A simple approach to convex corner compensation in anisotropic KOH etching on a (1 0 0) silicon wafer

Fan, Wei; Zhang, Dacheng

doi:10.1088/0960-1317/16/10/006

Cited by 39 publications

(28 citation statements)

References 16 publications

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“…In order to get the sharp edge convex corners (i.e. criterion to get the convex corner by lateral etching of vertical {100} planes), the following condition must be satisfied [107]:…”

Section: Corner Compensation Geometries For Si{100} Wafermentioning

confidence: 99%

A comprehensive review on convex and concave corners in silicon bulk micromachining based on anisotropic wet chemical etching

Pal

Sato

2015

Micro and Nano Syst Lett

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“…In order to get the sharp edge convex corners (i.e. criterion to get the convex corner by lateral etching of vertical {100} planes), the following condition must be satisfied [107]:…”

Section: Corner Compensation Geometries For Si{100} Wafermentioning

confidence: 99%

A comprehensive review on convex and concave corners in silicon bulk micromachining based on anisotropic wet chemical etching

Pal

Sato

2015

Micro and Nano Syst Lett

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“…The mass is formed by one-mask anisotropic wet etching process and the convex corner compensation etching technique (Fan and Zhang 2006;Offereins 1990;Schroder et al 2001) is used to design the greatest mass. Because the thickness of silicon substrate is 380 μm and the thickness of accelerometer's diaphragm is 15 μm, the depth of wet etching is calculated to be 365 μm.…”

Section: Design Of Accelerometermentioning

confidence: 99%

Monolithic-integrated piezoresistive MEMS accelerometer pressure sensor with glass-silicon-glass sandwich structure

et al. 2016

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Manuel Engesser et al. 2009) have been well developed and widely used in industrial and commercial applications. Recently, with the market expansion of electronic devices including automobiles, aerospace and portable electronics, great research effects have been motivated again to develop monolithic integrated silicon composite sensors that feature high reliability, low costs and mass fabrication capability (Wang et al. 2011(Wang et al. , 2012Xu et al. 2008;Roozeboom et al. 2013).This study aims at developing a novel monolithic composite MEMS sensor. The composite sensor integrated a piezoresistive pressure sensor and a piezoresistive accelerometer on one chip. It has a sandwich structure and is fabricated using bulk-micromachining process (Chen et al. 2009) and anodic wafer bonding technology (Liu et al. 2011;San et al. 2013). The accelerometer adopts double-cantilever-mass structure by which double cantilevers can lessen lateral sensitivity in insensitive direction and the mass can enlarge sensitivity in sensitive direction. The pressure sensor has rectangular diaphragm structure. The mass of accelerometer and the pressure-sensing diaphragm of pressure sensor are simultaneously wet anisotropic etched by using only one mask. Anodic bonding technology is used to seal the pressure-reference cavity for the pressure sensor and form the vacuum chamber for free motivation of accelerometer's cantilever-mass. Glass is bonded with the low pressure chemical vapor deposition (LPCVD) α-Si (amorphous silicon) layer in front side of wafer and with the silicon substrate in back side, respectively, to form sandwich structure. Around bonding areas in front side of wafer, trenches are designed and fabricated to ensure the electrical conduction between the LPCVD α-Si layer and the silicon substrate, which can protect the piezoresistors from p-n junction break-down during anodic bonding process in front side of wafer.Abstract A monolithic composite MEMS sensor with sandwich structure is designed, simulated, fabricated and characterized. It consists of a rectangular diaphragm piezoresistive pressure sensor and a double-cantilever-mass piezoresistive accelerometer. The professional MEMS software, Intellisuite 8.5, is used to simulate the performances of the composite sensor. The composite sensor is fabricated on a (100)-silicon wafer by using MEMS bulk-micromachining and anodic bonding technology. One-step wet anisotropic etching process on the backside of the wafer can form the main backside shape of the composite sensor including the mass of accelerometer and the pressure sensing diaphragm. The glass-silicon-glass sandwich structure is formed with α-Si (amorphous silicon)-glass anodic bonding on the top surface of the wafer and Siglass anodic bonding at the bottom. The fabricated composite sensor is measured, resulting in 33.0 μV/V kPa sensitivity for the 450 kPa-ranged pressure sensor, as well as, 11.2 μV/V g sensitivity for the 125 g-ranged accelerometer. The die size of the composite sensor chip is 2.5 mm × 2.5 mm × 1.4 mm. The...

