AVS 46th International Symposium
    Applied Surface Science Division Wednesday Sessions
       Session AS-WeM

Paper AS-WeM8
Quantitative Auger Spectroscopy: Applications to Process Development and Qualification of Tungsten Silicide Films

Wednesday, October 27, 1999, 10:40 am, Room 6A

Session: Gaede-Langmuir Award Address and Quantitative Surface Analysis
Presenter: C.T. Dziobkowski, IBM Corp., E. Fishkill
Authors: C.T. Dziobkowski, IBM Corp., E. Fishkill
S.C. Ramac, IBM Corp., E. Fishkill
E.D. Adams, IBM Corp., Burlington
Correspondent: Click to Email
Tungsten silicide films are widely used in gate conductors for DRAM gate structures for complementary metal-oxide-silicon (CMOS) integrated circuits. Careful characterization of these films with Rutherford backscattering spectrometry (RBS) and Auger electron spectroscopy (AES), the two most commonly used techniques, helps define and control a practical tungsten silicide process. The correct choice of analytical parameters is essential in obtaining accurate and reproducible compositional analysis. The enhanced depth resolution of Auger spectroscopy is especially critical in viewing the region of the interface between the tungsten silicide and polysilicon. Currently, an intrinsic polysilicon cap is used between the doped polysilicon and the CVD deposited tungsten silicide to prevent an unwanted secondary reaction between phosphorus and tungsten hexafluoride which leads to a tungsten enriched interface. This enriched tungsten interface can result in abnormal oxidation, stress and loss of adhesion between the intrinsic polysilicon and tungsten silicide. AES and RBS analytical techniques have been applied to examining the control of this interface to allow extension of CVD tungsten silicide to the thinner gate polysilicon needed for advanced technologies. Examples will be given of the effects of varied gate cap thickness of both amorphous and intrinsic polycrystalline silicon on the tungsten silicide / polysilicon interface using these analytical techniques. The interface composition is known to have a profound effect on the performance of these devices.