SiC Migration Enhanced Embedded Epitaxial (ME³) Growth Technology

Abstract

In this work, we have developed an innovative epitaxial growth process named the “Migration Enhanced Embedded Epitaxial” (ME3) growth process. It was found that at elevated growth temperatures, the epitaxial growth at the bottom of the trenches is greatly enhanced compared to growth on the sidewalls. This is attributed to the large surface diffusion length of reactant species mainly due to the higher growth temperature. In addition, it was found that this high temperature ME3 growth process is not influenced by the crystal-orientation. Similar growth behavior was observed for stripe-trench structures aligned either along the [11-20] or [1-100] directions. No difference was observed in the electrical performance of the pn diodes fabricated on either oriented stripe geometry. The ME3 process can also be used as an alternative to ion-implantation technology for selective doping process.

Design, process, and performance of all‐epitaxial normally‐off SiC JFETs

“…The parameter a is almost constant in the temperature range of 1450 °C to 1650 °C. From a fitted linear line in Arrhenius plot configuration, the extracted surface migration activation energy is about 65 kcal/mol, which is higher compared with standard growth conditions [34,35].…”

Filling 4H-SiC trench towards selective epitaxial growth by adding HCl to CVD process

“…9,10) The line (L) and space (S) dimensions of the line pattern on the mask used for trench lithography were 1 and 1.5 µm, respectively, and the trench depths (D) were about 4.7 and 5 µm, respectively. The HWCVD system with a rotary substrate was utilized.…”

“…7) Therefore, trench filling by epitaxially filling doped SiC into trenches of the opposite conductivity type is considered the preferable method for constructing SiC-SJ structures. [8][9][10][11][12][13][14] In previous literature, 4H-SiC trenches with depths of up to 7 µm and aspect ratios of about 2-4 have been completely or half-filled by using hot-wall chemical vapor deposition (HWCVD) with a conventional gas system, SiH 4 : C 3 H 8 : H 2 . [8][9][10][11][12][13] However, Schöner et al mentioned the necessity of maintaining a slow growth rate and long duration of trench filling to minimize excessive growth outside of the trenches.…”

“…[8][9][10][11][12][13][14] In previous literature, 4H-SiC trenches with depths of up to 7 µm and aspect ratios of about 2-4 have been completely or half-filled by using hot-wall chemical vapor deposition (HWCVD) with a conventional gas system, SiH 4 : C 3 H 8 : H 2 . [8][9][10][11][12][13] However, Schöner et al mentioned the necessity of maintaining a slow growth rate and long duration of trench filling to minimize excessive growth outside of the trenches. 13) Though few details have been released, it is conjectured that the motivation for minimizing the growth outside of the trenches was to avoid the potential risk of void formation (fast closing around the trench's top corner) during long-duration growth.…”

“…Apparently, overgrowth on the mesa requires the additional process of device planarization (polishing) after the growth, and therefore, it degrades productivity. [8][9][10][11] In the CVD filling of a Si trench, to minimize the excessive growth on the mesa top and trench top corner, Yamauchi et al reported a nonmasked method of filling Si trenches by flowing HCl and SiH 2 Cl 2 together. HCl was added to prevent growth around the trench tops, which was predicted based on the fact that the reaction of Cl-Si is faster than that of Si-Si.…”