Method for forming a mask

Abstract

To provide a mask forming method which solves a problem that a work of arranging masks each having the size corresponding to each chip every chip is time-consuming and troublesome.SOLUTION: A mask forming method includes a plate preparation step of preparing a plate 20 having the size corresponding to a substrate 10, a resin solidification step of coating the upper surface of the plate 20 with liquid resin 19 to form a solidified resin layer 19' with a uniform thickness, a groove forming step of forming grooves 100 by positioning a cutting blade 81A on the surface of the resin layer 19' in accordance with dividing scheduled lines 14, a resin layer adhering step of making the upper surface of the substrate 10 and the surface of the resin layer 19' face each other, and adhering the surface of the resin layer 19' to the upper surface of the substrate 10 with the grooves 100 corresponding to the dividing scheduled lines 14, and a plate removal step of removing the plate 20 from the resin layer 19' to expose the grooves 100 formed in the resin layer 19'.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for forming a mask used when applying metal plating to a planned division line of a substrate that is divided into individual chips by the planned division line.

Background Art

[0002] A wafer on which a plurality of devices such as ICs and LSIs are partitioned by a planned division line and formed on the surface is subjected to cutting by a cutting device having a rotatably mounted cutting blade and divided into individual device chips, which are used in electric devices such as mobile phones and personal computers.

[0003] Also, when dividing a ceramic substrate formed on the surface with a plurality of regions partitioned by a planned division line into individual chips for each region, the above cutting device is used (for example, see Patent Document 1). Before the cutting process, AuSn (gold-tin) plating having a width exceeding the thickness of the cutting blade along the planned division line is applied in a lattice pattern.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, as described above, in order to apply AuSn plating having a width exceeding the thickness of the cutting blade in a lattice pattern along the planned division line, it is necessary to arrange a mask having a size corresponding to each individual chip for each individual chip, which is a problem that is extremely troublesome.

[0006] The present invention has been made in view of the above facts, and its main technical problem is to provide a method for forming a mask that solves the problem of the time-consuming and troublesome process of arranging a mask of a size corresponding to each individual chip for each individual chip. [Means for solving the problem]

[0007] To solve the above-mentioned main technical problems, the present invention provides a method for forming a mask used when applying metal plating to the division lines of a substrate that is divided into individual chips by the division lines, comprising: a plate preparation step of preparing a plate having a size corresponding to the substrate; a resin solidification step of coating the upper surface of the plate with liquid resin to form a resin layer solidified to a uniform thickness; a groove forming step of positioning a cutting blade on the surface of the resin layer corresponding to the division lines to form grooves; a resin layer bonding step of bringing the upper surface of the substrate and the surface of the resin layer facing each other and bonding the surface of the resin layer to the upper surface of the substrate with the grooves corresponding to the division lines; and a plate removal step of removing the plate from the resin layer to expose the grooves formed in the resin layer.

[0008] In the plate removal process, the plate can be removed by grinding or turning. Alternatively, in the plate removal process, the plate can be removed by peeling it off the resin layer. [Effects of the Invention]

[0009] The present invention provides a method for forming a mask used when applying metal plating to the division lines of a substrate that is divided into individual chips by the division lines. The method comprises: a plate preparation step of preparing a plate having a size corresponding to the substrate; a resin solidification step of coating the upper surface of the plate with liquid resin to form a resin layer of uniform thickness; a groove forming step of positioning a cutting blade on the surface of the resin layer corresponding to the division lines to form grooves; a resin layer bonding step of bringing the upper surface of the substrate and the surface of the resin layer facing each other, and bonding the surface of the resin layer to the upper surface of the substrate with the grooves corresponding to the division lines; and a plate removal step of removing the plate from the resin layer to expose the grooves formed in the resin layer. As a result, grooves are formed along the division lines of the substrate in the resin layer that functions as a mask covered on the substrate, and masks of a size corresponding to each region can be easily arranged. This eliminates the need to arrange a mask of a size corresponding to each chip that is divided into individual regions of the substrate, thus resolving the cumbersome problem of having to arrange a mask of a size corresponding to each chip that is divided into individual regions of the substrate. Furthermore, in conventional techniques, if grooves are formed in the mask sheet using a cutting blade after the mask sheet has been attached to the substrate, there is a risk of damaging the substrate with the cutting blade. However, according to the present invention, since grooves are formed in advance in the resin layer that functions as a mask, damage to the substrate is avoided. [Brief explanation of the drawing]

