KOH Etching
Modutek Offers an Individualized Approach to KOH Etching
KOH etching is a chemical process used for fabricating silicon nanostructures. This etching process has been studied extensively in both research and real-world applications. Modutek provides individualized solutions for customers who want to use this process by using a etching tank along with their existing wet bench equipment. All of Modutek’s etching tanks are manufactured on-site and built per your specifications. All PFA material is used for cleanliness and compatibility.
Definition of KOH Etching
Potassium Hydroxide (KOH) etching is a wet chemical etching process used to create cavities in silicon. It is a highly corrosive alkaline chemical compound (pH > 12) that is used in conjunction with DI water and thermal regulation. The etch rate is limited, and the precision of Si etching is dependent on consistency throughout the nanochemical process. The process allows for the optimal precision of fabricating Si wafers. In addition, the KOH etching process can be automated for increased efficiency and reduction in cost.
Brief Overview of the KOH Etching Process
The KOH process is implemented in wet bench equipment using Modutek’s TFa or TT series of PFA Teflon tanks. The anisotropic nature of Si etching offers increased flexibility and control after the process is established.
The desired end product is impacted by the etching temperature; the percentage of KOH used; the implementation of crystal planes that act as a stop; the degree of anisotropy; the presence of any atomic defects in Si crystal; and the presence of other impurities naturally found in Si crystal. The doping concentration of Si has a notable impact on KOH etching; boron doped Si can also act as an etch stop if the boron doping concentration exceeds certain parameters.
Benefits of KOH Etching Process
The KOH process has notable advantages when compared to dry etching and other types of silicon wet etching process methods used to create nanostructures.
Benefits Include:
- KOH is safe and easy to handle
- Provides a repeatable process that etches fast
- Lower cost compared to other etching processes
- Superior fit for batch fabrication
Dry etching processes (Hydrazine) may pose notable risk of explosion and harmful toxins. Similar to KOH, Tetramethylammonium Hydroxide (TMAH) is an isotropic wet etching process. KOH is a superior process as TMAH etching is slower, and TMAH etching may result in the formation of hillocks.
Advantages of Modutek’s Individualized Approach to the KOH Process
Modutek’s Teflon Tanks are designed to decrease impurities and unwanted byproducts due to advanced welding techniques with PFA sheet material. After the initial KOH process has been established, continuous adjustments to the etching process are not necessary. We construct all of our products per individual customer specifications and routinely design products that are compatible with a customer’s existing wet bench equipment.
A few notable Modutek design features include the following
- Manual cover with overlapping seal
- Minimizes water lost
- No concentration deficiency over long etch time
- Water condensing system available on all baths (option)
- Auto lid feature (option)
- DI water or IPA spiking system available (option)