Speaker
Mr
Laurent Artola
(ONERA)
Description
**1. Introduction**
Image sensors are widely used in spacecraft for many applications [1] [2]. Photonic imager technology has been developed for wavelength responses that range from ultraviolet, through visible, to infrared. Most radiation effects studies have been made on infrared detectors, and visible/near infrared technologies such as charge coupled device (CCD), charge injection devices (CID) and active pixel sensors (APS). Among many optical applications, like earth or space observation, the guidance system in a spacecraft (launcher or satellite) is particularly critical. Then, the reliability of such guidance systems based on image sensors is essential for the space mission.
CMOS technology is mainly used in the readout circuit of photonic integrated circuits (ICs). However, CMOS technology is known to be sensitive to single event effects (SEE), such as single event transient (SET) [2]. SETs can be induced by various ionizing particles, i.e., heavy ions, protons, electrons the space radiation environment [3]. SETs can become critical for image devices and ICs boarded in flight because of their critical applications.
One of the interests of prediction tools, such as MUSCA SEP3 (MUti-SCAle Single Event Phenomena Prediction Platform) [4-5], is to anticipate the sensitivity trends with the aim to help the designers to select the best layout considering of performances and reliability. Moreover, these investigations lead to reduce the number of testing runs during the qualifications of electronics under high energy particles such as heavy ions.
In this work is presented in interest of such approach to understand the failure origins at transistor level with the aim to be able to harden circuits of the readout system of photonic device. This work is focus on infrared (IR) device, designed by Sofradir. Therefore, specificity of cryogenic temperatures, down to 77 K, will be considered, especially in the final paper. These temperatures are used with the aim to reduce the dark current and to increase in performances of the device.
**2. SEE prediction tool**
MUSCA SEP3 is a SEE prediction tool based on a Monte-Carlo approach which allows a complete simulation from the interaction of the radiation particles with the matter to the occurrence of the soft error in the IC. These simulations uses nuclear database and take into account the dynamic transport and charge collection mechanisms, bipolar amplification, the bias voltage, the layout, and the fabrication process with the aim to build a SET database. The modeling of the Front-End Of Line (FEOL) is based on the description (dimensions and locations) of implants, i.e., drain and source of each n-MOS and p-MOS transistor directly extracted from GDS files. All required layout files and electrical models were provided by Sofradir. Next this SET database is injected on each node at transistor level for an electrical simulation with Spectre simulator with the aim to estimate the soft error response of the circuit. The complete principle of the modeling is reported in previous works [4-5], but all the details of the simulation flow will be presented in the final paper.
The comparisons of experimental data and MUSCA SEP3 calculations at 300 K have been performed for 2 designs of DFF used in the readout circuit. Good correlations in terms of LET threshold and SEE saturation of cross section are proposed. More details will be presented and discussed in the final paper.
**3. Failure analysis**
These failure analyses based on sensitivity mappings can be really useful for designers in order to determine which transistors of the cell are critical and to anticipate design optimizations. In previous work [6], MUSCA SEP3 had already shown the relevance of the estimated critical areas.
The simulation results highlight that the transistors of the input of the cell are more sensitive than the transistor of the output of the flip-flop cell. It is interesting to note that even if the global SEE cross section is quite equivalent for the two bias condition of the circuit, i.e., state “1” and state “0” saved in the DFF, the locations of critical areas are strongly different. This point will be illustrated and developed in the final paper.
Based on this failure analysis it is possible to propose hardening techniques by design with the aim to reduce the SEE sensitivity of such circuits. This point will be fully illustrated in the final paper.
**4. Conclusion and perspectives**
This work presents an SEE prediction tool and its interest in failure investigations and in providing a help for designers with the aim to optimize the SEE sensitivity of Sofradir readout circuit. Estimations and a failure analysis at circuit level were presented considering the stored data configuration. Comparisons between predictions and experimental data obtained under heavy ion are consistent. In the final paper, complementary analyses and hardening techniques will be presented
**References**
[1] G. R. Hopkinson, IEEE Trans. Nucl. Sci., vol. 47, no, 6, pp. 2480-2484, Dec. 2000.
[2] C. Virmontois, et al, IEEE Trans. Nucl. Sci., vol. 61, no. 6, pp. 3331-3340, Dec. 2014.
[3] D. Falguere, et al, IEEE Trans. Nucl. Sci., vol. 49, no. 6, pp.2782-2887, Dec. 2002.
[4] G. Hubert, et al, IEEE Trans. Nucl. Sci., vol. 56, no. 6, pp. 3032-3042, Dec. 2009.
[5] G. Hubert, et al, IEEE Trans. Nucl. Sci., vol. 60, no. 6, pp. 4421-4429, Dec. 2013.
[6] G. Hubert, et al, IEEE Trans. Nucl. Sci., vol. 61, no. 6, pp. 3178-3186, Dec. 2014.
Summary
This work presents an SEE prediction tool called MUSCA SEP3 and its interest in failure investigations and in providing a help for designers with the aim to optimize the SEE sensitivity of Sofradir readout circuit. Estimations and a failure analysis at circuit level were presented. Comparisons between predictions and experimental data obtained under heavy ion are consistent. In the final paper, complementary analyses and hardening techniques will be presented.
Primary author
Mr
Laurent Artola
(ONERA)
Co-authors
Mr
Franck Perrier
(Sofradir)
Mr
Guillaume Hubert
(ONERA)
Mr
Nicolas Ricard
(Sofradir)
Mr
Samuel Ducret
(Sofradir)
