Polishing method and substrate processing apparatus

Abstract

The present invention provides a polishing method and a substrate processing apparatus that enable effective polishing. [Solution] The polishing method comprises a rotation step of rotating the substrate W in a horizontal position; an etching step of supplying an etching solution to the back surface of the substrate W to remove a film formed on the back surface of the substrate W; and a polishing step of polishing the back surface of the substrate W by chemical mechanical grinding after removing the film from the back surface of the substrate W, by bringing a polishing tool having a resin body in which abrasive particles are dispersed into contact with the back surface of the rotating substrate W. The film is formed in the device manufacturing process. The etching step removes the film so that a portion of the film remains on the back surface of the substrate W.

Description

Technical Field

[0001] The present invention relates to a polishing method for polishing the back surface of a substrate and a substrate processing apparatus. The substrate includes, for example, a semiconductor substrate, a substrate for a FPD (Flat Panel Display), a glass substrate for a photomask, a substrate for an optical disk, a substrate for a magnetic disk, a ceramic substrate, a substrate for a solar cell, and the like. Examples of the FPD include a liquid crystal display device, an organic EL (electroluminescence) display device, and the like. Here, the back surface of the substrate refers to the surface on the side where no electronic circuit is formed with respect to the surface of the substrate (device surface) on the side where the electronic circuit is formed.

Background Art

[0002] A polishing apparatus for polishing the back surface of a substrate includes a polishing head and a holding and rotating unit. The polishing apparatus supplies a polishing liquid, and further, contacts the polishing head with the back surface of the substrate to polish the substrate (see, for example, Patent Document 1). The holding and rotating unit rotates the substrate while holding the substrate in a horizontal posture.

[0003] In addition, as another polishing apparatus, there is a polishing apparatus that performs dry chemo-mechanical grinding (CMG) on a substrate (see, for example, Patent Document 2). This polishing apparatus includes a synthetic grindstone and a holding and rotating unit. The synthetic grindstone is formed by fixing an abrasive (abrasive grains) with a resin binder. This polishing apparatus polishes the substrate by bringing the synthetic grindstone into contact with the substrate. Further, there is a substrate processing apparatus provided with a polishing tool for removing contaminants and contact marks on the back surface of the substrate (see, for example, Patent Document 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

[0005] However, conventional devices with such a configuration have the following problem: In recent years, there has been a problem of defocusing (so-called blurring) in EUV (Extreme Ultraviolet) exposure machines due to the flatness of the substrate on the back surface of the substrate (e.g., wafer). One of the causes of poor flatness is thought to be scratches. Therefore, the use of the synthetic grinding wheel described in Patent Document 2 as a polishing tool has been considered in order to remove scratches. However, it has been found that even when the back surface of the substrate is polished with the polishing tool, the polishing is not always satisfactory.

[0006] This invention has been made in view of these circumstances, and aims to provide a polishing method and a substrate processing apparatus that can perform polishing treatment well. [Means for solving the problem]

[0007] To achieve this objective, the present invention has the following configuration. Specifically, the polishing method according to the present invention comprises a rotation step of rotating a substrate in a horizontal position; an etching step of supplying an etching solution to the back surface of the substrate to remove a film formed on the back surface of the substrate; and a polishing step of, after removing the film on the back surface of the substrate, bringing a polishing tool having a resin body in which abrasive particles are dispersed into contact with the back surface of the rotating substrate and polishing the back surface of the substrate by a chemical mechanical grinding method, wherein the film is formed in the manufacturing process of a device, and the etching step is characterized in that the film is removed such that a portion of the film remains on the back surface of the substrate.

[0008] According to the polishing method of the present invention, a polishing tool is brought into contact with the back surface of a rotating substrate, and the back surface of the substrate is polished by a chemical mechanical polishing method. However, it has been found that if a film is formed on the back surface of the substrate, the polishing cannot be performed properly due to this film. Therefore, an etching process is performed before the polishing process to remove the film so that a portion of the film formed on the back surface of the substrate remains. This allows for a successful polishing process.

[0009] Furthermore, in the polishing method described above, the film comprises a first film and a second film having a different composition from the first film, and the etching step preferably removes the first film such that the second film remains on the back surface of the substrate.

[0010] According to the polishing method of the present invention, a polishing tool is brought into contact with the back surface of a rotating substrate, and the back surface of the substrate is polished by a chemical mechanical polishing method. However, it has been found that if a film is formed on the back surface of the substrate, the polishing cannot be performed properly due to that film. Therefore, an etching process is performed before the polishing process to remove the first film so that a second film formed on the back surface of the substrate remains. This allows for a successful polishing process.

[0011] Furthermore, in the polishing method described above, one example of the etching step is to remove the silicon oxide film, which is the first film.

[0012] Furthermore, in the polishing method described above, one example of the etching step is to remove the silicon nitride film, which is the first film.

[0013] Furthermore, in the polishing method described above, one example of the etching step is to leave the polysilicon film, which is the second film.

[0014] Furthermore, the substrate processing apparatus according to the present invention comprises a holding and rotating unit that rotates the substrate while holding the substrate in a horizontal position, a polishing tool having a resin body in which abrasive particles are dispersed, an etching solution supply nozzle that supplies an etching solution to the back surface of the substrate held by the holding and rotating unit, and a control unit, wherein a film formed in the device manufacturing process is formed on the back surface of the substrate, the control unit supplies an etching solution from the etching solution nozzle to the back surface of the substrate to remove the film so that a part of the film remains on the back surface of the substrate, and after the film has been removed, the control unit brings the polishing tool into contact with the back surface of the substrate which is rotated by the holding and rotating unit, and polishes the back surface of the substrate by a chemical mechanical grinding method.

[0015] According to the substrate processing apparatus of the present invention, a polishing tool is brought into contact with the back surface of a rotating substrate, and the back surface of the substrate is polished by a chemical mechanical polishing method. However, it has been found that if a film is formed on the back surface of the substrate, the polishing cannot be performed properly due to that film. Therefore, an etching process is performed before the polishing process to remove the film so that a portion of the film formed on the back surface of the substrate remains. This allows for a successful polishing process.

[0016] Furthermore, in the substrate processing apparatus described above, the film comprises a first film and a second film having a different composition from the first film, and the control unit removes the first film by supplying an etching solution from the etching solution nozzle to the back surface of the substrate, thereby leaving the second film on the back surface of the substrate. After removing the first film, the control unit preferably brings the polishing tool into contact with the back surface of the substrate, which is rotated by the holding and rotating unit, and polishes the back surface of the substrate by a chemical mechanical grinding method.

[0017] According to the substrate processing apparatus of the present invention, a polishing tool is brought into contact with the back surface of a rotating substrate, and the back surface of the substrate is polished by a chemical mechanical polishing method. However, it has been found that if a film is formed on the back surface of the substrate, the polishing cannot be performed properly due to that film. Therefore, an etching process is performed before the polishing process to remove the first film so that a second film formed on the back surface of the substrate remains. This allows for a successful polishing process.

[0018] Furthermore, this specification also discloses inventions relating to the following polishing methods and substrate processing apparatus.

[0019] Furthermore, it is preferable that the polishing method described above includes a heating step in which the substrate is heated while polishing is being performed. When the substrate is heated, the polishing rate can be increased. Therefore, the polishing time can be shortened.

[0020] Furthermore, it is preferable that the polishing method described above further includes a control step for adjusting the polishing rate by controlling the heating temperature of the substrate in the heating step. The polishing rate can be increased or decreased by raising or lowering the heating temperature of the substrate.

[0021] Furthermore, in the polishing method described above, it is preferable that the control step further adjusts the polishing rate by controlling at least one of the following: the contact pressure of the polishing tool on the substrate, the moving speed of the polishing tool, the rotational speed of the polishing tool, and the rotational speed of the substrate. For example, by increasing the heating temperature of the substrate while maintaining the polishing rate, the contact pressure of the polishing tool on the substrate can be reduced. This reduces the load on the substrate due to the contact pressure, in other words, it is possible to prevent the substrate W from being pressed too hard.

[0022] Furthermore, in the polishing method described above, the etching step is to remove the polysilicon film, which is the second film.

[0023] Further, the above polishing method further includes an inspection step of detecting scratches formed on the back surface of the substrate by an inspection unit before the etching step, and the etching step is preferably executed when the scratches are detected by the inspection unit. Thereby, in the polishing step after the etching step, the detected scratches, that is, the selected scratches can be scraped off.

