Low-expansion glass substrate for a reflective mask and reflective mask
View Patent ↗A low-expansion glass substrate for a reflective mask, wherein the glass substrate is suited for a base material of a reflective mask employed in a lithographic process in semiconductor fabrication, comprises a lateral surface, a chamfered portion and a notched portion formed along an outer periphery thereof, at least one of the lateral surface, the chamfered portion and the notched portion being provided with a mirror-finished surface.
1. A low-expansion glass substrate for a reflective mask, which is suited for a base material of a reflective mask employed in a lithographic process in semiconductor fabrication, the low-expansion glass substrate comprising a lateral surface, a chamfered portion and a notched portion formed along an outer periphery thereof, all of the lateral surface, the chamfered portion and the notched portion having a surface roughness Ra of 0.05 μm or below.
2. The low-expansion glass substrate according to claim 1 , wherein at least one of the lateral surface, the chamfered portion and the notched portion formed along the outer periphery of the low-expansion glass substrate is provided with a mirror-finished surface having a surface roughness Rmax ranging from 0.05 to 0.50 μm.
3. A reflective mask comprising the low-expansion glass substrate for a reflective mask, defined in claim 2 .
4. The low-expansion glass substrate according to claim 1 , further comprising an ultra low-expansion glass substrate or ultra low-expansion crystallized glass substrate having a coefficient of thermal expansion of 0±10 ppb/° C. at 20° C.
5. A reflective mask comprising the low-expansion glass substrate for a reflective mask, defined in claim 4 .
6. A reflective mask comprising the low-expansion glass substrate for a reflective mask, defined in claim 1 .
7. A low-expansion glass substrate for a reflective mask, which is suited for a base material of a reflective mask employed in a lithographic process, the low-expansion glass substrate comprising a lateral surface formed along an outer periphery thereof and a notched portion, the lateral surface and the notched portion being covered with a metal film, a film of Si or a film of SiO 2 .
8. The low-expansion glass substrate according to claim 7 , further comprising an ultra low-expansion glass substrate or ultra low-expansion crystallized glass substrate having a coefficient of thermal expansion of 0±10 ppb/° C. at 20° C.
9. A reflective mask comprising the low-expansion glass substrate for a reflective mask, defined in claim 8 .
10. A reflective mask comprising the low-expansion glass substrate for a reflective mask, defined in claim 7 .
11. A low-expansion glass substrate for a reflective mask, which is suited for a base material of a reflective mask employed in a lithographic process, the low-expansion glass substrate comprising a lateral surface formed along an outer periphery thereof and a notched portion, wherein the lateral surface and the notched portion are etched.
12. The low-expansion glass substrate according to claim 11 , further comprising an ultra low-expansion glass substrate or ultra low-expansion crystallized glass substrate having a coefficient of thermal expansion of 0±10 ppb/° C. at 20° C.
13. A reflective mask comprising the low-expansion glass substrate for a reflective mask, defined in claim 12 .
14. A reflective mask comprising the low-expansion glass substrate for a reflective mask, defined in claim 11 .