Workpiece processing method and cutting apparatus

Abstract

To propose a novel technique for preventing particles from sticking to a surface of a workpiece.SOLUTION: A workpiece processing method uses a cutting device that comprises a holding table 20 for holding a workpiece, and a cutting unit 5 having a cutting liquid supply nozzle 51 for supplying cutting liquid to the workpiece. The workpiece processing method includes: a cutting step for cutting a workpiece (wafer W) held by the holding table 20 while the cutting liquid 55 is supplied, using a cutting blade 52; and a washing step for positioning the cutting unit 5 at a position above the workpiece held by the holding table 20, where the cutting blade 52 does not cut-in to the workpiece, after implementing the cutting step, and for supplying the cutting liquid 55 to the workpiece in order to wash the workpiece with the cutting liquid.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a processing method for processing a workpiece with a cutting device and a cutting device.

Background Art

[0002] Conventionally, for example, as disclosed in Patent Documents 1 and 2, it is known that in the manufacturing process of a semiconductor device, after cutting a semiconductor device wafer as a workpiece, cleaning is performed by a cleaning device.

[0003] If the wastewater containing cutting chips generated by cutting dries on the wafer before being transported to the cleaning device and cleaned, the particles contained in the wastewater adhere to the wafer and it becomes difficult to remove them even after subsequent cleaning.

[0004] And when particles adhere to the device, there is a risk of damaging the device. In addition, when particles adhere to the bonding pad, it may cause bonding failure.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] From the above, it is conceivable to supply cleaning water to the workpiece even during transportation and keep the wafer constantly wet.

[0007] However, in this case, waterproofing measures are also required along the workpiece transport path, and if wafers are transported non-contact using a Bernoulli transport pad, for example, it becomes difficult to continuously supply cleaning water during transport.

[0008] In view of the above problems, the present invention proposes a novel technique for preventing particles from adhering to the surface of a workpiece. [Means for solving the problem]

[0009] The problems that this invention aims to solve are as described above, and the means for solving these problems will now be explained.

[0010] According to one aspect of the present invention, a method for processing a workpiece using a cutting apparatus comprising a holding table for holding a workpiece and a cutting unit for cutting the workpiece with a cutting blade while supplying cutting fluid to the workpiece, the method comprising: a cutting step of cutting the workpiece held by the holding table with the cutting blade while supplying the cutting fluid; and a cleaning step of immediately after performing the cutting step, without releasing the workpiece from the holding table, positioning the cutting unit above the held workpiece and in a position where the cutting blade does not cut into the workpiece, and supplying cutting fluid to the workpiece to clean the workpiece with the cutting fluid.

[0011] Furthermore, according to one aspect of the present invention, in the cleaning step, the workpiece is cleaned with the cutting fluid while the holding table is moved relative to the cutting unit.

[0012] Furthermore, according to one aspect of the present invention, after performing the cleaning step, the present invention further comprises a cleaning step in which the workpiece is transported to a cleaning device and the workpiece is cleaned by the cleaning device.

[0013] Furthermore, according to one aspect of the present invention, a cutting device comprising a holding table for holding a workpiece and a cutting unit for cutting the workpiece with a cutting blade while supplying cutting fluid to the workpiece, wherein the cutting unit is positioned above the workpiece held by the holding table and in a position where the cutting blade does not cut into the workpiece, and the cutting fluid is supplied to the workpiece to clean the workpiece with the cutting fluid. [Effects of the Invention]

[0014] The present invention provides the following effects: In other words, according to one aspect of the present invention, by performing a cleaning step, the surface of the workpiece is cleaned with cutting fluid immediately after the cutting step is completed, thereby efficiently removing cutting chips without them remaining on the surface, and preventing the cutting chips from becoming particles and adhering to the surface.

[0015] Furthermore, according to one aspect of the present invention, since the surface of the workpiece is cleaned with a cutting fluid in the cleaning step, the probability of particles being present on the surface of the workpiece after this cleaning step can be further reduced. In other words, by performing a total of two cleanings, the cleaning step and this cleaning step, a higher cleaning effect can be obtained, and the occurrence of device damage due to the presence of particles and defects such as bonding failures can be more effectively prevented. [Brief explanation of the drawing]

[0016] [Figure 1] This is a perspective view of one embodiment of a cutting device used in carrying out the present invention. [Figure 2] A diagram showing an example of a wafer unit configuration. [Figure 3] A flowchart illustrating each step in the workpiece machining process. [Figure 4] A diagram illustrating the cutting steps. [Figure 5] A diagram illustrating the state of the cleaning step as viewed from the Y-axis direction. [Figure 6]A diagram for explaining the state of the cleaning step when viewed from the X-axis direction. [Figure 7] A diagram showing this cleaning step.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing a processing apparatus 2 according to an embodiment of the present invention.

