Image sensor and a method for forming the same

Abstract

This disclosure provides an image sensor and a method for forming the same. The image sensor includes a substrate, a plurality of image sensing elements, an isolation structure, a first dielectric layer, and a grid pattern. The substrate has a first surface and a second surface that are vertically opposite to each other and includes a plurality of pixel regions and a trench pattern extending from the second surface into the substrate to define the plurality of pixel regions. The plurality of image sensing elements are respectively disposed in the pixel regions and adjacent to the first surface of the substrate. The isolation structure is disposed in the trench pattern. The first dielectric layer is disposed above the second surface of the substrate and includes an opening pattern corresponding to the trench pattern. The opening pattern and the trench pattern overlap in the vertical direction. The grid pattern is disposed in the opening pattern and is horizontally opposite to each other, facing the concave sidewalls of the pixel regions.

Claims

1. An image sensor, comprising: A substrate having a first surface and a second surface opposite to each other in a vertical direction and including a plurality of pixel areas and a trench pattern extending from the second surface into the substrate to define the plurality of pixel areas; a plurality of image sensing elements, respectively disposed in the plurality of pixel areas adjacent to the first surface of the substrate; An isolation structure is provided within the ditch pattern; A first dielectric layer is disposed above the second surface of the substrate; a second dielectric layer is disposed between the substrate and the first dielectric layer, wherein the first dielectric layer includes an opening pattern that exposes the second dielectric layer and corresponds to the trench pattern, the opening pattern and the trench pattern overlapping in the vertical direction; a plurality of spacers are respectively disposed on opposite sidewalls of the opening pattern, wherein the second dielectric layer has grooves that space the plurality of spacers apart from each other, the grooves being recessed from the bottom of the opening pattern toward the second dielectric layer; And a grid pattern, filled into the opening pattern to be disposed on and to separate the plurality of spacers, wherein the grid pattern has concave sidewalls facing each other and toward the pixel area in the horizontal direction.

2. The image sensor as claimed in claim 1, wherein the grid pattern has a Y-shaped profile.

3. The image sensor as claimed in claim 1, wherein: The spacer is disposed between the grid pattern and the first dielectric layer.

4. The image sensor as claimed in claim 3, wherein the spacer has a convex sidewall that contacts the grid pattern.

5. The image sensor as claimed in claim 1, wherein: The grid pattern includes a portion that extends into the groove.

6. The image sensor as claimed in claim 5, wherein the material of the second dielectric layer is different from the material of the first dielectric layer.

7. The image sensor as claimed in claim 5, further comprising: A third dielectric layer is disposed on the first dielectric layer and covers the grid pattern, wherein the third dielectric layer includes a portion of the opening pattern that is filled in.

8. A method for forming an image sensor, comprising: A substrate is provided, wherein the substrate has a first surface and a second surface opposite to each other in a vertical direction and includes a plurality of pixel regions and a trench pattern extending from the second surface into the substrate to define the plurality of pixel regions; an image sensing element is formed in each of the pixel regions adjacent to the first surface of the substrate; and an isolation structure is formed in the trench pattern. A first dielectric layer is formed on the second surface of the substrate; a second dielectric layer is formed on the first dielectric layer, the second dielectric layer including an opening pattern that exposes the first dielectric layer and corresponds to the trench pattern, and the opening pattern and the trench pattern overlap in the vertical direction; a plurality of spacers are formed on opposite sidewalls of the opening pattern, wherein the first dielectric layer has grooves that space the plurality of spacers apart from each other, the grooves being recessed from the bottom of the opening pattern toward the first dielectric layer; A grid pattern is formed in the opening pattern, wherein the grid pattern fills the opening pattern and the groove to be formed on the plurality of spacers and to separate the plurality of spacers, and the grid pattern has concave sidewalls facing each other and facing the pixel area in the horizontal direction.

9. The method as described in claim 8, wherein the step of forming the grid pattern comprises: A grid material layer is formed on the second dielectric layer and filled into the opening pattern, wherein the spacer has convex sidewalls facing each other in the horizontal direction, and the grid material layer is formed on the convex sidewalls of the spacer and extends into the groove; And remove the grid material layer located on the top surface of the second dielectric layer to form the grid pattern.

10. The method of claim 9, wherein the step of forming the spacer comprises: A spacer material layer is formed on the second dielectric layer to fill the opening pattern, wherein the spacer material layer is formed on the sidewall and the bottom surface of the opening pattern; And removing a portion of the spacer material layer located on the top surface of the second dielectric layer and a portion of the spacer material layer located on the bottom surface of the opening pattern to form a plurality of spacers and the grooves that space the plurality of spacers apart from each other.

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