An object is to suppress occurrence of oxygen deficiency. The disk has a circumferential index and a band of servo reference tracks. A semiconductor device including a layer of the passivating coupling material, and a method of manufacturing such a semiconductor device are also contemplated. The right and left agitator chambers also each have a rearward or rear suction duct adjacent the rear edges of the respective agitator chambers. The above-described second electrode is formed in a rectangular shape, and at least one of the above-described first electrode and the above-described second electrode is a reflecting electrode that causes incident light coming from a direction of the above-described first substrate. The display is coupled to the contrast control voltage and has a variable contrast ratio, wherein the variable contrast ratio of the display is controlled by the contrast control voltage.