半導(dǎo)體制造技術(shù)導(dǎo)論（第二版）蕭宏 第7章 等離子體工藝

7.3等離子體系統(tǒng)7.4等離子體工藝7.5本章小結(jié)2023-05-271第7章等離子體工藝本章主要內(nèi)容7.1等離子體基本概念7.2等離子體參數(shù)7.1等離子體基本概念2本節(jié)主要內(nèi)容何為等離子體等離子體的用途等離子體的產(chǎn)生何為等離子體—定義3What

Is

Plasma？(什么是等離子體)

A

plasma(等離子體)is

a

ionized

gas(離化的氣體)

with

equal

numbers

of

positive

and

negative

charges

A

more

precise

definition(更準(zhǔn)確的定義):a

plasmais

a

quasi-neutral

gas(準(zhǔn)中性的氣體)of

charged(帶電的)and

neutral(中性的)particles

which

exhibitscollective

behavior(集體行為).何為等離子體—成分4A

plasma(等離子體)consists

of

neutral(中性的)

atoms(原子)or

molecules(分子),negative

charges(electrons)and

positive

charges(ions)Quasi-neutral(準(zhǔn)中性):ni

≈

neIonization

rate(離化率):ne/(ne

+nn)IonizationRate(離化率)

Ionization

rate(離化率)is

mainly

determined(決定)

electron

energy

in

plasma(等離子體)5Plasma

processing

chambers(等離子體工藝反應(yīng)室),thionization

rate(離化率)is

less

than

0.001%.

Plasma

etching

chambers(等離子體刻蝕反應(yīng)室),theionization

rate(離化率)is

about

0.01%.

High

density

plasma(e.g.,ICP感應(yīng)耦合等離子體,ECR電子回旋共振),the

ionization

rate

is

about

1%~

5%.何為等離子體—離化率等離子體的用途6Applications

of

Plasma(等離子體用途)CVD(化學(xué)氣相淀積)Etch(刻蝕)PVD(物理氣相淀積)Ion

Implantation(離子注入)Photoresist

strip(剝離光刻膠)

Process

chamber

dry

clean(工藝反應(yīng)室干式清洗)Collision(碰撞)Ionization(離化)Excitation-Relaxation(激發(fā)—松弛)Dissociation(分解)……7等離子體的產(chǎn)生—碰撞Ionization(離化)

Electron

collides(碰撞)with

neutral(中性的)atom(原子)or

molecule(分子)Knock

out(擊出)one

of

orbital

electron(軌道電子)等離子體的產(chǎn)生—離化8Ionization(離化)等離子體的產(chǎn)生—離化(自由電子)9(軌道電子)(自由電子)(原子核)(原子核)Excitation-Relaxation(激發(fā)—松弛)

Different

atoms(原子)or

molecules(分子)havedifference

frequencies(頻率),that

is

why

differengases

have

different

glow(發(fā)光)colors.

The

change

of

the

glow(發(fā)光)colors

is

used

foretch

and

chamber

clean

process

endpoint(終結(jié)點(diǎn)).等離子體的產(chǎn)生—激發(fā)松弛10(原子核)11(原子核)(碰撞電子)Excitation

Collision(激發(fā)碰撞)(碰撞電子)(基態(tài)電子)(激發(fā)態(tài)電子)等離子體的產(chǎn)生—激發(fā)松弛12(基態(tài))Relaxation(松弛)(普朗克常數(shù))(激發(fā)態(tài))可見光UV等離子體的產(chǎn)生—激發(fā)松弛等離子體的產(chǎn)生—分解Dissociation(分解)

Electron

collides(碰撞)with

a

molecule(分子),itcan

break

the

chemical

bond(化學(xué)鍵)and

generatefree

radicals(自由基):Increasing

chemical

reaction

rate(化學(xué)反應(yīng)速率)Very

important

for

both

etch

and

CVD13等離子體的產(chǎn)生—分解(分子)14Dissociation(分解)(自由基)Plasma

Etch(等離子體刻蝕)

