PROCESSING METHOD OF WORKPIECE

There is provided a processing method of a workpiece by which the workpiece is processed. The processing method includes a thermocompression bonding step of executing thermocompression bonding of a first sheet composed of a thermoplastic resin to a front surface side of the workpiece by disposing the first sheet on the front surface side of the workpiece and heating the first sheet, a processing step of processing the workpiece together with the first sheet, and a separation step of separating the first sheet from the workpiece by moving a second sheet composed of a thermoplastic resin after executing thermocompression bonding of the second sheet to the first sheet by disposing the second sheet on the first sheet processed and heating the second sheet.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a processing method of a workpiece by which the workpiece such as a wafer is processed.

Description of the Related Art

In a manufacturing process of device chips, a wafer in which a device is formed in each of a plurality of regions marked out by a plurality of streets (planned dividing lines) arranged in a lattice manner is used. By dividing this wafer along the streets, a plurality of device chips each including the device are obtained. The device chips are incorporated into various pieces of electronic equipment such as mobile phones and personal computers.

A cutting apparatus is used for the dividing of the wafer. The cutting apparatus includes a chuck table that holds a workpiece and a cutting unit that cuts the workpiece, and an annular cutting blade is mounted on the cutting unit. By holding the wafer by the chuck table and causing the cutting blade to cut into the wafer while rotating the cutting blade, the wafer is cut and divided. Furthermore, in recent years, development of a process of dividing a wafer by laser processing by use of a laser processing apparatus has also been being advanced. The laser processing apparatus includes a chuck table that holds a workpiece and a laser irradiation unit that executes irradiation with a laser beam with a predetermined wavelength. By holding a wafer by the chuck table and irradiating the wafer with the laser beam from the laser irradiation unit, ablation processing or the like is executed for the wafer, and the wafer is divided.

When a wafer is processed by a processing apparatus such as the cutting apparatus or the laser processing apparatus, dust generated due to the processing of the wafer (processing dust) is scattered. For example, when a wafer is cut by the cutting apparatus, cutting dust of the wafer is generated in a contact region between the wafer and the cutting blade. Furthermore, when the laser processing is executed for a wafer by the laser processing apparatus, a melt (debris) is generated in the region irradiated with the laser beam in the wafer. When the processing dust such as the cutting dust or the debris is scattered, there is a fear that a front surface side (surface side on which devices are formed) of the wafer is contaminated by the processing dust. Thus, a protective tape (adhesive tape) is stuck to the front surface side of a wafer when the wafer is processed by the processing apparatus (refer to Japanese Patent Laid-open No.2007-134390). The protective tape includes a base and an adhesive applied on a surface of the base and is stuck in such a manner that the adhesive side gets contact with the front surface side of the wafer. Then, the workpiece is processed together with the protective tape in the state in which the front surface side is covered by the protective tape. This can prevent the processing dust from adhering to the front surface side of the wafer.

The protective tape is separated and removed from the workpiece after the processing of the workpiece. At this time, part of the adhesive remains on the front surface side of the wafer and the front surface side of the wafer is contaminated by a residue of the adhesive in some cases. Thus, a processing method in which a thermocompression bonding sheet that does not include an adhesive is used instead of the protective tape has been proposed (refer to Japanese Patent Laid-open No. 2020-77812). When the thermocompression bonding sheet is used, an adhesive does not remain on a wafer even when the thermocompression bonding sheet is separated after processing of the wafer, and therefore contamination due to the residue of the adhesive is avoided.

SUMMARY OF THE INVENTION

In the case of using a sheet that does not include an adhesive (thermocompression bonding sheet) when a workpiece such as a wafer is processed as described above, the sheet is thermocompression-bonded to the workpiece by being heated and softened. Then, after the processing of the workpiece is completed, a tape for separation is stuck to the sheet and the tape for separation is moved in such a direction as to get farther away from the workpiece and thereby the sheet is separated and removed from the workpiece together with the tape for separation. However, when the sheet is thermocompression-bonded to the workpiece, the softened sheet gets deformed along the shape of the front surface side of the workpiece and firmly gets close contact with the workpiece. Thus, when sticking the tape for separation to the sheet and separating the sheet from the workpiece is attempted, the bonding between the workpiece and the sheet is stronger than the bonding between the sheet and the tape for separation, and the tape for separation detaches from the sheet in the middle of the separation in some cases. That is, when the sheet is thermocompression-bonded to the workpiece, there is a problem that it becomes difficult to separate the sheet from the workpiece after processing.

The present invention is made in view of such a problem and intends to provide a processing method of a workpiece in which it is possible to surely separate a sheet fixed to the workpiece by thermocompression bonding.

In accordance with an aspect of the present invention, there is provided a processing method of a workpiece by which the workpiece is processed. The processing method includes a thermocompression bonding step of executing thermocompression bonding of a first sheet composed of a thermoplastic resin to the front surface side of the workpiece by disposing the first sheet on the front surface side of the workpiece and heating the first sheet, a processing step of processing the workpiece together with the first sheet, and a separation step of separating the first sheet from the workpiece by moving a second sheet composed of a thermoplastic resin after executing thermocompression bonding of the second sheet to the first sheet by disposing the second sheet on the first sheet processed and heating the second sheet.

Preferably, in the processing step, the workpiece is processed together with the first sheet by causing a cutting blade to cut into the workpiece and the first sheet or irradiating the workpiece and the first sheet with a laser beam or supplying gas in a plasma state to the workpiece and the first sheet.

Furthermore, preferably, the processing method of a workpiece further includes a support component disposing step of disposing a support component on a back surface side of the workpiece before the processing step. Moreover, preferably, the processing method of a workpiece further includes a unifying step of unifying the first sheet processed, before the separation step, by heating and melting the first sheet processed.

Furthermore, preferably, devices are formed on the front surface side of the workpiece.

