JP6144503B2 - Processing equipment - Google Patents

Description

  The present invention relates to a processing apparatus.

  2. Description of the Related Art In recent years, there has been known a processing apparatus that cuts a processing object by condensing a processing laser beam at a position offset by a predetermined amount from the surface of the processing object (for example, see Patent Document 1 below). .

  Moreover, in the said processing apparatus, even if there exists an unevenness | corrugation in a processed surface by using an autofocus unit, a laser beam is made to condense to the said offset position by making a lens follow this unevenness | corrugation.

JP 2009-73366 A

  However, in the above prior art, since the optical system is set according to the offset amount, only processing corresponding to one offset position can be performed. Therefore, when processing with different offsets, it is necessary to change the optical system. There is a problem that the offset amount cannot be arbitrarily set.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a processing apparatus that can perform processing according to an arbitrary offset without changing an optical system.

In order to achieve the above object, a processing apparatus according to one aspect of the present invention includes a processing unit that performs processing by condensing a processing laser beam at a predetermined position of a processing object via an objective lens, and the objective. A plurality of confocal optical systems that receive reflected light of the light source from the object to be processed via a lens, and a difference between the received light intensity obtained based on the received light intensity of the two reflected lights in the plurality of confocal optical systems; And a plurality of offset amounts at the condensing position of the processing laser beam can be selected using a differential signal in which the offset amount of the objective lens and the offset amount of the objective lens are associated, and the position corresponding to the selected offset amount can be selected. Adjusting means for adjusting a relative position of the objective lens with respect to the object to be processed so as to collect a processing laser beam.

  According to this processing apparatus, a processing apparatus having a so-called autofocus function that adjusts the relative position of the objective lens with respect to the processing target so as to focus the processing laser beam at a position corresponding to the selected offset amount. Can provide. In addition, since it is possible to select a plurality of offset amounts at the focusing position of the processing laser beam, a versatile processing apparatus that can perform processing according to an arbitrary offset without changing the optical system. Can be provided.

  In the processing apparatus, three or more confocal optical systems may be provided.

  In the processing apparatus, each of the plurality of confocal optical systems may include the light sources that emit laser beams having different wavelengths.

  In the processing apparatus, at least two of the plurality of confocal optical systems may use divided light obtained by dividing light emitted from a common laser light source as light of the light source.

  Moreover, in the said processing apparatus, you may make it produce | generate the light splitting means which produces | generates the said division | segmentation light by dividing | segmenting the light of the said laser light source based on a polarization component.

  In the processing apparatus, the light splitting unit may include a λ / 2 plate and a polarization beam splitter.

  According to the present invention, it is possible to perform processing according to an arbitrary offset without changing the optical system.

The figure which shows schematic structure of the processing apparatus which concerns on 1st embodiment. The graph which shows the relationship between the light reception intensity | strength (standard value) of the light reception signal in each light detection part 21f-24f of the confocal optical systems 21-24, and the offset amount of the objective lens 3. FIG. The figure which shows an example of the difference signal produced by the control part. The figure which shows the process of parting the process target object A using a parting apparatus. The figure which shows schematic structure of the processing apparatus which concerns on 2nd embodiment.

Next, examples as specific examples of embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.
Also, in the description using the following drawings, it should be noted that the drawings are schematic and the ratio of each dimension and the like are different from the actual ones, and are necessary for the description for easy understanding. Illustrations other than the members are omitted as appropriate.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a processing apparatus according to the first embodiment.
As shown in FIG. 1, a processing apparatus 100 includes a laser processing unit (processing unit) 10, an autofocus optical system 20 that focuses processing laser light emitted from the laser processing unit 10 at a predetermined position, and a control. Part 50.

The laser processing unit 10 includes a stage 1 on which a processing target A is placed, a processing laser light source 2, and an objective lens 3 that is disposed to face the processing target A placed on the stage 1.
The stage 1 is provided with a placement surface 1a on which the workpiece A is placed on the upper surface. The movement of the stage 1 is controlled by the control unit 50. In the present embodiment, the processing object A is a silicon wafer. Note that the control unit 50 includes, for example, a CPU, a ROM, a RAM, and the like.

The control unit 50 moves the stage 1 along a direction (for example, a vertical direction) in which the workpiece A and the objective lens 3 on the placement surface 1a are brought close to or away from each other. Further, the control unit 50 can also move the stage 1 along a direction orthogonal to the vertical direction (for example, a paper surface penetration direction or a paper surface left-right direction).
Thereby, the stage 1 can finely adjust the relative position between the workpiece A and the objective lens 3 on the placement surface 1a.

  In this embodiment, the case where the relative position between the workpiece A and the objective lens 3 is adjusted by adjusting the position of the stage 1 will be described as an example. For example, the objective lens may be provided by providing a piezo element or the like. 3 may be moved directly to change the relative position of the objective lens 3 with respect to the workpiece A.

The processing laser light source 2 is for emitting the processing laser light L to the workpiece A, and includes a laser light source 2a that pulsates the processing laser light L or the like. The laser light source 2a pulsates infrared light as the processing laser light L.
The objective lens 3 condenses the processing laser light L at a predetermined position of the processing object A on the placement surface 1a.

  The autofocus optical system 20 collects the condensing position of the processing laser light L emitted from the laser processing unit 10 (processing laser light source 2) that changes according to the surface shape of the processing object A at a predetermined position. It is for making it light. The processing apparatus 100 according to the present embodiment uses the autofocus optical system 20 to focus the processing laser light L on the surface of the processing object A or a position offset by a predetermined amount inward from the surface. ing.

