Overview

General comment

Production covered

Gallium Arsenide based Vertical-Cavity Surface-Emitting Laser (VCSEL) for 850nm optical communication. Surface-emitting design with DBR mirrors enables wafer-level test, high-density arrays, and low-cost manufacturing. Used in multimode fiber applications for short-reach datacenter interconnects (100m).

This variant represents fabrication at Coherent/Lumentum US III-V photonics (Oregon/US-WECC proxy) using electricity from the United States Western grid (WECC).

This dataset represents operation with moderate PFC gas recovery and moderate water recycling.

Modelling choices

Facility nitrogen generated on site is excluded from the purchased-mass inventory because its generation and delivery are represented as facility electricity under the SEMI S23 utility-energy convention. Nitrogen used directly by wafer processes remains included as a mass input drawn from the same on-site product stream, so it has no purchased-liquid market link. The facility electricity includes nitrogen generation only.

Support energy is allocated using 3,000 wafer starts per month. That capacity represents one fab phase or production module at a high-volume site, not the combined output of a multi-phase campus.

Gas abatement (POU + central scrubber) is allocated as a flat per-wafer facility charge, not scaled per etch/CVD pass. The epitaxy record this dataset reads states that its own water covers the cooling and the scrubbing its reactor needs, so the facility cooling tower and scrubber makeup that the support calculation charges for that tool visit is not charged again here. What remains of that makeup is a whole-wafer facility allocation, and no source divides it between the epitaxy reactor and the other steps of the flow.

Scope in detail

Operational scenario scope: the scenario changes fluorinated-gas emissions to air (SF6, CF4, C4F8, CHF3 and the CF4/COF2/SO2F2 abatement byproducts that scale on destroyed mass), the NET purchased quantity of the two gases wired to recovery on the purchase side rather than the emission side (neon, and EUV-lithography hydrogen where the process carries EUV passes - which is why those two purchase rows move between scenario cells), and fresh-water intake and wastewater. It does not change NF3, whose remote-plasma clean consumes the large majority of the charge inside the chamber, so the industry control is abatement of the small residue rather than recovery; nor the cryogenic HF/PF3 etch feeds, which are scrubbed rather than captured; nor any in-chamber reaction product. The utilisation and recovery fractions behind those statements are stated with the scenario definition that this dataset's name carries.

Manufacturing-region scope: the regional options of this family swap the electricity market this dataset draws from, and the regional supplier entry for those few upstream chemicals and gases whose supplier data is published by region. They change nothing else. Facility heating, ventilation and cooling energy stays on the region the process data was built for, so per-unit energy is the same across the regional options; water, process chemicals, gases, materials, process emissions and solid waste are the same as well. Every inventory row of these regional datasets is therefore expected to match. What the separate datasets carry is the background market each region draws on.

Technology: Standard manufacturing process
Geography: Representative region: United States, WECC (Coherent/Lumentum/IQE III-V photonics; per-technology region). A japan option (Sony-class VCSEL) ships as a separate dataset.

Terms used above

PFC perfluorinated compounds; in power-supply contexts, power-factor correction
POU point of use

System boundary

The figure groups this dataset's unit processes by class. It is not a count of manufacturing steps — each process runs over as many passes as the flow requires, and those pass counts ship with the dataset.

Download this figure (SVG)

Data quality and references

Composite DQI 2.4 Good

Reliability

2.6

Completeness

2.7

Temporal

2.0

Geographic

1.9

Technological

2.9

How the score is calculated: Sources used across more manufacturing steps have more influence. Sources that define assumptions for the whole model account for 88.2% of the total weighting.

Pedigree scores follow the ecoinvent data-quality matrix: 1 is the best attainable, 5 the weakest. The composite is their aggregate.

Sampling procedure: Component vendor specifications, academic papers, industry literature
Coverage status: Partial
Pedigree-scored source files: 8 — the source records behind this dataset's manufacturing operations. Each carries the five pedigree axes above; the composite DQI aggregates them.

