1. 半導體量測技術 Semiconductor Materials and Device Characterization Topic 5: oxide trapped charge and poly-depletion effect in MOSFET Instructor: Dr. Yi-Mu Lee Department of Electronic Engineering National United University

2. Determine Q ot or Q m : D. K. Schroder, p. 363

3. Q ot QmQm no effect has effect effect on both sweeping direction D. K. Schroder, p. 363

4. Finite gate doping density: Typical doping densities: 10 19 ~10 20 /cm 3 D. K. Schroder, p. 351

5. Poly depletion effect on C-V curve (PMOS device): Lf and hf C-V: both showing capacitance drop Why? D. K. Schroder, p. 351

6. Poly depletion effects: 1.Change V t 2.Reduce the drain current 3.Increase gate resistance 1~3: reduce circuit speed

7. V FB -t ox plot: determine work function and Q f D. K. Schroder, p. 360

8. D. K. Schroder, p. 361

9. D. K. Schroder, p. 339

10. D. K. Schroder, p. 340

11. Fig 6.4 (a) D. K. Schroder, p. 341

12. Fig 6.4 (b) and (c) (b) –Vg, surface: accumulated, Q p dominates, C p is very high, so C p, C b, C n, C it are shorted (c) Small +Vg, depleted surface, Q b dominates Depletion to weak inversion Fig. from D. K. Schroder, p. 341

13. Fig 6.4 (d) and (e) (d) Strong inversion: C n can follow applied ac voltage, low-freq (e) Inversion charge can’t follow ac voltage, high-freq Fig. from D. K. Schroder, p. 341

14. Interface trapped charge (Q it ) Low-freq (quasistatic) method Effect of Q it on lf and hf C-V acceptor-like and donor-like trap density

15. High-freq CV Distorted C-V stretch-out due to gate-voltage axis Qit doesnot contribute capacitance Fig. from D. K. Schroder, p. 369

16. Low-freq CV additional capacitance: Q it respond low-frequency Qit does contribute capacitance Donor-like trap acceptor-like trap inversion delay Fig. from D. K. Schroder, p. 369

17. Review: P. 346 (exercise 6.1) Band structure (equilibrium, non-equilibrium) P. 368~372 Derive eq (6.44) and (6.47)