Grinding device and temperature control system

Abstract

To provide a polishing device that can uniformize in-plane temperatures of a wafer while being suppressed from being complicated and suppressing cost increase, and a CMP process temperature control system that can uniformize temperatures of a polishing surface of a polishing plate and in-plane temperatures of a wafer surface, during a CMP process.SOLUTION: In a plate for circulating a cooling medium for cooling a disk-like object to be cooled, a path for circulating a cooling medium at a center region of the object to be cooled and a path for circulating a cooling medium at a peripheral region thereof are formed separately. A ratio of areas in which the cooling medium flowing into the path contacts the plate for circulating the cooling medium to areas of a region of the object to be cooled is set to be larger in the path corresponding to the peripheral region than in the path corresponding to the center region. During polishing of a wafer, temperatures of the object to be cooled are monitored, and the temperatures are controlled so that variations of the temperatures of in-plane temperatures of the object to be cooled are uniformized, on the basis of information on the monitored temperatures.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a polishing apparatus for performing CMP processing and a CMP process temperature control system using the same. In particular, the present invention relates to a polishing apparatus for polishing a semiconductor wafer or the like as an object to be polished, the polishing apparatus including a plate for circulating a cooling medium, and a CMP process temperature control system using the same.

[0002] When forming an element structure or a wiring structure such as a transistor on the surface of various semiconductor wafers such as silicon (Si), silicon carbide (SiC), and gallium nitride (GaN), a pattern defining the region of the element structure or the wiring structure is transferred onto the wafer using an exposure apparatus.

[0003] At this time, if the wafer surface is not flat, the pattern transfer cannot be performed accurately, and abnormalities occur in the finally formed element structure and wiring structure. Therefore, a CMP (chemical mechanical polishing) apparatus is used to realize planarization of the wafer surface.

[0004] In addition, in the manufacturing process of semiconductor devices, structures such as transistor elements and wirings may be laminated on the wafer surface. Also, in the process of forming this laminated structure, a polishing process by CMP processing is performed.

[0005] When performing CMP processing using a CMP apparatus, an abrasive (CMP slurry) is impregnated into a polishing pad, a polishing head holding a wafer is pressed against a polishing plate, and the polishing head and the polishing plate are slid relative to each other while rotating respectively. Thereby, planarization of the wafer surface is realized by utilizing both the effect of mechanical polishing and the chemical reaction by the abrasive (CMP slurry).

[0006] On the other hand, during polishing by a CMP apparatus, heat is generated due to the friction between the wafer and the polishing pad. Both the wafer and the polishing pad are disk-shaped and rotate about their respective centers. Therefore, during polishing, the speed increases toward the outer diameter in the plane of the wafer and the polishing pad, and a large amount of frictional heat is generated.

[0007] Conventionally, in order to suppress heat generation during polishing, cooling water has been flowed through the back surface of the polishing pad to prevent the temperature of the wafer and the polishing pad from rising due to frictional heat.

[0008] However, the frictional force between the wafer and the polishing pad varies due to various factors during polishing. For example, as one of the factors, the diameters of the polishing head and the wafer fixed to the polishing head and the polishing pad are different, and the relative speed between the wafer and the polishing pad constantly varies during the CMP operation. Therefore, it has been difficult to make the temperature in the plane of the wafer and the polishing pad uniform during the polishing process. And the non-uniformity of the temperature in the plane of the wafer and the polishing pad has been a major factor in the deterioration of the flatness of the wafer surface.

[0009] In order to solve such problems, for example, Patent Document 1 discloses a polishing apparatus that divides the region of the polishing pad into a region corresponding to the central portion of the wafer and a region corresponding to the peripheral portion of the wafer, and controls the temperatures of both regions separately.

[0010] Specifically, in a base plate provided on the surface opposite to the polishing surface of the polishing pad, high-temperature cooling water at 20°C is circulated through the region corresponding to the central portion of the wafer, and low-temperature cooling water at 4°C is circulated through the region corresponding to the peripheral portion of the wafer. A polishing apparatus is disclosed that cools the peripheral portion of the wafer with cooling water at a lower temperature than the central portion of the wafer to equalize the temperature in the plane of the wafer.

[0011] In Patent Document 2, a system is also disclosed that monitors the temperature of a wafer or the like during a CMP process and controls the temperature of a polishing plate during the CMP process according to a signal based on that temperature.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0013] However, although Patent Document 1 discloses passing cooling water at a predetermined temperature through regions corresponding to the central portion of the wafer and regions corresponding to the peripheral portion of the wafer, there is no disclosure regarding controlling the temperature of the cooling water according to the temporal temperature variation within the plane of the wafer or the polishing plate.