Technosphere inputs

21 flows. Quantities are not published; they ship with the dataset on Circa.

TMGa production Process gasg · -40% / +50%

Derivation basis: Equipment vendor specs, academic literature

No source is attached to this row.
Source citations: Not stated
Upstream REEL dataset: Trimethylgallium (Ga(CH3)3)
Background dataset: Modelled by REEL; see the upstream dataset above.
Uncertainty: -40% / +50% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

TMAl production Process gasg · -40% / +53.3%

Derivation basis: Calculated by the manufacturing model. The linked REEL dataset carries the upstream life cycle sources.

No source is attached to this row.
Source citations: Not stated
Upstream REEL dataset: Trimethylaluminum (Al(CH3)3)
Background dataset: Modelled by REEL; see the upstream dataset above.
Uncertainty: -40% / +53.3% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

TMIn production Process gasg · -50% / +66.7%

Derivation basis: Calculated by the manufacturing model. The linked REEL dataset carries the upstream life cycle sources.

No source is attached to this row.
Source citations: Not stated
Upstream REEL dataset: Trimethylindium (In(CH3)3)
Background dataset: Modelled by REEL; see the upstream dataset above.
Uncertainty: -50% / +66.7% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

SF₆ production Process gasg · -50% / +100%

Derivation basis: Calculated by the manufacturing model. The linked REEL dataset carries the upstream life cycle sources.

No source is attached to this row.
Source citations: Not stated
Upstream REEL dataset: Sulfur hexafluoride (SF6)
Background dataset: Modelled by REEL; see the upstream dataset above.
Uncertainty: -50% / +100% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

TMAH Developer (2.38% solution) Process chemicalg · -30% / +50%

Derivation basis: Calculated by the manufacturing model. The linked REEL dataset carries the upstream life cycle sources.

No source is attached to this row.
Source citations: Not stated
Upstream REEL dataset: TMAH Developer (2.38% solution) (N(CH3)4OH (aq))
Background dataset: Modelled by REEL; see the upstream dataset above.
Uncertainty: -30% / +50% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

ArF Photoresist Process chemicalg · -33.3% / +50%

Derivation basis: Calculated by the manufacturing model. The linked REEL dataset carries the upstream life cycle sources.

No source is attached to this row.
Source citations: Not stated
Upstream REEL dataset: ArF Photoresist (193nm)
Background dataset: Modelled by REEL; see the upstream dataset above.
Uncertainty: -33.3% / +50% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Water supply (municipal) Waterm3 · -18.9% / +25.5%

Derivation basis: Calculated from process-water and ultrapure-water demand across all manufacturing operations, plus facility water allocated to each finished unit. The fresh intake shown is that demand less the share reused under the water-recycling scenario this dataset assumes, and wastewater follows the same balance.

No source is attached to this row.
Source citations: Not stated
Upstream REEL dataset: Water Supply (Municipal)
Background dataset: Modelled by REEL; see the upstream dataset above.
Notes: Net fresh-water intake, supplied as municipal water
Uncertainty: -18.9% / +25.5% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: m3

Electricity, United States – Western Grid (WECC) ElectricitykWh · -20.9% / +27%

Derivation basis: Calculated from equipment energy across all manufacturing operations, plus facility support such as cleanroom HVAC, ultrapure water, cooling, gas abatement, and bulk gases.
Facility nitrogen electricity is rebased from the reference fab by wafer area. Its uncertainty band varies delivered energy intensity only; the estimate-class reference volume is unbanded. Direct process nitrogen remains an on-site product mass under cutoff accounting.

The sources below come from the manufacturing operations behind this row.
Sources (inherited): Inherited, rolled up from the contributing process steps:

Hu et al. (2019). Analysis of energy efficiency improvement of high-tech fabrication plants. International Journal of Low-Carbon Technologies. DOI: 10.1093/ijlct/ctz041.

