Polishing pad, substrate processing device, and substrate processing method

Abstract

This polishing pad polishes a substrate. The polishing pad comprises: a metal member having a catalyst for producing a reactive species that reacts with the substrate from a processing solution supplied to the substrate; and a holding member for holding the metal member. The metal member and the holding member each extend perpendicularly from the surface of the polishing pad facing the substrate, and have a certain cross-sectional shape.

Description

Polishing pad, substrate processing apparatus, and substrate processing method

[0001] The present disclosure relates to a polishing pad, a substrate processing apparatus, and a substrate processing method.

[0002] The substrate processing method described in Patent Document 1 involves supporting the outer edge of the substrate with a substrate support, with the back surface of the substrate facing up, and removing the material to be removed within a predetermined processing range from the inner periphery of the back surface of the substrate to the vicinity of the substrate support.

[0003] The substrate processing method described in Patent Document 2 polishes a glass substrate using a catalyst. The catalyst dissociates water molecules, breaks bonds between oxygen and other elements that make up the glass substrate, and helps generate decomposition products through hydrolysis.

[0004] Japanese Patent Publication No. 2015-111731 Japanese Patent Publication No. 2015-231939

[0005] One embodiment of the present disclosure provides a technique for stabilizing the polishing performance of a polishing pad having a catalyst.

[0006] A polishing pad according to an embodiment of the present disclosure is used to polish a substrate. The polishing pad includes a metal member having a catalyst that generates a reactive species from a processing liquid supplied to the substrate, the reactive species reacting with the substrate, and a holding member that holds the metal member. The metal member and the holding member each extend perpendicularly from a surface of the polishing pad facing the substrate and have a constant cross-sectional shape.

[0007] According to one embodiment of the present disclosure, the polishing performance of a polishing pad having a catalyst can be stabilized.

[0008] FIG. 1 is a longitudinal cross-sectional view showing a substrate processing apparatus according to an embodiment. FIG. 2 is a longitudinal cross-sectional view showing an example of polishing using a catalyst. FIG. 3 is a longitudinal cross-sectional view showing a polishing pad according to a reference embodiment. FIG. 4 is a longitudinal cross-sectional view showing a polishing pad according to an embodiment. FIG. 5 is a longitudinal cross-sectional view showing an example of the relationship between the hardness of a holding member and the conformability of a polishing pad. FIG. 6(A) is a transverse cross-sectional view showing a first example of a cross-sectional shape of a polishing pad, FIG. 6(B) is a transverse cross-sectional view showing a second example of a cross-sectional shape of a polishing pad, FIG. 6(C) is a transverse cross-sectional view showing a third example of a cross-sectional shape of a polishing pad, and FIG. 6(D) is a transverse cross-sectional view showing a fourth example of a cross-sectional shape of a polishing pad. FIG. 7 is a longitudinal cross-sectional view showing an example of dressing of a polishing pad. FIG. 8 is a longitudinal cross-sectional view showing an example of a discharge port of a polishing pad. FIG. 9 is a longitudinal cross-sectional view showing an example of a second holding member of a polishing pad. FIG. 10 is a longitudinal cross-sectional view showing an example of unevenness on the underside of a polishing pad.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that in each drawing, the same or similar components are denoted by the same reference numerals, and descriptions thereof may be omitted. In this specification, the X-axis direction, Y-axis direction, and Z-axis direction are perpendicular to each other. The X-axis direction and Y-axis direction are horizontal directions, and the Z-axis direction is vertical. The X-axis direction includes the positive X-axis direction and the negative X-axis direction that is opposite to the positive X-axis direction. The Y-axis direction includes the positive Y-axis direction and the negative Y-axis direction that is opposite to the positive Y-axis direction. The Z-axis direction includes the positive Z-axis direction and the negative Z-axis direction that is opposite to the positive Z-axis direction.

[0010] A substrate processing apparatus 1 according to one embodiment will be described with reference to FIG. 1 . The substrate processing apparatus 1 processes a substrate W. The substrate W has a first main surface Wa and a second main surface Wb facing opposite to the first main surface Wa. The first main surface Wa may be a surface on which an electronic circuit is formed, and the second main surface Wb may be a surface on which no electronic circuit is formed. The substrate W has a semiconductor wafer such as a silicon wafer. The substrate W may further have a functional film formed on the surface of the semiconductor wafer. The functional film may be an oxide film, a nitride film, a metal film, or the like. The substrate processing apparatus 1 polishes the second main surface Wb of the substrate W. The substrate processing apparatus 1 may also polish the first main surface Wa of the substrate W.

