Polishing method and polishing apparatus

Abstract

To provide a polishing method that enables fluid to flow out through an upper surface of a wafer and enables a polishing head to apply proper force to the wafer.SOLUTION: A polishing method for a wafer W, which uses a polishing head 1 having a plurality of pressure chambers formed of elastic films 34, performs steps of: forming positive pressure in the first pressure chamber and forming negative pressure in the second pressure chamber positioned outside the first pressure chamber; forming positive pressure in the second pressure chamber and forming negative pressure in a third pressure chamber positioned outside the second pressure chamber, after moving fluid Q existing between an upper surface of the wafer W and the first pressure chamber to the outside; and polishing a lower surface of the wafer W while making the elastic films 34 press the lower surface of the wafer W against a polishing surface 2a, after moving the fluid Q existing between the upper surface of the wafer W and the second pressure chamber to the outside, forming positive pressure in the pressure chamber positioned at the outermost side, of the plurality of pressure chambers, and flowing out the fluid Q through the upper surface of the wafer W.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a technique for polishing a wafer by causing fluid to flow out from the upper surface of the wafer.

Background Art

[0002] Chemical mechanical polishing (CMP) is a technique for polishing the surface of a wafer by supplying a polishing liquid onto the polishing surface, pressing the wafer against the polishing surface, and causing the wafer to slide in contact with the polishing surface in the presence of the polishing liquid. During wafer polishing, the wafer is pressed against the polishing surface by a polishing head. The surface of the wafer is planarized by the chemical action of the polishing liquid and the mechanical action of abrasive grains contained in the polishing liquid and / or the polishing pad.

[0003] FIG. 12 is a cross-sectional view schematically showing a polishing head 100. The polishing head 100 has an elastic film 110 that contacts the upper surface of a wafer W1. This elastic film 110 has a shape that forms a plurality of pressure chambers 101 to 104, and the pressure in each of the pressure chambers 101 to 104 can be independently adjusted. Therefore, the polishing head 100 can press a plurality of regions of the wafer W1 corresponding to these pressure chambers 101 to 104 with different forces, and can achieve a desired film thickness profile of the wafer W1.

[0004] When the polishing of the wafer W1 is completed, the polished wafer W1 is conveyed to the next process by a conveying device. As shown in FIG. 13, the next wafer W2 is carried to a delivery position below the polishing head 100 by the conveying device. At the same time, the polishing head 100 is washed with a liquid (e.g., pure water) supplied from a washing nozzle 115, and the polishing liquid and polishing debris are removed from the polishing head 100. Then, the next wafer W2 is held by the polishing head 100 and conveyed to a position above the polishing surface by the polishing head 100. The wafer W2 is pressed against the polishing surface by the polishing head 100 and polished in the presence of the polishing liquid.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-131414 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, as shown in Figure 14, a fluid Q, such as the liquid used to clean the polishing head 100 or air, may be present between the top surface of the wafer W2 and the elastic film 110 of the polishing head 100. If fluid Q is present between the top surface of the wafer W2 and the polishing head 100, the polishing head 100 cannot properly apply force to multiple regions of the wafer W2 corresponding to pressure chambers 101 to 104. For example, if fluid Q is spread across multiple pressure chambers, the pressure in the adjacent pressure chamber is transmitted to fluid Q, and an unintended force is applied to the wafer W2. In the example shown in Figure 14, even though the pressure in the central pressure chamber 101 is reduced to lower the polishing rate of the central part of the wafer W2, the pressure in the adjacent pressure chamber 102 is applied to the central part of the wafer W2 via fluid Q. As a result, the wafer W 2 The polishing rate in the central part cannot be reduced. Thus, the fluid Q present between the wafer W2 and the polishing head 100 prevents the polishing head 100 from applying the appropriate force to the wafer W2.

[0007] Therefore, the present invention provides a polishing method and polishing apparatus that allows a fluid to flow out from the upper surface of the wafer, enabling the polishing head to apply appropriate force to the wafer. [Means for solving the problem]

[0008] In one embodiment, a method for polishing a wafer is provided using a polishing head having a plurality of pressure chambers formed by an elastic film, wherein the plurality of pressure chambers include a first pressure chamber, a second pressure chamber located outside the first pressure chamber, and a third pressure chamber located outside the second pressure chamber, wherein a positive pressure is formed in the first pressure chamber and a negative pressure is formed in the second pressure chamber to move the fluid present between the upper surface of the wafer and the first pressure chamber outward, then a positive pressure is formed in the second pressure chamber and a negative pressure is formed in the third pressure chamber to move the fluid present between the upper surface of the wafer and the second pressure chamber outward, a positive pressure is formed in the outermost pressure chamber of the plurality of pressure chambers to move the fluid present between the upper surface of the wafer and the outermost pressure chamber outward, causing the fluid to flow out from the upper surface of the wafer, and then the lower surface of the wafer is pressed against a polishing surface with the elastic film to polish the lower surface of the wafer.

[0009] In one embodiment, the timing at which the positive pressure is formed in the first pressure chamber is the same as the timing at which the negative pressure is formed in the second pressure chamber, and the timing at which the positive pressure is formed in the second pressure chamber is the same as the timing at which the negative pressure is formed in the third pressure chamber. In one embodiment, forming the negative pressure in the second pressure chamber includes lowering the pressure in the second pressure chamber to a negative pressure setpoint, and then opening the second pressure chamber to the atmosphere, and forming the negative pressure in the third pressure chamber includes lowering the pressure in the third pressure chamber to a negative pressure setpoint, and then opening the third pressure chamber to the atmosphere.

[0010] In one embodiment, the timing at which the negative pressure is formed in the second pressure chamber is earlier than the timing at which the positive pressure is formed in the first pressure chamber, and the timing at which the negative pressure is formed in the third pressure chamber is earlier than the timing at which the positive pressure is formed in the second pressure chamber. In one embodiment, forming the negative pressure in the second pressure chamber includes lowering the pressure in the second pressure chamber to a negative pressure setpoint and then eliminating the negative pressure in the second pressure chamber; forming the positive pressure in the first pressure chamber is performed while the negative pressure in the second pressure chamber is being eliminated; forming the negative pressure in the third pressure chamber includes lowering the pressure in the third pressure chamber to a negative pressure setpoint and then eliminating the negative pressure in the third pressure chamber; and forming the positive pressure in the second pressure chamber is performed while the negative pressure in the third pressure chamber is being eliminated.

[0011] In one embodiment, the first pressure chamber is located in the central part of the elastic membrane. In one embodiment, forming the positive pressure in the first pressure chamber includes raising the pressure in the first pressure chamber to a first positive pressure setpoint and then maintaining the pressure in the first pressure chamber at the first positive pressure setpoint, and forming the positive pressure in the second pressure chamber includes raising the pressure in the second pressure chamber to a second positive pressure setpoint and then maintaining the pressure in the second pressure chamber at the second positive pressure setpoint.

[0012] In one embodiment, wafer A polishing apparatus for polishing, having a plurality of pressure chambers formed by an elastic film, and in the plurality of pressure chambers waferA polishing apparatus is provided, comprising a polishing head that presses against a polishing surface, and an operation control unit that controls the operation of the polishing apparatus, wherein the plurality of pressure chambers include a first pressure chamber, a second pressure chamber located outside the first pressure chamber, and a third pressure chamber located outside the second pressure chamber, and the operation control unit is configured to operate the polishing apparatus to create a positive pressure in the first pressure chamber and a negative pressure in the second pressure chamber to move the fluid present between the upper surface of the wafer and the first pressure chamber outward, then create a positive pressure in the second pressure chamber and a negative pressure in the third pressure chamber to move the fluid present between the upper surface of the wafer and the second pressure chamber outward, create a positive pressure in the outermost pressure chamber of the plurality of pressure chambers to move the fluid present between the upper surface of the wafer and the outermost pressure chamber outward, causing the fluid to flow out from the upper surface of the wafer, and then press the lower surface of the wafer against the polishing surface with the elastic film to polish the lower surface of the wafer.

[0013] In one embodiment, the operation control unit is configured to operate the polishing device such that the timing at which the positive pressure is formed in the first pressure chamber is the same as the timing at which the operation control unit starts forming the negative pressure in the second pressure chamber, and to operate the polishing device such that the timing at which the positive pressure is formed in the second pressure chamber is the same as the timing at which the negative pressure is formed in the third pressure chamber. In one embodiment, the operation control unit is configured to operate the polishing device such that forming the negative pressure in the second pressure chamber includes lowering the pressure in the second pressure chamber to a negative pressure set value, and then opening the second pressure chamber to the atmosphere, and forming the negative pressure in the third pressure chamber includes lowering the pressure in the third pressure chamber to a negative pressure set value, and then opening the third pressure chamber to the atmosphere.

[0014] In one embodiment, the operation control unit is configured to operate the polishing device such that the timing at which the negative pressure is formed in the second pressure chamber is earlier than the timing at which the positive pressure is formed in the first pressure chamber, and the operation control unit is configured to operate the polishing device such that the timing at which the negative pressure is formed in the third pressure chamber is earlier than the timing at which the positive pressure is formed in the second pressure chamber. In one embodiment, the operation control unit is configured to operate the polishing device such that forming a negative pressure in the second pressure chamber includes lowering the pressure in the second pressure chamber to a negative pressure setpoint and then releasing the negative pressure in the second pressure chamber, and forming a positive pressure in the first pressure chamber while the negative pressure in the second pressure chamber is being released; and forming a negative pressure in the third pressure chamber includes lowering the pressure in the third pressure chamber to a negative pressure setpoint and then releasing the negative pressure in the third pressure chamber, and forming a positive pressure in the second pressure chamber while the negative pressure in the third pressure chamber is being released.

