JP6977191B1 - Laser processing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly perform laser processing of a product suitable for mass production such as a semiconductor wafer and a radial slide bearing into a desired shape or state. A laser processing apparatus irradiates a surface of a rotationally symmetric irradiation target with a laser beam to perform laser processing. The laser processing apparatus includes a laser light source capable of emitting a laser beam and a first optical element for changing the laser beam emitted from the laser light source in a direction different from the emission direction. Further, the present invention also includes a second optical element including a drive mechanism for scanning the laser beam emitted from the first optical element in the circumferential direction of the irradiation target. [Selection diagram] Fig. 1

Description

The present invention relates to a laser processing apparatus, and particularly relates to a laser processing apparatus suitable for flattening a surface to be formed with a chip of a semiconductor wafer and processing an inner surface of a cylindrical bearing.

Wafer processing for forming a circuit on a semiconductor wafer often includes a step of forming the front surface or the back surface of the wafer into a flat surface having a small surface roughness. Conventionally, such a process has been carried out using a grinding wheel or a polishing pad. However, if the grinding wheel or the polishing pad is unevenly worn when the surface of the wafer is ground or polished, the flatness of the machined surface is distorted and the quality is deteriorated.

In order to solve such a problem, in Patent Document 1, the following three steps are executed for the planned cutting position, which is the position where the semiconductor wafer is divided into chips. That is, before laser processing, the step of grinding or polishing the back surface of the wafer to flatten it, and irradiating the front surface side and the back surface side of the wafer arranged upside down with a laser to check the flatness of the back surface side. There are three steps: a step and a step of irradiating the laser with a condensing point set inside the wafer from the back surface side to the planned cutting position of the wafer.

Patent Document 2 discloses that a laser annealing method having uniform processing quality is realized. In the laser annealing method described in this publication, a semiconductor wafer having an uneven front surface is prepared, and the concave side of the front surface is filled with a filler. The front surface of the semiconductor wafer filled with the filler is held on the annealing table in a posture facing the annealing table, and the back surface of the held semiconductor wafer is irradiated with a laser beam to perform annealing.

Further, Patent Document 3 discloses that a defect formed in a wafer is annealed. _{The system described in this publication includes a CO 2} system line forming system configured to form a first line image with an optical output of 2000 W to 3000 W on the wafer surface. The first line image is scanned over the wafer surface and locally raises the temperature to the defect annealing temperature. In addition, it includes a visible wavelength ray forming system, which forms a second line image and locally raises the wafer surface temperature to the spike annealing temperature. Spike annealing is performed to reduce harmful pattern effects and improve temperature uniformity and associated annealing uniformity.

On the other hand, Patent Document 4 discloses a method for processing a cylindrical inner surface in which a groove is formed on a small-diameter cylindrical inner surface with high dimensional accuracy. In this publication, a laser beam is focused by a condenser lens, reflected by a small reflection mirror provided inside the bearing sleeve, and condensed on the inner peripheral surface of the bearing sleeve. By moving and rotating the bearing sleeve in the axial and circumferential directions, the focal point is moved on the inner peripheral surface of the bearing sleeve, and a groove is formed on the inner surface of the bearing sleeve.

JP-A-2019-121677 Japanese Unexamined Patent Publication No. 2016-143833 Japanese Unexamined Patent Publication No. 2016-105470 Japanese Unexamined Patent Publication No. 6-315784

In the grinding or polishing method using a grindstone or a polishing pad conventionally used for flattening the front surface or the back surface of a wafer, in addition to the unevenness of the surface caused by uneven wear, the abrasive grains are abraded due to the wear of the grindstone. Therefore, there is a possibility that unacceptable unevenness may be formed on the finished surface on the surface having less unevenness. Further, there is a possibility that a part of the machining stress during machining remains in the wafer as residual stress, and the more the unevenness of the surface is reduced, the longer the machining takes.

In the method of Patent Document 1, in order to solve such a problem, lighting means are arranged above the front surface of the inverted wafer and on the peripheral edge of the back surface to check the flatness of the back surface of the wafer, and then Laser processing is performed by aligning the condensing point inside the wafer at the planned cutting position. Since the laser irradiation from the back surface side to the entire wafer is for imaging to confirm the flatness and to judge whether or not the laser beam is diffusely reflected, the laser beam is applied to the front surface or the back surface of the wafer with uniform intensity and uniform short length. It is not configured to improve the processing efficiency by irradiating for a long time and performing flattening annealing of the irradiated surface for a short time.

