11
Contact Info.Contact Info.
• Name: Wing Leong, Chung (Zhong Rongliang, 锺荣亮 )
• Email: [email protected]• Tel: 2358 7211• Rm: 2130A
• Name: Wing Leong, Chung (Zhong Rongliang, 锺荣亮 )
• Email: [email protected]• Tel: 2358 7211• Rm: 2130A
22
Examination
• Time 120 mins• Open Book• Passing Marks:
• 2 Qualify Question • Part I 25 mc 60% (Safety)• Part II 25 mc 60% (Operation)• Part III 2 PF 60% (Process Flow)
• 5 mistakes / PF
NFF Operation TrainingNFF Operation Training
Introduction 概引
Introduction 概引
44
Introduction 概引
• Contamination and Control 污染與管制
• Process Flow 工藝流程• Do’s and Don’t’s 規矩• Discussion on Exam Questions 考題
討論• NFF Tour 參觀實驗所
NFF Operation TrainingNFF Operation Training
Contamination and Control 污染與管制
Contamination and Control 污染與管制
66
Research in NFF微電子實驗所的科研項目
• Sub-micron SOI• Display Technologies• MEMS• Integrate Power System• Advanced Packaging Program• Advanced Process Module
Developing• Sensor Technology• Gene Chip• Compound Semiconductor
Technology• Novel Magnetic – electronic
devices
• 亞微米 SOI• 顯示技術• 微機電系統• 集成功率系統• 先進封裝程序• 先進工藝模塊發展• 傳感器技術• 基因晶片• 化合物半導體技術• 新微電器件
77
Outline
• Contamination• Process Verification
Scheme• Cleanliness Levels• Process
Compatibility• Wafer Status
• General Processing Requirements of Individual Modules
• 污染
• 工藝驗証指引• 潔淨級別• 工藝兼容性• 晶片潔淨指數
• 個別模組的要求
88
What is contamination 何謂污染
• Contamination is the intrusion of impurities into devices that leads to their failure
• Examples:• Degradation of Oxide
Integrity• Threshold Voltage
Shift• Leakage
• 污染:器件因雜質而導致功能失效
• 例如:• 氧化層失效
• 國值電壓漂移
• 漏電
99
Knock-on Effect
Bath for Resist Strip
Contaminants
CleaningBath
Tools e.g.Cassette
Furnace A
Furnace B
Etcher A
Bath for Resist Strip
1010
Why contamination matters to you?
污染與我可干?• It’s like disease, easy
to spread across the laboratory
• It’s hard to be stopped once caused
• Any contamination you cause ruins others’ years of efforts
• You are the only one who can help us stop it from spreading
• 有如瘟疫一般,易於傳播到實驗的每個角落
• 一旦發生,難以制止
• 因你做成的污染,可把別人多的努力毀於一旦
• 可以幫助我們阻止污染傳播開去的,只有你!
