IAS

Continuous Chemical Sample Inspection

IAS Inc.

CSI monitors chemicals used in semiconductor FAB
Continuous Chemical Sampling Inspection (CSI ) is a system that monitors ultra tracelevel of metallic impurities in chemicals used in semicondutor industries.
Semiconductor device manufacturing process repeats more than a few hundreds ofdeposition, etching, diffusion, implantation, lithography and cleaning steps. Manydifferent types of chemicals are used for different purpose, and metallic impurities inchemicals cause malfunction of device.
Since a single wafer processing is getting popular, risk of cross-contamination incleaning and etching processes is getting smaller. Instead, contamination of bulk
chemicals causes a huge production loss. The contamination of bulk chemical may
occur when chemicals are transferred from lorries or canisters to storage tanks orafter replacement of filters.
In order to avoid any contamination risk in chemicals, CSI has been used to monitor
metallic impurities in different storage tanks by one ICP-MS sequentially for 24-7.
When a lorry comes, a sample from lorry is analyzed right after the current sample.
There are two types of sample transportation ways; liquid phase (LT) and aerosol
phase (AT). LT model is designed for monitoring storage tanks, canisters andlorries that can determine a sub-ppt level of metallic impurities for almost all
chemicals. Sample transfer tube should be connected to CSI directly. AT model isdesigned for monitoring an accident that can determine a single ppt level ofmetallic impurities for certain chemicals.
Sampling module(AT model)

FAB area
Cleaning
BathBulk chemical area

Cleaning
BathICP-MS area

Sampling module(LT model)

OnlineSoftware（OIS）

Storage
TankICPMS

Example of CSI system

CIM-HOST(Option)

◆ FAB area - Chemical solution is taken from a recycling line of cleaning bath to thesampling module (AT model) by using a narrow PFA tube (maximum 6 lines), andaerosol of selected chemical solution is generated by means of a special nebulizer
and Ar gas. The aerosol is carried through a PFA tube by Ar gas and transferred tothe ICP-MS. The maximum distance between the sampling module and ICP-MS isaround 100 m.
◆ Bulk chemical area – Bulk chemical is taken from an outlet of tank, canister or lorry
to the sampling module (LT model) and analyzed by ICP-MS. Dilution of chemicalwith DIW at a certain ratio will be done if dilution of chemical is needed. There is nolimitation of distance between tank or lorry and ICP-MS. Normally a recycle line isinstalled for tank chemical and a purge line is installed for lorry chemical.
◆ ICP-MS area – One of chemicals is collected in closed container, from which sample
solution is self-aspirated by nebulizer of ICP-MS and analyzed by ICP-MS. The
analysis is executed by the method of standard addition and ASAS (AutomatedStandard Addition System) adds standard solution into the self-aspirated samplesolution line. There is no valve in the sample and standard addition line by ASAS
that allows sub-ppt level analysis without memory issue.
Drain lines are separated for different chemicals.
Typical chemicals analyzed at present are HF, H2O2, HCl, TMAH, NH4OH, H2SO4, IPA,and Thinner. These chemicals are analyzed by only one ICP-MS sequentially for 24-7.
The tuning condition can be automatically switched for each chemical.

◆ CSI Online Interface Software (OIS) – OIS is an intelligent software that controls
each sampling module, introduction module and ICP-MS. ICP-MS is used as adetector and all information including calibration curve is managed by OIS.
OIS has the following functions- Automated calibration and re-calibration by the method of standard addition.
- Check correlation coefficient of calibration curve, minimum sensitivity, SD
and RSD, and automatic re-analysis function if results are out of limit.
- Periodic check of quality control standard (QC).
- Sensitivity compensation for each sampling module by internal standard.
- Two concentration upper limits, and generation of alarm and output signal.
- Insertion of lorry sample after the current sample.
- Change ICP-MS method for each chemical (depending on ICP-MS model).
- Trend chart in concentration and count for each sample.
- Communication with valve manifold boxes (VMBs).
- Communication with CIM-HOST in a FAB by SECS protocol. (Option)

Main window of CSI software

Trend graph in concentration (left) and counts (right)

The followings are standard addition calibration curves of various chemicals
analyzed by LT model. All chemicals were analyzed sequentially.

The followings are trend graph of SC-1 and SC-2 chemical bathes obtained by ATmodel (100 m PFA tube). Mixed standard solution was spiked into each chemicalbath. It took about two minutes to detect spiked standard elements after spiking.
0.250+0.02ppb(0.08)• High Temp. (76oC) SC-1 (H2O2/NH4OH/H2O)• Measurement Frequency : Data/10min.

Concentration (ppb)

0.200

Na:23
Mg:24
Ba:138+0.02ppb(0.06)

Pb:208
Al:27

0.150

K:39
Cr:52

+0.02ppb(0.04)

Mn:55
0.100

+0.02ppb(0.02)

Fe:56
Co:59
Ni:58

0.050 Ref.

Cu:63
Zn:64
Ca:40

0.000
2008/6/6
13:26

2008/6/6
13:55

2008/6/6
14:24

2008/6/6
14:52

2008/6/6
15:21

2008/6/6
15:50

Trend graph of SC-1 bath monitoring
1.000+0.300ppb(0.500)• Room Temp. SC-2 bottle sampling• Measurement Frequency : Data/10min.

Na:23
Mg:24

Concentration (ppb)0.800

Ba:138
Pb:208+0.100ppb(0.200)

Al:27

0.600

K:39
Cr:52

+0.050ppb(0.100)+0.030ppb(0.050)

0.400

0.200

Ref（Blank)

Mn:55Fe:56
Co:59
Ni:58

+0.020ppb(0.020)

Cu:63
Zn:64
Ca:40

0.000
08/06/26
10:29

08/06/26
11:20

08/06/26
12:10

08/06/26
13:01

08/06/26
13:51

Trend graph of SC-2 bath monitoring

IAS Inc.

IAS

2-2-1 Hinohonmachi, Hino, Tokyo, 191-0011 Japan
TEL: +81-42-589-5525
E-Mail: iasjapan@iasinc.jp URL: https://iasinc.jp

The contents of this catalog may be changed without notice.
April 2022