# US 12,191,168 B2 · Laser processing device, laser processing system and laser processing method

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- Number: US 12,191,168 B2
- Document ID: US12191168B2
- Status: Granted
- Kind: B2
- Application number: 16/979,191
- Filed: 2019-03-27
- Published: 2020-12-31
- Granted: 2025-01-07
- Earliest claimed: 2018-04-09
- Assignees: Tokyo Electron Limited
- Applicants: Tokyo Electron Limited
- Inventors: Hirotoshi Mori; Yoshihiro Kawaguchi; Hayato Tanoue; Kazuya Hisano
- Web page: https://patentgrep.com/patent/US12191168B2

## CPC

- H10P 72/0428: {Apparatus for mechanical treatment or grinding or cutting}
- H10P 72/7402: {Wafer tapes, e.g. grinding or dicing support tapes}
- B23K 26/0006: {taking account of the properties of the material involved (B23K26/32, B23K26/40 take precedence)}
- B23K 26/03: Observing, e.g. monitoring, the workpiece
- B23K 26/032: {using optical means}
- B23K 26/046: Automatically focusing the laser beam
- B23K 26/048: {by controlling the distance between laser head and workpiece}
- B23K 26/0665: {by beam condensation on the workpiece, e.g. for focusing}
- B23K 26/082: Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
- B23K 26/364: for making a groove or trench, e.g. for scribing a break initiation groove
- B23K 26/53: for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks
- G01B 11/0608: {Height gauges}
- G01B 11/0625: {with measurement of absorption or reflection}
- H10P 34/42: with electromagnetic radiation, e.g. laser annealing (laser cutting H10P54/20)
- H10P 54/00: Cutting or separating of wafers, substrates or parts of devices
- H10P 72/0436: {mainly by radiation}
- H10W 46/00: Marks applied to devices, e.g. for alignment or identification
- H10P 72/7416: {used during dicing or grinding}
- H10P 72/7422: {used to protect an active side of a device or wafer}
- H10P 72/744: {Details of chemical or physical process used for separating the auxiliary support from a device or a wafer}
- H10W 46/503: {Located in scribe lines}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A laser processing device includes a height measurement unit configured to measure a vertical direction position of an irradiation point of a processing laser beam on an upper surface of a substrate; and a controller configured to control a vertical direction position of a light condensing unit based on the vertical direction position of the irradiation point while moving the irradiation point along multiple dividing target lines. The height measurement unit includes a coaxial laser displacement meter and a separate-axis laser displacement meter. The controller controls the vertical direction position of the light condensing unit by using only one of the coaxial or the separate-axis laser displacement meter for each of the multiple dividing target lines while the substrate is processed and performs a switchover of a laser displacement meter for controlling the vertical direction position of the light condensing unit between the coaxial and the separate-axis laser displacement meters.

## Claims

### Claim 1

A laser processing device, comprising:
a substrate holder configured to horizontally hold a substrate from below;
a processing laser oscillator configured to oscillate a processing laser beam for processing the substrate;
a slider configured to move the substrate holder horizontally and move a processing irradiation point of the processing laser beam on an upper surface of the substrate held on the substrate holder;
a height measurement unit configured to measure a vertical direction position of the processing irradiation point;
a condensing lens configured to condense the processing laser beam from above to below the processing irradiation point;
an actuator configured to vertically move moves the condensing lens; and
a controller configured to control a vertical direction position of the condensing lens based on the vertical direction position of the processing irradiation point while moving the processing irradiation point along multiple dividing target lines on the upper surface of the substrate,
wherein the height measurement unit includes:
a coaxial laser displacement meter configured to measure a vertical direction position of a first measurement irradiation point, which is overlapped with the processing irradiation point in a vertical direction, by radiating, to the upper surface of the substrate, a first measurement laser beam having a different wavelength from the processing laser beam and a path same as the processing laser beam from a dichroic mirror provided in a path of the processing laser beam to the upper surface of the substrate and by receiving a reflected light of the first measurement laser beam; and
a separate-axis laser displacement meter configured to measure a vertical direction position of a second measurement irradiation point, which is distanced away from the processing irradiation point in a horizontal direction, by radiating, to the upper surface of the substrate, a second measurement laser beam having a different wavelength and a different path from the processing laser beam and the first measurement laser beam and by receiving a reflected light of the second measurement laser beam, and
wherein the controller selects either the coaxial laser displacement meter or the separate-axis laser displacement meter for each of the multiple dividing target lines before processing each dividing target line with the processing laser beam, and controls the vertical direction position of the condensing lens by using only one of selected meters while each of the multiple dividing target lines is processed with the processing laser beam,
wherein the separate-axis laser displacement meter obtains the vertical direction position of the processing irradiation point before a predetermined time period earlier than the coaxial laser displacement meter, and the controller controls the vertical direction position of the condensing lens based on a measurement result by the separate-axis laser displacement meter and monitors an intensity of the reflected light received by the coaxial laser displacement meter while a part of the multiple dividing target lines is processed, and
wherein when the monitored intensity of the reflected light is equal to or higher than a predetermined value, the controller performs a switchover of a laser displacement meter for controlling the vertical direction position of the condensing lens from the separate-axis laser displacement meter to the coaxial laser displacement meter, and controls a position of the condensing lens based on a measurement result by the coaxial laser displacement meter while a rest of the multiple dividing target lines is processed.

