WO2018034308A1 - Polishing method, polishing device, and recording medium with computer program recorded thereon - Google Patents

Abstract

The present invention relates to a polishing method for polishing a substrate such as a wafer. The polishing method comprises: polishing a substrate (W) by pressing the substrate (W) against the surface of a polishing pad (3); changing the surface temperature of the polishing pad (3) by operating flow rate control valves (42, 56) that are for controlling the flow rate of a fluid flowing through a pad temperature adjusting member (11) during the polishing of the substrate (W); measuring the surface temperature of the polishing pad (3); computing a PID parameter on the basis of a change in the surface temperature of the polishing pad (3) over time; calculating operation quantities of the flow rate control valves (42, 56) that are for minimizing the deviation between a target temperature value and a measured value of the surface temperature of the polishing pad by using a PID arithmetic expression that includes the PID parameter; and operating the flow rate control valves (42, 56) in accordance with the operation quantities during the polishing of the substrate (W).

Description

Polishing method, polishing apparatus, and recording medium recording computer program

The present invention relates to a polishing method for polishing a substrate such as a wafer, a polishing apparatus, and a recording medium on which a computer program for controlling the surface temperature of a polishing pad of the polishing apparatus is recorded.

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

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

Therefore, a polishing apparatus that measures the surface temperature of the polishing pad and adjusts the temperature of the polishing surface of the polishing pad by PID control based on the measured temperature information of the polishing pad has been proposed (for example, see Patent Document 1).

JP 2011-136406 A

However, there is no clear guideline for the method for determining the PID parameter, and the user must determine the PID parameter through trial and error. In addition, the PID parameter determination method often depends on a skilled person having special knowledge, experience, and know-how. Therefore, a lot of time is required to determine the PID parameter, and the cost is increased.

Therefore, an object of the present invention is to provide a polishing method and a polishing apparatus that do not require special knowledge, experience, and know-how, and that calculate PID parameters efficiently in a short time. Another object of the present invention is to provide a recording medium on which a program for controlling the surface temperature of the polishing pad is recorded.

In order to achieve the above-described object, according to one embodiment of the present invention, a substrate is pressed against a surface of a polishing pad to polish the substrate, and a flow rate of a fluid flowing through the pad temperature adjusting member is controlled during the polishing of the substrate. Operating the flow control valve for changing the surface temperature of the polishing pad, measuring the surface temperature of the polishing pad, calculating the PID parameter based on the time change of the surface temperature of the polishing pad, The operation amount of the flow rate control valve for minimizing the deviation between the temperature target value and the measured value of the surface temperature of the polishing pad is calculated using a PID arithmetic expression having the PID parameter, and the substrate is polished. In the polishing method, the flow control valve is operated according to the operation amount.

In a preferred aspect of the present invention, the step of measuring the surface temperature of the polishing pad includes a step of measuring a temperature distribution in a region including a center and an outer peripheral portion of the polishing pad.
In a preferred aspect of the present invention, in the step of changing the surface temperature of the polishing pad, the pad temperature adjusting member is brought into contact with or close to the surface of the polishing pad during polishing of the substrate. It is a step of changing the surface temperature of the polishing pad by operating a flow rate control valve for controlling the flow rate of the flowing fluid.
In a preferred aspect of the present invention, the step of changing the surface temperature of the polishing pad is a flow rate for controlling the flow rate of the fluid supplied from the pad temperature adjusting member onto the surface of the polishing pad during the polishing of the substrate. It is a step of changing the surface temperature of the polishing pad by operating a control valve.
In a preferred aspect of the present invention, the fluid is a heating fluid and a cooling fluid.

In a preferred aspect of the present invention, the step of calculating the PID parameter uses a limit cycle method, a step response method, or a Ziegler-Nichols limit sensitivity method to change the surface temperature of the polishing pad over time. It is a process of calculating a PID parameter based on it.
In a preferred aspect of the present invention, a simulation of the surface temperature of the polishing pad expected as a result of operating the flow control valve with an operation amount calculated using the PID arithmetic expression is performed.
In a preferred aspect of the present invention, a simulation is further executed to show a time transition of the surface temperature of the polishing pad expected when the temperature target value is changed.

Another aspect of the present invention includes a polishing table that supports a polishing pad, a polishing head that presses a substrate against the polishing pad, and a pad temperature adjustment system that adjusts a surface temperature of the polishing pad, and the pad temperature adjustment system. A pad temperature adjusting member having a flow path through which a fluid flows, a fluid supply pipe connected to the flow path, a flow control valve attached to the fluid supply pipe, and a surface temperature of the polishing pad And a PID control unit for operating the flow rate control valve, and the PID control unit operates the flow rate control valve during polishing of the substrate to control the surface of the polishing pad. Changing the temperature, obtaining a measured value of the surface temperature of the polishing pad from the pad temperature measuring instrument, and based on the time change of the surface temperature of the polishing pad, An ID parameter is calculated, and an operation amount of the flow control valve for minimizing a deviation between a temperature target value and a measured value of the surface temperature of the polishing pad is calculated using a PID arithmetic expression having the PID parameter. The polishing apparatus is characterized in that the flow control valve is operated according to the operation amount.

In a preferred aspect of the present invention, the pad temperature measuring device is at least one temperature measuring device selected from an infrared radiation thermometer, a thermocouple thermometer, a thermography, and a thermopile.
In a preferred aspect of the present invention, the pad temperature measuring device is configured to measure a temperature distribution in a region including a center and an outer peripheral portion of the polishing pad.
In a preferred aspect of the present invention, the pad temperature adjustment system further includes a temperature indicator that displays a surface temperature of the polishing pad measured by the pad temperature measuring device.
In a preferred aspect of the present invention, the pad temperature adjusting member is a cooling nozzle that sprays a cooling fluid onto the surface of the polishing pad.
In a preferred aspect of the present invention, the pad temperature adjusting member has a pad contact surface capable of contacting the surface of the polishing pad.

In a preferred aspect of the present invention, the PID control unit calculates the PID parameter using any one of a limit cycle method, a step response method, and a Ziegler-Nichols limit sensitivity method.
In a preferred aspect of the present invention, the PID control unit executes a simulation of a surface temperature of the polishing pad that is expected as a result of operating the flow rate control valve with an operation amount calculated using the PID arithmetic expression. It is configured.
In a preferred aspect of the present invention, the PID control unit is configured to further execute a simulation showing a time transition of the surface temperature of the polishing pad expected when the temperature target value is changed. And

According to still another aspect of the present invention, a command is given to the polishing head to cause the polishing head to perform an operation of pressing the substrate against the surface of the polishing pad to polish the substrate, and the fluid flowing through the pad temperature adjusting member. A step of changing a surface temperature of the polishing pad by operating a flow rate control valve provided to control a flow rate; a step of obtaining a measured value of the surface temperature of the polishing pad; and a surface of the polishing pad In order to minimize the deviation between the target temperature value and the measured value of the surface temperature of the polishing pad, using the step of calculating the PID parameter based on the time change of the temperature and the PID arithmetic expression having the PID parameter. Calculating a manipulated variable of the flow rate control valve and operating the flow rate control valve according to the manipulated value in a computer It is a non-transitory computer-readable recording medium recording a program for causing the row.

