JP2008126237A - Laser beam machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining apparatus in which a large sized apparatus can be avoided by suppressing an inertial force even if a machining feed speed is increased. <P>SOLUTION: A chuck table 10 and a laser beam irradiation means 20 are both structured so that feeding of work in the X axis direction is made possible by the respective machining feed means 30, 40 for the chuck table and the laser beam irradiation means. As a result, even with an increased feeding speed, the respective machining feed speeds required for the chuck table 10 and the laser beam irradiation means 20 can be reduced substantially by half. Accordingly, the inertial force generated for acceleration and deceleration can be suppressed to a quarter, making a large sized apparatus unnecessary by reducing a moving distance required for the X axis direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus that processes a wafer by irradiating a laser beam.

  A wafer on which a plurality of devices such as ICs and LSIs are formed is divided into individual devices by a dividing device such as a laser processing device, and used for electronic devices such as mobile phones and personal computers.

  A laser processing apparatus includes a chuck table for holding a wafer, a laser beam irradiation unit for irradiating a wafer held on the chuck table with a laser beam, and a processing feed unit for relatively processing and feeding the chuck table and the laser beam irradiation unit. A laser beam oscillating means for oscillating a pulsed laser beam, and a focusing unit for focusing the pulsed laser beam oscillated by the laser beam oscillator and positioning a focusing point on the wafer held by the chuck table; (For example, refer to Patent Document 1), and the wafer can be irradiated with a laser beam with high accuracy.

  Here, for example, when the laser beam oscillator irradiates a pulse laser beam at a repetition frequency of 50 kHz and the spot diameter is φ10 μm, the processing feed rate must be set to 500 mm / second in order to connect the spots and irradiate the wafer. I must.

Japanese Patent No. 3408805

  However, if the chuck table or the laser beam irradiation means is processed and fed at a processing feed rate of 500 mm / second, the movement distance of the chuck table or the laser beam irradiation means in the processing feed direction is sufficiently secured in consideration of acceleration and deceleration due to inertia. There is a problem that the apparatus becomes large.

  Further, when the processing feed rate is limited, there is a problem that a laser beam oscillator having a high repetition frequency cannot be used, and productivity cannot be improved.

  The present invention has been made in view of the above, and an object of the present invention is to provide a laser processing apparatus capable of suppressing the inertia force and avoiding the enlargement of the apparatus even when the processing feed rate is increased.

  In order to solve the above-described problems and achieve the object, a laser processing apparatus according to the present invention includes a chuck table that holds a wafer, and laser beam irradiation means that irradiates the wafer held by the chuck table with a laser beam. A chuck table processing and feeding means for processing and feeding the chuck table in the X-axis direction; and a laser beam irradiation means and processing / feeding means for processing and feeding the laser beam irradiation means in the X-axis direction. It is characterized by providing.

  The laser processing apparatus according to the present invention is characterized in that, in the above-mentioned invention, a chuck table indexing / feeding means for indexing and feeding the chuck table in the Y-axis direction orthogonal to the X-axis direction is provided.

  The laser processing apparatus according to the present invention is characterized in that, in the above-mentioned invention, the laser beam irradiation means includes indexing and feeding means for indexing and feeding the laser beam irradiation means in the Y-axis direction orthogonal to the X-axis direction.

  Further, the laser processing apparatus according to the present invention is characterized in that, in the above-mentioned invention, the laser beam irradiating means is moved in focus in the Z-axis direction orthogonal to the X-axis direction and the Y-axis direction. .

  According to the laser processing apparatus of the present invention, since both the chuck table and the laser beam irradiation means can be processed and fed in the X-axis direction, the chuck table and the laser beam irradiation means can be respectively supplied even if the processing feed speed is increased. The required machining feed rate can be substantially halved, so that the inertial force generated for acceleration and deceleration can be suppressed to ¼, and the required travel distance in the X-axis direction can be reduced. The effect of reducing the size of the apparatus can be avoided. On the other hand, according to the laser processing apparatus of the present invention, since the limit of the processing feed rate can be substantially doubled, a laser beam oscillator with a high repetition frequency can be employed, and further productivity improvement can be achieved. There is an effect that can be done.

