CMOS Processes

1. CMOS Processes

Hong Xiao, Ph. D.
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1

2. 1990’s Technology

• Driving force: digital logic electronics
– PC, telecommunication, and internet.
• Feature size: from 0.8 mm to 0.18 mm
• Wafer size: from 150 mm to 300 mm
Hong Xiao, Ph. D.
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2

3. 1990’s CMOS Technology

• Epitaxy silicon
• Shallow trench isolation
• The sidewall spacer for LDD and salicide
• Polycide gates and local interconnections
reduce resistance and improve device speed
– Tungsten silicide and titanium silicide.
Hong Xiao, Ph. D.
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3

4. 1990’s CMOS Technology

• Photolithography
– G-line, I-line (365 nm), and DUV 248 nm
– Positive photoresist
– Steppers replaced projection printer
– Track-stepper integrated systems
• Plasma etches for patterned etch
• Wet etches for blanket film stripping
Hong Xiao, Ph. D.
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4

5. 1990’s CMOS Technology

• Vertical furnaces
– smaller footprints, better contamination control.
• RTP systems
– post-implantation annealing
– silicide formation,
– faster, better process and thermal budget control.
• DC magnetron sputtering replaced evaporation
Hong Xiao, Ph. D.
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6. 1990’s CMOS Technology

• Multi-layer metal interconnection
• W CVD and CMP (or etch back) to form plugs
• Ti and TiN barrier/adhesion layer for W
• Ti welding layer for Al-Cu to reduce contact
resistance
• TiN ARC
Hong Xiao, Ph. D.
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7. 1990’s CMOS Technology

• BPSG was popularly used as PMD.
• DCVD: PE-TEOS and O3-TEOS
– STI, sidewall spacer, PMD, and IMD
• DCVD: PE-silane
– PMD barrier nitride, dielectric ARC, and PD nitride
• Tungsten CMP to form plug
• Dielectric CMP for planarization
Hong Xiao, Ph. D.
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7

8. 1990’s CMOS Technology

• Cluster tools became very popular
• Single wafer processing systems improve
wafer-to-wafer uniformity control
• Batch systems is still commonly employed
in many non-critical processes for their high
throughput.
Hong Xiao, Ph. D.
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8

9. Epitaxy Deposition

P-Epi
Hong Xiao, Ph. D.
P-Wafer
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9

10. Mask 1: N-well

Hong Xiao, Ph. D.
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10

11. N-well Implantation

Phosphorus Ions
Photoresist
N-Well
P-Epi
Hong Xiao, Ph. D.
P-Wafer
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11

12.

Mask 2: P-well
Hong Xiao, Ph. D.
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12

13. P-well Implantation

Boron Ions
Photoresist
P-Well
N-Well
P-Epi
Hong Xiao, Ph. D.
P-Wafer
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13

14. Strip PR, Strip Nitride/Pad Oxide

P-Well
P-Epi
Hong Xiao, Ph. D.
N-Well
P-Wafer
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14

15. Pad Oxidation, LPCVD Nitride

Nitride
P-Well
P-Epi
Hong Xiao, Ph. D.
N-Well
P-Wafer
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15

16.

Mask 3: Shallow Trench Isolation
Hong Xiao, Ph. D.
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16

17. Etch Nitride, Pad Oxide and Silicon

Nitride
Nitride
P-Well
P-Epi
Hong Xiao, Ph. D.
N-Well
P-Wafer
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17

18. HDP-CVD USG Trench Fill

USG
Nitride
Nitride
USG
P-Well
P-Epi
Hong Xiao, Ph. D.
N-Well
P-Wafer
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18

19. CMP USG, Stop on Nitride

Nitride
Nitride
USG
P-Well
P-Epi
Hong Xiao, Ph. D.
N-Well
P-Wafer
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19

20. Strip Nitride and Pad Oxide, Clean

USG
STI
P-Well
P-Epi
Hong Xiao, Ph. D.
N-Well
P-Wafer
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20

21.

Mask 4: N-channel VT Adjust
Hong Xiao, Ph. D.
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21

22.