[0014] Also, in the invention disclosed in Patent Document 1, it is necessary to supply two systems of cooling water, high-temperature cooling water and low-temperature cooling water, from a water supply device to a base plate via the rotation axis of the polishing plate and also circulate them through the water supply device. In order to circulate two types of cooling water with different temperatures, two systems of cooling water circulation paths must be provided within the polishing apparatus, leading to complication of the apparatus and an increase in manufacturing cost.

[0015] Further, although Patent Document 2 discloses a system that monitors the temperature of a wafer or the like during a CMP process and controls the temperature of a polishing plate during the CMP process according to a signal based on that temperature, there is no disclosure regarding controlling the temperature for each region according to the temperature variation within the plane of the polishing plate.

[0016] In view of the above circumstances, the present invention provides a polishing apparatus capable of suppressing temporal temperature fluctuations on the polishing surface of a polishing plate and on the wafer surface during a CMP process, suppressing temperature variations within these surfaces, and achieving uniformization of the in-plane temperature, as well as a CMP process temperature control system using the same. Furthermore, the present invention provides a polishing apparatus capable of suppressing complication of the cooling medium circulation passage from a cooling medium circulation device to the polishing apparatus and an increase in the apparatus manufacturing cost, and achieving uniformization of the in-plane temperature of the wafer surface.

Means for Solving the Problems

[0017] The wafer polishing apparatus according to the present invention is a wafer polishing apparatus including a polishing head unit that holds a wafer in a lower portion and a polishing plate unit having a polishing plate for polishing the wafer held by the polishing head unit, wherein the polishing plate unit includes a cooling medium circulation plate for cooling the polishing plate, which is a disk-shaped object to be cooled, on its lower surface, ッ the cooling medium circulation plate includes a disk-shaped first portion corresponding to a central region of the object to be cooled and having a first path formed therein for circulating a cooling medium for cooling the central region, and an annular second portion corresponding to a peripheral region of the object to be cooled and having a second path formed therein for circulating a cooling medium for cooling the peripheral region, the first path includes a plurality of paths along each of a plurality of concentric circles arranged in the radial direction and a radial path that connects only between any two adjacent paths among the plurality of paths, the second path includes a plurality of paths along each of a plurality of concentric circles arranged in the radial direction and a radial path that connects between any two adjacent paths among the plurality of paths, and the radial path is not connected to at least one of the plurality of paths along each of the plurality of concentric circles arranged in the radial direction of the second path, and the first path and the second path are separated from each other. When a predetermined circle is defined between the outermost circle among the plurality of concentric circles along the first path and the innermost circle among the plurality of concentric circles along the second path, the first portion is an area inside the predetermined circle, the second portion is an area outside the predetermined circle, and it is characterized in that the temperature of the second path is lower than the temperature of the first path.

[0018] Also, the wafer polishing apparatus according to the present invention The second part is divided into a plurality of partial annular shapes, The second path and provided for each of the partial annular parts is characterized by being composed of a plurality of separated paths.

[0019] Also, the wafer polishing apparatus according to the present invention The ratio of the area where the cooling medium flowing through the second path contacts the cooling medium circulation plate to the area of the peripheral region is larger than the ratio of the area where the cooling medium flowing through the first path contacts the cooling medium circulation plate to the area of the central region.

[0020] Also, the wafer polishing apparatus according to the present invention is characterized in that a cooling medium is circulated for each of the first path and the second path using independent cooling medium circulation devices.

[0021] Also, the wafer polishing apparatus according to the present invention is characterized in that a cooling medium is circulated for the first path and the second path using a common cooling medium circulation device.

[0022] Also, the temperature control system according to the present invention the wafer polishing apparatus, and a temperature monitor that monitors the temperature of the object to be cooled during wafer polishing, A control unit is provided that controls the wafer polishing apparatus so as to equalize the temperature variation within the plane of the object to be cooled based on the temperature monitor information output from the temperature monitor.

Advantages of the Invention

[0023] According to the present invention, it is possible to provide a polishing apparatus that can suppress the complication of the cooling medium circulation passage from the cooling medium circulation device to the polishing apparatus and the increase in the device manufacturing cost, and can achieve the equalization of the temperature within the wafer plane. Further, during the CMP process, it is possible to suppress the temporal temperature variation of the polishing surface of the polishing plate and the wafer surface, suppress the temperature variation within these surfaces, and provide a polishing apparatus capable of equalizing the in-plane temperature and a CMP process temperature control system using the same.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0025] FIG. 1 shows a polishing apparatus 1 according to an embodiment of the present invention. The polishing apparatus 1 is used for CMP (Chemical Mechanical Polishing) of a semiconductor wafer. The polishing apparatus 1 is composed of a polishing head unit 2 and a polishing plate unit 3.