Liu, Elgowainy and Wang (2020), Green Chemistry 22, 5751-5761, DOI 10.1039/D0GC02301A
Background data: ecoinvent 3.12
Background dataset: electricity, high voltage
Uncertainty: -20.9% / +27% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: kWh

AsH₃ Process gasg · -37.5% / +50%

Derivation basis: Calculated from per-operation consumption, operation counts, and manufacturing yield.

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12
Background dataset: arsine
Uncertainty: -37.5% / +50% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

H₂ Process gasg · -30% / +40%

Derivation basis: Calculated from per-operation consumption, operation counts, and manufacturing yield.

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12
Background dataset: hydrogen, gaseous, low pressure
Uncertainty: -30% / +40% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

SiH₄ Process gasg · -67% / +200%

Source citations: DOE/PNNL PNNL-21443 Table 5-4 silane supply for 100 mm MOCVD epitaxy, via the blue-LED MOCVD epitaxy record in this database
Background data: ecoinvent 3.12
Background dataset: silicon tetrahydride
Uncertainty: -67% / +200% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Cl₂ Process gasg · -33.3% / +66.7%

Derivation basis: Calculated from per-operation consumption, operation counts, and manufacturing yield.

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12
Background dataset: chlorine, liquid
Uncertainty: -33.3% / +66.7% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Ar Process gasg · ±50%

Derivation basis: Calculated from per-operation consumption, operation counts, and manufacturing yield.

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12
Background dataset: argon, liquid
Uncertainty: ±50% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

H₂O Process gasg · -40% / +50%

Derivation basis: Calculated from per-operation consumption, operation counts, and manufacturing yield.

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12
Background dataset: water, deionised
Uncertainty: -40% / +50% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Natural gas, burned in industrial furnace (facility heating, low-NOx) Process chemicalMJ · -33.3% / +41.7%

Derivation basis: Scaled from the InP epitaxy basis

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12
Background dataset: heat production, natural gas, at industrial furnace low-NOx >100kW
Uncertainty: -33.3% / +41.7% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: MJ

Acetone Process chemicalg · -30% / +50%

Derivation basis: Calculated from per-operation consumption, operation counts, and manufacturing yield.

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12
Background dataset: acetone, liquid
Uncertainty: -30% / +50% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Isopropanol Process chemicalg · -31.3% / +50%

Derivation basis: Calculated from per-operation consumption, operation counts, and manufacturing yield.

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12
Background dataset: isopropanol
Uncertainty: -31.3% / +50% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Gold (contacts and pads) Materialg · -33.3% / +50%

Derivation basis: Calculated from per-operation consumption, operation counts, and manufacturing yield.

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12
Background dataset: gold
Uncertainty: -33.3% / +50% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Titanium (adhesion) Materialg · ±50%

Derivation basis: Calculated from per-operation consumption, operation counts, and manufacturing yield.

No source is attached to this row.
Source citations: Not stated
Background data: proxy-mapped
Background dataset: titanium dioxide
Uncertainty: ±50% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Platinum (barrier) Materialg · -33.3% / +67%

Derivation basis: Calculated from per-operation consumption, operation counts, and manufacturing yield.

No source is attached to this row.
Source citations: Not stated
Background data: proxy-mapped
Background dataset: palladium
Uncertainty: -33.3% / +67% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

HMDS (adhesion promoter) Process chemicalg · -40% / +60%

Derivation basis: Calculated from per-operation consumption, operation counts, and manufacturing yield.

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12
Background dataset: hexamethyldisilazane
Uncertainty: -40% / +60% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Outputs and waste

Wastewater Wastewaterm3 · -18.9% / +25.5%

Derivation basis: Calculated from the water balance: fresh-water input minus evaporation.

