JP6260168B2 - Method and apparatus for processing brittle material substrate - Google Patents

Description

  The present invention relates to a technique for dividing a brittle material substrate such as a glass substrate, and more particularly to a technique for forming a starting point of division by irradiation with pulsed laser light.

  In dividing a brittle material substrate such as a glass substrate, a technique for forming a starting portion by irradiation with pulsed laser light is already known (see, for example, Patent Document 1 and Patent Document 2).

  In Patent Document 1, by causing ablation due to light energy absorption in an irradiated region (local part) of each pulsed laser beam light, by evaporating and scattering a substance present in the region, A technique is disclosed in which a dissolution mark including a group of micro cracks formed in the peripheral portion is formed, and the substrate is divided along a perforated separation facilitating region in which the dissolution marks are arranged.

  In Patent Document 2, a problem has been pointed out that in the case of the technique disclosed in Patent Document 1 (presented as Patent Document 1 in this document as well), the end face strength of the individual pieces after division is reduced. In addition, the laser beam is continuously irradiated to the brittle material substrate while scanning with the pulse laser beam (in a mode in which the individual pulse beams overlap), and ablation occurs due to light energy absorption in the irradiated region of the pulse laser beam. In this way, the material present in the region is evaporated and scattered, and in the region adjacent to the region where the ablation occurs, the brittle material substrate is locally melted and re-solidified, thereby providing a continuous scribe that becomes the starting point of the division. There is disclosed a technique capable of increasing the end face strength of an individual piece after dividing while forming a groove.

JP 2005-271563 A JP 2010-274328 A

  The technique disclosed in Patent Document 2 certainly has a certain effect in improving the end face strength of the divided piece, but the bottom of the formed scribe groove is a curved surface having a relatively large radius of curvature. For this reason, it is not always sufficient in terms of ease of division (certainty) in the brittle material substrate after applying such a method.

  The present invention has been made in view of the above problems, and it is possible to divide a brittle material substrate more easily and surely than before, and to increase the end face strength of an individual piece after division compared to the prior art. An object of the present invention is to provide a processing method and a processing apparatus for a brittle material substrate.

To solve the above problems, the invention of claim 1, a method of processing along the brittle material substrate to be cut position, by condensing a pulsed laser beam, the surface of the brittle material substrate, before Symbol A melt ablation step that forms a groove extending along the planned cutting position and forming a crack extending from the groove in the thickness direction of the substrate by irradiating while scanning along the planned cutting position, and the melting Cooling the surface of the brittle material substrate that has undergone an ablation step, and in the melt ablation step, the position is directly below the focused position of the pulsed laser light in the irradiated region of the pulsed laser light. Evaporation and scattering of the constituent material of the brittle material substrate in the first region, and melting and scattering of the constituent material in the second region adjacent to the first region. The upper end portion of the groove portion, which is a portion forming a pair of opposing edges of the groove portion, is irradiated with the pulsed light under an irradiation condition that causes melt ablation that causes solidification and re-solidification. It is formed as a curved surface continuous from the upper surface of the substrate .

  According to a second aspect of the present invention, there is provided the method for processing a brittle material substrate according to the first aspect, wherein the pulsed laser beam is a UV laser.

  Invention of Claim 3 is a processing method of the brittle material substrate of Claim 1 or Claim 2, Comprising: In the said cooling process, the surface of the said brittle material substrate is cooled by the liquid, gas, or the mixture of a liquid and gas. It is characterized by.

