WO2008105631A1

WO2008105631A1 - Laser processing apparatus and method

Info

Publication number: WO2008105631A1
Application number: PCT/KR2008/001135
Authority: WO
Inventors: Eun Jeong Hong; Won Chul Jung; Tae Hyun Kim; Hak Yong Lee; Dong Jun Lee; Tae Kyoung Ryoo; Jae Kwan Lim
Original assignee: Eo Technics Co., Ltd.
Priority date: 2007-02-28
Filing date: 2008-02-27
Publication date: 2008-09-04
Also published as: KR20080079828A

Abstract

Disclosed are a laser processing apparatus and a method thereof that splits incident laser beam into at least two laser beams, transfers the stage in the direction opposing to the irradiation direction of the laser beam to process the object, thereby improving the processing quality of the object and the efficiency. A laser processing apparatus according to the invention includes; a beam splitting unit that splits a laser beam emitted from a laser generating unit into at least two laser beams; a beam scanner that receives the split laser beams from the beam splitting unit and reflects the beams so as to be repeatedly irradiated onto a processing position of the object; and a stage transfer unit that transfers at least once a stage on which the object is placed to the direction opposing to the irradiation direction of the laser beam during the processing of the object Therefore, since the same effect that the laser beam is irradiated plural times on the same processing surface with a low energy can be achieved, which secures the narrow beam width. Further, since the laser beam that is split into a plurality of laser beams is simultaneously irradiated onto the object, it is possible to secure the higher processing speed. Furthermore, it is possible to improve the processing speed by transferring the stage in a direction opposing to the irradiation direction of the laser beam.

Description

LASER PROCESSING APPARATUS AND METHOD

Technical Field

The present invention relates a laser processing apparatus and method, and more particularly, to a laser processing apparatus and method that splits the incident laser beam into at least two laser beams, moves a stage into a direction opposing to the irradiation direction of laser beam to process an object, which increase the quality of the processed object and the processing efficiency.

Related Art Generally, in order to manufacture products using materials such as wafers, metals, and plastics, processing such as cutting, grooving is required. Such a processing is significant because it considerably influences the quality and the productivity in the subsequence processes.

For the sake of such processing, laser is recently used. The processing method, which uses laser, converges a high wavelength laser beam of ultraviolet rays (250 to 360 run) onto a surface of the object to cause heating and chemical reaction, thereby remove the converged part.

In recent semiconductor market, in order to increase the chip productivity per wafer, the number of chips per wafer is increased by decreasing the distance between the chips on the wafer. Accordingly, the manufacturers demand very narrow beam width of 15 μm or so for wafer processing,. In order to meet these demands, it is necessary to increase a processing overlay degree of laser beam, that is, laser frequency and maintain low beam intensity. However, according to the characteristics of the laser that generally uses, when the frequency of the laser beam increases, the power decreases. Therefore, even though the processing quality can be improved, the processing time cannot be guaranteed. Further, if the laser beam having low frequency is used in order to improve the processing speed, the laser beam is overheated by the processing object Therefore, the beam width is increased, which disturbs the minute processing.

SUMMARY OF THE INVENTION

Advantage of the present invention is to provide a laser processing apparatus and method that is capable of improving the processing speed while maintaining the intensity of the laser beam.

Another advantage of the present invention is to improve the processing efficiency by increasing the power by the number of split beams while maintaining the intensity of the split beams equal to the intensity of non-split beam, before irradiating the laser beam onto an object Further, Ihe stage is moved to a direction opposing to the irradiation direction of laser beam while irradiating the split laser beam, which increases the processing speed.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a configuration diagram showing a laser processing apparatus according to a first embodiment of the invention; Fig.2 is an exemplary diagram of a beam scanner shown in Fig. 1 ;

Figs. 3a to 3c are a first exemplary diagram of a beam splitting unit shown in Fig. 1, and cross-sectional views showing a split beam;

Figs. 4a and 4b are a second exemplary diagram of a beam splitting unit shown in Fig. 1, and a cross-sectional view showing a split beam; Figs. 5a and 5b are a third exemplary diagram of a beam splitting unit shown in Fig. 1 , and a cross-sectional view showing a split beam;

Figs. 6a and 6b are a fourth exemplary diagram of a beam splitting unit shown in Fig. 1 , and a cross-sectional view showing a split beam;

Fig. 7 is a diagram illustrating a concept of processing an object using a polygon mirror that is applied to Ihe present invention;

Fig. 8 is a diagram illustrating a concept of the overlay of beam when the object is processed using the polygon mirror,

Fig. 9 is a schematic configuration diagram showing a laser processing apparatus according to the first embodiment to which the polygon mirror is applied;

Fig. 10 is a configuration diagram showing a laser processing apparatus to which a polygon mirror having an error correcting fimction is applied:

Fig. 11 is a diagram illustrating a phenomenon that energy loss is caused at a comer of a reflecting surface of the polygon mirror; Figs. 12a and 12b are diagrams illustrating the energy loss relationship depending on the incident of the laser beam at the polygon mirror,

Fig. 13 is a diagram illustrating a concept of processing an object using a polygon mirror when a laser beam is incident so as to cover a plurality of reflection surfaces of the polygon mirror,

Fig. 14 is a configuration diagram showing a laser processing apparatus according to the first embodiment of the invention when an AOD is applied;

Fig. 15 is a diagram illustrating that a residual matter is discharged when the object is produced using the laser while moving the object;

Fig. 16 is a configuration diagram showing a laser processing apparatus according to a second embodiment of the invention; Fig. 17 is a detailed configuration diagram of a beam forming unit shown in Fig. 16;

Fig. 18 is a diagram illustrating that a residual product is sublimed when an object is processed using the laser processing apparatus according to the second embodiment of the invention;

Figs. 19a to 19d are diagrams illustrating a concept that the laser beam is repeatedly irradiated onto the object from a common laser processing apparatus; Fig. 20 is a schematic configuration diagram showing a laser processing apparatus according to a third embodiment of the invention;

Fig. 21 is a diagram illustrating a concept that a surface of an object is equally processed by the laser processing apparatus according to the third embodiment of the invention; Fig. 22 is a schematic configuration diagram showing a laser processing apparatus according to the fourth embodiment;

Figs. 23a to 23d are diagrams showing an example that the object is processed using the laser processing apparatus shown in Fig.22;

Fig.24 is an exemplary diagram of a stage that is applied to this invention; Figs.25a to 25d are detailed construction diagrams showing parts of the stage shown in Fig.

24;

Fig. 26 is a diagram showing an example of a thermoelectric element that is applied to the invention;

Fig. 27 is a configuration diagram showing a laser processing apparatus according to a fifth embodiment of the invention;

Fig. 28 is an exemplary diagram showing a first modification of the laser processing apparatus shown in Fig.27;

Fig. 29 is an exemplary diagram showing a second modification of the laser processing apparatus shown in Fig.27; Fig. 30 is an exemplary diagram showing a third modification of the laser processing apparatus shown in Fig.27;

Fig.31 is a flow chart illustrating a laser processing method according to a first embodiment of the invention;

Fig. 32 is a flow chart illustrating a laser processing method according to a second embodiment of the invention;

Fig. 33 is a flow chart illustrating a laser processing method according to a third embodiment of the invention;

Fig. 34 is a flow chart illustrating a laser processing method according to a fourth embodiment of the invention;

Fig. 35 is a flow chart illustrating an example of the object processing method shown in Fig. 34;

Figs.36a and 36b are diagrams illustrating an example that an object is processed according to the processing method shown in Fig. 35; Fig. 37 is a flow chart illustrating another example of the object processing method shown in Fig.34;

Figs. 38a and 38b are diagrams illustrating an example that an object is processed according to the processing method shown in Fig. 37; and

Fig. 39 is a flow chart illustrating a laser processing method according to a fifth embodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENT

In order to achieve the above-mentioned objects, a laser processing apparatus according to a first embodiment includes; a beam splitting unit that splits a laser beam emitted from a laser generating unit into at least two laser beams; a beam scanner that receives the split laser beams from the beam splitting unit and reflects the beams so as to be repeatedly irradiated onto a processing position of the object; and a stage transfer unit that transfers at least one time a stage on which the object is placed to the direction opposing to the irradiation direction of the laser beam during the processing of the object A laser processing apparatus according to a second embodiment includes; a plurality of laser generating units that emits laser beams; a plurality of beam splitting units that receives the laser beam emitted from the plurality of laser generating units and splits the laser beam into at least two laser beams; a plurality of mirrors that reflects the laser beams split from each of the beam splitting unit onto the same position; actuators that are provided in the plurality of mirrors to adjust the angle and the position of the mirrors; a reflection mirror that receives and reflects the laser beam reflected from the plurality of mirrors; and an optic system that condenses the laser beams reflected from the reflection mirror and irradiates onto the object

A laser processing apparatus according to a third embodiment includes: a plurality of laser generating units that emits laser beams; a plurality of beam splitting units that receives the laser beam emitted from the plurality of laser generating units and splits the laser beam into at least two laser beams; a plurality of polygon mirrors that has a plurality of reflection surfaces to rotate with respect to the reflection axis and receives and reflects the laser beams split from the beam splitting unit; a plurality of reflective mirrors that reflects the laser beams reflected from the plurality of polygon mirrors; and an optic system that condenses the laser beams reflected from the reflective mirror and irradiates onto the object.

A laser processing apparatus according to a fourth embodiment includes: a laser generating unit that emits laser beams; a plurality of beam splitting units that receives the laser beam emitted from the laser generating unit and splits the laser beam into at least two laser beams; a plurality of splitters that splits each of the laser beams split in the beam splitting units into at least two laser beams; a plurality of polygon mirrors that receives and reflects the laser beams that are transmitted or reflected from the beam splitter; a plurality of reflective mirrors that reflects the laser beam reflected from the plurality of mirrors; and an optic system that condenses the laser beams reflected from the reflective mirror and irradiates onto the object A laser processing method according to a first embodiment includes: placing the object on a stage; setting control parameters according to the kinds of objects and the processing purpose; driving a beam scanner and a stage transfer unit to transfer the stage at a preset speed; emitting a laser beam; splitting the emitted laser beam into at least two laser beams to irradiate onto the beam scanner, and irradiating the laser beam reflected from the beam scanner onto the object In this case, the stage may be transferred to a direction opposing to the irradiation direction of the laser beam.

A laser processing method according to a second embodiment includes: a first step of setting processing parameters with respect to layers of the multilayered object; a second step of irradiating a laser beam that is split into at least two laser beams onto the object on the basis of the processing parameters that are set with respect to a layer that is exposed onto the processing portion of the object to perform the laser processing; a third step of confirming whether all layers of the multilayered object are processed; and a fourth step of proceeding to the second step if all layers are not processed according a confirmed result in the third step.

A laser processing method according to a third embodiment includes: a first step of cutting the processing region by irradiating the laser beam that is split into at least two laser beams onto the object; and a second step of healing the processing region of the cut object

A laser processing method according to a fourth embodiment includes: placing the object on a stage; setting control parameters according to the kinds of objects and the processing purpose; adjusting gradients and positions of first and second mirrors using first and second actuators; driving a reflective mirror, transferring the stage at a preset speed; emitting laser beams from a plurality of laser generating units; splitting each of the laser beams emitted from the plurality of laser generating units into at least two laser beams to be incident onto the first and second mirrors; and irradiating the laser beam input from the first and second mirrors to the reflective mirror onto the object

According to the embodiments of the invention, if the laser beam that is incident onto the laser processing apparatus is split into a plurality of beams, the power is increased as much as the number of split beams while maintaining the intensity of the beams before being split, and the frequency of the laser beam is increased as many as the number of split beams. For example, the object processing that uses 200 kHz, 4 W laser beam has the same intensity as 100 kHz, 2 W laser beam. Therefore, if 100 kHz, 6W laser beam is split into three beams to process the object, it is possible to secure the narrower beam width. Further, since the power is 6W, the processing speed is also improved, thereby achieving triple beam superposing effect Similarly, if 100 kHz, 8 W laser beam is split into four beams to process the object, it is possible to process the object at higher speed with narrower beam width. Hereinafter, the preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.

Laser processing apparatus having laser beam splitting and stage moving function Fig. 1 is a configuration diagram showing a laser processing apparatus according to a first embodiment of the inventioa

As shown in Fig. 1 , a laser processing apparatus according to a first embodiment includes; a controller 101 that controls the overall operation, a laser generating unit 103 that outputs a laser beam having a specified diameter, a beam splitting unit 105 that splits the laser beams output from the laser generating unit 103 into at least two laser beams; a driver 107 that drives a beam scanner 115; an input unit 109 that inputs control parameters and control commands; an output unit 111 that display information such as operation status; a storing unit 113 that stores data; the beam scanner 115 that repeatedly and straightly scans the laser beam emitted from the beam splitting unit 105 in a predetermined section of an object processing position; an optic system 117 that condenses the laser beam reflected from the beam scanner 115 to irradiate onto the object; and a stage transfer unit 123 that transfers at least one time a stage 121 on which the object 119 is placed to the direction opposing to the irradiation direction of the laser beam while the object 119 is processed. Here, the optic system 117 may be embodied by a condensing lens.

When the object 119 is processed using the above laser processing apparatus, first, the control parameter is set by the input unit 109. This setting process is performed by previously registering a menu according to the kind of the objects and processing type, and then storing it in the storing unit 113. Therefore, the setting process can be easily processed by calling the menu.

After the control parameter is set, the beam scanner 115 is driven by the driver 107.

The beam scanner 115 can be embodied by using any one of galvanometer scanner and a reflecting device using a servomotor. More specifically, as shown in Fig. 2, the beam scanner 115 includes mirrors 320 and 340 that are connected to the rotation axis of one or two motors 310 and 330 to repeatedly rotate at a predetermined angle and in a predetermined direction (right and left, or up and down)

The laser beam that is incident from the beam splitting unit 105 to the second mirror 340 is reflected to the first mirror 320. Subsequently, the laser beam that is reflected from the first mirror

320 is irradiated to the optic system 117, and the laser beam that passes through the optic system 117 is irradiated to the object 119. In this case, the mirrors 320 and 340 can be used one or both according to the processing purpose.

According to this embodiment, since the first and second mirrors 320 and 340 rotate at a predetermined angle and in a predetermined direction, it is possible to irradiate the laser beam while moving the laser beam. Further, the object 119 moves also by the stage transfer unit 123, which reduces the processing time.