No source is attached to this row.
Source citations: Not stated
Background data: carried, no background dataset
Background dataset: No treatment route recorded for this output.
Uncertainty: -18.9% / +25.5% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: m3

Arsenic-bearing scrubber sludge (As2O3) Solid wasteg · -39.8% / +53%

Derivation basis: Mass balance on the arsine input; 2 AsH3 + 3 O2 -> As2O3 + 3 H2O

The sources below are this dataset's own bibliography. They are not tied to this row.
Source citations (dataset-level): Inherited from this dataset's own bibliography, not tied to this row:

patents.google.com (date not recorded). US 7,364,603 B2 - Applied Materials / ATMI (Sweeney, Marganski, Olander), sorbent system for hazardous gas abatement. Patent.

patents.google.com (date not recorded). EP 1 637 208 A1 - abatable species list and bed geometry. Patent.

cscleansystemsbenelux.com (date not recorded). CS Clean Solutions - Exhaust Gas Treatment product catalogue (CLEANSORB dry-bed chemisorption). Vendor catalogue.

DOE/PNNL PNNL-21443 Table 5-4 silane supply for 100 mm MOCVD epitaxy, via the blue-LED MOCVD epitaxy record in this database

Molar read-across of the sourced Cp2Mg p-dopant supply in the blue-LED MOCVD epitaxy record in this database (arXiv:2203.10654)

IPCC 2019 Guidelines Vol 3 Ch 6

EPA 40 CFR Part 98 Subpart I (2024)
Background data: ecoinvent 3.12 treatment route
Background dataset: treatment of hazardous waste, underground deposit
Uncertainty: -39.8% / +53% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Spent scrubber media (arsenic-loaded) Solid wasteg · -29.9% / +593.7%

Source citations: patents.google.com (date not recorded). US 7,364,603 B2 - Applied Materials / ATMI (Sweeney, Marganski, Olander), sorbent system for hazardous gas abatement. Patent.
patents.google.com (date not recorded). EP 1 637 208 A1 - abatable species list and bed geometry. Patent.
cscleansystemsbenelux.com (date not recorded). CS Clean Solutions - Exhaust Gas Treatment product catalogue (CLEANSORB dry-bed chemisorption). Vendor catalogue.
Background data: ecoinvent 3.12 treatment route
Background dataset: treatment of hazardous waste, underground deposit
Uncertainty: -29.9% / +593.7% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Chamber deposits (arsenic-bearing metal residue) Solid wasteg · -37.5% / +50%

Derivation basis: Calculated from the mass balance of spent materials and consumables, with treatment selected from the waste classification.

The sources below are this dataset's own bibliography. They are not tied to this row.
Source citations (dataset-level): Inherited from this dataset's own bibliography, not tied to this row:

patents.google.com (date not recorded). US 7,364,603 B2 - Applied Materials / ATMI (Sweeney, Marganski, Olander), sorbent system for hazardous gas abatement. Patent.

patents.google.com (date not recorded). EP 1 637 208 A1 - abatable species list and bed geometry. Patent.

cscleansystemsbenelux.com (date not recorded). CS Clean Solutions - Exhaust Gas Treatment product catalogue (CLEANSORB dry-bed chemisorption). Vendor catalogue.

DOE/PNNL PNNL-21443 Table 5-4 silane supply for 100 mm MOCVD epitaxy, via the blue-LED MOCVD epitaxy record in this database

Molar read-across of the sourced Cp2Mg p-dopant supply in the blue-LED MOCVD epitaxy record in this database (arXiv:2203.10654)

IPCC 2019 Guidelines Vol 3 Ch 6

EPA 40 CFR Part 98 Subpart I (2024)
Background data: ecoinvent 3.12 treatment route
Background dataset: treatment of hazardous waste, underground deposit
Uncertainty: -37.5% / +50% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

GaAs substrate edge-exclusion scrap (arsenic-bearing metal) Solid wasteg · -33.3% / +50%

Derivation basis: Calculated from the mass balance of spent materials and consumables, with treatment selected from the waste classification.