[0011] The substrate processing apparatus 1 includes, for example, a first holding unit 10, a first rotating unit 15, a second holding unit 20, a second rotating unit 25, and a first moving unit 40. The first holding unit 10 holds the substrate W horizontally. The first holding unit 10 holds the substrate W with the second main surface Wb facing upward, but the first main surface Wa of the substrate W may also face upward. The first rotating unit 15 rotates the substrate W together with the first holding unit 10. The second holding unit 20 holds a polishing pad 30. The polishing pad 30 polishes the upper surface (e.g., the second main surface Wb) of the substrate W. The second rotating unit 25 rotates the polishing pad 30 together with the second holding unit 20. The first moving unit 40 moves the polishing pad 30 together with the second holding unit 20.

[0012] The first holding unit 10 has a gripping unit 11 that grips the outer periphery of the substrate W, for example. A plurality of gripping units 11 are provided at intervals along the outer periphery of the substrate W. The gripping units 11 are movable radially outward and radially inward of the substrate W. When the lower surface of the substrate W is the first main surface Wa, it is preferable that the first holding unit 10 does not contact the lower surface of the substrate W to prevent damage to the electronic circuit. However, the first holding unit 10 may contact the lower surface of the substrate W, or may have a suction stage (not shown) instead of the gripping unit 11. Contact of the suction stage with the lower surface of the substrate W can suppress deformation of the substrate W due to the polishing pressure of the polishing pad 30. The first rotating unit 15 rotates the first holding unit 10, thereby rotating the substrate W together with the first holding unit 10. The first rotating unit 15 includes a first motor 16 and the like.

[0013] The first rotating unit 15 has a first rotating shaft 17 in addition to a first motor 16. The rotational driving force of the first motor 16 is transmitted to the first rotating shaft 17 via, for example, a gear or a belt. The first rotating shaft 17 is provided, for example, vertically. A first holding unit 10 is provided at the upper end of the first rotating shaft 17, and the first holding unit 10 rotates together with the first rotating shaft 17.

[0014] The second holding unit 20 holds, for example, the polishing pad 30 from above. The polishing pad 30 is, for example, disk-shaped and is replaceably attached to the underside of the second holding unit 20. The second rotating unit 25 rotates the second holding unit 20, thereby rotating the polishing pad 30 together with the second holding unit 20. The second rotating unit 25 includes a second motor 26 and the like.

[0015] The second rotating unit 25 has a second rotating shaft 27 in addition to a second motor 26. The rotational driving force of the second motor 26 is transmitted to the second rotating shaft 27 via, for example, a gear or a belt. The second rotating shaft 27 is provided, for example, vertically. The second holding unit 20 is provided at the lower end of the second rotating shaft 27, and the second holding unit 20 rotates together with the second rotating shaft 27.

[0016] The first moving unit 40 moves the second holding unit 20 in the vertical direction, thereby raising and lowering the polishing pad 30 together with the second holding unit 20. The first moving unit 40 raises and lowers the second holding unit 20 together with, for example, the second rotating unit 25. The first moving unit 40 presses the polishing pad 30 against the upper surface of the substrate W. Hereinafter, the pressure pressing the polishing pad 30 against the substrate W may be referred to as the polishing pressure.

[0017] The polishing pad 30 has a facing surface 30a that faces the substrate W. The facing surface 30a is the lower surface. When the size of the facing surface 30a is smaller than the size of the upper surface of the substrate W, the first moving unit 40 moves the polishing pad 30 in the horizontal direction to scrub the entire upper surface of the substrate W. The first moving unit 40 moves the polishing pad 30 radially outward or radially inward of the substrate W.

[0018] The first moving unit 40 has, for example, a Z-axis guide 41, a Z-axis slider 42, and a Z-axis motor 43. The Z-axis motor 43 moves the Z-axis slider 42 along the Z-axis guide 41. The Z-axis slider 42 is mounted with the second rotating unit 25. The second rotating unit 25 and the second holding unit 20 move in the Z-axis direction together with the Z-axis slider 42.

