Semiconductor device and method of forming the same
A method for manufacturing a semiconductor device includes depositing a first protective layer over a first conductive feature and a second conductive feature. The first protective layer covers respective sidewalls and top surfaces of the first conductive feature and the second conductive feature. A portion of the first protective layer between the first conductive feature and the second conductive feature is removed. After removing the portion of the first protective layer, an intermetal dielectric layer is formed between the first conductive feature and the second conductive feature.
1 . A method for manufacturing a semiconductor device, the method comprising:
forming a first metal line and a second metal line over a substrate;
conformally depositing a first dielectric layer over the first metal line and the second metal line, wherein the first dielectric layer comprises a dent between the first metal line and the second metal line;
recessing the first dielectric layer with an anisotropic etch process, wherein after the anisotropic etch process the dent extends below top surfaces of the first metal line and the second metal line;
forming a first protective layer over the first dielectric layer;
removing a portion of the first protective layer over the dent, wherein remaining portions of the first protective layer have respective umbrella shaped profiles in a cross-sectional view;
etching a hole through the first dielectric layer in the position of the dent; and
widening the hole into a space with an isotropic etch process.
2 . The method of claim 1 , wherein the first protective layer comprises a nitride.
3 . The method of claim 2 , wherein the nitride is Si 3 N 4 .
4 . The method of claim 1 , further comprising forming an air gap by depositing a second dielectric layer over the first protective layer and the space.
5 . The method of claim 4 , wherein a highest point of the air gap is below a top surface of the first protective layer.
6 . The method of claim 4 , wherein curved tips of the first protective layer extend over the air gap.
7 . The method of claim 1 , further comprising forming a second protective layer over sidewalls of the first metal line and the second metal line.
8 . The method of claim 7 , wherein the first protective layer and the second protective layer are a same material.
9 . A method for manufacturing a semiconductor device, the method comprising:
forming a first dielectric layer over a first metal line and a second metal line, wherein the first dielectric layer comprises a dent between the first metal line and the second metal line;
extending the dent below top surfaces of the first metal line and the second metal line by performing a first etch process on the first dielectric layer;
forming a protective layer over the first dielectric layer;
forming umbrella shaped profiles in the protective layer by removing a portion of the protective layer over the dent;
etching a hole through the first dielectric layer in the position of the dent; and
widening the hole into a space with a second etch process.
10 . The method of claim 9 , wherein the first etch process is an anisotropic etch process.
11 . The method of claim 9 , wherein the second etch process is an isotropic etch process.
12 . The method of claim 9 , wherein forming the protective layer comprises forming a curved corner profile of the protective layer in a cross-sectional view.
13 . The method of claim 9 , wherein the protective layer comprises a nitride.
14 . The method of claim 9 , further comprising forming a second dielectric layer over the umbrella shaped profiles of the protective layer.
15 . A method for manufacturing a semiconductor device, the method comprising:
conformally depositing a first dielectric layer over a first metal line and a second metal line;
recessing the first dielectric layer with a first etch process, a dent between the first metal line and the second metal line extending below top surfaces of the first metal line and the second metal line after the first etch process;
forming a protective layer over the first dielectric layer;
removing a portion of the protective layer over the dent, remaining portions of the protective layer having respective umbrella shaped profiles in a cross-sectional view;
etching a hole through the first dielectric layer in the position of the dent; and
widening the hole with a second etch process.
16 . The method of claim 15 , wherein the first etch process is an anisotropic etch process.
17 . The method of claim 15 , wherein the second etch process is an isotropic etch process.
18 . The method of claim 15 , wherein the protective layer comprises silicon nitride.
19 . The method of claim 15 , wherein curved tips of the protective layer extend over the hole after the second etch process.
20 . The method of claim 15 , further comprising sealing an air gap by forming a second dielectric layer over the hole.