Clean Room Class
• Class 10 is defined as less than 10 particles with diameter larger than 0.5 mm per cubic foot. • Class 1 is defined as less than 1 such particles per cubic foot. • 0.18 mm device require higher than Class 1 grade clean room.
Sale:
• 100% yield: 10000 - 2350 = $7650/wafer Profit • 50% yield : 5000 - 1850 = $3150/wafer Margin: • 0% yield : 0 - 1350 = - $1350/wafer
材料科學與工程學系 義守大學 – 助理教授 劉文仁
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Wafer Process Flow
Materials IC Fab Metallization Wafers Thermal Processes Masks Photolithography Design
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Ion Beam
Dopant in PR Particle Photoresist Screen Oxide
Partially Implanted Junctions
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Cleanroom Structure
Makeup Air Fans Makeup Air
Cost:
• 100% yield: 150+1200+1000 = $2350/wafer • 50% yield: 150+1200+500 = $1850/wafer • 0% yield: 150+1200 = $1350/wafer • 100% yield: 20050 = $10,000/wafer • 50% yield: 10050 = $5,000/wafer • 0% yield: 050 = $0.00/wafer
CMP
Dielectric deposition
Test
Implant PR strip
Etch PR strip
Packaging
Final Test
Fab Cost
• • • • • • Fab cost is very high, > $1B for 8” fab Clean room Equipment, usually > $1M per tool Materials, high purity, ultra high purity Facilities People, training and pay
*Cost of wafer, chips per wafer, and price of chip varies, numbers here are choosing randomly based on general information.
材料科學與工程學系 義守大學 – 助理教授 劉文仁
How Does a Fab Make (Loss) Money
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Wafer Yield
YW
Wafers Wafers
good total
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Die Yield
YD
Dies
good
Dies total
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Packaging Yield
Return Air
Raised Floor with Grid Panels
Pump, RF and etc.
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Gowning Area
Shelf of Gloves, Hair and Shoe Covers Entrance Gown Racks Disposal Bins Shelf of Gloves To Cleanroom
• At high yield, high throughput brought
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Defects and Yield
Y
1 (1 DA )
n
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Yield and Die Size
Killer Defects
Particles/ft3 Class M-1 1 10 100 1000 10000
材料科學與工程學系 義守大學 – 助理教授 劉文仁
0.1 mm 9.8 35 350
0.2 mm 2.12 7.5 75 750
0.3 mm 0.865 3 30 300
0.5 mm 0.28 1 10 100 1000 10000
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Cleanroom Classes
100000 10000
# of particles / ft3
1000
100
10 1 0.1
0.1
材料科學與工程學系 義守大學 – 助理教授 劉文仁
1.0 10 Particle size in micron
Definition of Airborne Particulate Cleanliness Class per Fed. Std. 209E
• 0.99600 = 0.0024 = 0.24%
• Almost no yield
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Throughput
• Number of wafers able to process
– Fab: wafers/month (typically 10,000) – Tool: wafers/hour (typically 60)
Wash/Clean Stations Storage
Shelf of Gloves Benches
材料科學與工程學系 義守大學 – 助理教rocess Module
Thin film growth, dep. and/or CMP
Photolithography
YC
Chips Chips
good total
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Overall Yield YT = YWYDYC
Overall Yield determines whether a fab is making profit or losing money
材料科學與工程學系 義守大學 – 助理教授 劉文仁
• Adopted in semiconductor industry in 1950 • Smaller device needs higher grade clean room • Less particle, more expensive to build
材料科學與工程學系 義守大學 – 助理教授 劉文仁
• Particles kills yield
• IC fabrication must in a clean room
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Clean Room
• First used for surgery room to avoid bacteria contamination
Etching PR Stripping Ion Implantation PR Stripping RTA or Diffusion
How Does Fab Make (Loss) Money
• Cost:
– Wafer (8”): ~$150/wafer* – Processing: ~$1200 ($2/wafer/step, 600 steps) – Packing: ~$5/chip
• Sale:
– ~200 chips/wafer – ~$50/chip (low-end microprocessor in 2000)
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Mini-environment
• Class 1000 cleanroom, lower cost • Boardroom arrangement, no walls between process and equipment • Better than class 1 environment around wafers and the process tools • Automatic wafer transfer between process tools
Test Structures Scribe Lines
Dies
材料科學與工程學系 義守大學 – 助理教授 劉文仁
Clean Room
• Artificial environment with low particle counts • Started in medical application for post-surgery infection prevention
Equipment Area Class 1000 Process Tool
HEPA Filter
Class 1 Process Area
Equipment Area Class 1000 Process Tool
Return Air