STS APS DGRIE/Processes/Fused silica etch
| About this Process | |
|---|---|
| Process Details | |
| Equipment | STS APS DGRIE |
| Technology | DRIE |
| Material | Fused silica, Pyrex |
| Mask Materials | KMPR, SU-8, polysilicon |
| Gases Used | C4F8, He, H2 |
| Date Created | 7/1/2012 |
| Authored By | Kevin Owen |
The Fused silica etch is designed for deep etching of fused silica and quartz substrates. Etch rate up to 5000 Å/min, depending on feature size. The etch has been tested up to 50 μm depth in 20 μm and larger features. This process generates a tremendous amount of heat and cannot be used with standard photoresist. KMPR and polysilicon are the recommended mask materials.
Contents
Procedure
When running this process use the "Fused Silica" Batch recipes for a maximum of 1hr per etch.
Characterization
Etch/Dep Rate
Etch rate is feature size and depth dependent. Smaller features will etch slower than larger ones and higher aspect ratios will also etch slower. Bulk etch rate is approximately 5000 Å/min. The etch exhibits minimal loading effect.
Mask selectivity
The selectivity of fused silica to KMPR is approximately 4:1 for shallower etches, decreasing with depth.
Limitations
KMPR is typically recommended, however SPR 220 has been tested on a 10 min etch on a mounted 4" wafer, and should survive if well mounted.
Etch depth
A 2 hour etch will yield approximately 45-50 μm depth depending on feature size on a fused silica substrate. The etch has been tested for up to 8 hours, but due to challenging lithography and the necessary extended cleans we do not recommend this process.
Substrate material
The above etch rate is based on a fused silica substrate. Glass and pyrex substrates are not allowed to be etched due to impurities in the material.