[0010] [Figure 1] This is an overall perspective view of a cutting apparatus suitable for this embodiment. [Figure 2] This is a perspective view of the substrate, which is the workpiece in this embodiment. [Figure 3] This is a perspective view of the plate prepared in the plate preparation process, and a perspective view showing how the plate is coated with liquid resin. [Figure 4] This is a perspective view showing the process of solidifying the resin coating on the plate. [Figure 5](a) A perspective view showing an embodiment of the groove formation process, (b) A partially enlarged cross-sectional view of the resin layer and plate in which the grooves have been formed, and (c) An overall perspective view of a plate having a resin layer on its surface in which the groove formation process has been carried out. [Figure 6] (a) A perspective view showing an embodiment of the resin layer bonding process, and (b) A perspective view showing the separation of the substrate and plate from the chuck table. [Figure 7] (a) A perspective view showing how the substrate and plate are placed on a holding table, (b) A perspective view showing an embodiment of the plate removal process, and (c) A perspective view showing another embodiment of the plate removal process. [Figure 8] (a) A magnified cross-sectional view of a portion of the substrate after the plate removal process, and (b) an overall perspective view of the substrate after the plate removal process. [Figure 9] This is a perspective view showing yet another embodiment of the plate removal process. [Figure 10] (a) A perspective view showing an embodiment of the division process for dividing a substrate into individual chips, and (b) A partially enlarged cross-sectional view when the division process is carried out. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments relating to a method for forming a mask based on the present invention will be described in detail with reference to the attached drawings.

[0012] Figure 1 shows a cutting apparatus 1 capable of cutting the illustrated substrate 10 and suitable for performing the mask formation method of this embodiment. The cutting apparatus 1 comprises a housing 2 with a substantially rectangular parallelepiped shape, a cassette 4 placed on a cassette table 4a of the housing 2, an loading / unloading means 3 for loading an unprocessed substrate 10 supported by a frame F from the cassette 4 to a temporary storage table 5 and loading a processed substrate 10 placed on the temporary storage table 5 into the cassette 4, a transport means 6 having a swivel arm for transporting the substrate 10 loaded onto the temporary storage table 5 to a chuck table 7, a cutting means 8 for performing cutting on the substrate 10 held on the chuck table 7, an imaging means 9 for imaging the substrate 10 held on the chuck table 7, a cleaning / unloading means 17 for transporting the processed substrate 10 from the loading / unloading position where the chuck table 7 is positioned in Figure 1 to a cleaning apparatus 16 (details omitted), and a control means (not shown). The cutting means 8 can be replaced with different cutting blades (for example, cutting blades 81A and 81B with different thicknesses and materials) in accordance with the material of the workpiece and the cutting conditions.

[0013] The substrate 10 cut by the cutting device 1 of this embodiment is a ceramic substrate, and as shown in Figure 2, it is a rectangular substrate formed on its surface 10a with a plurality of regions 12 partitioned by division lines 14. The division lines 14 are formed in a grid pattern by division lines 14 in a predetermined direction and division lines 14 in a direction perpendicular to the division lines 14 in the predetermined direction. When the substrate 10 is divided into individual chips for each region 12 using the cutting device 1, as shown in Figure 1, it is supported on an annular frame F via protective tape T and held on a chuck table 7. Note that the substrate 10 cut by the cutting means 8 is not limited to the above-described form, and may be in a form in which the regions 12 and division lines 14 are covered with mold resin and not exposed on the surface 10a.

[0014] The cutting device 1 includes an X-axis moving means for relatively moving the chuck table 7 and the cutting means 8 in the X-axis direction, and a Y-axis moving means for relatively moving the chuck table 7 and the cutting means 8 in the Y-axis direction orthogonal to the X-axis direction. The X-axis moving means in the present embodiment is a means for moving the chuck table 7 in the X-axis direction, and the Y-axis moving means is a means for moving the cutting means 8 in the Y-axis direction. The above-described X-axis moving means and Y-axis moving means are disposed inside the housing 2 and are not shown in the figure.