In the wafer annealing device described in Patent Document 2, the wafer is held upside down and the laser beam is focused on the back surface side. The shape of the laser beam is a predetermined long shape, and the light intensity distribution is uniform within the long shape. In this device, since the laser beam position is fixed, it is necessary to constantly move the wafer within the wafer beam range in order to anneal all over the wafer surface, and the annealing table on which the laser is placed is two-dimensional. Or it is necessary to move it three-dimensionally. Since this movement and positioning are performed on a general three-dimensional table or a three-dimensional + θ table, positioning takes time and the wafer processing throughput decreases.

Further, in the defect annealing device described in Patent Document 3, the laser beam from the light source is obliquely guided to the wafer surface through a plurality of mirrors, and the defect portion formed on the wafer is irradiated with the laser beam. In this device, the folded mirror optical system is made variable and the laser irradiation angle to the wafer is made variable. Therefore, in order to irradiate the laser beam at the desired position of the wafer, it is necessary to highly control the folded mirror optical system. This complicates the optical system.

On the other hand, in Patent Document 4, a small mirror is arranged in the bearing sleeve to form a groove on the inner surface of the bearing. Since a small mirror is arranged in the sleeve in this processing apparatus, the size of the mirror is limited to the size that can be inserted with a gap between the mirror and the sleeve. Therefore, in order to process the inner surface of an extremely small bearing, a small and complicated jig for holding the mirror at a position that does not interfere with the movement of the sleeve is required.

The present invention has been made in view of the above-mentioned defects of the prior art, and it is intended to enable rapid laser processing of products suitable for mass production such as semiconductor wafers and radial plain bearings into the desired shape or state. The purpose. In particular, in the case of semiconductor wafers, the purpose is to enable rapid flattening and uniform annealing of the front or back surface of the wafer, and in the case of small bearing parts, the inner surface can be shaped into a desired shape for a short time. The purpose is to be able to process with.

The features of the present invention that achieve the above object are a laser light source capable of emitting laser light and the laser light source in a laser processing apparatus that irradiates one surface of an object to be irradiated with laser light in a rotationally symmetrical manner to perform laser processing. A first optical element that changes the laser light emitted from the laser beam in a direction different from the emission direction, and a mechanism that controls scanning of the laser beam emitted from the first optical element in the circumferential direction of the irradiation target. 2 is to be provided with an optical element.

In this feature, the first and second optical elements are wedge prisms including a wedge prism and a translational control mechanism and / or rotation control mechanism, respectively, and the irradiation target is a semiconductor wafer, and the one surface thereof. Is either the surface on which the circuit of the semiconductor wafer is formed or the opposite surface, and it is preferable that the one surface is annealed by irradiating the irradiation target with the laser light emitted from the laser light source. The first and second optical elements are wedge prisms including a wedge prism and a translational control mechanism and / or a rotation control mechanism, respectively, and the one surface of the irradiation target is a sleeve-shaped inner peripheral surface. It is also preferable to irradiate the object to be irradiated with the laser light emitted from the laser light source to form a groove on the one surface.

In the above characteristics, a galvano scanner and an f−θ lens may be arranged between the second optical element and the irradiation target object, and the laser light source, the first optical element, and the second optical element may be arranged. Two sets of elements are provided, and the laser light source, the first optical element, and the second optical element are symmetrically arranged at positions opposite to each other with the irradiation target in between. A galvano scanner and an f−θ lens may be arranged between the second optical element and the object to be irradiated.

Further, in the above-mentioned features, even if the first and second reflecting means for reflecting the laser light emitted from the second optical element and the condensing means for condensing the laser light reflected by these reflecting means are provided. Often, two sets of the galvano scanner and the f-θ lens are provided, and the pair of the galvano scanner and the f-θ lens are symmetrically arranged between the second optical element and the irradiation target object. You may.

According to the present invention, by rotating an optical component at a variable speed, it becomes possible to immediately change the position of a laser beam emitted from a laser light source to a desired position such as a wafer or a bearing component and irradiate the semiconductor. Products suitable for mass production such as wafers and radial sliding bearings can be processed with high accuracy and in a short time. In particular, in the case of a semiconductor wafer, the front surface or the back surface of the wafer can be flattened and uniformly annealed quickly. In the case of small bearing parts, the inner surface can be processed into a desired shape in a short time.