Referring to Fig. 1 again, after driving the beam scanner 115 by the driver 107, the controller 101 operates the stage transfer unit 123 to move Ihe object 119 in a direction opposing to the irradiation direction of the laser beam, and controls the laser generating unit 103. When the laser is emitted from the laser generating unit 103, the laser beam is split into at least two laser beams by the beam splitting unit 105 and then is incident to the beam scanner 115.

Thereafter, at least two laser beams that are reflected from the beam scanner 115 are vertically irradiated onto the object 119 through the optic system 117. In this case, since a plurality of beams passes through the optic system 117, it is possible to obtain the same result that the laser beam is irradiated onto the object 119 plural times. Further, since the plurality of laser beams is simultaneously incident, it is possible to perform the processing with narrower beam width while maintaining the processing speed to the speed when the beam is not split, and to secure the processing quality.

Figs. 3a to 3c are a first exemplary diagram of a beam splitting unit shown in Fig. 1, and cross-sectional views showing a split beam, and show that the laser beam is split into two laser beams using a prism.

As shown in Fig. 3a, the beam splitting unit 105 includes a first mirror 10501 that reflects incident laser beam, a prism 10502 that divides the laser beam from the first mirror 10501 into two laser beams, and a second mirror 10503 that reflects the beams divided by the prism 10502.

Here, the first mirror 10501 enters the laser beam to the prism 10502 and the prism 10502 makes the two divided beams be symmetric to each other according to the arrangement of the prism. The second mirror 10503 controls an optic axis of the beam emitted from the prism 10502 to be horizontal to an optic axis of the laser beam incident to the first mirror 10501. Further, the laser beam reflected from the second mirror 10503 is incident to the beam scanner 115 to be irradiated onto the object In this case, the laser beam reflected from the beam scanner 115 is necessarily controlled such that the optic axis is vertical to the object

An example of the section of the laser beam that is irradiated onto the object by the beam splitting unit is shown in Fig. 3b. The distance between the two semicircular laser beams may be varied depending on the refractivity of the beam of the prism 10502. Further, the two laser beams can be irradiated on the same area as the irradiating area of non-split laser beam, that is, the number of laser beams that are irradiated in the unit area can be increased, which improve the processing efficiency.

Fig. 3c shows an example of the prism 10502 shown in Fig.3a

As shown in Fig. 3a, the prism 10502 consists of a first prism 10504 that splits the incident laser beam into two laser beams and a second prism 10505 that changes direction of the beam so as to make the laser beams split by the first prism 10504 be parallel to each other. Further, the folding angle of the first and second prisms 10504 and 10505 is 120 degree. The laser beam that is reflected from the first mirror 10501 and then enters the first prism 10504 is split into two laser beams, and then changed by the second prism 10505 so as to be converted to each other. Therefore, the split laser beam has a section shape shown in Fig. 3b, and then is incident onto the second mirror 10503 with this shape. Further, by changing the position of the second prism 10505, it is possible to control the distance between the split beams. In this case, the movement distance of the second prism 10505 is 1 to 20 mm. Specifically, when the first prism 10504 is fixed, by changing the position of the second prism 10505, the distance between the two prisms 10504 and 10505 is changed to change the distance of the two outgoing laser beams. Furthermore, before performing the laser processing, the distance between the first and second prisms 10504 and 10505 may be previously set by an operator depending on the purpose of the process.

Figs. 4a and 4b are a second exemplary diagram of a beam splitting unit shown in Fig. 1, and a cross-sectional view showing a split beam, in which a case that the laser beam is split into two laser beams by using a beam splitter is shown.

As shown in Fig.4a, the beam splitting unit 105 includes a beam splitter 10511 that splits the incident laser beam into two beams, a polarizer 10512 that changes the polarizing characteristic of a first laser beam reflected from the beam splitter 10511, a first mirror 10514 that reflects a second laser beam transmitting the beam splitter 10511, a second mirror 10515 that reflects the second laser beam reflected from the first mirror 10514, and a polarized beam splitter 10513 that reflects the first laser beam whose polarizing characteristics is changed by the polarizer 10512 and transmits the second laser beam reflected from the second mirror 10515. The first and second laser beams that are reflected and transmitted from the polarized beam splitter 10513 are vertically irradiated onto the object by the beam scanner 115.

The cross-sections of the first and second laser beams of the beam splitting unit are shown in Fig. 4b. The distance between the two laser beams can be controlled by changing the position of the second mirror 10515.

Further, the optic axis of the laser beam that is emitted from the polarized beam splitter 10513 is controlled so as to be parallel to the optic axis of the laser beam that enters the beam splitter 10511. Furthermore, the optic axis of the laser beam that is reflected from the beam scanner 115 is controlled so as to be perpendicular to the object

Further, as for the polarizer 10512, a polarizer that converts parallel linear polarization (P polarization) into perpendicular linear polarization (S polarization) can be used. As for the polarized beam splitter 10513, a polarized beam splitter that transmits the P polarized light and reflects the S polarized light can be used. Figs. 5a and 5b are a third exemplary diagram of a beam splitting unit shown in Fig. 1 , and a cross-sectional view showing a split beam. Referring to Figs. 5a and 5b, the beam splitter splits the laser beam into two laser beams, and then splits one of the two laser beams into two laser beams using a prism. Accordingly, the laser beams is split into three components.

As shown in Fig. 5a, the beam splitting unit 105 includes a beam splitter 10521 that splits incident laser beam into two laser beams, a polarizer 10522 that changes the polarization characteristic of the laser beam reflected from the beam splitter 10521, a prism 10523 that splits the laser beam polarized by the polarizer 10522 into first and second laser beams, a first mirror 10525 that reflects a third laser beam transmitting the beam splitter 10521 , a second mirror 10526 that reflects the third laser beam reflected from the first mirror 10525, and a polarized beam splitter 10524 that reflects the first and second laser beams emitted from the prism 10523 and transmits the third laser beam entering through the second mirror 10526. The first to third laser beams that are reflected or transmitted from the polarized beam splitter 10524 are perpendicularly irradiated onto the object through the beam scanner 115. The example of the cross-section of the laser beams split by the beam splitting unit according to the embodiment is shown in Fig. 5b. The distance between the first and second laser beams is controlled by controlling the refractivity of the prism 10523. Further, the arrangement of the prism 10523 is controlled such that the two laser beams becomes symmetrical to each other, and the position of the second mirror 10526 is controlled so as to control the position of the third laser beam.

Further, as for the polarizer 10522, a polarizer that converts parallel linear polarization (P polarization) into perpendicular linear polarization (S polarization) can be used. As for the polarized beam splitter 10524, a polarized beam splitter that transmits the P polarized light and reflects the S polarized light can be used. The prism 10523 can be configured as shown in Fig. 3c.

Figs. 6a and 6b are a fourth exemplary diagram of a beam splitting unit shown in Fig. 1 , and a cross-sectional view showing a split beam. Referring to Figs. 6a and 6b, one laser beam is split into two laser beams by a prism, and each of the two split laser beams is split into two beams by the beamsplitter. Accordingly, the laser beams is split into four laser beams. As shown in Fig. 6a, the beam splitting unit 105 includes a prism 10531 that splits incident laser beam into two laser beams, a beam splitter 10532 that splits each of the two laser beams split by the prism 10531 into two laser beams to reflect and transmit, a polarizer 10533 that changes the polarization characteristic of the first and second laser beams reflected from the beam splitter 10532, a first mirror 10535 that reflects third and fourth laser beams transmitting the beam splitter 10532, a second mirror 10536 that reflects the third laser beam reflected from the first mirror 10535, and a polarized beam splitter 10534 that reflects the first and second laser beams emitted from the prism

10533 and transmits the third and fourth laser beams entering through the second mirror 10536.

The first to fourth laser beams that are reflected or transmitted from the polarized beam splitter 10534 are perpendicularly irradiated onto the object through the beam scanner 115.

The example of the cross-section of the laser beams split by the beam splitting unit according to the embodiment is shown in Fig. 5b. Further, the distances of the first to fourth laser beams are controlled by controlling the refractivity of the prism 10531 or the arrangement of the second mirror 10536. In this case, the optic axis of the laser beam that is reflected from the second mirror 10536 is controlled so as to be parallel to the optic axis of the laser beam that enters the prism 10531. Furthermore, the optic axis of the laser beam that is reflected from the beam scanner 115 is controlled so as to be perpendicular to the object

The prism 10531 can be configured as shown in Fig.3c.

As described above, according to the embodiment, the laser beam is split into two or more laser beams using the prism, the beam splitter, or the combination of the prism and the beam splitter, thereby processing the object The total energy of the split laser beams is equal to the energy of the non-split laser beam, which makes it possible to maintain the processing speed. Further, the intensity of each of the split laser beams is lower than the non-split laser beam, which secures the narrow beam width. Further, the distances between the split laser beams can be easily changed according to the arrangement of the optic systems of the beam splitting unit

Further, since the split laser beams are irradiated onto the object 119 using the beam scanner 115, the same result that the laser beam moves to be irradiated onto the object can be obtained. Furthermore, it is possible to improve the processing speed by transferring the stage in a direction opposing to the irradiation direction of the laser beam, at least one time while processing the object

In the laser processing apparatus shown in Fig. 1 , the beam scanner 115 may be configured by a polygon mirror. The polygon mirror includes is a polygonal rotating mirror that includes a plurality of reflection surfaces and rotates with respect to the rotational axis. The polygon mirror will be described with respect to Fig. 7. Fig. 7 is a diagram illustrating a concept of processing an object using a polygon mirror that is applied to the present invention.

The polygon mirror 115-1 that includes n reflection surface rotates with respect to the rotary axis 11 with an angular velocity ω and a rotation period T at a constant speed. In this case, the incident laser beam is reflected from the reflection surface to be irradiated onto the object 119 through the optic system 117.

In the polygon mirror 115-1 that has n reflection surfaces 12, a scanning angle θ of the laser beam when one of the reflection surfaces 12 rotates is represented by the equation 1. [Equation 1]

θ⁼2(α₂-α₁)

π α _! =φ+ψ- —

2π α >=φ+ψ- — - + n

Ω y- ^4π n According to the above equation 1, the scanning angle θ is twice the central angle " of one reflection angle 12 of the polygon mirror 115-1. Therefore, the scanning length that is a length when the laser beam reflected from the reflection surface 12 of the polygon mirror 115-1 is irradiated onto the object 119 is determined by the characteristics of the optic system 117 that irradiates the laser beam onto the object 119, and is represented by the equation 2. [Equation 2]

SL : scanning length f: focal length θ : scanning angle

According to the equation 2, when the polygon mirror 115-1 rotates, the laser beams reflected from the reflection surfaces 12 of the polygon mirror 115-1 are irradiated onto the object 119 by the length S_L- That is, the scanning length of the laser beam that is irradiated onto the object 119 according to the rotation of the polygon mirror 115-1 is calculated by multiplying the focal length of the optic system 117 and the angle of the laser beams that are reflected from the reflection surfaces 12 of the polygon mirror 115-1.

The polygon mirror 115-1 includes n reflection surfaces 12. Therefore, when the polygon mirror 115 rotates one time, scanning is performed n times with the scanning length of SL- That is, the laser beam is irradiated onto the object 119 with the above scanning length, and when the polygon mirror 115-1 rotates one time, the laser beam is repeatedly irradiated onto the object as many times as the number of reflection surfaces 12 of the polygon mirror 115-1. The scanning frequency during a unit time, for example, one second is represented by the equation 3. [Equation 3] wn n

Scanning frequency = ^{2π τ} ω : angular velocity of polygon mirror T : rotational period of polygon mirror According to the equation 3, when the number of the reflection surfaces 12 of the polygon mirror 115-1 is n, the scanning frequency is controlled by controlling the rotational period or the angular velocity of the polygon mirror 115-1. In other word, it is possible to overlay the scanning length as many times as needed by controlling the rotational period or the angular velocity of the polygon mirror 115-1. In this case, if the angular velocity of the polygon mirror 115-1 is constant, by transferring the stage 121 on which the object 119 is placed to the opposing direction to the direction that the laser beam is irradiated onto the object 119 according to the rotation of the polygon mirror 115-1, the relative velocity that the laser reflected by the polygon mirror 115-1 scans the object 119 increases. That is, the speed Ihat the laser beam scans the object when the stage 121 is transferred in the direction opposing to the irradiation direction of the laser beam is higher than the speed that the laser beam scans the object 119 when the stage 121 is in a stop state.

Fig. 8 is a diagram illustrating a beam superposition concept when the object is processed using the polygon mirror.

As the stage 121 on which the object 119 is transferred, the laser beam moves in the opposing direction to the transferring direction of the stage 121 while the scanning length SL of the laser beam is overlaid. That is, as the stage 121 is transferred, the object is processed (cut) while the laser beam scans the object 119 in the opposing direction to the transferring direction of the stage 121.

In this case, the scanning length SL is uniformly overlaid in a predetermined section, the overlay frequency is controlled by controlling the transferring speed of the stage 121.

When the distance that the scanning length SL moves by transferring the stage 121 is t, the overlay degree N of the scanning length is represented by SJL

"I" refers to the travel distance of the stage 121 that moves at the velocity v during the rotation of one reflection surface 12 of the polygon 115-1, and is represented by the equation 4. Further, the overlay degree N is represented by the equation 5. [Equation 4]

,_ V _ Vl _ Z.%\

L n n rtw

Ύ

[Equation 5]

S₁ _^ 4π/ _ 2wf

Overlay degree (N) = 1 vT V

In summary, the angular velocity of the polygon mirror 115-1 in order to obtain the scanning overlay degree N while the object 119 is processed (cut) at the velocity v is represented by the equation 6. [Equation 6]

Nv

As represented in Equation 6, the angular velocity of the polygon mirror 115-1 is calculated by dividing the product of the overlay frequency N of the laser beam and the cutting velocity v of the object 119 by twice the focal distance f of the optic system. The cutting velocity v of the object 119 is the transferring speed of the stage 121 on which the object 119 is placed.

In the above embodiment, even though the polygon mirror is octagonal and has eight reflection surfaces, it can be modified within the gist of the invention.

Fig. 9 is a schematic configuration diagram showing a laser processing apparatus according to the first embodiment to which the polygon mirror is applied.

A driver 107 drives the polygon mirror 115-1 using a motor (not shown)), and the laser beams that is split into at least two beams by the beam splitting unit 105 are incident onto the reflection surfaces of the polygon mirror 115-1 to be reflected from the optic system 117. In this case, since the polygon mirror 115-1 rotates at a constant speed, the same effect that the laser beam is irradiated while laser beam moves can be obtained. Therefore, by transferring the stage 121 using the stage transfer unit 123 in the opposing direction to the irradiation direction of the laser beam, it is possible to increase the processing speed of the object.

