Chip inspection method

Abstract

To provide an inspection method of a chip capable of solving the problem that when the chip is broken by applying a load to the center of the chip in inspecting flexural strength, fine fragments are widely scattered when the chip is broken, and it is difficult to remove the fragments from a measuring device of the flexural strength.SOLUTION: According to another aspect of the present invention, there is provided a chip testing method for testing a die strength of a chip having a first surface and a second surface opposite to the first surface, the chip testing method including a preparing step of preparing a die strength testing apparatus including a support terminal for supporting the chip and a load terminal having an indenter for applying a load to divide the chip, a resin laying step of laying a resin on the first surface of the chip on which the load terminal acts, and a placing step of placing the second surface of the chip on the support terminal in the condition where the first surface of the chip is opposed to the load terminal. The breaking strength inspection method includes at least a breaking strength inspection step of bringing the load terminal into contact with the one surface to inspect the breaking strength of the chip, and a removal step of removing the broken chip from the breaking strength inspection apparatus, and scattering of broken pieces of the broken chip is suppressed by the laid resin.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a chip inspection method for inspecting the flexural strength of a chip having one surface and another surface on the opposite side. [Background technology]

[0002] Wafers, on the surface of which multiple devices such as ICs and LSIs are formed along planned dividing lines, are separated into individual device chips using cutting equipment and laser processing equipment, and are used in electrical devices such as mobile phones and personal computers.

[0003] Furthermore, the flexural strength of the device chips is measured by sampling inspection for each wafer, and only device chips from wafers that have device chips exceeding a predetermined flexural strength are used in electrical equipment, etc. (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-196183 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when testing the flexural strength, if a load is applied to the center of the chip and the chip breaks, the broken chip will scatter into small pieces over a wide area, which makes it difficult to remove them from the flexural strength measuring device, which is an unbearable hassle.

[0006] The present invention has been made in consideration of the above facts, and its main technical objective is to provide a chip inspection method that can solve the problem that when a load is applied to the center of a chip during inspection of its flexural strength, causing the chip to break, fine fragments are scattered widely and are difficult to remove from the flexural strength measuring device. [Means for solving the problem]

[0007] In order to solve the above-mentioned main technical problem, according to the present invention, there is provided a chip inspection method for inspecting the flexural strength of a chip having one side and an opposite side, which includes at least the following steps: a preparation step of preparing a flexural strength inspection device having a support terminal that supports the chip and a load terminal having an indenter that applies a load to divide the chip; a resin laying step of laying resin on one side of the chip on which the load terminal acts; a placement step of facing the one side to the load terminal and placing the other side on the support terminal; a flexural strength inspection step of contacting the load terminal with the one side to inspect the flexural strength of the chip; and a removal step of removing a broken chip from the flexural strength inspection device, wherein the laid resin prevents fragments of the broken chip from scattering.

[0008] The method may also include a dividing step of dividing a wafer having a surface partitioned by dividing lines into individual chips, and a grinding step of grinding the back surface of the wafer divided into chips. [Effects of the Invention]

[0009] The chip inspection method of the present invention is a chip inspection method for inspecting the flexural strength of a chip having one side and an opposite side, and includes at least the following steps: a preparation step for preparing a flexural strength inspection device having a support terminal that supports the chip and a load terminal having an indenter that applies a load to divide the chip; a resin laying step for laying resin on one side of the chip on which the load terminal acts; a placement step for facing the one side to the load terminal and placing the other side on the support terminal; a flexural strength inspection step for inspecting the flexural strength of the chip by contacting the load terminal with the one side; and a removal step for removing broken chips from the flexural strength inspection device.Since the laid resin prevents fragments of the broken chip from scattering, even if a load is applied to the center of a chip that has been divided into individual chips by the load terminal, causing the chip to break, the action of the resin laid in the resin laying step prevents the chips from breaking into small fragments and scattering over a wide area. Therefore, the problem that it is difficult and troublesome to remove chip fragments from the bending strength testing device is solved. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 10 is an overall perspective view of a bending strength testing device prepared in a preparation step. [Figure 2] FIG. 2 is a perspective view of a wafer before being divided into chips. [Figure 3] 1 is a perspective view showing an embodiment of a grinding process. [Figure 4] FIG. 10 is a perspective view showing an embodiment of a dividing step. [Figure 5] (a) is a perspective view showing how the resin laying process is carried out on the surface of the device, (b) is a perspective view showing how the resin laying process is carried out on the back surface of the device, and (c) is a side view of the device on which resin has been laid by the resin laying process shown in (a). [Figure 6] FIG. 1A is a perspective view showing an embodiment of a bending strength inspection step, and FIG. 1B is a perspective view showing the state of a device chip broken by the bending strength inspection step. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a chip inspection method configured based on the present invention will be described in detail with reference to the accompanying drawings.