According to the present invention, since the PID parameter can be automatically calculated based on the time change of the surface temperature of the polishing pad during the polishing of the substrate, an experiment by trial and error for determining the PID parameter, special knowledge No experience, know-how is required, and there is no need to rely on skilled workers. Therefore, the PID parameter can be determined in a short time and efficiently.

It is a mimetic diagram showing one embodiment of a polish device. It is a schematic diagram which shows other embodiment of a grinding | polishing apparatus. It is the figure which looked at the temperature measurement area | region of the pad temperature measuring device from the top. It is the figure which looked at the temperature measurement area | region of the pad temperature measuring device from the side. It is a horizontal sectional view showing a pad temperature adjusting member. It is a top view which shows the positional relationship of the pad temperature adjustment member on a polishing pad, and a polishing head. It is a schematic diagram which shows a temperature indicator. It is a figure which shows other embodiment of a pad temperature adjustment member. It is a figure for demonstrating a limit cycle method. It is a figure which shows 2 position operation | movement of a flow control valve. It is a figure which shows an example of the coefficient used for calculation of a PID parameter. It is a figure which shows the feedback control system when calculating a PID parameter. It is a schematic diagram which shows the structure of a PID control part. It is a flowchart which shows the step of the PID control part which operate | moves according to a program. It is a figure for demonstrating a step response method. It is a figure for demonstrating the limit sensitivity method of Ziegler-Nichols. It is a figure which shows the simulation result which shows the time transition of the surface temperature of a polishing pad. It is a flowchart which shows a mode that a PID parameter is calculated for every polishing process of a wafer.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic view showing a polishing apparatus. As shown in FIG. 1, the polishing apparatus includes a polishing head 1 that holds and rotates a wafer W that is an example of a substrate, a polishing table 2 that supports a polishing pad 3, and a polishing liquid (for example, A polishing liquid supply nozzle 4 for supplying a slurry) and a pad temperature adjusting system 5 for 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 can move in the vertical direction, and can rotate in the direction indicated by the arrow about its axis. 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 affixed to the upper surface of the polishing table 2.

The polishing apparatus further includes a dresser 20 for dressing the polishing pad 3 on the polishing table 2. The dresser 20 is configured to swing on the surface of the polishing pad 3 in the radial direction of the polishing pad 3. The lower surface of the dresser 20 constitutes a dressing surface composed of a large number of abrasive grains such as diamond particles. The dresser 20 rotates while swinging on the polishing surface of the polishing pad 3, and dresses the surface of the polishing pad 3 by slightly scraping the polishing pad 3.

The polishing of the wafer W is performed as follows. The wafer W to be polished is held by the polishing head 1 and further rotated by the polishing head 1. On the other hand, the polishing pad 3 is rotated together with the polishing table 2. In this state, 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 (ie, 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 flattened 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 system 5 includes a pad temperature adjusting member 11 in which a flow path for flowing a fluid for adjusting the surface temperature of the polishing pad 3 is formed, and the temperature adjusted heating fluid and cooling fluid are supplied to the pad temperature adjusting member. 11 and a fluid supply system 30 for supplying the fluid to the vehicle 11. The pad temperature adjusting member 11 can be in direct contact with the surface of the polishing pad 3 or close to the surface of the polishing pad 3.

The pad temperature adjustment system 5 further includes a vertical movement mechanism (vertical movement mechanism) 71 that moves the pad temperature adjustment member 11 perpendicularly to the surface of the polishing pad 3. The pad temperature adjusting member 11 is held by the vertical movement mechanism 71. The vertical movement mechanism 71 is configured to be able to move the pad temperature adjusting member 11 in the vertical direction with respect to the surface of the polishing pad 3. With such a configuration, the pad temperature adjusting member 11 can be in direct contact with the surface of the polishing pad 3 or close to the surface of the polishing pad 3. The vertical movement mechanism 71 includes a combination of a servo motor and a ball screw mechanism, or an air cylinder.

The pad temperature adjusting member 11 is configured to move perpendicularly to the surface of the polishing pad 3 to maintain a constant temperature in a region on the surface of the polishing pad 3 (a radial position of the polishing pad 3). ing. For example, the pad temperature adjusting member 11 is perpendicular to the surface of the polishing pad 3 so as to maintain the temperature at the radial position of the polishing pad 3 at a distance of 100 mm from the center CL of the polishing pad 3 at 60 degrees. Move in the direction. The user can arbitrarily determine (change) the surface temperature of the polishing pad 3 controlled by the pad temperature adjusting member 11 and the radial position of the polishing pad 3. For example, the user may change the distance from the center CL of the polishing pad 3 from 100 mm to 200 mm as the radial position of the polishing pad 3, and change the surface temperature of the polishing pad 3 from 60 degrees to 70 degrees. May be. As a result, the pad temperature adjusting member 11 is set against the surface of the polishing pad 3 so as to maintain the temperature at the radial position of the polishing pad 3 at a distance of 200 mm from the center CL of the polishing pad 3 at 70 degrees. Move up and down.

The fluid supply system 30 includes a fluid supply tank 31 as a fluid supply source that stores a temperature-adjusted fluid, a heating fluid supply pipe 32 that connects the fluid supply tank 31 and the pad temperature adjustment member 11, and a heating fluid return pipe 33. And. One end of the heating fluid supply pipe 32 and the heating fluid return pipe 33 is connected to the fluid supply tank 31, and the other end is connected to the pad temperature adjusting member 11.

The heated fluid whose temperature is adjusted is supplied from the fluid supply tank 31 to the pad temperature adjusting member 11 through the heated fluid supply pipe 32, flows in the pad temperature adjusting member 11, and passes from the pad temperature adjusting member 11 to the heated fluid return pipe 33. Returned to the fluid supply tank 31. Thus, the heating fluid circulates between the fluid supply tank 31 and the pad temperature adjusting member 11. The fluid supply tank 31 has a heater (not shown), and the heated fluid is heated to a predetermined temperature by the heater.

A first open / close valve 41 and a first flow control valve 42 are attached to the heated fluid supply pipe 32. The first flow rate control valve 42 is disposed between the pad temperature adjusting member 11 and the first opening / closing valve 41. The first on-off valve 41 is a valve that does not have a flow rate adjustment function, while the first flow rate control valve 42 is a valve that has a flow rate adjustment function.