1111
3 Commonest CMOS KillersCMOS 三煞
• Metallic Contaminants• Ions of heavy and transition m
etals (Au, Ag, Pt, Ni)• Ions of standard Metal (Al, Ti)• Alkali Ions (K, Na)
• Orgnaic• Photoresist and Polymers• Body Oil
• Particles• Carbon• Metal pieces from lifted-off wa
fers• You name it
• 金屬污染物• 重金屬和過渡金屬 ( 金、
銀、白金、鎳 ) 的離子• 常規金屬的離子 ( 鋁、鈦 )• 鹼性離子 ( 鉀、鈉 )
• 有機污染物• 光刻膠和聚合物• 體液
• 微粒• 炭• 剝離了的金屬碎片• 不能盡錄
1212
Contamination Control污染管制
• NFF Policy and Rules
• Process Verification Scheme
• Processing Requirements of individual modules
• Your awareness and observance
• 政策與規則• 工藝驗証指引
• 個別模組要求的工藝規格
• 你對污染的關注與規則的尊從
1313
NFF Policy and Rules政策與規則
• All Users• General Cleanroom
Rules and Regulations
• Non-CMOS Users• Process Flow• Satisfactory
Completion of Training Courses
• CMOS Users• Non-CMOS Users’
requirement• ELEC508 or Equivalent
• 所有實驗所的使用者• 一般無塵房的規則
• Non-CMOS 使用者• 工藝流程• 訓練合格
• CMOS 使用者• 符合 Non-CMOS 使用者的
要求• 完成 ELEC508 或同等經驗
1414
Process Verification Scheme 工藝驗証指引
• Every thing in NFF• Chemicals• Materials• Wafers• Equipment and
Machines
• Classified by• Contamination Risks• Process Compatibility
• 7 equipment Combination
• 4 Wafer Statuses
• 所有在實驗內的東西• 藥品• 物料• 晶片• 機台
• 按以下因素分類• 污染風險• 工藝兼容性
• 7 種機台的組合• 4個晶片潔淨指數
1515
What’s Risk
+Al
+Na
Al
Si Wafer
Au
Low Risk
High Risk
<<
<<+
Au
1616
Contamination Risks and 3 Cleanliness Levels污染風險與三個潔淨級別
• Clean (Lowest)• No contaminants
• Semi-Clean (Medium)• Ions of standard
materials such as Al, Cr, and Ti
• Non-Standard (Highest)• Ions of gold, copper, Ga
As, Ga Nitride, K, Na and materials/chemicals not yet classified
• 潔淨 (最低風險 )• 無污染物
• 半潔淨 (中度風險 )• 常規金屬如鋁、鉻和鈦的
離子• 非常規 (最高風險 )
• 非常規物質如金、銅、砷化鎵、氮化鎵、鉀、鈉和未分曾分類的物料或藥品的離子
1717
Process Compatibility工藝兼容性
• CMOS Compatible• Front End Processes
of ELEC508, PMOS, NMOS, and SOI
• Non-CMOS Compatible• MEMS• CMOS back-end
process• You Name it
• CMOS 兼容• ELEC508 、 PMOS 、
NMOS 和 SOI 的前工藝
• 非 CMOS 兼容• 微機電系統• CMOS 的後工藝• 不能盡錄
1818
3 Cleanliness + 2 Compatibilities = 4 Wafer Statuses 三個潔淨級別 + 兩種工藝兼容性 = 4 種晶片潔淨指數
Clean潔淨
Semi-Clean半潔淨
Non-Standard非常規
CMOS
Non-CMOS
Both兼用
CleanCMOS
CleanNon-CMOS
CleanCMOS/Non-CMOS
CleanCMOS/Non-CMOS
Clean/Semi-cleanCMOS/Non-CMOS
Clean/Semi-cleanCMOS/Non-CMOS
Semi-cleanNon-CMOS
Non-StandardNon-CMOS
Semi-clean/Non-StandardNon-CMOS
Semi-clean/Non-StandardNon-CMOS
+ 7 Combinations+ 7 Combinations+ 7+ 7 個組合個組合
1919
• Downward Compatible• CMOS -> Non-CMOS• Clean -> Semi-clean or Non-standard• Semi-clean -> Non-standard
• But not the Reverse• Non-standard -> Semi-clean ->
Clean• Once contaminated always
contaminated• Exceptions:
• Decontaminated MILC Wafers• Decontaminated wafers after Post
CMP Grinding Cleaning
• 向下兼容• CMOS -> Non-CMOS• 潔淨 -> 半潔淨或非常規• 半潔淨 -> 非常規
• 不准掉頭• 非常規 -> 半潔淨 -> 潔淨• 一被污染,永遠污染
• 例外情況:• 經過除污的金屬誘導橫向晶體化
的晶片• 經過除污的化學機械拋光晶片
Mechanism of PV Scheme工藝驗証指引的機制
2020
Decontamination除污工藝
• Wafer Status after decontamination• Clean Non-CMOS
• Not for:• Non-standard
Wafers• Almost all Semi-
Clean Wafers
• Not necessary for Non-CMOS users
• 除污後的晶片潔淨指數
• 潔淨 NON-CMOS
• 不合於:• 非常規晶片• 大部份半潔淨晶片
• NON-CMOS 使用者一般不須用此工藝
2121
