A gate structure is formed on a semiconductor. A pair of memory cells sharing a bit-line contact include a first capacitor below the substrate surface. The plurality of teeth are arranged in rows and columns that define a plurality of longitudinal and latitudinal arcuate channels along the curved surface. In use, there is a step for judging a reflected pulsed laser beam from the reflection sector by detecting a level of light quantity, a step for determining a center position of the reflection sector based on the result of the judgment, and a step for calibrating the laser scanner measuring system based on the determined center position and on the known position. Accordingly, a current is supplied to each current supply line from both the first and the second current input terminals.