Method for the fabrication of isolation structures

1. A method for manufacturing insulating structures in a semiconductor substrate comprising;

forming a first insulating layer on the semiconductor substrate;

forming a stop layer on the first insulating layer;

forming a barrier layer on the stop layer, the barrier layer being selectively removable with respect to the stop layer;

forming a screen layer on the barrier layer;

selectively removing a portion of the screen layer for forming an opening therethrough for exposing a portion of the barrier layer;

removing the exposed barrier layer for exposing a portion of the stop layer;

removing the exposed stop layer for exposing a portion of the semiconductor substrate;

removing the remaining barrier layer and, at a same time, removing a portion of the exposed semiconductor substrate for forming a trench therein.

2. A method according to claim 1 , further comprising removing the remaining screen layer when the exposed stop layer is removed.

3. A method according to claim 1 , further comprising forming a second insulating layer on the stop layer before forming the barrier layer.

4. A method according to claim 1 , wherein removing the remaining barrier layer is performed by plasma etching.

5. A method according to claim 4 , wherein the plasma etching is performed with a low polymerizing chemistry.

6. A method according claim 1 , wherein the screen layer comprises a resist layer.

7. A method according to claim 1 , wherein removing the exposed barrier layer is performed by a non-fluorine-based chemistry etching.

8. A method according to claim 1 , wherein the barrier layer comprises a semiconductor layer.

9. A method according to claim 8 , wherein the semiconductor layer comprises a polysilicon layer.

10. A method according to claim 1 , wherein the stop layer comprises a nitride layer.

11. A method according to claim 1 , further comprising forming a supplementary layer on the barrier layer before forming the screen layer.

12. A method for manufacturing insulating structures in a semiconductor substrate comprising:

forming a first insulating layer on the semiconductor substrate;

forming a stop layer on the first insulating layer;

forming a barrier layer on the stop layer, the barrier layer being selectively removable with respect to the stop layer;

forming a screen layer on the barrier layer;

selectively removing a portion of the screen layer for forming an opening therethrough for exposing a portion of the barrier layer;

removing the exposed barrier layer for exposing a portion of the stop layer;

removing the exposed stop layer for exposing a portion of the semiconductor substrate;

removing the remaining barrier layer; removing a portion of the exposed semiconductor substrate for forming a trench therein; and

forming a second insulating layer on the stop layer before forming the barrier layer.

13. A method according to claim 12 , wherein the barrier layer comprises a semiconductor layer.

14. A method for manufacturing insulating structures in a semiconductor substrate comprising:

forming a first insulating layer on the semiconductor substrate;

forming a stop layer on the first insulating layer;

forming a barrier layer on the stop layer, the barrier layer comprising a semiconductor layer and being selectively removable with respect to the stop layer;

forming a screen layer on the barrier layer;

selectively removing a portion of the screen layer for forming an opening therethrough for exposing a portion of the barrier layer;

removing the exposed barrier layer for exposing a portion of the stop layer;

removing the exposed stop layer for exposing a portion of the semiconductor substrate;

removing the remaining barrier layer; and

removing a portion of the exposed semiconductor substrate for forming a trench therein.

15. A method according to claim 14 , wherein the semiconductor layer comprises a polysilicon layer.