In the case of the above-described laser processing apparatus using the polygon mirror, the laser beams needs to be precisely incident at the center of the length direction of the reflection surface of the polygon mirror in order to process the object without error. Further, even when the laser beam is precisely incident onto the polygon mirror, if the reflection surfaces of the polygon mirror are not uniform, the reflection angle is undesirably distorted. That is, the laser beam reflected from the polygon mirror is imprecisely irradiated onto the object due to the dynamic track of the polygon mirror. This causes the error during the processing of the object, and reduces the production yield and reliability. Therefore, it is important to analyze the error by previously measuring the error of the polygon mirror before processing the object, and control the direction of the laser beam that is incident onto the polygon mirror on the basis of the analyzed error during the actual processing of the object to compensate the error of the laser processing apparatus.

Fig. 10 is a configuration diagram showing a laser processing apparatus to which a polygon mirror having an error correcting function is applied.

The laser processing apparatus according to the embodiment further includes: an error correcting unit 125 that analyzes the error of the polygon mirror according to the control of the controller 101, an encoder 127 that is mounted into the polygon mirror 115-1, and an actuator 200 that is provided with a mirror 202 for correcting the irradiation direction of the laser beam emitted from the beam splitting unit 105 on the basis of the error that is analyzed in the error correcting unit 125 according to the control of the controller 101 , in addition to the laser processing apparatus shown in Fig. 1.

In order to previously measure the error of the polygon mirror 115-1, the laser processing apparatus having the above configuration is tested That is, according to the control of the controller

101, the driver 107 rotates the polygon mirror 115-1, and the laser beam that is emitted from a laser generating unit 103 and has a low energy level (is lower than the energy level at the time of the actual processing) is split by the beam splitting unit 105 to be irradiated onto the polygon mirror 115-1.

Thereby, the laser beam that is incident onto the polygon mirror 115-1 is reflected from the reflection surface 12 of the polygon mirror 115-1 that rotates by the driver 107 toward the optic system 117. Subsequently, the optic system 117 collects the laser beam reflected from the reflection surface 12 to vertically irradiate the beam onto the test object.

In this case, when the reflection surface of the polygon mirror 115-1 has some errors, the laser beam is not irradiated straightly onto the test object Therefore, the operator measures the errors of the respective reflection surface of Ihe polygon mirror using the result of the test object processing, and inputs the result to the error correction unit 125 through an input unit 109. In this case, in order to precisely measure the error of the polygon mirror, it is preferable to measure the error by performing the test plural times. Meanwhile, when the laser beam is irradiated with very low energy level, the error can be measured using the waveform of the laser beam that is irradiated onto tiie test object, not the result of the processing of Ihe test object.

The error correcting unit 125 calculates the error compensated value of the each reflection surface of the polygon mirror, that is, the control value of the incident angle of the laser beam on the basis of the measured error of the polygon mirror and then stores in the storage unit 113.

Accordingly, after analyzing the error of the polygon mirror through the test process, the actual object processing is performed. During the actual object processing, the encoder 127 that is mounted onto the polygon mirror 115-1 converts information on the position and the velocity of the polygon mirror 115-1 into electrical signals to output to the controller 101. Further, the controller 101 extracts the error compensation value that is input from the encoder 127 and corresponds to the reflection surface of the polygon mirror to drive the actuator 200. That is, in order to precisely irradiate the laser beam onto the processing object by preventing the distortion of the reflection angle of the laser beam caused by the error of the reflection mirror of the polygon mirror onto which the laser beam is irradiated, the actuator 200 changes the direction of the mirror 202 to control the incident angle of the laser beam with respect to the reflection surface of the polygon mirror. Accordingly, the angle of the laser beam that is reflected from the reflection surface is controlled to have the constant value. Here, the encoder 127 can be embodied by a rotary encoder that is a sensor for detecting the rotary movement Examples of the rotary encoder include an optical rotary encoder that detects the rotated displacement by using a light source and a photoelectric element and attaching a scale plate onto a rotating rotary shaft and a magnetic rotary encoder that detects the rotated displacement using a magnetic rotary sensor mounted thereto. Meanwhile, when the polygon mirror is applied to the laser processing apparatus according to the first embodiment, if the laser beam that is irradiated onto the object has a large energy (about 10 W), the laser beam overheats the same processing position of the object, which damages the object Thereby, the reliability of the processing of the object is deteriorated. Further, as a laser beam for the laser processing apparatus, generally, a laser beam having a specified diameter is used instead of the point beam. In this case, if the laser beam is incident onto the comer of the reflection surface of the polygon mirror, some of the laser beam is lost This will be described with reference to Fig. 11.

Fig. 11 is a diagram illustrating a phenomenon that energy loss is caused at a comer of a reflecting surface of the polygon mirror. As shown in Fig. 11 , a laser beam having a specified diameter is incident onto the polygon mirror 115-1. If the laser beam having a specified diameter is incident onto the comer of the reflection surface 12 while the polygon mirror 115-1 rotates, some of the laser beam (energy reduced laser beam: A) is reflected from the reflection surface 12 to be incident onto the optic system 117, and the other laser beam (loss laser beam: B) is incident onto another reflection surface 12', not onto the optic system 117.

Therefore, the optic system 117 collects only the energy reduced laser beam A to irradiate onto the object 119 on the stage 121, which causes the difference in the processing efficiency on the processing position and the processing efficiency on the other position of the object 119. As a result, it is difficult to uniformly process the object 119, which deteriorates the processing reliability. Further, the energy of the laser beam is lost at the corner of the reflection surface of the polygon mirror, which wastes the resources.

Therefore, this embodiment uses a polygon mirror having a limited number of reflection surfaces such that the diameter of the incident laser beam can cover two or more reflection surfaces of the polygon mirror. Figs. 12a and 12b are diagrams illustrating the energy loss relationship depending on the incident of the laser beam at the polygon mirror.

Referring to Fig. 12a, when the laser beam having a specified diameter D is incident and reflected from the comer of one reflection surface of the polygon mirror 115-1, some of the laser beam (energy reduced laser beam: A) is incident onto the reflection surface 12 and the remaining laser beam (loss laser beam: B) is incident onto another reflection surface 12'. Therefore, the laser beam that is incident onto the reflection surface 12 is reflected from the reflection surface 12 with an energy reduced by the laser beam that is incident onto the other reflection surface 12'.

Further, in order to calculate the ratio of the scanning length that is processed by the energy loss laser beam A with respect to the total scanning length that is processed by the one reflection surface of the polygon mirror 115-1, a circumscribed circle 13 is drawn around the polygon mirror 115-1, and a point that the energy loss laser beam A intersects the circumscribed circle of the polygon mirror is connected with the center of the polygon mirror 115-1 (that is, rotational axis 11). The angle obtained as described above is referred to as a loss angle %. Next, the ratio of the loss part with respect to one reflection surface of the polygon mirror 115-1 having N reflection surfaces (hereinafter, referred to as "loss rate") will be described hereinafter.

Referring to Fig. 12a, a length of an arc obtained by connecting points that the circumscribed circle 13 of the polygon mirror 115-1 intersects both ends of the one reflection surface with the rotational axis, that is, the length of the arc Cl with respect to the one reflection surface of the polygon mirror to which the laser beam is irradiated is represented by the equation 7. [Equation 7]

ci = ^2πfi

N

Further, the length of the arc C2 with respect to the loss angle is represented by the equation 8 which represents the maximum length of the arc with respect to the loss angle. [Equation 8]

The length C2 of an arc with respect to the loss angle changes according to the rotation of the polygon mirror. When the laser beam is irradiated onto the polygon mirror except the comer, there is no loss laser beam. Therefore, the loss rate is 0. Thereafter, when the polygon mirror rotates and the laser beam is irradiated onto the polygon mirror including the corner, the loss rate gradually increases to have the maximum value represented by the equation 8, and then gradually decreases.

Further, a percentage (t_r, hereinafter, referred to as "loss rate") of a part of one reflection surface of the polygon mirror from which the laser beam is reflected with the reduced energy is represented by the equation 9. [Equation 9]

Further, the loss angel tø is represented by the equation 10, and the linear distance h from the center of the polygon mirror to the center of the laser beam that is irradiated onto the reflection surface is represented by the equation 11. [Equation 10]

[Equation 11]

Here, R is a radius of the circumscribed circle of the polygon mirror. Meanwhile, as shown in Fig. 12b, the scanning angle θ of the incident laser beam at one reflection surface of the polygon mirror is represented by the equation 12. [Equation 12]

Table 1 represents the relationship between the loss rate on one reflection surface of the polygon mirror and the number of split beams. That the loss rate is smaller than 100% means that C2 is smaller than Cl in the above equation, that is, the laser beam is incident to cover one reflection surface. In contrast, that the loss rate is larger than 100% means that C2 is larger than Cl in the above equation, and the incident laser beam covers two or more reflection surfaces.

[Table 1]

When the loss rate is 0 to 99, the laser beam is split into one or two laser beams after entering the reflection surface of the polygon mirror. Whereas, when the loss rate is 100 to 199, the laser beam is split into two or three components, and when the loss rate is 200 to 299, the laser beam is split into three or four components. That is, as the loss rate increases, the number of split laser beams increases. Further, when the laser beam is split into two or three beams, the diameter D of the laser beam is enough to cover two corners of the reflection surface of the polygon mirror. Furthermore, when the laser beam is split into three or four beams, the diameter D of the laser beam is enough to cover three comers of the reflection surface of the polygon mirror.

As described above, that the laser beam is split into one or two beams is a phenomenon caused by the characteristics of the polygon mirror and the laser beam that as the polygon mirror rotates, the laser beam that is irradiated onto the comer of the reflection surface is reflected. Therefore, it is not available beam splitting. Therefore, the case that the laser beam is split into two or three, or three or four is considered as available beam splitting. As known from the equations 9 to 11 , the loss rate increased as the number N of reflection surface increases, the diameter D of the incident laser beam increases and the radius R of the circumscribed circle of the polygon mirror decreases. Further, as known from the equation 12, as the number N of the reflection surfaces increases, the scanning angle at one reflection surface of the polygon mirror gradually decreases. As a result, the optic system 117 can collect the laser beam that is split and reflected from one reflection surface of the polygon mirror.

As described above, when the laser beam is split and then irradiated onto the object, the same effect that the laser beam is irradiated plural times on the same processing surface with a low energy can be achieved, which improves the processing quality of the object and the yield.

Fig. 13 is a diagram illustrating a concept of processing an object using a polygon mirror when a laser beam is incident so as to cover a plurality of reflection surfaces of the polygon mirror, in which a part of the enlarged polygon mirror is shown for convenience sake.

As shown in Fig. 13, the laser beam having a specified diameter D is irradiated onto the polygon mirror having a plurality of reflection surfaces. In this case, the polygon mirror is embodied so that the laser beam is irradiated so as to cover three reflection surfaces of the polygon mirror. That is, the number of reflection surfaces of the polygon mirror is controlled so as to have the loss rate of 100 to 199%.

The laser beams having a specified diameter D are irradiated onto the entire reflection surfacesNl and N2 ofthe polygon mirror 115-1 and a part of reflection surface N3. The laserbeam that is irradiated onto the reflection surface Nl is collected by the optic system 117 to be irradiated on the object 119 that is placed on the stage 121. The object 119 is processed within the scanning angle range of the reflection surface Nl as the polygon mirror rotates. The laser beam that is irradiated onto the reflection surface N2 and the laser beam that is irradiated onto a part of the reflection surface N3 are irradiated onto the object 119 according to the same principle. Therefore, when the object is processed using a laser beam having a specified diameter, not a point beam, the number of reflection surfaces of the polygon mirror is controlled so that the laser beams are split into a plurality of laser beams so as to be incident onto a plurality of reflection surfaces of the polygon. Further, the split laser beams are simultaneously irradiated onto the processing surface of the object plural times. Specifically, according to the embodiment, before the laser beam is incident onto the polygon mirror 115-1, the laser beam is split into a plurality beams by the beam splitting unit 105. Therefore, it is possible to obtain the same result that the laser beam is irradiated onto the processing part of the object plural times with the low energy. Further, since a plurality of laser beams are simultaneously irradiated, the processing can be performed with narrow beam width while maintaining the processing speed to the speed before splitting the beam, and the quality after processing is secured.

Fig. 14 is a configuration diagram showing a laser processing apparatus according to the first embodiment of the invention when an AOD is applied.

An acousto-optic deflector (AOD) is an optic driving device that is capable of scanning a minute area at high speed.

A laser scanning system requires the laser beam to be precisely adjusted at a desired position. A galvano scanning mirror or a polygon mirror is used for the laser scanning system up to now. However, in the case of the optic driving devices, it is difficult to improve the position precision below resolution of several μm. Further, since the unit of the scanning frequency is kHz, there is a speed limitation when the optic driving device operates together with the laser beam PRF (Pulse Repetition Frequency) of 50 kHz or larger.

In order to overcome the drawbacks in the precision and the speed of the optic driving device, the laser processing apparatus is embodied using an AOD that applies an acousto-optic technique, and is shown in Fig.4.

Unlike the laser processing apparatus shown in Fig. 1 , the laser processing apparatus shown in Fig. 14 includes a RF driver 300 and an AOD 302.

The acousto-optic modulator that is mainly used for Q-switching oscillation of the laser is driven by a RF driver of MHz frequency. Here, the term "Q-switching" refers a technique that creates a laser beam pulse output beam. Laser is excited with a low Q value (resonance value) of a laser resonator and a sufficient energy is stored in a laser medium. Thereafter, when the Q value is suddenly raised, the laser is oscillated, and the stored energy is emitted as a rapid and sharp optic pulse. When Q-switching is used for the laser, it is possible to obtain an output power of several GW. In the above acousto-optic modulator, when the phase difference is adjusted using two RF input signals, a laser beam that rotates at the loose and dense interface of the sound wave at a small angle is output

Therefore, in the laser processing apparatus according to the embodiment, two RF signals

(for example, 80 MHz signals) is input to the AOD 302 through the RF driver 300. Then, the sound wave propagates through the AOD 302, and the laser beam that is input from the beam splitting unit

105 is output to rotate at a scanning angle determined depending on the frequency of the RF signal that is input through the RF driver 300.

When using the AOD, the object can be processed with 10 times higher precision and 100 times faster speed than that of the polygon mirror. Further, since the AOD can perform MHz scanning and has 100 or more times fester frequency than a PRF, the laser beam can be uniformly irradiated on the respective positions irregardless of a deceleration period or an acceleration period.

