I. II. III. & C-Vocw.sogang.ac.kr/rfile/2011/course10-spt/1산화... · · 2011-12-29W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes 산화 공정 I

W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes

I. II. III. & C-V IV.

1


I.

1. 1) T < 200 :

: ethylene glycol + KNO3 : SiO2 , Si + O2 : coverage, stoichiometric : PECVD, SiH4/N2O, TEOS

2) 250 < T < 600 : SiH4, O2, N2 ~400 SiO2 for passivation doped SiO2 by B2H6 , PH3

2


3) 600 < T < 900

TEOS (tetra-ethyl-orthosilicate) SiH4 SiCl4 + CO2

Why TEOS ?

4) 900 < T < 1200 : thermal oxidation

Cl incorporated oxidation

3


2. 1)

45 % silicon oxidation 100 % SiO2

4


2)

5


3)

6


7


3. mechanism 1)

For steady state F1 = F2 = F3 F1 = hG (CG- CS ) -----------(1-1) hG : Henry Co = HPS, C* = HPG ------- (1-2) CG = PG /kT, CS = PS /kT -(1-3) F1 = h (C*-Co) (h = hG /HkT)

PG

PS

8


F2 = D(Co - Ci )/Xo (Fick's law)

D : O2 SiO2

Ks :

F3 = KsCi

D = f (O2, T, )

D ; small, Ci 0 and Co C*: diffusion controlled

D ; large, : reaction controlled )hK1(CCC s*

oi +=

DXK

hK1

CCoss

*

i

++=

DXK

hK1

C)DXK1(

Coss

*os

o

++

+=, - - - (1-4)

9


: G

( F : flux of oxidant reaching the SiO2-Si interface)

N :

In oxide 2.31022 SiO2 molecules/cm3

for dry oxidation

N=2.31022 O2 molecules/cm3

for wet oxidation

N=22.31022 H2O molecules/cm3

DXK

hK1

CKdt

dXNFoss

*so

++==

dtdXG o= ------(1-5) ,

10


Xo2 + AXo=B(t+) - - - - - - - - - - - - - - - - - - - (1-6) (1-6)

1) 2)

N2DCB,)h1K12D(A

(0)XX,B

AXX

*

s

0i

2i i

=+=

=+

=

1B4A

t12A

X 212

o

++=

constantgrowthlinear:AB,)t(

ABXo +=

constantgrowthparabolicBBtX 2o :,=

>>>> t,B4At 2

B4At 2


2) H2O O2 103

Cl

4HCl + O2 =2H2O+ 2Cl2 (A, B )

Cl ( )

12


3)

parabolic

: Ea = 28.5 kcal/mol O2 Ea = 27 kcal/mol : Ea = 16.3 kcal/mol H2O Ea = 18.3kcal/mol

13


linear

14


4.

1) (m) =

2) (DSiO2/DSi) DSiO2>>DSi m

3) (B/D)

Si

SiO2

15


16


17


18


4) () : Boron

P, As, Sb 10 Ga 20 B 0.3

]kT

)eV(33.0exp[4.13meff =

]kT

)eV(66.0exp[2.65)111(meff =

]kT

)eV(66.0exp[0.104)100(meff =

19


II.

1.

1)

1) 10:1 BHF(NH4F : HF =10:1)

2) TEOS Si(OC2H5)4 , tetra-ethyl-ortho-silicate, or

equivalently tetra-ethoxy-silane.

(g/) (/) (/sec)

TEOS CVD CO2 CVD

1.80 2.20

2.09 2.15 2.30 2.24 2.20

5.220.0 6 10 2 8 5 6

6.8 9.0 2 5

40 55 6 8

10 20 10 15

5 5

20


2)

(1)

:

[111] > [100], T < 900 [111] [100], T > 900 linear growth rate parabolic growth rate

: [111] > [100]

21


(3)

linear growth rate

.

(4) doping

C(P)>11020 atoms/cm3

silicon Ks .

(5)

B enhance .

( boron )

NDC2B

*

=

NC

hKhK

AB *

s

s

+=

22


1) 700 900 2) 35 ppm 1.751018 atoms/cm3, 2450 ppm 1.231020 atoms/cm3 doping .

oxide thickness:

0.7 m

oxide thickness:

0.2 m

23


24


25


3) , , , , ,

(1) : UV-visible photospectrometer, ellipsometer,

(2) ellipsometer

: SiO2 (1.46) Si(3.75)

(3) ,

(4) (pinhole) ,

26


(5) (etch rate)

( HF:HNO3:H2O = 15:10:100)

27


2.

