JPH1058317A - Polishing method and device for substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flat, smooth and clean polished surface by performing polishing while a surface to be polished of a substrate is pressed to a first polishing tool surface rotating on its axis with prescribed pressure, and performing polishing while the surface to be polished of the substrate is pressed with prescribed pressure to a second polishing tool surface adapted to conduct plane relative translation in a prescribed locus. SOLUTION: A first polishing process is performed for a wafer fitted to a top ring of a main polishing unit in such a manner that the top ring revolving on its axis presses the wafer to abrasive cloth of a turntable, high speed relative movement between the wafer and the abrasive cloth is conducted and a polishing liquid is supplied. After that, the wafer 1 is directly or coarsely washed to be transferred to a finishing unit 30. Here a second polishing process is performed, that is, a stool 37 conducts translational circular motion, the wafer 1 fitted to the top ring 32 revolving on its axis is pressed onto abrasive cloth 59 surface bonded to the stool 1, and polished by a polishing liquid supplied to the polishing surface. A very small relative translational circular motion with a radius (e) is caused between the abrasive cloth 59 and the wafer 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method and apparatus, and more particularly to a method and apparatus suitable for polishing a substrate requiring a high degree of cleanliness, such as a semiconductor wafer, a glass substrate, and a liquid crystal panel.

[0002]

2. Description of the Related Art In recent years, as the degree of integration of semiconductor devices has increased, circuit wiring has become finer and the distance between wirings has become smaller. Especially in the case of optical lithography of 0.5 μm or less, the depth of focus becomes shallower. Therefore, the flatness of the image forming surface of the stepper is required. Further, if particles larger than the distance between the wirings exist on the substrate, problems such as short-circuiting of the wirings occur. Therefore, in the processing of the substrate, it is important to clean the substrate together with the flattening. Such a situation is the same in the process of processing a glass substrate used as a mask or the like or a substrate such as a liquid crystal panel.

As a conventional polishing apparatus, as shown in FIG. 5, a polishing unit 10, a load / unload unit 2
1. Some have a transfer robot 22 and two washing machines 23a and 23b. As shown in FIG. 6, the polishing unit 10 includes a turntable 12 having a cloth (polishing cloth) 11 adhered to the upper surface thereof, and a top ring 13 which presses the semiconductor wafer 1 against the turntable 12 while holding the semiconductor wafer 1. I have.

In the polishing apparatus having such a configuration, the semiconductor wafer 1 is held on the lower surface of the top ring 13 and the semiconductor wafer 1 is pressed against the polishing cloth 11 on the rotating turntable 12 by a lifting cylinder. On the other hand, by flowing the polishing abrasive fluid Q from the polishing abrasive fluid nozzle 14, the polishing abrasive fluid Q is held by the polishing cloth 11, and the polishing abrasive fluid Q is placed between the polishing surface (the lower surface) of the semiconductor wafer 1 and the polishing cloth 11. Polishing is performed in the presence of Q.

The turntable 12 and the top ring 13 are rotating at independent rotation speeds. The top ring 13 is such that the edge of the wafer 1 is separated from the center and the edge of the turntable 12 by predetermined distances a and b. The wafer 1 is held so as to come to a position, whereby the entire surface of the wafer 1 is polished uniformly and at a high speed. Therefore, the turntable 12
Is set to be twice or more the diameter d of the wafer 1 as shown in the following equation. D = 2 (d + a + b)

The polished wafer 1 is supplied to a cleaning device 23a,
In the load / unload unit 21, the wafer is transferred to the wafer transfer cassette 24 through the first or several-order cleaning step and drying step at 23 b. As a method for cleaning the wafer 1, brushes such as nylon and mohair, PVA
Scrub cleaning in which the surface is rubbed with a (polyvinyl alcohol) sponge is performed.

[0007]

In the conventional polishing apparatus as described above, the relative displacement between the turntable 12 and the top ring 13 is large and the relative speed thereof is large, so that efficient polishing is performed, Can be obtained sufficiently, but the surface roughness tends to increase. In order to prevent this, it is conceivable to install two turntables and perform polishing by changing the roughness, rotation speed and polishing liquid of the polishing pad. However, as described above, the diameter of the turntable is twice as large as that of the wafer, occupying a large area, and increasing the apparatus cost. This disadvantage becomes more remarkable as the diameter of the semiconductor wafer increases.

