JP6744624B2 - Method and apparatus for cutting tubular brittle member - Google Patents

Description

The present invention relates to a method and an apparatus for cutting a tubular brittle member such as a glass tube or a sapphire tube using a short pulse laser beam. In particular, the present invention relates to a cutting method and apparatus using a laser having a wavelength that is transparent to the material.

A laser processing technique called “stealth dicing” is used in which a substrate is irradiated with a transparent (transparent) pulsed laser beam to form an internal modified layer (see Patent Document 1). In this laser processing technology, the inside of the substrate in the region to be divided is focused and irradiated with pulsed laser light for modification, and this is continuously performed along the streets (planned dividing lines) to form the modified layer. Form. Then, it is divided by applying an external force along the modified layer whose strength has been lowered.

Further, in recent years, as a result of research and development of a short pulse laser light having a pulse width (pulse duration) of nanosecond (ns) and picosecond (ps), a burst train (burst pulse light) in which individual pulses are divided ), a laser processing technique of irradiating a short pulse laser beam called "burst mode" to internally modify the substrate is also used (see Patent Document 2).
That is, using a laser with a wavelength that is transparent to the substrate, adjust the repetition frequency and pulse width of the pulsed laser light so that it becomes a short pulsed laser light suitable for processing, and adjust the focus point inside the substrate. It is possible to form the modified layer without causing ablation by irradiating the modified layer. In this laser processing technology, short pulse laser light having an adjusted pulse width is not directly irradiated, but individual pulse is a burst pulse light (burst train) having a plurality (for example, 2 to 10) fine pulse widths. It is made to oscillate and irradiate in the state divided into.

For example, when the pulsed light generation means generates short pulsed laser light having a repetition frequency of 100 kHz (pulses are generated at a cycle of 10 μs (μs)) and a pulse width of 200 ns with pulsed light energy of 10 μJ, burst pulsed light formation means Thus, the short pulse laser light is oscillated in a state of being divided into 10 burst pulse lights (burst trains) having a fine pulse width of 1 ns. In this case, the peak power of the burst pulse light is theoretically (10 μJ/10)/1 ns=1 kW on average, but the peak powers of the burst pulse lights may be equal to each other or different from each other. (For example, the peak power of each burst pulsed light can be sequentially increased or decreased sequentially).
Then, pulse laser light having a wavelength (for example, 1064 nm) that is transparent to the silicon substrate and having a pulse width suitable for modification is oscillated as burst pulse light having a plurality of such fine pulse widths, and is condensed. The focus point of the burst pulse light is aligned with the central portion in the thickness direction of the substrate by the instrument, and the silicon substrate is irradiated in "burst mode". As a result, it is possible to suppress damage to the opposite surface by light that escapes from the laser incident surface and the opposite surface of the workpiece, and suppresses damage to the device previously formed on the opposite surface. It is disclosed that this can be done.

Further, as a processing method for cleaving a substrate using a burst train of short pulsed laser light (burst pulsed light), another document discloses a laser processing technique in which a “filament” is formed in the substrate for processing. .. That is, by irradiating a substrate with a focused laser beam focused by an objective lens, which is called a “laser filament” (hereinafter abbreviated as “filament”) having a length of hundreds of microns or millimeters, a long laser energy is accumulated. It is disclosed in Patent Document 3 that a narrow channel is formed in a substrate, and a laser beam is moved in translation to move the laser filament in a straight line or a curved line so that a filament track is cut and processed (in particular, columns 0035 and 0039). ). In this document, glass, semiconductors, transparent ceramics, polymers, transparent conductors, wide band gap glass, quartz, crystalline quartz, diamond, and sapphire are described as substrate materials to which this processing method can be applied.

Further, Patent Document 4 discloses an improved method in which the “laser filament” described in Patent Document 3 is further expanded spatially to form a spatially homogeneous filament for a long time.
According to the document, Patent Document 3 discloses that an incident laser beam composed of a burst of ultrafast pulsed laser light is focused inside a substrate by a “focusing lens”, and a filament of about several hundreds of microns can be formed inside the substrate. I am going to. Then, instead of a "focusing lens", a "dispersive focusing element" (eg, one or more lenses formed to create a divergent focus) is used so that the incident laser beam is initially focused externally. Focused on the waist (ie outside the substrate) and weakly inside the substrate to be processed (columns 0040, 0041), this distributed focusing configuration results in a "filament" with controlled shape characteristics and millimeter scale lengths. Is formed.

