AVS 58th Annual International Symposium and Exhibition
    Electronic Materials and Processing Division Tuesday Sessions
       Session EM-TuA

Paper EM-TuA12
Metrology for Interfaces and Mass Transport in C-MOS Related Nanofilms

Tuesday, November 1, 2011, 5:40 pm, Room 210

Session: High-k Dielectrics for MOSFETs Part 2
Presenter: Araceli Sanchez-Martinez, CINVESTAV-Unidad Queretaro, Mexico
Authors: A. Herrera-Gomez, CINVESTAV-Unidad Queretaro, Mexico
A. Sanchez-Martinez, CINVESTAV-Unidad Queretaro, Mexico
O. Ceballos-Sanchez, CINVESTAV-Unidad Queretaro, Mexico
M.O. Vazquez-Lepe, CINVESTAV-Unidad Queretaro, Mexico
P. Lysaght, SEMATECH
Correspondent: Click to Email
Interface layers play a fundamental role in determining the electrical properties of CMOS devices because their thicknesses are of a magnitude comparable to that of the dielectric layers currently employed. The main (top) techniques traditionally used for characterizing the chemical depth profile of MOS structures have been XPS-Sputter and Back-Side TOF-SIMS. However, they lack the appropriate resolution to characterize the thickness and composition of nano or sub-nano layers. Due to the lack of appropriate metrology methods, the structure of interface layers is usually assessed indirectly through their effect on the device’s capacitance. Another important issue in the processing of MOS devices is the diffusion control of chemical species. To quantify or to simply observe displacements on the order of 2 or 3 nm of low concentration elements with those techniques is close to impossible. The semiconductor industry will greatly benefit from a metrology method capable of: (a) characterizing the thickness and composition of the various layers constituting a MOS device, including the interface layers; (b) assessing the effect of process driven diffusion of various critical chemical species present in the film. There is a growing consensus that X-Ray Photoelectron Spectroscopy (XPS), specifically Angle-Resolved XPS (ARXPS), has the appropriate chemical and depth resolution for assessing the depth profile of films between 0 and 8 nm. The precise methodology for applying the technique, however, varies wildly among different groups. In many cases the analysis algorithms of ARXPS data are highly susceptible to noise. Because of this, ARXPS is frequently regarded as qualitative techniques. In this talk we briefly describe a robust ARXPS analysis methodology that minimizes the sensitivity to noise. This methodology has been successfully applied to characterize various systems. One example that will be addressed regards the failure mechanism for the degradation of the electrical performance of TiN/HfO2/InGaAs devices during thermal processing. We investigated the change on the structure caused by annealing, such as the possible formation of As, Ga or In oxides, accumulation of these elements in the dielectric, formation of metallic arsenic, and/or any other change on the structure that could be correlated to device degradation. ARXPS experiments were performed on those samples and analyzed using the robust methodology. One important finding was that indium diffuses through the dielectric all the way into the metallic layer upon annealing.