The CiS Forschungsinstitut fuer Mikrosensorik is engaged in developments of radiation detector technologies on several different fields. Current projects are dealing with large area thinned sensors, active edge sensors and 3D-sensors.
The challenge of producing cost-efficient, thin and large-sized sensors for High Energy Physics experiments is approached by a wet etching technology. Cavities are etched with KOH to the sensors’ back side to reduce their thickness to the order of 150…50 µm. The technology was successfully applied on single-sided processes on 4” and 6” wafers. It is now transferred to a double-sided process which makes high demands on the wafer process, especially the photolithography. Further focus is set on the thickness homogeneity and very shallow doping profiles. One goal is to realize a thin, double-sided Delta-E strip sensor for an upgraded TRex detector (Miniball experiment at ISOLDE).
In order to reduce the inactive area of planar sensors to a minimum, an active edge technology can be used. A corresponding pixel sensor run was finished successfully. It showed that the vertical DRIE trenches worked in combination with different side wall doping methods. N- and p-substrates with two wafer thicknesses have been produced. A good yield was achieved for sensors with inactive edges down to 50 µm. The experiences gained within this run are currently used to develop two different 3D-sensor processes.