Overlay
How well one layer's pattern lands on the layer beneath it, in nanometers. Lithera predicts the residual per field and corrects the scanner before it reaches the limit.
Resources
The vocabulary of the fab, and what a pilot needs.
A glossary of the process and defect terms Waferira's agents work with, the standards and procedures the reasoning layer cites, and the inputs a fab brings to a pilot baseline. No white papers or calculators are published yet; this page is the reference we actually have.
What the reasoning layer cites
- SEMI standards, including the SECS/GEM family the tool integration speaks
- Your process recipes and integration specs
- Your excursion and OCAP procedures
- Your qualification and genealogy records
Retrieval is tenant-isolated and permission-aware, and every answer carries its citation.
Glossary
Twelve terms
The process and defect terms that appear throughout the site.
Critical dimension (CD)
The width of the smallest printed feature. Drift in CD or its uniformity across the wafer is a yield loss long before it is a failure.
Focus-exposure matrix
The process window of focus and dose inside which a layer prints to spec. Lithera watches drift against it and trims dose or focus.
Excursion
A departure of a tool or process from its qualified behaviour: uniformity, particles, overlay, dishing. Caught late, it scraps the lots that ran through it.
FDC
Fault detection and classification: the per-wafer tool-sensor signatures each chamber produces. The raw material for virtual metrology and prognostics.
Virtual metrology
Predicting a measurement from tool-sensor and FDC signatures instead of measuring it, so every wafer is scored and physical metrology goes where the uncertainty is.
Run-to-run and APC
Advanced process control that updates a recipe between lots or wafers from measured or predicted results. Waferira closes it across modules.
OCAP
Out-of-control action plan: the fab's procedure for an excursion. Every hold Waferira raises links to the OCAP it follows.
Killer and nuisance defects
A killer defect destroys the die; a nuisance defect does not. Scanira dispositions them so review effort goes to the ones that matter.
Reticle repeater
A defect at the same field position on many dies, pointing at the reticle rather than the process. Scanira flags it and the orchestrator holds for reticle inspection.
Dishing and erosion
CMP removing too much from wide features (dishing) or dense arrays (erosion). CMP-and-Implant holds removal rate and downforce inside the window.
Genealogy
The record of a lot: recipe moves, correctables, FDC signatures, virtual-metrology scores, defect map, approvals and release decision.
Pilot baseline
What a fab brings to the first meeting
The inputs for a baseline agreed in writing.
About the module
- Module type, tools and the layers it runs
- APC, inspection, metrology, FDC and MES systems installed, with interfaces
- How lots, recipes and excursions are recorded today
- Shift pattern and who approves recipe changes and holds
About the losses
- Yield by layer and the value of a yield point
- Excursions per quarter and lots scrapped or reworked
- Defect-review hours and nuisance rate
- Metrology sampling rate and unmeasured steps
- Cycle time and on-time delivery in the area
Reading
Where to go next
The pages that explain the mechanics.
Six layers, one loop
How the fab-edge runtime, orchestrator, agents, twin and training loop fit together.
How software is allowed to touch a tool
The write path, the audit record and the data governance.
Three labelled walk-throughs
What a pilot on inspection, litho or uniformity APC would do and measure.
Writing on fabs and autonomy
Rich data and reactive control, graduated autonomy, hit yield before the lot runs.
Typed tools, declared windows
The SDK and CLI design previews.
Per module, per fab, per group
Tiers, the comparison table and the arithmetic a fab runs.
Run timeline · scenario
One scenario run, step by step
Every Waferira run is an ordered, inspectable sequence. This is run_7b2e9c on Module M2 · 300 mm · metal-1 · lot L-48213. Scenario completes in 10 steps with one approval gate. Overlay and CD predicted inside spec, one reticle-repeater signature caught and held for review, dispatch re-optimised, lot released with full genealogy.
run_7b2e9c
Module M2 · 300 mm · metal-1 · lot L-48213
illustrative scenario
SUCCEEDED
-
01
ingest.lot
SUCCEEDED
0.7 s
Fab Orchestrator · Pulled lot L-48213 from fab MES: 25 wafers, 300 mm, metal-1 layer, route, reticle, overlay and CD spec and the standing cycle-time target. Locked the target envelope for the run.
-
02
twin.simulate
SUCCEEDED
38 s
Fab Twin · Simulated 64 candidate correctable, recipe and dispatch sets on the as-run fab twin and ranked them on predicted overlay residual, CD uniformity, excursion risk and cycle time.
-
03
litho.correctables
SUCCEEDED
1 m 20 s
Litho-and-Overlay · Per-field overlay correctables and a focus-dose trim written to scanner SCN-07 over SECS/GEM after the previous lot's residual trended toward the control limit. Predicted overlay residual back inside spec.
-
04
etch.uniformity
SUCCEEDED
58 s
Etch-and-Depo · Chamber B on etcher ETCH-12 showed an edge-fast uniformity drift in FDC. Pressure and RF trims written within the qualified recipe window; predicted CD uniformity recovered.
-
05
cmp.removal
SUCCEEDED
46 s
CMP-and-Implant · Downforce and platen-speed trim on CMP-03 against the virtual removal-rate estimate to hold post-CMP thickness and dishing inside the window.
-
06
inspect.classify
SUCCEEDED
continuous
Defect-and-Inspect · Inline optical, e-beam review and SEM imagery fused at the tool edge. 1,412 events classified, most dispositioned nuisance; one reticle-repeater signature on three dies flagged for review.
