Temporary Wafer Bonding

Temporary bonding and debonding are two main technologies for 3D integration, as well as for other processes such as TSV fabrication, microbumping, wafer thinning and backside RDL formation.

Selecting a suitable adhesive for temporary bonding is key to ensuring a reliable result in thin wafer processing. The mechanical properties and chemical stability of the adhesive must meet the material specifications applying to production processes.

Mechanical debonding at room temperature and excimer laser assisted debonding meet all normal requirements applying to the debonding process.

Overview of technologies by SUSS MicroTec

Temporary Wafer Bonding

To minimize the risks in thin wafer handling, the wafer is mounted on a carrier wafer prior to thinning. Bonding is only to facilitate further processing – the bond is designed to be dissolved once the wafer is processed.

Process steps required for temporary wafer bonding

  • Application of release layers (coating or plasma deposition)
  • Adhesive coating
  • Bonding
  • Thermal or UV curing

SUSS MicroTec offers an open platform that is compatible with all common material systems used in temporary bonding. In addition to the methods already used in production today, SUSS MicroTec is devoted to ongoing work towards qualifying new materials, in this way supporting the largest selection of adhesives currently available in the market.

Customer benefits

  • Open bonding platform supporting flexible configuration and all common adhesives and techniques
  • Coating of bonding and release layers, including temporary bonding, in one system
  • Integrated metrology to determine wafer thickness and TTV

Equipment

Mechanical Debonding

Various combinations of adhesive and release layers are available on the market that enable mechanical separation of the carrier wafer from the wafer before further processing. It is consequently essential to be able to vary parameters such as debonding speed and the debonding force applied in order to support the method applied in the particular case. The process needs to be controlled and monitored. During debonding, the thin wafer remains attached to dicing tape in order to facilitate further processing after being released from the carrier wafer.

The mechanical debonding processes supplied by SUSS MicroTec run at room temperature and are suitable for all common adhesives and techniques for temporary bonding. After debonding, the wafers require cleaning in order to remove any adhesive or release layer residues. Certain types of dicing tapes for mounting wafers have only limited resistance to cleaning media. Such tapes require protection during wafer cleaning.

Customer benefits

  • Open bonding platform supporting flexible configuration and all common adhesives and techniques
  • Controlled, monitored debonding process
  • Special protection during wafer cleaning allows unlimited choice of dicing tapes

Equipment

Laser Debonding

SUSS MicroTec’s laser debonding technology uses glass carriers with sufficient transmission at the wavelengths used in debonding processes. The adhesive is released by means of irradiation using a 248 nm or 308 nm excimer laser. In contrast to a solid state laser, the excimer laser breaks the adhesive’s chemical bonds in close proximity to the glass carrier interface. Considered a room temperature process, this debonding method results in no thermal stress at the debonding interface and achieves very high throughput.

Customer benefits

  • Laser debonding is compatible with a great variety of thermoplastic adhesives
  • Standard glass carries requiring no special release layer are used
  • Thin wafer is subjected to no thermal stress

Equipment

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