JP2020196038A - Inclination check method - Google Patents

Abstract

To provide an inclination check method that is able to accurately check the inclination of a laser beam emitted to a work piece.SOLUTION: An inclination check method, by which inclination of a laser beam emitted to a work piece from an emitting head of a laser beam emitting unit and having a wavelength absorbed by the work piece is checked with respect to the work piece, comprises: forming a first groove in the work piece by condensing the laser beam into a position of a first height using an upper surface of the work piece as a reference; forming a second groove in the work piece by condensing a laser beam into a position of a second height different from the first height; based on a first image obtained by imaging the first groove from above, calculating a first quantity of displacement, corresponding to a distance between a position serving as a reference in the first image and the first groove; based on a second image obtained by imaging the second groove from above, calculating a second quantity of displacement, corresponding to a distance between a position serving as a reference in the second image and the second groove; based on the first quantity of displacement and the second quantity of displacement, checking inclination of the laser beam made incident on the work piece, to the upper surface in an incident direction.SELECTED DRAWING: Figure 6

Description

The present invention relates to a tilt confirmation method used when confirming the tilt of a laser beam irradiated to a work piece.

For device chips to be incorporated into various electronic devices, the surface of the wafer as the base material is divided into a plurality of areas by a planned division line called a street, and devices such as integrated circuits are formed in each area, and then this wafer is placed. It is obtained by dividing along the planned division line. When dividing a plate-shaped workpiece such as a wafer, for example, a laser machining apparatus equipped with a laser beam irradiation unit capable of irradiating a laser beam having a wavelength absorbed by the workpiece is used (for example, a patent). Reference 1).

The laser beam irradiation unit generally includes a laser oscillator and an optical system composed of a plurality of optical components, and guides the laser beam generated by the laser oscillator to the workpiece by the optical system. If the laser beam irradiation unit is used to irradiate a laser beam so as to condense light on the surface or inside of the work piece, a groove or the like can be formed in the work piece by so-called ablation processing.

By the way, when the laser beam is obliquely incident on the surface of the workpiece (incident angle ≠ 0 °), the groove formed by the laser beam is tilted, and the debris generated during the ablation process is formed in the groove. It scatters a lot on one side. Therefore, in the ablation processing of the workpiece as described above, the optical system of the laser beam irradiation unit is adjusted so that the incident direction (traveling direction) of the laser beam is perpendicular to the surface of the workpiece. Is important.

JP-A-2007-275912

As a method of confirming the inclination of the laser beam in the incident direction with respect to the workpiece, for example, there is a method of reflecting the laser beam emitted from the laser beam irradiation unit with a mirror and confirming the deviation of the reflected light with respect to the incident light. .. However, in this method, when the angle of the mirror fixed by the holder or the like deviates from an appropriate value, it becomes difficult to accurately confirm the inclination of the laser beam in the incident direction.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a tilt confirmation method capable of accurately confirming the tilt of a laser beam irradiating a work piece.

According to one aspect of the present invention, there is a tilt confirmation method for confirming the tilt of a laser beam having a wavelength that is irradiated from the irradiation head of the laser beam irradiation unit to the workpiece and absorbed by the workpiece with respect to the workpiece. Then, while condensing the laser beam at a position at a first height with respect to the upper surface of the work piece, the work piece and the irradiation head are relatively moved in a direction along the upper surface, and the laser beam is focused. A position of a second height different from the first processing step of forming a first groove in the work piece by the laser beam applied to the work piece and the first height with respect to the upper surface of the work piece. While condensing the laser beam, the workpiece and the irradiation head are relatively moved in a direction along the upper surface, and the laser beam irradiating the workpiece is used to irradiate the workpiece. Based on the second processing step of forming the two grooves and the first image obtained by imaging the first groove from above, it corresponds to the distance between the reference position in the first image and the first groove. Based on the first deviation amount calculation step for calculating the first deviation amount to be performed and the second image obtained by imaging the second groove from above, the reference position in the second image and the second groove. The incident direction of the laser beam incident on the workpiece based on the second deviation amount calculation step for calculating the second deviation amount corresponding to the distance from and the first deviation amount and the second deviation amount. An inclination confirmation method including an inclination confirmation step for confirming the inclination with respect to the upper surface thereof is provided.

In the inclination confirmation method according to one aspect of the present invention, it is necessary to adjust the irradiation head as long as the inclination of the laser beam confirmed in the inclination confirmation step with respect to the upper surface in the incident direction is within an allowable range. If it is determined that the laser beam does not exist and the inclination of the laser beam confirmed in the inclination confirmation step with respect to the upper surface is out of the allowable range, the determination step of determining that the irradiation head needs to be adjusted is performed. May include more.

In the inclination confirmation method according to one aspect of the present invention, a laser beam is focused at a position of a first height to form a first groove in a work piece, and the first groove is imaged from above. Based on one image, the first deviation amount corresponding to the distance between the reference position in the first image and the first groove is calculated. Similarly, a second image is formed based on a second image obtained by condensing a laser beam at a position of a second height to form a second groove in a work piece and imaging the second groove from above. The second deviation amount corresponding to the distance between the reference position and the second groove is calculated.

Since the first groove and the second groove are formed at positions where the laser beam is irradiated on the upper surface of the work piece, the first deviation amount is the first groove from a predetermined position on the upper surface of the work piece. The second deviation amount represents the deviation of the second groove from a predetermined position on the upper surface of the workpiece. Therefore, it is possible to accurately confirm the inclination of the laser beam with respect to the workpiece in the incident direction based on the first deviation amount and the second deviation amount.

It is a perspective view which shows the structural example of the laser processing apparatus. It is a perspective view which shows the structural example of the work piece and the like. FIG. 3A is a side view showing how the laser beam is irradiated to the workpiece in a state where the height of the irradiation head is adjusted so that the laser beam is focused on the upper surface of the workpiece. FIG. 3B is a diagram showing an example of an image obtained by imaging a groove formed in a workpiece under the condition of FIG. 3A with an imaging unit. FIG. 4A shows the work piece being irradiated with the laser beam in a state where the height of the irradiation head is adjusted so that the laser beam is focused at the position of the first height with respect to the upper surface of the work piece. 4 (B) is a side view showing how the image is formed, and FIG. 4 (B) is a diagram showing an example of an image obtained by imaging the first groove formed in the workpiece under the conditions of FIG. 4 (A) with an imaging unit. Is. FIG. 5A shows the work piece being irradiated with the laser beam in a state where the height of the irradiation head is adjusted so that the laser beam is focused at the position of the second height with respect to the upper surface of the work piece. 5 (B) is a side view showing how the light beam is formed, and FIG. 5 (B) is a diagram showing an example of an image obtained by imaging the second groove formed in the workpiece under the condition of FIG. 5 (A) with an imaging unit. Is. FIG. 6A is a diagram schematically showing the relationship between the first deviation amount and the image, and FIG. 6B is a diagram schematically showing the relationship between the second deviation amount and the image.

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view showing a configuration example of a laser processing apparatus 2 in which the inclination confirmation method according to the present embodiment is used. In FIG. 1, some components of the laser processing apparatus 2 are shown by functional blocks. Further, the X-axis direction (machining feed direction), the Y-axis direction (indexing feed direction), and the Z-axis direction (height direction) used in the following description are perpendicular to each other.

As shown in FIG. 1, the laser processing apparatus 2 includes a base 4 that supports each component. A horizontal movement mechanism (machining feed mechanism, indexing feed mechanism) 6 is arranged on the upper surface of the base 4. The horizontal movement mechanism 6 includes a pair of Y-axis guide rails 8 fixed to the upper surface of the base 4 and substantially parallel to the Y-axis direction. A Y-axis moving table 10 is slidably attached to the Y-axis guide rail 8.

A nut portion (not shown) is provided on the lower surface side of the Y-axis moving table 10. A Y-axis ball screw 12 substantially parallel to the Y-axis guide rail 8 is screwed into the nut portion of the Y-axis moving table 10. A Y-axis pulse motor 14 is connected to one end of the Y-axis ball screw 12. If the Y-axis ball screw 12 is rotated by the Y-axis pulse motor 14, the Y-axis moving table 10 moves in the Y-axis direction along the Y-axis guide rail 8.

A pair of X-axis guide rails 16 substantially parallel to the X-axis direction are provided on the upper surface of the Y-axis moving table 10. An X-axis moving table 18 is slidably attached to the X-axis guide rail 16. A nut portion (not shown) is provided on the lower surface side of the X-axis moving table 18.

An X-axis ball screw 20 substantially parallel to the X-axis guide rail 16 is screwed into the nut portion of the X-axis moving table 18. An X-axis pulse motor 22 is connected to one end of the X-axis ball screw 20. When the X-axis ball screw 20 is rotated by the X-axis pulse motor 22, the X-axis moving table 18 moves in the X-axis direction along the X-axis guide rail 16.

A columnar table base 24 is arranged on the upper surface side of the X-axis moving table 18. Further, a chuck table (holding table) 26 used for holding the workpiece 11 (see FIG. 2) is arranged on the upper part of the table base 24. A rotary drive source (not shown) such as a motor is connected to the lower part of the table base 24.

The force generated from this rotation drive source causes the chuck table 26 to rotate around a rotation axis that is substantially parallel to the Z-axis direction. Further, the table base 24 and the chuck table 26 are moved in the X-axis direction and the Y-axis direction by the horizontal movement mechanism 6 described above (machining feed, index feed).