Laser Processing Apparatus having Laser Beam Splitting and Forming Function When a laser beam is irradiated onto an object, a part to which the laser beam is irradiated is removed, and residual products are discharged perpendicularly to the cut surface. If the depth of the recess of the object is not larger, the residual products are easily discharged to the outside. In contrast, as the depth of the recess is larger, the residual products that are sublimed or evaporated by the irradiation of the laser beam can not be discharged to the outside, but are condensed or recasted on the wall of the object.

The drawback that the cutting efficiency is lowered due to the recast of the residual products may be solved by enlarging the cutting width of the object That is, if the cutting width of the object is enlarged, the discharging amount of the residual products is increased, which can reduce the amount of residual products that are recasted on the cutting surface of the object However, when the cutting width of the object is increased, the focus of the laser beam has to be enlarged. Therefore, the beam intensity is lowered and the cutting width is enlarged, whereas the efficiency for removing the residual products is lowered and the object is not completely cut That is, the beam intensity is represented by the intensity of the laser beam per irradiation area. In this case, when the focus area of the beam is enlarged, the irradiation area is increased. Consequently, the beam intensity is lowered. Further, there is a limitation in increasing the cut width for an object that should be minutely processed. As a result, it is difficult to efficiently remove the residual products that are generated during the laser processing using the above method.

Meanwhile, when cutting the object, the laser beam is irradiated while transferring the stage on which the object is mounted using the stage transferring device. Accordingly, even though the laser beam is vertically irradiated, the same result when the laser beam is slantly irradiated can be obtained. This becomes more serious when the transferring speed of the object becomes larger.

Fig. 15 is a diagram illustrating that a residual matter is discharged when the object is produced using the laser while moving the object As shown in Fig. 15, when the laser beam is irradiated while transferring the object, the same result when the laser beam is slantly irradiated onto the object is obtained, and thus the cutting surface of the object has a slant shape that is tilt toward the irradiation direction of the laser beam (a direction opposing to the transferring direction of the object). Since the residual products E that is generated during the object cutting is discharged perpendicularly to the cutting surface, the residual products E can be easily discharged.

Therefore, when the cutting surface of the object is slanted toward the outside, the residual products are easily discharged. This effect becomes more significant as the slant becomes smaller.

However, when the transferring speed of the object becomes larger, the beam intensity becomes smaller and the object is not cut, but melted Further, as the stage transferring device moves at high speed, the processing condition becomes unstable, for example, the object shakes.

Therefore, the present invention discloses a laser processing apparatus that is capable of forming the shape of the laser beam that is irradiated onto the object to be oval.

Fig. 16 is a configuration diagram showing a laser processing apparatus according to a second embodiment of the invention. The laser processing apparatus according to the second embodiment includes: a controller

101 that controls the entire operation; a laser generating unit 103 that outputs a laser beam having a specified diameter; a beam splitting unit 105 that splits the laser beam emitted from Hie laser generating unit 103 into at least two beams; a driver 107 that drives a mirror 129; an input unit 109 that inputs a control parameter and a control command; an output unit 111 that displays information such as an operation status; a storing unit 113 that stores data; a mirror 129 that reflects the laser beam emitted from the beam splitting unit 105 onto a processing position of the object; an optic system 117 Ihat collects the laser beam reflected from the mirror 129 to irradiate onto the object; at least two beam forming units 131-1 and 131-2 (131) that changes the shape of the laser beams passing through the optic system 117 to an oval; and a stage transfer unit 123 that transfers the stage 121 to a direction opposing to the irradiation direction of the laser beam at least one time during the processing of the object.

In this case, the mirror 129 is configured by a polygon mirror, and the optic system 117 is configured by a condensing lens. When the mirror 129 is configured by a polygon mirror, the error can be corrected by the error correcting unit 125, the encoder 127, and the actuator 200 shown in Fig. 10.

Further, as shown in Fig. 17, the beam forming unit 131 is configured by a first cylindrical lens 1310 and a second cylindrical lens 1311. The first cylindrical lens 1310 is a long lens and transforms the laser beam into a sheet light The second cylindrical lens 1311 is a short lens and is provided away from the first cylindrical lens with a predetermined distance so as to have a transmission direction perpendicular to that of the first cylindrical lens 1310. Further, the second cylindrical lens changes the sheet light that is transmitted from the first cylindrical lens 1310 into an oval beam and then transmits it Furthermore, by moving the position of the first cylindrical lens 1310 up and down, the size of the beam that is irradiated onto the surface of the processing object can be changed.

The size of the oval laser beam is controlled such that the major axis is increased as the output of the laser beam is increased, and the major axis is decreased when the output is decreased. That is, the size of the focal surface is changed depending on the output of the laser beam to maintain the beam intensity. Even though the case that the beam forming unit 131 is configured by the cylindrical lenses is described in Fig. 17, any one of elements that can change the shape of the laser beam to have an oval can be used.

Fig. 18 is a diagram illustrating that a residual product is sublimed when an object is processed using the laser processing apparatus according to the second embodiment of the invention.

The object 119 is transferred by the stage transferring device 123 and then cut in a direction opposing to the transferring direction. The laser beam that is irradiated from the beam forming unit 131 slantly cuts the cutting face of the object That is, the cutting face of the object has a slant shape that is slanted toward the cutting direction of the object In this case, the length of the cutting face is the length of the major axis Dl of the laser beam and the width is the length of the minor axis D2 of the laser beam.

Since the laser beam is irradiated to have an oval shape and thus the cutting face of the object is slantly cut, the residual product E that is generated from the cutting face is totally discharged to the outside and does not remain at the bottom of the cutting part As described above, the size of the laser beam that is irradiated onto the object 119 is preferably set to have a ratio of minor axis and major axis of 1 :4 to 1 : 12. However, the ratio can be changed depending on the total depth of the object 119 to be cut

The method that processes the object 119 using the above laser processing apparatus is similar to that shown in Fig. 1, and the detailed description thereof will be omitted.

Laser Processing Apparatus having Laser Beam Splitting and Filtering Function

The laser processing apparatus shown in Fig. 1 splits the laser beam into two or more beams and irradiates the laser beam using the beam scanner while transferring the object in a direction opposing to the irradiation direction of the laser beam to process the object Therefore, the laser processing apparatus shown in Fig. 1 can improve the processing efficiency and the speed.

Figs. 19a to 19d are diagrams illustrating a concept that the laser beam is repeatedly irradiated onto the object from a common laser processing apparatus, in which it is assumed that the object is fixed for convenience sake. As shown in Figs. 19a to 19d, the mirror (320 in Fig. 2) of the beam scanner is gradually slanted from Fig. 19a to Fig. 19d, and thus the position of the object 119 on which the laser beam is irradiated is changed. The laser beam is continuously irradiated and the mirror 320 also continuously moves. Therefore, the laser beam is straightly irradiated onto the processing surface of the object 119 and the surface of the object 119 is continuously processed in the straight line (1, 2, 3). As described above, after the mirror 320 rotates to be moved to a predetermined angle, the mirror reversely rotates from the status shown in Fig. 19d to the status shown in Fig. 19a

However, when the mirror 320 of the beam scanner repeatedly rotates at a predetermined angle, the laser beam does not move at the turning point and is repeatedly irradiated. Therefore, the processing area of the object onto which the laser beam is irradiated is more deeply recessed at the turning point than the other processing area, which lowers the processing uniformity.

Therefore, this embodiment presents a laser processing apparatus including a mask in order to improve the processing ununiformity.

Fig. 20 is a schematic configuration diagram showing a laser processing apparatus according to a third embodiment of the invention. In addition to the construction shown in Fig. 1 , the laser processing apparatus according to the embodiment further includes a mask 400 that includes holes H for filtering a laser beam emitted from the turning point of the mirror (320 in Fig. 2) when the laser beam is emitted from the beam scanner 115.

In this case, the mask 400 may be provided between the beam scanner 115 and the optic system 117 or between the optic system 117 and the object 119. Further, the mask is manufactured by using a material that is capable of reflecting or absorbing the laser beam, such as a metal.

In the above-described laser processing apparatus, the laser beam that is irradiated at the turning point of the mirror of the beam scanner 115 is irradiated around the hole H of the mask 400 and then reflected. Therefore, the laser beams that passes through the hole H and then is irradiated onto the object 119 is uniformly irradiated without a point whose movement velocity is 0. That is, in this embodiment, the mask 400 reflects the laser beam that is irradiated at a point that the movement velocity of the mirror 320 of the beam scanner 155 is 0.

Fig. 21 is a diagram illustrating a concept that a surface of an object is equally processed by the laser processing apparatus according to the third embodiment of the invention.

As shown in Fig. 21, when the mirror 320 repeatedly rotates, the velocity of the mirror is 0 at a first end and a second end in order to change the direction. Therefore, in order to prevent the laser beam from overirradiating onto the processing surface of the object at these ends, the mask 400 having the hole H is introduced to filter the laser beam that is emitted from the first and second ends. A plurality of masks 400 is manufactured according to the size of holes H and is selectively used according to the scanning width of the laser beam. Further, when the size of hole H of the mask 400 is fixed, in order to filter the laser beam that is emitted at the turning point of the mirror, the scanning width of the beam passing through the hole H is adjusted by moving the mask 400 up or down. Further, when the mask 400 can not be changed or moved, the scanning width of the laser beam is adjusted by controlling the rotational angle of the mirror 320 of the beam scanner 115.

Furthermore, it is preferable to embody the same number of mask 400 as the number of beams split by the beam splitting unit 105.

Laser Processing Apparatus having Laser Beam Splitting and Object Cooling Function At the time of laser processing, particles generated at the beam condensed portion contact with the surface of the object to influence the performance of the object In order to remove the particles, the object has to be cleansed. However, in this case, since the object is exposed by the cleansing material, unexpected error may be occurred. In order to solve the above problem, before processing the object using the laser beam, a method for forming a coating layer on the surface of the object is used. However, in this case, after processing the object using the coating layer, additional cleansing process for removing the coating layer is needed. Further, since the cleaning solution contains the particles that are generated during the processing of the object, additional filter is needed to withdraw the particles. Therefore, according to this embodiment, during the processing of the object, the surface of the object is frozen by the water vapor in a processing chamber, and the frozen layer is used as the coating layer. Therefore, the processing of the object is simplified, and the frozen layer is removed after completing the processing of the object. In this case, the removed particles are withdrawn using a filter, which minimizes the industrial waste water. Fig. 22 is a schematic configuration diagram showing a laser processing apparatus according to the fourth embodiment.

In addition to the configuration shown in Fig. 1 (or Fig. 16), the laser processing apparatus shown in Fig. 22 includes a thermoelectric cooling module (TEC Module) 502, an insulator 504, a humidifier 506, a sensor 508, and a thawing unit 510, which are controlled by a controller 101. Further, the object 119 is loaded in a chamber 500.

In the above laser processing apparatus, as the thermoelectric cooling module 502 begins cooling, the stage 121 on the thermoelectric cooling module 502 is cooled, and thus the temperature of the object 119 is lowered. Since the chamber 500 is at the room temperature, as the temperature of the object 119 is lowered, the water vapor condenses to generate dews on the surface of the object 119 due to the difference in temperature. The thermoelectric cooling module 502 continuously cools to form the frozen layer 135 on the surface of the object 119.

The frozen layer 135 serves as a coating layer for protecting the surface of the object 119 and preventing the accompanying particles from directly contacting with the surface of the object 119 during the processing of Ihe object 119 using the laser beam.

That is, the object 119 on the stage 121 is cooled by the thermoelectric cooling module 502 to form the frozen layer 135 serving as a coating layer on the object The laser beam split by the beam splitting unit 105 is irradiated onto the object 10 by the beam scanner 115 (or mirror 129) and the optic system 117. In this case, since the frozen layer 135 is formed on the object 119, the particles that are generated during the processing the object 119 using the laser beam are attached onto the frozen layer 135. When the processing is completed, the frozen layer 135 thaws to cleanse the object 119. In this case, the particle attached onto the frozen layer 135 is also removed. Therefore, the water obtained by thawing the frozen layer contains the particles, and the water is filtered to withdraw the particles that cause the environmental contamination. Meantime, it is mrther possible to load the object 119 into the chamber 500 after precooling the object 119 in order to reduce the time required to cool the object 119 after loading the object 119 in the chamber 500. In this case, since a phenomenon that the moisture congealed between the object 119 and the stage 121 is frozen after loading the object 119 into the chamber 500 may be occurred, it is preferable to set the precooling temperature to be higher than the freezing point The freezing point is a temperature at which the water vapor begins to be changed into water, and is determined depending on the moisture at the peripheral. The water vapor and the freezing point are in proportion to each other.

As described above, according to the embodiment, the frozen layer 135 is formed on the surface of the object 119 using the difference of the temperatures of the inside of the chamber 500 and the object 119, and used as a coating layer. The freezing is caused by the congelation of the surrounding vapor and is a sort of growth of ice crystal. Therefore, the frozen layer 135 is not transparent, and thus it is difficult to read information such as pattern and ID that is formed on the object 119 formed below the frozen layer 135. However, this can be solved by melting a part of the frozen layer 135 and then recooling it Therefore, the laser processing apparatus according to the embodiment further includes a thawing unit 510.

The thawing unit 510 that melts the frozen layer 135 may be configured by a contact type or a non-contact type. When a contact type is used to melt 135 the frozen layer 135, in order to allow a heated metal plate to slide on a surface of the frozen layer, the thawing unit 510 is formed of a metal plate. In contrast, when a non-contact type is used to melt the frozen layer 135, the thawing unit 510 may be formed of a heating coil to uniformly spray the warm air onto the frozen layer 135. The contact type thawing unit 510 is useful for a frozen layer 135 having a even surface, and the non- contact type thawing unit 510 is useful for a frozen layer 135 having even or uneven surface.

In addition, the thickness of the frozen layer 135 that is formed on the surface of the object 119 changes depending on the humidity in the chamber 500, and the humidity changes depending on the temperature. In this embodiment, in order to adjust the thickness of the frozen layer 135 by controlling the temperature and the humidity in the chamber 500, a sensor 508 is attached into the chamber 500. Generally, since the humidity of the chamber 500 is controlled to be low, it does not need to consider a problem that the thickness of the frozen layer 135 becomes thicker due to the excessive humidity. Further, in order to prevent the frozen layer 135 from being insufficiently formed due to the insufficient moisture of the chamber when the humidity of the chamber 500 that is detected by the sensor 508 is lower than a predetermined value, a humidifier 506 that provides moisture into the chamber 500 is added.

Figs. 23a to 23d are diagrams showing an example that the object is processed using the laser processing apparatus shown in Fig.22.

