Semiconductor device including interconnects, vias connecting the interconnects and greater thickness of the liner film adjacent the vias
View Patent ↗An interlayer insulating film is formed on the upper surface of a semiconductor substrate, and lower-level interconnects are formed in the interlayer insulating film. A liner insulating film is formed on the upper surfaces of the interlayer insulating film and lower-level interconnects. An interlayer insulating film is formed on the upper surface of the liner insulating film. Upper-level interconnects are formed in the interlayer insulating film. The lower-level interconnects and the upper-level interconnects are connected with each other through vias. Parts of the liner insulating film formed in via-adjacent regions have a greater thickness than a part thereof formed outside the via-adjacent regions.
1. A semiconductor device comprising:
a semiconductor substrate;
a first interlayer insulating film formed on the semiconductor substrate;
first interconnects formed in the first interlayer insulating film;
a liner insulating film formed on the first interlayer insulating film and on the first interconnects;
a second interlayer insulating film formed on the liner insulating film;
second interconnects formed in the second interlayer insulating film; and
vias formed in the liner insulating film and in the second interlayer insulating film, and electrically connecting the first and second interconnects,
wherein parts of the liner insulating film formed on a given first interconnect and in via-adjacent regions adjacent to the vias have a greater thickness than a part of the liner insulating film formed on the given first interconnect and outside the via-adjacent regions.
2. The semiconductor device of claim 1 , wherein the liner insulating film is a multilayer film including a first liner insulating film and a second liner insulating film.
3. The semiconductor device of claim 2 , wherein the first liner insulating film is not formed outside the via-adjacent regions.
4. The semiconductor device of claim 2 , wherein the first liner insulating film has a Young's modulus of 40 GPa or higher.
5. The semiconductor device of claim 2 , wherein the second liner insulating film has a dielectric constant of 4.5 or lower.
6. The semiconductor device of claim 2 , wherein an air gap is formed between at least one of adjacent pairs of the first interconnects.
7. The semiconductor device of claim 6 , wherein the air gap is formed in a gap formed between the one of the adjacent pairs of the first interconnects, and
the second liner insulating film is formed on the bottom and side walls of the gap.
8. The semiconductor device of claim 1 , wherein each of the via-adjacent regions is a region on the upper surface of the first interlayer insulating film, has a length and a width each equal to, or within, two to ten times greater than the diameter of a corresponding one of the vias, and has a center matching the center of the corresponding via.
9. The semiconductor device of claim 1 , wherein the thickness of the parts of the liner insulating film formed in the via-adjacent regions is 10 nm or more and 100 nm or less.
10. The semiconductor device of claim 1 , wherein, of the part of the liner insulating film formed outside the via-adjacent regions, a part formed on a distance between an adjacent pair of the first interconnects which is 2d or more has a greater thickness than a part formed on a distance between an adjacent pair of the first interconnects which is less than 2d, where d is the value of a smallest distance between adjacent pairs of the first interconnects.
11. The semiconductor device of claim 1 , wherein a first portion, in which one of the first interconnects changes in width, bends, or divides, is present in a part of the upper surface of the first interlayer insulating film located outside the via-adjacent regions; and
of the part of the liner insulating film formed outside the via-adjacent regions, a part formed on the first portion has a greater thickness than a part formed on a portion other than the first portion.
12. The semiconductor device of claim 1 , wherein
a third liner insulating film is formed on the second interconnects,
parts of the third liner insulating film formed on the second interconnects and in via-adjacent regions have a greater thickness than a part of the third liner insulating film formed on the second interconnects and outside the via-adjacent regions.
13. The semiconductor device of claim 1 , wherein
a third liner insulating film is formed on the second interconnects,
second vias different from the first vias are formed in the second interlayer insulating film, and are electrically connected to the first interconnects,
parts of the liner insulating film formed on the first interconnects and in second via-adjacent regions adjacent to the second vias have a greater thickness than a part of the liner insulating film formed on the first interconnects and outside the via-adjacent regions,
the third liner insulating film is formed on the second vias,
parts of the third liner insulating film formed in regions between the second vias and the vias have a greater thickness than a part of the liner insulating film formed on the first interconnects and outside the via-adjacent regions.
14. The semiconductor device of claim 1 , wherein
a third liner insulating film is formed on the second interconnects,
second vias different from the first vias are formed in the second interlayer insulating film, and are electrically connected to the first interconnects,
parts of the liner insulating film formed on the first interconnects and in second via-adjacent regions adjacent to the second vias have a greater thickness than a part of the liner insulating film formed on the first interconnects and outside the via-adjacent regions,
the third liner insulating film is formed on the second vias,
parts of the third liner insulating film formed in regions between the second vias and the vias have a greater thickness than a part of the third liner insulating film formed on the second interconnects and outside the via-adjacent regions.
15. The semiconductor device of claim 2 , wherein
the first and second liner insulating films and are formed using different materials.
16. The semiconductor device of claim 2 , wherein
the second liner insulating film has a dielectric constant lower than that of the first liner insulating film.
17. The semiconductor device of claim 2 , wherein
the first liner insulating film is made of SiCN, and
the second liner insulating film is made of SiC.
18. The semiconductor device of claim 1 , wherein
the liner insulating film has a single-layer portion, and a multi-layer portion, and
a portion of the liner insulating film which is in contact with the vias is the multi-layer portion.
19. The semiconductor device of claim 6 , wherein the air gap is in contact with the second interlayer insulating film.
20. The semiconductor device of claim 7 , wherein the second interlayer insulating film is formed between the gap and the air gap.
21. The semiconductor device of claim 1 , wherein of the liner insulating film, a portion formed on the bottom and side walls of the gap is a single-layer film.
22. The semiconductor device of claim 6 , wherein of the part of the liner insulating film formed outside the via-adjacent regions, the air gap is not formed on a part formed on a distance between an adjacent pair of the first interconnects which is more than d, where d is a distance between adjacent pairs of the first interconnects.
23. A semiconductor device comprising:
a semiconductor substrate;
a first interlayer insulating film formed on the semiconductor substrate;
first interconnects formed in the first interlayer insulating film;
a second interlayer insulating film formed on the first interlayer insulating film and on the first interconnects;
second interconnects formed in the second interlayer insulating film;
vias formed in the second interlayer insulating film, and electrically connecting the first and second interconnects, and
a liner insulating film formed on the second interlayer insulating film and on the second interconnects,
wherein parts of the liner insulating film formed on a given second interconnect and in via-adjacent regions adjacent to the vias have a greater thickness than a part of the liner insulating film formed on the given second interconnect and outside the via-adjacent regions.
24. The semiconductor device of claim 23 , wherein the first and second liner insulating films and are formed using different materials.
25. The semiconductor device of claim 23 , wherein the second liner insulating film has a dielectric constant lower than that of the first liner insulating film.
26. The semiconductor device of claim 23 , wherein
the first liner insulating film is made of SiCN, and
the second liner insulating film is made of SiC.