Invention of Claim 4 is a processing method of the brittle material substrate according to any one of Claims 1 to 3, wherein in the melt ablation step, the groove portion includes the upper end portion, an intermediate portion, The middle part is formed so as to be composed of three parts with the bottom part, each of which is continuous from the upper end part, so that a pair of surfaces along the thickness direction of the brittle material substrate face each other or the upper end part The bottom portion is formed as a flat surface or a curved surface that is wider in the vicinity of the bottom portion than the vicinity thereof, and the bottom portion is formed as a curved surface that is continuous with each of the pair of surfaces forming the intermediate portion. , characterized in that.
A fifth aspect of the present invention is the brittle material substrate processing method according to any one of the first to fourth aspects, wherein in the melt ablation step, ablation does not occur if there is no overlap. The melt ablation is caused by irradiation with the pulsed laser light in which single pulsed light having a laser intensity is overlapped.
Invention of Claim 6 is a processing method of the brittle material substrate of Claim 5, Comprising: The said pulsed laser beam is UV laser whose wavelength is 355 nm, In the said melt ablation process, laser output: 4W-20W Laser intensity: 1.56 × 10 ¹⁰ W / cm ^{2 to} 7.81 × 10 ¹⁰ W / cm ² ; pulse repetition frequency: 0.2 MHz to 1.0 MHz; pulse width: 0.5 ns to 100 ns; scanning speed: 100 mm / s to 400 mm / s; overlap rate: 93.5% to 98.25%; condensing diameter at condensing position: 6 μm to 10 μm To do.

A seventh aspect of the present invention is a laser processing apparatus for irradiating a laser beam along a predetermined cutting position on the surface of a brittle material substrate, the laser light source emitting a pulse laser, and the pulse laser condensing the brittle material. An irradiation lens mechanism for irradiating the surface of the substrate, a cooling mechanism for supplying a coolant to the surface of the brittle material substrate, and the lens mechanism and the cooling mechanism relatively move along a planned division position on the surface of the brittle material substrate. A moving mechanism for moving the brittle material substrate, wherein the focused pulsed laser light is located in a region irradiated with the pulsed laser light and is located immediately below the focused position of the pulsed laser light. evaporation and scattering of constituents of the brittle material substrate in the first region and causes the melting and resolidification of the constituents in the second area adjacent to the first region, soluble Is applied to the surface of the brittle material substrate under the condition that ablation occurs, the cooling mechanism supplies coolant to the surface of the brittle material substrate on which the pulse laser is irradiated, characterized in that.

According to the first to seventh aspects of the invention, when the brittle material substrate is divided along a predetermined dividing line, a starting point for dividing can be formed at a deeper position in the substrate thickness direction than in the prior art. At the same time, it is possible to increase the end face strength of the individual pieces obtained after dividing.

1 is a diagram schematically showing a schematic configuration of a laser processing apparatus 10. It is sectional drawing perpendicular | vertical to the thickness direction of the board | substrate W which shows a mode that the pulse laser beam LB is condensed by the lens mechanism 3, and is irradiated to the board | substrate W. It is sectional drawing perpendicular | vertical to both the thickness direction of the board | substrate W, and the extending direction of a process planned line for demonstrating the mechanism of a fusion | melting ablation process and subsequent cooling. It is a figure which compares and shows the mode of the board | substrate W after performing the melt ablation process and cooling which concern on embodiment, and the mode of the board | substrate W after performing the process by another method. 2 is a cross-sectional SEM image of two substrates W subjected to melt ablation processing according to Condition 1. FIG. 4 is a cross-sectional SEM image of two substrates W subjected to melt ablation processing according to condition 2. FIG.

<Outline of laser processing equipment>
FIG. 1 is a diagram schematically showing a schematic configuration of a laser processing apparatus 10 according to an embodiment of the present invention. The laser processing apparatus 10 mainly includes a laser light source 1, a mirror mechanism 2, a lens mechanism 3, an XY stage 4, and a cooling mechanism 5. The laser processing apparatus 10 according to the present embodiment is configured to be capable of suitably performing melt ablation processing in a later-described mode for a brittle material substrate (hereinafter simply referred to as a substrate) W such as a glass substrate. It becomes.

  The laser light source 1 emits pulsed laser light LB from an internal oscillator. In the present embodiment, a laser light source 1 that emits UV laser light having a wavelength of 355 nm as pulsed laser light LB is used.