In the processing method of a workpiece according to the one aspect of the present invention, after the second sheet is thermocompression-bonded to the processed first sheet, the first sheet is separated from the workpiece by moving the second sheet. Due to this, the separation of the first sheet can be executed in the state in which the adhesiveness between the first sheet and the second sheet is high, and detachment between the first sheet and the second sheet in the separation is prevented. As a result, it becomes possible to surely separate the first sheet firmly fixed to the workpiece by the thermocompression bonding.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment according to the one aspect of the present invention will be described with reference to the accompanying drawings. First, a configuration example of a workpiece that can be processed by a processing method of a workpiece according to the present embodiment will be described.FIG.1is a perspective view illustrating a workpiece11.

For example, the workpiece11is a circular disc-shaped wafer composed of a semiconductor material such as single-crystal silicon and includes a front surface (first surface)11aand a back surface (second surface)11bthat are substantially parallel to each other. The workpiece11is segmented into a plurality of rectangular regions by streets (planned dividing lines)13arranged in a lattice manner to intersect each other. Furthermore, a device15such as an integrated circuit (IC), large scale integration (LSI), a light emitting diode (LED), or a micro electro mechanical systems (MEMS) device is formed on the side of the front surface11aof each of the plurality of regions marked out by the streets13. However, there is no limit on the material, shape, structure, size, and so forth of the workpiece11. For example, the workpiece11may be a wafer (substrate) composed of a material such as a semiconductor other than silicon (GaAs, InP, GaN, SiC, or the like), sapphire, glass, ceramic, resin, or metal. Moreover, there is no limit also on the kind, quantity, shape, structure, size, arrangement, and so forth of the devices15.

By dividing the workpiece11along the streets13, device chips each including the device15are manufactured. A structure such as a test element group (TEG) for executing inspection of the devices15may be disposed on the side of the front surface11aof the workpiece11. Furthermore, an electrode that penetrates the workpiece11in the thickness direction (via-electrode) may be disposed in the workpiece11.

For example, the workpiece11is processed by using a processing apparatus such as a cutting apparatus, a laser processing apparatus, or a plasma treatment apparatus and is divided into a plurality of device chips. A specific example of the processing method of the workpiece11will be described.FIG.2is a flowchart illustrating the processing method of the workpiece11.

First, a thermocompression bonding step of causing thermocompression bonding of a first sheet composed of a thermoplastic resin to the side of the front surface11aof the workpiece11(step S1) is executed. The workpiece11in the thermocompression bonding step is illustrated inFIG.3AandFIG.3B. In the thermocompression bonding step, a sheet (thermocompression bonding sheet, first sheet)17is thermocompression-bonded to the side of the front surface11aof the workpiece11.

FIG.3Ais a perspective view illustrating the workpiece11on which the sheet17is disposed. The sheet17is a sheet that can be thermocompression-bonded to the workpiece11. Specifically, the sheet17is composed of a thermoplastic resin with a lower melting point than the workpiece11and does not include an adhesive (glue layer). For example, as the sheet17, an olefin-based sheet, a styrene-based sheet, a polyester-based sheet, or the like is used. As examples of the olefin-based sheet, a polyethylene sheet, a polypropylene sheet, and so forth are cited. As examples of the styrene-based sheet, a polystyrene sheet and so forth are cited. As examples of the polyester-based sheet, a polyethylene terephthalate sheet, a polyethylene naphtholate sheet, and so forth are cited. The shape and size of the sheet17are set to allow the sheet17to cover the whole of the side of the surface to which the sheet17is fixed (side of the front surface11a) in the workpiece11. For example, the sheet17is formed into a circular shape, and a diameter of the sheet17is equal to or larger than that of the workpiece11. Furthermore, the sheet17is disposed to cover the whole of the side of the front surface11aof the workpiece11. Due to this, the plurality of devices15are covered by the sheet17and are protected.

FIG.3Bis a perspective view illustrating the workpiece11to which the sheet17is thermocompression-bonded. The sheet17disposed on the side of the front surface11aof the workpiece11is heated to be thermocompression-bonded to the workpiece11. For example, the sheet17is heated and pressurized by a heating unit2. The heating unit2includes a chuck table (not illustrated) that supports the workpiece11and a roller (heat roller)4capable of heating. The roller4is formed into a circular column shape whose height is equal to or larger than a diameter of the workpiece11and internally includes a heat source. When the workpiece11is held by the chuck table and the roller4heated to a predetermined temperature is brought into contact with the sheet17and is rolled on the sheet17, the sheet17is pressed against the side of the front surface11aof the workpiece11while being heated.

The sheet17is heated to cause the temperature of the sheet17to become equal to or higher than the softening point of the sheet17and equal to or lower than the melting point of the sheet17. However, the sheet17often does not have a definite softening point. In this case, the sheet17is heated to cause the temperature of the sheet17to become equal to or higher than a temperature lower than the melting point of the sheet17by a predetermined temperature (for example, 20° C.) and equal to or lower than the melting point of the sheet17. For example, a heating temperature can be set to at least 120° C. and at most 140° C. when the sheet17is a polyethylene sheet, and the heating temperature can be set to at least 160° C. and at most 180° C. when the sheet17is a polypropylene sheet. Furthermore, the heating temperature can be set to at least 220° C. and at most 240° C. when the sheet17is a polystyrene sheet. Moreover, the heating temperature can be set to at least 250° C. and at most 270° C. when the sheet17is a polyethylene terephthalate sheet, and the heating temperature can be set to at least 160° C. and at most 180° C. when the sheet17is a polyethylene naphtholate sheet.

When the sheet17is pressed against the workpiece11while being heated, the sheet17softens, and gets deformed along the shape of the side of the front surface11aof the workpiece11, and gets close contact with the side of the front surface11aof the workpiece11. Thereby, the sheet17is thermocompression-bonded to the side of the front surface11aof the workpiece11and is fixed thereto. There is no limit on the method for heating and pressurizing the sheet17. For example, it is also possible to use a plate-shaped pressing component (plate) internally including a heat source instead of the roller4. In this case, by pressing the pressing component heated to a predetermined temperature against the sheet17, the sheet17is pressed against the side of the front surface11aof the workpiece11while being heated.