Japanese Patent No. 3408805 JP, 2014-104484, A Japanese Patent Publication No. 2013-536081 Japanese Unexamined Patent Application Publication No. 2015-037808

In the laser processing technology using the “filament” shown in Patent Documents 3 and 4, the substrates specifically shown as the processing targets are all flat plates. With a flat glass substrate, the filament can be easily scanned by moving the laser beam in parallel on the plane so that the filament position is at a constant depth position.
On the other hand, Patent Document 4 discloses performing complicated control by combining control of a rotary stage and a Z position when processing a material having a complicated spline surface.
By the way, in the case of a glass tube (tubular brittle member) to be processed by similar processing using a filament, in order to irradiate with the filament at a certain depth, scan the entire circumference while rotating the glass tube. There is a need to. Therefore, there is a problem that the apparatus becomes complicated and a problem such as thermal deformation easily occurs in the case of a thin and thin glass tube.

Therefore, an object of the present invention is to provide a simple method for cutting a tubular brittle member and a cutting device using a laser beam including a burst of pulsed laser light.

The method of cutting a tubular brittle member of the present invention made to achieve the above object is to generate an aberrated laser beam by transmitting a laser beam including a burst of pulsed laser light through an aberrated converging optical member that causes aberration. Then, so that the aberrated laser beam traverses a part of the peripheral surface of the tubular brittle member, scans in a direction intersecting with the axis of the tubular brittle member and partially cuts part of the peripheral surface. The tubular brittle member is divided by applying an external force along the crack.
In the dividing method of the present invention, it is preferable to perform scanning so that the most focused portion of the aberration laser beam that is most focused is located inside the tube wall of the tubular brittle member.
Here, the most converging part of the aberration laser beam is located at the position where the peak power of the beam profile becomes highest when the beam profile (intensity distribution) is measured along the irradiation direction of the aberration laser beam (irradiation of the aberration laser beam. Position along the direction).

Further, the tubular brittle member cutting device of the present invention made from another viewpoint, a stage for mounting the tubular brittle member, a laser output device for emitting a laser beam containing a burst of pulsed laser light, and the laser output. An aberrating condensing optical system that generates an aberrated laser beam from an apparatus through an aberrating condensing optical member that causes an aberration, and the aberrating laser beam intersects the axis of the tubular brittle member. From a moving mechanism that relatively moves in a direction to cause a crack that is a full cut in a part of the peripheral surface of the tubular brittle member, and a break member that divides the tubular brittle member along the crack. I am trying to.
In the disruption device of the present invention, the aforesaid focusing optical system is an optical system in which the most focused portion of the aberrated laser beam is located inside the tube wall of the tubular brittle member on the focusing optical system side. Preferably.

Since the present invention is configured as described above, a splitting crack can be formed on a part of the peripheral surface of the tubular brittle member by a single linear movement scanning (one scan). As a result, when completely splitting along the crack in the next step, this crack triggers and the crack easily progresses in the circumferential direction, and the tubular brittle member is split into round slices with a split surface with excellent end face quality. can do. In particular, since it is only necessary to form a partial crack, the rotating mechanism of the tubular brittle member is unnecessary, and the scanning time is shortened compared to the case where the entire peripheral surface is rotationally scanned, and the work efficiency can be improved. There is an effect that you can.

In the present invention, at the time of scanning the tubular brittle member, along a virtual straight line drawn in the tangential direction to the inner surface of the tubular brittle member in the vicinity of the inner surface, the most focused portion of the aberration laser beam is moved linearly. Good.
Further, in the present invention, the aberration-improving condensing optical member may be a plano-convex lens. In this case, by inputting the laser beam from the plane side of the plano-convex lens, the aberration laser beam can be emitted from the convex side.
Further, in the present invention, the tubular brittle member is a glass tube or a sapphire tube, and the laser light source of the pulsed laser light has a wavelength of 0.7 to 2.5 μm (for example, a fundamental wave of an Nd:YAG laser) in the near infrared. A burst of ultrashort pulsed laser light which is a laser and has a pulse width of 100 picoseconds or less may be used.

