Semiconductor device structure with air gap for reducing capacitive coupling
The present disclosure provides a semiconductor structure and a method for preparing the semiconductor structure. The semiconductor device structure includes: a first conductive structure and a second conductive structure disposed at different vertical heights over a semiconductor substrate; a first conductive plug and a second conductive plug correspondingly disposed over the first conductive structure and the second conductive structure; a first spacer disposed on a sidewall surface of the first conductive plug; an etch stop layer disposed over the semiconductor substrate, wherein the etch stop layer adjoins the first spacer; and a first inter-layer dielectric (ILD) layer disposed over the etch stop layer and next to the first conductive plug, wherein the first ILD layer is separated from the first spacer by an air gap.
1. A semiconductor device structure, comprising:
a first conductive structure and a second conductive structure disposed at different vertical heights over a semiconductor substrate, wherein a bottom surface of the first conductive structure is vertically higher than a bottom surface of the second conductive structure;
a first conductive plug and a second conductive plug correspondingly disposed over the first conductive structure and the second conductive structure;
a first spacer disposed on a sidewall surface of the first conductive plug;
an etch stop layer disposed over the semiconductor substrate, wherein the etch stop layer adjoins the first spacer; and
a first inter-layer dielectric (ILD) layer disposed over the etch stop layer and next to the first conductive plug, wherein the first ILD layer is separated from the first spacer by an air gap.
2. The semiconductor device structure of claim 1 , further comprising:
a second spacer disposed over the etch stop layer, wherein the second spacer is between the first spacer and the ILD layer, and the air gap is over the second spacer.
3. The semiconductor device structure of claim 2 , wherein the second spacer does not overlap the conductive structure in a direction perpendicular to a top surface of the semiconductor substrate.
4. The semiconductor device structure of claim 2 , further comprising:
a second ILD layer disposed over the first ILD layer, wherein the air gap is enclosed by the second ILD layer, the first ILD layer, the second spacer and the first spacer.
5. The semiconductor device structure of claim 4 , further comprising:
a first conductive contact disposed over the first conductive plug, wherein the first conductive contact is surrounded by the second ILD layer, and the first conductive contact is electrically connected to the first conductive plug.
6. The semiconductor device structure of claim 1 , wherein a bottom surface of the etch stop layer is at a vertical height over a top surface of the first conductive structure.
7. The semiconductor device structure of claim 1 , wherein the first conductive plug has a first height, the second conductive plug has a second height, and the second height is greater than the first height.
8. The semiconductor device structure of claim 1 , wherein the first conductive plug has a first top surface, the second conductive plug has a second top surface, and the second top surface is substantially level with the first top surface.
9. The semiconductor device structure of claim 1 , wherein the first conductive plug has a first height, the second conductive plug has a second height, the first conductive structure has a third height, and the second height is substantially the same as a summation of the first height and the third height.
10. The semiconductor device structure of claim 1 , wherein the first conductive plug has a bottom surface substantially level with a bottom surface of the etch stop layer, and the second conductive plug has a bottom surface substantially lower than the bottom surface of the etch stop layer.
11. A semiconductor device structure, comprising:
a first conductive structure and a second conductive structure disposed at different vertical heights over a semiconductor substrate, wherein a bottom surface of the first conductive structure is vertically higher than a bottom surface of the second conductive structure;
a first conductive plug and a second conductive plug correspondingly disposed over the first conductive structure and the second conductive structure, wherein the first conductive plug has a first height, the second conductive plug has a second height, and the second height is greater than the first height;
a first spacer and a second spacer correspondingly disposed on a sidewall surface of the first conductive plug and a sidewall surface of the second conductive plug;
an etch stop layer disposed over the conductive structure, wherein the etch stop layer adjoins a sidewall surface of the first spacer and a sidewall surface of the second spacer;
a first inter-layer dielectric (ILD) layer disposed over the etch stop layer and next to the first spacer and the second spacer, wherein the first ILD layer is separated from the first spacer by a first air gap and the first ILD layer is separated from the second spacer by a second air gap; and
a second ILD layer disposed over the first ILD layer, wherein the first air gap and the second air gap are sealed by the second ILD layer.
12. The semiconductor device structure of claim 11 , wherein the second spacer is between the air gap and the etch stop layer.
13. The semiconductor device structure of claim 12 , wherein a material of the second spacer is different from a material of the first spacer and a material of the first ILD layer.
14. The semiconductor device structure of claim 11 , wherein the first spacer and the etch stop layer are made of silicon nitride.
15. The semiconductor device structure of claim 11 , wherein a bottom surface of the etch stop layer is at a vertical height over a bottom surface of the first spacer.
16. The semiconductor device structure of claim 11 , wherein the air gap does not overlap the conductive structure in a direction perpendicular to a top surface of the semiconductor substrate.
17. The semiconductor device structure of claim 11 , wherein the first conductive plug has a first height, the second conductive plug has a second height, and the second height is greater than the first height.
18. The semiconductor device structure of claim 11 , wherein the first conductive plug has a first top surface, the second conductive plug has a second top surface, and the second top surface is substantially level with the first top surface.
19. The semiconductor device structure of claim 11 , wherein the first conductive plug has a first height, the second conductive plug has a second height, the first conductive structure has a third height, and the second height is substantially the same as a summation of the first height and the third height.
20. The semiconductor device structure of claim 11 , wherein the first conductive plug has a bottom surface substantially level with a bottom surface of the etch stop layer, and the second conductive plug has a bottom surface substantially lower than the bottom surface of the etch stop layer.