Method for producing integrated MOS field effect transistors with an additional track level of metal silicides

Claim 1

In a method of producing integrated MOS field effect transistors, particularly complementary MOS field effect transistor circuits (CMOS-FET's) wherein a metal layer structure consisting of a metal silicide having a high melting point, comprising a silicide of molybdenum, tungsten, tantalum or titanium, is utilized as an additional interconnect, with the metal silicide layer being applied after the fabrication of the polysilicon level, the forming of active MOS regions, the application of an insulating oxide and the opening of contact holes, and phosphorous glass layer is utilized as an intermediate oxide between the metal silicide level and the metal interconnect, wherein the improvement comprises: substantially simultaneously opening, in one method step, contact areas to the active MOS and polysilicon regions for the metal silicide level as well as for the metal interconnect after the application of the insulating oxide and before the application of the metal silicide level; and structuring the metal silicide level in such a manner that during a flow-spread of the phosphorous glass layer functioning as an intermediate oxide, the p + regions of the circuit remain covered by the metal silicide level.