It is a schematic diagram of one Example of the laser processing apparatus which concerns on this invention. It is a figure explaining the operation of the optical element included in the laser processing apparatus shown in FIG. 1. It is a block diagram of the laser processing apparatus shown in FIG. It is a schematic diagram of another Example of the laser processing apparatus which concerns on this invention. It is a figure explaining the processing example by the laser processing apparatus shown in FIG. It is a block diagram of the laser processing apparatus shown in FIG.

Hereinafter, some examples of the laser processing apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic front view of an embodiment of the laser processing apparatus 100. The laser processing apparatus 100 of this embodiment is used in combination with, for example, a wafer chamfering apparatus including an XYZ-θ table (not shown).

The semiconductor wafer W is sucked downward to the suction unit 240 of a processing device such as a wafer chamfering device with the circuit forming surface facing downward. The main parts of the laser processing apparatus 100 having substantially the same configuration are arranged above and below the semiconductor wafer W portion with the semiconductor wafer W portion interposed therebetween. That is, the laser light source 210 is fixedly arranged at the uppermost portion directly above the wafer W as the main portion of the laser processing apparatus 100 located on the upper side. The laser light source 210 emits a pulse laser, and the intensity, timing, and the like of the emitted laser light 110 are controlled by the laser light source control unit 212.

Below the laser light source 210, a beam expander 222 is fixedly arranged so that the laser light 110 emitted from the laser light source 210 has a predetermined intensity and a predetermined spot diameter. Below the beam expander 222, an optical element (moving portion) 220 having a plurality of prisms is arranged.

The optical element 220 is a component for determining an irradiation position on a wafer W, which is a work, at a specific position, and includes two types of wedge prisms 224 and 226 having a shape obtained by cutting a cylinder diagonally. The wedge prism 224 located on the upper side is a first optical element, and is used for adjusting the irradiation angle as described in detail later, and has an upper prism (fixed prism) 224a spaced apart from each other in the optical axis direction. The distance between the upper prism 224a and the lower prism 224b including the lower prism 224b is variably controlled by the translation control unit 232. In the upper wedge prism 224, the translation control unit 232 changes the optical axis distance between the upper prism 224a and the lower prism 224b, so that the position on the wafer W is perpendicular to the optical axis of the laser beam 110, that is, the radial position. Can be changed.

The wedge prism 226 located on the lower side, which is the second optical element, is for the radius of the rotation operation circle whose details will be described later, and is the upper prism (fixed prism) 226a and the lower prism (fixed prism) 226a which are spaced apart from each other in the optical axis direction. Includes prism 226b. The distance between the upper prism 226a and the lower prism 226b is variably controlled by the translation control unit 234, and the rotation of the upper prism 226a and the lower prism 226b is controlled by the rotation control unit 236 about the optical axis. The rotation control unit 236 rotationally drives the upper prism 226a and the lower prism 226b to control the irradiation position of the laser beam in the circumferential direction of the wafer W. That is, when irradiating the wafer W surface in a circular shape, the wedge prism 226 may be continuously rotated for one round or more. The translation control unit 232 of the upper wedge prism 224, the translation control unit 234 of the lower wedge prism 226, and the rotation control unit 236 constitute an optical element control unit 230.

The laser light source 260, the beam expander 272, and the optical element 270, which have substantially the same configuration as the laser light source 210, the beam expander 222, and the optical element 220, are arranged symmetrically below the wafer W with the wafer W in between. .. That is, a beam expander 272 that diffuses the laser beam 110 is arranged above the laser light source 260, and an optical element (moving portion) 270 having a plurality of prisms is arranged above the beam expander 272. The laser light source 260 is a light source that emits a pulsed laser, and the intensity, timing, and the like of the emitted laser light 110 are controlled by the laser light source control unit 262.

The optical element 270 includes two types of wedge prisms 274 and 276 having a shape obtained by cutting a cylinder diagonally, and the lower wedge prism 274 includes an upper prism 274b and a lower prism (fixed prism) spaced in the optical axis direction. ) 274a, and the distance between the upper prism 274b and the lower prism (fixed prism) 274a is variably controlled by the translation control unit 282.

The wedge prism 276 located on the upper side includes an upper prism 276b and a lower prism 276a spaced apart from each other in the optical axis direction, and the distance between them is variably controlled by the translation control unit 284 and their rotation is rotated. The rotation is controlled by the control unit 286. The translation control unit 282 of the lower wedge prism 274, the translation control unit 284 of the upper wedge prism 276, and the rotation control unit 286 constitute an optical element control unit 230. By controlling the prisms 274a to 276b constituting the optical element 270, the optical element control unit 230 uniformly irradiates the laser beam concentrically from the inner diameter side to the outer diameter side of the wafer W or vice versa. Will be possible.

