Effect of selective tungsten contact fills on manufacturing issues

Abstract

Summary form only given. The selective deposition of CVD tungsten has been extensively studied as a promising technique for filling contacts and vias in semiconductor devices. The immediate need to apply this technology to devices with submicron contacts and vias requires that consideration be given to defect density, probe yield, process yield, and manufacturability. In addition, process control reliability must also be addressed. The authors show the yield effect of selective tungsten deposition as compared to a standard process flow. The 256 K DRAM was chosen as the test vehicle for the study. The most strongly affected electrical parameters were the contact resistances. In some cases degradation was bad enough to cause continuity failure in the functional tests. Across-wafer uniformities and failure analysis results for the different processes are also reported.<>