  The processing laser beam L passes through the workpiece A and is particularly absorbed in the vicinity of the condensing point inside the workpiece A (a position corresponding to the offset amount), thereby reforming the workpiece A. Form a region. That is, the processing apparatus 100 according to the present embodiment is for performing internal absorption laser processing. Here, the modified region formed by the processing apparatus 100 according to the present embodiment refers to a region where the density, refractive index, mechanical strength, and other physical characteristics are different from the surroundings. Specifically, the modified region includes, for example, a melting treatment region, a crack region (dielectric breakdown region), a refractive index change region, and the like, and includes a region where these are mixed.

  The melt treatment region is a region once solidified after being melted, a region in a molten state, a region in which the material is resolidified from a molten state, and can also be referred to as a phase-changed region or a region in which the crystal structure has changed. The melt treatment region can also be said to be a region in which one structure is changed to another structure in a single crystal structure, an amorphous structure, or a polycrystalline structure. In other words, for example, a region changed from a single crystal structure to an amorphous structure, a region changed from a single crystal structure to a polycrystalline structure, or a region changed from a single crystal structure to a structure including an amorphous structure and a polycrystalline structure. To do. When the object to be processed has a silicon single crystal structure, the melt processing region has, for example, an amorphous silicon structure.

The crack region is optical damage caused by the processing laser beam L being absorbed inside the object to be processed. Such optical damage induces thermal strain inside the workpiece, thereby forming a crack region including one or more cracks inside the workpiece. It can be said that the crack region is a dielectric breakdown region. The crack region is a condition in which, for example, a piezoelectric material made of glass or LiTaO ₃ is used as an object to be processed, and the electric field intensity at the focal point is 1 × 10 ⁸ (W / cm ² ) or more and the pulse width is 1 μs or less. This occurs when the processing laser beam L is irradiated.

The refractive index changing region means that when the laser beam L for processing is absorbed inside the object to be processed A in a state where the pulse width is extremely short, the energy is not converted into thermal energy, and ions inside the object to be processed exist. It is formed by inducing permanent structural changes such as valence change, crystallization, or polarization orientation. The refractive index changing region is made of, for example, glass as a processing object, and processing laser light under the condition that the electric field strength at the focal point is 1 × 10 ⁸ (W / cm ² ) or more and the pulse width is 1 ns or less. Occurs when L is irradiated.

The autofocus optical system 20 includes a first confocal optical system 21, a second confocal optical system 22, a third confocal optical system 23, a fourth confocal optical system 24, and a dichroic mirror 25.
The first to fourth confocal optical systems 21, 22, 23, and 24 (hereinafter sometimes referred to as confocal optical systems 21 to 24) have an optical path length from the objective lens 3 (processing object A) in this order. It is set to be long. The confocal optical systems 21 to 24 irradiate the processing object A on the placement surface 1a with detection light, and detect the reflected light on the surface of the processing object A.
The dichroic mirror 25 is disposed on the optical path of the processing laser light L between the processing laser light source 2 and the objective lens 3. The dichroic mirror 25 reflects the detection light in the confocal optical systems 21 to 24, but has an optical characteristic of transmitting the processing laser light L.

  The first confocal optical system 21 includes a collimating lens 21a, a convex lens 21b, a polarizing beam splitter 21c, a convex lens 21d, a pinhole plate 21e, a light detection unit 21f, a λ / 4 plate 21g, and a dichroic mirror 21h. And a light source 21i. The light source 21i is composed of, for example, a laser diode, and emits detection light having a wavelength (color) different from that of the other confocal optical systems 22, 23, and 24. The light detection unit 21f is composed of, for example, a photodiode.

  The second confocal optical system 22 includes a collimating lens 22a, a convex lens 22b, a polarizing beam splitter 22c, a convex lens 22d, a pinhole plate 22e, a light detection unit 22f, a λ / 4 plate 22g, and a dichroic mirror 22h. And a light source 22i. The light source 22i is composed of, for example, a laser diode, and emits detection light having a wavelength (color) different from that of the other confocal optical systems 21, 23, and 24. The light detection unit 22f is constituted by, for example, a photodiode.

  The third confocal optical system 23 includes a collimating lens 23a, a convex lens 23b, a polarizing beam splitter 23c, a convex lens 23d, a pinhole plate 23e, a light detection unit 23f, a λ / 4 plate 23g, and a dichroic mirror 23h. And a light source 23i. The light source 23i is composed of, for example, a laser diode, and emits detection light having a wavelength (color) different from that of the other confocal optical systems 21, 22, and 24. The light detection unit 23f is configured by a photodiode, for example.

  The fourth confocal optical system 24 includes a collimating lens 24a, a convex lens 24b, a polarizing beam splitter 24c, a convex lens 24d, a pinhole plate 24e, a light detection unit 24f, a λ / 4 plate 24g, and a dichroic mirror 24h. And a light source 24i. The light source 24i is composed of, for example, a laser diode, and emits detection light having a wavelength (color) different from that of the other confocal optical systems 21, 22, and 23. The light detection unit 24f is constituted by a photodiode, for example.

  In the first confocal optical system 21, the detection light emitted from the light source 21i is converted into parallel light by the collimator lens 21a, and then transmitted through the convex lens 21b, the polarization beam splitter 21c, and the λ / 4 plate 21g, and is dichroic. Passes through the mirror 21h. The dichroic mirror 21h has an optical characteristic that transmits only the detection light of the first confocal optical system 21 and reflects the detection light of the other confocal optical systems 22 to 24.

