阅读说明：本技术 垫温度调节装置、垫温度调节方法及研磨装置 (Pad temperature adjusting device, pad temperature adjusting method and grinding device ) 是由 鱼住修司 丸山徹 于 2021-05-07 设计创作，主要内容包括：提供一种垫温度调节装置,能够提高研磨垫的表面温度的控制响应性,并且能够不在基板产生划痕等缺陷和污染地调节该研磨垫的表面温度。垫温度调节装置(5)具备：热交换器(11),该热交换器配置于研磨垫(3)的上方,并且被维持在规定的温度；垫温度测定器(39),该垫温度测定器对研磨垫(3)的表面温度进行测定；距离传感器(14),该距离传感器对研磨垫(3)与热交换器(11)之间的间隔距离进行测定；上下移动机构(71),该上下移动机构使热交换器(11)相对于研磨垫(3)进行上下移动；以及控制装置(40),该控制装置基于垫温度测定器(39)的测定值来控制上下移动机构(71)的动作。(Provided is a pad temperature adjusting device capable of improving control responsiveness of a surface temperature of a polishing pad and adjusting the surface temperature of the polishing pad without causing defects such as scratches and contamination on a substrate. The pad temperature adjusting device (5) is provided with: a heat exchanger (11) which is disposed above the polishing pad (3) and is maintained at a predetermined temperature; a pad temperature measuring device (39) for measuring the surface temperature of the polishing pad (3); a distance sensor (14) for measuring the distance between the polishing pad (3) and the heat exchanger (11); an up-and-down moving mechanism (71) that moves the heat exchanger (11) up and down relative to the polishing pad (3); and a control device (40) for controlling the operation of the vertical movement mechanism (71) based on the measurement value of the pad temperature measuring device (39).)

1. A pad temperature adjusting device for adjusting a surface temperature of a polishing pad to a predetermined target temperature, the pad temperature adjusting device comprising:

a heat exchanger disposed above the polishing pad and maintained at a predetermined temperature;

a pad temperature measuring device for measuring a surface temperature of the polishing pad;

at least one distance sensor for measuring a distance separating the polishing pad and the heat exchanger;

an up-down moving mechanism that moves the heat exchanger up and down with respect to the polishing pad; and

and a control device for controlling the operation of the vertical movement mechanism based on the measurement value of the pad temperature measuring device.

2. The mat temperature conditioning device of claim 1,

the heat exchanger includes a heating flow path formed inside the heat exchanger,

the heating liquid maintained at a predetermined temperature is supplied to the heating flow path at a predetermined flow rate.

3. Pad temperature conditioning device according to claim 1 or 2,

further comprises a cooling mechanism for cooling the surface of the polishing pad,

the control device may operate the cooling mechanism when the target temperature is lower than a measurement value of the pad temperature measuring device after the vertical movement mechanism reaches an upper limit of movement of the heat exchanger.

4. Pad temperature conditioning device according to claim 3,

the cooling mechanism is formed inside the heat exchanger and includes a cooling flow path to which a cooling fluid is supplied,

the control device controls the flow rate of the cooling fluid based on the measurement value of the pad temperature measuring device.

5. Pad temperature conditioning device according to claim 1 or 2,

the control device is provided with:

a storage unit that stores a learning completion model constructed by machine learning using training data including at least a combination of a distance between the heat exchanger and the polishing pad and a temperature of a surface of the polishing pad corresponding to the distance; and

and a processing device that inputs temperature control parameters including at least the target temperature and a measurement value of the pad temperature measuring device into the learning completion model, and performs calculation for outputting an operation amount of the vertical movement mechanism.

6. A pad temperature adjusting method for adjusting a surface temperature of a polishing pad to a predetermined target temperature,

the surface temperature of the polishing pad was measured,

the heat exchanger, which is disposed above the polishing pad and maintained at a predetermined temperature, is moved up and down with respect to the polishing pad in accordance with the surface temperature of the polishing pad, thereby adjusting the surface temperature of the polishing pad to the target temperature.

7. The mat temperature adjusting method according to claim 6,

in order to maintain the heat exchanger at the predetermined temperature, a heating liquid maintained at the predetermined temperature is supplied at a predetermined flow rate to a heating flow path formed inside the heat exchanger.

8. The mat temperature adjusting method according to claim 6 or 7,

and cooling the surface of the polishing pad by using a cooling mechanism when the target temperature is lower than a measurement value of a pad temperature measuring device for measuring the surface temperature of the polishing pad after the heat exchanger reaches an upper limit of movement.

9. The mat temperature adjusting method according to claim 8,

the step of cooling the surface of the polishing pad is a step of controlling a flow rate of the cooling fluid flowing through a cooling channel formed inside the heat exchanger based on a measurement value of the pad temperature measuring device.

10. The mat temperature adjusting method according to claim 6 or 7,

constructing a learning completion model by machine learning using training data including at least a combination of a distance between the heat exchanger and the polishing pad and a temperature of a surface of the polishing pad corresponding to the distance,

temperature control parameters including at least the target temperature and a measurement value of the mat temperature measuring device are input to the learning completion model, and the learning completion model is caused to output an operation amount of the vertical movement mechanism.

11. A polishing apparatus is characterized by comprising:

a polishing table supporting a polishing pad;

a polishing head for pressing a substrate against the polishing pad;

a pad temperature measuring device for measuring a surface temperature of the polishing pad; and

the mat temperature conditioning device of any one of claims 1 to 5.

Technical Field

The present invention relates to a pad temperature adjusting apparatus and a pad temperature adjusting method for adjusting a surface temperature of a polishing pad used for polishing a substrate such as a wafer. The present invention also relates to a polishing apparatus incorporating the pad temperature control device.

Background

A polishing apparatus is known which holds a substrate such as a wafer on a polishing head, rotates the substrate, and further presses the substrate against a polishing pad on a rotating polishing table to polish the surface of the substrate. In the polishing process of the substrate, a polishing liquid (e.g., 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 the abrasive grains contained in the polishing liquid.

