Pad Temperature Adjusting Device and Polishing Device

Abstract

To provide a pad temperature adjustment device equipped with a heat exchanger that can clean even a limited space.SOLUTION: A pad temperature adjustment device 5 comprises: a heat exchanger 11 which contacts an abrasive pad 3, and performs exchanges heat with the abrasive pad 3; a movement mechanism which moves the heat exchanger 11 between a temperature control position at which the heat exchanger 11 can exchange heat with the abrasive pad 3 and a retreat position at which the heat exchange is positioned on a side of the abrasive pad 3; and a cleaning mechanism which cleans the heat exchanger 11 moved to the retreat position. The heat exchanger 11 has a substantially triangular horizontal cross shape, and a longest side of the heat exchanger 11 faces the abrasive pad 3 when the heat exchanger 11 moved to the retreat position.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pad temperature adjustment device provided with a heat exchanger for adjusting the surface temperature of a polishing pad. Further, the present invention relates to a polishing device provided with such a pad temperature adjustment device.

Background Art

[0002] A CMP (Chemical Mechanical Polishing) apparatus is a polishing apparatus used in the process of polishing the surface of a substrate such as a wafer in the manufacture of semiconductor devices. The CMP apparatus holds a substrate with a polishing head and rotates the substrate, and further presses the substrate against a polishing pad on a rotating polishing table to polish the surface of the substrate. During polishing, a polishing liquid (slurry) is supplied to the polishing pad, and the surface of the substrate is planarized by the chemical action of the polishing liquid and the mechanical action of abrasive grains contained in the polishing liquid.

[0003] The polishing rate of the substrate depends not only on the polishing load of the substrate against the polishing pad but also on the surface temperature of the polishing pad. This is because the chemical action of the polishing liquid on the substrate depends on the temperature. Therefore, in the manufacture of semiconductor devices, it is important to maintain the surface temperature of the polishing pad during substrate polishing at an optimal value in order to increase and further keep constant the polishing rate of the substrate.

[0004] Therefore, a pad temperature adjustment device for adjusting the surface temperature of the polishing pad has been conventionally used (see, for example, Patent Document 1). The pad temperature adjustment device has a heat exchanger that contacts the surface of the polishing pad and to which a temperature-adjusted heating liquid and a cooling liquid are supplied. By adjusting the flow rate of the heating liquid and the flow rate of the cooling liquid supplied to the heat exchanger, the surface temperature of the polishing pad during substrate polishing can be maintained at a desired optimal temperature.

[0005] During the polishing of the substrate, the heat exchanger is in contact with the surface of the polishing pad, and dirt such as abrasive grains contained in the polishing liquid and wear powder of the polishing pad adheres to the surface of the heat exchanger. If the dirt falls off from the heat exchanger during the polishing of the substrate and is sandwiched between the polishing pad and the substrate, scratches will be formed on the surface of the wafer. The scratches can become defects that reduce the reliability of the semiconductor device. In other words, the scratches are a factor that reduces the yield of the semiconductor device. Therefore, it is preferable to clean the heat exchanger regularly (for example, every time the substrate is polished).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in conventional polishing apparatuses, the polishing pad is disposed in a polishing chamber partitioned by partition walls, and in the current situation where downsizing of the apparatus is required, it is required to make the installation area of the polishing chamber as small as possible. Therefore, it is difficult to secure a sufficient cleaning space for the heat exchanger on the side of the polishing pad.

[0008] FIG. 15(a) is a schematic top view showing an example of a conventional polishing apparatus, and FIG. 15(b) is a schematic top view showing a state in which the heat exchanger shown in FIG. 15(a) is moved toward the partition wall. The polishing apparatus shown in FIG. 15(a) includes a polishing head 101 that holds and rotates a substrate (for example, a wafer), a polishing pad 103 supported by a polishing table, and a heat exchanger 111 of a pad temperature adjustment device that adjusts the surface temperature of the polishing pad 103. The conventional heat exchanger 111 has a circular shape in a horizontal cross-sectional view. The polishing head 101, the polishing pad 103, and the heat exchanger 111 are disposed in a polishing chamber 180 partitioned by a plurality of partition walls 181.

[0009] In order to achieve downsizing of the polishing apparatus, the partition wall 181 needs to be as close as possible to the polishing pad 103. However, if the partition wall 181 is brought close to the polishing pad 103, it becomes impossible to provide a surplus space for cleaning the heat exchanger 111 having a circular shape in the polishing chamber 180. For example, as shown in FIG. 15(b), the heat exchanger 111 cannot be completely moved to the side of the polishing pad 103 (in other words, a part of the heat exchanger 111 overlaps the polishing pad 103 in the vertical direction), and as a result, a space for cleaning the heat exchanger 111 cannot be secured.

[0010] Therefore, an object of the present invention is to provide a pad temperature adjusting device including a heat exchanger that can be cleaned even in a limited space. Another object of the present invention is to provide a polishing apparatus including such a pad temperature adjusting device.

