Method for treating object to be treated

Abstract

To provide a processing method of an object to be processed capable of suppressing adhesion of foreign matter to a sheet when performing predetermined processing in a state where the sheet is fixed to the object to be processed such as a wafer.SOLUTION: A method for processing an object to be processed includes a sheet fixing step 1001 of fixing a sheet having a fixing force to a surface of the object to be processed, and a processing step 1003,1004 of processing the object to be processed after the sheet fixing step 1001, in which in the processing step 1003,1004, a fixing force of a surplus region corresponding to the chamfered portion in a top view including the surface of the sheet is weaker than a fixing force of other regions.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for treating an object having a chamfered portion on its outer periphery. [Background technology]

[0002] When a semiconductor wafer having devices on one side is processed, a sheet for protecting the devices is fixed to the one side before the processing is carried out (see, for example, Patent Document 1).

[0003] The sheet includes, for example, an adhesive layer, and is fixed to one side of the wafer by the adhesive force of the adhesive layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-19461 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the outer periphery of a wafer is often chamfered, and when a sheet is fixed to a wafer with a chamfered outer periphery, the sheet may not be fixed to the wafer at the chamfered portion, resulting in the adhesive layer being exposed.

[0006] If the adhesive layer is exposed, there is a risk that foreign matter may adhere to the exposed adhesive layer during processing, etc.

[0007] When the sheet is peeled off from the wafer with foreign matter adhering to the exposed adhesive layer, there is a risk that the contaminants may fall into the equipment used to peel off the sheet or adhere to the device.

[0008] The present invention has been made in consideration of such problems, and aims to provide a method for processing a workpiece, such as a wafer, that can prevent foreign matter from adhering to a sheet when a predetermined process is performed while the sheet is fixed to the workpiece. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems and achieve the object, the method for processing a workpiece of the present invention is a method for processing a workpiece having a chamfered portion on its outer periphery, and comprises a sheet fixing step of fixing a sheet having fixing force to one surface of the workpiece, and a processing step of processing the workpiece after the sheet fixing step, wherein in the processing step, the fixing force of the excess area of ​​the sheet corresponding to the chamfered portion when viewed from above including the one surface is weaker than the fixing force of other areas.

[0010] The method for treating an object to be treated may further comprise, before the treatment step, a fixing force reducing step of reducing the fixing force of the excess region.

[0011] In the method for treating the object to be treated, the sheet has an adhesive layer whose adhesive strength decreases when irradiated with ultraviolet light, and in the fixing strength reduction step, the fixing strength of the excess area of ​​the sheet may be reduced by irradiating the excess area with ultraviolet light. [Effects of the Invention]

[0012] The present invention has an effect of preventing foreign matter from adhering to a sheet when a predetermined process is carried out with the sheet or the like fixed to a processing object such as a wafer. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view schematically showing a workpiece to be treated by a method for treating a workpiece according to a first embodiment. [Figure 2] FIG. 2 is a side view schematically showing the object to be treated shown in FIG. [Figure 3]FIG. 3 is a flowchart showing the flow of the method for processing an object to be processed according to the first embodiment. [Figure 4] FIG. 4 is a side view schematically showing a main part of the sheet fixed to the surface of the object to be treated in the sheet fixing step of the method for treating the object to be treated shown in FIG. [Figure 5] FIG. 5 is a perspective view that schematically shows the general configuration of a sheet applicator that performs the sheet fixing step of the method for treating an object to be treated shown in FIG. [Figure 6] FIG. 6 is a side view schematically showing the general configuration of the sheet applicator shown in FIG. [Figure 7] FIG. 7 is a side view schematically showing a state in which a sheet is attached to the surface of an object to be treated in the sheet fixing step of the method for treating an object to be treated shown in FIG. [Figure 8] FIG. 8 is a side view schematically showing a state in which the sheet is cut along the outer periphery of the object to be treated in the sheet fixing step of the method for treating the object to be treated shown in FIG. [Figure 9] FIG. 9 is a side view schematically showing the object to be treated after the sheet fixing step of the method for treating the object to be treated shown in FIG. [Figure 10] FIG. 10 is a side view, partially in section, schematically showing the fixing force reducing step of the method for treating an object shown in FIG. [Figure 11] FIG. 11 is a schematic side view showing the first processing step of the method for processing the object shown in FIG. [Figure 12] FIG. 12 is a perspective view schematically showing a fixing force reducing step in the method for treating an object to be treated according to a modified example of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made within the scope of the gist of the present invention.

