The present invention relates to a laser processing method, and in particular, to a laser processing method in which working is performed so as to hollow out a predetermined portion of an object to be processed.
As a conventional laser processing method, a method for irradiating a plate-shaped object with a laser light so as to focus a converging point on the object, to form a modified region inside the object is known (refer to Patent Literature 1, for example). Further, it is designed to partition the object into a plurality of chips from the modified region as a starting point by applying external stress to the object in which a modified region is formed by utilizing such a processing method (refer to Patent Literature 2, for example).
Patent Literature 1: Japanese Patent Application Laid-Open No. H4-111800
Patent Literature 2: Japanese Patent Application Laid-Open No. 2004-343008
Here, in recent years, in such a laser processing method as described above, working is performed so as to hollow out a predetermined portion of the object by utilizing a modified region formed inside the object in some cases. However, in this case, fracture or breakage may be caused in the object, that may deteriorate the strength and quality of the object after working.
Therefore, an object of the present invention is to provide a laser processing method which is capable of improving the strength and quality of an object to be processed after working.
In order to solve the above-described object, there is provided a laser processing method according to the present invention for working so as to hollow out a predetermined portion of an object to be processed by utilizing a modified region which is formed by converging a laser light inside the object, the method includes a laser light irradiating process of irradiating the object with the laser light, to form the modified region along an outline of the predetermined portion in the object, an etching process of performing etching onto the object after the laser light irradiating process, to selectively advance etching along a fracture which is contained in the modified region or extend from the modified region, and a spacing and moving process of spacing and moving the predetermined portion from the object after the etching process, and in which, in the laser light irradiating process, the modified region is formed so that the fracture is connected along the outline, and the fracture is exposed on an outer surface side of the object.
In the laser processing method, it is possible to perform working so as to hollow out the predetermined portion without applying external stress. Therefore, it is possible to prevent the object from being damaged or deteriorated in strength by application of external stress. Moreover, in the etching process, it is possible to remove fracture generated according to the formation of the modified regions from the object after working. Accordingly, it is possible to improve strength and quality of the object after working by the etching process.
Further, in the laser light irradiating process, it is preferable that a first modified region is formed at a first depth position in a direction of irradiation with the laser light in the object, and thereafter, a second modified region is formed at a second depth position on a laser light irradiation surface side from the first depth position in the object. In this case, it is possible to prevent an effect of the existing first modified region from being exerted on formation of the second modified region, and it is possible to accurately form the second modified region.
Further, it is preferable that the laser light irradiating process includes a first process of repeatedly performing the process of irradiating with the laser light while relatively moving a converging point of the laser light along one direction perpendicular to the direction of irradiation with the laser light, so as to change a depth position of the converging point in the direction of irradiation, and a second process of repeatedly performing the first process so as to change a position of the converging point in the other direction perpendicular to the direction of irradiation and the one direction. In this case, it is possible to shorten a takt time for the laser light irradiating process.
Further, it is preferable that a shape of the outline of the predetermined portion has a taper portion tilted to a direction perpendicular to one surface of the object so as to widen toward the one surface side. In this case, in the spacing and moving process, for example, the predetermined portion is moved so as to be taken out from the one surface side, thereby it is possible to easily space and move the predetermined portion from the object.
In accordance with the present invention, it is possible to improve strength and quality of the object after working.
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same or corresponding components in the following description are denoted by the same reference numerals and letters, and overlapping descriptions thereof will be omitted.
In a laser processing method according to the present invention, working is performed so as to hollow out a predetermined portion of an object to be processed by utilizing a modified region which is formed by converging a laser light inside the object. Then, first, the formation of a modified region will be hereinafter described with reference to
As shown in
In this laser processing apparatus 100, the laser light L emitted from the laser light source 101 is changed in direction of its optical axis by 90 degrees by the dichroic mirror 103, and is collected inside the plate-like object 1 placed on the support table 107 by the condenser lens 105. At the same time, the stage 111 is moved, to relatively move the object 1 along a part to form a modified region 5 with respect to the laser light L. Thereby, a modified region along the part 5 is formed in the object 1.
A semiconductor material, a piezoelectric material, or the like may be used as the object 1. As shown in
In addition, the converging point P is a place on which the laser light L is collected. Further, the part 5 is not limited to a linear shape, and may be a curved shape, a curved or planar three dimensional shape, and a shape whose coordinates are specified. Further, the modified region 7 is continuously formed in some cases, and is intermittently formed in some cases. Further, the modified region 7 may be a row form or a point form, that is, it suffices that the modified region 7 is formed at least inside the object 1. Further, a fracture may be formed from the modified region 7 as a starting point in some cases, and the fracture and the modified region 7 may be exposed at the outer surface (the surface, the rear surface, or the outer circumferential surface) of the object 1.
