Thermal budgeting in a double level metal process with CVD tungsten as first metal

The high-temperature stability of CVD tungsten (W) interconnects over TiSi/sub 2/-clad diffusions was tested up to 700 degrees C. A sputtered 10 wt.% Ti in W sticking layer was used to nucleate the W. Contact resistance was stable at the highest temperatures, and measured to be <0.01 mu ohm/cm/sup 2/. Junction leakage decreased from approximately 50 na/cm/sup 2/ to <5 na/cm/sup 2/ on 700 degrees C annealing of both p/sup +//n/sup -/ and n/sup +//p/sup -/ diodes. Apart from the expected benefits from CVD blanket W of excellent contact filling and high reliability, it is concluded that the results show an opportunity for higher temperature post-metal processing than can be realized for Al alloys when used with the TiSi/sub 2/ transistor cladding process. The results obtained point to the possibility of higher temperature oxide depositions than are now allowed following metal processing, to enhance the conformality of the interlevel insulators and reduce the tendency for void formation.<>