Fabrication of ultra-high-aspect-ratio single-crystal diamond microchannel plate by laser etching and MPCVD epitaxial growth

To address the heat dissipation issue of high-power electronic devices, the fabrication process of a closed single crystal diamond (SCD) microchannel plate with an ultra-high aspect ratio was explored by adopting laser etching and epitaxial growth. Water-guided laser was used to finely etch the SCD substrate, forming deep grooves with steep and smooth sidewalls under optimized etching parameters. Following that, diamond epitaxial growth on the etched SCD substrate by microwave plasma chemical vapor deposition (MPCVD) under the proper process conditions was performed to fabricate the closed SCD microchannel plate, which 2075.2 μm in microchannel depth and 30.73 in aspect ratio. The closing process of microchannel plate during epitaxial growth was investigated, and the closing mechanism was analyzed. Finally, the continuity of the microchannel plate was verified. The successfully fabricated SCD microchannel plate is a regularly shaped and uniformly distributed microchannel structure. The analysis results of Raman spectra and X-ray diffraction rocking curves indicate that the crystal quality of the epitaxial growth layer is at a comparable level to that of the original substrate. This offers a novel technical approach with high processing repeatability and controllability for fabricating diamond microchannel plate with ultra-high aspect ratio. It shows great potential for applications in the fields of microfluidics and heat pipes.