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 reactive ion etching of Pyrex glass using SF6 plasma
Abstract Deep reactive ion etching of Pyrex glass has been characterized in sulfur hexafluoride plasma (SF6). High etch rate (∼0.6 μm/min) was demonstrated under a condition of low pressure (0.2 Pa) and high self-bias (−390 V) by using a magnetically enhanced inductively coupled plasma reactive ion etching. Vertical etch profile (taper angle ∼88°), high aspect ratio (>10) and through-wafer etching of Pyrex glass (200 μm in thickness) were achieved under the condition by using thick (20 μm) and vertical electroplated nickel film as mask. The vertical etch profile was achieved when the mask opening is narrower than 20 μm because the deposition of nonvolatile product on the sidewall is reduced. A novel etching technique “scoop-out etching” was demonstrated by using the present etching characteristics.
Plasma Production Using Energetic Meandering Electrons
When an electron is accelerated by an oscillating electric field in an inhomogeneous magnetic field which has a null point, it meanders along a chaotic orbit. The kinetic energy becomes larger than that of regular motion in an off-resonant homogeneous magnetic field. This effect explains the high efficiency of plasma production in the neutral line discharge (NLD).