[0015] In one embodiment, the first pressure chamber is located in the central part of the elastic membrane. In one embodiment, the operation control unit is configured to operate the polishing device such that forming the positive pressure in the first pressure chamber includes raising the pressure in the first pressure chamber to a first positive pressure setpoint and then maintaining the pressure in the first pressure chamber at the first positive pressure setpoint, and forming the positive pressure in the second pressure chamber includes raising the pressure in the second pressure chamber to a second positive pressure setpoint and then maintaining the pressure in the second pressure chamber at the second positive pressure setpoint. [Effects of the Invention]

[0016] According to the present invention, in a polishing head in which a plurality of pressure chambers are formed, a positive pressure is formed in the inner pressure chamber among adjacent pressure chambers, and a negative pressure is formed in the outer pressure chamber, thereby moving the fluid present on the upper surface of the wafer outward. By sequentially performing this operation in the pressure chambers adjacent further outward, the fluid present on the upper surface of the wafer is moved outward. Further, by forming a positive pressure in the pressure chamber located most outward, the fluid can be made to flow out from the upper surface of the wafer. As a result, the elastic film forming the pressure chamber can apply an intended force to the wafer.

Brief Description of the Drawings

[0017] [Figure 1] It is a schematic diagram showing one embodiment of a polishing apparatus. [Figure 2] It is a cross-sectional view showing one embodiment of a polishing head. [Figure 3] It is a top view of a transfer device for transferring a wafer to the polishing head shown in FIG. 1. [Figure 4] It is a schematic diagram showing a state where fluid is present on the upper surface of a wafer. [Figure 5] It is a schematic diagram showing a state where the elastic film of the polishing head moves the fluid present on the upper surface of the wafer outward. [Figure 6] It is a schematic diagram showing a state where the elastic film of the polishing head moves the fluid present on the upper surface of the wafer further outward. [Figure 7] It is a schematic diagram showing a state where the elastic film of the polishing head moves the fluid present on the upper surface of the wafer further outward. [Figure 8] It is a schematic diagram showing a state where the elastic film of the polishing head causes the fluid present on the upper surface of the wafer to flow out. [Figure 9] It is a graph showing the relationship between the pressure and time in a plurality of pressure chambers. [Figure 10] It is a graph showing the relationship between the pressure and time in a plurality of pressure chambers according to another embodiment of a method for causing fluid to flow out from the upper surface of a wafer. [Figure 11]This graph shows the relationship between pressure and time in multiple pressure chambers according to yet another embodiment of a method for draining fluid from the top surface of a wafer. [Figure 12] This is a schematic cross-sectional view of the polishing head. [Figure 13] This diagram illustrates the cleaning process of the polishing head. [Figure 14] This diagram illustrates a problem caused by the fluid present between the top surface of the wafer and the elastic film of the polishing head. [Modes for carrying out the invention]

[0018] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic diagram showing one embodiment of a polishing apparatus. As shown in Figure 1, the polishing apparatus comprises a polishing table 3 that supports a polishing pad 2, a polishing head 1 that presses a wafer W, which is an example of a workpiece, against the polishing pad 2, a table motor 6 that rotates the polishing table 3, and a polishing liquid supply nozzle 5 for supplying polishing liquid (for example, a slurry containing abrasive particles) onto the polishing pad 2. The surface of the polishing pad 2 constitutes a polishing surface 2a for polishing the wafer W.

[0019] The polishing table 3 is connected to a table motor 6 and is configured to rotate the polishing table 3 and the polishing pad 2 together. The polishing head 1 is fixed to the end of the polishing head shaft 11, and the polishing head shaft 11 is rotatably supported by a head arm 15. The head arm 15 is rotatably supported by a pivot shaft 16. The polishing head shaft 11 is connected to a vertical movement mechanism 18 located within the head arm 15. The vertical movement mechanism 18 is configured to move the polishing head shaft 11 up and down in its axial direction. The vertical movement of the polishing head shaft 11 by the vertical movement mechanism 18 allows the wafer W held by the polishing head 1 to move closer to and further away from the polishing pad 2 on the polishing table 3.

[0020] The polishing apparatus further includes an operation control unit 9 that controls the operation of each component of the polishing apparatus. The operation control unit 9 is electrically connected to the polishing head 1, the polishing table 3, the polishing fluid supply nozzle 5, and the vertical movement mechanism 18, and controls the operation of the polishing head 1, the polishing table 3, the polishing fluid supply nozzle 5, and the vertical movement mechanism 18. The operation control unit 9 includes a storage device 9a in which a program is stored, and an arithmetic unit 9b that performs calculations according to the instructions contained in the program. The operation control unit 9 is composed of at least one computer. The storage device 9a includes a main memory such as random access memory (RAM) and an auxiliary storage device such as a hard disk drive (HDD) or a solid-state drive (SSD). Examples of arithmetic units 9b include a CPU (central processing unit) and a GPU (graphics processing unit). However, the specific configuration of the operation control unit 9 is not limited to these examples.

[0021] The wafer W is polished as follows: The motion control unit 9 issues commands to the polishing table 3, the polishing head 1, and the polishing fluid supply nozzle 5 to rotate the polishing table 3 and the polishing head 1 in the direction indicated by the arrows in Figure 1, while the polishing fluid is supplied from the polishing fluid supply nozzle 5 to the polishing surface 2a of the polishing pad 2 on the polishing table 3. As the wafer W is rotated by the polishing head 1, the polishing head 1 presses the wafer W against the polishing surface 2a of the polishing pad 2 with the polishing fluid present between the polishing pad 2 and the wafer W. The surface of the wafer W is polished by the chemical action of the polishing fluid and the mechanical action of the abrasive particles contained in the polishing fluid and / or the polishing pad.

[0022] Next, the polishing head 1 will be described. Figure 2 is a cross-sectional view showing one embodiment of the polishing head 1. The polishing head 1 comprises a carrier 31 fixed to the end of the polishing head shaft 11, an elastic membrane 34 attached to the lower part of the carrier 31, and a retainer ring 32 positioned below the carrier 31. The retainer ring 32 is positioned around the elastic membrane 34. This retainer ring 32 is an annular structure that holds the wafer W to prevent the wafer W from flying out of the polishing head 1 during polishing.

[0023] The elastic film 34 comprises a contact portion 35 having a contact surface 35a that can contact the upper surface of the wafer W, and inner wall portions 36a, 36b, 36c and outer wall portion 36d connected to the contact portion 35. The contact portion 35 has substantially the same size and shape as the upper surface of the wafer W. The inner wall portions 36a, 36b, 36c and outer wall portion 36d are endless walls arranged concentrically. The outer wall portion 36d is located outside the inner wall portions 36a, 36b, 36c and is arranged to surround the inner wall portions 36a, 36b, 36c. In this embodiment, three inner wall portions 36a, 36b, 36c are provided, but the present invention is not limited to this embodiment. In one embodiment, two inner wall portions may be provided, or four or more inner wall portions may be provided.

[0024] Multiple (four in this embodiment) pressure chambers 25A, 25B, 25C, and 25D are provided between the elastic membrane 34 and the carrier 31. The pressure chambers 25A, 25B, 25C, and 25D are formed by the contact portion 35, inner wall portions 36a, 36b, 36c, and outer wall portion 36d of the elastic membrane 34. That is, pressure chamber 25A is located within the inner wall portion 36a, pressure chamber 25B is located between the inner wall portions 36a and 36b, pressure chamber 25C is located between the inner wall portions 36b and 36c, and pressure chamber 25D is located between the inner wall portion 36c and outer wall portion 36d. The size of the pressure chambers 25A, 25B, 25C, and 25D, i.e., the distance from the center of the elastic membrane 34 to the inner wall portions 36a, 36b, 36c, and outer wall portion 36d, is not particularly limited. For example, the inner wall portions 36a, 36b, 36c and the outer wall portion 36d may be arranged at equal intervals from the center of the elastic membrane 34, or they may be arranged at different intervals.

[0025] The pressure chamber 25A located in the center of the elastic membrane 34 is circular, while the other pressure chambers 25B, 25C, and 25D are annular. These pressure chambers 25A, 25B, 25C, and 25D are arranged concentrically. Pressure chamber 25B is located outside pressure chamber 25A, pressure chamber 25C is located outside pressure chamber 25B, and pressure chamber 25D is located outside pressure chamber 25C. In this embodiment, the elastic membrane 34 forms four pressure chambers 25A to 25D, but in one embodiment, the elastic membrane 34 may form three pressure chambers, or five or more pressure chambers.

[0026] An annular membrane (rolling diaphragm) 37 is positioned between the carrier 31 and the retainer ring 32, and a pressure chamber 25E is formed inside this membrane 37. Gas transfer lines F1, F2, F3, F4, and F5 are connected to the pressure chambers 25A, 25B, 25C, 25D, and 25E, respectively. The gas transfer lines F1, F2, F3, F4, and F5 extend via a rotary joint 40 attached to the polishing head shaft 11.

