2004 Fiscal Year Final Research Report Summary
Mechanisms of chemical anisotropic etching of single crystals consistently applicable throughout Micro/Meso-scopic domains
| Project/Area Number |
14205016
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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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 Kazuo 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, Ecotopia Science Institute, Associate Professor, エコトピア科学研究機構, 助教授 (80273291)
ANDO Taek Nagoya University, Graduate School of Engineering, Assistant Professor, 工学研究科, 助手 (70335074)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Chemical anisotropic etching / Silicon / Quartz / KOH / TMAH / Etching mechanism / Surface morphology / Simulation |
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| Research Abstract |
The aim of the project is to clarify anisotropic etching mechanisms of single crystals such as silicon and quartz throughout all scales from atomistic to micrometer range. We clarified the difference in etching characteristics of two major etchants for silicon ; i.e., KOH and Tetra Methyl Ammonium Hydroxide(TMAH) solutions, in relation to those etching mechanisms. We also experimentally studied the effects of a small amount of impurities in the etchant that affect the etching rate, its anisotropy, and etched surface morphologies. We analytically verified the etching mechanism by calculating atomic removal rates at kinks and steps of a crystal surface using Monte-Carlo simulation that is based on a model considering weakening of atomic bonds caused by attachment of OH-base on the exposed surface. Etching mechanisms are well explained for silicon (111) and its vicinity. Macroscopic etching behavior is apparently dominated by the activeness of steps existing on silicon (111). This model can well explain the reverse in the anisotropy according to the difference in etching species. We recently found that the reverse in anisotropy also happens by a change in concentration of the solution. Thus the reverse in anisotropy proved not being a singular problem of the etchant, but more commonly acceptable phenomena by the change in activeness of the steps and kinks. We are further investigating the etching models for other orientations than (111).
In parallel to the silicon we also characterized the anisotropic etching properties of quartz, using the same methodologies applied to silicon. We evaluated the etching rate of quartz crystal as a function of orientations. This allowed us a 3-D etching profile prediction by using a simulation. This technology is effective to design etching process of quartz for fabricating MEMS devices.
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