Core Viewpoint - SK Hynix is transforming its wafer cutting process to accommodate next-generation memory manufacturing, specifically the sixth-generation high bandwidth memory (HBM4) and NAND flash wafers with over 400 layers, as existing methods have reached their limits [2][3]. Group 1: Wafer Cutting Technology - SK Hynix plans to introduce femtosecond laser grooving and full cutting methods for HBM4 wafer cutting, moving away from traditional mechanical and stealth cutting techniques [2][3]. - The thickness of HBM4 wafers is expected to be around 20-30 micrometers, which poses challenges for existing cutting methods that are effective for thicker wafers [2][3]. - The adoption of femtosecond laser technology is anticipated to accelerate in the semiconductor industry, following similar moves by TSMC, Micron, and Samsung Electronics [3]. Group 2: Demand for Thin Wafers - The shift from planar SoC to 3D-IC and advanced packaging necessitates thinner wafers to enhance performance and reduce power consumption [4]. - The market demand for ultra-thin wafers is increasing, particularly for applications in fan-out wafer-level packaging and advanced 2.5D and 3D packaging, which are growing faster than mainstream integrated circuits [4]. - The rise of lightweight mobile devices, wearables, and medical electronics further drives the need for reliable thin silicon wafer processing capabilities [4]. Group 3: Challenges in Thin Wafer Processing - Engineers face challenges in preventing defects or micro-cracks during thin wafer processing, especially at the wafer edges [14]. - Selective plasma etching at the wafer edges helps remove edge defects, while selective chemical vapor deposition (CVD) can passivate edges [14]. - The management of back and edge defects is crucial for maintaining yield rates in thin wafer processing [14]. Group 4: Temporary Bonding and Debonding Techniques - The industry is increasingly focused on temporary bonding and debonding processes, with a growing demand for the recycling of carrier wafers, particularly silicon carrier wafers [22]. - Various debonding methods, including laser debonding and mechanical debonding, are being explored for their compatibility with thin wafer formats [17][21]. - The choice of adhesive and release materials is critical for achieving high yield and reliability in the production of ultra-thin devices [22]. Group 5: Process Optimization - The thinning of wafers requires a delicate balance between grinding, chemical mechanical polishing (CMP), and etching processes to meet strict total thickness variation (TTV) standards [11]. - Engineers are keen on quantifying variations during thinning and processing to ensure precision in TSV (through-silicon via) reveal processes [12]. - The use of glass carriers is becoming more common due to their thermal expansion coefficient (CTE) compatibility with silicon, which is essential for maintaining structural integrity during processing [9].