Workpiece unit

Abstract

Provided is a workpiece unit, which can determine from its appearance whether a process accompanied by an external stimulus has been performed on it. The workpiece unit (1) comprises: a wafer (2); a belt (6) which is attached to the wafer (2); and an annular frame (7), the outer periphery of the belt (6) being attached to the annular frame (7), and the annular frame (7) having an opening (7A) at the center, the wafer (2) being arranged in the opening (7A) of the annular frame (7) by means of the belt (6), wherein the belt (6) has a color-changing layer which reversibly changes color according to a temperature change accompanied by cooling.

Description

Technical Field

[0001] The present invention relates to a workpiece unit, which comprises: a workpiece; a belt adhered to the workpiece; and an annular frame to which the outer peripheral edge of the belt is adhered, and the annular frame has an opening at the center. Background Art

[0002] Generally, there is known a workpiece unit, which has: a plate-shaped workpiece such as a semiconductor wafer; a tape attached to the workpiece; and an annular frame to which the outer periphery of the tape is attached, and the annular frame has an opening in the center. This workpiece unit sometimes has a ductile object such as a TEG (Test Element Group) arranged on a predetermined line for dividing the workpiece and a DAF (Die Attach Film) attached between the workpiece and the tape. Someone has proposed the following technology: when the tape is expanded to divide the workpiece together with the ductile object, the workpiece unit is cooled (external stimulation is given) to reduce the ductility of the ductile object and efficiently divide it (for example, refer to patent document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2006-049591

[0004] However, it is not possible to judge from the appearance whether the cooling is sufficient, so when the expansion is performed in a state of insufficient cooling, there is a problem that the ductile object is stretched and cannot be divided. In addition, once the band is expanded, the band will stretch, so it is not possible to fully expand with the stretched band, and even if the workpiece unit is cooled again, the ductile object cannot be divided. Summary of the invention

[0005] Therefore, an object of the present invention is to provide a workpiece unit that can determine from its appearance whether or not it has been processed in response to an external stimulus.

[0006] According to the present invention, a workpiece unit is provided, which includes: a workpiece; a belt, which is adhered to the workpiece; and an annular frame, the outer periphery of the belt is adhered to the annular frame, and the annular frame has an opening in the center, and the workpiece is arranged in the opening of the annular frame with the help of the belt, wherein the belt reversibly changes color due to external stimulation.

[0007] According to this structure, the belt changes color due to external stimulation, so it can be easily judged from the appearance whether the workpiece unit has been processed with external stimulation. Therefore, it is possible to prevent the inconvenience caused by feeding the unprocessed workpiece into the next process.

[0008] Preferably the external stimulus is a temperature change.

[0009] Preferably, the ribbon changes color to a first color at a first temperature, and changes color to a second color different from the first color at a second temperature different from the first temperature.

[0010] In the workpiece unit of the present invention, since the belt changes color due to an external stimulus, it can be easily determined from the appearance whether the workpiece unit has been processed in accordance with the external stimulus. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a perspective view showing a configuration example of a workpiece unit according to an embodiment of the present invention.

[0012] Figure 2 It is a partial cross-sectional view of the workpiece unit.

[0013] Figure 3 It is a perspective view showing a step of forming a reformed layer along a planned dividing line of a wafer of a workpiece unit.

[0014] Figure 4 It is a cross-sectional view showing a state before the wafer is divided under cooling.

[0015] Figure 5 It is a cross-sectional view showing a state after the wafer is divided under cooling.

[0016] Figure 6 It is a bottom view showing the workpiece unit with being sufficiently cooled.

[0017] Figure 7 It is a bottom view of a workpiece unit showing insufficient belt cooling.

[0018] Description of symbols

[0019] 1: workpiece unit; 2: wafer (workpiece); 3: predetermined dividing line; 6: belt; 6C: color-changing layer; 7: annular frame; 7A: opening; 8: TEG (ductile material); 9: modified layer; 11: device chip; 20: laser processing device; 30: expansion device; 31: frame holding workbench; 32: lifting unit; 33: belt expansion drum; 34: shooting unit; 50: cooling chamber. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited by the contents described in the following embodiments. In addition, the constituent elements described below include contents that can be easily thought of by those skilled in the art, and substantially the same contents. In addition, the structures described below can be appropriately combined. In addition, various omissions, substitutions or changes in the structure can be made within the scope of the gist of the present invention.