FIG. 3 is a block diagram showing an optical system for forming an aberrated laser beam used in the present invention. FIG. 6 is an enlarged explanatory view showing a focused state of an aberrated laser beam. The conceptual diagram which shows the profile of the burst of pulsed laser light. Explanatory drawing which shows the 1st step of crack formation in this invention. Explanatory drawing which shows the locus|trajectory range which the most converging part of an aberration laser beam passes. Sectional drawing which shows the cutting process in this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present invention, as shown in FIG. 1, a laser output device 1 emits a laser beam L1 including a burst train of pulsed laser light, and this laser beam L1 is used as an aberrated converging optical member (specifically described later). An aberrating condensing optical system that transmits the plano-convex lens 2) and generates an aberrated laser beam L2 (where the focus is dispersed) is provided.

The laser output device 1 is a laser that emits a pulsed laser beam having a pulse width (pulse duration) of 100 picoseconds or less, preferably 50 picoseconds or less (usually 1 picosecond or more), here 15 picoseconds. A light source 1a and an optical modulator 1b for emitting the pulsed laser light oscillated from the laser light source 1a as a set of divided burst trains are provided. A near infrared laser having a wavelength of 1064 nm is used as the laser light source 1a.
A laser output device 1 capable of emitting a burst train of pulsed laser light is disclosed in, for example, Japanese Patent Publication No. 2012-515450, and here, a known laser output device is used to emit a burst train of pulsed laser light. However, the detailed description is omitted.

The aberration-imparting condensing optical member used for producing the aberration in the laser beam L1 emitted from the laser output device 1 is not particularly limited, but here, the focus is dispersed in the optical axis direction and the passed laser beam is passed. A plano-convex lens 2 is used that focuses the beam L1 so as to form a blurry focal point in the axial direction to generate aberration. The laser beam L1 that has passed through the plano-convex lens 2 becomes an aberrated laser beam L2 having a dispersed focus. By inputting the laser beam L1 from the plane side of the plano-convex lens 2, the aberration laser beam L2 can be emitted from the convex side.

The aberration laser beam L2 generated from the burst train of pulsed laser light forms a narrow and long high energy distribution region F in which laser energy is accumulated by being focused by the plano-convex lens 2 as shown in FIG. 2(a). can do. A schematic enlarged view of the high energy distribution region F is shown in FIG. By forming such a high-energy distribution region F, when the surface of the object to be processed is irradiated, the object to be processed can be processed from the irradiated surface to a deep inside.

Next, a cutting processing experiment of a tubular brittle member using an aberrated laser beam according to the present invention will be described below by taking a glass tube as an example.
The conditions of the laser (burst train of pulsed laser light) used in this experiment are as follows.

Laser output: 19.4W
Repetition frequency: 32.5 kHz
Pulse width: 15 picoseconds Pulse interval (irradiation interval of irradiation spot of laser pulse on substrate): 4 μm
Burst: 4 pulses Pulse energy: 155 μJ/1 burst Scanning speed: 130 mm/s

As a result of irradiation under the above-mentioned processing conditions, it was possible to process the object to be processed from the irradiated surface to a deep inside. The processing depth and the processing state can be easily controlled by adjusting the laser output, the repetition frequency, the pulse width, the number of bursts, the pulse interval, and the aberration described above.

FIG. 3 is a schematic diagram showing a burst train of pulsed laser light. Four fine pulses P are formed by dividing each pulsed laser beam, and this is intermittently irradiated for each repetition frequency.

A method of cutting a glass tube using the laser beam thus generated will be described with reference to FIGS. As a glass tube (tubular brittle member) A to be cut, a glass tube made of soda glass and having a diameter of 11.4 mm and a thickness of 0.9 mm was used.

With respect to the glass tube A placed on the stage 3, the most converging part of the aberration laser beam L2 is scanned in a direction orthogonal to the axis of the glass tube A, and a part of the peripheral surface of the glass tube A is circled. The crack K along the direction is processed. When scanning, the most converging part is virtual along a virtual straight line B (in the present embodiment, the virtual straight line B is parallel to the stage 3) drawn tangentially to the inner surface near the inner surface of the glass tube A. The line is moved linearly while being aligned with the position of the line B. As a result, a crack K is formed on a part of the peripheral surface of the glass tube A. The crack K may be partially full-cut, but the glass tube A as a whole is not full-cut.
The "full cut" referred to here means a state in which the crack K penetrates from the outer surface of the glass tube A in the thickness direction and reaches the inner surface.

