KR101530390B1 - Laser machining apparatus - Google Patents

Abstract

An object of the present invention is to provide a laser processing apparatus capable of forming a laser processing groove having a desired width without peeling the laminate from a semiconductor substrate.

A laser beam irradiating means for irradiating the workpiece held on the chuck table with a laser beam, a processing transfer means for relatively moving the chuck table in the X axis direction, and an indexing transfer means for relatively moving the chuck table in the Y axis direction And a condensing lens for condensing the laser beam emitted from the laser beam emitting means and irradiating the workpiece held on the chuck table with the laser beam emitting means for emitting the laser beam. The laser beam irradiating means includes an energy distribution correcting means for forming an edge portion of the gauss of the energy distribution in the Y axis direction of the laser beam emitted from the laser beam emitting means and arranged between the laser beam emitting means and the condensing lens, And energy density adjusting means for adjusting the energy density in the X-axis direction of the laser beam.

Description

[0001] LASER MACHINING APPARATUS [0002]

The present invention relates to a laser machining apparatus for forming a laser machining groove by irradiating a laser beam along a street formed on a surface of a workpiece such as a semiconductor wafer.

As is known to those skilled in the art, in a semiconductor device manufacturing process, a semiconductor wafer is formed in which a plurality of devices such as ICs and LSIs are formed in a matrix by a laminate in which an insulating film and a functional film are laminated on the surface of a semiconductor substrate such as silicon. The semiconductor wafer thus formed is partitioned by a line to be divided, which is called a street, and the device is manufactured by dividing the device along the street.

Such division of the wafer along the streets is generally performed by a cutting apparatus. As a method of dividing the wafer, there is a method in which a condensing point is set inward from the backside of the wafer and a pulsed laser beam of a wavelength having a transmittance to the wafer is irradiated to continuously form a deformed layer along the streets in the wafer, A method of fracturing and dividing the wafer by applying an external force along a street whose strength has been lowered by the formation of the wafer is proposed.

In recent years, in order to improve the processing capability of semiconductor chips such as ICs and LSIs, an inorganic film such as SiOF or BSG (SiOB), an organic film such as a polyimide film or a parylene film, A semiconductor wafer in which a semiconductor chip is formed by a laminate in which a low dielectric constant insulating film (low-k film) composed of a base film and a functional film forming a circuit are laminated is put to practical use.

Since the above-described Low-k film is different from the material of the wafer, it is difficult to cut simultaneously with cutting blades. That is, since the Low-k film is very weak like mica, if the cutting blade cuts along the street, the problem that the Low-k film is peeled from the semiconductor substrate and the peeling reaches the circuit and gives a fatal damage to the device have.

In order to solve the above problem, a wafer dividing method in which a portion of a laminate in which a street is formed is removed by irradiating a pulsed laser beam along a street of the wafer, and a cutting blade is placed on the removed region to cut the wafer along the street (See, for example, Patent Document 1).

[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2006-190779

It has been found that when the laminate on which the streets of the wafer are formed is irradiated with a laser beam to remove a part of the laminate, the laminate is peeled off from the semiconductor substrate and the quality of the device is deteriorated. The inventors of the present application have repeatedly studied the reason why the laminate is peeled off from the semiconductor substrate and the reason is that the energy distribution of the laser beam is in a Gaussian distribution and the Gaussian distribution which is insufficient to remove the laminate in the width direction of the street And the like.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and it is a main object of the present invention to provide a laser processing apparatus capable of forming a laser processing groove with a desired width without peeling the laminate from the semiconductor substrate.

According to an aspect of the present invention, there is provided a chuck table comprising: a chuck table for holding a workpiece; laser beam irradiation means for irradiating a laser beam to a workpiece held on the chuck table; (X-axis direction) of the chuck table and the laser beam irradiating means in the direction of the indexing conveyance (Y-axis direction) orthogonal to the processing transfer direction (X-axis direction) The laser beam emitting means for emitting a laser beam and the laser beam emitted from the laser beam emitting means are condensed to irradiate the tangent tangent held on the chuck table, The laser processing apparatus comprising:

The laser beam irradiating means forms an edge portion of a gaussian of the energy distribution in the Y axis direction of the laser beam emitted from the laser beam oscillation means and arranged between the laser beam oscillation means and the condenser lens in a vertical distribution And an energy density adjusting means for adjusting the energy density in the X-axis direction of the laser beam whose energy distribution is modified by the energy distribution modifying means.

