JP2023090770A - Method for removing liquid from upper face of wafer to be polished - Google Patents

Abstract

To provide a method for removing a liquid from an upper face of a wafer to be polished, and applying appropriate force to the wafer by a polishing head.SOLUTION: A method removes a liquid from an upper face of a wafer W on a conveyance device 44, then holds the wafer W on the conveyance device 44 by a polishing head 1, pushes the lower face of the wafer W against a polished surface 2a by the polishing head 1, and polishes the lower face of the wafer W.SELECTED DRAWING: Figure 3

Description

The present invention relates to techniques for removing liquid from the top surface of a wafer before or during polishing of the wafer.

Chemical mechanical polishing (CMP) is a technique for polishing the surface of a wafer by pressing the wafer against the polishing surface while slurry is being supplied onto the polishing surface and bringing the wafer into sliding contact with the polishing surface in the presence of the slurry. . During polishing of the wafer, the wafer is pressed against the polishing surface by the polishing head. The surface of the wafer is flattened by the chemical action of the slurry and the mechanical action of abrasive grains contained in the slurry.

FIG. 28 is a cross-sectional view schematically showing a polishing head. Polishing head 600 has an elastic membrane 610 in contact with the top surface of wafer W1. This elastic membrane 610 has a shape that forms a plurality of pressure chambers 601-604, and the pressure in each of the pressure chambers 601-604 can be adjusted independently. Therefore, the polishing head 600 can press a plurality of regions of the wafer W1 corresponding to these pressure chambers 601 to 604 with different forces to achieve a desired film thickness profile of the wafer W1.

After the polishing of the wafer W1 is completed, the polished wafer W1 is transferred to the next process by the transfer device. As shown in FIG. 29, the next wafer W2 is carried to the transfer position below the polishing head 600 by the carrier device. At the same time, the polishing head 600 is washed with a liquid (for example, pure water) to remove slurry and polishing debris from the polishing head 600 . Then, the next wafer W2 is held by the polishing head 600 and transported by the polishing head 600 to a position above the polishing surface. Wafer W2 is pressed against the polishing surface by polishing head 600 and polished in the presence of slurry.

Japanese Patent Application Laid-Open No. 2003-11056 Japanese Patent Application Laid-Open No. 2005-313312 JP 2007-242655 A

However, as shown in FIG. 30, the liquid Q used for cleaning the polishing head 600 may exist between the upper surface of the wafer W2 and the elastic film 610 of the polishing head 600. FIG. If this liquid Q spreads over a plurality of pressure chambers, the pressure in the adjacent pressure chambers will be transmitted to the liquid Q, and an unintended force will be applied to the wafer W2. In the example shown in FIG. 30, although the pressure in the central pressure chamber 601 is lowered in order to lower the polishing rate in the central portion of the wafer W2, the pressure in the adjacent pressure chamber 602 increases the pressure of the wafer W2 through the liquid Q. Join the central part of W2. As a result, the polishing rate of the central portion of the wafer W cannot be lowered. Thus, the liquid Q existing between the wafer W2 and the polishing head 600 prevents the polishing head 600 from applying an appropriate force to the wafer W2.

Accordingly, the present invention provides a method of removing liquid from the top surface of the wafer being polished to allow the polishing head to apply the appropriate force to the wafer.

In one aspect, a method of polishing a wafer using a polishing head comprises removing liquid from a top surface of the wafer on a carrier, thereafter holding the wafer on the carrier with the polishing head, and A method is provided for polishing the underside of the wafer by pressing the underside of the wafer against a polishing surface with a polishing head.

In one aspect, the step of removing liquid from the upper surface of the wafer on the transport device is removing liquid from the upper surface of the wafer by tilting the wafer with the transport device.
In one aspect, removing liquid from the top surface of the wafer on the carrier includes removing liquid from the top surface of the wafer by agitating the wafer with the carrier.
In one aspect, removing liquid from the top surface of the wafer on the carrier comprises removing liquid from the top surface of the wafer by directing a jet of gas onto the top surface of the wafer on the carrier. .

According to one aspect, there is provided a method of polishing a wafer using a polishing head having a central pressure chamber and an outer pressure chamber formed by an elastic film, wherein the central portion of the elastic film is brought into contact with the central portion of the upper surface of the wafer. Then, the outer peripheral portion of the elastic film is brought into contact with the outer peripheral portion of the upper surface of the wafer to remove the liquid from the upper surface of the wafer, and the elastic film presses the lower surface of the wafer against the polishing surface, thereby A method is provided for polishing the underside of a wafer.
In one aspect, the central portion of the elastic film is brought into contact with the central portion of the upper surface of the wafer while the pressure in the central pressure chamber is higher than the pressure in the outer pressure chamber.
In one aspect, the center side pressure chamber communicates with an air cylinder, and a weight is placed on the piston of the air cylinder.

In one aspect, a method of polishing a wafer using a polishing head having a central pressure chamber and an outer pressure chamber formed by an elastic membrane, wherein the elastic membrane is brought into contact with the upper surface of the wafer, and then the outer side is A vacuum is formed in the outer pressure chamber and the central pressure chamber in order of the pressure chamber and the central pressure chamber to move the liquid existing on the upper surface of the wafer to the outside. A method is provided for polishing the lower surface of the wafer by pressing the lower surface against the polishing surface to remove liquid from the upper surface of the wafer and bringing the lower surface of the wafer into sliding contact with the polishing surface with the polishing head.

In one aspect, a compressed gas is supplied to the central pressure chamber and the outer pressure chamber in that order, so that the elastic film presses the lower surface of the wafer against the polishing surface. , removing liquid from the top surface of the wafer;
In one aspect, the outer pressure chamber and the central pressure chamber include at least a first pressure chamber, a second pressure chamber, and a third pressure chamber, and the second pressure chamber is located outside the first pressure chamber. The third pressure chamber is located outside the second pressure chamber, and the third pressure chamber, the second pressure chamber and the first pressure chamber are arranged in this order. A vacuum is created within the chamber, the first pressure chamber, to displace liquid present on top of the wafer outward.