[0027] The gas transfer lines F1, F2, F3, F4, and F5 are connected to the gas supply lines La1, La2, La3, La4, and La5, respectively, upstream of the rotary joint 40. The gas supply lines La1, La2, La3, La4, and La5 are connected to a compressed gas supply source (not shown) which serves as a utility supply source in the factory where the polishing equipment is installed. Compressed gas, such as compressed air, is supplied from the gas supply lines La1, La2, La3, La4, and La5 to the pressure chambers 25A, 25B, 25C, 25D, and 25E, respectively, through the gas transfer lines F1, F2, F3, F4, and F5.

[0028] Gas supply lines La1, La2, La3, La4, and La5 are each fitted with gas supply valves Va1, Va2, Va3, Va4, and Va5, and pressure regulators Ra1, Ra2, Ra3, Ra4, and Ra5, respectively. The gas supply valves Va1, Va2, Va3, Va4, and Va5 are actuator-driven valves, such as solenoid valves, electric valves, or air-operated valves. In one embodiment, the gas supply valves Va1 to Va5 may be manually operated. When the gas supply valves Va1 to Va5 are opened, compressed gas from the compressed gas supply source is supplied independently to the pressure chambers 25A to 25E through the pressure regulators Ra1 to Ra5. The pressure regulators Ra1 to Ra5 ​​are configured to regulate the pressure of the compressed gas in the pressure chambers 25A to 25E.

[0029] The gas supply valves Va1 to Va5 and pressure regulators Ra1 to Ra5 ​​are connected to the operation control unit 9. The operation of the gas supply valves Va1 to Va5 and pressure regulators Ra1 to Ra5 ​​is controlled by the operation control unit 9. The operation control unit 9 sends the respective target pressure values ​​for pressure chambers 25A to 25E to the pressure regulators Ra1 to Ra5, and the pressure regulators Ra1 to Ra5 ​​operate to maintain the pressure in pressure chambers 25A to 25E at the corresponding target pressure values.

[0030] The pressure regulators Ra1 to Ra5 ​​can independently change the internal pressure of the pressure chambers 25A to 25E. Therefore, the polishing head 1 can independently adjust the polishing pressure on four corresponding regions of the wafer W, namely the central region, the inner middle region, the outer middle region, and the edge region, and the pressing force of the polishing pad 2 of the retainer ring 32 against the polishing surface 2a. For example, the polishing head 1 can press different regions of the wafer W surface against the polishing surface 2a of the polishing pad 2 with different polishing pressures. Therefore, the polishing head 1 can control the film thickness profile of the wafer W to achieve a target film thickness profile.

[0031] Furthermore, gas transfer lines F1, F2, F3, F4, and F5 are connected to vacuum lines Lb1, Lb2, Lb3, Lb4, and Lb5, respectively, upstream of the rotary joint 40. Compressed gas, such as compressed air, is supplied from gas supply lines La1, La2, La3, La4, and La5 to pressure chambers 25A, 25B, 25C, 25D, and 25E, respectively, through gas transfer lines F1, F2, F3, F4, and F5. Vacuum valves Vb1, Vb2, Vb3, Vb4, and Vb5 and vacuum regulators Rb1, Rb2, Rb3, Rb4, and Rb5 are installed on vacuum lines Lb1, Lb2, Lb3, Lb4, and Lb5, respectively. Vacuum valves Vb1, Vb2, Vb3, Vb4, and Vb5 are actuator-driven valves such as solenoid valves, electric valves, or air-operated valves. In one embodiment, the vacuum valves Vb1 to Vb5 may be operated manually.

[0032] When vacuum valves Vb1 to Vb5 are opened, the compressed gas in pressure chambers 25A to 25E is independently discharged to the outside through gas transfer lines F1 to F5 and vacuum lines Lb1 to Lb5, respectively, creating a negative pressure within pressure chambers 25A to 25E. Vacuum regulators Rb1 to Rb5 are configured to adjust the vacuum pressure within pressure chambers 25A to 25E.

[0033] The vacuum valves Vb1 to Vb5 and vacuum regulators Rb1 to Rb5 are connected to the operation control unit 9. The operation of the vacuum valves Vb1 to Vb5 and vacuum regulators Rb1 to Rb5 is controlled by the operation control unit 9. When the polishing head 1 holds the wafer W, the contact portion 35 of the elastic film 34 is in contact with the wafer W, and the vacuum valves Vb1, Vb2, and Vb3 are opened to create a vacuum in the pressure chambers 25A, 25B, and 25C. The portion of the contact portion 35 that forms these pressure chambers 25A, 25B, and 25C is recessed upward, and the polishing head 1 can attract the wafer W by the suction effect of the elastic film 34. Furthermore, by supplying compressed gas to these pressure chambers 25A, 25B, and 25C to release the suction effect, the polishing head 1 can release the wafer W.

[0034] Furthermore, the gas transfer lines F1, F2, F3, F4, and F5 are connected to the atmospheric release lines Lc1, Lc2, Lc3, Lc4, and Lc5, respectively, upstream of the rotary joint 40. Atmospheric release valves Vc1, Vc2, Vc3, Vc4, and Vc5 are attached to the atmospheric release lines Lc1, Lc2, Lc3, Lc4, and Lc5, respectively. The atmospheric release valves Vc1, Vc2, Vc3, Vc4, and Vc5 are actuator-driven valves such as solenoid valves, electric valves, or air-operated valves. In one embodiment, atmospheric release valves Vc1 to Vc5 may be operated manually. When atmospheric release valves Vc1 to Vc5 are opened, the pressure chambers 25A to 25E are independently released to the atmosphere. The atmospheric release valves Vc1 to Vc5 are connected to the operation control unit 9. The operation of atmospheric release valves Vc1 to Vc5 is controlled by the operation control unit 9. In one embodiment, the atmospheric release lines Lc1 to Lc5 and atmospheric release valves Vc1 to Vc5 may not be provided.

[0035] In this embodiment, gas supply lines La1 to La5, vacuum lines Lb1 to Lb5, and atmospheric release lines Lc1 to Lc5, which communicate with pressure chambers 25A to 25E via gas transfer lines F1 to F5, are each fitted with gas supply valves Va1 to Va5, vacuum valves Vb1 to Vb5, and atmospheric release valves Vc1 to Vc5, respectively. In one embodiment, three-way valves may be fitted to gas transfer lines F1 to F5 instead of these gas supply valves Va1 to Va5, vacuum valves Vb1 to Vb5, and atmospheric release valves Vc1 to Vc5. In this case, by operating the three-way valves, the lines communicating with pressure chambers 25A to 25E via gas transfer lines F1 to F5 may be switched to either the gas supply lines La1 to La5, vacuum lines Lb1 to Lb5, or atmospheric release lines Lc1 to Lc5.

[0036] Figure 3 is a top view of a transport device 44 that transports a wafer W to the polishing head 1 shown in Figure 1. As shown in Figure 3, the wafer W is transported to the polishing head 1 by the transport device 44. The polishing head 1 is movable between the polishing position P1 shown by the solid line and the transfer position P2 shown by the dotted line in Figure 3. More specifically, the polishing head 1 can move between the polishing position P1 and the transfer position P2 by rotating the head arm 15 around the pivot shaft 16. The polishing position P1 is above the polishing surface 2a of the polishing pad 2, and the transfer position P2 is located outside the polishing surface 2a.

[0037] The transport device 44 includes a transport stage 45 on which the wafer W is placed, a lifting device 47 that moves the transport stage 45 up and down, and a horizontal moving device 49 that moves the transport stage 45 and the lifting device 47 together horizontally. The wafer W to be polished is placed on the transport stage 45 and moved to the transfer position P2 together with the transport stage 45 by the horizontal moving device 49. When the polishing head 1 is at the transfer position P2, the lifting device 47 raises the transport stage 45. The polishing head 1 holds the wafer W on the transport stage 45 and moves together with the wafer W to the polishing position P1.

[0038] The polishing fluid supply nozzle 5 supplies polishing fluid to the polishing surface 2a of the rotating polishing pad 2, while the polishing head 1 rotates the wafer W and presses the wafer W against the polishing surface 2a of the polishing pad 2, causing the wafer W to slide against the polishing surface 2a. The underside of the wafer W is polished by the chemical action of the polishing fluid and the mechanical action of the abrasive particles contained in the polishing fluid and / or the polishing pad.

[0039] After polishing the wafer W, the polishing head 1 moves to the transfer position P2 along with the wafer W. The polishing head 1 then transfers the polished wafer W to the transport stage 45. The transport stage 45 moves the wafer W to the next process. A cleaning nozzle 53 is located at the transfer position P2 to supply liquid (such as a rinsing solution like pure water) to the polishing head 1 for cleaning. The cleaning nozzle 53 is facing the polishing head 1. After releasing the wafer W, the polishing head 1 is cleaned by the liquid supplied from the cleaning nozzle 53.

[0040] While the polishing head 1 is being cleaned, the next wafer to be polished is moved by the transport stage 45 to a receiving position P2 below the polishing head 1. When the polishing head 1 is cleaned, the lifting device 47 raises the transport stage 45 on which the next wafer is placed. The cleaned polishing head 1 then holds the next wafer and moves to the polishing position P1. In this way, multiple wafers are polished continuously.