Next, an optical element that guides the laser light 110 emitted from the laser light source 210 at the top of the laser processing device 100 to the back surface side of the wafer W around the suction unit 240 of the processing device that sucks and holds the wafer W. Also, optical elements that guide the laser beam 110 emitted from the lower laser light source 260 to the back surface side of the wafer W are arranged. These optical elements form the optical element 250.

Specifically, the cylindrical portion 254a of the reflective mirror 254 is arranged at a radial interval from the outer peripheral edge of the wafer W, and the cone of the reflective mirror 254 having a truncated cone shape is arranged at the bottom end of the cylindrical portion 254a. The part 254b is connected. Further, the condenser lens 252 is arranged in a ring shape at a position corresponding to the conical portion 254b and at a position spaced downward from the wafer W.

On the other hand, in order to collect the laser light 110 emitted from the lower laser light source 260, the f-θ lens 256 is located at the opening position of the reflection mirror at a position corresponding to the center position of the wafer W. Galvano scanners 258 are arranged below the θ lens 256 at intervals. The rotation and the like of the f-θ lens 256 and the galvano scanner 258 are driven and controlled by the drive control unit 288. By arranging the optical elements in this way, the upper laser light source 210 is suitable for irradiating the outer diameter side of the wafer W mainly, and the lower laser light source 260 is suitable for irradiating the center side of the wafer W with laser light. Therefore, when the wafer diameter is small, the laser processing apparatus 100 may only have the lower configuration.

The laser light sources 210 and 260 are arranged one above the other to irradiate the center side and the outer peripheral side of the wafer W, respectively, which enables simultaneous processing, shortens the laser irradiation time, and is formed by a wedge prism. This is because the deflection angle to be obtained cannot be theoretically increased. This deflection angle is usually within a few degrees, at most 10 degrees.

The main optical elements included in the laser processing apparatus 100 shown in FIG. 1 will be described with reference to FIG. 2A and 2B are diagrams for explaining the operation and operation of the main optical element, and FIG. 2A is a schematic diagram for explaining the operation of the wedge prisms 224 and 226 included in the optical element 220, FIG. 2B. Is a schematic diagram for explaining the operation of the reflection mirror 254, FIG. 2 (c) is a schematic diagram for explaining the operation of the condenser lens 252, and FIG. 2 (e) shows the condenser lens 252. 2 (d) is a schematic view for explaining how to obtain scanning loci of concentric circles on the wafer W.

As described above, the optical element 220 comprises two sets of wedge prisms 224, 226, each wedge prism comprising two prisms 224a, 224b; 226a, 226b spaced apart from each other. The relative positions of the prisms 224a to 226b are variable, and although not shown in FIG. 2A, the positions are controlled by the optical element control unit 230. That is, in the upper wedge prism 224, by fixing the upper prism 224a and moving the lower prism 224b, the relative positions of the upper prisms 224 are variable in the optical axis direction.

For example, a lower prism 224b from one position causes a translational movement T _RL1 in the optical axis direction with respect to the upper prism 224a to that shown by the broken line indicated by the solid line, i.e. away. Then, the laser beam 110 that has reached the optical element 220 from the laser light source 210 via the beam expander 222 is radially from the one-dot chain line locus 112a located on the central side of the wedge prism 224 to the broken line locus 112b located on the outer peripheral side. Change the position (position in the direction perpendicular to the optical axis).

The lower the wedge prism 226 upper wedge prism 224 in the same manner as in the upper and lower prisms 226a, at least one of 226b, varying the gap between them an upper prism 226b by translating movement _{T RL2} in this example , The change in the radial position of the laser beam is magnified. Then, the upper and lower prism 226a, the 226b, is rotated moving R _OT1 together at high speed by a motor (not shown) or the like, the irradiation trajectory of a laser beam on the wafer W surface, to form a concentric track. That is, the loci 112a and 112b of the laser light whose radial positions are changed by the upper wedge prism 224 are the circular irradiation light loci shown by the broken line from the circular irradiation light locus 114a shown by the alternate long and short dash line on the wafer W surface, respectively. It changes to 114b.

