Temporary Bonding with Polydimethylglutarimide Based Lift Off Resist as a Layer Transfer Platform

Abstract

Bonding of lift off resist (LOR) was performed to realize temporary wafer bonding without residue. Bonding process conditions such as spin speed, pre-bake temperature, and bonding temperature were optimized to obtain a large bonded area with high bond strength. Under optimized process conditions, a bonded area covering over 98% of the wafer surface, with a room temperature bond strength of nearly 5 J/m 2 is achieved. During razor blade testing, fracture often occurs at the Si wafer. Moreover, debonding using an N-Methyl-2-pyrrolidone (NMP)-based solvent left the wafer surface extremely small amount of residue. Thus, the optimized bonding processed developed in this research is suitable for a clean temporary bonding process.

Temporary Bonding and Debonding in Advanced Packaging: Recent Progress and Applications

“…Micro Chem developed a lift-off resist (LOR) material (polydimethyl glutarimide) for wafer-to-wafer bonding and demonstrated that the LOR material could be resolved in NMP-based solvents [46]. Thermoset polymers have greater thermal and chemical stability compared to thermoplastic materials.…”

“…Special technologies such as ZoneBOND ® [40] and air-jetting were developed [41,42]. In addition, hydrogenated amorphous silicon (a:Si-H) [22,43] and various polymers, such as polyelec-trolyte [44], iCVD polyglycidylmethacrylate (PGMA) [45] and polydimethylglutarimide (PMGI) [46], have also been used as temporary bonding materials. Here, we review the corresponding temporary bonding materials, principles, applications and future trends according to different debonding methods.…”

Room Temperature Bonding with Polymethylglutarimide Using the Surface Activated Bonding Method for a Layer Transfer Platform

“…Recently, a wafer bonding method for polymethylglutarimide (PMGI) was proposed for layer transfer. 4 PMGI is a lift-off resist (LOR) material and is traditionally used as a sacrificial layer for the undercutting process during lift-off processing. [5][6][7] Moreover, our research group has demonstrated that the PMGI layer can be effectively bonded using thermal compression bonding.…”

“…Debonding using N-methyl-2-pyrrolidone (NMP) results in negligible amounts of the PMGI sacrificial layer residue on the debonded wafer surface and is therefore suitable for a transfer process. 4,9 However, thermal compression bonding materials require higher temperatures than the glass transition temperature (T g ) of the polymer material. In our previous bonding study, a bonding temperature of 250 • C was required for bonding most of the loaded area.…”

“…In our previous bonding study, a bonding temperature of 250 • C was required for bonding most of the loaded area. 4 Such high-temperature bonding may damage the transferred material because of mechanical stress derived from thermal expansion. Moreover, this high-temperature bonding limits its usage in other 2D materials, such as the integration of h-BN.…”