[0021] Figure 1 It is a perspective view showing a configuration example of a workpiece unit according to the present embodiment. Figure 2 It is a partial cross-sectional view of the unit of the workpiece. Figure 1 As shown, the workpiece unit 1 is configured to include: a wafer 2 as a workpiece; a belt 6 attached to the wafer 2; and an annular frame 7, to which the outer edge 61 of the belt 6 is attached, and the annular frame 7 has an opening 7A at the center. The annular frame 7 has an opening 7A having a larger diameter than the wafer 2, and the wafer 2 is held in the opening 7A by the belt 6.

[0022] Wafer 2 is a disk-shaped semiconductor wafer with silicon as the base material, or an optical device wafer with sapphire, SiC (silicon carbide), etc. as the base material. Wafer 2 has devices 4 formed in a plurality of areas divided by a grid-shaped predetermined division line (predetermined cutting line) 3 formed on the front side 2A. In addition, a TEG (Test Element Group) 8 as a ductile object is formed on the predetermined division line 3. TEG 8 is formed of a ductile metal, etc., and is a test pattern for discovering problems in the design and manufacturing of device 4. TEG 8 is arranged at a predetermined predetermined position of the predetermined division line 3 of wafer 2. In the present embodiment, a disk-shaped wafer is exemplified as the workpiece, but in addition to the wafer, a packaging substrate, a ceramic substrate, a glass substrate, etc. formed in a rectangular plate shape can also be used.

[0023] like Figure 2As shown, the belt 6 is, for example, an expansion belt, and the belt 6 has: a base material 6A made of a synthetic resin having elasticity; an adhesive layer (paste layer) 6B laminated on the upper surface side of the base material 6A; and a color-changing layer (color-changing portion) 6C laminated on the lower surface side of the base material 6A. The belt 6 is attached to the back surface 2B of the wafer 2 with the adhesive layer 6B as the upper surface. The color-changing layer 6C of the present embodiment is formed to include a first temperature-indicating ink that changes from colorless to a first color when a temperature change (external stimulus) accompanied by cooling, for example, reaches a predetermined first temperature (for example, 0° C.) or less, and a second temperature-indicating ink that changes from colorless to a second color different from the first color when a predetermined second temperature (for example, -100° C.) lower (different) than the first temperature is reached. The first temperature-indicating ink and the second temperature-indicating ink are respectively dispersed over the entire surface of the color-changing layer 6C. The color change of the first temperature-indicating ink and the second temperature-indicating ink is reversible, and can change color according to the temperature of the belt 6 (the workpiece unit 1). According to this structure, the operator can easily judge the approximate cooling temperature of the workpiece unit 1 from the appearance by observing that the color-changing layer 6C changes color to any color of the first color or the second color (including a color mixed with the first color). In addition, in the present embodiment, the first temperature-indicating ink and the second temperature-indicating ink are configured to change from colorless to colored by temperature changes below a predetermined temperature, but if the color after the color change is known in advance, it is also possible to change from colored to a different color.

[0024] Next, a processing step of the workpiece unit 1 in which the wafer 2 is supported on the annular frame 7 by the belt 6 provided with the color-changing layer 6C is described. In this embodiment, the wafer 2 is divided into device chips by expanding the belt 6 (cooling and expanding process) while the workpiece unit 1 is cooled. Figure 3 The figure shows the process of forming a modified layer along the planned dividing line of the wafer of the workpiece unit. Figure 4 The figure shows the state before the wafer is divided under cooling. Figure 5 This is a diagram showing a state where the wafer is divided while being cooled. Figure 6 It is a bottom view showing the workpiece unit with being sufficiently cooled. Figure 7 It is a bottom view of a workpiece unit showing insufficient belt cooling.

[0025] First, through Figure 3The laser processing device 20 shown forms a modified layer 9 inside the wafer 2 along the planned dividing line 3. The modified layer 9 refers to a modified region in which the density, refractive index, mechanical strength and other physical properties are different from those of the surroundings, and examples thereof include a melt-processed region, a crack region, an insulation breakdown region, a refractive index change region, and a region where these regions are mixed. The laser processing device 20 includes an irradiation head 21 that irradiates a laser beam 21A toward the wafer 2, and an imaging unit 22 that is arranged in parallel with the irradiation head 21 in the X direction. The irradiation head 21 includes a laser oscillator (not shown) that oscillates a laser beam of a wavelength that is transparent to the wafer 2, and a condenser (not shown) that condenses the laser beam emitted from the laser oscillator. The irradiation head 21 adjusts the condensing position (focal position) of the laser beam 21A irradiated toward the wafer 2 in the Z direction (vertical direction). The imaging unit 22 is a camera that captures the arrangement of the wafer 2 relative to the irradiation head 21 and the processing of the wafer 2.

