IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0448615
(2007-12-27)
|
등록번호 |
US-8441619
(2013-05-14)
|
우선권정보 |
JP-2006-356754 (2006-12-29) |
국제출원번호 |
PCT/JP2007/075413
(2007-12-27)
|
§371/§102 date |
20100108
(20100108)
|
국제공개번호 |
WO2008/081997
(2008-07-10)
|
발명자
/ 주소 |
- Hashimoto, Yusuke
- Tsunesada, Fumi
- Imai, Kenji
- Takada, Yuji
|
출원인 / 주소 |
|
대리인 / 주소 |
Edwards Wildman Palmer LLP
|
인용정보 |
피인용 횟수 :
0 인용 특허 :
5 |
초록
▼
A photodetector capable of improving dynamic range for input signals is provided. This photodetector includes a photoelectric converting portion, a charge separating portion, a charge accumulating portion, a barrier electrode formed the charge separating portion and the charge accumulating portion,
A photodetector capable of improving dynamic range for input signals is provided. This photodetector includes a photoelectric converting portion, a charge separating portion, a charge accumulating portion, a barrier electrode formed the charge separating portion and the charge accumulating portion, and a barrier-height adjusting portion electrically connected to the barrier electrode. Undesired electric charges such as generated when environment light is incident on the photoelectric converting portion are removed by the charge separating portion. A potential barrier with an appropriate height is formed under the barrier electrode by applying a voltage to the barrier electrode according to an electric charge amount supplied from the charge separating portion to the barrier-height adjusting portion. Electric charges flowing from the charge separating portion into the charge accumulating portion over the potential barrier are provided as an output of the photodetector.
대표청구항
▼
1. A photodetector comprising: a semiconductor substrate;a photoelectric converting portion formed in said semiconductor substrate to generate electric charges corresponding to a received light amount;a charge separating portion having a separation electrode formed on a general surface of said semic
1. A photodetector comprising: a semiconductor substrate;a photoelectric converting portion formed in said semiconductor substrate to generate electric charges corresponding to a received light amount;a charge separating portion having a separation electrode formed on a general surface of said semiconductor substrate;a charge accumulating portion having an accumulation electrode formed on the general surface of said semiconductor substrate;a barrier electrode formed on the general surface of said semiconductor substrate between said separation electrode and said accumulation electrode;a barrier-height adjusting portion electrically connected to said barrier electrode; anda charge discarding portion; wherein said charge separating portion is configured to separate undesired electric charges from the electric charges generated by said photoelectric converting portion by use of a potential barrier, which is formed in said semiconductor substrate under said barrier electrode by applying a voltage to said barrier electrode,said barrier-height adjusting portion determines the voltage applied to said barrier electrode according to an electric charge amount supplied from said photoelectric converting portion to adjust a height of said potential barrier, the electric charge amount supplied from said photoelectric converting portion based upon an amount of light received;said charge accumulating portion is configured to accumulate effective electric charges that are electric charges flowing from said charge separating portion into said charge accumulating portion over said potential barrier,said charge discarding portion is configured to discard the undesired electric charges separated by said charge separating portion, andthe effective electric charges accumulated in said charge accumulating portion are provided as an output of the photodetector,wherein said barrier electrode is formed on said semiconductor substrate through an insulating layer,said photoelectric converting portion, said charge separating portion, said barrier electrode and said charge accumulating portion are aligned in a row, andsaid barrier-height adjusting portion and said charge discarding portion are provided at one side of said row such that said barrier-height adjusting portion is positioned adjacent to said charge separating portion, and said charge discarding portion is positioned adjacent to said photoelectric converting portion. 2. The photodetector as set forth in claim 1, wherein said barrier-height adjusting portion determines the voltage applied to said barrier electrode according to the electric charge amount supplied from said photoelectric converting portion through said charge separating portion. 3. The photodetector as set forth in claim 1, wherein said photoelectric converting portion comprises a plurality of sensitivity control electrodes formed on the general surface of said semiconductor substrate, and a potential well having a desired aperture area is formed in said semiconductor substrate by controlling a voltage applied to each of said sensitivity control electrodes. 4. The photodetector as set forth in claim 1, comprises a pair of slit regions formed in said semiconductor substrate so as to straddle between said separation electrode and said barrier electrode, and spaced from each other in a direction orthogonal to said row, and said slit regions have a same conductive type as another region other than said slit regions, which straddles between said separation electrode and said barrier electrode, and have a higher impurity concentration than said another region. 