Polishing device and polishing method

Abstract

To provide a polishing device which can accurately control a film thickness profile of a substrate with a simple configuration.SOLUTION: A polishing device includes a stage for holding a substrate and which has a non-rotation structure, a plurality of press actuators, a pad holding body, and a polish pad rotation mechanism.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a polishing apparatus and a polishing method.

Background Art

[0002] In recent years, the required accuracy for each process in the manufacture of semiconductor devices has already reached the order of several nanometers, and chemical mechanical polishing (CMP) is no exception. Further, with the high integration of semiconductor integrated circuits, miniaturization and multilayerization are accelerating more and more.

[0003] Therefore, in order to achieve these miniaturization and multilayerization, even in CMP, it is required as an issue to keep the variation in film thickness after CMP within the order of several nanometers over the entire surface of the wafer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Patent Document 1 discloses a face-up type polishing apparatus configured to locally polish a wafer to control the film thickness profile of the wafer. The polishing apparatus in Patent Document 1 is configured to polish the wafer by pressing a polishing pad against the wafer while rotating a table holding the wafer by a drive mechanism.

[0006] In order to accurately control the film thickness profile of the wafer, it is necessary to control the pressing force of the polishing pad for each small region on the wafer, but it is necessary to use a polishing pad with a small diameter, and in this case, it takes a long time to polish the wafer.

[0007] Patent Document 2 discloses a face-up type polishing apparatus having a plurality of piezoelectric elements disposed inside a polishing head that holds a wafer. Also in such a polishing apparatus, as in the polishing apparatus in Patent Document 1, it is necessary to polish the wafer while rotating the polishing head that holds the wafer.

[0008] In the configuration of Patent Document 2, it is necessary to extend a plurality of power lines to which a plurality of piezoelectric elements are connected to the outside of the polishing head through a rotary connector. However, if all of the plurality of power lines are connected to the rotary connector, the polishing apparatus becomes complicated.

[0009] Therefore, an object of the present invention is to provide a polishing apparatus and a polishing method that have a simple structure and can accurately control the film thickness profile of a substrate.

Means for Solving the Problems

[0010] In one aspect, a polishing apparatus is provided. The polishing apparatus includes a stage that holds the substrate so that the surface to be polished of the substrate faces upward and has a non-rotating structure, a plurality of pressing actuators disposed inside the stage and independently pressing specific portions of the substrate, a pad holder that holds a polishing pad and presses the polishing pad against the surface to be polished, and a polishing pad rotation mechanism configured to rotate the polishing pad about itself.

[0011] In one aspect, the polishing apparatus includes a polishing pad moving mechanism configured to move the polishing pad. In one aspect, the polishing pad moving mechanism is configured to move the polishing pad along a spiral polishing track on the surface to be polished. In one aspect, the polishing track has a first track extending from a peripheral portion of the substrate toward a central portion of the substrate and a second track extending from the central portion of the substrate toward the peripheral portion of the substrate and not overlapping the first track.

[0012] In one aspect, the polishing apparatus includes a film thickness measuring device that detects a film thickness signal corresponding to the film thickness of the substrate. In one aspect, the polishing apparatus includes a plurality of film thickness measuring devices including the film thickness measuring device, which are arranged side by side in a straight line, and the plurality of film thickness measuring devices are configured to detect a film thickness signal corresponding to the film thickness of the substrate along a linear measurement locus on the surface to be polished. In one aspect, the polishing apparatus includes a polishing liquid supply device including a center supply nozzle that supplies polishing liquid from the central portion of the polishing pad.

[0013] In one aspect, the polishing apparatus includes a polishing liquid supply device including a peripheral supply nozzle arranged around the polishing pad, and the peripheral supply nozzle is configured to supply polishing liquid to the upstream side of the polishing pad in the traveling direction of the polishing pad. In one aspect, the polishing apparatus includes a suction device that vacuums the substrate arranged on the stage, and the suction device includes a vacuum line arranged inside the stage. In one aspect, at least one of the plurality of pressing actuators is an air cylinder having a hollow piston rod, and the vacuum line is connected to the piston rod.

[0014] In one aspect, a polishing method is provided. The polishing method includes holding the substrate by a stage that houses a plurality of pressing actuators such that the surface to be polished of the substrate faces upward, and pressing the polishing pad held by the pad holder against the surface to be polished while rotating the polishing pad about itself with the pressing pressure of a specific pressing actuator among the plurality of pressing actuators being different from the pressing pressures of the other pressing actuators, thereby polishing the substrate in a non-rotating state.

[0015] In one aspect, during polishing of the substrate, the polishing pad is moved along a spiral polishing locus on the surface to be polished. In one aspect, before polishing the substrate, the film thickness distribution of the substrate is measured, and based on the film thickness distribution, the pressing pressure by the plurality of pressing actuators is determined. In one aspect, during polishing of the substrate, polishing liquid is supplied from a center supply nozzle disposed at a central portion of the polishing pad. In one aspect, during polishing of the substrate, polishing liquid is supplied from a peripheral supply nozzle disposed around the polishing pad to an upstream side of the polishing pad in a traveling direction of the polishing pad.

Advantages of the Invention

[0016] The polishing apparatus can polish the surface to be polished of the wafer in a state where an uneven shape corresponding to a specific portion of the wafer is formed on the mounting surface of the stage by a plurality of pressing actuators. Since the stage has a non-rotating structure, simplification of the control lines of the pressing actuators can be achieved. Therefore, the polishing apparatus can accurately control the film thickness profile of the substrate with a simple structure.

Brief Description of the Drawings

[0017]

Figure 1

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Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are denoted by the same reference numerals and redundant descriptions are omitted. In the plurality of embodiments described below, the configuration of one embodiment that is not particularly described is the same as that of other embodiments, so the redundant description thereof is omitted.

[0019] Fig. 1 is a perspective view showing an embodiment of a polishing device. Fig. 2 is a cross-sectional view showing the polishing device shown in Fig. 1. In the embodiment shown in Figs. 1 and 2, the polishing device is a polishing device that polishes the wafer W (an example of a substrate) with the polished surface Wa of the wafer W as the object to be polished facing upward. Such a polishing device is called a face-up type polishing device.

