Pixel of image sensor and method for fabricating the same

1. A method for fabricating a pixel, the method comprising:

implanting a dopant in a substrate to form an active region, wherein the dopant is deposited pursuant to forming a semiconductor element of the pixel;

forming a first polysilicon layer over the active region;

forming a buried contact structure proximate the active region to provide a conductive path between the first polysilicon layer and the active region, wherein said forming a buried contact structure includes:

forming an insulating layer between the first polysilicon layer and the active region; and

breaking down at least a portion of the insulating layer in the active region through the first polysilicon layer to provide electrical contact between the active region and the first polysilicon layer, wherein said breaking down comprises breaking down at least a portion of the insulating layer using a process including ion implantation; and

forming a second polysilicon layer in electrical contact with the first polysilicon layer, wherein:

the first polysilicon layer has a first thickness;

the second polysilicon layer has a second thickness that is greater than the first thickness; and

the first and second polysilicon layers have a combined polysilicon layer thickness that is substantially the same as the thickness of a gate of a metal-oxide-semiconductor transistor adjacent the active region.

2. The method of claim 1 , wherein the semiconductor element comprises a floating diffusion region.

3. The method of claim 2 , wherein the metal-oxide-semiconductor transistor is a drive transistor adjacent the floating diffusion region.

4. The method of claim 2 , wherein the metal-oxide-semiconductor transistor is a reset transistor adjacent the floating diffusion region.

5. The method of claim 1 , wherein said forming an insulating layer comprises forming an oxide layer between the first polysilicon layer and the active region.

6. A method for fabricating a pixel, the method comprising:

depositing a dopant in a substrate to define an active region in the substrate;

forming a gate oxide layer over the active region;

forming a first polysilicon layer over the gate oxide layer, wherein the first polysilicon layer extends beyond the active region and has a first thickness;

forming a contact mask;

selectively breaking down the gate oxide layer by implanting dopants through the contact mask and the first polysilicon layer, wherein the gate oxide layer is broken down in an area of the gate oxide layer and the first polysilicon layer overlying the active region to provide an electrically-conductive path between the first polysilicon layer and the active region, and wherein another area of the gate oxide layer protected by the contact mask remains non-conductive; and

forming a second polysilicon layer in electrical contact with the first polysilicon layer, wherein the second polysilicon layer has a second thickness that is greater than the first thickness, and wherein the first and second polysilicon layers have a combined polysilicon layer thickness that is substantially the same as the thickness of a gate of a metal-oxide-semiconductor transistor adjacent the region.