[0012] (preparation process) When carrying out the chip inspection method of this embodiment, a preparation step is carried out to prepare a flexural strength inspection device equipped with support terminals that support the chip and a load terminal having an indenter that applies a load to divide the chip. A specific form of the flexural strength inspection device prepared by this preparation step of this embodiment will be described with reference to Figure 1.

[0013] 1 shows a flexural strength testing device 1 prepared in a preparation step in the chip testing method of this embodiment. The illustrated flexural strength testing device 1 is a testing device for measuring the three-point bending strength of a chip, which is an object to be tested, as will be described later, and includes a support block 9 on which the surface opposite to the side where stress is applied to test the flexural strength of the chip faces downward, as indicated by the arrow X in the figure, and which has two support terminals 9a, 9a spaced apart in the X direction indicated by the arrow X in the figure and arranged along the Y direction perpendicular to the X direction, and a load applying device positioned at the center of the support block 9, more specifically, between the two support terminals 9a, 9a, which moves from above to below on the chip supported by the support block 9 and applies a load in the Y direction. the load measured by the load measuring instrument 4 and the Z position of the indenter 7a measured by the position measuring instrument 5 are transmitted to and stored in control means 20 constituted by a computer. The indenter 7a has a tip that forms an acute angle when viewed in cross section, and the load terminal 7 including the indenter 7a and the support block 9 are both made of a material having high hardness (such as cemented carbide or stainless steel).

[0014] The bending strength testing device 1 is supported so as to be movable up and down relative to a support wall 2 disposed vertically on an apparatus frame (not shown). A pair of guide rails 2a, 2a extending in the Z direction (up and down direction) are provided on the inner surface of the support wall 2. A movable base 3 including a load measuring device 4 and a position measuring device 5 is attached to the guide rails 2a, 2a.

[0015] The movable base 3 is provided with guided grooves that slidably engage with the guide rails 2a, 2a arranged on the support wall 2, and is equipped with a moving means 8 that moves the movable base 3 in the up and down direction. The moving means 8 is equipped with a male threaded rod 8b that is arranged in the Z direction parallel to the guide rails 2a, 2a and rotatably supported on the support wall 2, a pulse motor 8a for rotating the male threaded rod 8b, and a female threaded block (not shown) that is attached to the movable base 3 and threadedly engages with the male threaded rod 8b. The male threaded rod 8b is driven in the forward and reverse directions by the pulse motor 8a to move the movable base 3 in the Z direction, and the indenter 7a is brought into contact with and separated from the tip supported by the support block 9.

[0016] A fixed block 6, to which a load terminal 7 is attached, is disposed at the lower end of the load measuring instrument 4, which is disposed below the movable base 3. The fixed block 6 includes a support portion 6a into which the plate-shaped load terminal 7 equipped with an indenter 7a extending in the Y direction is inserted, a rotation shaft 6b extending in the X direction and inserted into a through-hole (not shown) of the load terminal 7 to rotatably attach the load terminal 7 within the support portion 6a, and set bolts 6c, 6c disposed on both sides of the rotation shaft 6b and screwed into the fixed block 6 to fix the load terminal 7. The load terminal 7 is fixed by rotating the set bolts 6c forward so that their tips abut against the side of the load terminal 7 within the support portion 6a. The load terminal 7 can be fixed by rotating the set bolts 6c forward to loosen the set bolts 6c backward to release the fixation of the load terminal 7, thereby rotating the load terminal 7 around the rotation shaft 6a and fine-tuning the angle of the tip of the indenter 7a so that it is horizontal.