Next, a support component disposing step of disposing a support component on the side of the back surface11bof the workpiece11(step S2) is executed.FIG.4Ais a perspective view illustrating the workpiece11and a support component19in the support component disposing step.

The support component19is a component that supports the side of the back surface11bof the workpiece11and includes, for example, an annular frame21and a circular tape23. The frame21is composed of metal such as stainless steel (SUS), and a circular columnar opening21athat penetrates the frame21in the thickness direction is made at a central part of the frame21. A diameter of the opening21ais larger than that of the workpiece11. The tape23includes a film-shaped base formed into a circular shape and an adhesive (glue layer) disposed on the base. For example, the base is composed of resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate. Furthermore, the adhesive is composed of epoxy-based, acrylic-based, or a rubber-based adhesive, or the like. The adhesive may be an ultraviolet-curable resin that cures through irradiation with ultraviolet. In the state in which the workpiece11is disposed inside the opening21aof the frame21, a central part of the tape23is stuck to the side of the back surface11bof the workpiece11, and an outer circumferential part of the tape23is stuck to the frame21. Due to this, the workpiece11is supported by the frame21through the tape23.

FIG.4Bis a perspective view illustrating the workpiece11and the support component19after the support component disposing step. When the workpiece11is processed by a processing apparatus, the workpiece11is supported by the support component19for convenience of handling (conveyance, holding, and so forth) of the workpiece11. However, the support component disposing step may be omitted when the workpiece11can be handled alone without being supported by the support component19.

Next, a processing step of processing the workpiece11together with the sheet17(step S3) is executed. For example, in the processing step, the workpiece11is divided by cutting the workpiece11along the streets13(seeFIG.1and so forth) by using a cutting apparatus.

FIG.5is a perspective view illustrating a cutting apparatus10. InFIG.5, an X1-axis direction (processing feed direction, first horizontal direction) and a Y1-axis direction (indexing feed direction, second horizontal direction) are directions perpendicular to each other. Furthermore, a Z1-axis direction (vertical direction, upward-downward direction, height direction) is the direction perpendicular to the X1-axis direction and the Y1-axis direction.

The cutting apparatus10includes a chuck table (holding table)12that holds the workpiece11. The upper surface of the chuck table12is a flat surface substantially parallel to the horizontal plane (X1Y1plane) and configures a circular holding surface that holds the workpiece11. The holding surface of the chuck table12is connected to a suction source (not illustrated) such as an ejector through a flow path (not illustrated) formed inside the chuck table12, a valve (not illustrated), and so forth. To the chuck table12, a movement mechanism (not illustrated) of a ball screw system and a rotational drive source (not illustrated) such as a motor are coupled. The movement mechanism moves the chuck table12along the X1-axis direction. The rotational drive source rotates the chuck table12around a rotation axis substantially parallel to the Z1-axis direction.

Furthermore, the cutting apparatus10includes a cutting unit14disposed over the chuck table12. The cutting unit14includes a cylindrical housing16, and a circular columnar spindle (not illustrated) disposed along the Y1-axis direction is housed in the housing16. A tip part (one end part) of the spindle is exposed to the external of the housing16, and a rotational drive source (not illustrated) such as a motor is coupled to a base end part (the other end part) of the spindle. An annular cutting blade18is mounted on the tip part of the spindle. The cutting blade18rotates around a rotation axis substantially parallel to the Y1-axis direction at a predetermined rotation speed by power transmitted from the rotational drive source through the spindle.

As the cutting blade18, for example, a cutting blade of a hub type (hub blade) is used. The hub blade includes an annular base composed of a metal or the like and an annular cutting edge formed along the outer circumferential edge of the base. The cutting edge of the hub blade is configured by an electroformed abrasive stone including abrasive grains composed of diamond or the like and a bond such as a nickel plated layer that fixes the abrasive grains. Furthermore, it is also possible to use a cutting blade of a washer type (washer blade) as the cutting blade18. The washer blade is configured by only an annular cutting edge including abrasive grains composed of diamond or the like and a bond that is composed of a metal, ceramic, a resin, or the like and fixed the abrasive grains.

The cutting blade18mounted in the cutting unit14is covered by a blade cover20fixed to a tip part of the housing16. The blade cover20includes a pair of connecting parts22connected to a tube (not illustrated) that supplies liquid (cutting liquid) such as purified water and a pair of nozzles24connected to the pair of connecting parts22. The pair of nozzles24are disposed to sandwich the cutting blade18on both surface sides (front and back surface sides) of a lower end part of the cutting blade18. Furthermore, a supply port (not illustrated) that opens toward the cutting blade18is formed in each of the pair of nozzles24. When the cutting liquid is supplied to the pair of connecting parts22, the cutting liquid flows into the pair of nozzles24, and the cutting liquid is supplied from the supply ports of the nozzles24toward both surfaces (front and back surfaces) of the cutting blade18. By this cutting liquid, the workpiece11and the cutting blade18are cooled, and dust generated due to the cutting processing (cutting dust) is washed away.

A movement mechanism (not illustrated) of a ball screw system that moves the cutting unit14along the Y1-axis direction and the Z1-axis direction is coupled to the cutting unit14. By the movement mechanism, the position of the cutting blade18in the indexing feed direction, the depth of cutting into the workpiece11regarding the cutting blade18, and so forth are adjusted.

When the workpiece11is cut by the cutting apparatus10, first, the workpiece11is disposed over the chuck table12with the interposition of the tape23. At this time, the workpiece11is disposed in such a manner that the side of the front surface11a(side of the sheet17) is oriented upward and the side of the back surface11b(side of the tape23) faces the holding surface of the chuck table12. When a suction force (negative pressure) of the suction source is caused to act on the holding surface of the chuck table12in this state, the workpiece11is sucked and held by the chuck table12with the interposition of the tape23.