The fluid supply system 30 further includes a cooling fluid supply pipe 51 and a cooling fluid discharge pipe 52 connected to the pad temperature adjusting member 11. The cooling fluid supply pipe 51 is connected to a cooling fluid supply source (for example, a cold water supply source) provided in a factory where the polishing apparatus is installed. The cooling fluid is supplied to the pad temperature adjusting member 11 through the cooling fluid supply pipe 51, flows through the pad temperature adjusting member 11, and is discharged from the pad temperature adjusting member 11 through the cooling fluid discharge pipe 52.

A second opening / closing valve 55 and a second flow rate control valve 56 are attached to the cooling fluid supply pipe 51. The second flow rate control valve 56 is disposed between the pad temperature adjusting member 11 and the second opening / closing valve 55. The second on-off valve 55 is a valve that does not have a flow rate adjustment function, whereas the second flow rate control valve 56 is a valve that has a flow rate adjustment function.

FIG. 2 is a schematic view showing another embodiment of the polishing apparatus. As shown in FIG. 2, one end of the cooling fluid supply pipe 51 and the cooling fluid discharge pipe 52 may be connected to the fluid supply tank 31, and the other end may be connected to the pad temperature adjusting member 11. In the present embodiment, the cooling fluid that circulates between the fluid supply tank 31 and the pad temperature adjusting member 11 is cooled in the fluid supply tank 31. Similarly, the heating fluid circulating between the fluid supply tank 31 and the pad temperature adjusting member 11 is heated in the fluid supply tank 31. In FIG. 2, the cooling fluid discharge pipe 52 is a cooling fluid return pipe.

Returning to FIG. 1, the pad temperature adjustment system 5 includes a pad temperature measuring device 39 that measures the surface temperature of the polishing pad 3 (hereinafter, also referred to as pad surface temperature), and the pad surface measured by the pad temperature measuring device 39. A PID control unit 40 that operates the first flow control valve 42 and the second flow control valve 56 based on the temperature is further provided. The first opening / closing valve 41 and the second opening / closing valve 55 are normally opened.

The pad temperature measuring device 39 is disposed above the surface of the polishing pad 3 and is configured to measure the surface temperature of the polishing pad 3 in a non-contact manner. The pad temperature measuring device 39 is connected to the PID control unit 40, and further connected to the temperature indicator 45 via the PID control unit 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, measures the surface temperature of the polishing pad 3, and acquires the temperature distribution of the polishing pad 3. It may be a thermography or a thermopile. The pad temperature measuring device 39 is at least one temperature measuring device among an infrared radiation thermometer, a thermocouple thermometer, a thermography, and a thermopile. If liquid (slurry or the like) splashed by polishing the wafer W adheres to the pad temperature measuring device 39, the pad temperature measuring device 39 may not be able to accurately measure the surface temperature of the polishing pad 3. Therefore, the pad temperature measuring device 39 is disposed at a sufficiently high position from the surface of the polishing pad 3.

3 is a view of the temperature measurement region of the pad temperature measurement device 39 as viewed from above, and FIG. 4 is a view of the temperature measurement region of the pad temperature measurement device 39 as viewed from the side. As shown in FIGS. 3 and 4, the pad temperature measuring device 39 is configured to measure the surface temperature of the polishing pad 3 in a region including the center CL of the polishing pad 3 and the outer peripheral portion 3 a of the polishing pad 3. (See dotted lines in FIGS. 3 and 4).

The pad temperature measuring device 39 measures the surface temperature of the polishing pad 3 in a non-contact manner, and sends the measured value of the surface temperature to the PID control unit 40. The pad temperature measuring device 39 may measure the surface temperature of the polishing pad 3 every predetermined time. The PID control unit 40 operates the first flow rate control valve 42 and the second flow rate control valve 56 based on the measured pad surface temperature so that the pad surface temperature is maintained at a preset target temperature. . The first flow rate control valve 42 and the second flow rate control valve 56 operate according to the control signal from the PID control unit 40 and adjust the flow rate of the heating fluid and the cooling fluid supplied to the pad temperature adjustment member 11. Heat exchange is performed between the heating fluid and the cooling fluid flowing through the pad temperature adjusting member 11 and the polishing pad 3, thereby changing the pad surface temperature.

温 Warm water is used as the heating fluid supplied to the pad temperature adjusting member 11. The hot water is heated to, for example, about 80 ° C. by the heater of the fluid supply tank 31. In order to increase the surface temperature of the polishing pad 3 more quickly, silicone oil may be used as a heating fluid. When silicone oil is used as the heating fluid, the silicone oil is heated to 100 ° C. or higher (for example, about 120 ° C.) by the heater of the fluid supply tank 31. As the cooling fluid supplied to the pad temperature adjusting member 11, cold water or silicone oil is used. When silicone oil is used as a cooling fluid, the polishing pad 3 can be quickly cooled by connecting a chiller as a cooling fluid supply source to the cooling fluid supply pipe 51 and cooling the silicone oil to 0 ° C. or lower. it can.

The heating fluid supply pipe 32 and the cooling fluid supply pipe 51 are completely independent pipes. Therefore, the heating fluid and the cooling fluid are simultaneously supplied to the pad temperature adjusting member 11 without being mixed. The heating fluid return pipe 33 and the cooling fluid discharge pipe 52 are also completely independent pipes. Therefore, the heating fluid is returned to the fluid supply tank 31 without being mixed with the cooling fluid, and the cooling fluid is discharged without being mixed with the heating fluid.

Next, an example of the pad temperature adjusting member 11 will be described with reference to FIG. FIG. 5 is a horizontal sectional view showing the pad temperature adjusting member 11. As shown in FIG. 5, the pad temperature adjustment member 11 is a heat exchange member having a heating channel 61 and a cooling channel 62 formed therein. The heating channel 61 and the cooling channel 62 extend adjacent to each other and extend in a spiral shape. In the present embodiment, the heating channel 61 is shorter than the cooling channel 62.

The heating fluid supply pipe 32 is connected to the inlet 61 a of the heating channel 61, and the heating fluid return pipe 33 is connected to the outlet 61 b of the heating channel 61. The cooling fluid supply pipe 51 is connected to the inlet 62 a of the cooling flow path 62, and the cooling fluid discharge pipe 52 is connected to the outlet 62 b of the cooling flow path 62. The inlets 61a and 62a of the heating channel 61 and the cooling channel 62 are located at the peripheral edge of the pad temperature adjusting member 11, and the outlets 61b and 62b of the heating channel 61 and the cooling channel 62 are pad temperature adjusting members. 11 is located in the center. Therefore, the heating fluid and the cooling fluid flow spirally from the peripheral portion of the pad temperature adjusting member 11 toward the central portion. The heating channel 61 and the cooling channel 62 are completely separated, and the heating fluid and the cooling fluid are not mixed in the pad temperature adjusting member 11. The shapes of the heating channel 61 and the cooling channel 62 are not limited to the embodiment shown in FIG. 5, and the pad temperature adjusting member 11 may have a zigzag heating channel and a cooling channel.

