Reflective mask blank for EUV lithography and reflective mask for EUV lithography
View Patent ↗A reflective mask for an extreme ultra violet (EUV) lithography obtained by forming a mask pattern in an absorber layer of an reflective mask blank is useful in semiconductor production. The EUV reflective mask has two regions of a mask pattern region and a region outside the mask pattern region. The mask pattern region has the absorber layer and a non-absorber layer on the reflective layer of an substrate, wherein the region outside the mask pattern region has an EUV reflective layer, an EUV absorber layer, and a light shielding layer for suppressing reflection of EUV light and DUV-Vis light having a wavelength of from 190 to 500 nm. The EUV reflective mask reduces unnecessary exposure of resist formed on a substrate to reflected light from the region outside the mask pattern region and reduces a pattern size to produce an accurate transfer pattern.
1. A reflective mask for EUV lithography (EUVL) having a mask pattern region and a region outside the mask pattern region on a substrate, wherein
in the mask pattern region, a reflective layer for reflecting EUV light is formed on the substrate, and on the reflective layer, a portion having an absorber layer for absorbing EUV light provided and a portion having no absorber layer provided are arranged to form a mask pattern; and
in the region outside the mask pattern region, a reflective layer for reflecting EUV light, an absorber layer for absorbing EUV light and a light shielding layer for suppressing reflection of EUV light and DUV-Vis light having a wavelength of from 190 to 500 nm are formed in this order on the substrate; and
wherein in the region outside the mask pattern region, the average EUV reflectivity at a wavelength range of from 13.3 to 13.7 nm from the surface of the light shielding layer is less than 0.5%, and the DUV-Vis reflectivity at a wavelength of from 190 to 500 nm from the surface of the light shielding layer is at most 30%.
2. The reflective mask for EUVL according to claim 1 , wherein the light shielding layer contains chromium (Cr) and oxygen (O), and in the light shielding layer, the Cr content is from 15 to 40 at %, and the O content is from 60 to 85 at %.
3. The reflective mask for EUVL according to claim 1 , wherein the light shielding layer contains chromium (Cr), oxygen (O) and nitrogen (N); and in the light shielding layer, the Cr content is from 15 to 40 at %, the total content of O and N is from 60 to 85 at %, and the compositional ratio of O to N is from 9:1 to 5:5.
4. The reflective mask for EUVL according to claim 1 , wherein the light shielding layer has a two-layer structure comprising a layer (upper layer) on the surface side and a layer (lower layer) on the substrate side, wherein:
the upper layer of the light shielding layer contains chromium (Cr) and oxygen (O);
and the Cr content is from 15 to 40 at %, and the O content is from 60 to 85 at %; and
the lower layer of the light shielding layer contains Cr and nitrogen (N); and the Cr content is from 40 to 97 at %, and the N content is from 3 to 60 at %.
5. The reflective mask for EUVL according to claim 1 , wherein the light shielding layer has a two-layer structure comprising a layer (upper layer) on the surface side and a layer (lower layer) on the substrate side, wherein:
the upper layer of the light shielding layer contains chromium (Cr), oxygen (O) and nitrogen (N); and the Cr content is from 15 to 40 at %, the total content of O and N is from 60 to 85 at %, and the compositional ratio of O to N is from 9:1 to 5:5; and
the lower layer of the light shielding layer contains Cr and N; and the Cr content is from 40 to 97 at %, and the N content is from 3 to 60 at %.
6. The reflective mask for EUVL according to claim 5 , wherein in the light shielding layer, an interlayer is present between the upper layer and the lower layer.
7. The reflective mask for EUVL according to claim 5 , wherein in the light shielding layer, the thickness of the upper layer is from 5 to 80 nm, the thickness of the lower layer is from 5 to 80 nm, and the total thickness of the upper layer and the lower layer is from 10 to 100 nm.
8. The reflective mask for EUVL according to claim 1 , wherein the light shielding layer has a multilayer structure having at least 3 layers, wherein a first layer and a second layer which are alternately stacked from the absorber layer side, wherein:
each of the first layer and the second layer is selected from the group consisting of a film containing chromium (Cr) and oxygen (O), a film containing chromium (Cr) and nitrogen (N) and a film containing chromium (Cr), oxygen (O) and nitrogen (N), provided that the film compositions of the first layer and the second layer are different from each other.
9. The reflective mask for EUVL according to claim 8 , wherein in the multilayer structure:
the first layer contains chromium (Cr), oxygen (O) and nitrogen (N); and the Cr content is from 15 to 40 at %, the total content of O and N is from 60 to 85 at %, and the compositional ratio of O to N is from 9:1 to 5:5; and
the second layer contains Cr and nitrogen (N); and the Cr content is from 40 to 97 at %, and the N content is from 3 to 60 at %.
10. The reflective mask for EUVL according to claim 1 , wherein the thickness of the light shielding layer is from 10 to 100 nm.
