The document describes the design and simulation of a CMOS fabrication process using TCAD (Technology Computer-Aided Design). It involves dimensioning the design using MOSIS design rules, creating masks, and defining 44 steps for the process in Synopsys TCAD. This includes doping wells, growing oxides, depositing polysilicon, implanting sources and drains, and depositing metals. The process aims to fabricate n-well and p-well CMOS on a silicon substrate using a minimum number of masks. Characterization and optimization of the modeled device can be done using additional TCAD tools.

1. Rajesh Yadav 12ECP01P
Aakansha 13VLP001
Surbhi 13VLP013
6/23/2014 1itm University, Gurgaon

2. Agenda
Introduction
Problem Statements
Dimensioning using Mosis Design Rule
Mask Designing
Design steps using Synopsis TCAD
Conclusion and Future Scopes
References
6/23/2014 2itm University, Gurgaon

3. Agenda
Introduction
Problem Statements
Dimensioning using Mosis Design Rule
Mask Designing
Design steps using Synopsis TCAD
Conclusion and Future Scopes
References
6/23/2014 3itm University, Gurgaon

4. Introduction
• CMOS Design has basically Three Types
• pwell CMOS
• nwell CMOS
• Twin well/ Twin Tub CMOS
 Technology CAD is
 Numeric simulation of Semiconductor Process and Device
 Basic subprogram used in TCAD
i. Sentaurus Structure Editor
ii. Sentaurus Process
iii. Sentaurus Device
iv. Sentaurus Workbench
v. Svisual
.
6/23/2014 4itm University, Gurgaon

5. Agenda
Introduction
Problem Statements
Dimensioning using Mosis Design Rule
Mask Designing
Design steps using Synopsis TCAD
Conclusion and Future Scopes
References
6/23/2014 5itm University, Gurgaon

6. Problem Statements
• Using TCAD, Design a process sequence to fabricate the following CMOS structure
This Design Involves the
following unit steps
6/23/2014 6itm University, Gurgaon

7. Problem Statements
1. Silicon Substrate
2. n-well creation
3. P-well creation
4. Channel stop implant
and FOX creation
5. Gate oxidation
6. Polysilicon deposition
7. nmos LDD Implant
8. pmos LDD implant
9. Spacer formation
10. nmos S-D Implantation
11. pmos S-D Implantation
12. Silicide formation
13. Oxide layer deposition
14. Aluminum Contacts
n-well
p/n type Silicon Substrate
p-well
6/23/2014 7itm University, Gurgaon

8. Agenda
Introduction
Problem Statements
Dimensioning using Mosis Design Rule
Mask Designing
Design steps using Synopsis TCAD
Conclusion and Future Scopes
References
6/23/2014 8itm University, Gurgaon

9. Dimensioning using Mosis Design Rule
6
4
2
4
6
2
1 1
3
3
2
2
2
24
n-mos/ p-mos Design Rule
o Only in Y-direction(horizontal) dimension
o All dimensions are in Lambda
o 1Lambda = 100nm (for this particular
Design, since channel length = 200nm)
6/23/2014 9itm University, Gurgaon

10. • Complete CMOS Dimensioning
6 4 44 6 6 4 44 6
18
Dimensioning using Mosis Design Rule
Total substrate length required
= 24+18+24 = 66λ
6/23/2014 10itm University, Gurgaon

11. Agenda
Introduction
Problem Statements
Dimensioning using Mosis Design Rule
Mask Designing
Design steps using Synopsis TCAD
Conclusion and Future Scopes
References
6/23/2014 11itm University, Gurgaon

12. Mask Designing
Mask-1: For nwell doping
Mask-2: For pwell doping
42 24
4224
Mask-3: Active area (negative)
Nitride etching
Mask-4: Gate area (negative)
Polysilicon etching
6 12 30 12 6
11 2 40 2 11
Mask-5: Sorce – Drain Region
(negative) Gate-oxide etching
Mask-6: for Titanium etching
(negative)
Mask-7: for contact cut in thick
oxide (negative)
6 5 2 5 30 5 2 5 6
6 4 1214 30 41214 6
7 2 6 2 32 2 6 2 76/23/2014 12itm University, Gurgaon

13. Mask Designing
Mask-8: Aluminum etching 6 3 6 3 30 3 63 6
For a good design steps,
The number of mask
required should be
minimum
6/23/2014 13itm University, Gurgaon

14. Agenda
Introduction
Problem Statements
Dimensioning using Mosis Design Rule
Mask Designing
Design steps using Synopsis TCAD
Conclusion and Future Scopes
References
6/23/2014 14itm University, Gurgaon

15. Design Steps Using Synopsys TCAD
Step-1: Defining initial Substrate
Step:2: Masking for nwell doping
Length = 66Lambda =6.6 micron
Depth = 1.5 micron
Initial doping = 10E+14/cm3 with
Boron
Photomask-1 of thikness =
0.8 um.
6/23/2014 15itm University, Gurgaon

16. Step-3 : nwell doping with Phosphorus implantation
Step-4 : Etching Mask-1
Design Steps Using Synopsys TCAD
implant phosphorus dose=1.7e+10 energy=70
implant phosphorus dose=1.7e+10 energy=140
implant phosphorus dose=1.7e+10 energy=210
Required concentration = 1E+15/cm3
Required Depth of Implantation = 500nm
6/23/2014 16itm University, Gurgaon

17. Step-5 : Masking for pwell doping, Mask-2
Step-6 : pwell doping with Boron implantation
Design Steps Using Synopsys TCAD
Required concentration = 1E+15/cm3
Required depth = 500nm
implant Boron dose=1.7e+10 energy=40
implant Boron dose=1.7e+10 energy=80
implant Boron dose=1.7e+10 energy=110
6/23/2014 17itm University, Gurgaon

