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Article title RESEARCH OF WET SIO2 SACRIFICIAL LAYER ETCHING FOR MEMS STRUCTURES FORMING BASED ON POLY-SI*/SIO2/SI
Authors E.Yu. Gusev, J.Y. Jityaeva, V.A. Gamaleev, A.S. Kolomiytsev, I.N. Kots, A.V. Bykov
Section SECTION IV. ELECTRONICS AND NANOTECHNOLOGY
Month, Year 02, 2015 @en
Index UDC 621.38.049.77
DOI
Abstract This paper presents results of the removal of the silicon dioxide sacrificial layer by wet etching. The samples were polysilicon structural layer on thermal SiO2/n-Si(100) substrates. The samples were patterned by focused ion beams lithography: a part of them down to SiO2 layer, another ones to substrate. The structures were etching at buffered solution of hydrofluoric acid and ammonium fluoride (HF: NH4F = 1:4) for 10, 20, 40 and 60 seconds and for two type patterns. The series of beam type elements were fabricated and were investigated by scanning electron microscopy and focused ion beams. The independence of the etching parameters on pattern width is shown. SiO2 etch figures (profiles) were measured by focused ion beams. It has been established that the sacrificial etching results in well-known etch figure for polysilicon pattern and atypical vertical shape for dioxide silicon pattern. The time dependence of the lateral etch depth was found. The etch rate was approximately of about 20 nm/sec, and the minimum time required for sacrificial SiO2 removing under the beams width of 0.5–2.5 mm was in the range of 11 to 62.5 seconds. It was established that beams perforation significantly reduces this time. A potential of negative impact of focused ion beams on MEMS sensors fabrication technology was noted. The outcome of this study is useful for the development of manufacturing processes and fabrication of the inertial sensors (gyroscopes, accelerometers) and other MEMS by surface micromachining.

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Keywords Nanotechnology; MEMS; cantilevers; surface micromachining; focused ion beams; wet etching; silicon dioxide; polycrystalline silicon.
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