We propose a simple method to fabricate SiO 2 diaphragms supported on a Si substrate by using the inward plasma etching. In this method, a Si substrate covered with SiO 2 was locally etched with the inward plasma from the Si side. When using a SiO 2 (280 nm)/Si (380 mm) substrate, a SiO 2 diaphragm with a diameter of ～50 mm was fabricated at the bottom of the bowl-like hole with an opening diameter of ～1.2 mm. This method does not require lithographic processes which are inevitable for the conventional microfabrication techniques and may be used to fabricate MEMS devices in the lab. . は じ め に

Inward-type plasmas, which spread upstream against the gas flow in the capillary tube where the gas is discharged, can react with samples placed near the entrance of such a capillary tube. In this study, surface modification of polymer surfaces is conducted using inward plasma. The modification is also done by conventional microplasma jet, and the modified surfaces with two plasma techniques are characterized by contact angle measurement, X-ray photoemission spectroscopy (XPS), and atomic force microscopy (AFM). Although inward-plasma-treated surfaces are less hydrophilic than conventional plasma-treated ones, they are still sufficiently hydrophilic for surface coatings. In addition, it turns out that the polymer surfaces irradiated with the inward plasma yield much smoother surfaces than those treated with the conventional plasma jet. Thus, the inward plasma treatment is a viable technique when the surface flatness is crucial, such as for the surface coating of plastic lenses.