Effect of the Synthesis Conditions and Microstructure for Highly Effective Electron Shields Production Based on Bi Coatings

Abstract

Microelectronic products are very sensitive to ionizing radiation (electrons, protons, heavy charged particles, X-ray, and γ radiation). Lead is the commonly used material for radiation protection. Bismuth deposition has become an interesting subject for the electrochemical community because of bismuth’s unique electrical, physical, and chemical properties. There is a limited number of authors dealing with deposition of continuous bismuth films onto metallic substrates by electrodeposition method. The conditions of Bi electrochemical deposition and the structure of Bi coatings were examined. X-ray diffraction patterns for all samples were indexed to rhombohedral Bi. Coatings with a signified texture (012) are formed in electrolyte without additives. With gelatin the growth texture changes, and the most intense reflex becomes (110). It was found that increasing gelatin concentration from 0.1 to 0.5 g/L leads to Bi microstructural refinement from 4–20 μm, to from 50 nm to 2 μm, respectively. The protection efficiency of Bi-based shields under 1.6–1.8 MeV electron radiation energy was measured. The electron beam attenuation efficiency was estimated by the changing of current–voltage characteristics of semiconductor test structures which were located behind the shields and without them. It has been determined that optimal protection effectiveness and mass-dimensional parameters are enabled by Bi shields with 2 g/cm2 reduced thickness and 156 attenuation coefficient.