The energy distribution modifying means is composed of a mask member having a slit for regulating passage of the laser beam emitted from the laser beam generating means in the Y-axis direction.

Further, the energy density adjusting means is constituted by a cylindrical lens.

The condensing lens is configured such that a laser beam whose energy density in the X axis direction is adjusted by the energy density adjusting means is formed on the upper surface of the workpiece held on the chuck table in the Y axis direction and held And is condensed on the upper surface of the processed workpiece.

According to the laser machining apparatus of the present invention, the laser beam irradiation means is disposed between the laser beam emitting means and the condenser lens, and the edge portion of the gaussian of the energy distribution in the Y-axis direction of the laser beam emitted from the laser beam emitting means, And the energy density adjusting means for adjusting the energy density in the X-axis direction of the laser beam whose energy distribution is modified by the energy distribution correcting means. Therefore, Since the laser beam is formed in such a manner that both sides of the laser beam in the Y axis direction are perpendicular to the processing surface and the energy density is high so that the laser processing groove is formed so that the outer side is perpendicular to the processing surface, Do not. In addition, since a long spot can be formed in the Y-axis direction, laser machining grooves having a predetermined width can be formed in the streets of the wafer as the workpiece, thereby improving productivity.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments of a laser machining apparatus constructed in accordance with the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 shows a perspective view of a laser machining apparatus constructed in accordance with the present invention. The laser machining apparatus shown in Fig. 1 is provided with a stationary base 2 and a chuck table 2 arranged movably in the feed direction (X-axis direction) indicated by an arrow X in the stationary base 2 and holding the workpiece A laser beam irradiation unit support mechanism 4 arranged so as to be movable in an indexing direction (Y axis direction) indicated by an arrow Y perpendicular to the direction indicated by the arrow X in the stationary base 2 And a laser beam irradiation unit 5 which is arranged so as to be movable in the focus position adjustment direction (Z-axis direction) indicated by an arrow Z in the laser beam irradiation unit support mechanism 4.

The chuck table mechanism 3 includes a pair of guide rails 31 and 31 arranged on the stop base 2 in parallel along the X axis direction and a pair of guide rails 31 and 31 on the guide rails 31 and 31, A second sliding block 33 disposed so as to be movable in a direction indicated by arrow Y on the first sliding block 32, and a second sliding block 32 disposed on the first sliding block 32, 33, a support table 35 supported by a cylindrical member 34, and a chuck table 36 as a workpiece holding means. The chuck table 36 is formed of a porous material and has a workpiece holding surface 361. The workpiece, for example, a disk-shaped semiconductor wafer is held on a chuck table 36 by suction means have. Further, the chuck table 36 is rotated by a pulse motor (not shown) disposed in the cylindrical member 34. The chuck table 36 is also provided with a clamp 362 for fixing an annular frame for supporting a semiconductor wafer to be described later.

The first sliding block 32 is formed with a pair of to-be-guided grooves 321 and 321 which are fitted on the lower surface thereof with the pair of guide rails 31 and 31. On the upper surface thereof, A pair of guide rails 322 and 322 formed parallel to each other are provided. The first sliding block 32 constructed as described above is guided along the pair of guide rails 31 and 31 by engaging a pair of guide rails 31 and 31 in the guided grooves 321 and 321, As shown in FIG. The chuck table mechanism 3 in the illustrated embodiment is provided with a processing and transfer means 37 for moving the first sliding block 32 along the pair of guide rails 31 and 31 in the X axis direction . The processing and transfer means 37 includes a male thread rod 371 disposed in parallel between the pair of guide rails 31 and 31 and a pulse motor 372 for rotationally driving the male screw rod 371 And a driving source. One end of the male screw rod 371 is rotatably supported by a bearing block 373 fixed to the stationary base 2 and the other end of the male screw rod 371 is electrically connected to the output shaft of the pulse motor 372. The male screw rod 371 is screwed into a female screw hole formed in a female screw block (not shown) protruding from a central lower surface of the first sliding block 32. The first sliding block 32 is moved along the guide rails 31 and 31 in the machining feed direction indicated by the arrow X Direction.

The second sliding block 33 includes a pair of to-be-guided grooves 331 and 331 fitted on a lower surface thereof with a pair of guide rails 322 and 322 provided on the upper surface of the first sliding block 32, And is configured so as to be movable in the Y-axis direction by fitting the guided grooves 331 and 331 into the pair of guide rails 322 and 322. The chuck table mechanism 3 in the illustrated embodiment is configured to move the second sliding block 33 along the pair of guide rails 322 and 322 provided on the first sliding block 32 in the Y axis direction And a first indexing conveying means (38). The first indexing conveying means 38 includes a male screw rod 381 disposed in parallel between the pair of guide rails 322 and 322 and a pulse motor 382 for rotationally driving the male screw rod 381 ) And the like. One end of the male screw rod 381 is rotatably supported by a bearing block 383 fixed to the upper surface of the first sliding block 32 and the other end of the male screw rod 381 is electrically connected to the output shaft of the pulse motor 382 have. The male screw rod 381 is screwed to a female screw hole formed in a female screw block (not shown) projecting from a central lower surface of the second sliding block 33. The second sliding block 33 moves along the guide rails 322 and 322 in the indexing conveying direction indicated by the arrow Y Y axis direction).

The laser beam irradiation unit support mechanism 4 includes a pair of guide rails 41 and 41 arranged in parallel on the stop base 2 along the Y axis direction and a pair of guide rails 41 and 41 on the guide rails 41 and 41, And a movable support base 42 which is arranged so as to be movable in a direction. The movable support base 42 is composed of a movable support portion 421 movably arranged on the guide rails 41 and 41 and a mounting portion 422 attached to the movable support portion 421. The mounting portion 422 has a pair of guide rails 423 and 423 extending parallel to the Z-axis direction on one side surface thereof. The laser beam irradiation unit support mechanism 4 in the illustrated embodiment includes a second indexing feed means 43 for moving the movable support base 42 along the pair of guide rails 41 and 41 in the Y- . The second indexing conveying means 43 includes a male screw rod 431 disposed in parallel between the pair of guide rails 41 and 41 and a pulse motor 432 for rotationally driving the male screw rod 431, And the like. One end of the male screw rod 431 is rotatably supported on a bearing block (not shown) fixed to the stationary base 2, and the other end is electrically connected to the output shaft of the pulse motor 432. The male screw rod 431 is screwed to a female screw hole formed in a female screw block (not shown) provided on a central lower surface of the movable support portion 421 constituting the movable support base 42. The movable support base 42 is moved in the indexing conveying direction Y indicated by the arrow Y along the guide rails 41 and 41 by driving the male screw rod 431 in the forward rotation and the reverse rotation by the pulse motor 432 Axis direction).

The laser beam irradiation unit 5 in the illustrated embodiment includes a unit holder 51 and a laser beam irradiating means 6 attached to the unit holder 51. [ The unit holder 51 is formed with a pair of guided grooves 511 and 511 slidably fitted in a pair of guide rails 423 and 423 provided on the mounting portion 422, The grooves 511 and 511 are fitted to the guide rails 423 and 423 so as to be supported to be movable in the Z-axis direction.

The illustrated laser beam irradiating means 6 includes a cylindrical casing 61 fixed to the unit holder 51 and extending substantially horizontally. 2, a pulse laser beam oscillation means 62 and an edge portion of a gaussian of the energy distribution in the Y-axis direction of the pulsed laser beam oscillated from the pulsed laser beam oscillation means 62 are disposed in the casing 61 And an energy density adjusting means 64 for adjusting the energy density in the X-axis direction of the laser beam whose energy distribution is modified by the energy distribution modifying means 63 Respectively.

The pulse laser beam oscillation means 62 is constituted by a pulse laser beam oscillator 621 composed of a YAG laser oscillator or a YVO4 laser oscillator and a repetition frequency setting means 622 attached thereto, For example, a pulsed laser beam LB1 having a diameter of 4 mm. The energy distribution in the Y-axis direction of the pulsed laser beam LB1 oscillated from the pulsed laser beam oscillation means 62 is a Gaussian distribution ED1a as shown in Fig. The energy distribution in the X-axis direction of the pulsed laser beam LB1 oscillated from the pulsed laser beam oscillation means 62 is also a Gaussian distribution ED1b which is the same as the Gaussian distribution ED1a as shown in Fig.

The energy distribution modifying means 63 is composed of a mask member 631 in which slits 631a for regulating the passage of both side portions of the pulsed laser beam LB1 in the Y-axis direction are formed in the illustrated embodiment. The opening width A of the slit 631a in the Y-axis direction is set to, for example, 2 mm in the illustrated embodiment. The opening width B of the slit 631a in the X-axis direction is set to 4 mm or more in the illustrated embodiment. 2, the energy distribution of the pulsed laser beam LB2 passing through the slit 631a of the mask member 631 in the Y-axis direction is the same as the energy distribution in the Y-axis direction of the Gaussian distribution ED1a Is removed to obtain a corrected energy distribution ED2a with a vertical distribution. The energy distribution in the X axis direction of the pulse laser beam LB2 that has passed through the slit 631a of the mask member 631 is the same Gaussian distribution ED2b as the Gaussian distribution ED1b as shown in Fig. . As the energy distribution modifying means 63 for modifying the edge portion of the gaussian of the energy distribution in the Y-axis direction of the pulsed laser beam oscillated from the laser beam oscillating means 62 to a vertical distribution, the aspheric lens, May be used.

The energy density adjusting means 64 is composed of a cylindrical lens 641 of a concave lens in the illustrated embodiment. 3, the cylindrical lens 641 extends in the X-axis direction of the pulsed laser beam LB2 that has passed through the slit 631a of the mask member 631 as the energy distribution modifying means 63 . The energy distribution ED3b of the pulsed laser light LB2 in the X-axis direction of the pulsed laser light LB3 expanded in the X-axis direction by the cylindrical lens 641 is obtained by dividing the Gaussian distribution ED2b by the upper Similarity shape). 2, the energy distribution ED3a in the Y-axis direction of the pulsed laser beam LB3 that has passed through the cylindrical lens 641 becomes equal to the energy distribution ED2a.

As described above, the pulsed laser beam LB3 extended in the X-axis direction by the cylindrical lens 641 is guided to the condenser 65 mounted on the tip of the casing 61. [ The condenser 65 includes a direction conversion mirror 651 for converting the pulsed laser beam LB3 downward as shown in Fig. 2, and a pulsed laser beam And a condensing lens 652 for collecting the light beam LB3 and irradiating the work W held on the chuck table 36. [ This condensing lens 652 is arranged so that the upper surface of the workpiece W held on the chuck table 36 becomes an image point in the Y axis direction of the pulsed laser beam LB3 in the illustrated embodiment, Is set. Since the pulsed laser beam LB3 is extended in the X-axis direction by the cylindrical lens 641 as described above, the condenser lens 652 moves the X-axis direction of the pulsed laser beam LB3 in the X- The upper surface of the workpiece W held on the chuck table 36 is set to be the light-converging point. As a result, as shown by SP in FIG. 5, the spot of the pulsed laser beam irradiated on the upper surface of the workpiece W held on the chuck table 36 is an elliptical shape having L1 in the Y-axis direction and L2 in the X- Like a rectangle. In this embodiment, the focal lengths of the cylindrical lens 641 and the condenser lens 652 and the distance from the cylindrical lens 641 to the condenser lens 641 are set such that L1 is 60 mu m and L2 is 10 mu m, 652 are set.

Next, another embodiment of the energy density adjusting means 64 will be described with reference to Fig.

The energy density adjusting means 64 shown in Fig. 6 is made up of a combination of a cylindrical lens 641 of a concave lens and a cylindrical lens 642 of a convex lens. The cylindrical lens 641 of the concave lens and the cylindrical lens 642 of the convex lens are configured to be able to adjust the distance between them by means of the gap adjusting means 643. Therefore, by adjusting the interval between the cylindrical lens 641 of the concave lens and the cylindrical lens 642 of the convex lens, the energy density can be adjusted by adjusting the length of the pulsed laser beam LB2 in the X-axis direction.

1, the front end of the casing 61 constituting the laser beam irradiating means 6 is provided with a laser beam irradiation means 6 for imaging Means 7 are arranged. In the embodiment shown in the drawings, the imaging means 7 includes, in addition to a normal imaging device (CCD) for imaging by visible light, an infrared ray illumination means for irradiating infrared rays to the workpiece, (Infrared ray CCD) that outputs an electric signal corresponding to the infrared ray captured by the optical system, and sends the captured image signal to the control means (not shown).