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“…However, <100> −oriented beam compensation design provides very sharp corner, high spatial requirement along its length is a serious concern. In order to reduce the spatial requirement, superimposed square shape design is proposed [107]. In this geometry, one square of side a and two of side a/2 are superimposed at the apex of the convex corner, as illustrated in Figure 34.…”

Section: (Iii) <110> Oriented Beammentioning

confidence: 99%

“…In order to get the sharp edge convex corners (i.e. criterion to get the convex corner by lateral etching of vertical {100} planes), the following condition must be satisfied [107]: The SEM pictures of mesa structures fabricated in 30 wt% KOH and 25 wt% TMAH are shown in Figure 35(a) and (b), respectively. In both cases, the convex corners of mesa structures are well-defined.…”

Section: (Iii) <110> Oriented Beammentioning

confidence: 99%

A comprehensive review on convex and concave corners in silicon bulk micromachining based on anisotropic wet chemical etching

Pal¹,

Sato²

2016

Nano Online

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Wet anisotropic etching based silicon micromachining is an important technique to fabricate freestanding (e.g. cantilever) and fixed (e.g. cavity) structures on different orientation silicon wafers for various applications in microelectromechanical systems (MEMS). {111} planes are the slowest etch rate plane in all kinds of anisotropic etchants and therefore, a prolonged etching always leads to the appearance of {111} facets at the sidewalls of the fabricated structures. In wet anisotropic etching, undercutting occurs at the extruded corners and the curved edges of the mask patterns on the wafer surface. The rate of undercutting depends upon the type of etchant and the shape of mask edges and corners. Furthermore, the undercutting takes place at the straight edges if they do not contain {111} planes. {100} and {110} silicon wafers are most widely used in MEMS as well as microelectronics fabrication. This paper reviews the fabrication techniques of convex corner on {100} and {110} silicon wafers using anisotropic wet chemical etching. Fabrication methods are classified mainly into two major categories: corner compensation method and two-steps etching technique . In corner compensation method, extra mask pattern is added at the corner. Due to extra geometry, etching is delayed at the convex corner and hence the technique relies on time delayed etching. The shape and size of the compensating design strongly depends on the type of etchant, etching depth and the orientation of wafer surface. In this paper, various kinds of compensating designs published so far are discussed. Two-step etching method is employed for the fabrication of perfect convex corners. Since the perfectly sharp convex corner is formed by the intersection of {111} planes, each step of etching defines one of the facets of convex corners. In this method, two different ways are employed to perform the etching process and therefore can be subdivided into two parts. In one case, lithography step is performed after the first step of etching, while in the second case, all lithography steps are carried out before the etching process, but local oxidation of silicon (LOCOS) process is done after the first step of etching. The pros and cons of all techniques are discussed.

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A simple approach to convex corner compensation in anisotropic KOH etching on a (1 0 0) silicon wafer

Cited by 39 publications

References 16 publications

A comprehensive review on convex and concave corners in silicon bulk micromachining based on anisotropic wet chemical etching

A comprehensive review on convex and concave corners in silicon bulk micromachining based on anisotropic wet chemical etching

Monolithic-integrated piezoresistive MEMS accelerometer pressure sensor with glass-silicon-glass sandwich structure

A comprehensive review on convex and concave corners in silicon bulk micromachining based on anisotropic wet chemical etching

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