Application of Atomic Layer Deposition Tungsten (ALD W) as Gate Filling Metal for 22 nm and Beyond Nodes CMOS Technology

By using two different precursors i.e. SiH4 and B2H6, atomic layer deposition (ALD) Tungsten (W) as gate filling metal for 22 nm and beyond nodes CMOS technology were investigated in this work. In order to evaluate the applications of two kinds of ALD W in real devices, their properties were extensively characterized by means of X-ray Reflectivity (XRR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and electrical capacitance-voltage (C-V) and current-voltage (I-V) methods. It is revealed that the amorphous ALD W using B2H6 and WF6 shows lower growth rate, lower resistivity and better gap filling capability in gate trench of pretty high aspect-ratio, in contrast to the polycrystalline ALD W using SiH4 and WF6. It is further evidenced that the doping of boron (B) in ALD W does not affect the C-V and I-V characteristics of as-prepared capacitors, demonstrating that the ALD W using B2H6 and WF6 is a good gate filling metal which can be widely used in advanced devices.