[0024] Also, in the above polishing method, the inspection step detects the scratches formed on the back surface of the substrate by the inspection unit, measures the depth of the scratches when the scratches are detected, and the etching step is executed when the scratches are detected by the inspection unit. It is preferable that the polishing step polishes the back surface of the substrate until a thickness corresponding to the depth of the scratches measured by the inspection unit is scraped off. Thereby, since the depth of the scratches is recognized, the polishing amount in the thickness direction of the substrate can be made appropriate.

[0025] Further, the above polishing method further includes an inspection step of detecting scratches formed on the back surface of the substrate by an inspection unit between the etching step and the polishing step, and the polishing step is preferably executed when the scratches are detected by the inspection unit. In the polishing step, the scratches detected after the etching step, that is, the selected scratches can be scraped off.

[0026] Also, the above substrate processing apparatus further includes heating means for heating the substrate, and the control unit contacts the polishing tool with the back surface of the substrate that is rotating while being heated after removing the film on the back surface of the substrate, It is preferable to polish the back surface of the substrate by a chemical mechanical polishing method.

Effects of the Invention

[0027] According to the polishing method and the substrate processing apparatus according to the present invention, the polishing process can be performed well.

Brief Description of the Drawings

[0028] [Figure 1] This is a plan view showing the configuration of the substrate processing apparatus according to Example 1. [Figure 2] (a) to (d) are diagrams illustrating the inversion unit. [Figure 3] This is a side view showing the configuration of the polishing unit. [Figure 4] (a) is a plan view showing the configuration of the holding and rotating part, and (b) is a longitudinal cross-sectional view showing a part of the configuration of the holding and rotating part in an enlarged view. [Figure 5] This diagram shows the configuration of the polishing mechanism of the polishing unit. [Figure 6] This is a diagram showing the configuration of the inspection unit. [Figure 7] This is a flowchart showing the operation of the substrate processing apparatus according to Example 1. [Figure 8] (a) is a schematic longitudinal cross-sectional view showing the substrate before the etching process, (b) is a schematic longitudinal cross-sectional view showing the substrate after the etching process (before the back surface polishing process), and (c) is a schematic longitudinal cross-sectional view showing the substrate after the back surface polishing process. [Figure 9] This flowchart shows the details of the wet etching process. [Figure 10] This figure shows the relationship between the heating temperature of the substrate and the polishing rate. [Figure 11] This flowchart shows the details of the circuit board cleaning process. [Figure 12] This is a flowchart showing the operation of the substrate processing apparatus according to Example 2. [Figure 13] This diagram shows the relationship between the heating temperature of the substrate and the contact pressure (pressure) of the polishing tool. [Figure 14] This is a side view showing the configuration of the polishing unit according to Example 4. [Figure 15] This is a side view showing the configuration of the liquid processing unit according to Example 4. [Figure 16] (a) and (b) are diagrams showing heaters for heating abrasive tools. [Figure 17]This diagram shows the relationship between the combination of heating methods and the heating temperature of the substrate. [Example 1]

[0029] Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. Figure 1 is a plan view showing the configuration of the substrate processing apparatus according to Embodiment 1.

[0030] (1) Configuration of substrate processing apparatus Refer to Figure 1. The substrate processing apparatus 1 comprises an indexer block 3 and a processing block 5. Note that a block is also called a region.

[0031] The indexer block 3 comprises multiple (e.g., four) carrier mounting platforms 7 and an indexer robot 9. The four carrier mounting platforms 7 are positioned on the outer surface of the housing 10. Each of the four carrier mounting platforms 7 is used to mount a carrier C. The carrier C houses multiple substrates W. Each substrate W within the carrier C is in a horizontal position with the device surface facing upwards. Carrier C can be, for example, a hoop (FOUP: Front Open Unified Pod), an SMIF (Standard Mechanical Interface) pod, or an open cassette. The substrates W are silicon substrates, formed, for example, in a disc shape.

[0032] The indexer robot 9 retrieves the substrates W from the carriers C placed on each carrier mounting platform 7 and stores the substrates W back into the carriers C. The indexer robot 9 is located inside the housing 10. The indexer robot 9 has two hands 11 (11A, 11B), two articulated arms 13, 14, a lifting platform 15, and a guide rail 16. Each of the two hands 11 holds a substrate W. The first hand 11A is connected to the tip of the articulated arm 13. The second hand 11B is connected to the tip of the articulated arm 14.

[0033] Each of the two articulated arms 13 and 14 is configured, for example, as a SCARA type. The base end of each of the two articulated arms 13 and 14 is attached to a lifting platform 15. The lifting platform 15 is configured to extend and retract in the vertical direction. This allows the two hands 11 and the two articulated arms 13 and 14 to be raised and lowered. The lifting platform 15 is rotatable about a central axis AX1 that extends in the vertical direction. This allows the orientation of the two hands 11 and the two articulated arms 13 and 14 to be changed. The lifting platform 15 of the indexer robot 9 is movable along a guide rail 16 that extends in the Y direction.

[0034] The indexer robot 9 is equipped with multiple electric motors. The indexer robot 9 is driven by multiple electric motors. The indexer robot 9 transports the substrate W between the carrier C placed on each of the four carrier mounting tables 7 and the inversion unit RV, which will be described later.

[0035] The processing block 5 comprises a transport space 18, a substrate transport robot CR, an inversion unit RV, and a plurality (e.g., 8) processing units (processing chambers) U1 to U4. In Figure 1, each processing unit U1 to U4 is composed of, for example, two layers in the vertical direction. Processing unit U1 is an inspection unit 20. Processing units U2, U3, and U4 are polishing units 22. The number and types of processing units can be changed as appropriate.

[0036] The transport space 18 houses the substrate transport robot CR and the inversion unit RV. The inversion unit RV is positioned between the indexer robot 9 and the substrate transport robot CR. Processing units U1 and U3 are arranged side by side in the X direction along the transport space 18. Processing units U2 and U4 are also arranged side by side in the X direction along the transport space 18. The transport space 18 is positioned between processing units U1 and U3 and processing units U2 and U4.

[0037] The substrate transport robot CR is configured in much the same way as the indexer robot 9. That is, the substrate transport robot CR has two hands 24. Other components of the substrate transport robot CR are denoted by the same reference numerals as those of the indexer robot 9. Unlike the lifting platform 15 of the indexer robot 9, the lifting platform 15 of the substrate transport robot CR is fixed to the floor. However, the lifting platform 15 of the substrate transport robot CR may be configured to move in the X direction by having guide rails extending in the X direction. The substrate transport robot CR transports the substrate W between the inversion unit RV and the eight processing units U1 to U4.

[0038] (1-1) Reversal Unit RV Figures 2(a) to 2(d) are diagrams illustrating the inversion unit RV. The inversion unit RV comprises a support member 26, mounting members 28A and 28B, clamping members 30A and 30B, a slide shaft 32, and multiple electric motors (not shown). Mounting members 28A and 28B are provided on the left and right support members 26, respectively. Clamping members 30A and 30B are also provided on the left and right slide shafts 32, respectively. The multiple electric motors drive the support members 26 and the slide shafts 32. The mounting members 28A and 28B and the clamping members 30A and 30B are positioned so as not to interfere with each other.

[0039] Refer to Figure 2(a). Substrates W, transported by, for example, the indexer robot 9, are placed on the mounting members 28A and 28B. Refer to Figure 2(b). The left and right slide axes 32 move closer to each other along the horizontal axis AX2. As a result, the clamping members 30A and 30B clamp the two substrates W. Refer to Figure 2(c). Subsequently, the left and right mounting members 28A and 28B move away from each other as they descend. Then, the clamping members 30A and 30B rotate 180° around the horizontal axis AX2. As a result, each substrate W is inverted.

[0040] Refer to Figure 2(d). Subsequently, the left and right mounting members 28A and 28B rise while moving closer to each other. Then, the left and right sliding shafts 32 move away from each other along the horizontal axis AX2. As a result, the clamping of the two substrates W by the clamping members 30A and 30B is released, and the two substrates W are placed on the mounting members 28A and 28B. In Figures 2(a) to 2(d), the inversion unit RV can invert two substrates W, but the inversion unit RV may be configured to invert three or more substrates W.

