Photoelectric conversion element having a plurality of semiconductor regions and including conductive layers provided on each isolation element region
To provide a solid-state image pickup apparatus with little or no difference in the dark currents between adjacent photoelectroc conversion elements and providing a high sensitivity and a low dark current even in-a high-speed readout operation. A well is formed on a wafer, and diffusion layers are formed in the well to constitute a photodiode. A well contact is formed between the diffusion layers. Element isolation regions are provided between the well contact and the diffusion layers, and conductive layers are provided respectively on the element isolation regions, thereby reducing a difference in the minority carrier diffusions from the well contact to the photodiodes (diffusion layers).
1. An image pickup apparatus comprising:
a plurality of a photoelectric conversion element having a first semiconductor region of a first conductive type, a plurality of second semiconductor regions of a second conductive type forming a junction with the first semiconductor region, a third semiconductor region of a first conductive type, provided in the first semiconductor region between mutually adjacent second semiconductor regions;
an element isolation region respectively provided between the third semiconductor region and each of the mutually adjacent second semiconductor regions; and
a conductive layer provided on each element isolation region.
2. An image pickup apparatus according to claim 1 , wherein distances between the third semiconductor region and the adjacent second semiconductor regions are the same.
3. An image pickup apparatus according to claim 1 , wherein the third semiconductor region is provided for fixing a potential of the first semiconductor region.
4. An image pickup apparatus according to claim 1 , wherein the conductive layers provided on the respective element isolation regions are formed by a same layer.
5. An image pickup apparatus according to claim 3 , wherein the second semiconductor regions are arranged one-dimensionally or two-dimensionally, in which the plural second semiconductor regions arranged along a direction form a group by each predetermined number, and the third semiconductor region is provided for each group; and
the third semiconductor region is provided in the first semiconductor region between the second semiconductor regions which are at least partially adjacent in the group.
6. An image pickup apparatus according to claim 3 , wherein the second semiconductor regions are arranged one-dimensionally or two-dimensionally, in which the plural second semiconductor regions arranged along a direction form a group by each predetermined number; and
the third semiconductor region is provided in the first semiconductor region between the second semiconductor region in a first group and the second semiconductor group in a second group, adjacent to the second semiconductor in the first group.
7. An image pickup apparatus according to claim 6 , further comprising:
a floating diffusion region provided for each photoelectric device;
a transfer transistor provided for each second semiconductor region for transferring carriers accumulated in each second semiconductor region to the floating diffusion region;
an amplifying transistor of which a gate electrode is connected to the floating diffusion region;
a selecting transistor connected with the amplifying transistor; and
a reset transistor for resetting at least the floating diffusion region;
wherein the conductive layer provided on each element isolation region is formed by a gate electrode of the transfer transistor, a gate electrode of the amplifying transistor, a gate electrode of the selecting transistor, or a gate electrode of the reset transistor.
8. An image pickup apparatus according to claim 7 , wherein the amplifying transistor is provided in common for a group.
9. A solid-state image pickup system comprising:
an image pickup apparatus according to claim 1 ;
an optical system for focusing light onto the solid-state image pickup apparatus; and
a signal processing circuit for processing an output signal from the solid-state image pickup apparatus.