Solid-state imaging device

• US 6,046,466 A
• Filed: 12/09/1998
• Issued: 04/04/2000
• Est. Priority Date: 09/12/1997
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Juen, Masahiro, Suzuki, Satoshi, Ishida, Tomohisa, Ohkouchi, Naoki, Isogai, Tadao
• Primary Examiner(s): Ngo, Ngan V.
• Application Number:
  US09/209,322
• Time in Patent Office: 482 Days
• Field of Search: 257/257, 257/258, 257/262, 257/290, 257/291, 257/292, 348/296, 348/300, 348/301, 348/307, 348/308
• US Class Current: 257/258
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/14679 Junction field effect transistor [JFET] imagers; static induction transistor [SIT] imagers
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 25/53 Control of the integration time
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components

Abstract

A photoelectric conversion device suitable for use as an element of a photodetector array includes a photodiode for generating a first signal charge in response to incident light, an output unit including a JFET, and at least one transistor having an electrode that generates a second signal charge in response to incident light. The first and second signal charges may be output separately or combined. The second signal charge, or the first and second signal charges combined, may be monitored during an exposure time to determine the desired end of the exposure. An image sensor array may have one or more pixels with such light monitoring capability. The output signal for monitoring the light may be output over a reset drain interconnection, directly from the monitoring pixel or through other pixels via inter-pixel MOSFETS. Exposure time may be controlled, by timing a shutter or a strobe or the like, based on the monitored accumulation of signal charge during exposure. Microlenses may be provided on-chip to increase the effective aperture ratio of the array. The microlenses are designed to avoid interfering with the incident light used for monitoring. Resulting pixel-to-pixel variations in effective aperture ratio, if any, may be electronically compensated.

Claims

1. A photoelectric conversion device comprising:

(a) a photoelectric conversion element structured and arranged so as to generate, in response to incident light, a first signal charge corresponding to the incident light;

(b) an output unit comprising an amplification transistor having a control electrode, the amplification transistor being structured and arranged such that the control electrode generates, in response to the incident light, a second signal charge corresponding to the incident light, and the output unit being structured and arranged so as to output an electric signal corresponding to a charge present in the control electrode; and

(c) a transfer unit structured and arranged so as to transfer to the control electrode the first signal charge generated by the photoelectric conversion element, the transfer unit being supplied with a control signal so as to transfer the first signal charge in a manner either (1) so as to cause the output unit to output an electric signal corresponding to the sum of the first and second signal charges or (2) so as to cause the output unit to separately output both an electric signal corresponding to the first signal charge and an electric signal corresponding to the second signal charge.

2. The photoelectric conversion device of claim 1, wherein the amplification transistor is a field-effect transistor.

3. The photoelectric conversion device of claim 1, wherein a color filter of a specific color is provided above at least one of (1) an incident-light-receiving surface of the control electrode of the amplification transistor and (2) an incident-light-receiving surface of the photoelectric conversion element.

4. The photoelectric conversion device of claim 1, wherein a color filter of a specific color is provided above are incident-light-receiving surface of the control electrode of the amplification transistor and a color filter of a different color is provided above an incident-light-receiving surface of the photoelectric conversion element.

5. A photoelectric conversion apparatus comprising:

the photoelectric conversion device of claim 1;

a shutter; and

a controller structured and arranged so as to control the timing of the shutter so as to adjust the time during which the photoelectric conversion element generates a charge based on the second signal charge generated by the control electrode of the amplification transistor.

6. A photoelectric conversion apparatus comprising:

the photoelectric conversion device of claim 1;

a shutter; and

a controller structured and arranged to as to control the timing of the shutter based on the sum of (1) the signal charge generated by the control electrode of the amplification transistor and (2) the signal charge generated by the photoelectric conversion element, thereby adjusting the time during which the photoelectric conversion element generates a charge.

7. A photoelectric conversion device comprising:

(a) a photoelectric conversion element structured and arranged so as to generate, in response to incident light, a first signal charge corresponding to the incident light;

(b) an output unit comprising an amplification transistor having a control electrode, the output unit structured and arranged so as to output an electric signal corresponding to a charge present in the control electrode;

(c) a transfer unit structured and arranged so as to be able to transfer the first signal charge generated by the photoelectric conversion element to the control electrode; and

(d) a reset transistor positioned and arranged so as to be able to remove the charge present in the control electrode and so that at least a main electrode of the reset transistor generates, in response to the incident light, a second signal charge corresponding to the incident light, the reset transistor and the transfer unit being supplied with control signals so as to transfer the first signal charge to the output unit, causing the output unit to output an electric signal corresponding to the first signal charge, and so as to cause the second signal charge to be output from the reset transistor.