Therefore, the surface of the wafer W is formed by changing the relative distances of the prisms 224a to 226b of the upper and lower wedge prisms 224 and 226 in the optical axis direction and simultaneously rotating the prisms 226a and 226b of the lower wedge prism 226. It is possible to irradiate the laser beam all over the top. As shown in FIG. 1, since the back surface of the wafer W of this embodiment is processed with the back surface facing down, the laser light from the laser light source 210 arranged on the upper surface cannot be used as it is. Therefore, the reflection mirror 254 is used.

As shown in FIG. 2B, the reflection mirror 254 has a truncated cone having an opening 254c at the center connected to a cylindrical portion 254a having a diameter larger than the diameter of the wafer W and a lower end portion of the cylindrical portion 254a. It comprises a conical portion 254b in shape. The portion of the reflection mirror 254 that acts as a mirror is the inner surface side of each of these portions 254a and 254b. The laser beam 116 emitted from the optical element 220 reaches the reflection mirror 254 at an angle with the optical axis, first collides with the inner surface of the cylindrical portion 254a of the reflection mirror 254, becomes reflected light 116a, and becomes a conical portion 254b. Collide with the inclined surface of. Further, the reflected light 116b is formed. The reflected light 116b is a laser beam oriented in the optical axis direction, which is located inside the outer diameter edge position of the wafer W in the radial direction and outside the opening 254c of the reflection mirror 254. The reflection mirror 254 is set. As a result, the laser beam can be evenly applied to the wafer W from the outlet portion 254d of the reflection mirror 254 from the position of the wafer W corresponding to the opening 254c of the reflection mirror 254 to the outer diameter position of the wafer W.

The reflected light 116b may also include laser light diffusely reflected by the two reflecting surfaces 254a and 254b. Therefore, in order to make the laser beam more parallel to the optical axis, the wafer is spaced from the wafer W in the vicinity of the set position of the wafer W, and at least from the position of the wafer W corresponding to the opening 254c of the reflection mirror 254. A ring-shaped condenser lens 252 having a width up to the outer diameter position of W is provided. As shown in FIG. 2C, the condenser lens 252 is composed of a large number of microlenses 252a arranged concentrically, and a large number of microlenses 252a are arranged adjacent to each other even on the same circumference. The laser light emitted from the laser light source 210 is condensed by a condenser lens 252 made of a microlens 252a via an optical element and a reflection mirror (not shown) to form an irradiation portion having a predetermined spot diameter on the wafer W. .. FIG. 2D shows that the laser beams 118a and 118b formed through the condenser lens 252 and parallel to the optical axis form concentric irradiation light trajectories 114a and 114b on the W surface of the wafer.

Next, the operation of the laser processing apparatus 100 configured as described above will be described with reference to FIGS. 1 and 3. FIG. 3 is a block diagram showing an apparatus configuration of the laser processing apparatus 100. In the laser processing apparatus 100, the back surface of the wafer W on which the semiconductor circuit is formed is annealed after the circuit is formed in order to remove residual stress and flatten the wafer W surface. Until now, flattening has been carried out by machining, mainly grinding and chemical treatment, but incidental treatment such as residual stress during processing and waste liquid treatment was required. In this embodiment, by annealing the back surface of the wafer W with laser irradiation, it is possible to prevent cracks and chips from occurring in the next thinning process, improve the uniformity of processing, and enable high-throughput processing. become.

Each control unit that drives and controls each optical element of the laser machining apparatus 100 is generally integrated as a laser machining control apparatus 200 and arranged in a housing. First, the wafer W to be machined is conveyed to the suction unit 240 by using the drive control unit 150 of the processing device such as a grinding device, and the wafer W is sucked with the back surface facing down. Next, the laser light 110 is irradiated downward from the upper laser light source 210, and the laser light 110 is irradiated upward from the lower laser light source 260. At this time, the output timing and intensity of the laser beam are controlled by the laser light source control units 212 and 262. In the initial state, the upper laser beam 110 that has passed through the optical element illuminates the outer peripheral side region of the wafer W, and the lower laser beam 110 that has passed through the optical element illuminates the central region of the wafer W.