[0041] However, while the polishing head 1 is being cleaned, the next wafer to be polished is moved to the receiving position P2 below the polishing head 1, causing liquid to fall onto the top surface of the wafer. The liquid present on the top surface of the wafer prevents the polishing head 1 from applying the appropriate force to the wafer, as explained with reference to Figure 14. One solution is to move the next wafer to the receiving position P2 only after the cleaning of the polishing head 1 is complete. However, such an operation reduces the throughput of the polishing apparatus.

[0042] Furthermore, when the polishing head 1 holds the next wafer by adsorbing it through the suction effect of the elastic film 34, as described above, there may be gas, such as air, between the upper surface of the wafer and the elastic film 34 of the polishing head 1. As explained with reference to Figure 14, gas present on the upper surface of the wafer also prevents the polishing head 1 from applying the appropriate force to the wafer.

[0043] Therefore, in this embodiment, the fluid is discharged from the upper surface of the wafer as follows. Figure 4 is a schematic diagram showing the presence of fluid Q on the upper surface of the wafer W. Detailed diagrams of the polishing head 1 are omitted in Figure 4. The polishing head 1, which holds the wafer W to be polished, is touched down onto the polishing surface 2a of the polishing pad 2 by the vertical movement mechanism 18. When the polishing head 1 touches down onto the polishing surface 2a, it releases the negative pressure that had been formed in the pressure chambers 25A, 25B, and 25C to attract the wafer W. Figure 4 shows that the negative pressure formed in the pressure chambers 25A, 25B, and 25C of the polishing head 1 has been released, and fluid Q is present on the upper surface of the wafer W, that is, between the wafer W and the elastic film 34.

[0044] In this embodiment, before polishing the wafer W, the pressure in a plurality of pressure chambers 25A to 25D formed by the elastic film 34 of the polishing head 1 is sequentially changed to move the fluid Q present on the upper surface of the wafer W outwards and cause the fluid Q to flow out from the upper surface of the wafer W. Figures 5 to 8 are schematic diagrams showing how the elastic film 34 of the polishing head 1 moves the fluid Q present on the upper surface of the wafer W outwards and causes the fluid Q present on the upper surface of the wafer W to flow out. Figure 9 is a graph showing the relationship between pressure and time in the plurality of pressure chambers 25A to 25D in this embodiment. In Figure 9, the solid line shows the change in pressure over time in pressure chamber 25A, the thick line shows the change in pressure over time in pressure chamber 25B, the dashed line shows the change in pressure over time in pressure chamber 25C, and the dashed line shows the change in pressure over time in pressure chamber 25D.

[0045] First, as shown in Figure 5, a positive pressure is formed in the pressure chamber 25A located in the center of the polishing head 1, and a negative pressure is formed in the pressure chamber 25B located outside of pressure chamber 25A. Pressure chamber 25B is adjacent to pressure chamber 25A. The formation of positive pressure in pressure chamber 25A and negative pressure in pressure chamber 25B takes place during time T1 as shown in Figure 9. As shown in Figure 9, the timing for starting the formation of positive pressure in pressure chamber 25A and the timing for starting the formation of negative pressure in pressure chamber 25B are the same. During time T1, the pressure in pressure chamber 25A is raised to the positive pressure setpoint PS1, and then the pressure in pressure chamber 25A is maintained at the positive pressure setpoint PS1. During time T1, the pressure in pressure chamber 25B is lowered to the negative pressure setpoint NS1, and then the negative pressure in pressure chamber 25B is eliminated.

[0046] More specifically, during time T1, the operation control unit 9 issues a command to the gas supply valve Va1 (see Figure 2) to open it, connecting the gas supply line La1 to the pressure chamber 25A via the gas transfer line F1, and issues a command to the pressure regulator Ra1 (see Figure 2) to supply compressed gas into the pressure chamber 25A, raising the pressure in the pressure chamber 25A to the positive pressure setpoint PS1. After that, the pressure in the pressure chamber 25A is maintained at the positive pressure setpoint PS1. During time T1, the operation control unit 9 issues a command to the vacuum valve Vb2 (see Figure 2) to open it, connecting the vacuum line Lb2 to the pressure chamber 25B via the gas transfer line F2, and issues a command to the vacuum regulator Rb2 (see Figure 2) to lower the pressure in the pressure chamber 25B to the negative pressure setpoint NS1. After that, the operation control unit 9 issues a command to the vacuum valve Vb2 to close it. Furthermore, the operation control unit 9 issues a command to the gas supply valve Va2 (see Figure 2) to open the gas supply valve Va2, connecting the gas supply line La2 and the pressure chamber 25B via the gas transfer line F2, and issues a command to the pressure regulator Ra2 (see Figure 2) to supply compressed gas into the pressure chamber 25B, thereby raising the pressure in the pressure chamber 25B to atmospheric pressure and eliminating the negative pressure.

[0047] As shown in Figure 5, by forming a positive pressure in the pressure chamber 25A, the central part of the elastic film 34 forming the pressure chamber 25A comes into contact with the central part of the upper surface of the wafer W. By forming a negative pressure in the pressure chamber 25B, the portion of the elastic film 34 forming the pressure chamber 25B is pulled upward, creating a gap between the upper surface of the wafer W and the pressure chamber 25B. In particular, as a negative pressure is formed in the pressure chamber 25B, the inner wall portion 36a between the pressure chambers 25A and 25B is lifted upward, allowing the fluid Q present between the upper surface of the wafer W and the pressure chamber 25A to flow outward. Thus, during time T1, by forming a positive pressure in the pressure chamber 25A and a negative pressure in the pressure chamber 25B, the central part of the elastic film 34 pushes the fluid Q present between the upper surface of the wafer W and the pressure chamber 25A outward, causing it to move into the gap between the upper surface of the wafer W and the pressure chamber 25B. Since the positive pressure in pressure chamber 25A is maintained, the fluid Q that has moved outward remains between the top surface of wafer W and pressure chamber 25B without returning towards pressure chamber 25A. The fluid Q may move further outward or flow out from the top surface of wafer W.

[0048] Next, as shown in Figure 6, while maintaining positive pressure in pressure chamber 25A of the polishing head 1, positive pressure is formed in pressure chamber 25B, and negative pressure is formed in pressure chamber 25C, which is located outside of pressure chamber 25B. Pressure chamber 25C is adjacent to pressure chamber 25B. This formation of positive pressure in pressure chamber 25B and negative pressure in pressure chamber 25C occurs during time T2 as shown in Figure 9. As shown in Figure 9, the timing for starting the formation of positive pressure in pressure chamber 25B and the timing for starting the formation of negative pressure in pressure chamber 25C are the same. During time T2, the pressure in pressure chamber 25B is raised to the positive pressure setpoint PS2, and then maintained at the positive pressure setpoint PS2. During time T2, the pressure in pressure chamber 25C is lowered to the negative pressure setpoint NS2, and then the negative pressure in pressure chamber 25C is eliminated.

[0049] More specifically, during time T2, the operation control unit 9 issues a command to the pressure regulator Ra2 to supply compressed gas into the pressure chamber 25B, raising the pressure in the pressure chamber 25B to the positive pressure setpoint PS2. After that, the pressure in the pressure chamber 25B is maintained at the positive pressure setpoint PS2. During time T2, the operation control unit 9 issues a command to the vacuum valve Vb3 (see Figure 2) to open the vacuum valve Vb3, connecting the vacuum line Lb3 and the pressure chamber 25C via the gas transfer line F3, and issues a command to the vacuum regulator Rb3 (see Figure 2) to lower the pressure in the pressure chamber 25C to the negative pressure setpoint NS2. After that, the operation control unit 9 issues a command to the vacuum valve Vb3 to close the vacuum valve Vb3. Furthermore, the operation control unit 9 issues a command to the gas supply valve Va3 (see Figure 2) to open the gas supply valve Va3, connecting the gas supply line La3 and the pressure chamber 25C via the gas transfer line F3, and issues a command to the pressure regulator Ra3 (see Figure 2) to supply compressed gas into the pressure chamber 25C, thereby raising the pressure in the pressure chamber 25C to atmospheric pressure and eliminating the negative pressure.

[0050] As shown in Figure 6, by forming a positive pressure in the pressure chamber 25B, the portion of the elastic film 34 that forms the pressure chamber 25B comes into contact with the upper surface of the wafer W. By forming a negative pressure in the pressure chamber 25C, the portion of the elastic film 34 that forms the pressure chamber 25C is pulled upward, creating a gap between the upper surface of the wafer W and the pressure chamber 25C. In particular, as a negative pressure is formed in the pressure chamber 25C, the inner wall portion 36b between the pressure chambers 25B and 25C is lifted upward, allowing the fluid Q present between the upper surface of the wafer W and the pressure chamber 25B to flow outward. Thus, during time T2, by forming a positive pressure in the pressure chamber 25B and a negative pressure in the pressure chamber 25C, the portion of the elastic film 34 that forms the pressure chamber 25B pushes the fluid Q present between the upper surface of the wafer W and the pressure chamber 25B outward, causing it to move into the gap between the upper surface of the wafer W and the pressure chamber 25C. Since the positive pressure in the pressure chamber 25B is maintained, the fluid Q that has moved outward does not return towards the pressure chamber 25B, but remains between the top surface of the wafer W and the pressure chamber 25C. The fluid Q may move further outward or flow out from the top surface of the wafer W.

