The following lists part of a 0.25-m CMOS process flow. This sequence includes a

Question

The following lists part of a 0.25-m CMOS process flow. This sequence includes a lightly doped drain and a self-aligned silicide. The "select" mask produces a photore- sist image that opens up that device for an implant or etch and protects everything else on the chip. Embedded in this sequence are five major mistakes that will prevent the device from working. Find four of them and explain why they are incorrect. 6. Complete device through well formation, isolation, and channel implants Strip screen oxide to silicon Gate oxidation (dry O2, 800°C, 10 min) Gate mask Reactive ion etch gate electrode to gate oxide Resist strip PMOS transistor select mask Implant (P. 10 keV, 1 × 1015 cm-2) Resist strip NMOS transistor select mask Implant (As, 10 keV, 1 × 1014 cm-2) Resist strip Deposit aluminum for sidewall spacer (0.2 m) Etch reactive ion etch to silicon NMOS transistor select mask Implant (As, 20 keV, 1 × 1015 cm-2) Anneal (N2, 1000 C, 5 sec) Etch gate oxide down to silicon Sputter Ti (5 m thick) Anneal (N2, 550°C, 60 sec) Etch in aqua regia Anneal (N2, 750°C 60 sec) Finish wafer with interconnect

Explanation / Answer

1.Gate Oxidation (Dry O2 ,800oC,10 Min)

Here Oxidation temperature Should be 1000oC

2.Implant(P,10kev,1*10^15cm^-2)

Here Doping Concentration Should be 1*10^15cm^-3

3.Sputter Ti(5micro meters thick)

Thickness of Titanium should be 50-100nano meters

4.Anneal(N2,750oC,60sec)

Annealing temperature isaround 400-650oC

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