  The detection light that has passed through the dichroic mirror 21 h is reflected by the dichroic mirror 25. The detection light reflected by the dichroic mirror 25 is applied to the surface of the processing object A on the placement surface 1a via the objective lens 3.

  Detection light reflected on the surface of the workpiece A (hereinafter also referred to as reflection detection light) is reflected by the dichroic mirror 25, passes through the dichroic mirror 21h, and enters the λ / 4 plate 21g. Here, by reciprocating the λ / 4 plate 21g, the polarization direction of the reflected detection light is rotated by 90 °. Therefore, the reflected detection light is reflected by the polarization beam splitter 21c, and enters the light detection unit 21f through the pinhole plate 21e. The light detection unit 21f outputs a light reception signal having an intensity corresponding to the amount of light received.

  Similarly, in the second confocal optical system 22, the detection light emitted from the light source 22i is converted into parallel light by the collimator lens 22a, and then transmitted through the convex lens 22b, the polarization beam splitter 22c, and the λ / 4 plate 22g. Reflected by the dichroic mirror 22h. The dichroic mirror 22h has an optical characteristic that reflects only the detection light of the second confocal optical system 22 and transmits the detection light of the other confocal optical systems 23 and 24.

  The detection light reflected by the dichroic mirror 22h enters the dichroic mirror 21h of the first confocal optical system 21. Here, since the dichroic mirror 21h has an optical characteristic that transmits only the detection light of the first confocal optical system 21 as described above, the detection light of the second confocal optical system 22 is reflected by the dichroic mirror 21h. The light enters the dichroic mirror 25 and is reflected. The detection light reflected by the dichroic mirror 25 is applied to the surface of the processing object A on the placement surface 1a via the objective lens 3.

  The reflected detection light reflected by the surface of the workpiece A is reflected by the dichroic mirror 25, is sequentially reflected by the dichroic mirrors 21h and 22h of the first confocal optical system 21, and enters the λ / 4 plate 22g. Here, by reciprocating the λ / 4 plate 22g, the polarization direction of the reflected detection light is rotated by 90 °. Therefore, the reflected detection light is reflected by the polarization beam splitter 22c, and enters the light detection unit 22f through the pinhole plate 22e. The light detection unit 22f outputs a light reception signal having an intensity corresponding to the amount of light received.

  Similarly, in the third confocal optical system 23, the detection light emitted from the light source 23i is converted into parallel light by the collimator lens 23a, and then transmitted through the convex lens 23b, the polarization beam splitter 23c, and the λ / 4 plate 23g. Reflected by the dichroic mirror 23h. Note that the dichroic mirror 23 h has an optical characteristic of reflecting only the detection light of the third confocal optical system 23 and transmitting the detection light of the fourth confocal optical system 24.

  The detection light reflected by the dichroic mirror 23h enters the dichroic mirror 22h of the second confocal optical system 22. Here, since the dichroic mirror 22h has the optical characteristic of reflecting only the detection light of the second confocal optical system 22 as described above, the detection light of the third confocal optical system 23 is transmitted through the dichroic mirror 22h. The light enters the dichroic mirror 21 h of the first confocal optical system 21. Since the dichroic mirror 21h has an optical characteristic that transmits only the detection light of the first confocal optical system 21 as described above, the detection light of the third confocal optical system 23 is reflected by the dichroic mirror 21h and is reflected by the dichroic mirror 25. Is incident and reflected. The detection light reflected by the dichroic mirror 25 is applied to the surface of the processing object A on the placement surface 1a via the objective lens 3.

  The reflected detection light reflected from the surface of the workpiece A is sequentially reflected by the dichroic mirrors 25 and 21h, passes through the dichroic mirror 22h, is reflected by the dichroic mirror 23h, and enters the λ / 4 plate 23g. . Here, by reciprocating the λ / 4 plate 23g, the polarization direction of the reflected detection light is rotated by 90 °. Therefore, the reflected detection light is reflected by the polarization beam splitter 23c, and enters the light detection unit 23f through the pinhole plate 23e. The light detection unit 23f outputs a light reception signal having an intensity corresponding to the amount of light received.

  Similarly, in the fourth confocal optical system 24, the detection light emitted from the light source 24i is converted into parallel light by the collimator lens 24a, and then transmitted through the convex lens 24b, the polarization beam splitter 24c, and the λ / 4 plate 24g. Reflected by the dichroic mirror 24h.

  The detection light reflected by the dichroic mirror 24h is incident on the dichroic mirror 23h of the third confocal optical system 23. Here, since the dichroic mirror 23h has an optical characteristic of reflecting only the detection light of the third confocal optical system 23 as described above, the detection light of the fourth confocal optical system 24 is transmitted through the dichroic mirror 23h. The light enters the dichroic mirror 22 h of the second confocal optical system 22. Since the dichroic mirror 22h has an optical characteristic that reflects only the detection light of the second confocal optical system 21 as described above, the detection light of the fourth confocal optical system 24 passes through the dichroic mirror 22h and passes through the first confocal optical system 22h. The light enters the dichroic mirror 21 h of the focus optical system 21. Since the dichroic mirror 21h has an optical characteristic that transmits only the detection light of the first confocal optical system 21 as described above, the detection light of the fourth confocal optical system 24 is reflected by the dichroic mirror 21h and is reflected by the dichroic mirror 25. Is incident and reflected. The detection light reflected by the dichroic mirror 25 is applied to the surface of the processing object A on the placement surface 1a via the objective lens 3.

