INTEGRATION OF CMOS-ELECTRONICS AND PARTICLE DETECTOR DIODES IN HIGH-RESISTIVITY SILICON-ON-INSULATOR WAFERS

A new approach to monolithic pixel detectors, based on SOI wafers with high resistivity substrate, is being pursued by the CERN RD19 collaboration. This paper reports on the used fabrication methods, and on the results of the electrical evaluation of the SOI - MOSFET devices and of the detector structures fabricated in the bulk. The leakage current of the high-resistivity PIN-diodes was kept in the order of 5 to 10 nA/cm2. The SOI preparation processes considered (SIMOX and ZMR) produced working electronic circuits and appear to be compatible with the fabrication of detectors of suitable quality

A 1006 ELEMENT HYBRID SILICON PIXEL DETECTOR WITH STROBED BINARY OUTPUT

An asynchronous version of a binary pixel readabout circuit has been implemented in an array with 16 columns at 500 mu m pitch and 63 rows at 75 mu m pitch. This readabout chip has been bonded with solder bumps to a silicon detector with matching pixel elements. Event information in a pixel can be strobed into a local memory by a trigger signal and subsequently read out. Without a strobe the information is continuously cleared. The complete hybrid detector has been successfully tested with ionizing particles from a radioactive source. Three such devices have been put in the CERN heavy-ion experiment WA94 in the Omega spectrometer, where they recorded particle tracks from high-multiplicity /sup 32/S interactions. Preliminary data indicate a noise of approximately 60 e/sup -/ and a threshold spread of approximately 500 e/sup -/. The timing characteristics are adequate for a fixed-target experiment.<

Radiation tolerance of single sided silicon microstrips

The RD20 collaboration is investigating the design and operation of an LHC inner tracking detector based on silicon microstrips. Measurements have been made on prototype detectors after irradiation with electrons, neutrons, photons, and protons for doses up to 5 Mrad and fluences up to 10(15) particles/cm(2). The annealing of effective doping changes caused by high neutron fluences, one of the major limits to detector lifetime at the LHC, is shown to be strongly inhibited by cooling below room temperature. Detailed results are presented on the critical issue of microstrip capacitance. We have also investigated bulk damage caused by high-energy protons, interstrip isolation after neutron irradiation, and MOS capacitors irradiated with electrons and photons

DEVELOPMENT OF SILICON MICROPATTERN PIXEL DETECTORS

Successive versions of high speed, active silicon pixel detectors with integrated readout electronics have been developed for particle physics experiments using monolithic and hybrid technologies. Various matrices with binary output as well as a linear detector with analog output have been made. The hybrid binary matrix with 1024 cells (dimension 75 mum x 500 mum) can capture events at approximately 5 MHz and a selected event can then be read out in < 10 mus. In different beam tests at CERN a precision of 25 mum has been achieved and the efficiency was better than 99.2%. Detector thicknesses of 300 mum and 150 mum of silicon have been used. In a test with a Cd-109 source a noise level of 170 e- r.m.s. (1.4 keV fwhm) has been measured with a threshold non-uniformity of 750 e- r.m.s. Objectives of the development work are the increase of the size of detecting area without loss of efficiency, the design of an appropriate readout architecture for collider operation, the reduction of material thickness in the detector, understanding of the threshold non-uniformity, study of the sensitivity of the pixel matrices to light and low energy electrons for scintillating fiber detector readout and last but not least, the optimization of cost and yield of the pixel detectors in production