For the laser beam 110 emitted from the upper laser light source 210, the optical element control unit 230 adjusts and controls the wedge prisms 224 and 226 included in the optical element 220, and the incident angle which is the incident deflection angle to the wedge prism 226. And, the position in the radial direction (rotational scanning circle radius) of the laser beam emitted from the wedge prism 226 is determined. As a result, the position of the laser beam incident on the reflection mirror 254 is determined. The laser beam deflected by the reflection mirror 254 is condensed by the condenser lens 252 corresponding to the wafer W shape, and is irradiated as irradiation light substantially perpendicular to the wafer surface. After the laser irradiation at a certain radius is completed, the irradiation position is changed to the next radius position. Therefore, the optical element control unit 230 adjusts and controls the optical axis direction positions of the prisms 224a to 226b constituting the wedge prisms 224 and 226 of the optical element 220. The amount of change in the position in the optical axis direction finally corresponds to the radial pitch of the laser irradiation position on the wafer W. By repeating the radial movement of the laser irradiation position, that is, the movement in the optical axis direction of each prism 224a to 226b, the laser irradiation of the entire outer peripheral side region of the wafer W is completed.

On the other hand, with respect to the laser light 110 emitted from the lower laser light source 260, the optical element control unit 280 adjusts and controls the wedge prisms 274 and 276 included in the optical element 270 to determine the angle of incidence on the wedge prism 276. , Determines the radial position (rotational scanning circle radius) of the laser beam emitted from the wedge prism 276. Next, the optical element control unit 280 drives and controls the galvano scanner 258 and the f-θ lens 256 to collect the laser light passing through the optical element 270, and the laser light is substantially perpendicular to the central region of the wafer W. Irradiate. The irradiation position of the lower laser beam 110 is also changed to the next radius position after the laser irradiation at a certain radius is completed. Therefore, the optical element control unit 280 adjusts and controls the optical axis direction positions of the prisms 274a to 276b constituting the wedge prisms 274 and 276. By repeating the radial movement of the laser irradiation position, that is, the movement in the optical axis direction of each prism 274a to 276b, the laser irradiation of the entire central region of the wafer W is completed. As the lower condensing means, a condensing lens such as a condensing lens 252 may be used instead of the galvano scanner 258 and the f-θ lens 256. In that case, the shape of the condenser lens is a disk shape corresponding to the central portion of the wafer W.

In the above operation, the wedge prisms 226 and 276 are rotationally driven and controlled at high speed. As a result, the laser light 110 emitted from the upper laser light source 210 irradiates the portion of the wafer W at a predetermined radial position concentrically with the laser light, and the laser light emitted from the lower laser light source 260. The 110 can concentrically irradiate a portion of the wafer W at a predetermined radial position with a laser. As is clear from the above, when the diameter of the wafer W is small, the amount of processing per wafer W is small, so laser processing is performed using only the laser light source 260 arranged on the lower side in FIG. You can also do it.

As described above, according to the present embodiment, it is possible to perform uniform processing with high accuracy on the entire flat surface of the wafer. As a result, the quality of the wafer can be maintained at a high quality. In addition, since it is processed under atmospheric pressure and does not require a special chemical solution, there is no need for waste liquid treatment or consumables, and it can be processed cleanly at low cost.

Other examples of the laser processing apparatus 102 according to the present invention will be described with reference to FIGS. 4 to 6. 4 is a schematic diagram of the laser machining apparatus 102 corresponding to FIG. 1, FIG. 5 is a diagram showing some actual examples of machining patterns, and FIG. 6 is a device configuration of the laser machining apparatus 102 corresponding to FIG. It is a block diagram which shows. A processing target workpiece W _K is, for example, a radial sliding bearing having a sleeve-like inner circumferential surface, a case of forming, for example, spiral grooves on the inner peripheral surface of the radial sliding bearing. The same parts as those in the embodiments shown in FIGS. 1 to 3 are given the same number by changing the number in the 100th place. That is, reference numerals 210 and 310 indicate laser light sources as well. Since some of the parts are the same as those in the embodiment of FIG. 1, the description thereof will be omitted to avoid complexity.

Since the workpiece W _K is a cylindrical configuration, place the cylinder axis in the vertical direction, the holding portion 340 of the processing apparatus the outer peripheral portion is fixed and held. Thus, from the laser light source 310, 360 arranged above and below the workpiece W _K, becomes the laser beam 110 directly be radiated to the same position of the inner surface of the workpiece W _K, the semiconductor wafer in the embodiment in which this point is shown in FIG. 1 It is different from the processing of W. Further, due to this difference, the reflection mirror is not required on the upper side of the laser processing apparatus 102. The condensing means is composed of an f-θ lens 352, a galvano scanner 354, and a drive control unit 338 thereof instead of the condensing lens. Similarly, on the lower side, the condensing means includes an f-θ lens 392, a galvano scanner 394, and a drive control unit 388 thereof. Lower portion from the work W _K of the laser processing apparatus 102, which is configured in the upper portion and symmetrical with respect to the workpiece W _K, the description thereof is omitted.

