US 8,027,091 B2 · Method for correcting optical proximity effects

Abstract

In a method for correcting optical proximity effects (Optical Proximity Correction, OPC) when imaging a pattern, arranged in the object surface of a projection objective, into the image surface of the projection objective with the aid of a projection objective, a multiplicity of optical elements and at least one pupil surface that is Fourier-transformed to the image surface are arranged between the object surface and the image surface. An optical filtering of the light used for the imaging is carried out with the aid of at least one OPC filter inserted between the object surface and the image surface in accordance with an OPC filter function that is adapted to the pattern and corresponds to a spatially dependent transmission filtering in the region of the pupil surface of the imaging system. The profile of the pupil transmission function is adapted with the aid of the OPC filter to the pattern, characterized by the position of diffraction orders, of the mask such that there is respectively present for all the diffraction orders contributing to the imaging an optimized pupil transmission which leads to a minimization of line width variations, dependent on line density, in the image surface.

Claims37

Dependent claims

Method for correcting optical proximity effects when imaging a pattern, arranged in an object surface of a projection objective, into an image surface of the projection objective, wherein a multiplicity of optical elements and at least one pupil surface that is Fourier-transformed to the image surface are arranged between the object surface and the image surface, comprising:

optical filtering of imaging light with at least one optical proximity correction (OPC) filter inserted between the object surface and the image surface in accordance with an OPC-filter function that is adapted to the pattern and corresponds to a spatially dependent transmission filtering in a region of the pupil surface, and
selecting the OPC-filter function for the projection objective in accordance with a position of diffraction orders caused by the pattern such that variations in line widths in the image surface that are generated by interference of the diffraction orders are weaker than corresponding variations for the projection objective without the optical filtering.

Method for producing an optical filter for carrying out an optical filtering in accordance with a filter function, comprising:

defining a pattern that has a first partial pattern with a first line density, and at least a second partial pattern with a second line density that differs from the first line density;
calculating an imaging of the pattern, arranged in an object surface of a projection objective, into an image surface of the projection objective, wherein a multiplicity of optical elements and at least one pupil surface that is Fourier-transformed to the image surface are arranged between the object surface and the image surface;
defining a filter function for optically filtering light used for the imaging, the filter function corresponding to a spatially dependent transmission filtering in a region of the pupil surface of the projection objective;
determining a variation in line widths in the image surface of the projection objective that are generated by interference of diffraction orders of the pattern;
optimizing the filter function by stepwise variation in the filter function and repeated determination of the variation in the line width in order to determine an optimized filter function in which the variation in the line widths that are generated lies below a prescribed limit value;
and
producing the optical filter in accordance with the optimized filter function.

4 more elements

Dependencies are inferred from the claim text.

Method for correcting optical proximity effects

Life of this patent

Method for correcting optical proximity effects

Life of this patent

Abstract

Claims37