Total dose and displacement damage effects in a radiation-hardened CMOS APS

Abstract

A 512 512 CMOS active pixel sensor (APS) was designed and fabricated in a standard 0.5-m technology. The radiation tolerance of the sensor has been evaluated with Co-60 and proton irradiation with proton energies ranging from 11.7 to 59 MeV. The most pronounced radiation effect is the increase of the dark current. However, the total ionizing dose-induced dark current increase is orders of magnitude smaller than in standard devices. It behaves logarithmically with dose and anneals at room temperature. The dark current increase due to proton displacement damage is explained in terms of the nonionizing energy loss of the protons. The fixed pattern noise does not increase with total ionizing dose. Responsivity changes are observed after Co-60 and proton irradiation, but a definitive cause has not yet been established.

Combined reactor neutron beam and 60Co γ-ray radiation effects on CMOS APS image sensors

“…This is mainly due to the buildup of trapped charge in the field-oxide of CMOS APS image sensors. 7 TID damage causes a buildup of trapped charge in the field-oxide of CMOS APS image sensors and of traps at the Si/SiO 2 interface. The creation of trapped charges in the field-oxide will increase the width of space charge region by changing the potential of the Si/SiO 2 interface, and this causes an increase of thermal generation which induces the dark signal increase.…”

“…[4][5][6][7][8][9] The different types of CMOS APS image sensors with different pixel architectures such as three-transistor active pixels (3T-pixels) and Pinned Photo Diodes (PPD) pixels, 4,5 and different process technology such as 0.7, 0.5, 0.35, 0.18 and 0.13-µm has been investigated by exposing to ionizing radiation. [6][7][8][9] Displacement damage caused by energetic particles such as neutrons or protons induces stable bulk traps with energy levels within the band-gap, which can lead to the performance degradation of CMOS APS image sensors. Displacement damage effects are also a key issue for solid state image sensors (Charge coupled device, CMOS APS) exposed to space radiation environments 6 or used in nuclear physics experiments.…”

TID effects in deep N-well CMOS monolithic active pixel sensors

“…5. The increase in leakage current with increasing total ionizing dose, almost two orders of magnitude at 1100 krad(SiO 2 ), may be ascribed to the buildup of holes in the field oxide which may extend the space charge region at the diode junction and increase the surface generation current [14]. Combined with the previous mechanism, the creation of trapping states at the Si/SiO 2 interface over the pn junction depletion region may account for a further increase of the surface generation phenomena [15].…”

“…The C ox,lat W lat,f product, where C ox,lat is the effective oxide capacitance of the parasitic STI sidewall transistor, can be extracted from static I D − V GS curves [20]. The results from the rad-hard characterization of 130 nm NMOSFETs with different gate dimensions and operated at different drain currents were used to extract the main parameters appearing in (14). The extracted values, which are shown in Table IV, led to the theoretical evaluation of the noise degradation in the preamplifier input device, shown in Fig.…”

Displacement damage effects on CMOS APS image sensors induced by neutron irradiation from a nuclear reactor

“…Many studies have already been dedicated to the ionizing effects on CMOS APS image sensors. [3][4][5][6][7][8][9][10] On the contrary, fewer studies focus on displacement damage effects on CMOS APS image sensors, which are a subject of ongoing research. 11,12 Displacement damage effects are a key issue for solid-state image sensors (CCD, CID, and CMOS APS) exposed to space radiation environments 13 or used in nuclear physics experiments.…”