Since spiral grooving the work _{W K,} the holding portion 340 of the processing apparatus, the translational control unit 162 and the rotation control section 164 the drive control section 160 (see FIG. 4) is provided with a processing device, the upper and lower optical element 320, It is controlled to move up and down in synchronization with the rotation of the wedge prism 326 and 376 included in the 390. Depending on the synchronization method, a laser machining state of the workpiece W _K is different. 5 (a) is a case of not vertically moving the holding portion 340 in the laser processing, i.e., the laser processing in the workpiece W _K is stationary, upward shown in FIG. 4, the lower laser light source 310, 360 Laser beams 122 and 124 are emitted from the upper and lower openings 132 through the upper and lower openings 132. The irradiation points of the work _KK inner wall 134 are the same. By rotating the wedge prism 326,376, the irradiation point of the workpiece _{W K} inner wall 134 is moved, the irradiation trajectory 142 is formed. By adjusting the laser intensity, a desired circumferential groove is formed in the irradiation locus 142 portion.

FIG. 5 (b), and only the irradiation of the laser beam from one laser light source 310, and the workpiece W _K is translating movement T _RL3 downward in synchronization with the change in the circumferential direction irradiation position of the laser beam. Combined with the course of the processing state, the lower side of the workpiece W _K by the laser beam 122b is early in processing are processed, the workpiece W _K is moved downward over time, the workpiece W _K by the laser beam 122a The upper part of is processed. As a result, a spiral irradiation locus 144 is obtained, and by adjusting and controlling the intensity of the laser beam, a spiral groove is formed in the irradiation locus 144 portion.

FIG. 5C is an example in which the laser beams 124a and 124b from the laser light source 360 are added to the embodiment shown in FIG. 5B. Workpiece W _K is translational motion T _RL4 in synchronization with the rotation of the upper and lower laser beam. As a result, irradiation trajectories 144 and 146 of two spirals are obtained. The irradiation trajectories 144 and 146 of these two spirals are the irradiation trajectories 144 and 146 of the intersecting spirals, and the crossing spiral groove is formed by adjusting and controlling the laser beam intensity.

5 (d) is kept fixed holding the work W _K, intended to irradiate a laser from the top and bottom of the laser light source, the configuration and operation of FIGS. 5 (a) embodiment shown the laser processing apparatus is the same. However, the laser processing content is different from the embodiment shown in FIG. 5 (a). Although the embodiments so far was to form a groove in a cylindrical inner surface, it has a ring-like or sheet-like deposits 136 on the inner wall 134 of the cylindrical workpiece W _K is laser welding or welding in this example .. By making the adherend, for example, a minute protrusion, the opposite effect of the groove can be obtained.

Each example shown in FIG. 5 is particularly suitable when the opening diameter is small and it is difficult to insert the processing tool, or when the processing tool is too small to maintain the strength. For example, it is suitable for processing bearings for high-speed printers and radial bearings for micro turbines.

As described above, according to the above embodiment, it is possible to irradiate the processed portion with a laser beam at high speed, and the processing time can be shortened as compared with the conventional method. In addition, since processing is possible within the reach of the laser beam, it is possible to perform processing such as grooving inside the small hole, which was difficult to process, and welding of minute parts to the inside of the small hole.