[0041] (1-2) Polishing unit 22 Figure 3 shows the polishing unit 22. The polishing unit 22 comprises a holding and rotating part 35, a polishing mechanism 37, and a substrate thickness measuring device 39. The holding and rotating part 35 corresponds to the holding and rotating part of the present invention.

[0042] The holding and rotating unit 35 holds a single substrate W in a horizontal position with its back surface facing upward, and rotates the held substrate W. Here, the back surface of the substrate W refers to the side of the substrate W on which no electronic circuits are formed, as opposed to the surface of the substrate W on which electronic circuits are formed (device surface). The device surface of the substrate W held by the holding and rotating unit 35 is facing downward.

[0043] The holding and rotating section 35 comprises a spin base 41, six holding pins 43, a hot plate 45, and a gas outlet 47. The spin base 41 is formed in a disc shape and is positioned horizontally. A rotation axis AX3 extending in the vertical direction passes through the center of the spin base 41. The spin base 41 is rotatable around the rotation axis AX3.

[0044] Figure 4(a) is a plan view showing the spin base 41 and six retaining pins 43 of the holding and rotating part 35. The six retaining pins 43 are provided on the upper surface of the spin base 41. The six retaining pins 43 are arranged in a ring shape so as to surround the rotation axis AX3. The six retaining pins 43 are also provided at equal intervals on the outer edge side of the spin base 41. The six retaining pins 43 support the substrate W away from the spin base 41 and the hot plate 45, which will be described later. Furthermore, the six retaining pins 43 are configured to clamp the sides of the substrate W. In other words, the six retaining pins 43 can hold the substrate W away from the upper surface of the spin base 41.

[0045] The six retaining pins 43 are divided into three retaining pins 43A that rotate and three retaining pins 43B that do not rotate. The three retaining pins 43A are rotatable around a rotation axis AX4 that extends in the vertical direction. By rotating each retaining pin 43A around the rotation axis AX4, the three retaining pins 43A hold the substrate W and release the held substrate W. The rotation of each retaining pin 43A around the rotation axis AX4 is performed, for example, by magnetic attraction or repulsion by a magnet. The number of retaining pins 43 is not limited to six, but can be three or more. The substrate W may be held by three or more retaining pins 43, including the retaining pins 43A that rotate and the retaining pins 43B that do not rotate.

[0046] A hot plate 45 is provided on the upper surface of the spin base 41. The hot plate 45 contains, for example, an electric heater having a nichrome wire inside. The hot plate 45 is formed in a donut shape and a disc shape. The hot plate 45 heats the substrate W with radiant heat. The hot plate 45 also heats the gas discharged from the gas outlet 47, which will be described later, and heats the substrate W via that gas. The temperature of the substrate W is measured by a non-contact temperature sensor 46. The temperature sensor 46 is equipped with a detection element that detects infrared rays emitted by the substrate W. The hot plate 45 corresponds to the heating means of the present invention. In Example 1, the polishing unit 22 does not have heaters 147 and 154 (see Figure 3), which will be described later.

[0047] A shaft 49 is provided on the lower surface of the spin base 41. The rotation mechanism 51 has an electric motor. The rotation mechanism 51 rotates the shaft 49 around the rotation axis AX3. That is, the rotation mechanism 51 rotates the substrate W, which is held by six retaining pins 43 (specifically three retaining pins 43A) provided on the spin base 41, around the rotation axis AX3.

[0048] Refer to Figures 3 and 4(b). The gas outlet 47 opens onto the upper surface of the spin base 41 and is located in the central part of the spin base 41. A flow path 53 is provided in the center of the spin base 41, with its upper end open. A discharge member 57 is provided in the flow path 53 via a plurality of spacers 55. The gas outlet 47 is composed of a ring-shaped opening formed by the gap between the discharge member 57 and the flow path 53.

[0049] The gas supply pipe 59 is provided so as to pass through the shaft 49 and the rotating mechanism 51 along the rotation axis AX3. The gas piping 61 supplies gas (for example, an inert gas such as nitrogen) from the gas supply source 63 to the gas supply pipe 59. The gas piping 61 is provided with an on-off valve V1. The on-off valve V1 supplies and stops the gas. When the on-off valve V1 is open, gas is discharged from the gas discharge port 47. When the on-off valve V1 is closed, no gas is discharged from the gas discharge port 47. The gas discharge port 47 discharges gas in the gap between the substrate W and the spin base 41 such that the gas flows from the center of the substrate W to the outer edge of the substrate W.

[0050] Next, the configuration for supplying the chemical solution, rinse solution, and gas will be described. The polishing unit 22 is equipped with a first chemical solution nozzle 65, a second chemical solution nozzle 67, a first cleaning solution nozzle 69, a second cleaning solution nozzle 71, a rinse solution nozzle 73, and a gas nozzle 75.

[0051] The first chemical nozzle 65 and the second chemical nozzle 67 correspond to the etching solution supply nozzles of the present invention. Furthermore, the first chemical solution and the second chemical solution, described later, correspond to the etching solutions of the present invention.

[0052] A chemical piping 78 is connected to the first chemical nozzle 65 to supply the first chemical from the first chemical supply source 77. The first chemical is, for example, hydrofluoric acid (HF). A shut-off valve V2 is provided in the chemical piping 78. The shut-off valve V2 controls the supply and cessation of the first chemical. When the shut-off valve V2 is open, the first chemical is supplied from the first chemical nozzle 65. When the shut-off valve V2 is closed, the supply of the first chemical from the first chemical nozzle 65 is stopped.

[0053] A chemical piping 81 is connected to the second chemical nozzle 67 to supply the second chemical from the second chemical supply source 80. The second chemical is, for example, a mixture of hydrofluoric acid (HF) and nitric acid (HNO3), TMAH (tetramethylammonium hydroxide), or diluted hot ammonia water (Hot-dNH4OH). A shut-off valve V3 is provided in the chemical piping 81. The shut-off valve V3 controls the supply and cessation of the second chemical.

[0054] A cleaning fluid piping 84 is connected to the first cleaning fluid nozzle 69 to supply the first cleaning fluid from the first cleaning fluid supply source 83. The first cleaning fluid is, for example, SC2 or SPM. SC2 is a mixture of hydrochloric acid (HCl), hydrogen peroxide (H2O2), and water. SPM is a mixture of sulfuric acid (H2SO4) and hydrogen peroxide solution (H2O2). An on-off valve V4 is provided in the cleaning fluid piping 84. The on-off valve V4 controls the supply and cessation of the first cleaning fluid.

[0055] A cleaning fluid piping 87 is connected to the second cleaning fluid nozzle 71 to supply the second cleaning fluid from the second cleaning fluid supply source 86. The second cleaning fluid is, for example, SC1. SC1 is a mixture of ammonia, hydrogen peroxide (H2O2), and water. An on-off valve V5 is provided in the cleaning fluid piping 87. The on-off valve V5 controls the supply and cessation of the second cleaning fluid.

[0056] A rinse liquid nozzle 73 is connected to a rinse liquid pipe 90 for supplying rinse liquid from a rinse liquid supply source 89. The rinse liquid is, for example, pure water such as DIW (Deionized Water) or carbonated water. A shut-off valve V6 is provided in the rinse liquid pipe 90. The shut-off valve V6 controls the supply and cessation of the rinse liquid.

[0057] A gas nozzle 75 is connected to a gas pipe 93 for supplying gas from a gas supply source 92. The gas is an inert gas such as nitrogen. A shut-off valve V7 is provided in the gas pipe 93. The shut-off valve V7 controls the supply and cessation of the gas.

[0058] The first chemical nozzle 65 is moved horizontally by a nozzle moving mechanism 95. The nozzle moving mechanism 95 is equipped with an electric motor. The nozzle moving mechanism 95 may rotate the first chemical nozzle 65 around a preset vertical axis (not shown). The nozzle moving mechanism 95 may also move the first chemical nozzle 65 in the X and Y directions. The nozzle moving mechanism 95 may also move the first chemical nozzle 65 in the vertical direction (Z direction). Similar to the first chemical nozzle 65, the five nozzles 67, 69, 71, 73, and 75 may each be moved by a nozzle moving mechanism (not shown).

