Oral Presentation
Application of Bosch-Etching and Assembly Process in Corrugated Silicon Platelet Feed Horn
Presenter: Yen-Pin Chang (ASIAA)
The corrugated feed horn is a critical component of the receiver system designed by Dr. Lee for the 150/230 GHz dual-band receiver used in the E-KVN (East-Asian VLBI Network). This receiver operates across two frequency bands and requires high-precision components to ensure optimal performance at millimeter wavelengths.
We successfully fabricated a corrugated horn consisting of 56 silicon platelets, each 290 μm thick. Each platelet corresponds to either a ridge or groove of the horn's corrugation profile. A two-stage Bosch deep reactive ion etching (DRIE) process, combined with a polishing step, was developed to accurately define a full corrugation period within the 290 μm thickness, over diameters ranging from 0.72 mm to 6.88 mm. Isotropic metal deposition (Ti: 35 nm / Au: 200 nm) was performed on both sides of each silicon platelet using a sputtering system to prevent corners without adequate metalization. The platelets were then precisely stacked and aligned using silicon-based alignment pins to ensure high assembly accuracy.
In this work, we also demonstrate a method for significantly reducing Bosch etch residues by optimizing the timing between etch and passivation cycles. This improvement is particularly beneficial for silicon horn structures and other microfabricated silicon components, such as membranes and complex microstructures.
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