1. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 1 Chapter 2 Introduction of IC Fabrication Hong Xiao, Ph. D. hxiao89@hotmail.com

2. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 2 Objectives Define yield and explain its importance Describe the basic structure of a cleanroom. Explain the importance of cleanroom protocols List four basic operations of IC processing Name at least six process bays in an IC fab Explain the purposes of chip packaging Describe the standard wire bonding and flip-chip bump bonding processes

3. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 3 Wafer Process Flow Materials Design Masks IC Fab Test Packaging Final Test Thermal Processes Photo- lithography Etch PR strip Implant PR strip Metallization CMP Dielectric deposition Wafers

4. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 4 Fab Cost Fab cost is very high, > $1B for 8” fab Clean room Equipment, usually > $1M per tool Materials, high purity, ultra high purity Facilities People, training and pay

5. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 5 Wafer Yield

6. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 6 Die Yield

7. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 7 Packaging Yield

8. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 8 Overall Yield Y T = Y W  Y D  Y C Overall Yield determines whether a fab is making profit or losing money

9. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 9 How Does Fab Make (Loss) Money Cost: –Wafer (8”): ~$150/wafer * –Processing: ~$1200 ($2/wafer/step, 600 steps) –Packing: ~$5/chip Sale: –~200 chips/wafer –~$50/chip (low-end microprocessor in 2000) *Cost of wafer, chips per wafer, and price of chip varies, numbers here are choosing randomly based on general information.

10. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 10 How Does a Fab Make (Loss) Money 100% yield: 150+1200+1000 = $2350/wafer 50% yield: 150+1200+500 = $1850/wafer 0% yield: 150+1200 = $1350/wafer 100% yield: 200  50 = $10,000/wafer 50% yield: 100  50 = $5,000/wafer 0% yield: 0  50 = $0.00/wafer 100% yield: 10000  2350 = $7650/wafer 50% yield : 5000  1850 = $3150/wafer 0% yield : 0  1350 =  $1350/wafer Cost: Sale: Profit Margin:

11. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 11 Question If yield for every process step is 99%, what is the overall processing yield after 600 process steps?

12. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 12 Answer It equals to 99% times 99% 600 times 0.99 600 = 0.0024 = 0.24% Almost no yield

13. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 13 Throughput Number of wafers able to process –Fab:wafers/month (typically 10,000) –Tool:wafers/hour (typically 60) At high yield, high throughput brought

14. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 14 Defects and Yield

15. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 15 Yield and Die Size Y = 28/32 = 87.5%Y = 2/6 = 33.3% Killer Defects

16. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 16 Illustration of a Production Wafer Die

17. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 17 Illustration of a Production Wafer Scribe Lines Dies Test Structures

18. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 18 Clean Room Artificial environment with low particle counts Started in medical application for post-surgery infection prevention Particles kills yield IC fabrication must in a clean room

19. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 19 Clean Room First used for surgery room to avoid bacteria contamination Adopted in semiconductor industry in 1950 Smaller device needs higher grade clean room Less particle, more expensive to build

20. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 20 Clean Room Class Class 10 is defined as less than 10 particles with diameter larger than 0.5  m per cubic foot. Class 1 is defined as less than 1 such particles per cubic foot. 0.18 mm device require higher than Class 1 grade clean room.

21. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 21 Cleanroom Classes 0.1 1 10 100 1000 10000 100000 Class 100,000 Class 10,000 Class 1,000 Class 100 Class 10 Class 1 # of particles / ft 3 0.11.010 Particle size in micron Class M-1

22. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 22 Definition of Airborne Particulate Cleanliness Class per Fed. Std. 209E Class Particles/ft 3 0.1  m0.2  m0.3  m0.5  m5  m M-19.82.120.8650.28 1357.531 10350753010 100 750300100 1000 7 10000 70

23. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 23 Effect of Particles on Masks Particles on Mask Stump on +PR Hole on  PR Film Substrate

24. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 24 Effect of Particle Contamination Partially Implanted Junctions Particle Ion Beam Photoresist Screen Oxide Dopant in PR

25. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 25 Cleanroom Structure Process Area Equipment Area Class 1000 Equipment Area Class 1000 Raised Floor with Grid Panels Return Air HEPA Filter Fans Pump, RF and etc. Process Tool Makeup Air Class 1

26. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 26 Mini-environment Class 1000 cleanroom, lower cost Boardroom arrangement, no walls between process and equipment Better than class 1 environment around wafers and the process tools Automatic wafer transfer between process tools

27. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 27 Mini-Environment Cleanroom Class 1000 Raised Floor with Grid Panels Return Air HEPA Filter Fans Pump, RF and etc. Process Tool Makeup Air Process Tool HEPA Filter < Class 1

28. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 28 Gowning Area Gown Racks Benches Shelf of Gloves, Hair and Shoe Covers Disposal Bins Wash/Clean Stations Storage Shelf of Gloves Entrance To Cleanroom

29. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 29 IC Fabrication Process Module Photolithography Thin film growth, dep. and/or CMP Etching PR Stripping Ion Implantation RTA or Diffusion

30. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 30 Illustration of Fab Floor Process Bays Gowning Area Corridor Equipment Areas Sliding Doors Service Area

31. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 31 Mini-environment Fab Floor Gowning Area Emergency Exits Service Area Process and metrology tools

32. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 32 Wet Processes Dry Etch, PR strip, or cleanRinse

33. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 33 Horizontal Furnace Center Zone Flat Zone Distance Temperature Heating Coils Quartz Tube Gas flow Wafers

34. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 34 Vertical Furnace Process Chamber Wafers Tower Heaters

35. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 35 Schematic of a Track Stepper Integrated System Hot Plates Prep Chamber Chill Plates Spin Coater Developer Stepper Wafer Movement Wafer

36. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 36 Cluster Tool with Etch and Strip Chambers Transfer Chamber PR Strip Chamber Loading Station Etch Chamber PR Strip Chamber Etch Chamber Unloading Station Robot

37. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 37 Cluster Tool with Dielectric CVD and Etchback Chambers Transfer Chamber Loading Station PECVD Chamber O 3 -TOES Chamber Unloading Station Robot Ar Sputtering Chamber

38. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 38 Cluster Tool with PVD Chambers Transfer Chamber Loading Station Ti/TiN Chamber Al  Cu Chamber Unloading Station Robot Al  Cu Chamber Ti/TiN Chamber

39. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 39 Dry-in Dry-out CMP System Wafer Loading and Standby Post-CMP Clean Rinse Dryer and Wafer Unloading Multi-head Polisher Polishing Pad Clean Station Polishing Heads

40. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 40 Process Bay and Equipment Areas Process Area Equipment Area Process Tools Tables For PC and Metrology Tools Service Area Sliding Doors Wafer Loading Doors

41. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 41 Test Results Failed die

42. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 42 Chip-Bond Structure Chip (Silicon)Chip Backside Metallization Solder Substrate Metallization Substrate (Metal or Ceramic) Microelectronics Devices and Circuits Melt and Condense

43. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 43 Wire Bonding Metal Wire Formation of molten metal ball Bonding Pad Press to make contact Head retreat Wire Clamp

44. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 44 Wire Bonding LeadBonding Pad Lead Lead contact with pressure and heat Clamp closed with heat on to break the wire

45. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 45 IC Chip with Bonding Pads Bonding Pads

46. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 46 IC Chip Packaging

47. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 47 Chip with Bumps Bumps

48. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 48 Flip Chip Packaging Chip Bumps SocketPins

49. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 49 Bump Contact Chip Bumps SocketPins

50. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 50 Heating and Bumps Melt Chip Bumps SocketPins

51. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 51 Flip Chip Packaging Chip SocketPins

52. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 52 Molding Cavity for Plastic Packaging Bonding WiresIC Chip Lead Frame Pins Chip Bond Metallization Top Chase Bottom Chase Molding Cavity

53. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 53 Ceramic Seal Ceramic Cap Bonding WiresIC Chip Lead Frame, Layer 1 Pins Cap Seal Metallization Chip Bond Metallization Layer 2

54. Hong Xiao, Ph. D.www2.austin.cc.tx.us/HongXiao/Boo k.htm 54 Summary Overall yield Yield determines losing money or making profit Cleanroom and cleanroom protocols Process bays Process, equipment, and facility areas Die test, wafer thinning, die separation, chip packaging, and final test