[0019] The first moving unit 40 also has, for example, an X-axis guide 45, an X-axis slider 46, and an X-axis motor 47. The X-axis motor 47 moves the X-axis slider 46 along the X-axis guide 45. A Z-axis guide 41 is fixed to the X-axis slider 46. The Z-axis guide 41 and the like (including the second rotating unit 25 and the second holding unit 20) move in the X-axis direction together with the X-axis slider 46.

[0020] The substrate processing apparatus 1 includes a liquid supply unit 50 and a liquid recovery unit 55. The liquid supply unit 50 supplies a processing liquid to the upper surface of the substrate W while the substrate W is being polished. The liquid supply unit 50 includes, for example, a nozzle 51. The liquid recovery unit 55 recovers the processing liquid that splashes from the upper surface of the substrate W. The liquid recovery unit 55 includes, for example, a cup 56.

[0021] The nozzle 51 supplies the processing liquid, for example, to the center of the upper surface of the rotating substrate W. The processing liquid spreads over the entire upper surface of the substrate W by centrifugal force. The liquid supply unit 50 has a supply line that sends the processing liquid to the nozzle 51. The liquid supply unit 50 may have an on-off valve, a flow rate controller, and a flow meter along the supply line. Note that, as will be described in more detail later, instead of or in addition to the nozzle 51, the polishing pad 30 may supply the processing liquid to the upper surface of the substrate W.

[0022] The cup 56 surrounds the outer periphery of the substrate W held by the first holding part 10 and collects the processing liquid scattered from the outer periphery of the substrate W. A drain pipe 57 and an exhaust pipe 58 are provided at the bottom of the cup 56. The drain pipe 57 discharges the processing liquid accumulated inside the cup 56. The exhaust pipe 58 discharges the gas accumulated inside the cup 56.

[0023] The substrate processing apparatus 1 includes a control circuit 90. The control circuit 90 is, for example, a computer, and includes an arithmetic unit 91 such as a CPU (Central Processing Unit), and a storage unit 92 such as a memory. The storage unit 92 stores programs that control various processes executed in the substrate processing apparatus 1. The control circuit 90 controls the operation of the substrate processing apparatus 1 by causing the arithmetic unit 91 to execute the programs stored in the storage unit 92.

[0024] The program, i.e., a computer program product, may be supplied in a form recorded on a removable storage medium such as a memory card, an optical disk, or a hard disk drive (HDD). The control circuit 90 reads the program from the storage medium and stores it in the storage unit 92. The storage unit 92 includes a storage medium such as an HDD, a solid state drive (SDD), or an electronically erasable programmable read-only memory (EEPROM). The program may be written in advance to the storage medium of the storage unit 92. The control circuit 90 may also obtain the program distributed by a remote server device or the like via a network or other communication.

[0025] The control circuit 90 includes electronic circuits such as a CPU, a GPU (Graphics Processing Unit), an FPGA (Field Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit), and performs the various control operations described in this specification by executing instruction codes stored in memory or by being a circuit designed for a specific application.

[0026] 1 again, the operation of the substrate processing apparatus 1 will be described. First, the first holding unit 10 receives the substrate W from a transport device (not shown) and holds the substrate W horizontally with the second main surface Wb of the substrate W facing upward. As described above, the first holding unit 10 may also hold the substrate W horizontally with the first main surface Wa of the substrate W facing upward. Next, the first rotating unit 15 rotates the substrate W together with the first holding unit 10.

[0027] Thereafter, the first moving unit 40 lowers the polishing pad 30 together with the second holding unit 20, and the second rotating unit 25 rotates the polishing pad 30 together with the second holding unit 20. Next, the first moving unit 40 moves the polishing pad 30 radially outward or radially inward of the substrate W while keeping the polishing pad 30 in contact with the upper surface of the substrate W.

[0028] It is preferable that the control circuit 90 controls the polishing pressure to be constant when moving the polishing pad 30 radially outward or radially inward of the substrate W. Even if the upper surface of the substrate W is warped, the entire upper surface of the substrate W can be polished evenly. Note that it is sufficient for the control circuit 90 to control the polishing pressure to be constant within an error range.

