Utilization of Insitu Metrology Capability of ASML Lithography Scanner to Improve Overall Process Control

As the device integration and relating lithography process progressively increasing in complexity for each new technology node, there is a growing need for a more integrated approach to process control. There are several insitu metrology sensors in ASML scanners that can be used to improve not only the scanner equipment and lithography process stability but also to compensate for other process modules´ fingerprint to achieve an overall tighter process control and improved device performance. In this paper, we will describe the functionality of some of the scanner´s insitu metrology sensors, such as the ILIAS for lens performance, and the methods of it usage to not only control the scanner´s lens stability but also to improve the lithographic process performance such as the overall device critical dimension uniformity (CDU). Furthermore, we will introduce an integrated methodology of using scanner exposure dose, known as Dosemappertrade to compensate for other process module´s systematic fingerprint to achieve an improved device electrical performance. This was demonstrated in an improvement in the intra-wafer ring oscillator´s stage delay using the dose compensation [1]. Finally, we will show the potential of using another insitu detector, the spot sensor, to feed forward the reticle´s CD fingerprint (known as Spot sensor Enabled Reticle Uniformity Measurement or SERUM) to the scanner and take the advantage of using the Dosemapper´s functionality to improve the intrafield CDU.