Characterization of Organic Contaminants Outgassed fromMaterials Used in Semiconductor Fabs/Processing

Peng Sun, Caroline Ayre, and Matthew Wallacea

California Materials Technology Department, Intel Corporation, Santa Clara, CA 95052acurrent address: 3306 South 256th Street, Kent, WA 98032

Abstract. As ULSI technology continues to advance, semiconductor manufacturers are facing new contaminationcontrol and monitoring challenges, including airborne molecular contamination (AMC). AMC is being recognized asone of the yield limiting factors in newer generation microelectronics fabrication processes. A major AMC source,materials' outgassing can introduce a variety of organic contaminants into semiconductor fabs, impacting manyprocesses. This paper provides a brief overview of typical organic outgassing contaminants, their sources, processimpacts and analytical techniques used to detect these species. In addition, outgassing study results forpolycyclodimethylsiloxanes and several other contaminants using thermal desorption-gas chromatography-massspectrometry (TD-GC-MS) analysis are employed to demonstrate the relationships among (1) outgassing level andoutgassing time (linear), (2) outgassing quantity and the inverse of outgassing temperature (logarithmic), and (3)outgassing quantity and material surface area (linear). A new method, based on gas diffusion conductivity detection, forammonia and volatile amines' outgassing analysis is also presented.

INTRODUCTION

Understanding the effects of Airborne MolecularContamination (AMC) on microelectronic fabricationprocesses is of increasing concern as ULSI technologycontinues to develop. SEMI F2-951 standard"Classification of Airborne Molecular ContaminantLevels in Clean Environments" specified AMC in fourclasses - molecular acids (MA), molecular bases(MB), molecular condensables (MC), and moleculardopants (MD) [1]. Molecular condensables are organiccontaminants that may adversely impact manysemiconductor processes. The 2002 InternationalTechnology Roadmap for Semiconductor (ITRS-02)indicates organic contamination on silicon wafers aftercritical cleans should be below 2.6E13 carbonatoms/cm2 for 130 nm technologies. The value dropsto 1.5E13 for 90 nm technologies [2]. As one of themajor sources of molecular condensables, materials'outgassing can contribute to organic contaminationfrom a variety of cleanroom materials including filters,sealants, walls, adhesives, floor tiles, paints, wafercarrier and packaging materials, as well asconsumables such as garments, gloves, tapes andcleaners.

Material's outgassing is also a source of airbornebase contamination in semiconductor cleanrooms. Aslithography continues to progress to deeper DUVwavelengths, the resists employed in semiconductorprocessing are increasingly sensitive to airborne bases.The current ITRS specification for total bases inlithography is 750 pptM (parts per trillion Molar) [2].Therefore, better understanding of materials'outgassing behaviors is necessary for cleanroommaterial selection and the control of both molecularbase and molecular condensable concentrations inmicroelectronic Fab environments.

EFFECTS OF MOLECULARCONDENSABLES AND ANALYTICAL

METHODS FOR MATERIALS'OUTGASSING

Effects of Outgassed OrganicContaminants

Organic contaminants can affect semiconductorprocessing in a variety of ways. Tamaoki, et al.,

CP683, Characterization and Metrology for ULSI Technology: 2003 International Conference,edited by D. G. Seiler, A. C. Diebold, T. J. Shaffner, R. McDonald, S. Zollner, R. P. Khosla, and E. M. Secula