  Hereinafter, a laser processing apparatus which is the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is an external perspective view showing the main part of the laser processing apparatus of the present embodiment. First, the laser processing apparatus 1 of the present embodiment includes a chuck table 10 that holds a wafer W, and laser beam irradiation means 20 that irradiates the wafer W held on the chuck table 10 with a pulsed laser beam.

  The chuck table 10 is formed of a porous material and has a suction chuck structure that sucks and holds the wafer W with a negative pressure from a negative pressure source (not shown), and a pulse motor (not shown) disposed in the lower cylindrical member 11. Can be rotated. Here, the wafer W held by the chuck table 10 is affixed to the surface of the adhesive tape T attached to the annular frame F as shown in FIG. A plurality of regions are partitioned by a plurality of division lines S formed in a grid pattern, and devices D such as IC and LSI are formed in the partitioned regions. The chuck table 10 is provided with a clamp 12 for detachably fixing the annular frame F portion. A rectangular cover member 13 is disposed around the chuck table 10.

  The laser beam irradiation means 20 includes a cylindrical casing 21 arranged substantially horizontally. In the casing 21, as shown in FIG. 3, a pulse laser beam oscillation means 22 and a transmission optical system 23 are arranged. The pulse laser beam oscillation means 22 is a pulse laser beam oscillator 22a such as a Yb laser (ytterbium doped fiber laser) oscillator or an Er laser (erbium doped fiber laser) oscillator, and a repetition attached to the pulse laser beam oscillator 22a. And frequency setting means 22b. The transmission optical system 23 includes an optical adjustment element such as an attenuator, an acoustooptic deflection element, or a galvano scanner, in addition to an optical element such as a beam splitter. A condenser 24 containing a condenser lens (not shown) having a well-known structure such as a combined lens is attached to the front end of the casing 21, and a holder 25 is attached to the rear end.

  Note that an area to be processed by the pulsed laser beam irradiated from the condenser 24 of the laser beam irradiation means 20 is picked up at the tip of the casing 21 by imaging the surface Wa of the wafer W held on the chuck table 10. An imaging means 26 for detection is attached. The imaging unit 26 includes an imaging element such as a CCD, and sends the captured image signal to a control unit (not shown).

  Further, the laser processing apparatus 1 of the present embodiment includes a chuck table processing feed means 30 for processing and feeding the chuck table 10 in the X-axis direction, which is the processing direction, and a laser for processing and feeding the laser beam irradiation means 20 in the X-axis direction. Beam irradiation means processing and feeding means 40, chuck table indexing and feeding means 50 for indexing and feeding the chuck table 10 in the Y-axis direction, which is an indexing direction orthogonal to the X-axis direction, and laser beam irradiation means 20 for indexing and feeding in the Y-axis direction A laser beam irradiating means indexing and feeding means 60, and a focus moving means 70 for moving the laser beam irradiating means 20 in the Z-axis direction orthogonal to the X-axis direction and the Y-axis direction.

  The chuck table processing feed means 30 includes a pair of guide rails 31 disposed in parallel along the X-axis direction on the stationary base 2 and a cylindrical member 11 disposed below the chuck table 10. A sliding block 32 disposed on the guide rail 31 so as to be movable in the X-axis direction, a male threaded rod 33 disposed in parallel between the pair of guide rails 31, and a pulse for rotationally driving the male threaded rod 33 A drive source such as a motor 34 is included. One end of the male screw rod 33 is rotatably supported by a bearing block 35 fixed on the stationary base 2, and the other end is connected to the output shaft of the pulse motor 34. Further, the male screw rod 33 is screwed into a through female screw hole formed in a female screw block (not shown) that protrudes from the lower surface of the central portion of the sliding block 32, and the male screw rod 33 is driven to rotate forward and reverse by a pulse motor 34. As a result, the chuck table 10 is reciprocated in the X-axis direction along the guide rail 31 via the sliding block 32.

