I apologize I have not finished the manuscript. If you allow more delay, I will submit the paper by the end of 2019.


SOI is a CMOS LSI technology in which each MOSFET is separated by using a thin oxide layer in the silicon wafer, allowing high-performance CMOS circuit because of the low parasitic capacitance.
The SOI pixel sensor utilizes the silicon wafer as the radiation sensor.
Thanks to the small detector capacitance and the industry-standard CMOS technology, high-performance pixel sensors can be developed. In recent high-luminosity collider experiments, huge number of signal and background tracks enter the pixel detector.
We have to implement a complex circuit in each pixel to reduce the hits to be read out.
There is also demands to keep the small pixel size from the physics view point.
A solution to this issue is the 3D integration of readout chip, where,
the additional CMOS circuit is integrated to the sensor chip, and the circuit nodes are
connected pixel by pixel.
With this technology, the functions of each pixel can be improved significantly.
The first SOI pixel sensor with 3D integration was submitted in 2018 and the evaluation
of the chip are in progress.
In this presentation, the 3D integration technology for the pixel sensors is reviewed briefly.
Then the R\&D status of the SOI 3D pixel sensor will be discussed.