[0026] The polishing head unit 2 holds the wafer during the polishing operation, presses the wafer against the polishing pad on the polishing plate, and rotates and further oscillates the wafer. The polishing plate unit 3 is a unit for polishing the wafer with the polishing pad on the polishing plate by rotating the polishing plate.

[0027] First, the details of the polishing head unit 2 will be described. The polishing head unit 2 is composed of a polishing head 10, a wafer holding part 11, a retainer ring 12, and a first cooling medium circulation plate 13 for cooling the wafer.

[0028] The polishing head 10 is the main body part of the polishing head unit 2. The polishing head 10 is provided with a spindle for polishing head rotation at its upper part. Inside the spindle for polishing head rotation, a drive shaft for rotating the polishing head 10 is provided, and the drive shaft is driven by a motor.

[0029] A wafer holding part 11, which is a mechanism for holding the wafer, is provided at the lower part of the polishing head unit 2. For example, a glass plate or a packing pad is used as a member for holding the wafer in the wafer holding part 11.

[0030] When a glass plate is used in the wafer holding part 11, an adhesive such as wax is applied to the opposite side of the polishing surface of the wafer and attached to the glass plate to hold the wafer. When using a packing pad, the wafer is adsorbed and held by the packing pad without using wax.

[0031] The wafer holding part 11 further includes a flexible member, such as a membrane, on the upper side of the glass plate or the packing pad. Thereby, the pressure applied by the chamber inside the polishing head 10 can be absorbed and adjusted.

[0032] An annular retainer ring 12 is provided at the peripheral position of the wafer on the lower surface of the wafer holding portion 11. The retainer ring 12 surrounds and holds the periphery of the wafer which is the object to be polished.

[0033] A first cooling medium circulation plate 13 is provided between the polishing head 10 and the wafer holding portion 11 to cool the wafer. The first cooling medium circulation plate 13 has a structure that forms a plurality of paths for circulating the cooling medium inside it. The cooling medium is circulated by an external cooling medium circulation device. The cooling medium is, for example, water, but other liquids may also be used. The structure of the cooling medium circulation plate 13 will be described later. Also, inside the polishing head, a passage (such as a rotary joint, etc.) is provided to connect between the first cooling medium circulation plate 13 and the cooling medium circulation device to circulate the cooling medium.

[0034] Next, the details of the polishing plate unit 3 will be described. The polishing plate unit 3 is composed of a polishing plate 14, a second cooling medium circulation plate 15 for cooling the polishing plate 14, and a spindle 16 for rotating the polishing plate.

[0035] The polishing plate 14 is a disk-shaped surface plate for polishing the wafer pressed by the polishing head 10. A polishing pad is attached to the upper surface of the polishing plate 14, that is, the surface for polishing the wafer. For example, a polyurethane pad, a non-woven fabric pad, a suede pad, etc. are used for the polishing pad.

[0036] A second cooling medium circulation plate 15 for cooling the polishing plate 14 is provided on the lower surface of the polishing plate 14, that is, on the surface side opposite to the polishing pad. The second cooling medium circulation plate 15 has a structure that forms a plurality of paths for circulating the cooling medium inside it. The cooling medium is supplied from a cooling medium circulation device. The cooling medium is, for example, water, but other liquids may also be used. The structure of the second cooling medium circulation plate 115 will be described later.

[0037] The polishing plate 14 and the second cooling medium circulation plate 15 are supported by a spindle unit 16 for rotating the polishing plate. The spindle unit 16 for rotating the polishing plate has a drive shaft inside for rotating the polishing plate 14 and the second cooling medium circulation plate 15, and the drive shaft is driven by a motor. Inside the spindle unit 16 for rotating the polishing plate, a passage (such as a rotary joint etc.) for circulating the cooling medium between the second cooling medium circulation plate 15 and the cooling medium supply device is provided.

[0038] In the embodiment of the present invention, a polishing apparatus 1 provided with a cooling medium circulation plate in both the polishing head unit 2 and the polishing plate unit 3 is shown, but the polishing apparatus according to the present invention may have a configuration including a cooling medium circulation plate in only one of the polishing head unit 2 and the polishing plate unit 3. That is, the polishing apparatus according to the present invention only needs to be provided with at least one cooling medium circulation plate for cooling a disk-shaped object to be cooled.

