KR20140143478A - Apparatus for laser processing, system and method for real-time inspection of laser processing - Google Patents

Abstract

Disclosed are a laser processing apparatus, and a real-time inspection system and method of the laser processing. The laser processing apparatus comprises an optical unit providing a laser beam for processing; a real-time inspection system of the laser processing; and an objective lens condensing laser beam for the processing to an object to be processed from the optical unit. The real-time inspection system of the laser processing includes an optical path conversion part which is located between the optical unit and the objective lens to convert a progress path of incident beam; and an optical detector to generate a processing status detect signal in real time by receiving the back scattering beam which is scattered from the object to be processed to the rearward and processed to pass the optical path conversion part.

Description

TECHNICAL FIELD [0001] The present invention relates to a laser processing apparatus, a real-time inspection system and method for laser processing,

The present invention relates to a laser processing apparatus and a real-time inspection system and method for laser processing. More particularly, the present invention relates to a laser processing apparatus and a real-time inspection system and method for laser processing capable of enhancing reliability of laser processing.

A laser processing apparatus irradiates an object to be processed with a laser beam emitted from a laser oscillator through a scanner. Accordingly, laser processing such as marking, exposure, etching, punching, and scribing on one plane of the object or dicing using a stealth dicing method can be performed.

For laser machined objects, quality inspection is required to ensure that they are processed properly. When the reliability of the laser machining is low, it is necessary to perform a complete inspection and the like, so that the processing cost is very high and the inspection time is long.

The present invention provides a laser processing apparatus and a real-time inspection system and method for laser processing, which can perform real-time inspection during laser processing so as to increase the reliability of laser processing and reduce the necessity of total inspection.

A laser machining apparatus according to an embodiment of the present invention includes an optical unit for providing a laser beam for machining; A real time inspection system of laser machining; And an objective lens for converging a working laser beam provided from the optical unit onto an object to be processed, wherein the real time inspection system for laser processing is disposed between the optical unit and the objective lens, A light path changing unit; And a photodetector which scatters backward from the object to be processed and receives a backscattering beam traveling through the light path changing portion to generate a processing state detection signal in real time.

The optical unit can provide a polarized processing laser beam.

The optical path changing unit includes: a polarization beam splitter; And a wavelength plate disposed between the polarizing beam splitter and the objective lens for changing the polarization of the incident beam.

And an automatic focusing system for controlling a position where the processing laser beam is irradiated in the object to be processed.

The autofocus system comprises: an auxiliary light source for emitting an auxiliary beam; A light path changing unit for changing the traveling path of the incident auxiliary beam; An optical detecting unit that receives the auxiliary beam reflected from the object to be processed and detects the depth of the object to be processed with the processing laser beam; And an optical path separator / combiner that combines the optical path of the auxiliary beam and the processing laser beam toward the object and separates the optical path of the auxiliary beam and the backward scattered beam reflected from the object.

The optical path separator / coupler may be arranged to reflect any one of the auxiliary beam and the working laser beam and transmit the other.

Wherein the auxiliary beam has a wavelength different from that of the working laser beam and the optical path separator / coupler includes a dichroic mirror for reflecting one of the auxiliary beam and the working laser beam having different wavelengths and transmitting the other, have.

The autofocusing system may be arranged to irradiate the object to be processed coaxially with the working beam.

And a lens unit for adjusting the focal length of the auxiliary beam between the optical detection unit and the optical path combining / separating unit.

The lens unit may include a plurality of lenses, and may be provided to adjust the position of at least one of the plurality of lenses along an optical axis.

The optical detection unit may be arranged to detect a focusing signal by an astigmatism method.

The photodetecting unit includes: an astigmatic lens for generating astigmatism; And a quadrant photodetector for detecting the focusing signal by the astigmatism method.

And an actuator that adjusts the position of the objective lens along an optical axis so as to adjust the irradiation depth of the laser beam for processing by driving the objective lens.

And an aperture limiting member disposed at a front end of the photodetector for blocking a backscattered beam in an adjacent processing layer of the object to be processed.

