Oxford DRIE

About

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

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
No exposed metals (except Cr as a mask)	Si SiO₂ SiN Parylene Polyimide LiNbO₃ BCB Oxide / hard masks Chromium (Cr) as exposed metal

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:

1. Press EMO (Emergency Machine Off) -> red button on the front panel.
2. Evacuate Etch Bay 1 and notify staff immediately.
3. Call Nanofab staff: Jae Lamoure, +1 (213) 740-0743.
4. 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.