[0039] FIG. 2 shows a plan view of the first cooling medium circulation plate 13 and the second cooling medium circulation plate 15 in the embodiment of the present invention. The cooling medium circulation plates 13 and 15 according to the embodiment of the present invention have a disk-shaped first portion 21 corresponding to the central region of a disk-shaped object to be cooled (wafer or polishing plate) and an annular second portion 22 corresponding to the peripheral region.

[0040] In FIG. 2, the first portion 21 is the portion surrounded by the dashed-dotted line 23, and the second portion 22 is the portion between the dashed-dotted line 23 and the dashed-dotted line 24. A first path 201 for circulating the cooling medium for cooling the central region of the object to be cooled is provided in the first portion 21, and a second path 202 for circulating the cooling medium for cooling the peripheral region of the object to be cooled is provided in the second portion 22. The first path 201 and the second path 202 are separated, and the cooling media flowing through them do not merge.

[0041] The first path 201 is composed of an inner annular path 241, an outer annular path 242, and a plurality of radially extending paths connecting these two annular paths. The first path 201 is also provided with an injection port 243 for injecting a cooling medium and a discharge port 244 for discharging the cooling medium.

[0042] The cooling medium circulation plate shown in FIG. 2 is provided with one injection port and one discharge port on the first path 201, respectively, but any number of each may be provided. Also, the installation locations may be any locations on the first path 201. When a plurality of injection ports and discharge ports are provided respectively, arranging them at equal intervals on the first path 201 makes it easier to achieve a more uniform temperature distribution. Also, by arranging the injection port on the inner annular path 241, the flow rate of the cooling medium can be increased by utilizing centrifugal force, and the cooling efficiency can be further enhanced.

[0043] The second path 202 is composed of a plurality of paths along a plurality of concentric circles 251 arranged radially and a plurality of radially extending paths connecting the paths on those concentric circles 251. The second path 201 is also provided with an injection port 253 for injecting a cooling medium and a discharge port 254 for discharging the cooling medium. When the cooling medium circulation plate rotates, a centrifugal force is applied to the cooling medium toward the radially outer side, but the plurality of paths along the concentric circles 251 serve as stoppers to prevent the cooling medium from immediately moving radially outward. The cooling medium has a structure in which it moves circumferentially on the paths along the concentric circles 251 and then moves radially along the plurality of radially extending paths.

[0044] The cooling medium circulation plate shown in Fig. 2 is provided with two inlets 253 and four outlets 254 on the second path 202, but any number of each can be provided. Also, the installation location can be any location on the second path 202. When a plurality of inlets 253 and outlets 254 are provided respectively, by arranging them at equal intervals on the second path 202, it becomes easier to achieve a more uniform temperature distribution. Also, by arranging the inlet on the path along the innermost concentric circle 251, the flow of the cooling medium can be accelerated using centrifugal force, and the cooling efficiency can be further enhanced.

[0045] The first path 201 and the second path 202 are separated. Therefore, by independently controlling the temperature, flow rate, etc. of the cooling medium flowing through the first path 201 and the second path 202, the cooling efficiency for the central region and the peripheral region of the object to be cooled can be freely adjusted.

[0046] For example, it can be realized by preparing a plurality of cooling medium circulation devices (for example, a chiller water circulation device), providing a plurality of independent cooling medium circulation passages corresponding to the first path 201 and the second path 202 inside the spindle unit 16 for polishing plate rotation and the polishing head 10, and circulating the cooling medium using independent cooling medium circulation devices for each.

[0047] Regarding the first cooling medium circulation plate 13 and the second cooling medium circulation plate 15 according to the embodiment of the present invention, the ratio of the area of the cooling medium flowing through the second path 202 that contacts the cooling medium circulation plate to the area of the peripheral region of the object to be cooled is larger than the ratio of the area of the cooling medium flowing through the first path 201 that contacts the cooling medium circulation plate to the area of the central region of the object to be cooled. Such a structure may be adopted.

[0048] That is, when the areas of the central region and the peripheral region of the object to be cooled are SA1 and SA2 respectively, and the areas where the cooling medium flowing through the first path 201 and the second path 202 contact the cooling medium circulation plate are SB1 and SB2 respectively, the structure is such that SB2 / SA2 is larger than SB1 / SA1.

[0049] Also, if the cross-sectional shape in the thickness direction of the cooling medium circulation plates of the first path 201 and the second path 202 is the same throughout the paths, when the length of the first path 201 is L1 and the length of the second path 202 is L2, a structure may be adopted such that L2 / SA2 is larger than L1 / SA1.

