Auto Scanning System
Fully Automated VPD-ICP-MS

Expert TM

Indispensable tool for analysis of metallic impurities in Si wafer
ExpertTM is designed for analysis of metallic impurities in Si wafers. There are threemodels in the family : Expert_FAB, Expert_PS and Expert_LAB. FAB and PS models
can be integrated with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and LAB
model is for standalone use.
Analysis of metallic impurities in Si wafer is one of important items in semiconductor
manufacturing. The concentration of metallic impurities to be controlled has been lowerand lower as the integration has been higher. Total Reflection X-Ray Fluorescence(TRXRF) has been used in production lines (FAB) because of its non-destructive feature.
However, the detection limit of TRXRF could not satisfy the requirement, and VPD
technique was developed as a sample pre-concentration method. As a result, thedetection limit was improved around two orders of magnitude, but TRXRF is no longer anon-destructive technique. In addition, the chemical solution prepared by VPD can bedirectly analyzed by ICP-MS with much lower detection limit including lighter masses suchas Li, Na and Mg. Consequently, ICP-MS with VPD becomes a common technique tocontrol metallic impurities in Si wafer.
There are several VPD equipment in the market, but they were developed for preparationof TRXRF and not designed for ICP-MS analysis.
[ Expert_PS ]This model has been in the market for more than 10 years. It is used in both labs andFABs and It can be used with ICP-MS for full automation or without ICP-MS for standalone.
ICP-MS is installed right next to the main frame of Expert_PS. Two load port locations andan optical aligner from 6” to 12” are standard.
[ Expert_FAB ]This model is a fully integrated model including ICP-MS for semiconductor FAB. ICP-MS islocated inside the main frame of Expert_FAB. Many options for PS model are included inFAB model as standard. Two load port locations and an optical aligner from 6” to 12” arestandard.
[ Expert_LAB ]This mode is designed for laboratory use. All wafer treatment such as VPD, Dry and scancan be done automatically and a scanned solution is recovered in a vial, which should bemanually transferred to ICP-MS for analysis. Only one load port location and a gravity
aligner for three consecutive wafer sizes are standard.

Features of Expert
 Load port
Expert has one or two load port locations depending on the model and various
combinations of wafer sizes such as 300 mm (12”) FOUP or FOSB, 200 mm (8”)
SMIF, 150 mm (6”) or 200 mm adaptor are available.
 HF vapor generation
A PFA nebulizer is used for generation of HF vapor used for VPD. A bubbling
technique has been commonly used for generating HF vapor, but the concentrationof HF changes with time that causes different etching time.
On the other hand, the PFA nebulizer generates constant concentration of HF
vapor and improves the etching speed.
 Dual scan nozzle
A scan nozzle holds scan solution andscans desired area of wafer to collectmetallic impurities remained on a wafer after
VPD. However, surface of wafer becomeshydrophilic after the bulk etching or dry
etching because the wafer surface getsrough after the bulk etching and organic
residue remain on a wafer after dry etching.
As a result, it was difficult to hold the scansolution with the conventional scan nozzle.
The Dual scan nozzle with vacuum can hold
Scan by Dual Scan Nozzle
the scan solution inside the nozzle very welland allows the scan of hydrophilic surface.
 Scan mode
The Expert can do various scan patterns
such as full, radial, sector, radial-sector andbevel as a standard function. The Expert
can also do the edge scan that scansaround 1 mm from edge of backside wafer
together with the bevel part.
Edge Scan

Radial scan results on VIS

Sector scan set up windowInside of Expert_PS Bulk etching and depth profile measurement
A special gas is introduced into the VPD chamber together with HF vapor, which allows
etching of bulk-Si, Poly-Si, WSi and Ti films that cannot be etched by only HF.
Using this function, metallic impurities diffused into Si substrate from deposited films canbe analyzed and profile measurement of dopant and metallic impurities in implanted
wafer is possible.
The etching speed and depth can be controlled by optimizing the amount of HF vaporand special gas. The maximum etching speed is over 1.5 um/hr with ±10% uniformity.

