Sheet processing method, method for manufacturing chip, and method for manufacturing substrate

Abstract

To provide a sheet processing method that enables simple suppression of sheet slack fixed to an object.SOLUTION: A sheet processing method for processing a sheet fixed to an object comprises: a preparation step for preparing the object with a fixed sheet; a light-absorbing film forming step for forming a light-absorbing film capable of absorbing light and generating heat on the non-fixed area of the sheet that is not fixed to the object; and a shrinkage step for heating and shrinking the non-fixed area by irradiating light onto the light-absorbing film to generate heat within it.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sheet processing method for processing a sheet fixed to an object, a chip manufacturing method for manufacturing chips by dividing an object to which a sheet is fixed, and a substrate manufacturing method for manufacturing substrates by processing an object to which a sheet is fixed. [Background technology]

[0002] The device chip manufacturing process uses a wafer having a device region on its front surface where multiple devices are formed. The device region is divided into multiple regions by planned division lines (streets) set in a grid pattern, and devices are formed in each of the multiple regions. Device chips each containing a device are obtained by dividing the wafer along the planned division lines. Device chips are incorporated into various electronic devices such as mobile phones and personal computers.

[0003] Wafers are divided using a cutting device that cuts the wafer with an annular cutting blade. Recently, development of a process for dividing wafers using laser processing has also been progressing. For example, by irradiating the wafer with a laser beam, a modified layer that functions as a dividing starting point is formed inside the wafer along the planned dividing line. An external force is then applied to the wafer by pulling and expanding a sheet (holding tape) fixed to the wafer. As a result, the wafer breaks starting from the modified layer and is divided along the planned dividing line (see Patent Document 1).

[0004] In recent years, the miniaturization of electronic devices has led to a demand for thinner device chips. To address this, wafers are sometimes thinned by grinding before being divided. However, thinning the entire wafer reduces its rigidity, making it more susceptible to deformation and breakage. This makes it difficult to handle the thinned wafer.

[0005] Therefore, a processing method called TAIKO grinding has been proposed, in which only the central portion of the backside of the wafer that overlaps the device region is ground to thin it. When TAIKO grinding is performed, a recess is formed in the center of the wafer, but the outer periphery of the wafer remains thick without being thinned. As a result, the outer periphery of the wafer functions as an annular reinforcing portion, suppressing a decrease in the rigidity of the wafer after grinding (see Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-173475 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-19461 Summary of the Invention [Problem to be solved by the invention]

[0007] When processing an object such as a wafer, such as dividing or grinding, the object is supported by an annular frame for ease of handling (transporting, holding, etc.) the object. Specifically, a circular opening is provided in the center of the frame, and the object is placed inside the frame. A sheet (film) such as adhesive tape is then fixed to the object and the frame so as to cover the opening. In this way, the object is supported by the frame via the sheet.

[0008] However, when a predetermined process is performed on an object while the sheet is fixed to the object, the sheet may become loose. For example, when a wafer is divided by applying an external force to the wafer by expanding the sheet as described above, the sheet remains stretched after the wafer is divided, causing the sheet to become loose. Furthermore, after the wafer is divided into multiple chips, a process may be performed to expand the sheet fixed to the wafer to increase the spacing between the device chips to prevent them from colliding with each other. This process also causes the sheet to become loose. Furthermore, when processing wafers that have undergone the aforementioned TAIKO grinding, the sheet is fixed so that it is pressed against a recess formed on the backside of the wafer. After the wafer is subjected to various processes, the outer periphery (reinforcement) is finally separated and removed from the wafer. At this time, the tension of the sheet fixed to the recess of the wafer is released, which may cause the sheet to become loose.

[0009] If the sheet becomes loose, it can cause problems in handling the object. For example, the looseness of the sheet can cause the object to hang down from the frame, making it difficult to store the object in a designated storage container (cassette). Furthermore, if an object divided into multiple chips is supported and transported by a loose sheet, the shaking of the object can cause the chips to collide with each other, potentially damaging the chips.

[0010] Therefore, when slack occurs in a sheet due to processing of an object, a process may be performed in which the area where the slack has occurred (the slack area) of the sheet is heated to cause it to shrink. Specifically, light such as a laser beam is irradiated onto the slack area of ​​the sheet, and the slack area absorbs the light and becomes heated. This causes the slack area to shrink, eliminating the slack in the sheet.

[0011] However, the material of the sheet fixed to the object varies depending on the type of object, the processing to be performed on the object, etc. Furthermore, when irradiating light onto the sheet to remove slack, the wavelength of the light must be set according to the material of the sheet so that the light is absorbed by the sheet with high efficiency. Therefore, the process of removing slack by irradiating light is labor-intensive, and depending on the sheet material, it may be difficult to achieve high-efficiency light absorption. Furthermore, it is necessary to prepare equipment capable of irradiating light of various wavelengths onto the sheet, which increases the complexity of the equipment and costs.

[0012] The present invention has been made in consideration of such problems, and aims to provide a sheet processing method, a chip manufacturing method, and a substrate manufacturing method that can easily suppress slack in a sheet fixed to an object. [Means for solving the problem]

[0013] According to one aspect of the present invention, there is provided a sheet processing method for processing a sheet fixed to an object, the method comprising: a preparation step of preparing the object to which the sheet is fixed; a light-absorbing film formation step of forming a light-absorbing film that absorbs light and generates heat in an unfixed area of ​​the sheet that is not fixed to the object; and a shrinking step of heating and shrinking the unfixed area by irradiating the light-absorbing film with light to cause the light-absorbing film to generate heat.

[0014] Preferably, the sheet is fixed to an annular frame having an opening in which the object can be placed, and the non-fixed region is an annular region exposed between the object and the frame. Also preferably, the sheet processing method further includes a processing step of processing the object, and in the shrinking step, the non-fixed region that has become loose in the processing step is shrunk.

[0015] Preferably, in the processing step, division starting points are formed in the object along the planned division line, and then the object is divided along the planned division line by expanding the sheet. Also preferably, in the preparation step, the object is prepared having a recess in the center and an annular reinforcing part surrounding the recess in the outer periphery, and the sheet is fixed to the recess and the reinforcing part, and in the processing step, the reinforcing part is separated from the object.

[0016] According to another aspect of the present invention, there is provided a chip manufacturing method for manufacturing chips by dividing an object to which a sheet is fixed, the method comprising: a preparation step of preparing the object to which the sheet is fixed; a processing step of forming a division starting point on the object along a planned division line, and then dividing the object into a plurality of chips along the planned division line by expanding the sheet; a light-absorbing film formation step of forming a light-absorbing film that absorbs light and generates heat in a non-fixed area of ​​the sheet that is not fixed to the object; and a contraction step of heating and contracting the non-fixed area by irradiating the light-absorbing film with light to cause the light-absorbing film to generate heat.

[0017] According to another aspect of the present invention, there is provided a chip manufacturing method for manufacturing chips by dividing an object to which a sheet is fixed, the method comprising: a preparation step for preparing the object to which the sheet is fixed; a processing step for dividing the object into a plurality of chips along a planned division line and then expanding the sheet to widen the spacing between the plurality of chips; a light-absorbing film formation step for forming a light-absorbing film that absorbs light and generates heat in a non-fixed area of ​​the sheet that is not fixed to the object; and a contraction step for heating and contracting the non-fixed area by irradiating the light-absorbing film with light to cause the light-absorbing film to generate heat.

[0018] Furthermore, according to another aspect of the present invention, there is provided a method for manufacturing a substrate by processing an object to which a sheet is fixed to manufacture a substrate, the method comprising: a preparation step of preparing an object having a recess in the center and an annular reinforcing part surrounding the recess in the outer periphery, with the sheet fixed to the recess and the reinforcing part; a processing step of manufacturing a substrate by separating the reinforcing part from the object; a light absorbing film formation step of forming a light absorbing film that absorbs light and generates heat in an unfixed area of ​​the sheet that is not fixed to the object; and a shrinking step of irradiating the light absorbing film with light to cause the light absorbing film to generate heat, thereby heating and shrinking the unfixed area. [Effects of the Invention]

[0019] In the sheet processing method, chip manufacturing method, and substrate manufacturing method according to one aspect of the present invention, a light absorbing film formed in an unfixed region of a sheet is irradiated with light to generate heat in the light absorbing film, thereby heating and shrinking the unfixed region. This eliminates the need to set detailed light irradiation conditions depending on the sheet material, and simplifies the process of suppressing slack in the sheet. [Brief explanation of the drawings]

[0020] [Figure 1] 10 is a flowchart illustrating a sheet processing method. [Figure 2] FIG. 2 is a perspective view showing an object, a frame, and a seat. [Figure 3] FIG. 2 is a perspective view showing a frame unit. [Figure 4] FIG. 2 is a partial cross-sectional front view showing the laser processing device. [Figure 5] FIG. 5(A) is a partial cross-sectional front view showing an expansion device, and FIG. 5(B) is a partial cross-sectional front view showing an expansion device that expands a sheet. [Figure 6] FIG. 10 is a partial cross-sectional front view showing the expansion device in the light absorbing film forming step. [Figure 7] FIG. 2 is a cross-sectional view showing a part of a sheet and a light-absorbing film. [Figure 8]FIG. 10 is a partial cross-sectional front view showing the expansion device in a contracting step. [Figure 9] FIG. 9(A) is a perspective view showing a modified example of the object, and FIG. 9(B) is a perspective view showing a modified example of the frame unit. [Figure 10] FIG. 10(A) is a partially sectional front view showing the laser processing device, and FIG. 10(B) is a sectional view showing a part of an object on which a modified region has been formed. [Figure 11] FIG. 11(A) is a partial cross-sectional front view showing the separation device when an external force is applied to the object, and FIG. 11(B) is a partial cross-sectional front view showing the separation device when the reinforcing part is separated from the object. [Figure 12] FIG. 10 is a partial cross-sectional front view showing a separation device in a light absorbing film forming step. [Figure 13] FIG. 10 is a partial cross-sectional front view showing the separation device in a contraction step. [Figure 14] FIG. 14(A) is a cross-sectional view showing an object to be divided by cutting, and FIG. 14(B) is a cross-sectional view showing an object to be divided by laser processing. DETAILED DESCRIPTION OF THE INVENTION

[0021] (Embodiment 1) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the accompanying drawings. In this embodiment, a specific example of a sheet processing method (film processing method) according to an aspect of the present invention will be described.

