Overview

General comment

Production covered

The composite model includes sixteen 3D NAND core dies, a paired CMOS peripheral wafer, CBA wafer bonding, one thinned base logic die, TSV stacking, and known-good-die testing.

System boundary: this dataset ends at the assembled and tested stack. Silicon interposer, advanced-package redistribution, organic package substrate, and package-level assembly are deliberately excluded; those are owned by the consuming packaging dataset under the count-once convention. Accelerator and module assembly are also outside this dataset boundary.

Modelling choices

The model uses the nominal 10.975 mm x 16 mm device envelope in OCP High Bandwidth Flash Architecture Specification v0.7.0 as the core, CMOS-peripheral, and base-die footprint.

The central yield is exp(-0.005 defects/mm2 x 175.6 mm2) = 0.416; holding the prior 0.670 yield represents the favorable bad-block-absorption bound.

The 232-layer NAND, mature 65 nm peripheral, and mature 28 nm base-die processes are proxies because the OCP architecture specification does not define fabrication nodes, layer count, or the die-thickness split.

Loose-material BOM quantities represent manufacturing input demand before stage-yield losses, while the finished-stack mass sums only retained, geometry-bounded material.

Technology: HBF Gen1 16Hi
Geography: Global average – SanDisk/Kioxia (Japan), SK Hynix (Korea), Samsung (Korea)

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 2.2 Good

Reliability

3.0

Completeness

1.9

Temporal

1.8

Geographic

2.0

Technological

2.3

How the score is calculated: Constituent datasets have more influence when they contribute a larger share of the modelled cradle-to-gate energy demand.

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

Sampling procedure: No production data. Estimate built from: SanDisk HBF architecture specifications (2025), SK Hynix H3 simulation paper (IEEE, Feb 2026), existing REEL LCI models for 3D NAND wafer fab and HBM TSV stacking, equipment vendor specifications (Applied Materials), academic literature on hybrid bonding and TSV processes. Components with limited direct production data use the CBA Wafer Bonding process inventory, the 28nm Planar HKMG wafer dataset for the base logic die, and the Wafer Probe Test process inventory at three times the NAND test intensity.
Coverage status: Composed from linked REEL datasets
Pedigree-scored source files: 50 — the source records behind this dataset's manufacturing operations. Each carries the five pedigree axes above; the composite DQI aggregates them.

Technosphere inputs

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

NAND Core Dies REEL datasetwafer

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: 3D NAND 232L wafer, 300mm, moderate scenario, conventional etch
Background dataset: Modelled by REEL; see the upstream dataset above.
Notes: Wafer demand calculated from die count, rectangular wafer packing, die yield and assembly yield. Wafer manufacturing yield is already included upstream.
Uncertainty: No range defined.
Unit: wafer

CMOS Peripheral Wafer REEL datasetwafer

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: 65nm Planar wafer, 300mm, moderate scenario
Background dataset: Modelled by REEL; see the upstream dataset above.
Notes: Wafer demand calculated from die count, rectangular wafer packing, die yield and assembly yield. Wafer manufacturing yield is already included upstream.
Uncertainty: No range defined.
Unit: wafer

Base Logic Die REEL datasetwafer

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: 28nm Planar HKMG wafer, 300mm, moderate scenario
Background dataset: Modelled by REEL; see the upstream dataset above.
Notes: Wafer demand calculated from die count, rectangular wafer packing, die yield and assembly yield. Wafer manufacturing yield is already included upstream.
Uncertainty: No range defined.
Unit: wafer

TSV Stacking REEL datasetpackage

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: HBM3 TSV Stacking and Assembly package, 16-Hi
Background dataset: Modelled by REEL; see the upstream dataset above.
Notes: Adjusted for packaging yield.
Uncertainty: No range defined.
Unit: package

