1. Fundamentals of Semiconductor Physics 万 歆 Zhejiang Institute of Modern Physics xinwan@zimp.zju.edu.cn http://zimp.zju.edu.cn/~xinwan/ Fall 2006

2. Five-Point Plan for Success ☺Pursue your passions ☺Venture where you have never ventured before ☺Pace yourself ☺Serve others ☺Have lots of fun -- Princeton President Shirley M. Tilghman

3. Chapter 2. Silicon Technology Two foundations of successful engineering: –Mastery of physics concepts –Perfect technology – means to transfer concepts into useful structures. Total 3 hours.

4. IC Card

5. Si, Ge & GaAs Technological evolution began with gemanium in 1940s. –Band gap E g = 0.67 eV –At 300 K, intrinsic carrier density n i = 2.5 x 10 13 cm -3 –n i arises fast with T, due to small E g – ~10 15 cm -3 at 400 K –Device not useful when intrinsic carrier concentration is comparable to dopant density. Research efforts shifted to silicon (E g = 1.12 eV) and GaAs (E g = 1.42 eV) in 1950s.

6. Advantages of Silicon Key: ability to form on silicon a stable, controllable oxide film (silicon oxide, SiO 2 ) that has excellent insulating properties. Selective etching: HF dissolves SiO 2 not Si SiO 2 shields Si from doping (photosensitive polymer films are used to define shielded regions).

7. Wafer – Chips - Devices

8. The Whole Process

9. Planar Process Formation of a masking oxide layer Its selective removal Deposition of dopant atoms on or near the wafer surface Their diffusion into the exposed silicon regions

10. Czochralski Process

11. Single-Crystal Ingots of Silicon

12. Dopant Concentration

14. Floating-Zone Process

15. Primary & Secondary Flat

16. Silicon Wafers

17. MOSFET: An Example

18. Lithography & Pattern Transfer

19. Why Clean Room?

20. Thermal Oxidation

21. Silicon-Silicon Dioxide

22. Contact & Proximity Printing

23. Projection Printing

24. Positive & Negative Photoresist

25. Lift-off

26. Pattern Transfer

27. Doping: Gaseous Deposition

28. Doping: Ion Implantation

29. Doping Comparison

30. Metallization