Pocket Implant is an alternative name for the Halo Implant — a tilted, localized doping technique that places additional channel-type dopant atoms near the source/drain junction edges to counteract short-channel effects in sub-micron MOSFETs.
Pocket vs. Halo: Same Technique, Different Names
- Origin: "Halo" is the more common term in US/European literature. "Pocket" is preferred in some Japanese and Asian references.
- Process: Identical to halo — tilted implant (15-45°) with wafer rotation, same type as channel doping.
- Purpose: Increase local doping near S/D junctions to maintain $V_t$ at short gate lengths.
Why It Matters
- Short-Channel Control: Essential for sub-100nm planar CMOS to maintain acceptable $V_t$ roll-off characteristics.
- Optimization: The dose, energy, and tilt angle are carefully tuned to balance $V_t$ control against junction leakage and mobility.
- Obsolescence: Not needed in FinFET and GAA architectures where undoped channels and compact geometry provide inherent short-channel resistance.
Pocket Implant is the halo implant by another name — the same critical short-channel effect countermeasure, widely used in the planar CMOS era.