Laser working method, laser working apparatus, and its manufacturing method

Patent metadata

Field	Value
Publication number	US-9428413-B2
Application number	US-201213362781-A
Country	US
Kind code	B2
Filing date	Jan 31, 2012
Priority date	Aug 3, 2007
Publication date	Aug 30, 2016
Grant date	Aug 30, 2016

Abstract

An object is irradiated with a laser light modulated by a reflection type spatial light modulator such that aberration of the laser light converged inside the object becomes a predetermined aberration or less. Therefore, aberration of the laser light generated at a position on which a converging point of the laser light is located is made as small as possible, to enhance the energy density of the laser light at that position, which makes it possible to form a modified region with a high function as a starting point for cutting. In addition, because the reflection type spatial light modulator is used, it is possible to improve the utilization efficiency of the laser light as compared with a transmissive type spatial light modulator.

First claim

The invention claimed is:

1. A manufacturing method of a laser working apparatus which includes a supporting base supporting a plate-shaped object to be processed, a laser light source emitting a laser,light, a reflection spatial light modulator modulating the laser light emitted from the laser light source, a converging optical system converging the laser light modulated by the reflection spatial light modulator, inside the object supported by the supporting base, and a controller controlling the reflection spatial light modulator, and that irradiates the object with the laser light while locating a converging point within the object, so as to form a modified region serving as a starting point for cutting along a line to cut the object, the manufacturing method of the laser working apparatus comprising the steps of:
preparing a laser working apparatus and acquiring standard wavefront data by measuring a wavefront of first laser light emitted from a converging optical system of the laser working apparatus;
acquiring wavefront data by measuring a wavefront of second laser light emitted from the converging optical system; and
calculating a control signal for controlling the reflection spatial light modulator such that the wavefront of the second laser light becomes the wavefront of the first laser light on the basis of the standard wavefront data and the wavefront data acquired by measuring a wavefront of the laser light, to store the control signal in the controller.

2. A laser working method including the steps of:
irradiating a plate-shaped object to be processed with a laser light; and
locating a converging point of the laser light within the object so as to form a modified region serving as a starting point for cutting along a line to cut the object, wherein
a reflection spatial light modulator, which modulates the laser light, a converging optical system, which converges the laser light modulated by the reflection spatial light modulator inside the object, and an adjustment optical system, which has a first optical element and a second optical element functioning as lenses and located on the optical path between the reflection spatial light modulator and the converging optical system are prepared,
disposing the first optical element and the second optical element so as to matching the wavefront form at the reflection spatial light modulator to the wavefront form at the converging optical system, and the first optical element and the second optical element become a double telecentric optical system,
at the time of forming the modified region, the laser light is modulated by a reflection spatial light modulator such that aberration of the laser light occurs at a position on which a converging point of the laser light is located inside the object becomes a predetermined aberration or less.

3. The laser working method according to claim 2 , wherein
the first optical element and second optical element are disposed such that a distance between the reflection spatial light modulator and the first optical element becomes the first focal distance of the first optical element, a distance between the converging optical system and the second optical element becomes the second focal distance of the second optical element, and a distance between the first optical element the second optical element becomes the sum of the first focal distance and the second focal distance,
which forms modified regions in a plurality of lines so as to line up in the thickness direction of the object along the line to cut of the object, wherein at the time of forming the modified regions in one line or a plurality of lines including a modified region farthest from a laser light entrance surface of the object among the modified regions in a plurality of lines, modifies the distance between the convergence optical system and the object so that the distance between the convergence optical system that converges the laser light inside the object and the object becomes a predetermined distance, in accordance with the modified region to be formed.

4. The laser working method according to claim 3 , wherein
in the case in which the plurality of lines are set with respect to the object, the modified regions are formed in a plurality of lines along another one of the lines after forming the modified regions in a plurality of lines along one of the lines.

5. The laser working method according to claim 3 , wherein
in which the plurality of lines are set with respect to the object, the modified regions are formed in another one line along the plurality of lines after forming the modified regions in one line along the plurality of lines.

6. A laser working method comprising the steps of:
irradiating a plate-shaped object to be processed with a laser light; and
locating a converging point of the laser light within the object so as to form a modified region serving as a starting point for cutting along a line to cut the object, wherein
a reflection spatial light modulator, which modulates the laser light, converging optical system, which converges the laser light modulated by the reflection spatial light modulator inside the object, and an adjustment optical system, which has a first optical element and a second optical element functioning as lenses and located on the optical path between the reflection spatial light modulator and the converging optical system are prepared,
disposing the first optical element and the second optical element so as to matching the wavefront form at the reflection spatial light modulator to the wavefront form at the converging optical system ,and the first optical element and the second optical element become a double telecentric optical system,
at the time of forming the modified region, the laser light is modulated by a reflection spatial light modulator such that a wavefront of the laser light becomes a predetermined wavefront inside the object.

7. The laser working method according to claim 6 , wherein
the first optical element and second optical element are disposed such that a distance between the reflection spatial light modulator and the first optical element becomes the first focal distance of the first optical element, a distance between the converging optical system and the second optical element becomes the second focal distance of the second optical element, and a distance between the first optical element the second optical element becomes the sum of the first focal distance and the second focal distance,
which forms modified regions in a plurality of lines so as to line up in the thickness direction of the object along the line to cut of the object, wherein at the time of forming the modified regions in one line or a plurality of lines including a modified region farthest from a laser light entrance surface of the object among the modified regions in a plurality of lines, modifies the distance between the convergence optical system and the object so that the distance between the convergence optical system that converges the laser light inside the object and the object becomes a predetermined distance, in accordance with the modified region to be formed.

8. The laser working method according to claim 7 , wherein
in the case in which the plurality of lines are set with respect to the object, the modified regions are formed in a plurality of lines along another one of the lines after forming the modified regions in a plurality of lines along one of the lines.

9. The laser working method according to claim 7 , wherein
in the case in which the plurality of lines are set with respect to the object, the modified regions are formed in another one line along the plurality of lines after forming the modified region in one line along the

Assignees

• Nakano Makoto
• Kuno Koji
• Osajima Tetsuya
• Inoue Takashi
• Kumagai Masayoshi
• Hamamatsu Photonics Kk

Inventors

• Nakano Makoto
• Kuno Koji
• Osajima Tetsuya
• Inoue Takashi
• Kumagai Masayoshi

Classifications

• H10W46/501

  for use before dicing · CPC title

• H10W46/00

  Marks applied to devices, e.g. for alignment or identification · CPC title

• H10P54/00 Primary

  Cutting or separating of wafers, substrates or parts of devices · CPC title

• B23K2101/40

  Semiconductor devices · CPC title

• B28D5/00

  Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor (working by grinding or polishing B24; for artistic purposes B44B) · CPC title