Title :
Nano-structuring of silicon surface layers and nano-void formation by hydrogen plasma treatments
Author :
Job, R. ; Ulyashin, A.G. ; Fahrner, W.R.
Author_Institution :
Dept. of Electr. Eng., Univ. of Hagen, Germany
Abstract :
We summarize our recent results about nanostructuring of thin surface and sub-surface layers of Czochralski (Cz) silicon wafers by hydrogen plasma treatments. Standard Cz Si wafers were treated by a RF hydrogen plasma at about 250°C for 1 or 2 hours and subsequently annealed up to 2 hours at various temperatures up to 600°C in air. The surface/sub-surface Cz Si layers were studied by scanning electron microscopy (SEM), Raman spectroscopy and photoluminescence. On mechanically beveled samples by SEM the sub-surface wafer regions are investigated up to a depth of about 200 nm. Close to the surface, the treated wafers exhibit structures with the typical dimensions significantly below 100 nm. In deeper wafer regions, the structures become steadily larger (dimensions of a few 100 nm). By Raman spectroscopy, the samples were studied with regard to the formation of H 2-molecules. The H2-molecules are most probably located in sub-surface layers, but not directly at the surface, i.e. as nearly free H2-molecules in nano-voids or platelets (Raman shift 4150 cm-1). After annealing at 600°C in air, the nanostructured silicon exhibits a broad luminescence in the visible spectral range, which can be attributed to the evolution of the chemical structures and dimensions of Si based nano-clusters
Keywords :
Raman spectra; annealing; crystal growth from melt; elemental semiconductors; hydrogen; nanostructured materials; nanotechnology; photoluminescence; plasma materials processing; scanning electron microscopy; semiconductor growth; silicon; spectral line shift; surface structure; surface treatment; voids (solid); 1 hr; 100 nm; 2 hr; 200 nm; 250 C; 600 C; Cz Si wafers; Cz silicon wafers; Czochralski silicon wafers; H2; H2-molecule formation; RF hydrogen plasma; Raman shift; Raman spectroscopy; SEM; Si; anneal temperatures; annealing; chemical structures; hydrogen plasma treatment; luminescence; mechanically beveled samples; nano-clusters; nano-structuring; nano-void formation; nano-voids; nanostructured silicon; photoluminescence; platelets; scanning electron microscopy; silicon surface layers; sub-surface Cz Si layers; sub-surface layers; sub-surface wafer regions; surface Cz Si layers; thin sub-surface layers; thin surface layers; visible spectral range; wafer structures; Annealing; Hydrogen; Photoluminescence; Plasma temperature; Radio frequency; Raman scattering; Scanning electron microscopy; Silicon; Spectroscopy; Surface treatment;
Conference_Titel :
Industrial Electronics Society, 2000. IECON 2000. 26th Annual Confjerence of the IEEE
Conference_Location :
Nagoya
Print_ISBN :
0-7803-6456-2
DOI :
10.1109/IECON.2000.972563