· 112 · IMP & HIRFL Annual Report 2017

by different ion irradiation values is shown in Fig. 2(a). Here, only the SFTs whose sizes are larger than 2 nm

are taken into account. The size distribution of produced SFTs varies under different irradiation conditions. It

is concluded that the most probable distribution in size of SFTs is increased from 2.5 to 4 nm when increasing

the nuclear stopping power of incident ions according to Table 1, and the average size of all the statistic SFTs is

positively related to the nuclear stopping power. For the higher nuclear stopping power, a heavy ion impact can

deposit more energy in the displacement collision cascade, which may result in the larger SFTs.

Fig. 2 Size distribution of SFTs in gold nanowires. (a) The fraction of different SFT; (b) The relationship between average

size of SFT and nuclear energy loss.

In conclusion, MeV energy heavy ion irradiation modified structure of gold nanowire, and produced defect

cluster which is called stacking fault tetrahedron. According to our study, SFTs in gold nanowire can free-standing

or gather together to form a SFT group. Those SFTs were generated by different kind of incident ion have a

distinguishing size distribution, this phenomenon may ascribe to the distinct nuclear energy loss of these incident

heavy ions in gold nanowire.

References

[1] J. Silcox, P. B. Hirsch, Philos. Mag., 4(1959)72.

[2] E. Figueroa, D. Tramontina, G. Gutierrez, et al., J. Nucl. Mater., 467(2015) 677.

[3] S. Kojima, Y. Satoh, H. Taoka, et al., Philos. Mag. A, 59(1989)519.

4 - 19 Radiation Damage in Hafnium Oxide Based MOS Capacitors

Induced by Energetic Ions

Li Zongzhen, Liu Jie, Zhai Pengfei, Liu Tianqi, Yao Huijun, Xu lijun, Zhang Shengxia and Hu Peipei

Response of high dielectric-constant hafnium oxide (HfO2) under heavy ions irradiation is important for the anti-

radiation study of the electronic devices in space application. Modifications of heavy ions on the dielectric properties

of HfO2-metal oxide semiconductor (MOS) capacitors were investigated in this study. The typical sample structure

is W (75 nm) /TiN (5 nm) /HfO2 (8 nm) /p-Si (substrate). The samples were irradiated by 25 MeV/u 86Kr26+ ions

at room temperature with electronic energy loss from 12.58 to 19.53 keV/nm to a fluence of 1×1010 ions/cm2. The

capacitance-voltage (C-V) characteristics of the devices before and after irradiation were performed using Keithley

4200 integrated system analyzer and shielding probe station at 100 kHz AC frequency (Fig.1). The values of the

capacitance in the accumulation region decrease with increasing of electron energy loss. No obvious shift or “stretch

out” was observed in C-V curves after irradiation with different electronic energy losses, which suggests that heavy

ion irradiation does not introduce enough oxide trap charge and interface state trap charge at fluence up to 1×1010

ions/cm2[1]. To explain the influence of radiation-induced defects and interface states on electrical characterization

of the device, transmission electron microscopy (TEM) was used to investigate the micro-structure of the HfO2

gate dielectric. From TEM observation, the degradation of the electrical properties of the devices can be attributed

to the recrystallization of the amorphous HfO2 after irradiation, which changes the dielectric constant and the

insulation properties of the HfO2 gate dielectric layer (Fig.2).

2017 IMP & HIRFL Annual Report · 113 ·

Fig. 1 (color online) C-V characteristics measured at 100kHz for HfO2 MOS capacitors on 8∼12 Ω·cm p-typesilicon substrate. The different curves correspond topristine and 25 MeV/u 86Kr26+ ions irradiated deviceswith different electronic energy losses.

Fig. 2 Cross-section HRTEM micrograph of the HfO2

MOS capacitor irradiated at 1×1012 ions/cm2 withelectronic energy loss of 19.53 keV/nm.

Reference

[1] E. H. Nicollian, J. R. Brews, MOS (Metal Oxide Semiconductor) Physics and Technology (Wiley, New York, 2003).

4 - 20 Effects of Total Ionizing Dose on Single Event Upset

Sensitivity of FRAMs

Ji Qinggang, Liu Jie, Yin Yanan, Liu Tianqi, Ye Bing, Zhao Peixiong, Cai Chang,

Liu Li, Mo Lihua, Li Dongqing and Hou Mingdong

Ferroelectric random access memory (FRAM) is a type of nonvolatile memory that possesses many advantages,

such as high operation speed and low power consumption[1]. In this work, the impact of total ionizing dose (TID)

on single event upset (SEU) sensitivity was studied for FRAMs. The influence of different test modes and memory

patterns on FRAMs was investigated. Parameters of the test devices are listed in Table 1.

Table 1 Parameters of test devices.

Device type ManufacturerMemory

organization/bitFeature size/nm Bias/V

FM22l16 Ramtron 256k×16 130 3.3

The TID irradiations were performed with 60Co gamma rays utilized in Xinjiang Technical Institute of Physics

and Chemistry, Chinese Academy of Science. All bytes of the devices were set into a 55H pattern before the

irradiation. A distinct increase of the standby power supply current was observed after TID irradiation. Figure 1

shows the standby power supply current as a function of deposited dose.

SEU sensitivity was measured at the Heavy Ion Research Facility in Lanzhou (HIRFL) in Institute of Modern

Physics, Chinese Academy of Science. Bi ions were used to investigate the SEU sensitivity. Both 55H pattern

and AAH pattern were applied in SEU characterization. The SEU cross section of FRAMs decreased after TID

irradiation. Figure 2 shows the SEU cross section measured in dynamic mode as a function of TID. No SEL and

memory pattern dependency were observed in this work.

In our further work, the influence of high ionizing dose and high fluence of heavy ion on memory cells will be

studied. More details of FRAM structure are needed for better understanding of how the degradation of periphery

COMS circuits influences the SEU cross section.