[0020] The polishing apparatus includes a stage 1 having a non-rotating structure that holds the wafer W such that the polished surface Wa of the wafer W faces upward, a plurality of pressing actuators 10 disposed inside the stage 1 and independently pressing specific portions of the wafer W, a pad holder 20 that holds a polishing pad 21 in sliding contact with the polished surface Wa, a film thickness measuring device 90 that detects a film thickness signal corresponding to the film thickness of the wafer W, and a control device 50 that controls the operation of the components of the polishing apparatus.

[0021] While the stage 1 is configured to hold the wafer W, it is a non-rotating type substrate holding device that does not rotate the held wafer W. More specifically, the non-rotating stage 1 is not connected to a rotating device such as a motor. When the stage 1 holds the wafer W, the center CP of the wafer W is located on the central axis CL1 of the stage 1.

[0022] The polishing pad 21 is composed of, for example, a member such as a foamed polyurethane-based pad or a sponge, and has a size (diameter) smaller than the size (diameter) of the wafer W. The polishing pad 21 has a polishing surface 21a that is pressed against the polished surface Wa. The polishing surface 21a faces downward and faces the polished surface Wa.

[0023] The pad holder 20 is configured to press the polishing pad 21 against the polished surface Wa. More specifically, the pad holder 20 has an air bag 22 (see FIG. 2) disposed inside thereof, and the polishing pad 21 is disposed below the air bag 22.

[0024] Therefore, by supplying compressed air from a compressed air source (not shown) to the air bag 22, the air bag 22 expands and pushes down the polishing pad 21 toward the polished surface Wa. The polishing pad 21 polishes the polished surface Wa by pressing its polishing surface 21a against the polished surface Wa.

[0025] The polishing apparatus includes a polishing pad moving mechanism 30 configured to move the polishing pad 21. The polishing pad moving mechanism 30 includes a rotating shaft 31 to which the pad holder 20 is connected, a polishing pad arm 32 to which the rotating shaft 31 is connected, a turning shaft 33 to which the polishing pad arm 32 is connected, and a polishing pad drive source 34 connected to the turning shaft 33.

[0026] The rotating shaft 31 fixes the pad holder 20 to its lower end. As shown in FIG. 2, the rotating shaft 31 is connected to the rotating motor 40 through pulleys 41, 42 and a belt 43 wound around the pulleys 41, 42.

[0027] Therefore, when the rotating motor 40 is driven, it rotates the rotating shaft 31 through the pulleys 41, 42 and the belt 43. The pad holder 20 fixed to the rotating shaft 31 and the polishing pad 21 held by the pad holder 20 rotate about the central axis CL2 of the rotating shaft 31.

[0028] These rotating motor 40, pulleys 41, 42, and belt 43 constitute a polishing pad rotating mechanism 150 that rotates the polishing pad 21 together with the pad holder 20 about the central axis CL2.

[0029] The polishing pad drive source 34 is configured to move the polishing pad arm 32 in the X-axis direction and the Y-axis direction through the turning shaft 33. The X-axis direction and the Y-axis direction extend parallel to the polished surface Wa of the wafer W held on the stage 1 and are perpendicular to each other.

[0030] When the polishing pad drive source 34 is driven, it moves the pad holder 20 and the polishing pad 21 in a direction parallel to the polished surface Wa (i.e., the X-axis direction and the Y-axis direction) through the turning shaft 33 and the polishing pad arm 32.

[0031] Although not shown, as an example of the polishing pad drive source 34, a combination of an X-axis actuator (for example, a combination of a ball screw extending in the X-axis direction and a servo motor) and a Y-axis actuator (for example, a combination of a ball screw extending in the X-axis direction and a servo motor) can be mentioned.

[0032] The control device 50 includes a storage device 50a in which a program is stored, and an arithmetic device 50b that executes arithmetic operations according to instructions included in the program. The storage device 50a includes a main storage device such as a RAM, and an auxiliary storage device such as a hard disk drive (HDD) and a solid state drive (SSD). Examples of the arithmetic device 50b include a CPU (central processing unit) and a GPU (graphics processing unit).

[0033] FIGS. 3(a) and 3(b) are diagrams showing a polishing pad moving along an example of a polishing track. In the embodiment shown in FIGS. 3(a) and 3(b), the polishing pad 21 moves on the surface Wa to be polished along a spiral polishing track (see dotted arrow) on the surface Wa to be polished, and polishes the surface Wa to be polished. The control device 50 is configured to move the polishing pad 21 along a predetermined polishing track (for example, the polishing track according to the embodiment shown in FIGS. 3(a) and 3(b)) stored in the storage device 50a by operating the polishing pad drive source 34.

[0034] As shown in FIGS. 3(a) and 3(b), the polishing track has a first track C1 extending from the peripheral portion PP of the wafer W toward the center CP of the wafer W, and a second track C2 extending from the center CP of the wafer W toward the peripheral portion PP of the wafer W. Both the first track C1 and the second track C2 are polishing tracks that pass around the center CP without passing through the center CP of the wafer W.

[0035] The first track C1 and the second track C2 are formed so as not to overlap each other. Therefore, the polishing pad 21 is configured to draw different tracks and uniformly polish the entire surface Wa to be polished.

[0036] The polishing pad moving mechanism 30 is configured to continuously move the polishing pad 21 along the first trajectory C1 and the second trajectory C2. Therefore, the polishing pad 21 moves along the first trajectory C1 from the peripheral portion PP of the wafer W toward the center CP of the wafer W by the operation of the polishing pad driving source 34, and then moves along the second trajectory C2 from the center CP of the wafer W toward the peripheral portion PP of the wafer W.