[0015] The chuck table 7 includes a suction chuck 71 that constitutes the holding surface of the chuck table 7, and a clamp 72 that is disposed so as to face the outer periphery of the chuck table 7 and grips a frame F that supports the substrate 10. The suction chuck 71 is composed of a breathable member, and a suction source not shown in the figure is connected thereto. By operating the suction source, a negative pressure is generated on the holding surface of the suction chuck 71, and the substrate 10 can be sucked and held.

[0016] The above control means is composed of a computer, and includes a central processing unit (CPU) that performs arithmetic processing according to a control program, a read-only memory (ROM) that stores the control program and the like, a readable and writable random access memory (RAM) for temporarily storing the detection values of various sensors, arithmetic results, etc., an input interface, and an output interface (all are not shown in detail). Each operating part of the cutting device 1 is connected to the control means and controlled, and the image captured by the imaging means 9 is stored in the control means and displayed on a display means not shown in the figure.

[0017] The cutting device 1 shown in FIG. 1 generally has the above-described configuration, and the method for forming a mask in the present embodiment will be described below.

[0018] When implementing the method for forming the mask of the present embodiment, first, as shown in FIG. 3, a plate preparation step of preparing a plate 20 having a size corresponding to the above-described substrate 10 is performed. The plate 20 is a plate-like object having rigidity such as a glass plate or PET (polyethylene terephthalate). If the plate 20 is prepared by the plate preparation step, the plate 20 is positioned directly below the liquid resin supply means 18 shown in FIG. 3, and a predetermined amount of a liquid resin 19 such as an epoxy resin is dropped from the supply nozzle 18a of the liquid resin supply means 18 onto the surface 20a, and the liquid resin 19 is spread on the surface 20a of the plate 20 to a uniform thickness. At this time, although not shown, it is preferable to rotate the table holding the plate 20. Next, as shown in FIG. 4, a resin curing step of irradiating ultraviolet rays (UV) using the ultraviolet irradiation means 36 to cure the liquid resin 19 is performed on the liquid resin 19 spread on the surface 20a of the plate 20, and a resin layer 19' of uniform thickness is formed on the surface 20a of the plate 20. Note that the above-described liquid resin 19 is not limited to an epoxy resin, and may be an acrylic resin, and is not limited to being cured by irradiating ultraviolet rays, and may be a resin that cures over time.

[0019] Once a plate 20 corresponding to the size of the substrate 10 and with a resin layer 19' formed on its surface 20a has been formed by the plate preparation and resin solidification processes described above, as shown in Figure 5(a), the plate 20 is placed on the chuck table 7 of the cutting device 1 with the resin layer 19' facing upwards, and the suction source is activated to hold the plate 20 in place. Next, the X-axis moving means of the cutting device 1 is activated to position the chuck table 7 directly below the imaging means 9, and the information of the outer shape of the plate 20 is detected and stored in the control means. Note that the depth of the groove 100, which will be described later, is set to a depth that reaches the surface 20a of the plate 20, so information regarding the thickness of the plate 20 is input and stored in the control means in advance. Here, the control means has in advance the position information of the division line 14 formed on the surface 10a of the substrate 10, which is the workpiece, in XY coordinates, and the position on the plate 20 corresponding to the division line 14 is set as the groove formation line for forming the groove 100, which will be described later. The groove formation lines are set in a grid pattern, similar to the division lines 14, by groove formation lines set in a predetermined direction and groove formation lines (neither of which are shown) in a direction perpendicular to the predetermined direction.

[0020] Once the plate 20 is held by suction on the chuck table 7 and the external shape of the plate 20 is stored in the control means, as shown in Figure 5(a), the predetermined direction of the groove formation line described above is aligned with the X-axis direction, and the groove formation line to be processed is positioned directly below the cutting means 8. The cutting means 8 comprises a spindle housing 80 extending in the Y-axis direction, a rotating spindle 82 rotatably supported in the spindle housing 80, a cutting blade 81A fixed to the tip of the rotating spindle 82, a blade cover 83 covering the rotating spindle 82 and the cutting blade 81A, and a cutting fluid supply nozzle 84 that supplies cutting fluid to the area to be cut by the cutting blade 81A. The cutting blade 81A is rotated in the direction indicated by arrow R1 by a spindle motor (not shown). The cutting blade 81A is a cutting blade mounted to cut the resin layer 19' to form a groove 100, and for example, the thickness of the cutting edge at the tip is 100 μm, corresponding to the width of the division line 14.

