| 摘要 |
<p>PURPOSE:To vary the diffraction efficiency in a grating plane by a method wherein etchings of different depth are carried out in an etched surface by sputter etching under inclination of the surface to be etched in the region including a potential-inclined part. CONSTITUTION:A diffraction grating pattern of resist is prepared on an InP substrate 5 by interference exposure. The substrate 5 is placed on the cathode 3 of a parallel flat system RIE device, and is then inclined at 45 deg. rectangularly to the linear direction of the diffraction grating. Using CCl4, etching is carried out for 30sec ujnder a gas pressure of 5X10<-3>Torr at 13.56MHz and 150W. The accelerating voltage in the cathode 3 is VCC+VP but decreases below thid value when going off from the electrode 3 on the substrate 5. In case the physical etching is more dominant than the chemical etching, this accelerating voltage seriously influences the etching depth, thus, the etching with continuous changes in depth can be achieved. Since the accelerating voltage and the distribution of potential can be varied with the kind of gas, gas pressures, and powers, the proportion of continuous changes in etching depth can be arbitrarily determined by taking the angle of inclination of the substrate surface into consideration.</p> |