  The reflected detection light reflected on the surface of the workpiece A is sequentially reflected by the dichroic mirrors 25 and 21h, then passes through the dichroic mirrors 22h and 23h, and then is reflected by the dichroic mirror 24h and is reflected on the λ / 4 plate 24g. Incident. Here, by reciprocating the λ / 4 plate 24g, the polarization direction of the reflected detection light is rotated by 90 °. Therefore, the reflected detection light is reflected by the polarization beam splitter 24c, and enters the light detection unit 24f through the pinhole plate 24e. The light detection unit 24f outputs a light reception signal having an intensity corresponding to the amount of light received.

  As described above, in the present embodiment, each of the confocal optical systems 21 to 24 includes the light sources 21i to 24i that emit laser beams (detection lights) having different wavelengths, thereby utilizing the difference in wavelength. The detection light of each confocal optical system 21-24 is isolate | separated by the dichroic mirrors 21h-24h, and it becomes possible to receive each detection light reliably.

  Here, the relationship between the light reception signals of the respective light detection units 21f to 24f of the confocal optical systems 21 to 24 and the offset amount of the objective lens 3 will be described. FIG. 2 is a graph showing the relationship between the received light intensity (standard value) of the received light signal and the offset amount of the objective lens 3 in each of the light detection units 21 f to 24 f of the confocal optical systems 21 to 24. Hereinafter, the offset amount from the surface of the workpiece A at the focal position of the objective lens 3 may be referred to as the offset amount of the objective lens 3.

  The vertical axis indicates the received light intensity (standard value), and the horizontal axis indicates the offset amount (unit: μm) from the surface of the workpiece A at the focal position of the objective lens 3. Here, the offset amount from the surface of the workpiece A at the focal position of the objective lens 3 is a position (depth from the surface) where the processing laser light L transmitted through the objective lens 3 is focused. For example, an offset amount of 0 (zero) means that the processing laser light L via the objective lens 3 is focused on the surface of the workpiece A, and the offset amount is + (plus). This means that the processing laser beam L via the objective lens 3 is condensed inside the workpiece A, and an offset amount of − (minus) means that the processing laser beam L via the objective lens 3 is It means that the light is collected outside the workpiece A.

  As shown in FIG. 2, in the first confocal optical system 21, when the offset amount of the objective lens 3 with respect to the workpiece A is −25 μm, the light reception intensity (light reception signal) by the light detection unit 21f is maximized. Each optical member (pinhole plate 21e, convex lenses 21b, 21d, etc.) is arranged as described above. Therefore, when the light reception signal in the light detection unit 21f is maximized, the processing laser light L via the objective lens 3 is condensed at a position 25 μm away from the surface of the processing target A.

  As shown in FIG. 2, the second confocal optical system 22 has the maximum light reception intensity (light reception signal) by the light detection unit 22f when the offset amount of the objective lens 3 with respect to the workpiece A is +25 μm. Each optical member (pinhole plate 22e, convex lenses 22b, 22d, etc.) is arranged so as to be. Therefore, when the light reception signal in the light detection unit 22f is maximized, the processing laser light L via the objective lens 3 is condensed at a position (offset position) of 25 μm inside from the surface of the processing object A. Has been.

  As shown in FIG. 2, the third confocal optical system 23 has the maximum light reception intensity (light reception signal) by the light detection unit 23f when the offset amount of the objective lens 3 with respect to the workpiece A is +75 μm. Each optical member (pinhole plate 23e, convex lenses 23b, 23d, etc.) is arranged so as to be. Therefore, when the light reception signal in the light detection unit 23f is maximized, the processing laser light L through the objective lens 3 is condensed at a position (offset position) of 75 μm inside from the surface of the processing target A. Has been.

  Further, as shown in FIG. 2, the fourth confocal optical system 24 has the maximum light reception intensity (light reception signal) by the light detection unit 24f when the offset amount of the objective lens 3 with respect to the workpiece A is +125 μm. Each optical member (pinhole plate 24e, convex lenses 24b, 24d, etc.) is arranged so as to be. Therefore, when the light reception signal in the light detection unit 24f becomes the maximum, the processing laser light L via the objective lens 3 is condensed at a position (offset position) that is 125 μm inward from the surface of the processing object A. Has been.

  Each of the light detection units 21 f to 24 f is electrically connected to the control unit 50. The control unit 50 performs a calculation process for obtaining a difference for the detection signals (see FIG. 2) transmitted from the respective light detection units 21f to 24f, and creates a difference signal.

  FIG. 3 is a diagram illustrating an example of a difference signal created by the control unit 50. In FIG. 3, the vertical axis represents the difference in received light intensity, and the horizontal axis represents the offset amount (unit: μm) from the surface of the workpiece A at the focal position of the objective lens 3 as in FIG. . The first difference S1 in FIG. 3 indicates the difference in the received light intensity of the received light signal in the first confocal optical system 21 and the second confocal optical system 22 in FIG. The second difference S2 in FIG. 3 indicates the difference in the received light intensity of the received light signal in the second confocal optical system 22 and the third confocal optical system 23 in FIG. A third difference S3 in FIG. 3 indicates a difference in received light intensity of received light signals in the third confocal optical system 23 and the fourth confocal optical system 24 in FIG.