A method for real-time inspection of a machining state using a laser machining apparatus according to an embodiment of the present invention includes the steps of condensing a machining laser beam onto an object to be machined; And generating a machining state detection signal in real time by receiving a backscattering beam scattered rearward from the machining area of the machining target layer while processing the machining target with the machining laser beam.

A real-time inspection system for laser processing according to an embodiment of the present invention includes: a light source for emitting a beam; An objective lens for focusing a beam emitted from the light source onto a processing target layer of the object to be processed; A light path changing unit positioned between the light source and the objective lens for changing the path of the incident beam; And a photodetector for detecting a backscattering beam scattered rearward from an area to be processed of the processing target layer while processing the processing target layer to detect a processing state in real time during processing of the processing target layer.

The light source may be a light source for providing a working laser beam for processing the processing target layer of the object to be processed.

The backscattering beam may be scattered rearward by the processing region from the processing laser beam irradiated on the processing region of the processing target layer.

According to the laser machining apparatus and the real-time inspection system and method of laser machining according to the embodiment of the present invention, it is possible to check the laser machining state in real time during laser machining, thereby enhancing the reliability of laser machining, Can be reduced.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an optical configuration diagram schematically showing an overall system of a laser processing apparatus according to an embodiment of the present invention; FIG.
Fig. 2 schematically shows the construction of a real-time inspection system in the laser machining apparatus of Fig. 1. Fig.
FIG. 3 shows that real-time inspection of laser machining is possible even when a plurality of machining layers are formed in the real time inspection system of laser machining according to the embodiment of the present invention.
4A to 4C show the shape changes of the light spot received by the quadrant photodetector according to the change in the distance between the objective lens and the cover layer of the object to be processed.
Figure 5 shows the S-curve of the focus error signal (FES).

Hereinafter, a laser processing apparatus and method according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements, and the size or thickness of each element may be exaggerated for clarity of explanation.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an optical configuration diagram schematically showing an overall system of a laser processing apparatus according to an embodiment of the present invention; FIG. The laser processing apparatus according to the embodiment of the present invention can be provided to check the machining state in real time. That is, another laser processing apparatus according to an embodiment of the present invention includes a real time inspection system for laser processing. Fig. 2 schematically shows the construction of a real-time inspection system in the laser machining apparatus of Fig. 1. Fig.

1 and 2, the laser processing apparatus includes an optical unit 30 for providing a processing laser beam 31, a real time inspection system 50 for laser processing, And an objective lens 90 for converging the working laser beam 31 onto the object 10 to be processed. The real-time inspection system 50 includes an optical path changing unit 51 positioned between the optical unit 30 and the objective lens 90 to change the traveling path of the incident beam, And a photodetector 57 that receives the backscattered beam that is scattered and travels through the optical path changing unit 51 to generate a processing state detection signal in real time. The objective lens 90 and the processing laser beam 31 may be components of the real-time inspection system 50.

The optical unit 30 includes a laser beam source for emitting a processing laser beam 31 and may have various optical configurations so as to irradiate an object to be processed 10 with an appropriate processing laser beam. The optical unit 30 may be provided to provide a polarized laser beam 31 for processing.

The optical path changing section 51 causes the processing laser beam 31 incident from the optical unit 30 to proceed toward the objective lens 90 and causes the processing target layer 11 of the object 10 to be processed The backscattered beam, which is backscattered from the region, travels toward the photodetector 57 to change the path of the incident beam.

In Fig. 1, the optical path changing section 51 exemplarily shows a case in which the optical unit 30 is provided to be suitable for providing the polarized processing laser beam 31. Fig. For example, the optical path changing unit 51 includes a polarizing beam splitter 52 for transmitting or reflecting an incident beam in accordance with the polarized light, and a polarizing beam splitter 52 positioned between the polarizing beam splitter 52 and the objective lens 90, And a wavelength plate 53 for changing the polarization of the beam. The wave plate 53 may be a quarter wave plate with respect to the wavelength of the laser beam 31 for processing. In this case, the polarized processing laser beam 31 incident from the optical unit 30 travels toward the object 10 via the polarizing beam splitter 52 and is directed to the object 10 of the object 10 to be processed 10 The backscattered beam, which is backscattered from the processing region, proceeds to the photodetector 57 via the polarizing beam splitter 52. 1, the polarized processing laser beam 31 incident from the optical unit 30 is transmitted through the polarizing beam splitter 52 to the object to be processed 10 and the backscattered beam is reflected by the polarizing beam splitter 52 And is directed to the photodetector 57. Here, the polarized processing laser beam 31 incident from the optical unit 30 is reflected by the polarization beam splitter 52 and travels toward the object 10, and the backscattered beam is transmitted through the polarization beam splitter 52 It may be configured to be directed to the photodetector 57.