Processing Requirements of individual processes個別模組要求的工藝規格
• Wetstations• Oxidation,
Diffusion and CVD• Implantation• Dry Etching• Sputtering• Photolithography
• 濕化工藝台• 氧化、擴散與化學汽相澱積
• 離子注入• 乾化蝕刻• 濺射• 光刻
2222
Wetstations 濕化工藝台
• General Safety• No chemicals bottle left on the floor• Wafers have to be dump-rinsed in
the dump-rinser for at least 4 cycles immediately after any chemical processes
• No organic solvent (IPA, Acetone)• HF
• Highly hazardous Chemical Solutions (HF, BOE, 777 and Freckle etch)
• Concentration below 20% is more insidious and symptoms may be delayed for up to 24 hours
• Use of Chemical• Unconventional use of chemical requ
ires permission and booking. • Mixing own chemicals is only allowed
at semi-clean or non-standard wetstation
• Disposal• HF, Freckle Etch and BOE are needed
to be drained into the HF tank by NFF staff.
• Acid and Base are needed to be drained by users themselves with an aspirator
• Contamination• No Glass, Metals and Manual coate
d wafers at CLEAN wetstations• No Metals at the sulfuric acid bath
for resist stripping• Separation of cassettes, tools cont
ainers and gloves from those of different stations
• No lifted-off wafers put in baths• No mess left at wetstations
2323
Layout of Wetstations濕化台的分佈
2424
Labels of Wet-stations每個濕化台所用的記號
Lowest
Highest
Risks of C
ontamination
A:CMOS Cleaning Station
C:Oxide and nitride etch
B:Non-CMOS Cleaning Station
G:TMAH Etching Station
E:Semi-clean Non-metal Processing Station
D:Standard metal processing Station
Y:Semi-clean Organic Stripper
Z:Semi-clean Develop Station
Z2:Semi-clean/Non-standard Dump Rinser
F:Non-standard Processing Station
J:ASTRI’s Station (for ASTRI only)
2525
Summary of Wetstation Arrangement濕化台的調度
Non-Standard
Semi Clean
Clean
Non-Std Chemicals /Materials
Start
Ti-Silicide?
Wet-stations D, E
Liftoff?
Dump Rinsers ofWet-station FBath Z2
Std Metalse.g. Al/Cr/
Ti
CMOS?
Wet-Station D Wet-stations D, E
“Decontamina-table”
Wet-station X, G, Cand A
Yes Yes
Yes
Yes
Yes
No
No
No
No
No
Wet-station X, G, C and B
B3:Decontamination
Yes
No
Wet-station FBath Z2
Dow
nw
ard
Com
patib
leD
ow
nw
ard
Com
patib
le
Once contaminated by Non standard group (except Z2) cannot pass this line
Once contaminated by semi-clean group cannot pass this line
To find which baths you are allowed to use, look at the process historyTo find which baths you are allowed to use, look at the process history
2626
Oxidation, Diffusion and CVD 氧化、擴散與化學汽相澱積
• Wafer Substrates• Thickness• Full Wafers Preferred• Appropriate Cleaning
Processes• No Photoresist• No organic• No metals for most
furnaces• No wafers of
uncertain background
• 晶片材料• 厚度• 完整一片的晶片較合• 用適當的工藝清洗晶片• 不許有光刻膠• 不許有有機物• 大部份爐都不可入金屬• 不許有來歷不明的晶片
2727
Implantation離子注入
• Full wafers without chips and cracks
• Spices (B, BF2, As, P, H)
• Dosage• High Temperature
Photoresist• Wafers with no resist
on the rim and back side
2828
Dry Etching 乾化蝕刻
• Materials to etch (Oxide, Nitride, Si, Poly, some metal, compound Semiconductor)
• Thickness to etch• Full Wafers Preferred• Single Side Photoresist
Coating• No wafers with edges
wrapped with photoresist.
