Substrate holder for the metal-organic chemical vapor deposition

摘要

A substrate holder employed for MOCVD and supporting a wafer on which crystal growth proceeds includes a molybdenum holder body 1, a GaAs polycrystalline film 2 with a flat surface grown on a part of the surface of the molybdenum holder body where the wafer is absent, and an InP polycrystalline film 3 grown on the GaAs polycrystalline film. Each of the polycrystalline films is grown to a thickness of 0.3 mu m or more at a temperature higher than the epitaxial growth temperature of 575 DEG C. During the MOCVD process, the emissivity of the molybdenum substrate holder is settled at a value near the emissivity of the wafer on the substrate holder and, therefore, the decomposition ratio of the PH3 gas on the substrate holder is settled at a value near the decomposition ratio on the wafer, whereby the variation of the incorporation ratio of P atoms in the InGaAsP mixed crystal, i.e., the variation of the composition of the InGaAsP mixed crystal, is reduced and the run-to-run variation of the composition of the mixed crystal is reduced. In further embodiments an InGaAsP, at a temperature higher than 575 DEG C, and InP, at 400 - 550 DEG C, may be deposited on the molybdenum. The MOCVD apparatus includes a high-speed rotatable susceptor 200b; a substrate holder 300b disposed on the front surface of the susceptor; means for heating said susceptor; an inlet for supplying source gases; and a plurality of rotatable wafer trays 600a disposed on the front surface of the susceptor via the substrate holder, each wafer tray having a plurality of wings 600a1 to which a gas flow is applied. IMAGE