  The mirror mechanism 2 is a part for adjusting / changing the irradiation direction (irradiation angle) of the pulse pulse laser beam LB to the substrate W. In FIG. 1, for simplicity of illustration, only one mirror surface that reflects the pulse laser beam LB constitutes the mirror mechanism 2, and thereby the pulse laser beam LB is irradiated from the vertical direction to the substrate W in a horizontal posture. However, in practice, the mirror mechanism 2 may be configured by a plurality of mirror surfaces, and a mode in which prisms, diffraction gratings, and the like are included in the components of the mirror mechanism 2 may be used.

  The lens mechanism 3 is a part that condenses the pulsed laser beam LB. In FIG. 1, the case where the lens mechanism 3 is configured by only one lens is illustrated for simplicity of illustration, but in reality, the lens mechanism 3 may be configured by a plurality of lenses. The lens mechanism 3 is provided so that the vertical position of the condensing position of the pulse laser beam LB can be adjusted.

  In the present embodiment, the condensing position is a position where the beam diameter in the cross section perpendicular to the irradiation direction of the pulsed laser light LB is minimized. This generally corresponds to the focal position of the pulse laser beam LB, but in consideration of the fact that the pulse laser beam LB has a finite beam diameter at the focal position, in this embodiment, the beam diameter is the minimum. In consideration of the position, the word “focus position” is used instead of the word “focus position”.

  The adjustment of the condensing position may be realized by exchanging the lenses constituting the lens mechanism 3, or by changing the position of the lenses constituting the lens mechanism 3 by a position adjusting means such as an actuator (not shown). It may be realized.

  The XY stage 4 is a table on which the substrate W is placed, and is movable in two directions orthogonal to each other (the X direction and the Y direction) in the horizontal plane. In a state where the substrate W is placed and fixed on the upper surface of the XY stage 4, the pulse laser beam LB is emitted from the laser light source 1 while moving the XY stage 4 in the X direction or the Y direction. W scanning is realized. For example, by moving the pulse laser beam LB along a planned processing line set in advance on the surface of the substrate W, processing of the substrate W along the planned processing line is realized.

  The cooling mechanism 5 supplies the cooling medium CM to the surface of the substrate W. The refrigerant CM is a liquid or gas such as water, alcohol, carbon dioxide gas or nitrogen gas, or a mixture of liquid and gas. For example, the pulse laser beam LB is irradiated on the surface of the substrate W while the XY stage 4 is moved leftward in FIG. 1 while supplying the coolant CM from the cooling mechanism 5 to the surface of the substrate W. The surface of the substrate W processed by the light LB is cooled.

<Melting ablation>
Next, melt ablation processing using pulsed laser light LB performed in the present embodiment will be described. In the present embodiment, melt ablation processing is performed for the purpose of forming a portion that becomes a starting point when the substrate W is divided along a linear processing scheduled line (scheduling scheduled line) that is preset on the surface thereof. Assumed to be performed. That is, the melt ablation processing according to the present embodiment causes the melt ablation to occur along a linear planned processing line.

  FIG. 2 is a cross-sectional view perpendicular to the thickness direction of the substrate W, showing how the pulse laser beam LB is condensed by the lens mechanism 3 and irradiated onto the substrate W. FIG. 3 is a cross-sectional view perpendicular to both the thickness direction of the substrate W and the extending direction of the planned processing line, for explaining the mechanism of melt ablation processing and subsequent cooling in the present embodiment. In either case, the direction perpendicular to the drawing is the scanning direction of the pulse laser beam LB.