On the other hand, with one turntable, for example,
It is conceivable to perform polishing by changing the polishing liquid and reducing the rotation speed. However, the economics of the polishing liquid itself are reduced, and the efficiency is reduced due to prolonged polishing time.

[0009] Regarding cleaning, when scrub cleaning is performed after polishing using an abrasive, it is difficult to remove submicron-level particles or when the bonding force between the wafer and the particles is strong, the cleaning effect is high. There was a problem that it did not appear.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a polishing method and a polishing apparatus capable of efficiently performing advanced flattening and cleaning with a compact apparatus.

[0011]

According to a first aspect of the present invention, there is provided a first step of performing polishing while pressing a surface to be polished of a substrate against a surface of a first polishing tool which rotates by a predetermined pressure; A second step of performing processing while pressing the polished surface of the substrate with a predetermined pressure on a second polishing tool surface that performs a plane relative translation motion with a predetermined trajectory with respect to the polished surface of the substrate. A polishing method for a substrate characterized by the following.

A translational motion refers to a case where two surfaces move relative to each other without changing their attitude with respect to each other, that is, without rotating relatively, or a case where a relative motion such as such translational motion is mainly performed is performed. The movement pattern may be a circulating movement along a predetermined trajectory or a random (irregular) movement. In this translation, the same relative movement takes place in each part of the contacting surface. The trajectory of the circular motion may be a reciprocating motion along a straight line or a special shape such as a polygon or an ellipse.
Optimally, it is a circular motion from the viewpoint of polishing properties and mechanism. In order to obtain such a relative circular translational movement, either the second polishing tool surface or the surface to be polished of the substrate may be actually moved, or both may be moved.

In this method, in the first step, the wafer and the polishing tool surface are relatively moved at a relatively high speed to perform a predetermined polishing to increase the flatness. In the second step, the surface roughness of the polishing tool is reduced, and polishing is performed at a relatively low relative speed to finish the surface to be polished smoothly and to remove extremely small particles attached thereto. Abrasives suitable for each purpose are interposed on the contact surface.
In the first step, abrasive grains are included, and in the second step, pure water or a chemical solution is used. In the second step, abrasive grains are not usually used, and even when they are used, a small amount of ultrafine abrasive grains is used, and the pressing force between the polished surface and the surface to be polished is relatively small.

According to a second aspect of the present invention, there is provided the method of polishing a substrate according to the first aspect, wherein, in the second step, the translational movement is a circulating movement having a predetermined pattern. The invention according to claim 3 is the method for polishing a substrate according to claim 1, wherein in the second step, the translational movement is given by moving the second polishing tool. The invention described in claim 4 is
2. The method according to claim 1, wherein, in the second step, the translational movement is an irregular movement.

According to a fifth aspect of the present invention, in the second step, the irregular translational motion is given as a vector sum of two linear motions.
3. The method for polishing a substrate according to item 1. The invention according to claim 6, wherein a pressing pressure of the polished surface of the substrate against the first polishing tool surface is 200 to 500 g / cm ² , and a polished surface of the substrate against the second polishing tool surface. ^{2. The} method for polishing a substrate according to claim 1, wherein the pressing pressure is 0 to 200 g / cm < ² >.

In the second step, at least one of the substrate and the polishing tool may be rotated by a rotation cycle sufficiently larger than the cycle of the circulating translational motion, whereby the position where the polishing surface and the surface to be polished come into contact with each other. Are sequentially changed, and the process is made uniform throughout.

In the second step, pure water may be used as a polishing liquid, so that this step is used not only as a final step of polishing but also as one step of cleaning, and particularly, is performed on a surface to be polished. It is effective for removing minute particles.

According to a seventh aspect of the present invention, there is provided a first polishing tool having a first polishing tool rotatable along a polishing surface and a pressing means capable of pressing the surface to be polished of the substrate at a predetermined pressure on the polishing surface. 1
A polishing section, a second polishing tool capable of relatively translating along a predetermined locus with respect to the surface to be polished of the substrate, and pressing means for pressing the surface to be polished of the substrate against the polishing surface with a predetermined pressure. An apparatus for polishing a substrate, comprising: a second polishing section having the same.