According to one aspect, there is provided a method of polishing a wafer using a polishing head having an elastic membrane, wherein the elastic membrane is brought into contact with the upper surface of the wafer, and liquid flow paths formed in the elastic membrane flow through the upper surface of the wafer. A method is provided for polishing the bottom surface of the wafer by removing the liquid from the top surface of the wafer by flowing the liquid present in the wafer and then forcing the bottom surface of the wafer against the polishing surface with the elastic membrane.

In one aspect, the elastic membrane has a contact surface that contacts the upper surface of the wafer, and the liquid flow path includes an opening that opens at the contact surface, and is connected to the opening and and has a lateral aperture that opens at the outer surface of the elastic membrane.
In one aspect, the step of causing the liquid existing on the upper surface of the wafer to flow into the liquid flow channel is a step of sucking the liquid existing on the upper surface of the wafer through the liquid flow channel, and the liquid flow channel It communicates with a suction line connected to the elastic membrane.
In one aspect, the elastic membrane has a contact surface that contacts the upper surface of the wafer, and the liquid channel is a groove formed in the contact surface.
In one aspect, the width of the groove inside the elastic membrane is greater than the width of the groove at the contact surface.

In one aspect, an elastic membrane for pressing a wafer against a polishing surface includes a contact portion having a contact surface capable of contacting the wafer, and an outer wall portion connected to the contact portion, wherein the contact portion includes the An elastic membrane is provided having an aperture opening at the contact surface and a transverse hole connected to the aperture and extending through the contact.
In one aspect, the lateral hole is open on the outer surface of the elastic membrane.
In one aspect, the lateral hole is open on a surface of the contact portion opposite to the contact surface.

In one aspect, an elastic membrane for pressing a wafer against a polishing surface includes a contact portion having a contact surface capable of contacting the wafer, and an outer wall portion connected to the contact portion, wherein the contact portion includes the An elastic membrane is provided having grooves formed in the contact surface.
In one aspect, the width of the groove inside the contact portion is greater than the width of the groove at the contact surface.

According to the present invention, the liquid is removed from the upper surface of the wafer before or immediately after the wafer is polished. As a result, the elastic membrane forming the pressure chamber can apply an intended force to the wafer, and a desired film thickness profile of the wafer can be achieved.

1 is a schematic diagram showing an embodiment of a polishing apparatus; FIG. It is a cross-sectional view showing a polishing head. FIG. 2 is a top view of a transport device that transports a wafer to the polishing head shown in FIG. 1; FIG. 4 is a schematic diagram showing the polishing head when removing liquid from the top surface of the wafer; FIG. 4 is a schematic diagram showing how the elastic film of the polishing head pushes out the liquid existing on the upper surface of the wafer. FIG. 5 is a schematic diagram showing how the elastic film of the polishing head further pushes the liquid present on the upper surface of the wafer to the outside. FIG. 10 is a diagram illustrating an embodiment in which a combination of an air cylinder and a weight is used instead of a pressure regulator to inflate the central portion of the elastic membrane; FIG. 4 is a schematic diagram showing another embodiment of an elastic membrane; FIG. 10 is a schematic diagram showing still another embodiment of the elastic membrane; [0014] Figure 4 illustrates another embodiment of a method for removing liquid from the top surface of a wafer; 11 is a diagram further explaining the embodiment shown in FIG. 10; FIG. 11 is a diagram further explaining the embodiment shown in FIG. 10; FIG. 11 is a diagram further explaining the embodiment shown in FIG. 10; FIG. [0014] Figure 4 illustrates yet another embodiment of a method of removing liquid from the top surface of a wafer; 15 is a diagram further explaining the embodiment shown in FIG. 14; FIG. 15 is a diagram further explaining the embodiment shown in FIG. 14; FIG. [0014] Figure 4 illustrates yet another embodiment of a method of removing liquid from the top surface of a wafer; 18 is a diagram further explaining the embodiment shown in FIG. 17; FIG. [0014] Figure 4 illustrates yet another embodiment of a method of removing liquid from the top surface of a wafer; FIG. 20 is a diagram further explaining the embodiment shown in FIG. 19; [0013] Figure 1B is a cross-sectional view illustrating one embodiment of an elastic membrane capable of removing liquid from the top surface of a wafer. FIG. 22 is a schematic diagram showing how the elastic membrane shown in FIG. 21 removes liquid from the top surface of the wafer; FIG. 10 is a cross-sectional view showing another embodiment of an elastic membrane capable of removing liquid from the top surface of a wafer; FIG. 24 is a schematic diagram showing how the elastic membrane shown in FIG. 23 removes liquid from the top surface of the wafer; FIG. 10 is a cross-sectional view of yet another embodiment of an elastic membrane capable of removing liquid from the top surface of a wafer; 26 is a bottom view of the elastic membrane shown in FIG. 25; FIG. FIG. 26 is a schematic diagram showing how the elastic membrane shown in FIG. 25 removes liquid from the top surface of the wafer; It is a sectional view showing a polish head typically. It is a figure explaining a mode that the polishing head is wash|cleaned. FIG. 4 is a diagram illustrating a problem caused by a liquid existing between the upper surface of the wafer and the elastic membrane of the polishing head;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing one embodiment of a polishing apparatus. As shown in FIG. 1, the polishing apparatus includes 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 substrate, against the polishing pad 2, and a table motor 6 that rotates the polishing table 3. , and a slurry supply nozzle 5 for supplying slurry onto the polishing pad 2 . The surface of the polishing pad 2 constitutes a polishing surface 2a for polishing the wafer W. As shown in FIG.

