Processing equipment

Abstract

To provide a processing device which does not need means for supplying a fresh coolant separately to keep a chuck table at a constant temperature and can solve a problem of being uneconomical.SOLUTION: Grinding means 3 of a grinding device 1 is formed including: a mount 34 to which a grinding wheel 35 is attached; a rotary shaft 33 connected to the mount 34; a motor 38 connected to the rotary shaft 33; a housing 32 including air bearings 70, 80 for supporting the rotary shaft 33 with air A; and a first passage 323 formed within the housing 32. Cooling means 7 for supplying a coolant L1 to cool the housing 32 is connected to the first passage 323. The chuck table 4 is formed including: a holding part 41 configured to suction and hold a wafer 10; a frame body 42 supporting the holding part 41; and a second passage 45 formed at the frame body 42. Control means 100 measures a temperature of waste water L2 discharged from the first passage 323 and supplies the waste water L2 to the second passage 45 to adjust a temperature of the chuck table 4 to a predetermined temperature.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a processing apparatus for adjusting the temperature of a chuck table to a predetermined temperature.

Background Art

[0002] A wafer on which a plurality of devices such as ICs and LSIs are formed on the surface and partitioned by a division planned line is formed to a predetermined thickness by a grinding apparatus, and then divided into individual device chips by a dicing apparatus, and used for electrical devices such as mobile phones and personal computers.

[0003] The grinding apparatus includes a chuck table for holding a wafer, grinding means for rotatably supporting a grinding wheel having an annular grinding stone for grinding the wafer held on the chuck table, grinding feed means for feeding the grinding means in a grinding feed direction, and control means, and can process the wafer to a desired thickness.

[0004] Also, even when grinding while supplying grinding water to the wafer held on the chuck table by the grinding means, heat during grinding is transmitted to the chuck table, causing minute distortion and variation in the thickness of the wafer, leading to a problem of quality degradation. Therefore, a technique has been proposed in which a water channel for supplying cooling water to the chuck table is provided to maintain a constant temperature (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] According to the technology described in Patent Document 1 mentioned above, cooling of the chuck table can be achieved by providing an independent cooling means for the chuck table and introducing cooling water. However, introducing a new cooling means to cool the chuck table and maintaining a constant temperature requires a considerable amount of cooling water, which is uneconomical.

[0007] The present invention has been made in view of the above facts, and its main technical problem is to provide a processing apparatus that can solve the problem of uneconomical practices by eliminating the need for a separate means of supplying cooling water to maintain the chuck table at a constant temperature. [Means for solving the problem]

[0008] To solve the above-mentioned main technical problems, the present invention provides a processing apparatus comprising: a chuck table for holding a wafer; a grinding means for rotatably supporting a grinding wheel having an annular grinding wheel for grinding the wafer held on the chuck table; a grinding feed means for grinding feed the grinding means; and a control means, wherein the grinding means comprises a mount for mounting the grinding wheel, a rotating shaft connected to the mount, a motor connected to the rotating shaft, a housing equipped with an air bearing for supporting the rotating shaft with air, and a first flow path formed within the housing, wherein a cooling means for supplying cooling water to cool the housing is connected to the first flow path, the chuck table comprises a holding part for suction and holding a wafer, a frame supporting the holding part, and a second flow path formed in the frame, and the control means measures the temperature of wastewater discharged from the first flow path and supplies the wastewater to the second flow path to adjust the temperature of the chuck table to a predetermined temperature.

[0009] The control means may mix the cooling water and the wastewater to produce constant-temperature water and supply it to the second flow path. The chuck table may also be manufactured in an environment with a predetermined temperature. [Effects of the Invention]