Cu pillar + SnAg solder cap Materialkg · -45.5% / +118%

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

The sources for this row are listed below.
Source citations (dataset-level): SanDisk HBF Fact Sheet (2025) | url: https://documents.sandisk.com/content/dam/asset-library/en_us/assets/public/sandisk/collateral/company/Sandisk-HBF-Fact-Sheet.pdf
SanDisk press release 2026-02-25 - HBF global standardization with SK hynix | url: https://www.sandisk.com/company/newsroom/press-releases/2026/2026-02-25-sandisk-and-sk-hynix-begin-global-standardization-of-next-generation-memory-solution-high-bandwidth-flash-hbf
SK Hynix Newsroom (Feb 2026) - HBF standardization | url: https://news.skhynix.com/sk-hynix-and-sandisk-begin-global-standardization-ofnext-generation-memory-hbf/
TrendForce (Feb 2026) - SK hynix & SanDisk HBF kickoff | url: https://www.trendforce.com/news/2026/02/26/news-sk-hynix-sandisk-kick-off-global-standardization-of-hbf-market-set-to-surge-by-2030/
Tom's Hardware - SanDisk and SK hynix join forces to standardize HBF | url: https://www.tomshardware.com/tech-industry/sandisk-and-sk-hynix-join-forces-to-standardize-high-bandwidth-flash-memory-a-nand-based-alternative-to-hbm-for-ai-gpus-move-could-enable-8-16x-higher-capacity-compared-to-dram
Blocks & Files (Nov 2025) - HBF capacity and complexity | url: https://blocksandfiles.com/2025/11/27/stacked-layers-of-stacked-layers-hbf-capacity-and-complexity/
Vik's Newsletter - High Bandwidth Flash deep dive | url: https://www.viksnewsletter.com/p/high-bandwidth-flash-nands-bid-for-ai
ISSCC 2025 BiCS9 - Kioxia/SanDisk press release on next-gen 3D flash | url: https://www.sandisk.com/company/newsroom/press-releases/2025/kioxia-and-sandisk-unveil-next-generation-3d-flash-memory-technology
Kioxia CBA technology article - high-precision wafer bonding | url: https://www.kioxia.com/en-jp/business/topics/bics-cba-202407.html
EE Times - KIOXIA BiCS FLASH 3D high-density wafer bonding | url: https://www.eetimes.com/high-density-3d-flash-memory-using-high-precision-wafer-bonding-brings-new-value-to-storage/
SemiAnalysis - Hybrid Bonding Process Flow (Advanced Packaging Part 5) | url: https://semianalysis.com/2024/02/09/hybrid-bonding-process-flow-advanced/
Applied Materials - HBM materials innovation perspective | url: https://www.appliedmaterials.com/us/en/newsroom/perspectives/hbm--materials-innovation-propels-high-bandwidth-memory-into-the.html
Background data: composite
Background dataset: Modelled as a composite of its constituent materials.
Uncertainty: -45.5% / +118% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: kg

