总剂量效应致0.13μm部分耗尽绝缘体上硅N型金属氧化物半导体场效应晶体管热载流子增强效应

空间科学的进步对航天用电子器件提出了更高的性能需求, 绝缘体上硅(SOI)技术由此进入空间科学领域, 这使得器件的应用面临深空辐射环境与地面常规可靠性的双重挑战. 进行SOI N型金属氧化物半导体场效应晶体管电离辐射损伤对热载流子可靠性的影响研究, 有助于对SOI器件空间应用的综合可靠性进行评估. 通过预辐照和未辐照、不同沟道宽长比的器件热载流子试验结果对比, 发现总剂量损伤导致热载流子损伤增强效应, 机理分析表明该效应是STI辐射感生电场增强沟道电子空穴碰撞电离率所引起. 与未辐照器件相比, 预辐照器件在热载流子试验中的衬底电流明显增大, 器件的转移特性曲线、输出特性曲线、跨导特性曲线以及关键电学参数V_T, GM_max, ID_SAT退化较多. 本文还对宽沟道器件测试中衬底电流减小以及不连续这一特殊现象进行了讨论.

Enhanced channel hot carrier effect of 0.13 μm silicon-on-insulator N metal-oxide-semiconductor field-effect transistor induced by total ionizing dose effect

In this paper, a series of hot carriers tests of irradiated 130 nm partially depleted silicon-on-insulator NMOSFETs is carried out in order to explore the HCI influence on the ionizing radiation damage. Some devices are irradiated by up to 3000 Gy before testing the hot carriers, while other devices experience hot carriers test only. All the devices we used in the experiments are fabricated by using a 130 nm partially depleted (PD) SOI technology. The devices each have a 6nm-thick gate oxide, 100 nm-thick silicon film, and 145 nm-thick buried oxide, with using shallow trench isolation (STI) for isolation scheme. The irradiation experiments are carried by ⁶⁰Co-γ ray at the Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, with a dose rate of 0.8~Gy(Si)/s. During irradiation all the samples are biased at 3.3V, i.e., V_GS=3.3V and other pins are grounded, and when the devices are irradiated respectively by total doses of 500, 1000, 2000 and 3000Gy(Si), we test the characteristic curves again. Then 168-hour room temperature anneal experiments are carried out for the irradiated devices, using the same biases under irradiation. The HCI stress condition is chosen by searching for the maximum substrate current. The cumulative stress time is 5000s, and the time intervals are 10, 100, 500, 1000 and 5000s respectively. After each stress interval, the device parameters are measured until stress time termination appears. Through the comparison of characteristic between pre-irradiated and unirradiated devices, we find that the total dose damage results in the enhanced effect of hot carriers: the substrate current value which characterizes the hot carrier effect (for SOI device are the body to the ground current) increases with the increase of total dose, as the pre-irradiated and unirradiated device do under the same conditions of hot carrier stress, the degradations of key electrical parameters are more obvious for the pre-irradiated one. In order to analyze the physical mechanism of the experimental phenomena, the wide channel device is tested too, we also analyze the phenomenon of the decrease of the substrate current of the wide channel device. From the contrasts of pre-irradiated and unirradiated devices, and narrow and wide channel device test results, we can obtain the following conclusions: SOI devices (especially the narrow channel device) with additional ionization irradiation field induced by ionizing radiation enhance the rate of injecting electrons into the silicon dioxide, and produce oxide trap charge and interface states, which leads to the fact that the channel carrier scattering becomes stronger, transfer characteristic curve of the device, output characteristic curve, transconductance curves and the related parameters of V_T, GM_max, ID_SAT degradation degree increase. So, when designing 130nm PD SOI NMOSFETs which are applied to the space environment, one should make a compromise between radiation resistance and HCI reliability.