The control unit 50 controls the offset amount of the objective lens 3 based on the first difference S1, the second difference S2, and the third difference S3 illustrated in FIG.
As shown in FIG. 3, when the difference value of the received light intensity is 0 (zero), the first difference S1 has an offset amount of 0 (zero) μm. As shown in FIG. 3, the second difference S2 has an offset amount of 50 μm when the difference value of the received light intensity is 0 (zero). As shown in FIG. 3, the third difference S3 has an offset amount of 100 μm when the difference value of the received light intensity is 0 (zero).

  Based on such a configuration, the processing apparatus 100 can select a plurality (three) of offset amounts (in this embodiment, 0 μm, 50 μm, and 100 μm). Specifically, the control unit 50 adjusts the relative positions of the processing object A and the objective lens 3 so as to focus (focus) the processing laser light L on the selected offset amount. That is, the control unit 50 corresponds to the adjusting means described in the claims of the present invention.

  For example, the processing apparatus 100 adjusts the position of the stage 1 so that the control unit 50 sets the value of the first difference S1 to 0 (zero) when 0 (zero) μm is selected as the offset amount. Thus, the relative position of the objective lens 3 with respect to the workpiece A is adjusted. Thereby, the processing apparatus 100 can perform laser processing in a state where the offset amount of the objective lens 3 is set to 0 (zero). Therefore, the processing apparatus 100 can focus the processing laser light L on the surface of the processing target A via the objective lens 3.

  Further, when 50 μm is selected as the offset amount, the processing apparatus 100 adjusts the position of the stage 1 so that the control unit 50 sets the value of the second difference S2 to 0 (zero). The relative position of the objective lens 3 with respect to A is adjusted. Thereby, the control part 50 can perform laser processing in the state which set the offset amount of the objective lens 3 to 50 micrometers. Therefore, the processing apparatus 100 can focus the processing laser light L at a position offset by 50 μm inward from the surface of the processing target A via the objective lens 3.

  Further, when 100 μm is selected as the offset amount, the processing apparatus 100 adjusts the position of the stage 1 so that the control unit 50 sets the value of the third difference S3 to 0 (zero). The relative position of the objective lens 3 with respect to A is adjusted. Thereby, the control part 50 can perform laser processing in the state which set the offset amount of the objective lens 3 to 100 micrometers. Therefore, the processing apparatus 100 can focus the processing laser light L at a position offset by 100 μm inward from the surface of the processing target A via the objective lens 3.

Thus, according to the processing apparatus 100 according to the present embodiment, the control unit 50 transmits a signal transmitted from the autofocus optical system 20, specifically, the plurality of confocal optical systems 21 to 24 (light detection units 21f to 24f). A plurality of offset amounts at the condensing position of the processing laser light L can be selected based on the difference data of the reception result of the reflection detection light in ().
Further, the processing apparatus 100 can autofocus the relative position of the objective lens 3 with respect to the processing target A so as to correspond to the selected offset amount.

Next, a case where the processing object A is cut using the processing apparatus 100 will be described.
First, a semiconductor wafer having a thickness of, for example, 300 μm as the workpiece A is placed on the stage 1. This processing object A has a substantially circular shape in a plan view.

  Subsequently, the processing apparatus 100 adjusts the position of the objective lens 3 with respect to the processing target A so as to correspond to the offset amount selected by the user. Specifically, the processing apparatus 100 drives the stage 1 so that the processing laser light L via the objective lens 3 overlaps the start position of the line to be cut of the processing target A, and the processing target on the placement surface 1a. A and the objective lens 3 are aligned.

  For example, when the user selects an offset amount of 50 μm, the control unit 50 drives the first confocal optical system 21 and the second confocal optical system 22 in the autofocus optical system 20. Thereby, each light detection part 21f and 22f of the 1st confocal optical system 21 and the 2nd confocal optical system 22 receives each reflection detection light by the workpiece A via the pinhole plates 21e and 22e. The light detection units 21f and 22f transmit the light reception results to the control unit 50, respectively.

The control unit 50 acquires detection signals (see FIG. 2) of the respective light detection units 21f and 22f of the first confocal optical system 21 and the second confocal optical system 22, and differential data of these detection signals (see FIG. 3). ) Is calculated by arithmetic processing. Then, the relative position of the objective lens 3 with respect to the workpiece A is adjusted by adjusting the position of the stage 1 so that the value of the second difference S2 shown in FIG.
Thus, the alignment of the objective lens 3 and the workpiece A is completed at the start position of the planned cutting line.

  Subsequently, the control unit 50 drives the processing laser light source 2. The processing laser light source 2 irradiates the processing laser light L toward the objective lens 3. The processing laser light L passes through the dichroic mirror 25 and enters the objective lens 3, and is condensed at a predetermined position of the processing object A by the objective lens 3. Specifically, the processing laser light L corresponds to the selected offset amount, and is condensed at a position that enters by 50 μm inward from the surface of the processing object A. The processing laser light L forms the modified region as described above at the condensing position of the workpiece A.

  The control unit 50 can move the processing laser light L relative to the processing target A by moving the stage 1 while the processing target A is irradiated with the processing laser light L. As a result, a modified region is formed on the workpiece A along the scheduled cutting line set along the moving direction of the stage 1.

  The control unit 50 moves the stage 1 until the processing laser beam L passes through the entire area to be cut. Thus, the processing apparatus 100 ends the laser processing with the processing laser light L.

