Diffractive optical element and method of manufacturing the same

• US 6,611,376 B1
• Filed: 06/02/1998
• Issued: 08/26/2003
• Est. Priority Date: 06/06/1997
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Takeuchi, Seiji, Murakami, Eiichi
• Primary Examiner(s): CHANG, AUDREY Y
• Application Number:
  US09/089,480
• Time in Patent Office: 1,911 Days
• Field of Search: 359/565, 359/566, 359/570, 359/900, 359/569, 356/124, 356/127, 216/26, 512/84.R
• US Class Current: 359/566
• CPC Class Codes: G02B 5/1847 Manufacturing methods
• CPC Class Codes: G03F 7/70216 Mask projection systems
• CPC Class Codes: Y10S 359/90 Methods

Abstract

The present invention discloses a diffractive optical element whose optical axis can be precisely positioned, and a method of manufacturing the diffractive optical element. The diffractive optical element includes a region provided with a concentric uneven pattern and having a predetermined light bending characteristic, and a peripheral section worked so that the optical axis of the diffractive optical element determined by the light bending characteristic of the region aligns with the center of the profile of the diffractive optical element.

Claims

1. A method of manufacturing a diffractive optical element, which is turned by a turntable and has a light-bending function, said method comprising:

a first step of forming a diffraction grating of the diffractive optical element;

a second step of detecting the state of light transmitted from a light source through the diffractive optical element while turning the diffractive optical element about a turn axis of the turntable;

a third step of adjusting relative positions of an optical axis of the diffractive optical element and the turn axis to minimize a detected amount of shift of the light detected by said second step; and

a fourth step of cutting an outer periphery of the diffractive optical element, so that the optical axis of the diffractive optical element aligns with a center of a profile of the diffractive optical element.

2. A diffractive optical element manufactured according to the method of claim 1, wherein the light-bending function is provided by the diffraction grating, and the diffraction grating is formed on a flat surface.

3. A diffractive optical element according to claim 2, wherein the diffraction grating is shaped like a staircase in cross section.

4. A projection exposure apparatus, comprising:

an illumination optical system for illuminating a reticle with a pattern formed thereon; and

a projection optical system for projecting the pattern onto a wafer,

wherein at least one of said illumination optical system and said projection optical system has a diffractive optical element manufactured by a method according to claim 1.

5. A device manufacturing method, comprising the steps of:

applying a photosensitive material onto a wafer;

transferring a pattern formed on a reticle onto the wafer by using a projection exposure apparatus claimed in claim 4, and

developing the pattern transferred onto the wafer.

6. A method according to claim 1, wherein said fourth step is performed after said first step.

7. A diffractive optical element manufacturing apparatus for manufacturing a diffractive optical element having a diffraction grating formed on a substrate, said apparatus comprising:

a turning unit adapted to turn the diffractive optical element about a turn axis;

a detector adapted to detect an offset between the turn axis and an optical axis of the diffraction grating;

position adjustment unit adapted to adjust relative positions of the turn axis and the diffraction grating based on a detection result provided by said detector; and

a cutter adapted to cut an outer periphery of the diffractive optical element while the diffractive optical element is being turned by said turning unit so that the optical axis of the diffraction grating aligns with a center of a profile of the diffractive optical element.

8. A manufacturing apparatus according to claim 7, wherein said detector comprises:

a light emitting unit adapted to cause light to enter the diffractive optical element; and

a light receiving unit adapted to receive light emitted from the diffractive optical element.