[0050] The cooling medium absorbs heat more efficiently from the outside as the area of the surface in contact with the outside increases. Therefore, by making the ratio of the area where the cooling medium flowing through the second path 202 contacts the cooling medium circulation plate to the area of the peripheral region of the object to be cooled larger than the ratio of the area where the cooling medium flowing through the first path 201 contacts the cooling medium circulation plate to the area of the central region of the object to be cooled, even when a common cooling medium is supplied to the first path 201 and the second path 202 from one cooling medium circulation device, the peripheral region of the object to be cooled can be cooled more efficiently without individually controlling the temperature, flow rate, etc. of the cooling medium flowing through the first path 201 and the second path 202.

[0051] Thereby, it is possible to provide a polishing apparatus that suppresses the complication of the cooling medium circulation path, suppresses an increase in the manufacturing cost of the apparatus, and supplies the cooling medium in a simple configuration that can achieve uniformization of the temperature within the wafer surface.

[0052] Note that the cooling medium circulation plate shown in FIG. 2 may be made of a ceramic material with a low coefficient of thermal expansion and arranged directly below the polishing plate. Thereby, since a shape change due to heat can be suppressed, higher-precision planarization can be realized.

[0053] Alternatively, the first part 21 and the second part 22 may be formed as separate bodies and a combination thereof may be used. Also, different ceramic materials may be used for the first part 21 and the second part 22 respectively. By using a ceramic material having a higher thermal conductivity for the second part 22, the peripheral region of the object to be cooled can be cooled more efficiently. Also, not limited to the ceramic material, the same effect can be obtained by using a material having a higher thermal conductivity for the second part 22.

[0054] Furthermore, the first cooling medium circulation plate 13 and the second cooling medium circulation plate 15 in the embodiment of the present invention may have the structure shown in FIG. 3.

[0055] The first cooling medium circulation plate 13 and the second cooling medium circulation plate 15 having the structure shown in FIG. 3 have a disk-shaped first part 31 corresponding to the central region of a disk-shaped object to be cooled (wafer or polishing plate), and an annular second part 32 corresponding to the peripheral region. Also, the second part 32 is composed of a third part 323, a fourth part 324, and a fifth part 325.

[0056] In FIG. 3, the first part 31 is the part surrounded by the dashed-dotted line 34, and the second part 32 is the part between the dashed-dotted line 34 and the dashed-dotted line 35. The third part 323, the fourth part 324, and the fifth part 325 are respectively the parts obtained by dividing the part between the dashed-dotted line 34 and the dashed-dotted line 35 into three partial annular shapes. The boundary between the third part 323 and the fourth part 324 is shown by a dashed-dotted line 36, the boundary between the fourth part 324 and the fifth part 325 is shown by a dashed-dotted line 37, and the boundary between the fifth part 325 and the third part 323 is shown by a dashed-dotted line 38.

[0057] In the first part 31, a first path 301 for circulating a cooling medium to cool the central region of the object to be cooled is provided, and in the second part 32, a second path 302 for circulating a cooling medium to cool the peripheral region of the object to be cooled is provided. The first path 301 and the second path 302 are separated, and the cooling media flowing through them do not merge. The second path 302 is further composed of a plurality of separated paths. Specifically, the second path 302 consists of a third path 333 provided in the third part 323, a fourth path 334 provided in the fourth part 324, and a fifth path 335 provided in the fifth part 325. In FIG. 3, the annular second part 32 is divided into three partial annular parts, and the second path 302 is divided into three paths for each of the partial annular parts. However, the number of the divided partial annuli and paths may be two or more, and is not limited to three.

[0058] The first path 301 is composed of three concentric annular paths 341 and two paths extending in the radial direction connecting these annular paths. In addition, an injection port 343 for injecting a cooling medium and a discharge port 344 for discharging the cooling medium are provided in the first path 301.

[0059] On the cooling medium circulation plate shown in FIG. 3, one injection port and one discharge port are respectively provided on the first path 301, but any number of them may be provided respectively. Also, the installation positions may be any positions on the first path 301. When a plurality of injection ports and discharge ports are provided respectively, by arranging them at equal intervals on the third path 301, it becomes easier to achieve a more uniform temperature distribution. In addition, by arranging the injection port on the inner annular path, the flow of the cooling medium can be accelerated by utilizing centrifugal force, and the cooling efficiency can be further improved.

[0060] The third path 333, the fourth path 334, and the fifth path 335 that constitute the second path 302 are each composed of a plurality of paths along a plurality of concentric circles 351 arranged radially and a plurality of radially extending paths connecting between the plurality of paths on those concentric circles 351. The cooling medium flowing through the third path 333, the fourth path 334, and the fifth path 335 does not merge with the cooling medium flowing through any other path on the way. That is, the third path 333, the fourth path 334, and the fifth path 335 are separated. In addition, an injection port 353 for injecting the cooling medium and a discharge port 354 for discharging the cooling medium are provided for each of the third path 333, the fourth path 334, and the fifth path 335. When the cooling medium circulation plate rotates, a centrifugal force is applied to the cooling medium toward the outside in the radial direction, but the plurality of paths along the concentric circles 351 serve as stoppers to prevent the cooling medium from immediately moving to the outside in the radial direction. The cooling medium has a structure that moves circumferentially along the paths along the concentric circles 351 and then moves radially along the plurality of radially extending paths.

