A Novel Deep Hole Etching in NLD Plasma Low GWP Gases
As for etching of quartz or glass, CF<sub>4</sub> and C<sub>3</sub>F<sub>8</sub> and C<sub>4</sub>F<sub>8</sub> are mainly used. And, much SF<sub>6</sub> gas is used for etching of silicon. The case that uses together a C<sub>4</sub>F<sub>8</sub>-CVD method is also in sidewall protection film formation. However, these gases have a very large GWP. Since a MEMS market becomes larger in the future, the gas used by DRIE needs the reduction in GWP. This research is developing quartz etching technology, and succeeded in etching of the GWP free etching of Pyrex glass via using C<sub>3</sub>F<sub>7</sub>I. Furthermore, the method of performing anisotropic deep silicon etching by introducing a sputtering system into DRIE technology was invented, and C<sub>4</sub>F<sub>8</sub> free etching anisotropic etching was also successful. Therefore, the NLD etching in the MEMS field is very useful equipment, which can realize drastic GWP reduction and can propose highly efficient etching technology.
Deep dry etching of borosilicate glass using fluorine-based high-density plasmas for microelectromechanical system fabrication
For the fabrication of microelectromechanical system devices, deep trench etching of borosilicate glass (Corning 7740) has been investigated using SF6/Ar inductively coupled plasma. Since borosilicate glass contains metal elements which produce nonvolatile fluorides, dry etching of its smooth surface is a difficult issue. In this article, requisite conditions for etching glass with a smooth surface and high mask selectivity have been discussed on the basis of the results of a comprehensive experimental study of the effects of substrate bias power and Ar addition on the removal of involatile fluoride residues deposited via the backscattering of etch products in the vicinity of the substrate surface. Under optimized etching conditions, deep trench etching of borosilicate glass to 32 μm depth and 15 μm width has been accomplished using 3-μm-thick chrome metal masks.
Non-traditional technologies for microfabrication
Although silicon planar technology has generated the field of micromechanics, it has been realized that this technology has intrinsic limitations for the fabrication of truly so micromechanisms. A number of alternative technologies based either on silicon or on different materials are presently investigated in order to overcome the limitations of planar silicon technology. This paper outlines the motivations for developing new microfabrication technologies, especially those that are considered as 'non-traditional' in the microelectronics domain, and the perspectives offered by this approach for fabricating miniature, micro and nanodevices. Four representative 'non-traditional' technologies are considered. LIGA process, micro electro-discharge machining (EDM), micro stereo lithography, and the combination of biological and artificial microfabricated structures ('hybrid' technologies).