[0010] The processing apparatus of the present invention comprises a chuck table for holding a wafer, a grinding means for rotatably supporting a grinding wheel having an annular grinding wheel for grinding the wafer held on the chuck table, a grinding feed means for grinding feed the grinding means, and a control means, wherein the grinding means comprises a mount for mounting the grinding wheel, a rotating shaft connected to the mount, a motor connected to the rotating shaft, a housing equipped with an air bearing for supporting the rotating shaft with air, and a first flow path formed within the housing. A cooling means is connected to the first flow path to cool the housing by supplying cooling water. The chuck table is configured to include a holding part that sucks and holds a wafer, a frame that supports the holding part, and a second flow path formed in the frame. The control means measures the temperature of the wastewater discharged from the first flow path and supplies the wastewater to the second flow path to adjust the temperature of the chuck table to a predetermined temperature. Therefore, there is no need to provide a separate means for supplying cooling water to maintain the chuck table at a constant temperature, thus eliminating the problem of uneconomical implementation. [Brief explanation of the drawing]

[0011] [Figure 1] This is an overall perspective view of the grinding machine. [Figure 2] Figure 1 is a conceptual diagram showing a longitudinal section of the grinding means mounted on the grinding apparatus, as well as the cooling water supply path and the high-pressure air supply path. [Figure 3] This is a perspective view showing the grinding process. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of a processing apparatus configured according to the present invention will be described in detail with reference to the attached drawings.

[0013] Figure 1 shows an overall perspective view of a grinding apparatus 1, which is shown as an example of a processing apparatus of this embodiment. The illustrated grinding apparatus 1 comprises an apparatus housing 2, and a support wall 21 is erected on the rear end side of the apparatus housing 2. A pair of guide rails 22, 22 extending in the vertical direction (Z-axis direction) are provided on the inner surface of this support wall 21. The grinding means 3 is supported by a movable base 31 and mounted on the guide rails 22, 22 so as to be movable in the vertical direction. A control means 100 equipped with an operation panel 110 for operating the grinding apparatus 1 is provided on the front side of the apparatus housing 2, and a display means (not shown) is connected to the control means 100.

[0014] A chuck table 4 for holding the workpiece, a wafer 10, is provided on the upper surface of the apparatus housing 2. The wafer 10 whose back surface 10b is to be ground by the grinding apparatus 1 of this embodiment has a protective tape T attached to its surface, on which a device (not shown) is formed. The chuck table 4 comprises a holding portion 41 for suction-holding the wafer 10, and a frame 42 that surrounds and supports the holding portion 41. The chuck table 4 is rotatably positioned in the center of the cover plate 5 and is configured to move in the Y-axis direction, more specifically between the wafer attachment / detachment position where the chuck table 4 is positioned in Figure 1, and the grinding position where grinding is performed directly below the grinding means 3, by a moving means (not shown) provided inside the apparatus housing 2.

[0015] The grinding means 3 comprises a housing 32 supported on a movable base 31 via a support member 37, a mount 34 disposed at the lower end of a rotating shaft 33 rotatably supported in the housing 32, a grinding wheel 35 mounted on the mount 34 with a plurality of grinding wheels 36 arranged in an annular pattern on its lower surface, and a motor 38 mounted inside the upper end of the housing 32 for rotating the rotating shaft 33.

[0016] The grinding apparatus 1 includes a grinding feed mechanism 6 that moves the grinding means 3 vertically along a pair of guide rails 22, 22. The grinding feed mechanism 6 comprises a ball screw 61 and a pulse motor 62. By controlling the rotational drive of the pulse motor 62 by the control mechanism 100, the ball screw 61 rotates, moving the movable base 31 that supports the grinding means 3 to a desired position in the vertical direction.

[0017] Figure 2 schematically shows a longitudinal section of the housing 32 that constitutes the grinding means 3. The housing 32 of the grinding means 3 is equipped with an air bearing, which will be described in detail later, that supports the rotating shaft 33 with air. The rotating shaft 33 has a disc-shaped thrust plate 331 that is integrally formed with the rotating shaft 33, and the air bearing includes a radial air bearing 70 that supports the rotating shaft 33 in the radial direction (diameter direction) with air, and a thrust air bearing 80 that supports the rotating shaft 33 in the thrust direction (up and down direction) that sandwiches the thrust plate 331 with air.

