Limits in point to point resolution of MOS (Metal-Oxide-Semiconductor) based pixels detector arrays

Abstract

In high energy physics point to point resolution is a key prerequisite for particle detector pixel arrays. Current and future experiments require the development of inner-detectors able to resolve the tracks of particles down to the micron range. Present-day technologies, although not fully implemented in actual detectors can reach a 5 micometer limit, based on statistical measurements, with a pixel-pitch in the 10 micrometer range. Attempts to design small pixels based on SOI (Silicon On Insulator) technology will be briefly recalled here. This paper is devoted to the evaluation of the building blocks with regard to their use in pixel arrays for the accurate tracking of the charged particles. We will make here a simulations based quantitative evaluation of the physical limits in the pixel size. A design based on CMOS (Complementary Metal-Oxide-Semiconductor) compatible technologies that allows a reduction of the pixel size down to the sub-micronmeter range is introduced. Its physical principle relies on a buried carrier-localizing collecting gate. The fabrication process needed by this pixel design can be based on existing process steps used in silicon microelectronics. The pixel characteristics will be discussed as well as the design of pixel arrays. The existing bottlenecks and how to overcome them will be discussed in the light of recent ion implantation and material characterization.