Molding Compound Materialkg

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

The sources for this row are listed below.
Source citations (dataset-level): SanDisk HBF Fact Sheet (2025) | url: https://documents.sandisk.com/content/dam/asset-library/en_us/assets/public/sandisk/collateral/company/Sandisk-HBF-Fact-Sheet.pdf
SanDisk press release 2026-02-25 - HBF global standardization with SK hynix | url: https://www.sandisk.com/company/newsroom/press-releases/2026/2026-02-25-sandisk-and-sk-hynix-begin-global-standardization-of-next-generation-memory-solution-high-bandwidth-flash-hbf
SK Hynix Newsroom (Feb 2026) - HBF standardization | url: https://news.skhynix.com/sk-hynix-and-sandisk-begin-global-standardization-ofnext-generation-memory-hbf/
TrendForce (Feb 2026) - SK hynix & SanDisk HBF kickoff | url: https://www.trendforce.com/news/2026/02/26/news-sk-hynix-sandisk-kick-off-global-standardization-of-hbf-market-set-to-surge-by-2030/
Tom's Hardware - SanDisk and SK hynix join forces to standardize HBF | url: https://www.tomshardware.com/tech-industry/sandisk-and-sk-hynix-join-forces-to-standardize-high-bandwidth-flash-memory-a-nand-based-alternative-to-hbm-for-ai-gpus-move-could-enable-8-16x-higher-capacity-compared-to-dram
Blocks & Files (Nov 2025) - HBF capacity and complexity | url: https://blocksandfiles.com/2025/11/27/stacked-layers-of-stacked-layers-hbf-capacity-and-complexity/
Vik's Newsletter - High Bandwidth Flash deep dive | url: https://www.viksnewsletter.com/p/high-bandwidth-flash-nands-bid-for-ai
ISSCC 2025 BiCS9 - Kioxia/SanDisk press release on next-gen 3D flash | url: https://www.sandisk.com/company/newsroom/press-releases/2025/kioxia-and-sandisk-unveil-next-generation-3d-flash-memory-technology
Kioxia CBA technology article - high-precision wafer bonding | url: https://www.kioxia.com/en-jp/business/topics/bics-cba-202407.html
EE Times - KIOXIA BiCS FLASH 3D high-density wafer bonding | url: https://www.eetimes.com/high-density-3d-flash-memory-using-high-precision-wafer-bonding-brings-new-value-to-storage/
SemiAnalysis - Hybrid Bonding Process Flow (Advanced Packaging Part 5) | url: https://semianalysis.com/2024/02/09/hybrid-bonding-process-flow-advanced/
Applied Materials - HBM materials innovation perspective | url: https://www.appliedmaterials.com/us/en/newsroom/perspectives/hbm--materials-innovation-propels-high-bandwidth-memory-into-the.html
Background data: ecoinvent 3.12
Background dataset: epoxy resin insulator, SiO2
Uncertainty: No range defined.
Unit: kg

Wafer transport, KR fab to packaging site - Road Freight transporttkm · -100% / +172%

Derivation basis: Specified for this manufacturing operation and scaled to the dataset's functional unit.

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

Additional Investment in Onyang Campus... Expanding Back-End Processing Too (Seoul Economic Daily)

The Elec report, 2026-07: Samsung back-end investment focused on high-bandwidth memory

DigiTimes report, 2024-11-13: Samsung Cheonan and Onyang back-end hubs
Background data: ecoinvent 3.12
Background dataset: transport, freight, lorry, unspecified
Notes: Freight for the part-finished product moving between REEL-modelled sites: the wafer fraction this dataset consumes, travelling from memory fab to domestic back end. Shipped mass is that wafer fraction times the wafer mass implied by its declared diameter, times a shipping-packaging factor covering the returnable front-opening shipping box and its secondary carton; the packaging production burden is excluded as returnable, while its mass is carried because freight scales with what is actually shipped. Road freight is allocated on actual shipped mass, and the mapped road market already includes carrier empty returns; the central therefore has no return uplift. The authored band uses the route-class distance envelope, and its upper endpoint also adds the separate reusable-carrier return service.
Uncertainty: -100% / +172% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: tkm — tonne-kilometres, a transport effort rather than a mass

Wafer transport, TW fab to packaging site - Air (short haul) Freight transporttkm · -47.4% / +80%

Derivation basis: Specified for this manufacturing operation and scaled to the dataset's functional unit.

No source is attached to this row.
Source citations: Not stated
Background data: ecoinvent 3.12
Background dataset: transport, freight, aircraft, dedicated freight, short haul
Notes: Freight for the part-finished product moving between REEL-modelled sites: the wafer fraction this dataset consumes, travelling from foundry logic die to memory stacking site, cross-border. Shipped mass is that wafer fraction times the wafer mass implied by its declared diameter, times a shipping-packaging factor covering the returnable front-opening shipping box and its secondary carton; the packaging production burden is excluded as returnable, while its mass is carried because freight scales with what is actually shipped. Air freight is allocated on chargeable weight rather than actual shipped mass. The authored band holds the fixed route distance: its lower endpoint uses actual shipped mass, its central uses chargeable-weight allocation, and its upper endpoint adds the separate reusable-carrier return service, not aircraft backhaul.
Uncertainty: -47.4% / +80% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: tkm — tonne-kilometres, a transport effort rather than a mass

Electricity, South Korea (KR) ElectricitykWh · -24% / +32.2%

Derivation basis: Calculated from equipment energy across all manufacturing operations. This model includes no facility support, so the total is the manufacturing operations alone.

