JP6698453B2 - Wavelength converter - Google Patents

Description

  The present invention relates to a wavelength conversion device that converts the wavelength of a pulsed laser beam.

  A wafer formed on the surface by dividing a plurality of devices such as ICs and LSIs by planned dividing lines is irradiated with a laser beam on the planned dividing lines by a laser processing device and divided into individual devices, and electrical equipment such as mobile phones and personal computers. Used for.

  The laser processing apparatus comprises at least holding means for holding a work piece, and laser beam irradiation means for irradiating the work piece with a laser beam which is held by the holding means, and the laser beam irradiation means processes the work piece. A laser beam oscillator that oscillates a laser beam having a wavelength to be applied, a condenser that condenses the laser beam oscillated by the laser beam oscillator, and irradiates the workpiece held by the holding means with the laser beam, the laser beam oscillator, and the condensing unit. And an optical system such as an attenuator for adjusting the output of the laser beam and a beam expander for adjusting the beam diameter, which are arranged between the device and the device, and can perform desired processing on the workpiece (for example, patent See Reference 1.).

Also, when the wavelength of the laser beam emitted by the laser beam oscillator is as short as 355 nm and 266 nm, the optical system is damaged in a relatively short time and the optical system must be replaced frequently, which is uneconomical. There is a problem. In order to solve such a problem, the wavelength of the laser beam oscillated by the laser beam oscillator is set to a relatively long wavelength of, for example, 1064 nm, and a nonlinear optical crystal (for example, LBO:LiB ₃ O ₅ lithium is provided in front of the condenser. A technique for converting a laser beam having a short wavelength such as 355 nm by a wavelength converting means including triborate (for example, see Patent Document 2).

JP, 2006-108478, A JP, 2013-193090, A

  However, when a fiber laser is used as the oscillation source of the laser beam, the peak power of the laser beam is high, and a phenomenon in which the phase is shifted due to the self-phase modulation (Self Phase Modulation: SPM) effect occurs, and the spectrum width is increased. It will spread. If the spectrum width is widened in this way, when the wavelength is converted by a wavelength conversion means such as a non-linear optical crystal, for example, if the wavelength of 1064 nm is converted into a laser beam of 355 nm, the conversion efficiency becomes poor. ..

  The present invention has been made in view of the above facts, and a main technical problem thereof is to provide a wavelength conversion device capable of efficiently performing wavelength conversion when performing wavelength conversion of a pulsed laser beam having a wide spectrum width by wavelength conversion means. is there.

  In order to solve the above-mentioned main technical problems, according to the present invention, there is provided a wavelength conversion device for converting the wavelength of a pulsed laser beam, wherein an oscillator for oscillating a pulsed laser beam and a spectrum width of the pulsed laser beam oscillated by the oscillator are selected. Wavelength selecting means for selecting pulsed laser beams of at least two kinds of wavelengths, and a delay time is given to at least one of the pulsed laser beams of the selected wavelengths so that the selected at least two kinds of pulsed laser beams are timed. Delay time generating means for generating an interval, energy amplifying means for amplifying each energy of the pulsed laser beam generated for the time interval, and pulse of at least two kinds of wavelengths amplified by correcting the delay time There is provided a wavelength conversion device including at least a delay time correction unit that makes the laser beams travel the same and a wavelength conversion unit that converts the wavelengths of at least two types of pulsed laser beams that travel at the same time.

  The oscillator oscillates a pulsed laser beam having a spectral width with a wavelength of 1064 nm as an apex, the wavelength selection unit selects two types of pulsed laser beams of wavelengths close to 1064 nm, and the wavelength conversion unit outputs a pulse of 532 nm wavelength. It can be configured to generate a laser beam.

  The wavelength conversion device further includes a wavelength separation means and a wavelength synthesis means, the delay time correction means includes a first delay time correction means and a second delay time correction means, and the wavelength conversion means. The means includes a first wavelength converting means and a second wavelength converting means, the oscillator oscillates a pulsed laser beam having a spectral width having a wavelength of 1064 nm as an apex, and the wavelength selecting means is close to 1064 nm. Pulse laser beams of three types of wavelengths are selected and output, and the delay time generation means gives a delay time to the pulse laser beams of at least two types of the pulse laser beams of the three types of wavelengths to generate the pulse laser beams of the three types. At a time interval, the energy of the three types of pulse laser beams is amplified by the energy amplifying means, and the pulse laser beams of the three types of wavelengths, each energy of which has been amplified, are converted into two pulse laser beams by the wavelength separating means. And one pulsed laser beam, and the two pulsed laser beams are guided to a first delay time correction means which constitutes the delay time correction means and a first wavelength conversion means which constitutes the wavelength conversion means. The pulse laser beam having a wavelength of 532 nm is converted to the wavelength synthesizing unit, and the one pulse laser beam is guided to the second delay time correcting unit and the wavelength synthesizing unit that form the delay time correcting unit, and the delay is generated. The pulse laser beam synthesized by the wavelength synthesizing means is made uniform by the action of the time correcting means, and is converted into a pulse laser beam having a wavelength of 355 nm by the second wavelength converting means constituting the wavelength converting means. it can.

  In the wavelength converter of the present invention, an oscillator that oscillates a pulse laser beam, a wavelength selection unit that selects a pulse laser beam having at least two kinds of wavelengths from the spectral width of the pulse laser beam oscillated by the oscillator, and the selected wavelength Of the pulsed laser beams of (1), a delay time generation means for giving a delay time to at least one of the pulsed laser beams to generate a time interval between the selected at least two types of pulsed laser beams, and the pulse generated with the time interval Energy amplification means for amplifying the energy of each laser beam, delay time correction means for correcting the delay time so as to make the progress of the amplified pulse laser beams of at least two kinds of wavelengths the same, and at least two kinds of laser waves that simultaneously advance Wavelength conversion means for converting the wavelength of the pulsed laser beam of the wavelength, at least, by the laser beam oscillator, even if a pulsed laser beam having a wide spectrum width is oscillated, the spectral width of the pulsed laser beam guided to the wavelength conversion means Can be narrowed, and the effect of improving the conversion effect of the wavelength conversion means is exerted.

It is the whole laser processing device perspective view provided with the wavelength conversion device constituted based on the present invention. It is a block diagram for explaining an outline of an embodiment of a wavelength conversion device of the present invention. It is a block diagram for explaining the outline of other embodiments of a wavelength conversion device of the present invention.

  Hereinafter, embodiments of a wavelength conversion device according to the present invention will be described in more detail with reference to the accompanying drawings.

  FIG. 1 shows an overall perspective view of a laser processing apparatus 40 exemplified as a processing apparatus equipped with the wavelength conversion device of the present invention. The laser processing apparatus 40 shown in the figure includes a base 41, a holding means 42 for holding the wafer 10 held by an annular frame F via an adhesive tape T, and a moving means 43 for moving the holding means 42. And a laser beam irradiation mechanism 44 for irradiating the workpiece held by the holding means 42 with a laser beam.

  The holding means 42 is a rectangular X-direction movable plate 60 mounted on the base 41 so as to be movable in the X direction indicated by the arrow X in the figure, and is movable in the Y direction indicated by the arrow Y in the figure in the X direction. A rectangular Y-direction movable plate 61 mounted on the movable plate 60, a cylindrical support 62 fixed to the upper surface of the Y-direction movable plate 61, and a rectangular cover plate 63 fixed to the upper end of the support 62. including. On the upper surface of the cover plate 63, which holds a circular work piece extending upward through an elongated hole formed on the cover plate 63, an upper surface of a holding table 64 is formed of a porous material and extends substantially horizontally. An existing circular suction chuck 65 is arranged. The suction chuck 65 is connected to a suction unit (not shown) by a flow path passing through the support column 62. The X direction is the direction indicated by arrow X in FIG. 1, and the Y direction is the direction indicated by arrow Y in FIG. 2 and is a direction orthogonal to the X direction. The plane defined by the X and Y directions is substantially horizontal.

  The moving means 43 includes an X-direction moving means 80 and a Y-direction moving means 82. The X-direction moving means 80 converts the rotational motion of the motor into a linear motion and transmits the linear motion to the X-direction movable plate 60, and the X-direction movable plate 60 moves along the guide rail on the base 41. Move back and forth in the X direction. The Y-direction moving means 82 converts the rotational motion of the motor into a linear motion, transmits it to the Y-direction movable plate 61, and moves the Y-direction movable plate 61 forward and backward along the guide rail on the X-direction movable plate 60. . Although not shown, the X-direction moving means 80 and the Y-direction moving means 82 are respectively provided with position detecting means, and the X-direction position, the Y-direction position, and the circumferential direction of the holding table 64 are arranged. The rotational position is accurately detected, and the X-direction moving means 80 and the Y-direction moving means 82 are driven based on a signal instructed by the control means described later to accurately position the holding table 64 at an arbitrary position and angle. It is possible.

  As shown in FIG. 2, the laser beam irradiation mechanism 44 includes a condenser 44a for condensing and irradiating a workpiece with a pulsed laser beam, an oscillator 44b for oscillating the pulsed laser beam, and the pulsed laser beam oscillated from the oscillator 44b. At least a wavelength conversion device 50 including a wavelength conversion unit 44c that converts the wavelength of Although not shown in the figure, the laser beam irradiation mechanism 44 includes a reflection mirror for deflecting the optical path, an attenuator for adjusting the output, and a processing mark on the wafer 10 on the suction chuck 65. It is possible to further include various devices such as an image pickup unit for performing the operation, and it is possible to include a configuration other than that illustrated.

  The oscillator 44b that oscillates a pulse laser beam is a fiber laser oscillator that oscillates a pulse laser beam having a wavelength having a peak at 1064 nm. As shown in FIG. 2, the pulse laser beam λ emitted from the oscillator 44b has a wavelength (w) on the horizontal axis and a spectral density on the vertical axis, and its distribution is represented by 1062 nm to 1066 nm due to the effect of the self-phase modulation effect. Has a spectral width including the wavelength of

  The wavelength conversion unit 44c includes at least a wavelength selection unit 441 for selecting two wavelengths, a delay time generation unit 442, an energy amplification unit 443, a delay time correction unit 444, and a wavelength conversion unit 445. Explained.

  The pulse laser beam λ having the spectral width of 1062 nm to 1066 nm wavelength oscillated by the oscillator 44b is made incident on the wavelength selecting means 441. The wavelength selecting means 441 is composed of an optical filter which selectively separates the incident pulse laser beam λ into a pulse laser beam λ1 having a wavelength of 1062 nm and a pulse laser beam λ2 having a wavelength of 1066 nm and emits them.

  Next, the pulse laser beams λ1 and λ2 output from the wavelength selecting unit 441 are incident on the delay time generating unit 442. The delay time generation means 442 is formed by, for example, a volume Bragg grating (VBG), a fiber Bragg grating (FBG), or other general diffraction grating, and the passage time of at least one of them, for example, a pulse laser beam λ2. Is set substantially longer so that the pulse laser beam λ1 has a predetermined delay time. Then, by generating the delay time, a time interval based on a predetermined delay time is generated between the pulse laser beam λ1 and the pulse laser beam λ2, and the pulse laser beam λ1 and the pulse laser beam λ2 are generated from the delay time generating means 442. Emit.

  Next, the pulse laser beams λ1 and λ2 emitted from the delay time generating means 442 are incident on the energy amplifying means 443, and their outputs (pulse energy) are amplified and emitted.

  The pulse laser beams λ1 and λ2 whose outputs are amplified by the energy amplifying means 443 are incident on the delay time correcting means 444. The pulse laser beams λ1 and λ2 incident on the delay time correcting means 444 are advanced by the action of the delay time generating means 442 described above so that the pulse laser beam λ2 advances with a predetermined delay time with respect to the pulse laser beam λ1. Time intervals are created by minutes. Therefore, the delay time correction means 444 is provided with a configuration for delaying the pulse laser beam λ1 traveling forward by the predetermined time, and eliminating the time interval between the two pulse laser beams λ1 and λ2 incident at a time interval, The pulsed laser beams λ1 and λ2 of the two wavelengths are output as a pulsed laser beam λ3 that has the same progress. The configuration for generating the delay time for the pulse laser beam λ1 and eliminating the time interval is substantially the same as the configuration for generating the delay time for the pulse laser beam λ2 in the delay time generating means 442 (delaying). Since only the wavelength of the pulsed laser beam is different), its detailed description is omitted.

The pulsed laser beam λ3 emitted from the delay time correction means 444 is incident on the wavelength conversion means 445. As the wavelength conversion means 445, a generally known nonlinear optical crystal (for example, LBO:LiB ₃ O ₅ lithium triborate) can be adopted. Then, the pulse laser beam λ3 incident on the wavelength conversion means 445 is converted into a pulse laser beam having a wavelength of 532 nm and emitted. As described above, the wavelength conversion unit 44c performs wavelength conversion on the pulsed laser beam λ oscillated from the oscillator 44b.

  According to the wavelength conversion device 50 configured according to the present invention, for example, even in the case of converting the wavelength of a pulse laser beam whose spectrum width has spread in a fiber laser oscillator, the pulse laser beams of two types of wavelengths are spectral lines. Selective extraction as narrow seed light. Then, a delay time is generated for at least one of them to generate a time interval, and then the output of each pulsed laser beam is amplified, and after the amplification, the delay time is generated. After the time interval is eliminated and the two types of pulsed laser beams travel the same, wavelength conversion is performed by the wavelength conversion means. As a result, high wavelength conversion efficiency is realized, and processing efficiency when performing laser processing can be improved.

  In the wavelength selecting means 441 described above, a pulse laser beam having a wavelength of 1062 nm and a pulse laser beam having a wavelength of 1066 nm are selectively extracted from the pulse laser beam oscillated from the oscillator 44b, but a combination of two types of wavelengths to be selected. Is not limited to this. For example, a pulse laser beam having a wavelength of 1063 nm and a pulse laser beam having a wavelength of 1065 nm may be selected, and the pulse laser beam λ emitted from the oscillator 44b has a spectral width of 2 Any combination of wavelengths may be used as long as pulse lasers having different wavelengths are selected.

  Another embodiment of the wavelength conversion device of the present invention will be described with reference to FIG. The laser beam irradiation mechanism 44 shown in FIG. 3 also has an oscillator 44b that oscillates a pulse laser beam having a spectral width of 1062 nm to 1066 nm with a peak at 1064 nm and a wavelength conversion unit 44c′, as in the embodiment described in FIG. And the point that the light collector 44a is configured. Further, in comparison with the above-described embodiment of FIG. 2, the two are different in that the incident pulse laser beam λ is converted into a pulse laser beam having a wavelength of 355 nm and emitted in the wavelength conversion unit 44c′. The differences will be mainly described.

  The wavelength conversion unit 44c' selects a wavelength selection unit 461 for selecting three wavelengths, a delay time generation unit 462, an energy amplification unit 463, a wavelength separation unit 464, a first delay time correction unit 465, and a first wavelength conversion unit 466. , The second delay time correction means 467, the wavelength synthesis means 468, and the second wavelength conversion means, and the operation of the wavelength conversion unit 44c' will be described below.

