cmos fabrication.ppt

8/20/2019 CMOS Fabrication.ppt

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CMOS FabricationCMOS Fabrication

EMT 251EMT 251



Objectives

• To discussed the fundamentals ofCMOS fabrication steps

• To e!amined the major steps of theprocess flo"

• To overvie" the cross section vie" of

a circuit



Chip ma#in$ %rocess



&ntroduction

MOSFET

CMOSPMOS NMOS



SourceDrain

Gate

Metal Oxide Semiconductor Field Effect Transistor

Source (Arsenic, Phosphorous, Boron

Drain (Arsenic, Phosphorous, Boron

Gate (Aluminum, Pol!silicon

MOSFET



NMOS

P"t!pe su#strate

$"t!pe dopant for Source % Drain

&n'ersion la!er is formed to conduct electricit!



NMOS

P"t!pe su#strate

$"t!pe dopant for Source % Drain




PMOS

$"t!pe su#strate

P"t!pe dopant for Source % Drain




CMOS

A com#ination of #oth $MOS % PMOS technolo!

Most #asic example) in'erter



WELL FORMATIONWELL FORMATION

ISOLATION FORMATIONISOLATION FORMATION

TRANSISTOR MAKINGTRANSISTOR MAKING

INTERCONNECTIONINTERCONNECTION

PASSIVATIONPASSIVATION

%'OCESS F(O)



CMOS F*+'&C*T&O, %'OCESS "ell formation

• Start "ith clean p-t.pesubstrate /p-t.pe "afer0




• ro" epita!. la.er /made fromSiO20 as mas# la.er for "ellformation




• +. photolitho$raph. and etchin$process3 "ell openin$ are made

photolitho$raph. and etch processes are sho"n in ne!t slides

)ell "ill be formed

here



%hotolitho$raph. /CE40

%-substrateSi2

photoresist

• %hotoresist coatin$ /C0

• Mas#in$ and e!posureunder 67 li$ht/E0

• 'esist dissolved afterdeveloped /408 %re-shape the "ell

pattern at resist la.er

%-substrate

mas#

67 li$ht

Opa9uearea

Transparentarea



etchin$

• 'emovin$ the un"antedpattern b. "et etchin$

• 'esist clean

• 4esired pattern formed

%-substrate

%-substrate



CMOS F*+'&C*T&O, %'OCESS isolation formation

• &ncrease SiO2 thic#ness b.o!idation at hi$h temperature

• O!ide "ill electricall. isolates

nmos and pmos devices

Thic# o!ide



CMOS F*+'&C*T&O, %'OCESS transistor ma#in$

• +. photolitho$raph. and etchin$process3 pmos and nmos areasare defined

pmos "illbe formed

here

nmos "illbe formed

here

(OCOS /isolation structure0




• ro" ver. thin $ate o!ide atelevated temperature in ver.short time

ate o!ide



• 4eposit polisilicon la.er


polisilicon



• %hotolitho$raph. /photo0 andetchin$ to form $ate pattern


$ate




• %hoto process to define the nmos:sactive /source and drain0 area and744 contact

• &on implantation "ith *rsenic ion forn; dophant

• %hotoresist and polisilicon $ate act asmas#

photoresist

*rsenic ion



CMOS F*+'&C*T&O, %'OCESS

transistor ma#in$

• ,mos:s Source and drain "ith 744contact formation

• 'esist removal

source drain744

contact




• %hoto process to define the ,4 contactand pmos:s active area /source and drain0

• &on implantation "ith boron ionto have p;dophant

• %hotoresist and $ate act as mas#

+oron ion

photoresist




• %mos:s source and drainformation "ith ,4 contact

• 'esist removal

,4contact %mos:

source

%mos:sdrain



CMOS F*+'&C*T&O, %'OCESS interconnection

• 4eposit SiO2 la.er throu$hout "afer surface

SiO2



• %hoto and etchin$ process toma#e contact


contact



• Metal 1 deposition throu$hout"afer surface


Metal 1




• %hoto and etchin$ processes topattern interconnection



Mas# (a.out



**:

o!ide

p-substrate

n; n;

,-"ell

p;p;

Metal 1

n;



*ssi$nmentB

+:



(OSS*'<

• %hotolitho$raph. /photo08 %rocess of transferrin$ pattern on mas# to photoresist la.er on "afersurface /pre-pattern the chip0

• Etchin$8 %rocess of permanentl. removed the un"anted part of desi$n on "afer

surface to $et the desired pattern

• 4iffusion

8 %rocess of introducin$ dophant la.er b. movement of dophant atomsfrom hi$h concentration to lo" concentration area at hi$h temperature

• &on implantation8 %rocess of introducin$ dophant la.er b. bombardment of hi$h ener$.

dophant ion in hi$h electric field chamber

• O!idation8 %rocess of $ro"in$ thic# or thin SiO2 la.er depend on o!ide application

• CM%8 %rocess to ph.sicall. $rind flat to have a planar surface for better

e!posure at photo process

cmos fabrication.ppt

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