The objective lens 90 condenses the processing laser beam 31 provided from the optical unit 30 onto the object 10 so that the object lens 90 can be mounted on the actuator 100 so as to be driven along the optical axis .

The actuator 100 is a high-speed actuator having a center hole 101 through which a processing laser beam 31 passes and is capable of precisely and rapidly rotating the objective lens 90 with a piezoelectric element at a high speed, for example, And can be provided so as to be able to drive along the optical axis at high speed. The objective lens 90 may be mounted on the actuator 100 so that the processing laser beam 31 can be irradiated onto the object 10 through the center hole 101 of the actuator 100. [ The objective lens 90 is disposed on the optical path in a state of being mounted on the actuator 100. [

The objective lens 90 is moved along the optical axis in accordance with the driving of the actuator 100 so that laser processing can be performed on the desired processing layer 11 of the object 10 at the optimum focusing position. Here, the processing target layer 11 may correspond to a layer formed by the processing region obtained by processing the object 10 at a certain depth. It is possible to adjust the focusing depth of the processing laser beam 31 in the object 10 by adjusting the focusing position by driving the objective lens 90. According to the adjustment of the focusing depth, The target layer 11 can be formed. 1 shows a case where four objects to be processed 11 are formed on an object 10 to be processed.

The laser machining apparatus according to the embodiment of the present invention includes a spherical aberration correcting unit 60 for correcting spherical aberration generated as the depth of the processing laser beam 31 is changed within the object 10 . 1, the spherical aberration correction unit 60 is provided between the optical unit 30 and the objective lens 90, more specifically, between the optical path changing unit 51 and the optical path separator / combiner 80 described later And is disposed on the optical path. The spherical aberration correction unit 60 may be included in the optical unit 30.

According to the laser processing real time inspection system 50 and the laser processing apparatus using the laser processing according to the embodiment of the present invention as described above, a part of the processing laser beam 31 irradiated on the processing target layer 11 for laser processing Back scattering is performed by the machining area. By detecting the back scattering beam with the photodetector 57, it is possible to check in real time whether the laser machining is properly performed. Whether or not the laser processing is properly performed can be known from the light amount change of the backscattering beam.

FIG. 3 shows that, in a real time inspection system 50 for laser processing according to an embodiment of the present invention, real time inspection of laser processing is possible even when a plurality of processing layers are formed.

3, the first processing target layer L1 of the object to be processed 10 near the side where the processing laser beam 31 is incident is laser-processed first, and then the second processing target layer L2 on the far side is laser- Let's consider the case.

3, the processing laser beam 31 is focused on the first processing target layer L1, and a beam backscattered from the first processing target layer L1 is received by the photodetector 57 , The laser processing state is checked in real time for the first processing target layer (L1).

3, in the case where the second processing target layer L2 on the far side is laser-processed while the first processing target layer L1 is formed, the processing laser beam 31 is focused on the first processing target layer L1 Passes through the processing target layer L1 and is focused on the second processing target layer L2. The beam reflected back from the second processing target layer L2 is received by the photodetector 57 and the laser processing state is checked in real time for the second processing target layer L2. At this time, at the time of processing the second processing target layer (L2), the processing laser beam (31) reaches the second processing target layer (L2) via the first processing target layer (L1) 1 processing object layer 11 in the backward direction. However, the beam width S1 when passing through the first processing target layer L1 of the processing laser beam 31 focused on the second processing target layer L2 is smaller than the beam width S1 of the processing area 11a of the first processing target layer L1 The beam intensity per unit area is so small that the beam backscattered from the first processing target layer L1 does not significantly affect the real time processing state detection signal of the second processing target layer L2, It is possible to accurately detect the real-time processing state of the second processing target layer L2.

