Method for fabricating an integrated semiconductor circuit to prevent formation of voids
View Patent ↗Recesses between gate layer stacks are filled with a first electrically insulating material. Cavities or voids are opened up during the removal of a portion of the first insulating material. These voids are filled during the application of a conductive layer and can then lead to short circuits. Inventively, a layer for closing up voids is produced before the conductive material is applied, as a result of growing a second electrically insulating material onto the surface of the remaining first insulating material. This second insulating layer closes up voids that have formed in the first insulating material so that they can no longer lead to short circuits. In particular, voids that are difficult to gain access to and open out into side walls of contact holes can in this way be closed up in a simple manner.
1. A method for fabricating an integrated semiconductor circuit, which comprises:
a) providing a semiconductor substrate;
b) depositing an etching stop layer having a top side;
c) forming a recess;
d) depositing a first electrically insulating material to fill the recess;
e) removing a portion of the first insulating material by polishing the first insulating material down to the top side of the etching stop layer by using a chemical mechanical polishing operation;
f) applying an electrically conductive material; and
g) after step e) and before step f), producing a layer for closing up voids by growing a second electrically insulating material onto a surface of the first insulating material by a selective growth process performed selectively to the etching stop layer.
2. The method according to claim 1 , wherein: step b) includes forming the recess by etching a trench, which is for a shallow trench isolation, into the semiconductor substrate.
3. The method according to claim 1 , wherein:
the voids are formed in the interior of the first insulating material;
the voids are opened up when step e) is performed; and
the voids are closed by the second insulating material.
4. The method according to claim 1 , wherein: the first insulating material is a silicate glass that is doped with a material selected from a group consisting of boron and phosphorus.
5. The method according to claim 1 , wherein: the second insulating material is silicon oxide.
6. The method according to claim 1 , wherein: the second insulating material is thermally compacted by conditioning.