[0037] In the embodiment shown in FIG. 3(a), the polishing pad 21 moves along a spiral polishing trajectory (i.e., the first trajectory C1 and the second trajectory C2) that spirals in one direction (the first rotation direction). In the embodiment shown in FIG. 3(b), the polishing pad 21 moves along a spiral polishing trajectory (i.e., the first trajectory C1 and the second trajectory C2) that spirals in the same rotation direction as the first rotation direction.

[0038] FIGS. 4(a) and 4(b) are diagrams showing a polishing pad that moves along another example of a polishing trajectory. Also in the embodiments shown in FIGS. 4(a) and 4(b), the polishing pad 21 oscillates on the surface Wa to be polished along a spiral polishing trajectory. The storage device 50a stores the polishing trajectory according to the embodiments shown in FIGS. 4(a) and 4(b).

[0039] The polishing trajectory has a first trajectory C1' extending from the peripheral portion PP of the wafer W toward the center CP of the wafer W and a second trajectory C2' extending from the center CP of the wafer W toward the peripheral portion PP of the wafer W. The first trajectory C1' and the second trajectory C2' are polishing trajectories that pass through the center CP of the wafer W.

[0040] Also in FIGS. 4(a) and 4(b), the first trajectory C1' and the second trajectory C2' are formed so as not to overlap each other. Therefore, the polishing pad 21 is configured to polish the entire surface Wa to be polished uniformly by drawing different trajectories.

[0041] In the embodiment shown in FIG. 4(a), the polishing pad 21 moves along a spiral first trajectory C1' that spirals in the first rotation direction. After reaching the center CP of the wafer W, it moves along a spiral second trajectory C2' that spirals in the second rotation direction opposite to the first rotation direction.

[0042] In the embodiment shown in FIG. 4(b), the polishing pad 21 moves along a spiral first trajectory C1' that spirals in the second rotation direction. After reaching the center CP of the wafer W, it moves along a spiral second trajectory C2' that spirals in the first rotation direction.

[0043] As described above, the polishing pad 21 has a specific size. Therefore, the polishing pad 21 passing over the wafer W may not overlap uniformly. That is, if the speed at which the polishing pad 21 moves is constant, the time that the polishing pad 21 stays at a specific point (any one point) on the wafer W during one movement from the peripheral portion PP of the wafer W to the center CP of the wafer W and then from the center CP to the peripheral portion PP is not necessarily uniform on the wafer W.

[0044] Therefore, the control device 50 may control the polishing amount of the wafer W by changing the moving speed of the polishing pad 21 moving along the polishing trajectory based on the polishing conditions of the wafer W to be polished. Alternatively, the control device 50 may control the polishing amount of the wafer W by changing the pressing force applied to the wafer W by the polishing pad 21.

[0045] In this way, the control device 50 can uniformly polish the entire surface of the wafer W by operating the polishing pad drive source 34 to move the polishing pad 21 along the spiral polishing trajectory.

[0046] In this embodiment, the stage 1 is configured to hold the wafer W without rotating the wafer W. By moving the polishing pad 21 along the spiral polishing trajectory, an effect equivalent to that when the wafer W is polished in a rotated state can be achieved.

[0047] Hereinafter, in this specification, the region on the surface to be polished Wa is divided into a peripheral side region PA including the peripheral portion PP of the wafer W and a central side region CA including the center CP of the wafer W (see FIGS. 3(a) and 3(b), FIGS. 4(a) and 4(b)). When the polishing pad 21 is moved along the polishing locus while rotating at a constant rotational speed, there may be a difference between the polishing amount in the peripheral side region PA and the polishing amount in the central side region CA. For example, in the central side region CA, over-polishing may occur.

[0048] Therefore, in order to eliminate such a difference in polishing amount, the polishing pad 21 may move the peripheral side region PA and the central side region CA at different rotational speeds. For example, the rotational speed of the polishing pad 21 in the central side region CA may be made slower than the rotational speed of the polishing pad 21 in the peripheral side region PA. In one embodiment, the polishing pad 21 may move the peripheral side region PA and the central side region CA in a non-rotating state.

[0049] In one embodiment, the moving speed of the polishing pad 21 may be changed. For example, the moving speed of the polishing pad 21 in the peripheral side region PA may be made slower than the moving speed of the polishing pad 21 in the central side region CA.

[0050] FIG. 5 is a diagram showing a plurality of pressing actuators arranged in a grid pattern. In FIG. 5, illustration of the stage 1 that houses the plurality of pressing actuators 10 is omitted. As shown in FIG. 5, the plurality of pressing actuators 10 are arranged in a grid pattern so as to fill the wafer W, and are spread along the radial direction and the circumferential direction of the wafer W.

[0051] Each of the plurality of pressing actuators 10 has the same structure. The pressing actuator 10 is configured to be stretchable. The control device 50 is configured to operate the pressing actuator 10 to control the polishing amount at a specific part (or other parts excluding the specific part) of the wafer W. Examples of the pressing actuator 10 include a piezoelectric element and an air cylinder.

[0052] The pressing actuator 10 has a pressing surface 10a that can contact the back surface Wb on the side opposite to the surface Wa to be polished (see FIGS. 2 and 5). The plurality of pressing surfaces 10a constitute the mounting surface of the stage 1. Therefore, when the wafer W is placed on the mounting surface of the stage 1, the pressing surface 10a of the pressing actuator 10 faces the back surface Wb of the wafer W. The size of the pressing surface 10a is smaller than that of the polishing pad 21.

[0053] The plurality of pressing actuators 10 are configured to form an uneven shape corresponding to a specific part of the wafer W on the mounting surface of the stage 1 by their operation. When polishing the wafer W, the wafer W is placed on the mounting surface formed by the plurality of pressing surfaces 10a.

[0054] When the pressing actuator 10 corresponding to a specific part of the wafer W is operated, the pressing surface 10a pushes up the specific part of the wafer W. The pushed-up specific part of the wafer W protrudes with respect to other parts. In this state, when the polishing pad 21 is pressed against the surface Wa to be polished and the wafer W is polished, the specific part of the wafer W is polished more actively compared to other parts. More specifically, the specific part of the wafer W that protrudes more than other parts is polished by the polishing pad 21 with a higher pressure than other parts. Therefore, the polishing amount of the specific part becomes larger than the polishing amount of other parts.

