Work function stability of thermal ALD Ta(Si)N gate electrodes on HfO/sub 2/ [CMOS device applications]

Ta(Si)N films deposited by thermal atomic layer deposition (ALD) have been investigated as potential gate electrode materials in advanced CMOS devices. The work function (/spl Phi//sub m/) of these films was determined by high-frequency capacitance-voltage measurements (HF-CV) on a thickness series of ALD HfO/sub 2/. Depositing films at 400 and 500/spl deg/C with an optimized pulse sequence, two films with Si content of 3 and 8 at%, respectively, were studied. Both Ta(Si)N films gave /spl Phi//sub m/ of 4.7/spl plusmn/0.1 eV, also, after high-temperature thermal treatment, with the 400/spl deg/C deposition giving more reliable electrical performance.