[0061] The cooling medium circulation plate shown in FIG. 3 is provided with one injection port and one discharge port on each of the third path 333, the fourth path 334, and the fifth path 335, but any number can be provided. Also, the installation location may be any location on the third path 333, the fourth path 334, and the fifth path 335. When a plurality of injection ports and discharge ports are provided respectively, by arranging them at equal intervals on the paths of the third path 333, the fourth path 334, and the fifth path 335, it becomes easier to achieve a more uniform temperature distribution. Also, by arranging the injection port on the inner annular path, the flow rate of the cooling medium can be increased by utilizing the centrifugal force, and the cooling efficiency can be further enhanced.

[0062] The first path 301 and the second path 302 are separated, and since the third path 303, the fourth path 304, and the fifth path 305 that constitute the second path 302 are also separated, the cooling efficiency of these paths can be independently adjusted by independently controlling the temperature, flow rate, etc. of the cooling medium flowing through the first path 301, the third path 333, the fourth path 334, and the fifth path 335.

[0063] For example, a plurality of cooling medium circulation devices (e.g., a chiller water circulation device) are prepared, and independent cooling medium circulation passages corresponding to the first path 301, the third path 333, the fourth path 334, and the fifth path 335 are provided inside the spindle unit 16 for rotating the polishing plate and the polishing head 10, and the cooling medium is circulated using an independent cooling medium circulation device for each of them, which can be realized.

[0064] That is, during polishing, since the temperature on the outer peripheral side of the wafer or the polishing plate, which is the object to be cooled, tends to increase, by setting the temperature of the cooling medium circulated through the third path 333, the fourth path 334, and the fifth path 335 to be lower than the temperature of the cooling medium circulated through the first path 301, the outer peripheral side of the object to be cooled, which tends to have a high temperature, can be efficiently cooled. Similarly, by setting the flow rate of the cooling medium circulated through the third path 333, the fourth path 334, and the fifth path 335 to be faster than the flow rate of the cooling medium circulated through the first path 301, the outer peripheral side of the object to be cooled, which tends to have a high temperature, can be efficiently cooled. As a result, the temperature distribution within the wafer surface can be made uniform, leading to an improvement in the flatness of the wafer.

[0065] Regarding the first cooling medium circulation plate 13 and the second cooling medium circulation plate 15 according to the embodiment of the present invention, the ratio of the area where the cooling medium flowing through the second path 302 contacts the cooling medium circulation plate to the area of the peripheral region of the object to be cooled may be made larger than the ratio of the area where the cooling medium flowing through the first path 301 contacts the cooling medium circulation plate to the area of the central region of the object to be cooled.

[0066] That is, when the areas of the central region and the peripheral region of the object to be cooled are SA1 and SA2, respectively, and the areas where the cooling medium flowing through the first path 301 and the second path 302 contact the cooling medium circulation plate are SB1 and SB2, respectively, the structure is such that SB2 / SA2 is larger than SB1 / SA1.

[0067] Also, if the cross-sectional shape in the thickness direction of the cooling medium circulation plates of the first path 301 and the second path 302 is the same throughout the paths, when the length of the first path 301 is L1 and the length of the second path 302 is L2, a structure may be adopted such that L2 / SA2 is larger than L1 / SA1.

[0068] Also, with respect to the areas of the regions corresponding to the third portion 323, the fourth portion 324, and the fifth portion 325 among the peripheral regions of the object to be cooled, the respective ratios of the areas where the cooling medium flowing through the third path 333, the fourth path 334, and the fifth path 335 contacts the cooling medium circulation plate may be set to be larger than the ratio of the area where the cooling medium flowing through the first path 301 contacts the cooling medium circulation plate with respect to the area of the first region 301.

[0069] That is, when the areas of the regions corresponding to the third portion 323, the fourth portion 324, and the fifth portion 325 among the peripheral regions of the object to be cooled are SA3, SA4, and SA5 respectively, and the areas where the cooling medium flowing through the third path 333, the fourth path 334, and the fifth path 335 contacts the cooling medium circulation plate are SB3, SB4, and SB5 respectively, a structure is adopted such that SB3 / SA3, SB4 / SA4, and SB5 / SA5 are larger than SB1 / SA1.

