Throughput of a coater module within the coater track is related to the solvent evaporation rate from the material that is being coated. Evaporation rate is controlled by the spin dynamics of the wafer and airflow dynamics over the wafer. Balancing these effects is the key to achieving very uniform coatings across a flat unpatterned wafer. As today’s coat tracks are being pushed to higher throughputs to match the scanner, the coat module throughput must be increased as well. For chemical manufacturers the evaporation rate of the material depends on the solvent used. One measure of relative evaporation rates is to compare flash points of a solvent. The lower the flash point, the quicker the solvent will evaporate. It is possible to formulate products with these volatile solvents although at a price. Shipping and manufacturing a more flammable product increase chances of fire, thereby increasing insurance premiums. Also, the end user of these chemicals will have to take extra precautions in the fab and in storage of these more flammable chemicals. An alternative coat process is possible which would allow higher throughput in a distinct coat module without sacrificing safety. A tradeoff is required for this process, that being a more complicated coat process and a higher viscosity chemical. The coat process uses the fact that evaporation rate depends on the spin dynamics of the wafer by utilizing a series of spin speeds that first would set the thickness of the material followed by a high spin speed to remove the residual solvent. This new process can yield a throughput of over 150 wafers per hour (wph) given two coat modules. The thickness uniformity of less than 2 nm (3 sigma) is still excellent, while drying times are shorter than 10 seconds to achieve the 150 wph throughput targets.
In the rapidly evolving field of intravascular ultrasound (IVUS) for tissue characterization and visualization, the assessment of vessel morphology still lacks a geometrically correct 3D reconstruction. The IVUS frames are usually stacked up to form a straight vessel, neglecting curvature and the axial twisting of the catheter during the pullback. This paper presents a comprehensive system for geometrically correct reconstruction of IVUS images by fusion with biplane angiography, thus combining the advantages of both modalities. Vessel cross-section and tissue characteristics are obtained form IVUS, while the 3D locations are derived by geometrical reconstruction from the angiographic projections. ECG-based timing ensures a proper match of the image data with the respective heart phase. The fusion is performed for each heart phase individually, thus yielding the 4-D data as a set of 3-D reconstructions.