2929
Sputtering 濺射
• Limited Target Materials
• Thickness < 5000A• Full Wafers Preferred• No photoresist nor b
roken wafers on Semi-clean Sputterers
• Lift-off wafer in Non-Std sputterers only
• 濺射靶的材料是有限制的
• 一般厚度不多於 5000A
• 完整晶片較合
3030
Photolithography光刻
• Contamination caused by photoresist
• Inhalation of Organic Vapors and Solvent (HMDS, Photoresist)
• No acid nor base in Yellow Room
• Coater and developer Tracks not for double-side photoresist coating, and negative photoresist
• Disposal of Waste (IPA, Acetone)• Pour the waste into waste
collection bottles• Don’t use an aspirator to
suck it into the N-tank• Be careful of EKC,
which is a highly corrosive solvent
• Containers used for developing or any process require booking on the computer system.
• Transparency only allow on AB-M 2
3131
Contamination arising from Integration
• Inter-level Contamination• Caused by contaminants from incompatible cleanliness g
roups• E.g. Non-standard group contaminates Semi-clean group
• Intra-level Contamination• Caused by contaminants from the same cleanliness level• Heavily Doped Photoresist/PSG Vs some CLEAN equipme
nt• Cr/Al/ITO vs Some SEMI-CLEAN equipment • PCB boards vs Non-Standard Sputterers
• Extra-level Contamination• Caused by contamination sources other than the above• E.g. Photoresist, Particles, Body Oils, to name but a few
NFF Operation TrainingNFF Operation Training
Process Flow工藝流程
Process Flow工藝流程
3333
Outline
• Aim• Standard Format • Common Mistakes• Process
Guidelines
3434
Aim of Process Flows
• Functions:• Help you to plan ahea
d• Track down wafer mo
vement • Reduce uncertainty• keep the unqualified
away from NFF• Aim:
• Control Contamination
3535
Sample Process Flow
3636
Standard Format
• Heading• Cross-sections• Wafer Status• Step no.• Equipment• Cleanliness• Compatibility• Processes• Requirements
3737
Mistake 1 - Oversimplification
3838
Mistake 2 – Wrong Initial Wafer Status
3939
Mistake 3 – Incompatible equipment Status
4040
Mistake 4 - Double-side PR Coating
4141
Mistake 5 – Wrong PR Stripping
4242
Other Mistakes
• Mistake 6 - Misuse of low stress nitride as oxidation masks
• Mistake 7 – Misuse of Decontamination
• Mistake 8 – Wafer Edge Coating
• Mistake 9 – missing backside rinsing prior to implantation
4343
Process Guidelines
• 7 Cleanings• 4 Resist Stripping• Post-Deep Si Etch
Polymer Removal
• 3 Etchings to Etch Through Wafers
• Liftoff• Non-standard
Metal (Gold)
4444
Cleanings
• Sulfuric Clean (CMOS)• RCA2(Decontaminatio
n)• Pre-diffusion Clean (C
MOS)• Pre-deposition Clean
(CMOS)• Sulfuric Clean (Non-CM
OS)• Post-Metallization Clea
n• Mask Cleaning
4545
Sulfuric Clean (CMOS)
• CMOS Only • No photoresist, metals nor silicides
• A1:H2SO4:H2O2 + A2:HF:H2O 1:50• Removing organics and gross conta
minants e.g. scribe dust.• H2SO4 – reduces organics to carbon• H2O2 – oxidizes carbon to form CO2
4646
RCA2(Decontamination)