Means for Solving the Problems

[0011] In one aspect, there is provided a pad temperature adjusting device for adjusting the surface temperature of a polishing pad, including a heat exchanger that contacts the polishing pad and exchanges heat with the polishing pad, a moving mechanism that moves the heat exchanger between a temperature adjusting position where the heat exchanger can exchange heat with the polishing pad and a retracted position located on the side of the polishing pad, and a cleaning mechanism that cleans the heat exchanger moved to the retracted position. The heat exchanger has a substantially triangular horizontal cross-sectional shape, and the longest side of the heat exchanger faces the polishing pad when the heat exchanger is moved to the retracted position, and the pad temperature adjusting device is provided.

[0012] In one aspect, the heat exchanger has, inside thereof, a heating flow path and a cooling flow path to which a temperature-adjusted heating liquid and a cooling liquid are respectively supplied. The heating flow path and the cooling flow path extend adjacent to each other and extend in a spiral shape along the outer shape of the heat exchanger. An inlet of the heating flow path and an inlet of the cooling flow path are located at a peripheral portion of the heat exchanger, and an outlet of the heating flow path and an outlet of the cooling flow path are located at a central portion of the heat exchanger. In one aspect, the heat exchanger has a substantially isosceles triangular horizontal cross-sectional shape that is line-symmetric with respect to a straight line connecting the midpoint of the long side and the intersection points of the remaining two sides. In one aspect, the heat exchanger has a shape in which the midpoint of the long side protrudes outward from the straight line connecting both ends of the long side.

[0013] In one aspect, the moving mechanism includes an arm that holds the heat exchanger, a lifting mechanism that raises and lowers the heat exchanger via the arm, and a link mechanism that is attached to the heat exchanger and connects the heat exchanger to the arm. The link mechanism allows vertical movement of the heat exchanger with respect to the arm but restricts horizontal movement of the heat exchanger with respect to the arm. In one aspect, the link mechanism includes a first link arm connected to the arm, a second link arm connected to the arm and disposed on the opposite side of the first link arm with the arm interposed therebetween, a first link block attached to the upper surface of the first link arm, a second link block attached to the upper surface of the heat exchanger, and a link rod having both ends rotatably supported by the first link block and the second link block and having a link protrusion extending downward on the end side supported by the second link block. The link protrusion is spaced apart from the upper surface of the second link arm when the heat exchanger is in the temperature adjustment position, and the link protrusion contacts the upper surface of the second link arm when the heat exchanger is raised by the lifting mechanism. In one aspect, the link mechanism further includes a stopper that blocks vertical movement of the heat exchanger with respect to the arm. When the heat exchanger is further raised by the lifting mechanism after the link protrusion contacts the upper surface of the second link arm, the stopper contacts the upper surface of the first link arm. In one aspect, the cleaning mechanism includes a cleaning tank in which the bottom surface of the heat exchanger is immersed, and a swinging mechanism that swings the cleaning tank with respect to the heat exchanger.

[0014] In one aspect, there is provided a polishing apparatus for polishing a substrate by bringing the substrate into sliding contact with a polishing pad, the polishing apparatus including a polishing table that supports the polishing pad, a polishing head that presses the substrate against the polishing pad, and a pad temperature adjustment device that adjusts the surface temperature of the polishing pad. The pad temperature adjustment device is the above-described pad temperature adjustment device.

Advantages of the Invention

[0015] According to the present invention, since the heat exchanger has a substantially triangular horizontal cross-sectional shape, it can be cleaned in the surplus space formed between the partition wall that partitions the polishing chamber and the polishing pad. Therefore, the heat exchanger can be cleaned even in a limited space.

Brief Description of the Drawings

[0016]

Figure 1

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Figure 15

DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a polishing apparatus according to an embodiment. The polishing apparatus shown in FIG. 1 includes a polishing head 1 that holds and rotates a wafer W, which is an example of a substrate, a polishing table 2 that supports a polishing pad 3, a polishing liquid supply nozzle 4 that supplies a polishing liquid (for example, slurry) to the surface of the polishing pad 3, and a pad temperature adjusting device 5 that adjusts the surface temperature of the polishing pad 3. The surface (upper surface) of the polishing pad 3 constitutes a polishing surface for polishing the wafer W.

[0018] The polishing head 1 is movable in the vertical direction and rotatable about its axis in the direction indicated by the arrow. The wafer W is held on the lower surface of the polishing head 1 by vacuum suction or the like. A motor (not shown) is connected to the polishing table 2 and is rotatable in the direction indicated by the arrow. As shown in FIG. 1, the polishing head 1 and the polishing table 2 rotate in the same direction. The polishing pad 3 is attached to the upper surface of the polishing table 2.

[0019] The wafer W is polished as follows. The wafer W to be polished is held by the polishing head 1 and further rotated by the polishing head 1. On the other hand, the polishing pad 3 is rotated together with the polishing table 2. In this state, polishing liquid is supplied from the polishing liquid supply nozzle 4 to the surface of the polishing pad 3, and further the surface of the wafer W is pressed against the surface of the polishing pad 3 (i.e., the polishing surface) by the polishing head 1. The surface of the wafer W is polished by sliding contact with the polishing pad 3 in the presence of the polishing liquid. The surface of the wafer W is planarized by the chemical action of the polishing liquid and the mechanical action of the abrasive grains contained in the polishing liquid.

