KR20120058274A - The depth of the modified cutting device through a combination of characteristics - Google Patents

Abstract

PURPOSE: A cutting device through the combination of characteristics of a reformed surface according to depth is provided to maintain high surface precision and maximize machining accuracy by freely regulating the size of a reformed area through pulse width control. CONSTITUTION: A cutting device through the combination of characteristics of a reformed surface according to depth comprises a laser source(100), a plurality of mirrors(200-203), a first condensing lens(400), a dispersion control unit(300), and a second condensing lens(401). The laser source outputs pulse laser. The plurality of mirrors split a laser beam output from the laser source or determine the directivity of the laser beam. The first condensing lens condenses one of the laser beams split through the mirrors to irradiate a work piece(500). The dispersion control unit controls the dispersion of another one of the laser beams. The second condensing lens condenses the laser beam dispersed by the dispersion control unit to irradiate the work piece.

Description

The depth of the modified cutting device through a combination of characteristics}

The present invention relates to a cutting device through a combination of the characteristics of the modified surface according to the depth, more specifically, to cut the substrate that can be effectively cut while maintaining a high processing precision by adjusting the pulse width and focus size of the ultra-short pulse laser Relates to a device.

Conventional methods for cutting and separating brittle substrates are used to cut and separate brittle substrates such as glass, silicon, and ceramics, and include scribing, blade dicing, laser cutting, and stealth dicing. Cutting methods such as (Stealth Dicing) and TLS (Thermal Laser Seperation) are used.

Among them, the scribing and blade dicing methods are mechanical cutting methods, and the stealth dicing and TLS methods are non-contact cutting methods using lasers. Existing mechanical cutting method forms a large amount of chips during processing and leaves residual stress on the workpiece, which causes severe breakage and tearing in the thin film of less than 100 um. Conventional laser-based machining is a process based on heat transfer, which results in a large thermal load resulting in the formation of a heat-affected zone (HAZ), which has limitations such as cracking or dropping strength of the workpiece. The degree of processing varies depending on the degree of absorption, which makes it difficult to cut a multilayer structure made of various materials.

The stealth dicing method and the TLS method cut the substrate by directly forming a strained layer or generating tensile residual stress in the substrate without directly removing the substrate from the surface, thereby reducing generation of debris or particles during the cutting process. However, this is also based on the thermal process heat affected zone is formed and the residual stress remains the same to change the characteristics of the substrate, in the case of TLS has a limitation that requires a separate cleaning of the coolant to cool the heat.

Conventional pulsed lasers thermally excite the workpiece, thereby changing the phase of the material to perform the processing. In contrast, ultrashort pulse lasers (pulse widths less than 10 ps) are based on the high peak power of the ultrashort pulses to directly remove or remove the workpiece into the plasma state or change the state of the material. In addition, the narrow pulse width ensures that all processing is performed before heat is conducted to the surrounding materials, resulting in clean and precise processing without affecting the processing peripherals.

The advantages of the ultra short pulse laser The process starts and proceeds by nonlinear light absorption without depending on the non-defective defect electrons of the workpiece required in conventional laser processing. Therefore, the control of the machining is very easy with a deterministic process that does not depend on the workpiece.

Seed electron groups are sufficiently generated through nonlinear ionization for tens of femtoseconds in front of the ultra-short pulses, and processing starts and progresses. Therefore, the selectivity of the processing site and the repeatability of the process can be greatly increased, which is very advantageous in application to practical applications. In particular, the advantages of ultra-short pulse lasers in the processing of transparent materials include nonlinear light absorption, which allows the processing and changes to be concentrated only on the volume near the focal point, increasing the processing accuracy, and minimizing the stress variation in the surrounding area. can do. Since the nonlinear light absorption phenomenon does not depend on the physical properties of the workpiece, various workpieces can be processed, and in particular, a workpiece composed of a combination of various different materials and layers can be easily processed with a single laser.

The femtosecond laser micromachining principle is based on ultra-short laser-based optical breakdown. Light energy propagates through the material, which causes many electrons to ionize. As a result, energy is transferred to the material's lattice, causing a phase change or structural change in the material. It also produces changes in the refractive index and voids concentrated in the laser focusing zone. With a pulse width of 10 fs or more, nonlinearly excited electrons generate sufficient energy through a linear absorption mechanism through the photons, resulting in an Avalanche ionization process that further excites other bond electrons, resulting in additional processing speed. It brings an improvement.

In the conventional laser transparent material processing, a multi-layer reformed region was formed by changing the focus in the depth direction as a way to increase cutting efficiency. The ultrashort pulses were irradiated on the surface for high surface accuracy, and irradiated in different depth directions with the ultrashort pulses intact. However, it is advantageous to irradiate ultra-short pulses on the surface for the surface accuracy to evaluate the performance of the processed material, but the existing process has a problem of unnecessary energy waste because the internal processing of the processed material does not require a high level of surface accuracy. .

The present invention for solving the above problems, by using the dispersion control to irradiate the ultra-short pulse on the surface of the workpiece that requires a high surface accuracy, and relatively inside the workpiece that requires a relatively low surface accuracy By irradiating a wide pulse having a large processing area, the purpose is to maintain high surface accuracy and to increase productivity.

The present invention for achieving the above object, a laser source for outputting a pulse laser, a plurality of mirrors to separate or determine the direction of the laser output from the laser source, processing by condensing one laser separated from the mirror A first condenser for irradiating an object, a dispersion controller for adjusting the dispersion of another laser separated from the mirror, and a second laser for condensing the laser controlled by the dispersion controller to irradiate the object to be processed Characterized in that it comprises a condenser lens.

The mirror may include: a first mirror for dividing a laser output from the laser source, a second mirror for providing one laser split from the first mirror to the first condenser lens, and a split in the first mirror And a fourth mirror for providing the other laser to the dispersion controller and a fourth mirror for providing the laser output from the dispersion controller to the second condenser lens.

The dispersion controller may output a laser having an ultra short pulse width through dispersion and chirp compensation of the laser output from the laser source.

In addition, the laser beam passing through the dispersion control unit is characterized in that the pulse width is shorter than the laser does not pass.

In addition, the first condensing lens is characterized in that it corresponds to a condensing lens having a focus so that the laser focus on the inside of the object to be processed.

In addition, the second condensing lens is characterized in that it corresponds to a condensing lens having a focus so that the laser focus on the surface of the object to be processed.

In addition, after the laser beam is irradiated to the object to be processed through the cutting device, after the internal removal or the formation of the modified region, the object may be finally cut through thermal, mechanical, ultrasonic stress, and vibration stress.

The object to be processed may be a transparent material or a wafer.

The present invention configured as described above is a method that can combine the advantages of the processing characteristics according to the pulse width to optimize and control the processing and modification region in the transparent material for dicing and cutting, even with a very short laser pulse energy and time By performing the processing effectively, there is an effect of reducing the cost and processing efficiency.

In addition, the present invention has a high processing efficiency in the optical alignment of the multiple focus in the transparent material, and can be optimized for dicing and cutting equipment because it can arbitrarily adjust the size of the modified region through the pulse width control There is.

1 is a schematic configuration diagram of a cutting device through a combination of characteristics of the modified surface according to the depth according to the present invention,
2 is a cross-sectional view showing a reformed region formed by an ultrashort pulse and a reformed region formed by a wide pulse as an embodiment of the dispersion controller according to the present invention;
3 is a view showing that the pulse generated by the ultrashort pulse laser is converted to the ultrashort pulse through the dispersion controller as an example of operation of the dispersion controller according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the cutting device through the combination of the characteristics of the modified surface according to the depth according to the present invention.

Cutting device through the combination of the characteristics of the modified surface according to the depth according to the invention, the laser source 100 for outputting a pulse laser, a plurality of mirrors for separating or directing the laser output from the laser source, in the mirror The first condenser lens 400 for condensing the separated laser to irradiate the object to be processed, the dispersion control unit 300 for adjusting the dispersion of the other laser separated to the mirror and the dispersion control unit And a second condenser lens 401 for condensing the adjusted laser to irradiate the object to be processed.

The cutting device through the combination of characteristics of the modified surface according to the depth according to the present invention is irradiated with ultra-short pulse laser to the surface of the object to be processed to require a high surface accuracy by irradiating a laser having a different pulse width to the object, respectively, In order to provide a cutting device that maintains high surface quality and improves productivity by forming a modified surface by irradiating a laser having a wider pulse width than a pulse laser irradiated to the surface inside a processing object requiring a low surface accuracy. There is a purpose.

1 is a schematic configuration diagram of a cutting device through a combination of characteristics of the modified surface according to the depth according to the present invention. The cutting device according to the present invention focuses and irradiates a laser source 100 and a plurality of mirrors for controlling the direction of the laser, a dispersion control unit 300 for controlling the pulse width, and a laser to the object to be processed 500. It comprises a first condensing lens 400 and the second condensing lens 401 for.

The laser source 100 outputs a laser having a pulse width, and may be provided with a variety of known laser sources. In general, the laser source 100 outputs a laser having a pulse width of less than picoseconds. Use source The laser direction of the cutting device is determined by dividing or changing a path through a plurality of mirrors output from the laser source 100.

First, the laser output from the laser source is divided into two lasers through the first mirror 200 and irradiated. The first mirror may be a beam splitter applied.

One of the lasers split from the first mirror passes through the mirror and is irradiated by the second mirror 201 to the first condensing lens, and the remaining laser split from the first mirror is reflected to reflect the third mirror ( 203) and then reflected again by the third mirror to be irradiated to the fourth mirror 204, and then irradiated to the second condensing lens by the fourth mirror.

As described above, the configuration of the first to fourth mirrors according to the present invention is only one embodiment, and in the configuration of the system, various optical components may be applied in addition to the configuration described in the present invention. In order to irradiate laser beams having different pulse widths to the object to be processed, the surface and the inside of the object are removed or a modified region is formed.

