JP2014143295A - Chuck table of processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chuck of a processing apparatus that does not cause a transport error after processing even when the wafer surface side (device surface) is placed on a holding surface of a chuck table with an adhesive layer of an adhesive tape facing down. Is to provide a table.
A chuck table for a processing apparatus for sucking and holding a plate-like workpiece, a workpiece holding portion for holding the workpiece on a holding surface, and a base for supporting the workpiece holding portion. And a suction path formed in the base that communicates the workpiece holding part and a suction source, and the workpiece holding part has a plate-like shape having elasticity whose outer periphery is sealed with resin. It is formed of a porous resin, and the workpiece holding part and the base have the same diameter.
[Selection] Figure 6

Description

  The present invention relates to a chuck table of a processing apparatus, and more particularly to a chuck table of a laser processing apparatus that performs processing from a surface opposite to a surface on which a device is formed.

  A wafer such as a silicon wafer or a sapphire wafer formed on the surface by dividing a plurality of devices such as IC, LSI, LED, etc. by dividing lines is divided into individual devices by a processing apparatus, and the divided devices are mobile phones, Widely used in various electronic devices such as personal computers.

  A dicing method using a cutting device called a dicer is widely used for dividing the wafer. In the dicing method, a wafer is cut by cutting a wafer into a wafer while rotating a cutting blade having a thickness of about 30 μm by solidifying abrasive grains such as diamond with a metal or a resin at a high speed of about 30000 rpm. Divide into chips.

  On the other hand, in recent years, a condensing point of a laser beam having a wavelength (for example, 1064 nm) having transparency to the wafer is positioned inside the wafer corresponding to the planned division line, and the laser beam is irradiated along the planned division line. A method of forming a modified layer inside a wafer and then applying an external force to the wafer by a dividing device and dividing the wafer into individual device chips using the modified layer as a starting point (for example, Patent No. 3408805).

  The processing method using a laser beam can increase the processing speed as compared with a dicing method using a dicer, and can relatively easily process even a wafer made of a material having high hardness such as sapphire or SiC. .

  Further, since the modified layer can have a narrow width of, for example, 10 μm or less, there is an advantage that the amount of devices taken per wafer can be increased as compared with the case of processing by the dicing method.

  In this laser processing method, it is a condition that a material for attenuating the energy of the laser beam (for example, a material for forming various patterns constituting the device) is not formed on the incident surface side of the laser beam. For this reason, a wafer having a device formed on the front surface is irradiated with a laser beam from the back side of the wafer to form a modified layer inside the wafer.

  When the laser beam cannot be irradiated from the device surface, the wafer unit is generally fixed to an annular frame by sticking the wafer surface side to an adhesive tape (dicing tape), just as in normal processing. After that, the wafer front side is sucked and held on the holding surface of the chuck table made of porous ceramics through a dicing tape, and a laser beam is irradiated from the exposed back side of the wafer to form a modified layer inside the wafer. To do.

Japanese Patent No. 3408805 JP 2012-109338 A

  By the way, after attaching the front side of the wafer to the dicing tape in this way and irradiating the laser beam from the back side of the wafer to form a modified layer inside the wafer, the wafer is divided into individual device chips by a dividing device. In this method, since the surface of the device chip picked up from the dividing apparatus is on the lower side, it is necessary to carry out the subsequent steps after turning the device chip upside down.

  In order to eliminate such inconvenience, a wafer unit is formed by adhering the back surface of the wafer to an adhesive tape (dicing tape) and fixing it to the annular frame, and then the wafer surface (device surface) on the holding surface of the chuck table. In some cases, a laser beam is irradiated through an adhesive tape.

  However, in this method, the device is damaged by the hard porous ceramics, and the adhesive layer of the adhesive tape faces the chuck table, so that the adhesive tape exposed at the outer periphery of the wafer is stuck on the outer periphery of the chuck table. Therefore, there is a risk of causing a conveyance error after laser processing.

  Therefore, methods such as sticking a release paper to the adhesive layer around the wafer in a donut shape to cover the adhesive layer, or sucking through a porous sheet having both air permeability and releasability have been studied. (For example, refer to Patent Document 2).

  However, these materials have man-hours to set, are expensive because they are consumables, and because the member is inserted between the chuck table and the wafer, the upper surface accuracy of the suction held wafer is high. There was a detrimental effect that it was worse than a normal chuck table alone (height variation was greater).

  The present invention has been made in view of the above points, and an object of the present invention is to place the wafer surface side (device surface) on the holding surface of the chuck table with the adhesive layer of the adhesive tape facing down. It is an object of the present invention to provide a chuck table for a processing apparatus that does not damage the device even if it is placed and does not cause a transport error after processing.

