UV-Mask- and Bond-Aligner

• Subject Area: Systems Engineering
• Term: Funded in 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 519023672

An UV mask aligners is a basic tool for microsystems technology research. Currently, the Chair for Microsystems Technology owns a 30-year-old 3" mask aligner, only. A mask aligner for up to 150 mm wafers is available at the Center for Interface-Dominated High Performance Materials (ZGH, RUB core facility). Research projects in the fields of MEMS and 2D electronics research, especially in cooperation with scientific and industrial partners require a step-up to 200 mm substrates, e.g. in cooperation with FhG IMS Duisburg (Forschungsfabrik Mikroelektronik Deutschland, FMD) for 2D electronics. With respect to this, the cleanroom was upgraded for 200 mm, the mask aligner is the only missing link for a continuous 100 mm and 200 mm MEMS line. In 2021, a three-chamber PVD cluster tool (DFG) and a five-chamber ALD/RIE cluster were installed, both suitable for up to 200 mm. The ISO 6 lithography cleanroom is equipped with work benches and includes a 200 mm spincoating cluster for resists. Micro-nano-integration requires moreover nanoimprint-lithography using soft flexible templates for optical, electronic and sensing applications, also for flexible and thin glass substrates. For MEMS as well as for the temporal stabilization of flexible substrates, bonding of two wafers or substrates is important, that can be performed with the alignment system of the mask aligner. The requirements for the mask and bond aligner include backside alignment with better than 1 micrometer on front and 2 micrometers on backside and an LED-based UV source resulting in an optical resolution better than 1 micrometer for lines and spaces with hard- or vacuum contact. It allows a Hg-free use without preheating time and nitrogen purge for the source but a similar emission spectrum for commercial resists including dry resists and high-resolution thin film resists. The use of wafers from 30 μm up to 5 mm thickness and a proximity function are mandatory. Masks and wafers are loaded manually, the alignment should be support by vision control. Mask and wafer chucks are required for 100 mm and 200 mm substrates, as both sizes are used depending on the research project. The precise alignment function is used for both mask and bond alignment. Bonding will be supported by polymers for a temporal stabilization of substrates or for a permanent lamination. It is used for a stabilized handling of thin glass substrates but also for MEMS packaging on waferlevel.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: UV-Lithografie- und Bond-Aligner
• Instrumentation Group: 0910 Geräte für Ionenimplantation und Halbleiterdotierung
• Applicant Institution: Ruhr-Universität Bochum
• Leader: Professor Dr.-Ing. Martin Hoffmann