1) masking material

2) (silicon )

3) ( 1018 cm)

4) doping source

5) gate (gate capacitor) gate length/oxide thickness :

1 m/250 , 0.5 m/150 , 0.2m/70 , 0.1 m/30

6) field oxide

28


III. & C-V 29

1. C-V :


1) C-V parameter : SiO2, Si

capacitor

Si profile

MOS capacitor threshold voltage

2) C-V

30

Siox CC

,,d

SiSi

ox

oxox X

CT

C ==A

Sisd qN

X 2=


- CFB : flat band capacitance

- Cmax : maximum capacitance

- VT : threshold voltage

- Cmin : minimum capacitance

- Xdmax : maximum depletion

- deep depletion

- C-V depending on frequency

31


3)

Ene

rgy

s q(x) qp

x

Ec

Ei EF Ev

)()( xEExq if =

32


max

xdX

AXqNQ da=

AXqNQ da=

xdX

aqN

( )xaFSi

dFaSi

Fs

d

Si

da

Si

dad

dFs

qNXXNq

Xfor

XqNwhenXqNXx

X

d

42

21

21)(

max2

max

max

2

max

max

max=+==

===

= :

F

ASi

d

SiSi

iFF

qNX

C

EEq

4(min)

)(

max

==

=

( ) 1min 41 += SiAFoxox

qNCCC

4) Capacitance

33


1

2/1

2

1

,111

+=

+=

+

=

SiAox

ox

FB

Si

D

oxASiox

ox

FB

qNqkTC

CC

LCNq

kTxC

2/1

2

=

A

SiD Nq

kTL : Debye length

( )SUBFaSiox

FFBT

T

oxoxox

fMSFB

AFSiox

FFBoxdFFBT

VqNC

VV

dxxTx

CCQ

V

NC

VCQVV

ox

+++=

=

++=++=

2212

)(1

4122

0

34


35


36


37


38


2. C-V

39


1) :

: Na+, Li+, K+

: 10101012 /cm2

: , , , , Al, DI wafer

40

(Fixed Oxide Charge)

(Interface Trapped Charge)

(Mobile Oxide Charge)

(Oxide Trapped Charge)

Qf Qit Qm Qot

Nf Nit Nm Not


(a) 300 , +

(b) 300 ,

41


2) HTB (high temperature bias) : 250350

: (1 MV/cm10 MV/cm)

: 5

Note : C-V (+) stress

2 C-V () stress

3 C-V 30

minority

42


3) Qm Nm

Qm : gettering

43

oox

oxmFB K

TQV

=

ox

ooxFBm T

KVQ =

)m(T1010.2V

qTKV

qQN

ox

10

FBox

ooxFB

mm

=

== [/]


4) Qf C-V Qf [100] < Qf [110] < Qf [111]

.

theory ()stress VFB : -VFB

Qf : anneal (gas, , ) Qf : Si dangling bond

44

)m(T1010.2)V(

qTK)V(

qQ

ox

10

MSFB

o

ox

oxMSFB

f

+=

+=

(/)


45


46


5) C-V

47


6) :

48


49


7) Si band gap surface trap level (1) Si-O bond ,

,

, .

(2) Qit : 350500, N2 anneal

450 H2(25%) + N2(75%) forming gas

2Al + 3H2O = Al2O3 + 3H2

H2 + 2Si = 2 Si-H

50


8) Qot :

e-beam evaporator X-ray

Qot : . N2 515 anneal

;

gettering

radiation .

N2/H2 anneal

51


IV. (Gettering)

1960

heavy ion

mobile ion

1. Mobile ion

1) PSG(phosphosilica glass)

PSG high solubility

50150 PSG layer

PSG polarization

PR poor adhesion

PSG H2O H3PO4

52


2) chlorine

NaCl, KCl, LiCl

HCl(1971) : ,

TCE(1972) : trichloroethylene

TCA(1980) : trichloroethane

900 1100 0.51.0 % TCA

, minority carrier ,

,

53


54


55


2. bulk

1)

(Cu, Ag, Pt)

700 1019 phosphorus

/cm3 1020 phosphorus /cm3 1000

Cu dopant 10

wafer phosphorus .

BJT

switching Pt doping minority carrier

56


2) silicon defect

scratch

laser defect

ion implantation

Sirtl etcher[111] : 40 H2O + 20 HF + 15 mg Cr2O3

Secco etcher[100] : 1 H2O + 2 HF + 44 mg K2CrO7 3) Cl gettering

heavy metal Cl .

0.5~1.0% TCA .

defect TCA

57


1) diode

3. Gettering

58


2) solubility of Cu in 3) NPN transistor phosphorus doped Si

59


4) NPN BJT hFE

(a) (b)

60


5) PNP transistor

61

Slide Number 1I. Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19II. Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28 III. & C-V Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51IV. (Gettering)Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61

Documents

I. II. III. & C-Vocw.sogang.ac.kr/rfile/2011/course10-spt/1산화... · · 2011-12-29W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes 산화 공정 I