AVS 63rd International Symposium & Exhibition
    Electronic Materials and Photonics Thursday Sessions
       Session EM-ThP

Paper EM-ThP6
Proton-Induced Effects on HfOx-Based Resistive Random Access Memory

Thursday, November 10, 2016, 6:00 pm, Room Hall D

Session: EMPD Poster Session
Presenter: J. Leon Shohet, University of Wisconsin-Madison
Authors: K. Hsu, University of Wisconsin-Madison
T. Chang, University of Wisconsin-Madison
L. Zhao, Stanford University
Z. Wang, Stanford University
R. Agasie, University of Wisconsin-Madison
T. Betthauser, University of Wisconsin-Madison
J. Nickles, University of Wisconsin-Madison
J. Chang, University of Wisconsin-Madison
Y. Nishi, Stanford University
Z. Ma, University of Wisconsin-Madison
J.L. Shohet, University of Wisconsin-Madison
Correspondent: Click to Email
Resistive Random Access Memory (RRAM) [1], is considered to be a very promising memory technology. As RRAM technology matures and electronic devices using RRAM are likely to be built soon, malfunctions of RRAM caused by radiation will become an important problem in industry since the size of these devices will continue to decrease. The goal of this work is the measurement of proton-induced effects on HfOx RRAM cells. Proton irradiation in the MeV range of energies were initially chosen since most cosmic-ray protons are in this range. However, protons lose energy when they pass through matter and thus, lower-energy protons were also investigated. According to TRIM code calculations, there is more interaction between protons and HfOx films when the proton energy decreased to several keV.

Two proton fluences were chosen (~2 × 1015cm-2 and ~2 × 1014cm-2).The proton-induced effects on HfOx RR AM cell include forming rate, modification to forming voltage, resistance of high resistance state (HRS) and shifts in set/reset voltage. After proton irradiation, no RRAM cells were formed and ended up in the low resistance state (LRS) and no changes were observed in the forming voltage of irradiated RRAM cells even when exposed to very high fluence(~2 × 1015cm-2).

An increase in the resistance of HRS was observed in proton-irradiated RRAM cells. RRAM cells irradiated with 60 keV protons have a higher increase in their HRS state than RRAM cells irradiated with 5 MeV protons. The shift in values of the set voltage can be seen on the I-V characteristic of the proton-irradiated RRAM cell. It is very likely that there is an annealing process occurs and it might be a result of defect reordering after proton irradiation.

The shift in set voltage after 5 MeV proton irradiation (fuence ~2 × 1015cm-2) is from 3.5 V to 7 V. The shift in set voltage after 60 keV proton irradiation (fluence ~2 × 1015cm-2) is from 3.5 to 11 V. Such shifts of set voltages may create problems in real device applications. These shifts a likely to be be attributed to atomic-structure changes in HfOx caused by proton irradiation.

This work was supported by the Semiconductor Research Corporation under Contract No. 2012-KJ-2359, by the National Science Foundation under Grant No. CBET-1066231.

Reference:

[1] H.-S. Philip Wong, H-Y Lee, S. Yu, Y. S. Chen, Y. Wu, P-S Chen, B. Lee, F. T. Chen, and M-J Tsai, “Metal–oxide RRAM,” Proceedings of the IEEE 100 1951 (2012).