Glass diffraction grating and method of producing the same

A method of producing a diffraction grating of borosilicate glass or barium borosilicate glass, a period of the grating being from 0.2 to 10 micrometers and an aspect ratio of grooves of the grating being 2 or greater, the method comprising the steps of:

• forming a grating on a surface of a silicon wafer through the Bosch process;
• forming an oxide film on a surface of the grating by heating and exposure to water vapor of the silicon wafer;
• removing the oxide film using hydrofluoric acid;
• making the surface provided with the grating of the silicon wafer and a surface of a glass plate undergo anodic bonding in a container kept at the degree of vacuum of 0.01 to 0.1 pascals;
• heating the silicon wafer and the glass plate that have been bonded to each other so as to melt glass and to fill spaces formed between ridges of the grating of silicon with the molten glass;
• polishing a surface opposite to the bonded surface of the silicon wafer and a surface opposite to the bonded surface of the glass plate;
• and
• removing silicon from the glass plate by selective etching using xenon difluoride gas.