Process Hierarchy

  KOH Silicon Etch II
Process characteristics:
Depth of material removed by etch process
Depth of material removed by etch process, must be 0 .. 1000 µm
0 .. 1000 µm
Batch size 25
Etch rate 1.2 µm/min
Solutions and their concentrations.
Material silicon
Primary material removal rate divided by removal rates of secondary materials (i.e., factors by which primary material is removed faster than secondary materials)
silicon dioxide: 200, silicon nitride: 10000, silicon: 1
Sides processed both
Temperature 80 °C
Wafer size
Wafer size
Equipment Constant temperature bath
Equipment characteristics:
Wafer geometry
Types of wafers this equipment can accept
1-flat, 2-flat, notched, no-flat
Wafer holder
Device that holds the wafers during processing.
teflon cassette
Wafer materials
List of wafer materials this tool can accept (not list of all materials, just the wafer itself).
Wafer thickness
List or range of wafer thicknesses the tool can accept
200 .. 1000 µm
  • Wafers should not have any
    organic material (such as
    photoresist) on them.
  • KOH etch is a bulk silicon
    etch whose etch rate is very
    dependent on the orientation
    of the silicon's crystal
    planes. This makes it
    possible to create specific
    geometries difficult to
    produce with other
    micromachining techniques (for
    example V-grooves).
  • Silicon nitride is the preferred
    masking materials for this
    etch (selectivity to silicon:
  • Fast etch rate recipe good for
    through wafer etch.