FIG. 2 is a perspective view showing a configuration example of the workpiece 11 and the like. The workpiece 11 used in this embodiment is, for example, a disk-shaped wafer made of a semiconductor material such as silicon. As shown in FIG. 2, the workpiece 11 has an upper surface 11a and a lower surface 11b that are substantially flat and parallel to each other.

An adhesive tape (dicing tape) 13 having a diameter larger than that of the workpiece 11 is attached to the lower surface 11b of the workpiece 11. Further, an annular frame 15 is fixed to the outer peripheral portion of the adhesive tape 13. That is, the workpiece 11 is supported by the frame 15 via the adhesive tape 13.

In the present embodiment, the disk-shaped wafer made of a semiconductor material such as silicon is used as the workpiece 11, but the material, shape, structure, size, etc. of the workpiece 11 are not limited. For example, a substrate of any shape made of other materials such as semiconductors, ceramics, resins, and metals can be used as the workpiece 11. Further, if the work piece 11 can be appropriately held by the chuck table 26, the adhesive tape 13 does not necessarily have to be attached to the lower surface 11b of the work piece 11.

A part of the upper surface of the chuck table 26 is made of, for example, a porous material, and serves as a holding surface 26a for holding the workpiece 11. The holding surface 26a is formed substantially parallel to the X-axis direction and the Y-axis direction, and serves as a suction source (not shown) via a suction path (not shown) provided inside the chuck table 26. It is connected. Further, around the chuck table 26, four clamps 28 for fixing the annular frame 15 that supports the workpiece 11 are provided.

A columnar support structure 30 having a side surface substantially perpendicular to the X-axis direction is provided in a region on one side of the horizontal movement mechanism 6 in the Y-axis direction. A vertical movement mechanism (height adjustment mechanism) 32 is arranged on the side surface of the support structure 30. The vertical movement mechanism 32 includes a pair of Z-axis guide rails 34 fixed to the side surface of the support structure 30 and substantially parallel to the Z-axis direction. A Z-axis moving table 36 is slidably attached to the Z-axis guide rail 34.

A nut portion (not shown) is provided on the back surface side (Z-axis guide rail 34 side) of the Z-axis moving table 36. A Z-axis ball screw (not shown) substantially parallel to the Z-axis guide rail 34 is screwed into the nut portion of the Z-axis moving table 36. A Z-axis pulse motor 38 is connected to one end of the Z-axis ball screw. When the Z-axis ball screw is rotated by the Z-axis pulse motor 38, the Z-axis moving table 36 moves in the Z-axis direction along the Z-axis guide rail 34.

A support 40 is fixed to the surface side of the Z-axis moving table 36, and a part of the laser beam irradiation unit 42 is supported by the support 40. The laser beam irradiation unit 42 is provided, for example, at the laser oscillator (not shown) fixed to the base 4, the tubular housing 44 supported by the support 40, and the end portion of the housing 44 in the Y-axis direction. The irradiation head 46 and the like are included.

The laser oscillator includes, for example, a laser medium such as Nd: YAG suitable for laser oscillation, and generates a laser beam having a wavelength absorbed by the workpiece 11 and radiates it to the housing 44 side. The housing 44 accommodates a part of the optical system constituting the laser beam irradiation unit 42, and guides the laser beam emitted from the laser oscillator to the irradiation head 46. This optical system is mainly composed of optical components such as mirrors and lenses.

The irradiation head 46 is provided with another part of the optical system constituting the laser beam irradiation unit 42. For example, the irradiation head 46 changes the course of the laser beam guided from the housing 44 downward with a mirror (not shown) or the like, and has a predetermined height with a condensing lens 46a (see FIG. 3A or the like). Condenses on.

An imaging unit 48 fixed to the housing 44 of the laser beam irradiation unit 42 is arranged in a region on one side of the irradiation head 46 in the X-axis direction. The imaging unit 48 includes, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, a CCD (Charge Coupled Device) image sensor, and the like, and is used when imaging the upper surface 11a side of the workpiece 11 held by the chuck table 26. Be done.

The upper part of the base 4 is covered with a cover (not shown) capable of accommodating each component. A touch panel type display (input / output unit) 50 serving as a user interface is arranged on the side surface of the cover. For example, various conditions applied when processing the workpiece 11 are input to the laser processing apparatus 2 via the display 50. Further, the image generated by the image pickup unit 48 is displayed on the display 50.

The components such as the horizontal movement mechanism 6, the vertical movement mechanism 32, the laser beam irradiation unit 42, the image pickup unit 48, and the display 50 are each connected to the control unit (control unit) 52. The control unit 52 controls each of the above-mentioned components according to a series of steps required for processing the workpiece 11.

