M.Sc Thesis

M.Sc StudentGutman Zivit
SubjectStudy of CMOS-SOI-MEMS Transistors and Systems
DepartmentDepartment of Electrical and Computer Engineering
Supervisor PROFESSOR EMERITUS Yael Nemirovsky


Recent years have seen a progressively increasing interest in the field of Infra-Red (IR) uncooled detectors, mainly because they do not require cryogenic cooling thus achieving significantly reduced complexity and cost.  Uncooled detectors, also called thermal sensors, are based on the conversion of heat, generated by the absorbed radiation, into an electrical signal.

This work describes a novel type of IR uncooled detectors, the TMOS, which is based on a P type Metal-Oxide-Silicon (MOS) transistor, fabricated using standard CMOS processes. The transistor is thermally isolated from its surroundings, and changes its electrical properties as its temperature changes.

The TMOS is made possible due to the tremendous advances achieved in two key technologies, namely Silicon On Insulator (SOI) and Micro Electrical Mechanical System (MEMS).

This thesis describes the properties of the TMOS detector, and reviews the different technological and theoretical concepts which are crucial to its understanding. In addition, a comprehensive electrical and electro-optical characterization is performed on several fabricated configurations. In addition, thermal modeling of the device and the main thermal properties, such as thermal conductance and capacitance, are modeled.  

Operation of the TMOS sensor is both theoretically analyzed and experimentally verified showing that performance of the TMOS is optimal when the device operates in the sub-threshold region. In this region, the TMOS has a very large temperature dependence, which is described by a figure of merit, the Temperature Coefficient of Current (TCC). Specifically a TCC of 4%/K was achieved, compared to a TCC of only 2%/K achievable in the microbolometer array.

In summary, both theoretical analysis and the experimental results clearly show that the TMOS has very promising potential as an IR uncooled detector.