Abstract:

The ever increasing interest in inspection techniques with excellent depth resolution and great detection sensitivity remains a driving force for development of low energy SIMS (LESIMS). In spite of the great progress in LESIMS in the past ten years, challenges remains in further improvement of its depth resolving capability by either reducing the primary beam energy or increasing the angle of incidence. It is known that reduction in the primary beam energy in the range of hundreds electron Volts (eV) leads to dramatic drop in the sputter yield and the intensity of the primary beams. Meanwhile, probing a sample at a glancing incidence may encounter issues such as surface roughening, low secondary ion yield, and poor transmission of secondary ions.

This talk presents fundamentals and applications of LESIMS with sub-keV O₂⁺ beams at glancing incidence. Our data suggested that surface roughening remained minimal for 250 eV and 500 eV O₂⁺ beams at an angle of incidence above 80° but developed rapidly at angles between 60° and 80°. For some common dopant species in Si, such as boron and nitrogen, good detection sensitivity was achievable through proper selection of characteristic secondary ions. By using the glancing O₂⁺ beams, the sputtering erosion was constant after a short surface transient and the in-depth atomic mixing was minimal.

We applied the glancing O₂⁺ primary beams to characterize shallow boron in Si, shallow nitrogen in ultra-thin oxide, as well as ultra-thin SiGe films in Si. The approach delivered unprecedented accuracy for near surface boron and nitrogen depth profiles as well as for thin SiGe films inside Si.

Biography：

Dr. Zhixiong Jiang is a senior staff scientist in the Physical Analysis Laboratories (TX) of Freescale Semiconductor, Inc (former Semiconductor Product Sector of Motorola Inc.). Before he joined Motorola Inc. in 2000, he was a senior research engineer in the Department of Failure Analysis and Reliability, Institute of Microelectronics (IME), Singapore. From 1995 to 1998, Dr. Jiang worked as a postdoctoral research fellow in the Delft University of Technology, the Netherlands. He earned his Ph.D in 1995 from Tsinghua University in Beijing, under supervision of Prof. Liangzhen Cha. For about 20 years, Dr. Jiang has been working on SIMS and other surface analysis techniques on the fundamentals of ion-solid interactions, development of advanced analytical techniques, and applications of the surface analysis techniques in the semiconductor industry. He authored and co-authored over 60 publications in journals and conference proceedings. He currently holds two US patents.