Method for forming shallow trench isolation in semiconductor device
First Claim
1. A method for forming a shallow trench isolation structure for a semiconductor device, comprising the steps of:
- forming a dielectric layer and an amorphous silicon layer over a semiconductor substrate;
forming a mask layer over the amorphous silicon layer;
patterning the mask layer, the amorphous silicon layer, the dielectric layer, and the substrate to form a trench in the substrate;
growing a thermal oxide layer lining the sidewalls of the amorphous silicon layer and the trench, the thermal oxide layer being thinner at the position lining the amorphous silicon layer than at the position lining the trench; and
filling the trench with an isolation layer to form a shallow trench isolation (STI) structure.
1 Assignment
0 Petitions
Accused Products
Abstract
The present invention discloses a method for forming shallow trench isolation in a semiconductor device, particularly a nonvolatile memory device. A dielectric layer, an amorphous silicon layer, and a mask layer are sequentially formed over a substrate. Isolation trenches are etched in the substrate through the layers. An oxide layer is thermally grown lining the sidewalls of the amorphous silicon layer and the trenches. Due to the lower oxidation rate of amorphous silicon, the liner oxide layer is thinner at the position lining the amorphous silicon layer than at the position lining the trench. The trenches are filled with an isolation layer to form shallow trench isolation (STI) structures. After removing the mask layer, the amorphous silicon layer can be converted into a polysilicon layer to serve as a floating gate for a nonvolatile memory device.
-
Citations
17 Claims
-
1. A method for forming a shallow trench isolation structure for a semiconductor device, comprising the steps of:
-
forming a dielectric layer and an amorphous silicon layer over a semiconductor substrate;
forming a mask layer over the amorphous silicon layer;
patterning the mask layer, the amorphous silicon layer, the dielectric layer, and the substrate to form a trench in the substrate;
growing a thermal oxide layer lining the sidewalls of the amorphous silicon layer and the trench, the thermal oxide layer being thinner at the position lining the amorphous silicon layer than at the position lining the trench; and
filling the trench with an isolation layer to form a shallow trench isolation (STI) structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A method for fabricating a nonvolatile memory device with shallow trench isolation, comprising the steps of:
-
forming a tunnel dielectric layer and an amorphous silicon layer over a substrate;
forming a mask layer over the amorphous silicon layer;
patterning the mask layer, the amorphous silicon layer, the tunnel dielectric layer, and the substrate to form a trench in the substrate;
growing a thermal oxide layer lining the sidewalls of the amorphous silicon layer and the trench, the thermal oxide layer being thinner at the position lining the amorphous silicon layer than at the position lining the trench;
filling the trench with an isolation layer to form a shallow trench isolation (STI) structure;
removing the mask layer; and
sequentially forming an inter-gate dielectric layer and a control gate layer over the substrate, and converting the amorphous silicon layer into a polysilicon layer for serving as a floating gate. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
-
Specification