Anisotropic etching of silicon in (CH/sub 3/)/sub 4/NOH solutions

Tabata, Osamu; Asahi, Ryouji; Funabashi, Hirofumi; Saito, Susumu

doi:10.1109/sensor.1991.149007

Cited by 22 publications

(9 citation statements)

References 6 publications

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“…For typical TMAH solutions, etch-rate and surface roughness decrease as the TMAH concentration is increased. Tabata et al [29], [30] studied this and found that at 5 wt%, the surfaces are quite rough due to longer H bubble residence times, becoming quite smooth at approximately 20% (note that the formula given above is 10 wt%, trading off some surface roughness for lack of aluminum etching).…”

Section: B Anisotropic Wet Etchingmentioning

confidence: 99%

Bulk micromachining of silicon

Kovacs

Maluf²,

Petersen³

1998

Proc. IEEE

656

374

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Bulk silicon etching techniques, used to selectively remove silicon from substrates, have been broadly applied in the fabrication of micromachined sensors, actuators, and structures. Despite the more recent emergence of higher resolution, surfacemicromachining approaches, the majority of currently shipping silicon sensors are made using bulk etching. Particularly in light of newly introduced dry etching methods compatible with complementary metal-oxide-semiconductors, it is unlikely that bulk micromachining will decrease in popularity in the near future. The available etching methods fall into three categories in terms of the state of the etchant: wet, vapor, and plasma. For each category, the available processes are reviewed and compared in terms of etch results, cost, complexity, process compatibility, and a number of other factors. In addition, several example micromachined structures are presented.

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Section: B Anisotropic Wet Etchingmentioning

confidence: 99%

Bulk micromachining of silicon

Kovacs

Maluf²,

Petersen³

1998

Proc. IEEE

656

374

View full text Add to dashboard Cite

show abstract

“…A number of different etchants produce this type of silicon profile, and tetramethyl ammonium hydroxide [TMAH, (CH 3 ) 4 NOH) [16,17] has been selected for this work, as it is compatible with CMOS technology [18]. It has the further advantages that it can be mixed with other chemicals to prevent it etching aluminium interconnect [19] and that it is less toxic than most other anisotropic etch solutions, such as alkaline metal hydroxides.…”

Section: Cavity Constructionmentioning

confidence: 99%

“…The etch solution used was 22% TMAH in water, heated to 908C, providing a ,100. etch rate of 40 mm min 21 . The relatively high concentration and temperature give an even etch, without hillocking [17], while still stopping on the membrane of silicon dioxide and nitride upon which the gold electrode is fabricated.…”

Section: Cavity Constructionmentioning

confidence: 99%

Miniaturised drug delivery system with wireless power transfer and communication

Smith

Tang

Stevenson

et al. 2006

IET Seminar on MEMS Sensors and Actuators

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The development of an implantable system designed to deliver drug doses in a controlled manner over an extended time period is reported. Key performance parameters are the physical size, the power consumption and also the ability to perform wireless communications to enable the system to be externally controlled and interrogated. The system has been designed to facilitate wireless power transfer, which is very important for miniaturisation as it removes the need for a battery.

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“…A water solution of tetramethylammonium hydroxide TMAH [38][39][40][41][42][43] is also used for silicon etching. The solution shows very high selectivity against LPCVD silicon nitrides and thermal silicon dioxide (few thousands:1) and remains harmless to health [41].…”

Section: Etching Solutions Chemical Reactions Etching Modelsmentioning

confidence: 99%

“…3.14. Etch rates of silicon as a function of concentration of KOH a) for different orientations (110), (100),(111) at 80°C[46], b) for different temperatures of solution for (100) plane[43].…”

mentioning

confidence: 99%

Deep, Three-Dimensional Silicon Micromachining

Bonding in Microsystem Technology

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Three-dimensional (3-D) silicon structures (also called silicon micromechanical structures, micromechanical constructions or just micromechanical structures) are commonly produced by means of wet deep micromachining of silicon substrates. Structures are truly three-dimensional; they are micromachined ''through'' a substrate.The description of wet deep micromachining, presented in this chapter, begins with determination of the mechanical properties of silicon and characterization of silicon substrates used for fabrication of micromechanical structures and basic features of wet anisotropic etching of silicon (focused on etching in KOH). Next, fabrication procedures of basic silicon microconstructions, and examples of its application in microsystems, are described. * In ref. [9] the method of plastic permanent strain of silicon microstructures is described, as well as the permanent strain of a silicon substrate (heated to 800°C) by means of the method of applying a controlled pressure in such a way that material deformation does not exceed 0.1 mm/min. This means that silicon ''flows'' mechanically at a higher temperature. This phenomenon is of no significance in silicon microsystems, because their working temperature does not exceed a few hundred degrees centigrade. * This weight is maintained during silicon monocrystal fabrication through a narrow (2 mm) silicon seed neck. Tensile stress generated in the neck amounts to over 12 MPa [1]. However, the material does not crack. * Much credit for the discovery of anisotropic properties of crystals should be given to Rene ´-Just Hau ¨y, a canon from the Notre-Dame Cathedral of Paris in about 1802 (Traite `de Crystalographie, 1822). * It has been estimated that flying micro objects covered with such ''skin'' can reach speed of 20M (M -Mach number) in earth's atmosphere. † Grove-Deal effect: a strongly curved silicon surface oxidizes slower than a flat one.

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Anisotropic etching of silicon in (CH/sub 3/)/sub 4/NOH solutions

Cited by 22 publications

References 6 publications

Bulk micromachining of silicon

Bulk micromachining of silicon

Miniaturised drug delivery system with wireless power transfer and communication

Deep, Three-Dimensional Silicon Micromachining

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