As shown in Fig. 23a, the object 119 that is fixed on the stage is cooled by the thermoelectric cooling module 502 that is provided below the stage to form the frozen layer 135. Further, as shown in Fig.23b, the laser beam is irradiated onto a specified processing position. After the laser beam is irradiated to complete the processing, as shown in Fig. 23c, particles

G that are residual products are attached onto the surface of the frozen layer 135, and another frozen layer 137 is formed around the processed portion F. That is, since the cooling state of the object 119 is maintained during the irradiating of the laser beam, the frozen layer 137 is formed around the processed portion F due to the difference in temperature of the object 119 and the chamber. After completing the processing, the object is subjected to wet or dry cleansing process to remove the frozen layers 135 and the particles G. Therefore, as shown in Fig. 23d, the processed object 119 having a desired processed portion F that is cleansed can be obtained.

Since the processing of the object that uses a laser is non-contact method, it is difficult to adjust the processing height of the laser beam. Further, a portion to which the laser beam is not directly contacted due to the heat may be influenced by the laser beam. Therefore, as for the material of the stage on which the object is placed, a material having an absorption coefficient much lower than the transmittance/reflectance with respect to the laser beam at the time of laser processing is preferable.

In order to process the object using the laser beam, a processing tape is attached onto the stage, and then the object is placed thereoα In this case, the processing tape has a thickness of 100 to 400 μm, and has heat resistance that can resist up to 400⁰C.

Generally, during the processing that uses the laser, most laser beam transmits not to affect the processing tape or the chip. However, when the size of the chip is below a predetermined size, for example, when width*length is less than 3 mm * 3 mm or the width of the chip cutting line is less than 5 mm, a surplus energy that exceeds the energy transmitting the narrow area is accumulated, and thus reflecting or scattering energy is increased to affect the processing tape, which damages the processing tape.

In other word, even though the stage is manufactured using a material suitable for the laser processing, the temperature of the processing tape can be risen up to 1000⁰C depending on the processing parameters such as the diameter or the thickness of the object, the width and the number of the chip cutting lines. In this case, the processing tape is broken or melted to be damaged.

Accordingly, when the processed object needs to be moved to another apparatus, the chips on the object are flown (scattered). Therefore, the next processing can not be proceeded. Further, if the processing tape is melted and attached onto the stage not to be separated after the processing, all the chips on the object can not be used

In order to overcome the above drawback, according to the embodiment, the stage on which the object is placed has a cooling functioa

Fig.24 is an exemplary diagram of a stage that is applied to this invention. The stage 121 shown in Fig. 24 includes: a body 1211 having a plurality of vacuum holes on which the object is placed, a vacuum part 1213 that is provided rear of the body 1211 and has a vacuum pipeline sucking air, and a thermoelectric cooling module 1215 and a cooling pipeline unit 1217 that are formed rear of the vacuum part 1213 and serve as a cooling unit that discharges the heat accumulated on the body 1211. In this case, the thermoelectric cooling module 1215 cools the heat generated from the body

1211, and the cooling pipeline unit 1217 is provided rear of the thermoelectric cooling module 1215 and cools the thermoelectric cooling module 1215 by the circulation of the refrigerant

Figs.25a to 25d are detailed construction diagrams showing parts of the stage shown in Fig. 24. At first, as shown in Fig. 25a, the body 1211 includes a plurality of vacuum holes 12111, and the processing tape and the object are subsequently placed on the top surface thereof. The plurality of vacuum holes 12111 is formed in the body 1211, and is connected to a vacuum pipeline that is formed in the external pump (not shown), and absorbs and fixes the object that is placed on the top surface using the vacuum pressure from the pump. In this case, the vacuum pressure from the pump is preferably 50 to 80 kpa.

Further, the body 1211 may be formed of any one of quartz, porous glass, silver ceramic, and iron ore, and the silver ceramic refers ceramic containing silver.

Next, Fig. 25b is a detailed construction diagram of the vacuum part 1213, and the vacuum holes 12131 are formed at the center of the vacuum part 1213. Further, when the plurality of vacuum holes 12111 is formed on a plurality of concentric circles having different diameters of the body 1211, vacuum pipelines 12132 are concentrically formed according to the arrangement of the vacuum holes 12111 formed on the concentric circles. Therefore, the air is sucked through the vacuum pipelines 12132 so that the object is adsorbed onto the body 1211. Fig. 25c is a diagram of an example of the thermoelectric cooling module 1215, and the thermoelectric cooling module 1215 includes at least one thermoelectric element 12151.

The thermoelectric element 12151 is a functional element that is capable of converting a thermal energy into an electric energy or an electric energy into a thermal energy. The thermoelectric element is also referred to a Peltier element The thermoelectric element 1215 moves heats from an endothermic surface to a radiant surface and changes between the heating and the cooling by changing the heat transferring direction. Further, the thermoelectric element 1215 can control the temperature of minute faucet by the voltage/current control, not on/ofT control. Further, since there is no movable portion, there is no vibration and noise. Furthermore, since Freon refrigerant is not used, there is no contamination or pollution. In Fig. 25c, the thermoelectric elements 12151 are preferably arranged in a radial shape along the vacuum pipelines 12132 of the vacuum part 1213 shown in Fig.25b.

Next, Fig.25d is a detailed construction diagram showing the cooling pipeline unit 1217.

The cooling pipeline unit 1217 circulates the refrigerant that flows therein through a refrigerant flowing unit 12171 using a cooling pipeline 12173 to cool the thermoelectric cooling module 1215. The refrigerant that flows into a water tank (not shown) is compressed by an compressor and then provided to the cooling pipeline 12137 through the refrigerant flowing unit

12171 by a pump to be circulated. The refrigerant is any one of water, a mixture of water and Ethylene glycol, air, other cooling gas or cooling liquid. Further, in order to adjust the flow rate of the refrigerant that passes through the cooling pipeline 12173 of the cooling pipeline unit 1217, a flow control valve (not shown) may be provided in the cooling pipeline 12173. The flow rate of the refrigerant can be controlled by changing a pumping rate or other parameters.

In Fig. 25d, even though the cooling pipeline 12173 is curve, cooling pipelines may be configured such that a plurality of straight cooling pipelines that concentrically extends is connected to a plurality of straight cooling pipelines. Further, the cooling pipelines may be configured in a spiral shape.

In another embodiment, the refrigerant flowing unit 12171 and a refrigerant outflow unit

12172 may be plural. The object is processed by changing the cooling temperature depending on whether a coating layer is formed on the surface of the object using the stage 121 as described above.

In the case of processing the object on which the coating layer is not formed, as shown in Fig. 22, a frozen layer is formed on the surface of the object and thus the object can be safely processed without the process for forming the coating layer. Further, in the case of processing the object on which a coating layer is formed, the temperature of the body 1211 is necessarily maintained to the dew point or larger because the coating layer is formed of a water soluble material. That is, if the temperature is below the dew point, drops of water begins to be formed on the surface of the object, and thus the coating material is melt not to perform its functioa

In this case, the temperature of the body 1211 is preferably 0 to 20°C. In order to detect the temperature of the body 1211, a thermometer (not shown) is attached onto the body 1211.

Therefore, the power that is supplied to the thermoelectric cooling module 1215 is controlled to be turned on/off on the basis of the value measured by the thermometer, thereby maintaining the temperature of the body 1211 to a predetermined temperature.

The thermoelectric cooling module shown in Figs. 22 and 25c has the same configuration as the thermoelectric cooling module shown in Fig.26.

Fig. 26 is a diagram showing an example of a thermoelectric element that is applied to the invention. A lower conductive layer 620 and an upper conductive layer 622 are formed between a lower substrate 610 and an upper substrate 612. Further, semiconductor chips are formed between the lower conductive layer 620 and the upper conductive layer 622. When a power is supplied to power supply cables 640 and 642, cooling is performed.

Here, the lower substrate 610 and the upper substrate 612 effectively transfer the heat, and control the current Further, the lower conductive layer 620, the upper conductive layer 622, and the semiconductor chips serve as actual cooling engines. The semiconductor chips are configured such that P-type semiconductors and N-type semiconductors are connected in series to express maximum cooling efficiency.

Laser Processing Apparatus That Simultaneously Processes Multiple Processing Lines During the processing of an object using a laser, a processing such as multipass cutting that simultaneously processes two or more lines may be needed. For this sake, a processing object or a laser beam generating device needs to be repeatedly moved several times. Therefore, the above processing is ineffective in time and cost. Therefore, this invention suggests a method of simultaneously processing a plurality of processing lines.

Fig. 27 is a configuration diagram showing a laser processing apparatus according to a fifth embodiment of the invention.

As shown in Fig. 27, a laser processing apparatus according to a fifth embodiment includes: a controller 101 that controls the overall operation; at least two laser generating units 139-1 and 139-2 that output laser beams having a specified diameter, at least two beam splitting unit 141-1 and 141-2 that receive the laser beam emitted from the laser generating units 139-1 and 139-2 to split into at least two beams; a driver 107 that drives a reflective mirror 147; an input unit 109 that inputs control parameters and control commands; an output unit 111 that displays information such as operation status; a storage unit 113 that stores data; at least two mirrors 145-1 and 145-2 that reflect the laser beam output from the beam splitting units 141-1 and 141-2 onto the same position; actuators 143-1 and 143-2 that control the angles and the positions of the mirrors 145-1 and 145-2 in order to reflect the laser beam output from the beam splitting units 141-1 and 141-2 onto the same position; the reflective mirror 147 that reflects the laser beams that are reflected from the mirrors 145-1 and 145-2 to be incident onto the same position from the different directions; a reflective mirror driving unit 149 that repeatedly rotates the reflective mirror 147 within a predetermined angle range so as to have a predetermined angular velocity; and an optic system 117 that condenses the laser beam reflected from the reflective mirror 147. In this case, an object 119 is placed on a stage 121.

According to the fifth embodiment, the laser processing apparatus further includes a stage transfer unit 123 that transfers at least one time the stage 121 on which the object 119 is placed to the direction opposing to the irradiation direction of the laser beam during the processing of the object 119.

Further, the optic system 117 is preferably embodied by a condensing lens. Here, the mirrors 145-1 and 145-2 reflect the laser beams emitted from the beam splitting units 141-1 and 141-2 on the same position of the reflective mirror 147. Further, the gradient and the position of the mirrors 145-1 and 145-2 are adjusted using the actuators 143-1 and 143-2 to reflect the laser beams into the different specified directions to be reflected from the reflective mirror 147,

The reflective mirror 147 is provided to be perpendicular to the stage 121 on which the object 119 to be processed is placed and the optic system 117 is provided to be horizontal with the stage 121 on which the object 119 to be processed is placed to condense the laser beams reflected from the reflective mirror 147.

Further, the gradient and the position of the mirrors 145-1 and 145-2 are controlled by the respective actuators 143-1 and 143-2. Therefore, the laser beams that are reflected in the different directions by the reflective mirror 147 are condensed by the optic system 117 to control the distance between a pair of laser beams and the position of the laser beams that are irradiated perpendicularly to the object 119 that is placed on the stage 121.

In the meantime, the reflective mirror driving unit 149 rotates the reflective mirror 147 within a predetermined angle range at a predetermined speed according to the control of the controller 101. According to the laser processing apparatus having the above configuration, according to the control of the controller 101, the laser beams are split into at least two beams by the first and second beam splitting units 141-1 and 141-2, and then enter the first mirror 145-1 and the second mirror 145-2. The actuators 143-1 and 143-2 control the gradients and the positions of the first and second mirrors 145-1 and 145-2 to allow the laser beams to enter the same position of the reflective mirror 147 that rotates by the reflective mirror driving unit 149. Thereafter, the laser beams reflected from the reflective mirror 147 are condensed in the different positions of the optic system 117 to be irradiated perpendicularly to the object 119.

In this case, the slanting angles and the positions of the first and second mirrors 145-1 and 145-2 are controlled by the actuators 143-1 and 143-2 so that the distance between a pair of laser beams that are irradiated perpendicularly to the object 119 can be controlled.

Further, when the reflection surface of the reflective mirror 147 rotates at a predetermined angle, the laser beam that is irradiated onto the object 119 moves with a scanning length in a direction opposing to the transferring direction of the stage 121. Even not shown, the laser processing apparatus according to this embodiment includes at least two beam forming units to change the shape of the laser beam passing through the optic system 117 into an oval shape. Since the details are described above, the description thereof will be omitted.

Even though in the embodiment, the laser processing apparatus including two laser beam generating units is described, one laser beam generating unit can be used if necessary. In this case, the laser beam emitted from the laser beam generating unit is split by the beam splitter to be incident onto the beam splitting unit

Fig. 28 is an exemplary diagram showing a first modification of the laser processing apparatus shown in Fig.27. The laser beam processing unit shown in Fig.28 uses a polygon mirror 151 as the reflective mirror.

In this embodiment, the polygon mirror 151 includes a plurality of reflection surfaces 153 and rotates with respect to a rotation axis 152. Further, the driver 107 rotates the polygon mirror 151 using a motor (not shown) at a predetermined constant speed The laser beams reflected from the first and second mirrors 145-1 and 145-2 enter onto the reflection surface 153 of the polygon mirror 151 to be reflected, and then are irradiated onto the object 119 of the stage 121 by the optic system 117. Since the detailed operation principle is the same as Fig.27, the description will be omitted. In this embodiment, even though the number of laser generating units 139-1 and 139-2 is preferably two, one laser generating unit may be used if necessary. When one of laser generating unit is used, the laser beam is split into two beams using the beam splitter.

Further, the laser processing apparatus according to this embodiment also further includes at least two beam forming units that change the section of the laser beams passing through the optic system 117 into an oval.

In the meantime, even though not shown, the reflective mirror shown in Fig. 27 is configured by an AOD. In this case, the driver 107 is replaced with an RF driver.