[0059] Next, the configuration of the polishing mechanism 37 will be described. The polishing mechanism 37 polishes the back surface of the substrate W. Figure 5 is a side view showing the polishing mechanism 37. The polishing mechanism 37 comprises a polishing tool 96 and a polishing tool moving mechanism 97. The polishing tool moving mechanism 97 comprises a mounting member 98, a shaft 100, and an arm 101.

[0060] The polishing tool (grinding tool) 96 polishes the back surface of the substrate W using a dry chemical mechanical grinding (CMG) method. The polishing tool 96 is formed in a cylindrical shape. The polishing tool 96 has a resin body in which abrasive grains are dispersed. In other words, the polishing tool 96 is formed by fixing abrasive grains (abrasive material) with a resin binder. As abrasive grains, for example, oxides such as cerium oxide or silica are used. The average particle size of the abrasive grains is preferably 10 μm or less. As the resin body and resin binder, for example, thermosetting resins such as epoxy resin or phenolic resin are used. Alternatively, thermoplastic resins such as ethyl cellulose may be used as the resin body and resin binder. In this case, polishing is performed so as not to soften the thermoplastic resin.

[0061] Here, we will explain chemical mechanical grinding (CMG). CMG is thought to grind according to the following principle: The localized high temperature and high pressure generated near the abrasive grains, such as cerium oxide, upon contact with the workpiece, causes a solid-phase reaction between the abrasive grains and the workpiece, generating silicates. As a result, the surface layer of the workpiece softens, and this softened surface layer is mechanically removed by the abrasive grains. There is also a polishing method called CMP (Chemical Mechanical Polishing). In this method, a slurry solution is supplied to a pad that comes into contact with the workpiece, and the abrasive grains contained in the slurry solution are held in the irregularities on the surface of the pad, thereby performing chemical mechanical polishing. This invention adopts the CMG method.

[0062] The polishing tool 96 is detachably attached to the mounting member 98, for example, by a screw. The mounting member 98 is fixed to the lower end of the shaft 100. A pulley 102 is fixed to the shaft 100. The upper end of the shaft 100 is housed in the arm 101. That is, the polishing tool 96 and the mounting member 98 are attached to the arm 101 via the shaft 100.

[0063] An electric motor 104 and a pulley 106 are arranged inside the arm 101. The pulley 106 is connected to the rotational output shaft of the electric motor 104. A belt 108 is placed over the two pulleys 102 and 106. The electric motor 104 rotates the pulley 106. The rotation of the pulley 106 is transmitted to the pulley 102 and shaft 100 by the belt 108. As a result, the abrasive tool 96 rotates around the vertical axis AX5.

[0064] Furthermore, the polishing tool moving mechanism 97 includes a lifting mechanism 110. The lifting mechanism 110 includes a guide rail 111, an air cylinder 113, and an electro-pneumatic regulator 115. The base end of the arm 101 is connected to the guide rail 111 so as to be able to move up and down. The guide rail 111 guides the arm 101 in the vertical direction. The air cylinder 113 raises and lowers the arm 101. The electro-pneumatic regulator 115 supplies a gas such as air at a pressure set based on an electrical signal from the main control unit 134, which will be described later, to the air cylinder 113. The lifting mechanism 110 may also include a linear actuator driven by an electric motor instead of the air cylinder 113.

[0065] Furthermore, the polishing tool moving mechanism 97 includes an arm rotation mechanism 117. The arm rotation mechanism 117 is equipped with an electric motor. The arm rotation mechanism 117 rotates the arm 101 and the lifting mechanism 110 around the vertical axis AX6. In other words, the arm rotation mechanism 117 rotates the polishing tool 96 around the vertical axis AX6.

[0066] The polishing unit 22 includes a substrate thickness measuring device 39. The substrate thickness measuring device 39 measures the thickness of the substrate W held by the holding and rotating unit 35. The substrate thickness measuring device 39 is configured to irradiate the mirror and the substrate W with light in a wavelength range that is transparent to the substrate W (e.g., 1100 nm to 1900 nm) from a light source through an optical fiber. The substrate thickness measuring device 39 is also configured to detect the reflected light from the mirror, the reflected light reflected from the upper surface of the substrate W, and the reflected light reflected from the lower surface of the substrate W, which are interfered with by a photodetector. The substrate thickness measuring device 39 is configured to generate a spectral interference waveform that shows the relationship between the wavelength and light intensity of the reflected light, and to measure the thickness of the substrate W by waveform analysis of this spectral interference waveform. The substrate thickness measuring device 39 is a known device. The substrate thickness measuring device 39 may be configured to move between a standby position outside the substrate and a measurement position above the substrate W by a moving mechanism (not shown).

[0067] (1-3) Inspection Unit 20 Figure 6 is a side view showing the inspection unit 20. The inspection unit 20 comprises a stage 121, an XY direction movement mechanism 122, a camera 124, illumination 125, a laser scanning confocal microscope 127, a lifting mechanism 128, and an inspection control unit 130.

[0068] The stage 121 supports the substrate W with its back surface facing upward and in a horizontal position. The stage 121 comprises a disc-shaped base member 131 and, for example, six support pins 132. The six support pins 132 are arranged in a ring shape around the central axis AX7 of the base member 131. The six support pins 132 are also arranged at equal intervals in the circumferential direction. With this configuration, the six support pins 132 can support the outer edge of the substrate W while the substrate W is separated from the base member 131. The XY direction movement mechanism 122 moves the stage 121 in the XY direction (horizontal direction). The XY direction movement mechanism 122 comprises, for example, two linear actuators, each driven by an electric motor.

[0069] Camera 124 photographs the back surface of the substrate W. Camera 124 is equipped with an image sensor such as a CCD (charge-coupled device) or CMOS (complementary metal-oxide semiconductor). Illumination 125 irradiates light onto the back surface of the substrate W. This makes it easier to observe, for example, scratches that have occurred on the back surface of the substrate W.

[0070] The laser scanning confocal microscope 127 is hereinafter referred to as "laser microscope 127". The laser microscope 127 comprises a laser light source, an objective lens 127A, an imaging lens, a light sensor, and a confocal optical system having a confocal pinhole. The laser microscope 127 acquires a planar image by scanning the laser light source in the XY direction (horizontal direction). Furthermore, the laser microscope 127 acquires a planar image while moving the objective lens 127A in the Z direction (height direction) relative to the object being observed. As a result, the laser microscope 127 acquires a three-dimensional image (multiple planar images) including the three-dimensional shape. The laser microscope 127 is also referred to as a three-dimensional shape measuring device.

[0071] The laser microscope 127 acquires a three-dimensional image of any scratch that has occurred on the back surface of the substrate W. For example, the control unit, which will be described later, measures the depth of the scratch from the three-dimensional shape of the scratch in the acquired three-dimensional image. The lifting mechanism 128 raises and lowers the laser microscope 127 in the vertical direction (Z direction). The lifting mechanism 128 is composed of a linear actuator driven by an electric motor.

[0072] The inspection control unit 130 comprises one or more processors, such as a central processing unit (CPU), and a storage unit (not shown). The inspection control unit 130 controls each component of the inspection unit 20. The storage unit of the inspection control unit 130 comprises at least one of ROM (Read-only Memory), RAM (Random-Access Memory), and a hard disk. The storage unit of the inspection control unit 130 stores computer programs for operating the inspection unit 20, observation images, scratch extraction results, and three-dimensional images.

[0073] Furthermore, the substrate processing apparatus 1 includes a main control unit 134 and a storage unit (not shown) that are communicatively connected to the inspection control unit 130. The main control unit 134 includes one or more processors, such as a central processing unit (CPU). The main control unit 134 controls each component of the substrate processing apparatus 1. The storage unit of the main control unit 134 includes at least one of ROM (Read-only Memory), RAM (Random-Access Memory), and a hard disk. The storage unit of the main control unit 134 stores computer programs and the like for operating the substrate processing apparatus 1. The main control unit 134 corresponds to the control unit of the present invention.

[0074] (2) Operation of the substrate processing apparatus 1 Next, the operation of the substrate processing apparatus 1 will be explained with reference to Figure 7.

[0075] [Step S01] Removal of substrate W from carrier C A carrier C is placed on a designated carrier mounting table 7. The indexer robot 9 removes a substrate W from the carrier C and transports the removed substrate W to the inversion unit RV. At this time, the device side of the substrate W is facing upwards, and the back side of the substrate W is facing downwards.

