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REMOVAL OF VOLATILE METALS FROM CORROSIVE GASES BY A NEW
PURIFER
Carrie Wyse, Tadaharu Watanabe, Dan Fraenkel, Robert Torres, and
Virginia Houlding
Matheson Tri-Gas, Inc., Longmont, CO
INTRODUCTION
A new gas purifier has been developed for the removal of
volatile metal complexes from corrosive gas, in addition to
removing moisture. Performance of the purifier was tested by
generating a stream of volatile metals in HCI, challenging the
purifier and sampling the outlet of the purifier via hydrolysis.
The hydrolysis samples were analyzed for trace metals by ICP-MS.
Moisture performance was conducted in both inert and corrosive
gases by APlMS and FT-IR.
BACKGROUND Contamination control in etch processing is one of
the key issues in the semiconductor industry.
The level of volatile metal species found in HCI gas is
typically in the low ppb region even in the cleanest HCI
commercially avai~able."~~ These metal species pass through 0.003
pm particle filters to the final product. According to the SIA
Roadmap, the estimated allowable level of total metallic impurities
in gases is
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MetalXm efficiency for moisture in corrosive gas was tested in
HBr, since HBr is the most corrosive gas that is routinely used in
semiconductor processing. The challenge was monitored by FTlR
equipped with a MCT-A detector and 10 m pathlength cell. Moisture
levels were determined using the water peaks in the region of 3850
cm-' and a classical least squares algorithm. A challenge of 3 ppm
moisture in HBr was generated in a gas mixture of 10% N2 and 90%
HBr using a calibrated moisture generator. When exposed to this
challenge, MetalXm removed the ppm moisture challenge down to less
than 100 ppb, the detection limit of the method.
MetalXm efficiency for moisture in inert gas was also tested
using APIMS, since the detection limit is lower. A challenge of 7
ppm moisture in N2 was removed by MetalXTM to levels less than 1
ppb.
SUMMARY Conventional corrosive gas purifier technology can
merely help avoid the formation of volatile
metal complexes by minimizing corrosion facilitated by moisture.
~ a n o c h e m ~ MetalXm can do this very effectively, in addition
to providing removal of any trace volatile metal complexes. The
results presented demonstrate that MetalXm effectively removes ppm
levels of volatile metal complexes in HCI to levels less than
detection limit. MetalXm also removes moisture down to less than
100 ppb in HBr gas and 1 ppb in NP. In summary, the MetalXm
corrosive gas purifier offers the unique ability to remove both
volatile metal species and moisture.
ACKNOWLEDGMENTS
The authors acknowledge Analysis Now! For providing trace metals
analysis, and Ehrich Diede of Diede Precision Welding, Inc., for
welding and assembly of manifolds.
REFERENCES
i N. Anderson, et al., "Modeling Contaminants Generation from
Tubing during Start-up and Following Moisture Upsets in HCI
Distribution Systems", ISSM Symposium, San Francisco, October 1997.
ii N. Verma, et al., "Modeling purity in Bulk Reactive Gas
Distribution Systems", Proceedings Institute of Environmental
Sciences, 351 -359, 1997. iii Semiconductor Technology Workshop
Group Reports, Semiconductor Industry Associated, San Jose, CA,
November 1992.
SEMI Technical Symposium (STS) Innovations In Semiconductor
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Removal of Volatile Metals from Corrosive Gases by a
New Purifier (Nanochem MTXTM)
Carrie Wyse, T. Watanabe, D. Fraenkel, R. Toms, V. Houlding
Matheson Tri-Gas
Critical contaminants in corrosive systems Effects of
contaminants on process
Purifier Technology Performance of new purifier Benefits of
using new purifier
SEMI Technical Symposium (STS) Innovations In Semiconductor
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Critical Contaminants and Sources
Moisture - Source gas and container - Distribution system -
Cylinder changeouts Metals - Source gas and container - Corrosion
(particulates, volatiles) - Shedding from mechanical components
&semi- U..--C-LWr.ln Came Wyse, Matheson Tri-Gas - Slide
3
Impact of Critical Contaminants
Moisture - oxygenated species cause haze which affects
resistivity
(Si epi, Si-Ge epi) - degradation of distribution system due to
corrosion
Metals - highly mobile in semiconductor lattice
can be decreased by removing moisture particulates can be
removed by particle filter volatiles cannot be removed by particle
filter
/,semi- --..."-- Carrie Wyse, Matheson Tri-Gas - Slide 4
r t .