The sources below come from the manufacturing operations behind this row.
Sources (inherited): Inherited, rolled up from the contributing process steps:

patents.google.com (date not recorded). US 7,364,603 B2 - Applied Materials / ATMI (Sweeney, Marganski, Olander), sorbent system for hazardous gas abatement. Patent.

patents.google.com (date not recorded). EP 1 637 208 A1 - abatable species list and bed geometry. Patent.

cscleansystemsbenelux.com (date not recorded). CS Clean Solutions - Exhaust Gas Treatment product catalogue (CLEANSORB dry-bed chemisorption). Vendor catalogue.

DOE/PNNL PNNL-21443 Table 5-4 silane supply for 100 mm MOCVD epitaxy, via the blue-LED MOCVD epitaxy record in this database

Molar read-across of the sourced Cp2Mg p-dopant supply in the blue-LED MOCVD epitaxy record in this database (arXiv:2203.10654)
Background data: ecoinvent 3.12 treatment route
Background dataset: treatment of hazardous waste, underground deposit
Uncertainty: -33.3% / +50% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Photoresist waste Solid wasteg · -33.3% / +66.7%

Derivation basis: Calculated from the mass balance of spent materials and consumables, with treatment selected from the waste classification.

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12 treatment route
Background dataset: treatment of hazardous waste, hazardous waste incineration, with energy recovery
Uncertainty: -33.3% / +66.7% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Etch byproduct scrubber sludge (III-V/nitride metal chlorides) Solid wasteg · -40% / +60%

Derivation basis: Calculated from the mass balance of spent materials and consumables, with treatment selected from the waste classification.

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12 treatment route
Background dataset: treatment of hazardous waste, underground deposit
Uncertainty: -40% / +60% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Metal overspray Solid wasteg · ±50%

Derivation basis: Calculated from the mass balance of spent materials and consumables, with treatment selected from the waste classification.

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12 treatment route
Background dataset: treatment of hazardous waste, underground deposit
Uncertainty: ±50% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Scrapped material (line yield) Solid wastem2 · -72.2% / +58.8%

Source citations: csmantech.org (date not recorded). Wei et al. (Wavetek Microelectronics / UMC), "Wavetek's GaAs Manufacturing in UMC's 6-inch CMOS Fab", CS MANTECH 2014. PDF document.
csmantech.org (date not recorded). Welch & Faria (MAX I.E.G.), "Continual Improvement of Cumulative Yield in GaAs Wafer Fabrication", CS MANTECH 2021, 9.4. PDF document.
microlab.berkeley.edu (date not recorded). Leachman & Hodges, "Benchmarking Semiconductor Manufacturing" (CSM 28-fab IRW paper). PDF document.
ieor.berkeley.edu (date not recorded). Leachman (ed.), "The Competitive Semiconductor Manufacturing Survey - Third Report on Results of the Main Phase" (CSM-52), UC Berkeley, 2002. PDF document.
Background data: ecoinvent 3.12 treatment route
Background dataset: treatment of hazardous waste, underground deposit
Notes: Calculated reject material after accounting for a manufacturing yield of 90%. Wafer starts that do not complete processing, at the modeled line yield of 90 percent. Line yield here counts test, monitor, and damaged wafers against wafers processed - the inclusive convention of the cited fab benchmarking and life cycle studies. The 0.85 to 0.97 uncertainty band on the yield spans measured multi-fab benchmarking: the low end reflects below-average lines and deep multi-layer flows; the high end reflects the best benchmarked lines, which reach about 97 to 98 percent. A volume gallium-arsenide production line reports line yield above 97 percent; the 90 percent value is a conservative central within the band.
Uncertainty: -72.2% / +58.8% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: m2

Emissions to air

6 elementary flows released to air by this dataset's own operations. Quantities are not published; they ship with the dataset on Circa.