[0076] [Step S02] Invert the substrate W. When one or two substrates W are placed on the mounting members 28A and 28B by the indexer robot 9, the inversion unit RV inverts the two substrates W, as shown in Figures 2(a) to 2(d). As a result, the back surfaces of the substrates W are facing upwards.

[0077] The substrate transport robot CR removes the substrate W from the inversion unit RV and transports the substrate W to one of the two inspection units 20. The substrate W, with its back surface facing upwards, is placed on the stage 121 of the inspection unit 20 shown in Figure 6.

[0078] [Step S03] Scratch observation The inspection unit 20 inspects the back surface of the substrate W. The inspection unit 20 detects scratches, particles, and other protrusions. In this embodiment, the case of detecting scratches formed on the back surface of the substrate W will be described in particular.

[0079] In the inspection unit 20 shown in Figure 6, the illumination 125 irradiates light toward the back surface of the substrate W. The camera 124 captures an observation image of the back surface of the substrate W that is illuminated by the light. The camera 124 may perform the imaging while moving the stage 121 on which the substrate W is placed using the XY direction movement mechanism 122. The acquired observation image shows scratches of various sizes. The inspection control unit 130 performs image processing on the observation image and extracts one or more scratches, identifying areas with relatively strong reflected light, i.e., areas with a brightness greater than a preset threshold, as targets for polishing. The inspection control unit 130 may also extract scratches to be polished based on their length.

[0080] Furthermore, when the inspection unit 20 detects a scratch, it measures the depth of the scratch. For example, if multiple scratches are detected (extracted), the inspection unit 20 measures the depth of one or more representative scratches among them. The measurement of scratch depth will now be explained.

[0081] The lifting mechanism 128 (Figure 6) lowers the laser microscope 127 to a preset height. In addition, the XY direction movement mechanism 122 moves the stage 121 so that the scratch to be measured is positioned below the objective lens 127A of the laser microscope 127. The movement of the stage 121 is performed based on the coordinates of the scratch extracted in the observation image. The laser microscope 127 irradiates the scratch (whole or in part) and its surroundings with laser light from the objective lens 127A, while collecting reflected light through the objective lens 127A. As a result, the laser microscope 127 acquires a three-dimensional image including the three-dimensional shape.

[0082] The inspection control unit 130 performs image processing on the three-dimensional image to measure the depth of the scratch. Figure 8(a) is a longitudinal cross-sectional view illustrating the state of the substrate W before the etching process. In Figure 8(a), for example, a thin film such as a silicon oxide film, silicon nitride film, or polysilicon is formed on the back surface of the substrate W. Also, the scratch SH1 on the left side of Figure 8(a) is assumed to have reached the bare silicon BSi. In this case, the inspection control unit 130 measures the depth (value DP1) of the scratch SH1 from the three-dimensional image obtained by the laser microscope 127.

[0083] After observing for scratches and other defects, the substrate transport robot CR transports the substrate W from the stage 121 of the inspection unit 20 to one of the six polishing units 22 (U2 to U4). The substrate W, with its back surface facing upward, is placed on the holding and rotating part 35 of the polishing unit 22. Subsequently, a magnet (not shown) rotates the three holding pins 43A shown in Figure 4(a) around the rotation axis AX4. As a result, the three holding pins 43A hold the substrate W. At this point, the substrate W is held separated from the spin base 41 and the hot plate 45.

[0084] Here, before the next wet etching process, the substrate thickness measuring device 39 measures the thickness of the substrate W. The substrate thickness TK1 is obtained as shown in Figure 8(a).

[0085] [Step S04] Wet etching If thin films such as silicon oxide films, silicon nitride films, or polysilicon films are formed on the back surface of the substrate W, the back surface of the substrate W cannot be properly polished by the polishing tool 96. Some of these films are formed unintentionally during the device manufacturing process, while others are formed intentionally to suppress warping of the substrate W. Therefore, the polishing unit 22 removes the film FL formed on the back surface of the substrate W by supplying a first chemical solution (etching solution) to the back surface of the substrate W.

[0086] Figure 9 is a flowchart illustrating the details of the wet etching process in step S04. First, the silicon oxide film and silicon nitride film are removed (step S21).

[0087] Here, a gas outlet 47 located in the center of the spin base 41 discharges gas. That is, the gas outlet 47 discharges gas in the gap between the substrate W and the spin base 41 so that the gas flows from the center of the substrate W to the outer edge of the substrate. The device surface of the substrate W faces the spin base 41. When gas is discharged from the gas outlet 47, the gas is ejected to the outside from the gap between the outer edge of the substrate W and the spin base 41. This prevents liquids such as polishing debris and the first chemical solution from adhering to the device surface of the substrate W. In other words, the device surface can be protected. Also, due to the Bernoulli effect, a force acts to attract the substrate W to the spin base 41.

[0088] The nozzle moving mechanism 95 moves the first chemical nozzle 65 from a standby position outside the substrate to any processing position above the substrate W. The holding and rotating unit 35 rotates the substrate W while holding it in a horizontal position. Then, the first chemical solution (e.g., hydrofluoric acid) is supplied from the first chemical nozzle 65 to the back surface of the rotating substrate W. This makes it possible to remove the silicon oxide film and silicon nitride film formed on the back surface of the substrate W.

[0089] The first chemical solution may be supplied while the first chemical solution nozzle 65 is moved horizontally. After the supply of the first chemical solution from the first chemical solution nozzle 65 is stopped, the first chemical solution nozzle 65 is moved to a standby position outside the substrate.

[0090] Subsequently, a rinsing process is performed (step S22). That is, a rinsing liquid (for example, DIW or carbonated water) is supplied from the rinsing liquid nozzle 73 to the center of the rotating substrate W. This washes away any remaining first chemical solution on the back surface of the substrate W. Then, a drying process is performed (step S23). That is, the supply of rinsing liquid from the rinsing liquid nozzle 73 is stopped. The holding and rotating unit 35 then rotates the substrate W at high speed to dry it. At this time, gas may be supplied to the back surface of the substrate W from a gas nozzle 75 that has been moved above the substrate W. Note that the drying process may also be performed by supplying gas from the gas nozzle 75 without rotating the substrate W at high speed.

[0091] After steps S21 to S23, a polysilicon film removal process is performed (step S24). The second chemical nozzle 67 is moved from a standby position outside the substrate to an arbitrary processing position above the substrate W. The holding and rotating unit 35 rotates the substrate W at a preset rotation speed. Then, the second chemical solution (for example, a mixture of hydrofluoric acid (HF) and nitric acid (HNO3)) is supplied from the second chemical nozzle 67 to the back surface of the rotating substrate W. This makes it possible to remove the polysilicon film formed on the back surface of the substrate W.

[0092] The second chemical solution may be supplied while moving the second chemical solution nozzle 67 horizontally. After stopping the supply of the second chemical solution from the second chemical solution nozzle 67, the second chemical solution nozzle 67 is moved to a standby position outside the substrate.

[0093] Subsequently, a rinsing process (step S25) is performed, similar to that in the case of the first chemical solution (steps S22, S23), followed by a drying process (step S26). The holding and rotating unit 35 stops the rotation of the substrate W.

[0094] [Step S05] Polishing of the back surface of the substrate W After the wet etching process, the polishing unit 22 polishes the back surface of the substrate W. This polishing is performed when the inspection unit 20 detects scratches on the back surface of the substrate W. This will be explained in detail.

[0095] The holding and rotating section 35 rotates the substrate W while holding it in a horizontal position. The arm rotation mechanism 117 (Figure 5) of the polishing mechanism 37 rotates the polishing tool 96 and the arm 101 around the vertical axis AX6. This moves the polishing tool 96 from a standby position outside the substrate to a preset position above the substrate W. In addition, the electric motor 104 of the polishing mechanism 37 rotates the polishing tool 96 around the vertical axis AX5 (shaft 100).

[0096] Furthermore, the hot plate 45 generates heat when power is applied to heat the substrate W. The temperature of the substrate W is monitored by a non-contact temperature sensor 46. The main control unit 134 adjusts the heat generated by the hot plate 45 based on the temperature of the substrate W detected by the temperature sensor 46. The heating temperature of the substrate W is adjusted to a temperature higher than room temperature (e.g., 25°C) in order to obtain a high polishing rate. However, it is preferable to adjust it to 100°C or lower to avoid thermal degradation of the polishing tool 96.