The polishing table 3 is connected to a table motor 6 so as to rotate the polishing table 3 and the polishing pad 2 together. The polishing head 1 is fixed to the end of a 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 the support shaft 16 .

Wafer W is polished as follows. While rotating the polishing table 3 and the polishing head 1 in the direction indicated by the arrow in FIG. While being rotated by the polishing head 1 , the wafer W is pressed against the polishing surface 2 a of the polishing pad 2 by the polishing head 1 with slurry existing between the polishing pad 2 and the wafer W. The surface of the wafer W is polished by the chemical action of the slurry and the mechanical action of abrasive grains contained in the slurry.

The polishing apparatus further includes an operation control section 9 that controls operations of the polishing head 1 , polishing table 3 and slurry supply nozzle 5 . The operation control unit 9 is composed of at least one computer.

Next, the polishing head 1 will be explained. FIG. 2 is a sectional view showing the polishing head 1. As shown in FIG. The polishing head 1 includes 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 arranged below the carrier 31 . The retainer ring 32 is arranged around the elastic membrane 34 . The retainer ring 32 is an annular structure that holds the wafer W in order to prevent the wafer W from jumping out of the polishing head 1 while the wafer W is being polished.

The elastic film 34 includes a contact portion 35 having a contact surface 35a capable of contacting the upper surface of the wafer W, and inner wall portions 36a, 36b, 36c and an outer wall portion 36d connected to the contact portion 35. As shown in FIG. The contact portion 35 has substantially the same size and shape as the upper surface of the wafer W. As shown in FIG. The inner walls 36a, 36b, 36c and the outer wall 36d are concentrically arranged endless walls. 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 invention is not limited to this embodiment. In one embodiment, only one or two inner walls may be provided, or four or more inner walls may be provided.

Four 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 of the elastic membrane 34, the inner wall portions 36a, 36b and 36c and the outer wall portion 36d. That is, the pressure chamber 25A is positioned within the inner wall portion 36a, the pressure chamber 25B is positioned between the inner wall portion 36a and the inner wall portion 36b, the pressure chamber 25C is positioned between the inner wall portion 36b and the inner wall portion 36c, The pressure chamber 25D is positioned between the inner wall portion 36c and the outer wall portion 36d. The central pressure chamber 25A is circular and the other pressure chambers 25B, 25C, 25D are annular. These pressure chambers 25A, 25B, 25C and 25D are arranged concentrically. The pressure chamber 25B is located outside the pressure chamber 25A, the pressure chamber 25C is located outside the pressure chamber 25B, and the pressure chamber 25D is located outside the pressure chamber 25C.

Gas transfer lines F1, F2, F3 and F4 are connected to the pressure chambers 25A, 25B, 25C and 25D, respectively. One end of the gas transfer lines F1, F2, F3, F4 is connected to a compressed gas supply (not shown) as a utility supply provided at the factory where the polishing apparatus is installed. Compressed gas such as compressed air is supplied to pressure chambers 25A, 25B, 25C and 25D through gas transfer lines F1, F2, F3 and F4, respectively.

An annular membrane (rolling diaphragm) 37 is arranged between the carrier 31 and the retainer ring 32, and a pressure chamber 25E is formed inside the membrane 37. As shown in FIG. The pressure chamber 25E is connected to the compressed gas supply source via a gas transfer line F5. Compressed gas is supplied into the pressure chamber 25E through the gas transfer line F5, and the pressure chamber 25E presses the retainer ring 32 against the polishing surface 2a of the polishing pad 2. As shown in FIG.

Gas transfer lines F 1 , F 2 , F 3 , F 4 and F 5 extend through rotary joint 40 attached to polishing head shaft 11 . Pressure regulators R1, R2, R3, R4 and R5 are provided in the gas transfer lines F1, F2, F3, F4 and F5 communicating with the pressure chambers 25A, 25B, 25C, 25D and 25E, respectively. Compressed gas from a compressed gas supply is supplied independently into pressure chambers 25A-25E through pressure regulators R1-R5. Pressure regulators R1-R5 are configured to regulate the pressure of the compressed gas within pressure chambers 25A-25E.

The pressure regulators R1-R5 are capable of varying the internal pressures of the pressure chambers 25A-25E independently of each other, thereby adjusting the four corresponding regions of the wafer W: center, inner middle and outer. The polishing pressure for the intermediate portion and the edge portion and the pressing force of the retainer ring 32 against the polishing pad 2 can be adjusted independently. The gas transfer lines F1, F2, F3, F4, and F5 are also connected to air release valves (not shown) so that the pressure chambers 25A to 25E can be opened to the atmosphere. In this embodiment, the elastic membrane 34 forms four pressure chambers 25A-25D, but in one embodiment, the elastic membrane 34 may form less than four pressure chambers or more than four pressure chambers. good.

The pressure regulators R1-R5 are connected to the operation controller 9. FIG. The operation control unit 9 sends the respective target pressure values of the pressure chambers 25A-25E to the pressure regulators R1-R5, and the pressure regulators R1-R5 maintain the pressures in the pressure chambers 25A-25E at the corresponding target pressure values. works like

The polishing head 1 can apply independent polishing pressures to a plurality of regions of the wafer W, respectively. For example, the polishing head 1 can press different regions of the surface of the wafer W 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 the target film thickness profile.

Vacuum lines L1, L2, L3, L4 and L5 are connected to gas transfer lines F1, F2, F3, F4 and F5, respectively. Vacuum valves V1, V2, V3, V4 and V5 are attached to the vacuum lines L1, L2, L3, L4 and L5, respectively. The vacuum valves V1, V2, V3, V4 and V5 are actuator driven valves such as solenoid valves, motorized valves or air operated valves. The vacuum valves V1 to V5 are connected to the operation control section 9, and the operations of the vacuum valves V1 to V5 are controlled by the operation control section 9. FIG. Opening a vacuum line L1, L2, L3, L4, L5 creates a vacuum in the corresponding pressure chamber 25A, 25B, 25C, 25D, 25E.

