WO2013151350A1

WO2013151350A1 - Apparatus and method of manufacturing micro-notches at the edge line portion of scribing wheel using ultrafast laser

Info

Publication number: WO2013151350A1
Application number: PCT/KR2013/002808
Authority: WO
Inventors: Sae Chae Jeoung; Heung Soon Lee; Hyun Kyu Lee; Soo Kwang Kim
Original assignee: Korea Research Institute Of Standards And Science; Ehwa Diamond Ind. Co., Ltd.
Priority date: 2012-04-05
Filing date: 2013-04-04
Publication date: 2013-10-10
Also published as: JP6043421B2; CN104203485A; KR20130113289A; JP2015514018A; KR101334067B1; CN104203485B

Abstract

An object of the present invention is to provide an apparatus and a method of manufacturing a scribing wheel, which is a tool used to cut a brittle material, including a plurality of micro-notches formed at a edge line portion thereof, and an apparatus and a method of manufacturing micro-notches at a edge line portion of a scribing wheel using an ultrafast laser, capable of implementing a non-contact type process by forming the micro-notches using the ultrafast laser.

Description

APPARATUS AND METHOD OF MANUFACTURING MICRO-NOTCHES AT THE EDGE LINE PORTION OF SCRIBING WHEEL USING ULTRAFAST LASER

The present invention relates to an apparatus and a method of manufacturing micro-notches at a edge line portion of a scribing wheel using an ultrafast laser. More particularly, the present invention relates to an apparatus and a method of manufacturing micro-notches at a edge line portion of a scribing wheel made of a diamond or a hard metal using an ultrafast laser, capable of allowing a vertical crack for scribing to be better generated by more efficiently forming a scratch on a surface of a brittle material with respect to a scribing wheel, which is a tool forming the scratch on the brittle material in order to cut the brittle material.

The demand for a panel type device including a liquid crystal display (LCD), a thin film transistor LCD (TFT-LCD), an organic light emitting diode (OLED) based flat panel display (FPD), a touch panel, or the like, has increased. Therefore, in order to increase productivity, a size of the device has increased and a thickness of the device has decreased at the time of producing the panel itself. Therefore, in order to produce an end-product using the device, a process of cutting a previously produced large flat panel according to a purpose is necessary. Furthermore, generally, a semiconductor producing process necessarily includes a process of forming an integrated circuit on a wafer and then separating the wafer into the respective dies by a scribe process.

The scribe process indicates a process of forming a scribing line on a plate shaped object such as a device substrate, a wafer, or the like, and applying force to both sides based on the scribing line to break the plate shaped object along the scribing line, thereby performing the cutting. Generally, the wafer is made of a brittle material such as glass, or the like. Since the brittle material has a property in which a crack is very rapidly propagated well when external force is applied to the brittle material, the scribe process is very usefully used in cutting the brittle material. Particularly, in the case of the brittle material, it is much easier to form only a small crack in an object and then cut the object using the scribing, as compared with to cut the entire object using a cutting tool. The scribing apparatus or method as described above has been disclosed in detail in Korean Patent Laid-Open Publication No. 2011-0079977 entitled "Scribing Apparatus and Method Including Chip Pre-Processor" and filed on July 12, 2011, Japanese Patent Laid-Open Publication No. 2010-194784 entitled "Scribe Apparatus and Method" and filed on September 9, 2010, Korean Patent Laid-Open Publication No. 2010-0056216 entitled "Scribing Apparatus and Scribing Method Using the Same" and filed on May 27, 2010, and the like.

However, in the case of using the scribe process as described above, since the object is not completely cut using a cutting tool, it may be difficult to control a cutting direction at will. Therefore, there is the possibility that a defect will occur in the scribe process. Since the cutting direction at the time of the scribing ultimately becomes a propagation direction of the crack, it is possible to solve this problem to some degree by allowing the crack to be accurately formed in a vertical direction. Therefore, studies on several technologies for more accurately and efficiently forming a scribing line on an object made of a brittle material have been conducted.

Currently, a method of forming a scribing line on an object using a scribing wheel having strength higher than that of the object has been generally used. As disclosed in International Patent Publication No. WO09/099130 entitled "Polycrystalline Diamond" and filed on August 13, 2009 describing that a diamond polycrystalline material may be used to manufacture a scribing wheel, the scribing wheel is generally made of a material such as the polycrystalline diamond, a hard metal, or the like.