[0097] Subsequently, the electro-pneumatic regulator 115 supplies pressure-controlled gas based on an electrical signal to the air cylinder 113. This causes the air cylinder 113 to lower the polishing tool 96 and arm 101, bringing the polishing tool 96 into contact with the back surface of the substrate W. The polishing tool 96 is pressed against the back surface of the substrate W with a preset contact pressure. This performs the polishing. When polishing is performed, the arm rotation mechanism 117 (Figure 5) of the polishing mechanism 37 oscillates the polishing tool 96 and arm 101 around the vertical axis AX6. That is, the polishing tool 96 repeatedly reciprocates, for example, between a central position and an outer edge position on the back surface of the substrate W.

[0098] Regarding the amount of polishing in the thickness direction (Z direction) of the substrate W, it seems that polishing is unnecessary if the substrate W meets a predetermined flatness even if scratches are present. However, the edges of the scratches may create new scratches on, for example, the exposure machine stage. Therefore, polishing is carried out until scratches of a predetermined size are removed.

[0099] As shown in Figure 8(a), the depth of the scratch SH1 (value DP1) was obtained by the laser microscope 127. Therefore, the polishing unit 22 polishes the back surface of the substrate W until a thickness corresponding to the depth of the scratch SH1 (value DP1) measured by the laser microscope 127 is removed. The thickness corresponding to the depth of the scratch SH1 is value DP1. Polishing is performed until the thickness of the substrate W reaches value TK2 (=TK1-DP1). The thickness of the substrate W is measured periodically by the substrate thickness measuring device 39. The main control unit 134 compares the measured value of the substrate thickness with a target value (e.g., value TK2) and controls the unit to continue polishing if the measured value has not reached the target value.

[0100] Figure 8(b) shows the state after the etching process (step S04). When the film FL is removed by the etching process, the depth of the scratch SH1 becomes shallower. Therefore, although the amount of polishing in the vertical direction decreases, the substrate W is still polished to a thickness of value TK2. Figure 8(c) shows the state after the polishing process (step S05). Note that the scratch SH2 shown in Figure 8(a) does not reach the bare silicon. Such scratches are removed along with the film FL, such as a silicon oxide film.

[0101] The substrate W is heated by a hot plate 45. Figure 10 shows the relationship between the heating temperature of the substrate W and the polishing rate. The contact pressure of the polishing tool 96 and the rotation speed of the substrate W are constant. Here, for example, if the temperature TM2 of the substrate W is increased compared to when the substrate W is at room temperature (e.g., 25°C), the polishing rate will increase. Therefore, by heating the substrate W with the hot plate 45, the polishing rate can be increased. As a result, the polishing time can be shortened.

[0102] The polishing unit 22 may adjust the polishing rate by controlling the heating temperature of the substrate W using the hot plate 45 when performing polishing. The polishing rate can be increased or decreased by raising or lowering the heating temperature of the substrate W. The polishing rate may be adjusted before polishing or during polishing. For example, by changing the temperature of the substrate W between the center and the outer edge of the substrate W, the polishing rate can be made different between the center and the outer edge of the substrate W. The polishing tool 96 is then moved to a standby position on the substrate W.

[0103] [Step S06] Cleaning of substrate W After polishing the back surface of the substrate W, the back surface of the substrate W is cleaned. This removes any remaining polishing debris on the back surface of the substrate W, as well as metal, organic matter, and particles. Figure 11 is a flowchart detailing the cleaning process in step S06.

[0104] First, a first cleaning solution is supplied to the back surface of the substrate W (step S31). This will be explained in detail. The holding and rotating unit 35 continues to hold the substrate W. The holding and rotating unit 35 also continues to protect the device surface of the substrate W by discharging gas from the gas discharge port 47. The first cleaning solution nozzle 69 is moved from a standby position outside the substrate to an arbitrary processing position above the substrate W. The holding and rotating unit 35 rotates the substrate W. Then, the first cleaning solution (e.g., SC2 or SPM) is supplied from the first cleaning solution nozzle 69 to the back surface of the rotating substrate W. The first cleaning solution may be supplied while the first cleaning solution nozzle 69 is moved horizontally.

[0105] After the first cleaning solution is supplied and the cleaning process is performed, a rinsing process is carried out (step S32). That is, the rinsing solution (DIW or carbonated water) is supplied from the rinsing solution nozzle 73 to the center of the rotating substrate W. This washes away any remaining first cleaning solution on the back surface of the substrate W. After that, a drying process is carried out (step S33). That is, the supply of rinsing solution from the rinsing solution nozzle 73 is stopped. The holding and rotating unit 35 then dries the substrate W by rotating it at high speed. At this time, gas may be supplied to the back surface of the substrate W from a gas nozzle 75 that has been moved above the substrate W. Note that the drying process may also be carried out by supplying gas from the gas nozzle 75 without rotating the substrate W at high speed.

[0106] After steps S31 to S33, the second cleaning solution is supplied (step S34). That is, the second cleaning solution nozzle 71 is moved from a standby position outside the substrate to an arbitrary processing position above the substrate W. The holding and rotating unit 35 rotates the substrate W at a preset rotation speed. Then, the second cleaning solution (e.g., SC1) is supplied from the second cleaning solution nozzle 71 to the back surface of the rotating substrate W.

[0107] The second cleaning solution may be supplied while moving the second cleaning solution nozzle 71 horizontally. After stopping the supply of the second cleaning solution from the second cleaning solution nozzle 71, the second cleaning solution nozzle 71 is moved to a standby position outside the substrate.

[0108] Subsequently, a rinsing process (step S35) is performed, similar to that in the case of the first cleaning solution (steps S32, S33), followed by a drying process (step S36). The holding and rotating unit 35 stops the rotation of the substrate W. Since the polishing unit 22 in this embodiment has a cleaning function, the substrate W, from which the polishing debris has been cleaned, can be discharged from the polishing unit 22.

[0109] [Step S07] Reversal of substrate W The substrate transport robot CR removes the substrate W from the polishing unit 22 and transports the substrate to the inversion unit RV. At this time, the back surface of the substrate W is facing upwards, and the device surface of the substrate W is facing downwards. Once one or two substrates W are placed on the mounting members 28A and 28B by the substrate transport robot CR, the inversion unit RV inverts the two substrates W, as shown in Figures 2(a) to 2(d). As a result, the back surface of the substrate W is facing downwards.

[0110] [Step S08] Storage of the circuit board W into the carrier C The indexer robot 9 removes the substrate W from the inversion unit RV and returns the substrate W to the carrier C.

[0111] In this embodiment, the polishing unit 22 comprises a holding and rotating section 35, a hot plate 45 (heating means), and a polishing tool 96. The polishing tool 96 contacts the back surface of the rotating substrate W and polishes the back surface of the substrate W using a chemical mechanical grinding (CMG) method. During this polishing, the substrate W is heated by the hot plate 45. When the substrate W is heated, the polishing rate can be increased (see Figure 10). Therefore, the polishing time can be shortened.

[0112] Furthermore, the inspection unit 20, which inspects the substrate W, detects scratches formed on the back surface of the substrate W before polishing the back surface of the substrate W. When a scratch is detected, the inspection unit 20 polishes the back surface of the substrate W. This allows the detected scratch, i.e., the selected scratch, to be scraped off.

[0113] Furthermore, the inspection unit 20 measures the depth of a scratch when it is detected. The polishing unit 22 polishes the back surface of the substrate W until a thickness corresponding to the scratch depth measured by the inspection unit 20 is removed. This allows the depth of the scratch to be recognized, enabling the amount of polishing in the thickness direction of the substrate W to be adjusted appropriately.

[0114] According to the substrate processing apparatus 1, a polishing tool 96 is brought into contact with the back surface of a rotating substrate W, and the back surface of the substrate W is polished by a chemical mechanical polishing (CMG) method. However, it was found that if a film FL is formed on the back surface of the substrate W, the polishing cannot be performed properly due to this film FL. Therefore, an etching process is performed before the polishing process to remove the film FL formed on the back surface of the substrate W. This allows the polishing process to be performed properly. [Example 2]

[0115] Next, Embodiment 2 of the present invention will be described with reference to the drawings. Note that explanations that overlap with those in Embodiment 1 will be omitted. Figure 12 is a flowchart showing the operation of the substrate processing apparatus according to Embodiment 2.

