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
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  Polysilicon plasma etch (anisotropic, MOS clean)
Process characteristics:
Depth
Depth of material removed by etch process
Depth*
Depth of material removed by etch process, must be 0.01 .. 1 µm
0.01 .. 1 µm
Ambient
Ambient to which substrate is exposed during processing
 carbon tetrafluoride, HBr, chlorine, helium, oxygen
Aspect ratio 10
Batch size 4
Etch rate 0.3 µm/min
Material polysilicon
Min feature size 1 µm
Pressure
Pressure of process chamber during processing
 100 mTorr
Selectivity
Primary material removal rate divided by removal rates of secondary materials (i.e., factors by which primary material is removed faster than secondary materials)
 photoresist (category): 10, polysilicon: 1, silicon dioxide: 10
Sides processed either
Temperature 60 °C
Wafer size
Wafer size
Equipment Applied Materials Precision 5000 (chamber C)
Equipment characteristics:
Wafer holder
Device that holds the wafers during processing.
 mechanical clamp
Wafer materials
List of wafer materials this tool can accept (not list of all materials, just the wafer itself).
 silicon, quartz (single crystal), silicon on insulator, silicon germanium
Wafer thickness
List or range of wafer thicknesses the tool can accept
 350 .. 750 µm
Comments:
  • This is an MOS clean machine.
  • Amorphous silicon and
    silicon can be etched as
    well.
  • Resist must be baked at 110
    degC at least 24 hrs before
    etching.
  • No resist allowed on
    backside of wafers.
  • Resists thicker that 1.6 um
    will burn. Users should
    consider an alternate
    masking material.
  • Quartz wafers must have
    non-transparent material on
    backside.
  • The outer 5 mm of the edge
    of the wafers must be free
    of resist to avoid wafers
    sticking the the chuck clamp.
  • Endpoint detection
    available, assuming etch
    stop material is oxide.