Inclination detecting apparatus and method

A projection type exposure apparatus comprising:

• a projection optical system for projecting a pattern formed on a mask, onto a photosensitive substrate;
• a support system for supporting the substrate, said support system being arranged to adjust a position of the substrate in a direction parallel to a first optical axis of said projection optical system, a position of the substrate in two directions normal to said first optical axis and perpendicular to each other, and an inclination of the substrate relative to a plane which said first optical axis crosses;
• an inclination detecting system for detecting an inclination of a front surface of the substrate supported by said support system;
• and
• a control system for controlling said support system such that the front surface of the substrate supported by said support system becomes substantially parallel to a focus plane of said projection optical system, based on a result of detection by said inclination detecting system;
• wherein said inclination detecting system includes:
• an illumination optical system having a second optical axis obliquely arranged to said first optical axis, said illumination optical system supplying a collimated beam onto the front surface of the substrate in a direction oblique to said first optical axis;
• a condenser optical system having a third optical axis arranged symmetric with said second optical axis of said illumination optical system with respect to said first optical axis, said condenser optical system having a condensing member for condensing the collimated beam supplied from said illumination optical system and then reflected by the front surface of the substrate, and
• a light receiving member for receiving the beam condensed by said condensing member and generating a position signal corresponding to a light receiving position;
• a system for detecting an inclination of the front surface of the substrate, based on the position signal generated from said light receiving member;
• a first light limiting member having a light-transmitting portion and a light shield portion, said first light limiting member being set on the second optical axis of said illumination optical system such that a conjugate image thereof is formed on the front surface of the substrate placed substantially perpendicular to said first optical axis;
• and
• a second light limiting member having a light-transmitting portion and a light shield portion, said second light limiting member being set on the third optical axis of said condenser optical system such that a conjugate image thereof is formed on the front surface of the substrate placed substantially perpendicular to said first optical axis and that the conjugate image of said second light limiting member is substantially coincident with the conjugate image of said first light limiting member.

An inclination detecting method for detecting an inclination of a front surface of a transparent object comprising the steps of:

• providing an inclination detecting apparatus for detecting an inclination of a transparent object relative to a plane which a predetermined reference axis crosses, said inclination detecting apparatus comprising a first light limiting means having a light-transmitting portion and a light shield portion, said first light limiting means having a conjugate image formed on said front surface of said object;
• and a second light limiting means having a light-transmitting portion and a light shield portion, said second light limiting means having a conjugate image formed on said front surface of said object, said conjugate image of said second light limiting means being substantially coincident with said first light limiting means, wherein said light-transmitting portion and light shield portion of said first light limiting means and said light-transmitting portion and light shield portion of said second light limiting means are arranged such that said light shield portion of said second light limiting means can cut off light reflected by a back surface of said object arranged substantially perpendicular to said reference axis;
• providing an optical position detecting apparatus for detecting a position of said front surface of said object in a direction parallel to said reference axis;
• detecting a position of said front surface of said object in said direction, using said position detecting apparatus;
• moving said front surface of said object to a reference position in a first direction for measuring an inclination of said front surface of said object of said inclination detecting apparatus, based on a result of detection by said position detecting apparatus;
• and
• detecting an inclination of said front surface of said object, using said inclination detecting apparatus, in the state in which said front surface of said object is set at said reference position.

An apparatus for detecting an inclination of a substrate relative to a reference surface comprising:

• an illumination system for obliquely illuminating a collimated beam of light onto said substrate and projecting a pattern having dark portions and bright portions onto said substrate.
• a condenser system for condensing the collimated beam reflected by said substrate and forming an image of said pattern on a predetermined plane,
• a light limiting member disposed on said predetermined plane for substantially shielding dark portions of said pattern image, and
• a photodetector for receiving light from bright portions of said pattern image, and
• a photodetector for receiving light from bright portions of said pattern image.