Design Method For Ultra-High Resolution Linear CCD Imagers

Abstract

This paper presents the design method to achieve ultra -high resolution linear imagers.This method utilizes advanced design rules and novel staggered bilinear photo sensor arrays with quadrilinear shift registers. Design constraint in the detector arrays and shift registers are analyzed. Imager architecture to achieve ultra -high resolution is presented.The characteristics of MTF, aliasing, speed, transfer efficiency and fine photolithography requirements associated with this architecture are also discussed.A CCD imager with advanced 1.5 um minimum feature size was fabricated. It is intended as a test vehicle for the next generation small sampling pitch ultra -high resolution CCD imager.Standard double -poly, two -phase shift registers were fabricated at an 8 um pitch using the advanced design rules.A special process step that blocked the source -drain implant from the shift register area was invented.This guaranteed excellent performance of the shift registers regardless of the small poly overlaps. A charge transfer efficiency of better than 0.99995 and maximum transfer speed of 8 MHz were achieved.The imager showed excellent performance. The dark current was less than 0.2 mV /ms, saturation 250 mV, adjacent photoresponse non -uniformity ± 4% and responsivity 0.7 V/ uJ/cm2 for the 8 pm x 6 pm photosensor size.The MTF was 0.6 at 62.5 cycles /mm. These results confirm the feasibility of the next generation ultra -high resolution CCD imagers.

Biomedical imaging and sensing using flatbed scanners

“…The resolution of these systems are further enhanced by using a staggered pixel configuration, where an additional line of red, green, and blue sensitive pixels is placed next to the original ones with a half pixel shift. Since the CCD sensor pixels are usually more sensitive to light in the middle of the pixel 26 , this spatial sensitivity information together with the staggered configuration can be used to synthesize an image with a spatial resolution corresponding to half of the pixel pitch without sacrificing sensitivity 27–29 . Generally speaking, CCD based scanner systems have a longer depth of field (~1–2 mm), which makes them suitable to image samples placed outside the ideal focal plane of the lens, such as samples in Petri dishes.…”