[0051] Next, as shown in Figure 7, while positive pressure is maintained in pressure chambers 25A and 25B of the polishing head 1, positive pressure is formed in pressure chamber 25C, and negative pressure is formed in pressure chamber 25D, which is located outside of pressure chamber 25C. Pressure chamber 25D is adjacent to pressure chamber 25C. This formation of positive pressure in pressure chamber 25C and negative pressure in pressure chamber 25D occurs during time T3 as shown in Figure 9. As shown in Figure 9, the timing for starting the formation of positive pressure in pressure chamber 25C and the timing for starting the formation of negative pressure in pressure chamber 25D are the same. During time T3, the pressure in pressure chamber 25C is raised to the positive pressure setpoint PS3, and then maintained at the positive pressure setpoint PS3. During time T3, the pressure in pressure chamber 25D is lowered to the negative pressure setpoint NS3, and then the negative pressure in pressure chamber 25D is eliminated.

[0052] More specifically, during time T3, the operation control unit 9 issues a command to the pressure regulator Ra3 to supply compressed gas into the pressure chamber 25C, raising the pressure in the pressure chamber 25C to the positive pressure setpoint PS3. After that, the pressure in the pressure chamber 25C is maintained at the positive pressure setpoint PS3. During time T3, the operation control unit 9 issues a command to the vacuum valve Vb4 (see Figure 2) to open the vacuum valve Vb4, connecting the vacuum line Lb4 and the pressure chamber 25D via the gas transfer line F4, and issues a command to the vacuum regulator Rb4 (see Figure 2) to lower the pressure in the pressure chamber 25D to the negative pressure setpoint NS3. After that, the operation control unit 9 issues a command to the vacuum valve Vb4 to close the vacuum valve Vb4. Furthermore, the operation control unit 9 issues a command to the gas supply valve Va4 (see Figure 2) to open the gas supply valve Va4, connecting the gas supply line La4 and the pressure chamber 25D via the gas transfer line F4, and issues a command to the pressure regulator Ra4 (see Figure 2) to supply compressed gas into the pressure chamber 25D, thereby raising the pressure in the pressure chamber 25D to atmospheric pressure and eliminating the negative pressure.

[0053] As shown in Figure 7, by forming a positive pressure in the pressure chamber 25C, the portion of the elastic film 34 that forms the pressure chamber 25C comes into contact with the upper surface of the wafer W. By forming a negative pressure in the pressure chamber 25D, the portion of the elastic film 34 that forms the pressure chamber 25D is pulled upward, creating a gap between the upper surface of the wafer W and the pressure chamber 25D. In particular, as a negative pressure is formed in the pressure chamber 25D, the inner wall portion 36c between the pressure chamber 25C and the pressure chamber 25D is lifted upward, allowing the fluid Q present between the upper surface of the wafer W and the pressure chamber 25C to flow outward. Thus, during time T3, by forming a positive pressure in the pressure chamber 25C and a negative pressure in the pressure chamber 25D, the portion of the elastic film 34 that forms the pressure chamber 25C pushes the fluid Q present between the upper surface of the wafer W and the pressure chamber 25C outward, moving it between the upper surface of the wafer W and the pressure chamber 25D. Since the positive pressure in the pressure chamber 25C is maintained, the fluid Q that has moved outward remains between the top surface of the wafer W and the pressure chamber 25D without returning towards the pressure chamber 25C. The fluid Q may move further outward or flow out from the top surface of the wafer W.

[0054] Next, as shown in Figure 8, while positive pressure is maintained in the pressure chambers 25A, 25B, and 25C of the polishing head 1, positive pressure is formed in pressure chamber 25D. This formation of positive pressure in pressure chamber 25D takes place during time T4, as shown in Figure 9. As shown in Figure 9, during time T4, the pressure in pressure chamber 25D is raised to the positive pressure setpoint PS4, and then maintained at the positive pressure setpoint PS4. More specifically, during time T4, the operation control unit 9 issues a command to the pressure regulator Ra4 to supply compressed gas into pressure chamber 25D, raising the pressure in pressure chamber 25D to the positive pressure setpoint PS4. After that, the pressure in pressure chamber 25D is maintained at the positive pressure setpoint PS4.

[0055] As shown in Figure 8, by forming a positive pressure in the outermost pressure chamber, pressure chamber 25D, the portion of the elastic film 34 that forms the pressure chamber 25D comes into contact with the upper surface of the wafer W. Therefore, during time T4, the portion of the elastic film 34 that forms the pressure chamber 25D pushes the fluid Q present between the upper surface of the wafer W and the pressure chamber 25D outwards, causing the fluid Q to flow out from the upper surface of the wafer W.

[0056] In this embodiment, by creating a positive pressure in the inner pressure chamber 25A and a negative pressure in the outer pressure chamber 25B of the adjacent pressure chambers 25A and 25B, the fluid Q present on the upper surface of the wafer W can be moved outward. By sequentially performing this operation in the further outward adjacent pressure chambers 25B and 25C, and the even further outward adjacent pressure chambers 25C and 25D, the fluid Q present on the upper surface of the wafer W can be moved further outward. Furthermore, by creating a positive pressure in the outermost pressure chamber 25D, the fluid can be discharged from the upper surface of the wafer W.

[0057] According to this embodiment, the polishing head 1 can hold the wafer W in a state where there is substantially no fluid Q between the elastic film 34 and the upper surface of the wafer W. Then, while controlling the pressure in the pressure chambers 25A to 25D according to the polishing conditions of the wafer W, the polishing head 1 presses the lower surface of the wafer W against the polishing surface 2a with the elastic film 34 to polish the lower surface of the wafer W. By pressing the lower surface of the wafer W against the polishing surface 2a with the elastic film 34 in a state where there is substantially no fluid Q between the elastic film 34 and the upper surface of the wafer W, the intended force can be applied to the wafer W. As a result, the polishing head 1 can achieve the desired film thickness profile of the wafer W. The state where there is substantially no fluid Q between the elastic film 34 and the upper surface of the wafer W includes not only a state where there is no fluid Q at all, but also a state in which fluid Q has flowed out to the extent that the pressure chambers 25A to 25D of the polishing head 1 can apply appropriate force to multiple regions of the corresponding wafer W.

[0058] In this embodiment, the positive pressure setting values ​​PS1, PS2, PS3, and PS4 are the same pressure value, but the positive pressure setting values ​​PS1, PS2, PS3, and PS4 may be different positive pressure values. In this embodiment, the negative pressure setting values ​​NS1, NS2, and NS3 are the same pressure value, but the negative pressure setting values ​​NS1, NS2, and NS3 may be different negative pressure values.

[0059] In this embodiment, the lengths of time T1 to T4 are the same, but the lengths of time T1, T2, T3, and T4 are not limited to this embodiment, as long as the fluid Q present on the upper surface of the wafer W is moved outwards and the fluid is discharged from the upper surface of the wafer W. The lengths of time T1, T2, T3, and T4 may be adjusted based on the volume in the pressure chambers 25A to 25D, the flow rate of compressed gas supplied from the gas supply lines La1 to La4, the flow rate of compressed gas discharged to the vacuum lines Lb1 to Lb4, etc.

[0060] In this embodiment, initially, a positive pressure is formed in the inner pressure chamber 25A and a negative pressure is formed in the outer pressure chamber 25B of the adjacent pressure chambers 25A and 25B, thereby moving the fluid Q present on the upper surface of the wafer W outward. However, the two adjacent pressure chambers in which this operation is initiated are not limited to pressure chambers 25A and 25B. In one embodiment, if there is no fluid Q between the upper surface of the wafer W and pressure chamber 25A, but there is fluid Q between the upper surface of the wafer W and pressure chamber 25B, initially, a positive pressure may be formed in the inner pressure chamber 25B and a negative pressure in the outer pressure chamber 25C of the adjacent pressure chambers 25B and 25C, thereby moving the fluid Q present on the upper surface of the wafer W and pressure chamber 25B outward. In this case, a positive pressure is already formed in pressure chamber 25A. This operation is then sequentially performed in the further outward adjacent pressure chambers 25C and 25D to move the fluid Q present on the upper surface of the wafer W further outward. Furthermore, by creating a positive pressure in the outermost pressure chamber 25D, the fluid can be forced out from the top surface of the wafer W. Thus, the two adjacent pressure chambers that initiate operation may be appropriately changed depending on the position of the fluid Q present on the top surface of the wafer W.

[0061] In one embodiment, the elastic membrane 34 forms three pressure chambers 25A, 25B, and 25C, and the outermost pressure chamber may be pressure chamber 25C. In this case, a positive pressure is formed in the inner pressure chamber 25A and a negative pressure is formed in the outer pressure chamber 25B of the adjacent pressure chambers 25A and 25B, thereby moving the fluid Q present on the upper surface of the wafer W outward. Then, a positive pressure is formed in the inner pressure chamber 25B and a negative pressure is formed in the outer pressure chamber 25C of the further outward adjacent pressure chambers 25B and 25C, thereby moving the fluid Q present on the upper surface of the wafer W even further outward. Furthermore, a positive pressure is formed in the outermost pressure chamber 25C, thereby moving the fluid Q from the upper surface of the wafer W outward. Q It is acceptable to leak it.

[0062] Figure 10 is a graph showing the relationship between pressure and time in multiple pressure chambers 25A to 25D according to another embodiment of the method for draining fluid Q from the top surface of wafer W. Details of this embodiment that are not specifically described are the same as those of the embodiment described above, so redundant explanations are omitted. In this embodiment, after lowering the pressure in pressure chambers 25B, 25C, and 25D to negative pressure set values ​​NS1, NS2, and NS3, the negative pressure in pressure chambers 25B, 25C, and 25D is eliminated by opening the pressure chambers 25B, 25C, and 25D to the atmosphere.