8. The photoelectric conversion device of claim 7, wherein said main electrode of the reset transistor is connected to a first transistor for outputting the signal charge generated by said main electrode and to a second transistor for applying a prescribed voltage to said main electrode.

9. The photoelectric conversion device of claim 7, wherein the amplification transistor is a field-effect transistor, and the reset transistor is a MOS transistor.

10. The photoelectric conversion device of claim 7, wherein a color filter of a specific color is positioned above at least one of (1) an incident-light-receiving surface of said main electrode of the reset transistor and (2) an incident-light-receiving surface of the photoelectric conversion element.

11. The photoelectric conversion device of claim 7, wherein a color filter of a specific color is provided above an incident-light-receiving surface of said main electrode of the reset transistor and a color filter of a different color is provided above an incident-light-receiving surface of the photoelectric conversion element.

12. A photoelectric conversion apparatus comprising:

the photoelectric conversion device of claim 7;

a shutter; and

a controller structured and arranged so as to control the timing of the shutter based on the second signal charge generated said main electrode of the reset transistor, thereby adjusting the time during which the photoelectric conversion element generates a charge.

13. A photoelectric conversion device comprising:

(a) a photoelectric conversion element structured and arranged so as to generate, in response to incident light, a first signal charge corresponding to the incident light;

(b) an output unit comprising an amplification transistor having a control electrode, the output unit being structured and arranged so as to output an electric signal corresponding to a charge present at the control electrode;

(c) a transfer unit positioned and arranged so as to be able to transfer the first signal charge generated by the photoelectric conversion element to the control electrode; and

(d) a reset transistor structured and arranged so as to be able to remove from the control electrode the charge present at the control electrode, the reset transistor being further structured and arranged so that at least a main electrode thereof generates, in response to the incident light, a second signal charge corresponding to the incident light, the reset transistor and the transfer unit being supplied with control signals so as to transfer the first and second signal charges to the control electrode either (1) such that the first and second signal charges are combined at the control electrode, or (2) such that the first and second signal charges are successively and individually present in the control electrode.

14. The photoelectric conversion device of claim 13, wherein the amplification transistor is a field-effect transistor, and the reset transistor is a MOS transistor.

15. The photoelectric conversion device of claim 13, wherein a color filter of a specific color is positioned above at least one of (1) an incident-light-receiving surface of said main electrode of the reset transistor and (2) an incident-light-receiving surface of the photoelectric conversion element.

16. The photoelectric conversion device of claim 13, wherein a color filter of a specific color is provided above an incident-light-receiving surface of said main electrode of the reset transistor, and a color filter of a different color is provided above an incident-light-receiving surface of the photoelectric conversion element.

17. A photoelectric conversion apparatus comprising:

the photoelectric conversion device of claim 13;

a shutter; and

a controller structured and arranged so as to control the timing of the shutter based on the second signal charge generated said main electrode of the reset transistor, thereby adjusting the time during which the photoelectric conversion element generates a charge.

18. A photoelectric conversion device comprising:

(a) a photoelectric conversion element structured and arranged so as to generate, in response to incident light, a first signal charge corresponding to the incident light;

(b) an output unit comprising an amplification transistor having a control electrode, the output unit being structured and arranged so as to output an electric signal corresponding to a charge present at the control electrode, the amplification transistor being structured and arranged such that the control electrode generates, in response to the incident light, a second signal charge corresponding to the incident light;

(c) a transfer unit structured and arranged so as to be able to transfer the first signal charge generated by the photoelectric conversion element to the control electrode; and

(d) a reset transistor structured and arranged so as to be able to remove from the control electrode the signal charge present at the control electrode, the reset transistor being further structured and arranged so that at least a main electrode thereof generates, in response to the incident light, a third signal charge corresponding to the incident light, the reset transistor and the transfer unit being supplied with control signals so as to transfer the first signal charge to the control electrode and so as to transfer the second and third signal charges to said main electrode of the reset transistor for output from said main electrode, the second and third signal charges being either (1) combined at said main electrode and output together as a combined signal charge, or (2) output sequentially at said main electrode.

19. The photoelectric conversion device of claim 18, wherein said main electrode of the reset transistor is connected to both a first transistor for outputting the second and third signal charges, and to a second transistor for applying a prescribed voltage to said main electrode.

