Double patterning strategy for contact hole and trench in photolithography
A method of lithography patterning includes forming a mask layer on a material layer and forming a capping layer on the mask layer. The capping layer is a boron-containing layer with a higher resistance to an etching reaction of patterning process of the material layer. By adapting the boron-containing layer as the capping layer, the thickness of the mask layer can be thus reduced. Hence, a better gap filling for forming an interconnect metallization in the material layer could be achieved as well.
1. A method comprising:
forming an etch stop layer overlying a substrate;
forming a metal mask layer overlying the etch stop layer;
forming a boron-containing layer overlying the metal mask layer, wherein the boron-containing layer comprises a material selected from the group consisting essentially of amorphous boron, boron nitride, boron carbide, and combinations thereof;
forming a first pattern overlying the boron-containing layer;
etching the boron-containing layer using the first pattern as an etch mask to form a first patterned boron-containing layer having a set of first openings therein;
removing the first pattern;
forming a second pattern overlying the first patterned boron-containing layer;
etching the first patterned boron-containing layer using the second pattern as an etch mask to form a second patterned boron-containing layer having a second opening therein, wherein the second opening positioned between two of the set of first openings; and
removing the second pattern.
2. The method of claim 1 , further comprising a first bottom anti-reflective coating layer underlying the first pattern.
3. The method of claim 1 , further comprising a second bottom anti-reflective coating layer underlying the second pattern.
4. The method of claim 1 , wherein the etch stop layer is a nitrogen-free anti-reflection layer.
5. The method of claim 1 , wherein the metal mask layer includes titanium nitride, tantalum nitride, titanium, or combinations thereof.
6. The method of claim 1 , wherein the etch stop layer has a thickness ranging between about 50 angstroms and about 500 angstroms.
7. The method of claim 1 , wherein the metal mask layer has a thickness ranging between about 50 angstroms and about 500 angstroms.
8. The method of claim 1 , wherein the boron-containing layer has a thickness ranging between about 50 angstroms and about 500 angstroms.
9. The method of claim 1 , wherein the metal mask layer has a thickness of about or less than about 300 angstroms.
10. The method of claim 1 , wherein the step of etching the boron-containing layer is performed by an etching gas comprising of CxHyFz (x>0, y, z>=0), O 2 , N 2 , Ar, Cl 2 , or mixtures thereof.
11. The method of claim 1 , wherein the first and the second patterns are removed in an ashing process with at least one oxygen-containing gas.
12. The method of claim 1 , further comprising a step of etching the metal mask layer using the second patterned boron-containing layer as an etch mask.
13. A method of forming a semiconductor structure, comprising:
forming a dielectric layer overlying a substrate;
forming an etch stop layer overlying the substrate;
forming a metal mask layer overlying the etch stop layer;
forming a boron-containing layer overlying the mask layer, wherein the boron-containing layer comprises a material selected from the group consisting essentially of amorphous boron, boron nitride, boron carbide, and combinations thereof;
forming a first resist pattern overlying the boron-containing layer;
etching the boron-containing layer using the first resist pattern as an etch mask to form a plurality of intermediate boron-containing features;
removing the first resist pattern by a first ashing process;
forming a second resist pattern overlying the intermediate boron-containing features;
etching the intermediate boron-containing features using the second resist pattern as an etch mask to form a plurality of final boron-containing features;
removing the second resist pattern by a second ashing process; and
etching the metal mask layer using the final boron-containing features as an etch mask to form a patterned metal mask layer.
14. The method of claim 13 , further comprising a step of etching the dielectric layer using the patterned metal mask layer as an etch mask.
15. The method of claim 13 , wherein the metal mask layer includes titanium nitride, tantalum nitride, titanium, or combinations thereof.
16. The method of claim 13 , wherein the metal mask layer has a thickness of about or less than about 300 angstroms.
17. The method of claim 13 , wherein the step of etching the boron-containing layer is performed by an etching gas comprising of CxHyFz (x>0, y, z>=0), O 2 , N 2 , Ar, Cl 2 , or mixtures thereof.
18. A method of forming a semiconductor structure, comprising:
forming a dielectric layer overlying a substrate;
forming an etch stop mask layer overlying the dielectric layer;
forming a metal mask layer overlying the etch stop mask layer, wherein the metal mask layer has a thickness not thicker than 300 angstroms;
forming a boron-containing layer overlying the metal mask layer;
forming a first resist pattern overlying the boron-containing layer, the first resist pattern is formed by a first positive resist layer having a plurality of first openings therein;
etching the boron-containing layer using the first resist pattern as an etch mask to form a first patterned boron-containing layer having the plurality of first openings therein;
removing the first resist pattern;
forming a second resist pattern overlying the first patterned boron-containing layer, the second resist pattern is formed by a second positive resist layer having a plurality of second openings therein;
etching the first patterned boron-containing layer using the second resist pattern as an etch mask to form a second patterned boron-containing layer having the plurality of second openings therein, wherein at least one of the plurality of second openings positioned between two of the plurality of first openings;
removing the second resist pattern;
etching the metal mask layer using the second patterned boron-containing layer as an etch mask to form a patterned metal mask layer; and
etching the dielectric layer using the patterned metal mask layer as an etch mask to form a patterned dielectric layer, wherein after the step of etching the dielectric layer is finished, a portion of the second patterned boron-containing layer remains.
19. The method of claim 12 , further comprising, after etching the metal mask layer, etching a material layer underlying the metal mask layer using the metal mask layer as an etch mask, wherein after the step of etching the material layer is finished, a portion of the second patterned boron-containing layer remains.
20. The method of claim 14 , where after the step of etching the dielectric layer is finished, a portion of the final boron-containing features remains.