FIG. 6 is a plan view showing the positional relationship between the pad temperature adjusting member 11 on the polishing pad 3 and the polishing head 1. The pad temperature adjusting member 11 is circular when viewed from above, and the diameter of the pad temperature adjusting member 11 is smaller than the diameter of the polishing head 1. The distance from the center CL of the polishing pad 3 to the center of the pad temperature adjusting member 11 is the same as the distance from the center CL of the polishing pad 3 to the center of the polishing head 1. Since the heating channel 61 and the cooling channel 62 are adjacent to each other, the heating channel 61 and the cooling channel 62 are arranged not only in the radial direction of the polishing pad 3 but also in the circumferential direction of the polishing pad 3. Yes. Therefore, while the polishing table 2 and the polishing pad 3 are rotating, the pad temperature adjusting member 11 in contact with or close to the polishing pad 3 exchanges heat with both the heating fluid and the cooling fluid.

FIG. 7 is a schematic diagram showing the temperature indicator 45. As shown in FIG. 7, the pad temperature adjustment system 5 further includes a temperature indicator 45 that displays the surface temperature of the polishing pad 3 measured by the pad temperature measuring device 39. The PID control unit 40 is connected to the pad temperature measuring device 39 and the temperature indicator 45. The pad temperature measuring device 39 measures the surface temperature of the polishing pad 3 in the temperature measurement region, and the measured surface temperature of the polishing pad 3 is displayed on the temperature display 45. On the temperature display 45, the temperature of each surface position of the polishing pad 3 (that is, the surface position of the polishing pad 3 expressed in an orthogonal coordinate system) is displayed in a color and is easily displayed. For example, the surface position of the polishing pad 3 having a high temperature is represented in red, and the surface position of the polishing pad 3 having a low temperature is represented in blue. The temperature display 45 displays the surface temperature distribution of the polishing pad 3 as a color distribution.

The user may specify the measurement position of the polishing pad 3 on the temperature indicator 45, or may specify the measurement position of the polishing pad 3 by inputting coordinates. The temperature display 45 measures the temperature at the current measurement position of the specified polishing pad 3, the temperature at an arbitrary time, the time transition of the temperature, the temperature distribution of the polishing pad 3, the maximum temperature, the minimum temperature, and the average temperature. The time integral value of the selected temperature is displayed.

The PID control unit 40 operates the first flow control valve 42 and the second flow control valve 56 in order to eliminate the difference between the preset target temperature and the measured surface temperature of the polishing pad 3. Configured to calculate quantity. The operation amount of the first flow control valve 42 and the operation amount of the second flow control valve 56 are, in other words, the valve opening. The operation amount of the first flow rate control valve 42 is proportional to the flow rate of the heating fluid, and the operation amount of the second flow rate control valve 56 is proportional to the flow rate of the cooling fluid.

When the operation amounts of the first flow control valve 42 and the second flow control valve 56 are expressed by numerical values from 0% to 100%, the PID control unit 40 sets the operation amount of the first flow control valve 42 to 100. The operation amount of the second flow control valve 56 is determined by subtracting from%. In one embodiment, the PID control unit 40 may determine the operation amount of the first flow control valve 42 by subtracting the operation amount of the second flow control valve 56 from 100%.

The operation amount of the first flow control valve 42 being 100% indicates that the first flow control valve 42 is fully open, and the operation amount of the first flow control valve 42 is 0%. It shows that the flow control valve 42 is completely closed. Similarly, the operation amount of the second flow rate control valve 56 being 100% indicates that the second flow rate control valve 56 is fully open, and the operation amount of the second flow rate control valve 56 is 0%. , Indicating that the second flow control valve 56 is completely closed.

The flow rate of the heating fluid when the operation amount of the first flow control valve 42 is 100% is the same as the flow rate of the cooling fluid when the operation amount of the second flow control valve 56 is 100%. Therefore, the sum of the flow rate of the heating fluid passing through the first flow rate control valve 42 and the flow rate of the cooling fluid passing through the second flow rate control valve 56 is always constant.

The PID control unit 40 includes the first flow control valve 42 and the second flow control valve 56 so that the sum of the operation amount of the first flow control valve 42 and the operation amount of the second flow control valve 56 becomes 100%. To operate.

According to the present embodiment, only the heating fluid flows in the heating flow path 61 of the pad temperature adjusting member 11, and only the cooling fluid flows in the cooling flow path 62. The respective flow rates of the heating fluid and the cooling fluid are controlled based on the surface temperature of the polishing pad 3. That is, the first flow rate control valve 42 and the second flow rate control valve 56 are operated by the PID control unit 40 based on the difference between the surface temperature of the polishing pad 3 and the target temperature. Therefore, the surface temperature of the polishing pad 3 can be stably maintained at the target temperature.

FIG. 8 is a view showing another embodiment of the pad temperature adjusting member 11. Since the configuration and operation of the present embodiment that are not particularly described are the same as those of the above-described embodiment, redundant description thereof is omitted. As shown in FIG. 8, the pad temperature adjusting member 11 is a cooling nozzle that sprays a cooling fluid onto the surface of the polishing pad 3. In the present embodiment, a cooling gas such as air or an inert gas (for example, nitrogen gas) is used as the cooling fluid. A cooling channel 12 through which a cooling fluid flows is formed inside the pad temperature adjusting member 11 that is a cooling nozzle. The cooling flow path 12 is connected to the cooling fluid supply pipe 51 and the injection port of the pad temperature adjusting member 11. When the cooling fluid is supplied to the pad temperature adjusting member 11 through the cooling fluid supply pipe 51, the cooling fluid is supplied from the ejection port of the pad temperature adjusting member 11 onto the surface of the polishing pad 3. A flow rate control valve 56 for controlling the flow rate of the cooling fluid supplied from the pad temperature adjusting member 11 onto the surface of the polishing pad 3 is attached to the cooling fluid supply pipe 51. In this embodiment, no heating fluid is used.

When the pad temperature adjusting member 11 is a heat exchange member (see FIG. 5), the PID control unit 40 operates the flow rate control valves 42 and 56 during polishing of the wafer W, thereby adjusting the surface temperature of the polishing pad 3. Can be changed. When the pad temperature adjusting member 11 is a cooling nozzle (see FIG. 8), the PID control unit 40 changes the surface temperature of the polishing pad 3 by operating the flow rate control valve 56 during polishing of the wafer W. Can do.