[0020] As shown in FIG. 1, the pad temperature adjustment device 5 includes a heat exchanger 11 capable of contacting the surface of the polishing pad 3 and a liquid supply system 30 for supplying a temperature-adjusted heating liquid and a cooling liquid to the heat exchanger 11. In the present embodiment, the heat exchanger 11 has a substantially triangular shape in a horizontal cross-sectional view. The liquid supply system 30 includes a heating liquid supply tank 31 as a heating liquid supply source for storing the temperature-adjusted heating liquid, and a heating liquid supply pipe 32 and a heating liquid return pipe 33 connecting the heating liquid supply tank 31 and the heat exchanger 11. One end of the heating liquid supply pipe 32 and the heating liquid return pipe 33 is connected to the heating liquid supply tank 31, and the other end is connected to the heat exchanger 11.

[0021] The temperature-adjusted heating liquid is supplied from the heating liquid supply tank 31 to the heat exchanger 11 through the heating liquid supply pipe 32, flows through the heat exchanger 11, and is returned from the heat exchanger 11 to the heating liquid supply tank 31 through the heating liquid return pipe 33. Thus, the heating liquid circulates between the heating liquid supply tank 31 and the heat exchanger 11. The heating liquid supply tank 31 has a heater (not shown), and the heating liquid is heated to a predetermined temperature by the heater.

[0022] A first on-off valve 41 and a first flow control valve 42 are attached to the heating liquid supply pipe 32. The first flow control valve 42 is disposed between the heat exchanger 11 and the first on-off valve 41. The first on-off valve 41 is a valve having no flow rate adjustment function, while the first flow control valve 42 is a valve having a flow rate adjustment function.

[0023] The liquid supply system 30 further includes a coolant supply pipe 51 and a coolant discharge pipe 52 connected to the heat exchanger 11. The coolant supply pipe 51 is connected to a coolant supply source (for example, a cold water supply source) provided in the factory where the polishing apparatus is installed. The coolant is supplied to the heat exchanger 11 through the coolant supply pipe 51, flows through the heat exchanger 11, and is discharged from the heat exchanger 11 through the coolant discharge pipe 52. In one embodiment, the coolant that has flowed through the heat exchanger 11 may be returned to the coolant supply source through the coolant discharge pipe 52.

[0024] A second on-off valve 55 and a second flow control valve 56 are attached to the coolant supply pipe 51. The second flow control valve 56 is disposed between the heat exchanger 11 and the second on-off valve 55. The second on-off valve 55 is a valve having no flow rate adjustment function, while the second flow control valve 56 is a valve having a flow rate adjustment function.

[0025] The pad temperature adjustment device 5 further includes a pad temperature measuring device 39 that measures the surface temperature of the polishing pad 3 (hereinafter sometimes referred to as the pad surface temperature), and a control device 40 that operates the first flow control valve 42 and the second flow control valve 56 based on the pad surface temperature measured by the pad temperature measuring device 39. The first on-off valve 41 and the second on-off valve 55 are normally open. As the pad temperature measuring device 39, a radiation thermometer capable of measuring the surface temperature of the polishing pad 3 non-contact can be used.

[0026] The pad temperature measuring device 39 measures the surface temperature of the polishing pad 3 non - contact and sends the measured value to the control device 40. The control device 40 controls the flow rates of the heating liquid and the cooling liquid by operating the first flow control valve 42 and the second flow control valve 56 based on the measured pad surface temperature so that the pad surface temperature is maintained at a preset target temperature. The first flow control valve 42 and the second flow control valve 56 operate according to the control signal from the control device 40 and adjust the flow rates of the heating liquid and the cooling liquid supplied to the heat exchanger 11. Heat exchange occurs between the heating liquid and the cooling liquid flowing through the heat exchanger 11 and the polishing pad 3, thereby changing the pad surface temperature.

[0027] By such feedback control, the surface temperature of the polishing pad 3 (pad surface temperature) is maintained at a predetermined target temperature. As the control device 40, a PID controller can be used. The target temperature of the polishing pad 3 is determined according to the type of the wafer W or the polishing process, and the determined target temperature is input to the control device 40 in advance.

[0028] In order to maintain the pad surface temperature at a predetermined target temperature, during the polishing of the wafer W, the heat exchanger 11 is moved to a temperature - adjusting position where heat exchange with the polishing pad 3 is possible. In this embodiment, the heat exchanger 11 at the temperature - adjusting position contacts the surface (i.e., the polishing surface) of the polishing pad 3. In this specification, the mode in which the heat exchanger 11 contacts the surface of the polishing pad 3 includes not only the mode in which the heat exchanger 11 directly contacts the surface of the polishing pad 3 but also the mode in which the heat exchanger 11 contacts the surface of the polishing pad 3 with a polishing liquid (slurry) present between the heat exchanger 11 and the surface of the polishing pad 3. The temperature - adjusting position of the heat exchanger 11 may be a position where the heat exchanger 11 is separated from the polishing pad 3 as long as the heat exchanger can exchange heat with the polishing pad 3. In any mode, heat exchange occurs between the heating liquid and the cooling liquid flowing through the heat exchanger 11 and the polishing pad 3, thereby controlling the pad surface temperature.

