A novel process for perfect convex corner realization in bulk micromachining

Pal, Prem; Chandra, Sudhir

doi:10.1088/0960-1317/14/10/018

Cited by 30 publications

(20 citation statements)

References 19 publications

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“…(ii) The second method for the fabrication of perfect convex corner also involve two steps of etching and requires two masks [70,112,128,175]. However it does not need any lithography after the first step of etching.…”

Section: Perfect Convex Corners Using Two-step Etching Techniquesmentioning

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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Section: Perfect Convex Corners Using Two-step Etching Techniquesmentioning

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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“…Hence, achieving very sharp corner without any damage at the convex edge (or any residual at the bottom surface) is a tedious task. In order to avoid these issues and to fabricate microstructures with ideally sharp corners, two techniques have been developed [69,[111][112][113]. The convex corner is formed by the intersection of two {111} planes and, in these techniques, {111} planes are fabricated in two steps.…”

Section: Perfect Convex Corners Using Two-step Etching Techniquesmentioning

confidence: 99%

“…(ii) The second method for the fabrication of perfect convex corner also involve two steps of etching and requires two masks [ 70,112,128,175]. However it does not need any lithography after the first step of etching.…”

Section: Perfect Convex Corners Using Two-step Etching Techniquesmentioning

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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“…Various kinds of corner compensation designs have been proposed and demonstrated for KOH, EDP and TMAH solutions [11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Although other methods have also been reported, they use extra mask and processing steps, which make them more expensive and complex [11,[25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Study of corner compensating structures and fabrication of various shapes of MEMS structures in pure and surfactant added TMAH

Pal

Sato

Shikida

et al. 2009

Sensors and Actuators A: Physical

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A novel process for perfect convex corner realization in bulk micromachining

Cited by 30 publications

References 19 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

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

Study of corner compensating structures and fabrication of various shapes of MEMS structures in pure and surfactant added TMAH

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