| AVS 64th International Symposium & Exhibition | |
| Electronic Materials and Photonics Division | Thursday Sessions |
| Session EM-ThP |
| Session: | Electronic Materials and Photonics Poster Session |
| Presenter: | Panpan Xue, University of Wisconsin-Madison |
| Authors: | P. Xue, University of Wisconsin-Madison Z. Wang, Stanford University T. Chang, University of Wisconsin-Madison Y. Nishi, Stanford University J.L. Shohet, University of Wisconsin-Madison |
| Correspondent: | Click to Email |
Hafnium oxide(HfO2) is one of the most popular dielectric materials for RRAM. Changes of the defect concentrations of HfO2 may affect the resistive-switching mechanism of RRAM. In this work, in order to investigate the effects of proton radiation, (1) atomic-layer-deposited (ALD) HfO2 blanket films deposited on a Si substrate and (2) HfO2 base RRAM were exposed to proton. After exposure, electron spin resonance and FTIR measurements were made on the HfO2 blanket film, forming voltage and I-V characteristics were measured on the RRAM cell. The samples were exposed to proton radiation with a range of energies from 10 to 300keV. H ion implantation was used as the proton source. ESR measurements showed that after 300keV proton exposure, the defect concentration of Si dangling bond increased. Besides, all of the fresh pristine RRAM cells need to be formed, the forming voltage is approximately 3.4 ~ 3.65V. However, a number of the low-energy proton-exposed samples are set after exposure: about 50% of the 10keV proton exposed RRAM samples are set to the “on” state after irradiation. The 300keV proton-exposed RRAM samples were not formed or set after proton exposure, but the needed forming voltage decreased and breakdown occurred at a lower voltage. This is consistent to a TRIM simulation result, after low energy exposure, some of the H ions are seen to stay in the HfO2 films and generate conductive filaments that set the dielectric film to the low resistance state. However, 300keV protons have just enough energy to pass through the dielectric film. In addition, the high-resistance state (HRS) current of just-formed 300keV exposed RRAM is about 100 times higher than that for pristine RRAM. We conclude low-energy protons have a significant effect on the forming process of RRAM. However, higher-energy protons change the resistance of the HRS instead.
This work was supported by the Semiconductor Research Corporation under Contract 2012-KJ-2359