The IUP Journal of Electrical and Electronics Engineering
Fabrication of Silicon Tunnel Together with Well-Defined Diaphragm Using Wet Anisotropic Etching

Article Details
Pub. Date : Jul, 2019
Product Name : The IUP Journal of Electrical and Electronics Engineering
Product Type : Article
Product Code : IJEEE31907
Author Name : Arti Arora and Anil Arora
Availability : YES
Subject/Domain : Management
Download Format : PDF Format
No. of Pages : 07

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Abstract

In silicon diaphragm fabrication, smooth walls and bottom formation has been a difficult task during micromachining of (100) silicon due to its orientation-dependent chemical etching. The intended method has been developed in order to realize the perfect diaphragm together with the tunnel using anisotropic etching technique for the fabrication of MEMS-based silicon bulk micromachined acoustic sensor. Due to the restriction of the undercutting process, the wet anisotropic approach offers only limited patterns of silicon diaphragm. Smooth walls and bottom of about 470 μm deep silicon microstructures have been obtained after controlling the etchant composition, temperature and orientation of the masking pattern. LOCOS technique is used to obtain the desired structure. The paper reports the successful method of fabrication of the structure and different complex shapes that may develop during the wet anisotropic etching of the silicon bulk.


Description

Anisotropic etchants for crystalline silicon have been known for a long time (Seidel, 1990). Their first applications included the etching of V-grooves on <100> silicon or U-grooves on <110> silicon to fabricate MOS transistors for high power and high current densities (Ammar and Rodgers, 1980). Increasing attention has been paid to this etching technology, after recognizing its unique capabilities for micromachining three-dimensional structures. Silicon has been employed in a variety of MEMS devices, because of its excellent mechanical electrical and optical properties (Petersen, 1982; and Zhang et al., 1991). The advantages of silicon as a mechanical material are batch-fabrication capability, inexpensive miniaturization of structures and reproducibility of device characteristics. In silicon micromechanical devices (Sze, 1994; Muralt, 2001; McKinstry 2001; Defay et al., 2002; Du et al., 2003; Mo, 2003; Wan et al., 2003; Baboroski, 2004; and Wang et al., 2005), such as acoustic sensors, pressure sensors, accelerometers and force sensors, silicon is used as both mechanical and electrical material.


Keywords

Micromachining, Diaphragm, Acoustic sensor, Etching

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