[0015] [Embodiment 1] A method for treating an object to be treated according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view schematically showing an object to be treated by the method for treating an object to be treated according to the first embodiment. Fig. 2 is a side view schematically showing the object to be treated shown in Fig. 1. Fig. 3 is a flowchart showing the flow of the method for treating an object to be treated according to the first embodiment.

[0016] (Object to be processed) The method for treating an object to be treated according to the first embodiment is a method for treating an object to be treated 1 shown in Fig. 1. In the first embodiment, the object to be treated according to the method for treating an object to be treated according to the first embodiment is a wafer such as a disk-shaped semiconductor wafer or an optical device wafer, the substrate of which is silicon, sapphire, gallium arsenide, or the like.

[0017] 1, the workpiece 1 has a flat surface 2 (corresponding to one surface) of the substrate, and devices 4 are formed in each of the areas partitioned by a plurality of planned division lines 3. The devices 4 are, for example, integrated circuits such as ICs (Integrated Circuits) or LSIs (Large Scale Integrations), image sensors such as CCDs (Charge Coupled Devices) or CMOSs ​​(Complementary Metal Oxide Semiconductors), or various types of memories (semiconductor memory devices).

[0018] The workpiece 1 also has a chamfered portion 6 on its outer periphery (also referred to as the outer edge). The chamfered portion 6 is formed from the front surface 2 to the flat back surface 5 behind the front surface 2, and is formed in an arc-shaped cross section so that the center in the thickness direction is located at the outermost side. The workpiece 1 having the above-described configuration is thinned to a predetermined thickness by grinding or the like on the back surface 5, and then divided into individual devices 4 along the intended division lines 3.

[0019] (Method for treating material to be treated) As shown in FIG. 3, the method for processing an object according to the first embodiment includes a sheet fixing step 1001, a fixing force reducing step 1002, a first processing step 1003, a second processing step 1004, and a sheet removing step 1005.

[0020] (Seat fixing step) FIG. 4 is a side view schematically showing a main part of a sheet fixed to the surface of a workpiece in the sheet fixing step of the method for treating a workpiece shown in FIG. 3. FIG. 5 is a perspective view schematically showing the general configuration of a sheet applicator that performs the sheet fixing step of the method for treating a workpiece shown in FIG. 3. FIG. 6 is a side view schematically showing the general configuration of the sheet applicator shown in FIG. 5. FIG. 7 is a side view schematically showing a state in which a sheet has been attached to the surface of a workpiece in the sheet fixing step of the method for treating a workpiece shown in FIG. 3. FIG. 8 is a side view schematically showing a state in which a sheet is cut along the periphery of the workpiece in the sheet fixing step of the method for treating a workpiece shown in FIG. 3. FIG. 9 is a side view schematically showing a workpiece after the sheet fixing step of the method for treating a workpiece shown in FIG. 3.

[0021] The sheet fixing step 1001 is a step of fixing a sheet 10 shown in FIG. 4 having fixing power to the surface 2 of the workpiece 1. In the first embodiment, the sheet 10 fixed to the surface 2 of the workpiece 1 is formed in a sheet shape as shown in FIG. 4, and has a base layer 11 and an adhesive layer 12. The base layer 11 is made of a flexible and non-adhesive resin. The adhesive layer 12 is laminated on the base layer 11 and is made of a flexible and adhesive resin.