In such a polishing apparatus, there is no specific stationary point because the second polishing tool does not perform polishing by rotation but performs translational movement as a whole. Therefore, the size of the second polishing tool is only required to be slightly larger than the size obtained by adding the translation space to the substrate area, and the entire apparatus becomes compact. Along with this, the driving motor may be small and the occupied area may be small. This advantage increases as the size of the substrate to be processed such as a semiconductor wafer increases. In addition, since the second polishing tool does not rotate, the same relative speed can be obtained in any part of the substrate to be processed, and flatness can be easily obtained when polishing at a low speed.
This is also advantageous for obtaining a smooth surface.

[0020] The apparatus may comprise a support for supporting the second polishing tool so as to be capable of circulating translation, and a driving means for circulating and translating the support. Further, the drive means may have a drive end provided eccentrically with respect to a rotation axis of a drive source of the drive means, and the support portion may have a recess for accommodating the drive end.

According to an eighth aspect of the present invention, the pressing pressure of the polished surface of the substrate against the first polishing tool surface is 200.
And the pressing pressure of the surface to be polished of the substrate against the second polishing tool surface is 0 to 200 g / cm ^2.
a polishing apparatus substrate according to claim 7, characterized in that the m ^2.

According to a ninth aspect of the present invention, there is provided a base, a surface plate to which a polishing tool can be attached on an upper surface, a support portion for supporting the surface plate on the base so as to be capable of translational translation, and And a driving means for causing the board to circulate and translate. The drive means may have a drive end provided eccentrically with respect to a rotation axis of a drive source of the drive means, and the support may have a recess for accommodating the drive end.

According to a tenth aspect of the present invention, there is provided the polishing apparatus according to the ninth aspect, wherein the supporting portion supports the surface plate at at least three places on the edge thereof. In addition, the supporting portion has a connecting member that connects a pair of shafts whose axes are shifted, and each shaft of the connecting member is rotatably inserted into a recess formed in the base and the base. It may be configured.

According to a twelfth aspect of the present invention, in the polishing apparatus according to the ninth aspect, the polishing plate is provided with a polishing liquid supply flow path which opens toward a polishing surface of the polishing tool. Device. Thereby, the polishing liquid can be sufficiently supplied also to the central portion of the substrate.

According to a twelfth aspect of the present invention, there is provided a base, a surface plate to which a polishing tool can be attached on an upper surface, a first support portion for supporting the surface plate so as to be linearly movable in a first direction, A second support for supporting the first support in a second direction different from the first direction such that the first support can be linearly moved;
And a driving means for linearly moving the second support portion.

The translational movement in the second step may be a movement that does not substantially involve rotation between the second polishing tool and the substrate, but may include a slight relative rotation and a substantially planar relative movement. Anything that performs a translational motion may be used.

[0027]

FIG. 1 shows an embodiment of a polishing apparatus according to the present invention. A load / unload unit 21 for loading and unloading a wafer 1 as a material to be polished is provided at one end of a rectangular space. A main polishing unit (first polishing unit) 10 having a turntable and a top ring is provided on the other end side. Then, on the wafer transfer line connecting them, in this example, two transfer robots 2
2a and 22b are provided so as to be able to travel, and a reversing machine 25 for reversing the wafer 1 is provided on one side of the transfer line, and finish polishing units (second polishing units) 30 and 3 are provided on the other side.
The washing machines 23a, 23b, 23c of the machine are installed.
The main polishing unit 10 includes one turntable 12 and 2
It has two top rings 13 and can process two wafers 1 in parallel, except for this point.
And FIG. 6.

The configuration of the finish polishing unit 30 will be described with reference to FIGS. It has a translation table section 31 for providing a polishing tool surface which performs a cyclic translational movement, and a top ring 32 for gripping the wafer 1 with the surface to be polished downward and pressing the wafer 1 against the polishing tool surface with a predetermined pressure.

The translation table 31 has a motor 33 inside.
A support plate 35 is provided on an upper part of a cylindrical casing 34 for accommodating the inside of the casing.
One or more support portions 36 are formed, and the platen 37 is supported. That is, at the corresponding position between the upper surface of the support portion 36 and the lower surface of the surface plate 37, the plurality of recesses 3 are arranged at equal intervals in the circumferential direction.
8, 39 are formed, each bearing 4
0, 41 are mounted. And this bearing 4
A connecting member 44 having two shafts 42 and 43 shifted by “e” as shown in FIG. 3 is attached to 0 and 41 by inserting the ends of the shafts. Is the radius "e"
It can be translated along the circle.