11. A reflective mask for EUV lithography (EUVL) having a mask pattern region and a region outside the mask pattern region on a substrate, wherein
in the mask pattern region, a reflective layer for reflecting EUV light is formed on the substrate, and on the reflective layer, a portion having an absorber layer for absorbing EUV light and a low reflective layer for improving contrast at the time of inspection of a mask pattern, provided in this order, and a portion having no absorber layer or low reflective layer provided are arranged to form a mask pattern; and
in the region outside the mask pattern region, a reflective layer for reflecting EUV light, an absorber layer for absorbing EUV light, a low reflective layer for improving contrast at the time of pattern inspection and a light shielding layer for suppressing reflection of EUV light and DUV-Vis light are formed in this order on the substrate; and
wherein in the region outside the mask pattern region, the average EUV reflectivity at a wavelength range of from 13.3 to 13.7 nm from the surface of the light shielding layer is less than 0.5%, and the DUV-Vis reflectivity at a wavelength of from 190 to 500 nm from the surface of the light shielding layer is at most 30%.
12. A reflective mask blank for EUVL, having a reflective layer for reflecting EUV light, an absorber layer for absorbing EUV light and a light shielding layer for suppressing reflection of EUV light and DUV-Vis light, formed in this order on a substrate, wherein the average EUV reflectivity at a wavelength range of from 13.3 to 13.7 nm from the surface of the light shielding layer is less than 0.5%, and the DUV-Vis reflectivity at a wavelength of from 190 to 500 nm from the surface of the light shielding layer is at most 30%.
13. A reflective mask blank for EUVL, having a reflective layer for reflecting EUV light, an absorber layer for absorbing EUV light, a low reflective layer for improving contrast at the time of pattern inspection and a light shielding layer for suppressing reflection of EUV light and DUV-Vis light, formed in this order on a substrate, wherein the average EUV reflectivity at a wavelength range of from 13.3 to 13.7 nm from the surface of the light shielding layer is less than 0.5%, and the DUV-Vis reflectivity at a wavelength of from 190 to 500 nm from the surface of the light shielding layer is at most 30%.
14. The reflective mask blank for EUVL according to claim 12 , wherein the light shielding layer contains chromium (Cr), oxygen (O) and nitrogen (N); and in the light shielding layer, the Cr content is from 15 to 40 at %, the total content of O and N is from 60 to 85 at %, and the compositional ratio of O to N is from 9:1 to 5:5.
15. The reflective mask blank for EUVL according to claim 12 , wherein the light shielding layer has a two-layer structure comprising a layer (upper layer) on the surface side and a layer (lower layer) on the substrate side, wherein:
the upper layer of the light shielding layer contains chromium (Cr) and oxygen (O); and the Cr content is from 15 to 40 at %, and the O content is from 60 to 85 at %; and
the lower layer of the light shielding layer contains Cr and nitrogen (N); and the Cr content is from 40 to 97 at %, and the N content is from 3 to 60 at %.
16. The reflective mask blank for EUVL according to claim 12 , wherein the light shielding layer has a two-layer structure comprising a layer (upper layer) on the surface side and a layer (lower layer) on the substrate side, wherein:
the upper layer of the light shielding layer contains chromium (Cr), oxygen (O) and nitrogen (N); and the Cr content is from 15 to 40 at %, the total content of O and N is from 60 to 85 at %, and the compositional ratio of O to N is from 9:1 to 5:5; and
the lower layer of the light shielding layer contains Cr and N; and the Cr content is from 40 to 97 at %, and the N content is from 3 to 60 at %.
17. The reflective mask blank for EUVL according to claim 16 , wherein in the light shielding layer, an interlayer is present between the upper layer and the lower layer.
18. The reflective mask blank for EUVL according to claim 16 , wherein in the light shielding layer, the thickness of the upper layer is from 5 to 80 nm, the thickness of the lower layer is from 5 to 80 nm, and the total thickness of the upper layer and the lower layer is from 10 to 100 nm.
19. The reflective mask blank for EUVL according to claim 12 , wherein the light shielding layer has a multilayer structure having at least 3 layers, wherein a first layer and a second layer which are alternately stacked from the absorber layer side, wherein:
each of the first layer and the second layer is selected from the group consisting of a film containing chromium (Cr) and oxygen (O), a film containing chromium (Cr) and nitrogen (N) and a film containing chromium (Cr), oxygen (O) and nitrogen (N), provided that the film compositions of the first layer and the second layer are different from each other.
20. The reflective mask blank for EUVL according to claim 19 , wherein in the multilayer structure:
the first layer contains chromium (Cr), oxygen (O) and nitrogen (N); and the Cr content is from 15 to 40 at %, the total content of O and N is from 60 to 85 at %, and the compositional ratio of O to N is from 9:1 to 5:5; and
the second layer contains Cr and nitrogen (N); and the Cr content is from 40 to 97 at %, and the N content is from 3 to 60 at %.
21. The reflective mask blank for EUVL according to claim 12 , wherein the thickness of the light shielding layer is from 10 to 100 nm.
22. The reflective mask blank for EUVL according to claim 12 , wherein the light shielding layer contains chromium (Cr) and oxygen (O), and in the light shielding layer, the Cr content is from 15 to 40 at %, and the O content is from 60 to 85 at %.