Salil Mujumdar

Atomic layer deposition of HfxAlyCz as a work function material in metal gate MOS devices

As advanced silicon semiconductor devices are transitioning from planar to 3D structures, new materials and processes are needed to control the device characteristics. Atomic layer deposition (ALD) of HfxAlyCz films using hafnium chloride and trimethylaluminum precursors was combined with postdeposition anneals and ALD liners to control the device characteristics in high-k metal-gate devices. Combinatorial process methods and technologies were employed for rapid electrical and materials characterization of various materials stacks. The effective work function in metal–oxide–semiconductor capacitor devices with the HfxAlyCz layer coupled with an ALD HfO2 dielectric was quantified to be mid-gap at ∼4.6 eV. Thus, HfxAlyCz is a promising metal gate work function material that allows for the tuning of device threshold voltages (Vth) for anticipated multi-Vth integrated circuit devices.

Impact of thermal treatments on the schottky barrier height reduction at the Ti-TiO x -Si interface for contact resistance reduction

Metal-Insulator-Semiconductor (MIS) Schottky diodes were fabricated to study Fermi level unpinning by use of a thin TiO_x insulator. For Ti-TiO_x-n-Si junctions, the Schottky barrier height (SBH) was pinned due to O diffusion from TiO_x into Ti during thermal anneals, as observed from XPS depth profiles. A thin AlO_x barrier inserted between the Ti and the TiO_x prevented O diffusion from TiO_x into Ti, allowing SBH unpinning to be maintained after 450 °C anneals.