Substrate Temporary Bonding Supporting Post-Processing Applications

Abstract

Post-processing applications are carried out on substrates while they are temporarily supported. This requires a simple adhesion process with easy removal without complex tooling or cleaning. Substrates include wafers, displays, or components, organic or inorganic, and may contain topography such as solder bumps. The applications may vary from backside processing of wafers, complete flexible circuit integration, or the stacking of packages. Simple processing may use green products as the detergent soluble DaeCoatTM 600-series, exhibiting thermal stability from 80°C to allow hot DIW debond, to over 200°C to support thermal processing. Temporary bonding may resist heat and chemicals for many steps or one major extreme. The DaeCoatTM 300-series of products are designed to resist thermal exposures >300°C for wafer operations with bumps or reach ≥400°C (DaeCoatTM 315) for flexible displays to allow casting of liquid polyimide (PI) [1]. The properties are consistent with the needs of electronics processes, providing outgas below 1% inert to fab chemicals, and most important, an adhesive force that is tuned to allow simple substrate removal (peeling, lifting, or chemical diffusion). Where discrete die or components require installing infrastructure to support stacking or fan-out designs, the thin and fragile substrate is securely held in place by simple dry bonding completed in seconds and later removed by similar peeling practices without observed residue. Such component practices enable encapsulation during bumping, permanent bonding, or physical vapor deposition (PVD) of electromagnetic and radio-frequency interference (EMI/RFI) shielding [2]. The success in these and other technologies depend upon the use of the proper adhesive but most importantly, the tuning of the adhesion force. Successful tuning depends upon many factors, including substrate surface energy, texture, and the bonding process. Daetec has created adhesives used in temporary bonding processes for nearly 20yrs, applying to multiple wafer types, OLED and TFT displays, printed electronics, solar, thinning down to 4um, and thermal resistance >600°C [3]. Our experience in creating solutions for these and other industry needs will be discussed as well as the criteria to temporarily support flexible and rigid substrates of all types, sizes, and shapes.