[0022] 1 is a flowchart showing a sheet processing method. In this embodiment, a preparation step S1 is performed to prepare an object to which a sheet is fixed, followed by a processing step S2 to perform a predetermined process on the object. Then, a light absorbing film forming step S3 and a shrinking step S4 are performed to reduce or remove slack that has occurred in the sheet in the processing step S2.

[0023] 2 is a perspective view showing the object 11, the frame 19, and the sheet (film) 21. The object 11 is a member to which the sheet 21 is fixed, and corresponds to an object to be processed (an object to be processed, an object to be cleaned, an object to be inspected, etc.) that is subjected to various processes by a processing device such as a processing device, a cleaning device, an inspection device, etc.

[0024] For example, the object 11 is a disk-shaped wafer made of a semiconductor material such as single crystal silicon, and has a front surface (first surface) 11a and a back surface (second surface) 11b that are generally parallel to each other. The object 11 is divided into a plurality of rectangular regions by a plurality of planned division lines (streets) 13 that are arranged in a grid pattern so as to intersect with each other. Devices 15, such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems) devices, are formed on the front surface 11a side of each of the plurality of regions divided by the planned division lines 13.

[0025] The object 11 has, on its surface 11a side, a substantially circular device region 17A in which a plurality of devices 15 are formed, and an annular peripheral surplus region 17B surrounding the device region 17A. The peripheral surplus region 17B corresponds to a strip-shaped region of a predetermined width (e.g., approximately 2 mm) that includes the outer periphery of the surface 11a. No devices 15 are formed in the peripheral surplus region 17B, or only devices (dummy devices) that will not be used in the product are formed therein. Note that in FIG. 2, the imaginary boundary between the device region 17A and the peripheral surplus region 17B is indicated by a dashed line.

[0026] In this embodiment, a case will be described in which a dividing process is performed to divide an object 11 along the planned dividing lines 13. That is, the object 11 is a workpiece to be divided. By dividing the object 11 along the planned dividing lines 13, a plurality of chips (device chips), each having a device 15, are obtained.

[0027] However, there are no limitations on the type, material, shape, structure, size, etc. of the object 11. For example, the object 11 may be a substrate (wafer) made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), sapphire, glass, ceramics, resin, metal, etc. Furthermore, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of the devices 15, and the object 11 does not necessarily have to have any devices 15 formed thereon.

[0028] Furthermore, the target object 11 may be a package substrate such as a CSP (Chip Size Package) substrate or a QFN (Quad Flat Non-leaded package) substrate. For example, a package substrate is formed by mounting a plurality of device chips on a predetermined substrate and then covering and sealing the mounted device chips with a resin layer (mold resin). By dividing the package substrate along predetermined division lines, a plurality of package devices each including a plurality of packaged device chips are manufactured.

[0029] When processing the object 11, the object 11 is supported by an annular frame 19 for ease of handling (transporting, holding, etc.) the object 11. The frame 19 is made of a metal such as stainless steel (SUS), and a circular opening 19a is provided in the center of the frame 19, penetrating the frame 19 in the thickness direction. The diameter of the opening 19a is larger than the diameter of the object 11, allowing the object 11 to be placed in the opening 19a.

[0030] A circular sheet 21 is fixed to the object 11 and the frame 19. The sheet 21 is an expandable sheet that can be expanded by applying an external force. For example, the sheet 21 may be a tape including a circular base material and an adhesive layer (glue layer) provided on the base material. The base material may be made of a resin such as polyolefin or polyvinyl chloride, which has high extensibility. The adhesive layer may be made of an epoxy-based, acrylic-based, or rubber-based adhesive. The adhesive layer may have a property that its adhesiveness to the object 11 decreases when subjected to a predetermined treatment. For example, the adhesive layer may be made of an ultraviolet-curable resin that hardens when exposed to ultraviolet light.

[0031] With the object 11 placed inside the opening 19a, the sheet 21 is fixed to the object 11 and the frame 19 so as to cover the opening 19a. Specifically, the center of the sheet 21 is attached to the back surface 11b of the object 11, and the outer periphery of the sheet 21 is attached to the underside of the frame 19. In this way, the object 11 is supported by the frame 19 via the sheet 21.

[0032] However, the sheet 21 may also be a sheet (thermocompression sheet) that can be thermocompressed to the object 11 and the frame 19. The thermocompression sheet is made of a thermoplastic resin with a melting point lower than that of the object 11, and does not include an adhesive layer (glue layer). For example, an olefin-based sheet, a styrene-based sheet, a polyester-based sheet, etc. are used as the thermocompression sheet. Examples of the olefin-based sheet include a polyethylene sheet and a polypropylene sheet. Examples of the styrene-based sheet include a polystyrene sheet. Examples of the polyester-based sheet include a polyethylene terephthalate sheet and a polyethylene naphthalate sheet.

[0033] When fixing the thermocompression sheet to the object 11 and the frame 19, for example, a roller (heat roller) equipped with an internal heat source is used. Specifically, the heat roller heated to a predetermined temperature comes into contact with the thermocompression sheet to heat it, while pressing the thermocompression sheet against the object 11 and the frame 19. This softens the thermocompression sheet, causing it to adhere closely to the object 11 and the frame 19 and be thermocompression-bonded.

[0034] The thermocompression sheet is heated so that the temperature of the thermocompression sheet is equal to or higher than the softening point of the thermocompression sheet and equal to or lower than the melting point of the thermocompression sheet. However, the thermocompression sheet may not have a clear softening point. In this case, the thermocompression sheet is heated so that the temperature of the thermocompression sheet is equal to or higher than a temperature that is a predetermined temperature (e.g., 20°C) lower than the melting point of the thermocompression sheet and equal to or lower than the melting point of the thermocompression sheet.

[0035] For example, if the thermocompression sheet is a polyethylene sheet, the heating temperature can be set to 120°C or higher and 140°C or lower, and if the thermocompression sheet is a polypropylene sheet, the heating temperature can be set to 160°C or higher and 180°C or lower. If the thermocompression sheet is a polystyrene sheet, the heating temperature can be set to 220°C or higher and 240°C or lower. Furthermore, if the thermocompression sheet is a polyethylene terephthalate sheet, the heating temperature can be set to 250°C or higher and 270°C or lower, and if the thermocompression sheet is a polyethylene naphthalate sheet, the heating temperature can be set to 160°C or higher and 180°C or lower.

[0036] 3 is a perspective view showing a frame unit (object unit) 23. The object 11 is supported by the frame 19 via the sheet 21, thereby forming the frame unit 23 including the object 11, the frame 19, and the sheet 21. Then, with the object 11 supported by the frame 19, the object 11 is transported, held, etc., and a predetermined process is performed on the object 11. However, the object 11 may be supported by a member other than the annular frame 19. In other words, the sheet 21 does not necessarily have to be fixed to the frame 19.

[0037] The sheet 21 has a non-fixed region 21a which is a region that is not fixed to the object 11. In the frame unit 23 in which the object 11 is supported by the frame 19 via the sheet 21, the annular region that is not fixed to the object 11 and the frame 19 and is exposed between the object 11 and the frame 19 corresponds to the non-fixed region 21a.

[0038] In the preparation step S1, for example, the frame unit 23 is prepared according to the above-described procedure. Note that the person who performs the sheet processing method according to this embodiment may prepare the frame unit 23 by forming it himself or by obtaining a frame unit 23 formed by another person.

[0039] Next, processing step S2 is performed to process the object 11. In this embodiment, a case will be described in which the object 11 is subjected to a dividing process in processing step S2, and the object 11 is divided into a plurality of chips. For example, processing step S2 includes a step of forming division start points in the object 11 (division start point forming step) and a step of applying an external force to the object 11 (external force applying step).

[0040] 4 is a partial cross-sectional front view showing the laser processing apparatus 2. For example, in the division starting point forming step, the laser processing apparatus 2 performs laser processing on the object 11, thereby forming a modified layer that functions as a division starting point inside the object 11. In FIG. 4, the X-axis direction (processing feed direction, first horizontal direction) and the Y-axis direction (indexing feed direction, second horizontal direction) are perpendicular to each other. Furthermore, the Z-axis direction (up-down direction, height direction, vertical direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0041] The laser processing device 2 includes a chuck table (holding table) 4 that holds the object 11. The upper surface of the chuck table 4 is a circular flat surface that is roughly parallel to the horizontal plane (XY plane), and constitutes a holding surface 4a that holds the object 11. The holding surface 4a is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), and the like that are formed inside the chuck table 4.

[0042] A ball screw type movement mechanism (not shown) that moves the chuck table 4 along the X-axis and Y-axis directions is connected to the chuck table 4. A rotation drive source (not shown) such as a motor that rotates the chuck table 4 around a rotation axis that is approximately perpendicular to the holding surface 4a is also connected to the chuck table 4. Furthermore, a plurality of clamps 6 that grip and fix the frame 19 that supports the object 11 are provided around the periphery of the chuck table 4.

[0043] The laser processing device 2 also includes a laser irradiation unit 8 that irradiates a laser beam. The laser irradiation unit 8 includes a laser oscillator (not shown) such as a YAG laser, a YVO4 laser, or a YLF laser, and a laser processing head 10 disposed above the chuck table 4.

[0044] The laser processing head 10 has a built-in optical system that guides a pulsed laser beam 12 emitted from a laser oscillator to an object 11. The optical system includes optical elements such as a condenser lens that condenses the laser beam 12. The laser beam 12 emitted from the laser oscillator is irradiated from the laser processing head 10 toward the object 11 and condensed at a predetermined position. The laser beam 12 then performs a predetermined laser processing on the object 11.

[0045] Furthermore, the laser processing apparatus 2 includes a controller (control unit, control section, control device) 14 that controls the laser processing apparatus 2. The controller 14 is connected to each component (chuck table 4, clamp 6, laser irradiation unit 8, etc.) that constitutes the laser processing apparatus 2, and outputs a control signal to each component.

[0046] For example, the controller 14 is configured by a computer and includes a processing unit that executes processes such as calculations required for the operation of the laser processing device 2, and a storage unit that stores various information (data, programs, etc.) used for the operation of the laser processing device 2. The processing unit includes a processor such as a CPU (Central Processing Unit). The storage unit includes memories such as a ROM (Read Only Memory) and RAM (Random Access Memory).