[0018] As shown in FIG. 1, a holding table 20 is disposed on a base 4 of the processing apparatus 2. A water cover 14 is disposed around the holding table 20, and a bellows 16 for closing an opening of the base 4 is connected to the water cover 14. Below the water cover 14 and the bellows 16, a moving mechanism (not shown) for moving the holding table 20 in the X-axis direction and a rotating mechanism (not shown) for rotating the holding table 20 around the Z-axis are provided.

[0019] A cassette mounting table 8 for mounting a cassette 7 is provided at a front corner portion of the base 4. A wafer unit U in which a wafer W as a workpiece is fixed is accommodated in the cassette 7.

[0020] A gantry-shaped column 9 is erected on the base 4, and a pair of guide rails 31 extending in the Y-axis direction are fixed to the column 9. A Y-axis moving block 33 is provided on the guide rail 31 so as to be movable in the Y-axis direction, and the Y-axis moving block 33 is guided by the guide rail 31 and moves in the Y-axis direction by a Y-axis moving mechanism 30 including a ball screw 32 and a pulse motor 34.

[0021] A pair of guide rails 36 extending in the Z-axis direction are fixed to the Y-axis moving block 33. A Z-axis moving block 38 is provided on the guide rail 36 so as to be movable in the Z-axis direction, and the Z-axis moving block 38 is guided by the guide rail 36 and moves in the Z-axis direction by a Z-axis moving mechanism 40 including a ball screw 42 and a pulse motor 44.

[0022] The Z-axis movement block 38 is fitted with a cutting unit 5 and an imaging unit 6. The cutting unit 5 is configured by detachably attaching a cutting blade to the tip of a spindle that is rotationally driven by a motor (not shown).

[0023] A cleaning device 60 having a spinner table 62 is provided on the base 4, allowing the wafer W after cutting to be held by suction on the spinner table 62 for spinner cleaning and spin drying.

[0024] Figure 2 shows an example configuration of wafer unit U. The wafer W, which is the workpiece, is formed from materials such as Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductor materials. Alternatively, it is formed from complex oxides such as LT (lithium tantalate) or LN (lithium niobate). Or, the wafer W is a substrate made of materials such as sapphire, glass, or quartz. The glass can be, for example, alkali glass, alkali-free glass, soda-lime glass, lead glass, borosilicate glass, or quartz glass.

[0025] The wafer W shown in Figure 2 is constructed as a semiconductor wafer, with devices D regularly formed on its surface Wa. Streets S (planned division lines) are set between each device D, orthogonal to each other, and cutting grooves are formed along the streets S, as will be described in more detail later. Note that devices D may not be formed at all.

[0026] The back surface Wb of the wafer W is attached to the adhesive surface of the tape T and fixed to the annular frame F via the tape T. Alternatively, the front surface Waa of the wafer W may be attached to the tape T, and the tape T may also be one without an adhesive surface (glue layer).

[0027] Next, an example of a workpiece processing method according to the present invention will be described. Figure 3 is a flowchart showing each step of the workpiece processing method.

[0028] <Cutting Step> As shown in Figure 4, the step involves cutting the wafer W held on the holding table 20 with a cutting blade 52 while supplying cutting fluid from the cutting fluid supply nozzle 51.

[0029] As shown in Figure 4, the cutting unit 5 has a cutting blade 52 that is detachably attached to the tip of a spindle (not shown). At a height below the cutting blade 52, horizontal sections of cutting fluid supply nozzles 51 are positioned on both sides of the cutting blade 52. The horizontal sections of the cutting fluid supply nozzles 51 have nozzles (not shown) that open toward the side of the cutting blade 52.

[0030] The cutting fluid supply nozzle 51 is connected to the cutting fluid supply source 57 via a valve 56, and a cutting fluid such as pure water is sprayed into the cutting fluid supply nozzle 51 under the control of a controller (not shown). The nozzle of the cutting fluid supply nozzle 51 opens toward the cutting blade 52, and the cutting fluid sprayed toward the cutting blade is supplied to the machining point where the cutting blade cuts into the wafer W. The flow rate of the sprayed cutting fluid per unit time can be controlled by the controller. The cutting fluid is, for example, pure water.

[0031] Furthermore, the cutting unit 5 is provided with a nozzle block 53 connected to a cutting fluid supply source 59 via a valve 58. The nozzle block 53 has an opening for a shower nozzle that sprays cutting fluid toward the outer edge of the cutting blade 52. This cutting fluid may be, for example, pure water, or the same liquid as the cutting fluid supplied from the cutting fluid supply nozzle 51.

