Oxford DRIE

About

Oxford System 100 Deep Reactive Ion Etcher (DRIE) in Etch Bay 1

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 (Chandan Ramakrishnaiah or Shivakumar Bhaskaran)

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.