Threshold Adjustment

Q_i = x_iN_i implant dose
x_d depletion-layer width beneath the gate

Thus, for shallow implants, the threshold-voltage shift is approximately proportional to the implanted dose. (positive acceptors - negative donors)

Field - Region

The region between two transistor is called the field region and must be designed to provide isolation between adjacent MOS devices.

1. turn-off parasitic NMOS
2. make parasitic V_T large ® field oxide 3-10 gate oxide
3. field implant to increase V_T
4. phosphorus pile-up aid in increase V_T fro PMOS
5. check punch-through condition

TO PAGE 4