Diffractive optical component making method

Abstract

To provide a method for fabricating a high precision diffraction optical element capable of enhancing diffraction efficiency. [MEANS FOR SOLVING PROBLEMS] A diffraction optical element having a periodical stepwise profile is fabricated by repeating a series of processes for exposing and developing a substrate (1) coated with resist (2) through a mask to form a resist pattern and then etching the resist pattern. In the first process, a pattern having a width identical to that of the step is formed and then the width of the pattern is increased in the subsequent processes. When fabricating a seven-step diffraction optical element assuming the level difference of step is D, the second, fourth and sixth step portions are etched with depth D in the first process the ninth step portion is etched with depth 2D in the second process, the fifth, sixth and seventh step portions are etched with depth 2D in the third process, and the third, fourth, fifth, sixth and seventh step portions are etched with depth 2D in the fourth process.

Description

technical field [0001] The present invention relates to a method of manufacturing a diffractive optical element having a stepped shape. Background technique [0002] In recent years, there has been an increasing demand for diffractive optical elements that control the traveling direction and phase of light based on periodic fine shapes. There are various shapes of diffractive optical elements. Among them, a diffractive optical element with a zigzag cross section has a high logical diffraction effect. In fact, a stepped diffractive optical element similar to the zigzag shape is easy to manufacture and is widely used. Generally, as a method of manufacturing a diffractive optical element having a stepped shape, there is a method described in the following Non-Patent Document 1, which uses m (m is a natural number) masks to repeatedly expose, A series of processes of developing and etching, manufacturing 2 m class diffractive optical elements. For example, in the case of an 8...

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Problems solved by technology

In this way, in the conventional manufacturing method, a stepped shape with a size different from the design value may be formed, or a protrusion may be generated at the edge, so there is a problem of causing a decrease in diffraction efficiency.

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