PFA nebulizer

Poly-Si layer etching Drying module
The drying module is used to dry a wafer before returning to a cassette.
The Expert measures the volume of recovered scan solution. If the recovered volume issmaller than the original volume, the scan solution may remain on the wafer, and it isdangerous if the wafer returns to the cassette with the remaining scan solution. To avoid
such a risk, the wafer is transferred to the drying module before returning to the cassette.
The drying module can also be used for a local bulk etching and preparation for TRXRF
measurement.
 Intelligent VPD-ICP-MS software has been developed to interface Expert TM system andICP-MS.
The followings are fully automated VPD-ICP-MS procedure:
1.
Mapping sensor identifies the location of wafer.
2.
A preset recipe number automatically sets up VPD time, scanning mode andvolume of scan solution for each wafer.
3.
The first wafer is transferred to Aligner where wafer position such as centering andnotch or flat is adjusted without touching a bevel part.
4.
The wafer is carried into VPD chamber, and HF vapor generated by a PFA
nebulizer is introduced and then a layer such as oxide or nitride is decomposed.
The etching is terminated by time or EPD.
5.
The wafer is transferred to Scan stage and the special scan nozzle aspirates thescan solution (max. 1.5 mL).
6.
The nozzle moves on the wafer and around 100uL of scan solution is pushed out
from the nozzle and the wafer is scanned according to the method set in therecipe.
7.
The nozzle recovers the scanned solution from the wafer and the solution iscollected into a vial.
8.
Simultaneously, the VPD interface software (VIS) controls ICP-MS, and thestandard solution and QC check solution are analyzed.
9.
When all criteria pass, the collected VPD samples are analyzed automatically.
10. All wafer information is transferred to VIS and the impurities found in thedecomposed layer are obtained.
11. VIS provides automated QA/QC function that checks correlation coefficient ofcalibration curves, minimum sensitivity, and QC recovery. Sample results arechecked against the pre-defined criteria and user selectable actions can be takenplace automatically if the results are over the limit.
12. The VPD for the second wafer is performed while the scanning of first wafer is inoperation.
13. QC check solution is analyzed every specified samples such as10 wafer samples.
14. When the concentration is higher than the specified value in a sample, the scannozzle is cleaned for an extended rinse time, then the blank solution is checked
whether the scan nozzle is clean or not.
15. When the scan solution is contaminated, another scan solution is usedautomatically.

 Integration with OHT and ICP-MS for fully automated operation
The Expert can be installed in FABs and integrated with CIM-HOST using the protocol
specified by SEMI for fully automated operation. FOUP is transferred to the Expert by
Overhead Hoist Transportation (OHT) using SEMI-E84 protocol, and the Expert treats
wafers in the FOUP according to the information on wafers and recipes sent from CIMHOST, and the scanned solution is analyzed by ICP-MS and the results of ICP-MS aresent to CIM-HOST. After the analysis of all wafers in the FOUP, the FOUP is removed byOHT automatically.
The Expert was installed in a FAB of major semiconductor device manufacturers and has
been running 24-7 since 2008. More than 60 systems were installed around the world.
The VIS (VPD Interface Software) has intelligent functions that checks the status of ICPMS and allows unattended operation of ICP-MS for 24-7.
 Safety certificate
The Expert has SEMI-S2, SEMI-S8 and CE certificates to meet with strict safety
regulations required for FAB use.

Standard configuration

Option Two load ports (selection from the option).
 Wafer transfer robot module with mappingsensor.
 Fully automated VPD chamber and HFvapor generation system.
 High speed, precise aligner for 6” to 12”
wafer (FAB and PS model).
 Gravity aligner module (LAB model).
 Fully automated wafer scanning stage andaccurate X-Y-Z scanning arm and nozzlemodule.
 2 Sample racks (40 vials/rack).
 Class 1 environment with Teflon® ULPA
filter media.
 Intelligent ExpertTM operating software.
 Desktop PC with Windows 10 ®.

PP panel upgrade
6” or 8” manual cassette module with position
sensor.
12” FOUP opener module.
6” and 8” adaptor for 12” FOUP
RFID or barcode reader8” SMIF loader module.
Bulk-Si and poly-Si etching module.
Wafer drying module
VPD and ICP-MS integration module including
autosampler and software.
Automated calibration module for ICP-MS
Auto vial washing system
Auto chemical supply system
Edge scan module
Microscope for edge scan
Wafer weight measurement module
AMHS, Integration with OHT (E84)FAB interface/CIM using SECS
(ASAS) Automated Standard Addition System
Hydrophilic wafer scan with N2 wall.
Wafer flip.
Aqua regia solution supply module
Scan solution dilution module
CCD camera
Sample vial rack cover (LAB model)

IAS Inc.
2-2-1 Hinohonmachi, Hino, Tokyo, 191-0011 Japan
TEL: +81-42-589-5525
E-Mail: iasjapan@iasinc.jp URL: https://iasinc.jp
April/2022