[0026] The workpiece unit 1 is held on a chuck table (not shown). The chuck table is configured to be movable in the above-mentioned X direction. In addition, the chuck table is configured to be rotatable around an axis parallel to the vertical direction. In the present embodiment, the chuck table that holds the workpiece unit 1 is configured to move in the X direction, but as long as the laser processing device 20 moves relative to the workpiece unit 1 in the X direction, the laser processing device 20 may also be configured to move in the X direction.

[0027] When forming the modified layer 9 inside the wafer 2, the laser processing device 20 captures the front surface 2A of the wafer 2 through the imaging unit 22, and after obtaining the position of the predetermined dividing line 3, the focusing position of the laser beam 21A converged by the condenser is positioned inside the wafer 2. And, while the chuck table is processing and feeding in the X1 direction, the laser beam 21A is irradiated along the predetermined dividing line 3 of the wafer 2. Thus, the modified layer 9 is formed inside the wafer 2 along the predetermined dividing line 3. Here, multiple layers (for example, 3 layers) of the modified layer 9 can be formed in the thickness direction of the wafer 2 with respect to one predetermined dividing line 3. When the modified layer 9 is formed along all the predetermined dividing lines 3, the process of forming the modified layer 9 is completed.

[0028] Next, use Figure 4 The expansion device 30 shown expands the tape 6 to split the wafer 2 along the planned splitting line 3. The expansion device 30 of this embodiment is arranged in the cooling chamber 50, and expands the tape 6 (cooling expansion process) while cooling the workpiece unit 1. The cooling chamber 50 has a cold air supply port (not shown), and cold air can be supplied from the cold air supply port to cool the inside of the cooling chamber 50 to a desired temperature.

[0029] The expansion device 30 includes a frame holding table 31, a lifting unit 32, a belt expansion drum 33, and a photographing unit 34. The frame holding table 31 is formed in an annular shape, and is provided with a mounting surface 31A for mounting the annular frame 7 and a clamp 31B for holding the annular frame 7. The lifting unit 32 is arranged below the frame holding table 31 to lift and lower the frame holding table 31. The lifting unit 32 is configured to include a plurality of cylinders 32A, and a piston rod 32B of each cylinder 32A is connected to the lower surface of the frame holding table 31. The lifting unit 32 moves the mounting surface 31A of the frame holding table 31 in the up-down direction between a reference position at a height substantially the same as the upper end 33A of the belt expansion drum 33 and an expansion position at a predetermined amount below the upper end 33A by extending and retracting the piston rod 32B.

[0030] The belt expansion drum 33 is a cylindrical body arranged inside the above-mentioned annular frame holding table 31, and has an inner diameter and an outer diameter that are larger than the wafer 2 of the workpiece unit 1 and smaller than the opening 7A of the annular frame 7. Therefore, the upper end 33A of the belt expansion drum 33 contacts the belt 6 between the wafer 2 in the workpiece unit 1 and the annular frame 7. The imaging unit 34 is, for example, arranged inside the belt expansion drum 33, and is a camera that mainly photographs the belt 6 from the lower surface side of the workpiece unit 1. The photographed image is displayed on a display device such as a color monitor (not shown), so that the operator can confirm the color of the belt 6.

[0031] When the wafer 2 is divided, Figure 4 As shown, the workpiece unit 1 is held on the frame holding table 31 of the expansion device 30. Specifically, the annular frame 7 is placed on the mounting surface 31A of the frame holding table 31, and the annular frame 7 is held by the clamp 31B. At this time, the piston rod 32B of the lifting unit 32 is extended so that the mounting surface 31A of the frame holding table 31 is positioned at a reference position at substantially the same height as the upper end 33A of the belt expansion drum 33.

[0032] Next, cold air is supplied from the cold air supply port to cool the inside of the cooling chamber 50 to a desired temperature. Thus, the workpiece unit 1 (belt 6) in the cooling chamber 50 is cooled to a desired temperature. In the present embodiment, the belt 6 of the workpiece unit 1 is formed to include a first temperature indicating ink that changes color to a first color when a predetermined first temperature is reached according to a temperature change (external stimulus) and a second temperature indicating ink that changes color to a second color when a predetermined second temperature lower than the first temperature is reached. Here, when a ductile object such as TEG 8 provided on the predetermined dividing line 3 of the wafer 2 is cooled to a temperature lower than a predetermined reference temperature (e.g., -80°C), the ductility decreases, and it is determined that efficient dividing can be performed. The reference temperature varies depending on the type, material, or size of the ductile object, and is therefore set by prior experiments, etc. In the present embodiment, the second temperature (e.g., -100°C) is set to a temperature lower than the reference temperature (-80°C), and the first temperature (e.g., 0°C) is set to a temperature higher than the reference temperature.

