Abstract: A photodiode array includes an insulating film; a semiconductor layer of a first conductivity type provided on the insulating film; a positive electrode and negative electrode formed on the semiconductor layer; and a plurality of pn junctions formed in series in the semiconductor layer between the positive and negative electrodes. The pn junctions are formed by a diffusion layer of a second conductivity type formed in the semiconductor layer and another diffusion layer of the first conductivity type formed in the diffusion layer, so as to terminate on the insulating film.

Abstract: A photodiode array is provided which includes a cell comprised of at least a substrate, an insulating film formed on the substrate, a semiconductor layer containing an impurity of first conductivity type and provided on the insulating film, an impurity-diffusion layer of second conductivity type formed in the semiconductor layer and reaching the insulating film, and at least one impurity-diffusion layer of the first conductivity type formed within the impurity-diffusion layer of the second conductivity type and reaching the insulating film, wherein pn junctions are defined between the layers of opposite conductivity types and arranged laterally, and of the pn junctions, any pn junction of a predetermined order are connected to each other in series. By virtue of this arrangement, the area of pn junctions per unit area of a substrate is increased thereby contributing to a reduction in chip size and in production cost.

Abstract: A method for producing a semiconductor device, is composed of steps of: covering a lower side of a semiconductor wafer with a heavy metal and disposing the semiconductor wafer in a chamber; causing the heavy metal to diffuse into the semiconductor wafer by heating the semiconductor wafer with a heat source having a small thermal capacity; and thereafter, ceasing to heat with the heat source, then charging the chamber with a cooling gas.