Wafer Bonding

Polymer and adhesive bonding provide solutions for advanced packaging, 3D Integration, and temporary bonding. Many choices of materials including epoxies, dry films, BCB, polyimides, and UV curable compounds exist. SUSS MicroTec provides a full line of processing equipment for these applications. The wafer bonding products are specifically tailored to meet performance and cost of ownership needs for MEMS, lens stacking and CMOS Image Sensor manufacturing.

Anodic wafer bonding is used in MEMS processes whenever an ionic glass is used in the sensor fabrication. SUSS MicroTec aligner products include options for laser tacking and triple stack alignment which work in tandem with our wafer bonding systems to realize many advanced products. During triple stack wafer bonding three layers, glass/Si/glass, can be bonded simultaneously to increase functionality and throughput.

SUSS MicroTec provides complete production and development tools for anodic applications. Our experience can help bring your anodic process to production capacity with proven fixture and process cluster options currently in 24/7 production operations around the world.

Metal eutectic bonding of wafers is used in advanced MEMS packaging and 3D integration technologies. A unique feature of eutectic metals is the melting of the solder-like alloys that facilitate surface planarization and provides a tolerance of surface topography and particles.

Eutectic bonding requires precise force delivery and controlled uniform temperature to control reflow of the eutectic material. See the SUSS MicroTec CB wafer bonding series for more details.

Fusion wafer bonding is the spontaneous adhesion of two substrates placed in direct contact. Also termed silicon direct wafer bonding, this method describes the room temperature bond between wafers with or without dielectric layers following a wet chemical or plasma activation step.

The XBC300 Gen2 provides a cost effective 300mm platform offering plasma activation, wet chemistry application, alignment and wafer bonding.

Glass Frit wafer bonding has been the traditional wafer bonding technique used in MEMS production worldwide. Glass frit applications include three axis accelerometers, gyroscopes and pressure sensors used in automotive, gaming and cellular phone technology. SUSS MicroTec’s ABC200 is a standard production platform for glass frit wafer bonding. ABC200 production wafer bonding clusters are operating in 24/7 production environments worldwide within the MEMS industry. 

Metal diffusion bonds include Cu-Cu, Al-Al, Au-Au and others metallurgies that enable better hermeticity than traditional glass frit and anodic bonds. In addition, the use of metal diffusion bonds in 3D applications allows the mechanical and electrical connections to be made between two wafers in one step. Metal diffusion also enables superior post bond alignment accuracy over glass frit bonding. Aluminum metallization is used frequently in MEMS device structures and offers the potential to serve as a sealing metallurgy during device packaging steps via a diffusion reaction.

Advances in CMP techniques and deposition methods have made metal diffusion bonding an excellent choice for anodic and glass frit replacement. SUSS MicroTec’s CB wafer bonding series provide a high degree of temperature and force uniformity to meet the requirements for metal bonding.

During UV-bonding adhesives are applied to a wafer, in order to connect it with a second wafer. The curing takes place by means of UV light, which changes the chemical structure of the adhesive.

UV bonding is used primarily in the production of micro-lenses of wafer-level optics.