[0047] When processing the object 11 with the laser processing device 2, the object 11 is first held by the chuck table 4. For example, the object 11 is placed on the chuck table 4 so that the front surface 11a faces upward and the back surface 11b (the sheet 21 side) faces the holding surface 4a. In addition, the frame 19 is fixed by a plurality of clamps 6. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 4a, the object 11 is sucked and held by the chuck table 4 via the sheet 21.

[0048] Next, the chuck table 4 is rotated, and the angle of the chuck table 4 is adjusted so that the length direction of the predetermined dividing line 13 (see FIG. 3) coincides with the X-axis direction. Also, the position of the chuck table 4 in the Y-axis direction is adjusted so that the area irradiated with the laser beam 12 is positioned on an extension of the predetermined dividing line 13. Furthermore, the height position of the laser processing head 10 and the arrangement of the optical system are adjusted so that the focal point of the laser beam 12 is positioned at the same height position (position in the Z-axis direction) as the interior of the object 11 (between the front surface 11a and the back surface 11b).

[0049] Then, the chuck table 4 is moved along the X-axis direction while irradiating the laser beam 12 from the laser processing head 10. This causes the chuck table 4 and the laser beam 12 to move relatively along the processing feed direction at a predetermined processing feed speed. As a result, the laser beam 12 is irradiated along the intended division line 13 from the front surface 11a side of the object 11.

[0050] The laser processing device 2 processes the object 11 under predetermined processing conditions registered in advance in the controller 14. For example, the irradiation conditions of the laser beam 12 are set so that the area of ​​the object 11 irradiated with the laser beam 12 is modified and transformed by multiphoton absorption. Specifically, the wavelength of the laser beam 12 is set so that at least a portion of the laser beam 12 passes through the object 11. In other words, the laser beam 12 is a laser beam that is transparent to the object 11. Other irradiation conditions of the laser beam 12 are also set so that the object 11 is appropriately modified. For example, when the object 11 is a single crystal silicon wafer, the irradiation conditions of the laser beam 12 can be set as follows: Wavelength: 1064nm Average power: 1W Repetition frequency: 100kHz Processing feed rate: 800mm / s

[0051] When the object 11 is processed under the above processing conditions, the inside of the object 11 is modified and altered by multiphoton absorption, and modified layers (altered layers) 11c are formed inside the object 11 along the planned dividing lines 13. Thereafter, by repeating the same procedure, the laser beam 12 is irradiated along the other planned dividing lines 13. As a result, multiple modified layers 11c are formed in a lattice pattern inside the object 11 along all of the planned dividing lines 13.

[0052] The region of the object 11 where the modified layer 11c is formed becomes more fragile than other regions of the object 11. Therefore, when an external force is applied to the object 11, the object 11 is divided along the intended division line 13, starting from the modified layer 11c. In other words, the modified layer 11c functions as a division starting point (a trigger for division).

[0053] Note that multiple modified layers 11c may be formed in the thickness direction of the object 11. For example, if the object 11 is a single crystal silicon wafer or the like having a thickness of 200 μm or more, forming two or more modified layers 11c will make it easier to properly divide the object 11. When multiple modified layers 11c are formed, the laser beam 12 is irradiated multiple times along each planned division line 13 while changing the height position of the focal point of the laser beam 12.

[0054] Next, an external force is applied to the object 11, dividing the object 11 along the planned division lines 13 starting from the modified layer 11c (external force application step). For example, in the external force application step, the sheet 21 fixed to the object 11 is pulled and expanded to apply an external force to the object 11. The expansion of the sheet 21 may be performed using a dedicated expansion device or may be performed manually by an operator.

[0055] 5(A) is a partial cross-sectional front view showing the expansion device 20. The expansion device 20 includes a drum 22 formed in a hollow cylindrical shape. At the upper end of the drum 22, a plurality of rollers 24 are arranged at approximately equal intervals along the circumferential direction of the drum 22. In addition, a plurality of columnar support members 26 are arranged on the outside of the drum 22. At the lower end of each of the support members 26, an elevating mechanism (not shown) is connected, which raises and lowers the support member 26 in the vertical direction. For example, a linear actuator, an air cylinder, or the like is used as the elevating mechanism.

[0056] An annular table 28 is fixed to the upper ends of the multiple support members 26. A circular opening 28a is provided in the center of the table 28, penetrating the table 28 in the thickness direction. The diameter of the opening 28a is larger than the diameter of the drum 22, allowing the upper end of the drum 22 to be inserted into the opening 28a. In addition, multiple clamps 30 are arranged on the outer periphery of the table 28, which grip and secure the frame 19 that supports the object 11. When the multiple support members 26 are raised and lowered by an elevating mechanism (not shown), the table 28 and the frame 19 are raised and lowered in the vertical direction.

[0057] When dividing the target object 11, first, the support member 26 is raised and lowered by a lifting mechanism (not shown) to place the table 28 in its initial position. When the table 28 is placed in its initial position, the upper surface of the table 28 and the upper ends of the rollers 24 are positioned at approximately the same height. Then, the frame 19 is placed on the table 28, and the frame 19 is fixed by a plurality of clamps 30. At this time, the target object 11 is placed so as to overlap the inside of the drum 22, and the non-fixed region 21a of the sheet 21 is supported by the plurality of rollers 24.

[0058] Thereafter, the support member 26 is lowered, and the table 28 and clamp 30 are pulled down. This pushes down the frame 19, and the sheet 21 is pulled with the non-fixed region 21a supported by the rollers 24. As a result, the sheet 21 is stretched radially and expanded.

[0059] FIG. 5(B) is a partial cross-sectional front view showing the expansion device 20 expanding the sheet 21. When the sheet 21 is expanded, an external force directed radially outward is applied to the object 11 fixed to the sheet 21. As a result, the object 11 is broken along the intended division line 13, with the modified layer 11c serving as the division starting point. This causes the object 11 to be divided into a plurality of chips (device chips) 11d, each including a device 15 (see FIG. 3). When division of the object 11 is complete, the support member 26 is raised, and the table 28 is again placed in the initial position.

[0060] As described above, in processing step S2, when the target object 11 is divided along the planned division lines 13, a plurality of chips 11d are produced. That is, the sheet processing method according to this embodiment corresponds to a chip manufacturing method in which the target object 11 is divided to produce the chips 11d.

[0061] When the sheet 21 is expanded, the non-fixed region 21a of the sheet 21 stretches significantly, and the non-fixed region 21a becomes loose when the table 28 is returned to its initial position. When the non-fixed region 21a of the sheet 21 becomes loose, it becomes difficult to handle the object 11. For example, if the object 11 is transported from the expansion device 20 while the non-fixed region 21a is loose, the object 11 hangs down from the frame 19, and the object 11 is likely to sway. This may cause the chips 11d to collide with each other, potentially damaging the chips 11d.

[0062] Therefore, in this embodiment, after the division of the object 11 is completed, the non-fixed region 21a of the sheet 21 is heated to shrink it. Specifically, a light absorbing film is formed in the non-fixed region 21a of the sheet 21 (light absorbing film forming step S3), and then the light absorbing film is irradiated with light to cause the light absorbing film to generate heat, thereby heating and shrinking the non-fixed region 21a (shrinkage step S4). This reduces or eliminates slack in the sheet 21, allowing the object 11 to be handled appropriately thereafter.

[0063] 6 is a partial cross-sectional front view showing the expansion device 20 in the light-absorbing film-forming step S3. In the light-absorbing film-forming step S3, a light-absorbing film 25 that absorbs light and generates heat is formed in the non-fixed region 21a of the sheet 21. The light-absorbing film 25 is a film that has the property of absorbing light 42 (see FIG. 8) irradiated onto the sheet 21 in the contraction step S4 described below and generating heat. In this embodiment, a case where the light-absorbing film-forming step S3 is performed using the expansion device 20 will be described.

[0064] The expansion device 20 includes a light-absorbing film forming unit 32 that forms a light-absorbing film 25 on the sheet 21. The light-absorbing film forming unit 32 includes a nozzle 34 that supplies a film material 36, which is a raw material for the light-absorbing film 25. The nozzle 34 is provided above the multiple rollers 24 and the table 28, and is positioned so as to overlap the non-fixed region 21a of the sheet 21 supported by the multiple rollers 24 and the table 28. By supplying the film material 36 from the nozzle 34 to the non-fixed region 21a of the sheet 21, the light-absorbing film 25 is formed in the non-fixed region 21a.

[0065] The components of the expansion device 20 are installed, for example, on a rotating table (not shown). The rotating table is configured to rotate around a rotation axis that is set to be roughly parallel to the vertical direction and pass through the center of the table 28. When the rotating table is operated, the components of the expansion device 20 (drum 22, rollers 24, support member 26, table 28, clamp 30, etc.) rotate around the rotation axis of the rotating table. This causes the frame unit 23 held by the components of the expansion device 20 to also rotate.

[0066] In the light-absorbing film forming step S3, the frame unit 23 is rotated while the film material 36 is supplied from the nozzle 34 toward the non-fixed region 21a of the sheet 21. As a result, the film material 36 is supplied in an annular shape along the circumferential direction of the non-fixed region 21a, and part or all of the non-fixed region 21a is covered with the film material 36. Thereafter, the film material 36 is dried to form an annular light-absorbing film 25 in contact with part or all of the non-fixed region 21a.

[0067] However, instead of rotating the frame unit 23, the nozzle 34 may be rotated. For example, a rotating arm (not shown) is connected to the nozzle 34, which rotates the nozzle 34 along a circular path that overlaps the non-fixed region 21a of the sheet 21. In this case, by operating the rotating arm to rotate the nozzle 34 while supplying the film material 36 from the nozzle 34 to the non-fixed region 21a of the sheet 21, the film material 36 can be supplied in a circular pattern along the circumferential direction of the non-fixed region 21a.

[0068] As described above, by supplying the film material 36 to the non-fixed region 21a of the sheet 21, a ring-shaped light absorbing film 25 is formed in the non-fixed region 21a. The light absorbing film 25 is formed between the object 11 and the frame 19 so as to contact a part or the whole of the non-fixed region 21a.

[0069] 7 is a cross-sectional view showing a portion of the sheet 21 and the light-absorbing film 25. For example, the light-absorbing film 25 is made of a resin film 27 containing a light-absorbing agent 29 that absorbs light and generates heat. The light-absorbing agent 29 is a particulate or powdery substance that absorbs light in a predetermined wavelength band and generates heat, and is dispersed approximately evenly throughout the interior of the resin film 27.

