Masahiro Seyama

Reticle CD-SEM for 65-nm technology node and beyond

For next generation photomask lithography, improved resolution and precision are required to monitor lithography tools and photomask processes. The newly developed LWM9000 SEM Critical Dimension Scanning Electron Microscope (CD-SEM) for photomask applications will be presented. Its proprietary electron optics technology combined with an improved detection system leads to sub-nanometer CD measurement repeatability by almost completely eliminating the effect of charging and contamination. In an effort to minimize integration into production environments and to facilitate the ease of use the new CD-SEM utilizes a graphical user interface and data evaluation software based on Leica Microsystems’ LMS IPRO / LMS IPRO2. Presented in this paper is data showing leading edge CD measurement repeatability performance on chrome on glass substrates (COG), different types of phase shift masks (PSM), and resist plates. The virtual lack of charging in conjunction with a laser controlled stage, dramatically reduces the need for local feature alignment prior to CD measurement in most cases. The lack of need for local pattern alignment leads to increased throughput and high reliability during the measurement process. The standard system can be configured for manual loading or SMIF handling.

A new CDSEM metrology method for thin film hardmasks patterns using multiple detectors

Thin film hardmasks with 10nm or less are used in double patterning techniques to generate fine patterns for 32nm-node and beyond. Using a conventional Mask CDSEM for ultra accurate measurement of patterns on these thin film hardmasks is difficult due to weakness of the edge profiles generated by a scanning electron beam. Additionally, the tones of a SEM image can be reversed due to a charging phenomenon, which causes false recognition of lines and spaces. This paper addresses ultra accurate measurement of thin film hardmasks using a new measurement algorithm that is applied to profiles obtained from multiple detectors.

Addressing 3D metrology challenges by using a multiple detector CDSEM

In next generation lithography (NGL) for the 22nm node and beyond, the three dimensional (3D) shape measurements of side wall angle (SWA) and height of the photomask pattern will become critical for controlling the exposure characteristics and wafer printability. Until today, cross-section SEM (X-SEM) and Atomic Force Microscope (AFM) methods are used to make 3D measurements, however, these techniques require time consuming preparation and observation. This paper presents an innovative technology for 3D measurement using a multiple detector CDSEM and reports its accuracy and precision.