[0018] A supply port 392 is provided on the outer circumference of the housing 32 of the grinding means 3, through which high-pressure air A (e.g., 0.6 MPa) is supplied via a path 391 from an external air supply source 39. Inside the housing 32, supply paths 321 and 322 are provided through the supply port 392 to which high-pressure air A is supplied. An air outlet 321a connected to the supply path 321 is provided in the space that supports the rotating shaft 33 in the radial direction, and a radial air bearing 70 is formed by ejecting high-pressure air A from the air outlet 321a to support the rotating shaft 33. An air outlet 322a connected to the supply path 322 is provided in the space that supports the thrust plate 331 in the thrust direction, and a thrust air bearing 80 is formed by ejecting high-pressure air A from the air outlet 322a to support the thrust plate 331. The high-pressure air A, having passed through the radial air bearing 70 and the thrust air bearing 80, is discharged to the outside of the housing 32 through an exhaust path and outlet (not shown in the diagram).

[0019] Since the grinding means 3 includes the above-described radial air bearing 70 and thrust air bearing 80, high-pressure air A is ejected from the above-described air ejection ports 321a and 322a, and a high-pressure air layer with minute gaps (5 to 10 μm) is formed around the rotating shaft 33 and the thrust plate 331, and the rotating shaft 33 is configured to be supported in a non-contact state by the housing 32. As described above, a motor 38 is accommodated in the housing 32, and the rotating shaft 33 can stably rotate at high speed with extremely little resistance in the direction indicated by arrow R1. In addition, pressure gauges and flow meters (not shown) are arranged in the path for supplying high-pressure air A from an external air supply source 39 to adjust the pressure and flow rate of the high-pressure air A supplied from the air supply source 39 to the supply paths 321 and 322 in the housing 32.

[0020] Inside the housing 32 that constitutes the grinding means 3 of the above-described present embodiment, a first flow path 323 is formed independently of the supply paths 321 and 322 through which the above-described high-pressure air A flows. The first flow path 323 is a passage for circulating the cooling water L1. On the outer peripheral portion of the housing 32, a cooling water supply port 324 for introducing the cooling water L1 into the first flow path 323 and a discharge port 325 for discharging the waste water L2 after cooling the inside of the housing 32 after passing through the first flow path 323 are arranged. A cooling means 7 for supplying the cooling water L1 via a cooling water supply path 7a is connected to the cooling water supply port 324. The cooling water L1 supplied from the cooling means 7 is water at a certain temperature (for example, 23°C), but it is not necessarily required to forcibly lower the temperature by a refrigerating means or the like. If the clean room where the grinding apparatus 1 is arranged is managed at, for example, 23°C at all times, the water stored in the clean room may be used as it is. By flowing the cooling water L1 through the first flow path 323 formed in the housing 32, it is possible to prevent the rotating shaft 33 and the housing 32 from overheating due to the heat of the motor 38 and the heat during grinding transmitted from the grinding wheel 36, the grinding wheel 35, and the like.

[0021] A wastewater discharge channel 7b is connected to the outlet 325 of the housing 32, and the wastewater L2 discharged from the outlet 325 is supplied to the chuck table 4 shown in the figure via the wastewater discharge channel 7b.

[0022] The internal structure of the chuck table 4 will be explained in more detail with reference to Figure 2. For the sake of explanation, the cover plate 5 on which the chuck table 4 is mounted is omitted. In the chuck table 4 shown in the cross section, a wafer 10 is placed on the holding portion 41 with the side to which the protective tape T is attached facing downwards. The holding portion 41 is formed of a porous material that allows for airflow, and the frame 42 that surrounds and supports the holding portion 41 is connected to the motor 40 via a rotary joint 44. The space 43a formed by the upper surface of the frame 42 and the lower surface of the holding portion 41, and the negative pressure path 43b extending downward from the space 43a, are connected to the suction source 46 via the rotary joint 44. By operating the suction source 46, negative pressure is generated on the upper surface of the holding portion 41 via the space 43a and the negative pressure path 43b, allowing the wafer 10 to be held in place by suction. Inside the frame 42, a second flow path 45 is formed, independent of the aforementioned space 43a and negative pressure path 43b. The second flow path 45 branches horizontally into multiple paths inside the frame 42 to cool the entire frame 42. The rotary joint 44 is equipped with a wastewater inlet 45a connected to the second flow path 45, and a wastewater outlet 45b connected to the second flow path 45 for discharging the wastewater L2 introduced from the wastewater inlet 45a. The wastewater L2 that has flowed through the second flow path 45 is collected in the water storage container 90 via the drain pipe 7c from the wastewater outlet 45b.