[0116] In Example 1, scratch observation was not performed after the back surface of the substrate W was polished (step S05). In contrast, in Example 2, scratch observation was performed after polishing (step S51 in Figure 12).

[0117] Steps S01 to S08 shown in Figure 12 are substantially the same as steps S01 to S08 shown in Figure 7. After the substrate cleaning process (step S06), the substrate transport robot CR removes the substrate W from the polishing unit 22 and transports the substrate W to one of the two inspection units 20, stage 121.

[0118] [Step S51] Observation of scratches after polishing The inspection unit 20 specifically re-detects scratches formed on the back surface of the substrate W. That is, similar to the operation in step S03, the inspection unit 20 acquires observation images using the camera 124 and illumination 125. The inspection control unit 130 performs image processing on the acquired observation images to extract scratches to be polished. If scratches to be polished cannot be extracted, the main control unit 134 determines that re-polishing is not necessary and proceeds to step S07.

[0119] In response, when a scratch to be polished is detected, the main control unit 134 determines that repolishing is necessary. The inspection unit 20 then measures the depth of the scratch to be polished. That is, the laser microscope 127 acquires a three-dimensional image including the scratch to be polished. The inspection control unit 130 performs image processing on the acquired three-dimensional image to measure the depth of the scratch to be polished (value DP3 in Figure 8(b)).

[0120] Subsequently, the substrate transport robot CR transports the substrate W from the stage 121 of the inspection unit 20 to the holding and rotating section 35 of the polishing unit 22. After transport, the substrate W is held by the holding and rotating section 35, and gas is discharged from the gas outlet 47. Then, the substrate thickness measuring device 39 is moved above the substrate W and measures the thickness of the substrate W (value TK3 in Figure 8(b)). The process returns to step S05.

[0121] In step S05, if the inspection unit 20 has identified a scratch to be polished, the polishing unit 22 performs backside polishing of the substrate W again. Polishing is carried out until a thickness (value DP3) corresponding to the depth of the scratch is removed. In other words, polishing is carried out until the thickness of the substrate W reaches the value TK2 (=TK3-DP3) shown in Figure 8(b).

[0122] According to this embodiment, polishing is performed until all scratches on the object to be polished are gone, thus preventing the edges of the scratches from creating new scratches on, for example, the stage of an exposure machine.

[0123] Furthermore, in this embodiment, if scratches are present on the surface to be polished, the wet etching process (step S04) is not performed. However, wet etching may be performed if necessary. [Example 3]

[0124] Next, Embodiment 3 of the present invention will be described with reference to the drawings. Note that explanations that overlap with Embodiments 1 and 2 will be omitted.

[0125] Figure 13 shows the relationship between the heating temperature of the substrate W and the contact pressure (pressing pressure) of the polishing tool 96. Figure 13 shows the case when the polishing rate is kept constant. In Figure 13, assume that a predetermined polishing rate RA is obtained when the temperature of the substrate W is at room temperature (e.g., 25°C) and the contact pressure P1 is predetermined. When the substrate W is heated, the polishing rate increases. Therefore, if the temperature is raised above room temperature (e.g., to temperature TM2) while maintaining the polishing rate RA, a contact pressure P2 lower than the contact pressure P1 can be achieved. In other words, when the polishing rate RA is constant, the contact pressure can be lowered by raising the temperature of the substrate W.

[0126] According to this embodiment, the polishing unit 22 can adjust the polishing rate by controlling the contact pressure of the polishing tool 96 against the substrate W, in addition to the heating temperature of the substrate W. For example, by increasing the heating temperature of the substrate W while maintaining the polishing rate, the contact pressure of the polishing tool 96 against the substrate W can be reduced. This reduces the load on the substrate W due to the contact pressure, thus preventing excessive pressure on the substrate W.

[0127] Furthermore, the polishing rate may not be adjusted based on the relationship between the heating temperature of the substrate W and the contact pressure of the polishing tool 96. In other words, the polishing rate may be adjusted based on the relationship between the heating temperature of the substrate W and the movement speed of the polishing tool 96. The polishing rate may also be adjusted based on the relationship between the heating temperature of the substrate W and the movement speed (oscillation speed) of the polishing tool 96 around the vertical axis AX6. The polishing rate may also be adjusted based on the relationship between the heating temperature of the substrate W and the rotation speed of the polishing tool 96 around the vertical axis AX5. The polishing rate may also be adjusted based on the relationship between the heating temperature of the substrate W and the rotation speed of the substrate W.

[0128] In other words, the polishing unit 22 may adjust the polishing rate by controlling, in addition to the heating temperature of the substrate W, at least one of the following: the contact pressure of the polishing tool 96 on the substrate W, the moving speed of the polishing tool 96, the rotational speed of the polishing tool 96, and the rotational speed of the substrate W. [Example 4]

[0129] Next, Embodiment 4 of the present invention will be described with reference to the drawings. Note that explanations that overlap with Embodiments 1 to 3 will be omitted.

[0130] In Figure 1, in Example 1, processing unit U1 is inspection unit 20, and processing units U2 to U4 are polishing units 22. In Example 4, processing units U2 and U3 are polishing units 141, and processing unit U4 may be liquid processing unit 143. Processing unit U1 is inspection unit 20.

[0131] In other words, the substrate processing apparatus 1 of Example 4 comprises a two-layer inspection unit 20, a two-layer polishing unit 141, and a two-layer liquid treatment unit 143. To put it another way, the substrate processing apparatus 1 comprises eight treatment units U1 to U4. Figure 14 shows the polishing unit 141 according to Example 4. Figure 15 shows the liquid treatment unit 143 according to Example 4.

[0132] The polishing unit 141 and the liquid treatment unit 143 are configured as two separate components of the polishing unit 22 shown in Figure 3. The liquid treatment unit 143 includes a second holding and rotating part 145 configured similarly to the holding and rotating part 35. The polishing unit 141 may also include a rinsing liquid nozzle 73, a rinsing liquid supply source 89, and a rinsing liquid piping 90. The polishing units 22 and 141 correspond to the polishing units of the present invention.

[0133] The operation of the substrate processing apparatus 1 is carried out according to the flowchart shown in Figure 7 or Figure 12. However, for example, the substrate W is transported between the polishing unit 141 and the liquid treatment unit 143. For example, between steps S03 to S06 in Figure 7, the substrate W is transported by the substrate transport robot CR in the following order: inspection unit 20, liquid treatment unit 143 (wet etching process), polishing unit 141, and liquid treatment unit 143 (surface cleaning process for substrate W).

[0134] This embodiment provides the same effects as in Embodiment 1. Furthermore, since the configuration of the polishing unit 22 in Figure 2 is divided into two parts, the polishing unit 141 and the liquid treatment unit 143 can each be made compact.

[0135] Furthermore, the configuration for the wet etching process (step S04) of the liquid treatment unit 143 may be provided in the polishing unit 141. Also, the configuration for the substrate cleaning process (step S06) of the liquid treatment unit 143 may be provided in the polishing unit 141. In addition, in Example 4, the polishing unit 141 does not include the heaters 147 and 154 (see Figure 14), which will be described later.

[0136] The present invention is not limited to the embodiments described above, and can be modified and implemented as follows.

[0137] (1) In each of the embodiments described above, the polishing unit 22 is equipped with a hot plate 45 as a heating means. The polishing unit 22 may be configured to discharge heated gas from a gas outlet 47 instead of the hot plate 45. The substrate can be heated by the heated gas from the gas outlet 47. In this case, for example, the polishing unit 22 may be equipped with a heater 147 (see Figures 3 and 14) that heats the gas passing through the gas pipe 61 from the outside of the gas pipe 61. In this case, the polishing unit 22 does not need to be equipped with a hot plate 45. The substrate W may also be heated by both the hot plate 45 and the heated gas discharged from the gas outlet 47. The gas outlet 47 corresponds to the heating means of the present invention.

