Substrate processing method and substrate processing apparatus

Abstract

To suppress the consumption of a processing liquid and process a substrate satisfactorily in a technique for processing the substrate using the processing liquid.SOLUTION: A substrate processing method according to the present invention includes the steps of holding a substrate in a horizontal position, supplying a processing liquid to the upper surface of the substrate, rotating the substrate around a vertical axis to form a liquid film of the processing liquid on the upper surface of the substrate, detecting the film thickness of the liquid film, and arranging a plasma generation source so as to face the upper surface of the substrate and irradiating the liquid film with plasma from the plasma generation source when the detection result of the film thickness is a predetermined target value.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a technique for processing a substrate using a processing liquid, and more particularly to a substrate processing method and a substrate processing apparatus for removing a resist film on the surface of a substrate with a processing liquid.

Background Art

[0002] For the purpose of surface treatment of various substrates such as semiconductor substrates and glass substrates, it is widely practiced to process the substrate with a processing liquid. For example, in the process of stripping and removing a resist film formed on the surface of a semiconductor substrate, a mixed solution of concentrated sulfuric acid and hydrogen peroxide water (sulfuric acid hydrogen peroxide water, Sulfuric Acid Hydrogen Peroxide Mixture; SPM) is used as the processing liquid. For example, in the technique described in Patent Document 1, the substrate is held in a horizontal posture and rotated at a predetermined speed, and sulfuric acid hydrogen peroxide water is discharged from a nozzle disposed above it.

[0003] The inventor of the present application has obtained the finding that the stripping efficiency of the resist film is improved by allowing active species generated by a plasma generation source to act on the processing liquid in the process of stripping and removing the resist film. As a result of research, it has been confirmed that the resist film can be stripped and removed even when sulfuric acid is used instead of the mixed solution of concentrated sulfuric acid and hydrogen peroxide water as the processing liquid. This is presumably because the active species generated by the plasma generation source act on sulfuric acid to generate perchloric acid having a resist film removing action.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When the inventors of the present application caused active species generated by a plasma generation source to act on various treatment liquids including sulfuric acid, it was found that the stripping efficiency of the resist film was greatly affected by the film thickness of the liquid formed on the resist film. Since the resist film formed on the substrate has a wide variety of surface shapes and properties depending on the type of resist, the substrate treatment process, the shape of the circuit pattern formed on the substrate, etc., it is difficult to always keep the film thickness of the treatment liquid formed on the resist film constant. Even if the irradiation state of the plasma generation source on the treatment liquid on the substrate is kept constant, if the film thickness of the treatment liquid is different from the intended film thickness, the stripping result of the resist film will vary.

[0006] From these facts, it is desired to establish a technique for controlling the process of performing plasma irradiation on the liquid film of the treatment liquid on the substrate from the plasma generation source so as to obtain a desired result.

[0007] This invention has been made in view of the above problems, and an object thereof is to provide a technique capable of stabilizing the treatment of a treatment liquid and further optimizing the treatment in a technique for treating a substrate using the treatment liquid.

Means for Solving the Problems

[0008] In an aspect of the substrate processing method according to the present invention 1st In order to achieve the above object, a step of holding the substrate in a horizontal posture, a step of supplying a treatment liquid to the upper surface of the substrate and rotating the substrate around a vertical axis to form a liquid film of the treatment liquid on the upper surface of the substrate, a step of detecting the film thickness of the liquid film, and when the detection result of the film thickness is a predetermined target value, arranging a plasma generation source facing the upper surface of the substrate, and performing plasma irradiation on the liquid film from the plasma generation source. 、The plasma generation source faces a reactor having a planar size equal to or larger than the planar size of the substrate to the upper surface of the substrate, and performs the plasma irradiation with the rotation of the substrate stopped. 。 Moreover, a second aspect of the substrate processing method according to the present invention is, in order to achieve the above object, a step of holding the substrate in a horizontal posture, a step of supplying a processing liquid to the upper surface of the substrate and rotating the substrate about a vertical axis to form a liquid film of the processing liquid on the upper surface of the substrate, a step of detecting the film thickness of the liquid film, and when the detection result of the film thickness is a predetermined target value, arranging a plasma generation source to face the upper surface of the substrate and performing plasma irradiation on the liquid film from the plasma generation source, and repeating the formation of the liquid film, the detection of the film thickness, and the plasma irradiation a plurality of times in this order. Furthermore, a third aspect of the substrate processing method according to the present invention is, in order to achieve the above object, a step of holding the substrate in a horizontal posture, a step of supplying a processing liquid to the upper surface of the substrate and rotating the substrate about a vertical axis to form a liquid film of the processing liquid on the upper surface of the substrate, a step of detecting the film thickness of the liquid film, and when the detection result of the film thickness is a predetermined target value, arranging a plasma generation source to face the upper surface of the substrate and performing plasma irradiation on the liquid film from the plasma generation source, the processing liquid contains sulfuric acid, in the step of performing the plasma irradiation, a gas containing oxygen is supplied between the plasma generation source and the upper surface of the substrate, after the detection of the film thickness, while lowering the plasma generation source from a standby position above the substrate to a facing position with the substrate, the gas is supplied to the gap space between the plasma generation source and the substrate, and as the plasma generation source descends, the supply amount of the gas is decreased over time.

