Effect of concentration change of 0.1% triton added 25 wt% TMAH during fabrication of deep cavities with mesa structures in SOI wafer

Menon, P. Krishna; Ashok, Akarapu; Rao, Avvaru Venkata Narasimha; Pandey, Ashok Kumar; Pal, Prem

doi:10.1016/j.mee.2020.111323

Cited by 3 publications

(1 citation statement)

References 38 publications

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“…Among these additives, C 14 H 22 O (C 2 H 4 O)n, n = 9 and 10 (Triton-X-100) can slow down the etching rate of the affected surface orientation, which is frequently exploited for new 3D microstructures [6,8]. Several pieces of literature conclude that the etching rate of bulk Si in surfactant-added TMAH is determined by absorption of surfactant molecules, which subjects to a variety of factors, such as effects of stirring, galvanic interaction between the evolving facets [9], the concentration of etching solution [10]. Hydrophobicity model for vicinal {100}, {110} and {111} surfaces is proposed to explain the adsorption properties of surfactant molecules and verified by experimental evidence [11].…”

Section: Introductionmentioning

confidence: 99%

A Si-based suspended tunnel structure with trapezoidal section by two-step etching

Ma¹,

Wang²,

Zhou³

2022

J. Micromech. Microeng.

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Two - step etching method is used to prepare Si-based suspended tunnel structure with trapezoidal section. In the first wet etching, surfactant Triton-X-100 is added to TMAH enchant to inhibit crystal plane characteristics. Bulk Si Rib with trapezoidal cross section is formed, with inclination of side and height being modulated by changing etching time, so as to obtain good stability. After SiO2 support layer is grown by thermal oxidation, pure 25%TMAH is used in the second wet etching to quickly lateral etch and undercut the bulk silicon under the support layer and form a suspended structure along <100> opening. Using additive-no additive two-step etching method, suspended structure with high stability and compressive strength, good insulation characteristics, high yield can be prepared. It lays a solid foundation for the development of high sensitivity photo, thermal, chemical and gas sensors.

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Section: Introductionmentioning

confidence: 99%

A Si-based suspended tunnel structure with trapezoidal section by two-step etching

Ma¹,

Wang²,

Zhou³

2022

J. Micromech. Microeng.

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show abstract

Influence of fabrication tolerances on performance characteristics of a MEMS gyroscope

et al. 2020

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High speed silicon wet anisotropic etching for applications in bulk micromachining: a review

Pal

Swarnalatha

Rao

et al. 2021

Micro and Nano Syst Lett

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Wet anisotropic etching is extensively employed in silicon bulk micromachining to fabricate microstructures for various applications in the field of microelectromechanical systems (MEMS). In addition, it is most widely used for surface texturing to minimize the reflectance of light to improve the efficiency of crystalline silicon solar cells. In wet bulk micromachining, the etch rate is a major factor that affects the throughput. Slower etch rate increases the fabrication time and therefore is of great concern in MEMS industry where wet anisotropic etching is employed to perform the silicon bulk micromachining, especially to fabricate deep cavities and freestanding microstructures by removal of underneath material through undercutting process. Several methods have been proposed to increase the etch rate of silicon in wet anisotropic etchants either by physical means (e.g. agitation, microwave irradiation) or chemically by incorporation of additives. The ultrasonic agitation during etching and microwave irradiation on the etchants increase the etch rate. However, ultrasonic method may rupture the fragile structures and microwave irradiation causes irradiation damage to the structures. Another method is to increase the etching temperature towards the boiling point of the etchant. The etching characteristics of pure potassium hydroxide solution (KOH) is studied near the boiling point of KOH, while surfactant added tetramethylammonium hydroxide (TMAH) is investigated at higher temperature to increase the etch rate. Both these studies have shown a potential way of increasing the etch rate by elevating the temperature of the etchants to its boiling point, which is a function of concentration of etch solution. The effect of various kinds of additives on the etch rate of silicon is investigated in TMAH and KOH. In this paper, the additives which improve the etch rate have been discussed. Recently the effect of hydroxylamine (NH2OH) on the etching characteristics of TMAH and KOH is investigated in detail. The concentration of NH2OH in TMAH/KOH is varied to optimize the etchant composition to obtain improved etching characteristics especially the etch rate and undercutting which are important parameters for increasing throughput. In this article, different methods explored to improve the etch rate of silicon have been discussed so that the researchers/scientists/engineers can get the details of these methods in a single reference.

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Effect of concentration change of 0.1% triton added 25 wt% TMAH during fabrication of deep cavities with mesa structures in SOI wafer

Cited by 3 publications

References 38 publications

A Si-based suspended tunnel structure with trapezoidal section by two-step etching

A Si-based suspended tunnel structure with trapezoidal section by two-step etching

Influence of fabrication tolerances on performance characteristics of a MEMS gyroscope

High speed silicon wet anisotropic etching for applications in bulk micromachining: a review

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