20. The photoelectric conversion device of claim 18, wherein the amplification transistor is a field-effect transistor, and the reset transistor is a MOS transistor.

21. The photoelectric conversion device of claim 18, wherein a color filter of a specific color is provided above at least one incident-light-receiving surface from among (1) an incident-light-receiving surface of the control electrode of the amplification transistor, (2) an incident-light-receiving surface of said main electrode of the reset transistor, and (3) an incident-light-receiving surface of the photoelectric conversion element.

22. The photoelectric conversion device of claim 18, wherein a color filter of a specific color is provided above an incident-light-receiving surface of the photoelectric conversion element and a color filter of a different color is provided above at least one of (1) an incident-light-receiving surface of the control electrode of the amplification transistor and (2) an incident-light-receiving surface of said main electrode of the reset transistor.

23. A photoelectric conversion apparatus comprising:

the photoelectric conversion device of claim 18;

a shutter; and

a controller for controlling the timing of the shutter based on at least one of (1) the signal charge generated by the control electrode of the amplification transistor, and (2) the signal charge generated by said main electrode of the reset transistor, thereby adjusting the time during which the photoelectric conversion element generates a charge.

24. The photoelectric conversion apparatus of claim 23, wherein the controller closes the shutter when an electric signal output from the output unit exceeds a first prescribed value, or when a signal charge output from said main electrode of the reset transistor exceeds a second prescribed value, whichever comes first, thereby adjusting the time during which the photoelectric conversion element generates a charge.

25. A photoelectric conversion device comprising:

(a) a photoelectric conversion element structured and arranged so as to generate, in response to incident light, a first signal charge corresponding to the incident light;

(b) an output unit comprising an amplification transistor having a control electrode, the output unit being structured and arranged so as to output an electric signal corresponding to a charge present at the control electrode, the amplification transistor being structured and arranged such that the control electrode generates, in response to the incident light, a second signal charge corresponding to the incident light;

(c) a transfer unit structured and arranged so as to be able to transfer to the control electrode the first signal charge generated by the photoelectric conversion element; and

(d) a reset transistor structured and arranged so as to be able to remove from the control electrode the charge present at the control electrode, the reset transistor being further structured and arranged such that at least a main electrode thereof generates, in response to the incident light, a third signal charge corresponding to the incident light, the reset transistor and the transfer unit being supplied with control signals so as to output the third signal charge from said main electrode of the reset transistor and so as to transfer to the control electrode both the first and second signal charges, the first and second signal charges being so transferred either (1) so as to combine the first and second signal charges at the control electrode, or (2) so as to make the first and second signal charges individually present at the control electrode in succession.

26. The photoelectric conversion device of claim 25, wherein said main electrode of the reset transistor is connected to both a first transistor for outputting the third signal charge, and to a second transistor for applying a prescribed voltage to said main electrode.

27. The photoelectric conversion device of claim 25, wherein the amplification transistor is a field-effect transistor, and the reset transistor is a MOS transistor.

28. The photoelectric conversion device of claim 25, wherein a color filter of a specific color is provided above at least one incident-light-receiving surface from among (1) an incident-light-receiving surface of the control electrode of the amplification transistor, (2) an incident-light-receiving surface of said main electrode of the reset transistor, and (3) an incident-light-receiving surface of the photoelectric conversion element.

29. The photoelectric conversion device of claim 25, wherein a color filter of a specific color is provided above an incident-light-receiving surface of the photoelectric conversion element and a color filter of a different color is provided above at least one of (1) an incident-light-receiving surface of the control electrode of the amplification transistor and (2) an incident-light-receiving surface of said main electrode of the reset transistor.

30. A photoelectric conversion apparatus comprising:

the photoelectric conversion device of claim 25;

a shutter; and

a controller for controlling the timing of the shutter based on at least one of (1) the signal charge generated by the control electrode of the amplification transistor, and (2) the signal charge generated by said main electrode of the reset transistor, thereby adjusting the time during which the photoelectric conversion element generates a charge.

31. The photoelectric conversion apparatus of claim 30, wherein the controller closes the shutter when an electric signal output from the output unit exceeds a first prescribed value, or when a signal charge output from said main electrode of the reset transistor exceeds a second prescribed value, whichever comes first, thereby adjusting the time during which the photoelectric conversion element generates a charge.