[0055] When reducing the polishing amount of a specific part of the wafer W, other parts excluding the specific part are made to protrude by the pressing actuator 10. Or, the pressing actuator 10 corresponding to the specific part of the wafer W is contracted. In this state, when the wafer W is polished, the specific part of the wafer W is polished by the polishing pad 21 with a lower pressure than other parts.

[0056] In one embodiment, as a method of avoiding polishing of a specific part of the wafer W, the pressure of the compressed air supplied to the air bag 22 of the polishing pad 21 may be set to 0, or the polishing pad 21 may be lifted from the wafer W.

[0057] Thus, by operating the pressing actuator 10 (and the polishing pad 21) corresponding to a specific part (and / or other parts) of the wafer W, the polishing amount at the specific part (and / or other parts) of the wafer W can be controlled.

[0058] FIG. 6 is a diagram showing a stage on which a pressing actuator is disposed. As shown in FIG. 6, the stage 1 includes a base 1a on which a plurality of pressing actuators 10 are placed, and a plurality of split rings 1b disposed on the outer side in the radial direction of the base 1a. The base 1a has a flat plate shape extending in parallel with the wafer W held on the stage 1. The plurality of pressing actuators 10 are spread out on the base 1a.

[0059] The polishing apparatus includes control lines 60 connected to each of the plurality of pressing actuators 10, and the plurality of pressing actuators 10 are electrically connected to the control device 50 through the plurality of control lines 60 extending inside the base 1a (see FIGS. 2 and 6). The number of the control lines 60 corresponds to the number of the pressing actuators 10. The control device 50 is configured to control the operation of each pressing actuator 10 through each control line 60.

[0060] In the present embodiment, since the stage 1 has a non-rotating structure, it is not necessary to connect the control lines 60 to a rotary connector. Therefore, simplification of the control lines 60 can be achieved. Further, since it is not necessary to rotate the control lines 60 together with the stage 1, disconnection of the control lines 60 caused by entanglement of the control lines 60 can be prevented.

[0061] The plurality of split rings 1b are arranged so as to surround the wafer W disposed on the mounting surface of the stage 1. The plurality of split rings 1b have the same structure. In the present embodiment, the stage 1 includes four split rings 1b (see FIG. 1), and these split rings 1b have an annular shape surrounding the wafer W.

[0062] The plurality of split rings 1b are configured to be close to and separated from each other. More specifically, the polishing apparatus includes a moving actuator 70 that moves each split ring 1b in the horizontal direction. Examples of the moving actuator 70 include an air cylinder and a combination of a ball screw and a servo motor.

[0063] The moving actuator 70 is electrically connected to the control device 50. The control device 50 operates the moving actuator 70 to move the plurality of split rings 1b close to and separated from each other. When the wafer W is transported to the stage 1, the control device 50 operates the moving actuator 70 to separate the plurality of split rings 1b from each other. In this state, the wafer W is placed on the placement surface of the stage 1.

[0064] Thereafter, the control device 50 operates the moving actuator 70 to bring the plurality of split rings 1b close to each other. The plurality of split rings 1b that are close to each other hold the wafer W. The plurality of split rings 1b prevent the wafer W from tilting during polishing of the wafer W. When the wafer W is held, the polished surface Wa of the wafer W is arranged on the same plane as the upper surfaces of the plurality of split rings 1b.

[0065] As shown in FIG. 6, the polishing apparatus includes a suction device 80 that vacuums the wafer W disposed on the stage 1. The suction device 80 includes a vacuum line 81 attached to the stage 1 and a vacuum source 82 that suctions the wafer W through the vacuum line 81.

[0066] The vacuum line 81 is disposed inside the stage 1. More specifically, the vacuum line 81 penetrates the base 1a and is disposed at the central portion of the stage 1. The vacuum line 81 extends along the axis CL1 of the stage 1 and has a suction port 81a formed at its tip. The suction port 81a opens upward and faces the back surface Wb of the wafer W.

[0067] The suction port 81a has a flange portion (flange shape) that spreads outward. In one embodiment, the suction port 81a having a flange shape is made of an elastic body such as rubber so that it can surely adsorb the back surface Wb of the wafer W.

[0068] The plurality of pressing actuators 10 are arranged around the vacuum line 81. The suction device 80 includes a fixing member 83 to which the vacuum line 81 is attached. The fixing member 83 is configured to fix the relative positions of the vacuum line 81 and the pressing actuators 10 arranged around the vacuum line 81. The fixing member 83 to which the vacuum line 81 is attached is attached to the pressing actuators 10 around the vacuum line 81.

[0069] The vacuum source 82 is electrically connected to the control device 50, and the control device 50 is configured to control the operation of the vacuum source 82. The vacuum source 82 forms a vacuum on the back surface Wb side of the wafer W through the vacuum line 81 by its operation. In this way, the suction device 80 vacuum-sucks the wafer W through the suction port 81a of the vacuum line 81 and adsorbs and holds the wafer W.

[0070] The polishing apparatus includes a film thickness measuring device 90 that detects a film thickness signal corresponding to the film thickness of the wafer W (more specifically, the film formed on the polished surface Wa of the wafer W) (see FIGS. 1 and 2). Examples of the film thickness measuring device 90 include an optical sensor and an eddy current sensor.

[0071] The polishing apparatus includes a film thickness measuring device moving mechanism 100 that moves the film thickness measuring device 90. The film thickness measuring device moving mechanism 100 includes a measuring shaft 101 to which the film thickness measuring device 90 is connected, a measuring arm 102 to which the measuring shaft 101 is connected, a turning shaft 103 to which the measuring arm 102 is connected, and a film thickness measuring device drive source 104 connected to the turning shaft 103.

[0072] The film thickness measuring device drive source 104 is configured to move the measurement arm 102 in the X-axis direction and the Y-axis direction through the rotation axis 103. The film thickness measuring device drive source 104 may have the same structure as the polishing pad drive source 34 described above, or may have a different structure.