[0029] As shown in FIG. 2, the polishing pad 30 polishes the upper surface (e.g., the second main surface Wb) of the substrate W. The polishing pad 30 has a catalyst, which will be described in detail later. The catalyst generates reactive species from the processing liquid that react with the substrate W. The reactive species are generated on the surface of the catalyst and selectively etch convex portions on the upper surface of the substrate W. The substrate W can be polished by a catalyst referred etching (CARE) method, in which the surface of the catalyst serves as a reference surface. The polishing pad 30 has a catalyst on its lower surface, which is the surface 30a facing the substrate W. As shown in FIG. 2, the polishing pad 30 selectively etches convex portions on the upper surface of the substrate W. As a result, the upper surface of the substrate W is planarized.

[0030] The catalyst is made of, for example, a transition metal element, preferably Ru, Pt, Au, Ag, Cu, Ni, Cr, or Mo, and more preferably Ru. The catalyst may be a single metal or an alloy. The upper surface of the substrate W is made of an insulating film, a conductive film, a semiconductor film, or a semiconductor substrate. The insulating film may be, for example, SiO ２ or a Low-k material, etc. The conductive film is, for example, a Cu film or a W film, etc. The semiconductor film is, for example, a polycrystalline silicon film or an amorphous silicon film, etc. The semiconductor substrate is, for example, a silicon wafer, etc.

[0031] The processing liquid used in catalyst-based etching is selected appropriately depending on the combination of the catalyst material and the material on the top surface of the substrate W, but preferably contains water. Decomposition products can be generated by hydrolysis, and the decomposition products can be dissolved in water. Examples of processing liquids include diluted hydrofluoric acid, pure water, water containing dissolved oxygen, ozone water, and hydrogen peroxide solution.

[0032] Next, a polishing pad 30 according to one embodiment will be described with reference to Fig. 3. The polishing pad 30 shown in Fig. 3 includes a catalyst layer 31 and a substrate 32 on which the catalyst layer 31 is formed. The catalyst layer 31 contains a catalyst that generates reactive species from the processing liquid that react with the substrate W. The catalyst layer 31 is formed on the lower surface of the substrate 32. When the catalyst layer 31 of the polishing pad 30 shown in Fig. 3 wears or peels off, the contact area between the catalyst layer 31 and the substrate W decreases, resulting in a decrease in polishing efficiency.

[0033] Next, a polishing pad 30 according to one embodiment will be described with reference to Fig. 4. The polishing pad 30 shown in Fig. 4 includes a metal member 33 and a holding member 34 that holds the metal member 33. The metal member 33 has a catalyst that generates reactive species from the processing liquid that react with the substrate W. The metal member 33 is embedded in the holding member 34 and is exposed at the surface of the holding member 34 that faces the substrate W. The polishing pad 30 shown in Fig. 4 has a different structure from the polishing pad 30 shown in Fig. 3.

[0034] Specifically, the metal member 33 and the holding member 34 each extend perpendicularly from the surface 30a of the polishing pad 30 facing the substrate W and have a constant cross-sectional shape. Here, the cross-section is a cross section parallel to the facing surface 30a. The metal member 33 and the holding member 34 are exposed on the surface 30a of the polishing pad 30 facing the substrate W, and the metal member 33 and the holding member 34 form the same pattern in multiple cross-sections at different distances from the facing surface 30a.

[0035] When the polishing pad 30 is attached to the second holding part 20, the surface 30a of the polishing pad 30 that faces the substrate W is the lower surface. The metal member 33 and the holding member 34 each extend directly upward from the lower surface of the polishing pad 30 and have a constant horizontal cross-sectional shape. The metal member 33 and the holding member 34 are exposed on the lower surface of the polishing pad 30, and the metal member 33 and the holding member 34 form the same pattern in multiple horizontal cross sections at different heights.

[0036] When the underside of the polishing pad 30 deteriorates due to wear or the adhesion of dirt, the dresser scrapes and smooths the underside of the polishing pad 30, so that the metal member 33 and the holding member 34 are exposed on the underside of the polishing pad 30 in the same pattern as before the deterioration. Thus, the polishing performance of the polishing pad 30 can be restored and stabilized.

