Pressure mediated release of hydrogen from silicon co‐implanted with H₂⁺ and He⁺

Abstract

Hydrogen out-diffusion from porous-like buried layers prepared in single crystalline Si by implantation with hydrogen (Si : H) or hydrogen and helium (Si : H, He) depends, among others, on the sequence of layers enriched with H and He and on implantation conditions. Hydrogen loss at 720 -920 K decreases, increases or does not depend on hydrostatic pressure of ambient (HP, up to 1.1 GPa). This unusual effect is related to specific microstructure of Si : H, He induced under HP and to the He-mediated energy of creation of vacancies as well as of the strength of H -Si bonds.

Buried spongy‐like layers in silicon implanted with He+, annealed and treated in D+ plasma

“…The same has been observed after implantation with heavy hydrogen isotope, D + [3] and in Cz-Si co-implanted with H 2 + and He + [4]. The microstructure of Si:He, prepared by implantation of Si with He + only, reminds that of spongy -like silicon [5], especially if processed under HT -HP conditions [6].…”

“…9 it can be seen that, upon annealing under high pressure, more deuterium atoms are still present in the sub-surface region of Si:He:D, thus indicating a suppression of the deuterium out-diffusion. Thus, the high pressure processing of Cz-Si:He creates the conditions, under which a formation of the stiffer layer, preventing hydrogen out-diffusion in case of hydrogen based ion-cut processes, can be expected (compare [1][2][3][4][7][8][9]). …”

Deuterium accumulation within nano‐structured layers in Si:He upon plasma treatment

“…Much enhanced out-diffusion of deuterium occurs under HP. This unusual effect has been reported earlier for the Si:H,He structures and explained qualitatively as related to the He-mediated strenght of H-Si bonds under HP [6]. Marked redistribution of deuterium occurs at this step, especially for annealing done under 1.1 GPa (Fig.…”

“…Porosity has been also reported for Si implanted with heavy hydrogen isotope, deuterium [5] and for Cz-Si co-implanted with H 2 + and He + ions [6,7], especially after processing at HT, HP conditions [8].…”