Next, the chuck table12is rotated, and a length direction of the predetermined street13(seeFIG.1) is adjusted to the X1-axis direction. Furthermore, the position of the cutting unit14in the Y1-axis direction is adjusted to cause the cutting blade18to be disposed on an extension line of the predetermined street13. Moreover, the height of the cutting unit14(position in the Z1-axis direction) is adjusted to cause the lower end of the cutting blade18to be disposed on the lower side relative to the back surface11bof the workpiece11(upper surface of the tape23). Then, the chuck table12is moved along the X1-axis direction while the cutting blade18is rotated. This causes the chuck table12and the cutting blade18to relatively move along the X1-axis direction and causes the cutting blade18to cut into the workpiece11along the street13. As a result, the workpiece11and the sheet17are cut and divided along the street13. Furthermore, in the region cut by the cutting blade18in the workpiece11and the sheet17, a groove (cut groove)25that reaches the back surface11bof the workpiece11from the upper surface of the sheet17is formed along the street13.

Thereafter, by repeating a similar procedure, the workpiece11and the sheet17are cut along all streets13and the grooves25are formed. As a result, the workpiece11is divided into a plurality of device chips that each include the device15(seeFIG.1and so forth) and to which individual pieces of the sheet17adhere.

When the workpiece11is cut by the cutting blade18, cutting dust is generated in the contact region between the workpiece11and the cutting blade18and the cutting dust gets caught in the rotation of the cutting blade18and is scattered. However, because the side of the front surface11aof the workpiece11is covered by the sheet17, the cutting dust does not adhere to the front surface11aof the workpiece11and the devices15. This avoids contamination of the workpiece11and the devices15due to the cutting dust.

In the processing step, the workpiece11may be divided along the streets13(seeFIG.1and so forth) by using the laser processing apparatus.FIG.6is a perspective view illustrating a laser processing apparatus30. InFIG.6, an X2-axis direction (processing feed direction, first horizontal direction) and a Y2-axis direction (indexing feed direction, second horizontal direction) are directions perpendicular to each other. Furthermore, a Z2-axis direction (vertical direction, upward-downward direction, height direction) is the direction perpendicular to the X2-axis direction and the Y2-axis direction.

The laser processing apparatus30includes a chuck table (holding table)32that holds the workpiece11. The configuration and functions of the chuck table32are similar to those of the chuck table12(seeFIG.5) of the cutting apparatus10. Furthermore, to the chuck table32, a movement mechanism (not illustrated) of a ball screw system and a rotational drive source (not illustrated) such as a motor are coupled. The movement mechanism moves the chuck table32along the X2-axis direction and the Y2-axis direction. The rotational drive source rotates the chuck table32around a rotation axis substantially parallel to the Z2-axis direction.

Moreover, the laser processing apparatus30includes a laser irradiation unit34that executes irradiation with a laser beam. The laser irradiation unit34includes a laser oscillator (not illustrated) of a YAG laser, a YVO4laser, a YLF laser, or the like and a laser processing head36disposed over the chuck table32. An optical system that guides a laser beam of pulse oscillation emitted from the laser oscillator to the workpiece11is housed in the laser processing head36and the optical system includes optical elements such as a collecting lens that focuses the laser beam. Laser processing is executed for the workpiece11by a laser beam38with which irradiation is executed from the laser irradiation unit34.

When the workpiece11is processed by the laser processing apparatus30, first, the workpiece11is disposed over the chuck table32with the interposition of the tape23. At this time, the workpiece11is disposed in such a manner that the side of the front surface11a(side of the sheet17) is oriented upward and the side of the back surface11b(side of the tape23) faces the holding surface of the chuck table32. When a suction force (negative pressure) of a suction source is caused to act on the holding surface of the chuck table32in this state, the workpiece11is sucked and held by the chuck table32with the interposition of the tape23.

Next, the chuck table32is rotated and the length direction of the predetermined street13(seeFIG.1) is adjusted to the X2-axis direction. Furthermore, the position of the chuck table32in the Y2-axis direction is adjusted in such a manner that the region to be irradiated with the laser beam38overlaps with an extension line of the predetermined street13. Moreover, the optical system of the laser irradiation unit34is adjusted to cause a focal point of the laser beam38to be positioned to the same height (position in the Z2-axis direction) as the front surface11aor the inside of the workpiece11. Then, the chuck table32is moved along the X2-axis direction while irradiation with the laser beam38from the laser processing head36is executed. This causes the chuck table32and the laser beam38to relatively move along the X2-axis direction and causes the side of the front surface11aof the workpiece11to be irradiated with the laser beam38along the street13.

Irradiation conditions of the laser beam38are set to cause ablation processing to be executed for the workpiece11, for example. Specifically, a wavelength of the laser beam38is set to cause at least part of the laser beam38to be absorbed by the workpiece11. That is, the laser beam38is a laser beam having absorbability with respect to the workpiece11. Furthermore, other irradiation conditions of the laser beam38are also set as appropriate to cause the ablation processing to be properly executed for the workpiece11. For example, when the workpiece11is a single-crystal silicon wafer, irradiation conditions of the laser beam38can be set as follows.

Average output power: 2 W

When the workpiece11is irradiated with the laser beam38along the street13, the region irradiated with the laser beam38(processed region) in the workpiece11is removed by ablation. Furthermore, the region that overlaps with the processed region in the workpiece11in the sheet17also ruptures due to the irradiation with the laser beam38, impingement of a scattered object generated due to the ablation of the workpiece11, and so forth. As a result, the workpiece11and the sheet17are divided along the street13. Moreover, in the region processed by the laser beam38in the workpiece11and the sheet17, a groove (laser processed groove)27that reaches the back surface11bof the workpiece11from the upper surface of the sheet17is formed along the street13.

Thereafter, by repeating a similar procedure, irradiation with the laser beam38is executed along all streets13and the grooves27are formed. As a result, the workpiece11is divided into a plurality of device chips that each include the device15(seeFIG.1and so forth) and to which individual pieces of the sheet17adhere. When it is difficult to divide the workpiece11and the sheet17by one time of scanning with the laser beam38, irradiation with the laser beam38may be executed a plurality of times along each street13.