[0033] Therefore, the operator can easily judge from the appearance whether the workpiece unit 1 (TEG 8) has been cooled to below the reference temperature by observing whether the belt 6 has changed color and the size of the color-changed area. Figure 6 As shown in FIG. 1 , when the outer edge 65A of the region 65 that changes color to the second color reaches a position outside the outer periphery of the wafer 2 (at Figure 6 If the outer edge 61 of the belt 6 is reached, the operator can judge that at least TEG 8 ( Figure 1 ) is cooled to a temperature below the second temperature. Figure 5 As shown in FIG. 1 , the piston rod 32B of the lifting unit 32 is retracted, and the mounting surface 31A of the frame holding table 31 is lowered to the expanded position. Therefore, the annular frame 7 fixed to the mounting surface 31A of the frame holding table 31 is also lowered, so that the belt 6 mounted on the annular frame 7 abuts against the upper end 33A of the belt expansion drum 33 and expands. As a result, a tensile force is radially applied to the wafer 2 attached to the belt 6, so that the wafer 2 is moved along the modified layer 9 ( Figure 4 ) is divided into device chips 11. At this time, the TEG 8 on the planned dividing line 3 is cooled to a temperature below the second temperature, and the ductility is reduced, so that the TEG 8 can be reliably broken together with the wafer 2.

[0034] On the other hand, Figure 7As shown in FIG. 1 , when the region 66 that changes color to the first color exists on the inner side of the wafer 2, the operator can judge that the entire wafer 2 has not been cooled to below the second temperature, and therefore a part of the TEG 8 has not been sufficiently cooled, and there is a possibility of poor segmentation. Therefore, in the case of insufficient cooling, cooling is continued until at least the outer edge 65A of the region 65 that changes color to the second color reaches a position outside the outer periphery of the wafer 2, so that the occurrence of poor segmentation can be prevented before it occurs.

[0035] As described above, according to an embodiment of the present invention, when a prescribed first temperature is reached by temperature change (external stimulus), the belt 6 of the workpiece unit 1 reversibly changes color to a first color, and when a prescribed second temperature lower than the first temperature is reached, the belt 6 of the workpiece unit 1 reversibly changes color to a second color, so it is possible to easily determine from the appearance whether processing accompanied by external stimulus has been performed on the workpiece unit 1.

[0036] In addition, the present invention is not limited to the above-mentioned embodiment. That is, various deformations can be made and implemented within the scope of the main purpose of the present invention. For example, in the present embodiment, the workpiece unit 1 is configured such that the chip 2 has TEG 8 as a ductile object on the predetermined dividing line 3, but it is not limited to this, and can also be configured to have DAF (Die Attach Film) pasted between the chip 2 and the belt 6 as a ductile object. The DAF is an adhesive sheet for chip bonding, which is formed larger than the chip 2. Therefore, for example, if the outer edge 65A of the area 65 that changes color to the second color reaches a position closer to the outside than the outer periphery of the DAF, the operator can judge that at least the DAF is cooled to below the second temperature. On the other hand, in the case where the area 66 that changes color to the first color exists on the inner side of the DAF, the operator can judge that the entire DAF has not been cooled to below the second temperature, so there is a possibility of a DAF fracture defect.

[0037] In addition, in the present embodiment, the belt 6 is configured to have a first temperature-indicating ink that changes color at a first temperature higher than a reference temperature at which the ductility of the TEG 8 as a ductile material decreases, and a second temperature-indicating ink that changes color at a second temperature lower than the first temperature and the reference temperature, but may be configured to have a single temperature-indicating ink that changes color at the second temperature. With this configuration, it is possible to determine whether the area to be cooled is cooled to or below the second temperature.

Claims

1. A processing unit, comprising: A workpiece having a predetermined dividing line formed on the front surface; A tape attached to a workpiece; and an annular frame to which the outer periphery of the belt is adhered, and the annular frame has an opening in the center, The workpiece is arranged in the opening of the annular frame by means of the belt. in, The tape is an expandable tape that divides the workpiece along the planned dividing line by expanding in a cooled state, and the tape reversibly changes color according to a temperature change.

2. The workpiece unit according to claim 1, wherein: The ribbon changes color to a first color at a first temperature, and changes color to a second color different from the first color at a second temperature different from the first temperature.

3. The workpiece unit according to claim 1 or 2, wherein: The divided workpiece has a modified layer formed inside along the planned dividing line.

Images