[0070] The resin film 27 is formed by applying a film material 36 (see FIG. 6) containing a light absorber 29 to the non-fixed region 21a of the sheet 21. For example, a liquid resin produced by dissolving a solute made of a water-soluble resin in a solvent such as water is used as the film material 36. Specific examples of water-soluble resins include polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), hydroxypropyl cellulose, polyethylene glycol, polyethylene oxide, methyl cellulose, ethyl cellulose, polyacrylic acid, poly-N-vinylacetamide, polystyrene sulfonic acid, special nylon, phenolic resin, methylol melamine resin, and polyglycerin. Graft polymers of the above resins can also be used as the water-soluble resin.

[0071] Then, a light absorber 29 is added to the liquid resin. The light absorber 29 is made of a material that generates heat by absorbing light 42 (see FIG. 8) irradiated onto the sheet 21 in a shrinking step S4 described below. For example, when infrared light having a wavelength of 700 nm or more and 1300 nm or less is irradiated onto the sheet 21 in the shrinking step S4, the light absorber 29 can be made of a cinnamic acid-based organic compound (ferulic acid, etc.), a benzophenone-based organic compound, a metal oxide (zinc oxide, titanium oxide, etc.), carbon, or the like, which absorbs infrared light and generates heat.

[0072] The film material 36 produced as described above is supplied to the non-fixed region 21a of the sheet 21 and dried, thereby forming a resin film 27 containing a light absorbent 29 in the non-fixed region 21a. When light is irradiated onto the resin film 27, the light absorbent 29 contained in the resin film 27 absorbs the light and generates heat, thereby heating the resin film 27. If the resin film 27 is made of a water-soluble resin, the resin film 27 can be removed in a later step by a simple process of supplying water to the resin film 27.

[0073] However, as long as the light-absorbing film 25 has the property of absorbing light and generating heat, there are no limitations on the material, configuration, shape, formation method, etc. of the light-absorbing film 25. For example, the light-absorbing film 25 may be a film made of a material other than resin (such as a metal film). Furthermore, if the substrate (base material) of the light-absorbing film 25 has the property of absorbing light and generating heat, the light-absorbing film 25 does not necessarily need to contain the light absorber 29.

[0074] 6 illustrates an example in which the light absorbing film 25 is formed on the upper surface side of the sheet 21, but the light absorbing film 25 may be formed on the lower surface side of the sheet 21. In this case, the light absorbing film 25 may be formed only on a part of the sheet 21 (the area overlapping the non-fixed region 21a), or may be formed on the entire lower surface side of the sheet 21. Furthermore, the sheet-like light absorbing film 25 may be formed separately from the sheet 21 and then attached to the non-fixed region 21a of the sheet 21.

[0075] 8 is a partial cross-sectional front view showing the expansion device 20 in the contraction step S4. In the contraction step S4, the light absorbing film 25 is irradiated with light to cause the light absorbing film 25 to generate heat, thereby heating and contracting the non-fixed region 21a of the sheet 21. In this embodiment, a case where the contraction step S4 is performed using the expansion device 20 will be described.

[0076] The expansion device 20 includes a light irradiation unit 38 that irradiates light onto the light absorbing film 25. For example, the light irradiation unit 38 includes a light irradiation head 40 that irradiates light 42. The light irradiation head 40 is installed at a position overlapping the light absorbing film 25 formed in the non-fixed region 21a of the sheet 21. When the light 42 is irradiated onto the light absorbing film 25 from the light irradiation head 40, the light absorbing film 25 absorbs the light 42 and generates heat.

[0077] For example, the light irradiation unit 38 is a laser irradiation unit that irradiates a laser beam as the light 42. In this case, the light irradiation unit 38 can be configured similarly to the laser irradiation unit 8 (see FIG. 4), and an optical system including optical elements such as a condenser lens is housed in the light irradiation head 40. The wavelength of the light 42 is set so that the light 42 is absorbed by the light absorption film 25. For example, the wavelength of the light 42 is set to 700 nm or more and 1300 nm or less (typically, 940 nm, 1064 nm, etc.).

[0078] In the contraction step S4, the light irradiation unit 38 is activated, and light 42 is irradiated from the light irradiation head 40 toward the light absorbing film 25. As a result, the light 42 is absorbed by the light absorbing film 25 and converted into heat, causing the light absorbing film 25 to generate heat. When the light absorbing film 25 generates heat, the non-fixed region 21a of the sheet 21 that is in contact with the light absorbing film 25 is heated. This causes the non-fixed region 21a to contract, reducing or eliminating slack that has occurred in the non-fixed region 21a.

[0079] Furthermore, the frame unit 23 is rotated while irradiating the light absorbing film 25 with light 42 from the light irradiation head 40. This causes the light 42 to be scanned circularly along the circumferential direction of the light absorbing film 25, and irradiates the entire light absorbing film 25. As a result, the entire non-fixed region 21a in contact with the light absorbing film 25 is heated, and slack in the sheet 21 is reduced or eliminated across the entire non-fixed region 21a.

[0080] However, instead of rotating the frame unit 23 and the light absorbing film 25, the light 42 may be scanned circularly by rotating the light irradiation head 40. For example, a rotating arm (not shown) that rotates the light irradiation head 40 along a circular path that overlaps with the light absorbing film 25 is connected to the light irradiation head 40. In this case, the light 42 can be scanned circularly along the circumferential direction of the light absorbing film 25 by operating the rotating arm to rotate the light irradiation head 40 while irradiating the light 42 from the light irradiation head 40 onto the light absorbing film 25.

[0081] 8 illustrates an example in which the light emitting head 40 is disposed above the sheet 21 and the light absorbing film 25. However, the light emitting head 40 can also be disposed below the sheet 21 and the light absorbing film 25. In this case, light 42 irradiated from the light emitting head 40 passes through the sheet 21 and is absorbed by the light absorbing film 25, causing the light absorbing film 25 to generate heat.

[0082] As described above, by irradiating the light absorbing film 25 formed in the non-fixed region 21a of the sheet 21 with light 42, the non-fixed region 21a can be heated and shrunk even if the sheet 21 does not have the ability to absorb light 42. This makes it possible to suppress sagging of the sheet 21 regardless of the material of the sheet 21.

[0083] In the above, an example has been described in which the entire non-fixed region 21a of the sheet 21 is heated by the light absorbing film 25. However, in the shrinking step S4, only a part of the non-fixed region 21a may be heated depending on the characteristics of the sheet 21. For example, if a specific region of the non-fixed region 21a of the sheet 21 is particularly prone to sagging, only that region may be heated to shrink it.

[0084] Specifically, in the contraction step S4, the light 42 is scanned circularly along the light absorbing film 25, and the irradiation and non-irradiation of the light 42 are switched at predetermined timing. As a result, the light 42 is intermittently irradiated along the light absorbing film 25, and the light absorbing film 25 is partially heated. This makes it possible to heat only the desired region of the non-fixed region 21a.

[0085] Furthermore, when only a portion of the non-fixed region 21a is heated, the light absorbing film 25 may be disposed so as to contact only a portion of the non-fixed region 21a. In this case, the shape of the light absorbing film 25 does not necessarily have to be annular, corresponding to the shape of the non-fixed region 21a. For example, in the light absorbing film forming step S3, a plurality of light absorbing films 25 are formed at predetermined intervals along the circumferential direction of the non-fixed region 21a. Then, in the shrinking step S4, light 42 is sequentially irradiated onto the plurality of light absorbing films 25, thereby partially heating the non-fixed region 21a.

[0086] In the above description, the light absorbing film forming step S3 and the shrinking step S4 are performed after slack occurs in the sheet 21 in the processing step S2, thereby reducing or eliminating the slack in the sheet 21. However, by performing the light absorbing film forming step S3 and the shrinking step S4 in advance before the processing step S2 is performed, it is also possible to prevent the slack in the sheet 21 from occurring in the processing step S2.

[0087] Specifically, before performing processing step S2, the non-fixed region 21a of the sheet 21 is heated and shrunk in the above-described procedure (light absorbing film forming step S3 and shrinking step S4). As a result, the non-fixed region 21a of the sheet 21 is put in a state where it is more taut than the other regions, and the tension in the non-fixed region 21a is higher than in the other regions. Therefore, even if the sheet 21 is subsequently expanded in processing step S2, the non-fixed region 21a of the sheet 21 is less likely to stretch, and slack is less likely to occur in the non-fixed region 21a. This prevents the sheet 21 from slackening in advance.

[0088] As described above, in the sheet processing method (chip manufacturing method) according to this embodiment, the light absorbing film 25 formed in the non-fixed region 21a of the sheet 21 is irradiated with light 42 to heat the light absorbing film 25, thereby heating and shrinking the non-fixed region 21a. This eliminates the need to set detailed irradiation conditions for the light 42 depending on the material of the sheet 21, and simplifies the process of suppressing sagging of the sheet 21.

[0089] In the above embodiment, the light absorbing film 25 is formed by performing the light absorbing film forming step S3 (see FIG. 6) after the processing step S2 (see FIGS. 4 to 5(B)). However, the timing of forming the light absorbing film 25 can be changed as appropriate as long as it is performed before the shrinking step S4 (see FIG. 8). For example, the light absorbing film forming step S3 may be performed after the preparation step S1 and before the processing step S2.

[0090] In the above embodiment, a case has been described in which processing step S2 involves applying an external force to the target object 11 by expanding the sheet 21. However, there is no limitation to the processing performed on the target object 11 in processing step S2. Other examples of processing step S2 will be described in the following embodiments 2 and 3.

[0091] Furthermore, in the above embodiment, the light absorbing film forming step S3 (see FIG. 6) and the contraction step S4 (see FIG. 8) are performed using the expansion device 20. However, the light absorbing film forming step S3 and the contraction step S4 may be performed by a sheet processing device prepared separately from the expansion device 20. In this case, the sheet processing device includes the light absorbing film forming unit 32 and the light irradiation unit 38 described above. Then, after the sheet 21 is expanded by the expansion device 20, the sheet processing device forms the light absorbing film 25 and heats the non-fixed region 21a of the sheet 21, thereby suppressing sagging of the sheet 21.

[0092] In addition, the structure, method, etc. according to this embodiment can be modified as appropriate without departing from the scope of the object of the present invention.

