AVS 49th International Symposium
    Applied Surface Science Tuesday Sessions
       Session AS-TuP

Paper AS-TuP12
SIMS Depth Profiling of Multilayer Structures

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Topics in Applied Surface Science
Presenter: A. Godines, CINVESTAV-IPN, Mexico
Authors: A. Godines, CINVESTAV-IPN, Mexico
Yu. Kudriavtsev, CINVESTAV-IPN, Mexico
A. Villegas, CINVESTAV-IPN, Mexico
R. Asomoza, CINVESTAV-IPN, Mexico
Correspondent: Click to Email
In this work we performed a comparative study of the depth resolution function for metal and semiconductor multi-layers in depends on primary ion kind, primary ion energy and angle of incidence. Influence of oxygen flooding on the depth resolution was analyzed as well. Subject of our study was different test semiconductor multi-layers grown by MBE: AlAs/GaAs, AlGaAs/GaAs, GaAsN/GaAs, InGaAs/GaAs, AlGaN/AlN, as well as metal multi-layers (neutron super-mirrors): Co/Ti and Si/Fe. The number of layers has varied from 20 to 200; the thickness of an individual layer has varied from 1 monolayer to about 20nm. Sputtering was performed by cesium and oxygen positive ions. SIMS depth resolution depends on many different factors and effects such as surface roughness and surface roughness caused by ion bombardment, ion mixing effect, radiation enhanced diffusion and so on. In our work the ion mixing was found as the main effect affecting the depth resolution of semiconductor multi-layers. Parameter, which characterizes it, was found being proportional to the root square of the primary ion energy, normalized on the cosine of the angle of incidence, for both metal and semiconductor multi-layers. We did not find any mass dependence of the depth resolution that is in a contrast with the ballistic mixing model. Oxygen ion bombardment leaded to a dramatic reduce of the depth resolution in the case of metal multi-layers, because of a strong surface roughness formation. Moreover, a strong matrix effect was found at the interfaces of metal layers, which was more pronounced in the case of cesium ion bombardment. In order to reduce the matrix effect, we applied the oxygen flooding. This technique: Cs+ ion bombardment with CsM+ (where M is the analyzed element) secondary ions monitoring and with simultaneous oxygen flooding was found as the best method for metal multi-layer depth profiling.