COOLING HOOD FOR RETICLE

摘要

The present disclosure describes various aspects of systems, apparatuses, and methods for removing heat from a reticle during the operation of a lithographic apparatus to increase the accuracy with which a projected pattern overlies patterns already present on a substrate. In some aspects, the present disclosure describes a lithographic apparatus. The lithographic apparatus can include an optical system configured to direct a radiation beam onto a reticle supported by a reticle table to form a patterned radiation beam. The radiation beam can cause heating of an exposed area of the reticle. The lithographic apparatus can further include a reticle cooling apparatus configured to remove heat from the reticle. The reticle cooling apparatus can include a cooling element disposed below the reticle and adjacent to the exposed area, The cooling element can include a body that includes a chamber connected to a channel configured to deliver gas to the chamber. A roof of the chamber can be disposed adjacent to the reticle and can include openings configured to output the gas towards the reticle. The reticle cooling apparatus can further include actuators configured to modify a distance between the roof and the reticle. The reticle cooling apparatus can further include a cooling controller configured to generate a cooling control signal based on timing data for a projection of the patterned radiation beam, absorption data for the exposed area on the reticle, and a target heat transfer rate. The cooling control signal can be configured to instruct the reticle cooling apparatus to actuate the actuators to modify the distance between the roof and the reticle. The cooling controller can be further configured to transmit the cooling control signal to the actuators. In some aspects, the present disclosure describes a reticle cooling apparatus. The reticle cooling apparatus can include a cooling element configured to be disposed below a reticle supported by the reticle table and adjacent to an exposed area of the reticle. The cooling element can include a body containing a chamber connected to a channel configured to deliver gas to the chamber. A roof of the chamber can be configured to be disposed adjacent to the reticle and can include openings configured to output the gas towards the reticle. The reticle cooling apparatus can further include actuators configured to modify a distance between the roof and the reticle. The reticle cooling apparatus can further include a cooling controller configured to generate a cooling control signal based on timing data for a projection of a patterned radiation beam generated by the reticle, absorption data for the exposed area on the reticle, and a target heat transfer rate. The cooling control signal can be configured to instruct the reticle cooling apparatus to actuate the actuators to modify the distance between the roof and the reticle. The cooling controller can be further configured to transmit the cooling control signal to the actuators. In some aspects, the present disclosure describes a method for removing heat from a reticle. The method can include generating, by a cooling controller, a cooling control signal based on timing data for a projection of a patterned radiation beam formed by illuminating an exposed area on a reticle supported by a reticle table, absorption data for the exposed area, and a target heat transfer rate. The cooling control signal can instruct a reticle cooling apparatus to actuate actuators to modify a distance between the reticle and a roof of a chamber connected to a channel for delivering gas to the chamber. The channel can be disposed in a body of a cooling element of the reticle cooling apparatus. The method can further include transmitting, by the cooling controller, the cooling control signal to the actuators. The method can further include modifying, by the actuators based on the cooling control signal, the distance between the reticle and the roof to modify a heat transfer rate associated with a removal of heat from the reticle towards the target heat transfer rate. Further features, as well as the structure and operation of various aspects, are described in detail below with reference to the accompanying drawings. It is noted that the disclosure is not limited to the specific aspects described herein. Such aspects are presented herein for illustrative purposes only. Additional aspects will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein.