JP2006061954A - Substrate working device and substrate working method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate working device and a substrate working method for forming a scribe line to stably divide a substrate. <P>SOLUTION: Laser beams emitted from a laser beam source 2 are parallelized by a beam shaping optical system 3, and the power of the laser beams is regulated. The deflection direction is regulated by a 1/2 wavelength plate 4, and the laser beams are condensed on a substrate 7 by a condensing optical system 5. By condensing the laser beams on the substrate 7, multiple photon absorption occurs inside the substrate 7, and glass in the ionized zone formed by the multiple photon absorption is sublimed. Since the substrate 7 is relatively moved to the laser beams by an XY-stage 8, a sublimed portion forming a groove forms a scribe line. The rotation of the 1/2 wavelength plate 4 is controlled so that the deflection direction of the laser beams becomes constant in the laser beam moving direction with respect to the substrate 7. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a substrate processing apparatus and a substrate processing method used for cutting a substrate such as a glass substrate, a semiconductor substrate, and a piezoelectric material substrate.

Liquid crystal display devices, organic EL (electroluminescence) display devices, and the like are manufactured by forming TFTs (Thin Film Transistors) on a substrate typified by glass. In this production, a display device for a plurality of panels is formed from a large glass in order to increase efficiency, and then the panels are divided and taken out. For example, from a fourth generation (730 × 920 mm ² ) glass substrate, four 19-inch panels and six 17-inch panels can be produced. As the size of the glass substrate increases, more panels can be taken out from one glass substrate, and the productivity increases, while the yield of the dividing step becomes important.

  There are two stages of dividing the glass, and the first is a process of forming scratches on the glass, and this process is called scribing. The ruled line is called a scribe line. The second is a process of applying a force to the glass so that the glass breaks along the scribe line, and this process is called a break. The present invention relates to scribing.

  In many cases of scribing, a method of directly pressing a diamond blade against a glass substrate is used. In this method, an excessive force is applied to the glass substrate, so that unexpected cracks and chipping are likely to occur, and empirical intuition is required to adjust the pressure when pressing the blade and the feed rate of the substrate. Further, since the blade becomes weaker as the diamond blade is used, periodic replacement is necessary. Since the above-mentioned adjustment level varies from blade to blade, after blade replacement, adjustments corresponding to the blade must be performed, leading to a reduction in productivity.

  In view of the above, a non-contact scribing technique using laser light has been developed. Most of the light sources have a wavelength of 1 μm or more. Since glass absorbs light in this wavelength range well, stress is generated by the generated heat. Immediately after this, when a coolant such as water is sprayed and rapidly cooled, a crack occurs in the glass thickness direction. In this method, since the thermal stress is used, the position control is not easy. Furthermore, there is a problem in that a notch or a quenching refrigerant that is a base point for generating cracks is necessary and the glass substrate is contaminated because it is not a complete non-contact process.

On the other hand, a scribing technique using multiphoton absorption has also been proposed (see Patent Document 1). According to Patent Document 1, when laser light is oscillated with a pulse having a length of 1 microsecond or less and condensed so that the irradiation light density is 1 × 10 ⁸ (W / cm ² ) or more, multiphoton absorption is achieved. Modification of the glass by ionization takes place, and it becomes possible to cleave from that point. In this case, since the contact is completely non-contact, the above problem can be avoided. Multiphoton absorption occurs even in laser light in the ultraviolet region that is transparent to the glass. In this case, only the portion of the glass where ionization has occurred absorbs the wavelength in the ultraviolet region. Sublimates to form grooves. Such a phenomenon also occurs for non-metallic substrates other than glass.
Japanese Patent No. 3408805

  The depth of the range ionized by multiphoton absorption is more advantageous for cleaving as much as possible. Ideally, ionization can be performed for the thickness of the glass substrate, but in practice, the limit is about 100 μm. When the traveling speed of the glass substrate is increased in order to obtain the scribe speed, this depth is rapidly reduced. At this time, increasing the laser power density to obtain depth is known to cause the glass surface to be heated rapidly, resulting in unexpected cracking and a low effect of increasing the scribe speed. It was difficult to draw.

  In addition, a phenomenon that the groove depth of the scribe line changes depending on the scribe direction has narrowed the allowable range of the break condition. That is, if the scribe line has a variation in groove depth, cracks, chips, and the like that are removed from the scribe line are likely to occur.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a substrate processing apparatus and a substrate processing method capable of forming a scribe line for stably dividing a substrate.

  In order to achieve the above object, a substrate processing apparatus of the present invention has a stage for holding a substrate and a condensing point on the substrate so as to cause multiphoton absorption with respect to the substrate held on the stage. And laser light irradiation means for irradiating laser light, and the laser light irradiation means controls the polarization direction of the laser light applied to the substrate in accordance with the moving direction of the laser light relative to the substrate. It has an element.

In the substrate processing apparatus of the present invention described above, the substrate is irradiated with the laser beam whose focusing point is aligned with the substrate by the laser beam irradiation means. Thereby, multiphoton absorption occurs in the substrate, and the region where the multiphoton absorption occurs is modified.
By moving the relative position of the substrate and the laser beam, a scribe line composed of the locus of the modified region is formed. In the present invention, the polarization direction of the laser light is controlled in accordance with the moving direction. That is, the polarization direction of the laser beam is controlled so that the polarization direction of the laser beam is always constant with respect to the moving direction. As a result, a scribe line composed of the locus of the modified region having a certain depth is formed.

  In order to achieve the above object, the substrate processing method of the present invention is a substrate processing method for processing a substrate by aligning a condensing point on the substrate and irradiating a laser beam to cause multi-photon absorption on the substrate. Then, the laser beam having a controlled polarization direction is irradiated according to the moving direction of the laser beam with respect to the substrate.

In the substrate processing method of the present invention described above, the substrate is irradiated with laser light having a focused point on the substrate. Thereby, multiphoton absorption occurs in the substrate, and the region where the multiphoton absorption occurs is modified.
By moving the relative position of the substrate and the laser beam, a scribe line composed of the locus of the modified region is formed. In the present invention, the laser beam whose polarization direction is controlled is irradiated according to the moving direction. That is, the polarization direction of the laser beam is controlled so that the polarization direction of the laser beam is always constant with respect to the moving direction. As a result, a scribe line composed of the locus of the modified region having a certain depth is formed.

  According to the present invention, it is possible to form a scribe line for stably dividing a substrate.

  Hereinafter, embodiments of a substrate processing apparatus and a substrate processing method of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram illustrating an example of a configuration of a substrate processing apparatus according to the present embodiment.

  A substrate processing apparatus 1 according to this embodiment includes a laser light source 2, a light shaping optical system 3, a half-wave plate 4, a condensing optical system 5, a driving unit 6, and a substrate 7 to be processed. And an XY stage 8 on which the substrate 7 is placed, and a control means 10 for controlling the entire apparatus. The laser light source 2, the light shaping optical system 3, the half-wave plate 4 and the condensing optical system 5 correspond to the laser light irradiation means of the present invention.

  The laser light source 2 oscillates, for example, laser light having a third harmonic of YAG (wavelength 355 nm). The pulse repetition frequency is, for example, 30 kHz. The laser light emitted from the laser light source 2 is, for example, linearly polarized light. The laser light source 2 is selected according to the material of the substrate 7. In the present embodiment, for example, it is assumed that the substrate 7 is a glass substrate. Since the energy required to cut the Si-O bond of the glass substrate is about twice that of light having a wavelength of 355 nm, the Si-O bond is cut by multiphoton absorption (in this case, two-photon absorption). be able to. Therefore, the second harmonic of YAG (wavelength 532 nm) can be used as the laser light source 2 depending on the material of the substrate 7.

  For example, the optical shaping optical system 3 collimates laser light emitted from the laser light source 2. The optical shaping optical system 3 includes an optical attenuator that controls the power of the laser light. Thereby, for example, laser light having a laser power of 7 W is emitted from the optical shaping optical system 3.

  The half-wave plate 4 corresponds to the optical element of the present invention. When the polarization direction of the laser light emitted from the light shaping optical system 3 is incident at an angle θ with respect to the optical axis of the half-wave plate 4, the polarization direction of the light is rotated by 2 × θ. Accordingly, laser light having an arbitrary polarization direction can be obtained by controlling the optical axis of the half-wave plate 4.

The condensing optical system 5 condenses the laser light emitted from the half-wave plate 4 on the substrate 7. The condensing optical system 5 condenses the laser beam so that the energy required for causing multiphoton absorption inside the substrate 7 is, for example, 1 kJ / cm ² .

  Multiphoton absorption means that two or more photons are absorbed simultaneously, and energy required for excitation is supplied in total. In order to increase the probability of multiphoton absorption, the power of the laser beam and the energy at the focal point are adjusted. By the multiphoton absorption, for example, a modified region is formed in the substrate 7. When the substrate 7 is a glass substrate, the modified region is, for example, an ionization region. When this ionization region is further irradiated with laser light, the glass in this region is sublimated to form grooves. Even if the groove is not formed, the substrate 7 is cut using the ionization region as a base point by applying a force to the ionization region in a subsequent break.

  The drive unit 6 is a rotary stage that holds the half-wave plate 4 and rotates the half-wave plate 4 in accordance with a control signal from the control unit 10. Thereby, the angle of the optical axis of the half-wave plate 4 with respect to the polarization direction of the laser light is adjusted. The rotation angle of the driving unit 6 is controlled by the control unit 10.

  The substrate 7 is, for example, a glass substrate. However, the material is not limited as long as it is a material that can absorb multiphotons enough to be processed. In addition, a semiconductor substrate or a piezoelectric material substrate can be employed as the substrate 7.

  The XY stage 8 has a substrate 7 to be processed and is configured to be movable in the X direction and the Y direction. The operation of the XY stage 8 is controlled by the control means 10. In the present embodiment, the laser light is fixed and the substrate 7 is moved by the XY stage 8 so that the laser light moves on the substrate 7. However, the XY stage 8 is fixed and the laser light is moved. May be configured to scan. By moving the substrate 7 by the XY stage 8, a groove-like scribe line is formed.

  The control means 10 controls the operation of the entire apparatus. The control unit 10 controls the rotation angle of the half-wave plate 4 by the driving unit 6 according to the X-direction operation and the Y-direction operation of the XY stage 8. For example, the driving unit 6 is controlled so that the polarization direction of the laser light is always constant with respect to the moving direction of the laser light with respect to the substrate 7 by operating the XY stage 8. More preferably, the driving means 6 is controlled so that the polarization direction of the laser light is always parallel to the moving direction of the laser light with respect to the substrate 7.

  Next, the operation of the substrate processing apparatus 1 according to the present embodiment having the above configuration will be described.

  The laser light emitted from the laser light source 2 is collimated by the light shaping optical system 3 and the power of the laser light is adjusted. Then, the polarization direction is adjusted by the half-wave plate 4 and is condensed on the substrate 7 by the condensing optical system 5. When the laser beam is condensed on the substrate 7, multiphoton absorption occurs inside the substrate 7, and the glass in the ionized region generated by the multiphoton absorption sublimes.

  Since the substrate 7 is moved relative to the laser beam by the XY stage 8, the portion that is sublimated and becomes a groove becomes a scribe line. In the present embodiment, the rotation of the half-wave plate 4 is controlled so that the polarization direction of the laser light is always constant with respect to the moving direction of the laser light with respect to the substrate 7.

  After the scribe line is formed, a force is applied to the substrate 7 so that the substrate 7 is broken along the scribe line in a subsequent break process. Thereby, the board | substrate 7 is divided | segmented into each small board | substrate enclosed by the scribe line.

  In the substrate processing apparatus 1 according to this embodiment having the above-described configuration, the polarization direction of the laser light applied to the substrate 7 is controlled in accordance with the moving direction of the laser light with respect to the substrate 7. The reason for this will be described.

  When the laser beam was moved (referred to as scribe) with respect to the substrate 7, the relationship between the polarization direction of the laser beam and the angle formed by the scribe direction and the depth of the groove of the scribe line formed was examined. FIG. 2 shows the experimental results. In this experiment, a glass substrate was used as the substrate 7.

  As shown in FIG. 2, it can be seen that the groove depth of the formed scribe line changes as the polarization direction of the laser light is rotated with respect to the direction in which the laser light moves relative to the substrate 7. At this time, the groove depth is maximum when the polarization direction is parallel to the scribe direction. Therefore, it can be said that the depth of the ionization region becomes maximum when the polarization direction is parallel to the scribe direction. Further, it was found that the relationship between the minimum a of the groove depth in FIG. 2 and the maximum b was b = 1.2a.

  As a result of the above experiment, if scribing was performed while maintaining the polarization direction of the laser beam parallel to the scribe direction, the laser irradiation conditions were maximized by utilizing the depth of the ionization region for an arbitrary trajectory. Can be a thing. In addition, even if not parallel, the depth of the ionization region can be made constant with respect to an arbitrary locus by maintaining the polarization direction of the laser light constant with respect to the scribe direction.

  For example, when the pulse repetition frequency is 30 kHz, the laser power is 7 W, and the moving speed of the XY stage 8 is 60 mm / s, the half-wave plate 4 is arranged so that the polarization direction of the laser light is orthogonal to the scribe direction. When the rotation angle is controlled, the groove depth of the scribe line is about 55 μm. On the other hand, when the rotation angle of the half-wave plate 4 is controlled so that the polarization direction of the laser beam is parallel to the scribe direction under the same conditions, the groove depth of the scribe line is about 70 μm. become.

