Nikon Corporation

Hiroshi Ichihara

Takashi Gemma

Shigeru Nakayama

Hajime Ichikawa

Bruce Jacobsen

A method of manufacturing a projection optical system ( ) for projecting a pattern from a reticle to a photosensitive substrate, comprising a surface-shape-measuring step wherein the shape of an optical test surface ( ) of an optical element ( ) which is a component in the projection optical system is measured by causing interference between light from the optical surface ( ) and light from an aspheric reference surface ( ) while the optical test surface ( ) and said reference surface ( ) are held in integral fashion in close mutual proximity. A wavefront-aberration-measuring step is included, wherein the optical element is assembled in the projection optical system and the wavefront aberration of the projection optical system is measured. A surface correction calculation step is also included wherein the amount by which the shape of the optical test surface should be corrected is calculated based on wavefront aberration data obtained at the wavefront-aberration-measuring step and surface shape data obtained from the surface-shape-measuring step. The method also includes a surface shape correction step wherein the shape of the optical test surface is corrected based on calculation performed at the surface correction calculation step. Surface shape measuring interferometer systems and wavefront-aberration-measuring interferometer systems ( J- Q) used in performing the manufacturing method are also disclosed.

Interferometer system and method of manufacturing projection optical system using same

Interferometer that measures aspherical surfaces

Apparatus and methods are disclosed for measuring the surface topography of a test surface, such as a spherical or aspherical surface of a refractive or reflective optical element. The test surface is measured by detecting the state of interference fringes generated by interference of a reference light beam and a measurement light beam that interacts (e.g., reflects from) the test surface. The reference and measurement beams are produced by a point light source having a reflective surface. The point light source is disposed between a source of input light and the test surface. The measurement beam (after interacting with the test surface) and the reference beam are caused to interfere with each other to produce a first interference-fringe state. The distance between the point light source and the test surface can be changed between production of the first interference-fringe state and production of a second interference-fringe state. The profile of the test surface is determined by analyzing the resulting interference fringes. A null element can be used to convert a spherical wavefront of the measurement beam into an aspherical wavefront corresponding to the aspherical test surface, or to convert an aspherical wavefront generated by reflection of a spherical wavefront from an aspherical test surface into a spherical or planar wavefront.

Interferometric apparatus and methods for measuring surface topography of a test surface

A method of manufacturing a projection optical system (,) for projecting a pattern from a reticle to a photosensitive substrate, comprising a surface-shape-measuring step wherein the shape of an optical test surface (,) of an optical element (,) which is a component in the projection optical system is measured by causing interference between light from the optical surface (,) and light from an aspheric reference surface (,) while the optical test surface (,) and said reference surface (,) are held in integral fashion in close mutual proximity. A wavefront-aberration-measuring step is included, wherein the optical element is assembled in the projection optical system and the wavefront aberration of the projection optical system is measured. A surface correction calculation step is also included wherein the amount by which the shape of the optical test surface should be corrected is calculated based on wavefront aberration data obtained at the wavefront-aberration-measuring step and surface shape data obtained from the surface-shape-measuring step. The method also includes a surface shape correction step wherein the shape of the optical test surface is corrected based on calculation performed at the surface correction calculation step. Surface shape measuring interferometer systems and wavefront-aberration-measuring interferometer systems (,J-,Q) used in performing the manufacturing method are also disclosed.

Growing community of inventors

Yokohama, Japan

Hiroshi Ichihara