5. The photodetector as set forth in claim 1, further comprising a buffer electrode formed on the general surface of said semiconductor substrate between said barrier electrode and said accumulation electrode, and a voltage applied to said buffer electrode is controlled such that a potential developed in said semiconductor substrate under said buffer electrode is between a potential developed in said semiconductor substrate under said barrier electrode and a potential developed in said semiconductor substrate under said accumulation electrode. 6. The photodetector as set forth in claim 1, further comprising a barrier layer formed in said semiconductor substrate under said barrier-height adjusting portion to block a movement of electric charges from a deep portion of said semiconductor substrate into said barrier-height adjusting portion. 7. The photodetector as set forth in claim 1, further comprising a transfer gate electrode formed on the general surface of said semiconductor substrate between said charge separating portion and said barrier-height adjusting portion, and a potential adjusting portion formed adjacent to said barrier-height adjusting portion, a charge transfer channel is formed in said semiconductor substrate under said transfer gate electrode and between said charge separating portion and said barrier-height adjusting portion by controlling a voltage applied to said transfer gate electrode, andsaid potential adjusting portion has an impurity concentration controlled such that electric charges move in said charge transfer channel from said charge separating portion toward said barrier-height adjusting portion. 8. The photodetector as set forth in claim 1, wherein said charge discarding portion is located in the vicinity of said photoelectric converting region and said charge separation region to discard excess electric charges from said photoelectric converting portion as well as the undesired electric charges from said charge separation region. 9. The photodetector as set forth in claim 8, wherein said charge discarding portion comprises a first charge discarding portion configured to discard the excess electric charges, and a second charge discarding portion configured to discard the undesired electric charges. 10. The photodetector as set forth in claim 9, wherein said charge discarding portion is configured to discard the excess electric charges from said photoelectric converting portion through said first charge discarding portion at a first time and is configured to discharge the undesired electric charges from said charge separating portion through said second charge discarding portion at a second time, wherein the first time is different from the second time. 11. The photodetector as set forth in claim 1, wherein a plurality of pixels are formed on said semiconductor substrate, each of which comprises said photoelectric converting portion, said charge separating portion, said charge accumulating portion, said barrier-height adjusting portion and said barrier electrode. 12. A spatial information detecting device comprising: a light emission source configured to intermittently project light into a target space;the photodetector as set forth in of claim 1, which is disposed to receive light from said target space;a control portion configured to control light emission of said light emission source, and voltages applied to said separation electrode, said accumulation electrode and said charge discarding portion of the photodetector; anda signal processing portion configured to extract spatial information of said target space from an output of the photodetector;wherein said control portion moves electric charges, which are generated by said photoelectric converting portion within a rest period where the light is not projected from said light emission source to said target space, into said barrier height adjusting portion to form said potential barrier with a height determined according to the electric charge amount in said barrier height adjusting portion, the electric charge amount supplied from said photoelectric converting portion based upon an amount of light received,said charge separating portion removes the undesired electric charges from electric charges, which are generated by said photoelectric converting portion within a lighting period where the light is projected from said light emission source into said target space,the electric charges flowing from said charge separating portion into said charge accumulating portion over said potential barrier are accumulated as the effective electric charges in said charge accumulating portion,the undesired electric charges separated by said charge separating portion are discarded through said charge discarding portion prior to said rest period, andthe effective electric charges accumulated in said charge accumulating portion are provided as the output of the photodetector. 13. The spatial information detecting device as set forth in claim 12, wherein said photoelectric converting portion has a plurality of sensitivity control electrodes on the general surface of said semiconductor substrate, said control portion sends a modulation signal to said light emission source such that light intensity-modulated at the modulation signal is projected into said target space within said lighting period, and controls voltages applied to said sensitivity control electrodes such that an aperture area of a potential well formed in said semiconductor substrate under each of said sensitivity control electrodes changes at a timing synchronized with the modulation signal, thereby generating the electric charges corresponding to a phase zone of the modulation signal by said photoelectric converting portion, andsaid signal processing portion detects a distance to an object in said target space as the spatial information from outputs of the photodetector, which are obtained at plural phase zones of the modulation signal.
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