Fluorine ICP Etcher (PlasmaTherm/SLR Fluorine ICP)

Fluorine ICP Etcher (PlasmaTherm/SLR Fluorine ICP) Location Bay 2 Tool Type Dry Etch Manufacturer Plasmatherm (Unaxis) Model SLR Series Description SiRIE Based Flourine Etcher for Bosch MEMS Processes Primary Supervisor Tony Bosch (805) 893-3486 bosch@ece.ucsb.edu Secondary Supervisor Aidan Hopkins Recipes Dry Etch Recipes SignupMonkey: Sign up for this tool

About

The system is a Plasma-Therm 770 SLR series system with a loadlock, dedicated to fluorine-based gases (system aka. "FL-ICP"). The system has an Inductively Coupled Plasma (ICP) coil and a capactively coupled substrate RF supply to independently control plasma density and ion energy in the system. Helium back-side cooling is available to keep the sample cool during the etch. The system is fully computer controlled in all aspects of the pumping cycles and process control, and can be programmed by the user.

The system is generally meant for any fluorine-containing etch, which is typically for etching materials like SiO₂, Si₃N₄, Silicon, or other materials with volatile fluoride etch products.

The fixturing is configured for 4" diameter Si wafers and uses a ceramic clamp on the outer ~5mm of the 100mm wafer to hold the sample on the RF chuck.

Smaller samples can be mounted onto 100mm carrier wafers, either with no adhesive (sample temperature will be higher), or with Santovac oil for better thermal cooling. However, great care must be taken to ensure no oil, photoresist or small pieces are placed on the outer 5mm of the carrier wafer, as the ceramic clamp will physically press on this outer region, potentially causing stiction or wafer breakage if foreign or sticky substances are in those regions.

The in-situ laser monitor installed on the chamber allows for repeatable etches and endpoint detection via continuous optical monitoring of the wafer reflectivity in a user-determined location, through a porthole on the chamber.

Detailed Specifications

• 1000 W ICP coil power at 2 MHz and 500 W substrate bias at 13.56 MHz plasma generators
• C₄F₈, SF₆, O₂, Ar, N_2, CHF_3, CF₄ gases available
• He-back-side cooling, 10°C std. chuck temp.
• Single 100mm/4-inch wafer handling with physical topside clamp, contacting outer 5mm of wafer.
  • Small samples may be mounted with oil or no adhesive, but must be far away from this 5mm edge exclusion zone.
  • No photoresist or oil is allowed to contact the clamp, or wafers will get stuck and possibly break in the chamber.
• Windows-based computer control of process and wafer handling
  • Easy to chain recipes via "Batch" programming, eg. SiO2 Etch / Si Etch / PR strip in a single load.
• Laser endpoint monitoring with camera and simulation software, for repeatable etching - see: Intellemetrics LEP 500

Documentation

• Fluorine Etcher Operating Instructions (Cortex Software)

• How to restart software on Plasma-Therm Cortex Software
• Laser Monitor procedures
• How to edit recipe
• Cleaning rules
• Manual Edge-Bead Removal Techniques - 5mm of outer edge must be free of photoresist, use these techniques to accomplish that for full wafers.

Recipes

• Recipes > Dry Etching > PlasmaTherm/SLR Fluorine Etcher
  • Starting point recipes for the FL-ICP, including SiO₂ and Si etches.
  • Process Control Data records "calibration" etches to test tool performance.
• You can see a full list of all tools and all materials able to be etched on our Dry Etching Recipes Table.

Process Control Data

Plots of etch calibrations can be found on the following spreadsheets:

• SiO₂ Etching with CHF3/CF4 - Etch Data
• SiO₂ Etching with CHF3/CF4 - Plots
  

  Click for Process Control Charts
  
  
• SiVertHFv2 - Full Wafer Si etching with ~50% open area and resist mask
• Si Etching with C₄F₈/SF₆/CF₄ - Etch Data
• Si Etching with C₄F₈/SF₆/CF₄ - Plots
  

  Click for Process Control Charts
  

  Example of 1.65µm Deep Etched Silicon, 2µm Pitch. (Image Credit: Noah Dutra 2024-09)