[0037] The holding member 34 is preferably formed of resin so as to improve its ability to conform to irregularities on the upper surface of the substrate W. The holding member 34 is also preferably porous so as to temporarily hold the processing liquid at the interface between the polishing pad 30 and the substrate W. The holding member 34 is more preferably formed of foamed resin so as to improve its ability to conform to irregularities on the upper surface of the substrate W and to temporarily hold the processing liquid at the interface between the polishing pad 30 and the substrate W.

[0038] The material of the holding member 34 is not limited to resin, but may be ceramic or the like. However, from the viewpoint of conformability to the irregularities on the upper surface of the substrate W, the material of the holding member 34 is preferably resin. Furthermore, the holding member 34 is not limited to a porous body, but may be a dense body or the like. However, in order to temporarily retain the processing liquid at the interface between the polishing pad 30 and the substrate W, the holding member 34 is preferably a porous body.

[0039] 5, if the hardness of the holding member 34 is too high or too low, the metal member 33 will not be able to conform well to the irregularities on the upper surface of the substrate W. If the hardness of the holding member 34 is appropriate, the entire lower surface of the polishing pad 30 can smoothly deform to conform to the irregularities on the upper surface of the substrate W, and the entire lower surface can be in close contact with the upper surface of the substrate W. From the viewpoint of hardness, the material of the holding member 34 is preferably rigid urethane foam.

[0040] 5, it is preferable that there are a plurality of metal members 33, and that the holding member 34 fills the gaps between the plurality of metal members 33 and holds the plurality of metal members 33 at intervals. The plurality of metal members 33 can be dispersed on the lower surface of the polishing pad 30, and the upper surface of the substrate W can be polished evenly.

[0041] As shown in Figure 6, the cross-sectional shape of the metal member 33 is not particularly limited, but may be a circle (see Figures 6(A) and 6(D)), an ellipse (see Figure 6(C)), or a polygon (see Figure 6(B)). The polygon includes a rectangle. The rectangle includes a square. The polygon may include a triangle, a hexagon, or the like.

[0042] Although not shown, a single polishing pad 30 may include a plurality of metal members 33 with different cross-sectional shapes. Also, although not shown, a single polishing pad 30 may include a plurality of metal members 33 with different cross-sectional sizes. Here, the size of the cross section is expressed by the diameter of a circle, the major axis or minor axis of an ellipse, the length of one side of a polygon, or the like.

[0043] The overall cross-sectional shape of the polishing pad 30 is not particularly limited, but is preferably axially symmetrical about the center line of rotation of the polishing pad 30, and more specifically, is preferably a circular shape (see Figures 6(A), 6(B), and 6(C)) or a donut shape (Figure 6(D)).

[0044] 7, the holding member 34 may be selectively worn and dented compared to the metal member 33. Although not shown, the metal member 33 may be selectively worn and dented compared to the holding member 34. In any case, when the lower surface of the polishing pad 30 deteriorates due to wear or the adhesion of dirt, the dressers 60A and 60B scrape and smooth the lower surface of the polishing pad 30.

[0045] The dresser 60A roughly scrapes the lower surface of the polishing pad 30 to align the height of the lower surface of the holding member 34 and the lower surface of the metal member 33. The dresser 60B finely scrapes the lower surface of the polishing pad 30 to flatten the lower surface of the holding member 34 and the lower surface of the metal member 33. The installation locations of the dressers 60A and 60B are not particularly limited. The number of dressers used may be one or three or more.

[0046] 7, a thickness gauge 61 may measure the thickness of the polishing pad 30. A control circuit 90 performs control to issue an alarm based on the measurement value of the thickness gauge 61. In other words, the control circuit 90 controls the alarm device 100 to issue an alarm based on the measurement value of the thickness gauge 61. For example, if the measurement value of the thickness gauge 61 falls below the threshold, the life of the polishing pad 30 has expired, and the control circuit 90 performs control to issue an alarm. By issuing an alarm, the user can be prompted to replace the polishing pad 30.

[0047] The alarm device 100 that issues an alarm is, for example, a warning light, a buzzer, a display, etc. The alarm device 100 that issues an alarm is a part of the substrate processing apparatus 1, but may be provided separately from the substrate processing apparatus 1, and may be, for example, a mobile terminal.

