Tool IPA Recycling Technology
*Takashi Futatsuki, Hiroki Narita, Kazushige Takahashi, and Hiroshi Sugawara
*Deputy General Manager, Electronics Industry BU, Plant Division, ORGANO Corporation
OUTLINE
1. Background and Purpose
2. Quality Target
3. System and Apparatus
4. Analytical Result
5. Operating Cost
6. Summary
Background and Purpose
Wafer Drying Technologies
Method IPA Vapor Marangoni Rotagoni IPA Liquid SCCO2
Tool Type Batch Batch Single Single Single
IPA Phase Vapor Vapor Vapor Liquid Liquid
(Replacement）
IPA
Consumption
― ― ― Large Very Large
Discharge
Volume
― ― ― Large Very Large
Discharged
Concentration
― ― ― High
(>20wt%)
Very High
(>80wt%)
1. IPA consumption and discharge volume is getting larger.
2. Discharged concentration is getting higher.
→ Requirement of IPA recycling.
3. IPA is the final liquid chemicals contacted with wafer in new methods.
→ Requirement of IPA (fresh as well) purification, because of final contact.
Purpose of this study
Recycling IPA discharged from silicon wafer drying process
Conventional recycling technology is distillation
- Well established technology
- The recycled IPA quality is fine
- However, it needs high distillation tower and huge energy for evaporation
- Distillation tower cannot be installed by the process tools (never in the same building)
To develop a compact IPA recycling system with low energy consumption.
Quality Target
Quality Target of recycled IPA
Raw Materials
(waste IPA from
drying process)
Quality Target
(Recycled IPA)
IPA Concentration 20 – 80wt% >99.9wt%
Metals 10ppb < 0.1ppb
Si - < 1ppb
Anions 10ppb < 0.4ppb
Particles ≧200nm - < 100#/mL
note Assumption EL-IPA grade
※ On-site IPA recycling and purification system.
System and Apparatus
Schematic Flow Diagram of the System
UPW Wafer DryerDischarged
IPA
Ultrasonic
Atomization
Pre-conc.
(>80wt%)
Vapor
Permeation
Conc./
Purification
(>99.9wt%)
Fresh IPA
99.99wt%
<Features>
1. Compact (small space).
2. On-site treatment
3. Low energy consumption.
4. Quick start up.
Ultrasonic Atomization
・ Mist generation by ultrasonic.
・ Mist separation by size.
・ Smaller energy than evaporators
Atomization
Vaporization
H2O IPA
Laboratory System of Ultrasonic Atomization
P
HeaterUltrasonic
Atomization
Cyclone
Condenser
Chiller
Mist or Gas
Liquid
B
IPA/H2O
solution
IPA
Treated
Recovery Rate
95%
IPA: 20wt%
IPA: >85wt%
Laboratory System of Ultrasonic Atomization
Atomizing Unit
（magnification）
CycloneCondenser Air PumpIPA treatment ： 0.2 kg/h
System Flow Example of Ultrasonic Atomization
Discharged IPA
Product
Drainage
IPA: 85wt%
IPA: 20wt%IPA: <1wt%
Ultrasonic
Atomization
1
Ultrasonic
Atomization
3
Ultrasonic
Atomization
2
Comparison Evaporator and Ultrasonic Atomization
Stopping
Evaporator
・Whole Operation
・High Temperature
・Long Starting Time
Ultrasonic Atomization
・Flexible Operation
・Low Temperature
・Short Starting Time
Operating
Operating
VP (Vapor Permeation)
IPA
H2O（Vapor）Vacuum
IPA/H2O
（Vapor）
Zeolite MembraneSeparation Image
<Dewatering by zeolite membrane>
1. Selective adsorption on the membrane.
2. Selective diffusion in the membrane.
3. Desorption from the membrane by vacuum.
VP Test Apparatus
Front Back
IPA treatment : 2 kg/h
Zeolite membrane
System Flow of VP and Purification
Tank
Pump
MF
Ion adsorption membrane
No.1
Evaporator
Condenser
VP membrane
Ion exchange
resin
Tank
IPA Waste
P.O.U (Tool)
No.2
Evaporator
Condenser
Recovery Rate
93%
IPA: 85wt%
IPA: >99.9wt%
Analytical Result
Analytical Results
unit Fresh IPA - spec Fresh IPA - data Recycled IPA - data
IPA Conc. % >99.99 >99.999 >99.9
Water % <0.01 0.0019 <0.1
Cl ppb <5 <0.3 <0.3
SO4 ppb <5 <0.3 <0.3
Al ppb <0.1 <0.05 <0.05
Ca ppb <0.2 <0.10 <0.10
Cu ppb <0.1 <0.05 <0.05
Fe ppb <0.3 <0.10 <0.10
Na ppb <0.2 <0.10 <0.10
Ni ppb <0.1 <0.05 <0.05
Pb ppb <0.1 <0.05 <0.05
Zn ppb <0.1 <0.05 <0.05
Particle >30 nm /ml <200 5 3
Operating Cost
Pre-concentration by Ultrasonic Atomization - Cost
＜Conditions＞
Starting ：IPA=20wt%, 250kg/h
Treated ：IPA=85wt%, 56kg/h
IPA loss ：5%
＜Cost Estimation＞
・Ultrasonic Atomization (Pre-conc.)
Operating Cost ：12 JPY/kg
Foot Print (m)
W1.5×L2.0×H3.0
VP & IEX Purification - Cost
＜Conditions＞
Starting ：IPA=85wt%, 56kg/h
Treated ：IPA>99wt%, 44kg/h
IPA loss ：7%
＜Cost Estimation＞
・ VP & IEX Purification
Operating Cost ：30 JPY/kg
Foot Print (m)
W4.0×L3.0×H2.5
Total Cost (Ultrasonic Atomization +VP & Purification)
＜Conditions＞
Starting ：IPA=20wt%, 250kg/h
Treated ：IPA>99wt%, 50kg/h
IPA loss ：12%
Fresh IPA cost ：200 JPY/kg
＜Estimation＞
Pre-conc. : 12 JPY/kg
VP & Purification : 30 JPY/kg
Fresh IPA : 23 JPY/kg
Total : 65 JPY/kg
Total Cost Evaluation
Starting : IPA=20.0wt%、250kg/h
Treated : IPA＞99.9wt%、50kg/h
IPA recovery cost ＝ Initial cost + Operating costs
Summary
Summary
Recycling IPA discharged from silicon wafer drying process
Ultrasonic Atomization +VP & Purification
- Pre-concentration by Ultrasonic Atomization (to 85%)
- Concentration by Vapor Permeation (to 99.5%)
- Purification (metal removal) by Ion Exchange (less than 0.05 ppb)
Featuring compact and low energy consumption, the system can
recycle IPA by the process tools with economical benefits.