The laser beam irradiation unit 5 in the illustrated embodiment has moving means 53 for moving the unit holder 51 in the direction shown by the arrow Z along the pair of guide rails 423 and 423 . The moving means 53 includes a male screw rod (not shown) disposed between the pair of guide rails 423 and 423 and a driving source such as a pulse motor 532 for rotating the male screw rod, The unit holder 51 and the laser beam irradiating means 6 are moved along the pair of guide rails 423 and 423 in the direction of the arrow Z by rotating the male screw rod not shown by the pulse motor 532 forwardly or reversely (Z-axis direction) shown in the figure. In the illustrated embodiment, the laser beam irradiating means 6 is moved upward by driving the pulse motor 532 in the normal direction and the laser beam irradiating means 6 is moved downward by driving the pulse motor 532 in the reverse direction As shown in FIG.

The laser processing apparatus according to the embodiment of the present invention is configured as described above, and its operation will be described below.

Here, a semiconductor wafer as a workpiece processed by the laser machining apparatus will be described with reference to Figs. 7 and 8. Fig.

The semiconductor wafer 10 shown in Figs. 7 and 8 is a multilayer body 12 in which functional films on which an insulating film and a circuit are formed on the surface of a semiconductor substrate 11 such as silicon are laminated, The device 13 is formed in a matrix shape. Each of the devices 13 is partitioned by a street 14 formed in a lattice shape. In the illustrated embodiment, the insulating film forming the layered body 12 is an SiO ₂ film, an inorganic film such as SiOF or BSG (SiOB), or an organic film such as a polyimide film or a parylene film (Low-k film) composed of a low dielectric constant insulating film.

In order to divide the semiconductor wafer 10 described above along the street 14, the semiconductor wafer 10 is adhered to the surface of the protective tape T mounted on the annular frame F as shown in Fig. 9 . At this time, the back surface side of the semiconductor wafer 10 is adhered to the protective tape T with the surface 10a facing upward.

Next, a laser beam irradiation process is performed to irradiate a laser beam along the street 14 of the semiconductor wafer 10 and to remove the laminate 12 on the street.

In this laser beam irradiation step, the semiconductor wafer 10 supported on the annular frame F is placed on the chuck table 36 of the laser machining apparatus shown in Fig. 1 through the protective tape T, And adsorbs and holds the semiconductor wafer 10 on the chuck table 36. At this time, the semiconductor wafer 10 is held with the surface 10a as its upper side. The annular frame F supporting the semiconductor wafer 10 through the protective tape T is fixed by a clamp 362. [

The chuck table 36 with the semiconductor wafer 10 sucked and held as described above is positioned directly below the imaging means 7 by the processing and transfer means 37. [ When the chuck table 36 is located immediately below the image pickup means 7, an alignment operation for detecting the machining area of the semiconductor wafer 10 to be laser-machined is performed by the image pickup means 7 and control means not shown . That is, the imaging means 7 and the control means (not shown) include a street 14 formed in a predetermined direction of the semiconductor wafer 10, a laser beam irradiation means Image matching such as pattern matching for aligning the condenser 65 of the laser beam 6 is performed and alignment of the laser beam irradiation position is performed. Also, for the streets 14 formed on the semiconductor wafer 10 and extending in a direction orthogonal to the predetermined direction, alignment of the laser beam irradiation positions is likewise carried out.

When the street 14 formed on the semiconductor wafer 10 held on the chuck table 36 is detected and alignment of the laser beam irradiation position is performed as described above, The chuck table 36 is moved to the laser beam irradiation area where the condenser 65 for irradiating the laser beam is located and the predetermined street 14 is positioned just below the condenser 65. [ 10 (a), the semiconductor wafer 10 is positioned such that one end of the street 14 (the left end in FIG. 10 (a)) is positioned directly under the condenser 65 . The moving means 53 is operated so as to position the imaging point in the Y-axis direction of the pulse laser beam LB3 irradiated from the condenser 65 and the condensing point in the X-axis direction on the surface of the street 14, The height position of the irradiation means 6 is adjusted. 10 (b), the spot SP of the pulse laser beam LB3 emitted from the condenser 65 is positioned on the surface of the street 14 formed on the semiconductor wafer 10 do.

