for the two-step process where SiH₄ reduction is used in the first step and then SiH₄ reduction is used again in the second step but in situ annealing treatment was inserted in between steps, both adhesion and electrical properties of the W film is found to be good, even if the W film thickness was over 5000Å. |
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