[0017] The position measuring device 5 includes a linear scale 5a arranged along the Z-axis direction on the support wall 2, and a read head 5b arranged on the movable base 3 side for reading the scale of the linear scale 5a. The position measuring device 5 can measure the position (Z position) of the indenter 7a when the movable base 3 is moved in the Z-axis direction by operating the moving means 8 described above, and transmits this to the control means 1A.

[0018] The above-described flexural strength testing device 1 is merely one example of a flexural strength testing device that can be used in the present invention. For example, the flexural strength testing device of the present invention is not limited to being configured with the linear scale 5a disposed on the support wall 2 and the read head 5b disposed on the movable base 3, as in the above-described position measuring device 5. The position of the indenter 7a can be measured by counting the number of drive pulses of the pulse motor 8a constituting the above-described moving means 8 using the control means when moving the movable base 3. Alternatively, a light irradiating means for irradiating light in the Z direction can be disposed on the movable base 3, which moves in the Z direction, and the light can be reflected in the Z direction on the support wall 2 or on the device frame (not shown) to generate reflected light. A light receiving unit for receiving the reflected light can be disposed to measure the optical path length, thereby measuring the moving position of the indenter 7a disposed on the movable base 3. This can serve as the position measuring device in the flexural strength testing device 1 of this embodiment.

[0019] As described above, according to the preparation process of this embodiment, a flexural strength testing device 1 is prepared, which includes a pair of support terminals 9a, 9a and an indenter 7a positioned in the center of the pair of support terminals 9a, 9a and pressing the center of the chip supported by the pair of support terminals 9a, 9a.

[0020] In the chip inspection method of this embodiment, as described below, a resin laying process is carried out in which resin is laid on one side of the chip on which the above-mentioned load terminal 7 acts, but in order to obtain the chip to be inspected, a grinding process and a dividing process described below are carried out as necessary.

[0021] (Grinding process) The grinding step of this embodiment is performed to grind the back surface 10b of the wafer 10 shown in Fig. 2 to a desired thickness (e.g., 100 to 500 µm). The illustrated wafer 10 is a silicon wafer having a plurality of devices 12 formed on the front surface 10a and partitioned by planned division lines 14. In this embodiment, in order to grind the back surface 10b side of the wafer 10, a protective tape T1 is attached to the front surface 10a.

[0022] Once the wafer 10 with the protective tape T1 attached thereto is prepared as described above, it is transferred to a grinding apparatus 20 (only a portion of which is shown) shown in Fig. 3. The grinding apparatus 20 includes a rotatable chuck table 21 and grinding means 22 for grinding and thinning the back surface 10b of the wafer 10 held by suction on the chuck table 21. The grinding means 22 includes a rotating spindle 23 rotated by a rotation drive mechanism (not shown), a wheel mount 24 attached to the lower end of the rotating spindle 23, and a grinding wheel 25 attached to the lower surface of the wheel mount 24, and a plurality of grinding stones 26 are arranged in an annular shape on the lower surface of the grinding wheel 25.

[0023] As shown in FIG. 3, if the surface 10a side of the wafer 10 with the protective tape T1 attached is placed downward on the chuck table 21 and sucked and held, the rotary spindle 23 of the grinding means 22 is rotated in the direction indicated by the arrow R1 in FIG. 3, for example, at 6000 rpm, while the chuck table 21 is rotated in the direction indicated by the arrow R2, for example, at 300 rpm. Then, while supplying grinding water onto the back surface 10b of the wafer 10 by a grinding water supply means not shown, the grinding means 22 is lowered in the direction indicated by the arrow R3, the grinding wheel 26 is brought into contact with the back surface 10b of the wafer 10, and the grinding wheel 25 is fed downward at a grinding feed rate of, for example, 1 μm / sec. At this time, grinding can be advanced while measuring the thickness of the wafer 10 by a contact type or non-contact type measuring gauge not shown. When the back surface 10b of the wafer 10 is ground and the wafer 10 is made to have a desired thickness (100 to 500 μm), the grinding means 22 is stopped and transported to a cleaning means not shown, and after going through a cleaning and drying process etc. of the wafer 10, the grinding process for grinding the back surface 10b of the wafer 10 is completed.

