CMOS type solid imaging device
AssigneeSharp Kabushiki Kaisha
InventorTakashi Watanabe
Life of this patent
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Abstract
A solid imaging device including: a semiconductor substrate of a first conductivity type; a layer of a second conductivity type formed on a surface of the semiconductor substrate, the layer at least including a photosensitive portion of the second conductivity type; and a MOS transistor of the second conductivity type coupled to the photosensitive portion, wherein the solid imaging device further includes a layer of the first conductivity type in at least a channel region of the MOS transistor of the second conductivity type, the layer of the first conductivity type having an impurity concentration which is higher than an impurity concentration of the semiconductor substrate, and wherein at least a portion of a boundary of the layer of the second conductivity type is in direct contact with the semiconductor substrate.
Claims11
A solid imaging device comprising:
- a semiconductor substrate of a first conductivity type;
- a first layer of a second conductivity type formed on a surface of the semiconductor substrate, the first layer at least comprising a photosensitive portion of the second conductivity type;
- and
- a first MOS transistor of the second conductivity type coupled to the photosensitive portion,
- wherein the solid imaging device further comprises a layer of the first conductivity type in at least a channel region of the first MOS transistor of the second conductivity type, the layer of the first conductivity type having an impurity concentration which is higher than an impurity concentration of the semiconductor substrate, and
- wherein at least a portion of a boundary of the layer of the second conductivity type is in direct contact with the semiconductor substrate,
- the solid imaging device further comprising CMOS circuitry for controlling a signal from the photosensitive portion, the CMOS circuitry comprising:
- a first well of the first conductivity type having an impurity concentration different from that of the semiconductor substrate, and a second well of the second conductivity type, the first and second wells being formed in the semiconductor substrate of the first conductivity type;
- a second MOS transistor of the second conductivity type formed on the first well of the first conductivity type;
- and
- a third transistor of the first conductivity type formed on the second well of the second conductivity type.
A solid imaging device according comprising:
- a semiconductor substrate of a first conductivity type;
- a layer of a second conductivity type formed on a surface of the semiconductor substrate, the layer at least comprising a photosensitive portion of the second conductivity type;
- and
- a MOS transistor of the second conductivity type coupled to the photosensitive portion,
- wherein the solid imaging device further comprises a layer of the first conductivity type in at least a channel region of the MOS transistor of the second conductivity type, the layer of the first conductivity type having an impurity concentration which is higher than the impurity concentration of the semiconductor substrate, and
- wherein the layer of the second conductivity type further comprises a further layer of the second conductivity type between the photosensitive portion of the second conductivity type and the semiconductor substrate, the further layer of the second conductivity type having an impurity concentration which is lower than an impurity concentration of the photosensitive portion, at least a portion of the further layer of the second conductivity type being in contact with the semiconductor substrate.
Dependencies are inferred from the claim text.