Mask for manufacturing semiconductor device and method of manufacture thereof

Abstract

The present invention relates to a microminiaturization technique to achieve the miniaturization and higher integration of IC chips and to the improvement of a mask used in its manufacturing process. In other words, the phase of lights transmitted through the mask is controlled within one mask pattern. Specifically, a transparent film is formed in such a manner that it covers a mask pattern along a pattern formed by magnifying or demagnifying the mask pattern, or otherwise a groove is formed in a mask substrate. A phase difference of 180° is generated between the lights transmitted through the mask substrate and the transparent film or the groove, causing interference with each light to offset each other. Therefore, the pattern transferred onto a wafer has an improved resolution, being used in the invention.

What is claimed is: 
     
       1. A mask for manufacturing a semiconductor device comprising: a transparent substrate having main and back surfaces;   a circuit pattern formed on said main surface and comprising a first region comprising a metal layer and a second region where said transparent substrate is exposed; and   a means for shifting a phase of light, formed at both ends of said first region and in a part of said second region and not in the whole of said second region.   
     
     
       2. A mask for manufacturing a semiconductor device according to claim 1, wherein said means for shifting phase of light is formed in contact with at least a portion of said first region which is in the vicinity of said second region. 
     
     
       3. A mask for manufacturing a semiconductor device according to claim 2, wherein said means for shifting from the group consisting of indium oxide, silicon dioxide, silicon nitride, magnesium fluoride, and polymethyl methacrylate. 
     
     
       4. A mask for manufacturing a semiconductor device according to claim 2, wherein said means for shifting phase of light is a groove formed extending into said transparent substrate. 
     
     
       5. A mask for manufacturing a semiconductor device comprising: a transparent substrate having main and back surfaces;   a circuit pattern formed on said main surface and comprising a light shield region .[.comprising.]. .Iadd.having .Iaddend.a metal layer .Iadd.on the main surface in the light shield region, .Iaddend.and a transmission region wherein said transparent substrate is exposed, the lower surface of said metal layer being in contact with .Iadd.the main surface of .Iaddend.said transparent substrate; .[.a second groove in part of the light shield region and having a depth reaching said transparent substrate from an upper surface opposite to a lower surface, and said first groove for shifting phase of light being located below said second groove.]. .Iadd.and   a first groove region for shifting phase of transmitted light, formed extending from an upper surface of said metal layer into a depth of the transparent substrate in a portion of the light shield region, said portion of the light shield region in which said first groove region is formed being spaced from the transmission region, and a width of the first groove region being sufficiently narrow so as not to form an independent bright image corresponding thereto, said portion being located such that light transmitted through the first groove region and light transmitted through the transmission region interfere with each other at an end portion of the light shield region adjacent the transmission region, whereby resolution is improved due to interference between light beams transmitted through the first groove region and the transmission region, when the circuit pattern is optically projected onto a wafer on which the semiconductor device is to be formed.Iaddend..   
     
     
       6. A mask for manufacturing a semiconductor device according to claim .[.5.]. .Iadd.36.Iaddend., wherein said means for shifting phase of light is a transparent film of a material selected from the group consisting of indium oxide, silicon dioxide, silicon nitride, magnesium fluoride, and polymethyl methacrylate. 
     
     
       7. A mask for manufacturing a semiconductor device according to claim .[.5.]. .Iadd.36.Iaddend., wherein said means for shifting phase of light is a groove formed extending into said transparent substrate. 
     
     
       8. A mask for manufacturing a semiconductor device comprising: a transparent substrate having main and back surfaces;   a circuit pattern formed on said main surface and comprising a first region comprising a light shield region for shielding irradiation light and a transmission region wherein said transparent substrate is exposed; and   a means for shifting phase of light, formed in a part of said transmission region and not in the whole thereof, wherein the means for shifting phase o light has a thickness x, the thickness x of said means for shifting phase of light is,   x=λ/(2(n.sub.1 -1))       λ: wavelength of irradiation light   n 1  : reference index of said means for shifting phase of light.   
     
     
       9. A mask for manufacturing a semiconductor device according to claim 8, wherein said means for shifting phase of light is formed in contact with at least a portion of said light shield region which is in the vicinity of the transmission region. 
     
     
       10. A mask for manufacturing a semiconductor device according to claim 9, wherein said means for shifting phase of light is a transparent film of a material selected from the group consisting of indium oxide, silicon dioxide, silicon nitride, magnesium fluoride, and polymethyl methacrylate. 
     
     
       11. A mask for manufacturing a semiconductor device according to claim 9, wherein said means for shifting phase of light is a groove formed extending into said transparent substrate. 
     
     
       12. A mask for manufacturing a semiconductor device according to claim 11, wherein the thickness x of the means for shifting phase of light is the depth d of said groove, the depth d being,   d=λ/(2(n.sub.2 -1))     λ: wavelength of irradiation light   n 2  : refractive index of the transparent substrate.   
     
     
       13. A mask for manufacturing a semiconductor device according to claim 8, wherein said means for shifting phase of light is formed in the central part of said transmission region. 
     
     
       14. A mask for manufacturing a semiconductor device according to claim 13, wherein said means for shifting phase of light is a transparent film of a material selected from the group consisting of indium oxide, silicon dioxide, silicon nitride, magnesium fluoride, and polymethyl methacrylate. 
     
     
       15. A mask for manufacturing a semiconductor device according to claim 13, wherein said means for shifting phase of light is a groove formed extending into said transparent substrate. 
     
     
       16. A mask for manufacturing a semiconductor device according to claim 14, wherein the thickness x of said means for shifting phase of light is,   x=λ/(2(n.sub.1 -1))     λ: wavelength or iradiation light   n 1  : refractive index of said means for shifting phase of light.   
     
     
       17. A mask for manufacturing a semiconductor device according to claim 15, wherein the depth d of said groove is,   d=λ/(2(n.sub.2 -1))     λ: wavelength of irradiation light   n 2  : refractive index of said transparent substrate.   
     
     
       18. A method of manufacturing a mask comprising: a) preparing a transparent substrate having main and back surfaces;   b) forming a metal layer over said main surface;   c) coating a resist on an upper surface of said metal layer in a desired circuit pattern;   d) etching said metal layer to form said circuit pattern, leaving a part of the metal layer, so as to form a transmission region where said transparent substrate is exposed and a light shield region comprising said part of said metal layer; and   e) determining a region where a means for shifting phase of light is formed by magnifying said circuit pattern, and forming said means for shifting phase of light, in a part of said transmission region, said means for shifting phase of light being in said part of said transmission region and not in the whole thereof.   
     
     
       19. A method of manufacturing a mask according to claim 18, wherein said means for shifting phase of light is formed at both ends of said light shield region and in contact with said light shield region. 
     
     
       20. A method of manufacturing a mask according to claim 19, wherein said means for shifting phase of light is a transparent film of a material selected from the group consisting of indium oxide, silicon dioxide, silicon nitride, magnesium fluoride, and polymethyl methacrylate. 
     
     
       21. A method of manufacturing a mask according to claim 19, wherein said means for shifting phase of light is a groove formed extending into said transparent substrate. 
     
     
       22. A method of manufacturing a mask according to claim 18, wherein said means for shifting phase of light is formed at an area surrounding said light shield region and in a central part of said transmission region. 
     
     
       23. A method of manufacturing a mask according to claim 22, wherein said means for shifting phase of light is a transparent film of a material selected from the group consisting of indium oxide, silicon dioxide, silicon nitride, magnesium fluoride, or polymethyl methacrylate. 
     
     
       24. A method of manufacturing a mask according to claim 22, wherein said means for shifting phase of light is a groove formed extending into said transparent substrate. 
     
     
       25. A method of manufacturing a mask according to claim 18, wherein said means for shifting phase of light is formed by a focused ion beam. 
     
     
       26. A mask for manufacturing a semiconductor device according to claim 1, wherein said transparent substrate is a transparent glass substrate. 
     
     
       27. A mask for manufacturing a semiconductor device according to claim 8, wherein said transparent substrate is a transparent glass substrate. 
     
     
       28. A method of manufacturing a mask according to claim 18, wherein said transparent substrate is a transparent glass substrate. .[.29. A mask for manufacturing a semiconductor device according to claim 1, wherein said second region has corners, and wherein sub-transmission regions are provided at said corners so as to increase light intensity at the corners..]..[.30. A method of manufacturing a mask according to claim 18, wherein the transmission region has corners, and wherein the method includes the further step of forming sub-transmission regions at the 
     
     
        corners, so as to increase light intensity at the corners..].31. A .[.method of.]. .Iadd.mask for .Iaddend.manufacturing a semiconductor device according to claim 3, wherein said transparent film extends over said first region, and extends so as to .Iadd.be .Iaddend.formed in said 
     
     
        part of said second region. 32. A mask for manufacturing a semiconductor device according to claim 4, wherein said groove is arranged along the 
     
     
        contour of said metal layer. 33. A mask for manufacturing a semiconductor device comprising: a transparent substrate having main and back surfaces;   a circuit pattern formed on said main surface and comprising a first region comprising a metal layer and a second region where said transparent substrate is exposed; and   a means for shifting a phase of light, formed in a part of said second region and not in the whole thereof, and adjacent to a periphery of said   
     
     
        first region. 34. A mask for manufacturing a semiconductor device according to claim 33, wherein said transparent substrate is a transparent 
     
     
        glass substrate. 35. A mask for manufacturing a semiconductor device according to claim 33, wherein the thickness x of said means for shifting phase of light is,   x=λ/(2(n.sub.1 -1))     λ: wavelength of irradiation light   
     
     
       n 1  : refractive index of said means for shifting phase of light. 36. A mask for manufacturing a semiconductor device according to claim .[.34.]. .Iadd.33.Iaddend., wherein said means for shifting phase of light is 
     
     
        formed in a central part of said second region. 37. A mask for manufacturing a semiconductor device according to claim .[.36.]. .Iadd.5.Iaddend., wherein the depth d .[.of said first groove for shifting phase of light.]. .Iadd.into the transparent substrate .Iaddend.is,   d=λ/2(n.sub.1 -1))     λ: wavelength of irradiation light   n 1  : refractive index of said transparent substrate. .Iadd.38. A mask for manufacturing a semiconductor device, comprising:   a transparent substrate having main and back surfaces;   a circuit pattern formed on said main surface and comprising a light shield region and a light transmission region, the light transmission region having corners;   a means for shifting a phase of light, formed in the light shield region; and   sub-transmission regions adjacent the corners of the light transmission region, the sub-transmission regions increasing light intensity at the corners. .Iaddend..Iadd.39. A mask for manufacturing a semiconductor device according to claim 38, further comprising a metal layer on the main surface of the transparent substrate in the light shield region, and wherein in the light transmission region the transparent substrate is exposed. .Iaddend..Iadd.40. A mask for manufacturing a semiconductor device according to claim 38, wherein said means for shifting a phase of light, formed in said light shield region, is spaced from said light transmission region. .Iaddend..Iadd.41. A mask for manufacturing a semiconductor device according to claim 40, wherein a width of said means for shifting a phase of light is sufficiently narrow so as not to form an independent bright image corresponding thereto, and wherein said means for shifting a phase of light is positioned relative to the light transmission region such that light transmitted through the light transmission region and through the means for shifting a phase of light interfere with each other at an end portion of the light shield region adjacent the light transmission region, whereby resolution is improved due to interference between light beams transmitted through the means for shifting a phase of light and through the light transmission region, when the circuit pattern is optically projected onto a wafer on which the semiconductor device is to be formed. .Iaddend.