PROCESS FOR PRODUCING REFLECTIVE MASK BLANK FOR EUV LITHOGRAPHY
Provision of a process for producing an EUV mask blank wherein formation of scars of a glass substrate surface or a chuck surface due to sandwiching of foreign objects such as particles between an electrostatic chuck and the glass substrate, is suppressed. A process for producing an EUV mask blank wherein an electrostatic chuck for clamping a glass substrate has a main body and a lower dielectric layer made of an organic polymer film, and electrode portion made of an electrically conductive material and an upper dielectric layer made of an organic polymer film provided in this order on the main body, wherein the upper dielectric layer includes an anode and a cathode.
1 . A process for producing a reflective mask blank for EUV lithography (EUVL), which comprises forming a reflective layer for reflecting EUV light and an absorber layer for absorbing EUV light in this order on a glass substrate by using a sputtering deposition method while the glass substrate is clamped by an electrostatic chuck;
wherein the electrostatic chuck comprises a main body, and a lower dielectric layer made of an organic polymer film, an electrode portion made of an electrically conductive material and an upper dielectric layer made of an organic polymer film provided in this order on the main body; and wherein the electrode portion includes an anode and a cathode.
2 . A process for producing a reflective mask blank for EUV lithography (EUVL), which comprises forming a reflective layer for reflecting EUV light on a glass substrate and forming an absorber layer for absorbing EUV light on the reflective layer by using a sputtering deposition method while the glass substrate is clamped by an electrostatic chuck;
wherein at least at times of forming the reflective layer and the absorber layer, the electrostatic chuck comprises a main body, and a lower dielectric layer made of an organic polymer film, an electrode portion made of an electrically conductive material and an upper dielectric layer made of an organic polymer film provided in this order on an attraction side surface of the main body; and wherein the electrode portion includes an anode and a cathode.
3 . The process for producing a reflective mask blank for EUVL according to claim 1 , wherein the lower dielectric layer of the electrostatic chuck includes at least two layers of organic polymer films.
4 . The process for producing a reflective mask blank for EUVL according to claim 2 , wherein the lower dielectric layer of the electrostatic chuck includes at least two layers of organic polymer films.
5 . The process for producing a reflective mask blank for EUVL according to claim 1 , wherein the upper dielectric layer of the electrostatic chuck includes at least two layers of organic polymer films.
6 . The process for producing a reflective mask blank for EUVL according to claim 2 , wherein the upper dielectric layer of the electrostatic chuck includes at least two layers of organic polymer films.
7 . The process for producing a reflective mask blank for EUVL according to claim 1 , wherein each of the lower dielectric layer and the upper dielectric layer of the electrostatic chuck has an insulation breakdown voltage of at least 3.0 kV.
8 . The process for producing a reflective mask blank for EUVL according to claim 2 , wherein each of the lower dielectric layer and the upper dielectric layer of the electrostatic chuck has an insulation breakdown voltage of at least 3.0 kV.
9 . The process for producing a reflective mask blank for EUVL according to claim 1 , wherein each of the lower dielectric layer and the upper dielectric layer of the electrostatic chuck has a tensile strength of at least 50 MPa.
10 . The process for producing a reflective mask blank for EUVL according to claim 2 , wherein each of the lower dielectric layer and the upper dielectric layer of the electrostatic chuck has a tensile strength of at least 50 MPa.
11 . The process for producing a reflective mask blank for EUVL according to claim 1 , wherein each of the lower dielectric layer and the upper dielectric layer of the electrostatic chuck has a tensile elongation rate of at least 20%.
12 . The process for producing a reflective mask blank for EUVL according to claim 2 , wherein each of the lower dielectric layer and the upper dielectric layer of the electrostatic chuck has a tensile elongation rate of at least 20%.
13 . The process for producing a reflective mask blank for EUVL according to claim 1 , wherein each of the lower dielectric layer and the upper dielectric layer of the electrostatic chuck has a tensile modulus of elasticity of at least 1.0 GPa.