Various studies on a shape or a manufacturing method of the scribing wheel itself have been conducted in order to better form a scribing line. As a technology regarding improvement of a shape or a manufacturing method of a scribing wheel, Korean Patent Laid-Open Publication No. 2011-0129050 entitled "Scribing Wheel and Manufacturing Method Thereof" and filed on December 1, 2011, US Patent No. 7975589 entitled "Scribing Wheel for Brittle Material and Manufacturing Method for Same, as well as Scribing Method, Scribing Apparatus and Scribing Tool Using the Same" and filed on July 12, 2011, and the like, have been disclosed. Briefly describing this, a disk-like scribing wheel includes a plurality of micro-notches formed at a edge line portion, such that the scribing wheel has a shape such as a circular saw blade shape. Since sizes, shapes, and the like, of the micro-notches have a direct effect on quality of the scribing, a study has been conducted based on this point in the above-mentioned Related Art Documents, or the like.

Although various studies on how to form the shape of the scribing wheel have been disclosed as described above, a method itself of forming the micro-notches in the scribing wheel has hardly been disclosed. That is, only a contact type method such as grinding work (using a tool made of a material stronger than a material of the scribing wheel), or the like, has been disclosed. However, as described above, since the scribing wheel is made of a material having very high strength, such as the polycrystalline diamond, the hard metal, or the like, it is likely that a problem such as rapid consumption of a tool, or the like, even though the tool made of a material stronger than the material of the scribing wheel is used will occur. In addition, since this contact type process generates thermal damage, it is also difficult to accurately and uniformly form micro-notches having a desired form. Furthermore, it is hardly to reduce the size of the micro-notches less than 5 micrometers.

In addition, a process of forming micro-notches using a high energy charged particle such as a focused ion beam (FIB) has been introduced. However, in this case, high vacuum facility is necessary as a manufacturing process environment, which may cause problems such as an increase in a process cost, complication of a process, and the like.

In addition, several processes according to the related art as described above have a technical limitation in that notches may not be simultaneously formed at edge line portions of a plurality of wheels due to characteristics thereof.

[Related Art Document]

[Patent Document]

1. Korean Patent Laid-Open Publication No. 2011-0079977 entitled "Scribing Apparatus and Method Including Chip Pre-processor" and filed on July 12, 2011

2. Japanese Patent Laid-Open Publication No. 2010-194784 entitled "Scribe Apparatus and Method" and filed on September 9, 2010

3. Korean Patent Laid-Open Publication No. 2010-0056216 entitled "Scribing Apparatus and Scribing Method Using the Same" and filed on May 27, 2010

4. International Patent Publication No. WO09/099130 entitled "Polycrystalline Diamond" and filed on August 13, 2009

5. Korean Patent Laid-Open Publication No. 2011-0129050 entitled "Scribing Wheel and Manufacturing Method Thereof" and filed on December 1, 2011

6. US Patent No. 7975589 entitled "Scribing Wheel for Brittle Material and Manufacturing Method for Same, as well as Scribing Method, Scribing Apparatus and Scribing Tool Using the Same" and filed on July 12, 2011

In one general aspect, an apparatus 1000 of manufacturing a plurality of micro-notches 520 at a front end portion 510 of a wheel 500 using an ultrafast laser, includes: a laser irradiating part 100 irradiating the ultrafast laser; and a wheel moving part 200 moving the wheel 500 horizontally or vertically or rotating the wheel 500 so that the front end portion 510 of the wheel 500 is disposed on a light path of a laser beam irradiated by the laser irradiating part 100, wherein the micro-notches 520 are formed at the front end portion 510 of the wheel 500 by the laser beam irradiated by the laser irradiating part 100.

The laser irradiating part 100 may include: a laser light source 110; an objective lens 120 focusing the laser beam irradiated by the laser light source 110 on the front end portion 510 of the wheel 500; a dichroic mirror 130 disposed on a light path between the laser light source 110 and the objective lens 120, totally reflecting light of a wavelength range of the laser beam irradiated by the laser light source 110 thereon, and penetrating light of other wavelength ranges therethrough; and a photographing part 140 photographing the front end portion 510 of the wheel 500 using the light penetrating through the dichroic mirror 130. The laser irradiating part 100 may irradiate laser light having a pulse width of a femto second or a pico second.

The wheel moving part 200 may include: a stage 210; a shaft 220 fitted into a central hole 530 of the wheel 500; a step motor 230 disposed on the stage 210, provided at one distal end of the shaft 220, and rotating the shaft 220 to rotate the wheel 500; and a translator 240 coupled to the stage 210, provided at the other distal end of the shaft 220, and moving the wheel 500 horizontally or vertically.

