一种快速开启的低触发改进型DTSCR

提出了一种快速开启的低触发改进型DTSCR(MDTSCR)。该MDTSCR是在传统DTSCR基础上加入电流增益放大模块,大幅提升了寄生双极型晶体管的电流增益,降低触发电压,提高了器件的开启速度。实验结果表明,在28nm CMOS工艺下,与传统DTSCR相比,该MDTSCR的开启时间缩短了52%,触发电压从5.5V下降到4.5V。该MDTSCR通过调整二极管数目适应28nm CMOS工艺不同的设计窗口,获得了最优的防护性能。

A novel DTSCR with a variation lateral base doping structure to improve turn-on speed for ESD protection

The turn-on speed of electrostatic discharge （ESD） protection devices is very important for the protection of the ultrathin gate oxide. A double trigger silicon controlled rectifier device （DTSCR） can be used effectively for ESD protection because it can turn on relatively quickly. The turn-on process of the DTSCR is first studied, and a formula for calculating the turn-on time of the DTSCR is derived. It is found that the turn-on time of the DTSCR is determined mainly by the base transit time of the parasitic p-n-p and n-p-n transistors. Using the variation lateral base doping （VLBD） structure can reduce the base transit time, and a novel DTSCR device with a VLBD structure （VLBD_DTSCR） is proposed for ESD protection applications. The static-state and turn-on characteristics of the VLBD DTSCR device are simulated. The simulation results show that the VLBD structure can introduce a built-in electric field in the base region of the parasitic n-p-n and p--n-p bipolar transistors to accelerate the transport of free-carriers through the base region. In the same process and layout area, the turn-on time of the VLBD DTSCR device is at least 27% less than that of the DTSCR device with the traditional uniform base doping under the same value of the trigger current.

Insight into multiple-triggering effect in DTSCRs for ESD protection

The diode-triggered silicon-controlled rectifier（DTSCR） is widely used for electrostatic discharge（ESD） protection in advanced CMOS process owing to its advantages, such as design simplification, adjustable trigger/holding voltage, low parasitic capacitance. However, the multiple-triggering effect in the typical DTSCR device may cause undesirable larger overall trigger voltage, which results in a reduced ESD safe margin. In previous research, the major cause is attributed to the higher current level required in the intrinsic SCR. The related discussions indicate that it seems to result from the current division rule between the intrinsic and parasitic SCR formed in the triggering process. In this letter, inserting a large space into the trigger diodes is proposed to get a deeper insight into this issue. The triggering current is observed to be regularly reduced along with the increased space, which confirms that the current division is determined by the parasitic resistance distributed between the intrinsic and parasitic SCR paths. The theoretical analysis is well confirmed by device simulation and transmission line pulse（TLP） test results. The reduced overall trigger voltage is achieved in the modified DTSCR structures due to the comprehensive result of the parasitic resistance vs triggering current, which indicates a minimized multipletriggering effect.

Structure-dependent behaviors of diode-triggered silicon controlled rectifier under electrostatic discharge stress

The comprehensive understanding of the structure-dependent electrostatic discharge behaviors in a conventional diode-triggered silicon controlled rectifier （DTSCR） is presented in this paper. Combined with the device simulation, a mathematical model is built to get a more in-depth insight into this phenomenon. The theoretical studies are verified by the transmission-line-pulsing （TLP） test results of the modified DTSCR structure, which is realized in a 65-nm complementary metal-oxide-semiconductor （CMOS） process. The detailed analysis of the physical mechanism is used to provide predictions as the DTSCR-based protection scheme is required. In addition, a method is also presented to achieve the tradeoff between the leakage and trigger voltage in DTSCR.

Low-leakage diode-triggered silicon controlled rectifier for electrostatic discharge protection in 0.18-μm CMOS process

A diode-triggered silicon controlled rectifier (DTSCR) is being developed as an electrostatic discharge (ESD) pro- tection device for low voltage applications. However, DTSCR leaks high current during normal operation due to the Darlington effect of the triggering-assist diode string. In this study, two types of diode string triggered SCRs are designed for low leakage consideration; the modified diode string and composite polysilicon diode string triggered SCRs (MDTSCR & PDTSCR). Com- pared with the conventional DTSCR (CDTSCR), the MDTSCR has a much lower substrate leakage current with a relatively large silicon cost, and the PDTSCR has a much lower substrate leakage current with similar area and shows good leakage performance at a high temperature. Other DTSCR ESD properties are also investigated, especially regarding their layout, triggering voltage and failure current.