Method of manufacturing phase-shifted diffraction grating

• US 5,221,429 A
• Filed: 02/07/1992
• Issued: 06/22/1993
• Est. Priority Date: 04/19/1990
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Makuta, Akio
• Primary Examiner(s): Powell, William A.
• Application Number:
  US07/778,942
• Time in Patent Office: 501 Days
• Field of Search: 156/643, 156/652, 156/654, 156/656, 156/657, 156/659.1, 156/661.1, 156/662, 430/296, 430/312, 430/313, 430/316, 430/321, 430/323, 430/329
• US Class Current: 216/24
• CPC Class Codes: G02B 6/124 Geodesic lenses or integrated gratings
• CPC Class Codes: G03F 7/001 Phase modulating patterns, e.g. refractive index patterns
• CPC Class Codes: H01L 21/3081 characterised by their composition, e.g. multilayer masks, materials
• CPC Class Codes: H01L 21/3086 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01S 5/1231 Grating growth or overgrowth details
• CPC Class Codes: H01S 5/124 incorporating phase shifts

Abstract

A photoresist 12 is coated on a substrate 11, and a phase shift medium 13 is formed on the photoresist 12. The phase shift medium 13 is patterned. Thereafter, first and second laser beams 16 and 17 having asymmetric incidence angles with respect to the substrate 11 are radiated on the photoresist 12 to perform an interference exposing operation. The photoresist 12 is developed and post-baked, and the substrate 11 is etched using the photoresist 12 as a mask, thereby forming a diffraction grating having a discontinuous phase portion.

Claims

1. A method of manufacturing a phase-shifted diffraction grating characterized by comprising the steps of:

coating a photoresist on a substrate;

forming a phase shift medium on said photoresist;

patterning said phase shift medium;

radiating first and second laser beams having asymmetric incidence angles with respect to said substrate on said photoresist to perform an interference exposing operation;

removing said phase shift medium;

developing and post-baking said photoresist; and

etching said substrate using said photoresist as a mask to form a diffraction grating having a discontinuous phase portion.

2. A method of manufacturing a phase-shifted diffraction grating according to claim 1, characterized in that said phase shift medium is an SiO₂ film.

3. A method of manufacturing a phase-shifted diffraction grating according to claim 1, characterized in that said phase shift medium is patterned such that an end portion of said phase shift medium is located at a phase-shifted portion.

4. A method of manufacturing a phase-shifted diffraction grating according to claim 1, characterized in that said substrate is etched by an etchant containing hydrogen bromide.