[0073] FIG. 7 is a diagram showing a film thickness measuring device that moves along a spiral measurement locus. In FIG. 7, only the film thickness measuring device 90 and the wafer W are drawn for easy viewing of the drawing. As shown in FIG. 7, the film thickness measuring device 90 is configured to detect a film thickness signal along a spiral measurement locus on the polished surface Wa of the wafer W.

[0074] The film thickness measuring device drive source 104 is electrically connected to the control device 50. Therefore, the control device 50 is configured to operate the film thickness measuring device drive source 104 to move the film thickness measuring device 90 along the measurement locus on the polished surface Wa. The film thickness measuring device 90 moves from the peripheral portion PP of the wafer W toward the center CP of the wafer W along the measurement locus, and acquires the film thickness signal of the entire polished surface Wa of the wafer W.

[0075] The film thickness measuring device 90 is electrically connected to the control device 50. Therefore, the control device 50 measures the film thickness of the polished surface Wa based on the film thickness signal detected by the film thickness measuring device 90, and creates a film thickness profile (film thickness distribution data) of the wafer W.

[0076] In the present embodiment, the film thickness measuring device 90 is configured to detect the film thickness signal of the entire polished surface Wa by moving along a spiral measurement locus. Therefore, the control device 50 can acquire the accurate film thickness distribution of the polished surface Wa.

[0077] FIG. 8 is a diagram showing a plurality of film thickness measuring devices arranged side by side in a straight line. As shown in FIG. 8, the polishing apparatus may include a plurality of film thickness measuring devices 90. These plurality of film thickness measuring devices 90 are arranged side by side in a straight line in a direction parallel to the polished surface Wa, and are attached to the measurement arm 102.

[0078] In the embodiment shown in FIG. 8, the plurality of film thickness measuring devices 90 are configured to detect the film thickness signal of the wafer W along a linear measurement locus (see the black arrow in FIG. 8) on the surface Wa to be polished. The film thickness measuring device moving mechanism 100 linearly moves the measurement arm 102 in the radial direction of the wafer W, so that the plurality of film thickness measuring devices 90 detect the film thickness signal of the wafer W.

[0079] The film thickness measuring devices 90 arranged in a straight line have a length greater than the diameter of the wafer W. Therefore, with a simple configuration in which the measurement arm 102 is moved only once, the plurality of film thickness measuring devices 90 can detect the film thickness of the wafer W.

[0080] FIG. 9 is a diagram showing a film thickness measuring device attached to the polishing pad. As shown in FIG. 9, the film thickness measuring device 90 does not necessarily have to be attached to the measurement arm 102 via the measurement shaft 101, and may be attached to the polishing pad arm 32.

[0081] In the embodiment shown in FIG. 9, the film thickness measuring device 90 is arranged on the downstream side of the polishing pad 21 in the advancing direction of the polishing pad 21. With such an arrangement, immediately after the polishing pad 21 polishes the surface Wa to be polished of the wafer W, the film thickness measuring device 90 can detect the film thickness of the surface Wa to be polished. The control device 50 can measure the film thickness of the surface Wa to be polished in real time by acquiring the film thickness signal from the film thickness measuring device 90 during the polishing of the wafer W.

[0082] The polishing apparatus includes a polishing liquid supply device 130 that supplies a polishing liquid containing abrasive grains such as silica (SiO2) onto the surface Wa to be polished (see FIG. 1). The polishing liquid supply device 130 includes a center supply nozzle 132 and a peripheral supply nozzle 133 for supplying the polishing liquid onto the surface Wa to be polished.

[0083] During the polishing of the wafer W, the control device 50 is configured to operate the center supply nozzle 132 and the peripheral supply nozzle 133 to supply the polishing liquid onto the surface Wa to be polished. While supplying the polishing liquid onto the surface Wa to be polished, the control device 50 moves the polishing pad 21 along the polishing locus. The polishing pad 21 polishes the surface Wa to be polished in a state where the polishing liquid is present on the surface Wa to be polished.

[0084] FIG. 10 is a diagram showing the center supply nozzle and the peripheral supply nozzle. As shown in FIG. 10, the center supply nozzle 132 is configured to supply the polishing liquid from the central portion of the polishing pad 21. The peripheral supply nozzle 133 is configured to supply the polishing liquid to the periphery of the polishing pad 21.

[0085] In the embodiment shown in FIG. 1, the polishing liquid supply device 130 includes one center supply nozzle 132 and two peripheral supply nozzles 133. In the embodiment shown in FIG. 10, the polishing liquid supply device 130 includes one center supply nozzle 132 and twelve peripheral supply nozzles 133.

[0086] Thus, the number of each of the center supply nozzle 132 and the peripheral supply nozzle 133 is not particularly limited. In one embodiment, the polishing liquid supply device 130 may include a plurality of center supply nozzles 132 and one peripheral supply nozzle 133. In the present embodiment, the plurality of peripheral supply nozzles 133 are arranged at equal intervals in the circumferential direction of the polishing pad 21.

[0087] FIG. 11 is a diagram showing the center supply nozzle and the peripheral supply nozzle connected to the polishing pad arm. As shown in FIG. 11, the center supply nozzle 132 penetrates the rotating shaft 31 along the central axis CL2 and is connected to the polishing pad arm 32. The peripheral supply nozzle 133 is arranged on the outer side in the radial direction of the polishing pad 21 and is connected to the polishing pad arm 32.

[0088] FIG. 12(a) is a diagram showing a polishing liquid supply device including only a center supply nozzle, FIG. 12(b) is a diagram showing a polishing liquid supply device including only a peripheral supply nozzle, and FIG. 12(c) is a diagram showing a peripheral supply nozzle connected to a pad holder.

[0089] As shown in FIG. 12(a), the polishing liquid supply device 130 includes a center supply nozzle 132 and may not include a peripheral supply nozzle 133. As shown in FIG. 12(b), the polishing liquid supply device 130 includes a peripheral supply nozzle 133 and may not include a center supply nozzle 132. Even in this case, the peripheral supply nozzle 133 is configured to supply the polishing liquid to the upstream side of the polishing pad 21 in the traveling direction of the pad holder 20.