The pad temperature measuring device 39 measures the surface temperature of the polishing pad 3 when the wafer W is being polished, and sends the measured value of the surface temperature to the PID control unit 40. The PID control unit 40 is configured to acquire a measured value of the surface temperature of the polishing pad 3 from the pad temperature measuring device 39 and calculate a PID parameter based on a temporal change in the surface temperature of the polishing pad 3.

The PID parameter is calculated based on the time change of the surface temperature of the polishing pad 3 using any one of the limit cycle method, the step response method, and the limit sensitivity method of Ziegler Nichols. PID parameters calculated by these methods may be adjusted based on fuzzy inference, and PID parameters are calculated using a two-degree-of-freedom PID method that can optimize both target value tracking and disturbance suppression. May be.

The PID control unit 40 uses a PID arithmetic expression (described later) having a PID parameter calculated by the above method to minimize the deviation between the temperature target value of the polishing pad 3 and the measured value of the surface temperature. The operation amounts of the flow control valves 42 and 56 are calculated. The PID control unit 40 operates the flow rate control valves 42 and 56 according to the calculated operation amount during polishing of the wafer W.

The PID control unit 40 is configured to automatically calculate PID parameters during polishing of the wafer W. Hereinafter, a limit cycle method, which is an example of a method for calculating PID parameters, will be described with reference to the drawings.

FIG. 9 is a diagram for explaining the limit cycle method. In FIG. 9, symbol PV indicates a measured value of the surface temperature of the polishing pad 3, symbol MV indicates an operation amount of the flow rate control valves 42 and 56, and symbol SV indicates a temperature target of the surface temperature of the polishing pad 3. The value is shown. In the graph showing the relationship between the measured value PV and time in FIG. 9 (upper graph in FIG. 9), the vertical axis indicates the measured value PV, and the horizontal axis indicates time. In the graph showing the relationship between the operation amount MV of the flow control valves 42 and 56 in FIG. 9 and time (the lower graph in FIG. 9), the vertical axis shows the operation amount MV of the flow control valves 42 and 56. The horizontal axis indicates time.

The operation amount of the flow control valves 42 and 56 is determined so that the flow control valves 42 and 56 are fully opened and fully closed. More specifically, when the first flow control valve 42 is fully open (operation amount 100%), the second flow control valve 56 is fully closed (operation amount 0%). Further, when the second flow control valve 56 is fully opened (operation amount 100%), the first flow control valve 42 is fully closed (operation amount 0%). As described above, the operation in which the flow control valves 42 and 56 are repeatedly fully opened and fully closed is called a two-position operation of the flow control valves 42 and 56.

The control of the two-position operation of the flow control valves 42 and 56 will be described with reference to FIG. FIG. 10 is a view showing the two-position operation of the flow control valves 42 and 56. In FIG. 10, the vertical axis represents the operation amount MV of the flow control valves 42 and 56, and the horizontal axis represents the deviation e. When the operation amount of the first flow control valve 42 is 0% and the operation amount of the second flow control valve 56 is 100%, the operation amounts of the flow control valves 42 and 56 are -M. When the operation amount of the first flow control valve 42 is 100% and the operation amount of the second flow control valve 56 is 0%, the operation amounts of the flow control valves 42 and 56 are + M.

As shown in FIG. 9, when the measured value PV is higher than the temperature target value SV, the PID control unit 40 fully closes the first flow rate control valve 42 with an operation amount of 0% and sets the second flow rate control valve 56. The surface temperature of the polishing pad 3 is lowered by fully opening at an operation amount of 100%. When the measured value PV is lower than the temperature target value SV, the PID control unit 40 fully opens the first flow rate control valve 42 with an operation amount of 100% and fully closes the second flow rate control valve 56 with an operation amount of 0%. Thus, the surface temperature of the polishing pad 3 is raised. In other words, when the measured value PV is higher than the temperature target value SV, the PID control unit 40 outputs the cooling side operation amount −M, and when the measured value PV is lower than the temperature target value SV, the PID control unit 40 operates the heating side. Output amount + M. As described above, the PID control unit 40 repeatedly opens and closes the flow rate control valves 42 and 56 to periodically change the surface temperature of the polishing pad 3. Such a periodic temperature change is called a limit cycle waveform. The cycle of the limit cycle waveform to be generated may be 2 to 3 cycles.

Since the surface temperature of the polishing pad 3 gradually increases as the polishing of the wafer W progresses, the PID control unit 40 can also repeat opening and closing the flow control valve 56 with the first opening and closing valve 41 closed. Limit cycle waveforms can be generated. That is, when the measured value PV is higher than the temperature target value SV, the PID control unit 40 fully opens the flow control valve 56 at an operation amount of 100%, and when the measured value PV is lower than the temperature target value SV, the flow control valve 56. May be fully closed with an operation amount of 0%.

When the pad temperature adjusting member 11 is a cooling nozzle, the PID control unit 40 can generate a limit cycle waveform by controlling the flow rate of the cooling fluid supplied onto the surface of the polishing pad 3. That is, when the measured value PV is higher than the temperature target value SV, the PID control unit 40 opens the flow rate control valve 56 and supplies the cooling fluid onto the surface of the polishing pad 3. When the measured value PV is lower than the temperature target value SV, the PID control unit 40 fully closes the flow rate control valve 56 and stops the supply of the cooling fluid to the surface of the polishing pad 3.

The PID control unit 40 determines the surface temperature amplitude X and the dead time Lt of the polishing pad 3 based on the generated limit cycle waveform. The dead time Lt is obtained as a time difference L1 from the time when the first flow rate control valve 42 is fully closed and the second flow rate control valve 56 is fully opened to the time when the pad surface temperature starts to decrease. Is obtained by dividing the sum of the time difference L1 and the time difference L by 2 from the time when the second flow control valve 56 is fully closed to the time when the pad surface temperature starts to rise. . That is, the dead time Lt can be determined from the following equation (1).
Lt = (L1 + L2) / 2 (1)

As the amplitude X, a difference (absolute value) A1 between the temperature target value SV of the polishing pad 3 and the maximum value of the pad surface temperature is calculated, and the difference between the temperature target value SV of the polishing pad 3 and the minimum value of the pad surface temperature ( (Absolute value) A2 is calculated, and the sum of the difference A1 and the difference A2 is divided by 2. That is, the amplitude X can be determined from the following equation (2).
X = (A1 + A2) / 2 (2)

The PID control unit 40 calculates the limit sensitivity Kc and the limit period Tc using the amplitude M of the manipulated variable of the flow control valves 42 and 56, the amplitude X of the surface temperature of the polishing pad 3, and the dead time Lt, respectively. The limit sensitivity Kc is obtained by using the following formula (3), and the limit period Tc is obtained by using the following formula (4).
Kc = 4 × M / (π × X) (3)
Tc = 4 × Lt (4)

The PID control unit 40 calculates PID parameters from the calculated limit sensitivity Kc and limit period Tc. The PID parameter is a parameter necessary for PID control of the flow rate control valves 42 and 56, and includes a proportional gain Kp, an integration time Ti, and a differentiation time Td. Hereinafter, a method for calculating the PID parameter will be described.