The control unit 52 is typically composed of a processing device such as a CPU (Central Processing Unit) and a computer including a storage device such as a flash memory. The function of the control unit 52 is realized by operating the processing device or the like according to the software stored in the storage device.

When processing the workpiece 11 using the laser machining apparatus 2, first, the workpiece 11 is placed on the chuck table 26 via the adhesive tape 13 attached to the lower surface 11b, and the negative pressure of the suction source is maintained. It acts on the surface 26a. As a result, the workpiece 11 is held by the chuck table 26, and the upper surface 11a thereof is exposed. The frame 15 is fixed by four clamps 28.

After the workpiece 11 is held by the chuck table 26, as shown in FIG. 2, the chuck table 26 is moved downward in the X-axis direction by the horizontal movement mechanism 6 from the irradiation head 46 of the laser beam irradiation unit 42. Irradiate the laser beam 21. The position (height) of the irradiation head 46 in the Z-axis direction is adjusted so that the laser beam 21 concentrates on, for example, the upper surface 11a of the workpiece 11.

As a result, the work piece 11 is irradiated with the laser beam 21 along the moving path of the chuck table 26, and the upper surface 11a side of the work piece 11 can be machined by the laser beam 21 (ablation processing). In the present embodiment, the workpiece 11 and the irradiation head 46 move relatively along the X-axis direction, so that the linear groove 11c along the X-axis direction is the workpiece 11 as shown in FIG. It is formed on the upper surface 11a side of the above.

As described above, the imaging unit 48 is fixed to the housing 44 of the laser beam irradiation unit 42, and is arranged in a region on one side in the X-axis direction with respect to the irradiation head 46. Therefore, for example, if the groove 11c is formed in the workpiece 11 and then the chuck table 26 is moved in the X-axis direction, the groove 11c can be imaged by the image pickup unit 48.

Next, the method of confirming the inclination of the present embodiment will be described in detail. FIG. 3A shows a state in which the laser beam 21 is irradiated to the workpiece 11 with the height of the irradiation head 46 adjusted so that the laser beam 21 concentrates on the upper surface 11a of the workpiece 11. It is a side view which shows. FIG. 3B is a diagram showing an example of an image 31a obtained by imaging a groove 11d formed in the workpiece 11 under the condition of FIG. 3A with the image pickup unit 48.

In the optical system included in the laser beam irradiation unit 42 of the present embodiment, for example, when the laser beam 21 is focused on the upper surface 11a of the workpiece 11, the laser beam 21 serves as a reference in the Y-axis direction. It is adjusted to focus on position 17. Therefore, under the condition of FIG. 3A in which the condensing point 23 of the laser beam 21 is positioned on the upper surface 11a of the workpiece 11, the groove 11d is formed at the reference position 17. In the image 31a of FIG. 3 (B), the position 17a corresponding to the position 17 of FIG. 3 (A) is indicated by a alternate long and short dash line.

In the inclination confirmation method of the present embodiment, first, the laser beam 21 is focused at a position of the first height with respect to the upper surface 11a of the workpiece 11, and the first groove is formed in the workpiece 11. (First processing step). FIG. 4A shows a work piece in a state where the height of the irradiation head 46 is adjusted so that the laser beam 21 concentrates on the position of the first height h1 with respect to the upper surface 11a of the work piece 11. 11 is a side view showing how the laser beam 21 is irradiated to 11.

Specifically, as shown in FIG. 4A, the vertical movement mechanism 32 irradiates the work piece 11 so that the laser beam 21 concentrates at the position of the first height h1 with respect to the upper surface 11a. Adjust the height of the head 46. Then, in this state, the chuck table 26 holding the workpiece 11 is moved in the X-axis direction by the horizontal movement mechanism 6 while irradiating the laser beam 21 downward from the irradiation head 46.

That is, the direction in which the workpiece 11 and the irradiation head 46 are aligned with the upper surface 11a of the workpiece 11 while condensing the laser beam 21 at the position of the first height h1 with respect to the upper surface 11a of the workpiece 11. Move relative to. As a result, the laser beam 21 that irradiates the workpiece 11 forms a linear first groove 11e (see FIG. 4B) along the X-axis direction on the upper surface 11a side of the workpiece 11.

In the present embodiment, the first height h1 with reference to the upper surface 11a of the workpiece 11 is set so that the laser beam 21 concentrates below the upper surface 11a of the workpiece 11. That is, the first height h1 of this embodiment has a negative value. However, there is no particular limitation on the value of the first height h1. For example, the first height h1 may be set to a positive value or zero.

