JP6862045B2 - Processing method - Google Patents

Description

The present invention relates to a method for processing a workpiece such as a wafer.

A device chip on which a device such as an IC or an LSI is formed is formed by carrying out a processing method for dividing the wafer on which the device is formed on the surface. Scheduled division lines arranged in a grid pattern are set on the surface of the workpiece such as the wafer, and devices are formed in each region partitioned by the scheduled division lines. In the processing method, for example, the annular cutting blade is rotated and cut into the workpiece along the planned division line to divide the workpiece to form a device chip.

A metal film serving as an electrode or a heat radiating material may be formed on the back surface side of the workpiece. When a work piece having a metal film formed on the back surface is divided by a cutting blade, the cutting blade is also cut into the metal film. Then, the metal film is stretched by the rotating cutting blade to generate protrusions called burrs. If burrs remain on the manufactured device chip, problems such as the burrs hindering proper mounting may occur when the device chip is mounted on a predetermined target.

Further, a resin film may be formed on the back surface side of the workpiece for protection and mounting of the device chip. When a workpiece having a ductile film such as a resin film or a metal film formed on the back surface is cut with the cutting blade, the cutting blade may have problems such as clogging. If cutting is continued using a cutting blade that is clogged or the like, defects such as chipping (chips) are likely to occur in the workpiece.

Therefore, a method has been proposed in which a resin film or a metal film is removed by irradiating the back surface side of the work piece with a laser beam along a planned division line before cutting the work piece with a cutting blade. If the film is removed in advance along the planned division line, the film will not be cut by the cutting blade, and the above-mentioned problems will not occur.

Japanese Unexamined Patent Publication No. 2016-42526

However, when the film is removed by irradiating the laser beam, a fixed substance called debris is generated and adheres to the workpiece. The debris may also hinder the proper mounting of the manufactured device chip, which is a problem, but it is not easy to remove the stuck debris. Further, in the process of irradiating the laser beam, it is necessary to use a laser processing apparatus which is an expensive apparatus, and there is a problem that the processing cost of the workpiece increases.

The present invention has been made in view of such a problem, and an object of the present invention is a novel processing method for dividing a workpiece such as a wafer having a film formed on the back surface side along a planned division line. To provide.

According to one aspect of the present invention, it is a method of processing a plate-shaped workpiece having a plurality of scheduled division lines and a film on the back surface, and the surface of the workpiece is formed along the scheduled division lines. a groove forming step of forming a trench by dry etching from, after performing the groove forming step, the pressing positioned in back surface side of the workpiece has a convex portion corresponding to a plurality of該分sectional planned line It is provided with a dividing step of penetrating the convex portion through the film corresponding to the groove by pressing one or both of the member and the workpiece in the direction of each other to divide the workpiece. A processing method is provided.

In one aspect of the present invention, before carrying out the groove forming step, on the back surface side of the workpiece so that the position of the convex portion of the pressing member is aligned with the planned division line of the workpiece. An arrangement step for arranging the pressing member may be performed, and in the groove forming step, a groove may be formed by dry etching from the front surface of the workpiece on which the pressing member is arranged on the back surface side.

Further, in one aspect of the present invention, the groove forming step is carried out with a support member disposed on the back surface of the work piece, and before the division step is carried out, a tape is applied to the surface of the work piece. A transfer step may be provided in which the workpiece is attached to the frame via the tape while being attached, and the back surface side of the workpiece is exposed by removing the support member.

Further, in one aspect of the present invention, the groove forming step is carried out in a state where a tape is attached to the back surface of the work piece and the work piece is attached to the frame via the tape. The convex portion of the pressing member may press and divide the film corresponding to the groove via the tape.

According to the processing method according to one aspect of the present invention, a groove is formed by performing dry etching from the surface of a work piece such as a wafer along a planned division line. In addition, a pressing member having a convex portion corresponding to the plurality of scheduled division lines is prepared. Then, a pressing member is arranged so that the convex portion is positioned on the back surface side of the workpiece, and one or both of the pressing member and the workpiece are pressed in each direction to correspond to the groove. The convex portion is passed through the film to be processed, and the workpiece is divided. Then, individual device chips are formed.