Then, the division process of the workpiece A will be described.
FIG. 4 is a diagram illustrating a process of dividing the workpiece A using a cutting apparatus.
As shown in FIG. 4A, the cutting device 30 includes a pressing part 31 and a holding part 32. The pressing portion 31 has a substantially circular shape larger than the workpiece A and supports the workpiece A attached to the tape 33. The tape 33 has a circular shape concentric with the workpiece A. The holding | maintenance part 32 is arrange | positioned so that the circumference | surroundings of the press part 31 may be enclosed, and hold | maintains the circular tape 33 over the whole area of the circumferential direction.

As shown in FIG. 4B, the cutting device 30 moves the pressing portion 31 upward, and the holding portion 32 pulls the tape 33 toward the outer side in the radial direction. As a result, a tensile force is applied radially and isotropically from the center to the workpiece A attached to the tape 33. The processing object A is irradiated with the laser beam L for processing by the processing apparatus 100, so that a modified region is formed on the inner surface corresponding to the planned cutting line A1. The modification area | region is fractured | ruptured and the process target object A is divided | segmented into the several chip member A2, as FIG.4 (c) shows, when tensile force is provided.
Thus, the process of dividing (separating) the workpiece A is completed.

  In the above description, the case where the user selects the offset amount of 50 μm is taken as an example, but even when the offset amount of 100 μm is selected, the processing step by the processing device 100 and the cutting step by the cutting device 30 are similarly performed. By doing so, it is possible to divide the processing object A having a greater thickness and to separate the plurality of chip members into individual pieces.

  In addition, in the case where the user selects an offset amount of 0 μm, the processing apparatus 100 irradiates the processing laser beam L along the surface of the processing object A, thereby forming grooves and patterns on the surface of the processing object A. Can be formed.

  As described above, according to the present embodiment, the relative position of the objective lens 3 with respect to the processing object A is adjusted so that the processing laser light L is condensed at a position corresponding to the selected offset amount. A processing apparatus 100 having an autofocus function is provided. Further, since a plurality of offset amounts (offset amounts of the objective lens 3) at the condensing position of the processing laser beam L can be selected, it is possible to perform processing according to an arbitrary offset without changing the optical system. The processing apparatus 100 with excellent versatility can be provided.

  Moreover, the processing apparatus 100 can select three offset amounts by using the difference between detection results obtained by the light detection units 21f to 24f of the four confocal optical systems 21 to 24. Note that the processing apparatus 100 may include at least three confocal optical systems so that a plurality of offset amounts can be selected.

  In the description of the above embodiment, the control unit 50 controls the objective lens 3 so that the values of the first difference S1, the second difference S2, and the third difference S3 are all 0 (zero). Although the case where the offset amount of the objective lens 3 is set to 0, 50, or 100 μm by adjusting the position has been described as an example, the present invention is not limited to this. For example, if the position of the objective lens 3 is adjusted so that the values of the first difference S1, the second difference S2, and the third difference S3 are −0.4, the offset of the objective lens 3 The amount can be selected from 10, 60 and 110 μm. That is, various offsets can be selected by setting different difference values for each of the first difference S1, the second difference S2, and the third difference S3. Specifically, in the first difference S1, the objective lens is set by setting the value within a range of −1.0 to 0.

(Second embodiment)
Then, the structure of the processing apparatus which concerns on 2nd embodiment is demonstrated.
The difference between this embodiment and the said embodiment is an autofocus optical system, and the structure of the laser processing part 10 other than that is common. Therefore, in the following description, the same reference numerals are assigned to the same members and common configurations as those in the above-described embodiment, and descriptions of the configurations are omitted or simplified.

FIG. 5 is a diagram showing a schematic configuration of a processing apparatus according to the second embodiment.
As shown in FIG. 5, the processing apparatus 200 according to the present embodiment includes a laser processing unit 10, an autofocus optical system 120 that focuses a processing laser beam emitted from the laser processing unit 10 at a predetermined position, and The control unit 50 is provided.

The autofocus optical system 120 according to the present embodiment includes a first confocal optical system 121, a second confocal optical system 122, a third confocal optical system 123, a fourth confocal optical system 124, a dichroic mirror 25, 26 and a mirror 27.
The first to fourth confocal optical systems 121, 122, 123, and 124 (hereinafter sometimes referred to as confocal optical systems 121 to 124) have an optical path length from the objective lens 3 (processing object A) in this order. It is set to be long.
The dichroic mirror 26 is disposed on the optical path of the detection light between the confocal optical systems 121 to 124 and the dichroic mirror 25. Although the dichroic mirror 26 transmits the detection light in the first and second confocal optical systems 121 and 122, it has an optical characteristic of reflecting the detection light in the third and fourth confocal optical systems 123 and 124.
The mirror 27 is disposed on the optical path of the detection light between the dichroic mirror 26 and the third and fourth confocal optical systems 123 and 124. The mirror 27 has an optical characteristic of reflecting the detection light in the third and fourth confocal optical systems 123 and 124.

  The first confocal optical system 121 includes a light source unit 130, a convex lens 121b, a half mirror 121c, a pinhole lens 121d, a pinhole plate 121e, a light detection unit 121f, and a polarization beam splitter 131. The light source unit 130 includes, for example, a light source 130a composed of a laser diode, a collimator lens 130b, a λ / 2 plate 130c, and a polarization beam splitter 130d.

  The second confocal optical system 122 includes a light source unit 130, a mirror 132, a convex lens 122b, a half mirror 122c, a pinhole lens 122d, a pinhole plate 122e, a light detection unit 122f, a mirror 133, and a polarization. A beam splitter 131. That is, the second confocal optical system 122 shares the light source unit 130 and the polarization beam splitter 131 with the first confocal optical system 121.