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

In contrast, a pad temperature control device that controls the surface temperature of a polishing pad has been conventionally used (see, for example, patent documents 1 and 2). Generally, a mat temperature control device includes: a heat exchanger which can be brought into contact with a surface (polishing surface) of the polishing pad; a liquid supply system that supplies the temperature-adjusted heating liquid and cooling liquid to the heat exchanger; a pad temperature measuring device for measuring a surface temperature of the polishing pad; and a control device for controlling the liquid supply system based on the measured value of the pad temperature measuring device. The control device controls the flow rates of the heating liquid and the cooling liquid so as to maintain the surface temperature of the polishing pad at a predetermined target temperature, based on the pad surface temperature measured by the pad temperature measuring device.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-148933

Patent document 2: japanese patent laid-open publication No. 2018-027582

Technical problem to be solved by the invention

However, since the heat exchanger of the pad temperature control device inevitably comes into contact with the polishing liquid during the polishing of the substrate, dirt such as abrasive grains contained in the polishing liquid and abrasive powder of the polishing pad adheres to the heat exchanger. When the dirt falls from the heat exchanger during the polishing of the substrate, the substrate may be contaminated, and defects such as scratches may be generated on the substrate.

Further, the conventional control method of the mat temperature adjusting apparatus is a complicated control method because the two opposite parameters, that is, the flow rate of the heating liquid and the flow rate of the cooling liquid, are controlled at the same time. Therefore, it is desired to more simply control the surface temperature of the polishing pad, thereby improving the control responsiveness of the surface temperature of the polishing pad.

Disclosure of Invention

Accordingly, an object of the present invention is to provide a pad temperature adjusting apparatus and a pad temperature adjusting method capable of improving control responsiveness of a surface temperature of a polishing pad and adjusting the surface temperature of the polishing pad without causing defects such as scratches and contamination on a substrate. It is another object of the present invention to provide a polishing apparatus incorporating such a pad temperature adjusting apparatus.

Means for solving the problems

In one aspect, there is provided a pad temperature adjusting device for adjusting a surface temperature of a polishing pad to a predetermined target temperature, the pad temperature adjusting device including: a heat exchanger disposed above the polishing pad and maintained at a predetermined temperature; a pad temperature measuring device for measuring a surface temperature of the polishing pad; at least one distance sensor for measuring a distance separating the polishing pad and the heat exchanger; an up-down moving mechanism that moves the heat exchanger up and down with respect to the polishing pad; and a control device for controlling the operation of the vertical movement mechanism based on the measured value of the pad temperature measuring device.

In one aspect, the heat exchanger includes a heating flow path formed inside the heat exchanger, and the heating liquid maintained at a predetermined temperature is supplied to the heating flow path at a predetermined flow rate.

In one aspect, the polishing apparatus further includes a cooling mechanism that cools a surface of the polishing pad, and the control device operates the cooling mechanism when the target temperature is lower than a measurement value of the pad temperature measuring device after the vertical movement mechanism reaches an upper limit of movement of the heat exchanger.

In one aspect, the cooling mechanism is formed inside the heat exchanger, and includes a cooling flow path to which a cooling fluid is supplied, and the control device controls a flow rate of the cooling fluid based on a measurement value of the pad temperature measuring device.

In one aspect, the control device includes: a storage unit that stores a learning completion model constructed by machine learning using training data including at least a combination of a distance between the heat exchanger and the polishing pad and a temperature of a surface of the polishing pad corresponding to the distance; and a processing device that inputs temperature control parameters including at least the target temperature and a measurement value of the pad temperature measuring device into the learning completion model, and performs calculation for outputting an operation amount of the vertical movement mechanism.

In one aspect, a pad temperature adjusting method is provided, in which a surface temperature of a polishing pad is adjusted to a predetermined target temperature, the surface temperature of the polishing pad is measured, and a heat exchanger disposed above the polishing pad and maintained at a predetermined temperature is moved up and down with respect to the polishing pad in accordance with the surface temperature of the polishing pad, thereby adjusting the surface temperature of the polishing pad to the target temperature.

In one aspect, the heating liquid maintained at the predetermined temperature is supplied at a predetermined flow rate to a heating flow path formed inside the heat exchanger in order to maintain the heat exchanger at the predetermined temperature.

In one aspect, the method further includes cooling the surface of the polishing pad using a cooling mechanism when the target temperature is lower than a measurement value of a pad temperature measuring device that measures a surface temperature of the polishing pad after the heat exchanger reaches an upper limit of movement.

In one aspect, the step of cooling the surface of the polishing pad is a step of controlling a flow rate of the cooling fluid flowing through a cooling channel formed inside the heat exchanger based on a measurement value of the pad temperature measuring device.

In one aspect, a learning completion model is constructed by machine learning using training data including at least a combination of a distance between the heat exchanger and the polishing pad and a temperature of the surface of the polishing pad corresponding to the distance, a temperature control parameter including at least the target temperature and a measurement value of the pad temperature measuring device is input to the learning completion model, and the learning completion model is caused to output an operation amount of the vertical movement mechanism.

In one aspect, there is provided a polishing apparatus including: a polishing table supporting a polishing pad; a polishing head for pressing a substrate against the polishing pad; a pad temperature measuring device for measuring a surface temperature of the polishing pad; and the pad temperature adjusting means.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the heat exchanger is disposed above the polishing pad, and dirt contained in the abrasive grains of the polishing liquid and the abrasive powder of the polishing pad does not adhere to the heat exchanger. As a result, defects such as scratches and contamination are prevented from occurring on the substrate. The control device controls only the distance of the heat exchanger from the polishing pad so that the surface temperature of the polishing pad matches the target temperature. Therefore, the control responsiveness of the surface temperature of the polishing pad can be improved with simple control.

Drawings

Fig. 1 is a schematic view showing a polishing apparatus according to an embodiment.

Fig. 2 is a horizontal sectional view showing a heat exchanger according to an embodiment.

Fig. 3 is a schematic view showing a case where the surface temperature of the mat is adjusted by a heat exchanger.

Fig. 4 is a graph showing an example of the relationship between the distance between the heat exchanger and the polishing pad and the pad surface temperature.

Fig. 5 is a schematic diagram showing a case where the surface temperature of the pad is adjusted by operating the cooling liquid supply system.

Fig. 6 is a schematic view showing a case where the surface temperature of the mat is adjusted by the heat exchanger of the other embodiment.

Fig. 7 is a schematic diagram further illustrating the conditioning of the pad surface temperature by another embodiment of the heat exchanger.

Fig. 8 is a schematic diagram showing an example of a control device that executes machine learning for constructing a learning completion model for predicting an appropriate operation amount of the vertical movement mechanism.

Fig. 9 is a schematic diagram showing an example of the configuration of the neural network.

Fig. 10 (a) and 10 (b) are development views for explaining a simple recurrent network as an example of the recurrent neural network.