[0063] During time T1, a positive pressure is formed in pressure chamber 25A, and the pressure in pressure chamber 25B is reduced to a negative pressure setpoint NS1, after which pressure chamber 25B is opened to the atmosphere. The operation of forming a positive pressure in pressure chamber 25A is the same as in the embodiment described with reference to Figures 5 to 9. More specifically, during time T1, the operation control unit 9 issues a command to the vacuum valve Vb2 to open the vacuum valve Vb2, connecting the vacuum line Lb2 and pressure chamber 25B via the gas transfer line F2, and issues a command to the vacuum regulator Rb2 to reduce the pressure in pressure chamber 25B to a negative pressure setpoint NS1. After that, the operation control unit 9 issues a command to the vacuum valve Vb2 to close the vacuum valve Vb2. Furthermore, it issues a command to the atmospheric release valve Vc2 (see Figure 2) to open the atmospheric release valve Vc2 and open pressure chamber 25B to the atmosphere.

[0064] Furthermore, during time T2, a positive pressure is formed in the pressure chamber 25B, and the pressure in the pressure chamber 25C is reduced to the negative pressure setpoint NS2, after which the pressure chamber 25C is opened to the atmosphere. The operation of forming a positive pressure in the pressure chamber 25B is the same as in the embodiment described with reference to Figures 5 to 9. More specifically, during time T2, the operation control unit 9 issues a command to the vacuum valve Vb3 to open the vacuum valve Vb3, connecting the vacuum line Lb3 and the pressure chamber 25C via the gas transfer line F3, and issues a command to the vacuum regulator Rb3 to reduce the pressure in the pressure chamber 25C to the negative pressure setpoint NS2. After that, the operation control unit 9 issues a command to the vacuum valve Vb3 to close the vacuum valve Vb3. Furthermore, it issues a command to the atmospheric release valve Vc3 (see Figure 2) to open the atmospheric release valve Vc3 and open the pressure chamber 25C to the atmosphere.

[0065] Furthermore, during time T3, a positive pressure is formed in the pressure chamber 25C, and the pressure in the pressure chamber 25D is reduced to the negative pressure set value NS3, after which the pressure chamber 25D is opened to the atmosphere. The operation of forming a positive pressure in the pressure chamber 25C is the same as in the embodiment described with reference to Figures 5 to 9. More specifically, during time T3, the operation control unit 9 issues a command to the vacuum valve Vb4 to open the vacuum valve Vb4, connecting the vacuum line Lb4 and the pressure chamber 25D via the gas transfer line F4, and issues a command to the vacuum regulator Rb4 to reduce the pressure in the pressure chamber 25D to the negative pressure set value NS3. After that, the operation control unit 9 issues a command to the vacuum valve Vb4 to close the vacuum valve Vb4. Furthermore, it issues a command to the atmospheric release valve Vc4 (see Figure 2) to open the atmospheric release valve Vc4 and open the pressure chamber 25D to the atmosphere.

[0066] Furthermore, a positive pressure is formed within the pressure chamber 25D during time T4. The operation of forming a positive pressure within the pressure chamber 25D is the same as in the embodiments described with reference to Figures 5 to 9.

[0067] Relieving the negative pressure in pressure chambers 25B, 25C, and 25D by opening to the atmosphere can be done in a shorter time than relieving the negative pressure in pressure chambers 25B, 25C, and 25D by supplying compressed gas. In the embodiment described above, as shown in Figure 9, supplying compressed gas to pressure chamber 25B to relieve the negative pressure in pressure chamber 25B requires time A1. In contrast, in this embodiment, as shown in Figure 10, relieving the negative pressure in pressure chamber 25B by opening to the atmosphere can be done in a shorter time B1 than time A1.

[0068] Similarly, in pressure chamber 25C, the time B2 (see Figure 10) required to release the negative pressure inside pressure chamber 25C by opening it to the atmosphere is shorter than the time A2 (see Figure 9) required to release the negative pressure inside pressure chamber 25C by supplying compressed gas into pressure chamber 25C. Similarly, in pressure chamber 25D, the time B3 (see Figure 10) required to release the negative pressure inside pressure chamber 25D by opening it to the atmosphere is shorter than the time A3 (see Figure 9) required to release the negative pressure inside pressure chamber 25D by supplying compressed gas into pressure chamber 25D.

[0069] According to this embodiment, pressure chamber 25B, 25C ,25D Since the time required to relieve the internal negative pressure A1, A2, A3 can be reduced to time B1, B2, B3, the overall time required to allow fluid Q to flow out from the top surface of wafer W can be reduced.

[0070] Figure 11 is a graph showing the relationship between pressure and time in a plurality of pressure chambers 25A to 25D according to yet another embodiment of a method for draining fluid Q from the top surface of wafer W. Details of this embodiment, which are not specifically described, are the same as those of the embodiment described with reference to Figures 5 to 9, so redundant explanations are omitted. In this embodiment, the timing at which negative pressure begins to form in the outer pressure chamber of the adjacent pressure chambers is earlier than the timing at which positive pressure begins to form in the inner pressure chamber.

[0071] As shown in Figure 11, in this embodiment, the timing at which negative pressure is formed in pressure chamber 25B is earlier than the timing at which positive pressure is formed in pressure chamber 25A. Specifically, during time T0, the pressure in pressure chamber 25B is lowered to the negative pressure setpoint NS1. Then, during time T1, the negative pressure in pressure chamber 25B is eliminated, and the pressure in pressure chamber 25A is raised to the positive pressure setpoint PS1. After that, the pressure in pressure chamber 25A is maintained at the positive pressure setpoint PS1. Therefore, during time T1, positive pressure is formed in pressure chamber 25A located in the center of the polishing head 1, and negative pressure is formed in pressure chamber 25B located outside of pressure chamber 25A.

[0072] More specifically, during time T0, the operation control unit 9 issues a command to the vacuum valve Vb2 to open it, connecting the vacuum line Lb2 to the pressure chamber 25B via the gas transfer line F2, and issues a command to the vacuum regulator Rb2 to lower the pressure in the pressure chamber 25B to the negative pressure set value NS1. Then, during time T1, the operation control unit 9 issues a command to the vacuum valve Vb2 to close it. Furthermore, the operation control unit 9 issues a command to the gas supply valve Va2 to open it, connecting the gas supply line La2 to the pressure chamber 25B via the gas transfer line F2, and issues a command to the pressure regulator Ra2 to supply compressed gas into the pressure chamber 25B, raising the pressure in the pressure chamber 25B to atmospheric pressure and eliminating the negative pressure. During time T1, the operation control unit 9 issues a command to the gas supply valve Va1 to open it, connecting the gas supply line La1 and the pressure chamber 25A via the gas transfer line F1, and issues a command to the pressure regulator Ra1 to supply compressed gas into the pressure chamber 25A, raising the pressure in the pressure chamber 25A to the positive pressure setpoint PS1. After that, the pressure in the pressure chamber 25A is maintained at the positive pressure setpoint PS1.

[0073] In this embodiment, at time T1, a positive pressure is formed in pressure chamber 25A while the negative pressure in pressure chamber 25B is being relieved. Even while the negative pressure in pressure chamber 25B is being relieved, the pressure inside pressure chamber 25B remains negative, so during time T1, the fluid Q present between the upper surface of wafer W and pressure chamber 25A can be pushed outwards and moved into the gap between the upper surface of wafer W and pressure chamber 25B (see Figure 5).

[0074] Furthermore, in this embodiment, the timing at which negative pressure is formed in pressure chamber 25C is earlier than the timing at which positive pressure is formed in pressure chamber 25B. Specifically, during time T1, the pressure in pressure chamber 25C is lowered to the negative pressure setpoint NS2. Then, during time T2, the negative pressure in pressure chamber 25C is eliminated, and the pressure in pressure chamber 25B is raised to the positive pressure setpoint PS2. After that, the pressure in pressure chamber 25B is maintained at the positive pressure setpoint PS2. Therefore, during time T2, positive pressure is formed in pressure chamber 25B, and negative pressure is formed in pressure chamber 25C, which is located outside of pressure chamber 25B.

[0075] More specifically, during time T1, the operation control unit 9 issues a command to the vacuum valve Vb3 to open it, connecting the vacuum line Lb3 to the pressure chamber 25C via the gas transfer line F3, and issues a command to the vacuum regulator Rb3 to lower the pressure in the pressure chamber 25C to the negative pressure set value NS2. Then, during time T2, the operation control unit 9 issues a command to the vacuum valve Vb3 to close it. Furthermore, the operation control unit 9 issues a command to the gas supply valve Va3 to open it, connecting the gas supply line La3 to the pressure chamber 25C via the gas transfer line F3, and issues a command to the pressure regulator Ra3 to supply compressed gas into the pressure chamber 25C, raising the pressure in the pressure chamber 25C to atmospheric pressure and eliminating the negative pressure. During time T2, the operation control unit 9 issues a command to the gas supply valve Va2 to open it, connecting the gas supply line La2 and the pressure chamber 25B via the gas transfer line F2, and issues a command to the pressure regulator Ra2 to supply compressed gas into the pressure chamber 25B, raising the pressure in the pressure chamber 25B to the positive pressure setpoint PS2. After that, the pressure in the pressure chamber 25B is maintained at the positive pressure setpoint PS2.