When the ablation processing is executed for the workpiece11, a melt (debris) of the workpiece11is generated and scattered. However, because the side of the front surface11aof the workpiece11is covered by the sheet17, the debris does not adhere to the front surface11aof the workpiece11and the devices15. This avoids contamination of the workpiece11and the devices15due to the debris.

Furthermore, in the processing step, plasma treatment may be executed for the workpiece11. For example, by executing the plasma etching for the workpiece11by using the plasma treatment apparatus, the workpiece11is divided along the streets13(seeFIG.1and so forth) (plasma dicing).

FIG.7is a partially sectional front view illustrating a plasma treatment apparatus (plasma etching apparatus)40. The plasma treatment apparatus40includes a chamber42with a rectangular parallelepiped shape. The chamber42includes a bottom wall42a, an upper wall42b, a first sidewall42c, a second sidewall42d, a third sidewall42e, and a fourth sidewall (not illustrated). The inside of the chamber42is equivalent to a treatment space44in which plasma treatment is executed.

An opening46for carrying-in and carrying-out of the workpiece11is made in the second sidewall42d. A gate (opening-closing door)48that opens and closes the opening46is disposed outside the opening46. The gate48is connected to an opening-closing mechanism50, and the opening-closing mechanism50moves the gate48along a vertical direction (upward-downward direction). For example, the opening-closing mechanism50is configured by an air cylinder52including a piston rod54. The air cylinder52is fixed to the bottom wall42aof the chamber42with the interposition of a bracket56, and an upper end part of the piston rod54is coupled to the gate48. When the gate48is lowered by the opening-closing mechanism50, the opening46is exposed. This makes it possible to carry in the workpiece11to the treatment space44through the opening46or carry out the workpiece11from the treatment space44through the opening46.

A gas discharge port58that connects the internal and external of the chamber42is formed in the bottom wall42aof the chamber42. A gas discharge mechanism60for reducing the pressure of the treatment space44is connected to the gas discharge port58. The gas discharge mechanism60is configured by a vacuum pump, for example.

In the treatment space44, a lower electrode62and an upper electrode64are disposed to face each other. The lower electrode62is composed of an electrically-conductive material and includes a holding part66with a circular disc shape and a circular columnar support part68that protrudes downward from a central part of the lower surface of the holding part66. The support part68is inserted in an opening70formed in the bottom wall42aof the chamber42. An annular insulating component72is disposed between the bottom wall42aand the support part68in the opening70, and the chamber42and the lower electrode62are insulated by the insulating component72. Furthermore, the lower electrode62is connected to a high-frequency power supply74at the external of the chamber42.

A recess part is formed on the upper surface side of the holding part66, and a circular disc-shaped table76that holds the workpiece11is disposed in this recess part. The upper surface of the table76configures a flat holding surface76athat holds the workpiece11. The holding surface76ais connected to a suction source80such as an ejector through a flow path (not illustrated) formed inside the table76and a flow path78formed inside the lower electrode62.

Moreover, a cooling flow path82is formed inside the holding part66. One end side of the cooling flow path82is connected to a refrigerant circulation mechanism86through a refrigerant introduction path84formed in the support part68. Furthermore, the other end side of the cooling flow path82is connected to the refrigerant circulation mechanism86through a refrigerant discharge path88formed in the support part68. When the refrigerant circulation mechanism86is actuated, a refrigerant flows in the refrigerant introduction path84, the cooling flow path82, and the refrigerant discharge path88sequentially, and the lower electrode62is cooled.

The upper electrode64is composed of an electrically-conductive material and includes a gas ejecting part90with a circular disc shape and a circular columnar support part92that protrudes upward from a central part of the upper surface of the gas ejecting part90. The support part92is inserted in an opening94formed in the upper wall42bof the chamber42. An annular insulating component96is disposed between the upper wall42band the support part92in the opening94, and the chamber42and the upper electrode64are insulated by the insulating component96. Furthermore, the upper electrode64is connected to a high-frequency power supply98at the external of the chamber42.

A support arm102coupled to a raising-lowering mechanism100is mounted on an upper end part of the support part92. When the support arm102is raised and lowered by the raising-lowering mechanism100, the upper electrode64moves (rises and lowers) along the vertical direction (upward-downward direction).

A plurality of ejection ports104are made on the lower surface side of the gas ejecting part90. The ejection ports104are connected to a first gas supply source110and a second gas supply source112through a flow path106formed inside the gas ejecting part90and a flow path108formed inside the support part92. The first gas supply source110and the second gas supply source112can supply gases of components different from each other to the flow path108.

The respective constituent elements of the plasma treatment apparatus40(opening-closing mechanism50, gas discharge mechanism60, high-frequency power supply74, suction source80, refrigerant circulation mechanism86, high-frequency power supply98, raising-lowering mechanism100, first gas supply source110, second gas supply source112, and so forth) are connected to a controller (control unit, control device)114that controls the plasma treatment apparatus40. The controller114generates a control signal that controls operation of each of the constituent elements of the plasma treatment apparatus40. For example, the controller114is configured by a computer and includes a calculating section that executes calculation necessary for operation of the plasma treatment apparatus40and a storing section that stores various kinds of information (data, program, and so forth) used for the operation of the plasma treatment apparatus40. The calculating section includes a processor such as a central processing unit (CPU). Moreover, the storing section is configured to include a memory such as a read only memory (ROM) or a random access memory (RAM).

When plasma etching is executed for the workpiece11by the plasma treatment apparatus40, first, the gate48of the plasma treatment apparatus40is lowered by the opening-closing mechanism50, and the opening46is exposed. Then, by a conveying mechanism (not illustrated), the workpiece11is carried in to the treatment space44of the chamber42through the opening46and is disposed over the table76. At the time of the carrying-in of the workpiece11, it is preferable to raise the upper electrode64by the raising-lowering mechanism100to widen the interval between the lower electrode62and the upper electrode64in advance.