  In performing the melt ablation processing according to the present embodiment in this manner, as shown in FIG. 2, the pulse laser beam LB is irradiated with the upper surface Wa of the substrate W (the surface on the side not placed on the XY stage 4). Is irradiated to the substrate W in a mode in which the light is focused on the light. When the pulse laser beam LB is irradiated in this manner, the substrate W is heated in the vicinity of the condensing position F. When the irradiation condition of the pulse laser beam LB is appropriately set, the region RE1 immediately below the condensing position F is heated to a temperature exceeding the boiling point of the substrate W. Therefore, from such a region RE1, evaporation and scattering of the constituent material of the substrate W as shown by an arrow AR1 in FIG. On the other hand, the region RE2 around the region RE1 is heated to a temperature lower than the boiling point but exceeding the melting point of the substrate W. In such a region RE2, the substrate W is melted. After the pulse laser beam LB passes, when the temperature decreases due to heat dissipation, the substance existing in the region RE2 is solidified again. The melt ablation processing is a method intended to actively form such a region RE2 in which melting / resolidification occurs around the region RE1 in which ablation occurs. This is different from mere ablation that is not intended to be aggressively formed.

  As a result of the evaporation / scattering in the region RE1 and the melting / resolidification in the surrounding region RE2 as described above, the substrate W is perpendicular to the scanning direction as shown in FIG. Grooves G extending downward (in the thickness direction of the substrate W) from the upper surface Wa of the substrate W in the cross-sectional view are formed along the planned processing line. The groove part G has a surface shape formed by melting and re-solidifying the substance constituting the substrate W, and has a shape that is substantially symmetrical with respect to the thickness direction of the substrate W. Due to the difference in characteristics, it can be said that the three parts of the upper end G1, the intermediate part G2, and the bottom G3 are successively formed from the upper surface side of the substrate W.

  The upper end portion G1 is a portion forming a pair of opposing edges of the groove portion G, and each edge portion is formed of a curved surface continuous from the upper surface Wa of the substrate W. Each edge portion becomes an edge of an individual piece obtained by dividing the substrate W at the groove G. More specifically, the upper end portion G1 is formed such that a line of intersection with a cross section perpendicular to the scanning direction of the pulse laser beam LB (the extending direction of the groove portion G) has a smooth curve having an appropriate radius of curvature. Become. As a result, the piece after the division has a large end surface strength. This is presumably because microcracks are less likely to occur in the upper end G1 formed in a curved shape in the above-described state.

  The intermediate portion G2 is a portion formed by opposing a pair of surfaces along the thickness direction of the substrate, each continuous from the upper end portion G1. In other words, it can be said that the intermediate portion G2 is a portion corresponding to an extending portion of the groove portion G in the thickness direction of the substrate W. The intermediate portion G2 is opposed to a substantially flat surface such that, for example, the line of intersection with the cross section perpendicular to the scanning direction of the pulse laser beam LB (the extending direction of the groove portion G) is a straight line along the thickness direction. Alternatively, it may be formed as a flat surface or a curved surface in which the distance near the bottom G3 is wider than the vicinity near the upper end G1.

  The bottom G3 is a curved surface that is continuous with each of the pair of surfaces forming the intermediate portion G2. More specifically, the bottom G3 is formed so that the line of intersection with the cross section perpendicular to the extending direction of the groove G is a curve having an appropriate radius of curvature.

  Further, in the vicinity of the condensing position F of the pulse laser beam LB and outside the region RE2, the melting point does not reach the melting point, but heating by the pulse laser beam LB occurs. In such a region, thermal expansion occurs, and a tensile stress S1 acts from the condensing position F toward the outside. On the other hand, in the inside of the substrate W not affected by the heating by the pulse laser beam LB, the compressive stress S2 acts below the irradiation position of the pulse laser beam LB in order to cancel the thermal expansion described above.

  At this time, when the amount of heat input is larger than a certain amount because the scanning speed of the pulse laser beam LB is slow, as a result of the compressive stress S2, the pulse is emitted during heat radiation starting immediately after the pulse laser beam LB passes. A crack (vertical crack) CR extends downward from the lowermost end of the bottom G3 of the groove G formed by irradiation with the laser beam LB.