%
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H,O Levels in Source Gas
- - . ... . ..
Metal Specifications for Semiconductor Grade HCl
I
Note: includes particluates and volbles
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Vapor Pressures of Metal Chlorides
loo0 1 e .. * 1. .
I 4
E
5 0 - -- - ! ,,----- - f
$Z{I t FePCB t WCl6 t TiCl4 -+ SnCl4
t MOCE wC16 s CCE
1M) - - - - ---- --- .--- 0001 0.01 0.1 1 10 100 1000 10000
100000 10ooOOO
Correnbalion [ppm]
/,sem~- --...-- I Came Wyse, Matheson Tri-Gas - Slide 8
Piping Composition
SEMI Technical Symposium (STS) Innovations In Semiconductor
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SEMICON West 2001 O SEMI 2001
M h r l s l
Monelallay
SS 316L alloy
C-22alluy
C Co Cr Cu -Fa Ni Mn Yo
0.3 [I 31.0 2 5 2.0 €I max
0.03 0 17.0 O 'B81.5 12.0 0 2.5 : max
P.DI0 2.5 22 0 3 55.5 0.5 1.3 max
minimum 63% Ni + Co
/ , s e m ~ - - - . -... ---.- I Came Wyse, Matheson Tri-Gas -
Slide 7
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Preliminary Indication of Volatile M e t a l s
&em!- CBlla~r&auamT--81We9
Nanachem M T P Technology
~ ~ ~ c ~ ~ ~ b l e ~ h ~ ~ U r U ~ gases
DeoJgned to mwevolaHk metal 8-
E n g t n e e W f o r h ~ m o ~ ~ M y
~ h p m # i m ~ l
Shmt T m .f2 d m ) ftlrtouehO-w-1
Lung Term @days) (th-h 0.m pl fdhr)
?zlqmhm Ccmtml
Fe Wl
81k4
24928
I91
Mn epb)
H.3
74.5
4.6
NI C#b)
226.5
457.0
30.3
Cr Wl
1.09
T14,9
459
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MTXm Efficiency for Volatile Mo in HCI
MTXm Efficiency for Volatile Ti in HCI
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MTXTM Efficiency in HBr Service --"-
Time, minutes
MTXTM Efficiency at High Flow WUmhWQ
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MTXTsr Efficiency in N,
4
3
2 2 P Y
S 1 0
0 10 20 30 40 50 60 70 time (hour)
/,sem~- ---- .*..-A- ,.-..-.- ---- Came Wyse, Matheson Tri-Gas -
Slide 15
Effect of Moisture Removal on Components
b1-F nln seat of line n l v a in HBr nmw K4-C v.)w -04 line dw
In H& urvka without Nmoch*rn purifier, 1000 cyc ln wiUl Nmochom
puntior, 1000 cycl*l
/,sem~- --..- + ,- ---...- ..- I Came Wyse, Matheson Tn-Gas -
Slide 16
P"
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Effect of Moisture Removal on Particluates Generated in HBr
Before HBr Exposure
After HBr Exposum
I Canie Wyse, Matheson Tri-Gas - Slide 17 I
Effect of Particluates on Leak Rate of Valves
SEMI Technical Symposium (STS) Innovations In Semiconductor
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Benefits of MTXm Purifier on Corrosive Process
Minimizes Corrosion Reduces particulates Reduces volatile metals
Prolongs life of distribution system
Prevents device failure from oxygenated species, volatile
metals, and particulates
MTXm Summary
,--I.--
Impurities Removed Hz0
Volatile Metal species (e.g. Mo, Ti, Fe)
Particulates
Efficiency 4 0 0 ppb H20 in N2 (Lambda Scan)
c1 ppb H20 in N2 (APIMS)
c4 ppb Mo in HCI (HydrolysisllCP-MS)
Capacity - 5000 kg HCI
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Volatile metal species are electronically active contaminants
that can cause device failure.
Volatile metals in corrosive gas distribution systems are not
removed by particle filters.
Nanochem MTX is a corrosive gas purifier which removes volatile
metal species, moisture and particulates in one package.
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