Fig. 11 is a schematic diagram showing an example of a polishing apparatus having a pad height measuring instrument for obtaining the profile of a polishing pad.

Description of the symbols

1 grinding head

2 grinding table

3 grinding pad

4 polishing liquid supply nozzle

11 heat exchanger

14 distance sensor

17 gas jet nozzle (Cooling mechanism)

18 heating device

19 heating lamp

23 Cooling fan (cooling mechanism)

30 heating liquid supply mechanism

39 pad temperature measuring device

40 control device

40a memory device

40b treatment device

50 cooling liquid supply mechanism

71 vertical moving mechanism

74 actuator

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Fig. 1 is a schematic view showing a polishing apparatus according to an embodiment. As shown in fig. 1, the polishing apparatus includes: a polishing head 1 for holding a wafer W as an example of a substrate and rotating the wafer W; a polishing table 2, the polishing table 2 supporting a polishing pad 3; a polishing liquid supply nozzle 4, the polishing liquid supply nozzle 4 supplying a polishing liquid (e.g., slurry) to the surface of the polishing pad 3; and a pad temperature adjusting device 5, the pad temperature adjusting device 5 adjusting 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.

The polishing head 1 is movable in the plumb direction and rotatable in the direction indicated by the arrow about the axial center of the polishing head 1. 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.

The polishing apparatus shown in fig. 1 further includes a dresser 20 for dressing the polishing pad 3 on the polishing table 2. The dresser 20 is configured to oscillate in the radial direction of the polishing pad 3 on the surface of the polishing pad 3. The lower surface of the dresser 20 constitutes a dressing surface made up of a large number of abrasive grains such as diamond particles. The dresser 20 swings and rotates on the polishing surface of the polishing pad 3, and dresses the surface of the polishing pad 3 by slightly grinding the polishing pad 3.

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 rotates together with the polishing table 2. In this state, the polishing liquid is supplied from the polishing liquid supply nozzle 4 to the surface of the polishing pad 3, and 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.

The pad temperature adjusting device 5 includes: a heat exchanger 11, the heat exchanger 11 being disposed above the polishing pad 3; a pad temperature measuring device 39 for measuring the surface temperature of the polishing pad 3 (hereinafter, sometimes referred to as the pad surface temperature); a heating liquid supply system 30 that supplies the heat exchanger 11 with a heating liquid adjusted to a predetermined temperature at a predetermined flow rate from the heating liquid supply system 30; an up-down moving mechanism 71, the up-down moving mechanism 71 moving the heat exchanger 11 up and down with respect to the polishing pad 3; and a control device 40, wherein the control device 40 controls the operation of the vertical movement mechanism 71 based on the measurement value of the pad temperature measuring device 39. In the present embodiment, the controller 40 is configured to control the operation of the entire polishing apparatus including the pad temperature adjusting device 5.

The heating liquid control system 30 shown in fig. 1 includes: a heating liquid supply tank 31 as a heating liquid supply source for storing a heating liquid adjusted to a predetermined temperature in the heating liquid supply tank 31; and a heating liquid supply pipe 32 and a heating liquid return pipe 33, the heating liquid supply pipe 32 and the 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.

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. In the present embodiment, a heat source (e.g., a heater) 48 is disposed in the heating liquid supply tank 31. The heating liquid stored in the heating liquid supply tank 31 is heated to a predetermined temperature (set temperature) by the heating source 48.

A first opening/closing valve (heating liquid supply valve) 41 and a first flow rate control valve (heating liquid flow rate control valve) 42 are attached to the heating liquid supply pipe 32. The first flow rate control valve 42 is disposed between the heat exchanger 11 and the first opening/closing valve 41. The first on-off valve 41 is a valve having no flow rate adjusting function, whereas the first flow rate control valve 42 is a valve having a flow rate adjusting function. The first flow rate control valve 42 is connected to the controller 40, and adjusts the flow rate of the heating liquid supplied to the heat exchanger 11 to a predetermined flow rate (set flow rate).

Warm water is used as the heating liquid to be supplied to the heat exchanger 11. The warm water is heated by the heating source 48 of the heating liquid supply tank 31 to a set temperature of, for example, about 80 ℃. When the temperature of the heating liquid is set to a higher temperature, silicone oil may be used as the heating liquid. In the case of using silicone oil as the heating liquid, the silicone oil is heated to a set temperature of 100 ℃ or higher (for example, about 120 ℃) by the heating source 48 of the heating liquid supply tank 31.

In this way, since the heating liquid adjusted to a predetermined temperature and flowing at a predetermined flow rate is supplied to the heat exchanger 11, the temperature of the heat exchanger 11 is maintained at a constant temperature. The heat exchanger 11 is disposed above the polishing pad 3, and the surface of the polishing pad 3 is heated by radiant heat from the heat exchanger 11.

Although described in detail later, the pad temperature adjusting device 5 may also be provided with a coolant supply system 50 that supplies coolant to the heat exchanger 11, as shown in fig. 1. The coolant supply system 50 functions as a cooling mechanism for cooling the surface of the polishing pad 3. In the following description, although an embodiment of the mat temperature adjusting apparatus 5 including the cooling liquid supply system 50 is described, the cooling liquid supply system 50 may be omitted from the mat temperature adjusting apparatus 5.

The coolant supply system 50 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 (e.g., a cold water supply source) provided in a factory in which the polishing apparatus is installed. The coolant is supplied to the heat exchanger 11 through the coolant supply pipe 51, flows inside the heat exchanger 11, and is then discharged from the heat exchanger 11 through the coolant discharge pipe 52. In one embodiment, the coolant flowing through the heat exchanger 11 may be returned to the coolant supply source through the coolant discharge pipe 52.

A second on-off valve (coolant supply valve) 55 and a second flow control valve (coolant flow control valve) 56 are attached to the coolant supply pipe 51. The second flow rate control valve 56 is disposed between the heat exchanger 11 and the second opening/closing valve 55. The second on-off valve 55 is a valve having no flow rate adjusting function, whereas the second flow rate control valve 56 is a valve having a flow rate adjusting function. The control device 40 is connected to the second flow rate control valve 56, and is capable of adjusting the flow rate of the coolant supplied to the heat exchanger 11.