• CLEAN or Decontaminatable Wafers• No photoresist, metals• B3:H2O:H2O2:HCl at 70 ºC (fresh)• Drain after use• Removes metallic contaminants and alka
li ions• HCl – reacts with most metals to form solubl
e chlorides• H2O2 – acts as a buffer/oxidant
4747
Pre-diffusion Clean (CMOS)
• CMOS Only• No photoresist, metals nor silicides• Process:
• A3:H2SO4:H2O2 – cleans organics• Dump rinse• A2:HF:H2O (1:50)• Dump rinse• Spin Dry
• Prior to the growth of high quality oxide
4848
Pre-deposition clean (CMOS)
• CMOS only• No photoresist, metals nor silicides• Process:
• A1:Sulfuric Clean• Dump rinse• A2:HF:H2O (1:50) cleans native oxide
• Prior to deposition
4949
Sulfuric Clean (Non-CMOS)
• Clean MEMS only• No photoresist, metals nor silicides• B1:H2SO4:H2O2 + B2:HF:H2O 1:50• Removing organics and gross conta
minants e.g. scribe dust.• H2SO4 – reduces organics to carbon• H2O2 – oxidizes carbon to form CO2
5050
Post-Metal Clean
• Semi-clean• No non-standard materials esp.
Gold, nor samples undergone liftoff
• Process:- Clean wafers with Fresh MS2001 in
Bath Y2 (Optional)• Spin wafers Dry with Spin-dryer D
5151
Mask Cleaning
• Semi-Clean• Mask Only• Process:
• Y2:MS2001• Dump-rinse• Dry by an N2 Gun• Oven
5252
Resist Strips
• Sulfuric Acid (E4)• CLEAN• SEMI-CLEAN Without Met
als/ Silicides• MS2001 (Y1)
• Standard Metals• Semi-Clean
• O2 Ashers + Wet (E4, Y1)• High-temp Treated PR
• Non-Standard W2• Non-Standard
5353
Resist Strip (General)
• Semi-Clean and Clean• No metal nor silicide, nor ITO, nor heavily
doped/implanted photoresist, nor undensified doped LTO
• Process:• E4:Sulfuric Acid• Dump-rinse• Inspection
5454
Resist Strip (post implatation or high temp treatment)
• Semi-Clean and Clean• No metal nor silicides• Process:
• O2 Plasma ashing• E4:Sulfuric Acid/Y1:MS2001(it depends)• Dump-rinse• Inspection
5555
Resist Strip (Standard Metals)
• Standard Metals• No samples undergone liftoff• Process:
• Y1:MS2001• Dump-rinse• Spin Dry• Inspection
5656
Resist Strip (Non Standard)
• Standard Metals• No samples undergone liftoff• Process:
• W2:MS2001• Dump-rinse• Spin Dry• Inspection
5757
Post ICP Deep Silicon Etch Polymer Removal
• Clean CMOS/Non-CMOS• Wetstation X• Process
• EKC265 Stripper• 70 C• 20 mins• Inspection
5858
Etching Through Wafers
• Dry Etch• Deep-silicon Etcher• Under Installation
• KOH• Etching furiously • Non-standard
Process
• TMAH• CLEAN Process• Nitride + Oxide as
Etching Masks
5959
ICP Deep Silicon Etcher
Substrate
Sub- strate
Method 1 Method 2
Substrate
*8 um thick Photoresist
Oxide
Substrate
Scratches
Particles generated from here
*Note: The manual photoresist developing or polymer removal must be done at Wetstation X
6060
KOH Etching – Non-standard
Oxide Substrate
Nitride
Substrate
Photoresist
Substrate
strate Ideal
Scratches
What if resist is scratched away?
Sub-
ParticlesGeneratedFrom here
Sub-
6161
Sub-
TMAH Etching
Substrate
Nitride
strate
Oxide
Ideal
Photoresist
What if resist is scratched away?
