Seong Min Hwang

A high performance deep submicron MOSFET structure with self-aligned selectively grown W-gate (SAW)

A novel structure for high performance deep submicron MOSFETs, which is called the SAW (Self-Aligned selectively grown W-gate) MOSFET, is proposed. The SAW MOSFET structure has extremely low gate resistance due to the use of tungsten as gate electrode and low source/drain junction capacitance due to the threshold voltage adjustment implantation into the channel region only. In order to get a steep subthreshold slope, moderate threshold voltage, and high saturation current, a retrograde shaped channel profile is also used.

Dependence of deep submicron CMOSFET characteristics on shallow source/drain junction depth

With the MOSES (Mask Oxide Sidewall Etch Scheme) process which uses a conventional i-line stepper and isotropic wet etching, CMOSFETs with fine gate patterns of 0.1 /spl mu/m or less are fabricated and characterized successfully. To improve the short channel effect of 0.1 /spl mu/m CMOS devices, the screening oxide is deposited before the low energy ion implantation for source/drain extensions and a two step sidewall scheme is adopted. Through the characterization of 0.1 /spl mu/m CMOS devices, it is found that the screening oxide deposition scheme has a larger capability of suppressing the short channel effects than the two step sidewall scheme. In the case of 200 /spl Aring/-thick screening oxide deposition, both NMOS and PMOS devices maintain good subthreshold characteristics down to 0.1 /spl mu/m effective channel lengths, and show affordable drain saturation current reduction and low impact ionization rates.