[0023] When the grinding device 1 operates to grind the wafer 10, which is the workpiece, it is important that the finishing production is carried out in an environment with a predetermined temperature, such as 30 to 35 °C, which is the temperature adjustment target of the chuck table 4. That is, for example, the holding portion 41 is press-fitted onto the upper surface of the frame body 42, and the upper surface of the support portion 41 and the upper surface of the frame body 41 are simultaneously ground to make the upper surface of the chuck table 4 flat. By manufacturing in this way, the chuck table 4 in the state where the grinding device 1 is stopped generally shrinks in an atmosphere of the temperature (for example, 23 °C) of the clean room where the semiconductor wafer processing device is arranged. However, when the grinding device 1 is in an operating state, it is heated to a predetermined temperature (30 to 35 °C) to be adjusted and slightly expands to form a shape along the design target dimensions, contributing to the improvement of processing accuracy.

[0024] The waste water discharge path 7b described above is connected to the waste water inlet 45a of the rotary joint 44, and the waste water L2 discharged from the discharge port 325 of the housing 32 is introduced from the waste water inlet 45a of the rotary joint 44 through the waste water discharge path 7b into the second flow path 45 inside the frame body 42 of the chuck table 4. A second valve 8b is provided in the waste water discharge path 7b, and by adjusting the opening degree of the second valve 8b, the flow rate of the waste water L2 introduced into the second flow path 45 of the chuck table 4 is adjusted.

[0025] On the upstream side of the second valve 8b of the waste water discharge path 7b described above, a first water temperature gauge 120 for detecting the temperature of the waste water L2 discharged from the first flow path 323 is provided. Also, on the downstream side of the second valve 8b, a second water temperature gauge 130 is provided.

[0026] In the grinding apparatus 1 of this embodiment, a bypass passage 7d is connected to the wastewater discharge passage 7b described above, bypassing the housing 32 of the grinding means 3, upstream of the first valve of the cooling water supply passage 7a that supplies cooling water L1 from the cooling means 7. In addition, in the wastewater discharge passage 7b, a relief valve 8d equipped with a check valve structure is provided downstream of the outlet 325 of the housing 32, and upstream of the confluence point of the wastewater discharge passage 7b and the bypass passage 7d. The rotating shaft 33 is hollow, and grinding water L4 supplied from the grinding water supply means 9 is introduced from the upper end of the rotating shaft 33 and sprayed onto the grinding area by the grinding wheel 36 from the lower surface of the grinding wheel 35.

[0027] The control means 100 is composed of a computer and includes a central processing unit (CPU) that performs calculations according to a control program, a read-only memory (ROM) for storing the control program and the like, a read-write random access memory (RAM) for temporarily storing detected values, calculation results, etc., an input interface, and an output interface (details are not shown in the illustration). The control means 100 is connected to the motor 38 that drives the grinding means 3 of the grinding device 1, the grinding feed means 6, the moving means for the chuck table 4, etc., and its operation is controlled. The first valve 8a, the second valve 8b, and the third valve 8c are also connected to the control means 100, and the opening and closing and degree of opening of each valve are controlled by the control means 100.

[0028] The grinding apparatus 1 and grinding means 3 of this embodiment have generally the configuration described above, and their functions and operations will be explained below.