  The chuck table indexing and feeding means 50 indexes and feeds the chuck table 10 on the sliding block 32, and a pair of guide rails 51 provided in parallel on the sliding block 32 along the Y-axis direction and the cylindrical member 11 are provided. A sliding block 52 which is fixed and arranged on the guide rail 51 so as to be movable in the Y-axis direction, a male screw rod 53 which is arranged in parallel between the pair of guide rails 51, and the male screw rod 53 are driven to rotate. For example, a drive source such as a pulse motor 54 is included. One end of the male screw rod 53 is rotatably supported by a bearing block 55 fixed on the slide block 32, and the other end is connected to the output shaft of the pulse motor 54. The male threaded rod 53 is screwed into a through female threaded hole formed in the sliding block 52, and the male threaded rod 53 is forwardly and reversely driven by a pulse motor 54, whereby the chuck table 10 is moved via the sliding block 52. Indexed and fed along the guide rail 51 in the Y-axis direction.

  The in-focus moving means 70 is provided on a vertical surface of an L-shaped sliding block 71 provided so as to be movable in the X-axis direction and the Y-axis direction by the laser beam irradiation means processing feed means 40 and the laser beam irradiation means indexing feed means 60. A pair of guide rails 72 provided in parallel along the Z-axis direction, and a pair of guided grooves 73 formed on the holder 25 of the laser beam irradiation means 20 and slidably fitted to the pair of guide rails 72, A male screw rod (not shown) disposed in parallel between the pair of guide rails 72 and a drive source such as a pulse motor 74 for rotating the male screw rod are configured. The male screw rod is screwed into a penetrating female screw hole formed in the holder 25, and the male screw rod is forwardly and reversely driven by a pulse motor 74, whereby the condenser 24 of the laser beam irradiation means 20 is passed through the holder 25. Is moved along the guide rail 72 in the Z-axis direction.

  The laser beam irradiating means indexing and feeding means 60 is mounted with a pair of guide rails 61 arranged in parallel along the Y-axis direction on the stationary base 2 and a sliding block 71 and mounted on the guide rail 61 in the Y-axis direction. And a driving block such as a pulse motor 64 for rotationally driving the male screw rod 63. It consists of One end of the male screw rod 63 is rotatably supported by a bearing block (not shown) fixed on the stationary base 2, and the other end is connected to the output shaft of the pulse motor 64. Further, the male screw rod 63 is screwed into a through female screw hole formed in a female screw block (not shown) provided so as to protrude from the lower surface of the central portion of the sliding block 62, and the male screw rod 63 is driven to rotate forward and reverse by a pulse motor 64. Thus, the laser beam irradiation means 20 supported by the sliding block 71 via the sliding block 62 is indexed and fed along the guide rail 61 in the Y-axis direction.

  The laser beam irradiation means processing / feeding means 40 processes and feeds the laser beam irradiation means 20 in the X-axis direction on the sliding block 62 movable in the Y-axis direction, and is parallel to the sliding block 62 along the X-axis direction. A pair of guide rails 41 provided on the sliding block 71, a pair of guided grooves 42 formed on the lower surface of the sliding block 71 and slidably fitted to the pair of guide rails 41, and the pair of guide rails 41 in parallel. A male screw rod 43 is provided, and a drive source such as a pulse motor 44 for rotationally driving the male screw rod 43 is included. One end of the male screw rod 43 is rotatably supported by a bearing block (not shown) fixed on the slide block 62, and the other end is connected to the output shaft of the pulse motor 44. The male screw rod 43 is screwed into a through female screw hole formed in the slide block 71, and the male screw rod 43 is rotated forward and reversely by the pulse motor 44, whereby laser beam irradiation means is passed through the slide block 71. 20 is reciprocally fed along the guide rail 41 in the X-axis direction.

  Next, an outline of a laser processing method for the wafer W using such a laser processing apparatus 1 will be described. First, the wafer W with the frame F is placed on the chuck table 10, and the wafer W is sucked and held on the chuck table 10. The chuck table 10 that sucks and holds the wafer W is positioned directly below the imaging means 26 by the chuck table processing feed means 30, the laser beam irradiation means processing feed means 40, the chuck table index feed means 50, and the laser beam irradiation means index feed means 60. It is done.