[0021] A cutting blade 81A, rotated at high speed, is positioned on the groove formation line aligned in the X-axis direction. The cutting feed amount is adjusted in the Z-axis direction indicated by arrow Z by a cutting feed mechanism (not shown in the figure) to cut from the side of the plate 20 covered with the resin layer 19', and the chuck table 7 is machine-feeded in the X-axis direction to perform groove formation work to form the groove 100. At this time, the groove 100 is formed with a width of 100 μm and a depth that does not reach the back surface 20b side of the plate 20, as can be understood from the partially enlarged cross-sectional view shown in Figure 5(b). Furthermore, the cutting blade 81A of the cutting mechanism 8 is index-feeded on a groove formation line adjacent in the Y-axis direction to the groove formation line in which the above groove 100 has been formed, and a groove 100 is formed in the same manner as above. By repeating these steps, grooves 100 are formed along all groove formation lines along the X-axis direction. Next, the chuck table 7 is rotated 90 degrees to align the direction perpendicular to the direction in which the groove 100 was previously formed with the X-axis direction, and the groove forming process described above is performed on all groove formation lines newly aligned with the X-axis direction, thereby forming grooves 100 along all groove formation lines on the plate 20 (see Figure 5(c)). As described above, the groove forming process of this embodiment is completed by forming grooves 100 along all groove formation lines on the plate 20.

[0022] Once the groove formation process described above is complete, the substrate 10, as explained with reference to Figure 2, is positioned above the plate 20, and the surface 10a on which the planned division line 14 of the substrate 10 is formed is turned downwards, as shown in the upper part of Figure 6(a). The surface 10a of the substrate 10 and the resin layer 19' of the plate 20 on which the groove 100 has been formed by the groove formation process are brought into contact, and the resin layer bonding process is performed to bond the resin layer 19' of the plate 20 to the substrate 10, with the groove 100 corresponding to the planned division line 14 of the substrate 10. When performing this resin bonding process, for example, the plate 20 can be heated to soften the resin layer 19' and exert adhesive force, and then bonded by heat and pressure. However, the present invention is not limited thereto, and it is also possible to form an adhesive layer on the upper surface of the resin layer 19' and bond it.

[0023] Once the resin layer bonding process is completed as described above, the suction source connected to the chuck table 7 is stopped to release the negative pressure generated on the chuck table 7, and the substrate 10 with the plate 20 attached via the resin layer 19' is removed from the chuck table 7 as shown in Figure 6(b). The substrate 10 removed from the chuck table 7 is transported and placed on the holding table 30 shown in Figure 7(a) in order to carry out the plate removal process described later. A holding surface 32 is formed on the upper surface of the holding table 30, which is configured to correspond to the shape of the substrate 10 in order to hold the substrate 10. The holding surface 32 is made of a breathable material and is connected to a suction source (not shown). By operating the suction source, negative pressure is generated on the holding surface 32, and the substrate 10 is held in place by suction.

[0024] The plate removal process involves removing the plate 20 from the resin layer 19' formed on the surface 10a of the substrate 10, thereby exposing the grooves 100 formed in the resin layer 19' by the groove forming process described above. This process can be carried out, for example, by the grinding apparatus 40 shown in Figure 7(b).

[0025] The grinding device 40 includes a grinding means 42 for grinding and removing a plate 20 attached to the surface 10a of a substrate 10 that is held by suction on the holding surface 32 of a holding table 30. The grinding means 42 includes a rotating spindle 43 that is rotated by a rotational drive mechanism (not shown), a wheel mount 44 attached to the lower end of the rotating spindle 43, and a grinding wheel 45 attached to the lower surface of the wheel mount 44, with a plurality of grinding wheels 46 arranged in an annular pattern on the lower surface of the grinding wheel 45.

[0026] Once the substrate 10 is held in place by suction on the holding table 30, the rotating spindle 43 of the grinding means 42 is rotated at, for example, 3000 rpm in the direction indicated by arrow R2 in Figure 7(b), and the holding table 30 is rotated at, for example, 300 rpm in the direction indicated by arrow R3. Then, the grinding wheel 46 is brought into contact with the back surface 20b of the plate 20, and the grinding wheel 45 is fed downwards at, for example, a grinding feed rate of 1 μm / second, as indicated by arrow R4. By grinding and removing the thickness of the plate 20, the groove 100 formed in the resin layer 19' is exposed, as shown in Figures 8(a) and (b). The groove 100 is formed corresponding to the planned division line 14 of the substrate 10, as described above, and when the groove 100 is exposed on the upper surface, the planned division line 14 of the substrate 10 is also exposed.

[0027] The plate removal process of the present invention is not limited to being carried out by the grinding apparatus 40 described above, but may also be carried out by turning (cutting with a cutting tool) using the turning apparatus 50 shown in Figure 7(c). The turning apparatus 50 is equipped with a turning means 51 for turning and removing a plate 20 that is attached to the back surface 10b of a substrate 10 held by suction on the holding surface 32 of a holding table 30 via a resin layer 19'. The turning means 51 is equipped with a cutting tool wheel 53 disposed at the lower end of a rotating shaft 52 rotatably supported in a unit housing (not shown), an electric motor (not shown) disposed on the upper end side of the rotating shaft 52 to rotate the cutting tool wheel 53, and a lifting means for raising and lowering the unit housing in the vertical direction. A cutting tool 54 equipped with a cutting edge 55 made of single-crystal diamond or the like at its lower end is mounted and fixed on the lower side of the cutting tool wheel 53. The turning means 51, having this configuration, moves closer to and away from the plate 20 attached to the substrate 10, which is held by attraction to the holding table 30, by the lifting means described above. This allows the cutting edge 55 of the cutting tool 54 to be positioned at any desired height.

[0028] When turning the plate 20 with the turning device 50 described above, the electric motor described above is activated to rotate the rotation axis 52 of the turning means 51 at a predetermined rotational speed (for example, 6000 rpm) in the direction indicated by arrow R5, as shown in Figure 7(c). At the same time, the lifting means described above is activated to lower the turning means 51 in the direction indicated by arrow R6 to position it at a desired height, and the holding table 30 is moved in the direction of arrow R7 without rotating. This desired height is the height at which the plate 20 is removed by turning with the cutting tool 54, as shown in Figures 8(a) and (b), and the groove 100 is exposed on the upper surface. When turning with the cutting tool 54 by activating the lifting means described above, it is preferable to gradually lower the turning means 51 to the desired height while performing the turning. Even with such a turning device 50, it is possible to perform a plate removal process in which the plate 20 is removed and the groove 100 is exposed.

[0029] Furthermore, the plate removal process of the present invention is not limited to being carried out by the grinding or turning processes described above. If the plate 20 is made of a flexible material such as PET, it may be removed by peeling, as shown in Figure 9.

[0030] A mask is formed on the substrate 10 by the mask formation method, which includes the plate preparation step, resin solidification step, groove formation step, resin layer bonding step, and plate removal step described above, covering the region 12 excluding the division line 14 formed on the substrate 10 with a resin layer 19'. The substrate 10 on which the mask has been formed is transported to a suitable plating apparatus and plated with a metal such as AuSn (gold-tin) on the surface 10a of the substrate 10, so that a plating layer 60 of an appropriate thickness is formed on the surface 10a, as shown in Figures 10(a) and (b). In this embodiment, as described above, grooves 100 corresponding to the division line 14 are formed in the resin layer 19', and a resin layer 19' that functions as a mask remains on the region 12. Therefore, the plating layer 60 is formed on the resin layer 19' in the region 12 and on the substrate 10 at the division line 14.

