CMOS Fabrication process

1. CMOS Fabrication
Process
By Prof. Hitesh Dholakiya
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VLSI Lecture series
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2. nMOS and pMOS structure on P Type Substrate
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3. Create n well or p well
region and channel
stop region
❖ For nMOS and pMOS, special region must be created in which
semiconductor type is opposite to the substrate type, these region
are called wells or tubs.
❖ p well is created in n type substrate and n well is created in p type
substrate.
❖ nMOS transistor are created in p type substrate or p well and pMOS
transistor are created in n type substrate or n well.
❖ That well should be of defined boundary to have fixed channel stop
region.
❖ Thick Oxide is grown in active region of nMOS and pMOS.
❖ The thin gate oxide is grown on the surface through thermal
oxidation.
❖ As per circuit make a pattern of polysilicon layer.
❖ After that create n+ and p+ regions for source, drain and substrate.
❖ Final metallization for metal interconnects.
Grow field oxide (Thick
Oxide) and gate oxide
(Thin Oxide)
Deposit and pattern
polysilicon layer
Implant source, drain
region and substrate
contacts
Create contact
windows, deposit and
pattern metal layer
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4. nMOS and pMOS on P Type Substrate
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