Next, a negative pressure of the suction source80is caused to act on the holding surface76aof the table76, and the workpiece11is sucked and held by the table76. Furthermore, the gate48is raised by the opening-closing mechanism50, and the opening46is closed to seal the treatment space44. Moreover, a height of the upper electrode64is adjusted by the raising-lowering mechanism100to cause the upper electrode64and the lower electrode62to have a predetermined positional relationship suitable for the plasma etching. Then, the gas discharge mechanism60is actuated to set the treatment space44to a pressure-reduced state (for example, at least 50 Pa and at most 300 Pa). In the case in which it becomes difficult to hold the workpiece11over the table76by the negative pressure of the suction source80when the pressure of the treatment space44is reduced, the workpiece11is held over the table76by an electric force (typically electrostatic attraction) or the like. For example, a plurality of electrodes are buried inside the table76. By applying a predetermined voltage to these electrodes, a Coulomb force can be caused to act between the table76and the workpiece11and suction adhesion of the workpiece11, to the table76can be achieved. That is, the table76functions as an electrostatic chuck table.

Then, gas for etching (etching gas) is supplied from the first gas supply source110or the second gas supply source112to between the lower electrode62and the upper electrode64through the flow path108, the flow path106, and the plurality of ejection ports104. Furthermore, predetermined high-frequency power (for example, at least 1000 W and at most 3000 W) is given to the lower electrode62and the upper electrode64. As a result, the etching gas that exists between the lower electrode62and the upper electrode64becomes a plasma state containing ions and radicals. Then, the gas in the plasma state is supplied to the workpiece11, and the plasma etching is executed for the workpiece11.

FIG.8is a sectional view illustrating part of the workpiece11for which the plasma etching is executed. When the plasma etching is executed for the workpiece11, a mask29is formed on the sheet17. For example, the mask29is formed by applying a resist composed of a photosensitive resin on the sheet17and patterning the resist to expose regions that overlap with the streets13in the sheet17. However, there is no limit on the material and the forming method of the mask29. For example, the mask29composed of a water-soluble resin may be formed by applying, on the sheet17, a film composed of the water-soluble resin such as polyvinyl alcohol (PVA), polyethylene glycol (PEG), polyethylene oxide (PEO), or polyvinyl pyrrolidone (PVP) and thereafter patterning this film by irradiation with a laser beam, or the like.

The workpiece11is disposed over the table76in such a manner that the side of the front surface11a(side of the sheet17) is oriented upward and the side of the back surface11b(side of the tape23) faces the holding surface76a. Then, gas (etching gas)116in the plasma state is supplied to the sheet17and the workpiece11through the openings of the mask29. Thereby, regions that overlap with the streets13in the workpiece11and the sheet17are removed by etching and grooves31that reach the back surface11bof the workpiece11from the upper surface of the sheet17are formed along the streets13. As a result, the workpiece11and the sheet17are divided along the streets13.

The plasma treatment apparatus40illustrated inFIG.7can execute etching of the workpiece11and the sheet17by using etching gases of different components. For example, the plasma treatment apparatus40turns gas supplied from the first gas supply source110to plasma to use it for etching of the sheet17, and turns gas supplied from the second gas supply source112to plasma to use it for etching of the workpiece11.

When the plasma etching is executed for the workpiece11and the sheet17, part of the component of the etching gas adheres onto the workpiece11and is deposited in some cases. However, because the side of the front surface11aof the workpiece11is covered by the sheet17, the deposited object does not adhere to the front surface11aof the workpiece11and the devices15. This avoids contamination of the workpiece11and the devices15due to the deposited object. Furthermore, after the plasma etching of the workpiece11and the sheet17, treatment to remove the mask29is executed. At this time, because the side of the front surface11aof the workpiece11is covered by the sheet17, a chemical or the like for removing the mask29can be prevented from adhering to the front surface11aof the workpiece11and the devices15.

As described above, in the processing step, the workpiece11is processed together with the sheet17by causing the cutting blade18(seeFIG.5) to cut into the workpiece11and the sheet17or irradiating the workpiece11and the sheet17with the laser beam38(seeFIG.6) or supplying the gas116(seeFIG.8) in the plasma state to the workpiece11and the sheet17. However, the kind and contents of the processing executed for the workpiece11and the sheet17in the processing step are not limited to the above description.

Next, a unifying step of unifying the processed sheet17(step S4) is executed. In the unifying step, by heating the sheet17in the state of being divided into a plurality of individual pieces and melting the sheet17, the plurality of individual pieces are joined and the sheet17is unified.

FIG.9Ais a perspective view illustrating the workpiece11and the sheet17in the unifying step. For example, the sheet17is heated by a heating unit120. The heating unit120includes a chuck table (not illustrated) that supports the workpiece11and a heat source122that heats the sheet17. The heating unit120may be included in the processing apparatus that processes the workpiece11in the processing step or may be installed independently of the processing apparatus. For example, the heat source122includes a heat generating mechanism such as a heating wire and a blast mechanism such as a fan, and heats gas such as air and jets the gas as a hot wind124. The sheet17is heated by holding the workpiece11by the chuck table and blowing the hot wind124from the heat source122into the sheet17.

The sheet17is heated until the temperature of the sheet17reaches the melting point of the sheet17. Thereby, the individual pieces of the sheet17each melt and are joined to each other, so that the grooves25formed in the sheet17disappear. As a result, the sheet17is unified to become one circular component.FIG.9Bis a perspective view illustrating the workpiece11and the sheet17after the unifying step. When the unifying step is executed, the sheet17is unified and returns to a state similar to that before the processing (seeFIG.4B). There is no limit on the heating method of the sheet17. For example, the sheet17may be heated by using an infrared lamp as the heat source122and irradiating the sheet17with infrared from the infrared lamp.

Next, a separation step of separating the sheet17from the workpiece11(step S5) is executed. In the separation step, a second sheet composed of a thermoplastic resin is thermocompression-bonded to the sheet17and thereafter the sheet17is separated from the workpiece11by moving the second sheet. For example, a separating apparatus is used for the separation of the sheet17.

FIG.10is a perspective view illustrating a separating apparatus130. InFIG.10, an X3-axis direction (first horizontal direction) and a Y3-axis direction (second horizontal direction) are directions perpendicular to each other. Furthermore, a Z3-axis direction (vertical direction, upward-downward direction, height direction) is the direction perpendicular to the X3-axis direction and the Y3-axis direction. The separating apparatus130may be included in the processing apparatus that processes the workpiece11in the processing step or may be installed independently of the processing apparatus.