When the work piece is divided in this way, the metal film or resin film provided on the back surface side of the work piece can be divided without using a cutting blade or a laser beam. Therefore, clogging of the cutting blade does not become a problem, and debris does not occur.

Therefore, according to one aspect of the present invention, there is provided a novel processing method capable of dividing a workpiece such as a wafer having a film formed on the back surface side along a scheduled division line.

It is sectional drawing which describes the dry etching apparatus. FIG. 2A is a perspective view schematically showing a work piece, and FIG. 2B is a perspective view schematically showing a pressing member. FIG. 3A is a schematic cross-sectional view showing a state in which a pressing member is arranged on the back surface side of the work piece, and FIG. 3B is a schematic cross-sectional view showing a state in which a groove is formed in the work piece. FIG. 3C is a schematic cross-sectional view showing a state in which the workpiece is pressed toward the pressing member and the convex portion is penetrated through the film. FIG. 4A is a schematic cross-sectional view showing a state in which a work piece is attached on a support member, and FIG. 4B is a schematic cross-sectional view showing a state in which a groove is formed in the work piece. .. FIG. 5A is a schematic cross-sectional view showing a work piece attached to the frame via tape, and FIG. 5B is a convex portion on the film by pressing the pressing member toward the work piece. It is a cross-sectional schematic diagram which shows the state which penetrated. FIG. 6A is a schematic cross-sectional view showing a work piece attached to the frame via tape, and FIG. 6B is a schematic cross-sectional view showing a state in which a groove is formed in the work piece. 6 (C) is a schematic cross-sectional view showing a state in which the pressing member is pressed toward the workpiece to separate the film.

An embodiment according to the present invention will be described. First, a dry etching apparatus (plasma etching apparatus) used in the processing method according to the present embodiment will be described. FIG. 1 is a schematic cross-sectional view illustrating the dry etching apparatus 2. The dry etching apparatus 2 includes a vacuum chamber 4 in which a space for processing is formed. An opening 4a for carrying in and out the workpiece is formed on the side wall of the vacuum chamber 4.

A gate 6 for opening and closing the opening 4a is provided outside the opening 4a. An opening / closing mechanism (not shown) is connected to the gate 6, and the opening / closing mechanism opens / closes the gate 6. By opening the gate 6 to expose the opening 4a, the workpiece can be carried into the space inside the vacuum chamber 4 through the opening 4a, or the workpiece can be carried out from the space inside the vacuum chamber 4.

An exhaust port 4b is formed on the bottom wall of the vacuum chamber 4. The exhaust port 4b is connected to an exhaust unit 8 such as a vacuum pump. The lower electrode 10 is arranged in the space of the vacuum chamber 4. The lower electrode 10 is formed in a disk shape using a conductive material, and is connected to the high frequency power supply 12 outside the vacuum chamber 4.

An electrostatic chuck 14 is arranged on the upper surface of the lower electrode 10. The electrostatic chuck 14 includes, for example, a plurality of electrodes 16a and 16b that are insulated from each other, and attracts and holds the workpiece by an electric force generated between the electrodes 16a and 16b and the workpiece. The electrostatic chuck 14 of the present embodiment is configured so that the positive electrode of the DC power supply 18a can be connected to the electrode 16a and the negative electrode of the DC power supply 18b can be connected to the electrode 16b.

An upper electrode 20 formed in a disk shape using a conductive material is attached to the ceiling wall of the vacuum chamber 4 via an insulating material. A plurality of gas ejection holes 20a are formed on the lower surface side of the upper electrode 20, and the gas ejection holes 20a are formed through gas supply holes 20b and the like provided on the upper surface side of the upper electrode 20. It is connected to the. As a result, the raw material gas for dry etching can be supplied into the space of the vacuum chamber 4. The upper electrode 20 is also connected to the high frequency power supply 24 outside the vacuum chamber 4.

Next, the workpiece and the pressing member of the processing method according to the present embodiment will be described. FIG. 2A is a perspective view schematically showing the workpiece 1, and FIG. 2B is a perspective view schematically showing the pressing member 26. FIG. 3A is a cross-sectional view schematically showing the workpiece 1 and the pressing member 26 arranged under the workpiece 1. The workpiece 1 is, for example, a substantially disk-shaped wafer made of a semiconductor in which the device 5 is formed on the surface 1a.

