LIGHT DETECTING DEVICE AND METHOD OF CONTROLLING LIGHT DETECTING DEVICE

• US 20100290028A1
• Filed: 05/12/2010
• Published: 11/18/2010
• Est. Priority Date: 05/13/2009
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: SUGAWARA, Ryoichi, TACHINO, Yoshihide
• Granted Patent: US 8,134,690 B2
• Time in Patent Office: Days
• US Class Current: 356/5.01
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 7/483 Details of pulse systems
• 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 27/14612 involving a transistor
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers

Abstract

A light detecting device includes a well region, a first holding region disposed in a surface portion of the well region, a second holding region and a third holding region disposed in a surface portion of the first holding region, an insulating layer disposed on the second holding region and the third holding region, a first electrode disposed on the second holding region through the insulating layer, and the second electrode disposed on the third holding region through the insulating layer. The first holding region is configured to hold a first carrier generated in the well region. Each of the second holding region and the third holding region is configured to hold a second carrier generated in the well region. The first carrier is one of an electron and a hole, and the second carrier is the other one of the electron and the hole.

Claims

1. A light detecting device comprising:

a semiconductor substrate having a first conductivity type;

an element forming region disposed on a surface of the semiconductor substrate and having the first conductivity type;

a well region disposed in a surface portion of the element forming region and having a second conductivity type;

a first holding region disposed in a surface portion of the well region, having the second conductivity type, and configured to hold a first carrier generated in the well region, the first carrier being one of an electron and a hole;

a second holding region and a third holding region disposed in a surface portion of the first holding region, each of the second holding region and the third holding region having the first conductivity type, each of the second holding region and the third holding region configured to hold a second carrier generated in the well region, the second carrier being the other one of the electron and the hole;

a storing region disposed in the surface portion of the element forming region, having the second conductivity type, and configured to store the first carrier;

a discharging region disposed in the surface portion of the element forming region, having the second conductivity type, and configured to be used for discharging the first carrier;

an insulating layer being light-permeable and disposed on the second holding region and the third holding region;

a first control electrode being light-permeable, disposed on the second holding region through the insulating layer, and configured to control holding of the second carrier in the second holding region;

a second control electrode being light-permeable, disposed on the third holding region through the insulating layer, and configured to control holding of the second carrier in the third holding region;

a transferring electrode being in contact with the well region and the storing region and configured to control transferring of the first carrier or the second carrier between the well region and the storing region;

a discharging electrode being in contact with the well region and the discharging region and configured to control transferring of the first carrier or the second carrier between the well region and the discharging region; and

a resetting electrode being in contact with the storing region and the discharging region and configured to control transferring of the first carrier and the second carrier between the storing region and the discharging region.

2. The light detecting device according to claim 1, wherein

the second holding region and the third holding region have a same dimension.

3. The light detecting device according to claim 1, wherein

the first control electrode and the second control electrode have a same dimension.

4. The light detecting device according to claim 1, wherein

the first conductivity type is one of a P conductivity type and an N conductivity type, and the second conductivity type is the other one of the P conductivity type and the N conductivity type.

5. The light detecting device according to claim 1, wherein

the well region is in contact with the surface of the semiconductor substrate.

6. An apparatus including a plurality of the light detecting devices according to claim 1, the plurality of the light detecting devices arranged one dimensionally or two dimensionally.

7. A method of controlling the light detecting device according to claim 1, comprising:

controlling the first control electrode and the second control electrode so that in a plurality of first carriers and a plurality of second carriers generated in the well region during a light-off time of a light source, the plurality of first carriers is held in the first holding region and the plurality of second carriers is divided equally between the second holding region and the third holding region;

reversing the discharging electrode so that the plurality of first carriers is completely discharged from the first holding region to the discharging region;

reversing the discharging electrode;

controlling the first control electrode and the second control electrode so that in a plurality of first carriers and a plurality of second carriers generated in the well region during a light-on time of the light source, the plurality of first carriers is held in the first holding region and the plurality of second carriers is equally divided between the second holding region and the third holding region;

reversing only one of the first control electrode and the second control electrode so that a part of the plurality of first carriers held in the first holding region recombine with the plurality of second carriers held in one of the second holding region and the third holding region on which the one of the first control electrode and the second control electrode is disposed;

reversing the transferring electrode so that the other part of the plurality of first carriers remaining in the first holding region is completely transferred from the first holding region to the storing region; and

outputting a light detection signal in accordance with the other part of the plurality of first carriers stored in the storing region.