[0070] Also, if the cross-sectional shape in the thickness direction of the cooling medium circulation plates of the third path 333, the fourth path 334, and the fifth path 335 is the same throughout the paths, when the length of the third path 333 is L3, the length of the fourth path 334 is L4, and the length of the fifth path 335 is L5, a structure may be adopted such that L3 / SA3, L4 / SA4, and L5 / SA5 are larger than L1 / SA1.

[0071] The larger the area of the cooling medium in contact with the outside, the more efficiently it absorbs heat from the outside. Therefore, the ratio of the area of the cooling medium flowing through the third path 333, the fourth path 334, and the fifth path 335 in contact with the cooling medium circulation plate to the areas of the regions corresponding to the third portion 323, the fourth portion 324, and the fifth portion 325 in the peripheral region of the object to be cooled is larger than the ratio of the area of the cooling medium flowing through the first path 301 in contact with the cooling medium circulation plate to the area of the first region 301. With such a structure, even when a common cooling medium is supplied from one cooling medium circulation device to the first path 301, the third path 333, the fourth path 334, and the fifth path 335, the peripheral regions of the objects to be cooled corresponding to the third portion 323, the fourth portion 323, and the fifth portion 325 can be cooled more efficiently without individually controlling the temperature, flow rate, etc. of the cooling medium flowing through the first path 301, the third path 333, the fourth path 334, and the fifth path 335.

[0072] Thereby, it is possible to provide a polishing apparatus that supplies a cooling medium to the back surface of the polishing plate or the polishing head in a simple configuration that suppresses the complication of the cooling medium circulation path and suppresses an increase in the manufacturing cost of the apparatus, and that can achieve uniformization of the temperature within the wafer surface.

[0073] Note that the cooling medium circulation plate shown in FIG. 3 may be made of a ceramic material with a low coefficient of thermal expansion and may be disposed directly below the polishing plate. Since this can suppress shape changes due to heat, more accurate polishing can be achieved.

[0074] Also, the first portion 301 and the second portion 302 may be formed separately and combined. For example, different ceramic materials may be used for the first portion 301 and the second portion 302. By using a ceramic material having a higher thermal conductivity for the second portion 302, the peripheral region of the object to be cooled can be cooled more efficiently. Also, not limited to ceramic materials, the same effect can be obtained by using a material having a higher thermal conductivity for the second portion 302.

[0075] Figure 4 shows a CMP process temperature control system 4 using the polishing apparatus according to the embodiment of the present invention. The CMP process temperature control system 4 includes a polishing apparatus 1, a cooling medium circulation apparatus 44, a control unit 48, and a temperature monitor 47.

[0076] The polishing apparatus 1 includes the polishing head unit 2 and the polishing plate unit 3 which have been described above. The drive shaft 42 is the drive shaft of the spindle 16 for rotating the polishing plate and serves as the rotation axis of the polishing plate 14. The motor 43 is a power source for rotationally driving the drive shaft 42. The drive shaft 41 is the drive shaft of the polishing head 10 and serves as the rotation axis of the polishing head 10. The motor 40 is a power source for rotationally driving the drive shaft 41.

[0077] The cooling medium circulation apparatus 44 is a device for circulating the cooling medium through the first cooling medium circulation plate 13 and the second cooling medium circulation plate 15. The cooling medium circulation apparatus 44 is a single device and may circulate the cooling medium through the first cooling medium circulation plate 13 and the second cooling medium circulation plate 15. Also, a plurality of devices may be provided to circulate the cooling medium individually for each cooling medium circulation plate. Further, the cooling medium may be circulated through a plurality of separated paths in the cooling medium circulation plate by a common device, or a plurality of devices may be provided to circulate the cooling medium individually for each path.

[0078] The cooling medium circulation passage 46 is a passage for circulating the cooling medium between the first cooling medium circulation plate 13 and the cooling medium circulation apparatus 44. Also, the cooling medium circulation passage 45 is a passage for circulating the cooling medium between the second cooling medium circulation plate 15 and the cooling medium circulation apparatus 44.

[0079] The temperature monitor 47 is, for example, an infrared radiation thermometer, which is installed above the polishing plate and monitors the temperature of the polishing surface of the polishing plate during the CMP process. Also, a temperature monitor may be provided in the polishing head unit 2 to monitor the temperature of the wafer surface. The temperature may be monitored constantly or intermittently during the CMP process. The temperature monitor 47 transmits temperature monitor information, which is information regarding the temperature variation within the plane of the polishing surface of the polishing plate or the wafer surface, to the control unit 46.