  The third confocal optical system 123 includes a light source unit 134, a convex lens 123b, a half mirror 123c, a pinhole lens 123d, a pinhole plate 123e, a light detection unit 123f, and a polarization beam splitter 135. The light source unit 134 includes, for example, a light source 134a composed of a laser diode, a collimator lens 134b, a λ / 2 plate 134c, and a polarization beam splitter 134d. The light source 134 a emits light having a wavelength (color) different from that of the light source 130 a of the light source unit 130 of the first and second confocal optical systems 121 and 122.

  The fourth confocal optical system 124 includes a light source unit 134, a mirror 136, a convex lens 124b, a half mirror 124c, a pinhole lens 124d, a pinhole plate 124e, a light detection unit 124f, a mirror 137, and a polarization. A beam splitter 135. That is, the fourth confocal optical system 124 shares the light source unit 134 and the polarization beam splitter 135 with the third confocal optical system 123.

The detection light (laser light) emitted from the light source 130a of the light source unit 130 is converted into parallel light by the collimator lens 130b, and then passes through the λ / 2 plate 130c. Since the detection light is linearly polarized laser light, the light is separated based on the polarization component by appropriately rotating the λ / 2 plate 130c. Specifically detected light is separated into P-polarized light L _P and the S-polarized light L _S by passing through the lambda / 2 plate 130c. Here, the P-polarized light L _P is polarized light having a polarization component in which the vibration direction of light is parallel to the incident surface. S-polarized light L _S is polarized light having a polarization component in which the vibration direction of light is perpendicular to the incident surface.

Detection light including P-polarized light L _P and S-polarized light L _S enters the polarization beam splitter 130d. Polarization beam splitter 130d has a characteristic to transmit P-polarized light _{L P,} reflects the S-polarized light _{L S.} Accordingly, the detection light, splits the detection light incident through the polarizing beam splitter 130d into P-polarized light _{L P} and S-polarized light _{L S,} P-polarized light _{L P} is incident on the convex lens 121b of the first confocal optical system 121 , S-polarized light L _S is incident on the convex lens 122 b of the second confocal optical system 122.

Further, the detection light (laser light) emitted from the light source 134a of the light source unit 134 is converted into parallel light by the collimator lens 134b, and then passes through the λ / 2 plate 134c. Since the detection light is linearly polarized laser light, the divided light is separated based on the polarization component by appropriately rotating the λ / 2 plate 134c. Specifically detected light is separated into P-polarized light L _P and the S-polarized light L _S by passing through the lambda / 2 plate 134c.

In the first confocal optical system 121, P-polarized light _{L P} passes through the convex lens 121b, a half mirror 121c, the polarizing beam splitter 131, passes through the dichroic mirror 26. The polarization beam splitter 131 transmits only the detection light (P-polarized light L _P ) of the first confocal optical system 121 and reflects the detection light (S-polarized light L _S ) of the second confocal optical system 122. Have

The detection light (P-polarized light L _P ) that has passed through the dichroic mirror 26 is reflected by the dichroic mirror 25. The detection light reflected by the dichroic mirror 25 is applied to the surface of the processing object A on the placement surface 1a via the objective lens 3.

Detection light reflected by the surface of the workpiece A (hereinafter also referred to as reflection detection light) is reflected by the dichroic mirror 25, passes through the dichroic mirror 26 and the polarization beam splitter 131, and is reflected by the half mirror 121c. Is done. The reflected detection light (P-polarized light L _P ) is incident on the light detection unit 121f through the pinhole plate 121e. The light detection unit 121f outputs a light reception signal having an intensity corresponding to the amount of light received.

Similarly, in the second confocal optical system 122, after the S polarized light L _S is reflected by the mirror 132, it passes through the convex lens 122b and the half mirror 122c, and is reflected by the mirror 133 and the polarization beam splitter 131, respectively. 26 is transmitted.

The detection light (S-polarized light L _S ) transmitted through the dichroic mirror 26 is reflected by the dichroic mirror 25. The detection light reflected by the dichroic mirror 25 is applied to the surface of the processing object A on the placement surface 1a via the objective lens 3.

The detection light (reflection detection light) reflected by the surface of the workpiece A is reflected by the dichroic mirror 25, passes through the dichroic mirror 26, passes through the polarization beam splitter 131, and is reflected by the half mirror 122c. The reflected detection light (S-polarized light L _S ) enters the light detection unit 122f through the pinhole plate 122e. The light detection unit 122f outputs a light reception signal having an intensity corresponding to the amount of light received.

Similarly in the third confocal optical system 123, P-polarized light _{L P} is a convex lens 123b, transmitted through the half mirror 123c, passes through the polarizing beam splitter 135. The polarization beam splitter 135 transmits only the detection light (P-polarized light L _P ) of the third confocal optical system 123 and reflects the detection light (S-polarized light L _S ) of the fourth confocal optical system 124. Have

The detection light (P-polarized light L _P ) that has passed through the polarization beam splitter 135 is reflected by the mirror 27, the dichroic mirror 26, and the dichroic mirror 25, respectively. The detection light reflected by the dichroic mirror 25 is applied to the surface of the processing object A on the placement surface 1a via the objective lens 3.

