A study of tilt angle effect on Halo PMOS performance

The Halo structure is usually adopted in deep submicrometer MOS devices for punchthrough prevention. The tilt angle of the Halo implant determines the dopant distribution which induces anti-punchthrough operation. In this paper, we investigate the impact of the tilt angle on the Halo PMOS device performance via two-dimensional (2D) simulations. We find that the ratio of on-current to off-current is constant for all tilt angles of Halo implant, implying an equivalent DC performance for all tilt angles. The equivalence can be traced back to a self compensation between the body factor and source resistance. The result implies that a low tilt angle should be adopted for Halo devices, for it gives a small threshold voltage and thus a high noise margin. The methodology used in analyzing body factor and source resistance can also be applied to analyze other devices.