A drive end 46 eccentrically provided at the upper end of the main shaft 45 of the motor 33 is provided on the lower surface side of the center of the surface plate 37.
Is formed through a bearing 47. This eccentric amount is also “e”. The motor 33 is
The main shaft 45 is accommodated in a motor chamber 49 formed in the casing 34, is supported by upper and lower bearings 50, 51, and is provided with balancers 52a, 52b for balancing loads due to eccentricity.

The platen 37 is set to a diameter slightly larger than the value obtained by adding twice the eccentricity "e" to the diameter of the wafer 1 to be polished, and is constituted by joining two plate members 53 and 54 together. Have been. A space 55 is formed between these members to allow the polishing liquid supplied to the polishing surface to flow. The space 55 communicates with a polishing liquid supply port 56 provided on a side surface, and also communicates with a plurality of polishing liquid discharge holes 57 opened on the upper surface. A discharge hole 58 is formed at a position corresponding to a polishing cloth 59 attached to the upper surface of the surface plate 37.
7 are distributed substantially uniformly over the entire surface of the substrate 7. Polishing cloth 59
May be provided with grooves in a lattice shape, spiral shape, or radial shape on the surface thereof, and the discharge ports 58 may communicate with the grooves.

The top ring 32, which is a pressing means, is attached to the lower end of the shaft 60 so as to be able to tilt to some extent in accordance with the polishing surface, and the pressing force of an air cylinder (not shown) and the rotational force of the drive motor are transmitted through the shaft 60. The power is transmitted to the top ring 32. This top ring 32
Are structurally similar to FIGS. 5 and 6 except that the rotation speed is slow.
Are the same as those shown in FIG. In addition, a collection tank 61 for collecting the supplied polishing liquid is attached to the outside of the upper part of the casing 34.

Hereinafter, the operation of the polishing apparatus configured as described above will be described. The wafer 1 in the storage cassette 24 (see FIG. 5) is mounted on the top ring 13 of the main polishing unit 10 by the transfer robots 22a and 22b via a reversing machine 25 as necessary. The top ring 13 is shown in FIG.
As shown in FIG. 7, the wafer 1 is pressed onto the polishing pad 11 of the turntable 12 while rotating. Wafer 1 and polishing cloth 11
The first polishing step is performed by the high-speed relative movement during the above and the polishing liquid Q supplied from the nozzle 14.

The wafer 1 having undergone the first polishing step is transferred directly or after rough cleaning to a finish polishing unit 30, where the second polishing step is performed. That is, the platen 37 makes a translational circular motion by the operation of the motor 33, and the wafer 1 attached to the top ring 32 is pressed against the surface of the polishing pad 59 attached to the platen 37.

Polishing is performed by the polishing liquid supplied to the polishing surface through the polishing liquid supply port 56, the polishing liquid space 55, and the polishing liquid discharge holes 57 and 58. A small relative translational circular motion having a radius "e" occurs between the polishing cloth 59 and the wafer 1, and the surface to be polished of the wafer 1 is uniformly polished. If the positional relationship between the polished surface and the polished surface is the same, the polished surface is affected by a local difference. Polishing is prevented only at the place.

In the first polishing step, the wafer 1 and the surface of the polishing tool (polishing cloth) 11 are relatively moved at a high speed in order to obtain a predetermined polishing amount, and the pressing force is relatively large. , The second polishing step improves flatness and surface roughness,
Since the purpose is to remove the attached fine particles, the roughness of the surface of the polishing tool (polishing cloth) 59 is reduced,
The relative movement speed and pressing force between the tool and the wafer are set smaller than those in the first polishing step. The polishing liquid is usually water polishing using pure water, and a chemical solution or a special slurry is used as necessary.

The wafer after the second polishing step is dried after being subjected to several washings in washing machines 23a to 23c as necessary, and is stored in a wafer cassette 24. In this polishing apparatus, two top rings 13 are provided in the main polishing unit 10 for performing the first polishing step. Therefore, by making the polishing time of the second polishing step approximately half of the polishing time of the first polishing step,
Each device operates without any loss time to improve efficiency.