The sources for this row are listed below.
Source citations (dataset-level): SanDisk HBF Fact Sheet (2025) | url: https://documents.sandisk.com/content/dam/asset-library/en_us/assets/public/sandisk/collateral/company/Sandisk-HBF-Fact-Sheet.pdf
SanDisk press release 2026-02-25 - HBF global standardization with SK hynix | url: https://www.sandisk.com/company/newsroom/press-releases/2026/2026-02-25-sandisk-and-sk-hynix-begin-global-standardization-of-next-generation-memory-solution-high-bandwidth-flash-hbf
SK Hynix Newsroom (Feb 2026) - HBF standardization | url: https://news.skhynix.com/sk-hynix-and-sandisk-begin-global-standardization-ofnext-generation-memory-hbf/
TrendForce (Feb 2026) - SK hynix & SanDisk HBF kickoff | url: https://www.trendforce.com/news/2026/02/26/news-sk-hynix-sandisk-kick-off-global-standardization-of-hbf-market-set-to-surge-by-2030/
Tom's Hardware - SanDisk and SK hynix join forces to standardize HBF | url: https://www.tomshardware.com/tech-industry/sandisk-and-sk-hynix-join-forces-to-standardize-high-bandwidth-flash-memory-a-nand-based-alternative-to-hbm-for-ai-gpus-move-could-enable-8-16x-higher-capacity-compared-to-dram
Blocks & Files (Nov 2025) - HBF capacity and complexity | url: https://blocksandfiles.com/2025/11/27/stacked-layers-of-stacked-layers-hbf-capacity-and-complexity/
Vik's Newsletter - High Bandwidth Flash deep dive | url: https://www.viksnewsletter.com/p/high-bandwidth-flash-nands-bid-for-ai
ISSCC 2025 BiCS9 - Kioxia/SanDisk press release on next-gen 3D flash | url: https://www.sandisk.com/company/newsroom/press-releases/2025/kioxia-and-sandisk-unveil-next-generation-3d-flash-memory-technology
Kioxia CBA technology article - high-precision wafer bonding | url: https://www.kioxia.com/en-jp/business/topics/bics-cba-202407.html
EE Times - KIOXIA BiCS FLASH 3D high-density wafer bonding | url: https://www.eetimes.com/high-density-3d-flash-memory-using-high-precision-wafer-bonding-brings-new-value-to-storage/
SemiAnalysis - Hybrid Bonding Process Flow (Advanced Packaging Part 5) | url: https://semianalysis.com/2024/02/09/hybrid-bonding-process-flow-advanced/
Applied Materials - HBM materials innovation perspective | url: https://www.appliedmaterials.com/us/en/newsroom/perspectives/hbm--materials-innovation-propels-high-bandwidth-memory-into-the.html
Background data: ecoinvent 3.12
Background dataset: electricity, high voltage
Notes: Energy demand from cba wafer bonding and known-good-die testing, adjusted for assembly yield.
Uncertainty: -24% / +32.2% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: kWh

Process water WaterL · -23.9% / +25.4%

Derivation basis: Calculated from process-water and ultrapure-water demand across all manufacturing operations. This model includes no facility support, so the demand is the manufacturing operations alone. 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
Background data: ecoinvent 3.12
Background dataset: tap water
Notes: Aggregated water demand of this dataset's production stages.
Uncertainty: -23.9% / +25.4% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: L

N₂ Process gasg

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: nitrogen, liquid
Uncertainty: No range defined.
Unit: g

Compressed air Process gasg

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

The sources for this row are listed below.
Source citations (specific to this process): CAE Online: Teradyne Catalyst Specifications
EE Journal: "Advantest Unveils New Ultra-High-Current Power Supply" (2024)
4Semi: TEL Precio Wafer Prober Specifications
FormFactor Summit 11000/12000 Facility Planning Guide
3D InCites: "ERS Electronic Introduces High Power Dissipation Thermal Chuck" (2023)
Abachy: "How Much Energy and Water Are Required for Wafer Fabrication" (2025)
Background data: ecoinvent 3.12
Background dataset: compressed air, 700 kPa gauge
Uncertainty: No range defined.
Unit: g

