1997 Fiscal Year Final Research Report Summary
Fabirication Technology of Three-Dimentional Microstructures Made of Single-crystal Silicon
| Project/Area Number |
08455045
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied physics, general
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| Research Institution | Nagoya University |
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Principal Investigator |
SATO Kzuo Nagoya University, Graduate, School of Engineering, Professor, 工学研究科, 教授 (30262851)
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| Co-Investigator(Kenkyū-buntansha) |
SHIKIDA Mitsuhiro Nagoya University, Graduate, School of Engineering, Asistant, 工学研究科, 助手 (80273291)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Silicon / Orientation-dependent etching / Potassium-hydroxide (KOH) / Tetramethyl-ammonium-hydroxide (TMAH) / Etching rate / Surface roughness / Process simulation / MEMS |
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| Research Abstract |
We evaluated orientation dependence in the etching rate of single-crystal silicon for two different etchants ; potassium-hydroxide (KOH) and tetramethyl-ammonium-hydroxide (TMAH) water solutions. Etching rates for a number of crystallographic orientations were measured for a wide range of etching conditions in terms of etchants' concentration and temperature.
We found that the orientation dependence significantly varied according to changes both in concentration and temperature. We also found different types of orientation dependence in etching rate around (111) between TMAH and KOH solutions. This means the bonding energy of the silicon crystal lattice is not a single factor that dominates orientation dependence, and there exist different etching mechanisms, for the two etchants.
We further investigated roughening of single-crystal silicon during chemical anisotropic etching using KOH water solutions. The change in roughness strongly depends on the crystallographic orientation. We made a map showing roughness distribution as a function of orientation. Smooth surface appears in a region including (100), (200), and (311). Very rough surface appears in a region including (320) and (210). We clarified that roughened surface shows the facet textures composed of certain crystallographic planes.
The obtained data allowed us numerical simulation of etching profiles which is necessary for designing fabrication process of MEMS devices in industry. On the other hand, it is also of importance for physical chemists investigating atomic-scale models of the anisotropic etching process. We are going to start an international joint research as a Grant-in-Aid Program from 1998 fiscal year investigating the etching mechanisms on the atomic scale in collaboration with the University of Twente, the Netherlands.
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