[0090] In the embodiment shown in FIG. 11, the peripheral supply nozzle 133 connected to the polishing pad arm 32 is configured not to rotate, but in one embodiment, the peripheral supply nozzle 133 may be configured to rotate.

[0091] For example, as shown in FIG. 12(c), the peripheral supply nozzle 133 may be connected to the pad holder 20. With such a configuration, the peripheral supply nozzle 133 can supply the polishing liquid to the periphery of the polishing pad 21 while rotating together with the pad holder 20. In one embodiment, the peripheral supply nozzle 133 may be connected to the rotation shaft 31. Also with such a configuration, the peripheral supply nozzle 133 rotates together with the rotation shaft 31.

[0092] FIG. 13 is a diagram showing a polishing flow of a wafer by a polishing apparatus. Before starting the polishing of the wafer W, the control device 50 measures the initial film thickness of the entire polished surface Wa of the wafer W and creates an initial film thickness profile (see steps S101 and S102). The created initial film thickness profile is stored in the storage device 50a.

[0093] The initial film thickness profile may be created, for example, from the film thickness signal detected by the film thickness measuring instrument 90. In this case, the wafer W is held on the stage 1 with its polished surface Wa facing upward. In this state, the film thickness measuring instrument 90 acquires the film thickness signal of the polished surface Wa along the measurement locus on the polished surface Wa. When holding the wafer W, the control device 50 operates the moving actuator 70 to open the split ring 1b of the stage 1, and when the wafer W is placed on the plurality of pressing actuators 10, closes the split ring 1b.

[0094] In one embodiment, the control device 50 may create an initial film thickness profile based on the film thickness measurement value acquired by a stand-alone type film thickness measuring device (not shown). Even in this case, the initial film thickness profile is stored in the storage device 50a.

[0095] Thereafter, the control device 50 compares the initial film thickness profile with the target film thickness profile and creates a distribution of the target polishing amount on the polished surface Wa. The control device 50 determines a site (specific site) to be polished positively (and / or negatively) based on the created distribution of the target polishing amount.

[0096] In this way, the control device 50 determines the pressing force or pressing pressure of the pressing actuator 10 against the wafer W corresponding to a specific site of the wafer W and / or other sites excluding the specific site based on the initial film thickness profile. More specifically, the control device 50 determines the pressing force or pressing pressure required to achieve the target polishing amount within a predetermined polishing time based on the created distribution of the target polishing amount.

[0097] The pressing force of the pressing actuator 10 may be adjusted (corrected) according to the hardness of the polishing pad 21. For example, when polishing the wafer W using a relatively hard polishing pad 21, even if the pressing force of the pressing actuator 10 is small, the pressing force applied to the polished surface Wa by the polishing pad 21 changes greatly.

[0098] On the other hand, for example, when polishing the wafer W using a relatively soft polishing pad 21, the reaction force received by the wafer W from the pressing surface 10a of the pressing actuator 10 is absorbed by the polishing pad 21. Therefore, when the magnitude of the pressing force of the pressing actuator 10 is the same as the above pressing force, the pressing force applied to the surface Wa to be polished by the polishing pad 21 does not change significantly.

[0099] Thus, the control device 50 may correct the pressing force of the pressing actuator 10 according to the hardness of the polishing pad 21. The hardness data indicating the hardness of the polishing pad 21 is stored in the storage device 50a.

[0100] After determining the required pressing force (or pressing pressure) to achieve the target polishing amount, the control device 50 operates the pressing actuator 10 based on the determined pressing force (see step S103). Then, the control device 50 starts polishing the surface Wa to be polished of the wafer W with the pressing pressure (or pressing force) of a specific pressing actuator 10 among the plurality of pressing actuators 10 being different from the pressing pressure (or pressing force) of the other pressing actuators 10 (see step S104). The control device 50 may start polishing the surface Wa to be polished of the wafer W without operating the pressing actuators 10 other than the pressing actuator 10 corresponding to a specific portion of the wafer W.

[0101] At this time, the control device 50 operates the polishing liquid supply device 130 to supply the polishing liquid onto the surface Wa to be polished from at least one of the center supply nozzle 132 and the peripheral supply nozzle 133.

[0102] In the present embodiment, the stage 1 has a non-rotating structure. Therefore, during the polishing of the wafer W, it is possible to prevent the wafer W from shifting in the circumferential direction due to the rotation of the wafer W. As a result, the positional relationship between a specific portion (and / or other portions) of the wafer W and the portion of the wafer W where the pressing force acts does not shift. Therefore, the control device 50 can accurately polish the wafer W with the polishing pad 21.

[0103] When polishing the wafer W, the control device 50 rotates the polishing pad 21 about the central axis CL2 and supplies polishing liquid from the polishing liquid supply device 130, and moves the polishing pad 21 along a spiral polishing locus on the surface Wa to be polished.

[0104] When polishing the wafer W, the control device 50 does not necessarily need to move the polishing pad 21 along a spiral polishing locus according to a specific part (and / or other parts) of the wafer W. For example, when a part to be polished on the surface Wa to be polished exists locally, the control device 50 may directly move the polishing pad 21 to the local part and bring the polishing pad 21 into sliding contact with the local part.

[0105] The stage 1 is configured to dispose the surface Wa to be polished of the wafer W on the same plane as the upper surfaces of the plurality of dividing rings 1b when holding the wafer W. Therefore, the polishing pad 21 can polish the peripheral portion PP of the wafer W without being obstructed by the stage 1. When locally polishing the peripheral portion PP of the wafer W, the control device 50 can actively press the polishing pad 21 against the peripheral portion PP by operating the pressing actuator 10 corresponding to the peripheral portion PP to apply a pressing force to the peripheral portion PP.