Fig. 29 is an exemplary diagram showing a second modification of the laser processing apparatus shown in Fig.27. As shown in Fig.27, a laser processing apparatus according to a fifth embodiment includes: a controller 101 that controls the overall operation; at least two laser generating units 139-1 and 139-2 that output laser beams having a specified diameter, at least two beam splitting unit 141-1 and 141-2 that receive the laser beam emitted from the laser generating units 139-1 and 139-2 to split into at least two beams; a driver 107 that drives polygon mirrors 155-1 and 155-2; an input unit 109 that inputs control parameters and control commands; an output unit 111 that displays information such as operation status; a storage unit 113 that stores data; at least two polygon mirrors 155-1 and 155-2 that has a plurality of reflection surfaces 153-1 and 153-2 and rotate symmetric to each other with respect to the rotation axis; at least two reflective mirrors 157-1 and 157-2 that reflect the laser beam reflected from the polygon mirrors 155-1 and 155-2; and an optic system 117 that condenses the laser beam reflected from the reflective mirrors 157-1 and 157-2 . In this case, an object 119 is placed on a stage 121. The laser processing apparatus farther includes a stage transfer unit 123 that transfers at least one time the stage 121 on which the object 119 is placed to the direction opposing to the irradiation direction of the laser beam during the processing of the object 119. Furthermore, the optic system 117 is preferably embodied by a condensing lens

The pair of polygon mirrors 155-1 and 155-2 are provided horizontally to the stage 121 on which the object 119 to be processed is placed, and the reflective mirrors 157-1 and 157-2 are provided between the polygon mirrors 155-1 and 155-2. The reflective mirrors 157-1 and 157-2 are slanted with a predetermined angle so as to face perpendicular to the stage 121 such that the laser beam reflected from the reflection surfaces 153-1 and 153-2 of the polygon mirrors 155-1 and 155-2 are reflected toward the optic system 117.

In this case, the optic system 117 is provided perpendicularly to the stage 121 on which the object 119 to be processed is placed to condense the laser beams reflected from the reflective mirrors 157-1 and 157-2. Further, the gradient of the reflective 157-1 and 157-2 can be controlled to control the distance between a pair of laser beams that are perpendicularly irradiated onto the object 119. That is, when the reflective mirrors 157-1 and 157-2 are more slanted with respect to a direction perpendicular to the stage 121 , the distance between the laser beams that are irradiated onto the object 119 becomes smaller. In contrast, when the reflective mirrors 157-1 and 157-2 are less slanted with respect to a direction perpendicular to the stage 121, the distance between the laser beams that are irradiated onto the object 119 becomes larger.

According to the laser processing apparatus of this embodiment, according to the control of the controller 101, the laser beams generated from the two laser generating units 139-1 and 139-2 enter the first polygon mirror 155-1 and the second polygon mirror 155-2. The laser beams that enter the polygon mirrors 155-1 and 155-2 rotate symmetrically to each other by the driver 107 and are reflected from the reflection surfaces 153-1 and 153-2 toward the first mirror 157-1 and the second mirror 157-2 that are provided between the first polygon mirror 155-1 and the second polygon mirror 155-2. The laser beams that are reflected toward the first mirror 157-1 and the second mirror 157-2 are reflected from the first and second mirrors 157-1 and 157-2 that are slanted at a predetermined angle in a direction opposing to the stage 121 toward the optic system 117. Further, the laser beams reflected from the first mirror 157-1 and the second mirror 157-2 are condensed by the optic system 117 to be irradiated perpendicularly to the object 119.

Fig. 30 is an exemplary diagram showing a third modification of the laser processing apparatus shown in Fig.27. The laser processing apparatus according to this embodiment uses one laser generating unit and a beam splitting unit and split the laser beam emitted from the beam splitting unit using the beam splitter 159 to simultaneously process the multilines.

That is, the laser beam emitted from the laser generating unit 103 is split into at least two beams by the beam splitting unit 105, and each of the laser beams emitted from the beam splitting unit 105 is split into two beams by the beam splitter 159. The laser beams that transmit the beam splitter 159 enter the first polygon mirror 155-1 and the laser beams that are reflected from the beam splitter 159 enter the second polygon mirror 155-2.

Since the proceeding of the laser beam through the first and second polygon mirrors 155-1 and 155-2, the reflective mirrors 157-1 and 157-2, and the optic system 117 is the same as the description shown in Fig.29, the details will be omitted.

The fifth embodiment of the invention has an advantage in that since the laser beams are reflected onto the different positions and then condensed to be irradiated onto the object, a plurality of processing portions can be processed by single processing step.

Further, the laser processing apparatus shown in Figs. 29 and 30 includes at least two beam forming units that form the laser beam passing through the optic system 117 to have an oval sectional shape. In this case, the residual products can be easily discharged from the processed surface, which increases the processing efficiency.

Furthermore, the polygon mirror shown in Figs. 29 and 30 can be replaced with an AOD, and the driver 107 is also replaced with an RF driver.

Laser Processing Method using Laser Beam Splitting and Stage Transferring Fig.31 is a flow chart illustrating a laser processing method according to a first embodiment of the invention, and the laser processing method according to the first embodiment can be applied when the laser processing apparatus shown in Fig. 1 , 9, 14, 16 or 20 is used.

At first, according to a kind of object 119 to be processed and the processing purpose, control parameters such as a rotational speed of the beam scanner 115, a transferring speed of the stage transfer unit 123, a processing time, a frequency of the laser beam, a power of the laser beam are set using an input unit 109 (SlOl). The setting can be easily performed by registering menu that is previously set according to the kind of object and die processing purpose, and storing in the storing unit 113, and then calling the menu.

After setting the control parameters, the beam scanner 115 (or polygon mirror 115-1) is driven by a driver 107 (S103), and then a stage transfer unit 123 is driven to transfer the stage 121 in a specified direction (opposing to the irradiation direction of the laser beam) (S 105). Thereafter, when the laser beam is emitted from the laser generating unit 103 (S 107), the emitted laser beam enters the beam splitting unit 105 to be split into at least two beams (S109), and then the split laser beams are reflected from the beam scanner 115 (or polygon mirror 115-1) to be condensed by the optic system 117 and then irradiated onto the object 119 to process the object (Sill). According to the embodiment, the laser beam is split into a plurality of beams, which reduces the processing beam width and maintains the intensity of the laser beam. Further, the stage is transferred in a direction opposing to the direction that the laser beam is irradiated onto the object, which improves the processing speed. Further, when this method is applied to a laser processing apparatus that uses a polygon mirror, the laser beam is superposely irradiated on the object by rotating the polygon mirror to improve the processing efficiency.

Laser Processing Method Through Error Correction of Polygon Mirror Fig. 32 is a flow chart illustrating a laser processing method according to a second embodiment of the invention, and for example, the method can be applied when the laser processing apparatus shown in Fig. 10 is used.

At first, after a test object is placed on the stage 121, the driver 107 drives the polygon mirror 115-1, and the laser beam emitted from the laser generating unit 103 is split in the beam splitting unit 105 to be irradiated onto the reflection surface of the polygon mirror 115-1 (S201).

Like this, after the test object is processed by rotating the polygon mirror 155-1 at least one time, the error on the reflection surface of the polygon mirror is measured using the processing result of the test object, and the result is input to the error correcting unit 125 to calculate the error correction value of the reflection surface of the polygon mirror, that is, an adjusted incident angle of the laser beam (S203).

After the error compensated value on the respective reflection surfaces of the polygon mirror 115-1 is calculated, in order to process the actual processing object, control parameters according to the objects such as a rotational speed of the beam scanner, a transferring speed of the stage, a processing time, a frequency/power of the laser beam are set using an input unit 109 (S205). The setting can be easily performed by registering menu that is previously set according to the kind of object and the processing type (cutting or grooving), and storing in the storing unit 113, and then calling the menu.

After setting the control parameters, the driver 107 is controlled to constantly rotate the polygon mirror 115-1 at a previously set speed and drive the actuator 200 (S207), and then a stage transfer unit 123 is driven to transfer the stage 121 at a set speed (S209).

Thereafter, laser beams that are emitted from the laser generating unit 103 (S211) and split into at least two beams by the beam splitting unit 105 (S213) are incident onto the reflection surface of the polygon mirror 115-1 through a mirror 202 mounted onto the actuator 200. Further, the laser beams reflected from the reflection surface of the polygon mirror 115-1 is condensed by the optic system 117 and then irradiated onto the object 119 (S215).

When the laser beam emitted from the laser generating unit 103 is split by the beam splitting unit 105 and then irradiated onto the mirror 202, the controller 101 drives the actuator 200 on the basis of the error compensated value that is previously calculated to control the direction of the mirror 202. Therefore, the laser beam is irradiated by changing the incident angle with respect to a portion of a reflection surface of the polygon mirror having an error, which allows the laser beam to be reflected from the polygon mirror with the same angle.

Laser Processing Method through Laser Beam Splitting and Object Cooling Fig. 33 is a flow chart illustrating a laser processing method according to a third embodiment of the invention, and for example, this method can be applied when the laser processing apparatus shown in Fig.22 is used.

In order to process the object, the stage 121 on which the object 119 is placed is loaded in the chamber 500. Further, the control parameters according to the object to be processed are set (S301). The setting can be easily performed by registering menu that is previously set according to the kind of object and the processing type and storing in the storing unit 113, and then calling the menu..

After setting the control parameters, the thermoelectric cooling module 502 is driven to cool the object 119, and thus the frozen layer 135 is formed on the surface of the object 119 (S303). The object 119 can be cooled by the thermoelectric cooling module 502 after being loaded in the chamber

500. Further, a preliminarily frozen object can be loaded in the chamber 500 in order to reduce the cooling time. In this case, as described above, in order to prevent the congelated moist from being cooled between the object 119 and the stage 121, the object is preferably preliminarily frozen at a temperature higher than the freezing point

Furthermore, in order to solve the drawback that since the frozen layer 135 formed on a surface of the object 119 is not transparent, it is difficult to observe the surface of the object 119, a part of the frozen layer 135 is melted by a thawing unit 510 and then recooled to obtain a transparent frozen layer 135. When melting the frozen layer 135, a contact type that the heated metal plate is slid on the surface of the frozen layer 135 or a non-contact type that a warm air is uniformly scattered on the surface of the frozen layer 135 may be used.

Further, when the humidity of the chamber 500 that is detected by the sensor 508 is lower than a specified value, moisture is supplied into the chamber 500 by the humidifier 506 to form a frozen layer 135 having a sufficient thickness. Thereafter, the driver 107 drives the beam scanner 115 (S305) and the stage transfer unit

123 to transfer the stage 121 at a set speed (S307). Further the laser generating unit 103 is controlled to emit the laser beam (S309).

As this, the laser beam emitted from the laser generating unit 103 is split into at least two beams by the beam splitting unit 105 (S311), and then irradiated onto the object 119 by the beam scanner 115 and the optic system 117 to perform the processing (S313).

After completing the processing, the cleaning is performed in order to remove the frozen layer 135 on the object 119 and particles generated during the processing (S315). The wet or dry cleansing may be performed. The wet cleansing uses water to remove the particles attached onto the surface of the frozen layer 135 together with the frozen layer 135. Further, the dry cleansing sprays gas (warm air) onto the surface of the frozen layer 135 to melt the frozen layer 135 and remove the particles attached onto the surface of the frozen layer 135. As the result of the cleansing, water from the melting of the frozen layer is obtained, and the water contains the particles. The particles can be collected by a filter, which prevents the occurrence of the industrial waste water. When the object processing and the cleansing are completed, the object is unloaded from the chamber, and then subsequent processings are proceeded.

Multilayered Object Processing Method

The object that is processed by the laser may be formed of a single layer, or multilayer. However, if the multilayered object is processed under Ihe same processing condition, separation or explosion may be generated at the interface of the layers.

That is, since each layer has unique optical, physical, and chemical properties, the object needs to be processed by adjusting the processing parameter according to the property of the layer.

Therefore, when processing the multilayered object, if the object is processed by changing the processing parameter for every layer, it is possible to improve the processing efficiency and prevent the propagation of the crack that occurs during the object processing.

Fig. 34 is a flow chart illustrating a laser processing method according to a fourth embodiment of the invention, and shows the multilayered object processing method.

At first, processing parameters for every layer are set (S401). In this case, parameters that are previously set includes a laser output power, a rotational speed of the mirror (mirror of the beam scanner, polygon mirror or AOD), a transferring speed of the stage on which the object is placed, a frequency of the laser beam, and a focal position of the laser beam.

After setting the processing parameter for every layer, the laser processing apparatus using a mirror is driven to process the exposed layer of the object (S403). After completing the processing of the exposed upper layer, whether all layers are processed is checked (S405). If the all layers have been processed, the processing is completed. Otherwise, that is, if layers to be processed are left, the process returns to step S403.

The step (S403) of processing the exposed layers of the object will be described in detail. At first, the beam scanner (or polygon mirror or AOD) is driven (S4031), and then the stage on which the object is placed is transferred (S4033). In this case, the stage is preferably transferred in the direction opposing to the processing direction. Thereafter, the laser beam is emitted (S4035), the emitted laser beam is split into a plurality of beams by the beam splitting unit (S4037), and reflected from the reflection surface of the beam scanner (or polygon mirror or AOD) to be irradiated onto the object by the optic system.

As described above, in this embodiment, when the multilayered object is processed, the processing parameters are optimally set for every layer, and the each layer is processed using the different processing parameters. Therefore, it is possible to prevent the separation or explosion at the interfaces of the layers. Fig. 35 is a flow chart illustrating an example of an object processing method shown in Fig.

34.

The object processing method according to this embodiment includes a scribing step (S501) and a laser cutting step (S503).

When the multilayered object is directly processed by a laser, crack may be formed due to the difference in the properties of the layers. If the crack is propagated to an active region (chip region), the yield becomes lowered. Therefore, before the laser processing, the both edges in the processing area are scribed, and then cut by the laser processing, thereby reducing the occurrence rate of the crack. Figs. 36a and 36b are diagrams illustrating an example that an object is processed according to the processing method shown in Fig. 35

As described in Fig. 36a, after forming active regions 22 and 24 on semiconductor substrate 20, when the cutting step is performed to separate between the active regions, before the cutting step, the edge 26 of the processing region is processed by the scribing step. Thereafter, as shown in Fig. 36b, the processing region is removed using the laser processing apparatus. In this case, if a semiconductor substrate 20 in the processing region is formed of multi-layers, as shown in Fig. 34, it is preferable to process the semiconductor substrate 20 using the processing parameters that are set to be different for respective layers.

Further, in this embodiment, the scribing step can be also performed using the laser processing apparatus.

Even though not shown, if a healing step is performed after performing the cutting step (S503), it is possible to effectively remove the crack formed during the cutting step that uses the laser.

Fig. 37 is a flow chart illustrating another example of an object processing method shown in Fig. 34. When the multilayered object is processed using a laser, crack may be formed in the processed portion to be propagated to the active region. In order to prevent this, in this embodiment, after cutting the object (S601), the cut portion is healed (S603).

More specifically, the processing area is cut using the laser processing apparatus, In this case, when the processing object is formed of multi-layers, it is preferable to process the object using the processing method shown in Fig. 34 on the basis of the processing parameters that are set for every layer.

