A LIGA-like method for the fabrication of silicon-based x-ray absorption gratings

We propose a simplified Lithographie, Galvanoformung, Abformung (LIGA)-like method for fabricating silicon-based, high-aspect-ratio x-ray absorption gratings by bonding silicon substrates with different resistivities, creating a pre-positioned electrode structure. This design significantly enhances conductivity contrast between the trench bottoms and sidewalls, enabling stable and uniform bottom-up gold electroplating without relying on specialized electrolytes or complex procedures. COMSOL simulations and nickel electroplating experiments verify the bottom-up growth characteristics. The fabrication of void-free gold absorption gratings (period 6 μm, depth 55 μm) is verified by scanning electron microscopy and x-ray phase-contrast imaging. Our method allows the use of commercially available cyanide-free gold plating solutions, making silicon-based absorption gratings more accessible and greatly benefiting the advancement of x-ray phase-contrast imaging technology. Furthermore, the method offers a practical alternative to conventional LIGA technology for microsystem applications.