Projection exposure method and apparatus
AssigneeNikon Corporation
InventorNaomasa Shiraishi
Life of this patent
Estimating the term…
Abstract
In projection exposure of isolated pattern such as a contact hole, in order to increase the depth of focus a coherence reducing member is disposed on a Fourier transform plane in an image-forming optical path between a mask and a sensitized base, so that coherence is reduced between image-forming beams respectively passing through a plurality of different, concentric regions around the optical axis of the projection optical system on the Fourier transform plane. The coherence reducing member may be a polarization state control member for making a difference in polarization state, a member for making a difference in optical path length, or space filters with different shapes.
Claims51
A projection exposure apparatus comprising:
- illuminating means for illuminating a mask on which a pattern is formed, with illumination light for exposure at a predetermined numerical aperture;
- a projection optical system for receiving emergent light from the pattern on said mask to project a focused image of said pattern onto a sensitized base;
- and
- a coherence reducing element disposed on a Fourier transform plane or on a plane close thereto in an image-forming optical path between said mask and said sensitized base, for reducing coherence between a plurality of image-forming beams respectively passing through a plurality of concentric, different regions around an optical axis of said projection optical system on said Fourier transform plane or on the plane close thereto, said coherence reducing element setting to not less than 0.5 a coherence factor (σ value) determined by a ratio between a numerical aperture of said illumination light by said illuminating means and a numerical aperture of said projection optical system.
A projection exposure apparatus comprising:
- illuminating means for illuminating a mask on which a pattern is formed, with illumination light for exposure;
- a projection optical system for receiving emergent light from the pattern on said mask to project a focused image of said pattern onto a sensitized base;
- a coherence reducing element disposed on a Fourier transform plane or on a plane close thereto in an image-forming optical path between said mask and said sensitized base, for reducing coherence between a plurality of image-forming beams respectively passing through a plurality of concentric, different regions about an optical axis of said projection optical system on said Fourier transform plane or on the plane close thereto;
- and
- means provided at a position of a light source image plane of said illuminating means substantially conjugate with said Fourier transform plane, for making annular a shape of a light source image on said light source image plane.
A projection exposure apparatus comprising:
- illuminating means for illuminating a mask on which a pattern is formed, with illumination light for exposure;
- a projection optical system for receiving emergent light from the pattern on said mask to project a focused image of said pattern onto a sensitized base;
- a coherence reducing element disposed on a Fourier transform plane or on a plane close thereto in an image-forming optical path between said mask and said sensitized base, for reducing coherence between a plurality of image-forming beams respectively passing through a plurality of concentric, different regions about an optical axis of said projection optical system on said Fourier transform plane or on the plane close thereto;
- and
- means provided at a position of a light source image plane of said illuminating means substantially conjugate with said Fourier transform plane, for forming a plurality of light source images separate from each other on said light source image plane.
A projection exposure apparatus comprising:
- illuminating means for illuminating a mask on which at least two hole patterns are formed at a predetermined pitch, with illumination light for exposure;
- a projection optical system for receiving emergent light from the hole patterns on said mask to project focused images of said hole patterns onto a sensitized base;
- a coherence reducing element disposed on a Fourier transform plane or on close plane close thereto in an image-forming optical path between said mask and said sensitized base, for reducing coherence between a plurality of image-forming beams respectively passing through a plurality of concentric, different regions around an optical axis of said projection optical system on said Fourier transform plane or on the plane close thereto;
- and
- a setting member for setting a range of incident angle of said illumination light into the mask such that one coherence function of the illumination light on the pattern surface of said mask takes a value at a position of one of the two hole patterns separated at said predetermined pitch and another value of approximately zero or opposite in sign to said value at a position of the other of the two hole patterns.
A projection exposure apparatus for transferring an image of a pattern formed on a mask onto a substrate, comprising:
- a transforming member disposed between said mask and said substrate to transform light from said pattern which passes therethrough into plural lights reduced in coherence therebetween.
A projection exposure method of exposing a substrate with a light having passed through a mask, comprising:
- transforming, between said mask and said substrate, said light having passed through the mask into plural lights reduced in coherence therebetween on said substrate to guide the transformed plural lights onto said substrate.
A method of making an exposure apparatus that exposes a substrate with an illumination light through a mask, comprising:
- disposing a transforming member between said mask and said substrate to transform light that passes therethrough into plural lights reduced in coherence therebetween.
A method of producing a semiconductor integrated circuit by a projection exposure apparatus which illuminates a mask formed with a pattern to project a light from said pattern to a substrate, comprising:
- transforming, between said mask and said substrate, the light from said pattern into plural lights reduced in coherence therebetween;
- and
- exposing said substrate with said plural lights reduced in coherence in producing the semiconductor integrated circuit.
Dependencies are inferred from the claim text.