Next, while the chuck table 36, that is, the semiconductor wafer 10 is irradiated with the pulsed laser beam LB3 from the condenser 65 at a predetermined feed rate in the direction of arrow X1 in Fig. 10 (a) . When the other end of the street 14 (the right end in Fig. 10 (c)) reaches the position immediately below the condenser 65 as shown in Fig. 10 (c) And the movement of the chuck table 36, that is, the movement of the semiconductor wafer 10 is stopped.

As a result, the streets 14 of the semiconductor wafer 10 are formed with the laser machining grooves 140 deeper than the laminate 12 having the width D of 60 占 퐉 as shown in Fig. 11 in the illustrated embodiment do. As described above, according to the laser processing apparatus of the present invention, since the laser processing groove 140 having a wide width can be formed, the productivity is improved. The energy distribution in the Y-axis direction of the spot SP of the pulsed laser beam LB3 forming the laser machining groove 140 is corrected to a vertical distribution by removing the edges of the Gaussian distribution, The laser processing groove 140 is formed so that its outer side is perpendicular to the processing surface (upper surface) of the layered body 12 So that the laminate 12 is not peeled off.

The processing conditions in the laser beam irradiation step are set as follows, for example.

Laser beam source: YVO4 laser or YAG laser

Wavelength: 355 nm

Average power: 3.0 W

Repetition frequency: 100 kHz

Machining feed rate: 300 ㎜ / s

If all of the streets 14 formed on the semiconductor wafer 10 have been subjected to the laser beam irradiation process described above, a cutting process is performed to cut the semiconductor wafer 10 along the streets 14. That is, as shown in FIG. 12A, the semiconductor wafer 10 on which the laser beam irradiation process is performed on the chuck table 161 of the cutting device 16 is disposed with the surface 10a as an upper side, The semiconductor wafer 10 is held on the chuck table 161 by a suction means which is not provided. Next, the chuck table 161 holding the semiconductor wafer 10 is moved to the cutting start position of the cutting area. 12 (a), one end of the street 14 to be cut (the left end in FIG. 12 (a)) is cut out from immediately below the cutting blade 162 in advance And is located on the right side by a predetermined size. At this time, the cutting blade 162 is positioned within the width D of the laser processing groove 140 as shown in FIG. 12 (b).

When the chuck table 161, that is, the semiconductor wafer 10 is positioned at the cutting start position of the cutting area, the cutting blade 162 is moved from the standby position shown by the two-dot chain line in FIG. And is positioned at a predetermined cutting feed position as shown by the solid line in Fig. 12 (a). The cutting transfer position is set to a position where the lower end of the cutting blade 162 reaches the protective tape T adhered to the back surface of the semiconductor wafer 10 as shown in Fig. 12 (c).

12 (a), the cutting blade 162 is rotated at a predetermined rotational speed in the direction indicated by the arrow 162a, and the chuck table 161, that is, the semiconductor wafer 10 is rotated At a predetermined cutting feed speed in the direction shown by the arrow X1 in Fig. When the chuck table 161, that is, the other end of the semiconductor wafer 10 (the right end in FIG. 12 (a)) reaches the left side of the cutting blade 162 by a predetermined size, The movement of the table 161, that is, the movement of the semiconductor wafer 10 is stopped. The semiconductor wafer 10 is cut along the street 14 by cutting and transferring the chuck table 161, that is, the semiconductor wafer 10 as described above. Since the laser machining groove 140 is formed perpendicularly to the machined surface (upper surface) of the laminate body 12 from the outside as described above, the cutting blade 162 is formed on both sides of the street 14 And does not act on the laminate 12.

Next, the chuck table 161, that is, the semiconductor wafer 10 is indexed and transported in a size corresponding to the distance of the streets 14 in the direction perpendicular to the paper (indexing transport direction) in Fig. 12A, The street 14 to be cut is positioned at a position corresponding to the cutting blade 162, and is returned to the state shown in Fig. 12 (a). Then, the cutting process is performed as described above.

The cutting process is performed under the following processing conditions, for example.

Cutting blade: outer diameter 52 mm, thickness 20 탆

Rotation speed of cutting blade: 40,000 rpm

Cutting feed rate: 50 mm / sec

The above-described cutting process is performed on all the streets 14 formed on the semiconductor wafer 10. As a result, the semiconductor wafer 10 is cut along the street 14 and divided into individual devices.

