Metal-Assisted Chemical Etching and Electroless Deposition for Fabrication of Hard X-ray Pd/Si Zone Plates

Abstract

Zone plates are diffractive optics commonly used in X-ray microscopes. Here, we present a wet-chemical approach for fabricating high aspect ratio Pd/Si zone plate optics aimed at the hard X-ray regime. A Si zone plate mold is fabricated via metal-assisted chemical etching (MACE) and further metalized with Pd via electroless deposition (ELD). MACE results in vertical Si zones with high aspect ratios. The observed MACE rate with our zone plate design is 700 nm/min. The ELD metallization yields a Pd density of 10.7 g/cm 3 , a value slightly lower than the theoretical density of 12 g/cm 3 . Fabricated zone plates have a grid design, 1:1 line-to-space-ratio, 30 nm outermost zone width, and an aspect ratio of 30:1. At 9 keV X-ray energy, the zone plate device shows a first order diffraction efficiency of 1.9%, measured at the MAX IV NanoMAX beamline. With this work, the possibility is opened to fabricate X-ray zone plates with low-cost etching and metallization methods.

Micromachining of High Quality PMN–31%PT Single Crystals for High-Frequency (>20 MHz) Ultrasonic Array Transducer Applications

“…In most studies, high-frequency ultrasonic array transducers using PMN-PT and their composites were developed by low-stress dry and wet chemical etching techniques [7,8,11]. However, the etching processes are complicated, time consuming, very expensive, and pollutional [12][13][14].…”

Micro- and Nano-Fabrication by Metal Assisted Chemical Etching

“…The publications addressing the use of MacEtch for specific X-ray optics fabrication is 13 with the first reports in 2014. [2,8,15,17,18,21,[24][25][26]31,32,[35][36][37][38][39][40][41]43,47,50,51,54,[56][57][58]62,63,71,73,77,78,93, and specific for X-ray optics fabrication [17,18,21,[35][36][37][38][39][40][41]93,119,126,153].…”

“…Figure 14. Number of publications as a function of year regarding MacEtch for producing high aspect ratio (HAR) patterned structures[2,8,15,17,18,21,[24][25][26]31,32,[35][36][37][38][39][40][41]43,47,50,51,54,[56][57][58]62,63,71,73,77,78,93, and specific for X-ray optics fabrication[17,18,21,[35][36][37][38][39][40][41]93,119,126,153].…”

Microfabrication of X-ray Optics by Metal Assisted Chemical Etching: A Review

“…The publications addressing the use of MacEtch for specific X-ray optics fabrication is 13 with the first reports in 2014. [2,8,15,17,18,21,[24][25][26]31,32,[35][36][37][38][39][40][41]43,47,50,51,54,[56][57][58]62,63,71,73,77,78,93, and specific for X-ray optics fabrication [17,18,21,[35][36][37][38][39][40][41]93,119,126,153]. X-ray optics with nanostructured features, such as kinoform lenses and Fresnel zone plates, showed to benefit from MacEtch fabrication.…”