  That is, in the present embodiment, as a result of performing the melt ablation processing on the substrate W, both the formation of the groove portion G and the extension of the crack CR immediately below the groove portion G are realized.

  As shown in FIG. 3B, when the depths of the upper end G1, the intermediate portion G2, and the bottom G3 are D1, D2, and D3, the sum of D1, D2, and D3 is the depth of the groove G. Assuming that the length of the crack CR is L, the sum D + L of the depth D of the groove G and the length of the crack CR is the processing depth in the melt ablation processing according to the present embodiment.

  Note that, as described above, the melt ablation processing in the present embodiment in which the groove portion G and the crack CR are simultaneously formed in the above-described manner is performed by using the UV laser beam having a wavelength of 355 nm as the pulse laser beam LB. In addition to setting the upper surface Wa of the substrate W as the light condensing position, this is realized by satisfying the following processing conditions.

Laser power: 4W-20W;
Laser intensity: 1.56 × 10 ¹⁰ W / cm ^{2 to} 7.81 × 10 ¹⁰ W / cm ² ;
Pulse repetition frequency: 0.2 MHz to 1.0 MHz;
Pulse width: 0.5 ns to 100 ns;
Scanning speed: 100 mm / s to 400 mm / s;
Overlap rate: 93.5% to 98.25%;
Condensing diameter at condensing position: 6 μm to 10 μm

  Here, the scanning speed is generally a speed at which the pulse laser beam LB is moved relative to the substrate W. In the laser processing apparatus 10, the substrate W is mounted on the pulse laser beam LB. The speed at which the placed XY stage 4 is moved corresponds to this.

  The overlap rate is a value indicating the degree of overlap of irradiated areas of individual pulsed light (single pulsed light) of the pulsed laser light LB, and the pitch of the single pulsed light determined by the pulse repetition frequency and the scanning speed. It is calculated | required as ratio of the condensing diameter with respect to. If the pitch value is larger than the light collection diameter, the overlap rate is 0%, and if the pitch value is ½ of the light collection diameter, the overlap rate is 50%.

  Of the above-described processing conditions, the laser intensity is such that a single irradiation region is irradiated with a single pulse of light once, that is, no ablation occurs when the overlap rate is 0%. It is set as a range value. More specifically, it is set so that melt ablation occurs only when an overlap rate in the above-described range is observed. If the laser intensity is set in the above range and the overlap rate is larger than 0 but set to a value smaller than the above range, the substance is evaporated / scattered at the light condensing position F. It has been confirmed in advance by the inventor of the present invention that only melting and re-solidification or only crack generation and extension occur.

  Moreover, the depth D of the groove part G can be 10 micrometers-15 micrometers by adjusting the above-mentioned processing conditions suitably, and the length L of the crack CR can be 2 micrometers-3 micrometers. However, the actual value varies depending on the material of each substrate W.

<Cooling treatment>
In the present embodiment, the substrate W that has been melt-ablated in the above-described manner can be divided starting from the lowest end of the crack CR even in the state after the processing. In order to further extend the crack CR formed in the above-described manner, as shown in FIG. 3C, as shown by an arrow AR2 with respect to the upper surface Wa of the substrate W immediately after the melt ablation processing is performed. The substrate W is cooled from the side of the upper surface Wa by bringing the refrigerant into contact with the aspect.

  When cooling is performed in this manner, in the vicinity of the upper surface Wa of the substrate W, a tensile stress S3 acts temporarily from the groove G toward the outside. On the other hand, in the inside of the substrate W that is not in direct contact with the refrigerant, the compressive stress S4 acts toward the crack CR as the tensile stress S3 acts. From another viewpoint, in the inside of the substrate W, a compressive stress S4 acts as a temperature difference occurs with the upper surface Wa. As a result of the action of the compressive stress S4, as shown in FIG. 3D, the crack CR further extends in the thickness direction of the substrate. When the extension length of the crack CR during cooling is ΔL, LL = L + ΔL is the final crack CR length. The extension length ΔL of the crack CR due to cooling is about 4 μm.