In this apparatus, since the polishing step is performed in two stages and performed in parallel, the polishing time in the first polishing step is shortened. Therefore, the overall throughput (processing amount) of the apparatus is as shown in FIG. It is improved compared to the conventional device shown in FIG. Further, since the finish polishing unit 30 is of the circular translation type, the size of the surface plate 37 may be a diameter that is larger than the size of the wafer 1 by the amount of eccentricity “e”. Therefore, the installation area can be significantly reduced as compared with the case where two units of the same turntable type as the main polishing unit 10 are installed. Further, in the finish polishing unit 30, since the surface plate 37 performs a circulating translational motion, as shown in FIG. 2, the surface plate 37 can be supported at a plurality of locations on the edge thereof, so that the turntable can be rotated at a high speed. Polishing with higher flatness can be performed as compared with the above.

The average polishing conditions of the first polishing step and the second polishing step are shown below in comparison. Primary polishing Abrasive Depends on the material of the material to be polished Polishing cloth Depends on the material of the material to be polished Surface pressure 200 to 500 g / cm ² Relative speed 0.07 to 0.6 m / sec Time Depends on the amount of polishing Secondary polishing Abrasive Water, chemical solution, slurry Abrasive cloth Soft cloth (nonwoven fabric, nap layer) Surface pressure 0 to 200 g / cm ² Relative speed 0.07 to 0.6 m / sec Time 10 to 120 sec

In the above embodiment, the polishing tool is circulated and translated, but the substrate may be moved. Further, in the above embodiment, the platen is supported using the crank-shaped connecting member. However, a suitable support structure that enables translational movement while restricting rotation, for example, a magnetic bearing or a non-lubricated sliding bearing is used. May be used.

In the above description, the eccentric drive end is formed on the rotary drive shaft of the motor, and the platen is translated in circular motion. For example, the vector sum of the motion in the X direction and the Y direction is obtained by using an XY stage. The platen may be moved, and both the tool and the substrate may be moved to obtain the same translational movement.

FIG. 4 shows one embodiment of an apparatus for carrying out such a method, in which an underside of a top ring 100 for holding a substrate on a lower side and an upper side of an XY stage. The mounted polishing tool 101 is arranged. In this example, the polishing tool uses an electrodeposited grindstone in which abrasive grains having a relatively fine grain size are fixed with a binder.

The XY stage has an X stage 102, a Y stage 103, and a fixed board 104 which are sequentially installed on a base 105. For example, a sliding mechanism and a linear drive mechanism such as a feed screw are provided between the X stage and the Y stage so that the X stage can travel in the X direction with respect to the Y stage. Similarly, a sliding mechanism and a linear drive mechanism are provided between the Y stage and the fixed board so that the Y stage can run in the Y direction with respect to the fixed board. Further, a control device for controlling these drive mechanisms is provided.

In such a configuration, the X stage 10
When the sine wave and cosine wave displacements of the same phase are given in the respective directions by the respective drive mechanisms of the 2 and Y stage 103, the X stage makes a circular motion as a combined vector with respect to the fixed plate 104. As a result, the polishing tool 101 performs a circulating translational motion as in the apparatus according to the above-described embodiment, and polishing is performed. Also in this example, as shown by the arrow in FIG. 4, the top ring may be rotated at a rotation cycle sufficiently larger than the cycle of the circulating translational motion to eliminate the local influence of the polishing tool.

Since this device does not use a mechanical structure such as an eccentric mechanism, there is an advantage that the trajectory of the circulating translational motion can be arbitrarily changed. For example, the radius "e" of the circular motion can be changed during polishing of the substrate,
Control can be performed such that polishing is performed with a relatively small radius at the beginning and end of polishing, and polishing is performed with a relatively large radius at an intermediate stage. This can avoid disadvantages such as generation of a scratch in a fixed direction when a simple circulating motion is repeated.

This device can perform not only a circle but also an ellipse, a figure-eight movement, a circular translation movement such as an oscillating spiral, or any combination thereof. In addition, this device can perform a completely random, ie, non-circulating, translational motion instead of a circular motion of a specific trajectory. This is, for example,
The program can be executed by a program that determines a trajectory based on random numbers from a random number generator under a condition that a traveling route having a radius of curvature equal to or less than a predetermined radius of curvature is not adopted.

