Characterization of integrated optical CD for process control

Yu, Jackie; Uchida, Junichi; Dommelen, Youri van; Carpaij, Rene; Cheng, Stone; Pollentier, Ivan; Viswanathan, Anita; Lane, Lawrence; Barry, Kelly A.; Jakatdar, Nickhil H.

doi:10.1117/12.535949

Cited by 1 publication

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“…A library for this structure was generated by TEL-Timbre, based on the measured optical constants of the different layers, and using a trapezoid profile approximation, as shown in Figure 3. Before using the library for monitoring, the model has been tested extensively using FEM wafers [5]. By comparing the CD and profile with CD-SEM and cross-section SEM a good correlation was found.…”

Section: Qualification Of Integrated Metrologymentioning

confidence: 92%

In-line lithography cluster monitoring and control using integrated scatterometry

et al. 2004

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In the continuous drive for smaller feature sizes, process monitoring becomes increasingly important to compensate for the smaller lithography process window and to assure that Critical Dimensions (CD) remain within the required specifications. Moreover, the higher level of automation in manufacturing enables almost real-time correction of lithography cluster machine parameters, resulting in a more efficient and controlled use of the tools. Therefore, fast and precise in-line lithography metrology using Advanced Process Control (APC) rules are becoming crucial, in order to guarantee that critical dimensions stay correctly targeted. In this paper, the feasibility of improving the CD control of a 193nm lithography cluster has been investigated by using integrated scatterometry. The target of the work was to identify if a dose correction on field and wafer level, based on precise in-line measurements, could improve the overall CD control. Firstly, the integrated metrology has been evaluated extensively towards precision and sensitivity in order to prove its benefits for this kind of control. Having a long-term repeatability of significantly better than 0.75nm 3σ, this was very promising towards the requirements for subnanometer CD correction. Moreover, based on an extensive evaluation of the process window on the lithography cluster, it has been shown that the focus variation is minimal and that CD control can be improved using dose correction only. In addition, systematic variations in across-wafer uniformity and across-lot uniformity have been determined during this monitoring period, in order to identify correctable fingerprints. Finally, the dose correction model has been applied to compensate for these systematic CD variations and improved CD control was demonstrated. Using a simple dose correction rule, a forty percent improvement in CD control was obtained.

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Section: Qualification Of Integrated Metrologymentioning

confidence: 92%