1 is a perspective view of a laser machining apparatus constructed in accordance with the present invention;

Fig. 2 is a block diagram schematically showing a configuration of a laser beam irradiation means mounted on the laser machining apparatus shown in Fig. 1. Fig.

3 is a plan view of a main portion of the laser beam irradiation means shown in Fig.

Fig. 4 is a side view of a main part of the laser beam irradiation means shown in Fig. 2; Fig.

Fig. 5 is an explanatory view showing a spot shape of a laser beam irradiated from a condenser constituting the laser beam irradiation means shown in Fig. 2; Fig.

Fig. 6 is an explanatory view showing another embodiment of the energy density adjusting means constituting the laser beam irradiation means shown in Fig. 2; Fig.

7 is a perspective view of a semiconductor wafer as a workpiece;

8 is a partially enlarged cross-sectional view of the semiconductor wafer shown in Fig.

Fig. 9 is a perspective view showing a state in which the semiconductor wafer shown in Fig. 7 is supported on an annular frame via a protective tape. Fig.

Fig. 10 is an explanatory diagram of a laser beam irradiation step for forming a laser machining groove along the street of the semiconductor wafer shown in Fig. 7 by the laser machining apparatus shown in Fig.

11 is an enlarged sectional view of a laser machining groove formed in a semiconductor wafer by the laser beam irradiation step shown in Fig. 10; Fig.

Fig. 12 is an explanatory diagram of a cutting step of cutting a semiconductor wafer along the cavity of the laser formed by the laser beam irradiation step shown in Fig. 10; Fig.

<Description of Symbols>

A first chuck table table having a first chuck table and a second chuck table table having a first chuck table and a second chuck table table, A laser beam irradiating means 62 a pulsed laser beam emitting means 63 an energy distribution modifying means 631 a mask member 64 energy density adjusting means 641 cylindrical lens 65 laser beam irradiating means 63 laser beam irradiating means 63 laser beam irradiating means 63 laser beam irradiating means 63 laser beam modifying means 631 mask member 64 energy density adjusting means 641 cylindrical lens 65, A condenser 651 a direction changing mirror 652 a condensing lens 7 imaging means 10 semiconductor wafer 11 semiconductor substrate 12 laminate 13 device 14 street 16 cutting device, 161: chuck table of the cutting device, 162: cutting blade

Claims (4)

A chuck table for holding a workpiece; a laser beam irradiating means for irradiating a laser beam to a workpiece held on the chuck table; and a chuck table for moving the chuck table and the laser beam irradiating means in a relative movement And an indexing conveying means for relatively moving the chuck table and the laser beam irradiating means in an indexing conveying direction (Y-axis direction) orthogonal to the processing transfer direction (X-axis direction), and the laser beam irradiation And a condensing lens for condensing a laser beam emitted from the laser beam oscillation means and irradiating the workpiece held on the chuck table, wherein the laser beam oscillation means oscillates the laser beam, Wherein the laser beam irradiation means is disposed between the laser beam oscillation means and the condenser lens and generates energy that forms a vertically distributed edge portion of a gaussian energy distribution of a laser beam emitted from the laser beam oscillation means in the Y- And energy density adjusting means for adjusting the energy density in the X-axis direction of the laser beam whose energy distribution is modified by the energy distribution modifying means, Wherein the energy distribution modifying means includes a mask member having a slit for regulating passage of a laser beam emitted from the laser beam oscillation means in the Y axis direction and the energy density adjusting means comprises a cylindrical lens of a concave lens, A cylindrical lens of a convex lens disposed at a distance from a cylindrical lens of the lens, and a gap adjusting means for adjusting a distance between the cylindrical lens of the concave lens and the cylindrical lens of the convex lens, wherein the cylindrical lens of the concave lens, The length of the laser beam in the X-axis direction is adjusted by adjusting the distance from the cylindrical lens of the convex lens to adjust the energy density, A laser beam having an energy density in the X-axis direction adjusted by the energy density adjusting means is focused on the upper surface of the workpiece held in the chuck table in the Y-axis direction, and held on the chuck table in the X- And the workpiece is focused on the upper surface of the workpiece. delete delete delete

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