High Speed Field Programmable LSI Using Current-Drive Silicidation

采用钽/非晶硅/钽结构，研制了可大大缩短大规模集成电路开发周期的防熔丝器件。我们已经证明，通常只发生在700°C以上的温度下的硅化反应，可以在室温下通过“电流驱动硅化”进行，从而使反熔断器的编程非常快。采用超净等离子体工艺制作的防熔丝装置，可在不到1秒的短时间内通过“电流驱动硅化”进行编程，相当于反应速度达到5000m/秒，这是一般热反应所无法想象的。硅化后的接触电阻小于30 ω，而在硅化前，非晶硅在200-250℃的温度下沉积时，将泄漏电流限制在足够低的水平，足以分离开断状态。我们已经证明，通过在多室de…More位置系统中按顺序在钽膜上沉积非晶硅，而不将钽表面暴露在洁净室空气中，抗熔断器在高达400℃的温度下不会降解。为了表征工作偏置下漏电流的来源和电流驱动硅化的机理，我们研究了以钽、钛和铝为金属的防熔丝结构。此外，我们还利用n型和p型硅衬底形成了钽/非晶硅/晶体硅型肖特基二极管，目的是表征势垒高度和二极管特性。我们还通过研究接触电阻作为编程参数的函数，以及通过分析接触区域截面的SEM和TEM图像，阐明了许多杀菌机理。最后，为了建立实用LSI电路的设计规则，采用nMOS技术对TEG进行了精心设计，以最小化寄生电容和电阻。根据本研究的结果，建立了钽/非晶硅/钽型抗熔丝结构的制备工艺基础，该结构可以实现高速编程和极低的导通电阻。少

The antifuse device, that enables to drastically shorten the development cycle time of LSI circuits, was developed using tantalum/amorphous silicon/tantalum structure. We have shown that the silicidation reaction, that usually occurs only at temperatures higher than 700ﾟC,can be carried out at room temperature by the "current-drive silicidation" allowing a very fast programming of the antifuse. Antifuse devices made by ultraclean plasma process can be programd by "current drive silicidation" in the short time of less than 1 nsec, that is equivalent to a reaction speed of 5000m/sec, unimaginable in usual thermal reaction. The contact resistance after the silicidation is less than 30 OMEGA, and before the silicidation, the amorphous silicon, when deposited at temperature in the range of 200-250ﾟC,limits the leakage current at a level low enough to separate the on and off states. We have shown that by depositing the amorpous silicon over the tantalum film in sequence in a multi chamber de … More position system, without exposing the tantalum surface to the clean room air, there is no degradation of the antifuse up to a temperature as high as 400ﾟC.In order to characterize the origin of the leakage current under the operation bias and the mechanism of the current drive silicidation, we have studied antifuse structures using tantalum, titanium, and aluminum as the metal. In addition, we have formed Schottky diodes of the type tantalum/amorphous silicon/crystalline silicon, using silicon substrates of both, n and p type, with the purpose of characterizing the barrier height and the diode characteristics. We have also clarified many of the cilicidation mechanism by studying the contact resistance as a function of the programming parameter, as well as by analyzing SEM and TEM pictures of the cross sections at the contact region. Finally, in order to establish design rules of practical LSI circuits, TEG's were carefully designed to minimize the parasitic capacitances and resistances, using nMOS technology. From the results obtained in this research, the fundamentals of the fabrication process of antifuse structures of the type tantalum/amorphous silicon/tantalum, which allows high speed programming and very low on state resistance, were established. Less