Process Hierarchy

If you are interested in this process, either by itself or as part of a longer processing sequence, please send us email at engineering@mems-exchange.org or call us at (703) 262-5368
  Supercritical CO2 Dry
Ambient
Ambient to which substrate is exposed during processing
 methanol/carbon dioxide/air
Batch size 1
Pressure
Pressure of process chamber during processing
 77 atm
Process duration 40 min
Sides processed both
Temperature 35 °C
Wafer size
Wafer size
Equipment GT Technologies Supercritical CO2 Cleaner Dryer
Equipment characteristics:
Wafer geometry
Types of wafers this equipment can accept
 no-flat, 1-flat, 2-flat, notched
Wafer holder
Device that holds the wafers during processing.
 stainless steel
Wafer materials
List of wafer materials this tool can accept (not list of all materials, just the wafer itself).
 alumina, gallium arsenide, gallium phosphide, germanium, glass (category), indium phosphide, metal (category), Pyrex (Corning 7740), quartz (single crystal), sapphire, silicon, Borofloat (Schott), silicon dioxide, silicon germanium, silicon on insulator, silicon on sapphire
Wafer thickness
List or range of wafer thicknesses the tool can accept
 200 .. 1600 µm
Comments:
  • Supercritical CO2 drying process allows samples to be dried without any surface tension, thus reducing the likelihood of stiction. This process is typically used to dry samples that have been rinsed in de-ionized water. The de-ionized water is replaced by methanol prior to the drying process, and then the methanol is displaced by liquid CO2 as part of the drying process.
  • This process may also be used to clean samples.
  • Samples will be placed in methanol prior to drying. Samples must be compatible with methanol and liquid CO2.
  • Cost is per run, which in the case of dies refers to the number of dies that fit in the chamber at once.
  • For devices with long diffusion lengths (i.e. where CO2 is expected to penetrate long distances through narrow channels), drying time may need to be increased to ensure all methanol is displaced. This circumstance may require additional process time (and cost) as well as necessitate a process characterization run or two.