Post on 02-Mar-2019
Evaluation and Analysis of III-V ESH Processing Hazards
SESHA Hill Country Chapter
December 8, 2011
Brett Jay Davis, PE Zephyr Environmental Corporation
I. Project Background II. SVTC Process Engineers Mini-Survey
Results III. Texas State University Epi Process Tool
Sample Set-Up and Analytical Results IV. SVTC Process Tools Sample Set-Up and
Analytical Results V. Arsenic Wastewater Treatment Technologies VI. Findings and Recommendations VII. Future Work VIII. Acknowledgements IX. Questions?
Presentation Outline
• Compound (traditional Periodic Table Groups III-V) semiconductor films are being deposited on silicon dioxide wafers, at Texas State Univ. (TSU) in San Marcos, Texas, with further processing at SVTC in Austin, Texas.
• Compound semiconductor processing utilizes a variety of III-V chemicals, such as arsenic, which have potentially unique ESH hazards.
• Little work has been performed to understand the hazards posed by process materials, by-products, effluents and emissions from these processes.
• To better understand the potential personnel and environmental exposures from III-V layering and processing, a detailed evaluation of processing operations was performed at TSU and SVTC, by Zephyr.
Project Background
Periodic Table of the Elements
Period
Group
1 IA 1A
18
VIIIA 8A
1 1 H
1.008
2 IIA 2A
13
IIIA 3A
14 IVA 4A
15 VA 5A
16 VIA 6A
17 VIIA 7A
2 He 4.003
2 3
Li 6.941
4 Be 9.012
5 B
10.81
6 C
12.01
7 N
14.01
8 O
16.00
9 F
19.00
10 Ne 20.18
3 11
Na 22.99
12 Mg 24.31
3 IIIB 3B
4 IVB 4B
5 VB 5B
6 VIB 6B
7 VIIB 7B
8 9 10 11 IB 1B
12 IIB 2B
13 Al 26.98
14 Si
28.09
15 P
30.97
16 S
32.07
17 Cl
35.45
18 Ar 39.95
------- VIII -------
------- 8 -------
4 19 K
39.10
20 Ca 40.08
21 Sc 44.96
22 Ti
47.88
23 V
50.94
24 Cr 52.00
25 Mn 54.94
26 Fe 55.85
27 Co 58.93
28 Ni 58.69
29 Cu 63.55
30 Zn 65.39
31 Ga 69.72
32 Ge 72.64
33 As 74.92
34 Se 78.96
35 Br 79.90
36 Kr 83.79
5 37
Rb 85.47
38 Sr
87.62
39 Y
88.91
40 Zr
91.22
41 Nb 92.91
42 Mo 95.94
43 Tc (98)
44 Ru 101.1
45 Rh 102.9
46 Pd 106.4
47 Ag 107.9
48 Cd 112.4
49 In
114.8
50 Sn 118.7
51 Sb 121.8
52 Te 127.6
53 I
126.9
54 Xe 131.3
6 55 Cs 132.9
56 Ba 137.3
* 72 Hf 178.5
73 Ta 180.9
74 W
183.9
75 Re 186.2
76 Os 190.2
77 Ir
192.2
78 Pt
195.1
79 Au 197.0
80 Hg 200.5
81 Tl
204.4
82 Pb 207.2
83 Bi
209.0
84 Po (209)
85 At (210)
86 Rn (222)
7 87 Fr
(223)
88 Ra (226)
** 104 Rf (261)
105 Db (262)
106 Sg (266)
107 Bh (264)
108 Hs (277)
109 Mt (268)
110 Ds (271)
111 Rg (272)
112 Cn (285)
113 Uut (286)
114 Uuq (289)
115 Uup (289)
116 Uuh (291)
117 Uus (294)
118 Uuo (294)
Lanthanide Series*
57 La 138.9
58 Ce 140.1
59 Pr
140.9
60 Nd 144.2
61 Pm (145)
62 Sm 150.4
63 Eu 152.0
64 Gd 157.2
65 Tb 158.9
66 Dy 162.5
67 Ho 164.9
68 Er
167.3
69 Tm 168.9
70 Yb 173.0
71 Lu 175.0
Actinide Series**
89 Ac (227)
90 Th 232
91 Pa 231
92 U 238
93 Np (237)
94 Pu (242)
95 Am (243)
96 Cm (247)
97 Bk (247)
98 Cf (251)
99 Es (252)
100 Fm (257)
101 Md (258)
102 No (259)
103 Lr (262)
III-V Process Risks Mini-Survey A. III-V Process Chemistries and By-Products
For the tools that you are familiar with, please complete the following table related to process
chemicals and suspected by-products and residues, during III-V processing only, i.e., normal processing and invasive tasks (such as troubleshooting, daily PMs and major PMs, but not “end of life” tool, infrastructure and process issues).