The separating apparatus130includes a chuck table (holding table)132that holds the workpiece11and a separating unit134that separates the sheet17from the workpiece11. The separating apparatus130holds the workpiece11to which the sheet17is fixed by the chuck table132, causes thermocompression bonding of a sheet (sheet for separation, second sheet)33composed of a thermoplastic resin to the sheet17, and separates the sheet17and the sheet33from the workpiece11. The upper surface of the chuck table132is a flat surface substantially parallel to the horizontal plane (X3Y3plane) and configures a circular holding surface that holds the workpiece11. The holding surface of the chuck table132is connected to a suction source (not illustrated) such as an ejector through a flow path (not illustrated) formed inside the chuck table132, a valve (not illustrated), and so forth.

The separating unit134includes a holding mechanism136that holds the sheet33. For example, the holding mechanism136has an air cylinder138including a piston rod140, and the air cylinder138raises and lowers the piston rod140along the Z3-axis direction. A support component142with a rectangular parallelepiped shape is fixed to a lower end part of the piston rod140.

Furthermore, a grasping mechanism144that grasps the sheet33is mounted on the support component142. The grasping mechanism144includes a sidewall144awith a flat plate shape and a pair of flat plate-shaped grasping components144band144cthat protrude along the Y3-axis direction from a side surface of the sidewall144a. The grasping components144band144care disposed substantially in parallel to each other along the Y3-axis direction. The grasping component144bis coupled to a lower end part of the sidewall144a, and the grasping component144cis disposed to overlap with the grasping component144babove the grasping component144b. Moreover, a movement mechanism (not illustrated) is coupled to the grasping component144cand the movement mechanism slides the grasping component144cin the Z3-axis direction along the sidewall144a. In the state in which an end part of the sheet33is inserted between the pair of grasping components144band144c, the grasping component144cis lowered to be brought close to the grasping component144b. This causes the end part of the sheet33to be grasped by the grasping components144band144c.

The sheet33is a sheet composed of a thermoplastic resin that can be thermocompression-bonded to the sheet17, and does not include an adhesive (glue layer). Examples of the material of the sheet33are similar to those of the sheet17. That is, as the sheet33, an olefin-based sheet, a styrene-based sheet, a polyester-based sheet, or the like can be used. For example, the material of the sheet17and the material of the sheet33are the same. Alternatively, the material of the sheet17and the material of the sheet33may be different and the melting point of the sheet33may be lower than that of the sheet17. For example, the sheet33is formed into a strip shape, is fixed to a roller (not illustrated), and is taken up. Furthermore, a tip of the sheet33sent out from the roller is grasped by the pair of grasping components144band144c.

Moreover, the separating unit134includes a heating mechanism146that heats the sheet33. For example, the heating mechanism146has an air cylinder148including a piston rod150, and the air cylinder148raises and lowers the piston rod150along the Z3-axis direction. The air cylinder148is disposed adjacent to the air cylinder138in the Y3-axis direction. A heating component (heating plate)152is fixed to a lower end part of the piston rod150. For example, the heating component152is a flat plate-shaped component composed of a metal and is disposed substantially in parallel to the X3-axis direction and the Z3-axis direction. Furthermore, a heat source such as a heating wire is disposed inside the heating component152, and the heating component152is heated to a predetermined temperature by heat generation of the heat source. When the sheet33is held by the holding mechanism136, part of the sheet33is disposed at a position that overlaps with the heating component152.

Moreover, the separating unit134includes a cutting mechanism154that cuts the sheet33. For example, the cutting mechanism154has an air cylinder156including a piston rod158and the air cylinder156raises and lowers the piston rod158along the Z3-axis direction. A cutter (blade)160is mounted on a lower end part of the piston rod158. The cutter160is a circular disc-shaped component composed of a metal or the like and is disposed substantially in parallel to the X3-axis direction and the Z3-axis direction. Furthermore, a rotational drive source (not illustrated) such as a motor is coupled to the cutter160and the rotational drive source rotates the cutter160around a rotation axis substantially parallel to the Y3-axis direction. Moreover, the cutting mechanism154includes a support pedestal162that supports the sheet33. For example, the support pedestal162is a rectangular parallelepiped component composed of a metal, a resin, or the like and is disposed under the sheet33. Furthermore, a groove162ais made along the X3-axis direction on the upper surface side of the support pedestal162. The width of the groove162ais wider than that of the cutter160and a lower end part of the cutter160can be inserted in the groove162a.

A movement mechanism (not illustrated) of a ball screw system included in the separating apparatus130is coupled to the separating unit134. The movement mechanism moves the holding mechanism136and the heating mechanism146along the Y3-axis direction. Moreover, the movement mechanism moves the cutting mechanism154along the X3-axis direction and the Y3-axis direction independently of the holding mechanism136and the heating mechanism146.

When the sheet17is separated from the workpiece11by using the separating apparatus130, first, the workpiece11is disposed over the holding surface of the chuck table132with the interposition of the tape23. When a suction force (negative pressure) of the suction source is caused to act on the holding surface of the chuck table132in this state, the workpiece11is sucked and held by the chuck table132with the interposition of the tape23.

Next, the holding mechanism136and the heating mechanism146are moved and the sheet33and the heating component152are disposed above the workpiece11. One end side of the sheet33is grasped by the grasping mechanism144and the other end side of the sheet33is taken up by the roller (not illustrated). In addition, the sheet33is positioned to overlap with the sheet17fixed to the workpiece11in the state in which the sheet33is stretched between the grasping mechanism144and the roller. Furthermore, the heating component152is positioned to overlap with the sheet17and the sheet33.