In(CH₃)₃ Emission to airg

Derivation basis: Calculated as an air release, from a mass balance on the process gases going in, with the destruction or removal efficiency of any point-of-use abatement applied.
No corresponding ecoinvent dataset or flow was identified for this entry, so it is published with its own quantity and no background link

No source is attached to this row.
Source citations: Not stated
Compartment: Air (non-urban air or from high stacks)
CAS number: 3385-78-2
ecoinvent 3.12 elementary flow: Not stated
Uncertainty: A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit: g

CBr4 Emission to airg

Derivation basis: No corresponding ecoinvent dataset or flow was identified for this entry, so it is published with its own quantity and no background link

The sources for this row are listed below.
Source citations: Molar read-across of the sourced Cp2Mg p-dopant supply in the blue-LED MOCVD epitaxy record in this database (arXiv:2203.10654)
Compartment: Air
ecoinvent 3.12 elementary flow: Not stated
Uncertainty: A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit: g

Hydrogen chloride Emission to airg

Derivation basis: Calculated as an air release, from a mass balance on the process gases going in, with the destruction or removal efficiency of any point-of-use abatement applied.

No source is attached to this row.
Source citations: Not stated
Compartment: Air (non-urban air or from high stacks)
Formula: HCl
CAS number: 7647-01-0
ecoinvent 3.12 elementary flow: Hydrochloric acid
Notes: BCl3 + 3H2O → B(OH)3 + 3HCl; air HCl = stoich×0.02 scrubber slip (cross-compartment split)
Uncertainty: A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit: g

Cl₂ Emission to airg

Derivation basis: Calculated as an air release, from a mass balance on the process gases going in, with the destruction or removal efficiency of any point-of-use abatement applied.

No source is attached to this row.
Source citations: Not stated
Compartment: Air (non-urban air or from high stacks)
CAS number: 7782-50-5
ecoinvent 3.12 elementary flow: Chlorine
Uncertainty: A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit: g

SF₆ Emission to airg

Derivation basis: Calculated as an air release, from a mass balance on the process gases going in, with the destruction or removal efficiency of any point-of-use abatement applied.

No source is attached to this row.
Source citations: Not stated
Compartment: Air (non-urban air or from high stacks)
CAS number: 2551-62-4
ecoinvent 3.12 elementary flow: Sulfur hexafluoride
Uncertainty: A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit: g

H₂O Emission to airg

Derivation basis: Calculated as an air release, from a mass balance on the process gases going in, with the destruction or removal efficiency of any point-of-use abatement applied.

No source is attached to this row.
Source citations: Not stated
Compartment: Air (non-urban air or from high stacks)
CAS number: 7732-18-5
ecoinvent 3.12 elementary flow: Water
Uncertainty: A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit: g

Emissions to water

2 elementary flows released to water by this dataset's own operations. Quantities are not published; they ship with the dataset on Circa.

Chloride Emission to waterg

Derivation basis: Calculated as a release to water, from a contaminant mass balance on the process chemistry.

No source is attached to this row.
Source citations: Not stated
Compartment: Water (surface water)
Formula: Cl-
CAS number: 16887-00-6
ecoinvent 3.12 elementary flow: Chloride
Notes: BCl3 scrubbed Cl⁻ to wastewater (98% POU scrubber; Cl⁻/HCl mass ratio 35.45/36.46)
Uncertainty: A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit: g

As Emission to waterg

Derivation basis: Mass balance on the arsine input; precipitation removal follows the arsenic effluent convention used for implant scrubber discharge in this database

No source is attached to this row.
Source citations: Not stated
Compartment: Water (surface water)
CAS number: 7440-38-2
ecoinvent 3.12 elementary flow: Arsenic ion
Uncertainty: A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit: g

Flows not quantified

5 flows are recorded for this dataset but carry no quantity — cut off below the significance threshold, or with no background dataset available. They remain inside the declared system boundary; each is listed with its reason.

