KR102084269B1 - Laser machining apparatus and method for coating protection film - Google Patents

Abstract

An economical protective film coating apparatus which suppressed the amount of the protective film liquid discarded, the laser processing apparatus provided with the protective film coating apparatus, and a protective film coating method are provided.
A cassette placing table on which a processing table holding a workpiece, laser processing means for performing laser processing on the workpiece held on the processing table, a cassette capable of accommodating a plurality of workpieces, and the cassette placing table A laser processing apparatus comprising a conveying means for conveying a workpiece from at least one cassette to a processing table, the holding table having a holding surface for holding the workpiece and a protective film on the surface of the workpiece held by the holding table. A protective film liquid discharge head having a slit-shaped discharge port for discharging a protective film liquid made of a water-soluble resin for forming a film; Means, and said protective film liquid discharge head is flush with said holding surface of said holding table. And in that it includes a second moving means for relatively moving in one direction, it characterized in.

Description

LASER MACHINING APPARATUS AND METHOD FOR COATING PROTECTION FILM}

The present invention relates to a laser processing apparatus and a protective film coating method using the laser processing apparatus.

A wafer such as a silicon wafer, a sapphire wafer, and the like formed on the surface by dividing a plurality of devices such as an IC, an LSI, an LED, and the like by dividing lines, is divided into individual devices by a processing apparatus. It is widely used for various electronic devices such as a computer.

The dicing method using the cutting device called a dicer is widely employ | adopted for dividing a wafer. In the dicing method, a wafer is cut and divided into individual devices by cutting a cutting blade in which abrasive grains such as diamond are hardened with a metal or a resin and having a thickness of about 30 µm, into the wafer while rotating at a high speed of about 30000 rpm.

On the other hand, in recent years, a method of forming a laser processing groove by irradiating a wafer with a pulsed laser beam having an absorbing wavelength to the wafer, and dividing the wafer into individual devices by breaking the wafer with a breaking device along the laser processing groove is proposed. (See, for example, Japanese Patent Application Laid-Open No. 10-305420).

Formation of the laser processing groove by the laser processing apparatus can speed up the processing speed as compared with the dicing method by the dicer, and even a wafer made of a material having a high hardness such as sapphire or SiC can be processed relatively easily. In addition, since the processing groove can be made narrow, for example, 10 µm or less, the device acquisition amount per wafer can be increased in the case of processing by the dicing method.

However, when the pulsed laser beam is irradiated onto the wafer, thermal energy is concentrated in the region to which the pulsed laser beam is irradiated to generate debris. If this debris adheres to the surface of the device, a problem arises that the quality of the device is degraded.

For example, Japanese Patent Laid-Open Publication No. 2007-201178 discloses a protective film by applying a water-soluble resin such as PVA (polyvinyl alcohol) or PEG (polyethylene glycol) to the processed surface of the wafer in order to solve the problem caused by the debris. The laser processing apparatus which coat | covered and irradiated a pulse laser beam to a wafer through this protective film is proposed.

Patent Document 1: Japanese Patent Application Laid-Open No. Hei 10-305420 Patent Document 2: Japanese Patent Application Laid-Open No. 2007-201178 Patent Document 3: Japanese Patent Laid-Open No. 2006-140311

In the conventional protective film coating apparatus, the spin coating method which supplies a protective film liquid on a to-be-processed object while rotating the holding table which hold | maintains a to-be-processed object, expands a protective film liquid by centrifugal force, and coats a protective film liquid on the whole surface of a workpiece is common. to be. However, in the conventional spin coat method, about 90% or more of protective film liquid is discarded, and there exists a problem of being uneconomical.

Moreover, in the protective film coating apparatus which employ | adopted the conventional spin coat method, the large amount of protective film liquid scattered by the spin coat becomes a very thin debris, accumulates inside the protective film coating apparatus, takes time to clean, and is completely solid. It was difficult to get rid of debris.

