MEMS Wafer Processing
Philtech provides MEMS processing, including deep silicon etching and anisotropic wet etching, on 100mm, 150mm, 200mm, and 300mm wafers. The structures shown are a selection of processing examples; other shapes and processing requirements can also be discussed.
MEMS (Micro Electro Mechanical Systems) combine microscopic mechanical structures with electrical functions. They are used in sensors, actuators, as well as other devices.
MEMS fabrication combines processes such as film deposition, photolithography, and etching to create microstructures. The processing method must be selected according to the shape and dimensions of features such as trenches, holes, and pillars formed in the substrate.
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Contact UsDeep Silicon Etching
Deep silicon etching forms deep trenches, holes, and similar features in silicon substrates. The Bosch process, a type of DRIE (Deep Reactive Ion Etching), alternates etching with the formation of a protective film on the sidewalls.
This enables high-aspect-ratio structures with large depths relative to their widths. The examples below show trenches and pillars formed by Bosch etching. Processing difficulty varies with pattern dimensions and density.
Bosch Etching Examples
Width 0.4µm, Depth 18µm
Diameter 50µm, Depth 340µm
Diameter 60µm, Depth 200µm
Trench and Hole Pattern Examples
The following product pages also present examples of trenches and holes in silicon, including pattern shapes, layouts, and cross-sectional observations. Processing methods differ by product.
Anisotropic Wet Etching of Silicon
This method uses chemicals such as KOH (potassium hydroxide) or TMAH (tetramethylammonium hydroxide) and takes advantage of differences in etch rate between silicon crystal planes. It is used to form structures with inclined surfaces along crystal planes.
The examples below show wet etching with TMAH on a (100)-oriented silicon substrate. The slower etch rate of the (111) planes produces inclined surfaces.
TMAH Wet Etching Examples
Mechanical Pattern Formation
Blasting is one method for forming patterns such as holes and trenches.
Mechanical Through-Machining of a 300mm Silicon Wafer
This example shows through-holes with a diameter of 250µm formed in a silicon substrate with a diameter of 300mm and a thickness of 775µm. The technique offers low-cost processing because it does not use dry etching.