[0106] During the polishing of the wafer W, the control device 50 may measure the film thickness of the wafer W by the film thickness measuring device 90. The control device 50 determines whether the film thickness of the wafer W has reached a predetermined target film thickness (that is, whether the polishing end point has been reached) (see step S105). For example, the control device 50 determines the polishing end point when the difference between the thickest part and the thinnest part in the film thickness of the wafer W reaches within a predetermined range.

[0107] When the film thickness of the wafer W has not reached the target film thickness (see "NO" in step S105), the control device 50 continues to polish the wafer W. On the other hand, when the film thickness of the wafer W has reached the target film thickness (see "YES" in step S105), the control device 50 ends the polishing of the wafer W (see step S106).

[0108] In one embodiment, the control device 50 may end the polishing of the wafer W based on a predetermined polishing time without determining the polishing end point based on the film thickness measurement of the wafer W. For example, after polishing the wafer W for a predetermined polishing time, the control device 50 may measure the film thickness distribution of the wafer W again and end the polishing of the wafer W when the film thickness distribution of the wafer W becomes a desired film thickness distribution.

[0109] FIG. 14 is a perspective view showing another embodiment of the polishing apparatus. In the embodiment shown in FIG. 14, the configurations not particularly described are the same as those in the above-described embodiment, and thus the overlapping descriptions are omitted.

[0110] Also in the embodiment shown in FIG. 14, the polishing apparatus has configurations corresponding to the polishing liquid supply device 130 and the polishing pad rotation mechanism 150, but the illustrations of these polishing liquid supply device 130 and polishing pad rotation mechanism 150 are omitted.

[0111] As shown in FIG. 14, the polishing pad moving mechanism 30 includes a polishing pad arm 232 to which a rotating shaft 31 is connected, and a plurality of support bars 210 that movably support the polishing pad arm 232.

[0112] The polishing apparatus includes a plurality of support columns 200 arranged around the stage 1. The support columns 200 extend in the Z-axis direction. The Z-axis direction is a direction extending perpendicular to the polished surface Wa of the wafer W held by the stage 1, in other words, a direction extending perpendicular to the X-axis direction and the Y-axis direction. The support bars 210 are spanned between adjacent support columns 200 and extend in the X-axis direction.

[0113] The polishing pad moving mechanism 30 includes a moving device 242 that moves the polishing pad arm 232 in the X-axis direction along the support rod 210, and a linear actuator 240 that moves the polishing pad 21 (and the pad holder 20) in the Y-axis direction together with the rotation axis 31.

[0114] The moving device 242 is, for example, a servo motor connected to the support rod 210. In this case, the moving device 242, by its operation, moves the polishing pad 21 (and the rotation axis 31, the pad holder 20) in the X-axis direction through the support rod 210 together with the polishing pad arm 232.

[0115] The linear actuator 240 is, for example, a combination of a moving body connected to the rotation axis 31 and a guide rail for moving the moving body in the Y-axis direction. In this case, the linear actuator 240, by its operation, moves the polishing pad 21 (and the rotation axis 31, the pad holder 20) in the Y-axis direction together with the moving body.

[0116] The control device 50 is electrically connected to these moving device 242 and linear actuator 240. Therefore, the control device 50 can freely move the polishing pad 21 (and the pad holder 20) in the X-axis direction and the Y-axis direction by operating each of the moving device 242 and the linear actuator 240.

[0117] The film thickness measuring device moving mechanism 100 includes a measuring arm 302 to which a plurality of film thickness measuring devices 90 arranged in a straight line are attached, and a support rod 220 that movably supports the measuring arm 302.

[0118] The support rod 220 is spanned between adjacent columns 200 and extends in the Y-axis direction. In the embodiment shown in FIG. 14, the support rod 210 and the support rod 220 extend in directions perpendicular to each other (that is, the X-axis direction and the Y-axis direction).

[0119] The film thickness measuring device moving mechanism 100 includes a moving device 222 that moves the measuring arm 302 in the Y-axis direction along the support rod 220. The moving device 222 is, for example, a servo motor and may have the same structure as the moving device 242. In this case, by its operation, the moving device 222 moves the plurality of film thickness measuring devices 90 together with the measuring arm 302 in the Y-axis direction through the support rod 220.

[0120] The control device 50 is electrically connected to the moving device 222. Therefore, the control device 50 can freely move the measuring arm 302 to which the plurality of film thickness measuring devices 90 are attached in the Y-axis direction by operating the moving device 222.

[0121] FIG. 15 is a diagram showing another embodiment of the suction device. In FIG. 15, for the sake of clarity of the drawing, a single pressing actuator 10 is depicted. As shown in FIG. 15, the pressing actuator 10 is an air cylinder having a hollow piston rod 155, a cylinder body 156 that houses the piston rod 155, and a piston 155a that is connected to the piston rod 155 and partitions the inside of the cylinder body 156.

[0122] In FIG. 15, the illustration of the air supply and exhaust lines connected to the upper and lower spaces of the piston 155a is omitted. The control device 50 controls the pressure of the fluid flowing through the air supply and exhaust lines to control the pressing pressure of the pressing actuator 10 against the wafer W.

[0123] The tip of the hollow piston rod 155 serves as a suction port for sucking the back surface Wb (i.e., the lower surface) of the wafer W. Similar to FIG. 6, it is desirable for the suction port to have a flange portion (not shown) that spreads outward. The flange portion is made of an elastic body such as rubber so as to reliably adsorb the back surface Wb of the wafer W.

[0124] In the embodiment shown in FIG. 15, the pressing actuator 10 and the vacuum line 81 can be integrally configured. Therefore, it is not necessary to dispose the vacuum line 81 separately from the pressing actuator 10, and the polishing apparatus can achieve space saving of the stage 1.

[0125] In FIG. 15, a single vacuum line 81 is disposed for a single pressing actuator 10. The suction device 80 may have a number of vacuum lines 81 corresponding to the number of pressing actuators 10. In one embodiment, the suction device 80 may have a number of vacuum lines 81 less than the number of pressing actuators 10.