[0093] (Embodiment 2) In the above-described first embodiment, a case where slack occurs in the sheet 21 when an external force is applied to the object 11 due to the expansion of the sheet 21 has been described. In this embodiment, as another example of processing performed on the object, processing for separating an annular reinforcing portion from an object that has been subjected to TAIKO grinding will be described.

[0094] FIG. 9(A) is a perspective view showing an object 11A, which is a modified example of the object 11. The configuration, material, etc. of the object 11A are the same as those of the object 11 (see FIG. 2), except for the points described below. For example, the object 11A is a disk-shaped wafer made of a semiconductor material such as single crystal silicon, and has a front surface 11a and a back surface 11b that are generally parallel to each other. Furthermore, a plurality of devices 15 (see FIG. 2) are formed on the front surface 11a side of the object 11A, and the object 11A has a device region 17A and a peripheral excess region 17B (see FIG. 2).

[0095] By dividing the object 11A along the planned division lines 13 (see FIG. 2), a plurality of chips 11d (see FIG. 5(B)) each including a device 15 are manufactured. In addition, by grinding the object 11A before division to thin it, thinned chips 11d are obtained.

[0096] For example, a grinding device is used to thin the object 11A. The grinding device includes a chuck table (holding table) that holds the object 11A and a grinding unit that performs grinding on the object 11A. An annular grinding wheel including a plurality of grinding stones is attached to the grinding unit. The object 11A is held by the chuck table, and the grinding stones are brought into contact with the back surface 11b of the object 11A while the chuck table and the grinding wheel are rotated, thereby grinding the back surface 11b of the object 11A and thinning the object 11A.

[0097] However, if the entire back surface 11b of the object 11A is ground, the entire object 11A is thinned, and the rigidity of the object 11A is reduced. This makes the object 11A more susceptible to deformation and damage, making it difficult to handle the object 11A after thinning. Therefore, thinning may be performed only on a portion of the area on the back surface 11b of the object 11A.

[0098] Specifically, the target object 11A is subjected to TAIKO grinding, which grinds only the central portion of the target object 11A. In this case, a circular recess (groove) 31 is formed on the back surface 11b of the target object 11A. The recess 31 is provided at a position corresponding to the device region 17A (see FIG. 1). For example, the diameter of the recess 31 is approximately the same as the diameter of the device region 17A, and the recess 31 is formed at a position overlapping the device region 17A.

[0099] The recess 31 includes a circular bottom surface 31a that is generally parallel to the front surface 11a and back surface 11b of the object 11A, and an annular side surface (inner wall) 31b that is generally parallel to the thickness direction of the object 11A and connected to the back surface 11b and bottom surface 31a. Furthermore, an annular reinforcing portion (protrusion) 33 remains on the outer periphery of the object 11A, corresponding to an area that has not been subjected to the thinning process (grinding). The reinforcing portion 33 includes the outer periphery excess region 17B (see FIG. 1) and surrounds the device region 17A (see FIG. 1) and the recess 31.

[0100] By thinning only the central portion of the object 11A, the outer periphery (reinforcement portion 33) of the object 11A remains thick. This prevents a decrease in the rigidity of the object 11A, making the object 11A less susceptible to deformation, breakage, etc. In other words, the reinforcing portion 33 functions as an annular reinforcing member that reinforces the object 11A.

[0101] 9(B) is a perspective view showing a frame unit 23A which is a modified example of the frame unit 23. When a predetermined process is performed on the object 11A, the object 11A is supported by the frame 19 via the sheet 21. In this way, the frame unit 23A including the object 11A, the frame 19, and the sheet 21 is configured.

[0102] When constructing the frame unit 23A, the sheet 21 is fixed to the back surface 11b side of the object 11A and the frame 19. At this time, the sheet 21 is pressed against the bottom surface 31a of the recess 31 and stretched, and fixed along the contour of the back surface 11b side of the object 11A. As a result, the sheet 21 is attached along the back surface (lower surface) of the recess 31 and the reinforcing portion 33. Then, when the sheet 21 is fixed to the object 11A and the frame 19, a non-fixed region 21a of the sheet 21 that is not fixed to the object 11A and the frame 19 is formed. Details of the non-fixed region 21a of the sheet 21 are as described in the first embodiment (see FIG. 3, etc.).

[0103] In the preparation step S1, as described above, an object 11A is prepared, in which a recess 31 is provided in the center, a reinforcing portion 33 is provided on the outer periphery, and a sheet 21 is fixed to the recess 31 and the reinforcing portion 33. Note that while Fig. 9(B) illustrates a case in which there is a slight gap (space) between the sheet 21 and the bottom surface 31a and side surface 31b at the outer periphery of the recess 31, the sheet 21 may also be fixed so as to be in close contact with the bottom surface 31a and side surface 31b.

[0104] The object 11A that has been subjected to TAIKO grinding is processed while being supported by the frame 19 as described above. Then, after various processes have been performed on the object 11A, the reinforcing portion 33 is finally separated and removed from the object 11A.

[0105] In this embodiment, a case will be described in which the reinforcing portion 33 is separated from the target object 11A in processing step S2. For example, processing step S2 includes a step of forming a separation starting point in the target object 11 (separation starting point forming step) and a step of applying an external force to the target object 11 (external force applying step).

[0106] 10(A) is a partial cross-sectional front view showing the laser processing apparatus 50. For example, in the separation starting point forming step, the laser processing apparatus 50 performs laser processing on the object 11A to form a modified region that functions as a separation starting point in the object 11A.

[0107] The laser processing device 50 includes a chuck table (holding table) 52 that holds the frame unit 23 A. The lower surface of the chuck table 52 is a circular, flat surface that is roughly parallel to the horizontal plane, and constitutes a holding surface 52 a that holds the frame unit 23 A. The holding surface 52 a is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), and the like that are formed inside the chuck table 52.

[0108] A cylindrical support shaft 54 ​​that supports the chuck table 52 is connected to the upper surface side of the chuck table 52. The tip end (lower end) of the support shaft 54 ​​is fixed to the center of the upper surface side of the chuck table 52, and a rotational drive source (not shown) such as a motor that rotates the support shaft 54 ​​is connected to the base end (upper end) of the support shaft 54. When the rotational drive source is operated, the chuck table 52 and the support shaft 54 ​​rotate around a rotation axis that is approximately parallel to the vertical direction. In addition, a movement mechanism (not shown) that moves the chuck table 52 and the support shaft 54 ​​in the horizontal and vertical directions is connected to the support shaft 54.

[0109] The laser processing apparatus 50 also includes a laser irradiation unit 56 that irradiates a laser beam. The configuration and function of the laser irradiation unit 56 are similar to those of the laser irradiation unit 8 of the laser processing apparatus 2 (see FIG. 4).

[0110] Specifically, the laser irradiation unit 56 includes a laser oscillator (not shown) and a laser processing head 58 arranged below the chuck table 52. The laser processing head 58 has a built-in optical system that guides a pulsed laser beam 60 emitted from the laser oscillator toward the object 11A. The optical system includes optical elements such as a condenser lens that condenses the laser beam 60. The laser beam 60 emitted from the laser oscillator is irradiated from the laser processing head 58 toward the object 11A and is condensed at a predetermined position. Then, the laser beam 60 performs a predetermined laser processing on the object 11A.

[0111] Furthermore, the laser processing apparatus 50 includes a controller (not shown) that controls the laser processing apparatus 50. The configuration and functions of the controller are similar to those of the controller 14 of the laser processing apparatus 2 (see FIG. 4).

[0112] In the separation starting point forming step, a separation starting point is formed when separating the reinforcing portion 33 from the object 11A. Specifically, first, the frame unit 23A is held by the chuck table 52. For example, the frame unit 23A is brought into contact with the holding surface 52a so that the front surface 11a of the object 11A faces downward and the back surface 11b (the sheet 21 side) of the object 11A faces the holding surface 52a. In this state, when a suction force (negative pressure) of a suction source is applied to the holding surface 52a, the object 11A and the frame 19 are sucked and held by the chuck table 52 via the sheet 21. The chuck table 52 may be provided with a plurality of clamps (not shown) that grip the frame 19.

[0113] Next, the horizontal positional relationship between the chuck table 52 and the laser processing head 58 is adjusted so that the region (processed region) where the separation start point of the object 11A is to be formed overlaps the laser processing head 58 in the vertical direction. Also, the focusing position of the laser beam 60 is adjusted so that the laser beam 60 is focused on the processed region of the object 11A. In this embodiment, the outer periphery of the recess 31 formed in the object 11A (near the boundary between the recess 31 and the reinforcing portion 33) is set as the processed region.

[0114] Then, the chuck table 52 is rotated while irradiating a laser beam 60 from the laser processing head 58. This causes the laser beam 60 to scan annularly along the processing area (the outer periphery of the recess 31) of the object 11A. The irradiation conditions for the laser beam 60 can be set in the same way as when forming the modified layer 11c on the object 11 (see FIG. 4).

[0115] 10(B) is a cross-sectional view showing a portion of the object 11A in which a modified region (degraded region) 11e has been formed. When the object 11A is irradiated with the laser beam 60 as described above, the interior of the object 11A is modified and transformed by multiphoton absorption, and an annular modified region 11e is formed on the outer periphery of the recess 31 of the object 11A. The modified region 11e may be formed so as to extend from the surface 11a of the object 11 to the bottom surface 31a of the recess 31, or may be formed in a portion of the region between the surface 11a of the object 11 and the bottom surface 31a of the recess 31.

[0116] The region of the object 11A where the modified region 11e is formed is more fragile than other regions of the object 11A. Therefore, when an external force is applied to the object 11A, the object 11A breaks starting from the modified region 11e, and the reinforcing portion 33 is separated from the object 11A. In other words, the modified region 11e functions as a separation starting point (a trigger for separation).

[0117] Although the above description has been given of the case where modified region 11e is formed in object 11A, the separation starting point is not limited to modified region 11e. For example, a groove (laser-processed groove) that functions as a separation starting point may be formed on the outer periphery of recess 31 by performing ablation processing on object 11A. In this case, the wavelength of laser beam 60 is set so that at least a portion of laser beam 60 is absorbed by object 11A. In other words, a laser beam 60 that is absorbent by object 11A is used.