Outputs and waste

Spent CMP slurry Solid wasteg

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:

SemiAnalysis and IEEE hybrid bonding process flow

A-STAR Singapore hybrid bonding research

BusinessWorld and TweakTown HBM4 specifications

All About Circuits and Kynix HBM4 specifications
Background data: ecoinvent 3.12 treatment route
Background dataset: treatment of hazardous waste, underground deposit
Uncertainty: No range defined.
Unit: g

Failed packages (assembly reject) Solid wasteg · -6% / +12.5%

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:

SanDisk HBF Fact Sheet (2025) | url: https://documents.sandisk.com/content/dam/asset-library/en_us/assets/public/sandisk/collateral/company/Sandisk-HBF-Fact-Sheet.pdf

SanDisk press release 2026-02-25 - HBF global standardization with SK hynix | url: https://www.sandisk.com/company/newsroom/press-releases/2026/2026-02-25-sandisk-and-sk-hynix-begin-global-standardization-of-next-generation-memory-solution-high-bandwidth-flash-hbf

SK Hynix Newsroom (Feb 2026) - HBF standardization | url: https://news.skhynix.com/sk-hynix-and-sandisk-begin-global-standardization-ofnext-generation-memory-hbf/

TrendForce (Feb 2026) - SK hynix & SanDisk HBF kickoff | url: https://www.trendforce.com/news/2026/02/26/news-sk-hynix-sandisk-kick-off-global-standardization-of-hbf-market-set-to-surge-by-2030/

Tom's Hardware - SanDisk and SK hynix join forces to standardize HBF | url: https://www.tomshardware.com/tech-industry/sandisk-and-sk-hynix-join-forces-to-standardize-high-bandwidth-flash-memory-a-nand-based-alternative-to-hbm-for-ai-gpus-move-could-enable-8-16x-higher-capacity-compared-to-dram

Blocks & Files (Nov 2025) - HBF capacity and complexity | url: https://blocksandfiles.com/2025/11/27/stacked-layers-of-stacked-layers-hbf-capacity-and-complexity/

Vik's Newsletter - High Bandwidth Flash deep dive | url: https://www.viksnewsletter.com/p/high-bandwidth-flash-nands-bid-for-ai

ISSCC 2025 BiCS9 - Kioxia/SanDisk press release on next-gen 3D flash | url: https://www.sandisk.com/company/newsroom/press-releases/2025/kioxia-and-sandisk-unveil-next-generation-3d-flash-memory-technology

Kioxia CBA technology article - high-precision wafer bonding | url: https://www.kioxia.com/en-jp/business/topics/bics-cba-202407.html

EE Times - KIOXIA BiCS FLASH 3D high-density wafer bonding | url: https://www.eetimes.com/high-density-3d-flash-memory-using-high-precision-wafer-bonding-brings-new-value-to-storage/

SemiAnalysis - Hybrid Bonding Process Flow (Advanced Packaging Part 5) | url: https://semianalysis.com/2024/02/09/hybrid-bonding-process-flow-advanced/

Applied Materials - HBM materials innovation perspective | url: https://www.appliedmaterials.com/us/en/newsroom/perspectives/hbm--materials-innovation-propels-high-bandwidth-memory-into-the.html

AIP Publishing - Tutorial on forming through-silicon vias (J. Vac. Sci. Technol. A 38, 031202, 2020) | url: https://pubs.aip.org/avs/jva/article/38/3/031202/1023659/Tutorial-on-forming-through-silicon-vias

Kioxia press release Aug 2025 - 5TB HBF prototype (NEDO, PCIe 6.0) | url: https://americas.kioxia.com/en-us/business/news/2025/20250820-1.html

Tom's Hardware - Kioxia 5TB 64GB/s flash module HBF prototype | url: https://www.tomshardware.com/pc-components/gpus/kioxias-new-5tb-64-gb-s-flash-module-puts-nand-toward-the-memory-bus-for-ai-gpus-hbf-prototype-adopts-familiar-ssd-form-factor