[0029] As the heating liquid supplied to the heat exchanger 11, warm water is used. When it is desired to raise the surface temperature of the polishing pad 3 more rapidly, silicone oil may be used as the heating liquid. As the cooling liquid supplied to the heat exchanger 11, cold water or silicone oil is used. When silicone oil is used as the cooling liquid, a chiller is connected to the cooling liquid supply pipe 51 as the cooling liquid supply source, and by cooling the silicone oil to 0°C or lower, the polishing pad 3 can be rapidly cooled. As the cold water, pure water can be used. In order to cool the pure water to generate cold water, a chiller may be used as the cooling liquid supply source. In this case, the cold water that has flowed through the heat exchanger 11 may be returned to the chiller through the cooling liquid discharge pipe 52.

[0030] The heating liquid supply pipe 32 and the cooling liquid supply pipe 51 are completely independent pipes. Therefore, the heating liquid and the cooling liquid are supplied to the heat exchanger 11 simultaneously without being mixed. The heating liquid return pipe 33 and the cooling liquid discharge pipe 52 are also completely independent pipes. Therefore, the heating liquid is returned to the heating liquid supply tank 31 without being mixed with the cooling liquid, and the cooling liquid is discharged without being mixed with the heating liquid or returned to the cooling liquid supply source.

[0031] Next, the heat exchanger 11 will be described with reference to FIGS. 2 to 4. FIG. 2 is a schematic plan view showing a heat exchanger according to an embodiment, FIG. 3 is a cross-sectional view showing an example of a flow path formed in the heat exchanger shown in FIG. 2, and FIG. 4 is a cross-sectional view showing another example of a flow path formed in the heat exchanger shown in FIG. 2.

[0032] As shown in Fig. 2, the heat exchanger 11 has a substantially triangular shape in plan view or horizontal cross-sectional view. Specifically, the heat exchanger 11 has a substantially triangular shape with rounded vertices and includes a long side 11a and short sides 11b and 11c. In the present embodiment, the heat exchanger 11 has a substantially isosceles triangular horizontal cross-sectional shape that is line-symmetric with respect to a straight line CL connecting the intersection point CP of the short sides 11b and 11c and the midpoint MP of the long side 11a. Further, the heat exchanger 11 has a shape in which the midpoint MP of the long side 11a protrudes outside a straight line LL connecting both ends of the long side 11a. The straight line LL extends at a right angle to the straight line CL in the horizontal cross-section of the heat exchanger 11. By having such a shape, the heat exchanger 11 can be cleaned in a limited space while maximizing the area of the bottom surface of the heat exchanger 11.

[0033] As shown in Figs. 3 and 4, the heat exchanger 11 has a first flow path 61 and a second flow path 62 formed therein. The first flow path 61 and the second flow path 62 are adjacent to each other (side by side) and extend spirally (in other words, in a turning manner) along the substantially triangular outer shape of the heat exchanger 11.

[0034] The first flow path 61 has two openings 61a and 61b formed at both ends thereof, and the second flow path 62 has two openings 62a and 62b formed at both ends thereof. A heating liquid supply pipe 32 is connected to the opening 61a of the first flow path 61, and a heating liquid return pipe 33 is connected to the opening 61b of the first flow path 61. That is, the first flow path 61 functions as a heating liquid flow path, the opening 61a of the first flow path 61 is the inlet of the heating liquid flow path, and the opening 61b of the first flow path 61 is the outlet of the heating liquid flow path. A coolant supply pipe 51 is connected to the opening 62a of the second flow path 62, and a coolant return pipe 52 is connected to the opening 62b of the second flow path 62. That is, the second flow path 62 functions as a coolant flow path, the opening 62a of the second flow path 62 is the inlet of the coolant flow path, and the opening 62b of the second flow path 62 is the outlet of the coolant flow path.

[0035] In one embodiment, the first flow path 61 may function as a coolant flow path, and the second flow path 62 may function as a heating liquid flow path. In this case, the opening 61a of the first flow path 61 is a coolant inlet, the opening 61b is a coolant outlet, the opening 62a of the second flow path 62 is a heating liquid inlet, and the opening 62b is a heating liquid outlet.

[0036] The openings 61a and 62a are located at the peripheral portion of the heat exchanger 11, and the openings 61b and 62b are located at the central portion of the heat exchanger 11. Therefore, the heating liquid and the coolant flow spirally from the peripheral portion to the central portion of the heat exchanger 11. The heating flow path 61 and the cooling flow path 62 are completely separated, and the heating liquid and the coolant are not mixed within the heat exchanger 11.

[0037] When the wafer W is polished by the polishing apparatus, dirt such as abrasive grains and polishing debris contained in the polishing liquid adheres to the heat exchanger 11 that is in contact with the polishing pad 3. Therefore, the pad temperature adjusting device 5 has a cleaning device that cleans the dirt adhering to the heat exchanger 11. The cleaning device includes a moving mechanism and a cleaning mechanism, which will be described later. The heat exchanger 11 is moved by the moving mechanism from the temperature adjusting position where the heat exchanger 11 can exchange heat with the polishing pad 3 (that is, the temperature adjusting position in direct contact with or close to the surface of the polishing pad 3) to the retracted position where the heat exchanger 11 is located on the side of the polishing pad 3. The cleaning mechanism is at least a mechanism for cleaning the bottom surface of the heat exchanger 11 moved to the retracted position.