100, 102 ... Laser processing apparatus, 110 ... Laser light, 112a, 112b ... Laser light locus, 114a, 114b ... Irradiation light locus, 116 ... Laser light, 116a, 116b ... Reflected light, 118a, 118b ... (Parallel to the optical axis) N) Laser light, 122, 122a, 122b ... (Top) Laser light, 124, 124a, 124b ... (Bottom) Laser light, 132 ... Opening, 134 ... Inner wall, 136 ... Adhesion, 142, 144, 146 ... Irradiation Trajectory, 150, 160 ... Drive control unit (of the processing device), 162 ... Translation control unit, 164 ... Rotation control unit, 200 ... Laser processing control device, 210 ... Laser light source, 212 ... Laser light source control unit, 220 ... Optical element , 222 ... Beam expander, 224 ... (for adjusting irradiation angle) Wedge prism, 224a ... Upper prism (fixed prism), 224b ... Lower prism, 226 ... (for rotation operation circle) Wedge prism, 226a ... Upper prism (fixed) Prism), 226b ... Lower prism, 230 ... Optical element control unit, 232 ... Translation control unit, 234 ... Translation control unit, 236 ... Rotation control unit, 240 ... Suction unit (of processing equipment), 250 ... Optical element, 252 ... Condensing lens, 252a ... Micro lens, 254 ... Reflective mirror, 254a ... Reflective surface (cylindrical portion), 254b ... Reflective surface (conical portion), 254c ... Opening, 256 ... f-θ lens, 258 ... Galvano scanner, 260 ... Laser light source, 262 ... Laser light source control unit, 270 ... Optical element (moving part), 272 ... Beam expander, 274 ... Wedge prism, 274a ... Lower prism, 274b ... Upper prism, 276 ... Wedge prism, 276a ... Lower prism, 276b ... Upper prism, 280 ... Optical element control unit, 282, 284 ... Translation control unit, 286 ... Rotation control unit, 288 ... Drive control unit, 300 ... Optical element control unit, 310 ... Laser light source, 312 ... Laser light source control unit , 320 ... Optical element (moving part), 322 ... Beam expander, 324 ... (for adjusting irradiation angle) Wedge prism, 324a ... Upper prism (fixed prism), 324b ... Lower prism, 326 ... (for rotation operation circle) Wedge Prism, 326a ... Upper prism (fixed prism), 326b ... Lower prism, 330 ... Optical element control unit, 332, 334 ... Translation control unit, 336 ... Rotation control unit, 338 ... Drive control unit, 340 ... (Processing device ) Holding part, 350 ... Optical element, 352 ... f-θ lens, 354 ... Galvano scanner, 360 ... Laser light source, 362 ... Ray The light source control unit, 370 ... optical element, 372 ... beam expander, 374 ... (for adjusting irradiation angle) wedge prism, 374a ... lower prism (fixed prism), 374b ... upper prism, 376 ... (for rotation operation circle) wedge Prism, 376a ... Lower prism (fixed prism), 376b ... Upper prism, 380 ... Optical element control unit, 382, 384 ... Translation control unit, 386 ... Rotation control unit, 388 ... Drive control unit, 390 ... Optical element, 392 ... f-theta lens, 394 ... optical scanner, _{R OT1 ...} rotational _{movement, T RL1, T RL2, T} RL3, T RL4 ... translational movement, W ... wafer, W K _... work

Claims (7)

In a laser processing device that irradiates one surface of an object to be irradiated with laser light and performs laser processing in a rotationally symmetrical manner.
The irradiation of a laser light source capable of emitting laser light, a first optical element for changing the laser light emitted from the laser light source in a direction different from the emission direction, and a laser light emitted from the first optical element. A second optical element including a mechanism for scanning and controlling the object in the circumferential direction is provided .
A collection of reflecting means composed of a cylindrical reflecting mirror for reflecting the laser light emitted from the second optical element and a truncated cone-shaped reflecting mirror, and a collection of the laser light reflected by the reflecting means. Provided with optical means,
A laser processing device characterized by this. The first and second optical elements are wedge prisms including a fixed wedge prism and a translational control mechanism and / or rotation control mechanism, respectively, the irradiation target is a semiconductor wafer, and the one surface is the semiconductor. A claim which is either a surface on which a circuit of a wafer is formed or an opposite surface thereof, and irradiates the object to be irradiated with a laser beam emitted from the laser light source to anneal the one surface. The laser processing apparatus according to 1. The laser processing apparatus according to claim 2, wherein a galvano scanner and an f−θ lens are arranged between the second optical element and the irradiation target object. The laser light source, the first optical element, and the second optical element are included in two sets, and the laser light source and the first optical element are located on opposite sides of the irradiation target. The claim is characterized in that the set of the second optical element is arranged symmetrically, and the galvano scanner and the f−θ lens are arranged between the second optical element and the irradiation target object. The laser processing apparatus according to 1 or 2. The laser processing apparatus according to claim 2, wherein the one surface is the back surface side on the side where the laser light source is arranged. The cylindrical reflection mirror is arranged at a radial distance from the outer peripheral edge of the object to be irradiated, and the truncated cone-shaped reflection mirror is connected to the bottom end of the cylindrical reflection mirror. The laser processing apparatus according to claim 5. The laser processing apparatus according to claim 5 or 6, wherein the condensing means is a condensing lens composed of a large number of microlenses arranged concentrically.

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