[0048] 8, the polishing pad 30 may have a discharge port 30b for discharging the treatment liquid on a surface 30a facing the substrate W. The discharge port 30b is preferably provided on the rotation center line of the polishing pad 30. Although not shown, a plurality of discharge ports 30b may be provided rotationally symmetrically around the rotation center line of the polishing pad 30. Discharging the treatment liquid from the discharge port 30b of the polishing pad 30 allows new treatment liquid to be supplied to the interface between the polishing pad 30 and the substrate W.

[0049] 9, the polishing pad 30 may have a second holding member 35 that holds both the metal member 33 and the holding member 34. The second holding member 35 is provided on the opposite side (e.g., the upper side) from the substrate W relative to the metal member 33 and the holding member 34. The second holding member 35 may be formed from the same material as the holding member 34 and may be molded integrally with the holding member 34. The second holding member 35 may also be formed from a material different from that of the holding member.

[0050] 10, the polishing pad 30 may have irregularities on the surface 30a facing the substrate W. The metal member 33 may be recessed relative to the holding member 34. It is sufficient that the metal member 33 and the holding member 34 are exposed on the surface 30a of the polishing pad 30 facing the substrate W, and that the metal member 33 and the holding member 34 form the same pattern in multiple cross sections at different distances from the facing surface 30a.

[0051] Although the embodiments of the polishing pad, substrate processing apparatus, and substrate processing method according to the present disclosure have been described above, the present disclosure is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These naturally fall within the technical scope of the present disclosure.

[0052] This application claims priority based on Japanese Patent Application No. 2024-103361 filed with the Japan Patent Office on June 26, 2024, the entire contents of which are incorporated herein by reference.

[0053] REFERENCE SIGNS LIST 1 substrate processing apparatus 10 first holding unit 15 first rotating unit 25 second rotating unit 30 polishing pad 33 metal member 34 holding member W substrate

Claims

1. A polishing pad for polishing a substrate, comprising: a metal member having a catalyst that generates reactive species from a processing liquid supplied to the substrate that react with the substrate; and a holding member that holds the metal member, wherein the metal member and the holding member each extend perpendicularly from the surface of the polishing pad facing the substrate and have a constant cross-sectional shape.

2. The polishing pad according to claim 1, wherein said retaining member is formed of a resin.

3. The polishing pad of claim 1, wherein the retaining member is porous.

4. The polishing pad according to claim 1, wherein the metal members are plural, and the holding member fills the gaps between the metal members and holds the metal members at intervals.

5. The polishing pad according to claim 1, having a discharge port for discharging the processing liquid on the surface facing the substrate.

6. The polishing pad of claim 1, wherein the treatment liquid comprises water.

7. A substrate processing apparatus comprising: a first holding part that holds a substrate horizontally; a first rotating part that rotates the substrate together with the first holding part; a polishing pad that polishes the upper surface of the substrate; and a second rotating part that rotates the polishing pad, wherein the polishing pad comprises: a metal member having a catalyst that generates reactive species that react with the substrate from a processing liquid supplied to the substrate; and a holding member that holds the metal member, wherein the metal member and the holding member each extend directly upward from the underside of the polishing pad and have a constant horizontal cross-sectional shape.

8. The substrate processing apparatus according to claim 7, wherein the holding member is made of resin.

9. The substrate processing apparatus according to claim 7, wherein the holding member is porous.

10. The substrate processing apparatus according to claim 7, wherein the metal members are plural, and the holding member fills gaps between the plural metal members and holds the plural metal members at intervals.

11. The substrate processing apparatus according to claim 7, wherein the polishing pad has a discharge port on its lower surface for discharging the processing liquid.

12. The substrate processing apparatus of claim 7, wherein the processing liquid includes water.

13. A substrate processing apparatus according to claim 7, comprising: a dresser that scrapes and smooths the underside of the polishing pad; a thickness gauge that measures the thickness of the polishing pad; and a control circuit that controls an alarm device that issues an alarm based on the measurement value of the thickness gauge.

14. A method for processing a substrate, comprising polishing the substrate with the polishing pad according to any one of claims 1 to 6.

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