### Claim 2 (depends on 1)

The laser processing device of claim 1,
wherein the controller acquires data about a material and a film thickness of a film which forms the upper surface of the substrate,
the controller calculates a reflectivity of the first measurement laser beam reflected from the upper surface of the substrate based on the acquired data, and
the controller controls a position of the condensing lens by the coaxial laser displacement meter when an intensity of the reflected light received by the coaxial laser displacement meter is equal to or higher than a predetermined value based on the calculated reflectivity of the first measurement laser beam.

### Claim 3 (depends on 1)

The laser processing device of claim 1, further comprising:
a camera configured to detect the dividing target lines of the substrate held on the substrate holder; and
a laser light receiver configured to receive a reflected light of an inspection laser beam, having a same wavelength as the first measurement laser beam, reflected from the upper surface of the substrate and measure a reflectivity of the inspection laser beam, and
the controller controls a position of the condensing lens by the coaxial laser displacement meter when an intensity of the reflected light received by the coaxial laser displacement meter is equal to or higher than a predetermined value based on the reflectivity measured by the laser light receiver.

### Claim 4 (depends on 1)

A laser processing system, comprising:
a laser processing device of claim 1;
an alignment device configured to measure a center position of the substrate and a crystal orientation of the substrate; and
a transfer device configured to transfer the substrate from the alignment device to the laser processing device,
wherein the alignment device includes a reflectivity measurement unit configured to measure a reflectivity of an inspection laser beam having a wavelength same as the first measurement laser beam from the upper surface of the substrate, and
the controller performs the switchover based on the reflectivity measured by the reflectivity measurement unit of the alignment device.

### Claim 5

A laser processing method including measuring a vertical direction position of a processing irradiation point of a processing laser beam while moving the processing irradiation point along multiple dividing target lines on an upper surface of a substrate horizontally held; and controlling a vertical direction position of a condensing lens configured to condense the processing laser beam from above to below the processing irradiation point based on a measurement result by the measuring of the vertical direction position of the processing irradiation point, the laser processing method comprising:
selecting either a coaxial laser displacement meter or a separate-axis laser displacement meter for each of the multiple dividing target lines before processing each dividing target line with the processing laser beam, and controlling the vertical direction position of the condensing lens by using only one of selected meters while each of the multiple dividing target lines is processed with the processing laser beam, wherein the coaxial laser displacement meter is configured to measure a vertical direction position of a first measurement irradiation point, which is overlapped with the processing irradiation point in a vertical direction, by radiating, to the upper surface of the substrate, a first measurement laser beam having a different wavelength from the processing laser beam and a path same as the processing laser beam from a dichroic mirror provided in a path of the processing laser beam to the upper surface of the substrate and receiving a reflected light of the first measurement laser beam; and the separate-axis laser displacement meter is configured to measure a vertical direction position of a second measurement irradiation point, which is distanced away from the processing irradiation point in a horizontal direction, by radiating, to the upper surface of the substrate, a second measurement laser beam having a different wavelength and a different path from the processing laser beam and the first measurement laser beam and receiving a reflected light of the second measurement laser beam,
wherein the separate-axis laser displacement meter obtains the vertical direction position of the processing irradiation point before a predetermined time period earlier than the coaxial laser displacement meter, the vertical direction position of the condensing lens based on a measurement result is controlled by the separate-axis laser displacement meter and an intensity of the reflected light received by the coaxial laser displacement meter is monitored while a part of the multiple dividing target lines is processed, and
when the monitored intensity of the reflected light is equal to or higher than a predetermined value, a switchover of a laser displacement meter is performed for controlling the vertical direction position of the condensing lens from the separate-axis laser displacement meter to the coaxial laser displacement meter, and a positioning of the condensing lens is performed based on a measurement result by the coaxial laser displacement meter while a rest of the multiple dividing target lines is processed.

### Claim 6 (depends on 5)

The laser processing method of claim 5, further comprising:
acquiring, before processing the substrate, data about a material and a film thickness of a film, which forms the upper surface of the substrate;
calculating a reflectivity of the first measurement laser beam reflected from the upper surface of the substrate based on the acquired data; and
controlling a position of the condensing lens by the coaxial laser displacement meter when an intensity of the reflected light received by the coaxial laser displacement meter is equal to or higher than a predetermined value based on the calculated reflectivity of the first measurement laser beam.

### Claim 7 (depends on 5)

The laser processing method of claim 5, further comprising:
measuring, before processing the substrate, a reflectivity of an inspection laser beam having a wavelength same as the first measurement laser beam from the upper surface of the substrate; and
controlling a position of the condensing lens by the coaxial laser displacement meter when an intensity of the reflected light received by the coaxial laser displacement meter is equal to or higher than a predetermined value based on the measured reflectivity of the inspection laser beam.