Silicon on Ceramics - A New Concept for Micro-Nano-Integration on Wafer Level

A new integration concept for micro-nano-integration based on a new bonding technique between nano-scaled, modified Black Silicon (BSi) and an adapted, unfired LTCC substrate is presented. The novel technique enables to combine advantages of silicon and ceramic technology, especially electrical and fluidic interconnects from nmto mm-scale. Current bonding concepts of silicon on ceramics need joining materials like solders, adhesives or glass frits. Alternatively, silicon components can be mounted to a TCE-matched and fired LTCC by anodic bonding, which requires costly surface preparation by polishing. This step is eliminated by the use of the new technique. During a standard lamination process, a self-organized, nanostructured, grass-like silicon surface is joined with the green ceramic body. Pressure assisted sintering allows the cofiring of the composite. Dense contact between the Black Silicon surface and the ceramic, leading to a maximum average bonding strengths of 1775 N/cm2, is achieved by optimization of the nano-interface and the lamination procedure. The hermeticity of the interface has been proven showing helium leak rates up to 1.9*10 mbar l/s. Hereby, a gas-tight interface (representing only a 10-nm leakage), which is impermeable for viruses and allows therefore biomedical use, is given. Electrical interconnects between ceramic body and silicon have been realized by means of metallized BSi penetrating into LTCC conductors. Prefabricated silicon-on-ceramic substrates with wiring and vias are compatible to a variety of semiconductor technologies for MEMS manufacturing.