Cold water or silicone oil is used as the cooling liquid to be supplied to the heat exchanger 11. In the case of using silicon oil as the coolant, the polishing pad 3 can be cooled quickly by connecting a chiller as a coolant supply source to the coolant supply pipe 51 and cooling the silicon oil to 0 ℃ or lower. Pure water can be used as cold water. A chiller may be used as a coolant supply source to generate cold water for cooling pure water. In this case, the cold water flowing through the heat exchanger 11 may be returned to the chiller through the coolant discharge pipe 52.

The heating liquid supply pipe 32 of the heating liquid supply system 30 and the cooling liquid supply pipe 51 of the cooling liquid supply system 50 are completely independent pipes. Therefore, the heating liquid and the cooling liquid can be simultaneously supplied to the heat exchanger 11 without mixing. 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.

Fig. 2 is a horizontal sectional view showing a heat exchanger 11 according to an embodiment. The heat exchanger 11 shown in fig. 2 has a heating flow path 61 and a cooling flow path 62 formed inside the heat exchanger 11. The heating flow path 61 and the cooling flow path 62 extend adjacent to each other (side by side with each other) and extend in a spiral shape. The heating flow path 61 and the cooling flow path 62 are completely separated, and the heating liquid and the cooling liquid are not mixed in the heat exchanger 11.

The heating liquid supply pipe 32 is connected to an inlet 61a of the heating channel 61, and the heating liquid return pipe 33 is connected to an outlet 61b of the heating channel 61. The coolant supply pipe 51 is connected to an inlet 62a of the cooling channel 62, and the coolant discharge pipe 52 is connected to an outlet 62b of the cooling channel 62. Each of the heating flow path 61 and the cooling flow path 62 is basically constituted by a plurality of circular flow paths 64 having a constant curvature and a plurality of inclined flow paths 65 connecting the circular flow paths 64. The two adjacent circular-arc flow paths 64 are connected by the inclined flow paths 65. With this configuration, the outermost peripheral portions of the heating flow path 61 and the cooling flow path 62 can be disposed on the outermost peripheral portion of the pad contact member 11. That is, the pad contact surface formed by the lower surface of the pad contact member 11 is located substantially entirely below the heating flow path 61 and the cooling flow path 62, and the heating liquid and the cooling liquid can rapidly heat and cool the surface of the polishing pad 3.

Returning to fig. 1, the pad temperature measuring device 39 of the pad temperature adjusting device 5 is disposed above the surface of the polishing pad 3, and measures the surface temperature of the polishing pad 3 in a non-contact manner. The mat temperature measuring device 39 is connected to the control device 40, and transmits the measured value to the control device 40.

The pad temperature measuring device 39 may be an infrared radiation thermometer or a thermocouple thermometer that measures the surface temperature of the polishing pad 3, or may be a temperature distribution measuring device that obtains the temperature distribution (temperature profile) of the polishing pad 3 along the radial direction of the polishing pad 3. A thermal imager, a thermopile, and an infrared imaging device are cited as examples of the temperature distribution measuring instrument. When the pad temperature measuring device 39 is a temperature distribution measuring device, the pad temperature measuring device 39 is configured to measure the distribution of the surface temperature of the polishing pad 3 in a region including the center and the outer peripheral edge of the polishing pad 3, that is, a region extending in the radial direction of the polishing pad 3. In the present specification, the temperature distribution (temperature profile) represents a relationship between the pad surface temperature and the position in the radial direction on the wafer W.

The vertical movement mechanism 71 of the pad temperature adjusting device 5 is a device that moves the heat exchanger 11 in the vertical direction with respect to the polishing pad 3 in a range where the heat exchanger 11 does not contact the surface of the polishing pad 3. The vertical movement mechanism 71 includes at least an actuator 74, and the actuator 74 can move the heat exchanger 11 in the vertical direction.

The vertical movement mechanism 71 shown in fig. 1 includes a support member 73 connected to the heat exchanger 11 and an actuator 74 that moves the heat exchanger 11 vertically via the support member 73. The actuator 74 may have any configuration as long as it can move the heat exchanger 11 in the vertical direction. For example, the actuator 74 may be a piston-cylinder device provided with a piston that moves the heat exchanger 11 up and down via the support member 73, or the actuator 74 may be a motor (e.g., a servo motor or a stepping motor) that moves the heat exchanger 11 up and down via the support member 73. In one embodiment, the actuator 74 may be a piezoelectric actuator that moves the heat exchanger 11 up and down through the support member 73 by using the piezoelectric effect of a piezoelectric element.

The vertical movement mechanism 71 is connected to the control device 40. The controller 40 controls the vertical position of the heat exchanger 11 with respect to the polishing pad 3 by controlling the operation of the vertical movement mechanism 71 (i.e., the operation amount of the actuator 74) based on the measurement value of the pad temperature measuring device 39. As described above, the heat exchanger 11 is heated to a predetermined temperature and maintained at the predetermined temperature. Therefore, when the heat exchanger 11 is brought close to the polishing pad 3, the pad surface temperature can be raised. When the heat exchanger 11 is moved away from the polishing pad 3, the pad surface temperature decreases.

Fig. 3 is a schematic diagram showing a case where the surface temperature of the mat is regulated by the heat exchanger 11. Fig. 4 is a graph showing an example of the relationship between the distance between the heat exchanger 11 and the polishing pad 3 and the pad surface temperature. In the following description, the distance between the heat exchanger 11 and the polishing pad 3 may be referred to as a "separation distance". In fig. 4, the vertical axis represents the temperature of the surface of the polishing pad 3 (i.e., pad surface temperature), and the horizontal axis represents the separation distance. Fig. 4 is a graph showing an example of the pad surface temperature that changes when the heat exchanger 11 maintained at a predetermined temperature is moved relative to the polishing pad 3.

The control device 40 stores the relationship between the separation distance and the pad surface temperature in advance. For example, the control device 40 stores in advance a graph shown in fig. 4 or a relational expression between the separation distance and the pad surface temperature obtained by the graph. In one embodiment, the controller 40 may store a data table of the distance and the pad surface temperature obtained from the table shown in fig. 4 in advance. The graph shown in fig. 4 can be obtained through experiments or simulation.

The pad temperature adjusting device 5 has at least one distance sensor 14, and the distance sensor 14 is capable of measuring the distance between the heat exchanger 11 and the surface of the polishing pad 3. In the embodiment shown in fig. 1 and 3, the distance sensor 14 is attached to the outer surface of the heat exchanger 11. The distance sensor 14 is also connected to the control device 40, and transmits its measurement value to the control device 40.

