Progress in Bulk 4H SiC Crystal Growth for 150 mm Wafer Production

Abstract

The thermoelastic stress, mechanical properties and defect content of bulk 4H n-type SiC crystals were investigated following adjustments to the PVT growth cell configuration that led to a 40% increase in growth rate. The resulting 150 mm wafers were compared with wafers produced from a control process in terms of wafer bow and warp, and dislocation density. Wafer shape was found to be comparable among the processes, indicating minimal impact on internal stress. Threading edge and threading screw dislocation densities increased and decreased, respectively, while basal plane dislocation densities were unaffected by the increase in growth rate. Loss of wafer planar stability was observed in certain cases. The elastic modulus was measured to be in the range of approximately 420-450 GPa for selected stable and unstable wafers, and was found to correspond to resistivity.

Dislocations in 4H silicon carbide

“…Dislocations in 4H-SiC substrates can be generated during the growth and wafering processes as well as be replicated from seeds [24,25], many efforts have been made to reduce the dislocations densities. Up to now, the density of devicekilling MPs decreases to be lowered than 0.1 cm −2 in 4H-SiC substrates, while the densities of the other dislocations remain in the orders of magnitude of 10 2 -10 4 cm −2 [5,8,9].…”

“…In hexagonal 4H-SiC, dislocations are classified into threading dislocations (TDs) and basal plane dislocations (BPDs). The Burgers vectors, dislocation-line directions and densities of dislocations in commercialized 150 mm 4H-SiC single-crystal substrates are summarized in table 1 [5,8,9]. TDs in 4H-SiC can be classified into micropipes (MPs), threading screw dislocations (TSDs), threading mixed dislocations (TMDs) and threading edge dislocations (TEDs), which have the Burgers vectors of ±nc (n = 3-10), ±c, c + a, and ( [11 20]/3 ) a, respectively [17].…”

“…After decades of development, the commercialized 150 mm 4H-SiC single-crystal substrates are flourishing in the applications of high-power electronics based on the homoepitaxy of 4H-SiC thin films [5][6][7]. However, the density of dislocations in commercialized 150 mm 4H-SiC substrates is still as high as 10 3 -10 4 cm −2 [5,8,9].…”

“…After decades of development, the commercialized 150 mm 4H-SiC single-crystal substrates are flourishing in the applications of high-power electronics based on the homoepitaxy of 4H-SiC thin films [5][6][7]. However, the density of dislocations in commercialized 150 mm 4H-SiC substrates is still as high as 10 3 -10 4 cm −2 [5,8,9]. The high-density dislocations would either propagate into epitaxial layers, or convert to other types of dislocations or stacking faults (SFs) during the homoepitaxy of 4H-SiC.…”

Suppression of partial dislocation glide motion during contraction of stacking faults in SiC epitaxial layers by hydrogen ion implantation

“…[1][2][3] Different from silicon (Si), which can be produced dislocation-free by the Cz crystal growth technique, 4) SiC wafers contain many dislocations, which influence the performance, reliability, and yield of power devices. [5][6][7][8][9] Although the dislocation density in SiC wafers continues to improve day by day, [10][11][12][13][14][15][16] technologies for SiC power devices "with dislocations" are required. One of the critical issues that hinder the widespread use of SiC power devices is the bipolar degradation phenomenon.…”