AVS 50th International Symposium
    Electrochemistry and Fluid Solid Interfaces Tuesday Sessions
       Session EC+SS-TuM

Paper EC+SS-TuM5
Photoexcited Electrodeposition of Cu Structures on p-Si(001)

Tuesday, November 4, 2003, 9:40 am, Room 326

Session: Water at Interfaces I: Structure and Electrochemistry
Presenter: C. Scheck, The University of Alabama
Authors: C. Scheck, The University of Alabama
Y.-K. Liu, The University of Alabama
P. Evans, The University of Alabama
G. Zangari, University of Virginia
R. Schad, The University of Alabama
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Selective growth of metals on semiconductors has recently raised considerable interests, due to its possible application in the direct formation of interconnects on Si. We produced small structures by photo-excited electroless plating of Cu on p-type Si(001). The p-type substrate forms a Schottky barrier with the solution which inhibits the plating process. Local illumination creates minority carriers which become available to discharge metal ions. The illumination was done by converging a 1-5 mW laser beam to a 1-2mm focus diameter on the substrate in the plating solution using an optical microscope. We analyzed the diameter of the growing dots as a function of laser light wavelength and intensity, illumination duration, composition of the solution and charge carrier lifetime in the substrate. The dimensions of the dots are determined by the diffusion length of the excited minority carriers. The lateral dimensions of the produced structures are found to decrease with reduced laser wavelength or intensity but is independent of the duration of the illumination. Shorter minority carrier lifetimes in the semiconductor substrate lead to a further reduction of structure dimensions. The effect of spontaneous background precipitation on the Si surface is studied as a function of solution composition. The optical reflectivity can be related to the fractal surface roughness.