Development of Polycide Application and Control of Process Conditions on DCS Based WSix

Abstract

ABSTRACTDichlorosilane based CVD WSix is deposited by the reaction of tungsten fluoride (WF6) and dichlorosilane (SiH2Cl2; DCS). The reaction is thermodynamically favorable and results in WSix film with less fluorine (F) concentration than monosilane (SiH4; MS) based WSix. DCS based WSix shows less expansion of gate oxide and better step coverage than monosilane based WSix. Due to its DCS based stable film stoichiometry, WSix has low resistivity and therefore has been widely applied in ULSI memory devices. However, DCS is a source of chlorine, which is a major impurity. This means special considerations have to be made when using DCS based WSix in comparison with MS based WSix. This work provides evaluation and control of chlorine behaviors in DCS based WSix film.