[0038] FIG. 5(a) is a schematic plan view showing the state where the heat exchanger 11 is in the temperature adjustment position, and FIG. 5(b) is a schematic plan view showing the state where the heat exchanger 11 shown in FIG. 5(a) has moved to the retracted position. FIG. 6 is a perspective view schematically showing the heat exchanger 11 connected to the moving mechanism according to an embodiment, and FIG. 7 is a schematic cross-sectional view of the moving mechanism shown in FIG. 6. As shown in FIG. 5(b), the retracted position of the heat exchanger 11 is located on the side of the polishing pad 3. When the polishing of the wafer W is completed, the heat exchanger 11 is moved to the retracted position by the moving mechanism shown in FIGS. 6 and 7. The configuration of the moving mechanism is arbitrary as long as it can move the heat exchanger between the temperature adjustment position and the retracted position. Hereinafter, an example of the moving mechanism will be described with reference to FIGS. 6 and 7.

[0039] The moving mechanism 16 shown in FIG. 6 is a mechanism that moves the heat exchanger 11 from the temperature adjustment position where the heat exchanger 11 contacts the surface of the polishing pad 3 upward with respect to the polishing pad 3 and further rotates it to move it to the retracted position. This moving mechanism 16 includes an arm 15 that holds the heat exchanger 11, a shaft 20 fixed to the arm 15, a lifting mechanism 23 that moves the shaft 20 up and down, a rotation mechanism 22 that rotates the shaft 20, and a ball spline bearing 21 that supports the shaft 20 so as to be movable up and down. As shown in FIG. 6, the heat exchanger 11 is connected to one end of the arm 15. The lifting mechanism 23 moves the heat exchanger 11 connected to the arm 15 up and down via the shaft 20 and the arm 15. The shaft 20 shown in FIG. 6 is a spline shaft fixed to the end of the arm 15 opposite to the end where the heat exchanger 11 is fixed.

[0040] In this embodiment, the lifting mechanism 23 is configured as a piston cylinder mechanism. As shown in FIG. 7, the tip of the piston 23a of the lifting mechanism 23 is fixed to the lower end of the joint member 27. The joint member 27 has a recess formed therein, and a bearing 25 for rotatably supporting the lower end of the shaft 20 is disposed on the wall surface of the recess. The lifting mechanism 23 is supplied with a fluid (e.g., compressed air, nitrogen, etc.) for moving the piston 23a up and down from a fluid supply source (not shown). When the fluid is supplied to the lifting mechanism 23, the piston 23a rises, and the shaft 20 is raised via the joint member 27 and the bearing 25. Since the shaft 20 is connected to the arm 15 and the arm 15 is connected to the heat exchanger 11, when the shaft 20 rises, the arm 15 and the heat exchanger 11 rise with respect to the polishing pad 3. When the supply of the fluid to the lifting mechanism 23 is stopped, the piston 23a and the shaft 20 descend, whereby the arm and the heat exchanger 11 are lowered.

[0041] The main body of the ball spline bearing 21 is supported via a bearing 24 by a frame 38 fixed to the polishing apparatus. The rotation mechanism 22 includes an electric motor M1, a first pulley P1 fixed to the shaft 20, a second pulley P2 fixed to the rotation shaft of the electric motor M1, and a belt B1 wound around these pulleys P1 and P2. When the electric motor M1 is driven, the second pulley P2 rotates, and the rotation of the second pulley P2 is transmitted to the first pulley P1 via the belt B1, causing the first pulley P1 to rotate. The side surface of the first pulley P1 is connected to the main body of the ball spline bearing 21. When the first pulley P1 rotates, the ball spline bearing 21 and the shaft 20 rotate, whereby the arm 15 and the heat exchanger 11 rotate with respect to the polishing pad 3. By rotating the rotation shaft of the electric motor M1 in the clockwise or counterclockwise direction, the heat exchanger 11 can be rotated about the shaft 20 so that the heat exchanger 11 approaches or separates from the polishing pad 3.

[0042] When moving the heat exchanger 11 from the temperature adjustment position to the retracted position, first, drive the lifting mechanism 23 of the moving mechanism 16 to move the heat exchanger 11 above the polishing pad 3. Next, drive the rotation mechanism 22 to rotate the heat exchanger 11 to the retracted position on the side of the polishing pad 3. As shown in FIG. 5(b), when the heat exchanger 11 is moved to the retracted position, the longest side 11a of the heat exchanger 11 faces the (outer peripheral edge of) the polishing pad 3. Note that, as shown in FIG. 5(a), when the heat exchanger 11 is in the temperature adjustment position, the longest side 11a of the heat exchanger 11 preferably extends in the radial direction of the polishing pad 3. With such a configuration, the heat exchanger 11 can adjust the temperature over a wide range of the surface of the polishing pad 3.

