Total Ionizing Dose Radiation-Induced Dark Current Random Telegraph Signal in Pinned Photodiode CMOS Image Sensors

Abstract

In this work, several studies on Total Ionizing Dose effects on Pinned Photodiode CMOS images sensors are presented. More precisely, the evolution of a parasitic signal called Random Telegraph Signal is analysed through several photodiode designs. It is shown that the population of pixels exhibiting this fluctuation depends on the design variants. This population also increases in a different way with the dose: the effects are not same considering a low or high X-rays irradiation. Moreover, a statistical analysis is realized in order to better caracterize the defects responsible for RTS. It turns out that electric field enhancement signature can appear in some specific cases.

Radiation-Induced Variable Retention Time in Dynamic Random Access Memories

“…Compared to the radiation induced DC-RTS literature, those time constant activation energies are also lower than the range reported in [15] and [28] (i.e. between 0.55 and 0.9 eV) but they are in good agreement with the time constant distribution shown in [29] and with the range reported in [30] (0.36-0.54 eV).…”

“…It suggests that the storage PN junction of the 2 GB cell has a larger sensitive depletion volume or more intense electric fields than its 4 GB counterpart. Overall, the fact that TID generates VRT cells is in very good agreement with the behavior of DC-RTS centers in image sensors where it has been clearly demonstrated that ionizing radiation generates a large number of metastable generation centers at the various CMOS Si/SiO2 interfaces [16], [20].…”

“…In this case the charge state fluctuation of the modulator G-R center between the emission of a hole and an electron would explain the generation current discrete fluctuations of the nearby fast G-R center. Such mechanism seems possible but disagrees with some experimental observations such as the fact that increasing the electric field magnitude enhances the RTS center generation rate but not its time constant (which depends on the modulator generation rate that should also be enhanced by the electric field) as can be seen in [29] (Fig. 15), in [37] (Fig.…”

“…Regarding the location of those DC-RTS centers, it has been clearly established that they can originate from any Si/SiO 2 interfaces (gate oxide, pre-metal-dielectric interface, gate oxide...) in unirradiated sensors [42] and that bulk DC-RTS centers are nonexistent (or extremely rare) in unirradiated sensors [43]. In CIS exposed to TID, all Si/SiO 2 interfaces surrounding the photodiode have been identified as possible source of DC-RTS centers [16], [29]. Finally, after a displacement damage irradiation, it is well known that DC-RTS is caused by bulk defects in CCDs [15] as well as in CISs [17] and in any kind of silicon device.…”

Random Telegraph Noises from the Source Follower, the Photodiode Dark Current, and the Gate-Induced Sense Node Leakage in CMOS Image Sensors

“…The general effects of radiation damage on CIS and the design of radiation-hard CIS are outside the scope of this work [25][26][27][28][29][30][31][32]. Instead, X-ray irradiation is utilized as a tool to alter the composition of RTN types and to increase the number of RTN pixels for investigation.…”