  According to the present invention, there is provided a chuck table of a processing apparatus for sucking and holding a plate-shaped workpiece, a workpiece holding portion for holding the workpiece on a holding surface, and a base for supporting the workpiece holding portion. And a suction path formed in the base for communicating the workpiece holding part and the suction source, and the workpiece holding part is a plate having elasticity whose outer periphery is sealed with resin There is provided a chuck table for a processing apparatus, characterized in that the workpiece holding portion and the base have the same diameter.

  Preferably, the workpiece has a plurality of devices formed on the front surface side, and the back surface is stuck to the adhesive surface of the adhesive tape whose outer peripheral edge is stuck to the annular frame. The surface side of is sucked and held by the holding surface.

  According to the chuck table of the present invention, the wafer holding portion having elasticity that does not damage the device even when the device surface of the wafer is directly mounted and air permeability that sucks and holds the wafer is directly mounted on the base. Since the chuck table is configured, it is possible to prevent the cost increase due to the consumables and the deterioration of the top surface accuracy. The chuck table of the present invention is effective not only when the semiconductor wafer is sucked and held but also when it is placed directly without damaging glass or ceramics.

It is a perspective view of the laser processing apparatus provided with the chuck table concerning the embodiment of the present invention. 2A is an exploded perspective view of the chuck table according to the embodiment of the present invention, and FIG. 2B is a perspective view thereof. It is sectional drawing of the chuck table which concerns on this invention embodiment. It is a surface side perspective view of a semiconductor wafer. It is a disassembled perspective view of a wafer unit. It is a disassembled perspective view which shows a mode that a wafer unit is mounted on a chuck table. FIG. 7A is a cross-sectional view showing a state in which the wafer unit is mounted on the chuck table, and FIG. 7B is a cross-sectional view in a state in which the wafer unit is mounted on the chuck table.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a perspective view of a laser processing apparatus 2 including a chuck table according to an embodiment of the present invention is shown. A pair of guide rails 6 extending in the Y-axis direction are fixed on the stationary base 4 of the laser processing apparatus 2.

  A Y-axis moving block 8 is placed on the stationary base 4 along a pair of guide rails 6 by a Y-axis moving mechanism (index feeding mechanism) 14 composed of a ball screw 10 and a pulse motor 12, that is, Y It is mounted so as to be movable in the axial direction.

  A pair of guide rails 16 extending in the X-axis direction are fixed on the Y-axis moving block 8. On the Y-axis moving block 8, an X-axis moving block 18 is guided by the guide rail 16 by a X-axis moving mechanism (machining feed mechanism) 24 composed of a ball screw 20 and a pulse motor 22, i. It is mounted so as to be movable in the X-axis direction.

  A chuck table 28 is mounted on the X-axis moving block 18 via a table mounting table 26. The chuck table 28 includes four clamps 30 arranged at equal intervals on the outer periphery thereof.

  A support base 32 is fixed on the stationary base 4. A pair of guide rails 34 (only one is shown) extending in the Z-axis direction are fixed to the support base 32. The Z-axis moving block 36 is mounted on the guide rail 34 so as to be movable in the Z-axis direction (vertical direction) by a Z-axis moving mechanism 40 including a ball screw (not shown) and a pulse motor 38.

  A housing 44 of the laser beam irradiation unit 42 is supported on the Z-axis moving block 36. The laser beam irradiation unit 42 includes a laser beam generating unit including a laser oscillator and the like housed in a housing 44, and a condenser (laser head) 46 mounted on the front end portion of the housing 44. An alignment unit 48 including an imaging unit 50 is integrally disposed in the housing 44 of the laser beam irradiation unit 42.

  Next, the chuck table 28 according to the embodiment of the present invention will be described in detail with reference to FIGS. 2 and 3. 2A is an exploded perspective view of the chuck table 28, FIG. 2B is a perspective view thereof, and FIG. 3 is a cross-sectional view of the chuck table 28.

  The chuck table 28 includes a base 52 and a suction holding unit 54 mounted on the base 52. The base 52 is formed with a plurality of concentric suction grooves 58, two connection suction grooves 60 extending in the radial direction connecting the suction grooves 58, and a suction path 62 connected to the connection suction grooves 60. Has been.

  On the other hand, the suction holding part 54 is made of a porous resin having elasticity. As the porous resin, it is desirable to use “fluororesin”.

  The porosity of the suction holding part 54 is about 30 to 60%, and the outer periphery is impregnated with resin to form a sealing (seal) region 56. The flatness of the holding surface 54a of the holding part 54 is, for example, 10 μm or less, and the parallelism is 30 μm or less.