A plurality of scheduled division lines 3 arranged in a grid pattern are set on the workpiece 1, and the device 5 is formed in each region partitioned by the scheduled division lines 3. The workpiece 1 is finally divided along the planned division line 3, and individual device chips are formed.

A film 7 is formed on the back surface 1b side of the workpiece 1. The film 7 is, for example, a metal film used as an electrode or a heat radiating material, or a resin film for protecting the workpiece 1. Further, the film 7 may be a DAF (diatouch film) or a DBF (die backside film) used when mounting a device chip formed by dividing the workpiece 1 on a predetermined mounting target. ..

The film 7 is finally divided along the scheduled division line 3. Here, since the film 7 is formed of a ductile material such as a metal film or resin, for example, when the work piece 1 is divided, the work piece 1 is cut by using a cutting blade. Then, the cutting blade is clogged due to the film 7. In addition, protrusions called burrs may be formed on the workpiece 1, and the burrs may hinder the manufacture, transfer, or mounting of the device chip.

When ablation processing using a laser beam is performed on the back surface 1b side of the workpiece 1 in order to divide the film 7, a fixed substance called debris is generated from the film 7, which is also a manufacturing of a device chip. , Transport, or may interfere with mounting. In the first place, since the laser processing device that irradiates the laser beam is expensive, there is a problem that the manufacturing cost of the device chip becomes high when the process using the laser processing device is carried out.

On the other hand, in the processing method according to the present embodiment, the pressing member 26 is used to divide the film 7 provided on the back surface 1b of the workpiece 1. When the film 7 is divided by using the pressing member 26, such a problem does not occur. The pressing member 26 has a planar shape similar to that of the workpiece 1, and a convex portion 28 corresponding to a planned division line 3 of the workpiece 1 is formed on one surface of the pressing member 26. For example, when the workpiece 1 is a wafer made of a semiconductor, the pressing member 26 is also formed by being processed from the wafer made of a semiconductor.

For example, the pressing member 26 forms a resist mask on one surface of a wafer made of a semiconductor in a region corresponding to the scheduled division line 3 of the workpiece 1, and etches the region not corresponding to the scheduled division line 3. It is formed by processing. At this time, the shape or material of the resist mask is appropriately selected so that the resist mask recedes as the etching process progresses. Then, the pressing member 26 having the tapered convex portion 28 that easily penetrates the film 7 can be formed.

The resist mask used when forming the convex portion 28 of the pressing member 26 is, for example, an inverted photomask used when forming a groove 28 (see FIG. 3B) described later in the workpiece 1. It can be formed by using it. For example, when a positive type resist mask is used to form the groove 28, a negative type resist mask is used to form the convex portion 28 of the pressing member 26. Then, a convex portion 28 having a shape corresponding to 3 is formed on the scheduled division line.

Further, the pressing member 26 may be formed by another method. For example, a mold having a shape that becomes the convex portion 28 when transferred is prepared, and a metal or resin or the like is poured into the mold to solidify the mold. It may be formed by separating it from the mold. Alternatively, the resin film material may be provided on a flat base material similar to the workpiece 1, and the mold may be pressed to solidify the resin film material.

Next, each step of the processing method according to the present embodiment will be described. The processing method involves pressing one or both of the pressing member and the workpiece to form a groove in the workpiece along the planned division line, and pressing the film corresponding to the groove. It is provided with a dividing step of penetrating the convex portion of the member and dividing the workpiece.

First, a resist mask material is applied to the surface 1a of the workpiece 1. Then, the applied resist mask material is exposed and developed using, for example, the above-mentioned photomask to carry out patterning. The resist mask 9 is formed so as to expose the surface 1a of the workpiece 1 along the scheduled division line 3 of the workpiece 1 while protecting the region other than the scheduled division line 3 from the dry etching process.

Next, the workpiece 1 is carried into the dry etching apparatus 2 (plasma etching apparatus). First, the gate 6 is lowered by the opening / closing mechanism. Next, the workpiece 1 is carried into the space of the vacuum chamber 4 through the opening 4a and placed on the electrostatic chuck 14. After that, when the electrostatic chuck 14 is operated, the workpiece 1 is attracted to and held by the electrostatic chuck 14 with the resist mask 5 on the surface 1a side exposed upward.