After the first groove 11e is formed in the workpiece 11, the first groove 11e is imaged from above to obtain an image (first image acquisition step). FIG. 4B is a diagram showing an example of an image (first image) 31b obtained by imaging the first groove 11e with the imaging unit 48. In the image 31b of FIG. 4 (B), the position 17b corresponding to the position 17 of FIG. 4 (A) is indicated by a alternate long and short dash line.

Specifically, for example, after forming the first groove 11e in the workpiece 11, the chuck table 26 is moved in the X-axis direction to position the first groove 11e below the image pickup unit 48. Then, the image pickup unit 48 images the lower first groove 11e. The image 31b obtained by the image pickup unit 48 is stored in, for example, the control unit 52, and is displayed on the display 50 as needed.

As described above, in the optical system of the laser beam irradiation unit 42 of the present embodiment, when the laser beam 21 is focused on the upper surface 11a of the workpiece 11, the laser beam 21 serves as a reference in the Y-axis direction. It is adjusted to focus on a predetermined position 17. Therefore, when the center line 21a of the laser beam 21 irradiated to the workpiece 11 is tilted and the focusing point 23 of the laser beam 21 is positioned below the upper surface 11a of the workpiece 11, FIG. 4 (A) ), The intersection of the upper surface 11a and the center line 21a deviates from the reference position 17.

There are various reasons why the center line 21a of the laser beam 21 irradiated to the workpiece 11 is tilted. In the present embodiment, when the laser beam 21 asymmetrical with respect to the central axis (optical axis) 46b of the lens 46a is incident on the lens 46a, the center line 21a of the laser beam 21 irradiated to the workpiece 11 is tilted. Is illustrated. In addition, when the laser beam 21 that is non-parallel to the central axis 46b is incident on the lens 46a, the center line 21a of the laser beam 21 that irradiates the workpiece 11 is tilted.

Since the central position of the first groove 11e in the width direction (Y-axis direction) roughly coincides with the intersection of the upper surface 11a and the center line 21a, the central position of the first groove 11e in the width direction is also a reference. It will deviate from the position 17. Therefore, when the first groove 11e is imaged from above by the image pickup unit 48, the image 31b as shown in FIG. 4B can be obtained.

Since the center line 21a of the laser beam 21 irradiated to the workpiece 11 is substantially parallel to the incident direction 21b of the laser beam 21 with respect to the workpiece 11, the inclination of the incident direction 21b is approximately equal to the inclination of the center line 21a. Become equal. The x-axis direction and the y-axis direction of the image 31b correspond to the X-axis direction and the Y-axis direction of the laser processing apparatus 2, respectively.

After obtaining the image 31b, the laser beam 21 is focused at a position of a second height different from the first height h1 to form a second groove in the workpiece 11 (second processing step). .. FIG. 5A shows a work piece in a state where the height of the irradiation head 46 is adjusted so that the laser beam 21 concentrates on the position of the second height h2 with respect to the upper surface 11a of the work piece 11. 11 is a side view showing how the laser beam 21 is irradiated to 11.

Specifically, the chuck table 26 is moved in the Y-axis direction by the horizontal movement mechanism 6, and the region where the first groove 11e of the workpiece 11 is not formed is positioned below the irradiation head 46. However, this operation may be omitted as long as the second groove can be formed at a position that does not overlap with the first groove 11e.

Further, as shown in FIG. 5A, the vertical movement mechanism 32 of the irradiation head 46 so that the laser beam 21 concentrates at the position of the second height h2 with respect to the upper surface 11a of the workpiece 11. Adjust the height. Then, in this state, the chuck table 26 holding the workpiece 11 is moved in the X-axis direction by the horizontal movement mechanism 6 while irradiating the laser beam 21 downward from the irradiation head 46.

That is, the workpiece 11 and the irradiation head 46 are to be processed while condensing the laser beam 21 at a position of the second height h2 different from the first height h1 with respect to the upper surface 11a of the workpiece 11. It is relatively moved in the direction along the upper surface 11a of the object 11. As a result, the laser beam 21 that irradiates the workpiece 11 forms a linear second groove 11f (see FIG. 5B) along the X-axis direction on the upper surface 11a side of the workpiece 11.

In the present embodiment, the second height h2 with reference to the upper surface 11a of the workpiece 11 is set so that the laser beam 21 concentrates above the upper surface 11a of the workpiece 11. That is, the second height h2 of this embodiment has a positive value. However, as long as the value of the first height h1 and the value of the second height h2 are different, the value of the second height h2 is not particularly limited. For example, the second height h2 may be set to a negative value or zero.

After the second groove 11f is formed in the workpiece 11, the second groove 11f is imaged from above to obtain an image (second image acquisition step). FIG. 5B is a diagram showing an example of an image (second image) 31c obtained by imaging the second groove 11f with the imaging unit 48. In the image 31c of FIG. 5 (B), the position 17c corresponding to the position 17 of FIG. 5 (A) is indicated by a alternate long and short dash line.