  As shown in FIGS. 2B and 3, the chuck table 28 is configured when the suction holding portion 54 is mounted on the base 52. When the suction path 62 is connected to a suction source (not shown), negative pressure acts on the radial connection suction groove 60 and the concentric suction groove 58, and the suction holding portion 54 is sucked and held on the base 52.

  Referring to FIG. 4, a front perspective view of a semiconductor wafer 11 (hereinafter sometimes simply referred to as “wafer”) 11 is shown. A plurality of planned division lines (streets) 13 are formed in a lattice pattern on the surface 11 a of the wafer 11, and devices 15 such as ICs and LSIs are formed in each region partitioned by the planned division lines 13.

  When laser processing is performed on the wafer 11 by the laser processing apparatus 2 using the chuck table 28 according to the embodiment of the present invention, as shown in FIG. 5, an adhesive tape (dicing) whose outer peripheral portion is attached to the annular frame F is used. A wafer unit 17 is formed by sticking the back side of the wafer 11 to a tape T.

  Then, as shown in FIGS. 6 and 7A, the front and back of the wafer unit 17 are reversed and the surface (device surface) 11a of the wafer 11 is placed on the holding surface 54a of the chuck table 28, and FIG. As shown in B), the annular frame F is clamped and fixed by the clamp 30.

  As shown in FIG. 7, the table mounting table 26 of the chuck table 28 includes a suction path 64 communicating with the suction path 62 formed on the base 52 of the chuck table 28, and a suction communicating with the surface of the table mounting table 26. A path 66 is formed.

  When the suction paths 64 and 66 of the table mounting table 26 are connected to a vacuum suction source (not shown), negative pressure acts on the chuck table 28 via the suction path 66, and the chuck table 28 is sucked and held by the table mounting table 26. A negative pressure acts on the suction holding portion 54 via the suction paths 64 and 62 and the suction grooves 60 and 58. Therefore, the wafer 11 of the wafer unit 17 is sucked and held by the suction holding unit 54.

  Since the suction holding portion 54 is made of fluororesin, even if the device surface (surface) 11a of the wafer 11 is directly placed on the holding surface 54a of the chuck table 28, the device 15 is damaged by the elasticity of the fluororesin. There is no.

  Further, since the sealing portion 56 is formed by impregnating the outer peripheral portion of the suction holding portion 54 with a resin, the negative pressure does not escape from the outer periphery of the suction holding portion 54, and the wafer 11 is surely secured by the suction holding portion 54. Can be sucked and held.

  After the wafer 11 of the wafer unit 17 is sucked and held by the suction holding portion 54 of the chuck table 28 as shown in FIG. 7B, the laser beam is incident from the back surface 11b side of the wafer 11 via the adhesive tape T. Thus, a modified layer is formed along the scheduled division line 17 inside the wafer 11.

  As is apparent from FIG. 7B, the diameter of the wafer 11 and the diameter of the suction holding portion 54 including the seal portion 56 are substantially the same, and the outer diameter of the suction holding portion 54 is different from that of the conventional chuck table. Since there is no frame formed of a metal such as SUS, the adhesive layer of the adhesive tape T does not stick to the outer peripheral portion of the chuck table 28, and a conveyance error of the wafer unit 17 does not occur after laser processing. Further, the suction holding portion 54 and the base 52 of the chuck table 28 have substantially the same diameter.

  In the above-described embodiment, the semiconductor wafer 11 has been described as a workpiece to be mounted on the chuck table 28. However, the workpiece is not limited to a semiconductor wafer, and a workpiece such as glass or ceramic is also damaged. It can be directly mounted on the holding surface 54a of the chuck table 28 without any problem.

2 Laser processing equipment 11 Semiconductor wafer T Adhesive tape (dicing tape)
F annular frame 17 wafer unit 28 chuck table 52 base 54 suction holding part 54a holding surface 56 sealing part

Claims (2)

A chuck table of a processing apparatus for sucking and holding a plate-shaped workpiece,
A workpiece holding section for holding the workpiece on the holding surface;
A base for supporting the workpiece holding portion;
A suction path formed in the base that communicates the workpiece holding part and a suction source, and
The workpiece holding portion is formed of a plate-like porous resin having elasticity whose outer periphery is sealed with resin,
The chuck table of a processing apparatus, wherein the workpiece holding part and the base have the same diameter. The workpiece is
Multiple devices are formed on the surface side,
The back side is stuck to the adhesive surface of the adhesive tape whose outer periphery is stuck to the annular frame,
The chuck table of the processing apparatus according to claim 1, wherein the surface side of the workpiece on which the device is formed is sucked and held by the holding surface.

Images