Ch. 3 Lecture Slides for Chenming Hu book: Modern Semiconductor Devices for ICs

8/9/2019 Ch. 3 Lecture Slides for Chenming Hu book: Modern Semiconductor Devices for ICs

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Modern Semiconductor Devices for Integrated Circuits (C. Hu)Slide 3-1

Chapter 3

Device Fabrication Technology

About 1020 transistors (or 10 billion for every person in the

world) are manufactured every year.

VLS (Very Lar!e Scale nte!ration)"LS ("ltra Lar!e Scale nte!ration)

#S (#i!a$Scale nte!ration)

Variations of this versatile technolo!y are used for flat$paneldisplays% micro$electro$mechanical systems ( MEMS )% and

chips for &'A screenin!...


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Slide 3-2

3.1 Introduction to Device Fabrication

idation

Litho!raphy *

+tchin!

on mplantation

Annealin! *

&iffusion

Modern Semiconductor Devices for Integrated Circuits (C. Hu)


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Slide 3-3

Si ,afers

2

'2

-2 or ./+(trichloroethylene)

0uart1 tube

esistance$heated furnace

3lowcontroller

3.2 Oidation o! Silicon



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Slide 3-4


Si 4 2 → Si2

Si 42-2 → Si2 4 2-2

&ry idation 5

,et idation 5



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Slide 3-

E"#M$%E & T'o()tep Oidation

(a) How long does it take to grow 0.1 µ m of dry oxide at 1000 oC ?

(b) After step (a), how long will it take to grow an additional

0. µ m of oxide at !00 oC in a wet ambient ?

Solution5

(a) "rom the #1000oC dry$ %&r'e in lide *, it takes .+ hr to

grow 0.1 µ m of oxide.

(b) se the #!00oC wet$ %&r'e only. -t wo&ld ha'e taken 0.hr to

grow the 0.1 µ m oxide and ./hr to grow 0. µ m oxide frombare sili%on. he answer is ./hr0.hr 2 1.hr.




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Slide 3-!

3.3 %ithography

esist /oatin!(a) &evelopment(c)

+tchin! and esist Strip(d)

6hotoresist

ide Si

+posure(b)

Si

Si

6ositive resist 'e!ative resist

Si

Si

ptical

Lens system

&eep "ltraviolet Li!ht

6hotomas7 with

opa8ue andclear patterns



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Slide 3-"

3.3 %ithography

Photolithography Resolution Limit, *

9 3 ≥ k λ due to optical diffraction9 ,avelen!th λ needs to be minimied. (2:; nm% 1? nm@)9 k (


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Slide 3-#

3.3 %ithography

,afers are bein! loaded into a stepper in a clean room.



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Slide 3-1*

eflective photomas7B

Laser produced

plasma emittin!

+"V

Etre,e - %ithography /13n, 'avelength0

'o suitable lens material at this

wavelen!th. ptics is based on mirrors

with nm flatness.



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Slide 3-11

9 Electron ea, +riting 5 +lectron beam(s) scans and eposed

electron resist on wafer. eady technolo!y with relatively lowthrou!hput.

9 Electron $roection %ithography 5 +poses a comple

pattern usin! mas7 and electron lens similar to optical litho!raphy.

9 ano(i,print 5 6atterns are etched into a durable material to

ma7e a stamp.B his stamp is pressed into a li8uid film over

the wafer surface. Li8uid is hardened with "V to create animprint of the fine patterns.

eyond Optical %ithography



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Slide 3-12

3.4 $attern Tran)!er5Etching

Isotropic etching Anisotropic etching

Si2

Si2

Si2

(1)

(2)

photoresist

p h o t o r e s i s t

Si2

( 1 )

( 2 )

photoresist

p h o t o r e s i s t

Si2

Si2



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Slide 3-13


/ross$section View op View

*eactive(Ion Etching Sy)te,)

#as nlet

3 Vacuum

,afers#as Caffle

3



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Slide 3-14


Dry Etching /al)o 6no'n a) $la),a Etching7 or

*eactive(Ion Etching0 is anisotropic.

9 Silicon and its compounds can be etched by plasmas

containin! 3.9 Aluminum can be etched by /l.9 Some concerns 5

$ Selectivity and +nd$6oint &etection

$ 6lasma 6rocess$nduced &ama!e or ,afer /har!in!&ama!e and Antenna +ffect



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Slide 3-1

Scanning electron ,icro)cope vie' o! a pla),a(etched

8.19 , pattern in polycry)talline )ilicon !il,.



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Slide 3-1!

3.: Doping 3.5.1 Ion Implantation

9 he dominant dopin! method9 +cellent control of dose (cm$2)

9 #ood control of implant depth with ener!y (DeV to EeV)9 epairin! crystal dama!e and dopant activation re8uires

annealin!% which can cause dopant diffusion and loss of

depth control.