  As described above, by making the angle of the polarization direction with respect to the moving direction of the laser beam with respect to the substrate 7 always constant, the depth of the formed scribe line becomes constant. For this reason, a stable break becomes possible.

  More preferably, by making the angle of the polarization direction parallel to the moving direction of the laser light with respect to the substrate 7, the deepest scribe line can be formed when the laser irradiation conditions are constant. This makes it possible to form deep scribe lines at high speed. The ability to form deep scribe lines facilitates subsequent breaks.

(Second Embodiment)
FIG. 3 is a diagram illustrating an example of the configuration of the substrate processing apparatus according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same component as 1st Embodiment, The duplication description is abbreviate | omitted.

  In the present embodiment, a θ stage 9 is added to the substrate processing apparatus 1 according to the first embodiment. The θ stage 9 rotates the XY stage 8 on which the substrate 7 is mounted. The movement and rotation of the substrate 7 in the plane are controlled by the operations of the XY stage 8 and the θ stage 9. The operation of the θ stage 9 is controlled by the control means 10.

  The control means 10 calculates the traveling direction of the laser beam with respect to the substrate 7 in real time based on the movement data of the XY stage 8 and the θ stage 9 so that the traveling direction matches the polarization direction of the laser beam. The angle of the half-wave plate 4 is calculated, and the driving means 6 is controlled so as to satisfy the angle. Alternatively, the driving unit 6 is controlled so that the angle formed by the traveling direction of the laser beam and the polarization direction of the laser beam is always constant.

  According to the present embodiment, not only a straight line but also a scribe line composed of an arbitrary curve can be formed. Even in this case, the groove depth of the scribe line can be made constant as in the first embodiment.

The present invention is not limited to the description of the above embodiment.
For example, in the present embodiment, an example in which the half-wave plate 4 is used as an example of the optical element of the present invention has been described, but a polarizing plate may be employed. For example, when the laser light emitted from the laser light source 2 is not linearly polarized light, the polarization direction of the laser light that has passed through the polarizing plate is along the transmission axis (optical axis) of the polarizing plate. Therefore, by controlling the rotation of the polarizing plate, it is possible to irradiate the substrate 7 with laser light whose polarization direction is controlled.

For example, in the present embodiment, examples of the XY stage 8 and the θ stage 9 have been described, but a z stage may be further added. Thereby, the condensing point of the laser beam can be controlled in the depth direction of the substrate 7.
In addition, various modifications can be made without departing from the scope of the present invention.

It is a figure which shows an example of a structure of the board | substrate processing apparatus which concerns on 1st Embodiment. It is a figure which shows the relationship between the angle which the polarization direction of a laser beam and the scribe direction make, and the depth of a scribe line. It is a figure which shows an example of a structure of the board | substrate processing apparatus which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate processing apparatus, 2 ... Laser light source, 3 ... Optical shaping optical system, 4 ... 1/2 wavelength plate (optical element), 5 ... Condensing optical system, 6 ... Driving means, 7 ... Substrate, 8 ... XY stage , 9 ... θ stage, 10 ... control means

Claims (7)

A stage for holding a substrate;
A laser beam irradiation means for irradiating the substrate with a laser beam by aligning a condensing point so as to cause multiphoton absorption with respect to the substrate held on the stage;
The said laser beam irradiation means has an optical element which controls the polarization direction of the laser beam irradiated to the said board | substrate according to the moving direction of the said laser beam with respect to the said board | substrate. The substrate processing apparatus according to claim 1, wherein the optical element controls a polarization direction of the laser light so that a polarization direction is parallel to a moving direction of the laser light with respect to the substrate. Driving means for rotating the optical axis of the optical element;
The substrate processing apparatus according to claim 1, further comprising a control unit that controls rotation of the driving unit in accordance with a moving direction of the laser beam with respect to the substrate. The substrate processing apparatus according to claim 1, wherein the optical element includes a half-wave plate. The substrate processing apparatus according to claim 1, wherein the optical element includes a polarizing plate. A substrate processing method for processing a substrate by aligning a condensing point on a substrate and irradiating a laser beam to cause multiphoton absorption in the substrate,
A substrate processing method of irradiating the laser beam with a polarization direction controlled in accordance with a moving direction of the laser beam with respect to the substrate. The substrate processing method according to claim 6, wherein the laser beam having the polarization direction parallel to a moving direction of the laser beam with respect to the substrate is irradiated.

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