The wheel moving part 200 may further include a coupler 250 provided at a connection part between the step motor 230 and the shaft 220 to remove transfer of noise movement including precession of an axis of the step motor 230. The wheel moving part 200 may further include at least one supporter 260 disposed on the stage 210, supporting the shaft 220 while having the shaft 220 penetrating therethrough, and including a bearing 265 formed at a portion at which the shaft 220 penetrates therethrough and is supported thereby.

The wheel moving part 200 may move the wheel 500 horizontally so that an extension line of the light path of the laser beam irradiated by the laser irradiating part 100 and a tangential line at a point at which the laser beam is irradiated to the wheel 500 form an acute angle or a right angle The wheel moving part 200 may move the wheel 500 vertically using an image photographed by the photographing part 140 or a height value measured by a separately provided height measuring sensor 270.

The micro-notches 520 may be formed at a stack formed by stacking a plurality of wheels 500 on the same axis. The apparatus may further include a wheel cartridge 300 including the stack formed by stacking the plurality of wheels 500 on the same axis, a pair of support plates 310 provided at both distal ends of the stack, and a filling material 320 filled between the wheels 500, wherein the micro-notches 520 are formed at the wheel cartridge 300. The filling material 320 may be a material soluble in a solvent that does not physically and chemically damage the wheel 500.

In another general aspect, a method of manufacturing a plurality of micro-notches 520 at a front end portion 510 of a wheel 500 using an ultrafast laser, includes: a laser irradiating step of irradiating a laser to the front end portion 510 of the wheel 500 to form the micro-notches 520; a wheel rotating step of rotating the wheel 500 by a predetermined angle; and a step of sequentially and repeatedly performing the laser irradiating step and the wheel rotating step. The laser may have a pulse width of a femto second or a pico second.

The laser irradiating step may be performed by a process in which the laser is irradiated at least once while being relatively moved in an axial direction of the wheel 500. A width of the micro-notch 520, a depth of the micro-notch 520, energy of the laser, a pulse repetition rate of the laser, a relative movement speed of the laser, and the number of irradiation repetition of the laser may be determined according to the wheel 500.

The micro-notches 520 may be formed at a stack formed by stacking a plurality of wheels 500 on the same axis.

According to the exemplary embodiment of the present invention, since the micro-notches are formed at the edge line portion of the wheel by a non-contact type process using an ultrafast laser in manufacturing the scribing wheel, the micro-notches may be more accurately and easily formed as compared with the case in which the micro-notches are formed by a contact type process using grinding work according to the related art.

In addition, according to the exemplary embodiment of the present invention, when manufacturing the micro-notches at the scribing wheels, since a process of forming the micro-notches is performed on a plurality of scribing wheels collected in a cartridge form at a time rather than on each of the individual scribing wheels, productivity may be significantly improved as compared with the related art. Further, when manufacturing the wheel cartridge, the filling material such as a polymer is coated or filled between the front ends of the wheels, thereby making it possible to prevent partial ablation for a portion other than the edge line portions of the wheels that may occur in the laser process. Alternatively, a degree of coating is changed to control a degree of ablation, thereby making it possible to artificially control a three-dimensional structure of the manufactured notch.

Furthermore, since the method of manufacturing a scribing wheel according to the exemplary embodiment of the present invention is performed by a non-contact type process using the ultrafast laser as described above, a restriction on a process environment is not present unlike the related art in which a special environment such as a vacuum environment is required, such that a process may be further easily and economically implemented.

The above and other objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram of a hard metal or polycrystalline diamond (PCD) wheel having micro-notches uniformly formed at a edge line portion thereof.

FIG. 2 is a schematic diagram of an ultrafast laser process apparatus of manufacturing micro-notches at a edge line portion of a hard metal or polycrystalline diamond wheel according to an exemplary embodiment of the present invention.

FIG. 3 is a diagram of an apparatus of manufacturing micro-notches at a edge line portion of a hard metal or polycrystalline diamond wheel.

FIG. 4 is a typical diagram of a wheel cartridge according to an exemplary embodiment of the present invention.

FIGS. 5A to 5C are diagrams showing a principle of an angle control method from a central axis of a notch according to an exemplary embodiment of the present invention.

[Detailed Description of Main Elements]

1000: Apparatus of manufacturing micro-notches according to an exemplary embodiment of the present invention

100: Laser irradiating part

110: Laser light source

120: Objective lens

130: Dichroic mirror

140: Photographing part

200: Wheel moving part

210: Stage

220: Shaft

230: Step motor

240: Translator

250: Coupler

260: Support

265: Bearing

270: Height measuring sensor

300: Wheel cartridge

310: Support plate

320: Filling material

500: Wheel

510: edge line portion

520: Notch

530: Central hole

Hereinafter, an apparatus and a method of manufacturing micro-notches at a edge line portion of a scribing wheel using an ultrafast laser according to an exemplary embodiment of the present invention having the configuration as described above will be described in detail with reference to the accompanying drawings.