[0009] Also, in the substrate processing apparatus according to this invention 1stIn order to achieve the above object, an aspect includes a substrate holding unit that holds a substrate in a horizontal posture and rotates it around a vertical axis, a processing liquid supply unit that supplies a processing liquid to the upper surface of the substrate held by the substrate holding unit, a control unit that causes a predetermined amount of the processing liquid to be supplied from the processing liquid supply unit and rotates the substrate by the substrate holding unit to form a liquid film of the processing liquid on the upper surface of the substrate, a film thickness measurement unit that measures the film thickness of the liquid film, a reactor that generates plasma, and a moving mechanism that moves the reactor between an opposing position close to and facing the upper surface of the substrate and a standby position spaced apart from the upper surface of the substrate. The reactor has a planar size equal to or larger than the planar size of the substrate and faces the entire upper surface of the substrate at the facing position. The control unit has a film thickness calculation unit that calculates the film thickness from a signal from the film thickness measurement unit, and when the calculation result of the film thickness is a predetermined target value, positions the reactor at the opposing position. with the rotation of the substrate stopped Performs plasma irradiation on the liquid film on the upper surface of the substrate. Furthermore, in the substrate processing apparatus according to the present invention 2nd In order to achieve the above object, a substrate holding unit that holds a substrate in a horizontal posture and rotates it around a vertical axis; a processing liquid supply unit that supplies a processing liquid to the upper surface of the substrate held by the substrate holding unit; a control unit that causes a predetermined amount of the processing liquid to be supplied from the processing liquid supply unit and rotates the substrate by the substrate holding unit to form a liquid film of the processing liquid on the upper surface of the substrate; a film thickness measurement unit that measures the film thickness of the liquid film; a reactor that generates plasma; and a moving mechanism that moves the reactor between an opposing position close to and facing the upper surface of the substrate and a standby position spaced apart from the upper surface of the substrate, wherein the processing liquid contains sulfuric acid, the control unit has a film thickness calculation unit that calculates the film thickness from a signal from the film thickness measurement unit, and when the calculation result of the film thickness is a predetermined target value, the reactor is positioned at the opposing position to perform plasma irradiation on the liquid film on the upper surface of the substrate, and after the measurement of the film thickness, while the reactor is being lowered from the standby position above the substrate to the opposing position with the substrate, a gas containing oxygen is supplied to the gap space between the reactor and the substrate, and as the reactor is lowered, the supply amount of the gas is decreased over time.

[0010] In the invention configured as described above, by activating the processing liquid by plasma irradiation, the chemical reaction related to substrate processing can be promoted. However, according to the findings of the inventor of the present application, since the thickness (film thickness) of the liquid film greatly affects the processing quality, it is necessary to appropriately control the film thickness according to the processing content. Specifically, while it is necessary to sufficiently supply the chemical species in the processing liquid that contribute to the processing of the substrate, the liquid film must be thin enough so that the active species generated by plasma lighting can reach the substrate surface.

[0011] Therefore, in this invention, after forming a liquid film on the upper surface of the substrate by rotating the substrate in a horizontal posture and supplying the processing liquid, a step of detecting the film thickness is provided. And if the film thickness is appropriate, plasma irradiation is performed. By doing so, the processing of the substrate with the processing liquid can be performed well. Also, it is sufficient to cover the substrate with a thin liquid film, and it is not necessary to continuously supply the processing liquid, so as a result, the consumption amount of the processing liquid can also be reduced.

Effects of the Invention

[0012] As described above, according to the present invention, a liquid film of a processing liquid covering the substrate is formed, and after confirming that the film thickness is appropriate, plasma irradiation is performed. Therefore, the processing liquid can be activated to perform good processing.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0014] FIG. 1 is a diagram showing a schematic configuration of an embodiment of a substrate processing apparatus according to the present invention. This substrate processing apparatus 1 is an apparatus for performing wet processing using a processing liquid on various substrates such as semiconductor substrates and glass substrates. For example, this apparatus 1 can be applied for the purpose of removing a photoresist film formed on the surface of a semiconductor substrate. The substrate processing apparatus 1 includes an upper unit 20, a lower unit 30, a liquid supply unit 40, and a film thickness measurement unit 50 that are arranged in a processing chamber 10 and are the main bodies of substrate processing, and a control unit 90 that controls the operation of the entire apparatus.