Phosphorus Ions
Photoresist
USG
STI
P-Well
P-Epi
Hong Xiao, Ph. D.
N-Well
P-Wafer
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22

23.

Mask 5: P-channel VT Adjust
Hong Xiao, Ph. D.
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23

24.

Boron Ions
Photoresist
USG
STI
P-Well
P-Epi
Hong Xiao, Ph. D.
N-Well
P-Wafer
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24

25. Gate Oxidation, LPCVD Polysilicon

Polysilicon
USG
STI
P-Well
P-Epi
Hong Xiao, Ph. D.
N-Well
P-Wafer
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25

26.

Mask 6: Gate & Local Interconnection
Hong Xiao, Ph. D.
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26

27. Etch Polysilicon

Gate Oxide
STI
Hong Xiao, Ph. D.
Photoresist
Polysilicon gate
USG
P-Well
N-Well
P-Epi
P-Wafer
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27

28.

Mask 7: N-channel LDD
Hong Xiao, Ph. D.
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28

29. N-channel LDD Implantation, Arsenic

Arsenic Ions
Photoresist
USG
STI
P-Well
P-Epi
Hong Xiao, Ph. D.
N-Well
P-Wafer
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29

30.

Mask 8: P-channel LDD
Hong Xiao, Ph. D.
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30

31. P-channel LDD Implantation, BF2+

+
P-channel LDD Implantation, BF2
BF2+ Ions
Photoresist
USG
STI
P-Well
P-Epi
Hong Xiao, Ph. D.
N-Well
P-Wafer
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31

32. Sidewall Spacer

Polysilicon gate
n-LDD
Gate oxide
Hong Xiao, Ph. D.
n-LDD
Sidewall
Spacer
Polysilicon gate
n-LDD
Gate oxide
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Sidewall
Spacer
n-LDD
32

33.

Mask 9: N-channel Source/Drain
Hong Xiao, Ph. D.
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33

34. N-channel Source/Drain Implantation

Phosphorus Ions
Photoresist
STI
n+
n+
USG
P-Well
P-Epi
Hong Xiao, Ph. D.
p-
p-
N-Well
P-Wafer
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34

35.

Mask 9: P-channel Source/Drain
Hong Xiao, Ph. D.
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35

36. P-channel Source/Drain Implantation

Boron Ions
Photoresist
STI
Hong Xiao, Ph. D.
n+
n+
USG
p+
P-Well
N-Well
P-Epi
P-Wafer
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p+
36

37. Titanium Salicide Process

Ar
Ar +
+
Sidewall
spacer
n-
n+
Polysilicon gate
Gate oxide
Ti
Sidewall
spacer
Polysilicon gate
n-
nn+
n+
Gate oxide
nn+
Ti
TiSi2
Polysilicon gate
nn+
TiSi2
Gate oxide
Hong Xiao, Ph. D.
TiSi2
Polysilicon gate
n-
nn+
TiSi2
n+
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Gate oxide
n-
n+
37

38. Titanium Self-aligned silicide Process

Titanium Deposition
STI
Sidewall Spacer
Silicon
Titanium
RTP Silicide Alloying
Silicon
Strip Unreact Titanium
Polysilicon
Hong Xiao, Ph. D.
Titanium Silicide
Silicon
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Gate
Oxide
k.htm
38

39. BPSG Deposition and Reflow

BPSG
STI
n+
n+
n+
USG
p+
p+
USG
p+
p+
BPSG
STI
Hong Xiao, Ph. D.
n+
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39

40.