In addition, there is a problem that the yarn-like debris easily floats in the air, scatters during cleaning, adheres to the workpiece, and contaminates the workpiece or contaminates the inside and outside of the protective film coating apparatus.

This invention is made | formed in view of this point, Comprising: It aims at providing the laser processing apparatus and protective film coating method provided with the economical protective film coating apparatus which suppressed the quantity of the protective film liquid to discard.

According to the invention as set forth in claim 1, a cassette is provided with a processing table for holding the workpiece, laser processing means for performing laser processing on the workpiece held on the processing table, and a cassette for accommodating a plurality of workpieces. A laser processing apparatus having a mounting table and a conveying means for conveying a workpiece from at least the cassette placed on the cassette placing table to the processing table, comprising: a holding table having a holding surface for holding the workpiece and the holding table; A protective film liquid discharge head having a slit discharge port for discharging a protective film liquid made of a water-soluble resin that forms a protective film on the surface of the workpiece to be held, and the protective film liquid discharge head can be spaced apart from the holding surface of the holding table. The first moving means for moving relatively and the protective film liquid discharge head The laser processing apparatus provided with the 2nd moving means which moves relatively in the direction parallel to the said holding surface of the holding table.

Preferably, the laser processing apparatus further includes a drive source for rotating the holding table with a rotation axis orthogonal to the holding surface passing through the center of the holding surface. Preferably, a protective film liquid discharge head is attached to a conveying means, and a 1st moving means and a 2nd moving means serve as a conveying means.

According to the invention according to claim 4, the coating method of the protective film using the laser processing apparatus according to claim 2 or 3, comprising: a holding step of holding a workpiece on the holding table, and an upper surface of the workpiece held on the holding table. A positioning step of positioning the protective film liquid discharge head at a predetermined height, and after performing the positioning step, the protective film liquid from the protective film liquid discharge head while moving the protective film liquid discharge head on the holding table while rotating the holding table. Is discharged onto the workpiece, the coating step of spirally covering the upper surface of the workpiece with a protective film liquid having a predetermined thickness, and after the coating step is carried out, the holding table is rotated to flatten and dry the protective film liquid to form a protective film. Including maintaining table rolling step forming The protective film coating method, comprising a step is provided.

According to the laser processing apparatus according to claim 1, since the protective film liquid can be discharged from the protective film liquid discharge head having the slit protective film liquid discharge port, and the protective film can be coated on the workpiece, the amount of the protective film liquid to be discarded can be suppressed. It becomes possible.

According to the invention as set forth in claim 4, the protective film liquid is discharged from the slit protective film liquid discharge port while being supplied to the upper surface of the workpiece while rotating the holding table holding the workpiece and moving the protective film liquid discharge head. A protective film liquid can be apply | coated helically, and it becomes possible to suppress the quantity of the protective film liquid discarded.

1 is a perspective view of a laser processing apparatus according to an embodiment of the present invention.
It is a schematic diagram explaining arrangement | positioning of each mechanism part of the laser processing apparatus which concerns on embodiment of this invention.
3 is a perspective view of a wafer unit in which a wafer is supported in an annular frame through a dicing tape;
4 is a perspective view of the laser beam irradiation unit.
5 is a block diagram of a laser beam generating unit.
6 is a longitudinal sectional view of the protective film liquid discharge head.
7 is an explanatory diagram of a protective film liquid coating method.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail with reference to drawings. 1, a perspective view of a laser machining apparatus 2 according to an embodiment of the invention is shown. Reference numeral 4 is an exterior cover of the laser processing apparatus 2, and the processing region 14 shown in FIG. 2 is disposed in the exterior cover 4.

A touch panel display monitor 6 is disposed on the front surface 4a of the exterior cover 4. By this display monitor 6, an operator inputs the operation instruction of an apparatus, and the operation state of an apparatus is displayed on the display monitor 6.