Incidentally, here, the laser light L is made transmissive through the object 1 and is absorbed particularly in the vicinity of the converging point inside the object 1, and thereby forming the modified region 7 in the object 1 (i.e., internal absorption type laser working). Therefore, the laser light L is hardly absorbed into the surface 3 of the object 1, and thus, the surface 3 of the object 1 does not melt in any case. Generally, in the case in which removal portions such as holes, grooves, and the like are melted and removed from the surface 3 to be formed (surface absorption type laser working), a working region gradually advances from the surface 3 side to the rear surface side.
Meanwhile, a modified region formed by the laser processing apparatus according to the present embodiment means a region coming into a state different in density, refractive index, mechanical strength, and other physical characteristics from the circumference thereof. As a modified region, for example, there is a molten processed region, a crack region, a dielectric breakdown region, a refractive index change region, or the like, and there is a region where these are mixed as well. Moreover, as a modified region, there is a region in which the density of a modified region is changed as compared with the density of an unmodified region in a material of the object, or a region in which a lattice defect is formed (these may be collectively called a high-density transitional region).
Further, in some cases, a molten processed region, a refractive index change region, a region in which the density of a modified region is changed as compared with the density of an unmodified region, and a region in which a lattice defect is formed may further contain a fracture (cut or microcrack) inside those regions or in the interface between the modified region and the unmodified region. The fracture to be contained may spread over the entire surface of the modified region or may be formed in only one portion or a plurality of portions in some cases. As the object 1 is, for example, an object consisting of silicon, glass, LiTaO3, or sapphire (Al2O3), or an object composed of those may be cited.
Here, in the present embodiment, after the modified region 7 is formed in the object 1, etching is performed onto the object 1 so as to selectively advance etching along a fracture (called crack, microcrack, break, or the like. Hereinafter, called simply “fracture”) which are contained in the modified region 7 or extend from the modified region 7, to remove a region corresponding to the outline of a predetermined portion (hollowed-out portion) in the object 1.
In detail, in etching of the present embodiment, an etchant is infiltrated into the fracture which is contained in the modified region 7 or extend from the modified region 7 in the object 1, to advance etching along the creviced surface. Thereby, etching is advanced selectively at a high etching rate along the fracture to remove the fracture in the object 1. At the same time, etching is advanced selectively along the modified region 7 as well to remove the modified region 7 by utilizing the feature that the etching rate of the modified region 7 is high.
As etching of the present embodiment, there is a case in which the object is dipped into an etchant (a dipping method: Dipping), and a case in which an etchant is applied to the object while rotating the object (a spin etching method: Spin Etching).
Next, a first embodiment of the present invention will be described in detail.
As shown in
In addition, in the following description, the thickness direction of the object 1 (the direction of irradiation with the laser light L) is set as the Z direction, one direction along the surface 3 that is a laser light irradiation surface of the object 1 (direction perpendicular to the direction of irradiation with the laser light L) is set as the X direction, and another direction perpendicular to the X and Z directions (a direction perpendicular to the direction of irradiation with the laser light L and the one direction) is set as the Y direction.
As shown in
In the case where working for the object 1 is performed in the present embodiment, first, as shown in
Next, a converging point of the laser light L (hereinafter, simply called “converging point”) is focused on a Z directional position on the rear surface 21 side of the object 1, and at the same time, this converging point is relatively moved in the X direction. In accordance therewith, ON and OFF irradiation with the laser light L is performed so as to form the modified regions 7 at the part 5 (refer to
Thereby, the modified region (first modified region) 7 exposed at the rear surface 21 in the Z directional position (a first depth position) on the rear surface 21 side of the object 1 is intermittently formed along the X direction. In addition, here, because spot-irradiation with a pulse laser light serving as the laser light L is performed, the modified region 7 to be formed is composed of modified spots. Further, the fracture generated from the modified region 7 is inclusively formed in the modified region 7 (that is the same as in the following modified region).