[0029] When the back surface 10b of the wafer 10 is ground and thinned using the grinding apparatus 1 shown in Figure 1, a protective tape T is attached to the surface side of the wafer 10 where the device is formed, and the wafer is placed on the holding part 41 of the chuck table 4 positioned at the wafer attachment / detachment position as shown in Figure 1, and the suction source 46 described above is activated to hold the wafer by suction. Next, the moving means described above is activated to position the chuck table 4 at the grinding position directly below the grinding means 3, as shown in Figure 3 which shows an embodiment of the grinding process. Next, the air supply source 39 described above is activated to operate the air bearings (radial air bearing 70, thrust air bearing 80), and the motor 38 is activated to rotate the rotation shaft 33 in the direction indicated by arrow R1 in Figure 3, for example at 6000 rpm, while rotating the chuck table 4 in the direction indicated by arrow R2, for example at 300 rpm. Then, by activating the grinding water supply source 9 described above, grinding water L4 is supplied onto the back surface 10b of the wafer 10, while the grinding wheel 36 is brought into contact with the back surface 10b of the wafer 10, and the grinding wheel 76 is fed downward at a grinding feed rate of, for example, 1 μm / second. At this time, the thickness of the wafer 10 can be measured using a contact-type or non-contact-type measuring gauge (not shown) while grinding is carried out, and a predetermined amount of the back surface 10b of the wafer 10 is ground to a predetermined thickness.

[0030] When performing the grinding process described above, the cooling means 7, as explained in Figure 2, is activated to open the first valve 8a and the second valve 8b (at this time, the third valve 8c is closed). In this way, cooling water L1 is supplied from the cooling means 7 to the first flow path 323 in the housing 32 at a constant flow rate, and the temperature inside the housing 32, which tends to rise due to the high-speed rotation of the motor 38 and the grinding load, is reduced. The cooling water L1 introduced into the housing 32 in this way is heated by cooling the inside of the housing 32 and discharged as wastewater L2 from the outlet 325 of the housing 32 to the wastewater discharge path 7b. The flow rate of the wastewater L2 is set so that it is discharged at a temperature lower than a predetermined temperature (for example, 30-35°C) at which the chuck table 4, described later, is adjusted.

[0031] The wastewater L2 discharged into the wastewater discharge channel 7b is introduced into the second flow channel 45 from the wastewater inlet 45a of the chuck table 4, cools the frame 42 of the chuck table 4, and is discharged into the storage container 90 from the wastewater outlet 45b for storage. Here, the control means 100 measures the temperature of the wastewater L2 discharged from the first flow channel 323 based on the first water thermometer 120 and the second water thermometer 130, and supplies the wastewater L2 to the second flow channel 45 to adjust the temperature of the chuck table 4 to the predetermined temperature. In this embodiment, this adjustment is carried out by adjusting the opening degree of the second valve 8b described above. For example, if the temperature of the wastewater L2 is high, the opening degree of the second valve 8b is controlled to increase the flow rate of the wastewater L2, and if the temperature of the wastewater L2 is low, the opening degree of the second valve 8b is controlled to decrease the flow rate of the wastewater L3. This ensures that the temperature of the chuck table 4 is always adjusted to a predetermined temperature (e.g., 30-35°C) regardless of changes in the load applied to the grinding means 3.

[0032] If the opening of the second valve 8b is set to a small degree, the flow of water through the second valve 8b in the wastewater discharge channel 7b will be restricted, increasing the water pressure on the upstream side, which may prevent proper temperature control within the housing 32. However, in this embodiment, as described above, a relief valve 8d is provided upstream of the second valve 8b on the wastewater discharge channel 7b. When a certain pressure is applied, this valve opens, allowing the wastewater L2 from the wastewater discharge channel 7b to be discharged into a discharge channel not shown, thus preventing such problems. The first water thermometer 120 detects the temperature upstream of the second valve 8b, and the second water thermometer 130 detects the temperature downstream of the second valve 8b. By adjusting the opening of the second valve 8b, a temperature difference may occur between the two, and the estimated temperature of the wastewater L2 introduced into the chuck table 4 can be corrected based on this temperature difference. However, the present invention is not limited to providing both the first water temperature gauge 120 and the second water temperature gauge 130 described above, and may be implemented by providing only one of them.

[0033] The embodiment described above is not limited to measuring the temperature of the wastewater L2 discharged from the first flow path 323 and supplying the wastewater L2 to the second flow path 45 of the chuck table 4 to adjust the temperature of the chuck table 4 to a predetermined temperature.

