Photoelectric conversion device method for producing photoelectric conversion device and image pickup system
a technology of photoelectric conversion device and photoelectric conversion region, which is applied in the direction of television system, radioation control device, transistor, etc., can solve the problems of reducing the electric field strength in the photoelectric conversion region, and affecting the reliability of the mos transistor
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first embodiment
[0042]FIG. 4 is a schematic cross-sectional view of a photoelectric conversion device according to this embodiment. In this embodiment, a reset MOS transistor is exemplified as a MOS transistor located in a photoelectric conversion region.
[0043]FIG. 4 shows a photoelectric conversion region 101 and a peripheral circuit region 102. In the photoelectric conversion region 101, a cross-sectional structure of a photoelectric conversion element, a transfer MOS transistor, and a reset MOS transistor is shown. A MOS transistor in the peripheral circuit region 102 constitutes any of the above-described circuits.
[0044]The photoelectric conversion region 101 shown in FIG. 4 includes a gate electrode 31 of the transfer MOS transistor and a gate electrode 32 of the reset MOS transistor. Reference numeral 33 represents a semiconductor region 33 of a first conductivity type, the semiconductor region constituting the photoelectric conversion element. The same conductivity type as a charge treated a...
second embodiment
[0055]In this embodiment, a method for producing a photoelectric conversion device will be described. FIGS. 5A to 5E illustrate a procedure for fabricating a photoelectric conversion device.
[0056]As shown in FIG. 5A, a well (not shown) of a first conductivity type (n-type) and the well 39 of a second conductivity type (p-type) are formed in a semiconductor substrate 38 composed of silicon or the like. An element isolation region 41 is formed by shallow trench isolation (STI), selective oxidation, or the like. For convenience of description, in FIGS. 5A to 5E, the photoelectric conversion region 101 is shown adjacent to the peripheral circuit region 102.
[0057]As shown in FIG. 5B, after the formation of the polysilicon gate electrodes 31, 32, and 42 of MOS transistors, the semiconductor region 33 of a photodiode constituting a photoelectric conversion element is formed by introduction of an n-type impurity. Then a p-type surface region 35 is formed by introduction of a p-type impurity...
third embodiment
[0069]In this embodiment, the structure of an amplifying MOS transistor will be described as a MOS transistor located in the photoelectric conversion region. This structure may be combined with the structure of the reset MOS transistor described in each of the first and second embodiments.
[0070]FIG. 6 shows a cross-sectional structure in a photoelectric conversion region and a peripheral circuit region of a photoelectric conversion device. Elements equivalent to those in the first and second embodiments are designated using the same reference numerals, and redundant description is not repeated.
[0071]An optical anti-reflection film 66 is disposed on a photoelectric conversion element and reduces the interfacial reflection on the surface of a photodiode. The anti-reflection film 66 may have a stacked structure including a silicon nitride layer and a silicon oxide layer.
[0072]The floating diffusion region 3 that receives a charge from the photoelectric conversion element includes a lig...
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