Leakage current and threshold voltage alteration due to X-rays and proton beam in nMOSFETs with different geometries.
M. A. Silveira 1*, R. B. Santos 1, K. H. Cirne 1,2, J. A. De Lima 2, L. E. Seixas 2, S. P. Gimenez 1, N. H. Medina 3, N. Added 3, M. H. Tabacniks 3
1 Departamento de Física, Centro Univeristário da FEI, São Bernardo do Campo, São Paulo, Brazil.
2 Centro de Tecnologia da Informação Renato Archer, Campinas, São Paulo, Brazil.
3 Instituto de Física da Unversidade de São Paulo, São Paulo, Brazil.
This study came from the need to meet cost and performance of electronic circuits in applications requiring high tolerance to radiation effects. The requirement of the community related to space programs, e.g., is one of the main factors responsible for frequent development of devices for emerging technologies, which have played an important role in meeting these needs [1,2]. With miniaturization techniques the electronic devices have become increasingly more sensitive to ionizing radiation since the ionizing dose effects depends strongly on the device geometries Exposing an electronic system to ionizing radiation may provoke a reduction of the integrated circuit lifetime. Thus, it is of fundamental importance ground tests based on Total Ionizing Dose (TID) effects and Displacement Damage (DD) due to irradiation with high energy protons to qualify electronic devices to be used in space environment. In this present work we have studied the radiation effects on the integrated circuits, particularly Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) electronic devices which currently have proved the most viable to be used commercially. Enclosed-layout Circular Gate Transistors (CGT) and Rectangular Gate Transistor (RGT) were exposed to radiation dose, while beam current and irradiation time were varied during the experiment. Details of the CGT development can be found elsewhere . The integrated circuits were exposed to 10 keV X-ray radiation and 2.6 MeV high energy proton beam. The total dose effects due to ionizing radiation in MOSFET devices can lead to trapping of charges in the oxide and at the interface SiO2/Si, which increases or decreases transistor's off-current and leakage currents and shifts the threshold voltage. The results presented here were collected to establish the sensitivity of the devices selected as good candidates for use in space environment. There is a possibility that the bird’s beak structure influence the charge trapping in the SiO2/Si interface of the Rectangular-Gate Transistor . Since the Enclosed-layout Circular Gate Transistor (CGT) do not have this region it was found no significant damage. These results show that after being irradiated by X-ray and high energy proton beams the CTG is more tolerant to radiation than the counterpart RGT.
. Duzellier, S.,“Radiation Effects on Electronic Devices in Space”, Aerospace Science and Technology 9, p. 93-99, 2005.
. Barnaby, H. J., “Total-Ionization-Dose Effects in Modern CMOS Technologies”, IEEE Trans. Nuclear Science, vol. 53, n. 6, December, 2006.
. Mavis, D. G. and Alexander, D. R., “Employing Radiation Hardness By Design Techniques with Commercial Integrated Circuit Processes”, 16th Digital Avionics Systems Conference, 1997, IAA/IEEE.
. De Lima, J.A. and Gimenez, S.P. - "A Novel Overlapping Circular-Gate Transistor and its Application to Power MOSFETs", ECS Transactions, 23 (1), p. 361-369, 2009.