Electrochemical etch-stop characteristics of TMAH:IPA solutions

A brief review of silicon etching and electrochemistry provides an introduction to galvanic cell formation in silicon/metal contacts in aqueous electrolyte solutions. It is shown that such galvanic cells, which operate under open-circuit conditions, can be used to perform most of the functions of anodic etching and passivation. Applications relevant to sensor fabrication are described. These include the control of surface morphology, etch-stop mechanisms, and microporous and macroporous etching. In addition, surface structuring by open-circuit photoetching, a process which also depends on galvanic effects, is considered.

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“…If the difference between the two passivation potentials is small, as with TMAH solutions [40], this technique cannot be used.…”

Section: ) Electrochemically Controlled P/n Etch Stopmentioning

confidence: 99%

Galvanic cell formation: a review of approaches to silicon etching for sensor fabrication

et al. 2001

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“…Silicon nano-needles, with angles of 3.1° achieved, are formed on a thin n-type silicon-on-insulator (SOI) wafer. The key technology is based on the boron etch-stop of silicon, that is, the etching rate of silicon in TMAH solution decreases with increasing boron doping concentration N A [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Sharp Silicon Nano-Needles Based on Boron Etch-Stop in TMAH Solutions

Yan

Yang

et al. 2011

MRS Proc.

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Operations on biological living cells and molecular devices have driven research towards implementation of high-aspect-ratio nano-needles. However, current nano-needle fabrication is complicated to control the sizes and angles. In this work, we develop a simple method to fabricate repeatable and integrated circuit (IC)-compatible sharp silicon nano-needles based on boron etch-stop in tetramethyl ammonium hydroxide (TMAH) solutions, and the needle angles can be accurately controlled. An analytical model is proposed to efficiently predict the needle sizes and explain the etching evolution of silicon nano-needles.

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“…Isopropyl alcohol (IPA) has been known as a very effective additive to increase the smoothness of silicon etched in KOH solution [14,15]. Its addition has proven useful in the case of silicon etching with TMAH solutions for obtaining smoother surfaces [16][17][18]. The enhancement of surface smoothness through the addition of IPA to the etchant is a unique advantage and needs to be clearly understood in order to exploit it completely.…”

Section: Introductionmentioning

confidence: 99%