  The pulsed laser beam λ having a spectral width of 1062 nm to 1066 nm oscillated by the oscillator 44 b is first made incident on the wavelength selection means 461. The wavelength selecting means 461 selectively separates the pulsed laser beam λ1 having a wavelength of 1062 nm and the pulsed laser beam λ2 having a wavelength of 1066 nm from the incident pulsed laser beam λ and selectively separating the pulsed laser beam λ4 having a wavelength of 1064 nm. To do.

  The pulse laser beams λ1, λ2, and λ4 selected by the wavelength selection unit 461 are incident on the delay time generation unit 462, and a delay time of at least two types of pulse laser beams (in this embodiment, the pulse laser beams λ1 and λ2) is delayed by a predetermined time. And pulse laser beams λ4, λ1 and λ2 are emitted in this order at the same time intervals. Then, the pulse laser beams λ4, λ1, and λ2 provided with the time intervals are incident on the energy amplifying means 463.

  The pulsed laser beams λ4, λ1, and λ2 that have entered the energy amplification means 463 have their respective energy amplified and emitted, and then enter the wavelength separation means 464. The wavelength separating means 464 can have the same configuration as the wavelength selecting means 461, and is composed of an optical filter that transmits the wavelengths of the pulse laser beams λ1 and λ2, and an optical filter that branches the wavelength of the pulse laser beam λ4. The laser beams λ1 and λ2 and the pulsed laser beam λ4 are emitted to different optical paths.

  The pulse laser beams λ1 and λ2 separated by the wavelength separation means 464 are sent to the first delay time correction means 465 at the time intervals given by the delay time generation means 462, and by the action of the first delay time correction means 465. , The preceding pulsed laser beam λ1 is given a delay time by a predetermined time, so that the time interval is canceled and the pulsed laser beam λ2 is combined so as to have the same progress.

  The pulse laser beams λ1 and λ2 synthesized so that the delay time is eliminated by the first delay time correction means 465 and proceed at the same time are incident on the first wavelength conversion means 466, converted into a pulse laser beam λ3 having a wavelength of 532 nm, and emitted. To be done. The first delay time correction means 465 and the first wavelength conversion means 466 of this embodiment have exactly the same configuration as the delay time correction means 444 and the wavelength conversion means 445 of the embodiment shown in FIG. 2 described above. be able to.

  The other pulsed laser beam λ4 separated by the wavelength separation means 464 is incident on the second delay time correction means 467. The second delay time correction means 467 causes the incident pulse laser beam λ4 to travel the same way as the pulse laser beam λ3 synthesized in a later step through another optical path, that is, to generate the delay time first. The delay time given to the pulsed laser beam λ2 is corrected in the means 462, and is adjusted so that the time interval for the pulsed laser beam λ3 does not occur when combined in the subsequent step.

  The pulse laser beam λ3 converted into the pulse laser beam with the wavelength of 532 nm and the pulse laser beam λ4 with the delay time of 1064 nm are incident on the wavelength synthesizing means 468 and are synthesized. As the wavelength synthesizing unit 468, an optical unit that transmits only a specific wavelength and reflects light rays of other wavelengths can be adopted. By using such a wavelength synthesizing means 468, the pulse laser beam λ4 having a wavelength of 1064 nm is transmitted, and the pulse laser beam λ3 having a wavelength of 532 nm converted by the wavelength converting means 467 is reflected so that the optical paths are matched and the pulse laser beams λ3 and λ4. Are combined and emitted.

The pulse laser beams λ3 and λ4 synthesized by the wavelength synthesizing unit 468 are incident on the second wavelength converting unit 469 and emit the pulse laser beam λ5 having a wavelength of 355 nm. The second wavelength conversion means 469 is made of a non-linear crystal that can obtain a laser beam having a wavelength of 355 nm by injecting pulsed laser beams having two types of wavelengths (532 nm and 1064 nm). For example, LBO:LiB ₃ O ₅ Lithium triborate) can be adopted. The LBO is a non-linear crystal made of the same material as the first wavelength converting means, but the crystal axis direction of the LBO is different from that of the LBO of the first wavelength converting means, and the LBO is produced according to the wavelength to be converted. There is.

