The present invention provides a new method for the in situ generation of chlorine dioxide from a solution of sodium chlorite and carbon dioxide. A passage unit includes manifold plates, and a damper plate which is stacked on the manifold plates and has a damper wall facing a common liquid chamber. The method facilitates formation of FinFET devices with improved and reproducible fin height control while providing isolation between source and drain regions of the FinFET device. Also, an IC may be modified multiple times by simply reprogramming the device. The door includes a recessed portion including a retainer, and the diffusion lens is supported in the recessed portion with the retainer pressing an external surface of the diffusion lens entirely so that the light from the light source is prevented from leaking from the surface of the door. The circuit may include an adjustable current generator driven by a signal representing the number of phase circuits through which the current flows and configured to generate a current proportional to the number of phase circuits through which the current flows, and a tank capacitor charged by the adjustable current generator.