removal of volatile metals from corrosive ... west 2001...(si epi, si-ge epi) - degradation of...

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

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 Manufacturing

SEMICON West 2001 O SEMI 2001

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



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 .

%


424 SEMICON West 2001 (8 SEMI 2001

I

-

SEMI Technical Symposium (STS) Innovations In Semicondhictor Manufacturing

SEMICON West 2001 0 SEMI 2001

425 -

H,O Levels in Source Gas

- - . ... . ..

Metal Specifications for Semiconductor Grade HCl

I

Note: includes particluates and volbles

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



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

Preliminary Indication of Volatile M e t a l s

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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

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Mn epb)

H.3

74.5

4.6

NI C#b)

226.5

457.0

30.3

Cr Wl

1.09

T14,9

459

MTXm Efficiency for Volatile Mo in HCI

MTXm Efficiency for Volatile Ti in HCI

- - - - - _ _ _ _ _

- - - - - _ _ _

- - - - - _ _ _ _



MTXTM Efficiency in HBr Service --"-

Time, minutes

MTXTM Efficiency at High Flow WUmhWQ

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"


SEMICON West 200 1 O SEMI 2001

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



43 1 4

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



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.

/

SEMI Technical Symposium (STS) Innovations In Semiconductor Mmuhcturhg

SEMICON West 2001 - 0 SEMI 2001 43 3

removal of volatile metals from corrosive ... west 2001...(si epi, si-ge epi) - degradation of...

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