FIG. 11 is a diagram showing an example of coefficients used for calculating PID parameters. FIG. 11 shows coefficients used for calculation of PID parameters (and PI parameters) in the control rules of the fixed value control direction (Ziegler and Nichols) and the follow-up control direction (Chien, Herones, and Rewick). Note that the coefficient for calculating the PID parameter is not limited to the numerical values shown in FIG. These coefficients are determined in advance according to the polishing conditions of the wafer W. A PID parameter (that is, proportional gain Kp, integration time Ti, and differentiation time Td) can be calculated by multiplying the predetermined coefficient, the limit sensitivity Kc, and the limit period Tc, respectively.

As described above, the PID control unit 40 uses the PID arithmetic expression including the calculated PID parameter to minimize the deviation between the temperature target value SV and the measured value PV of the surface temperature of the polishing pad 3. The operation amounts of the flow control valves 42 and 56 are calculated. The PID formula is

It can be expressed as.

FIG. 12 is a diagram showing a feedback control system when calculating PID parameters. As shown in FIG. 12, with respect to the deviation e between the measured value PV and the temperature target value SV, the two-position operation of the flow rate control valves 42 and 56 is performed based on the deviation e as the non-linear element N (X). An input to the control object P (jω) for minimizing the deviation e, that is, an operation amount MV of the flow control valves 42 and 56 is calculated. In this way, the PID control unit 40 operates the flow rate control valves 42 and 56 to maintain the surface temperature of the polishing pad 3 at a desired target temperature.

In the present embodiment, the PID control unit 40 is configured by a dedicated computer or a general-purpose computer. FIG. 13 is a schematic diagram illustrating a configuration of the PID control unit 40. The PID control unit 40 includes a storage device 110 that stores programs and data, a processing device 120 such as a CPU (central processing unit) that performs operations according to programs stored in the storage device 110, data, programs, and An input device 130 for inputting various information to the storage device 110, an output device 140 for outputting processing results and processed data, and a communication device 150 for connecting to a network such as the Internet are provided.

The storage device 110 includes a main storage device 111 accessible by the processing device 120 and an auxiliary storage device 112 that stores data and programs. The main storage device 111 is, for example, a random access memory (RAM), and the auxiliary storage device 112 is a storage device such as a hard disk drive (HDD) or a solid state drive (SSD).

The input device 130 includes a keyboard and a mouse, and further includes a recording medium reading device 132 for reading data from the recording medium and a recording medium port 134 to which the recording medium is connected. The recording medium is a non-transitory tangible computer-readable recording medium, such as an optical disc (eg, CD-ROM, DVD-ROM) or semiconductor memory (eg, USB flash drive, memory card). is there. Examples of the recording medium reading device 132 include an optical drive such as a CD drive and a DVD drive, and a card reader. An example of the recording medium port 134 is a USB terminal. The program and / or data recorded on the recording medium is introduced into the PID control unit 40 via the input device 130 and stored in the auxiliary storage device 112 of the storage device 110. The output device 140 includes a display device 141 and a printing device 142. The printing device 142 may be omitted. The temperature indicator 45 described above may be used as a display device for the PID control unit 40. In this case, the display device 141 may be omitted.

The PID control unit 40 operates according to a program electrically stored in the storage device 110. FIG. 14 is a flowchart showing the operation steps of the PID control unit 40 that operates according to a program. The PID control unit 40 instructs the polishing head 1 to cause the polishing head 1 to perform an operation of pressing the wafer W against the surface of the polishing pad 3 to polish the wafer W (see Step 1 in FIG. 14). During polishing of the wafer W, the step of changing the surface temperature of the polishing pad 3 by operating the flow rate control valves 42 and 56 (see step 2 of FIG. 14) and the operation of measuring the surface temperature of the polishing pad 3 are performed. Based on the step of causing the pad temperature measuring device 39 to execute the measurement of the surface temperature of the polishing pad 3 (see Steps 3 and 4 in FIG. 14) and the time variation of the surface temperature of the polishing pad 3, Using the step of calculating (see step 5 in FIG. 14) and the PID calculation formula including the PID parameter, the temperature target value SV and the surface temperature of the polishing pad 3 A step of calculating an operation amount of the flow control valves 42 and 56 for minimizing a deviation from the constant value PV (see step 6 in FIG. 14), and a step of operating the flow control valves 42 and 56 based on the operation amount (See step 7 in FIG. 14).

The program for causing the PID control unit 40 to execute these steps is recorded on a computer-readable recording medium that is a non-temporary tangible material and provided to the PID control unit 40 via the recording medium. Alternatively, the program may be provided to the PID control unit 40 via a communication network such as the Internet.

Next, a step response method, which is another example of a method for calculating PID parameters, will be described with reference to the drawings. FIG. 15 is a diagram for explaining the step response method. In FIG. 15, symbol PV indicates a measured value of the surface temperature of the polishing pad 3, and symbol MV indicates an operation amount of the flow rate control valves 42 and 56. The vertical axis in FIG. 15 indicates the measured value PV and the manipulated variable MV, and the horizontal axis in FIG. 15 indicates time.

As shown in FIG. 15, the PID control unit 40 switches the first flow rate control valve 42 from fully closed to fully open, and switches the second flow rate control valve 56 from fully open to fully closed, so that the surface temperature of the polishing pad 3 is increased. Change. The pad temperature measuring device 39 measures the surface temperature of the polishing pad 3 at this time and sends it to the PID control unit 40. The PID control unit 40 acquires this measurement value from the pad temperature measuring device 39, calculates the slope R of the tangent TL of the curve indicating the time change of the surface temperature of the polishing pad 3, and calculates the slope R of the tangent TL and the dead time Lt. , And a time constant τ. The curve of the measured value PV shown in FIG. 15 is called a process reaction curve.

The PID control unit 40 can also generate a process reaction curve by switching the second flow rate control valve 56 from fully open to fully closed while the first opening / closing valve 41 is closed. Even when the pad temperature adjusting member 11 is a cooling nozzle, the PID control unit 40 can generate a process reaction curve by controlling the flow rate of the cooling fluid supplied onto the surface of the polishing pad 3. That is, the PID control unit 40 can generate a process reaction curve by switching the flow control valve 56 from fully open to fully closed.

