Manufacturing method of a semiconductor device having a diffraction grating

Abstract

A first layer of InP is deposited on a diffraction grating so as to cover it, by MOCVD in which PH or organophosphorus is used as a source material of P and in which H is used as a carrier gas. The substrate is heated up to a temperature which is higher than the substrate temperature during the first layer deposition, and then a second layer is deposited on the first layer. An active layer is deposited on the second layer. Found out is such a growth rate of an InP layer as to cause the photoluminescence intensity of a layer corresponding to the active layer to be one tenth as small as that when the InP layer is deposited at a growth rate of 0.2 microns per hour in the case where the InP layer deposition is carried out instead of the first layer deposition under the conditions wherein the ratio of the flow rate of the source material of P to the total flow rate of the carrier gas and the substrate temperature are the same as those in the first layer deposition but the growth rate of the InP layer is different from that of the first layer. The growth rate of the first layer is lower than such a growth rate of the InP layer as to cause the photoluminescence intensity to be one tenth. Accordingly, a diffraction grating can be formed with excellent reproductiveness and high accuracy, moreover, a high quality semiconductor layer can be deposited on thus formed diffraction grating.