Dry followed by wet backside etching processes for micromachined endfire antennae

Abstract

This paper presents a novel technological process based on dry followed by wet backside silicon etching for the manufacturing of ‘quasi-three edge’ membranes-supported millimeter wave circuits. The process is based on a backside deep reactive ion etching used to remove the first 350 µm of silicon, followed by wet etching in KOH solution, to eliminate the remaining 50 µm of silicon and create quasi-free edge membranes, according to the undercut mechanism. In order to validate the technology, a Yagi–Uda antenna for 45 GHz was designed using the Zeland IE3D software package, and fabricated. The demonstrator was characterized in terms of return loss and isotropic gain using ‘on wafer’ measurements. The agreement between the modeling and the measurements is very good, and validates the new technological approach, which assures free-space propagation conditions for endfire membrane-supported antennae structures.

Towards micro-assembly of hybrid MOEMS components on a reconfigurable silicon free-space micro-optical bench

“…Although desired shape of the structure with sidewalls bordered by two (111) walls on each side can be achieved in (100) oriented wafers, the laser fusing requires non-standard, dedicated equipment. In this work, an attractive alternative to this method was employed as a combination of two successive standard processes of anisotropic etching of silicon: dry deep reactive ion etching, followed by wet etching in aqueous KOH solution [25]. The baseplate structures were fabricated on a n-type, (100)-oriented silicon wafer with thickness of 380 µm and low total thickness variation (TTV < 3 µm).…”

RF MEMS status and perspectives

“…This allows to remove completely the substrate avoiding the substrate mode, enabling a quasi free space electromagnetic processing and consequently very low insertion losses. Some examples of suspended circuit can be found in [1,[7][8][9][10][11][12] with low loss transmission line, high performance filter and high quality factor resonator and suspended antenna. Another approach exploits the strain engineering to fabricate RF components.…”

Single wafer fabrication of a symmetric double-sided beam–mass structure using DRIE and wet etching by a novel vertical sidewall protection technique

“…In the creation of beams and beam-mass structures, extensive work has been carried out using wet etching or deep reactive ion etching (DRIE) or combination of both. DRIE offers the potential to achieve features with a very high aspect ratio, while wet etching has many inherent advantages including low process cost, high etching rate, good surface smoothness, high degree of anisotropy and low environmental pollution [2][3][4][5][6][7][8][9]. In many cases, both DRIE and wet etching are implemented: the mass is often first 4 Author to whom any correspondence should be addressed.…”