Method to insulate contact plug with silicon carbon oxide and to insulate above bit line with silicon oxide by oxidating silicon carbon oxide
A semiconductor structure and a method for manufacturing the same are provided. The semiconductor structure includes: a substrate, bit line structures, and an isolation structure. The substrate includes multiple active areas. The bit line structures are located above the active areas, and include multiple bit lines extending in a first direction parallel to the surface of the substrate and multiple contact plugs electrically connected to the bit lines and the active areas. The isolation structure includes a first insulating layer including a first part and a second part located below the first part, a second insulating layer covering the surface of the second part and a third insulating layer covering at least the surface of the first part. The first part covers at least side walls of the bit lines, and the second part covers at least side walls of the contact plugs.
1 . A method for manufacturing a semiconductor structure, comprising:
providing a substrate comprising an active area;
forming a bit line structure electrically connected to the active area; wherein the bit line structure comprises a bit line extending in a first direction parallel to a surface of the substrate and a contact plug electrically connected to the bit line and the active area;
forming silicon carbon oxide covering a top surface and side walls of the bit line structure;
forming a second insulating material layer with a dielectric constant greater than a dielectric constant of the silicon carbon oxide covering a surface of the silicon carbon oxide;
removing part of the second insulating material layer, wherein remaining part of the second insulating material forms a second insulating layer and covers the surface of the silicon carbon oxide covering side walls of the contact plug;
performing an oxidation treatment on part of the silicon carbon oxide not covered by the second insulating layer to form silicon oxide, wherein the silicon oxide forms a first part of a first insulating layer and covers side walls of the bit line, and remaining part of the silicon carbon oxide covers as a second part of the first insulating layer and covers the side walls of the contact plug; and
forming a third insulating material layer covering a top surface of the second insulating layer and side walls of the first part.
2 . The method of claim 1 , wherein
forming the bit line structure electrically connected to the active area comprises:
etching the substrate to form a contact hole exposing the active area, and filling the contact hole to form a conductive contact material layer; wherein the conductive contact material layer has a first surface and a second surface opposing each other; the first surface is in contact with the active area, and a size of the first surface is smaller than a size of the second surface;
forming a conductive material layer covering the substrate and the conductive contact material layer;
etching part of the conductive material layer to form a groove extending in the first direction; wherein the conductive material layer between two adjacent grooves forms the bit line; and
etching the conductive contact material layer exposed by the groove to form a gap; wherein the remaining conductive contact material layer forms the contact plug, and the gap is located on two sides of the contact plug.
3 . The method of claim 2 , wherein
the silicon carbon oxide covers the gap, the side walls of the bit line structure, and the surface of the substrate; the second insulating layer located in the gap.
4 . The manufacturing of claim 3 , wherein
performing an oxidation treatment on part of the silicon carbon oxide not covered by the second insulating layer to form silicon oxide comprises: performing the oxidation treatment on the silicon carbon oxide on the top surface and the side walls of the bit line structure, and on the surface of the substrate by using oxygen plasma.
5 . The method of claim 3 , wherein
materials of the second insulating material layer and the third insulating material layer comprise any one of silicon nitride, silicon nitrogen oxide, or silicon carbon nitride.
6 . The method of claim 3 , wherein before forming the silicon carbon oxide, the method further comprises:
forming a protective layer, which covers a surface, away from the substrate, of the bit line.