Specifically, for example, after forming the second groove 11f in the workpiece 11, the chuck table 26 is moved in the X-axis direction to position the second groove 11f below the image pickup unit 48. Then, the image pickup unit 48 images the lower second groove 11f. The image 31c obtained by the image pickup unit 48 is stored in, for example, the control unit 52, and is displayed on the display 50 as needed.

As described above, in the optical system of the laser beam irradiation unit 42 of the present embodiment, when the laser beam 21 is focused on the upper surface 11a of the workpiece 11, the laser beam 21 serves as a reference in the Y-axis direction. It is adjusted to focus on a predetermined position 17. Therefore, when the center line 21a of the laser beam 21 irradiated to the workpiece 11 is tilted and the focusing point 23 of the laser beam 21 is positioned above the upper surface 11a of the workpiece 11, FIG. 5 (A) ), The intersection of the upper surface 11a and the center line 21a deviates from the reference position 17.

Since the central position of the second groove 11f in the width direction (Y-axis direction) roughly coincides with the intersection of the upper surface 11a and the center line 21a, the central position of the second groove 11f in the width direction is also a reference. It will deviate from the position 17. Therefore, when the second groove 11f is imaged from above by the image pickup unit 48, the image 31c as shown in FIG. 5B can be obtained.

Since the center line 21a of the laser beam 21 irradiated to the workpiece 11 is substantially parallel to the incident direction 21b of the laser beam 21 with respect to the workpiece 11, the inclination of the incident direction 21b is approximately equal to the inclination of the center line 21a. Become equal. The x-axis direction and the y-axis direction of the image 31c correspond to the X-axis direction and the Y-axis direction of the laser processing apparatus 2, respectively.

After the first groove 11e is imaged to obtain the image 31b, the first deviation amount corresponding to the distance between the reference position 17b in the image 31b and the first groove 11e is calculated based on the image 31b ( First deviation amount calculation step). FIG. 6A is a diagram schematically showing the relationship between the first deviation amount y1 and the image 31b.

Specifically, for example, the control unit 52 performs processing such as edge detection on the image 31b, and calculates the y-coordinate values of the two edges of the first groove 11e, respectively. Then, from the y-coordinate values of the two edges of the first groove 11e, the y-coordinate value of the central position 33b in the width direction (y-axis direction) of the first groove 11e is calculated. The calculated y-coordinate value of the position 33b is stored in the control unit 52.

After that, the control unit 52 calculates the first deviation amount y1 from the y-coordinate value of the position 33b and the y-coordinate value of the reference position 17b in the image 31b. That is, in the present embodiment, the difference between the y-coordinate value of the position 33b and the y-coordinate value of the position 17b is set as the first deviation amount y1. The calculated value of the first deviation amount y1 is stored in the control unit 52.

Similarly, after the second groove 11f is imaged to obtain the image 31c, the second deviation amount corresponding to the distance between the reference position 17c in the image 31c and the second groove 11f is determined based on the image 31c. Calculate (second deviation amount calculation step). FIG. 6B is a diagram schematically showing the relationship between the second deviation amount y2 and the image 31c.

Specifically, for example, the control unit 52 performs processing such as edge detection on the image 31c, and calculates the y-coordinate values of the two edges of the second groove 11f, respectively. Then, from the y-coordinate values of the two edges of the second groove 11f, the y-coordinate value of the central position 33c in the width direction (y-axis direction) of the second groove 11f is calculated. The calculated y-coordinate value of the position 33c is stored in the control unit 52.

After that, the control unit 52 calculates the second deviation amount y2 from the y-coordinate value of the position 33c and the y-coordinate value of the reference position 17c in the image 31c. That is, in the present embodiment, the difference between the y-coordinate value at the position 33c and the y-coordinate value at the position 17c is defined as the second deviation amount y2. The calculated value of the second deviation amount y2 is stored in the control unit 52.

As described above, the relationship between the position of the irradiation head 46 and the position of the imaging unit 48 is constant and does not change. That is, the y-coordinate value of the position 17b in the image 31b obtained by the procedure as described above and the y-coordinate value of the position 17c in the image 31c are substantially equal.

Therefore, it is not necessary for the control unit 52 to perform any processing in order to acquire the y-coordinate value of the position 17b and the y-coordinate value of the position 17c. Further, in the present embodiment, the reference position is displayed in the image acquired by the image pickup unit 48, but the reference position does not necessarily have to be displayed in the image.

