BACKGROUND

Field of the Disclosure

The present disclosure relates to a lithography apparatus, a determination method, and a method of manufacturing an article.

Description of the Related Art

In the manufacturing of a semiconductor device, a MEMS, a flat panel display, or other such article, an exposure apparatus being an example of a lithography apparatus transfers a pattern drawn on an original (reticle or mask) onto a substrate (wafer or panel). As the pattern to be formed on the substrate is becoming finer, it is required to align the pattern to be transferred onto the substrate with higher accuracy.

The causes of a decrease in alignment accuracy include a foreign substance sandwiched between the original and an original stage on which the original is held. When the original is held on the original stage with a foreign substance being sandwiched between the original and the original stage, the pattern to be transferred onto the substrate may be misaligned. In view of this, the exposure apparatus is required to include means capable of detecting that the original has been held on the original stage under an abnormal state due to the sandwiched foreign substance or other such cause.

In Japanese Patent Application Laid-Open No. 2004-186313, there is disclosed an exposure apparatus configured to determine the presence or absence of a foreign substance by measuring the height of an original through use of a measuring unit. In Japanese Patent Application Laid-Open No. 2004-186313, the height of the original is obtained from a change in contrast exhibited when the measurement is repeatedly performed while changing the focal length of the measuring unit.

In Japanese Patent Application Laid-Open No. 2004-186313, the height of the original is measured by repeatedly performing focus measurement while changing the focal length of the measuring unit, and hence there is a problem in that much time is required to determine the presence or absence of a foreign substance.

SUMMARY

Therefore, the present invention has an object to provide a lithography apparatus, a determination method, and a method of manufacturing an article, which are capable of detecting an abnormal holding of an original in a shorter period of time.

In order to solve the above-mentioned problem, according to at least one embodiment of the present invention, there is provided a lithography apparatus configured to form a pattern on a substrate through use of an original, the lithography apparatus including: a holding unit configured to hold the original on which a first mark is formed; a measuring unit configured to pick up an image of the first mark; and a control unit configured to: cause the measuring unit to obtain the image of the first mark on the original held by the holding unit with a focus position of the measuring unit being adjusted to a reference position; and determine that the original is being abnormally held by the holding unit when a change in a first contrast, which is a contrast of the image of the first mark with respect to a reference contrast, falls out of an allowable range.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

