Novel approaches for Silicon-on-Insulator (SOI) related structures fabrication and channel doping

Abstract

Silicon-on-insulator (SOI) offers many advantages in fabricating deep sub-micrometer complementary metal-oxide (CMOS) devices with high speed and low power. The development of new technologies for the integration of dissimilar materials will be needed to meet many of the advanced technological needs of the future, such as new microelectronics, three-dimensional electronics, and the integration of small mechanical systems made from dissimilar materials. Currently, ion-cut (or smart-cut) processing is widely considered as a promising technology to achieve multi-materials integration. In the fabrication of SOI using ion-cut, hydrogen ion implantation is conventionally used to initiate the transfer of Si thin layers onto another Si wafers coated with a thermal oxide. However, the crystalline quality of the transferred layer often suffers from hydrogen implantation damage. Furthermore, the use of high dose hydrogen implantation results in process inefficiency and high cost. In this work, the feasibility of using plasma hydrogenation to replace high dose H-implantation for layer transfer was studied. Boron ion implantation was used to introduce H-trapping centers into Si wafers to illustrate this idea. B implantation and subsequent processes were used to control the uniformity of H-trapping and the trap depths. In addition to the SOI structures, we also demonstrated the use of plasma hydrogenation for the fabrication of SiGe-on-insulator (SGOI) materials by hydrogenating the SiGe/Si heterostructures. The H-trapping mechanism in both cases has been examined using different analytical methods. The optimal experimental conditions for plasma hydrogenation have been established. Our results suggest an innovative way to achieve high quality layer transfer without H implantation at high energies and high doses. Besides the novel approach for SOI related material fabrications, indium implantation into SOI as a novel dopant for channel doping was also studied. As device dimensions are scaled into the deep submicron regime, indium has become a promising dopant to create a steep retrograde channel profile (SRCP) in metal-oxide-semiconductor field-effect-transistors (MOSFETs). Although much work has hitherto been conducted to investigate the indium diffusion behavior in bulk Si substrate, there is a relative lack of studies on indium behaviors in SOI. In this work, the indium implant damage and diffusion behavior in thin silicon-on-insulator (SOI) were studied for different implantation energies and doses. The anomalous redistribution of indium after relatively high energy and dose implantation was also studied and compared between in both bulk Si and SOI substrates. There exist differences between diffusion behaviors in these two substrates based on the distinct structures of SOI.

Date of Award	4 Oct 2004
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Paul Kim Ho CHU (Supervisor)