A semiconductor device includes a semiconductor substrate, a photo sensing region, and a plurality of nanostructures. The semiconductor substrate has a first dopant. The photo sensing region is embedded in the semiconductor substrate, has a top surface level with a top surface of the semiconductor substrate, and has a second dopant that is of a different conductivity type than the first dopant. The plurality of nanostructures is on the photo sensing region and is made of a material the same as the photo sensing region.

A semiconductor device includes a substrate, a photo sensing region, and a plurality of semiconductor plugs. The photo sensing region is in the substrate. The photo sensing region forms a p-n junction with the substrate. The semiconductor plugs extend from above the photo sensing region into the photo sensing region.

A semiconductor device includes a substrate, a photo sensing region, and a plurality of semiconductor plugs. The photo sensing region is in the substrate. The photo sensing region forms a p-n junction with the substrate. The semiconductor plugs extend from above the photo sensing region into the photo sensing region.

An image sensor device includes nanostructures for improving light absorption efficiency. The image sensor device includes a substrate, a light absorption region, and a nanostructure array. The light absorption region is over the substrate. The nanostructure array us over the light absorption region. The nanostructure array includes a plurality of nanostructures repeatedly arranged from a top view.

A semiconductor device includes a semiconductor substrate, a photo sensing region, and a plurality of nanostructures. The semiconductor substrate has a first dopant. The photo sensing region is embedded in the semiconductor substrate, has a top surface level with a top surface of the semiconductor substrate, and has a second dopant that is of a different conductivity type than the first dopant. The plurality of nanostructures is on the photo sensing region and is made of a material the same as the photo sensing region.

A method of forming a semiconductor device includes forming a photo sensing region in a semiconductor substrate, wherein the semiconductor substrate is of a first type dopant and the photo sensing region is of a second type dopant that has a different conductivity type than the first type dopant; forming a nanostructure layer in contact with an interface between the photo sensing region and the semiconductor substrate; and etching the nanostructure layer until exposing the photo sensing region to form a plurality of nanostructures.

A method of forming a semiconductor device includes forming a photo sensing region in a semiconductor substrate, wherein the semiconductor substrate is of a first type dopant and the photo sensing region is of a second type dopant that has a different conductivity type than the first type dopant; forming a nanostructure layer in contact with an interface between the photo sensing region and the semiconductor substrate; and etching the nanostructure layer until exposing the photo sensing region to form a plurality of nanostructures.

A semiconductor device is provided, which includes a substrate and at least one nanostructure. The substrate has sensing pixels, and each of the sensing pixels has a photo sensing region for absorbing incident light. The nanostructure is directly on the photo sensing region. The nanostructure of each of the sensing pixels has a projected portion on an upper surface of the substrate, and a circle equivalent diameter of the projected portion of the nanostructure of each of the sensing pixels is substantially within a wavelength range of 100 nm to 1900 nm of the incident light configured to enter the substrate through the nanostructure.

A semiconductor device is provided, which includes a substrate and at least one nanostructure. The substrate has sensing pixels, and each of the sensing pixels has a photo sensing region for absorbing incident light. The nanostructure is directly on the photo sensing region. The nanostructure of each of the sensing pixels has a projected portion on an upper surface of the substrate, and a circle equivalent diameter of the projected portion of the nanostructure of each of the sensing pixels is substantially within a wavelength range of 100 nm to 1900 nm of the incident light configured to enter the substrate through the nanostructure.