When the polishing head 1 holds the wafer W, the vacuum valves V2, V3 and V4 are opened to form a vacuum in the pressure chambers 25B, 25C and 25D while the contact portion 35 of the elastic film 34 is in contact with the wafer W. do. The portions of the contact portion 35 forming these pressure chambers 25B, 25C, and 25D are recessed upward, and the polishing head 1 can suck the wafer W by the sucker effect of the elastic film 34. FIG. Further, the polishing head 1 can release the wafer W by supplying compressed gas to the pressure chambers 25B, 25C, and 25D to cancel the sucker effect.

FIG. 3 is a top view of a transfer device that transfers a wafer to the polishing head 1 shown in FIG. As shown in FIG. 3, the wafer W is transferred to the polishing head 1 by the transfer device 44 . The polishing head 1 is movable between a polishing position P1 indicated by a solid line in FIG. 3 and a delivery position P2 indicated by a dotted line. More specifically, the head arm 15 rotates about the support shaft 16 so that the polishing head 1 can move between the polishing position P1 and the transfer position P2. The polishing position P1 is above the polishing surface 2a of the polishing pad 2, and the transfer position P2 is positioned outside the polishing surface 2a.

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 movement device 49 that horizontally moves the transport stage 45 and the lifting device 47 together. ing. A wafer W to be polished is placed on the carrier stage 45 and moved together with the carrier stage 45 to the delivery position P2 by the horizontal movement device 49 . When the polishing head 1 is at the transfer position P2, the lifting device 47 lifts the carrier stage 45. As shown in FIG. The polishing head 1 holds the wafer W on the carrier stage 45 and moves together with the wafer W to the polishing position P1.

The slurry supply nozzle 5 supplies slurry to the polishing surface 2a of the rotating polishing pad 2, while the polishing head 1 presses the wafer W against the polishing surface 2a of the polishing pad 2 while rotating the wafer W, thereby W is brought into sliding contact with the polishing surface 2a. The lower surface of the wafer W is polished by the chemical action of the slurry and the mechanical action of abrasive grains contained in the slurry.

After polishing the wafer W, the polishing head 1 moves together with the wafer W to the delivery position P2. Then, the polished wafer W is transferred to the carrier stage 45 . The carrier stage 45 moves the wafer W to the next process. A cleaning nozzle 53 for cleaning the polishing head 1 by supplying a liquid (for example, a rinsing liquid such as pure water) to the polishing head 1 is arranged at the delivery position P2. The cleaning nozzle 53 faces the polishing head 1 . After releasing the wafer W, the polishing head 1 is cleaned with the liquid supplied from the cleaning nozzle 53 .

During cleaning of the polishing head 1 , the next wafer to be polished is moved by the carrier stage 45 to the receiving position P<b>2 below the polishing head 1 . When the cleaning of the polishing head 1 is finished, the lifting device 47 lifts the carrier 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 manner, multiple wafers are continuously polished.

However, during cleaning of the polishing head 1, the next wafer to be polished is moved to the receiving position P2 below the polishing head 1, so that the liquid falls on the upper surface of the wafer. Liquid present on the top surface of the wafer prevents the polishing head 1 from applying proper force to the wafer, as described with reference to FIG. One solution is to move the next wafer to the receiving position P2 after the polishing head 1 has finished cleaning. However, such operations reduce the throughput of the polishing apparatus.

Therefore, in this embodiment, the liquid is removed from the upper surface of the wafer as follows. FIG. 4 is a schematic diagram showing the polishing head 1 when removing liquid from the upper surface of the wafer. 4, the detailed configuration of the polishing head 1 is omitted. Before holding the wafer W to be polished, the pressure in the central pressure chambers 25A, 25B, 25C of the polishing head 1 is made higher than the pressure in the outer pressure chamber 25D. More specifically, the operation control unit 9 issues commands to the pressure regulators R1, R2, R3 (see FIG. 2) to supply compressed gas into the pressure chambers 25A, 25B, 25C, while operating The controller 9 opens the vacuum valve V4 to form a vacuum in the pressure chamber 25D.

In one embodiment, the operation control unit 9 opens the atmosphere release valves (not shown) connected to the gas transfer lines F1, F2, and F3 to release the pressure chambers 25A, 25B, and 25C to the atmosphere. Then, the operation control unit 9 may open the vacuum valve V4 to form a vacuum in the pressure chamber 25D. Further, in one embodiment, the motion controller 9 commands the pressure regulators R1, R2, R3 (see FIG. 2) to supply compressed gas into the pressure chambers 25A, 25B, 25C, while The operation control unit 9 may open the atmosphere release valve (not shown) connected to the gas transfer line F4 to release the inside of the pressure chamber 25D to the atmosphere.

The difference between the pressure in the pressure chambers 25A, 25B, 25C and the pressure in the pressure chamber 25D swells the central portion of the contact portion 35 of the elastic membrane 34 and pushes the central portion of the contact portion 35 toward the wafer W. protrude. The polishing head 1 descends toward the wafer W with the central portion of the contact portion 35 protruding, and the elastic film 34 is brought into contact with the upper surface of the wafer W. As shown in FIG. As shown in FIG. 5, the central portion of the elastic membrane 34, ie, the central portion of the contact portion 35, contacts the central portion of the upper surface of the wafer W first. The elastic film 34 pushes the liquid Q existing on the upper surface of the wafer W to the outside.

