FORCE is a Japan-US space-based astronomy mission for an X-ray imaging
spectroscopy in an energy range of 1--80 keV. The Wideband Hybrid X-ray Imager
(WHXI), which is the main focal plane detector, will use a hybrid semiconductor
imager stack composed of silicon and cadmium telluride (CdTe). The silicon
imager will be a certain type of the silicon-on-insulator (SOI) pixel sensor,
named the X-ray pixel (XRPIX) series. Since the sensor has a small pixel size
(30--36 $\mu$m) and a thick sensitive region (300--500 $\mu$m), understanding
the detector response is not trivial and is important in order to optimize the
camera design and to evaluate the scientific capabilities.
We have developed a framework to simulate observations of celestial sources
with semiconductor sensors. Our simulation framework was tested and validated
by comparing our simulation results to laboratory measurements using the XRPIX
6H sensor. The simulator well reproduced the measurement results with
reasonable physical parameters of the sensor including an electric field
structure, a Coulomb repulsion effect on the carrier diffusion, and arrangement
of the degraded regions. This framework is also applicable to future XRPIX
updates including the one which will be part of the WHXI, as well as various
types of semiconductor sensors.