This information is needed to identify unique III-V process chemicals used and by-products
formed. The knowledge will inform the industrial hygiene and environmental sampling and analyses to be conducted for this project.
Process Type Tool ID Process Chemicals Suspected By - Products and Residues Engineer
(List all chemical inputs) (List all known by - products from chemical - wafer or equipment - wafer interactions)
Dry Etch - Dep CVD08 NH3, NF3, CF4 , N2O, C2F6, SiH4, PH3, N2, O3, He, O2, Ar, 3Ms (trimethyl silane)
Putting on layer of oxide/nitride. No concern Sidi
Dry Etch – PVD MTL06 N2, O2, Ar Min im al : sputtering may dislodge As /Sb Ed Dry Etch PET28BM Cl2, HBr , CH F3, CF4 , NF3, O2, He, O2, CO,
BC L3, N2, Ar (red used by III - V) As /S b containing by product gas, pumped out by system ; minutes in chamber
Gabe
Wet Etch WTS 07/8 HF, HCL, H2SO4, BOE, NH4OH As/Sb particles in che m i cal waste Mark Wet Etch WTS92 HF, HNO3 Back side clean, minim al waste Ray Wet Etch WTC04 H2O2, NH4OH, HCL, H2SO4, HF As/Sb particles in che m i cal waste Mark Deposition – ALD
ALD02PM1 Ar, O2, NH3, O3 Putting additional films . At high temp might be o ut - gassing As /Sb . Minutes to hours in chamber
Sidi
Deposition – ALD
ALD02PM2 A r, O3 Depositing oxide/nitride . No concern Sidi
Deposition – ALD
ALD02PM3 Ar, NH3, O3 Depositing oxide/nitride. No concern Sidi
CMP PLN93 H2O2, slurry, H2O As, Sb on pads Ed Asher ASH07 H2/N2, CF4, N2, O2 Affects resists, will be seeing some As/Sb John
III-V Process Risks Mini-Survey A. III-V Process Chemistries and By-Products (Continued) Potential Personnel Exposures
For the tools that you are familiar with, please list the materials that workers might possibly be exposed to during normal processing or preventive maintenance, during III-V processing and preventive maintenance after III-V processing. This information is needed to determine where industrial hygiene personnel sampling should be performed.
This information indicated that only As and AsH3 are new to silicon manufacturing and with sufficient toxicity to merit IH-type sampling.
Process Type Tool ID Clean Room Operator During Process Equipment Technician During Preventive Maintenance
(List potential exposure materials) (List potential exposure materials) Dry Etch – CVD CVD08 As , S b (only if a gas leak ) As, S b dust , flaking, broken wafers Dry Etch – PVD MTL06 None expected As, Sb dust, flaking, broken wafers Dry Etch PET28BM As , S b ? ( Other react ion gas? ) As, Sb dust, flaking, broken wafers Wet Etch WTS 07/8 NONE Filter changes, broken lines Wet Etch WTS92 NONE Filter changes, broken lines Wet Etch WTC04 NONE Filter changes, broken lines Deposition – ALD ALD02PM1 As , S b (only if a gas leak) As, Sb dust, flaking, broken wafers Deposition – ALD ALD02PM2 As , S b (only if a gas leak) As, Sb dust, flaking, broken wafers Deposition – ALD ALD02PM3 As , S b (only if a gas leak) As, Sb dust, flaking, broken wafers CMP PLN93 During Pad change out Contamin ated pads, broken wafers Asher ASH07 As, S b (only if a gas leak) As, Sb dust, flaking, broken wafers
III-V Process Risks Mini-Survey B. Likely Environmental Discharges
For the tools that you are familiar with, please complete the following table related to any materials discharged during III-V processing. This information is needed to determine which materials need to be sampled and analyzed.
