TDI-type linear image sensor
In a TDI-type linear image sensor in which pixels are constituted of CCDs (Charge Coupled Devices) of n phases (n being an integer not smaller than 3), a gate opening portion and a gate non-opening portion functioning as a TDI transfer channel ( 15 ) are formed in all of transfer gates of the CCDs of n phases constituting the pixels. Within one pixel pitch in a TDI transfer direction, n microlenses ( 18 ) are formed such that light is concentrated at the gate non-opening portion formed at the transfer gate of each phase.
1. A TDI-type linear image sensor comprising:
plural pixels, each constituted of n phases (n being an integer not smaller than 3), each phase of each pixel comprising
a gate opening portion and a gate non-opening portion functioning as a TDI transfer channel formed in a transfer gate of the respective phase of the respective pixel,
a separate microlens being formed such that light is gathered onto the gate opening portion of the respective phase of the respective pixel.
2. The TDI-type linear image sensor according to claim 1 , wherein
the gate opening portions of two adjacent pixels are not connected to each other at any portion.
3. The TDI-type linear image sensor according to claim 1 , wherein
an embedding photodiode is formed in the gate opening portion formed in the transfer gate of each phase, and said embedding photodiode is formed from a high-concentration impurity region of a first conductivity type formed in a surface of a silicon substrate and an impurity region of a second conductivity type formed in contact with said high-concentration impurity region of the first conductivity type in a deeper region of the silicon substrate.
4. The TDI-type linear image sensor according to claim 3 , wherein
said high-concentration impurity region of the first conductivity type of said embedding photodiode is in contact with the impurity region of the first conductivity type formed between said gate opening portion and the gate non-opening portion of an adjacent pixel.
5. The TDI-type linear image sensor according to claim 3 , wherein
the impurity region of the first conductivity type is formed between embedding photodiodes formed in the gate opening portions of two adjacent pixels.
6. The TDI-type linear image sensor according to claim 3 , wherein
the transfer gates of two adjacent pixels are disconnected from each other,
the TDI-type linear image sensor further comprises:
a metal interconnection provided directly above said TDI transfer channel; and
a gate contact connecting said metal interconnection and said transfer gate to each other, and
a voltage is supplied through said metal interconnection and said gate contact.
7. The TDI-type linear image sensor according to claim 3 , wherein
the embedding photodiodes formed in the gate opening portions of the two adjacent pixels are connected to each other through the impurity region of the first conductivity type.
8. The TDI-type linear image sensor according to claim 1 , wherein
said microlens has a radius of curvature in the TDI transfer direction greater than a radius of curvature in a direction perpendicular to said TDI transfer direction.
9. The TDI-type linear image sensor according to claim 1 , wherein
said n is set to 4,
said gate opening portion is formed at a pitch of ½ of a pixel pitch in said TDI transfer direction which is a column direction and a direction perpendicular to said TDI transfer direction which is a row direction,
a column of said gate opening portions adjacent to one another is arranged as displaced by ¼ of the pixel pitch in said TDI transfer direction,
one pixel is formed by said gate opening portions in two rows and two columns, and
a transfer channel extends in the TDI transfer direction with said gate opening portions in the two columns being interposed.
10. The TDI-type linear image sensor according to claim 9 , wherein
said microlenses are formed at a pitch of ½ of the pixel pitch in said column direction and said row direction, and
the column of the microlenses adjacent to one another is arranged as displaced by ¼ of the pixel pitch in said TDI transfer direction such that light is gathered onto said gate opening portion.
11. The TDI-type linear image sensor according to claim 9 , wherein
an embedding photodiode is formed in said gate opening portion formed in the transfer gate of each phase, and
said embedding photodiode is formed from a high-concentration impurity region of a first conductivity type formed in a surface of a silicon substrate and an impurity region of a second conductivity type formed in contact with said high-concentration impurity region of the first conductivity type in a deeper region of the silicon substrate.
12. The TDI-type linear image sensor according to claim 9 , wherein
a gate length of the TDI transfer gate of each phase is extended in the transfer direction only around said gate opening portion.
13. The TDI-type linear image sensor according to claim 9 , wherein
said transfer channel and the impurity region of the second conductivity type are formed between the gate opening portions in two columns adjacent to each other, so as to extend alternately in said TDI transfer direction.
14. The TDI-type linear image sensor according to claim 13 , wherein
the impurity region of the first conductivity type is formed directly under a TDI transfer gate region where no said gate opening portion is formed, of TDI transfer gate regions lying between said transfer channel and said impurity region of the second conductivity type.
15. The TDI-type linear image sensor according to claim 14 , wherein
the high-concentration impurity region of the first conductivity type is formed in a region except for said gate opening portion, said transfer channel, said impurity region of the second conductivity type, and said impurity region of the first conductivity type.
16. The TDI-type linear image sensor according to claim 9 , wherein
the impurity region of the first conductivity type is formed in a region except for said gate opening portion and said transfer channel.