[0022] The sheet 10 has an adhesive layer 12, which provides the sheet 10 with a fixing force that fixes it to the workpiece 1, etc. In the first embodiment, the adhesive layer 12 is made of an ultraviolet-curing resin that hardens and reduces its adhesive force when irradiated with ultraviolet light 23 (shown in FIG. 10). In the present invention, the fixing force of the sheet 10 is not limited to the adhesive layer 12, but may be achieved by multiple layers.

[0023] The sheet 10 to be attached to the workpiece 1 is formed as a long sheet-like member, and is wound around the outer periphery of a core (not shown) at least once with the adhesive layer 12 positioned on the outer periphery, to form a roll, which constitutes a sheet roll 15 shown in Figures 5 and 6. In the first embodiment, both the length and width of the sheet 10 are longer than the outer diameter of the workpiece 1.

[0024] (sheet pasting machine) In the first embodiment, the sheet fixing step 1001 is performed by a sheet applicator 100 shown in Figures 5 and 6. The sheet applicator 100 shown in Figures 5 and 6 is an apparatus that applies a sheet 10 to the workpiece 1. The sheet applicator 100 shown in Figures 5 and 6 is an apparatus that applies the sheet 10 from a sheet roll 15 to the front surface 2 of the workpiece 1 and cuts the sheet 10 applied to the front surface 2 of the workpiece 1 along the outer periphery of the workpiece 1. Note that, although the sheet applicator 100 applies the sheet 10 to the front surface 2 of the workpiece 1 in the first embodiment, the sheet applicator 100 may also apply the sheet 10 to the back surface 5 of the workpiece 1 in the present invention.

[0025] As shown in Figures 5 and 6, the sheet application machine 100 includes a loading table 110, a sheet feed roller 120, a sheet application roller 130, a sheet cutter 140 (shown only in Figure 6), a sheet winding roller 150, a plurality of guide rollers 160, and a control unit 170.

[0026] The mounting table 110 holds the workpiece 1. The mounting table 110 has a flat mounting surface 111 along the horizontal direction on which the back surface 5 of the workpiece 1 is placed. The mounting surface 111 is made of a porous material such as porous ceramics, and is connected to a suction source (not shown). The mounting table 110 holds the workpiece 1 placed on the mounting surface 111 by suction from the suction source (not shown).

[0027] The sheet feed roller 120 has a cylindrical outer shape, and the sheet roll 15, i.e., the rolled sheet 10, is inserted into a core and attached to the sheet feed roller 120. The sheet feed roller 120 is supported so as to be rotatable about its axis. By rotating about its axis, the sheet feed roller 120 feeds the sheet 10 onto the loading surface 111 of the loading table 110, one end at a time.

[0028] The sheet adhering roller 130 presses the sheet 10, which has been delivered from the sheet delivery roller 120 onto the mounting surface 111 of the mounting table 110, against the surface 2 of the workpiece 1, which is held by suction on the mounting surface 111 of the mounting table 110, to adhere the sheet 10. The sheet adhering roller 130 is disposed above the mounting surface 111 of the mounting table 110. The sheet adhering roller 130 is formed in a cylindrical shape with its axis parallel to that of the sheet delivery roller 120, and is supported so as to be rotatable about its axis.

[0029] The sheet sticking roller 130 is provided so as to be able to move up and down in a direction perpendicular to the mounting surface 111 of the mounting table 110 by a movement mechanism (not shown), and is provided so as to be able to move along the mounting surface 111 in a direction perpendicular to the axis between a position shown by a solid line in Fig. 2 on one end of the mounting table 110 and a position shown by a dashed line in Fig. 2 on the other end. The sheet sticking roller 130, in a lowered state by the movement mechanism, moves along the mounting surface 111 between a position on one end of the mounting table 110 and a position on the other end, thereby sticking the sheet 10 onto the surface 2 of the workpiece 1 held on the mounting table 110.

[0030] The sheet cutter 140 cuts the sheet 10 along the outer periphery of the workpiece 1 after the sheet adhering roller 130 has adhered the sheet 10 to the workpiece 1. The sheet cutter 140 is disposed above the mounting surface 111 of the mounting table 110.

