Holger Stoldt

A high-speed high-sensitivity 1/2-inch 1M-pixel frame-transfer CCD imager for medical and industrial applications

A 1/2 inch 1M-pixel monochrome Frame-Transfer CCD imager with 5.6μm by 5.6μm pixel size was developed for use in medical and industrial applications. The sensor production uses 17 mask steps designed for an improved process, with highly transparent membrane poly-silicon gates and two metal layers. The first metal layer is used for vertical strapping to reduce the RC- times of the imaging electrodes. The image pixels, the storage cells and the readout register are made using two layers of membrane poly-silicon. An n-channel implant on a profiled p-well in a n-substrate achieves 52,000 electrons full well charge storage capacity in combination with excellent vertical anti-blooming and fast electronic shuttering. Smear as low as 0.06% at 1/30 sec integration time is achieved at 5MHz frame shift frequency. The pixel charge is converted to an output voltage using a 3-stage source follower amplifier, optimized for 40MHz pixel frequency. For use in high-speed industrial applications, the split read-out allows pixel rates up to 80MHz. The output amplifier with a conversion gain of 18.7μV/electron has an rms noise of 18 electrons at full bandwidth (linear dynamic range of 67.8 dB). The dark current level is 100 pA/cm2 at 60° C.

Real-time imaging with mega-pixel charge-coupled devices

A technology is described which allows the application of real-time imaging in combination with mega-pixel CCDs. This technology is based on the following characteristics: high-speed transport of the video information through the parallel CCDs in the imaging section, very high-speed transport of the charge packets through the serial section of the devices, and high- speed conversion of the electrons to a measurable voltage by the output amplifier. Key competencies to comply with these requirements are: low-resistive CCD gates, low- capacitance CCD gates and high bandwidth and low noise floor output stages.