32. A photoelectric conversion device comprising:

(a) a photoelectric conversion element structured and arranged so as to generate, in response to incident light, a first signal charge corresponding to the incident light;

(b) an output unit comprising an amplification transistor having a control electrode, the output unit being structured and arranged to as to output an electric signal corresponding to a charge present at the control electrode, the amplification transistor being structured and arranged such that the control electrode generates, in response to the incident light, a second signal charge corresponding to the incident light;

(c) a transfer unit structured and arranged so as to be able to transfer the first signal charge generated by the photoelectric conversion element to the control electrode; and

(d) a reset transistor structured and arranged so as to be able to remove from the control electrode the charge present at the control electrode, the reset transistor being further structured and arranged such that at least a main electrode thereof generates, in response to the incident light, a third signal charge corresponding to the incident light, the reset transistor and the transfer unit being supplied with control signals so as to cause the first, second, and third signal charges to be present, at the control electrode of the amplification transistor, with (1) all three signal charges combined at once at the control electrode, (2) all three signal charges individually in succession present at the control electrode, or (3) the first signal charge present individually and the second and third charges present in combination at the control electrode.

33. The photoelectric conversion device of claim 32, wherein the amplification transistor is a field-effect transistor, and the reset transistor is a MOS transistor.

34. The photoelectric conversion device of claim 32, wherein a color filter of a specific color is provided above at least one incident-light-receiving surface from among (1) an incident-light-receiving surface of the control electrode of the amplification transistor, (2) an incident-light-receiving surface of said main electrode of the reset transistor, and (3) an incident-light-receiving surface of the photoelectric conversion element.

35. The photoelectric conversion device of claim 32, wherein a color filter of a specific color is provided above an incident-light-receiving surface of the photoelectric conversion element and a color filter of a different color is provided above at least one of (1) an incident-light-receiving surface of the control electrode of the amplification transistor and (2) an incident-light-receiving surface of said main electrode of the reset transistor.

36. A photoelectric conversion apparatus comprising:

the photoelectric conversion device of claim 32;

a shutter; and

a controller for controlling the timing of the shutter based on at least one of (1) the signal charge generated by the control electrode of the amplification transistor, and (2) the signal charge generated by said main electrode of the reset transistor, thereby adjusting the time during which the photoelectric conversion element generates a charge.

37. The photoelectric conversion apparatus of claim 36, wherein the controller closes the shutter when an electric signal output from the output unit exceeds a first prescribed value, or when a signal charge output from said main electrode of the reset transistor exceeds a second prescribed value, whichever comes first, thereby adjusting the time during which the photoelectric conversion element generates a charge.

38. A light receiving device useful as a pixel element in a photodetector array, the device comprising:

(a) a photosensitive element structured and arranged so as to generate, in response light incident thereon, a first signal charge; and

(b) a first transistor having at least one electrode structured and arranged so as to generate, in response to light incident on said electrode, a second signal charge;

the first transistor being positioned and arranged within the device in one of the two following ways;

(i) the first transistor being positioned and arranged within the device to function as an amplification transistor, the said electrode comprising a gate of the first transistor connected to the photosensitive element in such a way as to be capable of receiving the first signal charge; and

(ii) the first transistor being positioned and arranged within the device to function as a reset transistor, connected to the photosensitive element in such a way as to be able to remove the first signal charge from the device, the said electrode comprising a reset drain of the reset transistor,

wherein the photosensitive element and the first transistor are positioned together within the device so as to facilitate formation of an extended array of such devices.

39. An photosensitive array comprising multiple instances of the device of claim 38.

40. An image sensor array comprising a regular array of pixel elements formed on a single semiconductor substrate, the array of pixel elements including at least one first pixel element, said at least one first pixel element comprising at least first and second photosensitive areas, said at least first and second photosensitive areas of said at least one first pixel element each being capable of providing an output signal in response to incident light, the value of any one said output signal being independent of any other said output signal.

41. The image sensor array of claim 40 wherein the array of pixel elements is a rectangular array.

42. The image sensor array of claim 41 wherein the array of pixel elements is a one-dimensional array.

43. The image sensor array of claim 41 wherein the array of pixel elements is a two-dimensional array.

44. The image sensor array of claim 40 wherein the array further includes at least one second pixel element, said at least one second pixel element including one and only one photosensitive area.

45. The image sensor array of claim 44 wherein each pixel includes an amplifier and the output signal from the first photosensitive area is read out via the amplifier.

46. The image sensor array of claim 45 wherein the output signal from the second photosensitive area is read out via said amplifier.