[0118] Next, an external force is applied to the target object 11A, and the reinforcing portion 33 is separated from the target object 11A starting from the modified region 11e (external force application step). For example, in the external force application step, the external force is applied by pressing a predetermined member (tool) against the reinforcing portion 33. Note that the reinforcing portion 33 may be separated from the target object 11A using a dedicated separation device, or may be separated manually by an operator.

[0119] 11(A) is a partial cross-sectional front view showing the separating device 70 when an external force is applied to the target object 11A. The separating device 70 includes a chuck table (holding table) 72 that holds the target object 11A. The lower surface of the chuck table 72 is a circular, flat surface that is roughly parallel to the horizontal plane, and forms a holding surface 72a that holds the target object 11A. The holding surface 72a is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), and the like formed inside the chuck table 72.

[0120] The diameter of the holding surface 72a side of the chuck table 72 is set to be smaller than the diameter of the recess 31 formed in the target object 11A. Therefore, the holding surface 72a side of the chuck table 72 can be inserted into the recess 31 of the target object 11A.

[0121] A cylindrical support shaft 74 that supports the chuck table 72 is connected to the upper surface side of the chuck table 72. The tip end (lower end) of the support shaft 74 is fixed to the center of the upper surface side of the chuck table 72, and a rotation drive source (not shown) such as a motor that rotates the support shaft 74 is connected to the base end (upper end) of the support shaft 74. When the rotation drive source is operated, the chuck table 72 and the support shaft 74 rotate around a rotation axis that is approximately parallel to the vertical direction. In addition, a movement mechanism (not shown) that moves the chuck table 72 and the support shaft 74 in the horizontal and vertical directions is connected to the support shaft 74.

[0122] A pair of external force application units 76 that apply an external force to the target object 11A are provided on both sides (the right and left sides in FIG. 11(A)) of the chuck table 72. Each of the pair of external force application units 76 includes a columnar movable member 78 and a flat support member 80 that protrudes horizontally from the lower end of the movable member 78.

[0123] A movement mechanism (not shown) that moves the movable member 78 in the horizontal and vertical directions is connected to the movable member 78. For example, the movement mechanism includes a linear actuator that moves the movable member 78 in the horizontal direction, and an air cylinder that moves (raises and lowers) the movable member 78 in the vertical direction. However, there are no limitations on the type, configuration, function, etc. of the movement mechanism as long as it is possible to move the movable member 78.

[0124] The support member 80 is fixed to the lower end of the movable member 78, and protrudes from the movable member 78 toward the chuck table 72. The upper surface of the support member 80 is a flat surface that is approximately parallel to the horizontal plane, and forms a support surface 80a that supports the components of the external force imparting unit 76.

[0125] A frame support base 82 that supports the frame 19 is provided on the support surface 80a of the support member 80. For example, the frame support base 82 is a disk-shaped member made of metal, resin, or the like, and supports the frame 19 from below.

[0126] Furthermore, a tool (pressing member) 84 that applies an external force to the reinforcing portion 33 of the target object 11A is provided on the support surface 80a of the support member 80. For example, the tool 84 is made of metal, resin, or the like, and is formed in the shape of an inverted truncated cone whose diameter increases from the bottom side to the top side. Therefore, the angle between the top surface and the side surface of the tool 84 is an acute angle, and a sharp corner is formed on the edge portion on the upper end side of the tool 84. However, the shape of the tool 84 is not limited to an inverted truncated cone, and it may be, for example, an inverted truncated polygonal pyramid shape.

[0127] The tool 84 is provided at a position closer to the chuck table 72 than the frame support base 82. That is, the tool 84 is disposed between the chuck table 72 and the frame support base 82 in a plan view. Note that, although Fig. 11(A) illustrates one frame support base 82 and one tool 84 provided on the support surface 80a of the support member 80, two or more frame support bases 82 and two or more tools 84 may be provided on the support surface 80a of the support member 80.

[0128] In the external force applying step, first, the target object 11A is held by the chuck table 72. Specifically, the target object 11A is placed below the chuck table 72 so that the front surface 11a faces downward and the back surface 11b (the sheet 21 side) faces the holding surface 72a. At this time, the target object 11A is positioned so that the holding surface 72a side of the chuck table 72 is inserted into the recess 31. In this state, when a suction force (negative pressure) from the suction source is applied to the holding surface 72a, the bottom surface 31a of the recess 31 of the target object 11A is sucked and held by the chuck table 72 via the sheet 21. In addition, a pair of external force applying units 76 are positioned so that the frame 19 is supported by the frame support base 82.

[0129] Next, the pair of external force application units 76 move closer to each other so as to sandwich the frame unit 23A. As a result, the object 11A is sandwiched between the pair of tools 84. At this time, the side of the tool 84 comes into contact with the reinforcing portion 33 of the object 11A, and the upper end (corner) of the tool 84 enters between the sheet 21 and the reinforcing portion 33. As a result, an external force is applied to the reinforcing portion 33 in an obliquely downward direction. In addition, the reinforcing portion 33 is partially peeled off from the sheet 21, which triggers the reinforcing portion 33 to peel off from the sheet 21.

[0130] Then, the chuck table 72 rotates with the tool 84 in contact with the reinforcing portion 33. As a result, the entire annular reinforcing portion 33 comes into contact with the tool 84, and an external force is applied to the entire reinforcing portion 33. In addition, a peel trigger is formed in the entire annular contact area where the sheet 21 and the reinforcing portion 33 are in contact.

[0131] FIG. 11(B) is a partial cross-sectional front view showing the separation device 70 when the reinforcing portion 33 is separated from the target object 11A. When an external force is applied to the reinforcing portion 33 as described above, the target object 11A breaks starting from the annular modified region 11e (see FIG. 10(B)). This separates the reinforcing portion 33 from the target object 11A. The reinforcing portion 33 is also peeled off from the sheet 21 and falls. In this way, the reinforcing portion 33 is removed from the target object 11A.

[0132] If the tool 84 is formed in an inverted truncated cone shape, the tool 84 may be configured to be rotatable around its central axis. In this case, when the chuck table 72 is rotated, the tool 84 rotates in conjunction with the rotation of the object 11A. This reduces friction acting between the reinforcing portion 33 and the tool 84, allowing the object 11A to be rotated smoothly.

[0133] As described above, when the reinforcing portion 33 is separated from the object 11A in processing step S2, the portion of the object 11A other than the reinforcing portion 33 remains as a plate-shaped substrate. That is, the sheet processing method according to this embodiment corresponds to a substrate manufacturing method in which the object 11 is processed to manufacture a substrate.

[0134] Here, as described above, if the object 11A has a recess 31, the sheet 21 is pressed against the bottom surface 31a of the recess 31 and fixed in a stretched state (see FIG. 9(B)). Then, when the reinforcing portion 33 is separated from the object 11A in processing step S2, the tension of the sheet 21 fixed to the recess 31 of the object 11A is released, and slack occurs in the non-fixed region 21a of the sheet 21.

[0135] Therefore, in this embodiment, after the reinforcing portion 33 is separated from the object 11A, a light absorbing film forming step S3 and a shrinking step S4 are performed to heat and shrink the non-fixed region 21a of the sheet 21, thereby reducing or eliminating slack in the sheet 21. The light absorbing film forming step S3 and the shrinking step S4 are the same as those in the first embodiment except for the matters described below (see FIGS. 6 and 8).

[0136] 12 is a partial cross-sectional front view showing the separating apparatus 70 in the light absorbing film forming step S3. In this embodiment, a case where the light absorbing film forming step S3 is performed using the separating apparatus 70 will be described.

[0137] The separating device 70 includes a light absorbing film forming unit 86 that forms a light absorbing film 25A on the sheet 21. The light absorbing film forming unit 86 is configured similarly to the light absorbing film forming unit 32 of the expanding device 20 (see FIG. 6).

[0138] For example, the light-absorbing film forming unit 86 includes a nozzle 88 that supplies a film material 90, which is a raw material for the light-absorbing film 25A. The nozzle 88 is disposed at a position overlapping the non-fixed region 21a of the sheet 21 provided on the frame unit 23A held by the chuck table 72. By supplying the film material 90 from the nozzle 88 to the non-fixed region 21a of the sheet 21, a light-absorbing film 25A that absorbs light and generates heat is formed in the non-fixed region 21a. Note that a specific example of the film material 90 is the same as the film material 36 (see FIG. 6) supplied from the light-absorbing film forming unit 32 in the first embodiment.

[0139] In the light-absorbing film forming step S3, the chuck table 72 is rotated together with the frame unit 23A while the film material 90 is supplied from the nozzle 88 toward the non-fixed region 21a of the sheet 21. As a result, the film material 90 is supplied in an annular shape along the circumferential direction of the non-fixed region 21a, and part or all of the non-fixed region 21a is covered with the film material 90. Thereafter, the film material 90 is dried to form a light-absorbing film 25A in contact with part or all of the non-fixed region 21a. For example, the light-absorbing film 25A is made of a resin film 27 (see FIG. 7) containing a light absorber 29.

[0140] However, instead of rotating the frame unit 23A, the nozzle 88 may be rotated. For example, a rotating arm (not shown) is connected to the nozzle 88, which rotates the nozzle 88 along a circular path that overlaps the non-fixed region 21a of the sheet 21. In this case, by operating the rotating arm to rotate the nozzle 88 while supplying the film material 90 from the nozzle 88 to the non-fixed region 21a of the sheet 21, the film material 90 can be supplied in a circular pattern along the circumferential direction of the non-fixed region 21a.

[0141] As described above, by supplying the film material 90 to the non-fixed region 21a of the sheet 21, an annular light-absorbing film 25A is formed in the non-fixed region 21a. The light-absorbing film 25A is formed between the object 11A and the frame 19 so as to be in contact with part or all of the non-fixed region 21a. Note that while Fig. 13 illustrates an example in which the light-absorbing film 25A is formed on the upper surface side of the non-fixed region 21a of the sheet 21, the light-absorbing film 25A may also be formed on the lower surface side of the non-fixed region 21a of the sheet 21.

[0142] 13 is a partial cross-sectional front view showing the separating device 70 in the shrinking step S4. In this embodiment, a case where the shrinking step S4 is performed using the separating device 70 will be described.

[0143] The separating device 70 includes a light irradiation unit 92 that irradiates the light absorbing film 25A with light. For example, the light irradiation unit 92 includes a light irradiation head 94 that irradiates with light 96. The light irradiation head 94 is installed at a position overlapping with the light absorbing film 25A formed in the non-fixed region 21a of the sheet 21. When the light irradiation head 94 irradiates the light 96 onto the light absorbing film 25A, the light absorbing film 25A absorbs the light 96 and generates heat.