As described above, in order to cut a substrate in a flat-panel display or semiconductor manufacturing process, a process of forming a scribing line on the substrate and then cutting the substrate in a fracture scheme is used. It is well known that it is important to form the scribing line well in order to lower a defect generation rate in the cutting process. In addition, to this end, studies on how to manufacture a scribing wheel well in order to form the scribing line well have been conducted in several viewpoints.

FIG. 1 is a diagram of a scribing wheel to be manufactured through the present invention. As shown in FIG. 1, the scribing wheel 500 has a form in which micro-notches 520 are radially and uniformly formed at a edge line portion 510 of the scribing wheel 500. As described above, as a material of the scribing wheel, a material having very high strength such as a hard metal or a polycrystalline diamond (PCD) is generally used. More specifically, the edge line portion 510 of the wheel 500 has a shape in which blades stand at a predetermined angle in both directions, and the center of the wheel 500 is provided with a central hole 530 having high precision and a predetermined diameter. The central hole 530 is formed in order for a process shaft to be inserted thereinto and used when intending to form a scratch (that is, a scribing line) on a surface of a brittle material using the wheel 500. In this case, a width of the notch 520 may be changed in a range of about 1 to 20 micron and a depth thereof may be changed in a range of about 0.3 to 10 micron, according to a use purpose. In addition, the number of notches 520 to be manufactured at the edge line portion 510 of the wheel 500 may be variously changed in a range of about 1 to 3,600 according to a use material and purpose.

FIG. 2 shows a schematic diagram of an ultrafast laser process apparatus of manufacturing micro-notches at a edge line portion of a scribing wheel according to an exemplary embodiment of the present invention; and FIG. 3 shows a diagram of an apparatus according to an exemplary embodiment of the present invention.

The apparatus 1000 of manufacturing micro-notches according to the exemplary embodiment of the present invention is basically configured to include two components, that is, a laser irradiating part 100 and a wheel moving part 200. As described above, the apparatus 1000 of manufacturing micro-notches according to the exemplary embodiment of the present invention implements a non-thermal process of minimizing thermal damage by using an ultrafast laser as well as a non-contact type process using a laser, unlike a contact type process used at the time of manufacturing a scribing wheel according to the related art and accompanied with thermal damage, such as grinding work, or the like. Briefly describing this, in the exemplary embodiment of the present invention, the laser irradiating part 100 irradiates an ultrafast laser, and the wheel moving part 200 is formed to move the wheel 500 horizontally or vertically or rotate the wheel 500 so that the edge line portion 510 of the wheel 500 is disposed on a light path of a laser beam irradiated by the laser irradiating part 100, thereby allowing the notches 520 to be formed at the edge line portion 510 of the wheel 500 by the laser beam irradiated by the laser irradiating part 100. Hereinafter, each component will be described in more detail.

The laser irradiating part 100 may be configured to include a laser light source 110, an objective lens 120, a dichroic mirror 130, and a photographing part 140, as shown in FIG. 3.

The laser light source 110 is preferably an ultrafast laser minimizing thermal damage in order to implement the non-contact type process and the non-thermal process as described above. More specifically, the laser irradiating part 100 preferably irradiates laser light having a pulse width of a femto second or a pico second.

The objective lens 120 serves to focus the laser beam irradiated by the laser light source 110 on the edge line portion 510 of the wheel 500. As an optical apparatus serving to focus the light as described above, an optical apparatus having various forms such as a form in which it is formed of a single lens, a form in which it is formed of a plurality of lenses, a form in which it further includes separate other optical components in addition to a lens, and the like, has been disclosed. That is, as a configuration of the objective lens 120 according to the exemplary embodiment of the present invention, a configuration appropriate for laser processing among configurations corresponding to the objective lens well-known as described above may be used. Therefore, a description for a detailed configuration of the objective lens 120 will be omitted.

The dichroic mirror 130 is disposed on a light path between the laser light source 110 and the objective lens 120 and serves to totally reflect light of a wavelength range of the laser beam irradiated by the laser light source 110 thereon and penetrate light of other wavelength ranges therethrough. Meanwhile, as an optical component serving to totally reflect light of a specific wavelength range thereon and penetrates light of other wavelength ranges therethrough as described above, there is also a beam splitter, or the like. That is, as an apparatus serving as the dichroic mirror 130, any other optical component capable of performing the function as described above may be used (even though it is not clearly the dichroic mirror).

