Illumination optical system

An illumination optical system usable with a projection optical system for projecting a pattern of a first object upon a second object, for illuminating a surface of the first object, said illumination optical system comprising:

• a multi-beam producing system for receiving light from a light source and for forming a secondary light source which emits a plurality of light beams;
• a condensing optical system for directing the light beams to the surface to be illuminated, said condensing optical system being effective to form an image of said secondary light source on a pupil of the projection optical system and also being effective to superimpose the light beams upon one another on the surface to be illuminated;
• and
• said condensing optical system including optical means disposed in a path of the light beams from said multi-beam producing system, said optical means having a variable refracting power which is variable in accordance with the size of the surface to be illuminated;
• wherein said image of said secondary light source is formed at a constant position irrespective of the change in the refracting power of said optical means.

An illumination optical system usable with a projection optical system for projecting a pattern of a first object upon a second object, for illuminating a surface of the first object, said illumination optical system comprising:

• a multi-beam producing system for receiving light from a light source and for forming a secondary light source which emits a plurality of light beams, said multi-beam producing system having a variable refracting power which is variable in accordance with the size of the surface to be illuminated;
• and
• a condensing optical system effective to direct the light beams from said multi-beam producing system to the surface to be illuminated, and also being effective to superimpose the light beams upon one another on the surface to be illuminated, said condensing optical system being further effective to bring said secondary light source into a conjugate relationship with a pupil of the projection optical system;
• wherein the conjugate relationship is maintained irrespective of the change in the refracting power of said multi-beam producing system.

An illumination device comprising:

• light source means for supplying light;
• and
• an optical system for receiving the light from said light source means and for directing the light to a surface to be illuminated, said optical system having optical means whose refracting power is variable in accordance with the size of the surface to be illuminated;
• wherein said optical system has a rear principal plane which is at a distance from the surface to be illuminated, substantially corresponding to the focal length of said optical system and wherein said distance and said focal length are in a fixed relation irrespective of the change in the refracting power of said optical means.

An illumination device comprising:

• light source means for supplying light;
• means for receiving light from said light source means and for forming, by use of the light, a secondary light source;
• condensing optical means for receiving light from said secondary light source and for directing the light to a surface to be illuminated;
• and
• optical means operable to change the range of illumination to be defined by the light from said secondary light source, in accordance with the size of the surface to be illuminated, said optical means changing the range of illumination by changing an angle of emission of light from said secondary light source while retaining a constant angle of incidence of the light upon the surface to be illuminated.

A projection exposure system usable with a mask having a circuit pattern and a wafer, said projection exposure system comprising:

• supplying means for supplying light;
• secondary light source forming means, disposed to receive the light from said supplying means, for forming a secondary light source by use of the received light;
• an illumination optical system disposed to receive light from said secondary light source, for illuminating the mask by use of the received light, said illumination optical system having an optical means which has a variable refracting power;
• and
• a projection optical system operable to form an image of the circuit pattern of the mask upon the wafer, said projection optical system having a pupil which is in a conjugate relationship with said secondary light source;
• wherein said illumination optical system is adapted to change the refracting power of said optical means in accordance with the range of an area on the mask to be illuminated, while substantially maintaining the conjugate relationship between said secondary light source and the pupil.

An exposure system usable with a mask having a circuit pattern and a wafer, said exposure system comprising:

• supplying means for supplying light;
• secondary light source forming means disposed to receive the light from said supplying means, for forming a secondary light source by use of the received light;
• and
• an illumination optical system disposed to receive light from said secondary light source, for illuminating the mask by use of the received light so that the circuit pattern of the mask is transferred onto the wafer, said illumination optical system having an optical means which has a variable refracting power;
• wherein said illumination optical system has a focal length and a rear principal plane which is set at such distance from the mask that is substantially equal to said focal length of said illumination optical system and wherein said illumination optical system is adapted to change the refracting power of said optical means in accordance with the range of an area on the mask to be illuminated, while substantially maintaining a fixed relation between said distance and said focal length.

A projection exposure system usable with a mask having a circuit pattern and a wafer, said projection exposure system comprising:

• a light source for providing light;
• an optical arrangement effective to form a secondary light source of a predetermined size by use of the light from said light source and to illuminate the mask with light from said secondary light source, said optical arrangement having an optical means whose refracting power is variable;
• and
• a projection optical system operable to form an image of the circuit pattern of the mask upon the wafer, said projection optical system having a pupil which is in conjugate relationship with said secondary light source;
• wherein the refracting power of said optical means is changed in accordance with the range of an area on the mask to be illuminated, such that the range of illumination by the light from said secondary light source is changed while substantially maintaining the conjugate relationship between said pupil and said secondary light source.

A projection exposure apparatus, comprising:

• a light source;
• means for supporting a reticle;
• means for supporting a wafer,
• arrangement means for forming a secondary light source by use of light from said light source and for illuminating the reticle with light from said secondary light source, said arrangement means including an adjustment optical system having a variable refracting power;
• a projection optical system for projecting a pattern of the reticle upon the wafer, said projection optical system having a pupil disposed in a conjugate relationship with said secondary light source;
• and
• an actuator for actuating said adjustment optical system to change an area to be illuminated by said arrangement means, while substantially maintaining the conjugate relationship between said pupil and said secondary light source.