FIG. 3A is a cross-sectional view schematically showing a workpiece 1 carried into the dry etching apparatus 2. As shown in FIG. 3A, when the workpiece 1 is carried into the dry etching apparatus 2, the pressing member 26 is arranged under the workpiece 1 and the pressing member 26 is attached to the electrostatic chuck 14. Hold it. That is, an arrangement step of arranging the pressing member 26 on the back surface 1b side of the workpiece 1 is performed, and then dry etching is performed on the workpiece 1 on which the pressing member 26 is arranged on the back surface 1b side to form a groove. Perform the groove formation step to be formed.

Here, when the pressing member 26 is arranged under the workpiece 1, the workpiece 1 is arranged so that the position of the convex portion 28 of the pressing member 26 is aligned with the scheduled division line 3 of the workpiece 1. The pressing member 26 is arranged on the back surface 1b side.

When the workpiece 1 and the pressing member 26 are formed of a wafer made of a semiconductor, for example, the positions and directions can be aligned by using a notch or a chipped portion such as an orientation flat provided on the outer peripheral portion of the wafer. A convex portion 28 is formed on the pressing member 26. Then, by aligning the chipped portions of the workpiece 1 and the pressing member 26, the convex portion 28 of the pressing member 26 is positioned so as to correspond to the scheduled division line 3 of the workpiece 1.

After the workpiece 1 is carried into the dry etching apparatus 2, the gate 6 is raised by an opening / closing mechanism to seal the space of the vacuum chamber 4. Further, the exhaust unit 8 is operated to reduce the pressure in the space. In this state, when the raw material gas for dry etching is supplied from the gas supply source 22 at a predetermined flow rate and appropriate high-frequency power is supplied to the lower electrode 10 and the upper electrode 20 by the high-frequency power supplies 12 and 24, the lower electrode 10 and Plasma containing radicals, ions, etc. is generated between the upper electrode 20 and the electrode 20.

As a result, the surface 1a (that is, the scheduled division line 3) of the workpiece 1 not covered with the resist mask is exposed to plasma, and the workpiece 1 can be processed. The raw material gas for dry etching supplied from the gas supply source 22 is appropriately selected according to the material of the work piece and the like. Then, a groove 11 is formed in the workpiece 1 along the scheduled division line 3 by dry etching. FIG. 3B is a cross-sectional view schematically showing a state in which the groove 11 is formed in the workpiece 1.

As described above, when the pressing member 26 is arranged under the workpiece 1 and then the dry etching is performed, the material of the pressing member 26 is preferably a material having resistance to the dry etching. For example, as the pressing member 26, a substrate made of metal or resin can be used in addition to the wafer made of semiconductor.

In the dry etching, the film 7 provided on the back surface side of the wafer 1 does not necessarily have to be exposed at the bottom of the groove 11 to be formed. That is, the wafer 1 may not be removed in all directions in the thickness direction by the dry etching, and a part of the wafer 1 may remain at the bottom of the groove 11. In that case, in the dividing step described later, a part of the film 7 is pierced by the convex portion 28 of the pressing member 26 together with the film 7.

Next, the division step will be described. In the dividing step, the film 7 provided on the back surface 1b of the wafer 1 is divided along the scheduled division line 3 to divide the workpiece 1 to form individual device chips. In the dividing step, the pressing member 26 is pressed toward the workpiece 1 side, or the workpiece 1 is pressed toward the pressing member 26 side, and a force is applied from the convex portion 28 to the film 7. The division step is continuously performed inside the dry etching apparatus 2, for example.

FIG. 3C is a cross-sectional view schematically showing the dividing step. The gate 6 of the dry etching apparatus 2 is lowered to allow the roller 30 to enter the inside of the vacuum chamber 4. Then, as shown in FIG. 3C, the tape 13 is attached to the surface 1a side of the workpiece 1 by using the roller 30, and the workpiece 1 is pressed by the roller 30.

Then, the film 7 provided on the back surface 1b of the workpiece 1 is pierced by the convex portion 28 of the pressing member 26, and the convex portion 28 penetrates. Then, the workpiece 1 is pulled away from the pressing member 26 on the back surface 1b side. As a result, the workpiece 1 is divided along the scheduled division line 3 to form individual device chips.