Next, as shown in
Next, the ON and OFF irradiation with the laser light L described above is repeatedly performed while changing the Z directional position for the converging point in order from the rear surface 21 side to the surface 3 side (the first process). Thereby, as shown in
In addition, when the relative movement of the converging point at the time of the ON and OFF irradiation with the laser light L is repeatedly performed in order from the rear surface 21 side to the surface 3 side, it is preferable that the converging point is relatively moved so as to be reciprocated in the X direction in order to shorten a takt time. That is, after performing ON and OFF irradiation with the laser light L while relatively moving the converging point in one direction of the X direction, it is preferable to perform ON and OFF irradiation with the laser light L while relatively moving the converging point in the other direction of the X direction.
Next, the above-described processes shown in
Next, as shown in
Next, a tape for removing 17 is stuck on the surface 3 of the object 1 as shown in
In accordance with the above-described processes, working is performed so as to hollow out the hollowed-out portions Q1 and Q2 of the object 1, thereby forming through-holes 33 in the object 1. Thereafter, as shown in
As described above, in accordance with the present embodiment, it is possible to perform working so as to hollow out the hollowed-out portions Q1 and Q2 from the object 1 without applying external stress. Therefore, it is possible to prevent the object 1 from being damaged or deteriorated in strength by application of external stress. Moreover, because etching is selectively advanced along the modified regions 7 and the fracture contained in the modified regions 7, it is possible to remove the fracture from the object 1′ after working, which makes it possible to improve strength and quality of the object 1′ after working. Further, because dust due to working is not generated as in a cutting work, it is possible to achieve a processing method, which is friendly to the working environment.
Further, in the present embodiment, as described above, after the modified region 7 is formed, the modified region 7 is newly formed on the surface 3 side in comparison to the existing modified region 7. Therefore, it is possible to prevent an effect of the existing modified region 7 from being exerted on the modified region 7 to be newly formed. Therefore, it is possible to accurately form the modified regions 7.
Further, in the present embodiment, as described above, the process of irradiation with the laser light L while relatively moving the converging point along the X direction is repeatedly performed while changing the Z directional position for the converging point (refer to
Further, in the present embodiment, as described above, because the modified regions 7 formed inside the object 1 by irradiation with the laser light L are utilized, it is possible to perform working so as to freely hollow out the object 1 in three dimensions.
In addition, in the present embodiment, as shown in
Further, in the present embodiment, as described above, the hollowed-out portions Q1 and Q2 are removed by use of the tape for removing 17 (refer to
In detail, after performing etching onto the object 1, the object 1 is inversed upside down, and the surface 3 is adsorbed by the air adsorption part 35 as shown in
Alternately, after performing etching onto the object 1, the hollowed-out portions Q1 and Q2 may be removed by use of an adhesive roller 36 as shown in
Next, a second embodiment of the present invention will be described. In addition, in the present embodiment, points different from the first embodiment will be mainly described.
In the present embodiment, working is performed so as to hollow out a plurality of hollowed-out portions Q3 and Q4 in the object 1. Here, the hollowed-out portions Q3 and Q4 are conical trapezoid-shaped with the surface 3 serving as the bottom surface. That is, the hollowed-out portions Q3 and Q4 have taper portions 55 tilted to the Z direction (a direction perpendicular to the surface 3) so as to widen toward the surface 3 (one surface) of the object 1, on their side surfaces.
In the case where working for the object 1 is performed in the present embodiment, first, as shown in
Next, after performing etching onto the object 1 in which the modified regions 57 are formed, to remove the modified regions 57 in the object 1 as shown in
As described above, in the present embodiment as well, the above-described operation and effect that improve the strength and quality of the object 1′ after working are exerted.
Further, in the present embodiment, as described above, the modified regions 57 tilted to the Z direction when viewed from the Y direction are formed in the object 1, to hollow out the hollowed-out portions Q3 and Q4 having taper portions 55. Therefore, the following operation and effect are exerted. That is, it is easy to move the hollowed-out portions Q3 and Q4 so as to take out those from the surface 3 side, which makes it possible to easily remove the hollowed-out portions Q3 and Q4 from the object 1. Moreover, when the object 1′ is laminated on the device substrate 31 after working (refer to
In addition, in the present embodiment, as shown in
Next, a third embodiment of the present invention will be described. In addition, in the description of the present embodiment, points different from the first embodiment will be mainly described.
In the present embodiment, working is performed so as to hollow out a plurality of hollowed-out portions Q5 and Q6 in the object 1. The hollowed-out portion Q5 includes a hollowed-out portion Q5a on the surface 3 side and a hollowed-out portion Q5b on the rear surface 21 side, and the hollowed-out portion Q6 includes a hollowed-out portion Q6a on the surface 3 side and a hollowed-out portion Q6b on the rear surface 21 side.
