Next Generation Imager

"Silicon based charged couple devices (CCD) have been the workhorse of solid state imaging technology for use in the visible spectrum. As the need for higher resolution is ever increasing, silicon based systems are being pushed to their limit. Either largersystems, constructed on a single wafer or higher pixel density per square centimeter are called for. In either case, all pixels in a frame must be clocked out in a serial manner. This causes a reduction in frame rates and as importantly data overload. Whentrying to fabricate large area devices on silicon, two constraints are imposed. The capacitance inherent in the poly-silicon lines, that shuffle the charge to the output register, limits the ability to drive the collected charge in the center pixels. Thepoly-silicon gates also reduce the quantum efficiency of the device due to the fact that they are place over the pixels and strongly absorb visible light. This has necessitated backside thinning of devices that increase production costs and lower yields.Also, the larger the area that a silicon imaging device covers on a substrate the lower the yield. This is due to defects formed during thermal cycling deposition steps and native defects found in the single silicon substrates. If a higher pixel density ischosen the full well capacity drops and saturation or blooming can occur even at a lower light level. Townsend Science and Engineering (TS&E) will possess the two critical elements