Silicon Wet Etch Services at a U.S.-Based MEMS Foundry
Rogue Valley Microdevices provides precision wet etch services for MEMS fabrication and silicon wafer processing. Using chemistries such as KOH, TMAH, and buffered oxide etchants (BOE), our engineers create cavities, remove thin films, and define device structures with high selectivity and excellent surface quality.
Silicon wet etching relies on controlled chemical reactions to remove material exactly where your design requires it. Every wet etch step runs in-house at our U.S.-based MEMS foundry in Medford, Oregon, on the same line as the photolithography, deposition, and dry etch processes that complete your fabrication flow.
Whether you need a single anisotropic silicon etch on customer-supplied wafers or a fully integrated device process, our team works as an extension of your engineering group, with transparency into every process decision. All work is U.S.-based and ITAR-registered.
Silicon Wet Etching Capabilities
Wet etching is fully integrated with our MEMS foundry capabilities, so etch steps drop cleanly into complete device process flows:
| Etch Chemistry | Target Materials | Masking Strategy | Typical MEMS Applications |
|---|---|---|---|
| KOH (potassium hydroxide) | Crystalline silicon (anisotropic) | LPCVD silicon nitride | Deep cavities, V-grooves, angled sidewalls, suspended membranes |
| TMAH (tetramethylammonium hydroxide) | Crystalline silicon (anisotropic) | Thermal silicon dioxide | Cavities, trenches, and diaphragms with critical layers preserved |
| BOE (buffered oxide etch) | Silicon dioxide layers | Patterned photoresist | Contact windows, sacrificial layer removal, dielectric patterning |
| Metal wet etch | Gold (Au), chromium (Cr), aluminum (Al) | Patterned photoresist | Conductive pathways, electrodes, bonding pads |
Our team works closely with you to optimize etch chemistry, process conditions, and wafer handling for reliable MEMS device performance.
KOH Silicon Etching
Potassium hydroxide (KOH) creates anisotropic silicon etch profiles that follow the natural crystal orientation of the wafer. Because KOH etches silicon at different rates along crystal planes, engineers can form well-defined cavities, V-grooves, and angled sidewalls with excellent dimensional control. That makes KOH a frequent choice when a design calls for deep cavities, suspended membranes, or precisely defined structural features, with consistent etch rates and smooth silicon surfaces across the wafer.
LPCVD silicon nitride often serves as the etch mask for KOH processing. Patterned nitride protects selected regions of the wafer while exposed silicon etches along crystallographic planes, producing predictable sidewall angles and complex device geometries with high precision.
TMAH Silicon Etching
Tetramethylammonium hydroxide (TMAH) provides a highly controllable anisotropic silicon etch with smooth etched surfaces and predictable etch rates. Engineers use TMAH to form cavities, trenches, and membranes in crystalline silicon while preserving critical device layers and surrounding structures.
Thermal silicon dioxide is an effective TMAH etch mask. Thick thermal oxide grown on the wafer resists TMAH chemistry, so patterned oxide masks define cavities, diaphragms, and suspended device structures with precision.
Choosing between chemistries? Our TMAH vs KOH silicon etch guide compares etch behavior, selectivity, and mask compatibility for both processes.
Oxide Wet Etching with BOE
Buffered oxide etch (BOE) solutions selectively remove silicon dioxide layers from wafers, giving engineers precise control when integrating multiple dielectric layers within complex MEMS devices. Common uses include:
- Opening contact windows
- Removing sacrificial oxide layers
- Patterning dielectric thin films
- Preparing surfaces for additional deposition processes
Metal Wet Etching
Wet chemical etching also enables selective removal of metal thin films used in microelectronic and MEMS structures. Our process capability supports metal etchants for PVD-deposited materials such as gold (Au), chromium (Cr), and aluminum (Al), defining conductive pathways, electrodes, and bonding pads on silicon wafers. For metals that resist chemical etchants, such as platinum, our metal lift-off process provides an additive alternative.
Wet Etch or DRIE?
Anisotropic wet etching delivers crystal-plane geometry and batch-process economy, while DRIE deep reactive ion etching produces vertical sidewalls and high-aspect-ratio features. Many device flows use both. See our DRIE vs. silicon wet etch guide for a side-by-side comparison, or ask our engineers which approach fits your design.
From Development to Volume Production
Because wet etch runs inside an active MEMS production fab, the process that etches your first prototype wafers is the same one that supports volume manufacturing. That means no technology transfer, no re-qualification surprises, and no translation loss between development and production.
Request a Quote for Wet Etch Services
Tell us about your device, substrate, and etch requirements, and our engineering team will respond with a practical process path. Request a quote to get started.