Method for forming semiconductor structures and semiconductor structure
The present disclosure provides a method for forming a semiconductor structure and a semiconductor structure. The method for forming a semiconductor structure includes: providing a substrate, and forming discrete bit line structures on the substrate; forming a first sacrificial layer on the surface of the substrate on the bottoms of gaps of the bit line structures; forming a second sacrificial layer filling the gaps of the discrete bit line structures; patterning the second sacrificial layer and the first sacrificial layer to form openings, the formed openings and the remaining of the second sacrificial layer being arranged alternately in an extension direction of the bit line structures; forming a dielectric layer filling the openings; and, removing the remaining of the first sacrificial layer and the remaining of the second sacrificial layer to form capacitor contact holes, the formed capacitor contact holes and the dielectric layer being arranged alternately.
1. A method for forming a semiconductor structure, comprising:
providing a substrate, and forming discrete bit line structures on the substrate;
forming a first sacrificial layer on a surface of the substrate on bottoms of gaps of the bit line structures;
forming a second sacrificial layer filling the gaps of the bit line structures, the second sacrificial layer being located on a top of the first sacrificial layer, and a material for the first sacrificial layer being different from a material for the second sacrificial layer;
patterning the second sacrificial layer and the first sacrificial layer to form openings, the openings and a remaining portion of the second sacrificial layer being arranged alternately in an extension direction of the bit line structures;
forming a dielectric layer filling the openings; and
removing a remaining portion of the first sacrificial layer and the remaining portion of the second sacrificial layer to form capacitor contact holes, the capacitor contact holes and the dielectric layer being arranged alternately in the extension direction of the bit line structures.
2. The method for forming the semiconductor structure according to claim 1 , wherein the forming the first sacrificial layer on the surface of the substrate on the bottoms of the gaps of the bit line structures comprises:
forming a first sacrificial film that covers tops and sidewalls of the bit line structures and covers the substrate on the bottoms of the gaps of the bit line structures; and
removing the first sacrificial film located on the tops and the sidewalls of the bit line structures, a remaining portion of the first sacrificial film forming the first sacrificial layer.
3. The method for forming the semiconductor structure according to claim 2 , wherein the first sacrificial film is formed by atomic layer deposition.
4. The method for forming the semiconductor structure according to claim 1 , wherein the first sacrificial layer has a thickness ranging from 3 to 10 nm.
5. The method for forming the semiconductor structure according to claim 4 , wherein a thickness ratio of the first sacrificial layer to the second sacrificial layer is less than or equal to 1:10.
6. The method forming the semiconductor structure according to claim 1 , wherein the forming the first sacrificial layer on the surface of the substrate on the bottoms of the gaps of the bit line structures comprises:
forming a first sub-sacrificial layer on the surface of the substrate on the bottoms of the gaps of the bit line structures; and
forming a second sub-sacrificial layer on a top surface of the first sub-sacrificial layer, a material for the first sub-sacrificial layer being different from a material for the second sub-sacrificial layer, the first sub-sacrificial layer and the second sub-sacrificial layer forming the first sacrificial layer.
7. The method for forming the semiconductor structure according to claim 1 , wherein the forming the second sacrificial layer filling the gaps of the bit line structures comprises:
forming, on a surface of the first sacrificial layer, a second sacrificial film that fills the gaps of the bit line structures and covers the bit line structures; and
planarizing the second sacrificial film until a height of a remaining portion of the second sacrificial film is equal to a height of the bit line structures, the remaining portion of the second sacrificial film forming the second sacrificial layer.
8. The method for forming the semiconductor structure according to claim 7 , wherein the second sacrificial film is formed by chemical vapor deposition.
9. The method for forming the semiconductor structure according to claim 1 , wherein an etching selectivity ratio of the material for the first sacrificial layer to the material for the second sacrificial layer is greater than 5:1, when the first sacrificial layer and the second sacrificial layer are etched by a same etching material.
10. The method for forming the semiconductor structure according to claim 1 , wherein a density of the material for the first sacrificial layer is less than a density of the material for the second sacrificial layer.
11. The method for forming the semiconductor structure according to claim 1 , wherein the patterning the second sacrificial layer and the first sacrificial layer to form the openings comprises:
forming a patterned photoresist on a top surface of the second sacrificial layer;
removing part of the second sacrificial layer based on the patterned photoresist to form pre-openings, the pre-openings and the remaining portion of the second sacrificial layer being arranged alternately in the extension direction of the bit line structures; and
removing the first sacrificial layer exposed by the pre-openings to form the openings.
12. The method for forming the semiconductor structure according to claim 1 , wherein the patterning the second sacrificial layer and the first sacrificial layer to form the openings comprises:
forming a patterned photoresist on a top surface of the second sacrificial layer; and
removing parts of the second sacrificial layer and the first sacrificial layer using a same etching material based on the patterned photoresist to form the openings.
13. The method for forming the semiconductor structure according to claim 1 , wherein the forming the dielectric layer filling the openings comprises:
forming a dielectric film that fills the openings and covers the second sacrificial layer; and
planarizing the dielectric film until a height of a remaining portion of the dielectric film is equal to a height of the second sacrificial layer, the remaining portion of the dielectric film forming the dielectric layer.
14. The method for forming the semiconductor structure according to claim 1 , wherein the removing the remaining portion of the first sacrificial layer and the remaining portion of the second sacrificial layer to form the capacitor contact holes comprises:
removing the remaining portion of the second sacrificial layer based on the dielectric layer and the bit line structures to form through vias, the through vias exposing the first sacrificial layer; and
removing the first sacrificial layer on bottoms of the through vias based on the dielectric layer and the bit line structures to form the capacitor contact holes.
15. The method for forming the semiconductor structure according to claim 14 , wherein the remaining portion of the second sacrificial layer is removed by ashing.