After calculating the first deviation amount y1 and the second deviation amount y2, the inclination of the incident direction 21b with respect to the upper surface 11a of the workpiece 11 is confirmed based on the first deviation amount y1 and the second deviation amount y2. (Tilt confirmation step). As described above, when the groove is formed in the workpiece 11 under the condition that the height of the irradiation head 46 with respect to the workpiece 11 is different, the incident direction 21b is tilted (that is, the center line 21a is tilted). In the case), the center position in the width direction (Y-axis direction) of each groove will be displaced.

More specifically, when the inclination of the incident direction 21b is large, the difference between the first deviation amount y1 and the second deviation amount y2 is also large, and when the inclination of the incident direction 21b is small, the first deviation amount y1 and the second deviation amount y1 and the second. The difference from the deviation amount y2 is also small. That is, the difference between the first deviation amount y1 and the second deviation amount y2 takes a value corresponding to the inclination of the incident direction 21b of the laser beam 21. Therefore, for example, the inclination of the incident direction 21b with respect to the upper surface 11a can be confirmed based on the difference between the first deviation amount y1 and the second deviation amount y2.

The confirmation of the inclination of the incident direction 21b is performed by, for example, an operator. Of course, the inclination of the incident direction 21b may be confirmed by arithmetic processing of the control unit 52 or the like. In addition, there are no particular restrictions on the specific confirmation method. For example, the angle of inclination in the incident direction 21b can be calculated based on the first deviation amount y1 and the second deviation amount y2.

As described above, in the inclination confirmation method according to the present embodiment, the laser beam 21 is focused at the position of the first height h1 to form the first groove 11e in the workpiece 11, and the first groove 11e is formed. Based on the image (first image) 31b obtained by imaging from above, the first deviation amount corresponding to the distance between the reference position 17b in the image 31b and the central position 33b in the width direction of the first groove 11e. Calculate y1.

Similarly, an image obtained by condensing the laser beam 21 at the position of the second height h2 to form the second groove 11f in the workpiece 11 and imaging the second groove 11f from above (second image). ) 31c, the second deviation amount y2 corresponding to the distance between the reference position 17c in the image 31c and the central position 33c in the width direction of the second groove 11f is calculated.

Since the first groove 11e and the second groove 11f are formed at positions where the laser beam 21 on the upper surface 11a of the workpiece 11 is irradiated, the first deviation amount y1 is the upper surface 11a of the workpiece 11. The deviation of the first groove 11e from the predetermined position 17 is represented, and the second deviation amount y2 represents the deviation of the second groove 11f from the predetermined position 17 of the upper surface 11a of the workpiece 11. Therefore, the inclination of the laser beam 21 with respect to the workpiece 11 in the incident direction 21b can be accurately confirmed based on the first deviation amount y1 and the second deviation amount y2.

The present invention is not limited to the description of the above-described embodiment, and can be implemented with various modifications. For example, after confirming the inclination of the incident direction 21b of the laser beam 21 by the procedure of the above-described embodiment, it is further determined whether or not it is necessary to adjust the irradiation head 46 or the like (optical system) of the laser beam irradiation unit 42. May be done (judgment step).

In this case, for example, if the difference between the first deviation amount y1 and the second deviation amount y2 corresponding to the inclination of the incident direction 21b is within an allowable range, it is not necessary to adjust the irradiation head 46 or the like. judge. Further, if the difference between the first deviation amount y1 and the second deviation amount y2 is out of the allowable range, it is determined that the irradiation head 46 or the like needs to be adjusted. The permissible range is, for example, −5 μm or more and + 5 μm or less, preferably -3 μm or more and + 3 μm or less in terms of the actual length.

That is, if the confirmed inclination of the incident direction 21b is within the allowable range, it is determined that it is not necessary to adjust the irradiation head 46 or the like, and the confirmed inclination of the incident direction 21b is outside the allowable range. For example, it is determined that the irradiation head 46 and the like need to be adjusted. It should be noted that this determination may be made by the control unit 52 or by the operator.

Further, in the above-described embodiment, as shown in FIGS. 4 (A) and 5 (A), the inclination of the incident direction 21b in the YZ plane is confirmed, but the same procedure is used to confirm the inclination in the XZ plane. You may check the inclination of the incident direction 21b. Specifically, by exchanging the relationship between the X-axis direction (y-axis direction) and the Y-axis direction (y-axis direction) of the above-described embodiment, the inclination of the incident direction 21b in the XZ plane can be confirmed.

Further, in the above-described embodiment, the image 31b is acquired after the first groove 11e is formed on the workpiece 11, and the image 31c is acquired after the second groove 11f is formed on the workpiece 11. However, this procedure can be changed arbitrarily as long as there is no contradiction. For example, the image 31b and the image 31c may be acquired after the first groove 11e and the first groove 11e are formed on the workpiece 11. Similarly, other procedures can be changed arbitrarily without causing inconsistency.

