New Development in Hot Wall Vapor Phase Epitaxial Growth of Silicon Carbide

Abstract

The progress in performance of devices made from Silicon Carbide (SiC) is to a large extent related to the quality and the size improvements in bulk material growth and homoepitaxial growth. Homoepitaxial growth of SiC by vapor phase epitaxy (VPE) was started in the mid 1980th due to unsatisfactory results in epilayer quality by growth techniques such as liquid phase epitaxy and close space sublimation. The first VPE-reactors for SiC were former gallium-arsenide reactors converted to meet the requirements for the growth of SiC. Figure 1 shows the schematic drawing of such a converted VPE-reactor. The heating of the substrate and the reactive gases was provided by high purity graphite susceptors, which were heated up to the growth temperature of about 1500°C by round or pancake like RF-coils. Because of the high temperatures SiC is grown, special care had to be taken to protect the quartz tube from being overheated, especially on the bottom side, where the susceptor is closest to the quartz. The thermal insulation of the susceptor was provided by graphite felt or highly reflective graphite layers deposited on additional quartz tubes. The reactor quartz tube was cooled by either water or air. Hence, the surrounding quartz tube walls were several hundred degrees colder than substrate and susceptor. This reactor type with cold sidewalls was called horizontal cold wall reactor.Open image in new windowFig. 1Schematic drawing of a horizontal cold wall VPE-reactor for the epitaxial growth of SiC. The SiC substrate is placed on a high purity graphite susceptor, which is thermally insulated from the quartz tube and is heated up to the growth temperature by the RF-coil