Titanium acts as an adhesion-promoting layer between the substrate and the gold surface. This bonding function helps the multilayer interface remain attached to silicon, glass, or polymers, where gold alone may not provide sufficient adhesion. Reliable bonding is especially important when contacts must withstand fabrication steps or continued operation without delamination.
Layer thickness and deposition conditions influence how effectively the titanium supports adhesion and how well the gold performs as the exposed electrical surface. An unsuitable combination can affect resistance, bonding, or structural stability. Engineering optimization therefore considers both layers together rather than treating the gold coating as an independent component.
Diffusion and delamination are key reliability concerns. Diffusion can allow material movement between layers or into nearby regions, while delamination separates the contact from its substrate. Either process can undermine the intended interface and affect electrical operation. Evaluating resistance to these changes helps determine whether a contact design is suitable for fabrication and use.
Gold primarily supplies the exposed, conductive interface and resists chemical degradation, making it suitable for probing, wire bonding, and device operation. Titanium contributes strong attachment to the substrate beneath it. This division of functions explains why the contact uses a layered structure: one metal supports adhesion while the other provides the functional surface.
A typical design sequence begins with preparing the substrate surface, depositing a thin titanium layer, and placing gold above it. The process must control surface preparation, layer thickness, and deposition conditions because these variables affect adhesion, resistance, and long-term stability. The resulting stack should also be assessed for diffusion or delamination risks before device use.
These contacts support electrical connections in sensors, microelectromechanical systems, semiconductor devices, and bioelectronics. Their combination of substrate adhesion, conductive access, and chemical stability makes them useful where small patterned interfaces must connect a device to external probing or bonding equipment. The same contact architecture can therefore serve both experimental characterization and operating devices.