  When the chuck table 10 is positioned immediately below the image pickup means 26, an alignment operation for detecting a processing region of the wafer W to be laser processed is executed by the image pickup means 26 and a control means (not shown). That is, the imaging unit 26 and the control unit include a division line S formed in a predetermined direction of the wafer W, and a condenser 24 of the laser beam irradiation unit 20 that irradiates the pulse laser beam along the division line S. Image processing such as pattern matching is performed to align the laser beam, and alignment of the laser beam irradiation position is performed. At this time, the alignment of the laser beam irradiation position is similarly performed on the division line S extending in the direction orthogonal to the predetermined direction formed on the wafer W.

  When alignment of the laser beam irradiation position is performed, the chuck table 10 is moved to the laser beam irradiation region where the condenser 24 for irradiating the pulsed laser beam is located, and condenses one end side of the predetermined division line S. It is positioned directly below the vessel 24. The chuck table 10 holding the wafer W and the condenser 24 while irradiating a pulse laser beam having a constant output at a predetermined wavelength having transparency from the condenser 24 are respectively connected to the chuck table processing feeding means 30. The laser beam irradiating means and the processing feed means 40 are moved at a predetermined processing feed speed in directions close to each other in the X-axis direction. When the irradiation position of the condenser 24 reaches the position of the other end of the division planned line S, the irradiation of the pulse laser beam by the laser beam irradiation means 20 is stopped and the X axis of the chuck table 10 and the condenser 24 is stopped. Stop machining feed in the direction. In such a pulse laser beam irradiation step, the condenser 24 is moved in focus by the focus moving means 70 so that the spot of the condensing point of the pulse laser beam is positioned inside the region of the wafer W with respect to the division line S. The altered region is formed by irradiating in the above state. By concatenating the spots of the condensing points and irradiating the wafer W to continuously form the altered region, the intensity of the planned division line S decreases.

  When the laser processing for one division line S is completed, the chuck table 10 holding the wafer W and the condenser 24 are held in Y by one or both of the chuck table indexing and feeding means 50 and the laser beam irradiation means indexing and feeding means 60. Indexing and feeding are performed in the axial direction, and the other end side of the adjacent division planned line S is positioned directly below the condenser 24. The chuck table 10 holding the wafer W and the condenser 24 while irradiating a pulse laser beam having a constant output at a predetermined wavelength having transparency from the condenser 24 are respectively connected to the chuck table processing feeding means 30. The laser beam irradiating means and the machining feed means 40 are moved at a predetermined machining feed speed in a direction approaching each other in the X-axis direction (the direction opposite to the case of the adjacent previous line). When the irradiation position of the condenser 24 reaches the position of one end of the division line S, the irradiation of the pulse laser beam by the laser beam irradiation means 20 is stopped and the chuck table 10 and the condenser 24 in the X-axis direction are stopped. Stop machining feed.

  Thereafter, the same laser processing is repeated, and when the process for the predetermined division line S in the predetermined direction is completed, the chuck table 10 is rotated 90 degrees to the predetermined division line S extending in the direction orthogonal to the predetermined direction. However, the same laser processing is repeated. After forming an altered region by laser processing for all the division lines S, an external force is applied to the wafer W along the division lines S whose strength has decreased, so that the wafer W is divided along the division lines S. It can be divided and divided into individual devices D.

  Processing feed in such a laser processing operation will be described with reference to FIG. FIG. 4 is an explanatory diagram schematically showing a state of change in the machining feed rate related to the machining feed according to the present embodiment in comparison with the conventional example. For example, in the case where the pulse laser beam oscillator 22a irradiates the wafer W with a pulse laser beam at a repetition frequency of 50 Hz and the spot diameter is φ10 μm, in order to irradiate the wafer W with the spots connected, processing on the wafer W is performed. The machining feed rate in the X-axis direction in the region must be set to a constant rate of Vc = 500 mm / second.

  Here, for example, when the chuck table is processed and fed at a machining feed rate of Vc = 500 mm / sec as in the prior art, as shown by a two-dot chain line in FIG. 4, it corresponds to a machining feed rate of Vc = 500 mm / sec. It is necessary to expect acceleration and deceleration due to a large inertial force, and it is necessary to secure a sufficient movement distance in the machining feed direction of the chuck table, which increases the size of the apparatus.