The hollowed-out portions Q5a and Q6a are conical trapezoid-shaped with the surface 3 serving as the bottom surface. Further, the hollowed-out portions Q5a and Q6a have taper portions 71 tilted to the Z direction so as to widen toward the surface 3 side of the object 1, on their side surfaces. On the other hand, the hollowed-out portions Q5b and Q6b are conical trapezoid-shaped with the rear surface 21 serving as the bottom surface. Further, the hollowed-out portions Q5b and Q6b have taper portions 72 tilted to the Z direction so as to widen toward the rear surface 21 side of the object 1, on their side surfaces.
In the case where working for the object 1 is performed in the present embodiment, first, as shown in
The modified regions 77 connect to each other along the respective side surfaces of the conical trapezoid-shaped hollowed-out portions Q5 and Q6, and are further exposed on the surface 3 side and the rear surface 21 side of the object 1. The modified regions 77 extend so as to be inflected when viewed from the Y direction (X direction). The modified region 78 extends along the X-Y plane so as to define the hollowed-out portions Q5a and Q5b at the middle position in the Z direction of the modified region 77, to connect to the modified region 77. The modified region 78 is formed linearly along the X direction (Y direction) when viewed from the Y direction (X direction), and formed to be circular when viewed from the Z direction.
Next, after performing etching onto the object 1 to remove the modified regions 77 in the object 1 as shown in
Thereby, working is performed so as to hollow out the hollowed-out portions Q5 and Q6 in the object 1, thereby forming through-holes 53 in the object 1 as shown in
As described above, in the present embodiment as well, the above-described operation and effect that improve the strength and quality of the object 1′ after working are exerted.
Further, in the present embodiment, as described above, the modified regions 77 extending so as to be inflected when viewed from Y direction are formed in the object 1, to hollow out the hollowed-out portions Q5 and Q6 having taper portions 71 and 72. Therefore, the following operation and effect are exerted. That is, it is easy to move the hollowed-out portions Q5a and Q6a so as to take out those from the surface 3 side, and it is also easy to move the hollowed-out portions Q5b and Q6b so as to take out those from the rear surface 21 side, which makes it possible to easily remove the hollowed-out portions Q5 and Q6 from the object 1. Moreover, when the object 1′ is laminated on the device substrate 31 after working (refer to
In addition, in the present embodiment, as shown in
Further, as shown in
The preferred embodiments of the present invention have been described above. However, the laser processing method according to the present invention is not limited to the above-described embodiments, and may be modified within the scope of the gist disclosed in the respective claims, or may be applied to another embodiment.
For example, a laser light incidence plane at the time of forming modified regions is not limited to the surface 3 of the object 1, and may be the rear surface 21 of the object 1. Further, in the above-described embodiments, working is performed so as to hollow out the two hollowed-out portions at the same time. However, the number of hollowed-out portions may be one or three, or more.
Further, the above-described embodiments are working for forming through-holes in the object. However, the above-described embodiments are not limited thereto, and may be working for outline working of the object. That is, hollowed-out portions (predetermined portions) may be manufactured products.
Further, in the above-described embodiments, the modified regions themselves are connected to one another along the outlines of the hollowed-out portions. However, it suffices that the fracture which is contained in the modified regions 7 or extend from the modified regions may be connected along the outlines of the hollowed-out portions.
Further, ON and OFF irradiation with the laser light L in the above-described embodiment may be performed by, not only controlling emission with the laser light L to be ON and OFF, but also opening and closing a shutter provided on the optical path of the laser light L, masking the surface 3 of the object 1, or the like. Moreover, an intensity of the laser light L may be controlled between an intensity which is higher than or equal to a threshold value (working threshold value) at which the modified regions are formed and an intensity which is lower than or equal to the working threshold value.
Further, in the present invention, in some cases, modified regions may be formed along the outlines of the hollowed-out portions by repeatedly performing the process of irradiation with the laser light L while moving the converging point in the X direction and the Y direction along the part to form a modified region so as to focus a converging point on a predetermined Z directional position, while changing the Z directional position for the converging point.
In accordance with the present invention, it is possible to improve strength and quality of a processed object to be processed.
1: Object, 3: Surface (one surface, outer surface), 7, 57, 77:
Modified regions (first modified regions, second modified regions), 21: Rear surface (one surface, outer surface), 55, 71, 72: Taper portions, 78: Modified regions, C1 to C3: fracture, L: laser light, P: Converging point, Q1 to Q6: Hollowed-out portions (predetermined portions).
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2011/062254 | 5/27/2011 | WO | 00 | 2/9/2012 |