  In such a cooled substrate W, the starting point when dividing in the subsequent process is the lowermost end portion of the crack CR at a depth D + LL from the upper surface Wa of the substrate W. Although depending on the type of the substrate W and the conditions of melt ablation, by cooling, the processing depth D + LL after cooling becomes several tens of percent larger than the processing depth D + L before cooling. By cooling after melt ablation, compared to the case where only the groove G is formed and the lowest end of the groove G is the starting point of the division, or compared to the case where only the melt ablation is performed, Easier and more reliable division is realized.

  Various modes can be applied as the cooling method. For example, a liquid such as pure water may be used as the refrigerant, or a gas such as low-temperature carbon dioxide may be used. Moreover, as a supply mode of the coolant, a mode in which the coolant is supplied to the entire upper surface Wa of the substrate W after the melt ablation processing is finished, or while the irradiation of the pulse laser beam LB is in progress (that is, the groove portion). In the middle of formation of G and crack CR), a mode may be used in which the coolant is supplied to the pin point with respect to the location where the groove G and crack CR are already formed.

  FIG. 4 is a diagram showing the state of the substrate W after the melt ablation processing and the subsequent cooling according to the present embodiment are compared with the state of the substrate W after processing by another method. is there. FIG. 4 (a) shows the state after cooling shown in FIG. 3 (d) again.

  On the other hand, FIG. 4B shows the thickness direction of the substrate W when processing is performed under the condition that only mere ablation that does not actively cause melting (hereinafter referred to as conventional method 1) is performed. It is sectional drawing perpendicular | vertical to both the extending direction of a process planned line. Such processing is realized by increasing the laser intensity beyond the above range.

  As shown in FIG. 4B, in the case of the conventional method 1, the groove portion Gα is formed as in the case where the melt ablation according to the present embodiment is performed. However, although the depth Dα of the groove part Gα is substantially the same as the depth D of the groove part G, cracks (vertical cracks) hardly extend from the bottom part of the groove part Gα. This is the same even if the substrate W is subsequently cooled.

  In other words, the combination of melt ablation and cooling according to the present embodiment is more effective at the starting point of division than the conventional method 1 illustrated in FIG. 4B (or more than when cooling is performed). Since it can be formed in a deep position, it is possible to realize easy and reliable division.

  Further, the edge E of the groove part Gα is angular. Therefore, the end face strength of the piece obtained after the division is weaker than in the case of the present embodiment in which the edge portion is a curved surface. When melt ablation is performed in the aspect according to the present embodiment, the end face strength of the piece after the division is about 4 to 5 times that in the case of the conventional method 1. Therefore, it is possible to obtain an effect that the end face strength of the piece after the division can be further increased as compared with the case where the processing is performed by the conventional method 1.

  Further, FIG. 4C shows a condensing position below the lower surface Wb of the substrate W using a UV laser having a wavelength of 266 nm as the pulse laser beam as in the embodiment exemplified in Patent Document 2. 6 is a cross-sectional view perpendicular to both the thickness direction of the substrate W and the extending direction of the planned processing line when melt ablation processing is performed with the above set (hereinafter referred to as conventional method 2).

  As shown in FIG. 4C, in the case of the conventional method 2, the groove portion Gβ is formed as in the case where the melt ablation according to the present embodiment is performed. However, the depth Dβ of the groove part Gβ remains in a smaller range than the depth D of the groove part G. Specifically, it is about 6 μm to 8 μm at most. The groove part Gβ is roughly formed so as not to have a part corresponding to the intermediate part G2 of the groove part G formed in the present embodiment, but to have only parts corresponding to the upper end part G1 and the bottom part G3. Also, cracks (vertical cracks) hardly extend from the bottom of the groove Gβ.

