KOH Etching

1. Etch rates For silicon, silicon nitride, and silicon dioxide in varying concentrations and temperatures of KOH.
2. Reference: J. Electrochem. Soc. Vol 137, 11, Nov 1990, 3612-3632.
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4. KOH Etching of Silicon 100

   1. KOH etches silicon depending on the concentration of the KOH solution and temperature. Graphs are provided for the etch rates depending on temperature (in degrees Celcius) for various solution concentrations. Experimentation has found that solutions less than 30% KOH yield rough etching. Addition of isopropyl alcohol has been found to decrease the etch rate by approximately 20%.
   2. Etch rates for 20% KOH solution
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   3. Etch rates for 25% KOH solution
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   4. Etch rates for 30% KOH solution
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   5. Etch rates for 35% KOH solution
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   6. Etch rates for 40% KOH solution
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   7. Etch rates for 45% KOH solution
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   8. Etch rates for 50% KOH solution
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   9. Etch rates for 55% KOH solution
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   10. Etch rates for 60% KOH solution
       2. 

5. KOH Etching of Silicon 110

   1. KOH etches silicon depending on the concentration of the KOH solution and temperature. Graphs are provided for the etch rates depending on temperature (in degrees Celcius) for various solution concentrations. Experimentation has found that solutions less than 30% KOH yield rough etching. Addition of isopropyl alcohol has been found to decrease etch rates by approximately 90%.
   2. Etch rates for 20% KOH solution
      2. 
   3. Etch rates for 25% KOH solution
      2. 
   4. Etch rates for 30% KOH solution
      2. 
   5. Etch rates for 35% KOH solution
      2. 
   6. Etch rates for 40% KOH solution
      2. 
   7. Etch rates for 45% KOH solution
      2. 
   8. Etch rates for 50% KOH solution
      2. 
   9. Etch rates for 55% KOH solution
      2. 
   10. Etch rates for 60% KOH solution
       2. 

6. KOH Etching of Silicon Dioxide and Silicon Nitride

   1. KOH etching of silicon nitride was not observed in the study. Therefore, the silicon nitride etch rate is under 1 nanometer per hour if it etches at all. If silicon nitride is being used as a mask for silicon etching, potential etching of the silicon nitride need not be taken into consideration.
   2. KOH etching of silicon dioxide is observable. The etch rates are considerably slower (1-2 orders of magnitude) than that of silicon but should be considered when deep etching is being done. Temperature dependent graphs for the etch rates of silicon dioxide in various concentrations of KOH are given.
   3. Etch rates for 20% KOH solution
      2. 
   4. Etch rates for 25% KOH solution
      2. 
   5. Etch rates for 30% KOH solution
      2. 
   6. Etch rates for 35% KOH solution
      2. 
   7. Etch rates for 40% KOH solution
      2. 
   8. Etch rates for 45% KOH solution
      2. 
   9. Etch rates for 50% KOH solution
      2. 
   10. Etch rates for 55% KOH solution
       2. 
   11. Etch rates for 60% KOH solution
       2. 

7. Anisotropic Etch Geometry

   1. Silicon 100 etches anisotropically, with a 54.74° angle from the plane. Masked silicon will etch as shown in the diagram.
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8. Return to Chemical Etching

9. Anisotropic Crystalline Etch Simulation (ACES)

   1. Anisotropic Crystalline Etch Simulation (ACES) is a first PC-based 3-D etch simulator using a continuous CA model and a dynamic method, which offer high computational speed and drastically reduced memory requirements. It's coded by UIUC MASS Group. The program can simulate silicon etching with different surface orientations in selected etchants with variable etch rate ratios. It can receive 2-D mask designs in common mask formats (including CIF, GDSII, BMP), generate 3D profile in standard solid-modeling languages, and display results using an integrated viewer, which is based on OpenGL.
   2. 
      This link is to the downloadACES Beta 2 for Windows.