BACKGROUND

The present invention generally relates to semiconductor integrated circuits, and more particularly, to methods for determining line edge and line width roughness with optical metrology in semiconductor pattern structures formed using an extreme ultraviolet (EUV) light sensitive structure.

It has been shown that the line width roughness (LWR) and line edge roughness (LER) of the features of a device have an impact on the device performance. Variations of edges and widths on semiconductor patterns from lithographic processes are commonly due to mask process variations, shot noise effects, stochastics associated with photoresists, and the like. As the critical dimensions (CD) of devices continue to shrink for enablement of 7 nanometers technology node and below, control and monitoring of LWR and LER become increasingly more critical.

SUMMARY

According to non-limiting embodiments of the present invention a computer-implemented method for determining optical roughness in a semiconductor pattern structure is provided. The method includes receiving, using a processor, optical responses spectra collected from the semiconductor pattern structure by an optical metrology tool and constructing, using the processor, optical critical dimension (OCD) models by using a set of input parameters for each layer of the semiconductor pattern structure. The method further includes calculating, using the processor, theoretical optical responses from a theoretical input generated by the OCD models. In addition, the method provides for comparing, using the processor, the optical responses spectra of the semiconductor pattern structure to the theoretical optical responses to determine output parameters for the optical roughness of the semiconductor pattern structure.

Embodiments of the present invention are further directed to a computer-implemented method for determining a line edge roughness (LER) and a line width roughness (LWR) in a semiconductor pattern structure. The method includes receiving, using a processor, optical responses spectra collected from the semiconductor pattern structure by an optical metrology tool and constructing, using the processor, optical critical dimension (OCD) models with a virtual material (VM), wherein the VM represents LER and/or LWR. The method also includes calculating, using the processor, theoretical optical responses from a theoretical input generated by the OCD models with the VM. In addition, the method provides for comparing, using the processor, of the optical responses spectra of the semiconductor pattern structure to the theoretical optical responses to determine output parameters for the LER and LWR of the semiconductor pattern structure.

Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with advantages and features, refer to the description and to the drawings.