The photographing part 140 serves to photograph the edge line portion 510 of the wheel 500 using the light penetrating through the dichroic mirror 130. More specifically, as a component performing the above-mentioned function, a charge coupled device (CCD) camera, or the like, is widely used. Therefore, the photographing part 140 may be formed of the CCD camera, or the like.

The wheel moving part 200 may be configured to include a stage 210, a shaft 220, a step motor 230, and a translator 240, as shown in FIG. 3.

The stage 210, which is literally a worktable, forms a space on which the wheel 500 is put and a notch manufacturing process may be performed. The stage 210 may be formed to be movable in a horizontal direction, that is, a direction denoted by an XY direction in FIG. 2 or FIG. 3.

The shaft 220 is fitted into the central hole 530 of the wheel 500 and includes the step motor 230 and the translator 240 coupled to both distal ends thereof, which will be described below in more detail. The shaft 220 is translated horizontally or vertically or is rotated in a state in which it is fitted into the wheel 500, thereby making it possible to adjust a position at which the laser is irradiated. Therefore, the notch 520 having a desired size may be formed at a desired portion of the edge line portion 510 of the wheel 500 by the laser processing. Devices moving the shaft 220 horizontally or vertically or rotating the shaft 220 are a step motor 230 and a translator 240 to be described below. A detailed description of each of the step motor and the translator will be provided below.

The step motor 230 serves to rotate the wheel 500. That is, the step motor 230 is disposed on the stage 210, is provided at one distal end of the shaft 220, and serves to rotate the shaft 220 to rotate the wheel 500. Here, it is preferable that the wheel moving part 200 further includes a coupler 250 provided at a connection part between the step motor 230 and the shaft 220 so as to remove transfer of noise movement including precession of an axis of the step motor 230. In addition, it is preferable that the wheel moving part 200 further includes at least one supporter 260 disposed on the stage 210, supporting the shaft 220 while having the shaft 220 penetrating therethrough, and including a bearing 265 formed at a portion at which the shaft 220 penetrates therethrough and is supported thereby, so as to ensure precision at the time of rotation of the shaft 220 and stably support the shaft 220.

The translator 240 serves to move the wheel 500 in a horizontal direction (that is, an XY direction in FIG. 2 or FIG 3) or a vertical direction (that is, a Z direction in FIG. 2 or FIG. 3). That is, the translator 240 is coupled to the stage 210, is provided at the other distal end of the shaft 220, and serves to move the wheel 500 horizontally or vertically. The translator 240 is used when arranging the wheel 500 at a desired position before a process starts and may be used in order to adjust the position during the process. Particularly, the translator 240 may also be used to adjust a height of the wheel 500 in the vertical direction in order to adjust a depth of the notch 520 formed at the time of irradiating the laser. In order to perform this precise adjustment, it is preferable that the wheel moving part 200 is formed to move the wheel 500 vertically using an image photographed by the photographing part 140 or a height value measured by a separately provided height measuring sensor 270.

Here, particularly, a feature of the present invention is to manufacture the notches 520 with respect to a plurality of wheels 500 at a time, rather than to perform a process of manufacturing the notches 520 with respect to the wheels 500 one by one. That is, the apparatus 1000 of manufacturing micro-notches is configured to form the notches 520 at a stack formed by stacking the plurality of wheels 500 on the same axis. In the exemplary embodiment of the present invention, a structure of a wheel cartridge 300 is introduced in order to stably fix the plurality of wheels 500. A detailed description thereof will be provided below.

FIG. 4 shows a typical diagram of a wheel cartridge according to an exemplary embodiment of the present invention. The wheel cartridge 300 may be configured to include a stack formed by stacking the plurality of wheels 500 on the same axis, a pair of support plates 310 provided at both distal ends of the stack, and a filling material 320 filled between the wheels 500. The wheel cartridge 300 may include only one wheel 500 or several tens to several hundreds of wheels. The notches 520 are formed at a time using the laser irradiating part 100 in a state in which the plurality of wheels 500 are stacked as described above, thereby making it possible to significantly improve productivity, as compared with the case in which the notches are formed at each of the individual wheels.