[0031] Once the substrate 10 has been plated as described above, as shown in Figure 10(a), the substrate 10 is supported by an annular frame F via protective tape T, and is held by suction on the chuck table 7 of the cutting device 1 described in Figure 1, with the frame F fixed by a clamp 72 (for explanatory purposes, the clamp 72 etc. are omitted in Figure 10). Next, the substrate 10 is imaged by the imaging means 9 described above to detect the position of the groove 100, i.e., the division line 14, which is the processing position, and the substrate 10 is positioned directly below the cutting means 8. At this time, the cutting means 8 is equipped with a cutting blade 81B, which has a thinner cutting edge than the cutting blade 81A and is suitable for cutting the substrate 10 and dividing it into individual chips. The cutting blade 81B has a thinner thickness (for example, 30 μm) than the cutting blade 81A, and is a thin blade compared to the width dimension of the plating layer 60 formed in the groove 100 μm in width. Then, the cutting blade 81B is rotated at high speed in the direction indicated by R1, and the X-axis feed means, Y-axis feed means, and cutting feed means are activated to perform a division process in which the substrate 10 is divided into individual chips for each region 12 by cutting from above into the center of the width direction of the division line 14, as shown in Figure 10(b). In this division process, as described above, the cutting process is performed along the division line 14 using a 30 μm cutting blade 81B, which has a thinner cutting edge at the tip than the cutting blade 81A, so that the outer circumference of each divided chip is surrounded by a 35 μm wide plating layer 60.

[0032] In the above-described embodiment, after performing the mask formation method, plating is performed without removing the resin layer 19' on region 12, and then the chips are separated into individual chips by the cutting means 8. This prevents cutting debris generated by the cutting process in the separation step from adhering to and contaminating each chip. However, the present invention is not limited thereto, and the resin layer 19' on which the plating layer 60 is formed may be removed from the chips before cutting the substrate 10 to separate it into individual chips.

[0033] As described in the above embodiment, by performing a mask formation method including a plate preparation step, a groove formation step, a resin layer bonding step, and a plate removal step, grooves 100 corresponding to the planned division lines 14 of the substrate 10 are formed in the resin layer 19' that functions as a mask covered on the substrate 10, and masks of a size corresponding to each individual region 12 can be easily arranged. This eliminates the need to arrange a mask of a size corresponding to each chip that is divided into regions 12 of the substrate 10 for each individual chip, thus resolving the cumbersome problem.

[0034] Furthermore, in conventional techniques, if a mask sheet is attached to a substrate and then grooves are formed in the mask sheet using a cutting blade to form a mask, there is a risk of damaging the substrate with the cutting blade. However, according to the present invention, grooves are formed in advance before the resin layer 19' that functions as a mask is attached to the substrate, thus avoiding damage to the substrate. [Explanation of Symbols]

[0035] 1:Cutting device 2: Housing 3: Carrying in / out means 4: Cassette 4a: Cassette Table 5: Temporary placement table 6: Conveying means 7: Chuck Table 71: Suction Chuck 72: Clamp 8:Cutting means 80: Spindle Housing 81A: Cutting blade 81B: Cutting blade 82: Rotating spindle 83: Blade Cover 84: Cutting fluid supply nozzle 9: Imaging means 10: Circuit board 12: Area 14: Planned division line 16: Washing device 17: Washing and unloading means 18: Liquid resin supply means 19: Liquid resin 19': Resin layer 20: Plate 20a: Surface 20b: Back side 30: Holding Table 32: Holding surface 34: Liquid resin 34': Resin layer 36: Ultraviolet irradiation means 40: Grinding equipment 42: Grinding means 43: Rotating spindle 44: Wheel Mount 45: Grinding Wheel 46: Grinding Wheel 50: Turning machine 51: Turning means 52: Rotation axis 53: Bite Wheel 54: Byte 55: Cutting edge 60: Plating layer 100: Groove

Claims

1. A method for forming a mask used when applying metal plating to the division lines of a substrate that is divided into individual chips by the division lines, A plate preparation step involves preparing a plate having a size corresponding to the substrate, A resin solidification process involves coating the upper surface of the plate with liquid resin to form a resin layer of uniform thickness, A groove forming step involves positioning a cutting blade on the surface of the resin layer in accordance with the planned division line to form a groove, A resin layer bonding step in which the upper surface of the substrate and the surface of the resin layer are brought into contact, and the groove is aligned with the planned division line, and the surface of the resin layer is bonded to the upper surface of the substrate, A method for forming a mask comprising a plate removal step of removing the plate from the resin layer to expose grooves formed in the resin layer.

2. In the plate removal process, A method for forming a mask according to claim 1, wherein the plate is removed by grinding or turning.

3. In the plate removal process, A method for forming a mask according to claim 1, wherein the plate is peeled off and removed from the resin layer.

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