In a 200 mm high volume environment, we studied data from a dual damascene process. Dual damascene is a combination of lithography, etch and CMP that is used to create copper lines and contacts in one single step. During these process steps, different metal CD are measured by different measurement methods. In this study, we analyze the key numbers of the different measurements after different process steps and develop simple models to predict the electrical behavior* . In addition, radial profiles have been analyzed of both inline measurement parameters and electrical parameters. A matching method was developed based on inline and electrical data. Finally, correlation analysis for radial signatures is presented that can be used to predict excursions in electrical signatures.
Multi-patterning processes have become common in the leading-edge semiconductor industry. These processes require a good patterning uniformity over the wafer while different process steps have impact. The initial lithography steps can be nearly perfect, but the CD variation after a trim process may cause CD variation after the spacer deposition. In fact, that leads to final non-uniformity of the final CD. Monitoring and controlling the individual CD parameters is not sufficient to ensure a stable process. We define a set of new KPIs, taking all contributions into account and using macro measurement data. We show that a reliable monitoring is achieved to meet the process specifications.
Proc. SPIE. 10145, Metrology, Inspection, and Process Control for Microlithography XXXI
KEYWORDS: Metrology, Statistical analysis, Data modeling, Metals, Reliability, Distortion, Process control, Optical alignment, Virtual reality, Semiconducting wafers, Environmental sensing, Overlay metrology, Model-based design, Back end of line, Front end of line
Overlay measurements are done for verification of the exposure and creation of process corrections for the next lots. As throughput of the overlay measurement tools is limited, it is desirable to avoid unnecessary measurements. Another concern can be that in-transparent stacks do not allow measuring a critical overlay relation directly. We developed methods for calculation of the overlay relation between two different layers between which there is no direct overlay measurement. We qualify the impact of sampling plans and the number of dependent layers. The indirect overlay calculation is applied on a significant high volume data set.
An active spindle system with an Electro-Magnetic Actuator (EMA) is developed for micromachining. The process of developing controllers for this mechatronic system requires reasonable models that expose the important dynamic effects without being excessively complicated. This paper develops a MIMO model with four inputs and two outputs based on the bond graph method. This model considers the bidirectional bearing compliance as well as the external load effect. System state space equations are produced automatically from the bond graph model. Simulations in several conditions are done in both time and frequency domain. Results from simulation and experiments are compared.