However, the crack may be formed at the processing portion by the cutting step. Therefore, the healing step is performed thereafter to bond the cracked portion, thereby increasing the processing efficiency.

Figs.38a and 38b are diagrams illustrating an example that an object is processed according to the processing method shown in Fig.37.

Referring to Fig.38a, it is known that the crack 28 is formed in the processing portion of the semiconductor substrate 20 when the semiconductor substrate 20 having the active regions 22 and 24 formed thereon is processed using the laser.

Therefore, in this case, the healing step as shown in Fig. 38b is performed to bond the cracked portioa For example, in the case of the silicon Si substrate, the substrate is changed into silicon dioxide to bond the cracked portion, thereby preventing the crack from propagating to the active regions. In summary, according to this embodiment, the processing parameters are set differently for every layer before processing the multilayered object, and then the layers are sequentially processed, thereby improving the processing reliability and the strength of a die.

Further, the edge of the processing portion is scribed before performing the multiprocessing using the polygon mirror, which prepares against the crack formed during the laser processing. Further, if the crack is formed, the crack portion is bonded by the healing step to prevent the crack from being propagated.

Laser Processing Method that Simultaneously Processes a plurality of Processing Lines Fig. 39 is a flow chart illustrating a laser processing method according to a fifth embodiment of the invention.

At first, using the input unit 109, control parameters such as the gradients and positions of the actuators 143-1 and 143-2, the rotation speed of the reflective mirror 147, and the transferring speed of the stage 121 on which the object 119 is placed is set depending on the object 119 (S701). The setting step is easily performed by registering menu that is previously set according to the kind of object s 119 to be processed and the processing type, and storing in the storing unit 113, and then calling the menu.

After setting the control parameters, tihe controller 101 controls the first actuator 143-1 and the second actuator 143-2 to adjust the first mirror 145-1 and the second mirror 143-2 to be in a preset position with a preset gradient angle (S703), and controls the driver 107 to repeatedly rotate the reflective mirror 147 at a preset rotational speed within a predetermined angle range (S705).

Further, the controller 101 controls the stage transfer unit 123 to transfer the stage 121 at a set speed

(S707). In this case, the controller 101 controls the two laser generating units 139-1 and 139-2 to emit the laser beam (S709). Thereafter, the emitted laser beam is split into at least two laser beams by the first and second beam splitting units 141-1 and 141-2 (S711), and then enters the first mirror 145-1 and the second 145-2. The laser beam that is incident onto the mirrors 145-1 and 145-2 is reflected by the mirrors 145-1 and 145-2 to be incident onto the same position of the reflective mirror from different directions. The laser beams that are incident onto the reflective mirror 147 is condensed by the optic system 117 through the reflection surface of the rotating reflective mirror 147, and then are irradiated perpendicularly to the object 119, thereby processing the plurality of processing lines at the same time

(S713).

In the above steps, since the reflective mirror 147 rotates at a constant speed, the scanning length of the laser beams are overlaid predetermined times to be irradiated onto the object 119. Further, when the stage 121 on which the object 119 is placed is transferred in the reverse direction to the rotation direction of the reflective mirror 147, the relative velocity that the laser beam is irradiated onto the object 119 with a scanning length becomes larger, and thus the object can be efficiently processed. According to the laser processing method shown in Figs. 31 to 34, and 29, when the laser beam passes through the optic system and then is irradiated onto the object through the beam forming unit, the shape of the beam that is irradiated onto the object is oval. In this case, the residual products generated during the object processing using the laser can be efficiently discharged, which maximizes the processing efficiency. It will be apparent to those skilled in the art that various modifications and changes may be made without departing from the scope and spirit of the inventioa Therefore, it should be understood that the above embodiment is not limitative, but illustrative in all aspects. The scope of the invention is defined by the appended claims rather than by the description preceding them, and therefore all changes and modifications that fall within metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the claims.

Industrial Applicability

According to the embodiments of the invention, since the laser beam is split into at least two beams to process the object, the same effect when the object is processed multiple times by the laser beam having a lower energy can be obtained, thereby securing the narrow beam width. Further, since the laser beams that are split into a plurality of beams are simultaneously irradiated onto the object, higher processing speed can be achieved.

Further, the stage is transferred into a direction opposing to the direction that the laser beam is irradiated onto the object, which improves the processing speed of the object Further, the object is processed using the laser beam that is adjusted to have an oval shape, and the residual products generated during the object processing are discharged outside, which prevent the residual products from being reattached onto the processing object, thereby improving the chip reliability of the subsequent process. Further, a mask that filters the laser beam that is emitted at the turning point of the mirror, among the laser beams that are emitted from the beam scanner is used, which prevents the object from being irregularly processed due to the laser beam emitted from the turning point of the mirror of the beam scanner.

In addition, the frozen layer is formed on the surface of the object using the thermoelectric cooling module or the cooling stage such that the object can be processed without forming additional coating layer, thereby reducing the cost required for cleansing process after processing the object

Furthermore, the particles generated during the laser processing are easily withdrawn by the cleansing step, which reduces the environmental contaminatioa

Meanwhile, a plurality of processing portions can be simultaneously processed using a plurality of laser generating units, which improves the processing speed and performance.

Finally, when a multilayered object is processed, processing parameters that are differently set depending on the properties of the layers are used to perform the processing. Therefore, it is possible to minimize the crack formed during the laser processing and prevent the crack from being propagated using the healing step, thereby significantly improving the yield and reliability of the elements.

Claims

What is claimed is:

1. A laser processing apparatus that irradiates a laser beam emitted from a laser generating unit onto an object to process the object, comprising: a beam splitting unit that splits a laser beam emitted from the laser generating unit into at least two laser beams; a beam scanner that receives the split laser beams from the beam splitting unit and reflects the beams so as to be repeatedly irradiated onto a processing position of the object; and a stage transfer unit that transfers at least one time a stage on which the object is placed to the direction opposing to the irradiation direction of the laser beam during the processing of the object

2. The apparatus of claim 1, further comprising: an optic system that condenses each of the laser beams reflected from the beam scanner; and at least two beam forming unit that form the sections of the laser beams passing through the optic system to irradiate onto the object

3. The apparatus of claim 2, wherein the beam forming unit includes: a first lens that changes the laser beam into a sheet light; and a second lens that is provided to have the transferring direction perpendicular to the first lens and changes the sheet light passing through the first lens to have an oval shape, and the first lens moves up and down to adjust the size of the oval laser beam passing through the second lens.

4. The apparatus of claim 3, wherein the first lens and the second lens are cylindrical lenses.

5. The apparatus of claim 3, wherein the object is processed such that the processing direction of the object is arranged to be matched with the major axis of the oval laser beam.

6. The apparatus of claim 3 or 5, wherein a ratio of minor axis and major axis of the oval laser beam is 1:4 to 1: 12.

7. The apparatus of claim 1, wherein the beam splitting unit includes a prism that splits a incident laser beam into two laser beams.

8. The apparatus of claim 1, wherein the beam splitting unit includes a beam splitter that splits the incident laser beam into two laser beams.

9. The apparatus of claim 1, wherein the beam splitting unit includes a beam splitter that splits the incident laser beam into two laser beams and a prism that splits one of two laser beams split from the beam splitter into two laser beams.

10. The apparatus of claim 1 , wherein the beam splitting unit includes a prism that splits the incident laser beam into two laser beams and a beam splitter that splits each of the two laser beams split from the prism into two laser beams.

11. The apparatus of claim 1 , wherein the beam splitting unit includes: a first mirror that reflects the incident laser beam; a prism that splits the laser beam reflected from the first mirror into two laser beams; and a second mirror that reflects the two beams split by the prism.

12. The apparatus of claim 1, wherein the beam splitting unit includes: a beam splitter that splits the incident laser beam into two beams; a polarizer that changes the polarizing characteristic of a first laser beam reflected from the beam splitter; a first mirror that reflects a second laser beam transmitting the beam splitter, a second mirror that reflects the second laser beam reflected from the first mirror, and a polarized beam splitter that reflects the first laser beam whose polarizing characteristics is changed by the polarizer and transmits the second laser beam reflected from the second mirror.

13. The apparatus of claim 1, wherein the beam splitting unit includes: a beam splitter that splits incident laser beam into two laser beams; a polarizer that changes the polarization characteristic of the laser beam reflected from the beam splitter; a prism that splits the laser beam polarized by the polarizer into first and second laser beams; a first mirror that reflects a third laser beam transmitting the beam splitter, a second mirror that reflects the third laser beam reflected from Ihe first mirror, and a polarized beam splitter that reflects the first and second laser beams emitted from the prism and transmits the third laser beam entering through the second mirror.

14. The apparatus of claim 1 , wherein the beam splitting unit includes: a prism that splits incident laser beam into two laser beams; a beam splitter that splits each of the two laser beams split by the prism into two laser beams to reflect and transmit; a polarizer that changes the polarization characteristic of the first and second laser beams reflected from the beam splitter, a first mirror that reflects third and fourth laser beams transmitting the beam splitter, a second mirror that reflects the third laser beam reflected from the first mirror, and a polarized beam splitter that reflects the first and second laser beams whose polarizing characteristics are changed by the polarizer and transmits the third and fourth laser beams entering through the second mirror.

15. The apparatus of claim 1, wherein the beam scanner is any one of a galvanometer scanner and a reflecting device using a servo motor.

16. The apparatus of claim 1 , further comprising a driver, wherein the beam scanner includes: one or two motors that are driven by the driver, and first and second mirror that are connected to the rotation axis of the motors to repeatedly rotate at a predetermined angle and in a predetermined direction, and the first mirror reflects the laser beam reflected from the beam splitting unit to emit the second mirror, and the second mirror irradiates the laser beam that is incident from the first mirror onto the object.

17. The apparatus of claim 1 , further comprising a driver, wherein the beam scanner is a polygon mirror that includes a plurality of reflection surfaces and rotates with respect to the rotation axis at an angular velocity preset by the driver.

18. The apparatus of claim 17, wherein the scanning length of the laser beam that is irradiated onto the object according to the rotation of the polygon mirror is calculated by multiplying the focal length of the optic system and the angle of the laser beams that are reflected from the reflection surfaces of the polygon mirror.

19. The apparatus of claim 18, wherein the angle of the laser beam is formed by the laser beams reflected from both edges of the reflection surface.

20. The apparatus of claim 17, wherein the laser beam that is reflected from the reflection surface is superposely irradiated a predetermined times on the object by rotating the polygon mirror and the overlay frequency is controlled by adjusting the angular velocity of the polygon mirror while constantly maintaining the transferring speed of the stage.

21. The apparatus of claim 17, further comprising: an encoder that is mounted onto the polygon mirror and converts information on the position and the velocity of the polygon mirror into electrical signals to output; an error correcting unit that receives an error values with respect to each of the reflection surfaces of the polygon mirror and calculates an error compensated value of the each reflection surface; and an actuator that receives the information of the reflection surface of the polygon mirror from the encoder to drive the mirror referring to the error compensated value with respect to the reflection surface and to change the incident direction of the laser beam that is emitted from the beam splitting unit to the reflection surface of the polygon mirror.

22. The apparatus of claim 21 , wherein the encoder is a rotary encoder.

23. The apparatus of claim 17, wherein the polygon mirror has a limited number of reflection surfaces so that when the laser beam input from the beam splitting unit is incident onto the reflection surface of the polygon mirror, the laser beams are simultaneously incident onto the plurality of reflection surfaces.

24. The apparatus of claim 23, wherein when a radius of a circumscribed circle of the polygon mirror is R, a diameter of the laser beam is D, a linear distance from Ihe rotation axis to the center of the laser beam that is irradiated onto the polygon mirror is h, an loss angle of the incident laser beam with reduced energy with respect to the total laser beam that is incident onto one reflection surface of the polygon mirror is

and the loss rate on the one reflection surface of the polygon mirror when the number of reflection

t_r= -~~ x l OO ( %) surfaces of the polygon mirror is N is ^ ^π ,

Ihe number N of reflection surfaces of the polygon mirror is embodied so as to make the loss rate be 100% or more.

25. The apparatus of claim 1, further comprising an RF driver, wherein the beam scanner is an acousto-optic deflector that irradiates at least two laser beams input from the beam splitting unit onto the object in response to an RF signal from the RF driver.

26. The apparatus of claim 25, wherein the RF driver inputs two RF signals to the acousto- optic deflector and the acousto-optic deflector outputs the laser beam so as to be rotated at a scanning angle that is determined depending on the frequency of the RF signal input through the RF driver.

27. The apparatus of claim 1 , further comprising: an optic system that condenses the laser beams reflected from the beam scanner, and a mask being provided with holes H for filtering a laser beam emitted from the turning point of the beam scanner before the laser beam emitted from the beam scanner is incident onto the optic system.

28. The apparatus of claim 1, further comprising: an optic system that condenses the laser beams reflected from the beam scanner, and a mask that includes holes H for filtering a laser beam emitted from the turning point of the beam scanner before the laser beam emitted from the optic system is incident onto the object

29. The apparatus of claim 27 or 28, wherein the mask is formed of a metal.

30. The apparatus of claim 1, further comprising: a thermoelectric cooling module that is provided on the rear side of the stage to cool the object through the stage, forms dews on the surface of the object due to the condensation of the water vapor caused by the difference in the temperature between the inside of the chamber on which the object is loaded and the object, and continuously cools the object to form a frozen layer on the surface of the object as a coating layer; and an insulator that is provided on the rear side of the thermoelectric cooling module.

31. The apparatus of claim 30, further comprising: a sensor that measures the temperature and the humidity of the processing chamber.

32. The apparatus of claim 31 , further comprising: a humidifier that supplies moisture to the chamber when the humidity of the processing chamber is lower than a predetermined value on the basis of the result measured by the sensor.

33. The apparatus of claim 30, further comprising: a thawing unit that melts a part of the frozen layer, wherein the frozen layer on the surface of the object is recooled by the thermoelectric cooling module to be transparent

34. The apparatus of claim 33, wherein the thawing unit is embodied by a contact type or non-contact type.

35. The apparatus of claim 34, wherein the contact type thawing unit is a heatable metal plate, and the non-contact type thawing unit is a heater coil that is supplied with a vapor to heat

36. The apparatus of claim 30, wherein the object is preliminarily cooled at a temperature higher than the freezing point before being loaded in the processing chamber.

37. The apparatus of claim 1, wherein the stage includes: a body having a plurality of vacuum holes on which the object is placed; a vacuum part that is provided on the rear side of the body and has a vacuum pipeline sucking air formed along the vacuum holes; and a cooling unit that is formed below the vacuum part and discharges the heat accumulated on the body.