Conversely, when the first processing target layer L1 is formed by laser processing after the second processing target layer L2 is formed by laser processing first, referring to the left part of FIG. 3, A portion of the processing laser beam 31 reaches the second processing target layer L2 which is an adjacent processing layer via the first processing target layer L1 and is rearwardly scattered by the second processing target layer L2 do.

A real-time inspection system 50 according to an embodiment of the present invention is configured to block at least a portion of a backscattering beam in an adjacent processing layer so as to improve the quality of the real- Similarly, at the front end of the photodetector 57, the opening limiting member 55 for blocking the back scattering beam in the adjacent processing layer of the object 10 may be further provided. The opening defining member 55 may be provided so as to adjust its position along the optical axis. Whereby the aperture limiting member 55 can better block the backscattering beam in the adjacent processing layer.

The laser processing apparatus according to the embodiment of the present invention may further include an automatic focusing system 70 for controlling the position where the processing laser beam 31 is irradiated in the object 10.

The automatic focus adjustment system 70 includes an auxiliary light source 71 for emitting the auxiliary beam 71a, a light path changing unit 73 for changing the path of the incident auxiliary beam, A photodetection unit 76 for receiving the reflected auxiliary beam 71b and detecting the depth of irradiation of the processing object 10 with the processing laser beam 31 and an auxiliary beam 71a And an optical path separator / combiner 80 for separating the optical path of the auxiliary beam 71b and the backward scattering beam 50a reflected from the object 10 from the optical path of the processing laser beam 31 and the optical path of the processing laser beam 31 . The automatic focus adjustment system 70 may be provided to irradiate the object 10 with the auxiliary beam coaxially with the processing laser beam 31. [

The auxiliary light source 71 may be arranged to emit an auxiliary beam having a wavelength different from that of the processing laser beam 31. [ For example, the auxiliary light source 71 may be provided to emit an auxiliary beam having a wavelength of approximately 635 nm to 650 nm. The auxiliary light source 71 does not necessarily have to be a laser light source. That is, the auxiliary light source 71 can use any kind of light source such as a laser light source or a light emitting diode (LED) light source, as long as the auxiliary beam reflected from the object 10 can be detected by the optical detection unit 76 have.

The optical path changing unit 73 directs the auxiliary beam emitted from the auxiliary light source 71 to the optical path separator / combiner 80, and the auxiliary beam reflected from the object to be processed 10, Unit 76 so as to change the traveling path of the incident auxiliary beam.

In FIG. 1, the optical path changing unit 73 exemplifies a case where the auxiliary light source 71 is provided to be suitable for providing the polarized auxiliary beam 71a. For example, the optical path changing section 73 includes a polarizing beam splitter 73a for transmitting or reflecting the auxiliary beam according to the polarized light, and a polarizing beam splitter 73b for positioning the polarizing beam splitter 73a and the optical path separating / And a wave plate 73b for changing the polarization of the incident auxiliary beam. The wave plate 73b may be a quarter wave plate with respect to the wavelength of the auxiliary beam. 1, the polarized auxiliary beam 71a incident from the auxiliary light source 71 is reflected by the polarizing beam splitter 73a and directed to the optical path separator / combiner 80. The auxiliary beam 71a reflected from the object 10 71b are configured to be transmitted to the polarization beam splitter 73a and directed to the optical detection unit 76. [ Here, the polarized auxiliary beam 71a incident from the auxiliary light source 71 is transmitted through the polarizing beam splitter 73a to the optical path separator / combiner 80, and the auxiliary beam 71b reflected from the object 10 May be reflected by the polarization beam splitter 73a and directed to the optical detection unit 76. [

