Eutectic bonding, also called eutectic soldering, is where the combination of two or more metals allow direct transformation from solid to liquid state or vice versa at specific temperature without passing two-phase equilibrium. The eutectic temperature is much lower than the melting temperature of the materials that are involved in the bonding process. Eutectic bonding is ideal for high-vacuum applications as this process has very low outgassing.
Eutectic wafer bonding is widely used in the MEMS industry for hermetic sealing, pressure or vacuum encapsulation as it allows highly reliable wafer-level processing for devices with the smallest form factors. The most common metals/alloys that are used in eutectic bonding are Al-Ge, Au-Sn and Au-In. However, there are many other material combinations available that can produce a eutectic bonding system. Additionally, the ability of silicon to alloy with metals like Au can also be the basis for eutectic bonding. All eutectic bonds must go through a liquid phase and thus are less sensitive to surface flatness irregularities, scratches and particles, thereby facilitating high volume manufacturing. Bonding temperature, time and pressure are the most important parameters for eutectic bonding where high bond strength can be achieved with low processing temperature and minimum resultant stress. Eutectic bonding can additionally enable hermetic sealing and electrical interconnections in a single process. Compared to other intermediate layers, such as adhesives or glass-frit, eutectic bonding also promotes better out-gassing and hermeticity.
Visit our booth 1520!
Visit our booth #L0316 and listen to our talks at the Heterogeneous Integration Global Summit on Friday 12th Sep, 14:10 with the title: “Fusion and Hybrid Wafer Bonding: The Past, The Present, and the Future” held by Team Leader Business Development Dr. Bernd Dielacher and at the TechXPOT at 13:00 with the title “Digital Lithography LITHOSCALE® Accomplishes Patterning of High-Resolution Novel Resists and Dielectric Materials for Next Generation AI and HPC Devices” held by Corinth Kuo.
Visit us at our booth & listen to our talk “Advanced Patterning For Smart Optical Devices: Integrating Inkjet Coating with Nanoimprinting for Precise Height Control and Minimal Residual Layers” held by Business Development Manager Andrea Kronawitter!
Contact the EVG experts