Effect of TiCl/sub 4/ pre-treatment in PECVD-Ti process for sub-0.2 /spl mu/m metal bit line contacts

Abstract

The effect of the initial steps in PECVD-Ti process is investigated for the optimization of TiSi/sub x/ formation. A remarkable difference in TiSi/sub x/ formation is observed between pre-plasma and pre-TiCl/sub 4/ treatment in which the initial steps start with H/sub 2/ gas with plasma and TiCl/sub 4/ gas without plasma. TiCl/sub 4/ pre-treatment in the PECVD-Ti process is compared with H/sub 2/ plasma pre-treatment especially for low aspect ratio contacts. PECVD-Ti films with H/sub 2/ plasma pre-treatment results in accumulation of Cl impurities at the interface between Si and TiSi/sub x/, and subsequently results in thinner TiSi/sub x/ and higher contact resistance. With the optimized TiCl/sub 4/ pretreatment, excellent electrical characteristics are obtained in sub-0.2 /spl mu/m bit line contacts.