  The wavelength conversion unit 44c′ in the present embodiment is configured as described above, and the pulse laser beam λ having a wide spectrum width oscillated by the oscillator 44b is efficiently converted into the pulse laser beam λ5 having the wavelength of 355 nm, and the condenser 44a is generated. The wafer 10 which is the object to be processed is irradiated with the light.

10: Wafer 40: Laser processing device 41: Base 42: Holding means 43: Moving means 44: Laser beam irradiation mechanism 44a: Condenser 44b: Oscillators 44c, 44c': Wavelength converters 441, 461: Wavelength selecting means 442, 462: delay time generation means 443, 463: energy amplification means 444: delay time correction means 445: wavelength conversion means 464: wavelength separation means 465: first delay time correction means 466: first wavelength conversion means 467: second Delay time correcting means 468: wavelength combining means 469: second wavelength converting means

Claims (3)

A wavelength conversion device for converting the wavelength of a pulsed laser beam,
At least one of an oscillator that oscillates a pulse laser beam, a wavelength selection unit that selects a pulse laser beam having at least two kinds of wavelengths from the spectral width of the pulse laser beam oscillated by the oscillator, and a pulse laser beam having the selected wavelength. Delay time generating means for giving a delay time to the pulsed laser beam to generate a time interval between the selected at least two types of pulsed laser beams, and energy for amplifying each energy of the pulsed laser beam generated at the time interval The amplifying means, the delay time correcting means for correcting the delay time so as to make the amplified pulse laser beams of at least two kinds of wavelengths have the same progress, and the wavelengths of the pulse laser beams of at least two kinds of wavelengths that simultaneously proceed are converted. A wavelength conversion device comprising at least wavelength conversion means.   The oscillator oscillates a pulsed laser beam having a spectral width with a wavelength of 1064 nm as an apex, the wavelength selection unit selects two types of pulsed laser beams of wavelengths close to 1064 nm, and the wavelength conversion unit outputs a pulse of 532 nm wavelength. The wavelength conversion device according to claim 1, which generates a laser beam. The wavelength conversion device according to claim 1, wherein
Furthermore, it includes a wavelength separating means and a wavelength synthesizing means,
The delay time correction means includes a first delay time correction means and a second delay time correction means,
The wavelength conversion means includes a first wavelength conversion means and a second wavelength conversion means,
The oscillator oscillates a pulse laser beam having a spectrum width having a peak of 1064 nm, the wavelength selecting means selects and outputs pulse laser beams of three kinds of wavelengths close to 1064 nm, and the delay time generating means A delay time is given to the pulse laser beams of at least two types of the pulse laser beams of the three types of wavelengths to generate a time interval between the pulse laser beams of the three types, and the energy of the three types of pulse laser beams is increased by the energy amplification means. Amplified,
The pulse laser beams of the three kinds of wavelengths, each of which energy is amplified, are separated into two pulse laser beams and one pulse laser beam by the wavelength separating means, and the two pulse laser beams constitute the delay time correcting means. And a first delay time correcting means for converting the pulse laser beam having a wavelength of 532 nm to the wavelength synthesizing means, which is guided to the first wavelength converting means constituting the wavelength converting means.
The one pulsed laser beam is guided to the second delay time correcting means and the wavelength synthesizing means constituting the delay time correcting means, and the progress of the pulse laser light is made the same by the action of the delay time correcting means. A wavelength conversion device in which the combined pulse laser beam is converted into a pulse laser beam having a wavelength of 355 nm by a second wavelength conversion unit that constitutes the wavelength conversion unit.