Shallow trench isolation structure and formation method thereof
View Patent ↗A method for fabricating an STI structure in a semiconductor device is disclosed. A disclosed method comprises: forming a pad oxide layer and a pad nitride layer on a substrate in sequence; patterning the pad oxide layer and the pad nitride layer to expose a predetermined part of the surface of the silicon substrate; forming a trench by etching the exposed part of the silicon substrate; depositing a nitride layer inside the trench and on the entire surface of the resulting structure; forming a thin thermal oxide layer along the interface between a silicon substrate and the thin nitride layer; and performing a wet cleaning process to make a predetermined angle in the upper part of the trench.
1. An STI structure comprising:
a trench with a predetermined depth in a substrate;
a nitride layer inside the trench, the nitride layer having a substantially planar upper surface that is coplanar with an upper surface of the trench;
a thin thermal oxide layer along the interface between the silicon substrate and the nitride layer, the thin thermal oxide layer having a substantially planar upper surface that is coplanar with the upper surface of the nitride layer, and
an insulation layer filling the trench, the insulation layer exposing the upper surface of the thin thermal oxide layer and covering the entire upper surface of the nitride layer.
2. An STI structure as defined by claim 1 , wherein the trench has a depth between 6000 Å and 7000 Å.
3. An STI structure as defined by claim 1 , wherein the nitride layer has a thickness between 100 Å and 300 Å.
4. An STI structure as defined by claim 1 , wherein the insulation layer has an upper surface tat is higher than an uppermost surface of the nitride layer and an uppermost surface of the thin thermal oxide layer.
5. An STI structure as defined by claim 1 , wherein the insulation layer is only on the nitride layer.
6. An STI structure as defined by claim 1 , wherein the insulation layer comprises an O 3 -TEOS oxide layer.
7. An STI structure as defined by claim 1 , wherein a width of a top surface of the insulation layer is narrower than a width of the trench.
8. An STI structure as defined by claim 7 , wherein the trench has a dept between 6000 Å and 7000 Å.
9. An STI structure as defined by claim 7 , wherein the nitride layer has a thickness between 100 Å and 300 Å.
10. An STI structure as defined by claim 7 , wherein the insulation layer has an upper surface that is higher than an uppermost surface of the nitride layer and an uppermost surface of the thin thermal oxide layer.
11. An STI structure as defined by claim 7 , wherein the insulation layer is only on the nitride layer.
12. An STI structure as defined by claim 11 , wherein the insulation layer exposes the thin thermal oxide layer.
13. An STI structure as defined by claim 7 , wherein the insulation layer comprises an O 3 -TEOS oxide layer.