Takashi Matsumae

Direct bonding of PEN at room temperature by means of surface activated bonding method using nano-adhesion layer

We realized the room temperature direct bonding method for polyethylene 2, 6 naphthalene dicarboxylate (polyethylene naphthalate, PEN) film by means of surface activated bonding method using nano-adhesion layer.

Direct bonding of polymer to glass wafers using surface activated bonding (SAB) method at room temperature

The room temperature bonding of PEN film to PEN film, PET film to PET film and PEN film to non-alkali glass was performed by the modified SAB method. No void is observed at the bonding interface with the optimized condition.

Room-temperature bonding method for polymer substrate of flexible electronics by surface activation using nano-adhesion layers

A sealing method for polymer substrates to be used in flexible electronics is studied. For this application, a low-temperature sealing method that achieves flexible bonding of inorganic bonding material is required, but no conventional technique satisfies these requirements simultaneously. In this study, a new polymer bonding method using thin Si and Fe layers and the surface activated bonding (SAB) method are applied to bond poly(ethylene naphthalate) (PEN) films to each other. PEN films can be bonded via the proposed method without voids at room temperature, and the bonded samples are bendable. The adhesion strength of the bonded samples is so strong that fracture occurs in the polymer bulk rather than at the bond interface. Investigations of the bonded samples by transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR) reveal that bonding is achieved by chemical interactions between the polymer surface and deposited atoms.

Novel sealing technology for organic EL display and lighting by means of modified surface activated bonding method

For a sealing of organic electro luminescence displays and lightings, a room temperature bonding of polymer films without organic adhesives is required. This paper describes a new bonding technique called modified surface activated bonding (mSAB) method using nano-adhesion layer that meets the requirement. Polymer films such as PEN, PET and PI can be bonded by this method. Especially PEN and PET films are so strongly bonded that the bond interface has tolerance for bending and loci of fracture after a peeling test are located in the polymer bulk. The organic electro luminescence lighting bonded by the proposed method clears environmental tests such as high temperature and high humidity tests.

2D material transfer using room temperature bonding

This study investigates the use of room temperature bonding for layer transfer process to reduce contaminants on a transferred material. It was found that resist residues on transferred graphene were significantly reduced using surface activated bonding at room temperature in comparison of thermal compression bonding at 250 °C. Surface activated bonding can provide a platform for layer transfer process suitable for 2D materials integration.

Graphene transfer by surface activated bonding with poly(methyl glutarimide)

In this study, we investigated the use of surface activated bonding at room temperature for layer transfer to improve the quality of the transferred material. Surface organic contaminants and the crystal quality of graphene transferred by surface activated bonding were compared with those in the case of thermal compression bonding at 250 °C. The physical and chemical surface characteristics of the transferred graphene indicate that the amount of organic contaminants derived from the poly(methyl glutarimide) sacrificial layer was significantly decreased by surface activated bonding at room temperature in comparison with the case of by thermal compression bonding at 250 °C. Furthermore, Raman spectra revealed a lower level of disorder in the graphene transferred by the surface activated bonding. Thus, surface activated bonding can provide a platform for a layer transfer process suitable for the integration of two-dimensional materials.

Room temperature bonding of Polymethylglutarimide for layer transfer method

Room temperature bonding of Polymethylglutarimide was performed for a damage-free layer transfer method. The PMGI layer was bonded to support Si wafer by using the Surface activated bonding method using nano-adhesion layers. Using SAB, bonded area covering around 90% of the wafer surface, with a room temperature bond strength of ~1 J/m2 is achieved. Micro voids at bond interface are never observed using scanning electron microscope. For debonding process, PMGI dissolve in N-methylpyrrolidone based solvent. Extremely small amount PMGI residues are detected by using atomic force microscope surface profile.

Bonding of polymer and glass using nano-adhesion layer for flexible electronics

This study addresses a sealing method for flexible polymer substrate. A modified method of the surface activated bonding (SAB) is applied to bonding polymer films together and polymer film to glass wafer. Void-free bonding can be achieved at optimized bonding conditions in which surfaces to bond are smooth. Moreover, the bond interface is enough strong to bend without break. The adhesion strength of the bonded samples is so strong that fracture occurs in the polymer bulk rather than at the bond interface during a peeling test. Investigations of the bonded samples by transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR) reveal that bonding is achieved by chemical interactions between the polymer surface and deposited atoms. Also, bonding of polymer substrates coated with Al2O3 gas-barrier layer was performed. The gas barrier layer was deposited via Atomic layer deposition (ALD), which is reported to achieve dense deposited layer with high gas barrier property. Surfaces of the Al2O3 gas barrier layers on polymer film were successfully bonded by the above-mentioned method.

The room temperature bonding method of Al 2 O 3 barrier layers deposited using Atomic Layer Deposition

Room temperature bonding of Al2O3 layer deposited by Atomic Layer Deposition (ALD) was studied for fabrication of micro-electronics, and gas barrier structure of polymer films. ALD deposition was performed at different process temperature at 80, 150 and 250 °C. From results of AFM surface profile, samples prepared at higher temperature in ALD process have rough surface. Also polymer films processed at high temperature has large wrinkle. Bonded area using Si and polyimide substrate coated at 80 °C were large, and there is only small unbonded area.