3.1 3 Process and Device Physics 1. Quantum-Theoretical Definition of Semicondu ctor 2. PN Diode 3. MOS(Metal-Oxide-Semiconductor) Capacitor Th eory 4. Ideal MOSFET : I-V Relations 5. Actual MOSFET(Secondary Effects) 6. CMOS Process 7. CMOS Layout Design Rules 8. SPICE Model for MOSFET Contents
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3.1 3 Process and Device Physics 1. Quantum-Theoretical Definition of Semiconductor 2. PN Diode 3. MOS(Metal-Oxide-Semiconductor) Capacitor Theory 4. Ideal.
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3.1
3 Process and Device Physics
1. Quantum-Theoretical Definition of Semiconductor
2. PN Diode
3. MOS(Metal-Oxide-Semiconductor) Capacitor Theory
4. Ideal MOSFET : I-V Relations
5. Actual MOSFET(Secondary Effects)
6. CMOS Process
7. CMOS Layout Design Rules
8. SPICE Model for MOSFET
Contents
3.2
1. Quantum Theoretical Definition of Semiconductor
Semiconductor No.1 Property;
Two charge carriers(electron & hole) existing in energy bands separated by Eg
Two important facts about semiconductor(or Semiconducting Crystal) ; Band Gap & Fermi Level
Band Gap(between Conduction & Valence band) Discrete energy levels in Isolated Quantum Well
E=0
Energy level
3.3
Perturbation of discrete energy levels in multiple QW’s in interacting distance(plus the effect of finiteness of energy wall)
Energy level becomes Energy band
Eg
(Energy Gap)
“nucleus”
EF(Fermi Level)
If the structure is non-periodic, the allowed energy levels constitute continuum.
3.4
Fermi Level(P(EF)=0.5 always)
According to Fermi-Dirac Statistics, P(E) = Probability of energy level, E being occupied by a particle, is
~1+exp[(E-EF)/kT]
1
T=0
E
P(E)
EF
E=0
Ec
Ev
full
empty
EgEF
T0
freeelectron
hole
nucleus
0.5P(E)
3.5
Fermi Level(cont’)
Impurity-doped Semiconductor ; electron & hole populations are unbalanced by doping n-type & p-type atoms, respectively.
(n-type Semiconductor)
Ec
Ev
EF
(p-type Semiconductor)
EF
Excesselectron
Phosphorus
Silicon
(n-type Semiconductor)
Deficit of electron=hole
BoronSilicon
(p-type Semiconductor)
3.6
2. P-N Diode
3.7
3.8
In Equilibrium, particle movement, in macroscopic sense, has stopped(i.e., no current flow in case of charged particle) ; therefore Fermi level is constant throughout all locations in equilibrium, i.e., connected and unbiased
(n-type Semiconductor)(p-type Semiconductor)
Ec
EF
EV
EFP
EFN
3.9
Forward bias :
P N
I
VF
Reverse bias :
VF
I
VB
V
VR
3.10
3. MOS Capacitor Theory
MOS Capacitor : combination of Metal, (Perfect Conductor), Oxide(Perfect Insulator in DC Sense, and good Dielectric in AC sense), and Semiconductor substrate.
(Oxide)
EFM
(metal)
(p-type silicon)
Ec
EFS,P
EV
M
S,P
(M) (O) (S)
: Minimal energy an electron needs to escape from inside metal(silicon) to air
Deple-tionRegion
P-Si
V
[V=0]
[separation]
M( S)
M S,P
3.11
flat-band conditionflat-band condition
V=VFB
VFB = MS - VFB = MS - Qfc
Cox
MS = M - S(Work Function Difference)
Qfc : Fixed charge per area
Cox : Oxide capacitance per unit area
Flat-band voltage(VFB)
3.12
Inversion conditionInversion condition
Xd
s
(M) (O) (P-Si)
Ec
Ei
EF
X=0
F
VT = VFB + 2F +QB
Cox
F = Ei - EF
q
QB = charge per unit surface area
= qNAXD
Threshold voltage (VT)
3.13
From Gauss’ Theorem, D = E= - (x)
xxxx AqN1
d)(1
)(E
)(V)(E xx
A
F
A
2A
qN
)(2ε2
qN
)(ε2
2ε
qN)0(V)s(
sxxx dd
2AA
ε2
qNN
ε
q )E(- )V( xxdxdxxx As ,
Fsdx 2qNε2qNQ AAB
Fsox
FFBTC
VV 2qNε21
2 A
3.14
)2qNε21
2 (A BSFsox
FFBT VC
VV
)0(
qNε2
)22(
0
0
As
BSTT
ox
FBSFTT
VVVC
VVV
: body effect constant
VBS = Bulk(Substrate) to Source (reverse) bias voltage
– Model parameters processed according to the device size start with ‘z’ follo
wed by the parameter name
Bias-Sensitivity Factors( start with ‘’ )
xu0= zu0 - zx2u0 vsb
xu1 = zu1 - zx2u1 vsb + zx3u1 (vds - VDDM)
1Leff
1LREFeff
1 1weff WREFeff
3.58
3.59
이 시대는 정보화시대라고 한다 . 이 시대에는 모든 사업의 성패가 적절한 정보의소유정도에 달려 있다 . 많은 사람들은 자기에게필요한 정보가 매우 얻기 힘들고 , 그것만 얻으면모든것이 다 해결된다고 생각한다 .이들은 자기가 이미 갖고 있는 정보를 다듬고생각하여 활용하는 것 보다는 ,오로지 쓸데도 없는 새로운 정보를 찾아숱한 시간을 날린다 .
이 시대는 정보화시대라고 한다 . 이 시대에는 모든 사업의 성패가 적절한 정보의소유정도에 달려 있다 . 많은 사람들은 자기에게필요한 정보가 매우 얻기 힘들고 , 그것만 얻으면모든것이 다 해결된다고 생각한다 .이들은 자기가 이미 갖고 있는 정보를 다듬고생각하여 활용하는 것 보다는 ,오로지 쓸데도 없는 새로운 정보를 찾아숱한 시간을 날린다 .
정보의 허상을좇는 것
정보의 허상을좇는 것
3.60
자기가 도저히 얻을 수 없는 정보나사람 , 혹은 매우 구하기 어려운정보나 사람이 없어서사업이 안 된다고 생각하는 사람을운명적 비관론자라고 부른다 .
자기가 도저히 얻을 수 없는 정보나사람 , 혹은 매우 구하기 어려운정보나 사람이 없어서사업이 안 된다고 생각하는 사람을운명적 비관론자라고 부른다 .