The laser beam passing through the first mirror is reflected by the second mirror and irradiated onto the first condenser lens. The first condenser lens forms a modified region by focusing the object 500 into the object 500, and condenses a laser having a pulse width output from the laser source as it is to be irradiated into the object. Therefore, a lens having a focus is applied so that the focus area is formed inwardly according to the thickness of the object to be processed.

Therefore, the laser having a relatively wide pulse width output from the laser source is focused through the first condensing lens and irradiated to form a modified region inside the object to be processed, such as a transparent material or a wafer, so that the laser can be cut.

Meanwhile, the other laser divided by the first mirror is reflected by the third mirror, and the third mirror reflects the laser back to the dispersion controller. The dispersion controller outputs a laser having an ultra-short pulse width smaller than the pulse width output from the laser source through dispersion control and chirp compensation of the laser output from the laser source. That is, the laser of which the pulse width is adjusted in the dispersion control unit forms a modified region suitable for the processing object that requires a high surface accuracy of the processing object.

The laser, the dispersion and the chirp compensated by the dispersion controller, is irradiated to the second condenser lens 401 by the fourth mirror 204. The second condensing lens is composed of a lens having a focal point near the surface of the object to be condensed so that the laser light can be focused near the surface to form a modified region.

2 is a cross-sectional view showing a reformed region formed by an ultrashort pulse and a modified region formed by a wide pulse according to an embodiment of the dispersion controller according to the present invention. As shown, the ultrashort pulse reforming region 501 is formed near the surface of the object 500 to be processed, and a wide pulse reforming region is formed by a relatively wide pulse width laser output from the race source. 502) is formed.

3 is a view showing that the pulse generated by the ultrashort pulse laser is converted to the ultrashort pulse through the dispersion controller as an example of the operation of the dispersion controller according to the present invention. The laser light output from the laser source has a relatively wide pulse 504 and is irradiated to the inside of the object to form a modified region, and the laser light whose dispersion control and chirp are compensated through the dispersion control unit is more than the laser light. By outputting a short ultra-short pulse laser, there is an advantage in that the substrate can be effectively cut by forming a modified region for high surface accuracy near the substrate surface to be processed.

Therefore, a modified region is formed by using an ultra-short pulse laser near the surface of the object to be processed according to the surface degree using lasers having different pulse widths, and a modified region is formed by irradiating a laser having a relatively wide pulse width inside. The substrate is finally cut through a cutting process.

According to the present invention configured as described above, laser light having a wide pulse width uses laser light having different pulse widths to form a modified region by irradiating inside a substrate where a high level of surface accuracy is not required, and a laser having a short pulse width. Irradiation near the substrate surface forms a modified region, which is very effective in cutting a substrate requiring high surface accuracy and has an advantage of increasing productivity.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. On the contrary, those skilled in the art will appreciate that many modifications and variations of the present invention are possible without departing from the spirit and scope of the appended claims. And all such modifications and changes as fall within the scope of the present invention are therefore to be regarded as being within the scope of the present invention.

100: laser source 200: the first mirror
201: second mirror 203: third mirror
204: fourth mirror 300: dispersion control unit
400: first condenser lens 401: second condenser lens
500: object to be processed 501: ultra-short pulse reforming area
502: wide pulse reforming region 503: ultra short pulse
504: wide pulse

Claims (8)

A laser source for outputting a pulsed laser;
A plurality of mirrors separating or directing the laser output from the laser source;
A first condenser lens for condensing one laser separated from the mirror and irradiating the object to be processed;
A dispersion controller for controlling dispersion of the other laser separated from the mirror; And
And a second condenser lens for condensing the laser controlled by the dispersion control unit and irradiating the object to be processed. 2. The method of claim 1, wherein the mirror,
A first mirror dividing a laser output from the laser source;
A second mirror for providing one laser split from the first mirror to the first condensing lens;
A third mirror for providing another laser divided by the first mirror to a dispersion controller; And
And a fourth mirror for providing the laser output from the dispersion controller to the second condensing lens. The dispersion control unit according to claim 1 or 2,
Cutting device through the combination of the characteristics of the modified surface according to the depth, characterized in that for outputting the laser having a very short pulse width through the dispersion and chirp compensation of the laser output from the laser source. The method of claim 1,
The laser passing through the dispersion control unit is a cutting device through the combination of the characteristics of the modified surface according to the depth, characterized in that the pulse width is shorter than the laser does not pass. The method of claim 1, wherein the first condensing lens,
And a condenser having a focus to focus the laser within the object to be processed. The method of claim 1, wherein the second condensing lens,
And a condensing lens having a focus so as to focus the laser on the surface of the object to be processed. The method of claim 1,
After the laser beam is irradiated to the object to be processed through the cutting device, after the internal removal or the formation of the modified region, the object is finally cut through thermal, mechanical, ultrasonic stress, and vibration stress. Cutting device by combination of characteristics. The said object to be processed according to any one of claims 1 to 7,
Cutting device through the combination of properties of the modified surface according to the depth, characterized in that the transparent material or wafer.

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