Substrate
Substrate
ParticlesGeneratedFrom here Scratches
6262
Particulate - liftoff
Substrate
Substrate
Substrate
Photoresist
Photoresist
Photoresist Residue
Metal
Metal Residue
Step 1
Step 2
Step 3
6363
Particulate – liftoff (con’t)
• Guideline for liftoff process• Acetone, and IPA used should be poured
into dedicated waste bottles• Make it the last step• Once liftoff is done, the samples can’t
stop generating contaminants. • Don’t even think about putting samples
into any processing baths, That is extremely irresponsible!
6464
Metallic Contaminant – Gold
• Gold Ions• Most-Contaminating because of its high mob
ility• Easy to spread into the atmosphere, if heate
d• From films, equipment, tools, containers and
cassettes, which are in contact with Au+ ions• Totally incompatible with almost all process
es and equipment except for• Bath Z2• Wetstation F• Thermco E4: Thermal Anneal (Gold)
6565
Metallic Contaminant – Gold
• Guidelines for processing gold• Make it as close to the last step as
possible. Once samples are gold-contaminated, you are banned from doing almost all processes.
• Never put gold-contaminated samples into clean and semi-clean areas, (in particular sulfuric acid for resist stripping). Otherwise you will kill the whole laboratory!
NFF Operation TrainingNFF Operation Training
Do’s and Don’t’s 規矩
Do’s and Don’t’s 規矩
6767
Chemicals and Wetstations
• Don’t bring your own chemicals or materials into NFF unless you have approval
• Don’t take any chemicals or materials away. That is theft.
• Don’t leave chemical bottles on the floor
• Never put into CLEAN baths wafers that have undergone metallization.
• Don’t leave anything, especially incompatible materials, on the top of wet-stations.
• Disposal of HF and BOE must be done by trained persons
• Don’t be so irresponsible as to leave down the tools you have used and go away
• Don’t mix up the gloves, cassettes and tools of one station with those of others. You should look at the labels!
• Clean all the tools and containers you have used and place them back to where they are
• No ORGANIC Solvent at wetstations in Class 1000
• No acid and base in Yellow Room
6868
Operation
• Store wafers of different wafer status in separate boxes
• Always inspect your wafers after a resist strip to ensure cleanliness
• Don’t put non-standard materials, especially gold into semi-clean and clean baths
• Don’t put liftoff samples in any processing baths
• Always keep your samples in your own containers or cassette boxes in case they contaminate others or be contaminated.
• Always be careful with photoresist which is very contaminating.
• Arrange non-standard steps as close to the end of process flow as possible.
• After cleaning, wafers must go straight to furnaces without being touched by any objects
6969
Process Flows
• Plan before work. If you fail to plan you are planning to fail
• Write what you do and do what you write.
• Once your process becomes different from what you have planed, sumit us a new flow
• Never copy others’ process flow
• Never let others copy your process flow
• Do let us know, if you find your processes departing from our scheme.
• Proofread before submitting them
7070
Personal
• Don’t shortcut any policy and rules
• Keep yourself abreast of information about rules and regulations, as it is dynamic and subject to change.
• Report to us any mistakes you or others have made. Don’t hide it!
• be aware of contamination that you may cause and others cause
• Remember, this is a shared lab. Everyone must follow lab policy to keep it clean
• Use your judgment. Avoid contamination of wafers or equipment
• Don’t stay in the laboratory if not necessary. NFF is not a meeting place!
7171
Useful Webpages
• NFF User Guide (well underway)• Hook up to http://www.nff.ust.hk and then click on “Safet
y course registration” or• http://www.nff.ust.hk/mffdoc/index.htm
• NFF Booking System• https://www.nff.ust.hk/booking
• Material Request Form• Logon NFF Booking System and then click on “User Info”
• Other process information • http://mfk060.ust.hk
NFF Operation TrainingNFF Operation Training
Q&A答問時間
Q&A答問時間