Further, in the above-described embodiment, the inclination of the incident direction 21b is confirmed based on the two deviation amounts corresponding to the two grooves formed under different conditions, but three or more grooves formed under different conditions. You may calculate the amount of deviation corresponding to 3 or more and confirm the inclination of the incident direction 21b based on the amount of deviation of 3 or more. In this case, the inclination of the incident direction 21b can be confirmed with higher accuracy.

Further, in the above-described embodiment, the deviation amount is calculated based on the value of the y coordinate of the center position in the width direction (y-axis direction) of each groove, and this deviation amount is the reference position and each. Anything corresponding to the distance to the groove may be used. For example, when there is no large difference in the widths of the plurality of grooves formed under different conditions, the deviation amount can be calculated based on the y-coordinate value of the edge of each groove. That is, the difference between the y-coordinate value of the reference position and the y-coordinate value of the edge of each groove can be used as the deviation amount.

Further, in the above-described embodiment, when the laser beam 21 is focused on the upper surface 11a of the workpiece 11, the position in the Y-axis direction (y-axis direction) where the laser beam 21 is focused is used as a reference. Although it is set to the position 17, the reference position is arbitrarily set. For example, the position corresponding to the end of the acquired image can be set as a reference position.

Further, in the optical system of the laser beam irradiation unit 42 of the above-described embodiment, when the laser beam 21 is focused on the upper surface 11a of the workpiece 11, the laser beam 21 becomes a reference position 17 in the Y-axis direction. Although it is adjusted to focus on the laser, such adjustment does not necessarily have to be performed. Further, in the above-described embodiment, the control unit 52 calculates the first deviation amount y1 and the second deviation amount y2, but the operator may calculate the deviation amount. Further, the first groove 11e and the second groove 11f may be formed on different workpieces 11.

In addition, the structures, methods, and the like according to the above-described embodiments and modifications can be appropriately modified and implemented without departing from the scope of the object of the present invention.

11: Work piece 11a: Upper surface 11b: Lower surface 11c: Groove 11d: Groove 11e: First groove 11f: Second groove 13: Adhesive tape (dicing tape)
15: Frame 21: Laser beam 21a: Center line 21b: Incident direction 23: Condensing point 31a: Image 31b: Image (first image)
31c: Image (second image)
y1: 1st deviation amount y2: 2nd deviation amount 2: Laser machining device 4: Base 6: Horizontal movement mechanism (machining feed mechanism, indexing feed mechanism)
8: Y-axis guide rail 10: Y-axis moving table 12: Y-axis ball screw 14: Y-axis pulse motor 16: X-axis guide rail 18: X-axis moving table 20: X-axis ball screw 22: X-axis pulse motor 24: Table base Table 26: Chuck table (holding table)
26a: Holding surface 28: Clamp 30: Support structure 32: Vertical movement mechanism (height adjustment mechanism)
34: Z-axis guide rail 36: Z-axis moving table 38: Z-axis pulse motor 40: Support 42: Laser beam irradiation unit 44: Housing 46: Irradiation head 46a: Lens 46b: Central axis (optical axis)
48: Imaging unit 50: Display (input / output unit)
52: Control unit (control unit)

Claims (2)

This is a tilt confirmation method for confirming the tilt of a laser beam having a wavelength that is irradiated to a work piece from the irradiation head of the laser beam irradiation unit and is absorbed by the work piece.
While condensing the laser beam at a position at a first height with respect to the upper surface of the work piece, the work piece and the irradiation head are relatively moved in a direction along the upper surface to be processed. A first processing step of forming a first groove in the work piece with the laser beam applied to the object, and
While condensing the laser beam at a position of a second height different from the first height with respect to the upper surface of the work piece, the work piece and the irradiation head are relatively relative to the direction along the upper surface. A second machining step of moving and forming a second groove in the workpiece with the laser beam irradiated to the workpiece.
The first deviation that corresponds to the distance between the reference position in the first image and the first groove is calculated based on the first image obtained by imaging the first groove from above. Amount calculation step and
A second deviation that calculates a second deviation amount corresponding to the distance between the reference position in the second image and the second groove based on the second image obtained by imaging the second groove from above. Amount calculation step and
An inclination that includes an inclination confirmation step for confirming the inclination of the laser beam incident on the workpiece with respect to the upper surface in the incident direction based on the first deviation amount and the second deviation amount. Confirmation method. If the inclination of the laser beam confirmed in the inclination confirmation step with respect to the upper surface in the incident direction is within an allowable range, it is determined that the irradiation head does not need to be adjusted, and the laser beam is confirmed in the inclination confirmation step. The first aspect of the present invention is characterized in that the determination step of determining that the irradiation head needs to be adjusted is further included if the inclination of the laser beam with respect to the upper surface in the incident direction is out of the allowable range. How to check the inclination of.