An empirical growth window concerning the input ratio of HCl/SiH₄gases in filling 4H-SiC trench by CVD

Abstract

Two kinds of defective growth in 4H-SiC trench filling were found to be associated with the compositional ratio of supplied gases. An input HCl/SiH4 ratio below 35 leads to overgrowth around the mesa, forming voids. Overetching on the mesa induces an etched mesa when HCl is supplied in excess, e.g., HCl/SiH4 > 65 (SiH4 = 30 sccm). Thus, an empirical window for nondefective growth is discerned. It also contains a high-filling-rate area around HCl/SiH4 ∼50, which proves well-proportioned etching and deposition reactions, and 25-µm-deep trenches (aspect ratio of ∼11) are successfully filled at a rate as high as 4.3 µm/h.

Effects of ion implantation process on defect distribution in SiC SJ-MOSFET

“…In SiC SJ-MOSFETs, several fabrication methods, such as multi-epitaxial growth 7,8) and trench-filling epitaxial growth, can be employed. [9][10][11] Among the fabrication methods, trench-filling epitaxial growth is not sufficiently easy for practical processes involved the mass production of devices. Specifically, it is difficult to form void-free trenches and fill them with defect-free epitaxial growth.…”

“…Specifically, it is difficult to form void-free trenches and fill them with defect-free epitaxial growth. [9][10][11] Conversely, multi-epitaxial growth enables the fabrication of SJ-MOSFETs with deep p-n columns via repeated ion implantation and epitaxial growth. 7,8) However, in this fabrication process, defect generation, via the ion implantation process, is unavoidable, and the defects will impact the performance of the device performance.…”

Selection of ion species suited for channeled implantation to be used in multi-epitaxial growth for SiC superjunction devices

“…Although a trench-etching-and-sidewall-implant method has been used to fabricate 1.35-kV SiC SJ Schottky diodes, 7,8) an increase in BV (i.e., trench depth > 6 μm) is limited by the difficulty in the sidewall implant with an incident angle more than 70°. 7,8) Large BV can be attained using a trench-filling epitaxial growth method; [9][10][11][12][13][14][15] however, complete filling of SiC around the trench edge has yet to be attained. 16) In contrast, a multiepitaxial growth method (ME), in which epitaxial growth and ion implantation are repeated alternately until a certain driftlayer thickness is achieved, has been successfully employed; namely, 1.54-kV SJ p-n diodes 17) and 0.82-kV SJ V-groove trench MOSFETs 18) fabricated using 9 MeV Al-ion implantation, as well as 1.17-kV SJ V-groove trench MOSFETs 19) and 1.2 kV-class SJ trench MOSFETs 20) fabricated using sub-MeV Al-ion implantation.…”

A 4H-SiC trench MOSFET structure with wrap N-type pillar for low oxide field and enhanced switching performance

“…Moreover, the practical feasibility of fabricating superjunction structures has been discussed by using the trenchfilling epitaxial growth method in some papers. Ji et al [21,22] studied and made possible uniform epitaxial filling in the 4H-SiC trench between 7 µm and 50 µm deep. There have also been significant advances in understanding the mechanisms of epitaxial growth of trench filling.…”