Mask 10: Contact Hole
Hong Xiao, Ph. D.
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40

41. Contact Hole Etch, BPSG Etch

BPSG
STI
Hong Xiao, Ph. D.
n+
n+
p+
USG
P-Well
N-Well
P-Epi
P-Wafer
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p+
41

42. Contact Hole Etch, BPSG Etch

Titanium/Titanium Nitride
Tungsten
BPSG
STI
Hong Xiao, Ph. D.
n+
n+
p+
USG
P-Well
N-Well
P-Epi
P-Wafer
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p+
42

43. Contact Hole Etch, BPSG Etch

Titanium/Titanium Nitride
TiN ARC
Titanium
Aluminum Copper Alloy
W BPSG
STI
Hong Xiao, Ph. D.
n+
n+
p+
USG
P-Well
N-Well
P-Epi
P-Wafer
www2.austin.cc.tx.us/HongXiao/Boo
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p+
43

44. Mask 11: Metal 1 Interconnect

Hong Xiao, Ph. D.
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44

45. Metal Etch

Titanium/Titanium Nitride
TiN ARC
Titanium
Al-Cu Alloy
W BPSG
STI
Hong Xiao, Ph. D.
n+
n+
p+
USG
P-Well
N-Well
P-Epi
P-Wafer
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p+
45

46. PE-TEOS USG Dep/Etch/Dep/CMP

IMD 1
USG Dep/Etch/Dep/CMP
Al-Cu Alloy
W BPSG
STI
Hong Xiao, Ph. D.
n+
n+
USG
P-Well
P-Epi
P-Wafer
www2.austin.cc.tx.us/HongXiao/Boo
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p+
p+
N-Well
46

47. Mask 12: Via 1

Hong Xiao, Ph. D.
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47

48. Via Etch, Etch USG

IMD 1
USG
Al-Cu Alloy
W BPSG
STI
Hong Xiao, Ph. D.
n+
n+
USG
P-Well
P-Epi
P-Wafer
www2.austin.cc.tx.us/HongXiao/Boo
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p+
p+
N-Well
48

49. Via Etch, Etch USG

Metal 2
IMD 1
Al-Cu Alloy
USG
M1
Al-Cu Alloy
W BPSG
STI
Hong Xiao, Ph. D.
n+
n+
USG
P-Well
P-Epi
P-Wafer
www2.austin.cc.tx.us/HongXiao/Boo
k.htm
p+
p+
N-Well
49

50. Mask 13: Metal 2 Interconnect

Hong Xiao, Ph. D.
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50

51. Etch Metal 2

M2
IMD 1
Al•Cu
USG
M1
Al•Cu Alloy
W BPSG
STI
Hong Xiao, Ph. D.
n+
n+
USG
P-Well
P-Epi
P-Wafer
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p+
p+
N-Well
51

52. USG Dep/Etch/Dep/CMP

IMD 2
USG
M2
IMD 1
Al•Cu
USG
M1
Al•Cu Alloy
W BPSG
STI
Hong Xiao, Ph. D.
n+
n+
USG
P-Well
P-Epi
P-Wafer
www2.austin.cc.tx.us/HongXiao/Boo
k.htm
p+
p+
N-Well
52

53. Mask 14: Via 2

Hong Xiao, Ph. D.
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53

54. Via 2 Etch, Etch USG

IMD 2
USG
M2
IMD 1
Al•Cu
USG
M1
Al•Cu Alloy
W BPSG
STI
Hong Xiao, Ph. D.
n+
n+
P-Well
USG
www2.austin.cc.tx.us/HongXiao/Boo
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p+
N-Well
p+
54

55. Metallization of Metal 3

Metal 3
IMD 2
USG
M2
IMD 1
Al•Cu Alloy
W
Al•Cu
USG
M1
Al•Cu Alloy
W BPSG
STI
Hong Xiao, Ph. D.
n+
n+
P-Well
USG
www2.austin.cc.tx.us/HongXiao/Boo
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p+
N-Well
p+
55

56. Mask 15: Metal 3 Interconnects

Hong Xiao, Ph. D.
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56

57. Metal Etch, PR Strip and Metal Anneal

Metal 3
IMD 2
USG
W
Al•Cu
M2
IMD 1
Al•Cu Alloy
USG
Al•Cu Alloy
M1
W BPSG
STI
Hong Xiao, Ph. D.
n+
n+
P-Well
USG
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p+
N-Well
p+
57

