AlN/AlGaN/GaN buffer optimization on silicon (111): bow and crystal quality control for Si‐CMOS fabs

Abstract

In GaN‐on‐silicon there are many challenges which are currently encountered when making this technology compatible with standard Si‐CMOS fabs especially the bow. Bringing this technology to CMOS fabs can potentially drive the costs down, in addition to the cost advantage expected from large wafer sizes. We report here on the impact of AlN nucleation layer on crystal quality and bow. The focus will be on V/III ratios and pre‐dose conditions for AlN, which have considerable effect on the AlN/AlGaN/GaN buffer structures. We will also discuss how AlN thickness can be used to tune the bow. Finally, a brief description on the effect of surface pits will be presented.(© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Impact of the AlN nucleation layer on the variation of the vertical-direction breakdown voltage of AlGaN/GaN high-electron-mobility transistor structures on a Si substrate

“…The Al content of the AlGaN buffer layer showed no correlation with the VDBV of the HEMT structure on the AlN/Si template. Meanwhile, Kandaswamy et al reported that the crystal quality and surface pit of a HEMT structure has a strong dependency on the growth conditions of the AlN NL . These results suggest that the variation of the VDBV can be correlated with the growth conditions under which surface pits are formed in the AlN NL.…”

Temperature effect on Al predose and AlN nucleation affecting the buffer layer performance for the GaN-on-Si based high-voltage devices

“…[3][4][5] It has been shown that the AlN nucleation layer and its interface with a Si substrate plays a key role in formation of defects in the overgrown epitaxial structure, such as melt-back defects, inversion domains, V-pits or hillocks. [6][7][8][9][10] Through the AlN nucleation layer one can control stress and crystal quality in subsequent buffer and GaN layers. [7][8][9][10][11] Careful pre-treatment of Si substrate properties and the nucleation process can improve electrical properties of the HEMT devices such as a reduction of vertical leakage current (VLC).…”

“…[6][7][8][9][10] Through the AlN nucleation layer one can control stress and crystal quality in subsequent buffer and GaN layers. [7][8][9][10][11] Careful pre-treatment of Si substrate properties and the nucleation process can improve electrical properties of the HEMT devices such as a reduction of vertical leakage current (VLC). 9,[12][13][14][15] It has also been recently confirmed that the AlN/Si interface has a significant influence on the overall leakage and charge transport through the entire epitaxial structure during the HEMT operation.…”

“…[7][8][9][10][11] Careful pre-treatment of Si substrate properties and the nucleation process can improve electrical properties of the HEMT devices such as a reduction of vertical leakage current (VLC). 9,[12][13][14][15] It has also been recently confirmed that the AlN/Si interface has a significant influence on the overall leakage and charge transport through the entire epitaxial structure during the HEMT operation. [13][14][15][16][17][18] Therefore it is necessary to understand a mechanism of the AlN nucleation on the silicon substrate and optimize the AlN growth process.…”

“…23,24) Utilization of the Al predose led to an improvement in the AlN quality but many authors have reported that the amorphous Si x N y is still present on the AlN/ Si interface despite the Al predose. 6,9,25) Such a behavior can be explained by Si inter-diffusion through the interface during the HT AlN growth. An amorphous layer can be then formed by the AlSiN disordered alloy.…”