Optical system for mask inspection

Abstract

Disclosed is an optical system for mask inspection, comprising an objective lens, a first beam splitter, a second beam splitter, a primary tube lens, and a tube lens switching mechanism. The objective lens, the first beam splitter, the primary tube lens, the tube lens switching mechanism, and the second beam splitter are sequentially arranged along an inspection optical path. At least two secondary tube lenses are connected into the tube lens switching mechanism. The tube lens switching mechanism is used to drive the secondary tube lenses to move, so as to switch different secondary tube lenses into the inspection optical path. Consequently, light, after passing through the objective lens, is transmitted to the primary tube lens through the first beam splitter, then passes through the primary tube lens and the secondary tube lens positioned in the inspection optical path, and then enters the second beam splitter. In the present utility model, optical magnification can be adjusted by means of switching tube lenses, thereby enabling inspection of masks with different line widths and improving inspection efficiency.

Description

Mask detection optical system

[0001] TECHNICAL FIELD

[0002] The utility model relates to a mask detection optical system.

Claims

1. A mask inspection optical system characterized by comprising: The objective lens (1), the first beam splitter (2), the first-stage tube lens (4), the tube-lens switching mechanism (100) and the second beam splitter (3) are sequentially arranged along a detection light path. The tube-lens switching mechanism (100) is connected with at least two second-stage tube lenses (5). The tube-lens switching mechanism (100) is used to drive the second-stage tube lenses (5) to move so as to switch different second-stage tube lenses (5) to move into the detection light path, and then the light rays pass through the objective lens (1), are transmitted to the first-stage tube lens (4) through the first beam splitter (2), and then pass through the first-stage tube lens (4) and the second-stage tube lens (5) located in the detection light path and are incident into the second beam splitter (3). The second beam splitter (3) is used to decompose the received light rays into transmitted light rays directed to the first camera (6) and reflected light rays directed to the second camera (7).

2. The mask inspection optical system of claim 1, wherein, The first camera (6) is used to capture the transmitted light rays, and the second camera (7) is used to capture the reflected light rays. The second beam splitter (3) is mounted in the lens barrel (8). The lens barrel (8) has a first exit portion (9) and a second exit portion (10), the first camera (6) is connected to the first exit portion (9), the second camera (7) is connected to the second exit portion (10), the transmitted light rays pass through the first exit portion (9) and are directed to the first camera (6), and the reflected light rays pass through the second exit portion (10) and are directed to the second camera (7).

3. The mask inspection optical system of claim 2, wherein, The first camera (6) and the second camera (7) are both TDI cameras. The tube-lens switching mechanism (100) comprises a rotating seat (11) and at least two second-stage tube lenses (5). The rotating seat (11) is rotationally arranged, the second-stage tube lenses (5) are connected to the rotating seat (11) and are sequentially and spacedly distributed along the circumference of the rotating seat (11), and the rotating seat (11) is used to rotate so as to switch different second-stage tube lenses (5) to move into the detection light path.

4. The mask inspection optical system of claim 2, wherein, The tube-lens switching mechanism (100) further comprises a driving motor, the driving motor is in transmission connection with the rotating seat (11) and is used to drive the rotating seat (11) to rotate so as to switch different second-stage tube lenses (5) to move into the detection light path.

5. The mask inspection optical system of claim 1, wherein, The rotating seat (11) is provided with mounting through holes corresponding to the second-stage tube lenses (5) in one-to-one correspondence, and the second-stage tube lenses (5) are connected in the corresponding mounting through holes. ​ 6. The mask inspection optical system of claim 5, wherein, ​ ​ 7. The mask inspection optical system of claim 1, wherein, The preview device comprises a preview optical path camera (12), a preview optical path lens (13) and a preview optical path light source (14); the preview optical path lens (13) is connected to the preview optical path camera (12), the preview optical path light source (14) is located below the preview optical path lens (13), and the mask (200) moves below the objective lens (1) after passing between the preview optical path lens (13) and the preview optical path light source (14).

8. The mask inspection optical system of claim 7, wherein, The mirror seat (15) is further included, the first beam splitter (2) is installed in the mirror seat (15), and the preview optical path lens (13) is connected to the mirror seat (15) through a support (16).

9. The mask inspection optical system of claim 1, wherein, The focusing device (17) for focusing the objective lens (1) is further included, the objective lens (1) is connected to the focusing device (17), and the focusing device (17) is used to drive the objective lens (1) to move to adjust the distance between the objective lens (1) and the mask (200).

10. The mask inspection optical system of claim 1, wherein, The first beam splitter (2) is a semi-transparent and semi-reflective beam splitter, and the second beam splitter (3) is a polarization beam splitter.

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