8. The method according to claim 7, wherein

the plurality of first carriers generated in the well region is held in the first holding region, and

the plurality of second carriers generated in the well region is held in at least one of the second holding region and the third holding region.

9. The method according to claim 7, wherein

the controlling the first control electrode and the second control electrode so that the plurality of second carriers is divided equally between the second holding region and the third holding region includes applying a same voltage to the first control electrode and the second control electrode so that a same number of second carriers are generated in the second holding region and the third holding region in accordance with a light.

10. The method according to claim 7, wherein

the one of the first control electrode and the second control electrode are controlled so that the plurality of second carriers held in the one of the second holding region and the third holding region recombine with the part of the plurality of first carriers held in the first holding region.

11. The method according to claim 7, wherein

the light-off time and the light-on time are set to have a same time length so that the other part of the plurality of first carriers that remain in the first holding region after the part of the plurality of first carriers held in the first holding region during the light-on time recombine with the plurality of second carriers held in the one of the second holding region and the third holding region during the light-off time and the light-on time becomes a half of the plurality of first carriers generated during the light-on time.

12. A method of controlling the light detecting device according to claim 1, comprising:

setting a light-off time and a light-on time of a light source to have a same time length;

applying a same voltage to the first control electrode and the second control electrode so that in a plurality of first carriers and a plurality of second carriers generated in the well region during the light-off time in accordance with an intensity of an outside light, the plurality of first carriers is held in the first holding region and the plurality of second carriers is divided equally between the second holding region and the third holding region;

reversing a voltage applied to the discharging electrode so that the plurality of first carriers is completely discharged from the first holding region to the discharging region;

reversing the voltage applied to the discharging electrode;

applying a same voltage to the first control electrode and the second control electrode so that in a plurality of first carriers and a plurality of second carriers generated in the well region during the light-on time in accordance with the intensity of the outside light and an intensity the light source, the plurality of first carriers is held in the first holding region and the plurality of second carriers is divided equally between the second holding region and the third holding region;

reversing the voltage applied to only one of the first control electrode and the second control electrode so that a part of the plurality of first carriers held in the first holding region during the light-on time in accordance with the intensity of the outside light and the intensity of the light source recombine with the plurality of second carriers held in one of the second holding region and the third holding region, on which the one of the first electrode and the second electrode is disposed, during the light-off time and the light-on time in accordance with the intensity of the outside light and the intensity of the light source, and a half of the plurality of first carriers that is generated during the light-on time in accordance with the intensity of the light source remains in the first holding region;

reversing a voltage applied to the transferring electrode so that the half of the plurality of first carriers remaining in the first holding region is completely transferred from the first holding region to the storing region; and

outputting a light detection signal in accordance with the half of the plurality of first carriers stored in the storing region.

13. A method of controlling an apparatus including a pair of the light detecting devices according to claim 1, the pair of the light detecting devices including a first light detecting device and a second light detecting device arranged next to each other, the method of controlling the apparatus including a method in a distance measurement mode for measuring a distance from a light source to an object, the method in the distance measurement mode comprising:

applying a same voltage to the first electrode and the second electrode in the first light detecting device so that in a plurality of first carriers and a plurality of second carriers generated in the well region during a first light-off time of the light source in accordance with an intensity of an outside light, the plurality of first carriers is held in the first holding region and the plurality of second carriers is divided equally between the second holding region and the third holding region;

applied to the discharging electrode in the first light detecting device so that the plurality of first carriers is completely discharged from the first holding region to the discharging region;

reversing the voltage applied to the discharging electrode in the first light detecting device;

irradiating a pulse light from the light source in a first light-on time;