[0031] In the first embodiment, the sheet cutter 140 includes a cutter blade 141 and a cutter blade moving mechanism 142. The cutter blade 141 has a cutting edge at its lower end that is longer than the thickness of the sheet 10 fed onto the mounting surface 111 of the mounting table 110. The cutting edge of the cutter blade 141 faces the outer periphery of the workpiece 1 that is held by suction on the mounting surface 111 of the mounting table 110.

[0032] The cutter blade moving mechanism 142 raises and lowers the cutter blade 141 in a direction perpendicular to the mounting surface 111 of the mounting table 110, and moves the cutter blade 141 along the outer periphery of the workpiece 1. The cutter blade moving mechanism 142 includes a base 143 that is disposed on the center of the mounting surface 111 of the mounting table 110 and is raised and lowered by a lifting mechanism (not shown), a rotating shaft 144 that is rotatable about its axis on the base 143, that is disposed on the center of the mounting surface 111 of the mounting table 110, and that is rotated about its axis by a driving device such as a motor (not shown), and an arm 145 that extends from the rotating shaft 144 parallel to the mounting surface 111 of the mounting table 110 toward the outer periphery of the mounting table 110 and supports the cutter blade 141 at its tip.

[0033] The sheet cutter 140 lowers the base 143, i.e., the cutter blade 141, by the lifting mechanism of the cutter blade moving mechanism 142, and causes the cutting edge of the cutter blade 141 to cut into the outside of the outer periphery of the object to be processed 1 in the sheet 10 adhered to the object to be processed 1. The sheet cutter 140 rotates the arm 145, i.e., the cutter blade 141, around the axis of the rotation shaft 144 by a driving device such as a motor, and cuts the sheet 10 along the outer periphery of the object to be processed 1 with the cutter blade 141.

[0034] The sheet winding roller 150 winds up the unnecessary portion of the sheet 10 (corresponding to the sheet 10 that was not attached to the object to be processed 1) after the portion attached to the object to be processed 1 has been cut off by the sheet cutter 140. The unnecessary portion of the sheet 10 is the portion on the outer periphery side of the outer periphery of the object to be processed 1 that is cut off by the cutter blade 141.

[0035] In the first embodiment, the sheet take-up roller 150 is disposed in a position that positions the loading table 110 between it and the sheet feed roller 120 along the horizontal direction. The sheet take-up roller 150 is formed in a cylindrical shape with its axis parallel to the axes of the sheet feed roller 120 and the sheet bonding roller 130, and is rotated about its axis by a driving device such as a motor (not shown), thereby winding up the unnecessary portion of the sheet 10 onto its outer circumferential surface. The sheet take-up roller 150 winds up the unnecessary portion of the sheet 10 onto its outer circumferential surface, thereby pulling out the sheet 10 from the sheet roll 211 supported by the sheet feed roller 120 onto the loading surface 111 of the loading table 110.

[0036] In the first embodiment, two guide rollers 160 are provided, which are arranged between the end of the loading table 110 and the sheet winding roller 150, and sandwich unnecessary portions of the sheet 10 between them to transport the sheet 10 from the sheet feed roller 120 to the sheet winding roller 150, and also apply tension to the sheet 10 to prevent slack in the sheet 10. The guide roller 160 is formed in a cylindrical shape with its axis parallel to the axes of the sheet feed roller 120 and the sheet winding roller 150, and is provided so as to be rotatable about its axis.

[0037] The control unit 170 controls each of the above-mentioned components of the sheet applicator 100, causing the sheet applicator 100 to perform the applicator operation of applicating the sheet 10 to the workpiece 1. The control unit 170 is a computer having an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having memory such as a ROM (read only memory) or RAM (random access memory), and an input / output interface device. The arithmetic processing device of the control unit 170 performs arithmetic processing in accordance with a computer program stored in the storage device, and outputs control signals for controlling the sheet applicator 100 to each of the above-mentioned units of the sheet applicator 100 via the input / output interface device.

