Silicon anisotropic etching in TMAH solutions containing alcohol and surfactant additives

Zubel, Irena; Kramkowska, M.; Rola, Krzysztof

doi:10.1016/j.sna.2012.02.018

Cited by 37 publications

(20 citation statements)

References 24 publications

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“…In case of TMAH, an increase in alcohol concentration did not cause reduction of etching rate of (110) plane and the anisotropy ratio V (110) /V (100) was still higher than 1. Similar behavior was observed for butanol 22 . It means that the solution can be successfully used for texturing silicon surfaces but not for etching any complex 3D shapes.…”

Section: Results Of Anisotropic Etchingsupporting

confidence: 82%

Behavior of tensioactive compounds in the solutions for silicon anisotropic etching

2013

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In this work, results of measurements of surface tension of KOH and TMAH solutions containing alcohol additives were used to assess the behavior of the alcohols during silicon anisotropic etching. Surface tension of KOH and TMAH solutions containing additives of alcohols with one or more hydroxyl groups as well as etching rates and surface roughness of Si(100) and Si(110) surfaces etched in these solutions were analyzed. An improvement in roughness of both the planes was observed after addition of the alcohols to the KOH and TMAH solutions, however reduction of etching rates of Si(110) planes occurred only in KOH solutions. Based on surface tension measurements, it was stated that reduction of etching rates results from selective adsorption of the surface active compound on Si surfaces, which is possible due to adsorption layer formed on the solution surface of KOH etchant. The adsorption layer does not appear in TMAH + alcohols solutions, which accounts for a different behavior of TMAH-based etchants.

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Section: Results Of Anisotropic Etchingsupporting

confidence: 82%

Behavior of tensioactive compounds in the solutions for silicon anisotropic etching

2013

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“…A low concentration of IPA in KOH [33,[129][130][131][132][133] and a very small concentration of surfactant (e.g. 0.1% v/v) in TMAH [134][135][136][137][138][139][140][141][142][143][144][145][146][147] ensure a significant reduction in the etch rates of {110} and its vicinal planes (or the planes between {110} and {111} surfaces such as {441}, {331}, {221}, etc.). Recently, surfactant added KOH is characterized to alter the etching anisotropy and etched surface morphology [148,149].…”

Section: Difference Between Etch Rate Underetching and Undercuttingmentioning

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: Difference Between Etch Rate Underetching and Undercuttingmentioning

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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Silicon anisotropic etching in TMAH solutions containing alcohol and surfactant additives

Cited by 37 publications

References 24 publications

Behavior of tensioactive compounds in the solutions for silicon anisotropic etching

Behavior of tensioactive compounds in the solutions for silicon anisotropic 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

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