The scanning of the glass tube A with the aberration laser beam L2 can be performed by relatively moving the aberration laser beam L2 or the stage 3 via a moving mechanism (not shown).

The position of the virtual straight line B, which is the locus of passage of the most converging portion, is expressed as "in the vicinity of the inner surface" of the glass tube A, but "the vicinity of the inner surface" in the present invention includes the positions shown in FIG. A space S from a position in contact with the inner surface of the glass tube A as shown in FIG. 5 to a position separated in the tube wall by about 1/5 of the tube wall thickness is included.
When the most converging part of the aberration laser beam L2 is aligned and scanned on the tangent line of the inner surface of the glass tube A or slightly above the tangent line, the external force required for the division in the next step becomes the smallest and can be easily obtained. I was able to divide it. In the experiment conducted by the inventor, it was confirmed that the scan position of the most converging part has a difference in the state of the sectional surface from the other part.

After processing the crack K in the glass tube A as described above, the glass tube A is moved to a position where the crack K to be divided protrudes from the end of the stage 3 as shown in FIG. The glass tube A is separated from the crack K by pressing the break member 5 while bending the glass tube A while holding the glass tube A with the pressing member 4. At this time, since the crack K penetrates in the thickness direction at the uppermost portion and is fully cut, the crack K triggers by bending and the crack easily propagates to both sides in the circumferential direction, so that the glass tube A can be cut into a round slice shape. Can be divided by.
In this embodiment, it was confirmed that a glass tube having a diameter of 5 to 100 mm and a thickness of 0.3 to 2 mm can be divided without any problem.
The breaking member 5 may be configured such that a chuck member grips the end of the glass tube A and bends it downward.

Although the representative embodiments of the present invention have been described above, the present invention is not necessarily limited to only the above-mentioned embodiments, achieves the object thereof, and appropriately modifies within the scope not departing from the claims and It is possible to change.
For example, although the glass tube has been described as an example in the above embodiment, when a near-infrared laser light source of 1064 nm is used, the sapphire tube can be similarly divided. Further, according to the material of the object to be processed, the present invention can be applied to materials other than these materials by using a laser light source having a transparency to the material.

INDUSTRIAL APPLICABILITY The present invention can be used when cutting a tubular brittle member such as a glass tube.

A glass tube (tubular brittle member)
B Virtual straight line F High energy distribution region K Crack L1 Laser beam L2 Aberration laser beam 1 Laser output device 2 Plano-convex lens (Aberration focusing optical member)
3 Stage 4 Holding member 5 Breaking member

Claims (5)

A method for cutting a tubular brittle member,
A laser beam containing a burst of pulsed laser light is transmitted through an aberrated converging optical member that produces aberration, and an aberrated laser beam is generated.
As the aberrated laser beam traverses a part of the circumferential surface of the tubular brittle member, a crack that scans in a direction intersecting the axial center of the tubular brittle member and partially cuts the circumferential surface partially Causes
A method for dividing a tubular brittle member, which divides the tubular brittle member by applying an external force along the crack. When scanning the tubular brittle member, the most converging part of the aberrated laser beam is linearly moved along an imaginary straight line drawn tangentially to the inner surface near the inner surface of the tubular brittle member. The method for dividing the tubular brittle member described. The method for dividing a tubular brittle member according to claim 1 or 2, wherein the aberration-improving condensing optical member is a plano-convex lens. The tubular brittle member is a glass tube or a sapphire tube, the laser light source of the pulsed laser light is a near-infrared laser having a wavelength of 0.7 to 2.5 μm, and the pulse width is an ultrashort pulse of 100 picoseconds or less. The method for dividing a tubular brittle member according to claim 1, wherein a burst of laser light is used. A stage for mounting the tubular brittle member,
A laser output device that emits a laser beam containing a burst of pulsed laser light,
An aberrating condensing optical system that generates an aberrated laser beam from a laser beam from the laser output device via an aberrating condensing optical member that causes an aberration;
A moving mechanism that relatively moves the aberrated laser beam in a direction intersecting with the axis of the tubular brittle member to cause a crack, which is a partial full cut, in a part of the peripheral surface of the tubular brittle member,
A device for cutting a tubular brittle member, which comprises a break member that divides the tubular brittle member along the crack.

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