18. Step-7 : Etching the photo Mask-2
Step-8 : Grow pad oxide
Design Steps Using Synopsys TCAD
6/23/2014 18itm University, Gurgaon

19. Step-9 : Nitride deposition
Step-10 : Patterning and etching Nitride using mask -3 (active area defination)
Design Steps Using Synopsys TCAD
6/23/2014 19itm University, Gurgaon

20. Step-11 : Etching pad Oxide using, Mask-3
Step-12 : Masking for channel stop implant in pwell using Mask-2
Design Steps Using Synopsys TCAD
6/23/2014 20itm University, Gurgaon

21. Step-13 : Channel stop implant in pwell with Boron
Step-14 : Etching Photomask-2
Design Steps Using Synopsys TCAD
6/23/2014 21itm University, Gurgaon

22. Step-15 : Masking for nwell channel stop implant with mask-1
Step-16 : nwell channel stop implant with Phosphorous
Design Steps Using Synopsys TCAD
6/23/2014 22itm University, Gurgaon

23. Step-17 : Etching of photomask-1
Step-18 : Growing field oxide (Birds-Beak Formation)
Design Steps Using Synopsys TCAD
6/23/2014 23itm University, Gurgaon

24. Step-19 : Etching Nitride Layer
Step-20 : Growing Gate oxide
Design Steps Using Synopsys TCAD
6/23/2014 24itm University, Gurgaon

25. Step-21 : Deposit Polysilicon
Step-22 : selective etching of polysilicon using Mask-4
Design Steps Using Synopsys TCAD
6/23/2014 25itm University, Gurgaon

26. Step-23 : selective Etching of Gate Oxide using Mask-5
Step-24 : Masking for pmos LDD implant using mask-1
Design Steps Using Synopsys TCAD
6/23/2014 26itm University, Gurgaon

27. Step-25 : LDD Implantation for pmos with Boron
Step-26 : Remove the Photomask-1
Design Steps Using Synopsys TCAD
Desired Concentration = 1E+16/cm3
Desired Depth of Implantation = 30nm
implant boron dose=3e+10
energy=3
6/23/2014 27itm University, Gurgaon

28. Step-27 : Masking for LDD Implant in nmos
Step-28 : LDD Implantation in nmos with Phosphorous
Design Steps Using Synopsys TCAD
6/23/2014 28itm University, Gurgaon

29. Step-29 : Etch photomask-2
Step-30 : Deposit Nitride Spacer
Design Steps Using Synopsys TCAD
6/23/2014 29itm University, Gurgaon

30. Step-31 : Masking for Source – Drain implant in nmos using photomask-2
Step-32 : Source- Drain Implant in nmos with Phosphorous
Design Steps Using Synopsys TCAD
Desired Concentration = 1E+17/cm3
Desired Depth of implantation=
120nm
implant phosphorus dose=1.2e+12 energy=25
6/23/2014 30itm University, Gurgaon

31. Step-33 : Etch photomask -2
Step-34 : Masking for pmos Source-Drain Implant using photomask-1
Design Steps Using Synopsys TCAD
6/23/2014 31itm University, Gurgaon

32. Step-35 : source-Drain Implantation of pmos using Boron
Step-36 : Etching photomask-1
Design Steps Using Synopsys TCAD
6/23/2014 32itm University, Gurgaon

33. Step-37 : Titanium Silicide formation
Step-38 : Selected etching of Titanium
Design Steps Using Synopsys TCAD
6/23/2014 33itm University, Gurgaon

34. Step-39 : Thick Oxide layer deposition
Step-40 : Selected Etching of thick Oxide layer
Design Steps Using Synopsys TCAD
6/23/2014 34itm University, Gurgaon

35. Step-43 : Deposition of Contact aluminum layer
Step-44 : Selected etching of Aluminum layer
Design Steps Using Synopsys TCAD
Done
6/23/2014 35itm University, Gurgaon

36. Agenda
Introduction
Problem Statements
Dimensioning using Mosis Design Rule
Mask Designing
Design steps using Synopsis TCAD
Conclusion and Future Scopes
References
6/23/2014 36itm University, Gurgaon

37. Conclusion and future scope
• Taken a substrate first as per our required dimension
and lightly doped with Boron
• nwell and pwell creation
• Channel stop implantation and grown Field Oxide
• Gate Oxide and Polysilicon layer deposition
• LDD implantation
• Spacer formation
• Source – Drain Implantation
• Silicide formation
• Thick Oxide layer deposition for passivation
• Selected etching of Thick oxide and deposition of
Aluminum and patterning
 Further characterization of the modeled device can be done using
Sdevice.
 Complete optimization of device can only be done after creating a device
file (.des) correcponding to device characterization6/23/2014 37itm University, Gurgaon

38. Agenda
Introduction
Problem Statements
Dimensioning using Mosis Design Rule
Mask Designing
Design steps using Synopsis TCAD
Conclusion and Future Scopes
References
6/23/2014 38itm University, Gurgaon

39. Refrences
[1] Michael Duane, “The Role of TCAD in Compact Modelling ” , 3320 Scott
Blvd.,MS 1148,Santa Clara,CA.
[2] Sentaurus tool User Guide https://solvnet.synopsys.com..
6/23/2014 39itm University, Gurgaon

40. 6/23/2014 40itm University, Gurgaon

41. THANK YOU
6/23/2014 41itm University, Gurgaon