[0080] The control unit 48 is a device that controls the overall operation of the polishing apparatus 1 and transmits and receives signals to and from the motors 40 and 43, the cooling medium circulation device 44, and the temperature monitor 47. For example, based on the information regarding the temperature variation within the plane of the polishing surface of the polishing plate sent from the temperature monitor 47, a signal for equalizing the temperature variation within the plane of the polishing surface of the polishing plate or the wafer surface is sent to the cooling medium circulation device 44 to control the temperature and flow rate of the cooling medium. Signals may also be sent to the motors 40 and 43 to control the rotational speed of the polishing plate and the polishing head.

[0081] The control unit 48 can be realized by computer hardware or a combination of computer hardware and software. The software is stored in a non-transitory storage medium as a program for executing predetermined processes and may be executed by a CPU within the computer hardware.

[0082] As described above, it is possible to perform more precise temperature control and temperature management by more precisely controlling the temperature fluctuations that change as the CMP process of the semiconductor wafer progresses.

Description of Reference Numerals

[0083] 1 Polishing Apparatus 2 Polishing Head Unit 3 Polishing Plate Unit 4 CMP Process Temperature Control Unit 10 Polishing Head 11 Wafer Holding Portion 12 Retainer Ring 13 First Cooling Medium Circulation Plate 14 Polishing Plate 15 Second Cooling Medium Circulation Plate 16 Spindle for Polishing Plate Rotation 21, 31 First Part 22, 32 Second Part 23, 24, 34, 35, 36, 37, 38 Dashed-Dotted Line 47 Temperature Monitor 48 Control Unit 44 Cooling Medium Circulation Device 40, 43 Motor 41, 42 Drive Shaft 45, 46 Cooling Medium Circulation Path 201, 301 First Route 202, 302 Second Route 241 Inner Circular Path 242 Outer Circular Path 243, 253, 343, 353 Inlet 244, 254, 344, 354 Outlet 251, 351 Concentric Circles 323 Third Part 324 Fourth Part 325 Fifth Part 333 Third Route 334 Fourth Route 335 Fifth Route 341 Circular Ring Path

Claims

1. A wafer polishing apparatus comprising a polishing head unit that holds a wafer at a lower portion, and a polishing plate unit having a polishing plate for polishing the wafer held by the polishing head unit, wherein the polishing plate unit includes a cooling medium circulation plate for cooling the polishing plate, which is a disk-shaped object to be cooled, on its lower surface, the cooling medium circulation plate has a disk-shaped first portion corresponding to a central region of the object to be cooled and having a first path formed therein for circulating a cooling medium for cooling the central region, and an annular second portion corresponding to a peripheral region of the object to be cooled and having a second path formed therein for circulating a cooling medium for cooling the peripheral region, the first path includes a plurality of paths along each of a plurality of concentric circles arranged in the radial direction, and a radial path that connects only between any two adjacent paths among the plurality of paths, the second path includes a plurality of paths along each of a plurality of concentric circles arranged in the radial direction, and a radial path that connects between any two adjacent paths among the plurality of paths, and the radial path is not connected to at least one of the plurality of paths along each of the plurality of concentric circles arranged in the radial direction of the second path, the first path and the second path are separated, when a predetermined circle is defined between the outermost circle among the plurality of concentric circles along which the first path extends and the innermost circle among the plurality of concentric circles along which the second path extends, the first portion is a region inside the predetermined circle, the second portion is a region outside the predetermined circle, and the wafer polishing apparatus is characterized in that the temperature of the second path is lower than the temperature of the first path.

2. The wafer polishing apparatus according to claim 1, wherein the second portion is divided into a plurality of partial annular shapes, and the second path is composed of a plurality of separated paths provided for each of the partial annular portions.

3. The wafer polishing apparatus according to claims 1 to 2, A wafer polishing apparatus, characterized in that a ratio of an area where a cooling medium flowing through the second path contacts the cooling medium circulation plate to an area of the peripheral region is larger than a ratio of an area where a cooling medium flowing through the first path contacts the cooling medium circulation plate to an area of the central region.

4. The wafer polishing apparatus according to claims 1 to 2, characterized in that a cooling medium is circulated for each of the first path and the second path by using an independent cooling medium circulation device.

5. The wafer polishing apparatus according to claim 3, characterized in that a cooling medium is circulated for the first path and the second path by using a common cooling medium circulation device.

6. The wafer polishing apparatus according to claim 1, a temperature monitor for monitoring a temperature of the object to be cooled during wafer polishing, and a temperature control system including a control unit for controlling the wafer polishing apparatus so as to equalize temperature variations in the plane of the object to be cooled based on temperature monitor information output from the temperature monitor.

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