[0034] As described above, a bypass passage 7d is connected to the upstream side of the first valve 8a of the cooling water supply passage 7a that supplies cooling water L1 from the cooling means 7, bypassing the housing 32 of the grinding means 3 and connecting to the wastewater discharge passage 7b, and a third valve 8c is placed on the bypass passage 7b. By using this bypass passage 7d and the third valve 8c, mixed water L1+L2, which is a mixture of the cooled water L1 supplied from the cooling means 7 and the wastewater L2 discharged from the first passage 323, can be supplied to the second passage 45, and the temperature of the chuck table 45 can be adjusted to a predetermined temperature. More specifically, first, the first valve 8a and the second valve 8b are opened. Then, the third valve 8c is opened, and the temperature of the mixed water L1+L2 flowing through the wastewater discharge passage 7b is detected based on the first water thermometer 120 and the second water thermometer 130 (either one or the other may be used). Then, by adjusting the opening of the third valve 8c, the amount of cooling water L1 introduced into the wastewater discharge channel 7b via the bypass channel 7d is adjusted, and the mixing ratio of the cooling water L1 and wastewater L2 is adjusted to generate constant-temperature water at a constant temperature (e.g., 27°C). By supplying this constant-temperature water as the wastewater of the present invention to the second flow path 45 of the chuck table 4, the temperature of the chuck table 4 can be adjusted so that it is always at a predetermined temperature (e.g., 30-35°C) while grinding is being performed.

[0035] As described above, once the back surface 10b of the wafer 10 has been ground by a predetermined amount while cooling the grinding means 3 and the chuck table 4, the grinding means 3 is stopped, and the process is completed by going through a cleaning process using a cleaning device (not shown), a drying process using a drying device, etc., to grind the back surface 10b of the wafer 10.

[0036] According to the embodiment described above, there is no need to provide a means for supplying independent cooling water to maintain the chuck table 4 at a constant temperature, thus eliminating the problem of uneconomical practices. [Explanation of symbols]

[0037] 1: Grinding device 2: Device housing 21:Supporting wall 22, 22: Guide rail 3: Grinding method 31: Mobile base 32: Housing 321: Supply Route 321a: Air nozzle 322: Supply Route 322a: Air nozzle 323: First channel 325: Outlet 33: Rotation axis 331: Thrust Plate 34: Mount 35: Grinding Wheel 36: Grinding Wheel 38: Motor 39: Air supply source 391: Route 392: Supply port 4: Chuck Table 40: Motor 41: Holding part 42:Frame body 43a: Space 43b: Negative pressure path 44: Rotary joint 44a: Negative pressure supply port 45: Second channel 45a: Wastewater inlet 45b: Waste water outlet 46:Suction source 5: Cover board 6: Grinding feed means 61: Ball screw 62: Pulse motor 7: Cooling means 7a: Cooling water supply path 7b: Wastewater discharge channel 7c: Drain pipe 7d: Bypass road 8a: First valve 8b: Second valve 8c: Third valve 8d: Relief valve 9: Grinding water supply source 9a: Grinding water supply channel 70: Radial air bearing 80: Thrust air bearing 90: Water storage container 100: Control means 110: Control Panel 120: 1st water temperature gauge 130:Second water temperature gauge

Claims

1. A processing apparatus comprising: a chuck table for holding a wafer; a grinding means for rotatably supporting a grinding wheel having an annular grinding wheel for grinding the wafer held on the chuck table; a grinding feed means for grinding and feeding the grinding means; and a control means, The grinding means comprises a mount for mounting a grinding wheel, a rotating shaft connected to the mount, a motor connected to the rotating shaft, a housing equipped with an air bearing that supports the rotating shaft with air, and a first flow path formed within the housing. A cooling means is connected to the first flow path to supply cooling water and cool the housing. The chuck table comprises a holding section for suctioning and holding a wafer, a frame supporting the holding section, and a second flow path formed in the frame. The control means measures the temperature of the wastewater discharged from the first channel and supplies the wastewater to the second channel to adjust the temperature of the chuck table to a predetermined temperature.

2. The processing apparatus according to claim 1, wherein the control means mixes the cooling water and the wastewater to generate constant temperature water and supplies it to the second flow path.

3. The processing apparatus according to claim 1 or 2, wherein the chuck table is manufactured in an environment at the predetermined temperature.

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