Fabrication of PIN diode detectors on thinned silicon wafers

Thin substrates are one of the possible choices to provide radiation hard detectors for future high-energy physics experiments. Among the advantages of thin detectors are the low full depletion voltage , even after high particle fluences, the improvement of the tracking precision and momentum resolution and the reduced material budget. In the framework of the CERN RD50 Collaboration, we have developed p-n diode detectors on membranes obtained by locally thinning the silicon substrate by means of tetra-methyl ammonium hydroxide etching from the wafer backside. Diodes of different shapes and sizes have been fabricated on 57 and 99 um thick membranes. They have been tested, showing a very low leakage current (< 0.4 nA/cm2 ) and, as expected, a very low depletion voltage (< 1V for the 57 um membrane).The paper describes the technological approach used for devices fabrication and reports selected results from the electrical characterization.