Shinsuke Matsui

Low-loss in-line microfilter fabricated by precision trench machining

A machining technique has been developed that enables a narrow, smooth damage-free walled trench to be cut into an optical fiber engraved in a silica substrate by using a fine silica powder effect. This technique allows a very low insertion loss (0.21 dB) in-line microfilter to be made by inserting a thin filter plate into a trench cut into an optical fiber already fixed to a substrate.

Clamping Characteristics of Pin-type Vacuum Chuck. (2nd Report). Reducing the Influence of Back-surface Waviness on Wafer Flatess.

Fabrication of ULSI devices requires a 12-in. silicon wafer to have a site flatness better than 0.1 μm /30 mm. Vacuum pin chucks have been developed for flattening processed wafers. This paper describes to reduce the influence of the back-surface waviness on wafer flatness resulting from vacuum clamping. It was found that the contact ratio between the back-surface and the pin tops decreases with an increase in pin pitch or waviness, which degrades wafer flatness. Reducing the vacuum pressure improves flatness only slightly, but polishing for a short time produced good results. It is also shown that flatness better than 0.05μm/30 mm is obtained by reducing the waviness to better than 0.1μm /30 mm in clamping a 775 -μm-thick silicon wafer.