  Therefore, since the combination of melt ablation and cooling according to the present embodiment can form the starting point of the fragmentation deeper than the conventional method 2 illustrated in FIG. Easy and reliable division can be realized.

  Further, even in the case of the conventional method 2, the edge of the piece after dividing becomes a curved surface, but the melt ablation processing according to the present embodiment increases the end face strength of the piece obtained after dividing, It has been confirmed experimentally.

  As described above, according to the present embodiment, when a brittle material substrate is divided along a predetermined dividing line, UV laser light having a wavelength of 355 nm is focused on the upper surface of the substrate. In this state, irradiation is performed while scanning along the planned dividing line under conditions where melt ablation occurs, and then cooling is performed, so that a starting point for dividing can be formed at a deeper position in the substrate thickness direction than before. It is possible to increase the end face strength of the piece obtained after dividing.

As an example, with respect to a glass substrate having a thickness of 0.3 mm (OA-10G manufactured by Nippon Electric Glass Co., Ltd., thermal expansion coefficient 38 × 10 ⁻⁷ / ° C.), along the planned processing line defined linearly, the following An attempt was made to form the groove G and the crack CR under four different conditions.

  Specifically, melt ablation according to the following condition 1 was performed on the two substrates W, and only one of the substrates W was cooled with pure water.

<Condition 1>
Laser wavelength: 355 nm;
Laser power: 12.0W;
Laser intensity: 4.69 × 10 ¹⁰ W / cm ² ;
Pulse repetition frequency: 1 MHz;
Pulse width: 1 ns;
Scanning speed: 350 mm / s;
Overlap rate: 93.9%;
Condensing position: substrate surface;
Condensing diameter at the condensing position: 6 μm.

  The cooling process was performed by supplying pure water from a position 5 mm above the upper surface Wa of the substrate W to a position 15 mm behind the focusing position of the pulse laser light LB in the scanning direction of the pulse laser light LB. Supply flow rate is 1 ml / min. It was.

  Further, melt ablation according to the following condition 2 was performed on another two substrates W, and only one of the substrates W was cooled with carbon dioxide gas.

<Condition 2>
Laser wavelength: 355 nm;
Laser power: 4.0W;
Laser intensity: 1.56 × 10 ¹⁰ W / cm ² ;
Pulse repetition frequency: 1 MHz;
Pulse width: 1 ns;
Scanning speed: 100 mm / s;
Overlap rate: 98.3%;
Condensing position: substrate surface;
Condensing diameter at the condensing position: 6 μm.

  In the cooling process, carbon dioxide gas at a low temperature (about −20 ° C.) is applied from a position 5 mm above the upper surface Wa of the substrate W to a position 15 mm behind the focused position of the pulse laser light LB in the scanning direction of the pulse laser light LB. Done by feeding. Supply flow rate is 1 ml / min. It was.

  5 and 6 are cross-sectional SEM images of two substrates W that have been subjected to melt ablation processing in accordance with Condition 1 and Condition 2, respectively. FIGS. 5A and 6A are images of the substrate W that has not been cooled, and FIGS. 5B and 6B are images of the substrate W that has not been cooled.

  In both FIG. 5 and FIG. 6, the processing depth (D + LL) when cooling is performed is larger than the processing depth (D + L) when cooling is not performed.

  Such a result means that the combination of the melt ablation process and the cooling process is effective in forming the starting point of the division at a deeper position.

