Extreme ultraviolet lithography method, extreme ultraviolet mask and formation method thereof
A method of forming an extreme ultraviolet (EUV) mask includes forming a multilayer Mo/Si stack comprising alternating stacked Mo and Si layers over a mask substrate; forming a ruthenium capping layer over the multilayer Mo/Si stack; doping the ruthenium capping layer with a halogen element, a pentavalent element, a hexavalent element or combinations thereof; forming an absorber layer over the ruthenium capping layer; and etching the absorber layer to form a pattern in the absorber layer.
1. A method of forming an extreme ultraviolet (EUV) mask, comprising:
forming a multilayer Mo/Si stack comprising alternating stacked Mo and Si layers over a mask substrate;
forming a ruthenium capping layer over the multilayer Mo/Si stack;
doping the ruthenium capping layer with a halogen element, a pentavalent element, a hexavalent element or combinations thereof;
forming an absorber layer over the ruthenium capping layer; and
etching the absorber layer to form a pattern in the absorber layer.
2. The method of claim 1 , wherein doping the ruthenium capping layer is performed prior to forming the absorber layer.
3. The method of claim 1 , wherein doping the ruthenium capping layer is performed after etching the absorber layer.
4. The method of claim 1 , wherein doping the ruthenium capping layer is performed in-situ with etching the absorber layer.
5. The method of claim 1 , wherein a bottom portion of the ruthenium capping layer remains substantially un-doped after doping the ruthenium capping layer is complete.
6. The method of claim 1 , further comprising:
forming an anti-reflection layer over the absorber layer prior to etching the absorber layer, wherein doping the ruthenium capping layer is performed prior to forming the anti-reflection layer.
7. The method of claim 1 , further comprising:
forming an anti-reflection layer over the absorber layer prior to etching the absorber layer, wherein doping the ruthenium capping layer is performed after forming the anti-reflection layer.
8. The method of claim 1 , further comprising:
forming an anti-reflection layer over the absorber layer prior to etching the absorber layer, wherein doping the ruthenium capping layer is performed such that a top portion of the anti-reflection layer is doped.
9. An extreme ultraviolet (EUV) mask, comprising:
a multilayer Mo/Si stack comprising alternating stacked Mo and Si layers disposed over a mask substrate;
a capping layer on the multilayer Mo/Si stack, wherein a top portion of the capping layer has a first composition different from a second composition of a bottom portion of the capping layer under the top portion of the capping layer; and
a patterned absorber layer on the capping layer.
10. The EUV mask of claim 9 , wherein the first composition of the top portion of the capping layer comprises a ruthenium complex with a ligand having a halogen element, a pentavalent element, a hexavalent element or combinations thereof.
11. The EUV mask of claim 9 , wherein the second composition of the bottom portion of the capping layer is free of a halogen element, a pentavalent element or a hexavalent element.
12. The EUV mask of claim 9 , wherein the top portion of the capping layer is partially exposed by the patterned absorber layer.
13. The EUV mask of claim 9 , further comprising:
a patterned anti-reflection layer over the patterned absorber layer, the patterned anti-reflection layer has a halogen element, a pentavalent element, or a hexavalent element the same as that of the first composition of the top portion of the capping layer.
14. A method of forming an extreme ultraviolet (EUV) mask, comprising:
forming a multilayer Mo/Si stack comprising alternating stacked Mo and Si layers over a mask substrate;
forming a capping layer over the multilayer Mo/Si stack, wherein the capping layer comprises a top portion having a first composition;
performing a doping process such that the top portion of the capping layer has a second composition different from the first composition;
forming an absorber layer over the capping layer; and
etching the absorber layer to form a pattern in the absorber layer.
15. The method of claim 14 , wherein the top portion of the capping layer is not cross-linkable with hydrocarbon after the doping process.
16. The method of claim 14 , wherein after the doping process, the bottom portion has a third composition different from the second composition of the top portion.
17. The method of claim 14 , wherein the first composition of the top portion is Ru, and the second composition of the top portion is Ru x O 1-x , Ru x N 1-x , or Ru x A y O 1-x-y , in which A is halogen.
18. The method of claim 14 , wherein the second composition of the top portion and the first composition of the top portion have different chemical bonding types.
19. The method of claim 14 , wherein the absorber layer is formed after the doping process.
20. The method of claim 14 , wherein the absorber layer is etched before the doping process.