A method and apparatus measures an image plane of a test pattern projected onto a surface of a sample disposed on a stage to precisely detect the image plane to thereby obtain a precise alignment therebetween for subsequent exposure. The test pattern is provided on a member having a conjugate surface with an upper surface of an illumination detecting unit having at least three optical sensors at different positions thereof and disposed on the stage. The upper surface of the illumination detecting unit has an analogous pattern to the test pattern on each optical sensor and, by moving the stage three dimensionally, outputs of the optical sensors are processed to obtain amounts of light and peak values thereof from which the image plane is obtained.
One example of a lithographic projection apparatus includes an image sensing device configured and arranged to measure a pattern in a patterned projection beam. The image sensing device includes a slab and a radiation-sensitive sensor that is sensitive to the radiation of the projection beam. The image sensing device also includes a film of a material that is non-transparent to the radiation of the projection beam. This film is provided over the sensor and includes one or more patterned segments to selectively pass radiation of the projection beam to the sensor. The apparatus also includes an intermediate plate made from a material having a thermal expansion coefficient below approximately 12.times.10.sup.-6 K.sup.-1 and having a slab-bearing surface.
A checkered characteristic pattern is picked up by an image input device to form pick-up data. Characterizing points (intersecting points) are detected from the pick-up data. From the arrangement of the characterizing points about the center of the pattern and the positions of the characterizing points on the picture plane, a mapping function obtained when a TV camera is assumed to be a pin-hole camera is prepared. Reference positions of the characterizing points through the entire picture plane are calculated from the mapping function. The reference positions are compared with the actual positions on the picture plane to calculate a correcting function which in turn is stored in a correcting function preparing device. Normally, the inputted image is corrected by the correcting function and then outputted to an image output device.
A method of calibrating a positioning stage includes placing a substrate on the positioning stage. The substrate has a contrast film above a portion of the substrate. At least one pattern is at a predetermined location above the substrate, corresponding to a predetermined location on the positioning stage if the positioning stage has zero offset from a registration position. A beam is applied to a position where the pattern on the substrate would be located if the positioning stage has zero offset. At least one of the group consisting of reflected, transmitted and scattered portions of the beam is measured. Whether the positioning stage has a non-zero offset is detected based on the measured portion of the beam.
A lithographic apparatus according to one embodiment of the invention includes an image sensing device configured and arranged to measure a pattern in a patterned beam of radiation. The image sensing device comprises a slab on which at least two sensors are formed. The sensors are sensitive to radiation of the beam and are arranged on a first side of the slab. A film that is non-transparent to radiation of the beam is provided at the first side over the sensors. The film includes a patterned segment above each sensor.
In a projection exposure apparatus for projecting an image of a pattern on a reticle through a projection optical system onto a wafer, in order to quickly measure imaging characteristics of the projection optical system without actual exposure, an enlarging optical system consisting of an objective lens and a relay optical system, and an image pickup element are provided on a Z-stage on which the wafer is mounted. Illumination light illuminates an index pattern formed on the reticle to form an image thereof near a first lens in the objective lens through the projection optical system, the enlarging optical system enlarges the thus formed image of the index pattern to form an enlarged image thereof on a receiving surface of the image pickup element, the image pickup element converts it into a signal, and an image processing system processes the signal from the image pickup element, thereby measuring the imaging characteristics of the projection optical system, based on the processing results.