As described above, the controller 40 controls the vertical position of the heat exchanger 11 with respect to the polishing pad 3 using the vertical movement mechanism 71 so that the measurement value of the pad temperature measuring device 39 matches the predetermined target temperature. Hereinafter, a method of adjusting the mat surface temperature by the mat temperature adjusting device 5 will be described in further detail.

First, the controller 40 moves the heat exchanger 11 to reach a spacing distance X1 (see fig. 4) at which the distance between the heat exchanger 11 and the polishing pad 3 corresponds to a predetermined target temperature T1. Specifically, the controller 40 calculates a movement amount until the distance between the heat exchanger 11 and the polishing pad 3 reaches the separation distance based on the measurement value of the distance sensor 14, and determines an operation amount of the actuator 74 of the vertical movement mechanism 71 corresponding to the obtained movement amount. The control device 40 sends a command to the actuator 74 to move the heat exchanger 11 based on the operation amount of the actuator 74.

Next, if the measured value of the pad temperature measuring device 39 is higher (lower) than the predetermined target temperature T1, the control device 40 sends a command to the actuator 74 of the vertical movement mechanism 71 to increase (decrease) the separation distance X. In this case, the amount of movement of the heat exchanger 11 is determined based on the difference between the target temperature T1 and the measurement value of the pad temperature measuring device 39. Specifically, the controller 40 calculates the difference between the target temperature T1 and the measurement value of the mat temperature measuring device 39, and determines the movement amount of the heat exchanger 11 to make the difference 0, based on the table shown in fig. 4 or the relational expression (or data table) between the distance obtained from the table and the mat surface temperature. Each time the distance of the heat exchanger 11 from the polishing pad 3 is changed, the controller 40 stores a combination of the separation distance X and the pad surface temperature corresponding to the separation distance X (i.e., the measurement value of the pad temperature measuring device 39).

In this way, the controller 40 changes the distance X of the heat exchanger 11 from the polishing pad 3, which is maintained at a predetermined temperature, in order to adjust the pad surface temperature to the target temperature. The heat exchanger 11 is always positioned above the polishing pad 3, and the controller 40 does not bring the heat exchanger 11 into contact with the polishing pad 3. Therefore, since the abrasive grains contained in the polishing liquid and the dirt such as the abrasive powder of the polishing pad 3 do not adhere to the heat exchanger 11, defects such as scratches and contamination are prevented from occurring in the wafer (substrate) W. Further, the control device 40 controls only the distance of the heat exchanger 11 from the polishing pad 3 in order to adjust the surface temperature of the polishing pad 3 to the target temperature. Therefore, the control responsiveness of the surface temperature of the polishing pad 3 can be improved with simple control.

The up-down moving mechanism 71 necessarily has an upper limit and a lower limit of the moving amount of the heat exchanger 11. The lower limit of the amount of movement of the heat exchanger 11 (see the spacing distance Xl in fig. 4) is a limit value at which the heat exchanger 11 can be brought close to the surface of the polishing pad 3, and is determined in advance. The controller 40 stores in advance an operation amount of the actuator 74 corresponding to the lower limit of the movement amount of the heat exchanger 11, and is configured not to transmit a command exceeding the operation amount to the actuator 74.

The upper limit of the amount of movement of the heat exchanger 11 (see the interval distance Xh in fig. 4) is, for example, a physical or mechanical operation limit value of the vertical movement mechanism 71. When there are other components of the polishing apparatus directly above the heat exchanger 11, the upper limit of the amount of movement of the heat exchanger 11 is set in advance so that the heat exchanger 11 does not contact the other components. Thus, the heat exchanger 11 is kept away from the surface of the polishing pad 3. Therefore, as shown in fig. 4, when the predetermined target temperature is set to a target temperature T2 equal to or lower than the pad surface temperature Tc corresponding to the upper limit of movement of the heat exchanger 11 and the vertical movement mechanism 71 (i.e., the separation distance Xh shown in fig. 4), the temperature of the surface of the polishing pad 3 cannot be lowered to the target temperature T2 by the heat exchanger 11 maintained at the predetermined temperature.

In this case, the controller 40 operates the coolant supply system (cooling mechanism) 50 described above. Fig. 5 is a schematic diagram showing a case where the coolant supply system 50 is operated to adjust the pad surface temperature. As shown in fig. 5, the coolant is supplied to the heat exchanger 11 through a coolant supply system 50 (see fig. 1). In this case, the heating liquid adjusted to a predetermined temperature is continuously supplied to the heat exchanger 11 at a predetermined flow rate, but the temperature of the heat exchanger 11 is lowered by the cooling liquid supplied from the cooling liquid supply system 50. As a result, the temperature of the surface of the polishing pad 3 can be lowered to the target temperature T2 equal to or lower than the pad surface temperature Tc.

The control device 40 adjusts the flow rate of the coolant supplied to the heat exchanger 11 based on the measurement value of the pad temperature measuring device 39. More specifically, the controller 40 controls the opening degree of the second flow rate control valve 56 (see fig. 1) to adjust the flow rate of the coolant supplied to the heat exchanger 11 so that the measurement value of the pad temperature measuring device 39 matches the target temperature T2.

When the predetermined target temperature is set to the target temperature T2 equal to or lower than the mat surface temperature Tc corresponding to the upper limit of movement of the vertical movement mechanism 71, the control device 40 controls the flow rate of the coolant without controlling the operation amount of the vertical movement mechanism 71 (i.e., the vertical position of the heat exchanger 11). In this case, the parameter controlled by the controller 40 to adjust the pad surface temperature to the predetermined target temperature is only the flow rate of the coolant. Therefore, the control responsiveness of the surface temperature of the polishing pad 3 can be improved with simple control.

The coolant is used only when the predetermined target temperature is set to a temperature equal to or lower than the pad surface temperature Tc corresponding to the upper limit of the movement of the vertical movement mechanism 71. Therefore, the mat temperature control device 5 of the present embodiment can reduce the amount of coolant used as compared with a conventional mat temperature control device that constantly supplies coolant to the heat exchanger. As a result, the cost for manufacturing the coolant is reduced, and therefore, the running cost of the mat temperature adjusting device 5 can be reduced.

Fig. 6 is a schematic diagram showing a case where the surface temperature of the mat is adjusted by the heat exchanger 11 of another embodiment. The configuration of the embodiment not specifically described is the same as that of the above-described embodiment, and therefore, redundant description thereof is omitted.