[0144] The light irradiation unit 92 is configured in the same manner as the light irradiation unit 38 (see FIG. 8) of the extension device 20. For example, the light irradiation unit 92 is a laser irradiation unit that irradiates a laser beam as light 96. The wavelength of the light 96 is appropriately set so that the light 96 is absorbed by the light absorbing film 25A.

[0145] In the contraction step S4, the light irradiation unit 92 is activated, and light 96 is irradiated from the light irradiation head 94 toward the light absorbing film 25A. The light 96 then passes through the sheet 21, reaches the light absorbing film 25A, and is absorbed by the light absorbing film 25A and converted into heat. This causes the light absorbing film 25A to generate heat, heating the non-fixed region 21a of the sheet 21 that is in contact with the light absorbing film 25A. As a result, the non-fixed region 21a contracts, and slack occurring in the non-fixed region 21a is reduced or eliminated.

[0146] Furthermore, the chuck table 72 is rotated while the light irradiation head 94 irradiates the light absorbing film 25A with light 96. As a result, the light absorbing film 25A rotates together with the frame unit 23A, and the light 96 is scanned circularly along the circumferential direction of the light absorbing film 25A. The light 96 is then irradiated over the entire light absorbing film 25A, and the entire non-fixed region 21a in contact with the light absorbing film 25A is heated. As a result, slack in the sheet 21 is reduced or eliminated over the entire non-fixed region 21a.

[0147] However, instead of rotating the frame unit 23A and the light absorbing film 25A, the light 96 may be scanned circularly by rotating the light irradiation head 94. For example, a rotating arm (not shown) that rotates the light irradiation head 94 along a circular path that overlaps with the light absorbing film 25A is connected to the light irradiation head 94. In this case, by operating the rotating arm to rotate the light irradiation head 94 while irradiating the light 96 from the light irradiation head 94 onto the light absorbing film 25A, the light 96 can be scanned circularly along the circumferential direction of the light absorbing film 25A.

[0148] 13 shows an example in which the light emitting head 94 is disposed below the sheet 21 and the light absorbing film 25A. However, the light emitting head 94 can also be disposed above the sheet 21 and the light absorbing film 25A. In this case, light 96 emitted from the light emitting head 94 is directly irradiated onto the light absorbing film 25A and is absorbed by the light absorbing film 25A.

[0149] As described above, by irradiating the light absorbing film 25A in contact with the non-fixed region 21a of the sheet 21 with light 96, the non-fixed region 21a can be heated and shrunk even if the sheet 21 does not have the ability to absorb light 96. This makes it possible to suppress sagging of the sheet 21 regardless of the material of the sheet 21.

[0150] In the above, an example has been described in which the entire non-fixed region 21a of the sheet 21 is heated by the light absorbing film 25A. However, in the shrinking step S4, only a portion of the non-fixed region 21a may be heated depending on the characteristics of the sheet 21. For example, if a specific region of the non-fixed region 21a of the sheet 21 is particularly prone to sagging, only that region may be heated to shrink it. A specific example of a method for heating only a portion of the non-fixed region 21a is the same as in embodiment 1.

[0151] In the above description, the light absorbing film forming step S3 and the shrinking step S4 are performed after slack occurs in the sheet 21 in the processing step S2, thereby reducing or eliminating the slack in the sheet 21. However, by performing the light absorbing film forming step S3 and the shrinking step S4 in advance before the processing step S2 is performed, it is also possible to prevent the slack in the sheet 21 from occurring in the processing step S2.

[0152] Specifically, before performing processing step S2, the non-fixed region 21a of the sheet 21 is heated and shrunk in the above-described procedure (light absorbing film forming step S3 and shrinking step S4). As a result, the non-fixed region 21a of the sheet 21 is put in a state where it is more taut than the other regions, and the tension in the non-fixed region 21a is higher than in the other regions. Therefore, even if the reinforcing portion 33 is subsequently separated from the object 11A in processing step S2, slack is less likely to occur in the non-fixed region 21a. This prevents the sheet 21 from slackening in advance.

[0153] As described above, in the sheet processing method (substrate manufacturing method) according to this embodiment, the light absorbing film 25A formed in the non-fixed region 21a of the sheet 21 is irradiated with light 96 to heat the light absorbing film 25A, thereby heating and shrinking the non-fixed region 21a. This eliminates the need to set detailed irradiation conditions for the light 96 depending on the material of the sheet 21, and simplifies the process of suppressing sagging of the sheet 21.

[0154] In the above embodiment, the light absorbing film forming step S3 (see FIG. 12) and the shrinking step S4 (see FIG. 13) are performed using the separating device 70. However, the light absorbing film forming step S3 and the shrinking step S4 may be performed by a sheet processing device prepared separately from the separating device 70. In this case, the sheet processing device includes the light absorbing film forming unit 86 and the light irradiation unit 92 described above. Then, after the separating device 70 separates the reinforcing portion 33 from the target object 11A, the sheet processing device heats the non-fixed region 21a of the sheet 21, thereby suppressing sagging of the sheet 21.

[0155] In addition, the structure, method, etc. according to this embodiment can be appropriately modified and implemented without departing from the scope of the object of the present invention. Furthermore, this embodiment can be appropriately combined with embodiment 1, and the explanation of embodiment 1 can be appropriately cited for matters omitted in this embodiment.

[0156] (Embodiment 3) In the above-described first embodiment, a chip manufacturing method was described in which the target object 11 is divided into a plurality of chips 11d by expanding the sheet 21 (see FIG. 5(B)). However, when manufacturing the chips 11d, the sheet 21 may be expanded at times other than when the target object 11 is divided. Below, a form will be described in which the sheet 21 is expanded after the target object 11 is divided into a plurality of chips 11d.

[0157] In the sheet processing method (chip manufacturing method) according to this embodiment, first, in processing step S2, the target object 11 is divided into a plurality of chips 11d (division step). In this embodiment, a method of dividing the target object 11 that is different from that of embodiment 1 will be described.

[0158] 14(A) is a cross-sectional view showing an object 11 to be divided by cutting. For example, in the dividing step, the object 11 may be divided by cutting the object 11 along the planned dividing lines 13 with an annular cutting blade. For example, a cutting device 100 is used to cut the object 11.

[0159] The cutting device 100 includes a chuck table (holding table) 102 that holds the target object 11. The upper surface of the chuck table 102 is a circular, flat surface that is roughly parallel to the horizontal plane (XY plane), and constitutes a holding surface 102a that holds the target object 11. The holding surface 102a is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), and the like that are formed inside the chuck table 102.

[0160] A ball screw type movement mechanism (not shown) that moves the chuck table 102 along the X-axis direction is connected to the chuck table 102. A rotation drive source (not shown) such as a motor that rotates the chuck table 102 around a rotation axis that is approximately perpendicular to the holding surface 102a is also connected to the chuck table 102. Furthermore, a plurality of clamps 104 that grip and fix the frame 19 that supports the object 11 are provided around the periphery of the chuck table 102.

[0161] The cutting device 100 also includes a cutting unit 106 that performs cutting processing. The cutting unit 106 is installed above the chuck table 102 and includes a cylindrical spindle 108 that is arranged along the Y-axis direction. An annular cutting blade 110 is attached to the tip of the spindle 108. The cutting unit 106 is also connected to a ball screw type movement mechanism (not shown) that moves the cutting unit 106 along the Y-axis direction and the Z-axis direction.

[0162] The cutting blade 110 may be, for example, a hub-type cutting blade (hub blade). The hub blade has an annular hub base made of a metal such as an aluminum alloy and an annular cutting edge formed along the outer periphery of the hub base. The cutting edge of the hub blade is formed by an electroformed grinding stone containing abrasive grains made of diamond, cubic boron nitride (cBN), or the like, and a binder such as a nickel-plated layer that secures the abrasive grains. However, a washer-type cutting blade (washer blade) may also be used as the cutting blade 110. A washer blade is formed only by an annular cutting edge that contains abrasive grains and a binder made of metal, ceramics, resin, or the like that secures the abrasive grains.

[0163] When dividing the object 11 using the cutting device 100, the object 11 is first held by the chuck table 102. For example, the object 11 is placed on the chuck table 102 so that the front surface 11a faces upward and the back surface 11b (the sheet 21 side) faces the holding surface 102a. In addition, the frame 19 is fixed by a plurality of clamps 104. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 102a, the object 11 is sucked and held by the chuck table 102 via the sheet 21.

[0164] Next, the chuck table 122 is rotated, and the angle of the chuck table 102 is adjusted so that the length direction of the predetermined dividing line 13 coincides with the X-axis direction. Also, the position of the cutting unit 106 in the Y-axis direction is adjusted so that the cutting blade 110 is positioned on an extension of the predetermined dividing line 13. Furthermore, the height of the cutting unit 106 is adjusted so that the lower end of the cutting blade 110 is positioned below the back surface 11b of the object 11 (the upper surface of the sheet 21) and above the holding surface 102a (the lower surface of the sheet 21).

[0165] Then, while rotating the cutting blade 110, the chuck table 102 is moved along the X-axis direction. As a result, the chuck table 102 and the cutting blade 110 move relatively along the X-axis direction (processing feed), and the cutting blade 110 cuts the object 11 along the planned dividing lines 13. As a result, grooves (cutting grooves) 35 extending from the front surface 11a to the back surface 11b of the object 11 are formed along the planned dividing lines 13. Then, when the grooves 35 are formed along all of the planned dividing lines 13, the object 11 is divided into a plurality of chips 11d.

[0166] 14(B) is a cross-sectional view showing the object 11 to be divided by laser processing. In the dividing step, the object 11 may be divided by irradiating a laser beam along the intended dividing lines 13. For example, a laser processing device 120 is used for laser processing the object 11.

[0167] The laser processing device 120 includes a chuck table (holding table) 122 that holds the object 11. The upper surface of the chuck table 122 is a circular flat surface that is roughly parallel to the horizontal plane (XY plane), and constitutes a holding surface 122a that holds the object 11. The holding surface 122a is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), and the like that are formed inside the chuck table 122.

