The detection of empty resist bottles or air in the resist lines of a photolithography coating tool

Photolithography is when light is used to put an image from a photo mask onto a wafer that has photo resist on it thus creating integrated circuits or other technology such as read/write heads for hard drives. Reservoir Switching Units can fail to detect resist on the Photolithography tool or the Millipore pump thus introducing air into the resist lines and ultimately causing scrap due to poor dispenses on under layer processes. This is difficult to detect via operator inspection. It is important to improve the dispense system on a Photolithography coating tool because with the increasing cost of photoresist there is a need for less waste. There are more read/write heads on a wafer and larger wafers therefore if the Photolithography coating tool has a poor dispense which is not detected and a wafer is scrapped, this will increase manufacturing costs. By reducing the amount of scrap and rework, there will be a reduction in the time to produce a single wafer thus reducing the overall production costs of making a single read/write head therefore staying more competitive in the hard drive market. This paper outlines a method for detecting empty resist bottles or air in the resist lines using Programmable Logic Controller technology in conjunction with a relay dispense system to monitor the dispense system from a remote station, Terrence Sweeney, Kevin Curran (2014) The Detection of Empty Resist Bottles or Air in the Resist Lines of a Photolithography Coating Tool, Vol 27, No. 11, pp: , International Journal of Computer Integrated Manufacturing, ISSN: 0951-192X thereby improving the process and reducing cost of manufacturing read/write heads. Overall, there are less dispense errors, thus less rework and scrap, yield on the wafer had improved and therefore has reduced the cost of manufacturing a read/write head and also the time to market has improved. Due to the success of the PLC control system the system will be implanted across other coating tools in the factory.