CF4

is

used

in

plasma(等離子體)to

generate(產(chǎn)生)

fluorine

free

radical(F自由基)for

oxide

etch(刻蝕)等離子體的產(chǎn)生—分解15Plasma

Enhanced

CVD(等離子體增強(qiáng)CVD)PECVD

with

SiH4

and

N2O(笑氣)PECVD

can

achieve(獲得)high

deposition

rate(淀積速率)at

relatively(相對)lower

temperature.等離子體的產(chǎn)生—分解16等離子體的產(chǎn)生—分解177.3等離子體系統(tǒng)7.4等離子體工藝7.5本章小結(jié)2023-05-2718第7章等離子體工藝本章主要內(nèi)容7.1等離子體基本概念7.2等離子體參數(shù)7.2等離子體參數(shù)19本節(jié)主要內(nèi)容平均自由程熱速度磁場中的帶電粒子玻爾茲曼分布平均自由程Mean

Free

Path

(MFP)

The

average

distance(平均距離)a

particle(粒子)cantravel

before

colliding(碰撞)with

another

particlen

is

the

density

of

the

particle(粒子濃度)

s

is

the

collision

cross-section

of

the

particle(粒截面)20平均自由程Exercise

分子直徑為4?，密度為5×1016

cm-3，請計(jì)算分子的平均自由程。MFP

=

1/[1.414×5×1016

×p(2×10-8)2]

=

0.011

cm2122平均自由程MFP

Illustration(MFP介紹)高壓情形低壓情形Question(問題)

Q:Why

does

one

need

a

vacuum

chamber(真空反應(yīng)室)to

generate(產(chǎn)生)a

stable(穩(wěn)定的)plasma?

A:在標(biāo)準(zhǔn)大氣壓下(760

Torr),電子的平均自由程很短，因此電子很難獲得足夠的能量離化氣

體分子。而當(dāng)電場很強(qiáng)時(shí)，等離子體將形成弧

光放電，而不是穩(wěn)定的輝光放電。23平均自由程熱速度Electron(電子)is

much

lighter(更輕)than

ion(離子

Electric

forces(電場力)on

electrons

and

ions(離子the

sameElectron

has

much

higher

acceleration(加速度)24Movement

of

Charged

Particle(帶電粒子)RF(射頻)electric

field(電場)varies(變化)quickl25electrons

are

accelerated(加速)very

quickly

whileions(離子)react(反應(yīng))slowly.

Ions(離子)have

more

collisions(碰撞)due

to

theirlarger

cross-section(橫截面)that

further(進(jìn)一步)

slowing

them

down(降低它們的速度)Electrons

move(移動(dòng))much

faster

than

ions(離子)

in

plasma(等離子體)熱速度熱速度Thermal

Velocity(熱速度)Electron

thermal

velocity(電子熱速度)*

k:波爾茲曼常數(shù)RF

plasma(射頻等離子體),kTe

is

about

2

eV*

mph,

miles

per

hour;

1

mph

=

4.4704

cm/s26Magnetic

Force

and

Gyro-motion(磁場力和螺旋運(yùn)動(dòng))Magnetic

force(磁場力)on

a

charged

particle(帶電粒

Magnetic

force(磁場力)is

always

perpendicular(垂直the

particle

velocity(粒子速度)

Charged

particle(帶電粒子)will

spiral

around(螺旋圍the

magnetic

field

line(磁力線),Gyro-motion(螺旋運(yùn)磁場中的帶電粒子27Gyro-motion(螺旋運(yùn)動(dòng))磁場中的帶電粒子28參數(shù)電子氬離子熱速度v

(cm/s)5.93×1073.46×104螺旋轉(zhuǎn)動(dòng)半徑r

(cm)at

B

=100

G=0.01

T0.0341.44Gyrofrequency(螺旋轉(zhuǎn)動(dòng)頻率)磁場中的帶電粒子Gyro

radius(螺旋轉(zhuǎn)動(dòng)半徑)29玻爾茲曼分布307.3等離子體系統(tǒng)7.4等離子體工藝7.5本章小結(jié)2023-05-2731第7章等離子體工藝本章主要內(nèi)容7.1等離子體基本概念7.2等離子體參數(shù)7.3等離子體系統(tǒng)32本節(jié)主要內(nèi)容離子轟擊直流偏壓離子轟擊33Ion

Bombardment(離子轟擊)

Electrons

reach(到達(dá))electrodes(電極)andchamber

wall(反應(yīng)室墻壁)first

Electrodes(電極)charged

negatively(帶負(fù)電),

repel(排斥)electrons

and

attract

ions(吸引離子).

The

sheath

potential(鞘層電勢)accelerates(加速)itowards

the

electrode(電極)and

causes(引起)ionbombardment(離子轟擊)Very

important

for

sputtering(濺射),etch

and

PECVD34離子轟擊Sheath

Potential(鞘層電勢)(暗區(qū))(鞘層電勢)(體內(nèi)等離子體)(鞘層區(qū))Applications

of

Ion

bombardment(離子轟擊的應(yīng)用)Help

control

film

stress(膜應(yīng)力)in

PECVD

processesHelp

to

achieve(獲得)anisotropic(各向異性)etch

prArgon

sputtering(氬離子濺射)35離子轟擊直流偏壓36Plasma

Potential

&

DC

Bias(等離子體電勢和直流偏壓)DC

biases

and

RF

powers(直流偏壓和射頻功率)(等離子體電勢)37Lower

RF

powerSmaller

DC

biasHigher

RF

powerLarger

DC

bias直流偏壓38直流偏壓(暗區(qū)或鞘層區(qū))DC

Bias

of

CVD

Chamber

Plasma(CVD反應(yīng)室等離子體的直流偏壓)(地)(射頻熱電極)DC

Bias

of

Etch

Chamber

Plasma(刻蝕反應(yīng)室等離子體的直流偏壓)直流偏壓39DC

Bias

of

Etch

Chamber

Plasma(刻蝕反應(yīng)室等離子體的直流偏壓)直流偏壓407.3等離子體系統(tǒng)7.4等離子體工藝7.5本章小結(jié)2023-05-2741第7章等離子體工藝本章主要內(nèi)容7.1等離子體基本概念7.2等離子體參數(shù)7.4等離子工藝42本節(jié)主要內(nèi)容等離子體工藝的優(yōu)點(diǎn)PECVD與等離子體刻蝕遙控等離子體工藝高密度等離子體工藝等離子體工藝的優(yōu)點(diǎn)43Plasma

processes(等離子體工藝):PECVD(等離子體增強(qiáng)化學(xué)氣相淀積)CVD

chamber

dry

clean(CVD反應(yīng)室干法清洗)Plasma

Etch(等離子體刻蝕)PVD(物理汽相淀積)Ion

implantation(離子注入)Benefits

of

Using

Plasma

For

CVD

Process(CVD工藝使用等離子體的優(yōu)點(diǎn))

High

deposition

rate(淀積速率)at

relatively(相對

lower

temperatureIndependent

film

stress

control(控制薄膜應(yīng)力)Chamber

dry

clean(反應(yīng)室干法清洗)44等離子體工藝的優(yōu)點(diǎn)—CVDComparison(比較)of

PECVD

and

LPCVD等離子體工藝的優(yōu)點(diǎn)—CVD4546Gap

Fill(間隙填充)

