A solid-state imaging device and a method therefore capable of suppressing occurrence of motion distortion are provided. Each pixel includes a photo diode PD which accumulates a charge generated by photo-electric conversion in an accumulation period, a transfer transistor capable of transferring the accumulated charge in a transfer period, a floating diffusion FD to which the charge accumulated in the photo diode PD is transferred, a source-follower transistor which converts the charge of the floating diffusion FD to a voltage signal in accordance with the charge quantity, and a capacity changing portion capable of changing the capacity of the floating diffusion FD in accordance with a capacity changing signal, the capacity of the floating diffusion FD being changed by the capacity changing portion in a predetermined period in one readout period with respect to the accumulation period and a conversion gain being switched in this one readout period.

Semiconductor devices and methods of fabricating such devices are provided. The devices include source and drain regions on one conductivity type separated by a channel length and a gate structure. The devices also include a channel region of the one conductivity type formed in the device region between the source and drain regions and a screening region of another conductivity type formed below the channel region and between the source and drain regions. In operation, the channel region forms, in response to a bias voltage at the gate structure, a surface depletion region below the gate structure, a buried depletion region at an interface of the channel region and the screening region, and a buried channel region between the surface depletion region and the buried depletion region, where the buried depletion region is substantially located in channel region.

A semiconductor device includes a light-receiving element which outputs electric charges in response to incident light, and a drive transistor which is gated by an output of the light-receiving element to generate a source-drain current in proportion to the incident light, wherein the drive transistor include a first gate electrode, a first channel region which is disposed under the first gate electrode, first source-drain regions which are disposed at respective ends of the first channel region and that have a first conductivity type, and a first channel stop region which is disposed on a side of the first channel region, and that separates the light-receiving element and the first channel region, the first channel stop region having a second conductivity type that is different from the first conductivity type.

A change in electrical characteristics of a semiconductor device including an interlayer insulating film over a transistor including an oxide semiconductor as a semiconductor film is suppressed. The structure includes a first insulating film which includes a void portion in a step region formed by a source electrode and a drain electrode over the semiconductor film and contains silicon oxide as a component, and a second insulating film containing silicon nitride, which is provided in contact with the first insulating film to cover the void portion in the first insulating film. The structure can prevent the void portion generated in the first insulating film from expanding outward.

An image sensor may include an array of image sensor pixels. Each pixel may have a photodiode, a charge storage region, and a charge overflow circuit. The charge storage region may be used to operate the image sensor array in global shutter mode. During high light level illumination, the charge overflow circuit may divert charge away from the photodiode such that only a predetermined portion of the accumulated charge remains in the photodiode. During low light level illumination all of the accumulated charge may be stored in the pixel photodiode. The charge overflow circuit may include a transistor and a resistor or capacitor. By implementing a charge overflow circuit, the size of the charge storage region may be reduced while still preserving the high dynamic range and low noise of the image sensor during all light illumination conditions.

An object is to provide a structure of a transistor which has a channel formation region formed using an oxide semiconductor and a positive threshold voltage value, which enables a so-called normally-on switching element. The transistor includes an oxide semiconductor stack in which at least a first oxide semiconductor layer and a second oxide semiconductor layer with different energy gaps are stacked and a region containing oxygen in excess of its stoichiometric composition ratio is provided.

To provide a semiconductor device which has transistor characteristics with little variation and includes an oxide semiconductor. The semiconductor device includes an insulating film over a conductive film and an oxide semiconductor film over the insulating film. The oxide semiconductor film includes a first oxide semiconductor layer, a second oxide semiconductor layer over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer. The energy level of a bottom of a conduction band of the second oxide semiconductor layer is lower than those of the first and third oxide semiconductor layers. An end portion of the second oxide semiconductor layer is positioned on an inner side than an end portion of the first oxide semiconductor layer.

In order to form a light receiving element having high reliability and a MOS transistor together on the same silicon substrate, after forming a gate electrode of the MOS transistor, a gate oxide film in a light receiving element forming region is removed. Then, a thermal oxide film is newly formed in the light receiving element forming region, and ion implantation is performed in the light receiving element forming region through the thermal oxide film such that a shallow pn junction is formed.

Provided is a solid-state imaging device including a lamination-type backside illumination CMOS (Complementary Metal Oxide Semiconductor) image sensor having a global shutter function. The solid-state imaging device includes a separation film including one of a light blocking film and a light absorbing film between a memory and a photo diode.

An image sensor with a pinned photodiode includes a photodiode formed in a substrate by implanting dopants of a first type through one or more dielectric layers formed over the substrate. A pinning layer for the photodiode may be formed by implanting dopants of a second type through the same one or more dielectric layers. The pinning layer may be formed over a photodiode region of the substrate. The concentration of dopants of the second type may have a maximum value in dielectric layers over the photodiode that exceeds the concentration of dopants of the second type in the substrate below. The photodiode and pinning layer may both be formed by implanting ions of the first and second type respectively through a dielectric layer formed after etching away a portion of another dielectric layer, having a different thickness, and having different optical transmission properties than the another dielectric layer.