Influence of gamma irradiation on silicon nitride mis capacitors and radiation hardness


Yilmaz E., TUĞAY E., Aktaga A., Turanc R.

1st International Conference on Radiation and Dosimetry in Various Fields of Research, RAD 2012, Nis, Serbia, 25 - 27 April 2012, vol.2012-April, pp.23-26 identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 2012-April
  • City: Nis
  • Country: Serbia
  • Page Numbers: pp.23-26
  • Keywords: C-V Characterization, Gamma Radiation, PECVD, Silicon Nitride
  • Recep Tayyip Erdoğan University Affiliated: Yes

Abstract

SiNx thin films with thickness of 100 nm were deposited on p-type (100) silicon wafer by using plasmaenhanced chemical vapor deposition (PECVD) method. After deposition the samples annealed at 500 and 700 °C for 1h at N2 ambient. The chemical bonds and their densities inside the films were investigated by Fourier transform infrared (FTIR) spectroscopy. The as-deposited and annealed samples with Al/SiNx/Si structure as metal-insulatorsemiconductor (MIS) capacitors were exposed to a 60-Co gamma radiation source with a dose rate of 0.015 Gray/S. Capacitance-voltage (CV) measurements were performed for frequencies of 10, 100 and 1000 kHz before and after radiation exposure with doses of up to 40 Gray. It was found that before gamma irradiation compared with asdeposited sample, the annealed samples exhibit less negative flatband voltages (Vfb) shift indicating the relative reduction in positive charge in the SiNx:H samples. After gamma irradiation for all samples a negative shift has been observed in Vfb, being more pronounced in the samples annealed at higher annealing temperature of 700 °C. The more strike feature is that the amount of shift does not change by increasing radiation dose after first irradiation, in which we attributed to the radiation hardening in Al/SiNx/Si MIS capacitors which can be used in space and nuclear applications as a radiation hardened device.