Arrays of micro Penning-Malmberg traps: AN approach to fabricate very high aspect ratios

This paper reports on the progress of fabrication of very high aspect ratio (1000:1) micro-Penning-Malmberg trap arrays designed to store antimatter. The structure consists of thousands of 100μm diameter tubes etched by deep reactive ion etching through Si wafers. Cycles of thermal oxidation and wet etching in buffered oxide etch (BOE) minimized the sidewalls roughness and ensured a complete coating during gold sputtering. The wafers were then aligned and stacked in order to create the microtubes. Uniform plating with mean roughness of R_a=600nm was achieved by tuning the electroplating parameters.