As shown in FIG. 15, the tangent TL indicates the process reaction when the measured value PV increases to a predetermined value (63% in the present embodiment) when the measured value PV is represented by a value from 0% to 100%. It is a tangent line passing through the point P1 on the curve. The slope R is obtained based on the tangent line TL. The dead time Lt is obtained by calculating the time difference from the time when the first flow control valve 42 is fully opened to the time at the intersection P2 between the tangent TL and the horizontal axis. The time constant τ is obtained by calculating the time difference from the time at the intersection P2 to the time corresponding to the point P1.

The PID control unit 40 calculates the PID parameter using the slope R of the tangent line TL, the dead time Lt, and the time constant τ. More specifically, the proportional gain Kp can be obtained by using the following equation (6).
Kp = a / (R × Lt) (6)

The integration time Ti can be obtained by using the following formula (7) or the following formula (8).
Ti = b × Lt (7)
Ti = b × τ (8)

The differential time Td can be obtained by using the following formula (9).
Td = c × Lt (9)
Here, the coefficients a, b, and c in the above equations (6) to (9) are predetermined numerical values, for example, the coefficient a is 1.2, the coefficient b is 2.0, and the coefficient c is 0. .5.

The PID control unit 40 minimizes the deviation between the temperature target value SV and the measured value PV of the surface temperature of the polishing pad 3 using the PID calculation formula (see the above formula (5)) having the calculated PID parameter. The amount of operation of the flow control valves 42 and 56 is calculated.

Next, the Ziegler-Nichols limit sensitivity method, which is still another example of the method for calculating the PID parameter, will be described with reference to the drawings. FIG. 16 is a diagram for explaining the limit sensitivity method of Ziegler-Nichols. In FIG. 16, symbol PV indicates a measured value of the surface temperature of the polishing pad 3, symbol SV indicates a temperature target value of the surface temperature of the polishing pad 3, and symbol Pu indicates a period of a limit gain. . The curve Kp1 is a control curve of the measured value PV by the first gain, the curve Kp2 is a control curve of the measured value PV by the second gain larger than the first gain Kp1, and the curve Kp3 is the second gain Kp2. It is a control curve of the measured value PV with a larger third gain (Kp1 <Kp2 <Kp3). The vertical axis in FIG. 16 indicates the measured value PV, and the horizontal axis in FIG. 16 indicates time.

The PID control unit 40 increases the first gain Kp1, the second gain Kp2, and the third gain Kp3 in this order in a state where the integration time Ti and the differentiation time Td are invalidated, and the temperature target value SV Hunting (waveform of measured value PV) is generated between measured values PV. In one embodiment, the gain value is increased by ten. In FIG. 16, hunting occurs when the third gain Kp3 is output. The third gain Kp3 is determined as the limit gain Ku.

The PID control unit 40 calculates the period Pu of the limit gain Ku. The PID control unit 40 calculates PID parameters (proportional gain Kp, integration time Ti, derivative time Td) using the limit gain Ku and the period Pu. More specifically, the proportional gain Kp can be obtained by using the following equation (10), the integration time Ti can be obtained by using the following equation (11), and the differential time Td can be obtained by the following equation (12). ) Can be used.
Kp = a × Ku (10)
Ti = b × Pu (11)
Td = c × Pu (12)
Here, the coefficients a, b, and c in the above equations (10) to (12) are predetermined numerical values, for example, the coefficient a is 0.6, the coefficient b is 0.5, and the coefficient c is 0. .125.

The PID control unit 40 minimizes the deviation between the temperature target value SV and the measured value PV of the surface temperature of the polishing pad 3 using the PID calculation formula (see the above formula (5)) having the calculated PID parameter. The amount of operation of the flow control valves 42 and 56 is calculated.

According to the present embodiment, the PID control unit 40 can automatically calculate the PID parameter based on the temporal change in the surface temperature of the polishing pad 3 during the polishing of the wafer W, and therefore determines the PID parameter. For this reason, trial and error experiments, special knowledge, experience, and know-how are not necessary, and there is no need to rely on skilled workers. Therefore, the PID parameter can be determined efficiently in a short time. Furthermore, according to the present embodiment, time and personnel can be significantly reduced, and thus costs can be reduced.

The PID control unit 40 is configured to execute a simulation of the surface temperature of the polishing pad 3 that is expected as a result of operating the flow control valves 42 and 56 with the operation amount calculated using the PID arithmetic expression described above. . The surface position of the polishing pad 3 on which the simulation result is displayed is arbitrarily determined by the user, and the PID control unit 40 executes the simulation based on the PID parameter and the temperature target value SV.

Furthermore, the PID control unit 40 is configured to further execute a simulation showing the time transition of the surface temperature of the polishing pad 3 expected when the temperature target value SV is changed. FIG. 17 is a diagram showing simulation results showing the time transition of the surface temperature of the polishing pad 3. As shown in FIG. 17, the simulation result of the time transition of the surface temperature of the polishing pad 3 is displayed on the temperature display 45. The surface position of the polishing pad 3 on which the simulation result is displayed is arbitrarily determined by the user.

Since an appropriate PID parameter is different for each polishing process of the wafer W, the PID control unit 40 is configured to automatically determine the PID parameter for each polishing process of the wafer W. The polishing process of the wafer W is changed depending on, for example, the film thickness of the wafer W, the polishing pad, and the type of slurry.

FIG. 18 is a flowchart showing how the PID parameters are calculated for each wafer W polishing process. First, in order to calculate an appropriate PID parameter, one wafer W is polished by using any one of a limit cycle method, a step response method, and a Ziegler-Nichols limit sensitivity method (step 1 in FIG. 18). reference). At this time, the wafer W is polished according to a polishing recipe for calculating PID parameters. When the limit cycle method is used, the temperature target value SV when polishing one wafer W is the same as the temperature target value when polishing the wafer W in an actual polishing process.

The most appropriate PID parameter is calculated from the limit cycle method, the step response method, and the Ziegler-Nichols limit sensitivity method (see step 2 in FIG. 18), and polishing of the wafer W reflecting the calculated PID parameter is executed (see FIG. 18). (See Step 3 in FIG. 18). When the wafer W is polished by a polishing process different from the polishing process at the time of polishing the wafer W, one wafer W is polished again, and the most appropriate PID parameter is calculated (see step 4 in FIG. 18). ). When only the temperature target value SV of the polishing pad 3 is changed, the PID control unit 40 may execute a simulation of the expected surface temperature of the polishing pad 3 (see Step 5 in FIG. 18). In this case, the temperature indicator 45 includes the time from the operation of the flow rate control valves 42 and 56 to the change of the surface temperature of the polishing pad 3 and the magnitude of the overshoot caused in the change of the surface temperature of the polishing pad 3. The deviation between the temperature target value SV and the measured value PV, and the magnitude of hunting generated in the waveform of the measured value PV of the surface temperature of the polishing pad 3 may be displayed.