[0024] (Dicing process) The wafer 10 having the desired thickness as described above is diced into individual device chips by the dicing process described below. When carrying out the dicing process, the above-mentioned protective tape T1 attached to the surface 10a of the wafer 10 is peeled off, and the wafer 10 with the surface 10a side facing upward is positioned in the opening Fa of the annular frame F having an opening Fa capable of accommodating the wafer 10 shown in FIG. , and the adhesive tape T2 is attached to the back surface 10b side of the wafer 10 and the back surface of the frame F to be integrated. The wafer 10 integrated with the frame F in this way is transported to a cutting device 30 (only a part is shown) shown in FIG. 4.

[0025] The cutting device 30 includes a chuck table (not shown) that holds the wafer 10 by suction, and cutting means 31 that cuts the wafer 10 held by suction on the chuck table. The chuck table is rotatable and includes a moving means (not shown) that feeds the chuck table in the direction indicated by the arrow X in the figure. The cutting means 31 includes a spindle housing 32 disposed in the Y-axis direction indicated by the arrow Y in the figure, a spindle 33 rotatably held in the spindle housing 32, an annular cutting blade 34 held at the tip of the spindle 33, a blade cover 35 that covers the cutting blade 34, and a cutting water supply nozzle 36 disposed in the blade cover 35 that supplies cutting water to the cutting area of ​​the cutting blade 34. The cutting means 31 also includes a Y-axis moving means (not shown) that indexes and feeds the cutting blade 34 in the Y-axis direction. The spindle 33 is driven to rotate by a spindle motor (not shown).

[0026] To perform the dividing process, the wafer 10 is placed on the chuck table of the cutting device 50 with the front surface 10a facing upward and held by suction. The predetermined dividing lines 14 of the wafer 10 are aligned in the X-axis direction and aligned with the cutting blade 34. Next, the cutting blade 34, rotating at high speed, is positioned on the dividing lines 14 aligned in the X-axis direction and cuts into the wafer from the front surface 10a while supplying cutting water from the cutting water supply nozzle 36. The chuck table is moved in the X-axis direction to form a cut groove 100. The cutting blade 34 of the cutting means 31 is then indexed and moved to a dividing line 14 adjacent in the Y-axis direction to the dividing line 14 where the cut groove 100 has been formed but where no cut groove 100 has been formed. By repeating these steps, cut grooves 100 are formed along all dividing lines 14 along the X-axis direction. Next, the chuck table is rotated 90 degrees, the direction perpendicular to the direction in which the cut grooves 100 were previously formed is aligned with the X-axis direction, and the above-mentioned cutting process is performed on all of the dividing lines 14 that have now been aligned with the X-axis direction, thereby forming cut grooves 100 along all of the dividing lines 14 formed on the wafer 10. By performing the dividing process in this manner, the wafer 10 is divided along the dividing lines 14 into individual device chips.

[0027] Note that the splitting process of the present invention is not limited to being carried out using the above-described cutting device 30. For example, the wafer 10 before splitting is transported to a laser processing device (not shown), and a laser beam having an absorbable wavelength is irradiated onto the wafer 10 along the planned splitting line 14 on the surface 10a side of the wafer 10 to form laser processing grooves serving as splitting bases along all the planned splitting lines 14. Then, an external force may be applied to the wafer 10 to split it into device chips along the laser processing grooves. Further, instead of irradiating the wafer 10 with a laser beam having an absorbable wavelength as described above, a laser beam irradiation means for irradiating the wafer 10 with a laser beam having a transmissive wavelength is prepared, and the condensing point of the laser beam is positioned inside the planned splitting line 14 of the wafer 10 and irradiated to form a modified layer serving as a splitting base inside the wafer 10 along all the planned splitting lines 14, and it is also possible to apply an external force to the wafer 10 to split it into individual device chips.