The support plate 310 may have any shape as long as it may allow an interval between the wheels 500 not to become wide and maintain a stack form well and be made of any material such as glass, or the like. The filling material 320 may be filled between the wheels 500 and be a material (for example, a polymer material, or the like) soluble in a solvent (for example, water, or the like) that does not physically and chemically damage the wheel 500. The filling material 320 serves to improve adhesion capability between the wheels 500 and between the wheel 500 and the support plate 310 and prevent damage to a surface of the wheel other than a required process surface that may also occur due to a laser generating plum, or the like, at the time of manufacturing the notches using the ultrafast laser. Here, the filing material 320 made of a polymer material, or the like, is formed on the edge line portion 510 of the wheel 500 to have a thickness of several tens of nanometers or less, thereby allowing process precision not to be affected by the thickness of the filling material 320 at the time of manufacturing the notches using the ultrafast laser.

The filling material 320 such as the polymer is coated or filled between the front ends of the wheels 500, thereby making it possible to prevent partial ablation for a portion other than the edge line portions of the wheels 500 that may occur in the laser process. Alternatively, a degree of coating is changed to control a degree of ablation, thereby making it possible to artificially control a three-dimensional structure of the manufactured notch 520.

A method of manufacturing micro-notches using the apparatus 1000 of manufacturing micro-notches configured as described above will be schematically described below. The method of manufacturing micro-notches according to the exemplary embodiment of the present invention, which is a method of manufacturing a plurality of micro-notches 520 at the edge line portion 510 of the wheel 500, is configured to include a laser irradiating step of irradiating a laser to the edge line portion 510 of the wheel 500 to form the notches 520; a wheel rotating step of rotating the wheel 500 by a predetermined angle; and a step of sequentially and repeatedly performing the laser irradiating step and the wheel rotating step.

Here, the laser irradiating step is performed by a process in which the laser is irradiated at least once while being relatively moved in an axial direction of the wheel 500. That is, the laser irradiating part 100 may be directly moved in the axial direction of the wheel 500 or the wheel 500 may be directly moved using the wheel moving part 200 in a state in which the laser irradiating part 100 is fixed. As described above, in the case of forming the notch 520 at the stack formed by stacking the plurality of wheels 500 on the same axis (in the case of using the wheel cartridge 300), the laser irradiating part 100 may form the notches 520 while lengthily reciprocating in the axial direction.

That is, the entire driving will be described below comprehensively. First, as shown in FIGS. 2 and 3, the wheel 500 is disposed to be vertical to a horizontal surface (that is, an XY surface), and a surface direction of the wheel 500 is disposed to be vertical to a driving axis direction of a process operation. In this case, it is preferable that an axial direction of the wheel 500 is disposed in parallel with any one of an X axis and a Y axis. (This is also applied in the case of using the wheel cartridge 300.) The above-mentioned arrangement and disposition work may be manually performed or be automatically performed using an image acquired by the photographing part 240.

After the wheel 500 (or the wheel cartridge 300) is arranged and disposed on the worktable, that is, the stage 210, a height of the objective lens 120 is adjusted or a height of the wheel 500 is adjusted using the translator 240 to allow the laser beam irradiated by the laser irradiating part 100 to be focused on the edge line portion 510 of the wheel 500. The above-mentioned focus arrangement work may be performed using the image acquired by the photographing part 240 or be performed using a height value measured using the height measuring sensor 270 separately provided in the wheel moving part 200 as described above.

After the work of arranging and disposing the wheel 500 (or the wheel cartridge 300) on a three-dimensional (XYZ) space is completed, the ultrafast laser irradiated by the laser irradiating part 100 is irradiated to be focused on the front end portion 510 of the wheel 500, such that the notches 520 are manufactured. Here, a width of the notch 520, a depth of the notch 520, energy of the laser, a pulse repetition rate of the laser, a relative movement speed of the laser, and the number of irradiation repetition of the laser may be determined according to the wheel 500. A specific example will be descried below.

An ablation depth d and width w per an ultrafast laser pulse in a specific material have the following Equation with respect to a laser fluence (F, J/cm²).

d = a^-1 x ln(F/F₀)

w² = 2 x w₀ ² x ln(F/F₀)

a indicates an extinction coefficient of a material in a used laser wavelength, and a^-1 means a depth at which the laser beam may optically penetrate into the material. (See JOSK Vol. 7 2003, PP150-155, Transition of femtosecond laser ablation mechanism for sodalime glass caused by photoinduced defects) Here, a laser energy fluence corresponds to a region in which thermal damage does not occur in the material, and F₀ is an ablation threshold fluence, which is a minimum fluence at which ablation starts. In addition, w₀, which indicates a beam size in the case of focusing a laser beam having a wavelength of 1 through an objective lens having a predetermined numeral aperture (NA), is determined according to Equation: 2l/NA.

