Thermally stable tungsten bit-line process flow for the capacitor over bit-line-type dynamic random-access memory

Thermally stable tungsten (W) bit-line process technology has been successf ully integrated for capacitor over bit-line (COB)-type dynamic random-acces s memory (DRAM). Major parameters of the W bit-line process now are demonst rated to be the Ti thickness, the silicidation temperature and the dopant c oncentration. The minimum contact resistance (<1000 Omega) of the W bit-lin e into the p(+) active region has been obtained by the silicidation of thin Ti (7 nm) at a high temperature (800 degrees C) with the additional ion im plantation of BF2+ after the contact formation. The effects of the process parameters were explained in terms of the agglomeration of the Ti silicide and dopant concentration in the silicon active region.