Characterization of residual strain in epitaxial Ge layers grown in sub-100nm width SiO2 trench arrays

• Published in: Thin solid films Vol. 580; pp. 45 - 51
• Main Authors: Kim, Byongju, Jang, Hyunchul, Koo, Sangmo, Kim, Jeong-Hoon, Kim, Dae-Hyun, Min, Byoung-Gi, Song, Jason S., Ko, Dae-Hong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-04-2015
• Subjects: Arrays; Epitaxial growth; Germanium; Mathematical analysis; Nanobeam electron diffraction (NBD); Reciprocal space mapping (RSM); Selective epitaxial growth (SEG); Silicon dioxide; Strain; Trenches; Walls; Nanobeam electron diffraction (NBD); Reciprocal space mapping (RSM); Selective epitaxial growth (SEG); Ge; Strain
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2015.03.006

We examined the selective epitaxial growth of Ge on Si(001) substrates with 40, 65, and 90nm width trench arrays by ultra-high vacuum chemical vapor deposition. Because SiO2 trench walls were present, no surface undulation in the direction parallel to the trenches was observed and compressive strain developed in the same direction. Based on reciprocal space mapping (RSM) measurements, this strain along the parallel direction increased from −0.28 to −0.72% as the width of the exposed Si substrate between the SiO2 walls decreased from 90 to 40nm, which was due to a decrease in strain relaxation. We calculated the effect of the Si trench width on changes in strain after removing the SiO2 walls and compared the calculated values with the RSM results. No significant change in the strain relaxation was detected along the direction perpendicular to the trenches, and the strain changes were <0.1%.
•Epitaxial Ge layers were selectively grown in sub-100nm oxide trench arrays.•Compressive strain in Ge along trench directions was observed.•As the exposed trench width decreased, compressive strain values increased.•After removing the oxide trenches, the compressive strain in Ge was maintained.