Further, the polishing head 1 is lowered to bring most of the contact portion 35 into contact with the upper surface of the wafer W. Then, as shown in FIG. More specifically, as shown in FIG. 6, in a state in which the central portion of the elastic film 34 is in contact with the central portion of the upper surface of the wafer W, the outer peripheral portion of the elastic film 34, that is, the outer peripheral portion of the contact portion 35 is pressed against the wafer. It is brought into contact with the outer periphery of the upper surface of W. The elastic film 34 further pushes the liquid Q existing on the upper surface of the wafer W to the outside and removes the liquid Q from the upper surface of the wafer W. As shown in FIG. After that, the elastic film 34 of the polishing head 1 brings the lower surface of the wafer W into sliding contact with the polishing surface 2a in the presence of the slurry on the polishing surface 2a, and the chemical action of the slurry and the mechanical action of the abrasive grains contained in the slurry. Polish with

In this manner, the liquid Q existing on the upper surface of the wafer W is moved to the outside of the wafer W by the elastic film 34 protruding at the central portion, and removed from the upper surface of the wafer W. FIG. Therefore, the polishing head 1 can hold the wafer W in a state where there is substantially no liquid Q between the elastic film 34 and the upper surface of the wafer W. As a result, the elastic membrane 34 forming the pressure chambers 25A, 25B, 25C, 25D can apply the intended force to the wafer W, and the polishing head 1 can achieve the desired film thickness profile of the wafer W. .

Since the elastic membrane 34 is flexible, the elastic membrane 34 easily expands even if the pressure in the pressure chambers 25A, 25B, and 25C is low. If the swelling of the elastic film 34 is too large, there is a possibility that an excessive load will be applied to the wafer W when the elastic film 34 presses the wafer W against it. Although it is possible to maintain the pressure chambers 25A, 25B, and 25C at a low pressure (for example, 25 hPa or less) by the pressure regulators R1, R2, and R3, it takes a long time to reduce the pressure to the target low pressure, and The pressure inside the pressure chambers 25A, 25B, 25C may not be stable.

Therefore, in one embodiment, as shown in FIG. 7, instead of the pressure regulators R1, R2, R3, a combination of an air cylinder 41 and a weight 42 is used to supply compressed gas to the pressure chambers 25A, 25B, 25C. send. The pressure chambers 25A, 25B, 25C communicate with a common air cylinder 41 via gas transfer lines F1, F2, F3. The air cylinder 41 is arranged in a vertical posture. Before the polishing head 1 holds the wafer W, the weight 42 is placed on the piston 41A of the air cylinder 41 to push the piston 41A downward. Since the gas in the air cylinder 41 is sent into the pressure chambers 25A, 25B, 25C, the central portion of the elastic membrane 34 expands. Similar to the embodiment shown in FIG. 4, a vacuum is formed in pressure chamber 25D. In one embodiment, the operation control section 9 may open the atmosphere release valve (not shown) connected to the gas transfer line F4 to release the pressure chamber 25D to the atmosphere.

The swelling of the elastic membrane 34 is adjusted by the diameter of the air cylinder 41 and the stroke distance of the piston 41A. If the weight 42 is too light, the elastic membrane 34 will not swell and the piston 41A will stop halfway. According to this embodiment, the combination of the air cylinder 41 and the weight 42 can stably maintain the low pressure in the pressure chambers 25A, 25B, 25C, and as a result, the expansion of the elastic membrane 34 can be appropriately controlled. can do.

FIG. 8 is a schematic diagram showing another embodiment of the elastic membrane 34. As shown in FIG. In this embodiment, the longitudinal length of inner walls 36a, 36b, 36c is greater than the longitudinal length of outer wall 36d, and the lower ends of inner walls 36a, 36b, 36c are lower than the lower ends of outer wall 36d. in position. The difference in vertical length between the inner wall portions 36a, 36b, 36c and the outer wall portion 36d causes the central portion of the contact portion 35 of the elastic film 34 to protrude toward the wafer W. FIG.

FIG. 9 is a schematic diagram showing another embodiment of the polishing head 1. FIG. In this embodiment, the lower portion of carrier 31 has a first surface 31a to which inner walls 36a, 36b, 36c are fixed and a second surface 31b to which outer wall 36d is fixed. The first surface 31a is positioned lower than the second surface 31b. The lower ends of the inner wall portions 36a, 36b, 36c are positioned lower than the lower end of the outer wall portion 36d. The difference in height between the first surface 31a and the second surface 31b of the carrier 31 causes the central portion of the contact portion 35 of the elastic film 34 to protrude toward the wafer W. FIG.

The elastic membrane 34 shown in FIGS. 8 and 9 pushes out the liquid Q existing on the upper surface of the wafer W when it comes into contact with the upper surface of the wafer W, as in the embodiment shown in FIGS. , the liquid Q can be removed from the top surface of the wafer W. FIG. In addition, in the embodiment shown in FIGS. 8 and 9, it is not necessary to provide a difference between the pressure in the pressure chambers 25A, 25B, 25C and the pressure in the pressure chamber 25D. Specifically, pressure regulators R1, R2, R3, and R4 may maintain the same pressure of compressed gas within pressure chambers 25A, 25B, 25C, and 25D.

Another embodiment of a method for removing liquid from the top surface of the wafer W will now be described with reference to FIGS. 10-13. Details of the present embodiment that are not particularly described are the same as those of the above-described embodiment, and redundant description thereof will be omitted.

The polishing head 1 is lowered toward the upper surface of the wafer W as shown in FIG. A liquid Q exists on the upper surface of the wafer W. As shown in FIG. As shown in FIG. 11, the contact portion 35 of the elastic film 34 is brought into contact with the liquid Q on the upper surface of the wafer W, and the contact portion 35 of the elastic film 34 is pressed against the upper surface of the wafer W. As shown in FIG. At this time, part of the liquid Q spills down from the upper surface of the wafer W. As shown in FIG.