[0043] FIG. 8(a) is a schematic plan view showing a cleaning tank of a cleaning mechanism for cleaning the heat exchanger 11 moved to the retracted position, and FIG. 8(b) is a schematic side view of the cleaning mechanism having the cleaning tank shown in FIG. 8(a). The cleaning mechanism 65 shown in FIGS. 8(a) and 8(b) includes a cleaning tank 66 in which the bottom surface of the heat exchanger 11 is immersed, a swing mechanism 68 that swings the cleaning tank 66 with respect to the heat exchanger 11 moved to the retracted position, and a connecting shaft 67 that connects the swing mechanism 68 to the cleaning tank 66.

[0044] The cleaning tank 66 has a bottomed cylindrical shape with an open top. A cleaning liquid supply line (not shown) is connected to the cleaning tank 66, and cleaning liquid is supplied to and stored in the cleaning tank 66 through this cleaning liquid supply line. A cleaning liquid discharge line (not shown) is also connected to the cleaning tank 66, and the cleaning liquid used for cleaning the heat exchanger 11 is discharged from the cleaning liquid discharge line. The cleaning liquid supply line is connected to an opening formed in the side wall of the cleaning tank 66, for example. The cleaning liquid discharge line is connected to an opening formed in the bottom wall of the cleaning tank 66, for example.

[0045] The cleaning liquid is, for example, pure water. In one embodiment, the cleaning liquid may be isopropyl alcohol (IPA), or a mixture of pure water and isopropyl alcohol. The cleaning liquid may contain a surfactant.

[0046] The swing mechanism 68 shown in FIG. 8(b) swings the cleaning tank 66 horizontally via the connecting shaft 67 (see, for example, the double-headed arrows in FIG. 8(a)). The configuration of the swing mechanism 68 is arbitrary as long as the cleaning tank 66 can swing relative to the heat exchanger 11. Examples of the swing mechanism 68 include a combination of a servo motor and a gear mechanism (or a ball screw mechanism), and an air cylinder. By swinging the cleaning tank 66 via the connecting shaft 67 by the swing mechanism 68, the cleaning liquid stored in the cleaning tank 66 swings, and thereby the heat exchanger 11 can be efficiently cleaned.

[0047] As shown in FIGS. 5(a) and 5(b), the heat exchanger 11 of the polishing head 1, the polishing pad 3, and the pad temperature adjusting device 5 is disposed in a polishing chamber 80 partitioned by a plurality of partition walls 81. In order to achieve downsizing of the polishing apparatus, when each partition wall 81 is brought closer to the polishing pad 3, the shape of the surplus space formed between the polishing pad 3 having a circular shape in a horizontal cross-sectional view and each partition wall 81 approaches a triangle in a horizontal cross-sectional view. In the present embodiment, since the cleaning tank 66 is provided in this surplus space, the horizontal cross-sectional shape of the heat exchanger 11 is made substantially triangular to maximize the area of the bottom surface of the heat exchanger 11 (that is, the contact surface with the polishing pad 3).

[0048] The bottom surface of the heat exchanger 11 (having a substantially triangular shape) according to the present embodiment has an area approximately half of the area of the bottom surface of the conventional heat exchanger 111 (having a circular shape) shown in FIGS. 15(a) and 15(b). However, according to the experiments of the present inventors, it has been found that the polishing rate of the wafer W when adjusting the temperature of the polishing pad using the heat exchanger 11 according to the present embodiment is substantially the same as the polishing rate of the wafer W when adjusting the temperature of the polishing pad using the conventional heat exchanger 111.

[0049] In this experiment, first, the polishing rate (reference polishing rate) of the wafer W was measured under the condition that the temperature of the polishing pad was not adjusted by the heat exchanger 11 and the heat exchanger 111. Next, with the heat exchanger 11 according to the present embodiment and the conventional heat exchanger 111 maintained at the same temperature (for example, 80°C), the polishing rates when polishing the wafer W were measured respectively.

[0050] When the temperature of the polishing pad was adjusted using the conventional heat exchanger 111, the polishing rate of the wafer W increased by 15% compared to the reference polishing rate. On the other hand, when the temperature of the polishing pad was adjusted using the heat exchanger 11 according to the present embodiment, the polishing rate of the wafer W increased by 13.7% compared to the reference polishing rate. According to this experimental result, although the polishing rate of the wafer W when the temperature of the polishing pad was adjusted using the heat exchanger 11 according to the present embodiment was slightly lower than the polishing rate of the wafer W when the temperature of the polishing pad was adjusted using the conventional heat exchanger 111, it was found that they were almost the same.

[0051] Thus, according to the present embodiment, since the heat exchanger 11 has a substantially triangular shape in a horizontal cross-sectional view, the heat exchanger 11 can be cleaned in the surplus space formed between the partition wall 81 partitioning the polishing chamber 80 and the polishing pad 3. That is, the heat exchanger 11 can be cleaned in the cleaning tank 66 provided in the limited space of the substantially triangular shape.

