Laser dicing device
AssigneeTokyo Seimitsu Co., Ltd.
InventorKazushi HYAKUMURA
Life of this patent
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Abstract
A height position of a surface of a wafer can be detected accurately and stably without being affected by variation in a thin film formed on the surface of the wafer. An AF (autofocus) device irradiates the surface of the wafer W with an AF laser beam, detects reflection light thereof for each wavelength with a detection optical system. An AF signal processing unit outputs a displacement signal indicating displacement of the surface of the wafer to a control unit on the basis of a detection result of the detection optical system. Moreover, the AF device includes a focus optical system disposed in an irradiation optical path which is an optical path from the light source unit to a light converging lens. The focus optical system adjusts a light converging point of the AF laser beam in a wafer thickness direction.
Claims9
A laser dicing device comprising:
- a table configured to hold a wafer;
- a processing laser light source configured to emit a processing laser beam for forming a modified region inside the wafer held by the table;
- a light converging lens configured to converge the processing laser beam emitted from the processing laser light source inside of the wafer;
- a light converging lens actuator configured to displace a light converging point of the processing laser beam converged by the light converging lens in a wafer thickness direction by moving the light converging lens in an optical axis direction of the processing laser beam;
- a height position detector configured to detect a height position of a laser beam irradiation surface of the wafer held by the table;
- and
- a control unit configured to control the light converging lens actuator based on a detection signal from the height position detector, wherein
- the height position detector includes:
- a detection laser beam output unit configured to output a plurality of detection laser beams with different wavelengths;
- an optical path branching unit disposed in an irradiation optical path which is an optical path from the detection laser beam output unit to the light converging lens, the optical path branching unit configured to branch a part of reflection light of the plurality of detection laser beams converged by the light converging lens and emitted to and reflected by the laser beam irradiation surface of the wafer;
- a light detector configured to detect the reflection light of the plurality of detection laser beams branched by the optical path branching unit for each wavelength;
- a displacement signal generating unit configured to output a displacement signal indicating displacement of the laser beam irradiation surface of the wafer to the control unit based on light amounts of the plurality of detection laser beams detected by the light detector for each wavelength;
- and
- a light converging point adjustment optical system configured to adjust a light converging point of the detection laser beam in the wafer thickness direction.
Dependencies are inferred from the claim text.