Pattern
Deposit a noble-metal catalyst such as Au, Pt, or Ag in the desired geometry.
A semiconductor nanomanufacturing platform
Anisotropic etching.
Without plasma damage.
Metal-assisted chemical etching (MacEtch) uses a patterned catalyst to localize redox chemistry at a semiconductor interface—translating a metal pattern into deep, anisotropic micro- and nanostructures without plasma-induced lattice damage.
9+semiconductor systems
6process modes
15MacEtch patent families
Pattern-defined semiconductor architectures
The catalyst geometry determines whether MacEtch produces pillars, holes, or sheets while preserving high anisotropy.
Mechanism
Chemistry with a built-in address
The catalyst does more than mask the surface. It defines where charge transfer—and therefore material removal—can proceed.
Generate carriers
An oxidant is catalytically reduced, generating holes that oxidize the semiconductor locally.
Dissolve locally
The oxidized material is dissolved by the surrounding chemistry at the catalyst–semiconductor interface.
Translate in depth
The catalyst descends as etching proceeds, transferring its pattern anisotropically into the crystal.
catalyst pattern+localized redox+mass transport=3D structure
Platform map
One principle, multiple operating modes
Select a process mode to see what changes and why it matters.
FOUNDATIONAL MODE
Forward MacEtch
A patterned catalyst drives localized dissolution directly beneath the metal, enabling high-aspect-ratio pillars, vias, sheets, and arbitrary patterns.
- Control lever
- Catalyst geometry + solution chemistry
- Best known for
- Direct anisotropic pattern transfer
- Representative materials
- Si, GaAs, InGaAs
Material reach
Select a material to highlight its family.
Forward MacEtch advantage
Ultra-high Aspect Ratio
The catalyst descends into the semiconductor with the advancing interface. If intimate metal–semiconductor contact and the desired reaction pathway are maintained, etching can continue.
CATALYSTS
increasing depth
Intimate catalyst–semiconductor interfaces advance downward together
Idealized limit
In principle: unbounded
Unlike a conventional masking process in which selectivity consumes a stationary mask, the MacEtch catalyst travels with the reaction front and is not consumed by the net reaction. There is therefore no intrinsic geometric aspect-ratio ceiling in the idealized mechanism.
Practical limits
- Catalyst detourLoss of vertical trajectory distorts or terminates pattern transfer.
- Interface lossEtching slows if intimate metal–semiconductor contact is disrupted.
- Mass transportReactant delivery and product removal become harder with depth.
- Parasitic etchingEven a small isotropic chemical rate accumulates during long etches.
Damage-free advantage
The sidewall can look smooth—and still be damaged.
Damage-free processing is intrinsic to the plasma-free MacEtch platform—including forward, inverse, photo-enhanced, and other modes. It is especially consequential for wide- and ultrawide-bandgap semiconductors, where photo-enhanced hν-MacEtch supplies the carriers needed for controlled etching.
hν-MacEtch
photons · hν ≥ Eg
oxidantOH⁻OH⁻
Pt-covered · cathode
e⁻ →e⁻ →← e⁻← e⁻
h⁺h⁺h⁺h⁺
h⁺h⁺h⁺h⁺
wide-bandgap semiconductorexposed surface etches ↓
Pt-protected mesa
exposed surface etches ↓
① light generates many e⁻ / h⁺② e⁻ migrate to Pt③ h⁺ remain at exposed surfaces → etch
Above-bandgap light generates electron–hole pairs. Electrons migrate to the Pt-covered cathodic region for oxidant reduction, while holes remain at the exposed semiconductor surfaces and drive oxidation and dissolution. The material not covered by Pt is therefore removed.
No energetic ion bombardmentOptical quality retained
VS
Reactive-ion etching
reactive-ion plasma
+++++++
photoresist mask
semiconductor
advancing etch front
Directional ions remove semiconductor through openings in a photoresist mask. Collision cascades generate randomly distributed vacancies and interstitials that spread deeper below the advancing etched surface and sidewalls.