As shown in FIG. 12, the pressure chambers 25D, 25C, and 25B are evacuated in order from the outer pressure chamber 25D to the central pressure chamber 25B (that is, in the order of the pressure chambers 25D, 25C, and 25B). are formed sequentially. The portions of the contact portions 35 forming the pressure chambers 25D, 25C, and 25B are depressed upward by the vacuum, and a space is formed between the elastic film 34 and the upper surface of the wafer W. FIG. The liquid Q on the upper surface of the wafer W sequentially flows into these spaces, and a flow of the liquid Q toward the outside of the wafer W is formed.

After that, the polishing head 1 carries the wafer W to a position above the polishing pad 2, and presses the lower surface of the wafer W against the polishing surface 2a of the polishing pad 2 with the elastic film 34, as shown in FIG. At this time, the operation control unit 9 issues commands to the pressure regulators R2, R3, and R4 in order from the pressure chamber 25B located on the center side to the pressure chamber 25D located on the outer side (that is, the pressure chambers 25B, 25C, 25C, 25D). 25D) to supply compressed gas into the pressure chambers 25B, 25C and 25D. The liquid Q held in the space between the elastic film 34 and the upper surface of the wafer W is pushed by the contact portion 35 of the elastic film 34 to move to the outside of the wafer W and removed from the upper surface of the wafer W. .

After that, the elastic film 34 of the polishing head 1 brings the lower surface of the wafer W into sliding contact with the polishing surface 2a in the presence of the slurry on the polishing surface 2a, and the chemical action of the slurry and the mechanical action of the abrasive grains contained in the slurry. Polish with

Another embodiment of a method for removing liquid from the top surface of the wafer W will now be described with reference to FIGS. 14-16. Details of the present embodiment that are not particularly described are the same as those of the above-described embodiment, and redundant description thereof will be omitted. FIG. 14 is a schematic diagram showing a modification of the conveying device 44 shown in FIG. The details of this embodiment that are not specifically described are the same as those of the embodiment shown in FIG. 3, so redundant description thereof will be omitted.

As shown in FIG. 14 , the transport device 44 includes a tilting device 55 that tilts the transport stage 45 . The tilting device 55 is held by an elevating device 47 and vertically moved integrally with the carrier stage 45 . The tilting device 55 has a horizontally extending support shaft 55a and a rotating device 55b for rotating the support shaft 55a. The support shaft 55 a is connected to the carrier stage 45 , and the rotating device 55 b is fixed to the lifting device 47 . The rotating device 55b is configured to rotate the support shaft 55a and the carrier stage 45 by a predetermined angle. The rotating device 55b includes an actuator (not shown) such as a servomotor.

The wafer W on the carrier stage 45 is moved to the delivery position P2 by the horizontal movement device 49 . The polishing head 1 is cleaned with liquid supplied from the cleaning nozzle 53 . The liquid used for cleaning the polishing head 1 drops onto the upper surface of the wafer W on the carrier stage 45 . FIG. 15 is a view of the transport device 44 viewed from the direction indicated by the arrow A shown in FIG. As shown in FIG. 15, the liquid Q exists on the upper surface of the wafer W. As shown in FIG. Therefore, as shown in FIG. 16 , the tilting device 55 tilts the carrier stage 45 and the wafer W together before the wafer W is held by the polishing head 1 . The liquid Q spills off the top surface of the tilted wafer W, thereby removing the liquid Q from the top surface of the wafer W. FIG.

After the liquid Q is removed from the upper surface of the wafer W, the tilting device 55 returns the wafer W to the horizontal position again. After that, the wafer W is held by the polishing head 1 . The polishing head 1 carries the wafer W to a polishing position P1 (see FIG. 3) above the polishing pad 2, and presses the lower surface of the wafer W against the polishing surface 2a of the polishing pad 2 with the elastic film . The elastic film 34 of the polishing head 1 brings the lower surface of the wafer W into sliding contact with the polishing surface 2a in the presence of slurry on the polishing surface 2a, and polishes the wafer W by the chemical action of the slurry and the mechanical action of abrasive grains contained in the slurry. do.

According to this embodiment, the wafer W is held by the polishing head 1 after the liquid Q is removed from the upper surface of the wafer W. As shown in FIG. Therefore, the liquid Q does not exist between the upper surface of the wafer W and the elastic film 34 of the polishing head 1 , the elastic film 34 can apply the intended force to the wafer W, and the polishing head 1 moves the wafer W to the desired level. film thickness profile can be achieved.

17 and 18 are schematic diagrams illustrating still another embodiment of the method for removing liquid from the upper surface of the wafer W. FIG. The details of this embodiment that are not specifically described are the same as those of the embodiment shown in FIG. 3, so redundant description thereof will be omitted.

As shown in FIG. 17, the wafer W on the carrier stage 45 is moved by the horizontal movement device 49 to the transfer position P2. The polishing head 1 is cleaned with liquid supplied from the cleaning nozzle 53 . The liquid used for cleaning the polishing head 1 drops onto the upper surface of the wafer W on the carrier stage 45 .

As shown in FIG. 18, before the wafer W is held by the polishing head 1, the horizontal movement device 49 horizontally rocks the carrier stage 45 and the wafer W. As shown in FIG. As the wafer W is shaken, the liquid Q spills from the upper surface of the wafer W, thereby removing the liquid Q from the upper surface of the wafer W. As shown in FIG. In one embodiment, the horizontal movement device 49 may rock the carrier stage 45 and the wafer W in the horizontal direction while the carrier stage 45 and the wafer W are tilted by the tilting device 55 . Additionally, in one embodiment, the tilting device 55 may not be provided.