[0138] (2) In each of the embodiments and modification (1) described above, the polishing unit 22 is equipped with a hot plate 45 as a heating means. In this regard, as shown in Figures 16(a) and 16(b), the polishing unit 22 may be equipped with a heater 149 (152) for heating the polishing tool 96 instead of the hot plate 45. Alternatively, the polishing unit 22 may be equipped with a hot plate 45 and a heater 149 (152). In Figure 16(a), the mounting member 98 is configured like a container with a recessed bottom surface. A ring-shaped heater 149 is provided in the hollow cylindrical portion 150 surrounding the polishing tool 96 (vertical axis AX5) of the mounting member 98. The heater 149 heats the polishing tool 96. When the polishing tool 96 is heated, the substrate W can be heated via the polishing tool 96. In addition, the interface between the polishing tool 96 and the back surface of the substrate W can be effectively heated.

[0139] Furthermore, as shown in Figure 16(b), the heater 152 may be built into the mounting member 98 and positioned between the shaft 100 and the polishing tool 96. Each heater 149, 152 may be heated by an electric heater, such as a nichrome wire. Alternatively, each heater 149, 152 may be heated by passing a heated gas or heated liquid through piping. Each heater 149, 152 corresponds to the heating means of the present invention.

[0140] (3) In each of the embodiments and modifications described above, the back surface of the substrate W was polished using a dry chemical mechanical grinding method with the polishing tool 96. However, the back surface of the substrate W may also be polished using a chemical mechanical grinding method while supplying liquid onto the back surface of the substrate W with the polishing tool 96. For example, heated pure water (e.g., DIW) may be supplied from a rinsing liquid nozzle 73 (Figures 3 and 14) onto the back surface of the substrate W and near the polishing tool 96. The heated pure water can heat the substrate W. Also, the heated pure water can wash away polishing debris from the back surface of the substrate W. For example, the polishing unit 22 (141) may be equipped with a heater 154 that heats the pure water passing through the rinsing liquid pipe 90 from the outside of the rinsing liquid pipe 90. Alternatively, the substrate W may be heated by heated pure water from the rinsing liquid nozzle 73 without using the hot plate 45. In this case, the polishing unit 22 does not need to be equipped with the hot plate 45. The rinsing liquid nozzle 73 corresponds to the heating means of the present invention.

[0141] The substrate W may also be heated by at least one of the following: a hot plate 45, a gas outlet 47 for discharging heated gas, a heater 149 (or heater 152) for heating the polishing tool 96, and a rinsing liquid nozzle 73 for supplying heated pure water to the back surface of the substrate W.

[0142] Furthermore, the polishing unit 22 may be equipped with these heating means and the heating temperature of the substrate W may be controlled by combining the heating means. For example, suppose heating is performed only by the hot plate 45 (symbol H1 in Figure 17). If further heating is desired, the substrate W may be heated by the gas outlet 47 that discharges heated gas in addition to the hot plate 45 (symbol H1 + symbol H2 in Figure 17). If further heating is desired, the substrate W may be heated by the heater 149 (or heater 152) that heats the polishing tool 96 in addition to the hot plate 45 and the gas outlet 47 (symbol H1 + symbol H2 + symbol H3 in Figure 17). If heating is to be reduced from this state, the substrate W may be heated only by the hot plate 45 (symbol H1).

[0143] (4) In each of the embodiments and modifications described above, the substrate thickness measuring device 39 measured the thickness of the substrate W before the wet etching process (step S04). In this case, the substrate thickness measuring device 39 may measure the thickness of the substrate W between step S04 and the back surface polishing process of the substrate W (step S05). In this case, the scratch observation process (step S03) may be moved between steps S04 and S05.

[0144] (5) In each of the embodiments and modifications described above, the polishing unit 22 and the main control unit 134 were provided in the substrate processing apparatus 1 together with the indexer block 3, etc. However, the polishing unit 22 and the main control unit 134 may be provided in the polishing apparatus.

[0145] (6) In each of the embodiments and modifications described above, the contact pressure of the polishing tool 96 with respect to the substrate W may be detected, for example, by a load cell. The moving speed of the polishing tool 96 may be detected by a rotary encoder that detects the angle of the polishing tool 96 around the vertical axis AX6. The rotational speed of the polishing tool 96 may be detected by a rotary encoder that detects the angle of the polishing tool 96 around the vertical axis AX5. The rotational speed of the substrate W may be detected by a rotary encoder that detects the angle of the substrate W around the rotation axis AX3. The main control unit 134 may control each of the components based on these detection results.

[0146] (7) In each of the embodiments and modifications described above, the holding and rotating part 35 held the substrate W with its back surface facing upward in a horizontal position. The spin base 41 of the holding and rotating part 35 was positioned below the substrate W. In this respect, the holding and rotating part 35 may be positioned upside down. That is, the spin base 41 of the holding and rotating part 35 is positioned above the substrate W. The holding and rotating part 35 also holds the substrate W with its back surface facing downward in a horizontal position. In this case, the polishing tool 96 is brought into contact with the substrate W with its back surface facing downward from below the substrate W.

[0147] (8) In each of the above-described embodiments and modifications, steps S21 to S26 were performed as a wet etching process (Figure 9). Of the six steps S21 to S26, only steps S21 to S23 may be performed. Alternatively, of the six steps S21 to S26, only steps S24 to S26 may be performed.

[0148] (9) In each of the embodiments and modifications described above, steps S31 to S36 were performed as a cleaning process for the substrate W (Figure 11). Of the six steps S31 to S36, only steps S31 to S33 may be performed. Alternatively, of the six steps S31 to S36, only steps S34 to S36 may be performed. [Explanation of Symbols]

[0149] 1 ... Substrate processing equipment 20… Inspection unit 22,141 ... Polishing unit 35 ... Holding and rotating part 37 … Polishing mechanism 41… Spin base 43… Retaining pin 45… Hot plate 47… Gas outlet 65 ... First chemical solution nozzle 67 ... Second chemical solution nozzle 73… Rinse solution nozzle 96 … Polishing tools 117... Arm rotation mechanism 127 … Laser scanning confocal microscope 130 ... Inspection and Control Unit 134 ... Main control unit 145 ... Second holding and rotating part 147, 149, 152, 154 ... Heater

Claims

1. A rotation process in which the substrate is rotated in a horizontal position, An etching step is performed by supplying an etching solution to the back surface of the substrate to remove a film formed on the back surface of the substrate. The process includes a polishing step in which, after removing the film on the back surface of the substrate, a polishing tool having a resin body in which abrasive particles are dispersed is brought into contact with the back surface of the rotating substrate, and the back surface of the substrate is polished by a chemical mechanical grinding method. The aforementioned film is formed in the device manufacturing process, The etching step is a polishing method characterized by removing the film such that a portion of the film remains on the back surface of the substrate.

2. In the polishing method described in claim 1, The film comprises a first film and a second film having a different composition from the first film. The etching step is a polishing method characterized by removing the first film such that the second film remains on the back surface of the substrate.

3. In the polishing method described in claim 2, The polishing method is characterized in that the etching step removes the silicon oxide film, which is the first film.

4. In the polishing method according to claim 2 or 3, The polishing method is characterized in that the etching step removes the silicon nitride film, which is the first film.

5. In the polishing method according to any one of claims 2 to 4, The polishing method is characterized in that the etching step leaves the polysilicon film, which is the second film, intact.

6. A holding and rotating unit that rotates the substrate while holding it in a horizontal position, A polishing tool having a resin body in which abrasive particles are dispersed, An etching solution supply nozzle for supplying etching solution to the back surface of the substrate held by the holding and rotating part, It comprises a control unit and, A film formed in the device manufacturing process is formed on the back surface of the substrate. The control unit supplies etching solution from the etching solution nozzle to the back surface of the substrate, thereby removing the film so that a portion of the film remains on the back surface of the substrate. The substrate processing apparatus is characterized in that, after removing the film, the control unit brings the polishing tool into contact with the back surface of the substrate, which is rotated by the holding and rotating unit, and polishes the back surface of the substrate by a chemical mechanical grinding method.

7. In the substrate processing apparatus according to claim 6, The film comprises a first film and a second film having a different composition from the first film. The control unit removes the first film by supplying etching solution from the etching solution nozzle to the back surface of the substrate, so that the second film remains on the back surface of the substrate. The substrate processing apparatus is characterized in that, after removing the first film, the control unit brings the polishing tool into contact with the back surface of the substrate, which is rotated by the holding and rotating unit, and polishes the back surface of the substrate by a chemical mechanical grinding method.

Images