© 2003 American Institute of Physics 0-7354-0152-7/03/$20.00245

reported that organic contamination on the initial SiO2surface caused degradation in the polysilicon layerresulting in breakdown field strength reduction [3].Kasi, et al., found that significant organiccontamination (1014-1015 C atoms/cm2) could causeserious degradation in MOS devices grown onhydrogen-passivated silicon (Si) [4]. Both oxide andnitride film growth and quality can be affected byorganic contamination as well. Licciardello, et al.,reported that plasticizers such as dioctyl phthalate(DOP) could react with HF-etched surfaces to generatecarbon-rich hydrophobic surfaces that retarded siliconoxide growth [5]. Saga et al, found that waferscontaminated with butylated hydroxytoluene (BHT)and dibutyl phthalate (DBF) experienced gate oxideintegrity (GOI) degradation and low-pressure CVDnitride growth retardation [6,7]. Organophosphoruscontaminants such as triethyl phosphate (TEP) andtris(choloropropyl) phosphate (TCPP) flame retardantscan cause serious unintentional doping of Si devicewafers resulting in yield losses [8,9]. FTIR and GCstudies have shown that polycyclodimethylsiloxanesoutgassed from sealants of silicone polymers formparticles [10]. Organic contaminants and photo resistoutgassing can present contamination and hazeproblems in DUV lithography [11].

Analytical Methods for Materials'Outgassing Measurements

Both direct and indirect techniques may be used formaterials' outgassing measurements. Direct methodscommonly used in the microelectronic industryinclude material weight loss analysis and thermaldesorption gas chromatography-mass spectrometry(TD-GC-MS, also referred as dynamic headspace GC-MS). Weight loss measurements are an excellentmethod to determine total mass loss due to outgassingof volatiles and semi-volatiles. They provide usefulinformation for assessing physical property changessuch as shrinkage during the curing process of asealant material. TD-GC-MS combines the superiorseparation ability of GC and the powerful unknownidentification and quantification ability of massspectrometry. The TD-GC-MS technique allows forqualitative and quantitative analysis of volatile andsemi-volatile compounds outgassed from differentmaterials used in semiconductor fabs and processes.

Indirect measurements of outgassed volatiles andsemi-volatiles can be made by exposing witness Siwafers to materials of interest and subsequentlyanalyzing the outgassed or adsorbed species by TD-GC-MS or Time-of-Flight Secondary Ion MassSpectrometry (TOF-SIMS), respectively. One of the

benefits of indirect outgassing measurements is thatthey provide a means to study the adsorption behaviorof outgassed organic species on Si wafer surfaces[12,13]. A drawback of the indirect measurement isthat it does not provide a complete picture of the totaloutgassed organic contaminants.

Related industry standard methods include: ASTMF1227-89 "Standard Test Method for Total Mass Lossof Materials and Condensation of Outgassing Volatileson Microelectronics Related Substrates" [14]; ASTMF1982-99: "Standard Test Methods for AnalyzingOrganic Contaminants on Silicon Wafer Surfaces byThermal Desorption Gas Chromatography" [15];SEMI E108-0301 "Test Method for the Assessment ofOutgassing Organic Contamination fromMinienvironments Using Gas Chromatography/MassSpectroscopy" [16]; EEST Working Group CC031ongoing activity: Recommended Practice (RP) formethod for characterizing outgassed organiccompounds from cleanroom materials and components[17].

CHARACTERIZATION OFOUTGASSED ORGANIC

CONTAMINANTS USING TD-GC-MS

Detection of Organic ContaminantsOutgassed from Cleanroom Materials

Because of its good qualitative and quantitativecapabilities, TD-GC-MS was used in all of the organicoutgassing characterization experiments and wafersurface organics' analyses described here. Fig. 1shows a block diagram of a TD-GC-MS system. Formaterials' outgassing analysis, a piece of selectedmaterial was placed in a outgassing thermal desorptiontube and analyzed on a TD-GC-MS system (Fig.lA).Method B in ASTM F1982-99 standard [15] was usedfor wafer surface organic analysis (Fig. IB).

outgassing

A. tube

B. tube

wafer TD unit

organic outgassing* result: ug/g

surface organic* result: ng/cmA2

FIGURE 1. Block diagram of TD-GC-MS system.

