Formation of ultra-smooth 45° micromirror on (100) silicon with low concentration TMAH and surfactant: Techniques for enlarging the truly 45° portion

Xu, Yi; Michael, Aron; Kwok, Chee Yee

doi:10.1016/j.sna.2010.12.018

Cited by 46 publications

(39 citation statements)

References 37 publications

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“…In the field of MOEMS, manufacturing of micromirrors formed by {hkl} sidewall planes is particularly interesting (Sadlery et al 1997;Resnik et al 2000;Strandman et al 1995), due to the exact geometries of the etched microstructures and the simplicity of the wet etching technology. The {110} planes are especially attractive, because they can serve as micromirrors inclined at 45°t owards the (100) substrate and thus reflect a light beam at an angle of 90° (Strandman et al 1995;Resnik et al 2005;Yagyu et al 2010;Xu et al 2011). However, to be useful as micromirrors, the {110} planes ought to be very smooth.…”

Section: Introductionmentioning

confidence: 99%

“…However, the {110} planes are patterned with stripes after etching in this solution (Backlund and Rosengren 1992;Zubel and Kramkowska 2004). Although smooth {110} planes can be obtained in TMAH-based solution (Resnik et al 2005;Yagyu et al 2010;Xu et al 2011), it is quite expensive and usually provides lower etch rates than KOH. Therefore, there is still a need for searching for the composition of the KOH-based solution in which smooth {110} planes are achievable.…”

Section: Introductionmentioning

confidence: 99%

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Impact of alcohol additives concentration on etch rate and surface morphology of (100) and (110) Si substrates etched in KOH solutions

Rola

Zubel

2012

Microsyst Technol

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The influence of alcohol concentration on etch rate and surface morphology of (100) and (110) Si planes was investigated in this paper. The etching processes were carried out in KOH solutions with different concentrations of isopropanol and butanols. The etch rate minima versus alcohol concentration were observed for all the alcohols used in the experiments. Furthermore, close to the concentrations of etch rate minima, the smooth (110) planes were obtained. However, the (100) surfaces were covered with hillocks at these concentrations. Based on the surface tension measurements and literature reports, the explanation of appearance of the etch rate minimum was suggested. In the proposed model, the adsorption maximum corresponds to the complete formation of an alcohol monolayer on Si surface and, consequently, to the etch rate minimum. At higher concentrations of alcohol, the monolayer disappears and the etch rate increases.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of alcohol additives concentration on etch rate and surface morphology of (100) and (110) Si substrates etched in KOH solutions

Rola

Zubel

2012

Microsyst Technol

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“…Additionally, the {110} reflective sidewalls could be coated with metal film (e.g. gold) to improve the reflectivity further (Hsiao et al 2009;Xu et al 2011). The above mentioned issues are the challenge for the future research on silicon 45°micromirrors fabrication.…”

Section: Resultsmentioning

confidence: 99%

“…This etching mixture allowed one to obtain high etch rate ratio R(100)/ R(110) and relatively smooth {110} sidewalls. Another nonionic surfactant NCW-1002 was also applied for TMAH etching of {110} micromirrors (Xu et al 2010(Xu et al , 2011Yagyu et al 2010). The etching processes resulted in smooth {110} planes, though the rounded profile of {110} sidewalls in the cross section was reported by Xu et al (2011).…”

Section: Introductionmentioning

confidence: 99%

Silicon 45° micromirrors fabricated by etching in alkaline solutions with organic additives

et al. 2013

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The fabrication of 45°micromirrors by silicon anisotropic etching in potassium hydroxide (KOH) and tetramethylammonium hydroxide (TMAH) solutions containing organic additives is investigated in this paper. The reflective planes are formed by {110} sidewall planes inclined at 45°towards the Si (100) wafer. Isopropyl alcohol and Triton X-100 surfactant are used as additives, because they are supposed to provide the etch rate ratio R(100)/R(110) [ 1, which is necessary for {110} sidewalls development. The fabricated spatial microstructures with 45°sidewalls are examined in terms of the {110} surface roughness and the quality of the {110} sidewall profile. The KOH solution saturated with the alcohol gives the striped {110} surface, though the stripes almost disappear after addition of Triton surfactant to KOH and TMAH etchants. The 45°sidewall profiles fully defined by {110} planes are obtained in KOH as well as TMAH solutions containing additives. The measurements of micromirrors' reflectivity indicate that replacement of the alcohol by Triton surfactant in the KOH solution reduces the optical power loss caused by the reflection. The achieved reflectivity is comparable with the one obtained by etching in the TMAH solution with surfactant.

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“…cantilever, diaphragm, cavity, etc.) [1][2][3][4][5]. It is a low cost technique and suitable for batch process.…”

Section: Introductionmentioning

confidence: 99%

Etching characteristics of Si{110} in 20 wt% KOH with addition of hydroxylamine for the fabrication of bulk micromachined MEMS

Rao

Swarnalatha

Pal

2017

Micro and Nano Syst Lett

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Anisotropic wet etching is a most widely employed for the fabrication of MEMS/NEMS structures using silicon bulk micromachining. The use of Si{110} in MEMS is inevitable when a microstructure with vertical sidewall is to be fabricated using wet anisotropic etching. In most commonly employed etchants (i.e. TMAH and KOH), potassium hydroxide (KOH) exhibits higher etch rate and provides improved anisotropy between Si{111} and Si{110} planes. In the manufacturing company, high etch rate is demanded to increase the productivity that eventually reduces the cost of end product. In order to modify the etching characteristics of KOH for the micromachining of Si{110}, we have investigated the effect of hydroxylamine (NH 2 OH) in 20 wt% KOH solution. The concentration of NH 2 OH is varied from 0 to 20% and the etching is carried out at 75 °C. The etching characteristics which are studied in this work includes the etch rates of Si{110} and silicon dioxide, etched surface morphology, and undercutting at convex corners. The etch rate of Si{110} in 20 wt% KOH + 15% NH 2 OH solution is measured to be four times more than that of pure 20 wt% KOH. Moreover, the addition of NH 2 OH increases the undercutting at convex corners and enhances the etch selectivity between Si and SiO 2 .

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Formation of ultra-smooth 45° micromirror on (100) silicon with low concentration TMAH and surfactant: Techniques for enlarging the truly 45° portion

Cited by 46 publications

References 37 publications

Impact of alcohol additives concentration on etch rate and surface morphology of (100) and (110) Si substrates etched in KOH solutions

Impact of alcohol additives concentration on etch rate and surface morphology of (100) and (110) Si substrates etched in KOH solutions

Silicon 45° micromirrors fabricated by etching in alkaline solutions with organic additives

Etching characteristics of Si{110} in 20 wt% KOH with addition of hydroxylamine for the fabrication of bulk micromachined MEMS

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