AVS 47th International Symposium
    Material Characterization Tuesday Sessions
       Session MC-TuP

Paper MC-TuP7
Comparison of Improved Spreading Resistance Profiling and Secondary Ion Mass Spectrometry in the Characterization of Ion Implanted Dopant Profiles

Tuesday, October 3, 2000, 5:30 pm, Room Exhibit Hall C & D

Session: Poster Session
Presenter: L.C.P. Tan, The National University of Singapore
Authors: L.C.P. Tan, The National University of Singapore
L.S. Tan, The National University of Singapore
M.S. Leong, The National University of Singapore
C.W. Lee, ST Microelectronics Ltd.
Correspondent: Click to Email
Spreading resistance profiling (SRP) is a well-established technique for the determination of dopant profiles in silicon wafers. The dopant profile can then be recovered from the spreading resistance profile by using an iterative algorithm. It has been noticed that for certain dopant profiles, especially shallow ion implanted profiles, the junction depth determined from SRP often do not agree with those predicted by process simulators such as SUPREM3. In addition, the sheet resistance as measured using four-point probes is also sometimes different from that deduced from dopant profiles recovered by SRP. The discrepancy may arise if the algorithm used to convert the spreading resistance profile into the dopant profile does not take into an account a phenomenon known as the carrier redistribution effect. In this work, we describe the results of a set of experiments carried out to compare the dopant profiles obtained from SRP and secondary ions mass spectrometry (SIMS) as well as those predicted by SUPREM3. SRP is an electrical characterization technique that responds to the presence of electrons and holes. The p-n junction indicated by the spreading resistance profile is the electrical junction, where the electron concentration is equal to the hole concentration. SIMS, on the other hand, is a physical characterization technique that measures the profile of dopant atoms, and the junction obtained by SIMS is the metallurgical junction where the donor concentration is equal to the acceptor concentration. The electrical junction and the metallurgical junction do not necessarily coincide because of the carrier redistribution effect, especially in shallow ion implanted profiles. However, we shall show that by using a new algorithm that correctly models the carrier redistribution effect, the disagreement in the dopant profiles obtained by SRP, SIMS and SUPREM3 can be significantly reduced.