AVS 49th International Symposium
    Manufacturing Science and Technology Monday Sessions
       Session MS+SE-MoM

Paper MS+SE-MoM11
Post-Deposition Control of Resistivity and Anisotropy in ZnO Thin Films

Monday, November 4, 2002, 11:40 am, Room C-109

Session: In-Situ Monitoring and Metrology for Coating Growth and Manufacturing
Presenter: J.S. Lewis, MCNC
Authors: J.S. Lewis, MCNC
B. Stoner, MCNC
C. Pace, MCNC
Correspondent: Click to Email
A method for post-deposition control of the resistivity of ZnO thin films has been developed, and a method for providing anisotropic sheet resistance in the plane of the film has been demonstrated. Military needs for real-time image processing can be met using thin film analog image processor (TAIP) devices. TAIP chips provide compact and power-efficient analog processing, including high- or low-pass spatial frequency filtering. The analog spatial filters are based on the RC time constant of the circuit, and therefore require thin films with controlled, repeatable sheet resistance in the range of M@ohm@/sq. This range of sheet resistance can be difficult to achieve with good repeatability for inorganic films. ZnO thin films were sputtered from an undoped ZnO target by RF magnetron sputtering. The as-deposited sheet resistance of the films was in the range 5-50 k@ohm@/sq. Post deposition processing yielded films with sheet resistance in the range from the as deposited value to > 100 M@ohm@/sq. Target values of sheet resistance were obtained routinely. Using an in-situ monitor of sheet resistance during processing resulted in much better repeatability than that possible for as-deposited films. For TAIP chips, anisotropic sheet resistance in the plane of the film can allow more sophisticated algorithms for image processing. Post processing techniques were used to fabricate ZnO thin films with sheet resistance anisotropy ratios in the range of 2:1 to 25:1, and larger anisotropies should be possible. This work was sponsored by DARPA (contract no. DAAD19-00-1-0002).