[0076] In this embodiment, at time T2, a positive pressure is formed in pressure chamber 25B while the negative pressure in pressure chamber 25C is being relieved. Even while the negative pressure in pressure chamber 25C is being relieved, the pressure inside pressure chamber 25C remains negative, so during time T2, the fluid Q present between the upper surface of wafer W and pressure chamber 25B can be pushed outwards and moved into the gap between the upper surface of wafer W and pressure chamber 25C (see Figure 6).

[0077] Furthermore, in this embodiment, the timing at which negative pressure is formed in pressure chamber 25D is earlier than the timing at which positive pressure is formed in pressure chamber 25C. Specifically, during time T2, the pressure in pressure chamber 25D is lowered to the negative pressure setpoint NS3. Then, during time T3, the negative pressure in pressure chamber 25D is eliminated, and the pressure in pressure chamber 25C is raised to the positive pressure setpoint PS3. After that, the pressure in pressure chamber 25C is maintained at the positive pressure setpoint PS3. Therefore, during time T3, positive pressure is formed in pressure chamber 25C, and negative pressure is formed in pressure chamber 25D, which is located outside of pressure chamber 25C.

[0078] More specifically, during time T2, the operation control unit 9 issues a command to the vacuum valve Vb4 to open it, connecting the vacuum line Lb4 to the pressure chamber 25D via the gas transfer line F4, and issues a command to the vacuum regulator Rb4 to lower the pressure in the pressure chamber 25D to the negative pressure set value NS3. Then, during time T3, the operation control unit 9 issues a command to the vacuum valve Vb4 to close it. Furthermore, the operation control unit 9 issues a command to the gas supply valve Va4 to open it, connecting the gas supply line La4 to the pressure chamber 25D via the gas transfer line F4, and issues a command to the pressure regulator Ra4 to supply compressed gas into the pressure chamber 25D, raising the pressure in the pressure chamber 25D to atmospheric pressure and eliminating the negative pressure. During time T3, the operation control unit 9 issues a command to the gas supply valve Va3 to open it, connecting the gas supply line La3 and the pressure chamber 25C via the gas transfer line F3, and issues a command to the pressure regulator Ra3 to supply compressed gas into the pressure chamber 25C, raising the pressure in the pressure chamber 25C to the positive pressure setpoint PS3. After that, the pressure in the pressure chamber 25C is maintained at the positive pressure setpoint PS3.

[0079] In this embodiment, at time T3, a positive pressure is formed in the pressure chamber 25C while the negative pressure in the pressure chamber 25D is being relieved. Even while the negative pressure in the pressure chamber 25D is being relieved, the pressure inside the pressure chamber 25D remains negative, so during time T3, the fluid Q present between the upper surface of the wafer W and the pressure chamber 25C can be pushed outwards and moved into the gap between the upper surface of the wafer W and the pressure chamber 25D (see Figure 7).

[0080] Furthermore, in this embodiment, during time T4, the pressure in the pressure chamber 25D is raised to the positive pressure setpoint PS4. After that, the pressure in the pressure chamber 25D is maintained at the positive pressure setpoint PS4. During time T4, the operation control unit 9 issues a command to the gas supply valve Va4 to open the gas supply valve Va4, connecting the gas supply line La4 and the pressure chamber 25D via the gas transfer line F4, and issues a command to the pressure regulator Ra4 to supply compressed gas into the pressure chamber 25D, raising the pressure in the pressure chamber 25D to the positive pressure setpoint PS4. After that, the pressure in the pressure chamber 25D is maintained at the positive pressure setpoint PS4.

[0081] In this embodiment, by forming a positive pressure in the pressure chamber 25D at time T4, the fluid Q present between the upper surface of the wafer W and the pressure chamber 25D is pushed outwards, causing the fluid Q to flow out from the upper surface of the wafer W (see Figure 8).

[0082] According to this embodiment, by setting the timing at which negative pressure is formed in the outer pressure chamber of the adjacent pressure chamber to be earlier than the timing at which positive pressure is formed in the inner pressure chamber, the overall time required to drain the fluid Q from the top surface of the wafer W can be shortened compared to the embodiment described with reference to Figures 5 to 9.

[0083] In one embodiment, lowering the pressure in the pressure chamber 25B to a negative pressure setpoint NS1 at time T0 may be done to create a negative pressure in the pressure chamber 25B to attract and hold the wafer W before the polishing head 1 touches down onto the polishing surface 2a of the polishing pad 2. In this case, after the polishing head 1 touches down onto the polishing surface 2a, the formation of a positive pressure in the pressure chamber 25A may begin and the release of the negative pressure in the pressure chamber 25B may begin, as shown at time T1 in Figure 11. This further reduces the overall time required to drain the fluid Q from the top surface of the wafer W.

[0084] The embodiments described above are intended to enable persons with ordinary skill in the art to implement the present invention. Various modifications of the above embodiments can be made naturally by those skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments as well. Therefore, the present invention is not limited to the embodiments described, but is to be interpreted in the broadest sense according to the technical idea defined by the claims. [Explanation of Symbols]

[0085] 1 Polishing head 2 polishing pads 2a Polished surface 3 Polishing Table 5. Polishing fluid supply nozzle 6 Table motors 9. Operation Control Unit 9a Storage device 9b Arithmetic unit 11 Polished Head Shaft 15 Head Arm 16 Spindle 18 Vertical movement mechanism 25A, 25B, 25C, 25D, 25E ​​Pressure Chambers 31 Careers 32 Retainer Rings 34 Elastic membrane 35 Contact area 35a Contact surface 36a,36b,36c Inner wall 36d Exterior wall 37 Membrane (Rolling Diaphragm) 40 Rotary Joint 44 Conveying device 45 Conveyor Stages 47 Lifting device 49 Horizontal movement device 53 Cleaning nozzle F1, F2, F3, F4, F5 Gas Transfer Line La1, La2, La3, La4, La5 Gas supply line Va1, Va2, Va3, Va4, Va5 Gas supply valves Ra1, Ra2, Ra3, Ra4, Ra5 pressure regulator Lb1, Lb2, Lb3, Lb4, Lb5 Vacuum Line Vb1, Vb2, Vb3, Vb4, Vb5 Vacuum valves Rb1, Rb2, Rb3, Rb4, Rb5 Vacuum Regulators Lc1, Lc2, Lc3, Lc4, Lc5 Open to the atmosphere lines Vc1, Vc2, Vc3, Vc4, Vc5 Atmospheric release valves

Claims

1. A method for polishing a wafer using a polishing head having multiple pressure chambers formed by an elastic film, The aforementioned plurality of pressure chambers are First pressure chamber and A second pressure chamber located outside the first pressure chamber, Including a third pressure chamber located outside the second pressure chamber, After the polishing head touches down onto the polishing surface, from a state where no pressure is applied to the first pressure chamber, the second pressure chamber, and the third pressure chamber, positive pressure is formed in the first pressure chamber and negative pressure is formed in the second pressure chamber, thereby moving the fluid present between the upper surface of the wafer and the first pressure chamber outwards. Subsequently, a positive pressure is formed in the second pressure chamber and a negative pressure is formed in the third pressure chamber, thereby moving the fluid present between the upper surface of the wafer and the second pressure chamber outwards. A positive pressure is formed in the outermost pressure chamber among the plurality of pressure chambers, causing the fluid present between the upper surface of the wafer and the outermost pressure chamber to move outwards, and the fluid to flow out from the upper surface of the wafer. A polishing method comprising pressing the lower surface of the wafer against the polishing surface with the elastic film thereafter to polish the lower surface of the wafer.

2. A method for polishing a wafer using a polishing head having a plurality of pressure chambers formed by an elastic film, The aforementioned plurality of pressure chambers are First pressure chamber and A second pressure chamber located outside the first pressure chamber, Including a third pressure chamber located outside the second pressure chamber, A positive pressure is formed in the first pressure chamber and a negative pressure is formed in the second pressure chamber, thereby moving the fluid present between the upper surface of the wafer and the first pressure chamber outwards. Subsequently, a positive pressure is formed in the second pressure chamber and a negative pressure is formed in the third pressure chamber, thereby moving the fluid present between the upper surface of the wafer and the second pressure chamber outwards. A positive pressure is formed in the outermost pressure chamber among the plurality of pressure chambers, causing the fluid present between the upper surface of the wafer and the outermost pressure chamber to move outwards, and the fluid to flow out from the upper surface of the wafer. Subsequently, the process includes pressing the lower surface of the wafer against the polishing surface with the elastic film to polish the lower surface of the wafer. The timing at which the positive pressure is formed in the first pressure chamber and the timing at which the negative pressure is formed in the second pressure chamber are the same. A polishing method in which the timing at which the formation of positive pressure in the second pressure chamber begins and the timing at which the formation of negative pressure in the third pressure chamber begins are the same.

3. Forming the negative pressure in the second pressure chamber includes lowering the pressure in the second pressure chamber to a negative pressure set value, and then opening the second pressure chamber to the atmosphere. The polishing method according to claim 2, wherein forming the negative pressure in the third pressure chamber includes lowering the pressure in the third pressure chamber to a negative pressure set value, and then opening the third pressure chamber to the atmosphere.

