Patent Number: 050349724
Section: claims

1. A method of producing a sheet of material which is stretched over a frame and which has a planar and smooth surface with a low defect density, comprising the steps of: applying a layer of a release material to one surface of a substrate while leaving an area along the outer edge of the substrate free of release material;  covering said release material layer and said release material layer free edge area of said substrate with a layer of the sheet material;  connecting a frame to said layer of sheet material within a region occupied by the release layer;  severing said layer of sheet material around the periphery of the frame;  releasing the portion of the layer of sheet material connected to the frame from said one surface of substrate and from said release material layer; and  removing any release material remaining on the surface of said portion of said layer of sheet material.  applying a layer of a release material to one surface of a substrate while leaving an area along the outer edge of the substrate free of release layer material;  covering said release material layer and said release material layer free edge area of said substrate with a layer of an X-ray transparent material;  forming desired X-ray absorber structures on a portion of the surface of said X-ray transparent layer overlying said layer of release material;  connecting a frame to said surface of said X-ray transparent layer in a region overlying said layer of release material and so as to surround said absorber structures;  severing said layer of X-ray transparent material around the periphery of the frame;  releasing the portion of said X-ray transparent layer connected to the frame from said one surface of said substrate and from said release material layer; and  removing any release material remaining on the surface of said layer of X-ray transparent material. 2. A method as defined in claim 1 wherein the material of said release layer is a material which can be removed from the substrate as well as from the sheet material without adversely influencing the surface of the sheet. 3. A method as defined in claim 2, wherein carbon is used as the material for the release layer. 4. A method as defined in claim 3 wherein the substrate is formed of silicon and the sheet material is a metal. 5. A method as defined in claim 4 wherein the metal is titanium. 6. A method as defined in claim 1 wherein said sheet material is a material which is transparent to X-ray radiation. 7. A method as defined in claim 6 wherein said X-ray transparent material is a metal. 8. A method as defined in claim 1 wherein said frame is ring shaped. 9. A method as defined in claim 1 wherein said release layer has a thickness of about 100 nm, and said layer of the sheet material has a thickness of approximately 2-3 .mu.m. 10. A method as defined in claim 1 wherein said substrate has a diameter of approximately 100 mm and said release material free edge has a width of about 1 mm. 11. A method according to claim 1 further comprising forming X-ray absorber structures on a surface of said layer of sheet material to provide an X-ray mask. 12. A method as defined in claim 1 further comprising prior to said step of connecting a frame, forming X-ray absorber structures on a portion of the surface of said layer of the sheet material which will be surrounded by the frame, whereby an X-ray mask is produced by said method. 13. A method of producing an X-ray mask comprising: 14. A method as defined in claim 13 wherein said X-ray transparent material is a metal and said step of covering includes sputtering the metal. 15. A method as defined in claim 13 wherein said release material is carbon.