  On the other hand, in this embodiment, as schematically shown in FIG. 2, both the wafer W held on the chuck table 10 and the condenser 24 of the laser beam irradiation means 20 are processed and fed in the X-axis direction. For example, the machining feed rate of the chuck table 10 is set to Vc / 2 as shown by the solid line in FIG. 4, and the machining feed rate of the condenser 24 of the laser beam irradiation means 20 is shown in FIG. As shown by the broken line, Vc / 2 is set, and the chuck table 10 and the condenser 24 are always processed and fed in the opposite directions, so that the overall processing feed speed is Vc = 500 mm / sec depending on the relative speed difference between the two. The necessary constant speed can be ensured. Even when the chuck table 10 and the condenser 24 are processed and fed at a processing feed rate of Vc / 2 = 250 mm / second, acceleration and deceleration due to inertia force are expected as shown by a solid line and a broken line in FIG. Although it is necessary, since the inertia force is substantially reduced to about ¼ due to the substantial halving of the machining feed rate, the travel distance required for acceleration and deceleration can be shortened. In particular, in recent years, the diameter of the wafer W has been increased. For example, even when the diameter of the wafer W is increased to 450 mm, the X-axis direction necessary for laser processing the wafer W is increased. The movement distance for acceleration and deceleration in the can be shortened, and the enlargement of the apparatus can be suppressed. Further, as a result of shortening the moving distance for acceleration and deceleration in the X-axis direction, the processing time required for each scheduled division line S can also be shortened.

  Further, according to the present embodiment, since both the chuck table 10 and the condenser 24 of the laser beam irradiation means 20 can be processed and fed in the X-axis direction, if it is desired to prioritize the processing speed. For example, the processing feed speed of both the chuck table 10 and the condenser 24 is set as Vc = 500 mm / sec and the machining feed is always performed in the opposite direction so that the limit of the machining feed speed is substantially 2. The pulse laser beam oscillator 22a having a higher repetition frequency can be employed, and the productivity can be further improved.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the present embodiment, the sliding block 71 is configured to be movably mounted in the X-axis direction on the sliding block 62 that is movable in the Y-axis direction. However, the sliding block 71 moves in the X-axis direction on the stationary base 2. By providing a free slide block and mounting a slide block movable in the Y-axis direction on this slide block, the laser beam irradiation means processing feed means and the laser beam irradiation means indexing feed means may be configured. Good.

It is an external appearance perspective view which shows the principal part of the laser processing apparatus of embodiment of this invention. It is a perspective view which shows schematically a mode that both the wafer hold | maintained at the chuck | zipper table and the collector of a laser beam irradiation means can be processed and sent to an X-axis direction. It is a block diagram which shows the structural example of a laser beam irradiation means. It is explanatory drawing which shows typically the mode of a change of the process feed speed regarding the process feed by this Embodiment contrasting with a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Chuck table 20 Laser beam irradiation means 30 Chuck table processing and feeding means 40 Laser beam irradiation means Processing and feeding means 50 Chuck table indexing and feeding means 60 Laser beam irradiation means and indexing and feeding means 70 Focusing movement means W Wafer

Claims (4)

A laser processing apparatus comprising: a chuck table that holds a wafer; and a laser beam irradiation unit that irradiates a wafer held by the chuck table with a laser beam,
Chuck table processing and feeding means for processing and feeding the chuck table in the X-axis direction;
Laser beam irradiation means processing and feeding means for processing and feeding the laser beam irradiation means in the X-axis direction;
A laser processing apparatus comprising:   The laser processing apparatus according to claim 1, further comprising: a chuck table indexing / feeding unit that indexes and feeds the chuck table in a Y-axis direction orthogonal to the X-axis direction.   3. The laser processing apparatus according to claim 1, further comprising a laser beam irradiation unit indexing and feeding unit that indexes and feeds the laser beam irradiation unit in a Y-axis direction orthogonal to the X-axis direction.   The laser processing according to any one of claims 1 to 3, further comprising: a focusing movement unit that moves the laser beam irradiation unit in a Z-axis direction orthogonal to the X-axis direction and the Y-axis direction. apparatus.

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