This information indicated that only As and AsH3 are new to silicon manufacturing and with sufficient toxicity to merit environmental sampling.
Process Type Tool ID Wastewater Waste Wet Etch Acids Exhaust Air Chamber Surfaces (List Potential
Materials or Indicate None)
(List Potential Materials or Indicate None)
(List Potential Materials or Indicate
None)
(List Potential Materials or Indicate
None) Dry Etch – CVD CVD08 NONE NONE NONE NONE Dry Etch – PVD MTL06 NONE NONE As , Sb Dry Etch PET28BM NONE NONE As , Sb Wet Etch WTS 07/8 As , Sb HF, BOE (HF&HCL) , As, Sb NONE NONE Wet Etch WTS92 As, Sb HF, HCL, H2SO4, BOE,
NH4OH , As, Sb NONE NONE
Wet Etch WTC04 As, Sb H2O2, NH4OH, HCL, H2SO4, HF , As, Sb
NONE NONE
Deposition – ALD ALD02PM1 NONE NONE As, Sb Deposition – ALD ALD02PM2 NONE NO NE NONE Deposition – ALD ALD02PM3 NONE NONE NONE CMP PLN93 As, Sb, maybe H2O2, As, Sb maybe NONE As, Pb Asher ASH07 NONE NONE As , Sb
III-V Process Risks Mini-Survey
C. Opportunities for Sampling
For the tools that you are familiar with, please enter the projected timeframe of the next III-V processing and preventive maintenance activities, after III-V processing activity. This information is needed to schedule industrial hygiene sampling.
This information indicated that little maintenance sampling would be possible.
Process Type Tool ID Next III - V Processing Next Preventive Maintenance
(Approximate Date(s )) (Approximate Date(s))
Dry Etch – CVD CVD08 Once a month to once every 2 months
Dry Etch – PVD MTL06 Once a week
Dry Etch PET28BM Never
Wet Etch WTS 07/8 Bath changes approx 1/week
Wet Etch WTS92 Every Wednesday
Wet Etch WTC04 Bath changes ap prox 1/week
Deposition – ALD ALD02PM1 Rarely
Deposition – ALD ALD02PM2 Rarely
Deposition – ALD ALD02PM3 Rarely
CMP PLN93 Toss pads weekly
Asher ASH07 1/year
III. Texas State University Epi Process Tool Sample Set-Up and Analytical Results
Note: In all cases, for arsine air sampling, a modified NIOSH 6001 method, inclusive of a pre-filter, was used and for arsenic air sampling, a modified NIOSH 7300 method was used. For arsenic surface sampling, the NIOSH 9100 method was used.
Epi Tool at Texas State University
Back of tool showing pumps collecting from exhaust and near back of reactor
Close up of exhaust sample system
Exhaust Sample System
Filter cassette for arsenic = Modified NIOSH 7300 Method
Sampling pumps – High flow for arsenic, low flow for arsine
Sorbent tube for arsine – Note filter cassette pre-filter = Modified NIOSH 6001 Method
Inside load lock - wipe collected from bottom
Load lock chamber lid – wipe collected from botton
Epi Tool at Texas State University
Epi Tool Analytical Results
* Wipes are typically for 100 cm2 of surface. Action level typically 50 ug. BDL <0.11 ug for Arsine and <0.15 ug for Arsenic in air samples BDL <1 ug for wipes
IV. SVTC Process Tools Sample Set-Up and Analytical Results
Note: The asher and CMP tools were not included in the SVTC processing scheme and therefore were not sampled. Wastewater was not sampled as drain lines at SVTC did not have existing sampling ports. The wet etch tool WTS07/08 was replaced by the wet hood WTS91.