The photodetection unit 76 may be arranged to detect a focusing signal by an astigmatism method. For example, the photodetector unit 76 may include an astigmatism lens 78 for generating an astigmatism and a quadrant photodetector 79 for detecting a focusing signal by an astigmatism method. A collimating lens 77 may be further included between the astigmatism lens 78 and the optical path changing unit 73. [

The optical path separator / combiner 80 may be arranged to reflect any one of the auxiliary beam 71a and the processing laser beam 31 and transmit the other. When the auxiliary light source 71 emits an auxiliary beam 71a having a wavelength different from that of the working laser beam 31, the auxiliary beam 71a having different wavelengths from the optical path separator / combiner 80, A dichroic mirror for reflecting one of the laser beams 31 and transmitting the other is used. 1 shows an example in which the optical path separator / coupler 80 reflects the auxiliary beam 71a and transmits the laser beam 31 for processing.

On the other hand, since the objective lens 90 optimally focuses on the working laser beam 31, it may be difficult to optimally focus the auxiliary beam 71a. In consideration of this, the focusing automatic focusing system 70 further includes a lens unit 75 for adjusting the focal distance of the auxiliary beam 71a between the optical detection unit 76 and the optical path separator / combiner 80 can do. The lens unit 75 includes a plurality of lenses, and may be provided to adjust the position of at least one of the plurality of lenses along an optical axis. 1, the lens unit 75 includes first and second lenses 75a and 75b, and the position of the first lens 75a is adjusted along the optical axis so that the first and second lenses 75a and 75b, Thereby adjusting the focusing position of the auxiliary beam 71a.

According to the above-described automatic focusing system 70, the auxiliary beam 71a is focused by the objective lens 90 onto the interface between the cover layer 15 of the object 10 and the processing layer 13 , And the position of the objective lens 90 is automatically adjusted in accordance with the signal detected by the optical detection unit 76.

For example, the distance between the objective lens 90 and the cover layer 15 of the object to be processed 10 is appropriate, and the auxiliary beam 71a is reflected by the cover layer 15 of the object 10 and the processing layer 13 , A light spot having a shape as shown in FIG. 4A is formed in the quadrant photodetector 79. In this case, as shown in FIG. The distance between the objective lens 90 and the cover layer 15 of the object to be processed 10 is too close so that the auxiliary beam 71a is not in contact with the interface between the cover layer 15 and the processing layer 13 of the object 10 In the case of far focusing, a light spot having the same shape as shown in FIG. 4B is formed in the quadrant photodetector 79. The distance between the objective lens 90 and the cover layer 15 of the object to be processed 10 is too far and the auxiliary beam 71a is not formed between the cover layer 15 of the object 10 and the processing layer 13 A light spot having a shape as shown in FIG. 4C is formed in the quadrant photodetector 79. The light spot of FIG.

Therefore, when the light receiving region of the quadrant photodetector 79 and the detection signals thereof are D1, D2, D3 and D4, the focus error signal FES by the astigmatism method is FES = (D1 + D3-D2-D4 ) / (D1 + D2 + D3 + D4), and the S-curve as shown in Fig. 5 is drawn.

When the position of the objective lens 90 is controlled by using the focus error signal FES, the focus can be automatically adjusted. That is, when the control point on the S-curve is determined according to the depth of the processing target layer 11, the irradiation depth of the processing laser beam 31 is adjusted by driving the objective lens 90, The objective lens 90 can be controlled so that laser processing is performed.

In the real time inspection of the laser processing in the laser processing apparatus according to the embodiment of the present invention as described above, the processing laser beam 31 is condensed on the object 10 and the object 10 is processed by the processing laser beam 31, And a back scattering beam scattered rearward from the processing region of the processing target layer 11 is received by the photodetector 57 while processing the processing target layer 11 to generate a processing state detection signal in real time.