Reference numeral 8 denotes a cassette placing table for arranging cassettes containing a plurality of wafers inside, and is configured to be movable in the vertical direction (Z-axis direction). As shown in FIG. 3, in the wafer 11 such as a semiconductor wafer or an optical device wafer, a plurality of regions are partitioned by a plurality of division scheduled lines 13 formed in a lattice shape on the surface thereof, and in each divided region. The device 15 is formed.

The wafer 11 adheres to the dicing tape T, which is an adhesive tape, and the outer periphery of the dicing tape T is adhered to the annular frame F to constitute the wafer unit 17. Thereby, the wafer 11 is in the state supported by the annular frame F via the dicing tape T, and is accommodated in a cassette in this state.

Adjacent to the cassette placing table 8, a provisional placement region 10 for temporarily placing the wafer unit 17 taken out from the cassette 8 is provided. As best shown in the arrangement diagram of FIG. 2, on the opposite side of the cassette mounting table 8 in the Y-axis direction, the protective film coating region 12 is disposed adjacent to the temporary placement region 10. Moreover, the process area | region 14 is arrange | positioned on the extension line of the provisional arrangement area 10 in the X-axis direction. In the protective film coating area | region 12, the washing | cleaning process of washing the wafer 11 after laser processing is also implemented.

Adjacent to the cassette mounting table 8, a carrying in / outing unit (carrying-in / out means) 16 for discharging the wafer unit 17 with respect to the cassette placed on the cassette mounting table 8 is disposed.

The carry-in / out unit 16 has the clamp 17 attached to the front-end | tip of the support member 18. As shown in FIG. The annular frame F shown in FIG. 3 is clamped by this clamp 17 to carry out the wafer unit 17 from the cassette or to carry it into the cassette.

The support member 18 is fixed to the block 20, and the nut 20 which screws to the ball screw 24 is built in the block 20. As shown in FIG. One end of the ball screw 24 is connected to the pulse motor 26, and the carry-in / out unit moving mechanism 28 which moves the carry-in / out unit 16 to a Y-axis direction by the ball screw 24 and the pulse motor 26. ).

When the pulse motor 26 of the carrying-in / out unit movement mechanism 28 is driven, the ball screw 24 will rotate, and the block 20 will move to a Y-axis direction, and the support member 18 will be attached to the block 20 here. The clamp 17 connected through) moves in the Y-axis direction.

The wafer unit 17 with which the annular frame F is clamped to the clamp 17 and drawn out from the cassette is disposed on the pair of centering guides 30 arranged in the provisional deployment area 10, and the centering guide 30 Is moved in a direction close to each other, so that the centering of the wafer unit 17 is performed.

The processing table 32 located in the home position is arrange | positioned below the provisional placement area | region 10. As shown in FIG. A plurality of clamps 34 for clamping the annular frame F are arranged on the machining table 32.

The machining table 32 shown in FIG. 1 is in a state positioned at the home position, and the machining table 32 is moved in the X-axis direction and positioned in the machining region 14 as shown in FIG. 2. In 14, in order to index and convey the wafer 11 currently laser-processed, it can also move to a Y-axis direction.

An opening 36 is formed in the lower part of the side surface 4b of the exterior cover 4, and the wafer 11 held by the processing table 32 is processed through the groove position shown in FIG. It is moved between regions 14.

Reference numeral 38 denotes an upper arm movable in the Y-axis direction and the Z-axis direction. An H-shaped plate member 40 is fixed to the lower end of the upper arm 38, and the plate member 40 is annular by vacuum suction. Four suction pads 42 which suck and hold the frame F are attached.

A rotatable holding table (spinner table) 44 is disposed in the protective film covering region 12. Although not shown in particular, the some clamp which clamps the annular frame F is attached to the circumference | surroundings of the holding table 44. As shown in FIG.

