monitoring and remediation of contaminants in bulk chemicals€¦ · 02/04/2019 · j....
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Monitoring and Remediation of Contaminants in Bulk Chemicals
Eugene Shalyt, Jack Shamie60 Gordon Drive, Totowa, NJ [email protected] (201) 819-5302
SPCC 2019
Industry Requirements for Advanced Node
Challenges of the Future
J. Srinivasaraghavan
“Business of Cleans”
2018 Linx Conference
Requirements and challenges for
semiconductor cleaning chemicals
J. Hemphill
2016 Critical Materials Conference
Generalized Diagram of
Semiconductor Processing
Test point
Description Concern
Raw materials as
manufactured by chemical
supplier
Does CoA applies to EVERY
container?
Degradation in transit?
Does CoA cover ALL
parameters?
Raw material as it passed
through facility
distribution system for
bulk chemical
Degradation/Contamination of
chemical in transit e.g. O2, CO2
exposure, particle and metal
characterization
Process blend of
individual chemicals
Was blend prepared properly?
Compensation for degradation
of components
WaferOutside of scope of this
presentation
Process equipment
parameters
Outside of scope of this
presentation
Reclaim
Exact degradation of
components for proper
replenishment
Waste Compliance
Case Study: Bulk Chemical X
• End-user reported problems loosely related to lots of raw materials
Problem Statement
• End-user lab compared good and bad lots but could not find difference
Investigation
NIR Spectroscopy
Raman Spectroscopy
ICP
Potentiometric Titration
Conductometric Titration
E-Chem Impedance
Cyclic Voltammetric
Stripping
UV-Vis Spectroscopy
Surface Tension
Specific Gravity
OCP (Open Circuit Potentiometry)
Dissolved Oxygen
Ion Chromatography
HPLC
ECI In-house Tests
ECI screened Good and Bad Samples by variety of
analytical methods
ECI Test Results
• Most analytical methods including ICP-MS with pptsensitivity did not show difference between “Good” and “Bad”
• Surprisingly, cyclic voltammetry electrochemical method with sensitivity in ppm showed large difference indicating presence of Red/Ox active contaminant
Results ECI Electrochemical Method
Cyclic Voltammetry Method
Identifying Contaminant
Compound MatchStability in
Bulk Chemical
AxByCz
Clean bulk Chemical
Stable
AxByCz-1Contaminatedbulk chemical
Stable
AxBy+1Cz-1 Unstable
AxBy+1Cz+4
Clean bulk chemical
Stable
ECI Electrochemical Method
Analytical Method
Cyclic Voltammetry analytical method was optimized to provide
repeatable and accurate measurement of contaminant in
ppm concentration range
Remediation of Contaminated Chemical
AxByCz-1 + 1/n Cn ⇒ 𝐴𝑥𝐵𝑦𝐶𝑧
Contaminant Good productContaminant lacks one “C” atom
as compared to good product
Can contaminated chemical be
remediated by treatment with C ?
Brief sparging with C gas
removed contaminant
signature from both
“bad lot” and simulated
contaminant standard
SEMI grade vs ACS grade
Even “good” SEMI grade sample shows higher contaminant level than ACS grade (Reagent Grade of American
Chemical Society)
We suspect that removal process of metals to low PPT level or other semi-grade purification introduces contaminant
Contaminant is NOT regulated in SEMI or ACS standards
Conclusions
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Electrochemical
Cyclic
Voltammetry
method was
developed for
monitoring of
contaminant in
bulk chemical
Contaminant was identified
Gas sparging
was effective in
remediation of
contaminated
chemical
TMAH is widely used bulk chemical. Short exposure to air degrades chemicals
CO2 + OH- ⇒ 𝐻𝐶𝑂3-
Carbonate Calibration Carbonate Accumulation
DIW
Case Study 2: TMAH Degradation by
Contact with Air
UV-Vis method provides effective monitoring of carbonate accumulation and reveals carbonate uptake rate at different conditions