AVS 49th International Symposium
    Applied Surface Science Wednesday Sessions
       Session AS-WeA

Paper AS-WeA1
Ultra-high Resolution AES Depth Profiling using a Masked Specimen Holder

Wednesday, November 6, 2002, 2:00 pm, Room C-106

Session: High-k Dielectric Characterization
Presenter: K. Satori, SONY Corporation, Japan
Authors: K. Satori, SONY Corporation, Japan
H. Kobayashi, SONY Corporation, Japan
K. Kimura, Kyoto University, Japan
K. Nakajima, Kyoto University, Japan
Correspondent: Click to Email
Auger electron spectroscopy (AES) using an instrument with coaxial geometry for an electron column and a cylindrical mirror analyzer (CMA) has the advantages of high sensitivity and accurate mapping capability. However, the analytical depth when using a coaxial CMA is larger than when using a hemispherical analyzer because the angle of the Auger electrons detected by a coaxial CMA ranges widely at any given tilt angle. This is a serious problem when we wish to evaluate ultra-thin films such as gate dielectrics. Some studies have been conducted using ion sputtering with low kinetic energy, to obtain high depth resolution. However, these studies have highlighted that one of the most important factors concerning depth resolution is the analytical depth. We designed angled and masked specimen holders to obtain a more shallow analytical depth using the coaxial CMA. We optimized the holder angle by calculating the distribution of the angle of the Auger electrons and the actual AES measurement to increase the intensity of the Auger electrons emitted at high angle from the surface normal. Next, we designed an electron shadow mask on a specimen holder to prevent the analyzer detecting the Auger electrons at low angle from the surface normal. Using the holder that we designed, the surface-sensitivity becomes three times higher than that of conventional methods. In addition, to improve depth resolution, we designed a new mask shape and obtained a low incident angle for the ion beam. Using the holder, the depth resolution was improved sufficiently to evaluate ultra-thin silicon oxynitride films (thickness 2.5nm). The shape of the AES depth profile was in good agreement with that obtained by means of high-resolution Rutherford backscattering spectroscopy. Our method is easy to use but useful for obtaining a shallow analytical depth and high depth resolution.