TRIton®
Automated endpoint detection for plasma etching with multi‑wavelength in‑situ reflectometry.
As device architectures become thinner and more complex, time-based etching is no longer reliable. Etch rate can drift within a run and across wafers due to chamber conditions, wafer properties, and process history. TRIton® is LayTec’s in‑situ reflectometry solution that brings real-time etch depth control and fully automated endpoint detection (EPD) to plasma etching processes.
Key takeaway:
TRIton® measures the reflectance transient at three optimized wavelengths during etching and uses this data to track etch progress, detect interfaces, calculate remaining thickness, and stop the process at the right moment – even when etch rate varies.
What is TRIton®?
TRIton® is an in‑situ optical metrology system for dry etching (e.g., ICP‑RIE, RIE, and ALE) designed to provide robust endpoint detection down to nanometer-level precision on advanced semiconductor layer stacks. It is especially useful when you must stop:
within a layer (residual thickness target),
at a thin-film interface (layer-to-layer transition),
or after a defined etch depth (absolute depth target).
For setup and operation, TRIton® supports camera-based spot positioning (useful for patterned wafers and repeatable placement on the correct feature).
Why multi‑wavelength reflectometry (and why single-wavelength is often not enough)
Many commercial endpoint systems rely on a single wavelength. In complex stacks, this creates a trade‑off:
Long wavelengths penetrate deeper and can show Fabry‑Pérot oscillations (FPOs) useful for depth tracking – but they may miss thin interfaces.
Short wavelengths can be highly sensitive to interfaces – but may be too strongly absorbed for reliable depth tracking across thicker regions.
TRIton® solves this by measuring three wavelengths simultaneously, selected based on the optical properties of your material system (wavelength selection is configurable roughly across the UV-NIR range). This enables etch rate extraction and interface detection at the same time, without compromising one for the other.
Examples of wavelength sets used in published use cases include:
GaN/AlGaN: near‑UV + UV combinations to combine FPO tracking and sensitive interface detection
GaAs/AlGaAs: visible + NIR combination for rate + interface identification in thick stacks
InP heterostructures: shorter wavelengths for interface sensitivity plus a longer wavelength for depth control.
Monitoring of etch processes
Endpoint detection for nitrides, arsenides, and phosphides
Inductively coupled plasma (ICP) etching, reactive ion etching (RIE) & atomic layer etch processes (ALE)
GaN power devices (HFET recess etch)
InP-based lasers (heterostructures & MQW proximity)
GaAs laser diodes
and many other materials
Within layer EPD for various materials and process classes
Automatic and reproducible endpoint detection for plasma etching
Low latency real time endpoint control
Down to sub-nm endpoint resolution
Camera-based point and click measurement spot positioning
UV to NIR measurement wavelength selection
Multiple measurement zones
Layer interface detection
Etch depth control
Remaining layer thickness control
Immune to etch-rate variation
Graphical endpoint recipe development
Endpoint interface for automated etch stop
Remote control interface for full integration into etcher
Features
What TRIton® can control in real time
Depending on your stack, etch chemistry, and recipe design, TRIton® supports real-time monitoring and control of:
Etch depth progress (via reflectance features and/or FPO analysis)
Etch rate and etch rate drift during the run (enabling adaptive control vs fixed etch time)
Interface detection (via slope/contrast changes at sensitive wavelengths)
Remaining thickness targeting for within-layer stops (critical for recess and gate structures)
Optional: system health / chamber conditioning insight by tracking run-to-run etch behavior and correlating optical/plasma signals
EtchNet: real-time endpoint recipes, automation, and traceability
TRIton® ships with EtchNet, LayTec’s standard software for etch monitoring and endpoint control.
With EtchNet, teams typically:
Develop an endpoint recipe based on reference traces (from previous runs, etch-through experiments, or simulations),
Run the recipe during live etching while monitoring the three reflectance traces,
Trigger start/stop signals for etch steps when the endpoint conditions are met,
Store run data and recipe versions for traceability, audits, and statistical process control.
This makes endpointing more robust than relying on fixed etch time – especially when etch rate varies with chamber state, wafer loading, or tool drift.
SimulyzR: reflectance simulation and “digital twin” workflow for faster recipe development
For advanced stacks, recipe development often requires multiple iterations. SimulyzR complements EtchNet by enabling offline reflectance simulation and fitting:
Import, build or approximate the wafer stack model,
Predict reflectance transients for multiple wavelengths,
Import TRIton® data for analysis
Extract process and/or material parameters like etch rate, optical constants and many more by advances Fit algorithms
Export reference data back into EtchNet to accelerate endpoint recipe creation and refinement.
In practice, the SimulyzR → EtchNet workflow reduces the need for repeated etch-through trials and shortens time to stable production recipes.
TRIton® in the LayTec Connected Metrology® ecosystem (“from epi to etch”)
TRIton® becomes even more powerful when paired with upstream and downstream LayTec metrology:
Use EpiCurve® TT / EpiTT during epitaxy to capture accurate growth thickness/composition data,
Use EpiX® for ex‑situ 2D wafer mapping (uniformity, PL/reflectance),
Use TRIton® in plasma etch for in‑situ thickness tracking and endpointing.
This “from epi to etch” approach supports tighter specs and better die-level understanding in advanced front-end flows.
Contact
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