Method of repetitively imaging a mask pattern on a substrate, and apparatus for performing the method
AssigneeU.S. Philips Corporation
InventorsManfred G. Tenner, Jan E. van der Werf, Cornelis M. J. van Uijen, Peter Dirksen
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Abstract
A method and apparatus for repetitively imaging a mask pattern (C) on a substrate (W) are described. Various parameters of the apparatus and the projection lens system (PL) can be measured accurately and reliably and measuring devices of the apparatus can be calibrated by measuring a latent image of a mark by means of a scanning microscope (LID) forming a diffraction-limited radiation spot (Sp) on the photoresist layer on the substrate (W), in which layer the latent image is formed by means of a projection beam (PB).
Claims14
A method of repetitively imaging a mask pattern, provided in a mask table, on a substrate provided in a substrate table, by means of a projection beam, which method comprises the following steps:
- providing a mask having at least one test mark in the mask table;
- providing a substrate having a photoresist layer in the substrate table;
- projecting the image of at least one test mark of the mask in the photoresist layer by means of the projection beam and the projection lens system;
- aligning the mask with respect to the substrate by means of an alignment device;
- detecting the latent image of at least one test mark by means of a latent-image detection device in which non-actinic radiation is used;
- setting at least one parameter influencing the quality and position of the mask pattern image by means of the output signal of the latent-image detection device, and
- repetitively imaging a production mask pattern at consecutive, different positions on a production substrate,
- characterized in that a diffraction-limited scanning spot is used for the latent-image detection and in that said spot and the latent image are moved with respect to each other for point-by-point scanning of the latent image.
An apparatus for repetitively projecting a mask pattern on a substrate, which apparatus successively comprises an illumination system for supplying a projection beam, a mask table, a projection lens system and a substrate table and which is further provided with an alignment device for aligning the mask with respect to the substrate and a latent-image detection device, characterized in that the latent-image detection device is constituted by a scanning optical microscope comprising a radiation source supplying a non-actinic test beam, an objective system for focusing the test beam to a diffraction limited scanning spot in a photoresist layer present on the substrate, scanning spot position detection means for detecting the position of the scanning spot in the plane of the photoresist layer, and a radiation-sensitive detection system having at least one detector whose surface area is of the order of the image of the scanning spot formed in the detector plane, said detection system being intended for converting the test beam radiation from the photoresist layer into an electric signal which represents the local refractive index of the photoresist layer at the location of the scanning spot.
Dependencies are inferred from the claim text.