Detection light (reflection detection light) reflected on the surface of the workpiece A is reflected by the dichroic mirror 25, reflected by the dichroic mirror 26 and mirror 27, transmitted through the polarization beam splitter 135, and reflected by the half mirror 123c. The The reflected detection light (S-polarized light L _S ) enters the light detection unit 123f through the pinhole plate 123e. The light detection unit 123f outputs a light reception signal having an intensity corresponding to the amount of light received.

Similarly, in the fourth confocal optical system 124, after the S-polarized light L _S is reflected by the mirror 136, it is transmitted through the convex lens 124b and the half mirror 124c, and the mirror 137, the polarization beam splitter 135, the mirror 27, and the dichroic mirror 26. Are each reflected.

The detection light (S-polarized light L _S ) reflected by the dichroic mirror 26 is reflected by the dichroic mirror 25. The detection light reflected by the dichroic mirror 25 is applied to the surface of the processing object A on the placement surface 1a via the objective lens 3.

Detection light (reflection detection light) reflected on the surface of the workpiece A is reflected by the dichroic mirror 25, the dichroic mirror 26, the mirror 27, the polarization beam splitter 135, the mirror 137, and the half mirror 124c. The reflected detection light (S-polarized light L _S ) enters the light detection unit 124f through the pinhole plate 124e. The light detection unit 124f outputs a light reception signal having an intensity corresponding to the amount of light received.

  As described above, in the present embodiment, each of the first and second confocal optical systems 121 and 122 and the third and fourth confocal optical systems 123 and 124 constituting the autofocus optical system 120 is mutually connected to the light source unit 130. , 134 are made common. Thereby, the number of parts of the processing apparatus 200 is reduced, and cost reduction is realized.

Further, the processing device 200, the light source unit 130 and 134 includes a light source 130a, the respective detected light reliably detected light emitted from 134a by separating the P-polarized light _{L P} and S-polarized light _{L S} based on the polarized component It is possible to receive light.

  Also in the present embodiment, each of the light detection units 121f to 124f is electrically connected to the control unit 50, respectively. As in the above embodiment, the control unit 50 performs a calculation process for obtaining a difference on the detection signals (see FIG. 2) transmitted from the respective light detection units 121f to 124f, and creates a difference signal.

  Therefore, also in the processing apparatus 200 according to the present embodiment, a plurality (three) of offset amounts (in this embodiment, 0 μm, 50 μm, and 100 μm) can be selected. The control unit 50 adjusts the relative positions of the processing object A and the objective lens 3 so as to focus (focus) the processing laser light L on the selected offset amount.

As described above, also in the present embodiment, a signal transmitted from the autofocus optical system 120 by the control unit 50, specifically, reflection detection in the plurality of confocal optical systems 121 to 124 (light detection units 121f to 124f). A plurality of offset amounts at the condensing position of the processing laser beam L can be selected based on the difference data of the light reception result.
Further, the processing apparatus 200 can autofocus the relative position of the objective lens 3 with respect to the processing target A so as to correspond to the selected offset amount.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the main point of invention, it can change suitably. For example, in the above-described embodiment, the modified region including the melt processing region is formed on the workpiece A made of a semiconductor wafer. However, the crack region or the inside of the workpiece made of another material such as glass or a piezoelectric material is formed. Other modified regions such as a refractive index changing region may be formed.

In the above embodiment, the autofocus optical systems 20 and 120 each include four confocal optical systems so that three offset amounts can be selected. However, by providing five or more confocal optical systems. A configuration in which four or more offset amounts are selected may be employed.
Also, the configurations of the autofocus optical systems 20 and 120 may be combined. That is, one of the light sources of the plurality of confocal optical systems may be shared, and the detection light may be detected by separating the light components by the polarization component, and the detection light may be detected by separating the light sources by wavelength. .
In the above embodiment, the case where the optical axes of the autofocus optical systems 20 and 120 are emitted coaxially with the optical axis of the processing laser beam L has been described as an example. May be.

A ... processing object, L ... laser beam for processing, 3 ... objective lens, 10 ... laser processing part (processing means), 21, 121 ... first confocal optical system, 22, 121 ... second confocal optical system, 23, 123 ... third confocal optical system, 24, 124 ... fourth confocal optical system, L _P ... P polarized light (polarized light component), L _S ... S polarized light (polarized light component), 100, 200 ... processing device, 130a , 134a... Light source (common laser light source), 130c, 134c... Λ / 2 plate, 130d, 134d.

Claims (6)

A processing means for performing processing by condensing the processing laser beam at a predetermined position of the processing object via the objective lens;
A plurality of confocal optical systems that receive reflected light of the light source from the object to be processed through the objective lens;
The difference between the received light intensity obtained based on the received light intensity of the two reflected lights in the plurality of confocal optical systems and the offset signal of the objective lens are used for the processing laser light. A plurality of offset amounts at the condensing position can be selected, and the relative position of the objective lens with respect to the object to be processed is adjusted so that the processing laser light is condensed at a position corresponding to the selected offset amount. And a processing device. The processing apparatus according to claim 1, wherein each of the plurality of confocal optical systems includes the light source that emits laser beams having different wavelengths. Wherein at least two of the plurality of confocal optical system, the processing apparatus according to claim 1 or 2 utilizing divided light obtained by dividing the light emitted from a common laser light source as the light of the light source. The processing apparatus according to claim 3 , wherein the light splitting unit that generates the split light is generated by splitting the light of the laser light source based on a polarization component. The processing apparatus according to claim 4 , wherein the light splitting unit includes a λ / 2 plate and a polarization beam splitter. Processing apparatus according to any one of claims 1 to 5 comprising three or more the confocal optical system.

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