applying a same voltage to the first control electrode and the second control electrode in the first light detecting device so that in a plurality of first carriers and a plurality of second carriers generated in the well region during the first light-on time in accordance with the intensity of the outside light and an intensity of a reflected light of the pulse light from the object, the plurality of first carriers is held in the first holding region and the plurality of second carriers is divided equally between the second holding region and the third holding region;

reversing the voltage applied to only one of the first control electrode and the second control electrode in the first light detecting device so that a part of the plurality of first carriers held in the first holding region during the first light-on time in accordance with the intensity of the outside light and the intensity of the reflected light recombine with the plurality of second carriers held in one of the second holding region and the third holding region, on which the one of the first electrode and the second electrode is disposed, during the first light-off time and the first light-on time in accordance with the intensity of the outside light and the intensity of the reflected light, and a half of the plurality of first carriers that is generated during the first light-on time in accordance with the intensity of the reflected light remains in the first holding region;

reversing a voltage applied to the transferring electrode in the first light detecting device so that the half of the plurality of first carriers remaining in the first holding region is completely transferred from the first holding region to the storing region;

outputting a first light detection signal in accordance with the half of the plurality of first carriers stored in the storing region;

applying a same voltage to the first electrode and the second electrode in the second light detecting device so that in a plurality of first carriers and a plurality of second carriers generated in the well region during a second light-off time of the light source in accordance with the intensity of the outside light, the plurality of first carriers is held in the first holding region and the plurality of second carriers is divided equally between the second holding region and the third holding region;

reversing a voltage applied to the discharging electrode in the second light detecting device so that the plurality of first carriers is completely discharged from the first holding region to the discharging region;

reversing the voltage applied to the discharging electrode in the second light detecting device;

irradiating the pulse light from the light source in a second light-on time;

applying a same voltage to the first control electrode and the second control electrode in the second light detecting device so that in a plurality of first carriers and a plurality of second carriers generated in the well region during the second light-on time in accordance with the intensity of the outside light and the intensity of the reflected light, the plurality of first carriers is held in the first holding region and the plurality of second carriers is divided equally between the second holding region and the third holding region;

reversing the voltage applied to only, one of the first control electrode and the second control electrode in the second light detecting device so that a part of the plurality of first carriers held in the first holding region during the second light-on time in accordance with the intensity of the outside light and the intensity of the reflected light recombine with the plurality of second carriers held in one of the second holding region and the third holding region, on which the one of the first electrode and the second electrode is disposed, during the second light-off time and the second the light-on time in accordance with the intensity of the outside light and the intensity of the reflected light, and a half of the plurality of first carriers that is generated during the second light-on time in accordance with the intensity of the reflected light remains in the first holding region;

reversing a voltage applied to the transferring electrode in the second light detecting device so that the half of the plurality of first carriers remaining in the first holding region is completely transferred from the first holding region to the storing region;

outputting a second light detection signal in accordance with the half of the plurality of first carriers stored in the storing region; and

calculating the distance from the light source to the object based on the first light detection signal and the second light detection signal.

14. The method according to claim 13, wherein:

the first light-off time, the first light-on time, and the pulse light have a first time length;

the second light-off time and the second light-on time have a second time length; and

the second time length is longer than the first time length.

15. The method according to claim 13, further comprising a method in an image pickup mode for picking up an image of the object, the method in the image pickup mode comprising:

applying a same voltage to the first control electrode and the second control electrode in each of the first light detecting device and the second light detecting device so that in a plurality of first carriers and a plurality of second carriers generated in the well region during a light-off time of the light source in accordance with the intensity of the outside light, the plurality of first carriers is held in the first holding region and the plurality of second carriers is equally divided into the second holding region and the third holding region;

reversing the voltage applied to the transferring electrode in each of the first light detecting device and the second light detecting device so that the plurality of first carriers held in the first holding region is completely transferred from the first holding region to the storing region; and

outputting a light detection signal in accordance with the plurality of first carriers stored in the storing region.

16. The method according to claim 15, wherein

the distance measurement mode and the image pickup mode are selectively switchable.