[0038] In addition, the control unit 170 is connected to a display unit that displays the status of the pasting operation and images, an input unit that the operator uses to input information, etc. into the control unit 170 of the sheet pasting machine 100, and an alarm unit that emits at least one of sound and light to alert the operator.

[0039] In the first embodiment, the sheet fixing step 1001 is also a sticking operation in which the sheet applicator 100 having the above-described configuration sticks the sheet 10 to the surface 2 of the workpiece 1. In the first embodiment, in the sheet fixing step 1001, the control unit 170 of the sheet applicator 100 receives conditions for the sticking operation input by an operator or the like, and when the control unit 170 receives an instruction to start the sticking operation from the operator or the like, the sheet applicator 100 starts the sticking operation. When the sticking operation starts, the sheet applicator 100 starts the sheet fixing step 1001.

[0040] In embodiment 1, in the sheet fixing step 1001, the sheet applying machine 100 places the back surface 5 of the workpiece 1 on the loading surface 111 of the loading table 110 by a conveying unit not shown, and suction-holds the back surface 5 of the workpiece 1 on the loading surface 111, exposing the front surface 2.

[0041] In the first embodiment, in the sheet fixing step 1001, as shown in Fig. 7 , the sheet applicator 100 lowers the sheet applicator roller 130 to press the adhesive layer of the sheet 10 against the surface 2 of the workpiece 1 that is held by suction on the mounting surface 111 of the mounting table 110, and moves the sheet applicator roller 130 along the mounting surface 111 from the position indicated by the solid line in Fig. 7 to the position indicated by the dashed line to adhere the sheet 10 to the surface 2 of the workpiece 1. The sheet applicator 100 raises the sheet applicator roller 130 to retract the sheet applicator roller 130 from above the mounting surface 111.

[0042] In the first embodiment, in the sheet fixing step 1001, the sheet applicator 100 lowers the cutter blade 141 to make the cutter blade 141 cut into the outside of the outer periphery of the object to be treated 1 of the sheet 10, as shown in Fig. 8. In the first embodiment, in the sheet fixing step 1001, the sheet applicator 100 causes the cutter blade moving mechanism 142 to rotate the cutter blade 141 by 360 degrees or more around the axis of the rotation shaft 144, and cuts the sheet 10 along the outer periphery of the object to be treated 1 while making the cutting edge of the cutter blade 141 cut into the outside of the outer periphery of the object to be treated 1 of the sheet 10.

[0043] In the first embodiment, in the sheet fixing step 1001, the sheet applying machine 100 cuts the sheet 10, then raises the sheet cutter 140, and then winds up an amount of sheet 10 to be applied to one workpiece 1 with the sheet winding roller 150, and moves the sheet 10 by the distance of one workpiece 1. In the first embodiment, in the sheet fixing step 1001, the sheet applying machine 100 releases the suction hold of the loading surface 111 of the loading table 110, and the transport unit carries out the workpiece 1 on the loading surface 111, thereby completing the operation of applying the sheet 10, i.e., the sheet fixing step 1001.

[0044] After the sheet fixing step 1001, as shown in Fig. 9, the workpiece 1 has the adhesive layer 12 attached to the surface 2, and the sheet 10 fixed to the excess area 13 corresponding to the chamfered portion 6 of the adhesive layer 12 with a gap therebetween. The excess area 13 corresponding to the chamfered portion 6 of the adhesive layer 12 is an area of ​​the adhesive layer 12 that overlaps with the chamfered portion 6 in the thickness direction of the workpiece 1.

[0045] (Reduced fixing force step) Fig. 10 is a side view, partially in cross section, schematically showing the fixing force reducing step of the method for processing the workpiece shown in Fig. 3. The fixing force reducing step 1002 is a step for reducing the fixing force of the excess region before processing steps 1003 and 1004.

