Oxford DRIE
About
Films / Materials: This is an Oxford Instruments System 100 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. Also etches SiO₂, SiN, Parylene, polyimide, LiNbO₃, and BCB.
Hardware: Inductively coupled plasma (ICP) source with a separate coil (up to 3000 W) and table RF bias (up to 300 W) for independent control of ion density and ion energy. Temperature-controlled electrode at 20°C. 4'' wafer clamp standard; carrier wafers used for smaller pieces. Load lock for fast wafer exchange and high-aspect-ratio etching 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 – Si etch step in Bosch cycles)
- C₄F₈ (octafluorocyclobutane – sidewall passivation polymer in Bosch cycles)
Etch Properties:
- High-rate anisotropic Si etching via the 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, and silicon micromachining for sensors/actuators. Not for exposed metals (except Cr); polymers may be used as masks only.
Usage: Load wafer (4 clamp or carrier for smaller pieces) and pump down via the load lock, select/load a Bosch or continuous etch recipe, set time/power/gas flows, and run. Use endpoint detection if available or a 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
- ICP Power: (max) 3000 W
- Table RF Power: (max) 300 W (13.56 MHz)
- Table temperature: 20°C (controlled/chilled)
- Gases: Ar, O₂, CF₄, CHF₃, SF₆, C₄F₈ (max flows per SOP)
- Features: Bosch process capability, load lock, high-aspect-ratio etching, good uniformity and selectivity
Restrictions and Materials Allowed
| Restrictions | Materials Allowed |
|---|---|
|
|
Safety & Emergency
Required PPE: Safety glasses, cleanroom gloves, bunny suit.
Toxic / hazardous gases used: CHF₃, SF₆, CF₄, C₄F₈ -> fluorine byproducts (HF) possible. Do not open chamber if a gas alarm is active.
If the tool alarms or gas cabinet shows red:
- Press EMO (Emergency Machine Off) -> red button on the front panel.
- Evacuate Etch Bay 1 and notify staff immediately.
- Call Nanofab staff: Jae Lamoure, +1 (213) 740-0743.
- After hours / life-threatening: USC DPS (213) 740-4321, or 911.
Gas leak or chemical exposure: Activate bay alarm, exit cleanroom, call DPS.
Chamber vent failure: Do NOT force open. Leave tool and contact staff.
Dry Etcher Comparison
Use this table to help choose the right etching tool for your process.
| Feature | Oxford RIE | Oxford DRIE | Oxford DRIE-ALE | Oxford III-V | XeF2 Etcher |
|---|---|---|---|---|---|
| Model | PlasmaPro 80 RIE | Oxford System 100 DRIE | Oxford DRIE + ALE | PlasmaPro 100 Cobra | Custom built (Armani group) |
| Location | Etch Bay 1 | Etch Bay 1 | Etch Bay 1 | Etch Bay 1 | Deposition Bay 1 |
| Substrate Size | Up to 200 mm (8") | Up to 4" clamp; 2", 3", 4", 6", 8" possible | Up to 4" clamp; 2", 3", 4", 6", 8" possible | Up to 4" clamp; 2", 3", 4", 6", 8" possible | Up to 6" |
| Etch Type | RIE (capacitively coupled) | DRIE / Bosch (ICP) | DRIE + Atomic Layer Etch | ICP-RIE (cryo capable) | Isotropic chemical etch |
| Table RF Power | 300 W max | 300 W max | 300 W max | 1500 W max | N/A |
| ICP Power | None (RIE only) | 3000 W max | 3000 W max | 1500 W max | N/A |
| Table Temperature | 20°C | 20°C | -120°C to 200°C allowed
(-150°C to 400°C max) |
-120°C to 200°C allowed
(-150°C to 400°C max) |
20°C |
| Gases | Ar, O₂, CF₄, CHF₃, SF₆ | Ar, O₂, CF₄, CHF₃, SF₆, C₄F₈ | Ar, O₂, C₄F₈, SF₆, BCl₃, Cl₂, H₂, N₂O, CH₄, CF₄, CHF₃ | Ar, O₂, SF₆, CH₄, H₂, Cl₂, BCl₃, SiCl₄ | XeF₂ (crystal source) |
| Allowed Materials | Si, SiO₂, Si₃N₄, oxide/nitride masks, Cr | Si, SiO₂, SiN, Parylene, Polyimide, LiNbO₃, BCB | InP, InAs, GaN, AlGaAs, GaAs, InGaAsP, ITO, Si, SiC, MoS₂, WSe, Graphene | InP, InAs, GaN, AlGaAs, GaAs, InGaAsP, ITO, Si, SiC, MoS₂, WSe, Graphene | Si only |
| Disallowed | No metals except Cr; no deep polymer >1 µm | No exposed metals except Cr | No metals except Cr; no deep polymer >1 µm | No metals except Cr; no deep polymer >1 µm | None listed |
| Endpoint Detection | Optical (LEM G50) | Not Available | TBD | Optical (LEM G50) | Not Available |
| Best For | Dielectric etching, passivation removal, via openings, resist descum | Deep Si etching, high-aspect-ratio structures, Bosch process | Precise atomic-layer-level etch control | III-V semiconductors, exotic/compound materials, cryo etching | Fast isotropic Si etching, high selectivity |
| Status | Operational | Operational | Operational | Operational | Operational |
| SOP | SOP | SOP | TBD | SOP | SOP |
Documentation
- SOP
- Quickstart Guide
- Load lock operation video (chamber open)
- Training required – contact lab staff (Chandan Ramakrishnaiah) Request form
Recipes & Data
- Standard Recipes: Standard Recipes Spreadsheet
- Standard recipes include: 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.
Troubleshooting
- Plasma won't ignite
- Check gas flows are stable, pressure is in range, and the ICP/RF matching networks are tuned.
- Etch rate dropped suddenly
- Chamber may need conditioning. Run an O₂ clean recipe and re-check calibration.
- Excessive sidewall scalloping or profile drift
- Re-balance Bosch etch/passivation cycle times; verify SF₆ and C₄F₈ flows.
- Chamber pressure won't drop
- Possible vacuum leak or pump issue. Stop process, notify staff.
Acknowledgment
If results from this tool appear in a publication, please acknowledge the facility:
"This work was performed in part at the USC Nanofab at the University of Southern California, Michelson Center for Convergent Bioscience."
Please also email the citation to chandanr@usc.edu so we can track facility output.