Solid state image sensor

• US 4,591,917 A
• Filed: 10/06/1983
• Issued: 05/27/1986
• Est. Priority Date: 10/07/1982
• Status: Expired due to Term

• Current Assignee: Tokyo Shibaura Denki Kabushiki Kaisha
• Original Assignee: Tokyo Shibaura Denki Kabushiki Kaisha
• Inventors: Suzuki, Nobuo
• Primary Examiner(s): Rubinson, Gene Z.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/539,424
• Time in Patent Office: 964 Days
• Field of Search: 358/213, 358/212, 358/225, 357/24 LR
• US Class Current: 348/312
• CPC Class Codes: H01L 27/14831 Area CCD imagers
• CPC Class Codes: H04N 25/72 using frame transfer [FT]

Abstract

A solid state image sensor is constituted so as to transfer signal charges produced in response to optical irradiation to readout means (22) provided at the end in the direction of alignment of the transfer electrodes with charge transfer channels (30) located below a plurality of transfer electrode array (27) arranged on a semiconductor wafer (20) through an insulating film (32) and to output them from the readout means. The solid state image sensor is provided with means for controlling applied voltage comprising voltage sources (37, 38) of low and high voltages, multi-phase clock source (36) and switch means (34). The applied voltage control means, at a time period of optical irradiation, is operative to apply a voltage to form a deep potential well in transfer channels located below either odd number of transfer electrodes or even number thereof, and form a potential barrier in the transfer channels located below the other electrodes, thereby to store signal charges in the potential well. Further, this applied voltage control means, at a time period of signal readout in a light-interrupted condition, is operative to apply charge transfer multi-phase clocks from transfer electrodes closest to signal readout means sequentially towards those located apart therefrom.

Claims

1. A solid state image sensor in which charge transfer channels are formed below an array, said array comprising an alternating succession of first and second transfer electrodes of a plurality of transfer electrodes aligned in a first direction, on a semiconductor wafer through an insulating film, the charge transfer channels allowing signal charges produced as an output of photoelectric converting means responsive to optical irradiation to be transferred to signal readout means having a first side adjacent to the transfer electrode array for defining the charge transfer channels to output the signal charges therefrom,

the improvement comprising means for controlling applied voltage, wherein:

(a) during optical irradiation of said photoelectric converting means, said applied voltage controlling means applies a voltage to form a deep potential well in a transfer channel below said first electrodes, and to form a potential barrier in a transfer channel located below said second electrodes, thereby to store signal charges in said potential well, and

(b) during reading out of said signal charges by means of signal readout means after illumination of said photoelectric converting means, said applied voltage control means applies a charge transfer multi-phase clock to a pair of first and second transfer electrodes adjacent to the signal readout means and sequentially applies a charge transfer multiphase clock to each successive pair of first and second transfer electrodes, to effect a readout.

2. A solid state image sensor according to claim 1, wherein said applied voltage control means comprises voltage source means for supplying voltages thereby to form said deep potential well and potential barrier, multi-phase clock source means for supplying transfer clocks, and electronic switch means for switching the voltage supplied from said voltage source means and said transfer clocks.

3. A solid state image sensor according to claim 1, wherein said transfer electrodes are comprised of a transparent electrodes.

4. A solid state image sensor according to claim 1, wherein said signal readout means is provided at said first side in the direction of alignment of the transfer electrode array for defining the charge transfer channels.

5. A solid state image according to claim 1, wherein said signal readout means is provided at said first side of said transfer electrode array in the direction of alignment of the transfer electrode array for defining the charge transfer channels, and a second signal readout means is provided at a second side of said transfer electrode array in the direction of alignment of the transfer electrode array for defining the charge transfer channels.

6. A solid state image sensor according to claim 1, wherein said photoelectric converting means is comprised of a photodiode of P-N junction type, said diode being arranged in the vicinity of said transfer electrodes.

7. A solid state image sensor according to claim 1, wherein said transfer channel is formed with a buried channel.

8. A solid state image sensor according to claim 1, wherein said photoelectric converting means comprises a shutter for interrupting light irradiated on said photoelectric converting means.

9. A solid state image sensor according to claim 1, wherein each of said signal charges produced by said photoelectric converting means is stored in two of said transfer electrodes.

10. The solid state image sensor of claim 1, wherein said readout means is comprised of a plurality of third transfer electrodes disposed substantially perpendicular to said first and second transfer electrodes.

11. A method of sensing an image comprising the steps of:

(a) draining signal charges and noise charges from a plurality of transfer channels disposed below a photosensitive element;

(b) forming potential wells in a first group of said transfer channels;

(c) forming potential barriers in a second group of said transfer channels;

(d) arranging the transfer channels of said first group of transfer channels in alternating succession with the transfer channels of said second group of transfer channels to form adjacent pairs of barrier-well transfer channels;

(e) exposing said photosensitive element to an incident optical signal;

(f) reading out signal charges into a readout device, from a first pair of transfer electrodes superposed above a first adjacent pair of transfer channels immediately adjacent said readout device; and

(g) reading out signal charges from additional successive pairs of transfer electrodes superposed above successive adjacent pairs of transfer channels.