Semiconductor isolation structure and manufacturing method thereof
The present disclosure provides a method for manufacturing a semiconductor isolation structure, including providing a substrate with a top surface; forming a patterned mask over the top surface; forming a trench through the patterned mask in the substrate by a directional etch comprising nitrogen-containing substance, wherein an aspect ratio of the trench is formed to be greater than about 18, and a ratio of a width of a narrowest portion and a width of a widest portion of the isolation region is formed to be greater than about 0.7; and filling the trench with insulating materials. The present disclosure also provides an image sensing device, including a radiation sensing region with a first isolation region separating adjacent radiation detecting units and a peripheral region, wherein an aspect ratio of the first isolation region is greater than about 18.
1. A method for manufacturing a semiconductor isolation structure, comprising:
providing a substrate with a top surface;
forming a patterned mask over the top surface;
forming a trench through the patterned mask in the substrate by a directional etch comprising nitrogen-containing substance, fluorine-containing substance, and oxygen-containing substance, wherein an aspect ratio of the trench is formed to be greater than about 18, and a ratio of a width of a narrowest portion and a width of a widest portion of the isolation region is formed to be greater than about 0.7, nitrogen-containing substance and the fluorine-containing substance being introduced within a ratio of from about 0.8 to about 4; and
filling the trench with insulating materials.
2. The method for manufacturing a semiconductor isolation structure of claim 1 , wherein the forming the patterned mask over the top surface comprises forming the patterned mask exposing a portion of the top surface of the substrate, and a critical dimension of the pattern on the mask is less than about 90 nm.
3. The method for manufacturing a semiconductor isolation structure of claim 1 , wherein the forming the trench through the patterned mask in the substrate by the directional etch further comprises introducing the oxygen-containing substance and the fluorine-containing substance at a ratio of about 1.
4. The method for manufacturing a semiconductor isolation structure of claim 1 , wherein the forming the trench through the patterned mask in the substrate by a directional etch comprises introducing nitrogen gas and SF 6 .
5. A method for manufacturing an image sensing device, comprising:
forming a first isolation region by forming a patterned mask over a surface of a substrate;
forming a trench through the patterned mask in the substrate by a directional etch comprising nitrogen-containing substance, wherein an aspect ratio of the trench is formed to be greater than about 18, the trench with a ratio of a width of a narrowest portion and a width of a widest portion thereof being greater than about 0.7;
filling the trench with insulating materials; and
forming a second isolation region at a peripheral region of the substrate;
wherein the patterned mask is positioned in a radiation sensing region, separating adjacent radiation detecting units, and
wherein the widest portion of the trench is configured to be positioned opposite to a radiation-receiving surface of the image sensing device.
6. The method of claim 5 , wherein the forming the trench through the patterned mask further comprises forming a SiN-based composite layer over a sidewall of the trench.
7. The method of claim 5 , wherein the forming the trench through the patterned mask further comprises forming a SiO-based composites layer over a sidewall of the trench.
8. The method of claim 6 , further comprising forming a protection layer over the SiN-based composite layer by forming an oxide stack with a thickness of from about 20 to about 200 angstroms.
9. The method of claim 5 , wherein the directional etch further comprises fluorine-containing substance and oxygen-containing substance.
10. The method of claim 5 , wherein the directional etch is configured to obtain a concave bottom in the trench.
11. The method of claim 1 , wherein the forming the trench through the patterned mask further comprises forming a SiN-based composite layer over a sidewall of the trench.