As a radiation detector for use in a CT sensor, etc., there is a detector of an arrangement wherein a scintillator is disposed on a light-incident surface of a semiconductor photodetecting element, which is a semiconductor element. With such a radiation detector, when an X-ray, γ-ray, charged particle beam or other radiation to be detected is made incident on the scintillator, scintillation light is generated inside the scintillator by the radiation. The semiconductor photodetecting element then detects the scintillation light that is made incident from the scintillator and output an electrical signal that is in accordance with the intensity of the radiation.
Also, in order to carry out signal processing of the electrical signal output from the semiconductor photodetecting element, a signal processing element is provided. As an arrangement for electrically connecting the semiconductor element with the signal processing element and transmitting the electrical signal, an arrangement is used wherein a semiconductor device is arranged in one united body by connecting the semiconductor element to a wiring substrate that is provided with a conduction path and the signal processing element is connected to the wiring substrate of this semiconductor device. Such a semiconductor device using a wiring substrate is used in various applications besides radiation detectors (see for example, Japanese Patent No. 2555720 and Japanese Patent Application Laid-Open No. H3-203341).