10: object to be processed 11:
30 ... optical unit 31 ... working laser beam
50 ... real-time inspection system 51, 73 ... light path conversion section
52 ... polarizing beam splitter 53 ... wave plate
57 ... photodetector 70 ... automatic focusing system
71 ... auxiliary light source 76 ... optical detection unit
79 ... 4-split photodetector 80 ... optical path separator / combiner
90 ... Objective lens 100 ... Actuator

Claims (20)

An optical unit for providing a working laser beam;
A real time inspection system of laser machining;
And an objective lens for converging a working laser beam provided from the optical unit onto an object to be processed,
A real-time inspection system for laser machining comprises: a light path changing unit positioned between the optical unit and an objective lens, for changing a traveling path of an incident beam;
And a photodetector for receiving a backscattering beam scattered rearward from the object to be processed and traveling through the optical path changing portion to generate a processing state detection signal in real time. The laser processing apparatus according to claim 1, wherein the optical unit provides a polarized processing laser beam. 3. The apparatus according to claim 2,
A polarization beam splitter;
And a wavelength plate positioned between the polarizing beam splitter and the objective lens for changing the polarization of the incident beam. The laser processing apparatus according to any one of claims 1 to 3, further comprising an automatic focusing system for controlling a position at which the processing laser beam is irradiated in the object to be processed. 5. The system of claim 4,
An auxiliary light source for emitting an auxiliary beam;
A light path changing unit for changing the traveling path of the incident auxiliary beam;
An optical detecting unit that receives the auxiliary beam reflected from the object to be processed and detects the depth of the object to be processed with the processing laser beam;
And an optical path separator / combiner for coupling the optical path of the auxiliary beam and the working laser beam to the object to be processed and separating the optical path of the auxiliary beam and the backscattering beam reflected from the object. 6. The apparatus of claim 5, wherein the optical path separator /
Wherein one of the auxiliary beam and the working laser beam is reflected and the other is transmitted. 7. The apparatus according to claim 6, wherein the auxiliary beam has a different wavelength from the working laser beam,
The light path separating /
And a dichroic mirror for reflecting one of the auxiliary beam and the working laser beam having different wavelengths and transmitting the other. 6. The system of claim 5,
And the auxiliary beam is irradiated to the object to be processed coaxially with the processing laser beam. 6. The laser processing apparatus according to claim 5, further comprising: a lens unit between the optical detection unit and the optical path coupling / separator for adjusting a focal length of the auxiliary beam. 10. The image pickup apparatus according to claim 9, wherein the lens unit includes a plurality of lenses,
Wherein the position of at least one of the plurality of lenses is adjusted along an optical axis. The laser processing apparatus according to claim 5, wherein the optical detection unit is arranged to detect a focusing signal by an astigmatism method. 12. The optical pickup apparatus according to claim 11,
An astigmatic lens for generating astigmatism;
And a quadrant photodetector for detecting a focusing signal by an astigmatism method. The laser processing apparatus according to claim 1, further comprising an actuator for adjusting the position of the objective lens along an optical axis, wherein the irradiation depth of the processing laser beam is adjusted by driving the objective lens. The laser processing apparatus according to claim 1, further comprising: a aperture limiting member disposed at a front end of the photodetector for blocking a backscattered beam in an adjacent processing layer of the object to be processed. A method for real-time inspection of a processing state using the laser processing apparatus according to claim 1,
Converging the working laser beam on the object to be processed;
And generating a machining state detection signal in real time by receiving a backscattering beam scattered rearward from an machining area of the machining target layer while processing the machining target with the machining laser beam. The method of claim 1, wherein the backscattering beam from the adjacent processing layer of the object is blocked. A light source for emitting a beam;
An objective lens for focusing a beam emitted from the light source onto a processing target layer of the object to be processed;
A light path changing unit positioned between the light source and the objective lens for changing the path of the incident beam; And
And a photodetector for detecting a backward scattered beam scattered rearward from an area to be processed of the processing target layer while processing the processing target layer to detect a processing state in real time during the processing of the processing target layer, . 18. The system of claim 17, wherein the light source is a light source for providing a processing laser beam for processing a processing target layer of the object. 19. The system of claim 18, wherein the backscattering beam is a beam that is scattered rearward by the machining region from the machining laser beam irradiated to the machining region of the machining target layer. 18. The system of claim 17, further comprising: a aperture limiting member at the front end of the photodetector for blocking a backscattered beam in an adjacent processing layer of the object.

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