[0168] A ball screw type movement mechanism (not shown) that moves the chuck table 122 along the X-axis and Y-axis directions is connected to the chuck table 122. A rotation drive source (not shown) such as a motor that rotates the chuck table 122 around a rotation axis that is approximately perpendicular to the holding surface 122a is also connected to the chuck table 122. Furthermore, a plurality of clamps 124 that grip and fix the frame 19 that supports the object 11 are provided around the periphery of the chuck table 122.

[0169] The laser processing device 120 also includes a laser irradiation unit 126 that irradiates a laser beam. The laser irradiation unit 126 includes a laser oscillator (not shown) such as a YAG laser, a YVO4 laser, or a YLF laser, and a laser processing head 128 that is disposed above the chuck table 122.

[0170] The laser processing head 128 has a built-in optical system that guides a pulsed laser beam 130 emitted from a laser oscillator to the object 11. The optical system includes optical elements such as a condenser lens that condenses the laser beam 130. The laser beam 130 emitted from the laser oscillator is irradiated from the laser processing head 128 toward the object 11 and is condensed at a predetermined position. Then, the laser beam 130 performs a predetermined laser processing on the object 11.

[0171] When dividing the object 11 using the laser processing device 120, the object 11 is first held by the chuck table 122. For example, the object 11 is placed on the chuck table 122 so that the front surface 11a faces upward and the back surface 11b (the sheet 21 side) faces the holding surface 122a. In addition, the frame 19 is fixed by a plurality of clamps 124. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 122a, the object 11 is sucked and held by the chuck table 122 via the sheet 21.

[0172] Next, the chuck table 122 is rotated, and the angle of the chuck table 122 is adjusted so that the length direction of the predetermined dividing line 13 coincides with the X-axis direction. Also, the position of the chuck table 122 in the Y-axis direction is adjusted so that the area irradiated with the laser beam 130 is positioned on an extension of the predetermined dividing line 13. Furthermore, the height position of the laser processing head 128 and the arrangement of the optical system are adjusted so that the focal point of the laser beam 130 is positioned at the same height as the target object 11.

[0173] Then, the chuck table 122 is moved along the X-axis direction while irradiating the laser beam 130 from the laser processing head 128. This causes the chuck table 122 and the laser beam 130 to move relatively along the processing feed direction at a predetermined processing feed speed. As a result, the laser beam 130 is irradiated along the intended division line 13 from the front surface 11a side of the object 11.

[0174] The irradiation conditions of the laser beam 130 are set so that ablation processing is performed on the object 11. Specifically, the wavelength of the laser beam 130 is set so that at least a portion of the laser beam 130 is absorbed by the object 11. In other words, the laser beam 130 is absorbent by the object 11. In addition, other irradiation conditions of the laser beam 130 are also set appropriately so that appropriate ablation processing is performed on the object 11. For example, when the object 11 is a single crystal silicon wafer, the irradiation conditions of the laser beam 130 can be set as follows. Wavelength: 355nm Average output: 2W Repetition frequency: 200kHz Processing feed rate: 400mm / s

[0175] When the object 11 is processed under the above processing conditions, ablation processing is performed along the intended dividing lines 13 of the object 11, and grooves (laser processed grooves) 37 extending from the front surface 11a to the back surface 11b of the object 11 are formed along the intended dividing lines 13. When the grooves 37 are formed along all the intended dividing lines 13, the object 11 is divided into a plurality of chips 11d. Note that if it is difficult to form the grooves 37 by irradiating the laser beam once, the laser beam 130 may be irradiated along each intended dividing line 13 multiple times.

[0176] As described above, in the dividing step, the target object 11 is divided into a plurality of chips 11d. Then, the sheet 21 fixed to the target object 11 (the plurality of chips 11d) is expanded (expanding step). The expansion of the sheet 21 may be performed using a dedicated device such as the aforementioned expanding device 20 (FIG. 5(A)), or may be performed manually by an operator.

[0177] When the expansion step is performed, the intervals between the multiple chips 11d fixed to the sheet 21 are widened, and a certain gap or more is secured between adjacent chips 11d. This makes it less likely that the chips 11d will collide with each other when the object 11 is subsequently transported, and prevents damage to the chips 11d.

[0178] As described above, in processing step S2, the sheet 21 may be expanded after dividing the target object 11. However, expanding the sheet 21 causes slack in the sheet 21, as in the case where an external force is applied to the target object 11 (see FIG. 5(B)). Therefore, after processing step S2, a light absorbing film 25 is formed in the non-fixed region 21a of the sheet 21 (light absorbing film forming step S3, see FIG. 6), and then the light absorbing film 25 is irradiated with light 42 to heat the light absorbing film 25, thereby heating and shrinking the non-fixed region 21a (shrinkage step S4, see FIG. 8).

[0179] As described above, in the sheet processing method (chip manufacturing method) according to this embodiment, after dividing the object 11 and expanding the sheet 21 in processing step S2, the non-fixed region 21a of the sheet 21 is heated and shrunk in shrinking step S4, thereby reducing or eliminating slack occurring in the non-fixed region 21a.

[0180] Details of the light absorbing film forming step S3 and the shrinking step S4 are as described in embodiment 1. The timing of forming the light absorbing film 25 can be changed as appropriate as long as it is before the shrinking step S4. For example, the light absorbing film forming step S3 may be performed after the preparation step S1 and before the processing step S2. Furthermore, by performing the light absorbing film forming step S3 and the shrinking step S4 before performing the processing step S2, slack in the sheet 21 during the processing step S2 may be suppressed in advance.

[0181] In addition, the structure, method, etc. according to this embodiment can be appropriately modified and implemented without departing from the scope of the object of the present invention. Furthermore, this embodiment can be appropriately combined with embodiment 1, and the explanation of embodiment 1 can be appropriately cited for matters omitted in this embodiment. [Explanation of symbols]

[0182] 11,11A Object 11a Surface (first side) 11b Back side (2nd side) 11c Modified layer (altered layer) 11d chip (device chip) 11e Modified area (altered area) 13 Planned division line (street) 15 devices 17A Device Area 17B Surplus outer area 19 frames 19a opening 21 sheets (film) 21a Unfixed area 23, 23A Frame unit (object unit) 25,25A Light absorbing film 27 Resin film 29 Light absorber 31 Recess (groove) 31a Bottom 31b Side (inner wall) 33 Reinforcement part (convex part) 35 groove (cutting groove) 37 Groove (laser processed groove) 2. Laser processing equipment 4 Chuck table (holding table) 4a Holding surface 6 Clamp 8 Laser irradiation unit 10 Laser processing head 12 Laser Beam 14 Controller (control unit, control unit, control device) 20 Expansion Unit 22 Drums 24 Colo 26 Support member 28 tables 28a opening 30 Clamp 32 Light-absorbing film formation unit 34 nozzles 36 Membrane material 38 Light irradiation unit 40 Light irradiation head 42 light 50 Laser processing equipment 52 Chuck table (holding table) 52a Holding surface 54 Support shaft 56 Laser irradiation unit 58 Laser processing head 60 Laser Beam 70 Separation device 72 Chuck table (holding table) 72a Holding surface 74 Support shaft 76 External force application unit 78 Movable parts 80 Support member 80a support surface 82 Frame support 84 Tools (pressing members) 86 Light-absorbing film forming unit 88 nozzles 90 Membrane material 92 Light irradiation unit 94 Light irradiation head 96 light 100 Cutting equipment 102 Chuck table (holding table) 102a Holding surface 104 Clamp 106 Cutting unit 108 Spindle 110 Cutting Blade 120 Laser processing equipment 122 Chuck table (holding table) 122a Holding surface 124 Clamp 126 Laser irradiation unit 128 Laser Processing Head 130 Laser Beam

Claims

1. A sheet processing method for processing a sheet fixed to an object, comprising: a preparation step of preparing the object to which the sheet is fixed; a light absorbing film forming step of forming a light absorbing film that absorbs light and generates heat in an unfixed region of the sheet that is not fixed to the object; a shrinking step of irradiating the light absorbing film with light to cause the light absorbing film to generate heat, thereby heating and shrinking the non-fixed region.

2. the sheet is fixed to an annular frame having an opening in which the object can be placed; The sheet processing method according to claim 1 , wherein the non-fixed area is an annular area exposed between the object and the frame.

3. further comprising a processing step of processing the object; 3. The sheet processing method according to claim 1, wherein the shrinking step shrinks the unfixed area that has become loose in the processing step.

4. 4. The sheet processing method according to claim 3, wherein in the processing step, division start points are formed in the object along the planned division lines, and then the object is divided along the planned division lines by expanding the sheet.

5. In the preparation step, an object is prepared in which a recess is provided in a central portion and an annular reinforcing portion is provided on an outer periphery so as to surround the recess, and the sheet is fixed to the recess and the reinforcing portion; The sheet processing method according to claim 3 , wherein the processing step includes separating the reinforcing portion from the object.

6. A method for manufacturing chips by dividing an object to which a sheet is fixed, a preparation step of preparing the object to which the sheet is fixed; a processing step of forming division start points on the object along a planned division line, and then dividing the object into a plurality of chips along the planned division line by expanding the sheet; a light absorbing film forming step of forming a light absorbing film that absorbs light and generates heat in an unfixed region of the sheet that is not fixed to the object; a shrinking step of irradiating the light absorbing film with light to cause the light absorbing film to heat and shrink the non-fixed region.

7. A method for manufacturing chips by dividing an object to which a sheet is fixed, a preparation step of preparing the object to which the sheet is fixed; a processing step of dividing the object into a plurality of chips along a predetermined dividing line, and then expanding the sheet to widen the intervals between the plurality of chips; a light absorbing film forming step of forming a light absorbing film that absorbs light and generates heat in an unfixed region of the sheet that is not fixed to the object; a shrinking step of irradiating the light absorbing film with light to cause the light absorbing film to heat and shrink the non-fixed region.

8. A method for manufacturing a substrate by processing an object to which a sheet is fixed, a preparation step of preparing the object, the object having a recessed portion provided in a central portion and an annular reinforcing portion provided on an outer periphery surrounding the recessed portion, the sheet being fixed to the recessed portion and the reinforcing portion; a processing step of separating the reinforcement portion from the object to produce a substrate; a light absorbing film forming step of forming a light absorbing film that absorbs light and generates heat in an unfixed region of the sheet that is not fixed to the object; a shrinking step of irradiating the light absorbing film with light to cause the light absorbing film to generate heat, thereby heating and shrinking the non-fixed region.

Images