[0046] In the first embodiment, in the fixing force reducing step 1002, as shown in FIG. 10 , a disk-shaped mask 30 is placed on the flat upper surface 22 of a disk-shaped irradiation table 20 made of a light-transmitting material such as glass and incorporating an ultraviolet light source 21, and the surface 2 of the workpiece 1 is placed on the mask 30 via a sheet 10. The mask 30 includes a circular shielding portion 31 that overlaps the surface 2 of the workpiece 1 in the thickness direction via the sheet 10, and a ring-shaped transmitting portion 32 that is provided on the outer periphery of the shielding portion 31 and overlaps the chamfered portion 6 of the workpiece 1 in the thickness direction via the excess region 13 of the sheet 10. The shielding portion 31 blocks ultraviolet light 23 emitted by the ultraviolet light source 21. The transmitting portion 32 transmits ultraviolet light 23 emitted by the ultraviolet light source 21.

[0047] In the first embodiment, in the fixing force reducing step 1002, as shown in Fig. 10, the irradiation table 20 irradiates ultraviolet light 23 from the ultraviolet light source 21 through the mask 30 onto the adhesive layer 12 of the sheet 10. Then, the ultraviolet light 23 is blocked by the shielding portion 31, and the ultraviolet light 23 is not irradiated onto the area adhered to the surface 2 of the adhesive layer 12. Furthermore, the ultraviolet light 23 passes through the transmitting portion 32 and is irradiated onto the excess area 13 of the sheet 10, thereby reducing the adhesive force, i.e., the fixing force, of the excess area 13. In this way, in the fixing force reducing step 1002, the fixing force of the excess area 13 of the sheet 10 is reduced by irradiating the excess area 13 of the sheet 10 with ultraviolet light 23.

[0048] (First processing step) Fig. 11 is a side view showing a schematic diagram of the first processing step of the processing method for the workpiece shown in Fig. 3. The first processing step 1003 is a processing step for processing the workpiece 1 after the sheet fixing step 1001. In the first embodiment, the first processing step 1003 is performed after the fixing force reducing step 1002. Therefore, in the first processing step 1003, the fixing force of the excess region 13 corresponding to the chamfered portion 6 in the top view including the surface 2 of the sheet 10 is weaker than the fixing force of the other regions.

[0049] In the first embodiment, in the first processing step 1003, the grinding device 50 shown in FIG. 11 suction-holds the front surface 2 of the workpiece 1 on the holding surface 52 of the holding table 51 via the sheet 10. In the first processing step 1003, as shown in FIG. 11, the grinding device 50 rotates the grinding wheel 53 about its axis using the spindle 55 and rotates the holding table 51 about its axis while supplying grinding water, and brings the grinding wheel 54 into contact with the back surface 5 of the workpiece 1 and approaches the holding table 51 at a predetermined feed rate, thereby grinding the entire back surface 5 of the workpiece 1 with the grinding wheel 54 and thinning the workpiece 1 to a predetermined thickness. In the first processing step 1003, the workpiece 1 is subjected to grinding as a processing.

[0050] (Second processing step) The second processing step 1004 is a processing step for processing the workpiece 1 after the sheet fixing step 1001. In addition, in the first embodiment, the second processing step 1004 is performed after the fixing force reducing step 1002, so that in the second processing step, the fixing force of the excess region 13 corresponding to the chamfered portion 6 in the top view including the surface 2 of the sheet 10 is weaker than the fixing force of the other regions.

[0051] In the first embodiment, in the second processing step 1004, a cutting device (not shown) holds the workpiece 1 by suction on the holding surface of a holding table, and cuts the planned division lines 3 with a cutting blade to divide the workpiece 1 into individual devices 4. In the first embodiment, in the second processing step 1004, cutting is performed as a processing on the workpiece 1. Note that in the present invention, in addition to cutting, various other processing may be performed on the workpiece 1 as a processing, such as picking up the divided devices 4, in the second processing step 1004.

[0052] (Sheet removal step) The sheet removing step 1005 is a step of removing the sheet 10. In the first embodiment, the sheet removing step 1005 removes the sheet 10, thereby completing the method for treating the object to be treated.

