Novel design of an inspection tool for an extreme ultraviolet radiation source to observe tin residual

A method of inspecting an extreme ultraviolet (EUV) radiation source of a semiconductor manufacturing system, wherein the EUV radiation source comprises a droplet generator configured to introduce tin droplets into a chamber of the EUV radiation source, and an excitation laser configured to generate a light beam that is configured to focus onto the tin droplets to generate EUV radiation, and wherein the droplet generator is detached from the chamber of the EUV radiation source to produce a first opening in a wall of the chamber of the EUV radiation source, wherein the EUV radiation source comprises a blocking shield configured to block the light beam of the excitation laser and be transparent to the EUV radiation, the method comprising,

• in an idle mode of the EUV radiation source:
• inserting a camera mounted on a fixture through the first opening into the EUV radiation source, wherein the camera is attached to a first end of a connection cable, wherein the fixture comprises an extendible section mounted to a first side of the extendible section on a lead screw, and wherein the camera is mounted to a second side of the extendible section;
• rotating the lead screw to extend the extendible section and to move the camera inside a chamber of the EUV radiation source beyond the blocking shield;
• acquiring one or more images by the camera from an intermediate focus (IF) cap region of the chamber of the EUV radiation source between a second opening of the EUV radiation source and the blocking shield, wherein the EUV radiation generated inside the EUV radiation source exits the chamber of the EUV radiation source through the second opening;
• and
• analyzing the one or more acquired images to determine an amount of tin debris deposited in the IF cap region.

A semiconductor manufacturing system, comprising:

• a main controller;
• an analyzer module coupled to the main controller;
• and
• an extreme ultraviolet (EUV) radiation source comprising:
• a chamber having:
• a first opening configured for connecting a droplet generator configured to introduce target droplets into the chamber;
• a second opening of the chamber configured for connecting a droplet catcher;
• an excitation laser configured to generate a light beam that is onto the target droplets to generate EUV radiation;
• a collecting mirror configured to direct the EUV radiation toward a third opening;
• a blocking shield between the third opening and the collecting mirror and configured to block the light beam from exiting the chamber through the third opening;
• and
• an observation system comprising:
• a flat elongated surface;
• an extendible section mounted from a first side of the extendible section on the flat elongated surface;
• a camera assembly mounted on a first end of a fiber optics cable, wherein the camera assembly is mounted on a second side, opposite to the first side, of the extendible section;
• and
• an image processing system coupled to the camera assembly via the fiber optics cable, wherein:
• the main controller is configured to move the camera assembly inside the chamber to an intermediate focus (IF) cap region comprising the second opening of the EUV radiation source and a region of the chamber of the EUV radiation source between the second opening of the EUV radiation source and the blocking shield, and
• the main controller is configured to command the image processing system to acquire one or more images from the IF cap region.