A tool for machining bore surfaces having at least four cutting edges in respective pairs, one pair of cutting edges are arranged so as to be offset from one another as viewed in the axial direction of the tool, one pair may be diametrically opposed and another pair may be diametrically offset and not diametrically opposed. Fully saturating the water with excess oxygen and injecting this high-pressure mixture into a blender have a lower pressure atmosphere to produce a plurality of micro-bubbles known as white-water. Through automatic generation of the test structures and automatic wiring, the present invention greatly shortens the design cycle of test chips for target transistor testing, and greatly reduces the error probability in the process of designing test chips for target transistor testing, and improves the testing relevancy. An anchor portion for mounting the diaphragm on the silicon substrate is provided between the diaphragm and the silicon substrate in a manner surrounding circumferentially an opening end of the through hole located at the side facing the first main surface.