The protective film liquid discharge head 46 is disposed on the lower end side surface of the upper arm 38. The protective film liquid discharge head 46 is fixed to the Z-axis moving member 48, and is formed by the protective film liquid discharge head moving mechanism 56 including the ball screw 52 and the pulse motor 54. 46 is movable up and down (Z-axis direction) along a pair of guides 50 fixed to the upper arm 38.

The upper arm 38 is attached to the Y-axis moving member 58 so as to be movable in the Z-axis direction by a moving mechanism not shown. As the moving mechanism, for example, a combination of a ball screw and a pulse motor, an air cylinder, and the like can be employed.

The Y-axis moving member 58 incorporates a nut, and the nut is screwed to the ball screw 60 extending in the Y-axis direction. A pulse motor 62 is connected to one end of the ball screw 60, and the ball screw 60 and the pulse motor 62 constitute the Y-axis moving mechanism 64 of the upper arm 38. Driving the pulse motor 62 causes the ball screw 60 to rotate, and the Y-axis moving member 58 along the pair of guides 66 fixed to the side surface 4b of the outer cover 4 in the Y-axis direction. Is moved.

Reference numeral 68 denotes a lower arm, an H-shaped plate member 70 is fixed to the lower end of the lower arm 68, and the H-shaped plate member 70 is sucked and held by the annular frame F by vacuum suction. Four suction pads 72 are arranged.

The lower arm 68 is attached to the Y-axis moving member 74 so as to be movable in the vertical direction (Z-axis direction) by a moving mechanism not shown. As a moving mechanism, the combination of a ball screw and a pulse motor, an air cylinder, etc. are employable.

A nut (not shown) is built in the Y-axis moving member 74, and the nut is screwed to a ball screw 76 extending in the Y-axis direction. A pulse motor 78 is connected to one end of the ball screw 76, and the ball screw 76 and the pulse motor 78 constitute the Y-axis moving mechanism 80 of the lower arm 68.

When the pulse motor 78 of the Y-axis moving mechanism 80 is driven, the ball screw 76 rotates, and the lower arm 68 connected to the Y-axis moving member 74 has the side surface 4b of the outer cover 4. It is moved in the Y-axis direction along a pair of guides 82 attached to it.

As shown in FIG. 4, in the processing region 14 covered by the exterior cover 4, a column 86 is placed upright on the base 84, and the laser beam irradiation unit 90 is attached to the column 86. It is. The laser beam irradiation unit 90 is composed of a laser beam generating unit 92 shown in FIG. 5 housed in a casing 88 and a condenser (processing head) 94 attached to the tip of the casing 88. An imaging unit 96 is attached to the tip of the casing 88 adjacent to the light collector 94.

As shown in FIG. 5, the laser beam generating unit 92 includes a laser oscillator 98 such as a YAG laser oscillator or a YVO4 laser oscillator, a repetition frequency setting means 100, a pulse width adjusting means 102, It includes a power adjusting means 104. Although not specifically shown, the laser oscillator 98 has a Brewster window, and the laser beam emitted from the laser oscillator 98 is a linearly polarized laser beam.

As shown in FIG. 6, the protective film liquid discharge head 46 is provided with the slit-type discharge port 106 which discharges a protective film liquid. The slit-shaped discharge port 106 extends in the direction perpendicular to the ground in FIG. The discharge port 106 is connected to the protective film liquid supply source 110. As a protective film liquid, water-soluble resin, such as PVA (polyvinyl alcohol) and PEG (polyethylene glycol), can be employ | adopted.

The protective film liquid discharge head 46 also has a suction port 108 connected to the suction source 112 formed adjacent to the slit-type discharge port 106 at the head side of the protective film liquid application direction indicated by the arrow Y1. have. The suction port 108 is also formed in a slit shape extending in the direction perpendicular to the ground.

By sucking air from the suction port 108, gas is prevented from entering the protective film liquid 114 coated on the wafer 11. Arrow Y2 is a moving direction of the wafer 11 at the time of applying the protective film liquid.