Next, the individual device chips are carried out from the dry etching apparatus 2 in a state where the tape 13 is attached to the surface of the formed individual device chips. Then, another tape is attached to the back surface side of each device chip, the tape 13 on the front surface side is peeled off, and the resist film 9 formed so as to protect the device 5 on the front surface of the device chip is removed. .. Finally, the device chip is picked up from the tape attached to the back surface side of the device chip.

The dividing step may be performed outside the dry etching apparatus 2. In that case, the workpiece 1 in which the groove 11 is formed and rests on the pressing member 26 is carried out from the inside of the vacuum chamber 4. The film 7 is divided while the tape 13 is attached using the roller 30.

As described above, according to the processing method according to one aspect of the present invention, dry etching is performed from the surface 1a of the workpiece 1 along the scheduled division line 3 to form the groove 11. Then, by pressing one or both of the pressing member and the workpiece in each direction, the convex portion 28 of the pressing member 26 is penetrated through the film 7 corresponding to the groove 11, and the workpiece 1 is divided. To do.

In this way, when the workpiece 1 is divided by the processing method according to the present embodiment, the film 7 such as a metal film or a resin film provided on the back surface 1b side of the workpiece 1 is formed regardless of the cutting blade or the laser beam. Can be divided into. Therefore, clogging of the cutting blade due to the metal film, the resin film, or the like does not become a problem, and debris and burrs do not occur.

In the processing method according to the present embodiment, in the groove forming step, the pressing member 26 is arranged under the workpiece 1 and then the groove 11 is formed by dry etching, but the present invention is not limited to this. ..

For example, the groove forming step may be carried out in a state where a support member for supporting the workpiece 1 is arranged on the back surface 1b side of the workpiece 1. In this case, a tape is attached to the surface 1a of the workpiece 1 on which the groove 11 is formed before the dividing step is performed, and then the support member is removed to the back surface 1b side of the workpiece 1. Further carry out a transfer step to expose the. Hereinafter, such a case will be described.

FIG. 4A is a cross-sectional view schematically showing a state in which a support member 15 for supporting the workpiece 1 is arranged on the back surface 1b of the workpiece 1. Here, the support member 15 is a disk-shaped base material having a plane shape similar to the plane shape of the workpiece 1, and is, for example, a wafer made of a semiconductor, a substrate made of metal, a substrate made of resin, or the like. is there. In order to support the workpiece 1 on the support member 15, an adhesive member such as resin may be provided between the workpiece 1 and the support member 15.

After arranging the support member 15 on the back surface 1b side of the workpiece 1, a resist mask is formed to protect the device 5 on the surface 1a of the workpiece 1 from dry etching. After that, a groove forming step is carried out. In the groove forming step, the workpiece 1 in which the support member 15 is arranged on the back surface 1b side is carried into the dry etching apparatus 2, and dry etching is performed to form the groove 11 in the workpiece 1. FIG. 4B is a cross-sectional view schematically showing the workpiece 1 in which the groove forming step is carried out and the groove 11 is formed in a state where the support member 15 is arranged on the back surface 1b of the workpiece 1. ..

Next, a transfer step is performed so that the back surface 1b side of the workpiece 1 can be pressed by the pressing member 26. In the transfer step, the tape is attached to the front surface 1a side of the workpiece 1 on which the groove 11 is formed, and then the support member 15 arranged on the back surface 1b side of the workpiece 1 is removed. FIG. 5A is a cross-sectional view schematically showing a work piece 1 in which the transfer step is performed and the support member 15 is removed.

In the transfer step, first, a tape 19 stretched on an annular frame 17 is prepared, and the tape 19 is attached to the surface 1a side of the workpiece 1. Then, the workpiece 1 is attached to the frame 17 via the tape 19. Next, the support member 15 arranged on the back surface 1b side of the workpiece 1 is removed. Then, the back surface 1b side of the workpiece 1 is exposed, and the pressing member 26 can press the back surface 1b side of the workpiece 1.

Then, the division step is carried out. In FIG. 5B, the back surface 1b side of the workpiece 1 mounted on the frame 17 via the tape 19 is pressed by the pressing member 26, and the film 7 is divided along the scheduled division line 3 by the convex portion 28. It is sectional drawing which explains typically the division step. When the division step is performed, the workpiece 1 is divided to form individual device chips.