Next, the piston rod150is lowered while the heating component152is heated to a predetermined temperature. Due to this, the heating component152gets contact with the sheet33located directly under it and the sheet33is heated. Moreover, the sheet33is pressed down by the heating component152and is pressed against the sheet17fixed to the workpiece11. This causes the sheet33to be heated and pressurized and be thermocompression-bonded to the sheet17. The heating temperature of the sheet33is set as appropriate to cause the sheet33to be thermocompression-bonded to the sheet17. Specific examples of the heating temperature of the sheet33are similar to those of the heating temperature of the sheet17in the thermocompression bonding step (seeFIG.3B).

Next, the positions of the holding mechanism136and the support pedestal162are adjusted to cause the sheet33to be supported by the upper surface side of the support pedestal162. Furthermore, the position of the cutting mechanism154is adjusted to cause the cutter160to overlap with the groove162aof the support pedestal162. Then, the piston rod158is lowered and the lower end part of the cutter160is inserted into the groove162aof the support pedestal162. Thereafter, the cutter160is caused to cut into the sheet33by moving the cutting mechanism154along the X3-axis direction while rotating the cutter160. Thereby, the sheet33is cut and the tip side of the sheet33(on the side of the grasping mechanism144) is cut off.

FIG.11Ais a partial sectional front view illustrating the sheet17to which the sheet33has been thermocompression-bonded. When the sheet33is pressed against the sheet17while being heated by the heating component152(seeFIG.10), the sheet33and a region17athat gets contact with the sheet33in the sheet17are heated and the sheet33is thermocompression-bonded to the region17aof the sheet17. Due to this, the sheet17and the sheet33are joined and the sheet33firmly gets close contact with the sheet17.

FIG.11Bis a partial sectional front view illustrating the sheet17separated from the workpiece11. When the grasping mechanism144is moved toward the other end side of the sheet17after the sheet33is thermocompression-bonded to the one end part of the sheet17, the sheet33is pulled by the grasping mechanism144and the one end part of the sheet17follows the sheet33and moves toward the other end side of the sheet17. This causes the sheet17to be separated from the workpiece11. However, there is no limit on the direction in which the sheet33is pulled. For example, the sheet33may be pulled upward to separate the sheet17by raising the grasping mechanism144along the Z3-axis direction.

By the above-described separation step, the sheet17is separated from the workpiece11. Because the sheet17is composed of the thermoplastic resin that does not include an adhesive (glue layer), the adhesive does not remain on the side of the front surface11aof the workpiece11after the separation of the sheet17. This avoids contamination of the workpiece11and the devices15(seeFIG.1) due to a residue of the adhesive. Moreover, in the separation step, the sheet17is separated from the workpiece11by using the sheet33fixed to the sheet17by the thermocompression bonding. Due to this, even when the sheet17is firmly in close contact with the workpiece11through thermocompression bonding, the adhesiveness between the sheet17and the sheet33can be made equivalent to or higher than the adhesiveness between the workpiece11and the sheet17and it is possible to prevent the sheet33from detaching from the sheet17in the separation of the sheet17.

As above, in the processing method of a workpiece according to the present embodiment, after the sheet33is thermocompression-bonded to the processed sheet17, the sheet17is separated from the workpiece11by moving the sheet33. Due to this, the separation of the sheet17can be executed in the state in which the adhesiveness between the sheet17and the sheet33is high, and detachment between the sheet17and the sheet33in the separation is prevented. As a result, it becomes possible to surely separate the sheet17firmly fixed to the workpiece11by the thermocompression bonding.

In the above-described embodiment, description has been made about the example in which the sheet17is separated from the workpiece11after the unifying step (seeFIG.9AandFIG.9B) of unifying the processed sheet17is executed. However, it is also possible to omit the unifying step. In this case, the whole of the sheet17is separated from the workpiece11by fixing a sheet for separation to the whole of the processed sheet17. Another example of the separation step will be described with reference toFIG.12AandFIG.12B.

FIG.12Ais a perspective view illustrating the sheet17to which a sheet (sheet for separation, second sheet)35is thermocompression-bonded. After execution of the processing step (seeFIG.5toFIG.8), the sheet35composed of a plastic resin is thermocompression-bonded to the processed sheet17. The sheet35is a sheet composed of a thermoplastic resin that can be thermocompression-bonded to the sheet17, and does not include an adhesive (glue layer). Examples of the material of the sheet35are similar to those of the sheet17. That is, as the sheet35, an olefin-based sheet, a styrene-based sheet, a polyester-based sheet, or the like can be used. For example, the material of the sheet17and the material of the sheet35are the same. Alternatively, the material of the sheet17and the material of the sheet35may be different and the melting point of the sheet35may be lower than that of the sheet17. The shape and the size of the sheet35are set to allow the sheet35to cover the whole of the sheet17. For example, the sheet35is formed into a circular shape and a diameter of the sheet35is equal to or larger than that of the sheet17. However, there is no limit on the shape of the sheet35. For example, the sheet35may be formed into a rectangular shape having a length and a width equal to or larger than the diameter of the sheet17.

In the separation step, the sheet35is thermocompression-bonded to the sheet17divided into a plurality of individual pieces. Specifically, first, the sheet35is disposed on the side of the front surface11aof the workpiece11to cover all individual pieces of the sheet17. Next, the sheet35is pressed against the sheet17while being heated. For example, the sheet35is heated and pressurized by the above-described heating unit2(seeFIG.3B). This causes the sheet35to soften and get close contact with the sheet17, so that the sheet35is thermocompression-bonded to the sheet17. The heating temperature of the sheet35is set as appropriate to cause the sheet35to be thermocompression-bonded to the sheet17. Specific examples of the heating temperature of the sheet35are similar to those of the heating temperature of the sheet17in the thermocompression bonding step (seeFIG.3AandFIG.3B).

FIG.12Bis a perspective view illustrating the sheet17separated from the workpiece11. After the sheet35is thermocompression-bonded to the sheet17, for example, an end part of the sheet35is grasped and is moved in such a direction as to get farther away from the workpiece11. This causes the sheet17to follow the sheet35and be separated from the workpiece11.

Besides, structures, methods, and so forth according to the above-described embodiment can be carried out with appropriate changes without departing from the range of the object of the present invention.