Meanwhile, when the pulse repetition rate increases, a time interval (t) between pulses decreases. The meaning that a time constant (t) for a thermal diffusion speed of the material is longer than the interval (t) between the pulses is that thermal energy is continuously accumulated by the next pulse before thermal energy increased by an initial pulse is completely diffused. Therefore, when the number of average pulses of the laser per unit area of the edge line portion of a process target wheel increases, the heat is continuously accumulated, such that a temperature increases and rapidly decreases at a portion at which the laser pulse ends. (See Korean Patent Laid-Open Publication No. 2012-0022169 entitled "Wafer Processing and Apparatus Thereof" and filed on March 12, 2012 by Jeoung Sae Chae, etc.) In order to overcome an increase in mechanical stress of a target material and a decrease in strength thereof due to the above-mentioned problem, the number (N_p) of average irradiation pulses of the laser should be 1 or less. Meanwhile, the number (N_p) of average irradiation pulses of the laser is determined by a given laser pulse repetition rate PRR (Hz), a movement speed v (stage speed, m/sec) of a process axis, and a laser beam size w₀.

N_p = PRR x w₀/v

In the case in which the laser pulse repetition rate PRR and the laser beam size w₀ used in the above-mentioned exemplary embodiment are 100 kHz and 3 μm, respectively, when it is assumed that a minimum movement speed (stage speed) v of the stage is 0.3m/sec, the number of average irradiation pulses becomes 1.

Meanwhile, in the case in which an ablation depth per a pulse is 75 nm in a predetermined laser fluence, a process is repeated a total of thirty times, thereby making it possible to form a notch having a depth of 1.5 micron at the edge line portion of the wheel.

As a result, one notch 520 may be manufactured at the edge line portion 510 of the wheel 500 through the above-mentioned process. When the notch 520 is manufactured as described above, after the wheel 500 is rotated by a predetermined angle, the above-mentioned process is again repeated. A plurality of notches 520 radially disposed on the wheel 500 may be finally formed through the above-mentioned process.

Meanwhile, a total time required for the above-mentioned process will be described below. That is, a total time required for operating the stage may be calculated from a uniform velocity (v) section from a state in which the stage stops, that is, an acceleration section for entering a processing process section, a process uniform velocity section, a time at which the stage stops from the uniform velocity section, and a section in which the step motor is driven to rotate the wheel cartridge. Here, a main process required time is an acceleration and deceleration section. It is very important in improving productivity to minimize an average required time per one wheel. Meanwhile, as described above, in order to maintain the strength of the material, maintain the manufacturing of the high quality notch, and maximize productivity, it is judged that a method of minimizing the average required acceleration and deceleration section is the best. In the exemplary embodiment of the present invention, as described above, the structure of the wheel cartridge 300 is introduced, such that the notches 520 may be manufactured at several tens of wheels 500 at a time rather than being manufactured at each of the individual wheels 500, thereby making it possible to maximize a productivity improvement effect.

FIGS. 5A to 5C show a principle of an angle control method from a central axis of a notch according to an exemplary embodiment of the present invention. In the exemplary embodiment of the present invention, the wheel moving part 200 is formed to move the wheel 500 horizontally so that an extension line of the light path of the laser beam irradiated by the laser irradiating part 100 and a tangential line at a point (hereinafter, referred to as an 'irradiated point') at which the laser beam is irradiated to the wheel 500 form an acute angle or a right angle. This will be described in detail with reference to FIGS. 5A to 5C.

FIG. 5A shows the case in which the extension line of the light path of the laser beam and the tangential line at the irradiated point are formed to be vertical to each other. In this case, an angle at which the notch 520 is manufactured becomes vertical to a tangential line direction of the edge line portion 510 at the irradiated position. FIG. 5 B shows the case in which the wheel 500 is disposed to be moved horizontally so that an axis of the wheel 500 and the light path of the laser beam deviate from each other. In this case, the extension line of the light path of the laser beam and the tangential line at the irradiated point form an acute angle (about 45 degrees in FIG. 5B). In this case, the notch 520 is also formed in a shape in which it is tilted by an angle of about 45 degrees. FIG. 5C shows the case in which the wheel 500 is disposed so that the axis of the wheel 500 and the light path of the laser beam further deviate from each other as compared with the case of FIG. 5B. In this case, the extension line of the light path of the laser beam and the tangential line at the irradiated point form substantially a zero degree. As described above, a horizontal position of the wheel 500 is appropriately adjusted with respect to the extension line, thereby making it possible to freely manufacture the notch 520 having a desired angle and form.

