Laser Lateral Crystallization of Thin Au and Cu Films on SiO 2
- PDF / 2,728,154 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 13 Downloads / 234 Views
O6.6.1
Laser Lateral Crystallization of Thin Au and Cu Films on SiO2 J.E. Kline and J.P. Leonard, Department of Materials Science and Engineering, University of Pittsburgh, Pittsburgh, PA 15261 Rapid lateral solidification via excimer laser melt processing is demonstrated in 200 nm thick pure Cu and Au films, encapsulated above and below by amorphous SiO2. Mask projection irradiation is used to selectively melt lines 3 to 30 µm wide in the metal films, with lateral solidification proceeding transversely from the edge to the middle of the line. Encapsulation with the SiO2 overlayer and control of the fluence are found to be crucial parameters necessary to prevent dewetting while the films are molten. Transmission electron microscopy reveals large columnar grains with twin structures and other defects typical of rapid solidification. 1 Introduction Microstructural modification and control in metallic thin films on insulating substrates is a significant materials challenge for a number of emerging device applications. These include: 1) Electrical properties including conductance, scattering losses, and electromigration in sub-100 nm metallic interconnect structures[1]. 2) Compositional and microstructure requirements in electrode attachments for ferroelectric devices[2] and magnetic storage applications. 3) Development of new metal-based actuators, membranes, and other structural components in emerging MEMS/NEMS devices and sensors[3]. Current strategies to effect microstructural control in metal thin films involve parameters associated with the thermodynamics and kinetics of the deposition process, which are typically vapor or electrochemical methods. Heat treatment can also be used to relax stresses, refine crystalline microstructures, redistribute alloy or impurity components, or initiate the formation of new phases. These methods are neither spatially selective, nor direct⎯ they must act through the very thermodynamic and kinetic mechanisms that drive the stochastic development of microstructure—which generally lead to broad grain size distributions over limited ranges. There is a need for processing techniques that can directly modify the microstructure and properties of metal films after deposition, while avoiding the problems associated with conventional heat treatment. Such a processing technique should allow 1) Microstructural and spatially selective control of metallic sub-micron scale features in two- or three-dimensions, 2) Composition control with engineered and non-equilibrium redistribution of alloying elements, phases, and precipitates, and 3) Compatibility with existing device materials and processes, in particular a low processing temperature, but also should allow control of stress, adhesion, diffusion and interfacial chemistry. Rapid solidification processing (RSP) is a good example of a potential alternative process, with a demonstrated capability to produce unique properties in metals not otherwise available[4]. A rich array of phenomena have been discovered and investigated using RSP, including
Data Loading...