After the liquid Q has been removed from the top surface of the wafer W, the wafer W is held by the polishing head 1 . The polishing head 1 carries the wafer W to a polishing position P1 (see FIG. 3) above the polishing pad 2, and presses the lower surface of the wafer W against the polishing surface 2a of the polishing pad 2 with the elastic film . The elastic film 34 of the polishing head 1 brings the lower surface of the wafer W into sliding contact with the polishing surface 2a in the presence of slurry on the polishing surface 2a, and polishes the wafer W by the chemical action of the slurry and the mechanical action of abrasive grains contained in the slurry. do.

According to this embodiment, the wafer W is held by the polishing head 1 after the liquid Q is removed from the upper surface of the wafer W. As shown in FIG. Therefore, the liquid Q does not exist between the upper surface of the wafer W and the elastic film 34 of the polishing head 1 , the elastic film 34 can apply the intended force to the wafer W, and the polishing head 1 moves the wafer W to the desired level. film thickness profile can be achieved.

19A and 19B are schematic diagrams illustrating still another embodiment of a method for removing liquid from the top surface of the wafer W. FIG. The details of this embodiment that are not specifically described are the same as those of the embodiment shown in FIG. 3, so redundant description thereof will be omitted.

As shown in FIG. 19, the polishing apparatus of this embodiment includes a gas jet nozzle 57 arranged at the delivery position P2. The gas jet nozzle 57 is inclined with respect to the horizontal direction, and is arranged so as to face the top of the transfer stage 45 at the transfer position P2, that is, face the upper surface of the wafer W on the transfer stage 45 . The gas jet nozzle 57 is connected to a compressed gas supply source (not shown). Although a plurality of gas jet nozzles 57 are provided in this embodiment, only one gas jet nozzle 57 may be provided in one embodiment.

The wafer W on the carrier stage 45 is moved to the delivery position P2 by the horizontal movement device 49 . The polishing head 1 is cleaned with liquid supplied from the cleaning nozzle 53 . The liquid used for cleaning the polishing head 1 drops onto the upper surface of the wafer W on the carrier stage 45 . As shown in FIG. 20, before the wafer W is held by the polishing head 1, the gas jet nozzle 57 sends a gas jet to the upper surface of the wafer W to remove the liquid Q from the upper surface of the wafer W. As shown in FIG.

After the liquid Q has been removed from the top surface of the wafer W, the wafer W is held by the polishing head 1 . The polishing head 1 carries the wafer W to a polishing position P1 (see FIG. 3) above the polishing pad 2, and presses the lower surface of the wafer W against the polishing surface 2a of the polishing pad 2 with the elastic film . The elastic film 34 of the polishing head 1 brings the lower surface of the wafer W into sliding contact with the polishing surface 2a in the presence of slurry on the polishing surface 2a, and polishes the wafer W by the chemical action of the slurry and the mechanical action of abrasive grains contained in the slurry. do.

According to this embodiment, the wafer W is held by the polishing head 1 after the liquid Q is removed from the upper surface of the wafer W. As shown in FIG. Therefore, the liquid Q does not exist between the upper surface of the wafer W and the elastic film 34 of the polishing head 1 , the elastic film 34 can apply the intended force to the wafer W, and the polishing head 1 moves the wafer W to the desired level. film thickness profile can be achieved.

FIG. 21 is a cross-sectional view illustrating one embodiment of an elastic membrane 34 capable of removing liquid from the top surface of wafer W. As shown in FIG. As shown in FIG. 21, the elastic membrane 34 has a liquid channel 60 formed therein. More specifically, the contact portion 35 of the elastic membrane 34 has a plurality of openings 61 opened at the contact surface 35 a and lateral holes 62 connected to the plurality of openings 61 . The contact surface 35a of the elastic film 34 is one surface of the elastic film 34 that contacts the upper surface of the wafer W. As shown in FIG. The opening 61 is provided below the central pressure chamber 25A and is not provided below the other pressure chambers 25B to 25D. In one embodiment, openings 61 may also be provided below pressure chambers 25B-25D. The lateral hole 62 extends inside the contact portion 35 , and the outer end of the lateral hole 62 opens at the outer surface 34 a of the elastic membrane 34 . Therefore, the contact surface 35a and the outer surface 34a of the elastic membrane 34 are in communication with each other through the liquid channel 60 composed of the opening 61 and the lateral hole 62. As shown in FIG.

As shown in FIG. 22, compressed gas is supplied into the pressure chambers 25A to 25D to inflate the elastic film 34, and the contact surface 35a of the elastic film 34 is pressed against the upper surface of the wafer W. As shown in FIG. The liquid Q (see FIG. 21) existing on the upper surface of the wafer W flows into the liquid channel 60 through the opening 61 and flows out of the elastic membrane 34 through the liquid channel 60 . As a result, liquid Q is removed from the top surface of wafer W. FIG.

After the liquid Q has been removed from the top surface of the wafer W, the wafer W is held by the polishing head 1 . The polishing head 1 carries the wafer W to a polishing position P1 (see FIG. 3) above the polishing pad 2, and presses the lower surface of the wafer W against the polishing surface 2a of the polishing pad 2 with the elastic film . The elastic film 34 of the polishing head 1 brings the lower surface of the wafer W into sliding contact with the polishing surface 2a in the presence of slurry on the polishing surface 2a, and polishes the wafer W by the chemical action of the slurry and the mechanical action of abrasive grains contained in the slurry. do.

According to this embodiment, the polishing head 1 can hold the wafer W in a state in which substantially no liquid Q exists between the elastic film 34 and the upper surface of the wafer W. FIG. As a result, the elastic membrane 34 forming the pressure chambers 25A, 25B, 25C, 25D can apply the intended force to the wafer W, and the polishing head 1 can achieve the desired film thickness profile of the wafer W. .