-
07
vm.score
SUCCEEDED
2.1 s
Metrology-and-Virtual · Virtual metrology scored every wafer at post-etch and post-CMP from tool-sensor and FDC signatures. Two wafers routed to physical metrology on predicted variance; the rest sampled at plan.
-
08
approve.human
APPROVAL
1 m 04 s
Fab Orchestrator · The reticle-repeater signature called for a reticle inspection hold and a recipe move outside the qualified window. Held for the module process engineer and approved at 03:14:27.
-
09
dispatch.route
SUCCEEDED
4.3 s
Yield-and-Dispatch · Dispatch re-optimised across 1,840 lots in WIP under reticle, chamber and qualification constraints. The lot routed to the qualified chamber with the shortest predicted queue; AMHS move issued to the stocker.
-
10
lot.release
SUCCEEDED
1 m 05 s
Quality-and-Conformance · Lot L-48213 moved on: genealogy written (recipe moves, correctables, FDC signatures, VM scores, defect map, approvals) and checked against the layer spec.
Autonomy
Four levels, set per agent and per tool
A fab does not go from manual APC to unattended control in one step. Waferira makes the level explicit, auditable and reversible at any time. The first release runs shadow mode, then assist mode, then graduated autonomy for low-risk APC, defect and metrology loops.
| Level | What the agent does | What the human does | Where it sits in a pilot |
|---|---|---|---|
| L1 · Advisory | Recommends recipe moves, dispositions and dispatch, with citations | Enters every change manually | Shadow mode, first on the design-partner cell |
| L2 · Supervised | Proposes a recipe write or hold; it executes on approval | Approves each move in the review console | Assist mode, where accuracy and ROI are proven |
| L3 · Bounded | Writes inside the qualified recipe window, tool-state checks and OCAP linkage | Approves holds, out-of-window moves and lot release | Graduated autonomy for low-risk APC, defect and metrology loops |
| L4 · Qualified loops | Runs a qualified loop without prompting, inside its envelope | Sets the envelope; reviews the shift record | Planned; reserved for loops the fab has qualified |
Accelerated computing
Physical AI, at the tool
Computational lithography, defect classification on e-beam and SEM imagery, per-wafer virtual metrology and a full-fab twin are among the most compute-intensive workloads in manufacturing. Waferira keeps IP-sensitive inference and feature storage at the fab edge and runs training, simulation and optimisation on GPUs the fab controls.
Inspection vision
Inline optical, e-beam and SEM imagery and sensor fusion on fab-edge GPUs. 10 to 50 inspection streams per pilot module and sub-200 ms priority defect triage are the design targets.
Virtual metrology and FDC
High-volume multivariate tool-sensor and FDC time-series scoring on every wafer, 1 to 5 seconds per lot-step in the design, with nightly retraining as recipes and chambers drift.
Training
Defect, virtual-metrology and process-response models retrained per process family; 500 to 2,000 GPU-hours per family per quarter is the design target. Dedicated capacity is planned.
Fab twin
As-run process and flow simulation, 1,000 to 10,000 candidate recipe, metrology and dispatch scenarios per fab per day in the design. OVX access is planned.
Synthetic rare events
Rare defect, particle, overlay-drift, CMP-dishing and film-uniformity variants generated and validated against real distributions before promotion. Planned.
Dispatch optimisation
Constrained WIP dispatch re-optimised every 1 to 5 minutes across reticle, chamber, route, tool-state and cycle-time constraints.
AMHS and handling
Local FOUP and robot perception and exception detection at the fab edge. Jetson Thor is planned for higher sensor density.
Process reasoning
Tenant-isolated process Q&A and OCAP reasoning over recipes, SEMI procedures and audit logs, with citations enforced on every answer.
FAQ
Straight answers
The questions fab directors and process engineers ask in the first meeting.
Yes, over SECS/GEM, but only inside the qualified recipe window for that tool, with per-parameter limits and tool-state checks, and only at the autonomy level your fab has set. Level 1 is advisory: Waferira recommends and an engineer enters everything. Design partners start there, in shadow mode.
The tool stays on its own controller and its last qualified recipe. Waferira is a supervisory layer on top of the APC, inspection, metrology and MES systems you already run, never a replacement for them, so an outage leaves the module running the way it runs today.
No. Inference and feature storage stay at the fab edge, recipes, device designs, defect libraries and process memory are isolated per tenant, and an on-prem control plane is available for IP-sensitive fabs. Any cross-fab learning is planned, contract-gated and privacy-preserving, and none of it moves recipes or designs.
Advisory recommendations start from the existing APC, metrology and ADC data on the wedge module. Defect classification, virtual metrology and excursion prediction improve as labelled events and lot outcomes accumulate per process family. Rare excursions are augmented synthetically only after validation against real distributions.
You are, the same as with any APC strategy, which is why every write is policy-checked, bounded to the qualified window, logged and reversible, and why holds, out-of-window moves and lot release wait for a named approver with the OCAP linked.
A paid pilot on one process module or tool fleet, scoped to one wedge workflow with a baseline agreed in writing. Shadow mode first, observing and measuring the baseline. Then assist mode, where the agent recommends and your engineer approves and accuracy and ROI are measured. Then bounded autonomy for low-risk APC, defect or metrology loops if the fab is satisfied.
Get started
Bring the inputs, we bring the baseline
Start with one process module or tool fleet and one measurable baseline. A paid, IP-isolated pilot on defect classification, virtual-metrology-driven overlay and CD control or uniformity APC shows the number before you commit further.