Our experience in the design of an ultra-high speed image sensor targeting the theoretical maximum frame rate is summarized. The imager is the backside illuminated in situ storage image sensor (BSI ISIS). It is confirmed that the critical factor limiting the highest frame rate is the signal electron transit time from the generation layer at the back side of each pixel to the input gate to the in situ storage area on the front side. The theoretical maximum frame rate is estimated at 100 Mega-frames per second (Mfps) by transient simulation study. The sensor has a spatial resolution of 140,800 pixels with 126 linear storage elements installed in each pixel. The very high sensitivity is ensured by application of backside illumination technology and cooling. The ultra-high frame rate is achieved by the in situ storage image sensor (ISIS) structure on the front side. In this paper, we summarize technologies developed to achieve the theoretical maximum frame rate, including: (1) a special p-well design by triple injections to generate a smooth electric field backside towards the collection gate on the front side, resulting in much shorter electron transit time; (2) design technique to reduce RC delay by employing an extra metal layer exclusively to electrodes responsible for ultra-high speed image capturing; (3) a CCD specific complementary on-chip inductance minimization technique with a couple of stacked differential bus lines.

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This paper outlines a special microscope under development, named "Ultra-high-speed bionanoscope" for ultra-highspeed imaging in biological applications, and preliminary design of the image sensor, which is the key component in the system. The ultra-high-speed bionanoscope consists of two major subsystems: a video camera operating at more than 10 Mfps with ultra-high-sensitivity and the special microscope to minimize loss of light for seriously reduced illumination light energy due to the ultra-high-speed imaging. The ultra-high-frame rate is achieved by introducing a special structure of a CCD imager, the ISIS, In-situ Storage Image Sensor, invented by Etoh and Mutoh. The ISIS has an array of pixels each of which equips with a slanted linear CCD storage area for more than 100 image signals for reproduction of smoothly moving images. The ultra-high-sensitivity of the sensor of less than 10 photons is achieved by introducing three existing technologies, backside-illumination, cooling, and the CCM, Charge Carrier Multiplication invented by Hynecek.