&opant ions



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Slide 3-1"

3.5.1 Ion Implantation

Sche,atic o! an Ion I,planter



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Slide 3-1#

3.5.1 Ion implantation

6hosphorous density profile after

implantation



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Slide 3-1$

3.5.1 Ion Implantation

Model o! I,plantation Doping $ro!ile /;au))ian0

22 2F)(

)(2)( 3 3 xi e

3

4 x 4 ∆−−

⋅∆⋅

=π

4 i 5 dose (cm$2)

3 5 ran!e or depth∆ 3 5 spread or si!ma



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Slide 3-2*

Other Doping Method)

9 ;a)(Source Doping 5 3or eample% dope Si with 6

usin! 6/l=.

9 Solid(Source Doping 5 &opant diffuses from a dopedsolid film (Si#e or oide) into Si.

9 In(Situ Doping 5 &opant is introduced while a Si

film is bein! deposited.



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Slide 3-21

3.9 Dopant Di!!u)ion

5t xo e 5t

4 t x 4 :F2

)%( −

⋅=

π

4 5 4 d or 4 a (cm$=)

4 o 5 dopant atoms per cm2t 5 diffusion time

5 5 diffusivity% is the approimate distance of

dopant diffusion

5t

p$type Si

Si2

n$typediffusion layer

Gunction depth



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Slide 3-22


9 Some applications need

very deep Hunctions (hi!h

% lon! t ). thers needvery shallow Hunctions

(low % short t ).

9 5 increases with

increasin! temperature.



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Slide 3-23


Shallo'


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Slide 3-24

3.= Thin(Fil, Depo)ition

Three >ind) o! Solid

/rystalline 6olycrystalline

+ample5

Silicon wafer hin film of Si or metal. hin film of

Si2 or Si= ':.

Amorphous



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Slide 3-2

3.= Thin(Fil, Depo)ition

9 Advanced ES3+ !ate dielectric

9 6oly$Si film for transistor !ates

9 Eetal layers for interconnects

9 &ielectric between metal layers

9 +ncapsulation of /

+amples of thin films in inte!rated circuits



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Slide 3-2!

3.7.1 Sputtering

ar!et materialdeposited on wafer

S i , a f e r

on (Ar 4)

Sputterin! tar!et

Atoms sputtered out of the tar!et

Sche,atic Illu)tration o! Sputtering $roce))



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Slide 3-2"

3.7.2 hemical !apor "eposition #!"$

hin film is formed from !as phase components.



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Slide 3-2$

wo types of /V& e8uipment5

9 LP!" #Lo% Pressure !"$ 5 #ood uniformity.

"sed for poly$Si% oide% nitride.

9 P&!" #Plasma &nhanced !"$ 5 Low temperature

process and hi!h deposition rate. "sed for oide%

nitride% etc.




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Slide 3-3*

Si ,afers

uart tube

esistance$heated furnace6ressure sensor

#as control Source !ases

6ump

rap ehausto

system

L6/V& Systems




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Slide 3-31


6+/V& Systems

/old ,all 6arallel 6late

-ot ,all 6arallel 6late

6ump

6lasma +lectrodes

6ower leads

,afers

#as

nlet

,afers#as nHection

in!6ump

-eater /oil



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Si2

Si2

Substrate

Si2

Si2

Substrate

& p i ' i l m

(b)

Substrate

Substrate

&pi 'ilm

(a)

Si Si

Si Si

Slide 3-32

3.7.3 &pita(y /Depo)ition o! Single(Cry)talline Fil,0

+pitay Selective +pitay



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Slide 3-33

3.? Interconnect 5 The ac6(end $roce))

&opant diffusion re!ionSi

Si)2

Al$/u

(a)

Sidiffusion re!ion

/oSi2

* etal 1

*etal 2

* etal 3

&ielectric

&ielectric

+ncapsulation

(b)

&ielectric

via or plu!

silicide

Al or /u



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Slide 3-34

SEM& Multi(%evel Interconnect /a!ter re,oving the dielectric0




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Slide 3-3

Copper Interconnect

9 Al interconnect is prone to voids formation by

electromi!ration.

9 /u has ecellent electromi!ration reliability

and :0K lower resistance than Al.

9 Cecause dry etchin! of copper is difficult (copper

etchin! products tend to be non$volatile)% copper

patterns are defined by a da,a)cene process.




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Slide 3-3"


$lanari@ation

9 A flat surface is hi!hly desirable for subse8uent

litho!raphy and etchin!.

9 /E6 (/hemical$Eechanical 6olishin!) is used

to planarie each layer of dielectric in the

interconnect system. Also used in the front$end

process.



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Slide 3-3#

3.A Te)ting7 #))e,bly7 and Buali!ication

9 ,afer acceptance test9 &ie sortin!9 ,afer sawin! or laser cuttin!9 6ac7a!in!

9 3lip$chip solder bump technolo!y9 Eulti$chip modules9 Curn$in9 3inal test

9 ualification



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Slid 3 4*

Eetal

etchin!

/V&

nitride

deposition

Litho!raphy

and etchin!

Cac7 Sidemillin!

Cac7 sidemetalliation

&icin!% wire bondin!%

and pac7a!in!

3.18 Chapter Su,,ary5# Device Fabrication Ea,ple

Si2 Si2

6 '4

(;)

(

Ch. 3 Lecture Slides for Chenming Hu book: Modern Semiconductor Devices for ICs

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Transcript of Ch. 3 Lecture Slides for Chenming Hu book: Modern Semiconductor Devices for ICs