Next, the pressing member 26 is removed, and for example, the tape 19 is expanded in the outer peripheral direction by a predetermined method. Then, the gap between the formed device chips is widened, and each device chip can be easily picked up.

Further, in the processing method according to the present invention, the tape 19 stretched on the frame 17 is attached to the back surface 1b of the workpiece 1 before the groove forming step, and the workpiece 1 is attached to the frame 17. The groove forming step may be carried out on the surface. In this case, when the workpiece 1 is carried into the inside of the dry etching apparatus 2, the workpiece 1 can be handled via the frame 17, so that the workpiece 1 can be easily handled. Hereinafter, such a case will be described.

FIG. 6A is a cross-sectional view schematically showing a state in which the tape 19 stretched on the frame 17 is attached to the back surface 1b of the workpiece 1 before the groove forming step. Then, the groove forming step is carried out, and as shown in FIG. 6B, the groove 11 is formed in the workpiece 1. Next, the workpiece 1 is carried out from the dry etching apparatus 2, and the pressing member 26 is arranged on the back surface 1b side of the workpiece 1 via the tape 19. Then, the dividing step of pressing the back surface 1b side of the workpiece 1 with the pressing member 26 is performed.

FIG. 6C shows a state in which the back surface 1b side of the workpiece 1 is pressed by the pressing member 26 via the tape 19, and the film 7 corresponding to the groove 11 is divided by the convex portion 28 of the pressing member 26. It is sectional drawing which shows typically. In this case, in the dividing step, the tape 19 is divided together with the film 7 by the pressing member 26. Then, since the tape 19 remains on the device chip formed by dividing the workpiece 1, the tape 19 is peeled off from the back surface of the device chip.

If the material of the tape 19 is appropriately selected and a stretchable tape is used for the tape 19, it may be possible to divide only the film 7 without the tape 19 being divided. In that case, the tape 19 can be peeled off from the device chip by picking up the formed device chip.

In addition, the structure, method, and the like according to the above-described embodiment can be appropriately modified and implemented as long as they do not deviate from the scope of the object of the present invention.

1 Work piece 1a Front surface 1b Back surface 1c Notch 3 Scheduled division line 5 Device 7 Membrane 9 Resist film 11 Groove 13 Tape 15 Support member 17 Frame 19 Tape 2 Dry etching equipment (plasma etching equipment)
4 Vacuum chamber 4a Opening 4b Exhaust port 6 Gate 8 Exhaust unit 10 Lower electrode 12 High frequency power supply 14 Electrostatic chuck 16a, 16b Electrodes 18a, 18b DC power supply 20 Upper electrode 20a Gas ejection hole 20b Gas supply hole 22 Gas supply source 24 High frequency power supply 26 Pressing member 26a Notch 28 Convex part 30 Roller

Claims (4)

It is a processing method of a plate-shaped workpiece with a plurality of scheduled division lines and a film on the back surface.
A groove forming step of forming a groove from the surface of the workpiece along the planned division line by dry etching,
After performing groove forming step, one or both of the push member positioned on the back surface side of the workpiece has a convex portion corresponding to a plurality of該分sectional scheduled line, the workpiece, By pressing in the direction of each other, the convex portion is penetrated through the film corresponding to the groove, and the work piece is divided.
Processing method with. Before carrying out the groove forming step, an arrangement step of arranging the pressing member on the back surface side of the workpiece so that the position of the convex portion of the pressing member is aligned with the planned division line of the workpiece is performed. Carry out,
The processing method according to claim 1, wherein in the groove forming step, a pressing member forms a groove from the front surface of the workpiece arranged on the back surface side by dry etching. The groove forming step is carried out with the support member disposed on the back surface of the workpiece.
Before carrying out the dividing step, a tape is attached to the surface of the work piece, the work piece is attached to the frame via the tape, and the support member is removed to remove the back side of the work piece. The processing method according to claim 1, further comprising a transfer step for exposing. The groove forming step is carried out in a state where a tape is attached to the back surface of the work piece and the work piece is attached to the frame via the tape.
The processing method according to claim 1, wherein in the dividing step, the convex portion of the pressing member presses and divides the film corresponding to the groove via the tape.

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