Digitimes (Oct 2025) - Samsung joins HBF development | url: https://www.digitimes.com/news/a20251007PD233/samsung-market-development-nand-flash-nand.html

TrendForce (Nov 2025) - SK hynix, Samsung, SanDisk bet on HBF | url: https://www.trendforce.com/news/2025/11/11/news-sk-hynix-samsung-and-sandisk-bet-on-hbf-the-next-battleground-in-memory-sector/

KED Global - SK Hynix H3 hybrid HBM/HBF concept | url: https://www.kedglobal.com/korean-chipmakers/newsView/ked202602110001

TrendForce (Feb 2026) - SK hynix HBF AI chip architecture, 2.69x perf/watt | url: https://www.trendforce.com/news/2026/02/12/news-sk-hynix-unveils-ai-chip-architecture-with-hbf-reportedly-boosts-performance-per-watt-by-up-to-2-69x/

IEEE conference paper on NAND thinning (2019)
Background data: ecoinvent 3.12 treatment route
Background dataset: treatment of waste electric and electronic equipment, shredding
Uncertainty: -6% / +12.5% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: g

Emissions to air

No emissions to air are recorded at this level.

Emissions to water

No emissions to water are recorded at this level.

Flows not quantified

3 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.

Not modelled (2)

CMP slurry (colloidal silica) Process chemicalg

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: not modelled
Background dataset: Not applicable: this flow is not quantified in the inventory.
Reason: The quantified material is retained, but its authored name does not identify a sufficiently specific background dataset or defensible proxy; background modeling remains an explicit gap.
Uncertainty: No range defined.
Unit: g

SC-1 solution (NH4OH/H₂O₂/H₂O) Process chemicalg

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: not modelled
Background dataset: Not applicable: this flow is not quantified in the inventory.
Reason: The quantified material is retained, but its authored name does not identify a sufficiently specific background dataset or defensible proxy; background modeling remains an explicit gap.
Uncertainty: No range defined.
Unit: g

Not quantified - no background dataset available (1)

NCF Adhesive Materialkg · ±4.3%

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

The sources for this row are listed below.
Source citations (dataset-level): SanDisk HBF Fact Sheet (2025) | url: https://documents.sandisk.com/content/dam/asset-library/en_us/assets/public/sandisk/collateral/company/Sandisk-HBF-Fact-Sheet.pdf
SanDisk press release 2026-02-25 - HBF global standardization with SK hynix | url: https://www.sandisk.com/company/newsroom/press-releases/2026/2026-02-25-sandisk-and-sk-hynix-begin-global-standardization-of-next-generation-memory-solution-high-bandwidth-flash-hbf
SK Hynix Newsroom (Feb 2026) - HBF standardization | url: https://news.skhynix.com/sk-hynix-and-sandisk-begin-global-standardization-ofnext-generation-memory-hbf/
TrendForce (Feb 2026) - SK hynix & SanDisk HBF kickoff | url: https://www.trendforce.com/news/2026/02/26/news-sk-hynix-sandisk-kick-off-global-standardization-of-hbf-market-set-to-surge-by-2030/
Tom's Hardware - SanDisk and SK hynix join forces to standardize HBF | url: https://www.tomshardware.com/tech-industry/sandisk-and-sk-hynix-join-forces-to-standardize-high-bandwidth-flash-memory-a-nand-based-alternative-to-hbm-for-ai-gpus-move-could-enable-8-16x-higher-capacity-compared-to-dram
Blocks & Files (Nov 2025) - HBF capacity and complexity | url: https://blocksandfiles.com/2025/11/27/stacked-layers-of-stacked-layers-hbf-capacity-and-complexity/
Vik's Newsletter - High Bandwidth Flash deep dive | url: https://www.viksnewsletter.com/p/high-bandwidth-flash-nands-bid-for-ai
ISSCC 2025 BiCS9 - Kioxia/SanDisk press release on next-gen 3D flash | url: https://www.sandisk.com/company/newsroom/press-releases/2025/kioxia-and-sandisk-unveil-next-generation-3d-flash-memory-technology
Kioxia CBA technology article - high-precision wafer bonding | url: https://www.kioxia.com/en-jp/business/topics/bics-cba-202407.html
EE Times - KIOXIA BiCS FLASH 3D high-density wafer bonding | url: https://www.eetimes.com/high-density-3d-flash-memory-using-high-precision-wafer-bonding-brings-new-value-to-storage/
SemiAnalysis - Hybrid Bonding Process Flow (Advanced Packaging Part 5) | url: https://semianalysis.com/2024/02/09/hybrid-bonding-process-flow-advanced/
Applied Materials - HBM materials innovation perspective | url: https://www.appliedmaterials.com/us/en/newsroom/perspectives/hbm--materials-innovation-propels-high-bandwidth-memory-into-the.html
Background data: no background dataset
Background dataset: Not applicable: this flow is not quantified in the inventory.
Reason: A specialty thermosetting epoxy bonding film used in wafer-level stacking. No production dataset for it exists in the background database used for linkage; plain epoxy resin is the closest constituent but leaves out the cure system that defines this film, so it is not substituted. The quantity is recorded here and its upstream production is left unlinked.
Uncertainty: ±4.3% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit: kg

