  We present the development status of the SOIKID, a detector combining the SOI
pixel detector and the superconducting detector KID (Kinetic Inductance
Detector). The aim of the SOIKID is to measure X-ray photon energy with the
resolution better than that of the semiconductor detector. The silicon
substrate is used as the X-ray photon absorber. The recoiled electron creates
athermal phonons as well as the ionizing electron-hole pairs. The KID formed at
one side of the substrate surface detects the phonons to measure the total
energy deposited, while the SOI pixel detector formed on the other side of the
substrate detects the ionized carries to measure the position. Combining the
position and energy measurements, it is in principle possible to have the
extremely high energy resolution.
