Use of selective aluminum oxide etch
Methods of forming and processing semiconductor devices which utilize the selective etching of aluminum oxide over silicon oxide and/or silicon nitride are described. Certain embodiments relate to the formation of fin-etched substrates. Other embodiments relate to the removal of source drain caps from substrates. Further embodiments relate to the processing of substrates comprising vias and/or metal contacts with bottom etch stop layers and/or liner layers.
1. A method of forming a semiconductor device, the method comprising:
forming a first spin-on-carbon layer, a first hardmask and a first photoresist on a film comprising alternating columns of spacer mandrels and gapfill materials with oxide films between, the first photoresist having an opening over one of the gapfill materials and the gapfill materials comprising aluminum oxide;
etching the first hardmask and the first spin-on-carbon layer through the opening in the first photoresist to expose a top surface of one of the gapfill materials;
removing the first spin-on-carbon layer, the first hardmask and the one of the gapfill materials to leave a gap;
forming a second spin-on-carbon layer, a second hardmask and a second photoresist on the film comprising alternating columns of spacer mandrels, gapfill materials, oxide films and the gap, the second photoresist having an opening over one of the spacer mandrels;
etching the second hardmask and the second spin-on carbon layer through the opening in the second photoresist to expose a top surface of one of the spacer mandrels;
removing the second spin-on-carbon layer, the second hardmask and the one of the spacer mandrels to leave another gap;
removing the oxide films to leave the spacer mandrels and the gapfill materials on a first etch stop layer on a first oxide layer on a substrate;
etching to remove the first etch stop layer and the first oxide layer not covered by the spacer mandrels or the gapfill materials and reducing a height of the spacer mandrels and gapfill materials to expose portions of the substrate; and
fin etching the exposed portions of the substrate and removing the remaining spacer mandrels, the gapfill materials, the first etch stop layer and the first oxide layer.
2. The method of claim 1 , wherein prior to forming the second spin-on-carbon layer the method further comprises:
forming mandrels in an amorphous silicon layer on the first etch stop layer;
forming a conformal spacer layer on the mandrels;
removing the mandrels and square etching the conformal spacer layer to form the spacer mandrels on the first etch stop layer;
forming a conformal oxide layer on the spacer mandrels;
etching the conformal oxide layer to form the oxide films on both sides of the spacer mandrels with gaps between the adjacent oxide films; and
depositing flail the gapfill materials in the gaps between adjacent oxide films.
3. The method of claim 2 , wherein the first oxide layer on the substrate comprises silicon oxide.
4. The method of claim 2 , wherein the spacer mandrels comprise silicon nitride.
5. The method of claim 2 , wherein the gapfill material is removed by an etch process with a selectivity greater than or equal to about 12.
6. The method of claim 2 , wherein the oxide films comprise silicon oxide.
7. The method of claim 2 , wherein the conformal spacer layer comprises silicon nitride.
8. The method of claim 1 , wherein prior to forming the second spin-on-carbon layer, the method further comprises:
forming mandrels in a third spin-on-carbon layer on a second etch stop layer on a silicon nitride layer on the first etch stop layer on the oxide layer on the substrate;
forming a conformal spacer layer on the mandrels;
removing the mandrels and square etching the conformal spacer layer to form spacer mandrels on the second etch stop layer;
transferring the spacer mandrels on the second etch stop layer to the silicon nitride layer to form the spacer mandrels and expose the first etch stop layer; removing the spacer mandrels on the second etch stop layer and the remaining portions of the second etch stop layer;
forming a conformal oxide layer on the spacer mandrels on the second etch stop layer;
etching the conformal oxide layer to form the oxide films on both sides of the spacer mandrels with Hall gaps between the adjacent oxide films; and
depositing flail the gapfill material in the gaps between adjacent oxide films.
9. The method of claim 8 , wherein the oxide layer on the substrate comprises silicon oxide.
10. The method of claim 8 , wherein the spacer mandrels comprise silicon nitride.
11. The method of claim 8 , wherein the gapfill material is removed by an etch process with a selectivity greater than or equal to about 12.
12. The method of claim 8 , wherein the oxide films comprise silicon oxide.
13. The method of claim 8 , wherein the conformal spacer layer comprises silicon nitride.
14. The method of claim 1 , wherein prior to forming the second spin-on-carbon layer, the method further comprises:
forming mandrels in a fourth spin-on-carbon layer on a second etch stop layer on an amorphous silicon layer on the first etch stop layer on the first oxide layer on the substrate;
forming a conformal spacer layer on the mandrels in the fourth spin-on-carbon layer;
removing the mandrels in the fourth spin-on-carbon layer and square etching the conformal spacer layer to form spacer mandrels on the second etch stop layer;
transferring the spacer mandrels on the second etch stop layer to the amorphous silicon layer to form amorphous silicon spacer mandrels and expose the second etch stop layer;
removing the spacer mandrels on the second etch stop layer and the remaining portions of the second etch stop layer;
forming a conformal oxide layer on the amorphous silicon spacer mandrels on the first etch stop layer;
etching the conformal oxide layer to form the oxide films on both sides of the amorphous silicon spacer mandrels with gaps between the adjacent oxide films;
depositing flail the gapfill materials in the gaps between adjacent oxide films;
removing the amorphous silicon spacer mandrels leaving gaps between adjacent oxide films; and
depositing a silicon nitride film in the gaps between the adjacent oxide films to form the spacer mandrels.
15. The method of claim 14 , wherein the spacer mandrels comprise silicon nitride.
16. The method of claim 14 , wherein the gapfill material is removed by an etch process with a selectivity greater than or equal to about 12.
17. The method of claim 14 , wherein the oxide films comprise silicon oxide.