by

HDP-CVD等離子體工藝的優(yōu)點(diǎn)—CVD0.25

mm,深寬比=4:147Benefits

of

Using

Plasma

For

Etch

Process(刻蝕工藝使用等離子體的優(yōu)點(diǎn))High

etch

rate(刻蝕速率)Anisotropic(各向異性)etch

profile(形狀)Optical

endpoint(光學(xué)終點(diǎn)監(jiān)測)Less

chemical(化學(xué)制品)usage

and

disposal(處理)等離子體工藝的優(yōu)點(diǎn)—刻蝕Benefits

of

Using

Plasma

For

PVD

Process(物理汽相淀積使用等離子體的優(yōu)點(diǎn))Argon

sputtering(氬離子濺射)Higher

film

quality(膜質(zhì)量)—Less

impurity(雜質(zhì))and

higher

conductivityBetter

uniformity(均勻性)Better

process

control(工藝控制)Higher

process

integration(工藝兼容)capabilityEasier

to

deposit

metal

alloy

films(合金薄膜)48等離子體工藝的優(yōu)點(diǎn)—PVD49PECVD與等離子體刻蝕PECVD

and

Plasma

Etch

Chambers(PECVD和等離子體刻蝕反應(yīng)室)CVD:Adding

materials(添加材料)on

wafer

surfaceFree

radicals(自由基)Some

bombardment(轟擊)for

stress(應(yīng)力)controlEtch:Removing(去除)materials

from

wafer

surfaceFree

radicals(自由基)Heavy

bombardment(轟擊)Prefer

low

pressure(低壓),better

directionalityof

ions50PECVD與等離子體刻蝕Schematic

of

a

PECVD

ChamberElectrodes(電極)have

about

the

same

area(相同面積The

ion

bombardment(轟擊)energy

is

about

10

to

20

eV51PECVD與等離子體刻蝕Schematic

of

an

Etch

Chamber(工藝氣體)(磁場線圈)(真空泵抽走副產(chǎn)物)(氦氣冷卻晶圓背面)Plasma

Etch

ChambersIon

bombardment

energy(離子轟擊能量)on

wafer

(RF

hot

electrode):

200

to

1000

eVon

lid(蓋子)(ground

electrode):10

to

20

eV.Ion

bombardment(離子轟擊)Physically

dislodge(物理移除)break

chemical

bonds(打破化學(xué)鍵)Heat

generation(熱產(chǎn)生)Need

to

protect

masking

PR(掩膜光刻膠)Helium(氦氣)backside

cooling

required52PECVD與等離子體刻蝕Plasma

Etch

ChambersEtch

prefer

lower

pressure(低壓)longer

MFP(平均自由程)more

ion

energy(能量)and

less

scattering(散射)Low

pressure,less

ionization

collision(碰撞)hard

to

generate

and

sustain

plasma

Magnets(磁體)are

used

to

force(促使)electron

sp(電子自旋)and

travel

longer

distance

to

increasecollisions(碰撞)53PECVD與等離子體刻蝕遙控等離子體工藝—Plasma

Clean(等離子體清洗)54Remote

Plasma

Processes(遙控等離子體工藝Need

free

radicals(自由基)Enhance

chemical

reactions(增強(qiáng)化學(xué)反應(yīng))Don’t

want

ion

bombardment(離子轟擊)Avoid

plasma-induced

damage(損傷)Remote

plasma

systems(遙控等離子體系統(tǒng))Photoresist

Strip(剝離光刻膠)Plasma

Etch(等離子體刻蝕)55遙控等離子體工藝—?jiǎng)冸x光刻膠(有光刻膠的晶圓)(加熱平板)Photoresist

Strip

Process(剝離光刻膠工(微波)(遠(yuǎn)端等離子反應(yīng)室)Remote

Plasma

Etch(遙控等離子體刻蝕)Isotropic

etch

processes(各項(xiàng)同性刻蝕工藝):LOCOS

or

STI

nitride

strip(剝離氮化物)wineglass

contact

hole

etch(酒杯狀接觸孔刻蝕)Part

of

efforts

to

replace(取代)wet

process(濕法工56遙控等離子體工藝—等離子體刻蝕遙控等離子體工藝—等離子體清洗Remote

Plasma

Clean(遙控等離子體清洗)(微波)(遠(yuǎn)端等離子反應(yīng)室)57(加熱平板)Remote

Plasma

CVD

(RPCVD)Epitaxial(外延)Si,GeDielectric(介質(zhì)):SiO2,SiON,and

Si3N4High-k

dielectrics:

HfO2,

TiO2,

and

Ta2O5PMD(金屬淀積前介質(zhì))barrier

nitrideLPCVD:budget

limitations(熱預(yù)算限制)PECVD:plasma

induced

damage(損傷)58遙控等離子體工藝—等離子體CVDHigh-density

Plasma(高密度等離子體)

Etch

and

CVD

desire(需要)high-density

plasma

atlow

pressure(低壓下高密度等離子體)

Lower

pressure(低壓),less

ion

scattering(散射),

enhances(增強(qiáng))etch

profile(刻蝕輪廓)controlHigher

density,more

ions

and

free

radicals(自由基)Enhance

chemical

reaction(化學(xué)反應(yīng))Increase

ion

bombardment(離子轟擊)CVD

processes,dep/etch/dep

enhance

gap

fill(填空隙59高密度等離子體工藝Limitation

of

Parallel

Plate

Pla