Oxford DRIE
About
Process: This is a high-density plasma deep reactive ion etcher (DRIE) optimized for anisotropic deep silicon etching using the Bosch process (alternating SF₆ etch and C₄F₈ passivation cycles). It produces high-aspect-ratio features with smooth sidewalls, ideal for MEMS, through-silicon vias (TSVs), and advanced silicon micromachining.
Hardware: Inductively Coupled Plasma (ICP) source with separate coil (up to 3000 W) and table RF bias (up to 300 W). Temperature-controlled electrode at 20°C. 4" wafer clamp standard; carrier wafers used for smaller pieces. Load lock for fast wafer exchange. High-aspect-ratio etching capability with excellent selectivity and profile control.
Gases:
- Ar (argon – physical sputtering enhancement)
- O₂ (oxygen – polymer removal or oxidation)
- CF₄ (tetrafluoromethane – fluorine etching)
- CHF₃ (trifluoromethane – selective etching/passivation)
- SF₆ (sulfur hexafluoride – isotropic Si etch in Bosch cycles)
- C₄F₈ (octafluorocyclobutane – sidewall passivation polymer in Bosch cycles)
Etch Properties:
- High-rate anisotropic Si etching via Bosch process
- Smooth, vertical sidewalls with scalloping control
- High selectivity to masks (e.g., SiO₂, photoresist, hard masks)
- Aspect ratios >20:1 possible depending on feature size and recipe
- Good uniformity across 4–6" wafers
Applications:
- Deep silicon trenches and pillars for MEMS
- Through-silicon vias (TSVs)
- Microfluidic channels
- Photonic crystal structures
- High-aspect-ratio gratings
- Silicon micromachining for sensors/actuators
Usage: Load wafer (4" clamp or carrier for smaller), pump down via load lock, select/load Bosch or continuous etch recipe, set time/power/gas flows, run process. Use endpoint detection if available or timed etch. Monitor particles and profile post-etch.
Detailed Specifications
- Model: Oxford System 100 Deep Reactive Ion Etcher
- Location: Etch bay 1
- Substrate size: 4" wafer clamp standard; smaller pieces on carrier wafers; 2", 3", 4", 6", 8" possible
- Table temperature: 20°C (controlled/chilled)
- Plasma power:
* ICP coil: up to 3000 W * Table RF bias: up to 300 W
- Gases: Ar, O₂, CF₄, CHF₃, SF₆, C₄F₈
- Features: Bosch process capability, load lock, high-aspect-ratio etching, good uniformity and selectivity
- Restrictions: No exposed metals (except Cr); avoid deep etching of polymers
- Other: Excellent for deep Si features in research and prototyping
Documentation
- SOP – Standard Operating Procedure
- Quickstart Guide
- Load lock operation video (chamber open)
- Recipes: Standard Recipes Spreadsheet
- Training required – contact lab staff (Joey)
Recipes & Data
- Standard Recipes: Bosch process for deep Si etch (high-rate anisotropic); continuous SF₆ etch for isotropic; O₂ plasma clean
- Process Control: Measure etch depth/rate/profile via SEM or Dektak profilometer. Check sidewall roughness and scalloping. Perform test etches and particle scans post-run.
- Notes: Use carrier wafers for pieces. Adjust cycle times for scallop size vs. rate trade-off. Monitor mask erosion for selectivity.
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