Cut off - below the significance threshold (3)

GaAs <001> n-doped (Si) substrate Substrate materialm2 · -7.2% / +5.9%

Derivation basis: Calculated from per-operation consumption, operation counts, and manufacturing yield.

No source is attached to this row.
Source citations: Not stated
Background data: cut off
Background dataset: Not applicable: this flow is not quantified in the inventory.
Notes: GaAs <001> n-doped (Si) substrate (100mm diameter, 0.007854 m2)
Reason: No wafer-level production dataset available in ecoinvent for GaAs <001> n-doped (Si). Raw material datasets (e.g. gallium, silicon carbide powder) exist but miss crystal growth and wafering which dominate the environmental footprint.
Uncertainty: -7.2% / +5.9% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: m2

N₂ Process gasg · -32% / +46%

Derivation basis: This quantity is process nitrogen rather than a facility allocation. The model draws its bulk nitrogen from an on-site generator, and the energy that generator uses is carried in the facility electricity, so no capacity-scaled facility base is added to this row. What the row contains is the purge nitrogen the lithography, etch and deposition passes of this process flow consume, together with the nitrogen the contributing process files author for their own steps. The intervals those process files publish carry through into the interval shown here, while the per-pass purge allowance is a point estimate that is held at the same value at both ends of it.

No source is attached to this row.
Source citations: Not stated
Background data: cut off
Background dataset: Not applicable: this flow is not quantified in the inventory.
Reason: Direct process nitrogen is retained as inventory mass drawn from the on-site product stream. Its generation and delivery are carried in facility electricity, so a purchased-liquid market link would duplicate the upstream supply burden.
Uncertainty: -32% / +46% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

BCl₃ Process gasg · -40% / +60%

Derivation basis: Calculated from per-operation consumption, operation counts, and manufacturing yield.

No source is attached to this row.
Source citations: Not stated
Background data: cut off
Background dataset: Not applicable: this flow is not quantified in the inventory.
Reason: Boron trichloride is consumed at low rate in metal etch, and no production dataset for it exists in the background database used for linkage. It is scrubbed in wet abatement and its primary emission product, hydrogen chloride, is tracked separately in this inventory, so no upstream production dataset is attached here.
Uncertainty: -40% / +60% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Not quantified - no background dataset available (2)

CBr4 Process gasg · -66.7% / +200%

Source citations: Molar read-across of the sourced Cp2Mg p-dopant supply in the blue-LED MOCVD epitaxy record in this database (arXiv:2203.10654)
Background data: no background dataset
Background dataset: Not applicable: this flow is not quantified in the inventory.
Reason: The carbon dopant precursor for compound-semiconductor epitaxy. No carbon-tetrabromide production activity exists in the background database used for linkage. Elemental bromine is mapped in this inventory, but making a brominated methane is not what bromine production represents, so it is not substituted. The quantity is recorded here and its upstream production is left unlinked.
Uncertainty: -66.7% / +200% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Scrubber media (dry-bed chemisorbent) Process chemicalg · -29.9% / +593.7%

Source citations: patents.google.com (date not recorded). US 7,364,603 B2 - Applied Materials / ATMI (Sweeney, Marganski, Olander), sorbent system for hazardous gas abatement. Patent.
patents.google.com (date not recorded). EP 1 637 208 A1 - abatable species list and bed geometry. Patent.
cscleansystemsbenelux.com (date not recorded). CS Clean Solutions - Exhaust Gas Treatment product catalogue (CLEANSORB dry-bed chemisorption). Vendor catalogue.
Background data: no background dataset
Background dataset: Not applicable: this flow is not quantified in the inventory.
Reason: Purchased granulate for point-of-use dry-bed abatement of hydride process gases. No chemisorbent or sorbent abatement-medium activity exists in the background database used for linkage. Its burden is dominated by the impregnated reactive phase that makes it a scavenger, and vendors do not disclose that chemistry, so a generic carbon-supported substitute would carry the wrong material. The quantity is recorded here and its upstream production is left unlinked.
Uncertainty: -29.9% / +593.7% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Limitations and unquantified flows (2)

Limits this dataset declares about itself: first any limit stated in its own description, then any limit it declares flow by flow, grouped by channel. Each entry below is the model's own disclosure.

