AVS 46th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS1+EM-WeA

Paper SS1+EM-WeA7
Microcalorimetric Heats of Adsorption of Metals on Metal Oxide and Si(100) Surfaces

Wednesday, October 27, 1999, 4:00 pm, Room 606

Session: Semiconductor Surface Science
Presenter: D.E. Starr, University of Washington
Authors: D.E. Starr, University of Washington
D.J. Bald, Intel Corporation
J.E. Musgrove, University of Washington
J.T. Ranney, University of Washington
J.H. Larsen, University of Washington
C.T. Campbell, University of Washington
Correspondent: Click to Email
Single crystal adsorption microcalorimetry has been proven to be a powerful method to study the heats of adsorption of gaseous atoms or molecules onto single crystal surfaces. Recently, a microcalorimeter has been built which possesses the capability to measure heats of adsorption of metal atoms onto single crystal surfaces as a function of coverage. A sensitive pyroelectric polymer is used to detect the heat released due to the adsorption of pulses of gaseous metal atoms, each containing ~2% of a monolayer, onto the surface. The microcalorimeter has been employed to study the energetics of film growth from the initial stages of deposition through the multilayer regime for metal on metal and metal on metal oxide systems. For the metal on oxide systems, an initial heat of adsorption which is much lower than the heat of sublimation of the metal is observed. This provides detailed insight into the thermodynamic driving force for the metal overlayer to form three dimensional islands. Auger electron spectroscopy was used to verify the growth morphology. In addition, the extension of this technique to study the heats of adsorption of metals onto silicon substrates allows the study of many systems important to metal-semiconductor contact technology. In order to accurately quantify the heats of adsorption, the metals sticking probability on the surface must be known. These have also been measured and will be discussed. In addition, via a thermodynamic cycle the adhesion energy of the metal to the substrate is obtained from the measured microcalorimetric heats of adsorption.