[0052] When the polishing pad 3 is rotated, undulations may occur on the surface of the polishing pad 3 (i.e., the polishing surface). Further, polishing liquid (slurry) may be allowed to penetrate between the heat exchanger 11 and the surface of the polishing pad 3, and polishing of the wafer W may be performed with the heat exchanger 11 slightly separated from the polishing pad 3. Therefore, the heat exchanger 11 is preferably connected to the arm 15 by a connection mechanism that allows movement of the heat exchanger 11 relative to the arm 15 to such an extent that the heat exchanger 11 can follow the undulations of the polishing surface and to such an extent that the heat exchanger 11 can be separated from the polishing pad 3 by the buoyancy of the polishing liquid. On the other hand, if the movement direction of the heat exchanger 11 relative to the arm 15 is allowed without limitation, when the cleaning tank 66 of the cleaning mechanism 65 swings, the heat exchanger 11 may move freely in the cleaning tank 66 by the cleaning liquid that sways in the cleaning tank 66, and as a result, the components of the connection mechanism may be significantly worn.

[0053] Therefore, the movement mechanism 16 of the pad temperature adjustment device 5 according to the present embodiment has a link mechanism that allows vertical movement of the heat exchanger 11 relative to the arm 15 but restricts horizontal movement of the heat exchanger 11 relative to the arm 15. The heat exchanger 11 is connected to the arm 15 via this link mechanism. Hereinafter, an example of such a link mechanism will be described with reference to FIGS. 9 to 14. However, the configuration of the link mechanism is arbitrary as long as it allows vertical movement of the heat exchanger 11 relative to the arm 15 and can restrict horizontal movement of the heat exchanger 11 relative to the arm 15, and is not limited to this example.

[0054] FIG. 9 is a schematic diagram showing a link mechanism according to an embodiment. FIG. 10 is a simplified diagram of the link mechanism shown in FIG. 9. FIG. 10 is a diagram showing the configuration of the link mechanism shown in FIG. 9 in blocks for easy understanding of the invention. Further, FIG. 10 shows the state of the link mechanism 70 when the heat exchanger 11 is in the temperature adjustment position (i.e., when it is in contact with the surface of the polishing pad 3).

[0055] The link mechanism 70 shown in FIGS. 9 and 10 includes a first link arm 71 connected to one side surface of the arm 15, a second link arm 72 connected to the other side surface of the arm 15, a first link block 74 attached to the upper surface of the first link arm 71, and a second link block 75 attached to the upper surface of the heat exchanger 11. The second link arm 72 is disposed on the side opposite to the first link arm 71 with the arm 15 interposed therebetween. The link mechanism 70 further includes a link rod 77 rotatably supported by the first link block 74 and the second link block 75. The first link block 74 and the second link block 75 support the ends of the link rod 77, respectively. A link protrusion 77a extending downward is formed at the end of the link rod 77 supported by the second link block 75. The link protrusion 77a opposes the upper surface of the second link arm 72. Further, the link mechanism 70 has a stopper 79 located above the first link arm 71 and facing the upper surface of the first link arm 71.

[0056] FIG. 11 is a cross-sectional view taken along line A-A of FIG. 9. As shown in FIGS. 9 and 11, the first link block 74 includes two column members 74a, 74a, a shaft 74b connected to these column members 74a, 74a, and a resin cover 74c covering the outer peripheral surface of the shaft 74b. The link rod 77 has a first through-hole into which the shaft 74b and the resin cover 74c are inserted, and is supported by the first link block 74 so as to be rotatable around the shaft 74b. The diameter of the first through-hole is substantially equal to the outer diameter of the resin cover 74c. Therefore, the movement of the link rod 77 other than the rotation around the shaft 74b of the first link block 74 is restricted.

[0057] FIG. 12 is a cross-sectional view taken along line B-B of FIG. 9. As shown in FIGS. 9 and 12, the second link block 75 includes two column members 75a, 75a, a shaft 75b connected to these column members 75a, 75a, and a resin cover 75c that covers the outer peripheral surface of the shaft 75b. The link bar 77 has a second through-hole into which the shaft 75b and the resin cover 75c are inserted, and is supported by the second link block 75 so as to be rotatable around the shaft 75b. The diameter of the second through-hole is substantially equal to the outer diameter of the resin cover 75c. Therefore, the link bar 77 is restricted from moving other than rotating around the shaft 75b of the second link block 75.

[0058] Next, with reference to FIGS. 10 and 13 to 15, the operation of the link mechanism 70 having such a configuration will be described. FIGS. 13 to 15 are schematic views showing the operation state of the link mechanism, and like FIG. 10, it is a view showing the configuration of the link mechanism 70 in blocks.

[0059] As shown in FIG. 10, when the heat exchanger 11 is in the temperature adjustment position, the link protrusion 77a of the link bar 77 is separated from the second link arm 72. That is, a gap t is formed between the link protrusion 77a and the second link arm 72. Here, as described above with reference to FIGS. 11 and 12, the link bar 77 of the link mechanism 70 is only allowed to rotate with respect to the first link block 74 and the second link block 75. Therefore, the vertical movement of the heat exchanger 11 with respect to the arm 15 via the link mechanism 70 is allowed by the amount of this gap t. This gap t is set such that the heat exchanger 11 can follow the undulation of the polished surface and the heat exchanger 11 can be separated from the polishing pad 3 by the buoyancy of the polishing liquid. The size of the gap t is, for example, several millimeters.