[0032] Alternatively, the cutting fluid supply source 57 and the cutting fluid supply source 59 may be configured as a single unit, with the cutting fluid supplied from the same source via valves 56 and 58.

[0033] The holding table 20 has a porous plate 22 that constitutes a suction holding surface 21. A containment space 20a formed below the porous plate 22 is connected to a suction source 28 via a valve 27. By opening the valve 27 under the control of a controller (not shown), negative pressure is generated on the suction holding surface 21, and the wafer W is held in place by suction on the suction holding surface 21 via tape T. The annular frame F of the wafer unit U is held by clamps 23 provided at multiple locations.

[0034] In the above configuration, during cutting, the position of the cutting blade 52 in the Y-axis direction is aligned with the street S (Figure 2) by alignment using the captured image acquired by the imaging unit 6 (Figure 1).

[0035] Then, the lower end of the cutting edge of the cutting blade 52 is positioned at a predetermined height, and while rotating the cutting blade 52, the injection of cutting fluid from the cutting fluid supply nozzle 51 is started. Next, the holding table 20 is machined in the X-axis direction, and the wafer W is cut along the street S (Figure 2), forming a cutting groove. The cutting groove is formed by a full cut, which completely cuts the wafer W in the thickness direction, or a half cut, which forms a groove up to the middle of the wafer W in the thickness direction.

[0036] After forming a cutting groove in a street S (Figure 2), the holding table 20 is indexed and fed in the Y-axis direction to form a cutting groove in the adjacent street S (Figure 2). After forming cutting grooves in the streets S extending in the first direction, the holding table 20 is rotated 90 degrees, and cutting grooves are similarly formed in the streets S extending in the second direction perpendicular to the first direction, thereby forming cutting grooves in all streets S.

[0037] The cutting debris generated during the formation of these cutting grooves is partially washed away from the surface of the wafer W as wastewater along with the cutting fluid, but some remains on the surface of the wafer W and remains as particles. To prevent these particles from adhering to the surface of the wafer W when the water in the wastewater evaporates, the following cleaning steps are performed.

[0038] < cutting fluid Cleaning steps > As shown in Figures 5 and 6, immediately after performing the cutting step, the cutting unit 5 is positioned above the held wafer W and in a position where the cutting blade 52 does not cut into the wafer W, without releasing the wafer from the holding table 20, and cutting fluid 55 is supplied to the wafer W from the cutting fluid supply nozzle 51 to clean the wafer W with the cutting fluid 55.

[0039] Specifically, for example, the cutting unit 5 is positioned above the holding table 20 such that the height distance H from the holding table 20 to the center of the cutting blade 52 is equal to the height distance H. The cutting unit 5 is then positioned approximately above the center of the wafer W by adjusting the position of the cutting unit 5 in the Y-axis direction and the position of the holding table 20 in the X-axis direction.

[0040] Then, the cutting fluid 55 is sprayed toward the cutting blade 52 for a predetermined time, and the cutting fluid 55 that hits the cutting blade 52 is allowed to flow onto the wafer W, thereby cleaning the surface Wa of the wafer W. The cutting blade 52 may be rotated or stopped. In particular, if the cutting fluid is pure water, stopping the rotation can prevent the leaching of metals such as nickel contained in the cutting blade 52.

[0041] Furthermore, cleaning is performed by rotating the holding table 20 while moving the cutting unit 5 in the Y-axis direction, or by rotating the holding table 20 while moving it in the X-axis direction. Note that the rotation of the holding table 20 and movement in the X-axis direction, and the cutting unit 5 in the Y-axis direction may be stopped, and the system is not limited to this configuration. In addition, the flow rate of the sprayed cutting fluid 55 per unit time may be increased compared to that in the cutting step. Furthermore, the cutting unit 5 may be moved vertically, and the height distance H may be changed according to time.

[0042] Furthermore, in this cleaning step, cutting fluid may be sprayed from the nozzle of a shower nozzle provided on the nozzle block 53 toward the outer edge of the cutting blade 52, and this cutting fluid may be allowed to flow onto the wafer W, thereby contributing to the cleaning of the wafer W.

[0043] In the cutting unit 5, if the cutting fluid supply nozzle 51 is not provided and only the nozzle block 53 is provided, the wafer W will be cleaned by the cutting fluid sprayed from the nozzle block 53. In the configuration where the nozzle block 53 is not provided and only the cutting fluid supply nozzle 51 is provided, the wafer W will be cleaned by the cutting fluid sprayed from the cutting fluid supply nozzle 51.

[0044] By performing the cleaning step as described above, the surface of the wafer W (workpiece) is cleaned with cutting fluid immediately after the cutting step is completed. This allows for efficient removal of cutting debris without it remaining on the surface, preventing it from adhering to the surface as particles.