[0028] (Resin laying process) FIG. 5(a) shows a device chip 12' split from the wafer 10 with the surface 12a side facing upward, and FIG. 5(b) shows the device chip 12' with the back surface 12b facing upward.

[0029] When the flexural strength of the individually separated device chips 12′ is inspected using the flexural strength inspection apparatus 1, a resin is applied to one surface of the device chip 12′ on the side where stress is applied by the load terminal 7. The method for applying the resin to one surface of the device chip 12′ is not particularly limited. For example, when inspecting the flexural strength when stress is applied from the surface 12a of the device chip 12′, as shown in FIG. 5( a), a resin supply nozzle 42 of a liquid resin supply means 40 is positioned above the surface 12a of the device chip 12′. Next, a predetermined amount of liquid resin 44 is dropped onto the surface 12a. An example of a suitable liquid resin for this embodiment is polyvinyl alcohol (PVA). The resin applied in the resin application step of the present invention is not limited to PVA and may be, for example, polyethylene (PE), polypropylene (PP), polystyrene (PS), or the like.

[0030] As described above, after the liquid resin 44 is dropped, the resin 44 solidifies over a predetermined time period, forming a film of the resin 44 on the surface 12a of the device chip 12', as shown in Fig. 5(c). The film of the resin 44 is formed to a thickness of, for example, 1 to 10 µm. The thickness of the resin film 44 is preferably as thin as possible, and is preferably formed to a thickness of about 1 µm.

[0031] Furthermore, when testing the flexural strength by applying stress from the back surface 12b of the device chip 12', as shown in FIG. 5(b), the resin supply nozzle 42 of the liquid resin supply means 40 is positioned above the back surface 12b of the device chip 12'. Next, a predetermined amount of resin 44 is dropped onto the back surface 12b. In this case, too, a film of resin 44 is formed on the back surface 12b of the device chip 12', similar to the device chip 12' shown in FIG. 5(c). In the following explanation, it is assumed that a film of resin 44 is formed on the front surface 12a of the device chip 12'.

[0032] In the resin application step, when applying the resin 44 to one surface of the device chip 12′, the method is not necessarily limited to applying the resin 44 by dripping the liquid resin 44 as described above. For example, a resin sheet may be formed in advance and attached to the front surface 12a or the back surface 12b of the device chip 12′.

[0033] (Placement process) After the resin laying process has been carried out as described above, one side on which the resin 44 is laid, i.e., the front surface 12a side, on which the stress is applied, is placed facing the load terminal 7 of the above-mentioned bending strength testing device 1, and the other side opposite the front surface 12a, i.e., the back surface 12b side, is placed on the support terminals 9a, 9a of the support block 9, as shown in Figure 6(a).

[0034] (Deflective strength inspection process) After the above-mentioned mounting process has been carried out, the moving means 8 of the flexural strength testing device 1 described based on Figure 1 is operated to lower the fixed block 6 at a slow, constant speed in the direction indicated by arrow R5, as shown in Figure 6(a), and the indenter 7a of the load terminal 7 is positioned and pressed against the surface 12a of the device chip 12' on which the film of resin 44 has been formed, and the Z position of the indenter 7a is measured by the position measuring device 5, and the load is measured by the load measuring device 4.

[0035] 6(a), the indenter 7a comes into contact with the device chip 12' via the resin 44 on the surface 12a side of the device chip 12', and from that position, the load begins to be measured by the load measuring instrument 4. After the indenter 7a comes into contact with the device chip 12', the indenter 7a is lowered in the direction indicated by arrow R5 to press against the device chip 12', whereby the device chip 12' begins to deform, the load of the device chip 12' is applied to the indenter 7a, and the load measured by the load measuring instrument 4 increases in approximate proportion to the amount of descent of the indenter 7a in the Z position.