[0126] In the embodiment shown in FIG. 6, the suction device 80 includes a vacuum line 81 disposed at the central portion of the stage 1. However, in one embodiment, the suction device 80 may include a plurality of vacuum lines 81 uniformly disposed on the entire mounting surface of the stage 1. With such an arrangement, it is possible to prevent the suction pressure on the wafer W from acting locally, and the suction pressure can be uniformly applied to the entire surface of the wafer W. In one embodiment, the embodiment shown in FIG. 6 and the embodiment shown in FIG. 15 may be combined.

[0127] In the embodiment shown in FIG. 15, the suction device 80 includes a control valve 160 instead of the vacuum source 82 (see FIG. 6). Thus, the suction device 80 does not necessarily include the vacuum source 82. For example, the vacuum line 81 may be connected to a utility line (not shown) for forming a vacuum laid in the factory.

[0128] In this case, the control device 50 forms a vacuum on the back surface Wb side of the wafer W by operating the control valve 160 attached to the vacuum line 81. Similarly, in the embodiment shown in FIG. 6, the suction device 80 may include a control valve 160 instead of the vacuum source 82.

[0129] The above-described embodiments are described for the purpose of enabling those with ordinary knowledge in the technical field to which the present invention pertains to implement the present invention. Various modifications of the above embodiments can be naturally made by those skilled in the art, and the technical idea of the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is construed in the broadest scope in accordance with the technical idea defined by the claims.

Explanation of Reference Numerals

[0130] 1 Stage 1a Base 1b Split Ring 10 Pressing Actuator 10a Pressing Surface 20 Pad Holder 21 Polishing Pad 21a Polishing Surface 22 Airbag 30 Polishing Pad Moving Mechanism 31 Rotation Shaft 32 Polishing Pad Arm 33 Swivel Shaft 34 Polishing Pad Drive Source 40 Rotation Motor 41, 42 Pulley 43 Belt 50 Control Device 50a Storage Device 50b Arithmetic Unit 60 Control Line 70 Moving Actuator 80 Suction Device 81 Vacuum Line 81a Suction Port 82 Vacuum Source 83 Fixed Member 90 Film Thickness Measuring Device 100 Film Thickness Measuring Device Moving Mechanism 101 Measuring Shaft 102 Measuring Arm 103 Swivel Shaft 104 Film Thickness Measuring Device Drive Source 130 Polishing Liquid Supply Device 132 Center supply nozzle 133 Peripheral supply nozzle 150 Polishing pad rotation mechanism 155 Piston rod 155a Piston 156 Cylinder body 160 Control valve 200 Support pillar 210 Support rod 220 Support rod 222 Moving device 232 Polishing pad arm 240 Linear actuator 242 Moving device 302 Measuring arm W Wafer Wa Ground surface Wb Back surface CL1,CL2 Central axis CP Center PP Peripheral part C1,C1’ First locus C2,C2’ Second locus PA Peripheral part side region CA Center side region

Claims

1. A polishing apparatus comprising: a stage that holds the substrate such that the surface to be polished of the substrate faces upward and has a non-rotating structure; a plurality of pressing actuators disposed inside the stage and independently pressing specific portions of the substrate; a pad holder that holds a polishing pad and presses the polishing pad against the surface to be polished; a polishing pad rotation mechanism configured to rotate the polishing pad about its own center.

2. The polishing apparatus according to claim 1, further comprising a polishing pad moving mechanism configured to move the polishing pad.

3. The polishing apparatus according to claim 2, wherein the polishing pad moving mechanism is configured to move the polishing pad along a spiral polishing track on the surface to be polished.

4. The polishing track includes: a first track extending from a peripheral portion of the substrate toward a central portion of the substrate; and a second track extending from the central portion of the substrate toward the peripheral portion of the substrate and not overlapping the first track.

5. The polishing apparatus according to claim 1, further comprising a film thickness measuring device configured to detect a film thickness signal corresponding to the film thickness of the substrate.

6. The polishing apparatus includes a plurality of film thickness measuring devices including the film thickness measuring device arranged side by side in a straight line, wherein the plurality of film thickness measuring devices are configured to detect a film thickness signal corresponding to the film thickness of the substrate along a linear measurement track on the surface to be polished.

7. The polishing apparatus according to claim 1, further comprising a polishing liquid supply device including a center supply nozzle that supplies polishing liquid from a central portion of the polishing pad.

8. The polishing apparatus includes a polishing liquid supply device including a peripheral supply nozzle disposed around the polishing pad, wherein the peripheral supply nozzle is configured to supply polishing liquid to an upstream side of the polishing pad in a traveling direction of the polishing pad.

9. The polishing apparatus according to claim 1, further comprising a suction device configured to vacuum suction the substrate disposed on the stage, wherein the suction device includes a vacuum line disposed inside the stage.

10. At least one of the plurality of pressing actuators is an air cylinder having a hollow piston rod, The polishing apparatus according to claim 9, wherein the vacuum line is connected to the piston rod.

11. A polishing method, Holding the substrate by a stage that houses a plurality of pressing actuators so that the surface to be polished of the substrate faces upward, A polishing method in which a polishing pad held by a pad holder is pressed against the surface to be polished while rotating about itself in a state where the pressing pressure of a specific pressing actuator among the plurality of pressing actuators is different from the pressing pressures of the other pressing actuators, and the substrate is polished in a non-rotating state.

12. The polishing method according to claim 11, wherein the polishing pad is moved along a spiral polishing track on the surface to be polished during polishing of the substrate.

13. Before polishing the substrate, measuring the film thickness distribution of the substrate, The polishing method according to claim 11, wherein the pressing pressures by the plurality of pressing actuators are determined based on the film thickness distribution.

14. The polishing method according to claim 11, wherein polishing liquid is supplied from a center supply nozzle disposed at the center portion of the polishing pad during polishing of the substrate.

15. The polishing method according to claim 11, wherein polishing liquid is supplied from a peripheral supply nozzle disposed around the polishing pad to the upstream side of the polishing pad in the traveling direction of the polishing pad during polishing of the substrate.

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