The heat exchanger 11 shown in fig. 6 includes a heater 18 instead of the heating liquid supply system 30. The heater 18 is connected to a control device 40. The control device 40 controls the current and voltage supplied to the heater 18 to be constant. Thereby, the heat exchanger 11 is heated to a predetermined temperature and maintained at the predetermined temperature.

In the embodiment shown in fig. 6, a gas injection nozzle 17 for injecting a gas onto the surface of the polishing pad 3 is provided instead of the coolant supply system 50. The gas injection nozzle 17 functions as a cooling mechanism for cooling the surface of the polishing pad 3.

In the present embodiment, the pad temperature adjusting device 5 adjusts the pad surface temperature to the target temperature by moving the heat exchanger 11 maintained at the predetermined temperature up and down with respect to the polishing pad 3 based on the measurement value of the pad temperature measuring device 39. When the predetermined target temperature is set to a target temperature T2 equal to or lower than the pad surface temperature Tc corresponding to the upper limit of the movement of the vertical movement mechanism 71, the gas injection nozzle (cooling mechanism) 17 is activated. The control device 40 controls the flow rate of the gas injected from the gas injection nozzle 17 based on the measurement value of the pad temperature measuring device 39.

Fig. 7 is a schematic diagram showing a case where the surface temperature of the mat is further adjusted by the heat exchanger 11 of the other embodiment. The configuration of the embodiment not specifically described is the same as that of the above-described embodiment, and therefore, redundant description thereof is omitted.

The heat exchanger 11 shown in fig. 7 includes a heating lamp 19 instead of the heating liquid supply system 30. The heater lamps 19 are connected to a control device 40, and the control device 40 controls the current and voltage supplied to the heater lamps 19 to be constant. Thereby, the heat exchanger 11 is heated to a predetermined temperature and maintained at the predetermined temperature.

In the embodiment shown in fig. 7, a cooling fan 23 that generates an air flow toward the surface of the polishing pad 3 is provided instead of the coolant supply system 50. The cooling fan 23 functions as a cooling mechanism for cooling the surface of the polishing pad 3.

In the present embodiment, the pad temperature adjusting device 5 adjusts the pad surface temperature to the target temperature by moving the heat exchanger 11 maintained at the predetermined temperature up and down with respect to the polishing pad 3 based on the measurement value of the pad temperature measuring device 39. When the predetermined target temperature is set to a target temperature T2 equal to or lower than the mat surface temperature Tc corresponding to the upper limit of movement of the vertical movement mechanism 71, the cooling fan (cooling mechanism) 23 is started. The control device 40 controls the rotation speed of the cooling fan 23 based on the measurement value of the pad temperature measuring device 39.

In one embodiment, the mat temperature control device 5 shown in fig. 6 may include a cooling fan 23 instead of the gas injection nozzle 17. The mat temperature control device 5 shown in fig. 7 may have a gas injection nozzle 17 instead of the cooling fan 23.

As long as the distance between the heat exchanger 11 and the surface of the polishing pad 3 can be measured in a non-contact manner, any sensor can be used as the distance sensor 14. A laser sensor, an ultrasonic sensor, an eddy current sensor, a capacitance sensor, or the like is given as an example of the distance sensor 14. In the embodiment shown in fig. 1 and 3, only one distance sensor 14 is attached to the heat exchanger 11, but the mat temperature adjusting device 5 may have a plurality of (for example, four) distance sensors 14 arranged at equal intervals along the outer peripheral surface of the heat exchanger 11. When the mat temperature adjusting device 5 includes a plurality of distance sensors 14, the control device 40 may use an average value of the measurement values of the plurality of distance sensors 14 as the separation distance, or may use a maximum value (or a minimum value) of the measurement values of the plurality of distance sensors 14 as the separation distance.

The controller 40 of the pad temperature adjusting device 5 may predict or determine an appropriate operation amount of the vertical movement mechanism 71 (or an appropriate distance between the heat exchanger 11 and the polishing pad 3) for rapidly converging the pad surface temperature to the predetermined target temperature and maintaining the predetermined target temperature, using a learning completion model constructed by performing machine learning.

Machine learning is performed by a learning algorithm that is an algorithm of Artificial Intelligence (AI), and a learning completion model that predicts an appropriate operation amount of the up-and-down moving mechanism 71 is constructed by the machine learning. The learning algorithm for constructing the learning completion model is not particularly limited. For example, known learning algorithms such as "supervised learning", "unsupervised learning", "reinforcement learning", and "neural network" can be used as the learning algorithm for learning the appropriate operation amount of the vertical movement mechanism 71.

Fig. 8 is a schematic diagram showing an example of a control device 40 capable of executing machine learning for constructing a learning completion model. The control device 40 includes: a storage device 40a, the storage device 40a storing programs, data, learning completion models, and the like; a processing device 40b such as a CPU (central processing unit) or a GPU (graphic processing unit), the processing device 40b performing an operation based on a program stored in the storage device 40 a; and a machine learning device 300, the machine learning device 300 being connected to the processing device 40b, and constructing a learning completion model that predicts an appropriate operation amount of the vertical movement mechanism 71. In one embodiment, a machine learning device 300 that constructs a learning completion model that predicts an appropriate operation amount of the vertical movement mechanism 71 may be provided separately from the control device 40.

The machine learning device 300 shown in fig. 8 is an example of a machine learning device capable of learning an appropriate operation amount of the vertical movement mechanism 71. The machine learning device 300 includes a state observation unit 301, a data acquisition unit 302, and a learning unit 303.

The state observation unit 301 observes a state variable as an input value for machine learning. The state variable is a generic term for a temperature control parameter related to the control of the pad surface temperature. In the present embodiment, the state variables include at least the measurement value of the mat surface temperature acquired by the mat temperature measuring device 39 and the measurement value (i.e., the separation distance) of the distance sensor 14 when the mat surface temperature is acquired by the mat temperature measuring device 39.

The data acquisition unit 302 acquires the movement amount data from the determination unit 310. The movement amount data is data used when a learning completion model for predicting an appropriate operation amount of the vertical movement mechanism 71 is constructed, and is data for measuring a relationship between a variation amount when a distance between the heat exchanger 11 and the polishing pad 3 maintained at a certain temperature is varied and a variation amount of the temperature of the surface of the polishing pad 3 corresponding to the variation amount, according to a known measurement method. The movement amount data is correlated (correlated) with the state variable input to the state observing unit 301.

