Study on the Vt Variation of TiN-metal Buried-gate (BG) Cell Transistors in DRAM

The Vt variation of TiN-metal buried-gate (BG) cell transistors in DRAM is characterized. The use of TiN gate shows a large Vt variation and is attributed to the formation of chlorine (Cl)-related trap sites during the etch-back process of the metal gate. This indicates that the Cl component in the chemical vapor deposition (CVD) process of the TiN gate is responsible for such a phenomenon. Reduction of the Vt variation is achieved by rapid thermal annealing (RTA) after the etch-back process. KCI Citation Count: 1