【作者】 刘畅；

【导师】 赵毅；

【作者基本信息】 南京大学 ， 微电子学与固体电子学， 2015， 硕士

【摘要】 由于硅集成电路器件的尺寸遵循着摩尔定律不断缩小,即将接近其物理极限,减小栅长以提高性能的方法已经无法继续,因此寻找新的材料、结构、工艺和原理才是集成电路继续发展的方向。与硅同为四族元素的锗材料,由于其具有的较高空穴迁移率,成为了未来集成电路发展的热门候选材料。基于上述原因,本课题选择锗作为衬底材料进行讨论和器件制备。首先讨论了两种最成熟的集成电路掺杂工艺:气相热扩散和离子注入,分析了这些工艺应用于锗基立体结构器件超浅掺杂的局限性,比较得出旋涂掺杂工艺的优势和可行性。在介绍旋涂掺杂工艺基本步骤和原理后,针对锗材料的特点和集成电路工艺的要求,进行了掺杂元素种类的筛选。提出了使用激光退火改善p-n结中杂质分布的设想并讨论其可行性。从扩散的基本原理出发,建立模型计算旋涂掺杂和激光退火得到的p-n结中杂质的分布,讨论了适当参数激光退火对掺杂元素分布可能产生的改善。设计了包含旋涂掺杂和激光退火的p-n结工艺,通过实验制备了热处理和激光退火的旋涂掺杂p-n结,得到的器件性能符合预期,而且经过激光退火的p-n结开关比增大了近一个数量级,证明了激光退火对p-n结特性的改善,通过p-n结势垒电容的测试和计算,证明了杂质分布符合本课题的理论分析。完成p-n结的制备后,又设计了锗基旋涂掺杂晶体管工艺,并制备出具有一定器件性能的样品,证明了旋涂掺杂和激光退火融入传统晶体管工艺的可能性,并通过分析器件制备过程中的问题,提出了改进方案,指导后续的实验和研究。更多还原

【Abstract】 With the continued device scaling to its physical limitation following the Moore’s law,it would not be feasible to improve device performance by decreasing the gate length.So the introduction of new materials,structures,processes and theories is compulsory for developing the integrated circuit(IC)technology.Germanium,in the same element group of silicon,is a promising new material candidate for the future semiconductor industry because of its high carrier mobility.So we choose Germanium as the subject for discussion and device preparation in this research work.Two well-developed doping techniques in integrated circuits were gaseous heat diffusion and ion implantation.Both have its limitations in forming the ultra-shallow doped junction which is necessary for the 3-D Germanium devices.However,we found that the spin-on dopant(SOD)technique is more feasible in the application of ultra-shallow-junction for Ge devices..We first introduced the fundamentals of SOD and the basic process flow of the SOD technique.The selection of the suitable doping element in SOD is based on the properties of Germanium and the compatibility with the CMOS IC fabrications.Then the laser annealing,instead of furnace annealing or rapid thermal annealing(RTA),is used to improve the doping profile.This improvement of the laser annealing over the thermal annealing(RTA/furnace annealing)has been confirmed by a model based on the first principle of the diffusion.A p-n junction was realized by SOD and the laser annealing.The samples show normal performance of p-n junction,and the on-off ratio of the laser annealed sample was an order of magnitude larger than that by the thermal-annealing.C-V measurement of the p-n junction also shows that the junction depth by the laser annealing is for small than that by the normal thermal annealing.This work demonstrates that the laser annealing can improve the p-n junctions’ performance.After the successful fabrication of the p-n junction,the SOD technique was introduced to the Germanium MOSFET process.The devices by the first trial run already show certain gate voltage control over the channel conductivity,i.e.,laser annealing after the SOD is suitable for the Ge MOSFET.Possible problems were analyzed and the suggestion for improving the MOSFET performance were proposed.更多还原