GOALI/IUCRP: Uniform Grain Size Polysilicon for Thin Film Transistors

GOALI/IUCRP：用于薄膜晶体管的均匀晶粒尺寸多晶硅

• 批准号: 9424399
• 负责人: George Collins
• 金额: $ 33.15万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-07-01 至 1998-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9424399&HistoricalAwards=false
• 关键词: GOALI; IUCRP; Uniform; Grain; Size

9424399 Collins The goal is to define low temperature processes to form uniform grain silicon films for use in fabricating thin film transistors to be benchmarked in static Random Access Memory System (RAMS), in collaboration with industrial partners. At present, transistors in amorphous silicon achieve low leakage, while in polysilicon, they achieve carrier high mobility. But one material is not able to provide both desirable properties at the same time unless crystalline silicon is used. The research approach is to use anodic aluminum oxide as a seed bed, where the seeds are uniformly spaced so that the subsequent polysilicon grains are forced to have an extremely narrow distribution of grain sizes thereby providing a tighter distribution of threshold voltages, mobilites and leakage currents in the thin film transistors. The first step is to use aluminum substrates that are anodized to form alumina and then move on to Al metalized Si wafers as substrates for final Si wafers processing through device fabrication . Since the processed wafer must never exceed 350 degrees celcius during the polysilicon formation on alumina due to the temperature limits of the underlying devices, non-thermal electron irradiation will be incorporated to cause weakly-bound species to desorb or re-order more efficiently, thereby allowing new microstructural pathways for uniform grain silicon. First, a silicon seed layer that has a single strong preferred orientation will be grown on the anodized Al, with as grown grain size as large as possible. Second, energetic particle bombardment-assisted Chemical Vapor Deposition will be used for the thick Si-on-Si film growth to achieve uniform size grains. Finally, grain boundary passivation is achieved via either low temperature plasma-based anneals or plasma immersion ion implantation. The electrical performance of transistors built with these silicon wafers will be measured with a target to exceed on/off current ratios above 10 to the power of 10 and mobilitie s exceeding 500 square cm./V-sec. Silicon remains the workhorse semiconductor material in the manufacture of computers, telecommunication equipment and myriad's of electronics devices. Successful completion of this research project has the potential to drive down the cost of silicon wafers for many electronic applications and improve the efficiency of many electronic devices. Further, industrial partners are collaborating closely by hosting university faculty and one student for three months and sending their own researcher to the university for one year. Cross fertilization of ideas between academia and industry impacts the Nation's ability to select relevant areas for research and then transform the results into the commercial sector to maintain global competitiveness.

9424399柯林斯目标是与工业合作伙伴合作，定义形成均匀颗粒硅膜的低温工艺，用于制造将在静态随机存取存储器系统(RAMS)中进行基准测试的薄膜晶体管。目前，非晶硅中的晶体管实现了低漏，而多晶硅中的晶体管实现了载流子的高迁移率。但是，除非使用结晶硅，否则一种材料不能同时提供这两种理想的性能。研究方法是使用阳极氧化铝作为种子床，其中种子均匀分布，从而迫使随后的多晶硅颗粒具有极窄的晶粒度分布，从而在薄膜晶体管中提供更紧密的阈值电压、MOBILITE和泄漏电流分布。第一步是使用铝阳极氧化形成氧化铝，然后转移到铝金属化的硅片上作为基片，通过器件制造进行最终的硅片加工。由于在氧化铝上形成多晶硅的过程中，由于底层器件的温度限制，处理后的晶片绝不能超过350摄氏度，因此将结合非热电子辐照，以使弱结合物种更有效地解吸或重新排序，从而为均匀颗粒硅提供新的微结构路径。首先，在经过阳极氧化的铝上生长具有单一强烈择优取向的硅种子层，生长出的晶粒度尽可能大。其次，采用高能粒子轰击辅助化学气相沉积的方法生长厚的Si-on-Si薄膜，以获得均匀的颗粒尺寸。最后，通过低温等离子体基退火或等离子体浸没离子注入实现晶界钝化。用这些硅片制造的晶体管的电性能将被测量，目标是超过10的通断电流比10的幂，以及移动S超过500平方厘米/伏秒。在计算机、电信设备和无数电子设备的制造中，硅仍然是主要的半导体材料。这一研究项目的成功完成有可能降低许多电子应用的硅片成本，并提高许多电子设备的效率。此外，行业合作伙伴正在密切合作，接待大学教职员工和一名学生三个月，并派遣他们自己的研究人员到大学学习一年。学术界和产业界之间的思想交流影响到国家选择相关领域进行研究，然后将结果转化为商业部门以保持全球竞争力的能力。