[0036] In the state shown in FIG. 6(a), if the indenter 7a is further lowered in the direction indicated by arrow R5 to press and deform the device chip 12', the strength limit of the device chip 12' will be reached, and the device chip 12' will break, as shown in FIG. 6(b). The load measured at the Z position of the indenter 7a when the device chip 12' breaks is the maximum load measured in this test and is stored in the control means 1A as an indication of the flexural strength of the device chip 12'. Based on this result, it is determined whether the device chip 12' whose flexural strength has been tested satisfies the predetermined strength. In this way, the measurement of flexural strength in the flexural strength testing process is completed. Note that when the flexural strength testing process is performed by applying the load terminal 7 to the back surface 12b of the device chip 12', the resin 44 is laid on the back surface 12b in the resin laying process, and the opposite front surface 12a is placed on the support terminals 9a, 9a, and the flexural strength is tested using the same procedure as above.

[0037] 6(b) is completed, the broken device chip 12' is removed from the support block 9 of the breakable strength testing apparatus 1. As shown in the figure, the device chip 12' broken in the breakable strength testing process of this embodiment is prevented from scattering into multiple fragments by the action of the resin 44, and the device chip 12' can be removed extremely easily.

[0038] According to the chip inspection method of the present embodiment described above, even if the device chip 12' is broken by the load applied by the load terminal 7, the resin 44 laid in the resin laying step prevents the chip from breaking into fragments and scattering over a wide area. Therefore, it becomes easy to remove the broken device chip 12' from the flexural strength inspection apparatus 1, and the conventional problem of the difficulty and hassle of removing chip fragments from the flexural strength inspection apparatus 1 is resolved.

[0039] In the above embodiment, the chip whose flexural strength is inspected by the flexural strength inspection device 1 is the device chip 12', but the chip whose flexural strength is inspected by the present invention is not limited to this. For example, the present invention can also be applied to a case where a glass plate is divided to form glass chips of a predetermined size and the flexural strength of the glass chips is inspected. [Explanation of symbols]

[0040] 1: Transverse strength testing device 1A: Control means 2:Supporting wall 3: Mobile base 4: Load measuring instrument 5: Position measuring instrument 5a: Linear scale 5b: Read head 6: Fixed block 6a: Support part 6b: Rotation axis 6c: Set bolt 7: Load terminal 7a:Indenter 8. Transportation 8a: Pulse motor 8b: Male threaded rod 9: Support block 9a: Support terminal 10: Wafer 10a: surface 10b: Back side 12: Device 12': Device chip 14: Planned division line 20: Grinding equipment 21: Chuck table 22: Grinding means 23: Rotating spindle 25: Grinding wheel 26: Grinding wheel 30: Cutting equipment 31:Cutting means 32: Spindle housing 33: Spindle 34: Cutting blade 35: Blade cover 36: Cutting water supply nozzle 100: Cutting groove

Claims

1. A chip inspection method for inspecting the flexural strength of a chip having one surface and an opposite surface, comprising: a preparation step of preparing a bending strength testing device including a support terminal for supporting the chip and a load terminal having an indenter for applying a load to divide the chip; a resin laying step of laying resin on one surface of the chip on which the load terminal acts; a placing step of placing the one surface of the support terminal on the other surface of the support terminal so that the one surface faces the load terminal; a flexural strength inspection step of inspecting the flexural strength of the chip by bringing the load terminal into contact with one surface side; a removing step of removing the broken chip from the bending strength testing device; At least A chip inspection method in which scattering of chip fragments is prevented by the application of resin.

2. A dividing step is included in which a wafer having a surface on which a plurality of devices are defined by dividing lines is divided into individual chips; 2. The inspection method according to claim 1, wherein chips are formed by the dividing step.

3. 3. The inspection method according to claim 2, further comprising a grinding step of grinding the back surface of the wafer to be divided into the chips.

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