246

803T3C3^

2 o 4 ^1=|1

A1

ILo

V.» Total outgassing: 680 ug/g

Siloxanes: 290 ug/g

6I

5.00 10.00 15.00 20.00 25.00 30.00

B

3

2

Total organics: 7.6 ng/cm2

Siloxanes: 6 ng/cm2

i ,

6 7

1 „ 1 .s no_____in no_____i.s.no

Retention Time (min)

8(0T5

^5

=3000

-t ooo

seL«s««o<,

^».ooo

T 000

C

-»o oo

unknown spectrum

_[

Dodecamethyl-cyclohexasiloxane

standard spectrum

«o -, oo-, io-, Ao-, Ao-, sosoo^o^o^o^o^oo^o^

-«.„

~--~~— '

Tm/z

FIGURE 2. A. TD-GC-MS outgassing chromatogram for a cleanroom sealant, (1): acetic acid, (2)-(6):polycyclodimethylsiloxanes; B. Witness wafer surface organic analysis result, (2)-(6): polycyclodimethylsiloxane, (7) organicacid ester; C. Identification of dodecamethyl- cyclohexasiloxane by MS detector. Retention time = the time when a specificcompound elutes out from the GC column.

Fig. 2A shows a TD-GC-MS outgassingchromatogram of a silicone-based cleanroom sealant.A series of polycyclodimethylsiloxanes, knownproblematic contaminants, outgassed from thismaterial at 50 °C. The total amount ofpolycyclodimethylsiloxane outgassing was 290microgram/gram (ug/g). Another major outgassingcompound was acetic acid, 380 ug/g. Fig. 2B showsthe TD-GC-MS chromatogram for a witness wafer thatwas exposed to one gram of the sealant shown in Fig.2A. After three days of exposure at room temperature,the same types of polycyclodiemethylsiloxanes were

detected on the witness wafer surface withdodecamethyl cyclohexasiloxane as the most abundantcontaminant (peak 4 in Fig. 2B). The total polycyclo-dimethylsiloxane level of 6 ng/cm2 (~ 2.5E14 carbonatoms/cm2) was significantly higher (> 10 times) thanthe ITRS-02 requirement for 130 nm technologies.Another major outgassing compound, acetic acid wasnot detected on the wafer surface, suggesting thatacetic acid did not deposit there. Fig. 2C demonstratesthe powerful contaminant identification capability ofTD-GC-MS technique. The chemical structure of thecontaminant eluted from the GC column at 10.9 min

247

0)oCO•oc3.Q

Triethyl phosphate: 49ug/g

kJJXXfc> «_i rt cita r t ot»

9OOOOOO

eoooooo•7OOOOOO

©oooooo5000000•4OOOOOO

3OOOOOO

2OOOOOO

•i oooooo

TIC: 1216O2O2-D

BTriethyl phosphate: 5.8ng/cm2

>.OO 2O.OO 25.OO 3O.OO 35.OO

Retention Time (min)

o>o(0•oc

©000

2000

SOOO

©000

2000

20

J

"Vs J20

C

**'o ©b s'<

«•:•*

-MS. j «S£>

-*'o ©b s'

Scao

, 1 .D 1 <

£»

'

O T

T929 (I 1 -5©3

A . j . . .lil U in ,DO T 2O 1 -»O

<;:>

-, ̂

III ill i!i00 12° °̂

r-nir-i>: 12-1SO2O2.O>i-S

Unknown spectrum

•i e,-v "' s-?- -=.ov ->-=>«3 "o-^ "o-j©0 I SO 200 220 2*3-0 2©O 28O

s-s Triethyl phosphatestandard spectrum

., tsv -T SS2

1 ©0 I SO 200 220 2**0 2©0 2SO

m/zFIGURE 3. A. TD-GC-MS outgassing chromatogram for a cleanroom sealant; B. Witness wafer surface organic analysisresult; C. Identification of TEP by MS.

was identified to be dodecamethyl-cyclohexasiloxaneby matching the unknown spectrum (top panel in Fig.2C) with the standard dodecamethyl-cyclohexasiloxane spectrum (bottom panel in Fig. 2C)stored in the MS spectral library.