From the dataset description

Supply energy for argon, oxygen, and clean dry air is excluded because the former aggregate provides no defensible component split. The energy-only convention also omits upstream gas-plant infrastructure, transport losses, and other non-electricity burdens associated with delivered liquid nitrogen.
At most the whole of the cooling tower and scrubber makeup remaining in the support charge is an overlap with the epitaxy record's own water; how much of it actually is remains unresolved, and the two are published as they stand.

The flows above are this dataset's own records. What follows are the scope rules set once for the whole database in the methodology report, repeated here so every dataset page carries them.

Database-wide boundary policy — applies to every REEL dataset

These boundaries are set once for the whole database, in Chapter 2 of the methodology report, and apply to this dataset wherever they are relevant to it. The excluded flows listed above are specific to this dataset.

Use phase: Product operation is outside the cradle-to-gate scope.
End-of-life treatment: Recycling and disposal are outside the cradle-to-gate scope.
Distribution and retail: The gate is a finished component ready for integration into a higher-level assembly.
Inbound transport of raw materials: Transport of purchased raw materials to the manufacturing facility is already inside the upstream "market for" datasets that users link to a background database, so it is not modelled a second time here. This does not cover freight between REEL production stages, which is modelled where a dataset authors it.
Returnable shipping containers: Where freight between production stages is modelled, the mass moved is the product itself. The shipping container (FOSB, SEMI M31) is returnable capital equipment whose per-trip share is unsourced, so its tare is excluded from the transport effort.
Photomask fabrication: A mask set's embodied burden is amortised across a high-volume production run and is not attributed per wafer. Users assessing low-volume production should add mask fabrication separately; the methodology report gives the basis for the exclusion.
Employee transport, administration and R&D overhead: Employee transportation, facility administration and R&D/pilot-production overhead are outside scope.
Capital goods: Manufacturing equipment, cleanroom construction and facility infrastructure are excluded, on the grounds of absent public data on equipment embodied energy, uncertainty in equipment lifetime and allocation, common practice in electronics LCA, and a focus on the operational inventory. Future versions may include capital goods when sufficient public data becomes available.
Precious metal recovery credits: Scrap recovery credits for precious metals are excluded pending data availability.
Wafer reclaim: Test wafers and scrap are outside the system boundary.

Inside the boundary, linked rather than modelled

Silicon ingot growth and wafer slicing: Inside the cradle-to-gate scope, but treated as upstream material inputs linked to background databases rather than modelled as REEL processes.
Freight between production stages: Where a dataset's product moves between REEL production stages - wafer fabrication to the packaging site, for example - that leg is authored as a transport service and linked to an ecoinvent freight activity. It is measured as a transport effort in tonne-kilometres, not as a mass. Route distances are authored per route class with a stated band; a lower bound of zero is a modelling statement that the two sites can be co-located, not a missing value.

Cut-off criteria

A flow is excluded from a process inventory when it contributes less than 1 % of the total mass of inputs to that unit process, or less than 1 % of its total energy input. The denominator is total process inputs, not product mass. That distinction matters in semiconductor manufacturing, where the input mass of water, chemicals and gases greatly exceeds the product mass, so the threshold removes only genuinely minor flows.

Included regardless of the cut-off

Perfluorocarbons (CF4, C2F6, SF6, NF3) - high GWP, EPA regulated
Heavy metals (Pb, Cd, Hg, Cr(VI)) - RoHS regulated, high toxicity
Volatile organics (photoresist solvents, PGMEA) - air quality
Precious metals (Au, Ag, Pd, Pt) - high embodied impacts
Ozone-depleting substances (legacy CFCs, HCFCs) - Montreal Protocol