4. The timing at which the negative pressure is formed in the second pressure chamber is earlier than the timing at which the positive pressure is formed in the first pressure chamber. The polishing method according to claim 1, wherein the timing for initiating the formation of the negative pressure in the third pressure chamber is earlier than the timing for initiating the formation of the positive pressure in the second pressure chamber.

5. A method for polishing a wafer using a polishing head having a plurality of pressure chambers formed by an elastic film, The aforementioned plurality of pressure chambers are First pressure chamber and A second pressure chamber located outside the first pressure chamber, Including a third pressure chamber located outside the second pressure chamber, A positive pressure is formed in the first pressure chamber and a negative pressure is formed in the second pressure chamber, thereby moving the fluid present between the upper surface of the wafer and the first pressure chamber outwards. Subsequently, a positive pressure is formed in the second pressure chamber and a negative pressure is formed in the third pressure chamber, thereby moving the fluid present between the upper surface of the wafer and the second pressure chamber outwards. A positive pressure is formed in the outermost pressure chamber among the plurality of pressure chambers, causing the fluid present between the upper surface of the wafer and the outermost pressure chamber to move outwards, and the fluid to flow out from the upper surface of the wafer. Subsequently, the process includes pressing the lower surface of the wafer against the polishing surface with the elastic film to polish the lower surface of the wafer. The timing at which the negative pressure is formed in the second pressure chamber is earlier than the timing at which the positive pressure is formed in the first pressure chamber. The timing at which the negative pressure is formed in the third pressure chamber is earlier than the timing at which the positive pressure is formed in the second pressure chamber. Forming the negative pressure in the second pressure chamber includes lowering the pressure in the second pressure chamber to a negative pressure set value, and then eliminating the negative pressure in the second pressure chamber, and forming the positive pressure in the first pressure chamber is performed while the negative pressure in the second pressure chamber is being eliminated. A polishing method comprising forming the negative pressure in the third pressure chamber, which includes lowering the pressure in the third pressure chamber to a negative pressure set value, and then eliminating the negative pressure in the third pressure chamber, and forming the positive pressure in the second pressure chamber, which is performed while the negative pressure in the third pressure chamber is being eliminated.

6. The polishing method according to claim 1, wherein the first pressure chamber is located in the central part of the elastic membrane.

7. Forming the positive pressure in the first pressure chamber includes raising the pressure in the first pressure chamber to a first positive pressure setpoint, and then maintaining the pressure in the first pressure chamber at the first positive pressure setpoint. The polishing method according to any one of claims 1 to 6, wherein forming the positive pressure in the second pressure chamber includes raising the pressure in the second pressure chamber to a second positive pressure setpoint, and then maintaining the pressure in the second pressure chamber at the second positive pressure setpoint.

8. A polishing apparatus for polishing wafers, A polishing head having a plurality of pressure chambers formed by an elastic film, which presses the wafer against the polishing surface in the plurality of pressure chambers, The polishing device is equipped with an operation control unit that controls the operation of the polishing device, The aforementioned plurality of pressure chambers are First pressure chamber and A second pressure chamber located outside the first pressure chamber, Including a third pressure chamber located outside the second pressure chamber, The aforementioned operation control unit, After the polishing head touches down onto the polishing surface, from a state where no pressure is applied to the first pressure chamber, the second pressure chamber, and the third pressure chamber, positive pressure is formed in the first pressure chamber and negative pressure is formed in the second pressure chamber, thereby moving the fluid present between the upper surface of the wafer and the first pressure chamber outwards. Subsequently, a positive pressure is formed in the second pressure chamber and a negative pressure is formed in the third pressure chamber, thereby moving the fluid present between the upper surface of the wafer and the second pressure chamber outwards. A positive pressure is formed in the outermost pressure chamber among the plurality of pressure chambers, causing the fluid present between the upper surface of the wafer and the outermost pressure chamber to move outwards, and the fluid to flow out from the upper surface of the wafer. The polishing apparatus is configured to operate in such a way that it then presses the lower surface of the wafer against the polishing surface using the elastic film, thereby polishing the lower surface of the wafer.

9. A polishing apparatus for polishing wafers, A polishing head having a plurality of pressure chambers formed by an elastic film, which presses the wafer against the polishing surface in the plurality of pressure chambers, The polishing device is equipped with an operation control unit that controls the operation of the polishing device, The aforementioned plurality of pressure chambers are First pressure chamber and A second pressure chamber located outside the first pressure chamber, Including a third pressure chamber located outside the second pressure chamber, The aforementioned operation control unit, A positive pressure is formed in the first pressure chamber and a negative pressure is formed in the second pressure chamber, thereby moving the fluid present between the upper surface of the wafer and the first pressure chamber outwards. Subsequently, a positive pressure is formed in the second pressure chamber and a negative pressure is formed in the third pressure chamber, thereby moving the fluid present between the upper surface of the wafer and the second pressure chamber outwards. A positive pressure is formed in the outermost pressure chamber among the plurality of pressure chambers, causing the fluid present between the upper surface of the wafer and the outermost pressure chamber to move outwards, and the fluid to flow out from the upper surface of the wafer. Subsequently, the polishing device is configured to operate in such a way that the elastic film presses the lower surface of the wafer against the polishing surface to polish the lower surface of the wafer. The aforementioned operation control unit, The polishing device is operated such that the timing at which the positive pressure is formed in the first pressure chamber and the timing at which the operation control unit starts forming the negative pressure in the second pressure chamber are the same. A polishing apparatus configured to operate such that the timing at which the operation control unit starts forming the positive pressure in the second pressure chamber and the timing at which the operation control unit starts forming the negative pressure in the third pressure chamber are the same.

10. The aforementioned operation control unit, The polishing apparatus is operated such that forming the negative pressure in the second pressure chamber includes lowering the pressure in the second pressure chamber to a negative pressure set value, and then opening the second pressure chamber to the atmosphere. The polishing apparatus according to claim 9, wherein the polishing apparatus is operated such that forming the negative pressure in the third pressure chamber includes lowering the pressure in the third pressure chamber to a negative pressure set value, and then opening the third pressure chamber to the atmosphere.

11. The aforementioned operation control unit, The polishing device is operated such that the timing at which the negative pressure is formed in the second pressure chamber is earlier than the timing at which the positive pressure is formed in the first pressure chamber. The polishing apparatus according to claim 8, wherein the operation control unit is configured to operate the polishing apparatus such that the timing at which the negative pressure is formed in the third pressure chamber is earlier than the timing at which the positive pressure is formed in the second pressure chamber.

12. A polishing apparatus for polishing wafers, A polishing head having a plurality of pressure chambers formed by an elastic film, which presses the wafer against the polishing surface in the plurality of pressure chambers, The polishing device is equipped with an operation control unit that controls the operation of the polishing device, The aforementioned plurality of pressure chambers are First pressure chamber and A second pressure chamber located outside the first pressure chamber, Including a third pressure chamber located outside the second pressure chamber, The aforementioned operation control unit, A positive pressure is formed in the first pressure chamber and a negative pressure is formed in the second pressure chamber, thereby moving the fluid present between the upper surface of the wafer and the first pressure chamber outwards. Subsequently, a positive pressure is formed in the second pressure chamber and a negative pressure is formed in the third pressure chamber, thereby moving the fluid present between the upper surface of the wafer and the second pressure chamber outwards. A positive pressure is formed in the outermost pressure chamber among the plurality of pressure chambers, causing the fluid present between the upper surface of the wafer and the outermost pressure chamber to move outwards, and the fluid to flow out from the upper surface of the wafer. Subsequently, the polishing device is configured to operate in such a way that the elastic film presses the lower surface of the wafer against the polishing surface to polish the lower surface of the wafer. The aforementioned operation control unit, The polishing device is operated such that the timing at which the negative pressure is formed in the second pressure chamber is earlier than the timing at which the positive pressure is formed in the first pressure chamber. The operation control unit is configured to operate the polishing apparatus such that the timing at which the negative pressure is formed in the third pressure chamber is earlier than the timing at which the positive pressure is formed in the second pressure chamber. The aforementioned operation control unit, The polishing device is operated such that forming the negative pressure in the second pressure chamber includes lowering the pressure in the second pressure chamber to a negative pressure set value and then eliminating the negative pressure in the second pressure chamber, and forming the positive pressure in the first pressure chamber is performed while the negative pressure in the second pressure chamber is being eliminated. A polishing apparatus configured to operate such that forming the negative pressure in the third pressure chamber includes lowering the pressure in the third pressure chamber to a negative pressure set value, and then releasing the negative pressure in the third pressure chamber, and forming the positive pressure in the second pressure chamber is performed while the negative pressure in the third pressure chamber is being released.

13. The polishing apparatus according to claim 8, wherein the first pressure chamber is located in the central part of the elastic membrane.

14. The aforementioned operation control unit, The polishing apparatus is operated such that forming the positive pressure in the first pressure chamber includes raising the pressure in the first pressure chamber to a first positive pressure setpoint, and then maintaining the pressure in the first pressure chamber at the first positive pressure setpoint. The polishing apparatus according to any one of claims 8 to 13, wherein the polishing apparatus is operated such that forming the positive pressure in the second pressure chamber includes raising the pressure in the second pressure chamber to a second positive pressure setpoint, and then maintaining the pressure in the second pressure chamber at the second positive pressure setpoint.

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