[0047]

As described above, according to the method of the present invention, in the first polishing step, the wafer and the polishing tool surface are relatively moved at a relatively high speed to perform a predetermined polishing to improve the flatness. In the second polishing step, the surface roughness of the polishing tool is reduced, the surface is polished at a relatively small relative speed to finish the surface to be polished smoothly, and the extremely small particles attached thereto are removed. As a result, a flat, smooth and clean polished surface can be efficiently obtained.

Further, according to the apparatus of the present invention, the second polishing tool does not perform polishing by rotation but performs translational movement as a whole. And the whole apparatus becomes compact, and accordingly, the driving motor also needs to be small, and the occupied area may be small. Further, by supporting the platen at at least three or more of its edges, the platen is stably supported even when a pressing force is applied, so that the flatness of the polished surface is maintained high.

[Brief description of the drawings]

FIG. 1 is a view showing an overall arrangement of a polishing apparatus according to the present invention.

FIG. 2 is a sectional view of a finish polishing unit.

3A and 3B are a plan view and a cross-sectional view of a motor side, on which a support portion at an edge of the surface plate of FIG. 2 is enlarged.

FIG. 4 is a perspective view showing another embodiment of the finish polishing unit.

FIG. 5 is a perspective view showing a conventional polishing apparatus.

FIG. 6 is a sectional view of a conventional polishing unit.

[Explanation of symbols]

 Reference Signs List 1 substrate (wafer) 10 main polishing unit (first polishing unit) 11 polishing cloth (polishing tool) 12 turntable 13 top ring (pressing means) 30 finish polishing unit (second polishing unit) 57, 58 supply of polishing liquid Hole 59 Polishing cloth (polishing tool) 32 Top ring (pressing means) 33 Motor (driving means) 35 Support plate (base) 36 Support section 37 Surface plate 44 Connecting member

Claims (12)

[Claims] A first step of performing polishing while pressing a surface to be polished of a substrate against a surface of a first polishing tool which rotates by a predetermined pressure; A step of performing a process while pressing the surface to be polished of the substrate with a predetermined pressure against a surface of a second polishing tool which performs relative translation motion. 2. The method according to claim 1, wherein, in the second step, the translational movement is a circulating movement having a predetermined pattern. 3. The method according to claim 1, wherein, in the second step, the translation is provided by moving the second polishing tool. 4. The method according to claim 1, wherein in the second step, the translational movement is an irregular movement. 5. The method according to claim 1, wherein, in the second step, the irregular translational motion is given as a vector sum of two linear motions. 6. The pressing pressure of the polished surface of the substrate against the first polishing tool surface is 200 to 500 g / cm ² , and the pressing pressure of the polished surface of the substrate against the second polishing tool surface. the polishing method of substrate according to claim 1, characterized in that the 0 to 200 g / cm ^2. 7. A first polishing unit having a first polishing tool rotatable along a polishing surface, and a pressing means capable of pressing a surface to be polished of a substrate at a predetermined pressure on the polishing surface, A second translational movement relative to the polished surface of the substrate along a predetermined trajectory
A substrate polishing apparatus, comprising: a polishing tool having a second polishing section having a polishing tool, and pressing means for pressing a surface to be polished of the substrate at a predetermined pressure on the polishing surface. 8. The pressing pressure of the polished surface of the substrate against the first polishing tool surface is 200 to 500 g / cm ² , and the pressing pressure of the polished surface of the substrate against the second polishing tool surface. polishing device substrate according to claim 7, characterized in that the 0 to 200 g / cm ^2. 9. A base, a surface plate to which a polishing tool can be mounted on an upper surface, a support portion for supporting the surface plate so as to be capable of circulating translation on the base, and a drive for circulating and translating the surface plate. Means for polishing a substrate, comprising: 10. The polishing apparatus according to claim 9, wherein said support portion supports said platen at at least three or more edges thereof. 11. The polishing apparatus according to claim 9, wherein the surface plate is provided with a polishing liquid supply flow path that opens toward a polishing surface of the polishing tool. 12. A base, a surface plate to which a polishing tool can be attached on an upper surface, a first support portion for supporting the surface plate so as to be linearly movable in a first direction, and the first support portion. A second support portion that supports linear movement in a second direction different from the first direction; and a driving unit that linearly moves the base, the first support portion, and the second support portion. An apparatus for polishing a substrate, comprising: