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US 2004/0002010 A1Published application
Vortex phase shift mask for optical lithography
OwnerMarc David Levensoninventor
Life of this patent
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Abstract
A photolithography method and apparatus for producing minima of light intensity corresponding to a point in a phase shift mask is described. The phase shift in the light produced by the mask varies in a spiral fashion around the point so that the phase shift measured along lines drawn across the surface of the mask which pass through the point have a 180° jump at the point, and lines passing around the point have no jumps between 130° and 230°, and most preferably no jumps between 100° and 260°.
Claims9
An apparatus, comprising:
- a phase shift mask (PSM) substrate having a surface and a surface pattern, the surface for interacting with light of wavelength λ and intensity I0 to change the phase of the light in a pattern determined by the surface pattern, wherein the intensity of the light after interacting with the surface is determined at least in part by the phase changes induced by the surface pattern, and wherein when the light passes through a lens of a lithographic system having a numerical aperture (N.A.) so that the surface is imaged on an image plane, the intensity of the light imaged on the image plane has a plurality of point images, each point image having an intensity minimum of intensity Imin surrounded by an annular area having intensity much greater than Imin throughout the entire annular area surrounding the intensity minimum, and wherein the full width of the intensity minimum is less than λ/2 N.A.
An apparatus, comprising;
- a phase shift mask (PSM) substrate having a large plurality of phase shift areas, at least some of the large plurality of phase shift areas having at least one wedge shaped area boundary, wherein a feature is formed by n wedge shaped area boundaries of n of the large plurality of phase shift areas fitting together to surround a first point on the PSM substrate, the n phase shift areas cooperating together to produce a pattern of light intensity for light of wavelength λ and intensity I0 interacting with the n phase shift areas, wherein the pattern of light intensity has a deep minimum Imin in light intensity corresponding to the point on the PSM, and wherein the intensity of the light after interacting with the surface has intensity much greater than Imin in an annular area surrounding the first point, and wherein n is greater than or equal to four, and wherein each of the n phase shift areas has a different phase shift.
An apparatus, comprising:
- a phase shift mask (PSM) substrate having a surface and a surface pattern, the surface for interacting with light of wavelength λ and intensity I0 to change the phase of the light in a pattern determined by the surface pattern, wherein the intensity of the light after interacting with the surface is determined at least in part by the phase changes induced by the surface pattern, and wherein a plurality of points on the surface have a surface pattern surrounding each point such there exists a line nearly encircling each point such that phase changes along the line, and that the phase does not change in jumps greater than 120° along the line, and that the phase changes by at least 240° from one end of the line to the other.
Dependencies are inferred from the claim text.