Fig. 3 shows the detection of triethyl phosphate(TEP), a commonly used flame retardant.Approximately 49 ug/g of TEP outgassed from a

cleanroom pop-out sealant material at 50 °C (Fig. 3A).A witness wafer exposed to the pop-out sealant atroom temperature showed a surface TEP level of 5.8ng/cm2 (-2E13 P atoms/ cm2), well above the criticallevel that can cause unintentional phosphorus dopingof Si wafers and yield loss [17]. Once again, TEP waspositively identified by the MS detector (Fig. 3C).

248

Outgassing Characterization

Several polymer materials known to outgas organiccontaminants commonly seen in semiconductor Fabcleanroom environments were selected as part of astudy designed to understand outgassing behavior as afunction of time, temperature, material surface areaand weight. Organic contaminants tested includedpolycyclodimethylsiloxanes, dibutyl phthalate (DBF),butylated hydroxytoluene (BHT), 2-ethyl-l-hexanol,methylstyrene and naphthalene.

As shown in Fig. 4, a linear relationship wasobserved between the concentration of variouspolycyclodimethylsiloxanes outgassed at 50 °C andoutgassing time. Outgassing rates for differentcompounds were estimated from the slopes ofoutgassing concentration vs. outgassing time plots.Similar results were also obtained for DBF and BHT.Data for tests conducted at 75 °C also showed a linearrelationship with higher slope values, indicative ofhigher outgassing rates at 75 °C verses 50 °C.

The influence of outgassing temperature onoutgassing concentration is shown in Fig. 5. A linearrelationship was observed between the logarithm ofoutgassing quantity and the inverse of outgassingtemperature (1/T) for polycyclodimethylsiloxanes,DBF and BHT. These results are in agreement withthe findings reported by Takeda, et al, in their paper,which demonstrated a method of estimating outgassingrates of contaminants of interest based on their vaporpressure [18].

Outgassing Time Dependence (at 50°C)1.20 -i

1.00 ^

°-80 ]

2 £ 0.60o EC Q.

0.40 ]

0.20

0.00

0.0358x + 0.2154R2^ 0.9816

L0394X + 0.0609FP = 0.9872

D

X

= 0.0236X + 0.0744R2 = 0.9993

10 20 30Outgassing Time (min)

40

The influence of outgassing temperature onoutgassing concentration is shown in Fig. 5. A linearrelationship was observed between the logarithm ofoutgassing quantity and the inverse of outgassingtemperature (1/T) for polycyclodimethylsiloxanes,DBF and BHT. These results are in agreement withthe findings reported by Takeda, et al., in their paper,which demonstrated a method of estimating outgassingrates of contaminants of interest based on their vaporpressure [18].

Fig. 6 and Fig. 7 illustrate the relationship amongsurface area, sample weight and outgassing quantity.As shown in Fig. 6, outgassing levels ofpolycyclodimethylsiloxanes are proportional to thesample surface area when the sample weight remainsconstant. However, outgassing is independent ofsample weight when the surface area remains constant(Fig. 7). Similar behavior was observed for methyl-styrene, 2-ethyl-hexanol and naphthalene.

Outgassing vs. Temperature2.50

2.00 -

O

oo0)

1.50 -

J? 0.50

0.00

-0.50

-1.00

y = -3.9015x + 11.825R2 = 0.9726

2.D

y = -1.782x+5.4216R? = 0.9977

y=-1.5764x+4.6101R2 = 0.9841

2.70

y =-1.724x + 5.301R2 = 0.9945

2.90 3.80

1/Tx103(1/Kx103)

FIGURE 5. Outgassing quantity vs. outgassingtemperature. (O): Octylmethyl-cyclotetrasiloxane; (n):Decamethyl-cyclopentasiloxane; (x): Dodecamethyl-cyclohexasiloxane; (A): Dibutyl phthalate (DBF).

FIGURE 4. Outgassing quantity vs. outgassing time.(O): Octylmethyl-cyclotetrasiloxane; (n): Decamethyl-cyclopentasiloxane; (x): Dodecamethyl-cyclohexasiloxane.