[0053] In the method for processing a workpiece according to the first embodiment described above, processing steps 1003 and 1004 are performed in a state in which the fixing force of excess region 13 of sheet 10 corresponding to chamfered portion 6 of workpiece 1 is weaker than the fixing force of other regions. Therefore, the method for processing a workpiece according to the first embodiment can reduce the possibility of foreign matter adhering to sheet 10 in processing steps 1003 and 1004.

[0054] As a result, the method for processing a workpiece according to embodiment 1 has the effect of suppressing the adhesion of foreign matter to the sheet 10 when a predetermined process is carried out with the sheet 10 or the like fixed to the workpiece 1 such as a wafer.

[0055] [Modification] A method for treating a workpiece according to a modified example of embodiment 1 will be described with reference to the drawings. Fig. 12 is a perspective view schematically showing the fixing force reducing step of the method for treating a workpiece according to a modified example of embodiment 1. In Fig. 12, the same parts as those in embodiment 1 are designated by the same reference numerals, and their description will be omitted.

[0056] The method for processing an object according to a modification of the first embodiment is the same as that of the first embodiment, except that the fixing force reducing step 1002 is different. In the modification, in the fixing force reducing step 1002, the back surface 5 of the object 1 is held on the holding surface 61 of the holding table 60, as shown in Fig. 12, and ultraviolet rays 23 are irradiated from the ultraviolet irradiation unit 70 onto the entire periphery of the excess region 13 of the sheet 10. In the modification, for example, the spot diameter of the ultraviolet rays 23 irradiated by the ultraviolet irradiation unit 70 is 200 µm.

[0057] The processing method for the workpiece according to the modified example performs processing steps 1003 and 1004 in a state in which the fixing force of the excess area 13 of the sheet 10 corresponding to the chamfered portion 6 of the workpiece 1 is weaker than the fixing force of other areas, and therefore, as in embodiment 1, when a predetermined processing is performed in a state in which the sheet 10 or the like is fixed to the workpiece 1 such as a wafer, it has the effect of suppressing adhesion of foreign matter to the sheet 10.

[0058] The present invention is not limited to the above-described embodiment. In other words, various modifications can be made without departing from the gist of the present invention. For example, in the present invention, when irradiating ultraviolet light 23, the atmosphere may be purged with nitrogen before irradiation, or the workpiece 1 may be submerged in water before irradiation with ultraviolet light 23, in order to prevent oxygen-induced inhibition. When irradiating ultraviolet light 23 while the workpiece 1 is submerged in water, even if the chamfered portion 6 and the excess region 13 are partially fixed, water is likely to penetrate through the unfixed portions due to capillary action, further accelerating the curing of the adhesive layer 12 in the excess region 13 by ultraviolet light 23. [Explanation of symbols]

[0059] 1. Material to be processed 2 Surface (one side) 6 Chamfered part 10 sheets 12 Glue layer 13 Surplus Area 23 Ultraviolet rays 1001 Seat fixing step 1002 Fixation force reduction step 1003 First processing step (processing step) 1004 Second processing step (processing step)

Claims

1. A method for treating an object having a chamfered portion on its outer periphery, comprising: a sheet fixing step of fixing a sheet having fixing force to one surface of the object to be treated; a processing step of processing the object to be processed after the sheet fixing step, A method for processing a workpiece, characterized in that in the processing step, the fixing force of the excess area corresponding to the chamfered portion when viewed from above including the one surface of the sheet is weaker than the fixing force of other areas.

2. 2. The method for treating an object to be treated according to claim 1, further comprising a fixing force reducing step of reducing the fixing force of the excess region before the treating step.

3. The sheet has an adhesive layer whose adhesive strength decreases when irradiated with ultraviolet light, 3. The method for treating an object to be treated according to claim 2, wherein the fixing force reducing step reduces the fixing force of the excess area of ​​the sheet by irradiating the excess area with ultraviolet light.

Images