The present invention is not limited to the above-mentioned exemplary embodiments but may be variously applied, and may be variously modified by those skilled in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims.

According to the exemplary embodiment of the present invention, productivity may be significantly improved as compared with the related art and a restriction on a process environment is not present, such that a process may be further easily and economically implemented.

Claims

An apparatus 1000 of manufacturing a plurality of micro-notches 520 at a edge line portion 510 of a wheel 500 using an ultrafast laser, comprising:

a laser irradiating part 100 irradiating the ultrafast laser; and

a wheel moving part 200 moving the wheel 500 horizontally or vertically or rotating the wheel 500 so that the edge line portion 510 of the wheel 500 is disposed on a light path of a laser beam irradiated by the laser irradiating part 100,

wherein the micro-notches 520 are formed at the edge line portion 510 of the wheel 500 by the laser beam irradiated by the laser irradiating part 100.
The apparatus of claim 1, wherein the laser irradiating part 100 includes:

a laser light source 110;

an objective lens 120 focusing the laser beam irradiated by the laser light source 110 on the edge line portion 510 of the wheel 500;

a dichroic mirror 130 disposed on a light path between the laser light source 110 and the objective lens 120, totally reflecting light of a wavelength range of the laser beam irradiated by the laser light source 110 thereon, and penetrating light of other wavelength ranges therethrough; and

a photographing part 140 photographing the edge line portion 510 of the wheel 500 using the light penetrating through the dichroic mirror 130.
The apparatus of claim 1, wherein the laser irradiating part 100 irradiates laser light having a pulse width of a femto second or a pico second.
The apparatus of claim 1, wherein the wheel moving part 200 includes:

a stage 210;

a shaft 220 fitted into a central hole 530 of the wheel 500;

a step motor 230 disposed on the stage 210, provided at one distal end of the shaft 220, and rotating the shaft 220 to rotate the wheel 500; and

a translator 240 coupled to the stage 210, provided at the other distal end of the shaft 220, and moving the wheel 500 horizontally or vertically.
The apparatus of claim 4, wherein the wheel moving part 200 further includes a coupler 250 provided at a connection part between the step motor 230 and the shaft 220 to remove transfer of noise movement including precession of an axis of the step motor 230.
The apparatus of claim 4, wherein the wheel moving part 200 further includes at least one supporter 260 disposed on the stage 210, supporting the shaft 220 while having the shaft 220 penetrating therethrough, and including a bearing 265 formed at a portion at which the shaft 220 penetrates therethrough and is supported thereby.
The apparatus of claim 4, wherein the wheel moving part 200 moves the wheel 500 horizontally so that an extension line of the light path of the laser beam irradiated by the laser irradiating part 100 and a tangential line at a point at which the laser beam is irradiated to the wheel 500 form an acute angle or a right angle.
The apparatus of claim 2, wherein the wheel moving part 200 moves the wheel 500 vertically using an image photographed by the photographing part 140 or a height value measured by a separately provided height measuring sensor 270.
The apparatus of claim 1, wherein the micro-notches 520 are formed at a stack formed by stacking a plurality of wheels 500 on the same axis.
The apparatus of claim 9, further comprising a wheel cartridge 300 including the stack formed by stacking the plurality of wheels 500 on the same axis, a pair of support plates 310 provided at both distal ends of the stack, and a filling material 320 filled between the wheels 500,

wherein the micro-notches 520 are formed at the wheel cartridge 300.
The apparatus of claim 10, wherein the filling material 320 is a material soluble in a solvent that does not physically and chemically damage the wheel 500.
A method of manufacturing a plurality of micro-notches 520 at a edge line portion 510 of a wheel 500 using an ultrafast laser, comprising:

a laser irradiating step of irradiating a laser to the edge line portion 510 of the wheel 500 to form the micro-notches 520;

a wheel rotating step of rotating the wheel 500 by a predetermined angle; and

a step of sequentially and repeatedly performing the laser irradiating step and the wheel rotating step.
The method of claim 12, wherein the laser has a pulse width of a femto second or a pico second.
The method of claim 12, wherein the laser irradiating step is performed by a process in which the laser is irradiated at least once while being relatively moved in an axial direction of the wheel 500.
The method of claim 14, wherein a width of the micro-notch 520, a depth of the micro-notch 520, energy of the laser, a pulse repetition rate of the laser, a relative movement speed of the laser, and the number of irradiation repetition of the laser are determined according to the wheel 500.
The method of claim 12, wherein the micro-notches 520 are formed at a stack formed by stacking a plurality of wheels 500 on the same axis.