Shadowing effects due to tilted arsenic source/drain implant

The extent of n/sup +/ source/drain implant shadowing by the LDD (lightly doped drain) oxide sidewall spacer was studied for the commonly used 7 degrees wafer-to-implant beam tilt. A clear asymmetry in substrate current characteristics was observed between normal and reverse polarity, despite the use of 0 degrees tilt for the n/sup -/ LDD implant. The results suggest that 0 degrees tilt should be used for both n/sup -/ (LDD) and n/sup +/ (source/drain) implants.<
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