WTC04 Front Sample System 2
WTC04 Front Sample System
Chemicals in use: hydrochloric acid, ammonium hydroxide
Wet Clean Tool at SVTC
ALD02 Exhaust Sample System 2
ALD02 Front Sample System
Chemicals in use: ozone, trimethyl aluminum and argon
Deposition Tool at SVTC
WTS91 Front
WTS91 Spin Rise Dryer Sample System
Chemicals in use: dilute phosphoric acid and hydrogen peroxide
Second Wet Etch Tool at SVTC
Second Wet Etch Tool Analytical Results
BDL <0.11 ug for Arsine and< 0.15 ug for Arsenic (in air) and <1 mg/Kg (in liquid)
MTL06 Maintenance Sample System
MTL06 Maintenance Sample System
Metal sources in use: molybdenum, ruthenium, tungsten, hafnium
Metal Deposition Tool at SVTC
MTL06 Open Maintenance Sample System
MTL06 Target Maintenance Sample System
Metal Deposition Tool at SVTC
MTL06 Wafer Stand Wipe
MTL06 Target Perimeter Wipe
Chemicals in use: argon and nitrogen
Metal Deposition Tool at SVTC
Metal Deposition Tool Analytical Results
BDL <0.11 ug for Arsine and < 0.15 ug for Arsenic for air samples BDL <1 ug for wipes
Sampling Results Summary
• Except for the MBE tool load lock, no arsenic or arsine was detected at above analytical detection method limits. – Note: Due to the short process and
sampling durations, this information cannot be correlated with personnel exposure limits, which are typically defined as average exposures over eight-hours.
• ACGIH TLV-TWA = 0.005 ppm ASH3
• ACGIH TLV-TWA = 0.01 mg/m3 As
Arsenic Contaminated Wastewater Treatment Technologies
• In early 2011, Zephyr was retained by ISMI to perform an assessment of available arsenic removal technologies.
• The purpose of the project was to provide guidance on the possible treatment of arsenic from the application and processing of compound (III-V) semiconductor films on silicon oxide substrates, as presently being demonstrated at SVTC in Austin, Texas.
• The resulting table of available technologies and their capabilities and limitations follows.
Findings and Recommendations
As expected: • Dry semiconductor processing of silicon wafers with gallium
arsenide films, did not liberate arsenic or arsine into the workspace (at least not above detection limits).
• Wet semiconductor processing of silicon wafers with gallium arsenide films, did not liberate arsenic or arsine into the workspace or into an acid bath (at least not above detection limits).
This project did not detect EHS hazards that would require additional personnel protection or environmental controls, however: • It is advisable to perform personnel monitoring for III-V
processing at a production facility, preferably with lower method detection limits than those available for this project.
Future Work
• Investigate ability to obtain lower detection limits – Portable FTIR? • Perform wipe sample on load lock before and after processing • Sample for off-gassing from wafer box • Sample during maintenance of all wet and dry tools • Sample wastewater discharged from wet etch and CMP processing • Sample metal deposition tool exhaust • Analyze waste wafers for TCLP concentrations • Investigate need to repeat project for other Group V semiconductor
compounds, such as antimony and bismuth
Acknowledgements
This project was successful thanks to the following people:
• The Banker – Steve Trammell, ISMI • The Architects – Niti Goel, Wei-E Wang and Kevin Wolfe,
Intel • The Superintendent – Bob Bianconi, SVTC • The Foremen – Barry Sassman and Melvin Cruz, ISMI • The Builders – Tiffany Giles and Jeanne Yturri, Zephyr • The Inspectors – Sara Brenner and Hallie Morgan, CNSE,
and Galson Laboratories