An example of the machine learning performed by the machine learner 300 is as follows. First, the state observing unit 301 acquires a state variable including at least a spacing distance and a temperature of the surface of the polishing pad 3 corresponding to the spacing distance, and the data acquiring unit 302 acquires movement amount data related to the state variable acquired by the state observing unit 301. The learning unit 303 learns an appropriate operation amount of the vertical movement mechanism 71 based on a training data set which is a combination of the state variables acquired from the state observing unit 301 and the movement amount data acquired from the data acquiring unit 302. The machine learning performed by the machine learner 300 is repeatedly performed until the machine learner 300 outputs an appropriate operation amount of the up-down moving mechanism 71.

In one embodiment, the machine learning performed by the learning unit 303 of the machine learner 300 may be machine learning using a neural network, and particularly, may be deep learning. Deep learning is a machine learning method based on a neural network in which hidden layers (also referred to as intermediate layers) are multilayered. In this specification, machine learning using a neural network including an input layer, two or more hidden layers, and an output layer is referred to as deep learning.

Fig. 9 is a schematic diagram showing an example of the configuration of the neural network. The neural network shown in fig. 9 has an input layer 350, a plurality of hidden layers 351, and an output layer 352. The neural network learns an appropriate operation amount of the vertical movement mechanism 71 based on a training data set constituted by a large number of combinations of the state variables acquired by the state observing unit 301 and the movement amount data acquired by the data acquiring unit 302 related to the state variables. That is, the neural network learns the relationship between the state variable and the operation amount of the up-down moving mechanism 71. Such machine learning is called so-called "supervised learning". In supervised learning, the association of state variables and movement amount data (labels) related to the state variables is learned inductively by inputting a combination of them in a large amount to a neural network.

In an embodiment, the neural network may also learn an appropriate operation amount of the up-down moving mechanism 71 by so-called "unsupervised learning". Unsupervised learning is, for example, to input only a large number of state variables into a neural network and to learn how the state variables are distributed. In the unsupervised learning, even if the supervised output data (movement amount data) corresponding to the state variables are not input to the neural network, the input state variables are compressed, classified, shaped, and the like, and a learning completion model for outputting an appropriate operation amount of the up-down moving mechanism 71 is constructed. That is, in unsupervised learning, a neural network classifies state variables that are largely input into a small group having some similar characteristics. The neural network sets a predetermined reference for outputting an appropriate operation amount of the vertical movement mechanism 71 to the plurality of groups classified, and constructs a learning completion model by optimizing the relationship between the predetermined reference and the reference, thereby outputting an appropriate operation amount of the vertical movement mechanism 71.

Furthermore, in one embodiment, in order to reflect the change of the state variable with time in the learning completion model, the machine learning performed by the learning unit 303 may use a so-called "Recurrent Neural Network (RNN)". The recurrent neural network uses not only the state variable at the current time but also the state variable input to the input layer 350 up to the present time. In the recurrent neural network, by expanding and considering the change of the state variable along the time axis, it is possible to construct a learning completion model for estimating an appropriate operation amount of the up-down moving mechanism 71 based on the transition of the state variable input up to now.

Fig. 10 (a) and 10 (b) are development views for explaining a recurrent neural Network (Elman Network) as an example of the recurrent neural Network. More specifically, (a) of fig. 10 is a schematic diagram showing a time axis development of the Elman network, and (b) of fig. 10 is a schematic diagram showing a backward propagation elapsed time of the error inverse propagation method (also referred to as "backward propagation").

In the Elman networks shown in fig. 10 (a) and 10 (b), unlike a normal neural network, an error propagates in a time-tracing manner (see fig. 10 (b)). By applying such a recurrent neural network structure to the neural network of machine learning executed by the learning unit 303, it is possible to construct a learning completion model that outputs an appropriate operation amount of the up-down moving mechanism 71 based on the transition of the state variables input up to now.

The learning completion model thus constructed is stored in the storage device 40a (see fig. 8) of the control device 40. The control device 40 operates according to a program stored electrically in the storage device 40 a. That is, the processing device 40b of the control device 40 inputs state variables including at least the distance between the pad temperature measuring device 39 and the distance sensor 14 to the control device 40 and the pad surface temperature corresponding to the distance to the input layer 350 of the learning completion model, predicts the operation amount of the vertical movement mechanism 71 for bringing the pad surface temperature to the predetermined target temperature from the input state variables (and the amount of change over time in the state variables), and performs an operation for outputting the predicted operation amount from the output layer 352. The controller 40 moves the heat exchanger 11 in the vertical direction based on the operation amount of the vertical movement mechanism 71 outputted from the output layer 352. By such control, the pad surface temperature can be adjusted to the target temperature more quickly and accurately.

When the operation amount of the vertical movement mechanism 71 outputted from the output layer 352 is determined to be equal to the normal data, the control device 40 may store the operation amount of the vertical movement mechanism 71 in the determination unit 310 as additional supervisory data. In this case, the machine learner 300 updates the learning completion model by machine learning based on the supervised data and the appended supervised data. This can improve the accuracy of the operation amount of the vertical movement mechanism 71 output from the learning completion model.

In one embodiment, some of the state variables shown below may be selected as the state variables to be further input to the state observation unit 301. Alternatively, all the state variables described below may be input to the state observation unit 301.

(1) Kind of the polishing pad 3

(2) Thickness of the polishing pad 3

(3) Amount of wear of the polishing pad 3

(4) Rotational speed of polishing head 1

(5) Pressing load of polishing head 1 (i.e., wafer W) against polishing pad 3

(6) Rotational speed of the polishing table 2

(7) Kinds of abrasive grains contained in polishing liquid (slurry)

(8) Flow rate of the polishing liquid

(9) Temperature of the polishing slurry

(10) Set temperature of heat exchanger 11

(11) Ambient gas temperature in the grinding device

These state variables (1) to (10) are related to changes in the pad surface temperature. Specifically, when any of the above state variables (1) to (10) is changed, the amount of frictional heat generated between the wafer W and the polishing pad 3 is changed. Therefore, under the condition that any one of the state variables (1) to (10) is different, the pad surface temperature to be reached is different even if the heat exchanger 11 heats the surface of the polishing pad 3 at the same interval distance. The same phenomenon occurs even under the condition that the atmospheric temperature in the polishing apparatus is different.

Therefore, by further inputting at least one of these state variables (1) to (11) to the state observation unit 301 and using it for machine learning to construct a learning completion model, the learning completion model can output a more accurate operation amount of the up-down movement mechanism 71.