[0045] <Main cleaning step> As shown in Figure 7, after performing the cleaning step, the wafer W is transported to the cleaning device 60, and the wafer W is cleaned in the cleaning device 60.

[0046] The cleaning apparatus 60 comprises a housing 61 that constitutes the cleaning space 61a, a spinner table 62 that is rotationally driven by a motor 69 to hold a wafer W (wafer unit U), a support base 63 that supports and raises the lower part of the spinner table 62, a clamp 64 that holds the wafer unit U held by the spinner table 62, a nozzle unit 65 that supplies cleaning fluid to the wafer W, and a moving unit 68 that moves the nozzle unit 65.

[0047] On the holding surface 62a of the spinner table 62, the wafer W of the wafer unit U is held in place by suction from below via the tape T. On the outer periphery of the spinner table 62, the annular frame F of the wafer unit U is placed and held by a clamp 64 that tilts due to centrifugal force.

[0048] The nozzle unit 65 has a horizontally extending swing arm 66a, the rear end of which is fixed to the pivot shaft 68a of the moving unit 68. The pivot shaft 68a of the moving unit 68 is rotated by a motor 68b, which causes the swing arm 66a to swing horizontally above the spinner table 62, and the cleaning fluid nozzle 66 provided at the tip of the swing arm 66a moves.

[0049] A cleaning solution is supplied from the cleaning solution nozzle 66. The cleaning solution is a single liquid such as pure water, or a mixed fluid (two-fluid cleaning water) obtained by mixing a liquid such as pure water with a gas such as air. The cleaning solution nozzle 66 is connected to a cleaning solution supply source via a swing arm 66a and a control valve (not shown), and the supply and stop of the cleaning solution are controlled by the control valve.

[0050] After cleaning the wafer W with the cleaning apparatus 60 configured as described above, the spinner table 62 is rotated at high speed to dry the wafer W.

[0051] As described above, since the surface of the wafer W is cleaned with cutting fluid in the cleaning step, the probability of particles being present on the surface of the wafer W after this cleaning step can be further reduced. In other words, by performing a total of two cleanings, the cleaning step and this cleaning step, a higher cleaning effect can be obtained, and the occurrence of device damage or defects such as bonding failures due to the presence of particles can be more effectively prevented. [Explanation of symbols]

[0052] 2 Processing equipment 4 base 5 Cutting Units 6. Imaging Unit 20 Holding Tables 21 Suction holding surface 22 Porous Plates 23 Clamp 27 valves 28 Suction source 51 Cutting fluid supply nozzle 52 cutting blades 53 Nozzle Block 55 Cutting fluid 60 Washing device 61 cabinets 61a Washing space 62 Spinner Table 65 Nozzle Unit 66 Cleaning solution nozzle 68 Mobile Units D Device F Circular Frame S Street T Tape U wafer unit W wafer Wa surface Wb back side

Claims

1. A holding table for holding the workpiece, A cutting unit that cuts the workpiece with a cutting blade while supplying a cutting fluid such as pure water to the workpiece, A method for machining a workpiece using a cutting device equipped with, A cutting step in which the cutting fluid is supplied while the workpiece held on the holding table is cut with the cutting blade, Immediately after performing the cutting step, the cutting unit is positioned above the held workpiece and in a position where the cutting blade does not cut into the workpiece, without releasing the workpiece from the holding table, and the cutting fluid is supplied to the workpiece held by the holding table to clean the workpiece with the cutting fluid. A method for machining a workpiece, wherein the flow rate of the cutting fluid per unit time in the cutting fluid cleaning step is increased compared to that in the cutting step.

2. In the cutting fluid cleaning step, the workpiece is cleaned with the cutting fluid while the holding table is moved relative to the cutting unit. The method for machining a workpiece as described in feature 1.

3. The method further comprises a cleaning step in which, after performing the cutting fluid cleaning step, the workpiece is transported to a cleaning device and the workpiece is cleaned in the cleaning device. A method for processing a workpiece according to claim 1 or 2.

4. A holding table for holding the workpiece, A cutting unit that cuts the workpiece with a cutting blade while supplying a cutting fluid such as pure water to the workpiece, A cutting device equipped with, The cutting unit is positioned above the workpiece held by the holding table and in a position where the cutting blade does not cut into the workpiece, and the cutting fluid is supplied to the workpiece held by the holding table to clean the workpiece with the cutting fluid. When cleaning the workpiece with the cutting fluid, the flow rate of the cutting fluid per unit time is: A cutting apparatus that increases the flow rate of the cutting fluid per unit time when cutting the workpiece.

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