TANAKA to Apply Ruthenium Film Deposition for Semiconductor Front-End Processes

Logic and DRAM are seen as promising

Cutting-edge semiconductors require low-resistance wiring and support for three-dimensional structures, and the use of ruthenium is attracting attention in addition to the conventional materials of aluminum, copper, and cobalt. The company is promoting material development and the establishment of mass production technology, and is promoting sample work for multiple types. The company is working on both the development of core materials and customization according to application.
"For logic applications, evaluation is underway for the contact wiring that connects transistors and multi-layer wiring. Currently, application to the liner layer is seen as the most likely application, but it is also attracting attention as a capping material to be deposited on top of copper wiring. We hope to first use ruthenium in the liner layer, and then as a capping material. We will promote the development of materials that meet required specifications, such as the selectivity to deposit only on copper wiring without reacting with the low-k material that serves as the insulating layer.
Research is underway on capacitor electrodes for DRAM. It has been reported that replacing titanium nitride with ruthenium improves dielectric properties, and there is a growing momentum for the introduction of ruthenium. As the electrode layer will be a thin film, the use of ALD is also anticipated. Furthermore, as finer lines are becoming increasingly common, such as with the introduction of EUV (extreme ultraviolet), the introduction of ruthenium into the wiring layer of DRAM is also being considered. The introduction of ruthenium into mass production lines is expected to begin with logic.
Logic applications have different requirements, such as low resistance, while DRAM applications have different requirements, such as application to three-dimensional shapes and high aspect ratios, and the company is working to understand these needs through collaboration with universities and sample work. The company will also continue joint development with Yeungnam University in South Korea, and aims to "prepare for mass production supply at any time" for both logic and DRAM. Ruthenium is used at a rate of 20-400kJ per year, and in addition to its main use as a soda electrolysis electrode, its range of uses is expanding to include fuel cell catalysts, magnetic layer underlayers and magnetic layer alloys for hard disk drives (HDDs). Rhodium is a by-product element mined together with platinum and palladium, and stable supply is also an issue.
Recycling technology will also be emphasized. By applying the recycling technology for recovering and refining precious metals that has been cultivated for existing applications, the company will be able to achieve green supply and the equalization of procurement prices. While it will first consider recycling during film formation, it is also considering collaboration in related processes such as the embedding process. It will differentiate itself from competitors not only in materials but also in lifecycle management and sustainable use, and will work to commercialize new applications for precious metals.
(Daiki Sato)