DESCRIPTION OF SYMBOLS 1 Laser light source 2 Mirror mechanism 3 Lens mechanism 4 XY stage 5 Cooling mechanism 10 Laser processing apparatus CM Cooling medium CR Crack E Edge (of groove part Gα) F Condensing position G, Gα, Gβ Groove G1 (Upper part of groove part G) G2 Intermediate portion G3 (of groove G) Bottom portion of LB pulse laser beam S1, S3 Tensile stress S2, S4 Compressive stress W Substrate Wa (Substrate W) upper surface Wb (Substrate W) lower surface

Claims (7)

A method of processing a brittle material substrate along a planned cutting position,
It condenses the pulsed laser beam, the substrate from the groove with the surface of the brittle material substrate, by irradiating while scanning along the front SL be cut position to form a groove along the cutting scheduled position Forming a crack extending in the thickness direction of the melt ablation process;
A cooling step of cooling the surface of the brittle material substrate that has undergone the melt ablation step;
Equipped with a,
In the melt ablation step, evaporation and scattering of constituent materials of the brittle material substrate in a first region located immediately below the condensing position of the pulsed laser light among irradiated regions of the pulsed laser light, By irradiating the pulsed light under irradiation conditions in which melt ablation occurs, which causes melting and re-solidification of the constituent material in the second region adjacent to the first region, a pair of opposing grooves The upper end portion of the groove portion that is a portion forming the edge of is formed as a curved surface continuous from the upper surface of the brittle material substrate.
A method for processing a brittle material substrate, characterized in that: A method for processing a brittle material substrate according to claim 1,
The pulse laser beam is a UV laser;
A method for processing a brittle material substrate, characterized in that: A method for processing a brittle material substrate according to claim 1 or 2,
In the cooling step, the surface of the brittle material substrate is cooled by liquid, gas, or a mixture of liquid and gas.
A method for processing a brittle material substrate, characterized in that: A method for processing a brittle material substrate according to any one of claims 1 to 3,
In the melt ablation step, the groove portion is formed so as to consist of three portions, the upper end portion, an intermediate portion, and a bottom portion,
The intermediate portion is continuously spaced from the upper end portion so that a pair of surfaces along the thickness direction of the brittle material substrate face each other or in the vicinity of the bottom portion rather than in the vicinity of the upper end portion. It is formed as a flat or curved surface that becomes wider,
The bottom portion is formed as a curved surface continuous with each of the pair of surfaces forming the intermediate portion,
A method for processing a brittle material substrate, characterized in that: A method for processing a brittle material substrate according to any one of claims 1 to 4,
In the melt ablation step, when there is no overlap, the melt ablation is caused by irradiation with the pulsed laser light that is overlapped with a single pulse light having a laser intensity that does not cause ablation.
A method for processing a brittle material substrate, characterized in that: A method for processing a brittle material substrate according to claim 5,
The pulse laser beam is a UV laser having a wavelength of 355 nm,
In the melt ablation process,
Laser power: 4W-20W;
Laser intensity: 1.56 × 10 ¹⁰ W / cm ² ~ 7.81 × 10 ¹⁰ W / cm ² ;
Pulse repetition frequency: 0.2 MHz to 1.0 MHz;
Pulse width: 0.5 ns to 100 ns;
Scanning speed: 100 mm / s to 400 mm / s;
Overlap rate: 93.5% to 98.25%;
Condensing diameter at the condensing position: 6 μm to 10 μm,
The pulse laser beam is irradiated under the condition
A method for processing a brittle material substrate, characterized in that: A laser processing apparatus for irradiating a laser beam along a planned cutting position on a brittle material substrate surface,
A laser light source that emits a pulsed laser;
An irradiation lens mechanism for condensing the pulse laser and irradiating the surface of the brittle material substrate;
A cooling mechanism for supplying a coolant to the surface of the brittle material substrate;
A moving mechanism for moving the brittle material substrate so that the lens mechanism and the cooling mechanism move relatively along the planned cutting position on the brittle material substrate surface;
With
The condensed pulsed laser light is evaporated and scattered in the first region located directly below the focused position of the pulsed laser light in the irradiated region of the pulsed laser light. And irradiating the surface of the brittle material substrate under conditions where melt ablation occurs, causing melting and resolidification of the constituents in a second region adjacent to the first region ,
The cooling mechanism supplies a coolant to the surface of the brittle material substrate irradiated with the pulse laser.
An apparatus for processing a brittle material substrate.