38. The apparatus of claim 37, wherein the cooling unit includes: a thermo electric cooling module unit that has a thermoelectric cooling module that adjusts the heat transferring direction to cool the heat generated from the body; and a cooling pipeline unit that is provided below the thermoelectric cooling module and cools the thermoelectric cooling module by circulating the refrigerant

39. The apparatus of claim 37, wherein the stage forther includes a thermometer that detect the temperature of the body, and the cooling unit is turned on/off on the basis of the result detected by the thermometer.

40. The apparatus of claim 37, wherein the body is formed of any one of quartz, porous glass, silver ceramic, and iron ore.

41. The apparatus of claim 37, wherein the vacuum pressure of the body is 50 to 80 kpa.

42. The apparatus of claim 38, wherein the refrigerant is any one of water, a mixture of water and Ethylene glycol, air, cooling gas or cooling liquid.

43. A laser processing apparatus that uses a laser to process an object, comprising: a plurality of laser generating units that emits laser beams; a plurality of beam splitting units that receives the laser beam emitted from the plurality of laser generating units and splits the laser beam into at least two laser beams; a plurality of mirrors that reflects the laser beams split from the beam splitting unit onto the same position; actuators that are provided in the plurality of mirrors to adjust the angle and the position of the mirrors; a reflective mirror that receives and reflects the laser beam reflected from each of the plurality of mirrors; and an optic system that condenses the laser beams reflected from the reflective mirror and irradiates onto the object.

44. A laser processing apparatus that uses a laser to process an object, comprising, a plurality of laser generating units that emits laser beams; a plurality of beam splitting units that receives the laser beam emitted from the plurality of laser generating units and splits the laser beam into at least two laser beams; a plurality of polygon mirrors that has a plurality of reflection surfaces to rotate with respect to the reflection axis and receives and reflects the laser beams split from the beam splitting unit; a plurality of reflective mirrors that reflects the laser beams reflected from the plurality of polygon minors; and an optic system that condenses the laser beams reflected from the reflective mirror and irradiates onto the object

45. A laser processing apparatus that uses a laser to process an object, comprising, a laser generating unit that emits laser beams; a plurality of beam splitting units that receives the laser beam emitted from the laser generating unit and splits the laser beam into at least two laser beams; a plurality of splitters that splits each of the laser beams split in the beam splitting units into at least two laser beams; a plurality of mirrors that receives and reflects the laser beams split from the beam splitter; a plurality of reflective mirrors that reflects the laser beam reflected from the plurality of mirrors; and an optic system that condenses the laser beams reflected from the reflective mirror and irradiates onto the object

46. The apparatus of any one of claims 43 to 45, further comprising: a stage transfer unit that transfers at least one time a stage on which the object is placed to the direction opposing to the irradiation direction of the laser beam during the processing of the object.

47. The apparatus of claim 43, wherein the reflective mirror is a polygon mirror.

48. The apparatus of claim 45, wherein the plurality of mirrors is polygon mirrors.

49. The apparatus of claim 47 or 48, wherein the scanning length of the laser beam that is irradiated onto the object according to the rotation of the polygon mirror is calculated by multiplying the focal length of the optic system and the angle of the laser beams that are reflected from the reflection surfaces of the polygon mirror.

50. The apparatus of claim 47 or 48, wherein the laser beam that is reflected from the reflection surface is superposely irradiated a predetermined times on the object by rotating the polygon mirror and the overlay frequency is controlled by adjusting the angular velocity of the polygon mirror while constantly maintaining the transferring speed of the stage.

51. The apparatus of claim 47 or 48, further comprising: an encoder that is mounted onto the polygon mirror and converts information on the position and the velocity of the polygon mirror into electrical signals to output; an error correcting unit that receives an error values with respect to each of the reflection surfaces of the polygon mirror and calculates an error compensated value of the each reflection surface; and an actuator that receives the information of the reflection surface of the polygon mirror from the encoder to drive the mirror referring to the error compensated value with respect to the reflection surface and to change the incident direction of the laser beam that is emitted from the beam splitting unit to the reflection surface of the polygon mirror.

52. The apparatus of claim 51 , wherein the encoder is a rotary encoder.

53. The apparatus of claim 47 or 48, wherein the polygon mirror has a limited number of reflection surfaces so that when the laser beam input from the beam splitting unit is incident onto the reflection surface of the polygon mirror, the laser beams are simultaneously incident onto the plurality of reflection surfaces.

54. The apparatus of claim 53, wherein when a radius of a circumscribed circle of the polygon mirror is R, a diameter of the laser beam is D, a linear distance from the rotation axis to the center of the laser beam that is irradiated onto the polygon mirror is h, an loss angle of the incident laser beam with reduced energy with respect to the total laser beam that is incident onto one reflection surface of the polygon mirror is

f_θ= arccos[l ^ { yj R ²-{R-h) ²-/^~R ²-(R-h-D) ²+D ²} ] 2^R and the loss rate on the one reflection surface of the polygon mirror when the number of reflection t_fJV t_r=⁼ -§— ^χ ioo(%) surfaces of the polygon mirror is N is , the number N of reflection surfaces of the polygon mirror is embodied so as to make the loss rate be 100% or more.

55. The apparatus of any one of claims 43 to 45, further comprising: at least two beam forming unit that form the sections of the laser beams passing through the optic system to irradiate onto the object.

56. The apparatus of claim 55, wherein the beam forming unit includes a first lens that changes the laser beam into a sheet light; and a second lens that is provided to have the transferring direction perpendicular to the first lens and changes the sheet light passing through the first leas to have an oval shape, and the first lens moves up and down to adjust the size of the oval laser beam passing through the second lens.

57. The apparatus of claim 56, wherein the first lens and the second lens are cylindrical lenses.

58. The apparatus of claim 54, wherein the object is processed such that the processing direction of the object is arranged to be matched with the major axis of the oval laser beam.

59. The apparatus of claim 54, wherein a ratio of miner axis and major axis of the oval laser beamis l:4to l: 12.

60. The apparatus of any one of claims 43 to 45, wherein the beam splitting unit includes a prism that splits the incident laser beam into two laser beams.

61. The apparatus of any one of claims 43 to 45, wherein the beam splitting unit includes a beam splitter that splits the incident laser beam into two laser beams.

62. The apparatus of any one of claims 43 to 45, wherein the beam splitting unit includes a beam splitter that splits the incident laser beam into two laser beams and a prism that splits one of the two laser beams split from the beam splitter into two laser beams.

63. The apparatus of any one of claims 43 to 45, wherein the beam splitting unit includes a prism splitter that splits the incident laser beam into two laser beams and a beam splitter that splits each of two laser beams split from the prism into two laser beams.

64. The apparatus of any one of claims 43 to 45, wherein the beam splitting unit includes: a first mirror that reflects the incident laser beam; a prism that splits the laser beam reflected from the first mirror into two laser beams; and a second mirror that reflects the two beams split by the prism.

65. The apparatus of any one of claims 43 to 45, wherein the beam splitting unit includes: a beam splitter that splits the incident laser beam into two beams; a polarizer that changes the polarizing characteristic of a first laser beam reflected from the beam splitter; a first mirror that reflects a second laser beam transmitting the beam splitter, a second mirror that reflects the second laser beam reflected from the first mirror, and a polarized beam splitter that reflects the first laser beam whose polarizing characteristics is changed by the polarizer and transmits the second laser beam reflected from the second mirror.

66. The apparatus of any one of claims 43 to 45, wherein the beam splitting unit includes: a beam splitter that splits incident laser beam into two laser beams; a polarizer that changes the polarization characteristic of the laser beam reflected from the beam splitter; a prism that splits the laser beam polarized by the polarizer into first and second laser beams; a first mirror that reflects a third laser beam transmitting the beam splitter, a second mirror that reflects the third laser beam reflected from the first mirror, and a polarized beam splitter that reflects the first and second laser beams emitted from the prism and transmits the third laser beam entering through the second mirror.

67. The apparatus of any one of claims 43 to 45, wherein the beam splitting unit includes: a prism that splits incident laser beam into two laser beams; a beam splitter that splits each of the two laser beams split by the prism into two laser beams to reflect and transmit; a polarizer that changes the polarization characteristic of the first and second laser beams reflected from the beam splitter, a first mirror that reflects third and fourth laser beams transmitting the beam splitter, a second mirror that reflects the third laser beam reflected from the first mirror, and a polarized beam splitter that reflects the first and second laser beams whose polarizing characteristics are changed by the polarizer and transmits the third and fourth laser beams entering through the second mirror.

68. The apparatus of any one of claims 43 to 45, further comprising an RF driver, wherein the reflective mirror is an acousto-optic deflector that reflects the plurality of laser beams input from the plurality of mirrors onto the optic system in response to an RF signal from the RF driver.

69. The apparatus of claim 68, wherein the RF driver inputs two RF signals to the acousto- optic deflector and the acousto-optic deflector outputs the laser beam so as to be rotated at a scanning angle that is determined depending on the frequency of the RF signal input through the RF driver.

70. A method of processing an object using a laser, comprising:

placing Ihe object on a stage; setting control parameters according to the kinds of objects and the processing purpose; driving abeam scanner and a stage transfer unit to transfer the stage at apreset speed; emitting a laser beam; splitting the emitted laser beam into at least two laser beams to irradiate onto the beam scanner; and irradiating the laser beam reflected from the beam scanner onto the object, wherein the stage is transferred to a direction opposing to the irradiation direction of the laser beam.

71. The method ofclaim 70, further comprising: before the irradiating of the laser beam reflected from the beam scanner onto the object, changing the section of the laser beam to be an oval shape.

72. The method of claim 71, wherein the laser beam is arranged such that the processing direction of the object is matched with the major axis of the oval laser beam.

73. The method ofclaim 70, wherein the beam scanner is a polygon mirror, and, the method further comprising: before the placing of the object on the stage, placing a test object on the stage; driving the polygon mirror, after emitting the laser beam and splitting the beam into two beams, allowing the laser beam to be incident onto the polygon mirror, calculating an error compensated value on each of the reflection surface of the polygon mirror according to the processing result of the test object, and adjusting an incident angle of the laser beam on the basis of the error compensated value, after the placing of the object on the stage and before the irradiating of the laser beam reflected from the polygon mirror onto the object

74. A method of processing a multilayered object using a laser, comprising: a first step of setting processing parameters with respect to layers of the multilayered object; a second step of irradiating a laser beam that is split into at least two laser beams onto the object on the basis of the processing parameters that are set with respect to a layer that is exposed onto the processing portion of the object to perform the laser processing; a third step of confirming whether all layers of the multilayered object are processed; and a fourth step of proceeding to the second step if all layers are not processed according a confirmed result in the third step.

75. The method of claim 74, wherein the second step includes: a second-first step of driving a beam scanner; a second-second step of transferring the stage on which the object is placed; a second-third step of emitting the laser beam; a second-fourth step of splitting the emitted laser beam into at least two laser beams; and a second-fifth step of reflecting the laser beam split into at least two laser beams from the beam scanner to irradiate onto the processing area of the object

76. The method of claim 75, wherein the stage is transferred to a direction opposing to the irradiation direction of the laser beam.

77. The method of claim 75, further comprising: before the irradiating of the laser beam reflected from the beam scanner onto the object, changing the section of the laser beam to be an oval shape.

78. The method of claim 77, wherein the laser beam is arranged such that the processing direction of the object is matched with the major axis of the oval laser beam.

79. The method of claim 74, wherein the processing parameter includes a laser output power, a rotational speed of the beam scanner, a transferring speed of the stage on which the object is placed, a frequency of the laser beam, and a focal position of the laser beam,

80. A method of processing a multilayered object using a laser, comprising: a first step of scribing both edge of a processing region of the multilayered object; and a second step of cutting the processing region by irradiating the laser beam that is split into at least two laser beams onto the object

81. The method of claim 80, wherein the second step includes: a second-first step of setting processing parameters with respect to layers of the multilayered object; a second-second step of performing the laser processing on the basis of the processing parameters that are set with respect to a layer that is exposed onto the processing portion of the object; a second-third step of rønfirming whether all layers of the multilayered object are processed; and a second-fourth step of proceeding to the second-second step if all layers are not processed according a confirmed result in the second-third step.

82. The method of claim 81, wherein the processing parameter includes a laser output power, a transferring speed of the stage on which the object is placed, a frequency of the laser beam, and a focal position of the laser beam.

83. The method of claim 81, wherein the second-second step performs the laser processing by changing the section of the laser beam to have an oval shape.

84. The method of claim 83, wherein the laser beam is arranged such that the processing direction of the object is matched with the major axis of the oval laser beam.

85. The method of claim 80, further comprising: after the second step, a third step of healing the processing region.

86. A method of processing a multilayered object using a laser, comprising; a first step of cutting the processing region by irradiating the laser beam that is split into at least two laser beams onto the object; and a second step of healing Hie processing region of the cut object

87. The method of claim 86, wherein the first step includes: a first-first step of setting processing parameters with respect to layers of the multilayered object; a first-second step of performing the laser processing on the basis of the processing parameters that are set with respect to a layer that is exposed onto the processing portion of the object; a first-third step of confirming whether all layers of the multilayered object are processed; and a first-fourth step of proceeding to the first-second step if all layers are not processed according a confirmed result in the first-third step.

88. The method of claim 87, wherein the processing parameter includes a laser output power, a transferring speed of the stage on which the object is placed, a frequency of the laser beam, and a focal position of the laser beam.

89. The method of claim 87, wherein the first-second step performs the laser processing by changing the section of the laser beam to have an oval shape.

90. The method of claim 89, wherein the laser beam is arranged such that the processing direction of the object is matched with the major axis of the oval laser beam.

91. A method of processing an object using a laser, comprising: placing the object on a stage; setting control parameters according to the kinds of objects and the processing purpose; adjusting gradients and positions of first and second mirrors using first and second actuators; driving a reflective mirror; transferring the stage at a preset speed; emitting laser beams from a plurality of laser generating units; splitting each of the laser beams emitted from the plurality of laser generating units into at least two laser beams to be incident onto the first and second mirrors; and irradiating the laser beam input from the first and second mirrors to the reflective mirror onto the object.

92. The method of claim 91, wherein the stage is transferred to a direction opposing to the irradiation direction of the laser beam.

93. The method of claim 91, further comprising: before the irradiating of the laser beam incident onto the reflective mirror onto the object, changing the section of the laser beam to be an oval shape.

94. The method of claim 93, wherein the laser beam is arranged such that the processing direction of the object is matched with the major axis of the oval laser beam.