In this specification, the carrying-in / out unit 16 which has the clamp 17, the upper arm 38, its moving mechanism 64, the lower arm 68, and its moving mechanism 80 are collectively called a conveyance means. . Therefore, in the above-mentioned embodiment, the protective film liquid discharge head 46 is attached to the conveying means.

Therefore, in the present invention, the protective film liquid discharge head 46 is not only attached to the upper arm 38 but also the protective film liquid discharge head 48 is attached to the lower arm 68 or the carry-in / out unit 16. You may.

Hereinafter, the effect | action of the laser processing apparatus 2 mentioned above is demonstrated. First, the clamp 17 pulls out the first wafer unit 17 from the cassette to the provisional placement area 10, and centers the wafer unit 17 with the centering guide 30.

Subsequently, the upper arm 38 sucks the wafer unit 17, moves in the Y-axis direction, and conveys the wafer unit 17 to the holding table 44 disposed in the protective film covering region 12. The holding table 44 sucks and holds the wafer 11 through the dicing tape T, and clamps and fixes the annular frame F with a clamp (not shown).

Subsequently, as shown in FIG. 7, the protective film liquid discharge head 46 is moved from the outer peripheral side of the wafer 11 toward the center, and the protective film liquid is discharged from the slit-shaped discharge port 106 while rotating the holding table 44. Is supplied, and the protective film liquid 114 is spirally applied to the surface of the wafer 11.

Protective film liquid application | coating by raising the rotational speed of the holding table 44 at the time of protective film liquid application, for example from 2 rpm when the protective film liquid discharge head 46 is located in the outer peripheral side to 25 rpm when it is located in the inner peripheral side. It is preferable to make the application | coating speed in a point constant.

After application of the protective film liquid 114, the holding table 44 is rotated at, for example, 3000 rpm for about 30 seconds to flatten and dry the protective film liquid 114 to coat the protective film on the surface of the wafer 11.

After coating the protective film on the wafer 11 surface, the upper arm 38 sucks the wafer unit 17 and conveys the wafer unit 17 to the processing table 32 located at the home position. The wafer 11 is suction-held through the dicing tape T in the processing table 32, and the annular frame F is clamped and fixed by the clamp 34. As shown in FIG.

Subsequently, the processing table 10 is moved in the X-axis direction, positioned in the processing region 14, and aligned by the imaging unit 96, and then the wavelength having absorbency to the wafer 11 from the light collector 94. A laser beam (for example, 355 nm) is irradiated along the division scheduled line 13 to form a laser processing groove by abrasion.

During the laser processing on the first wafer 11, the clamp 17 pulls the second wafer unit 17 from the cassette to the provisional disposition region 10 and centers the centering guide 30.

After centering, the upper arm 38 conveys the second wafer unit 17 to the holding table 44 to coat the protective film on the second wafer 11. After coating the protective film, the upper arm 38 adsorbs the second wafer unit 17 and holds the wafer unit 17 until the end of processing of the first wafer 11 in a state spaced apart from the holding table 44. Put it.

When the machining of the first wafer 11 is finished, the machining table 10 is moved in the X-axis direction and positioned at the home position shown in FIG. 1. The lower arm 68 sucks the first wafer unit 17 on the work table 32, moves it in the Y-axis direction, and conveys the first wafer unit 17 on which the processing is completed up to the holding table 44. Thus, the wafer 11 after the end of processing is washed.

The 2nd wafer unit 17 hold | maintained by the upper arm 38 is conveyed to the process table 32, and is arrange | positioned on the process table 32. FIG. Subsequently, the processing table 32 is conveyed to the processing region 14 in the X-axis direction, and laser processing is performed on the second wafer 11.