FIG. 23 is a cross-sectional view showing another embodiment of an elastic membrane 34 capable of removing liquid from the top surface of the wafer W. As shown in FIG. The details of this embodiment that are not particularly described are the same as those of the embodiment shown in FIGS. 21 and 22, so redundant description thereof will be omitted. As shown in FIG. 23, the liquid channel 60 communicates with a suction line 70 connected to the elastic membrane 34 . More specifically, lateral hole 62 is connected to both opening 61 and suction line 70 . One end of the horizontal hole 62 is connected to the opening 61, and the other end of the horizontal hole 62 is open on the upper surface 35b of the connecting portion 35 (the surface of the connecting portion 35 opposite to the contact surface 35a).

The suction line 70 extends through the carrier 31 and the end of the suction line 70 is connected to the upper surface 35 b of the contact portion 35 . The suction line 70 communicates with the liquid flow path 60, but does not communicate with the pressure chamber 25A. Therefore, the suction line 70 can create a vacuum in the liquid flow path 60 without creating a vacuum in the pressure chamber 25A.

As shown in FIG. 24, compressed gas is supplied into the pressure chambers 25A to 25D to inflate the elastic film 34, and while the contact surface 35a of the elastic film 34 is pressed against the upper surface of the wafer W, the liquid flow path 60 is drawn by the suction line 70. As shown in FIG. Create a vacuum within. The liquid Q (see FIG. 23) existing on the upper surface of the wafer W is sucked into the liquid flow path 60 through the opening 61 and removed from the upper surface of the wafer W. As shown in FIG.

FIG. 25 is a cross-sectional view showing yet another embodiment of an elastic membrane 34 capable of removing liquid from the top surface of wafer W. As shown in FIG. The details of this embodiment that are not particularly described are the same as those of the embodiment shown in FIGS. 21 and 22, so redundant description thereof will be omitted. As shown in FIG. 25, the liquid flow path is composed of a plurality of grooves 75 formed in the contact surface 35a.

26 is a bottom view of the elastic membrane 34 shown in FIG. 25. FIG. As shown in FIG. 26, the plurality of grooves 75 are annular grooves arranged concentrically. However, the shape of the groove 75 is not limited to this embodiment. For example, grooves 75 may be straight grooves arranged parallel to each other.

As shown in FIG. 27, compressed gas is supplied into the pressure chambers 25A to 25D to inflate the elastic film 34, and the contact surface 35a of the elastic film 34 is pressed against the upper surface of the wafer W. As shown in FIG. The liquid Q (see FIG. 25) existing on the upper surface of the wafer W flows into the grooves 75 as liquid flow paths. As a result, liquid Q is removed from the top surface of wafer W. FIG.

In the present embodiment, in order to prevent the liquid Q that has flowed into the groove 75 once from flowing out of the groove 75, the width of the groove 75 inside the contact portion 35 is set larger than the width of the groove 75 on the contact surface 35a. big. That is, the entrance of the groove 75 is narrow and the inside of the groove 75 is wide. The groove 75 having such a cross-sectional shape easily retains the liquid Q therein. The grooves 75 may be evenly distributed over the contact surface 35a of the elastic membrane 34 in order to remove the liquid irregularly present on the top surface of the wafer W. As shown in FIG.

The elastic membrane 34 shown in FIGS. 21 to 27 can be produced using a 3D printer (three-dimensional printer).

The embodiments described above can be combined as appropriate. For example, the embodiments shown in FIGS. 4-6 may be applied to the embodiments shown in FIGS. 14-16, or the embodiments shown in FIGS. 17 and 18, or the embodiments shown in FIGS. 19 and 20. good.

Although the polishing head 1 according to each embodiment described above has four pressure chambers 25A, 25B, 25C, and 25D, the present invention is not limited to these embodiments. The above embodiments of excluding liquid from the top surface of the wafer are applicable to polishing heads with less than four pressure chambers, as well as polishing heads with more than four pressure chambers.

The above-described embodiments are described for the purpose of enabling a person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiments can be 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 its broadest scope in accordance with the technical spirit defined by the claims.

1 polishing head 2 polishing pad 2a polishing surface 3 polishing table 5 slurry supply nozzle 6 table motor 11 polishing head shaft 15 head arms 25A, 25B, 25C, 25D, 25E pressure chamber 31 carrier 32 retainer ring 34 elastic film 35 contact portion 35a contact Surfaces 36a, 36b, 36c Inner wall portion 36d Outer wall portion 37 Membrane (rolling diaphragm)
40 Rotary joint 41 Air cylinder 42 Weight 44 Transfer device 45 Transfer stage 47 Lifting device 49 Horizontal movement device 53 Cleaning nozzle 55 Tilting device 57 Gas jet nozzle 60 Liquid channel 61 Opening 62 Horizontal hole 70 Suction line 75 Grooves F1, F2, F3, F4, F5 gas transfer lines R1, R2, R3, R4, R5 pressure regulators L1, L2, L3, L4, L5 vacuum lines V1, V2, V3, V4, V5 vacuum valves

Claims (4)

A method of polishing a wafer using a polishing head, comprising:
removing liquid from the top surface of the wafer on a carrier, and then
holding the wafer on the transport device with the polishing head;
A method of polishing the lower surface of the wafer by pressing the lower surface of the wafer against the polishing surface with the polishing head. 2. The method of claim 1, wherein removing liquid from the top surface of the wafer on the carrier comprises tilting the wafer with the carrier to remove liquid from the top surface of the wafer. 2. The method of claim 1, wherein removing liquid from the top surface of the wafer on the carrier comprises shaking the wafer with the carrier to remove liquid from the top surface of the wafer. 2. The step of removing liquid from the top surface of the wafer on the carrier comprises removing liquid from the top surface of the wafer by directing a jet of gas onto the top surface of the wafer on the carrier. The method described in .

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