249

Siloxane Outgassing Dependence onSample Surface Area

(outgassing condition: 50°C, 15 min)700 -

O)

0)

600 -

500 -

400 -

300 -

200

TOO

Octcmefrhyl- Deocrrefhyl- TcydotetrcBiloxcne cydopentcBiloxcne cydoheptcsiloxcne

D 1x surface area, 1x sample weight& 2x surface area, 1x sample weight

FIGURE 6. Outgassing quantity vs. material surface.

Outgassing Dependence on SampleWeight (50°C, 15m in)

600

O) 500 -

400 -

O)3O75

300 -

200 -

100 -

OctcmeThyl-cydotetrcBiloxcne

Deocmethyl- T efrcdeccnrerh/l-cydopentcsiloxcne o/doheptailoxcne

n 1x sample weight, 1x surface area0 2x sample weight, 1x surface area

FIGURE 7. Outgassing quantity vs. material weight.

Based on the results of these material outgassingcharacterization experiments, the followingconclusions may be drawn for the contaminantsstudied under the conditions outlined above: 1) there isa linear relationship between outgassing concentrationand outgassing time; 2) outgassing rate can beestimated from the slope of the outgassingconcentration vs. outgassing plot; 3) there is a linearrelationship between the logarithm of the outgassingquantity and the inverse of outgassing temperature

(1/T); and 4) outgassing quantity is proportional to thematerial surface area and independent of materialweight when surface area remains constant,suggesting that outgassing is a surface phenomenon.However, due to the large number of variables in thephysical properties and chemical composition ofmaterials used in cleanroom construction andoperation, the authors believe that materials'outgassing can be far more complicated than thelimited findings reported in this paper.

AMMONIA/AMINES' OUTGASSING

Ammonia/Amines' Impact

The impact of airborne molecular base (MB)contamination on the performance of chemicallyamplified (CA) resist has been a long-standingproblem in semiconductor lithography [20-21]. MBcan neutralize the photo-generated acid during the timedelay between the exposure and post-exposure bake(PEB), generating insoluble products that cannot bedissolved by the developer solvent. A lip, known as"T-topping", forms at the top of the developed resistprofile. Extreme cases of "T-topping" cause bridgingbetween adjacent patterns. Among numerous possibleMB contamination sources, materials' outgassing is acommon one. Volatile molecular bases can outgasfrom cleanroom materials such as ceiling tiles, sealant,paints, adhesives, cleaning solutions and processchemicals, among others. Screening new cleanroommaterials for NH3/amines outgassing before usingthem in the cleanroom and/or DUV bay maysubstantially reduce the likelihood of MBcontamination.

Gas Diffusion-ConductivityAmmonia/Amines' Outgassing Analysis

The typical TD-GC-MS technique used forcondensable organics outgassing is generally notsuited for detecting ammonia (NH3) and very volatileamines, which have poor recovery in TD-GC-MS dueto their high volatility. Therefore, a new materials'NH3/amines' outgassing method based on gasdiffusion conductivity detection has been developed.Fig. 8 shows a schematic diagram of this NH3/amines'outgassing technique. Detection limits of less than 1part per billion (ppb or ng/g) can be achieved usingthis method.

250

sample chambercarrier gas

buffersolution

liquid conductivitydetector

T diffusion module

gas outlet

FIGURE 8. Schematic diagram of gas diffusionconductivity based NH3/amines' outgassing technique.

B

NH3/amines signal

FIGURE 9. NH3/amines' outgassing of two cleanroomsealants. A. Sealant A; B. Sealant B; C. SEM image of"T-topping" caused by NH3/amines' outgassing of sealantA.

Fig. 9 shows the NH3/amines' outgassing of twocleanroom sealants. Sealant A outgassed 723 ng/gNH3/amines at room temperature (Fig. 8 A) and causedsignificant "T-topping" defects in EO delay photoresist tests (Fig. 8C). The NH3/amines' outgassing

level of sealant B was < 5 ng/g and this sealant had noimpact on the photo resist develop process.