Published GaN comparison>60% PL loss
The controlled comparison
Similar etch depth and morphology. Very different photoluminescence.
The RIE condition was deliberately selected as a gentle recipe while achieving the same etch depth. Even so, the RIE-processed GaN showed a greater than 60% decrease in PL peak intensity relative to MacEtch—revealing a damage burden that morphology alone does not show.
Advanced Optical Materials (2024) ↗01
Optical performance
Preserve radiative efficiency near etched surfaces.
02
Electronic interfaces
Reduce damage-related states and hysteresis.
03
Dimensional scaling
Limit the growing sidewall penalty as devices shrink.
Demonstrated applications
From semiconductor structures to functioning devices
A curated path through peer-reviewed demonstrations—not an exhaustive bibliography.
2023Manufacturing
Programmable vapor-phase MacEtch
Versatile, high-aspect-ratio silicon nanomanufacturing using a vapor-phase process.
Applied Physics Reviews ↗ 2024PhotonicsPlasma-damage-free microLED scaling
Photo-enhanced MacEtch preserves optical quality while defining small emitters.
Advanced Optical Materials ↗ 2016ElectronicsUltra-high-aspect-ratio InP FinFETs
Inverse MacEtch produced smooth InP fins for junctionless transistors with near-ideal subthreshold behavior.
IEEE Electron Device Letters ↗ 2022ElectronicsUltra-low-hysteresis β-Ga₂O₃ FinFETs
Plasma-free MacEtch enabled high-aspect-ratio β-Ga₂O₃ fins with low hysteresis and strong electrostatic control.
Applied Physics Letters ↗ 2017ManufacturingScaling closely packed silicon vias
Kinetics of carrier generation and mass transport explain aspect-ratio scaling.
Advanced Functional Materials ↗ 2019ElectronicsLow-interface-charge Ga₂O₃ fins
Inverse MacEtch yields high-aspect-ratio fin arrays with favorable interfaces.
ACS Nano ↗ 2013PhotonicsMagnetic-guided photonic crystals
A magnetic field guides catalyst motion to form photonic-crystal membrane reflectors.
Applied Physics Letters ↗ 2018PhotonicsSelf-passivated Ge photodiodes
Inverse MacEtch combined monolithic antireflection texturing with α-Ge self-passivation to enhance photodiode performance.
ACS Nano ↗ 2013PhotonicsGaAs pillar-array LEDs
MacEtch-defined GaAs pillar arrays were integrated into operating light-emitting diodes.
Journal of Applied Physics ↗ 2018PhotonicsEnhanced-responsivity Ga₂O₃ photodiodes
Room-temperature inverse MacEtch created nanoscale groove textures that increased photodiode responsivity.
Applied Physics Letters ↗ 2012PhotonicsSilicon micropillar-array solar cells
Periodic MacEtch-produced micropillars established design relationships for light harvesting in silicon photovoltaics.
IEEE Journal of Photovoltaics ↗2000Porous silicon
2011III–V high aspect ratio
2018Device integration
2021Wide-bandgap expansion
2024MicroLED scaling
Structure gallery
Different crystals. Different geometries. One platform.
Selected micro- and nanostructures from published MacEtch studies.
51-µm high-aspect-ratio structures
Translation
A protected platform, not a single recipe
The MacEtch patent portfolio spans foundational chemistry, materials expansion, catalyst control, vapor-phase processing, optical surfaces, monolithic microLED fabrication, and radiation-enabled systems.
Explore the MacEtch patent portfolio →01
Foundations
Porous silicon and porous III–V formation
02
Geometry
3D patterns and high-aspect-ratio arrays
03
Process control
Magnetic guidance, self-anchoring, vapor phase
04
Devices
Optoelectronics, microLEDs, and radiation-enabled systems
The broader opportunity
MacEtch is an anisotropic, plasma-free, damage-free, and versatile etching method.
It is positioned to potentially revolutionize the traditional RIE approach across diverse fields such as electronics, photonics, quantum, energy, and bio-sensing applications.