[0060] Next, in order to move the heat exchanger 11 to the retracted position, when the arm 15 and the heat exchanger 11 are lifted by the elevating mechanism 23 (see FIG. 6), the upper surface of the second link arm 72 comes into contact with the protrusion 77a of the link rod 77 (see FIG. 13). After the link protrusion 77a of the second link arm 72 comes into contact with the upper surface of the second link arm 72, when the arm 15 and the heat exchanger 11 are further lifted by the elevating mechanism 23, the second link block 75 rotates with respect to one end of the link rod 77, and the first link block 74 rotates with respect to the other end of the link rod 77, and the heat exchanger 11 separates from the surface of the polishing pad 3 in a state of being inclined with respect to the arm 15. The rotation of the first link block 74 and the second link block 75 with respect to the link rod 77 is blocked by the upper surface of the first link arm 71 coming into contact with the stopper 79 (see FIG. 14).

[0061] In this state, the heat exchanger 11 is moved by the moving mechanism 16 to the cleaning tank 66 of the cleaning mechanism 65 and is cleaned by the cleaning mechanism 65 (see FIGS. 8(a) and 8(b)). As described above, during the cleaning of the heat exchanger 11, the cleaning tank 66 is swung horizontally by the swinging mechanism 68. However, since the horizontal movement of the heat exchanger 11 is blocked by the link mechanism 70, the heat exchanger 11 cannot move horizontally by the action of the cleaning liquid moving in the cleaning tank 66. As a result, while allowing the vertical movement of the heat exchanger 11 with respect to the arm 15, it is possible to prevent the components of the link mechanism 70 that connect the heat exchanger 11 to the arm 15 from being significantly worn.

[0062] The above-described embodiments are described for the purpose of enabling those having ordinary knowledge in the technical field to which the present invention pertains to practice the present invention. Various modifications of the above embodiments are naturally possible for those skilled in the art, and the technical idea of the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is interpreted in the broadest scope in accordance with the technical idea defined by the claims.

Explanation of Reference Numerals

[0063] 1 Grinding head 2 Grinding table 3 Grinding pad 5 Pad temperature adjustment device 11 Heat exchanger 15 Arm 16 Moving mechanism 20 Shaft 21 Ball spline bearing 22 Rotating mechanism 23 Lifting mechanism 40 Control device 65 Cleaning mechanism 66 Cleaning tank 68 Oscillating mechanism 70 Link mechanism 71 First link arm 72 Second link arm 74 First link block 75 Second link block 77 Link rod 79 Stopper

Claims

1. A pad temperature adjustment device for adjusting the surface temperature of a polishing pad, comprising: A heat exchanger that contacts the polishing pad and exchanges heat with the polishing pad; A moving mechanism that moves the heat exchanger between a temperature adjustment position where the heat exchanger can exchange heat with the polishing pad and a retracted position located on the side of the polishing pad; A cleaning mechanism for cleaning the heat exchanger moved to the retracted position. The heat exchanger has a substantially triangular horizontal cross-sectional shape. The longest side of the heat exchanger faces the polishing pad when the heat exchanger moves to the retracted position. The moving mechanism includes: An arm for holding the heat exchanger; A lifting mechanism for lifting and lowering the heat exchanger via the arm; A link mechanism attached to the heat exchanger and connecting the heat exchanger to the arm. The link mechanism allows vertical movement of the heat exchanger with respect to the arm but restricts horizontal movement of the heat exchanger with respect to the arm. The link mechanism includes: A first link arm connected to the arm; A second link arm connected to the arm and disposed on the side opposite to the first link arm with the arm interposed therebetween; A first link block attached to the upper surface of the first link arm; A second link block attached to the upper surface of the heat exchanger; A link bar having both ends rotatably supported by the first link block and the second link block and having a link protrusion extending downward on the end side supported by the second link block. The link protrusion is spaced apart from the upper surface of the second link arm when the heat exchanger is in the temperature adjustment position. The link projection is a pad temperature adjustment device that contacts the upper surface of the second link arm when the heat exchanger is raised by the lifting mechanism.

2. The link mechanism further includes a stopper that prevents the vertical movement of the heat exchanger with respect to the arm. When the heat exchanger is further raised by the lifting mechanism after the link projection contacts the upper surface of the second link arm, the stopper contacts the upper surface of the first link arm. The pad temperature adjustment device according to claim 1.

3. The cleaning mechanism A cleaning tank in which the bottom surface of the heat exchanger is immersed, A swing mechanism that swings the cleaning tank with respect to the heat exchanger. The pad temperature adjustment device according to claim 1 or 2.

4. A polishing device that polishes a substrate by sliding the substrate in contact with a polishing pad, A polishing table that supports the polishing pad, A polishing head that presses the substrate against the polishing pad, A pad temperature adjustment device that adjusts the surface temperature of the polishing pad. The polishing device is provided with The pad temperature adjustment device is the pad temperature adjustment device according to any one of claims 1 to 3. A polishing device.

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