SOI材料和器件抗辐射加固技术

Radiation hardening technology in SOI materials and devices

绝缘体上硅(SOI)技术是一种在硅材料与硅集成电路巨大成功的基础上发展起来的,有独特优势的并且能够突破传统硅集成电路限制的新技术.绝缘埋层(BOX)的存在使得SOI技术从根本上消除了体硅CMOS中的闩锁效应.在同等工艺节点下其单粒子翻转截面较体硅CMOS技术小了1~2个数量级,抗瞬时剂量率的能力也提高了2个数量级以上.这些固有优势使得SOI技术在军事和空间应用中具有举足轻重的地位.然而,在空间和核爆等电离辐射环境下,辐射将会在BOX层中引入大量的陷阱电荷.这些辐射感生的陷阱电荷会导致SOI器件和电路性能的退化,从而严重阻碍和制约了SOI技术在抗辐射加固中的应用.另一方面,SOI器件的寄生三极管放大效应会削弱SOI技术在抗单粒子辐射和瞬态辐射方面的优势,这使得抗辐射SOI器件与电路的加固设计面临着严峻的挑战.本文介绍了SOI器件中3种主要的电离辐射效应并对比了体硅器件和SOI器件辐射效应的差异.针对寄生双极晶体管导致SOI器件单粒子效应和剂量率效应敏感性增强的问题,提出了相应地减弱寄生双极晶体管效应的加固方法.针对SOI器件抗总剂量效应差的问题,分别从材料工艺和器件结构两个层次介绍了SOI器件的总剂量加固技术.

Based on the great success of silicon material and silicon integrated circuit, the silicon-on-insulator （SOI） technology occurs as a new technology with unique advantages to break the limitation of traditional bulk silicon technology. The existence of the buried oxide （BOX） can fundamentally eliminate the latch-up effect of the bulk CMOS technology. The sensitive volume of charge collection in SO1 device is smaller than in bulk one, potentially making SOI devices much more hardened to dose rate effect and single-event upset, the upset cross section is nearly two orders of magnitude smaller. These inherent advantages of SOI technology make it very important in military and space applications. However, the existence of the thick buried oxide also makes the total ionizing dose （TID） effect of the SOI devices more complicated. The radiation-induced trapped charge in the buried oxide can lead to serious degradations of the SO1 devices and circuits in the space and nuclear radiation environment, such as the increases of the off-state leakage current in the partially-depleted devices and the decreases of the front-gate threshold voltage in the fully-depleted NMOS devices. Meanwhile, the relatively thick field oxide is also very soft to ionizing radiation. Two common types of field oxide isolation are local oxidation of silicon （LOCOS） and shallow trench isolation （STI）. LOCOS isolation has been replaced by STI to reduce spacing between adjacent devices in the advanced submicron technology node. STI induced leakage after TID radiation has become a dramatic problem in modern technologies. Both the STI oxide and the buried oxide can potentially impact the total dose tolerance in SO1 transistors. This limits the application of SOI technology in radiation hardening. It is only by solving the problem of the total dose hardening that the SO1 technology can better fulfill its military applications. In addition, the single-event effect and dose rate effect of the SO1 circuits become more complicated due to the less critical charge for upset, higher operating frequency and enhanced parasitic bipolar effect for the deep submicron technology. All these factors challenge the hardening design technique of the SO1 devices and circuits. In this paper, the difference of ionizing radiation effects between bulk-silicon devices and SOI devices is compared. In order to enhance the radiation hardness of single event effect and dose rate effect in SOI device, the method of suppressing the parasitic bipolar transistor effect is proposed. Furthermore, the radiation hardened methods for TID effect in SO1 technology is investigated from two levels： radiation hardened by material and process, radiation hardened by layout. The development of an independent SOl radiation hardening technology will contribute to solve the problem in military electronics, such as radiation hardening, high reliability, and to promote the sustainable development of national defense construction and national security.