58. PE-TEOS USG Dep/Etch/Dep/CMP

IMD 3
USG
Metal 3
IMD 2
USG
M2
IMD 1
Hong Xiao, Ph. D.
Al•Cu Alloy
W
Al•Cu
USG
M1
Al•Cu Alloy
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58

59. Mask 16: Via 3

Hong Xiao, Ph. D.
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59

60. Via 3 Etch and PR Strip

IMD 3
USG
Metal 3
IMD 2
USG
Hong Xiao, Ph. D.
W
Al•Cu
M2
IMD 1
Al•Cu Alloy
USG
M1
Al•Cu Alloy
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60

61. Metal 4 Deposition

Al•Cu
Metal 4
IMD 3
USG
Metal 3
IMD 2
USG
M2
IMD 1
Hong Xiao, Ph. D.
Al•Cu Alloy
W
Al•Cu
USG
M1
Al•Cu Alloy
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61

62. Mask 17: Metal 4 Interconnects

Hong Xiao, Ph. D.
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62

63. Etch Metal 4

Al•Cu Alloy
Al•Cu
Metal 4
IMD 3
USG
Metal 3
Hong Xiao, Ph. D.
Al•Cu Alloy
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63

64. Passivation Dielectric Deposition

Silicon Nitride
USG
Al•Cu Alloy
Al•Cu
Metal 4
IMD 3
USG
Metal 3
Hong Xiao, Ph. D.
Al•Cu Alloy
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64

65. Mask 18: Bonding Pad

Hong Xiao, Ph. D.
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65

66. Etch Bonding Pad, Strip PR

Silicon Nitride
USG
Al•Cu Alloy
Al•Cu
Metal 4
IMD 3
USG
Metal 3
Hong Xiao, Ph. D.
Al•Cu Alloy
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66

67.

Passivation 2
Silicon Nitride
Passivation 1
Al•Cu Alloy
USG
Al•Cu
Metal 4
Ti/TiN
IMD33
IMD
USG
TiN ARC
Metal 3
Al•Cu Alloy
Ti
Ti/TiN
IMD 2
W
USG
M2
IMD 1
Al•Cu
M1
PMD
TiSi2
W
USG
Al•Cu Alloy
W
Sidewall
Spacer, USG
BPSG
Poly-Si
STI
Hong Xiao, Ph. D.
n+
n+
p+
USG
P-Well
N-Well
P-Epi
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P-Wafer
k.htm
p+
PMD Barrier
Nitride
67

68. Lead-Tin Alloy Coating

Lead-tin alloy
Nitride
PSG
Copper 5
SOD
SOD
Hong Xiao, Ph. D.
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68

69. PR Coating, A&E, PEB, and Develop

PR Coating, A&E, PEB, and Develop
Photoresist
Lead-tin alloy
Nitride
PSG
Copper 5
SOD
SOD
Hong Xiao, Ph. D.
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69

70. Metal Etch

Photoresist
Lead-tin alloy
Nitride
PSG
Copper 5
SOD
SOD
Hong Xiao, Ph. D.
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70

71. Strip Photoresist

Lead-tin alloy
Nitride
PSG
Copper 5
SOD
SOD
Hong Xiao, Ph. D.
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71

72. Lead-Tin Alloy Reflow

Lead-tin alloy
Nitride
PSG
Copper 5
SOD
SOD
Hong Xiao, Ph. D.
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72

73.

Cr, Cu, and
Au liners
Lead-tin alloy
Nitride
SiN seal
layer
PSG
Copper 5
SOD
SOD
Copper 4
SOD
SiC etch
stop layers
Ta/TaN
barrier layer
SOD
Cu 3
SOD
Cu 3
SOD
Copper 2
SOD
SiC seal layer
SOD
PE-TEOS cap
Cu 1
Cu 1 SOD
CoSi2
Poly Si gate
Hong Xiao, Ph. D.
Cu 1
Cu 1
SOD
W
SiC seal layer
PSG
Tungsten
n+
n+ USG p+
STI www2.austin.cc.tx.us/HongXiao/Boo
P-well
N-well
Buried SiO 2 k.htm
P-wafer
p+
USG
SiN barrier
layer
73