| 摘要 |
PURPOSE:To easily manufacture a lambda/4 shift type diffraction grating whose transition region is very short by utilizing the reversibility of an etching method and a lift-off method. CONSTITUTION:A patterning layer 2 composed of an SiO2 film and novorak system positive type photoresist 3 are formed o an N-type InP semiconductor substrate 1. The photoresist 3 is exposed to form a periodical pattern and the SiO2 film 2 is etched by buffered fluoric acid with the patterned photoresist 3 as a mask to form a periodical pattern and then the photoresist 3 is removed. After the region II is covered with photoresist 4, the n-type InP semiconductor substrate 1 is etched in the region I by HBr+H2O2+H2O with the SiO2 film 2 as a mask to form a diffraction grating 5. After the photoresist 4 is removed, an Al film 6 is formed. If the periodical SiO2 film 2 remaining in the region II is etched and the Al film 6 on the SiO2 film 2 is removed by lift-off, the Al film 6 in the region II is periodically patterned. The InP substrate 1 is etched by HBr+H2O2+H2O2 with the Al film 6 as a mask to form a diffraction grating 5' in the region II. |