During the cleaning of the first wafer 11 and during the processing of the second wafer 11, the clamp 17 draws the third wafer unit 17 from the cassette to the provisional placement region 10. Centering is performed with the centering guide 30. After centering, the upper arm 38 sucks and holds the third wafer unit 17.

The lower arm 68 transfers the first wafer unit 17 on which cleaning is completed from the holding table 44 onto the centering guide 30, and the clamp 17 of the carry-in / out unit 16 finishes processing. The first wafer unit 17 is housed in a cassette.

The carrying-in / out unit 16, the upper arm 38, and the lower arm 68 operate in this sequence hereinafter to form a protective film on the wafer 11, and then wafer 11 by abrasion processing of the laser beam. To form a laser processing groove.

In this embodiment, since the conveying means is comprised by the carry-out / out unit 16, the upper arm 38, and the lower arm 68, the wafer unit 17 is in turn from within a cassette without incurring processing waiting time. After the extraction, the protective film is coated on the wafer 11, and then laser processing can be performed.

According to this embodiment, since the protective film liquid can be discharged from the slit-shaped discharge port 106 of the protective film discharge head 46 and the protective film liquid can be applied spirally on the wafer 11, the amount of the protective film liquid to be discarded. Can be suppressed.

Moreover, since the conveying means was comprised by the carry-out / out unit 16, the upper arm 38, and the lower arm 68, it can perform laser processing on several wafer 11 efficiently without having to wait time. Can be.

In the above-described embodiment, an example in which a wafer such as a semiconductor wafer or an optical device wafer is employed as the workpiece is described. However, the workpiece is not limited to this, and other workpieces having patterns or microstructures on the surface thereof may also be used. The present invention is applicable.

8: cassette holder 10: batch area
12: protective film coating area 14: processing area
16: Carry-out unit 17: Clamp
30: centering guide 32: machining table
38: upper arm 44: holding table
46: protective film liquid discharge head 68: lower arm
90: laser beam irradiation unit 94: light collector (laser head)
106: slit-type discharge port 108: suction port

Claims (4)

A cassette placing table on which a processing table for holding a workpiece, laser processing means for performing laser processing on a workpiece held on the processing table, a cassette for accommodating a plurality of workpieces, and the cassette placing table A laser processing apparatus provided with a conveying means for conveying a workpiece to at least the said processing table from the cassette arrange | positioned at
A holding table having a holding surface for holding the workpiece,
A protective film liquid discharge head having a slit discharge port for discharging a protective film liquid made of a water-soluble resin that forms a protective film on the surface of the workpiece held by the holding table;
First moving means for moving said protective film liquid discharge head relatively relatively to said holding surface of said holding table so as to be spaced apart from each other;
Second moving means for linearly moving the protective film liquid discharge head in a direction parallel to the holding surface of the holding table;
A driving means for rotating the holding table through a rotation axis orthogonal to the holding surface passing through the center of the holding surface;
The protective film liquid discharge head is attached to the conveying means,
The said 1st moving means and the said 2nd moving means are combined with the said conveying means, The laser processing apparatus characterized by the above-mentioned. The laser processing apparatus according to claim 1, wherein the protective film liquid discharge head has a suction port formed adjacent to the slit-shaped discharge port at the head side in the protective film liquid application direction. As a coating method of a protective film using the laser processing apparatus of Claim 1 or 2,
A holding step of holding the workpiece in the holding table;
A positioning step of positioning the protective film liquid ejecting head at a predetermined height from an upper surface of the workpiece held by the holding table;
After performing the positioning step, the protective film liquid is discharged from the protective film liquid discharge head onto the workpiece while the protective film liquid discharge head is linearly moved on the holding table while rotating the holding table at a first speed. A coating step of spirally covering the upper surface with a protective film liquid having a predetermined thickness;
After the coating step, the protective film forming step of forming a protective film by rotating the holding table at a second speed faster than the first speed to planarize and dry the protective film liquid
Protective film coating method comprising a. delete

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