47. The image sensor array of claim 45 wherein the amplifier is a junction-field-effect transistor.

48. The image sensor array of claim 45 further including a reset interconnection and wherein the second photosensitive area is read out via the reset interconnection.

49. The image sensor array of claim 48 wherein the second photosensitive area comprises at least a portion of a reset drain.

50. The image sensor array of claim 48 wherein the second photosensitive area is permanently electrically connected to said reset interconnection.

51. The image sensor array of claim 48 wherein the second photosensitive area is capable of being intermittently electrically connected to said reset interconnection.

52. The image sensor array of claim 51 further comprising inter-pixel switches capable of electrically connecting a second photosensitive area of one pixel with an area of another pixel, and wherein the second photosensitive area is intermittently electrically connected to said reset interconnection via a pixel other than said at least one first pixel.

53. The image sensor array of claim 48 further comprising a switch arranged so as to be able to change between a first state in which a driving pulse is supplied to the reset interconnection and a second state in which an output signal may be read from the reset interconnection.

54. The image sensor array of claim 44 wherein each first pixel of the array is associated with a first on-chip microlens so arranged as to focus incident light on the first photosensitive area of said first pixel, and each second pixel of the array is associated with the first or a second on-chip microlens so arranged as to focus incident light on the one and only one photosensitive area of said second pixel, the first microlens pixel being shaped and positioned with respect to said first pixel in a fashion identical to how the first or the second microlens is shaped and positioned with respect to said second pixel, the first microlens not extending above the second photosensitive area.

55. The image sensor array of claim 54 wherein the first microlens is cylindrical.

56. The image sensor array of claim 54 wherein the first microlens is semispherical.

57. The image sensor array of claim 44 further comprising an on-chip microlens over the first photosensitive area and no microlens over the second photosensitive area.

58. The image sensor array of claim 57 wherein the second pixel is not adjacent to the first pixel and further comprising an on-chip microlens substantially the same size as the second pixel positioned over the one and only one photosensitive area.

59. The image sensor array of claim 44 further comprising on-chip microlenses over each of the first and second pixels, said on-chip microlenses being virtually identical except for a hole over the second photosensitive area of the first pixel.

60. The image sensor array of claim 59 wherein the hole has sidewalls having a reflective layer thereon.

61. The image sensor array of claim 44 further comprising a first on-chip microlenses over each at least one first pixel, said on-chip microlens having a hole over the second photosensitive area of the first pixel, the second pixel having a second on-chip microlens virtually identical to the first microlens.

62. The image sensor array of claim 44 wherein the first photosensitive area is associated with a first on-chip microlens positioned to focus light thereon, and the second photosensitive area is associated with a second on-chip microlens positioned to focus light thereon.

63. The image sensor array of claim 44 including an aperture ratio compensator capable of adjusting the output signals from the first photosensitive area and the one and only one photosensitive area as needed so as to cancel differences in said output signals attributable to a difference between an effective aperture ratio of the first photosensitive area and an effective aperture ratio of the one and only one photosensitive area.

64. The image sensor array of claim 63 wherein the pixels of the array are provided with on-chip microlenses.

65. A fixed-image image capture apparatus comprising an (1) image sensor array for capturing an image formed, for an exposure time, on the image sensor array, and (2) a light-control device;

the image sensor array comprising a regular array of pixel elements formed on a single semiconductor substrate, the array including at least one photosensitive area arranged to be capable of providing an output signal, during an exposure time, indicative of the incident light flux at said photosensitive area during the exposure time, the light-control device arranged to be able to control the duration of the exposure time based on the output signal from the at least one photosensitive area.

66. The fixed-image image capture apparatus of claim 65 further comprising a shutter for starting and ending the exposure time by opening and closing, respectively, and wherein the exposure control device is arranged to be capable of controlling the exposure time by controlling the shutter.

67. The fixed-image image capture apparatus of claim 65 further comprising a strobe for starting and ending the exposure time by turning on and turning off, respectively, and wherein the exposure control device is arranged to be capable of controlling the exposure time by controlling the strobe.

68. A photoelectric conversion device comprising a photoelectric conversion element structured and arranged so as to be able to generate a signal charge in response to incident light, an amplification transistor for amplifying the signal charge from the photoelectric conversion element;

and a reset transistor for resetting the photoelectric conversion device, wherein at least one of

(1) a control electrode of the output amplification transistor and

(2) a main electrode of the reset transistor is structured and arranged so as to be able to generate a signal charge in response to incident light.