14 . The process for producing a reflective mask blank for EUVL according to claim 2 , wherein each of the lower dielectric layer and the upper dielectric layer of the electrostatic chuck has a tensile modulus of elasticity of at least 1.0 GPa.
15 . The process for producing a reflective mask blank for EUVL according to claim 1 , wherein each of the lower dielectric layer and the upper dielectric layer of the electrostatic chuck contains at least one organic polymer film selected from the group consisting of a polyimide film, a polyolefin type material film, a silicone film, a polyvinyl chloride film and a polyethylene terephthalate film.
16 . The process for producing a reflective mask blank for EUVL according to claim 2 , wherein each of the lower dielectric layer and the upper dielectric layer of the electrostatic chuck contains at least one organic polymer film selected from the group consisting of a polyimide film, a polyolefin type material film, a silicone film, a polyvinyl chloride film and a polyethylene terephthalate film.
17 . The process for producing a reflective mask blank for EUVL according to claim 1 , wherein the thickness of the lower dielectric layer of the electrostatic chuck is at least twice the thickness of the upper dielectric layer.
18 . The process for producing a reflective mask blank for EUVL according to claim 2 , wherein the thickness of the lower dielectric layer of the electrostatic chuck is at least twice the thickness of the upper dielectric layer.
19 . The process for producing a reflective mask blank for EUVL according to claim 1 , wherein the thickness of the upper dielectric layer of the electrostatic chuck is from 10 to 500 μm.
20 . The process for producing a reflective mask blank for EUVL according to claim 2 , wherein the thickness of the upper dielectric layer of the electrostatic chuck is from 10 to 500 μm.
21 . The process for producing a reflective mask blank for EUVL according to claim 1 , wherein the electrostatic chuck has projecting portions on an attraction side surface of the upper dielectric layer so as to reduce the contact area with a glass substrate to be clamped.
22 . The process for producing a reflective mask blank for EUVL according to claim 2 , wherein the electrostatic chuck has projecting portions on an attraction side surface of the upper dielectric layer so as to reduce the contact area with a glass substrate to be clamped.
23 . The process for producing a reflective mask blank for EUVL according to claim 21 , wherein the height of the projecting portions of the electrostatic chuck is from 5 to 50 μm.
24 . The process for producing a reflective mask blank for EUVL according to claim 22 , wherein the height of the projecting portions of the electrostatic chuck is from 5 to 50 μm.
25 . The process for producing a reflective mask blank for EUVL according to claim 21 , wherein the total contact area of the projecting portions of the electrostatic chuck with the glass substrate to be clamped is from 0.1 to 25.0% of the surface area of the upper dielectric member.
26 . The process for producing a reflective mask blank for EUVL according to claim 22 , wherein the total contact area of the projecting portions of the electrostatic chuck with the glass substrate to be clamped is from 0.1 to 25.0% of the surface area of the upper dielectric member.
27 . The process for producing a reflective mask blank for EUVL according to claim 1 , wherein the anode and the cathode of the electrostatic chuck have respective comb-tooth shapes and arranged so that the comb-tooth shapes of respective electrodes are adjacent to each other with a gap.
28 . The process for producing a reflective mask blank for EUVL according to claim 2 , wherein the anode and the cathode of the electrostatic chuck have respective comb-tooth shapes and arranged so that the comb-tooth shapes of respective electrodes are adjacent to each other with a gap.
29 . The process for producing a reflective mask blank for EUVL according to claim 1 , wherein the thickness of the electrode portion of the electrostatic chuck is at most 10 μm.
30 . The process for producing a reflective mask blank for EUVL according to claim 2 , wherein the thickness of the electrode portion of the electrostatic chuck is at most 10 μm.
31 . The process for producing a reflective mask blank for EUVL according to claim 1 , wherein an electrically conductive film is provided on a surface of the glass substrate to be clamped by the electrostatic chuck.
32 . The process for producing a reflective mask blank for EUVL according to claim 2 , wherein an electrically conductive film is provided on a surface of the glass substrate to be clamped by the electrostatic chuck.