In time-dependent outgassing studies, three (3)days of curing were required for the NH3/amines'outgassing level from sealant A to drop to the singleppb range (Fig. 10A). The initial quantity ofNH3/amines outgassed was in excess of 700 ppb. Theoutgassing level dropped to 30 ppb after an 8-hourcure.

_ onn

JH3/

Amin

e O

utga

ssin

c(n

g/g)

0

NH3/Amine Outgassing vs. Cure Time

V10 20 30 40 50 60 70 80

Cure Time (hour)

onnn

Waf

er S

urfa

ce N

H4+

(E10

NH

4+/c

m2)

_k

-L

ro

ro c

go

0

1

o

oi

cO

0

O

0

C

D

O

O

O

O

O

C

Wafer Surface NH4+ vs. Cure Time(1 hour exposure at room temperature)

L _" — ——— —— —— 4 i*

0 10 20 30 40 50 60 70 80Cure Time (hour)

Wafer Exposure Test(1 hour at room temperature)

onnn

+ 2500 -S «Z c onnng ^2000-

•t x 1500 -3 Z

*2 2 1000 -O UJ<5 ^;> cr\n

0 .———, ——— , —————————— , —— _,___,___,

C ^+^^^

^^+^"^ ———————————————————

0 100 200 300 400 500 600 700 800NH3 Outgassing

(ng/g)

FIGURE 10. NH3/amines' outgassing of and depositionon witness wafer surfaces. A. Time dependentNH3/amines' outgassing of sealant; B. Surface NH4+ onwitness wafers exposed to sealant A; C. Correlation ofwitness wafer surface NH4+ and sealant outgassing levels.

251

In order to understand the adsorption behavior ofoutgassed NH3/amines on Si wafers as a function ofcuring time, clean Si wafers were exposed to samplesof sealant A that had been cured for different lengthsof time. Each wafer was subsequently extracted withdeionized (DI) water and the extract analyzed by ionchromatography (1C) [22] in order to determine theammonium (NH4+) content. The wafer exposed tofresh sealant A for one (1) hour at room temperatureshowed a very high surface NH4+ concentration of2600E10 NH4+ ions/cm2 (Fig. 10B). By contrast, thewafer exposed to a sealant A sample that has beencured for 69 hours exhibited a surface NH4+concentration close to that of the control wafer, whichhad no sealant exposure. The linear relationshipbetween witness wafer surface NH4+ concentrationand NH3/amines' outgassing measurements for sealantA appears in Fig. 10C.

The results from the time-dependent outgassingstudies and wafer exposure tests have demonstratedthat the gas diffusion-conductivity based techniqueprovides a sensitive method for materials'NH3/amines' outgassing measurements. Thecombination of this technique with the widely usedTD-GC-MS method allows for a more completescreening of cleanroom materials for potential airbornebase and condensable contamination, respectively.

SUMMARY

Microelectronic fabrication processes withdecreasing device geometries are increasinglysusceptible to AMC. Many AMC contaminants foundin semiconductor Fabs come from outgassing ofcleanroom materials. Outgassed contaminants canadversely affect many processes, resulting in yieldloss, shortened tool life and reduced long-term devicereliability. The large variety of cleanroom materialsand numerous outgassing contaminants combined withthe complexity of process steps makes understandingdetrimental levels of particular contaminants inparticular processes very challenging. Screeningmaterials for condensables' and NH3/amines'outgassing prior to bringing them into Fabs can beused as a first-line-of-defense against molecularcontaminants such as organo-phosphorus, siloxanes,plasticizers and ammonia/amines. As processes andchemistries change, requirements for monitoring,control and analysis of materials' outgassing willcontinue to evolve. Cooperative efforts amongmanufacturers of integrated circuits, materials andanalytical tools are needed to better understand theimpact of molecular contaminants and to properly

define specifications applicable to the new ULSItechnology.

