Ag and SiO2-film Removal-rate Enhancement Using Periodic Acid Oxidant

Abstract

Recently, the display market has witnessed a rising demand for Virtual Reality (VR) and Augmented Reality (AR) devices, with the latest VR/AR technologies necessitating resolutions exceeding 3000 Pixels Per Inch (PPI). Traditionally, glass substrates have been employed in manufacturing processes, but the challenges associated with fine patterning have led to a growing trend favoring the adoption of wafer substrates. In the realm of Organic Light-Emitting Diode displays on silicon (OLEDos), achieving high resolutions becomes challenging as the pixel spacing narrows. The application of the conventional Wet-Etching process results in yield degradation issues, prompting the adoption of Chemical Mechanical Polishing (CMP) processes to address challenges related to mass production and yield. Particularly in OLEDos, Ag reflectors are utilized on the Bottom Emission Layer (BL) to enhance luminous efficiency. The implementation of the Ag Damascene process becomes imperative in realizing this enhancement. The Ag-film serving as the reflective surface must maintain its reflectivity post-CMP, necessitating the development of high abrasion- resistant Ag-film CMP slurries. Given the imperative nature of this aspect in achieving optimal performance, this paper focuses on the design of CMP slurries with high abrasion resistance and low surface roughness applicable to Ag Damascene processes. The slurry composition includes Silica, H5IO6, Glycine, BTA (benzotriazole), and Titrant. Considering that Ag is a Noble Metal, conventional oxidants like H2O2 pose challenges in generating surface oxide layers. Therefore, this paper introduces the addition of a highly reactive Halide Oxidant (H5IO6) to enhance the formation of surface oxide layers on the Ag-film. This augmentation aims to increase the generation of Hydroxyl radicals, known for their high reactivity. Furthermore, the inclusion of both cationic and anionic Glycine is employed to minimize the Relative electrostatic force between the Ag-film and slurry particles, thereby enhancing the Removal rate. To achieve not only high abrasion resistance but also low surface roughness, a corrosion inhibitor, BTA, is incorporated into the slurry. This comprehensive approach is designed to improve the overall performance of the CMP process for Ag Damascene applications.