Abstract: An InGaAsP thin film layer having the same index of refraction as a diffraction grating is inserted between a p-type InP clad layer and the diffraction grating composed of an InGaAsP layer. In this structure, the InGaAsP layer is present over an active layer, and the amount of thermal diffusion of dopant to the vicinity of the active layer does not depend on an aperture width or the presence or absence of the diffraction grating when the p-type InP clad layer is grown, thereby obtaining a stable optical output, a threshold current, and slope efficiency.

Abstract: In a dry etching step for an organic material film, a fluorine-containing member is disposed to the periphery of a semiconductor substrate disposed on a lower electrode or a tray for wafer transportation to form fluorine (fluoro-radicals) from the member per se in addition to the fluoric gas added to the etching gas, with a purpose of removing reaction products, thereby removing reaction products deposited on the semiconductor substrate efficiently and stably.

Abstract: During the polishing of a semiconductor substrate, the semiconductor wafer that has been reduced in thickness, and hence in strength, by polishing, suffers outer-surface damage (or cracking) due to the initial damage caused by the use of polishing quartz. In order to solve these problems, the present invention applies a semiconductor substrate fixing jig formed with, on the face for fixing the semiconductor substrate, a groove(s) of almost the same diameter as that of the semiconductor substrate. Semiconductor substrate damage and cracking can be suppressed by applying this jig.