ACKNOWLEDGMENTS

The authors thank Yaacov Maoz of Intel Fab 18for providing the "T-topping" defect SEM image, ZariPourmotamed of Intel California MaterialsTechnology Department for collecting the time-dependent NH3/amines' outgassing results, and JosephO'Sullivan of Intel Facilities TechnologyDevelopment for providing valuable technical inputs.

REFERENCES

1. SEMI F21-95: "Classification of AirborneMolecular Contaminant Levels in CleanEnvironments", SEMI 1995.

2. The International Technology Roadmap forSemiconductors: 2002 (ITRS-02).

3. Tamaoki, M., Nishiki, K., Shimazaki, A., Sasaki,Y., and Yanagi, S., "The Effect of AirborneContaminants in the Cleanroom for ULSIManufacturing Process", 1995 IEEE/SEMIAdvanced Semiconductor ManufacturingConference Proceedings, pp. 322-326 (1995).

4. S.R. Kasi, S.R., Liehr, M., Thiry, P.A., Dallaporta,H., and Offenberg, M., Appl. Phys. Lett., 59 (1),108-110(1991).

5. Licciardello, A., Puglisii, O., and Pignataro, S.,Appl. Phys Lett., 48(1), 41-43 (1986).

6. Saga, K., and Hattori, T., Appl. Phys. Lett., 71,3670-3672 (1997)

7. Saga, K., and Hattori, T., J. Electrochem. Soc. 144,L253-L255 (1997).

8. Mori, E.J., Dowdy, J.D., and Shive, L.W.,Microcontamination 10 (10), 35-37 (1992).

9. Lebens, J.A., McColgin, W.C., Russell, J.B., Mori,E.J., and Shive, L.W., J. Electrochem. Soc. 143(9), 2906-2909 (1996).

10. Namiki, N., Otani, Y., Emi, Hitoshi and Fujii, S.,J. Institute of Environ. ScL, 26-32 (January, 1996).

11. Kunz, R., .Microlithography World, pp.2-8 (2000).12. Saga, K., and Hattori, T., J. Electrochem. Soc. 143

(9), 3279-3284 (1996).13. Hou, D., Sun, P., Adams, M., Hedges, T., and

Govan, S., "Comparative Outgassing Studies onExisting 300 mm Wafer Shipping Boxes andPods", 44th Annual Tech. Meeting of IESTProceedings, pp. 419-428 (1998)

14. ASTM F1227-89: "Standard Test Method for TotalMass Loss of Materials and Condensation ofOutgassed Volatiles on Microelectronics-RelatedSubstrates" (1989).

252

15. ASTM F1982-99: "Standard Test Methods forAnalyzing Organic Contaminants on Silicon WaferSurfaces by Thermal Desorption GasChromatography", West Conshohocken, ASTM(1999).

16. SEMI E108-0301: "Test Method for TheAssessment of Outgassing Organic Contaminationfrom Minienvironments Using GasChromatography/Mass Spectroscopy" (2001).

17. IEST WG CC031 Ongoing Activity:Recommended Practice for CharacterizingOutgassed Organic Compounds from CleanroomMaterials and Components.

18. Kumar, A., Ahmed, L., and Camenzind, M.J.,MICRO, 41-48 (January, 2001).

19. Takeda, K., Mochizuki, A., Nonaka, T.,Matsumoto, L, Fujimoto, T., and Nakahara, T.,"Evaluation of Outgassing Compounds fromCleanroom Construction Materials", IEST 2000ESTECH Conference Proceedings, pp. 71-77(2000).

20. MacDonald, S., Clecak, N., Wendt, H., Willson,G., Snyder, C., Knors, C, Deyoe, N., Maltabes, J.,Morrow, J., McGuire, A., and Holes, S., Proc. Soc.Photo-Opt. Instr. Eng., 1466, pp 2012 (1991).

21. Ito, H., Breyta, G. and Hofer, D., Proc. of SPIE,2438, 53-60 (1995).

22. Sun, P., and Adams, M., MICRO, 41-46 (April,1999).

253