The above-described embodiments are described for the purpose of enabling the person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in the widest scope according to the technical idea defined by the claims.

The present invention can be used for a polishing method for polishing a substrate such as a wafer, a polishing apparatus, and a recording medium on which a computer program for controlling the surface temperature of a polishing pad of the polishing apparatus is recorded.

DESCRIPTION OF SYMBOLS 1 Polishing head 2 Polishing table 3 Polishing pad 4 Polishing liquid supply nozzle 5 Pad temperature adjustment system 11 Pad temperature adjustment member 20 Dresser 30 Fluid supply system 31 Fluid supply tank 32 Heating fluid supply pipe 33 Heating fluid return pipe 39 Pad temperature measuring device 40 PID control unit 41 First on-off valve 42 First flow control valve 45 Temperature indicator 51 Cooling fluid supply pipe 52 Cooling fluid discharge pipe 55 Second on-off valve 56 Second flow control valve 61 Heating flow path 62 Cooling flow path 71 Vertical movement Mechanism (vertical movement mechanism)
110 Storage Device 120 Processing Device 130 Input Device 140 Output Device 150 Communication Device

Claims (18)

1. Polishing the substrate by pressing the substrate against the surface of the polishing pad;
   By operating a flow rate control valve for controlling the flow rate of the fluid flowing to the pad temperature adjusting member during polishing of the substrate, the surface temperature of the polishing pad is changed,
   Measuring the surface temperature of the polishing pad;
   Based on the time change of the surface temperature of the polishing pad, PID parameters are calculated,
   Calculate the manipulated variable of the flow rate control valve to minimize the deviation between the temperature target value and the measured value of the surface temperature of the polishing pad, using a PID arithmetic expression having the PID parameter,
   A polishing method, wherein the flow rate control valve is operated according to the operation amount during polishing of the substrate.
2. 2. The polishing method according to claim 1, wherein the step of measuring the surface temperature of the polishing pad includes a step of measuring a temperature distribution in a region including a center and an outer peripheral portion of the polishing pad.
3. The step of changing the surface temperature of the polishing pad controls the flow rate of the fluid flowing through the pad temperature adjusting member by bringing the pad temperature adjusting member into contact with or close to the surface of the polishing pad during polishing of the substrate. 2. The polishing method according to claim 1, wherein the polishing step is a step of changing a surface temperature of the polishing pad by operating a flow rate control valve.
4. The step of changing the surface temperature of the polishing pad is performed by operating a flow rate control valve for controlling the flow rate of the fluid supplied from the pad temperature adjusting member onto the surface of the polishing pad during polishing of the substrate. The polishing method according to claim 1, wherein the polishing method is a step of changing a surface temperature of the polishing pad.
5. The polishing method according to claim 1, wherein the fluid is a heating fluid and a cooling fluid.
6. The step of calculating the PID parameter is to calculate the PID parameter based on the time change of the surface temperature of the polishing pad using any one of a limit cycle method, a step response method, and a limit sensitivity method of Ziegler Nichols. The polishing method according to claim 1, wherein the polishing method is a step of:
7. The polishing method according to claim 1, wherein a simulation of a surface temperature of the polishing pad expected as a result of operating the flow rate control valve with an operation amount calculated using the PID arithmetic expression is executed.
8. 8. The polishing method according to claim 7, further comprising executing a simulation showing a time transition of the surface temperature of the polishing pad expected when the temperature target value is changed.
9. A polishing table that supports the polishing pad;
   A polishing head for pressing a substrate against the polishing pad;
   A pad temperature adjustment system for adjusting the surface temperature of the polishing pad;
   The pad temperature adjustment system includes:
   A pad temperature adjusting member having a flow path through which the fluid flows;
   A fluid supply pipe connected to the flow path;
   A flow control valve attached to the fluid supply pipe;
   A pad temperature measuring device for measuring the surface temperature of the polishing pad;
   A PID control unit for operating the flow rate control valve,
   The PID control unit
   During polishing of the substrate, the flow control valve is operated to change the surface temperature of the polishing pad,
   Obtaining a measured value of the surface temperature of the polishing pad from the pad temperature measuring device;
   Based on the time change of the surface temperature of the polishing pad, PID parameters are calculated,
   Calculate the manipulated variable of the flow rate control valve to minimize the deviation between the temperature target value and the measured value of the surface temperature of the polishing pad, using a PID arithmetic expression having the PID parameter,
   A polishing apparatus, wherein the flow rate control valve is operated according to the operation amount.
10. The polishing apparatus according to claim 9, wherein the pad temperature measuring device is at least one temperature measuring device selected from an infrared radiation thermometer, a thermocouple thermometer, a thermography, and a thermopile.
11. The polishing apparatus according to claim 9, wherein the pad temperature measuring device is configured to measure a temperature distribution in a region including a center and an outer peripheral portion of the polishing pad.
12. 10. The polishing apparatus according to claim 9, wherein the pad temperature adjusting system further includes a temperature indicator for displaying a surface temperature of the polishing pad measured by the pad temperature measuring device.
13. The polishing apparatus according to claim 9, wherein the pad temperature adjusting member is a cooling nozzle that sprays a cooling fluid onto a surface of the polishing pad.
14. 10. The polishing apparatus according to claim 9, wherein the pad temperature adjusting member has a pad contact surface capable of contacting the surface of the polishing pad.
15. The polishing apparatus according to claim 9, wherein the PID control unit calculates a PID parameter using any one of a limit cycle method, a step response method, and a Ziegler-Nichols limit sensitivity method.
16. The PID control unit is configured to execute a simulation of a surface temperature of the polishing pad expected as a result of operating the flow rate control valve with an operation amount calculated using the PID arithmetic expression. The polishing apparatus according to claim 9.
17. The said PID control part is comprised so that it may further perform the simulation which shows the time transition of the surface temperature of the said polishing pad anticipated when the said temperature target value is changed, It is characterized by the above-mentioned. Polishing equipment.
18. Giving a command to the polishing head, causing the polishing head to perform an operation of pressing the substrate against the surface of the polishing pad and polishing the substrate;
    Changing the surface temperature of the polishing pad by operating a flow rate control valve provided to control the flow rate of the fluid flowing through the pad temperature adjusting member;
    Obtaining a measured value of the surface temperature of the polishing pad;
    Calculating a PID parameter based on time variation of the surface temperature of the polishing pad;
    Calculating a manipulated variable of the flow control valve for minimizing a deviation between a temperature target value and a measured value of the surface temperature of the polishing pad, using a PID arithmetic expression having the PID parameter;
    A non-transitory computer-readable recording medium recording a program for causing a computer to execute the step of operating the flow control valve according to the operation amount.

Images