Limitations and unquantified flows (7)

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

PROSPECTIVE DATASET - Pre-commercial engineering estimate for High Bandwidth Flash Gen 1 at technology readiness level 4-5, with samples expected in H2 2026.
The specification is a pre-1.0 draft: width and length are approximate, the bump map remains preliminary, and dimension minimum/maximum values await v1.0. Re-evaluate the footprint and Poisson die-yield basis at HBF specification v1.0 or the first vendor product documentation.
Use the shipped asymmetric uncertainty range until production data are available.

General

The mould-compound mass booked on this stack is an authored estimate that the stack's own packaging inventory contradicts. Three separate figures for the same encapsulant are in play across the files that describe this stack: the mass booked here as purchased demand, the mass the stacking inventory derives from the package envelope and the die stack inside it when it prices a scrapped stack, and the encapsulant basis the mould-waste allocation uses to size the flash it trims. They do not agree, and the flash waste this dataset ships is sized on the third of them. Reconciling them needs a package height and a base-die thickness that no file on this path declares consistently across stack heights - above the reference stack height the declared die and gap thicknesses no longer fit inside the declared envelope - and no public dimension for the taller rungs was found. The mass is therefore left as authored and disclosed here rather than re-derived on an assumed envelope.
The post-mould grinding slurry leaves this stack as waste with no matching input. It is a consumable of the moulding cycle, and the inventory that books its disposal does not book its purchase, so the mass it carries out is not balanced by a mass carried in. The single-use release film beside it, which had the same gap, is now booked as an input at the mass it leaves as waste. The slurry is not, because that same inventory records an unresolved question about whether the raw slurry and the treatment residues already booked as outputs in this dataset describe the same material twice; booking the raw slurry as an input before that is settled would compound it rather than close it.
The die capacity on this dataset and the die area beside it imply a bit density an order of magnitude below the one the flash wafer this dataset consumes declares for its own die. One of the two is wrong: either this die holds far more than the capacity booked here, or its footprint is far smaller than the area booked here. The area booked here is not a measured die: it is the outline of the finished package, taken from the architecture specification and used as a stand-in for all three dies because no die dimension is published for any of them. Those outline dimensions are approximate in that specification, and a die is smaller than the package around it, so the stand-in may overstate the die area. The wafer demand allocated from it is conditional on that assumed geometry and on the assumed die yields beside it rather than bounded by them. The capacity of this part is an open question on this dataset already, and the area drives its wafer demand, so the disagreement is stated rather than resolved by picking one side or by assuming what share of the envelope a die occupies.
Two of the direct operations behind this stack carry quantities that no public measurement supports. The nitrogen booked for the bonding anneal and for the plasma activation step before it, and the prepared cleaning solution booked for particle removal, are declared estimates inherited from the bonding process description: the searches recorded against them found no published figure reporting those volumes. They ship as authored, with their derivation stated, rather than dropped or replaced by an invented value.

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