Structure and method for reflective-type mask
The present disclosure provides an embodiment of a reflective mask that includes a substrate; a reflective multilayer formed on the substrate; a capping layer formed on the reflective multilayer and having a hardness greater than about 8; and an absorber layer formed on the capping layer and patterned according to an integrated circuit layout.
1. A reflective mask, comprising:
a substrate;
a reflective multilayer formed on the substrate;
a capping layer formed on the reflective multilayer and having a hardness greater than about 8; and
an absorber layer formed on the capping layer and patterned according to an integrated circuit layout.
2. The reflective mask of claim 1 , wherein the capping layer has a refractive index greater than about 0.95 and an extinction coefficient less than 0.005.
3. The reflective mask of claim 1 , wherein the capping layer includes silicon carbide.
4. The reflective mask of claim 1 , wherein the capping layer includes a Ru alloy selected from the group consisting of YRu, ZrRu, CrRu, RuCo, RuNi, HfRu, RuGe, and combination thereof.
5. The reflective mask of claim 1 , wherein the capping layer includes an yttrium (Y) layer.
6. The reflective mask of claim 1 , wherein the substrate includes a low thermal expansion material (LTEM).
7. The reflective mask of claim 1 , wherein the substrate includes one material selected from the group consisting of fused silica, titanium oxide (TiO 2 ) doped fused silica (SiO 2 ), fused quartz, calcium fluoride (CaF 2 ), and a combination thereof.
8. The reflective mask of claim 1 , wherein the reflective multilayer includes a plurality of alternating molybdenum-silicon (Mo/Si) films.
9. The reflective mask of claim 1 , wherein the reflective multilayer includes a plurality of alternating molybdenum-beryllium (Mo/Be) films.
10. The reflective mask of claim 1 , wherein the absorber layer includes tantalum boron nitride (TaBN).
11. The reflective mask of claim 1 , wherein the absorber layer includes a material selected from the group consisting of chromium (Cr), chromium oxide (CrO), titanium nitride (TiN), tantalum nitride (TaN), tantalum (Ta), titanium (Ti), or aluminum-copper (Al—Cu), palladium, tantalum boron nitride (TaBN), aluminum oxide (AlO), molybdenum (Mo).
12. The reflective mask of claim 1 , further comprising a protective layer formed on the absorber layer, wherein the protective layer and the capping layer include a same material.
13. A reflective mask, comprising:
a substrate;
a reflective multilayer formed on the substrate;
a capping layer of a material formed on the reflective multilayer;
an absorber layer formed on the capping layer; and
a protective layer of the material formed on the absorber layer, wherein the absorber layer and the protective layer are both patterned according to an integrated circuit layout.
14. The reflective mask of claim 13 , wherein the material has
a cleaning durability greater than that of ruthenium (Ru);
a refractive index greater than about 0.95; and
an extinction coefficient less than 0.005.
15. The reflective mask of claim 13 , wherein the material includes a Ru alloy selected from the group consisting of YRu, ZrRu, CrRu, RuCo, RuNi, HfRu, RuGe, and combination thereof.
16. The reflective mask of claim 13 , wherein the material includes one of silicon carbide and yttrium (Y).
17. The reflective mask of claim 13 , wherein
the substrate includes a low thermal expansion material (LTEM);
the reflective multilayer includes a plurality of alternating molybdenum-silicon (Mo/Si) films; and
the absorber layer includes tantalum boron nitride (TaBN).
18. A method for forming an integrated circuit comprising:
forming a material layer over a substrate;
forming a photoresist layer over the material layer; and
patterning the photoresist layer using a photomask in a photolithography process, wherein the photomask includes
a substrate;
a reflective multilayer over the substrate;
a capping layer over the reflective multilayer and having a hardness greater than about 8; and
an absorber layer formed on the capping layer and patterned according to an integrated circuit layout.
19. The method of claim 18 , wherein the capping layer includes one of silicon carbide, yttrium (Y), YRu, ZrRu, CrRu, RuCo, RuNi, HfRu, and RuGe.
20. The method of claim 18 , wherein
the forming the photoresist layer includes coating a material layer sensitive to an extreme ultraviolet (EUV) radiation; and
the patterning the photoresist layer includes performing a photolithography exposing process to the photoresist layer by an EUV photolithography system using the photomask and thereafter developing the photoresist layer to form a patterned photoresist layer.