Next, a method of measuring the amount of wear of the polishing pad 3 will be described with reference to fig. 11. Fig. 11 is a schematic diagram showing an example of a polishing apparatus having a pad height measuring device for obtaining the profile of the polishing pad 3.

The polishing apparatus shown in fig. 11 further includes: a dresser device 152 provided for regenerating the surface of the polishing pad 3 deteriorated by repeated polishing of the wafer W; a pad height measuring unit 173, the pad height measuring unit 173 being attached to the dresser device 152. As described below, the pad height measuring device 173 measures the height of the surface of the polishing pad 3, and the control device 40 calculates the amount of wear of the polishing pad 3 based on the obtained height of the surface of the polishing pad 3.

The trimming device 152 shown in fig. 11 includes: the above-described dresser 20 (see fig. 1) that dresses the surface of the polishing pad 3; a dresser shaft 155 to which the dresser 20 is attached; a cylinder 154 provided at an upper end of the dresser shaft 155; and a dresser arm 157 that rotatably supports the dresser shaft 155. The lower surface of the dresser 20 constitutes a dressing surface made of abrasive grains (e.g., diamond particles). The cylinder 154 is fixed to the dresser arm 157 via a support mechanism, not shown.

The dresser arm 157 is driven by a motor, not shown, and is configured to rotate about a dresser rotation shaft 158. The dresser 20 is rotationally driven together with the dresser shaft 155 by a rotation mechanism, not shown, provided in the dresser arm 157. The air cylinder 154 functions as an actuator that presses the dresser 20 against the surface of the polishing pad 3 with a predetermined load (pressing force) via the dresser shaft 155. When the dresser arm 157 rotates about the dresser rotation shaft 158, the dresser 20 swings in the substantially radial direction of the polishing table 2 on the surface of the polishing pad 3.

In dressing the polishing pad 3, the dresser 20 rotates about the dresser shaft 155, and a dressing liquid is supplied from the liquid supply nozzle 174 onto the polishing pad 3. In this state, the dresser 20 is pressed against the polishing pad 3, and the dressing surface (i.e., the lower surface of the dresser 20) is in sliding contact with the surface of the polishing pad 3. Then, the dresser arm 157 is rotated about the dresser rotation shaft 158, and the dresser 20 is swung in the radial direction of the polishing pad 3. Thus, the polishing pad 3 is ground by the dresser 20, and the surface of the polishing pad 3 is dressed (regenerated).

The pad height measuring instrument 173 shown in fig. 11 includes a pad height sensor 175 for measuring the height of the surface of the polishing pad 3, and a sensor target 176 disposed to face the pad height sensor 175. The mat-height sensor 175 is connected to the control device 40.

The pad height sensor 175 is fixed to the dresser arm 157, and the sensor target 176 is fixed to the dresser shaft 155. The sensor target 176 moves up and down integrally with the dresser shaft 155 and the dresser 20. On the other hand, the vertical position of the pad height sensor 175 is fixed. The pad height sensor 175 is a displacement sensor, and can indirectly measure the height of the surface of the polishing pad 3 (the thickness of the polishing pad 3) by measuring the displacement of the sensor target 176. Since the sensor target 176 moves up and down integrally with the dresser 20, the pad height sensor 175 can measure the height of the surface of the polishing pad 3 during dressing of the polishing pad 3. As the pad height sensor 175, various types of sensors such as a linear scale sensor, a laser sensor, an ultrasonic sensor, an eddy current sensor, and a capacitance sensor can be used.

The pad height sensor 175 is connected to the control device 40, and transmits an output signal of the pad height sensor 175 (i.e., a measured value of the height of the surface of the polishing pad 3) to the control device 40. The control device 40 can acquire the profile of the polishing pad 3 (the cross-sectional shape of the surface of the polishing pad 3) from the measured value of the height of the surface of the polishing pad 3.

After the unused polishing pad 3 is attached to the polishing table 2, the controller 40 obtains the initial height of the polishing pad 3 using the pad height measuring instrument 173, and stores the initial height in the storage unit 40a (see fig. 8). Each time a predetermined number of wafers W are polished or the polishing pad 3 is dressed, the controller 40 measures the height (wear height) of the polishing pad 3 using the pad height measuring instrument 173. The controller 40 can calculate the amount of wear of the polishing pad 3 by subtracting the wear height from the initial height. In this way, the control device 40 can acquire the amount of wear of the polishing pad 3 as the state variable input to the state observing unit 301.

When the polishing apparatus includes the pad height measuring device 173, the controller 40 may calculate the distance between the polishing pad 3 and the heat exchanger 11 using the pad height sensor 175 instead of the distance sensor 14, and control the operation of the vertical movement mechanism 71. In this case, the controller 40 stores an initial position of the heat exchanger 11 with respect to a predetermined reference surface in advance.

The predetermined reference surface is, for example, a dressing surface of the dresser 20 which is retracted above the polishing pad 3 after dressing. The initial position is, for example, a standby position of the heat exchanger 11 when the wafer W is not polished, and the controller 40 moves the heat exchanger 11 to the initial position using the vertical movement mechanism 71 every time the polishing of the wafer W is completed.

As described above, the control device 40 stores the initial height of the polishing pad 3. Therefore, the controller 40 can calculate the distance between the heat exchanger 11 located at the initial position and the unused polishing pad 3. Further, the control device 40 can obtain the current height of the polishing pad 3 by bringing the dresser 20 into contact with the surface of the polishing pad 3 every time the wafer W is polished. That is, the controller 40 can calculate the distance between the heat exchanger 11 located at the initial position and the current surface of the polishing pad 3.

Therefore, the controller 40 can calculate the operation amount of the actuator 74 by subtracting the distance from the distance between the heat exchanger 11 located at the initial position and the current surface of the polishing pad 3. According to the present embodiment, the mat height sensor 175 is used as a sensor for making the heat exchanger 11 to reach the spaced distance. That is, the pad height sensor 175 is used instead of the distance sensor 14 for measuring the distance between the polishing pad 3 and the heat exchanger 11. Therefore, in the case where the polishing apparatus includes the pad height measuring device 173, the distance sensor 14 is not required, and therefore, the manufacturing cost of the pad temperature adjusting apparatus 5 can be reduced.

The above-described embodiments are described in order to enable those having ordinary skill in the art to which the present invention pertains to practice the present invention. Various modifications of the above-described embodiments will be apparent to those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but interpreted as the widest scope according to the technical idea defined by the scope of the claims of the present invention.