Etching baths with varying concentrations of potassium hydroxide (KOH) and controlled temperatures are used to create microscopic structures on silicon wafers. Semiconductor manufacturing and research facilities usual prefer the KOH etching process because it provides controlled and uniform etching results with a high degree of precision. In addition, it’s also comparatively safe.
The silicon surface is masked to enable etching and the creation of cavities in specific areas, based on the layout of the final semiconductor product. The etch rate can be precisely controlled by adjusting the bath temperature and the levels of KOH. The KOH etching is also influenced by the following:
- The presence of atomic defects in the silicon crystal
- The lattice planes of the crystalline silicon
- Boron doping of the silicon
- Natural impurities
The oriention of the lattice planes in a particular direction can also influence and control the direction of the etching and the shape of the cavities created in silicon. Also boron doping can be used to stop etching in a specific direction. These along with the mask are factors that permit the creation of cavities in required shapes and orientations.
The advantages of KOH etching include:
- Easy to handle
- Rapid etching
- Excellent reproductivity
- Provides high precision when process variables are strictly controlled
Modutek’s KOH Etching process equipment includes PFA Teflon tanks, circulation and filtering systems as well as cassette handling equipment. Modutek also provides customized equipment for a particular application, by size, capacities, and controls. These may include the KOH processing tank, the recirculating system, and the silicon wafer handling. Modutek uses the latest state-of-the-art technology to provide high accuracy and exceptional output quality.
For more details read the complete article titled “Using KOH Etching for Batch Processing” and and contact Modutek if you have questions or would like to discuss your particular application requirements.