[0015] The lower unit 30 is provided with a spin chuck mechanism for holding the substrate S. Specifically, a flat spin base 31 having a planar size substantially the same as the planar size of the substrate S is provided in the lower unit 30. A plurality of chuck pins 32 are arranged at positions on the upper surface of the spin base 31 close to the outer peripheral portion. By the chuck pins 32 coming into contact with the substrate S, the substrate S is held in a horizontal posture.

[0016] A rotary support shaft 33 extending in the vertical direction is coupled to the lower surface of the spin base 31, and the rotary support shaft 33 is rotatably supported about the vertical axis by a rotation drive mechanism 34. The rotation drive mechanism 34 is fixed to the bottom surface of the processing chamber 10, and operates in response to a control command from a rotation control unit 98 provided in the control unit 90 to rotate the spin base 31 at a predetermined rotation speed. As a result, the substrate S in the horizontal posture rotates about the vertical axis. The dashed-dotted line indicates the rotation axis of the substrate S. When the substrate S is circular, it is preferable to make the center thereof coincide with the rotation center.

[0017] Also, a splash guard 35 is arranged so as to surround the side of the spin base 31. The splash guard 35 moves up and down in response to a control command from an elevation control unit 99 provided in the control unit 90. When the upper end of the splash guard 35 has risen above the substrate S, the splash guard 35 surrounds the periphery of the substrate S and receives and collects liquids such as processing liquid scattered from the upper surface of the substrate to the periphery in the substrate processing described later. On the other hand, when the upper end of the splash guard 35 has descended below the substrate S and the substrate S is exposed, for example, access by a hand for transporting the substrate from the outside can be accepted.

[0018] An upper unit 20 is arranged above the lower unit 30. The upper unit 20 has a flat plate member 21 having a planar size slightly larger than the planar size of the substrate S. A shaft 22 is coupled to the upper portion of the plate member 21, and the shaft 22 is supported so as to be vertically movable by a lifting mechanism 23 fixed to the ceiling surface of the processing chamber 10.

[0019] The lifting mechanism 23 operates in response to a control command from the lifting control unit 91 provided in the control unit 90, causing the plate member 21 to move up and down. As a result, the plate member 21 moves between a standby position shown in FIG. 1, which is significantly separated upward from the spin base 31, and an opposing position where it approaches and faces the upper surface of the substrate S held on the spin base 31 as described later.

[0020] A plasma reactor 24 that functions as a plasma generation source under atmospheric pressure is attached to the lower surface of the plate member 21, that is, the surface facing the substrate S. The plasma reactor 24 has a flat plate shape with a planar size equal to or larger than the planar size of the substrate S and faces the entire upper surface of the substrate S. That is, when viewed from above, the plasma reactor 24 covers the entire substrate S. For example, if the substrate S is circular, a disk-shaped plasma reactor 24 with a diameter larger than that of the substrate S can be used. The plasma reactor 24 receives power supply from the plasma power supply 92 provided in the control unit 90 and plasmaizes the nearby gas.

[0021] A gas nozzle 25 is provided at the peripheral edge portion of the lower surface of the plate member 21 outside the plasma reactor 24. The gas nozzle 25 is connected to the gas supply unit 93 of the control unit 90 and discharges the gas supplied from the gas supply unit 93. As shown by the dotted arrow, the gas discharge direction is along the lower surface of the plasma reactor 24, and more specifically, it is a substantially horizontal direction and a direction toward the rotation axis of the substrate S. Thereby, the atmosphere control in the plasma generation space directly below the plasma reactor 24 can be performed.

[0022] It is sufficient to have at least one gas nozzle 25, but it is more preferable to provide a plurality of gas nozzles at equal angular intervals with respect to the rotation axis of the substrate S. Also, as described later, there are cases where gas supply is not required depending on the object to be processed, and in cases where only such cases are assumed, it is possible to omit the gas nozzle.

[0023] At least one liquid supply unit 40 is provided on the side of the lower unit 30. The liquid supply unit 40 includes a rotation mechanism 41 having a movable shaft 42 that rotates around a vertical axis, an arm 43 attached to the movable shaft 42, and a liquid nozzle 44 attached to the tip of the arm 43. The liquid nozzle 44 selectively discharges a processing liquid supplied from a processing liquid supply unit 94 provided in the control unit 90 and a rinse liquid supplied from a rinse liquid supply unit 95. Here, it is assumed that one set of liquid supply units 40 handles two types of liquids, but liquid supply units may be provided for each type of liquid. Also, a configuration in which a plurality of nozzles are provided on one arm and they are used selectively for each type of liquid may be adopted.

[0024] When the rotation mechanism 41 rotates in response to a control command from the rotation control unit 96 of the control unit 90, the liquid nozzle 44 moves between a processing position where it is positioned above the substrate S and supplies liquid to the upper surface of the substrate S, and a standby position where it retracts to the side of the substrate S. Also, while discharging liquid from the liquid nozzle 44, the liquid nozzle 44 can be scanned and moved along the upper surface of the substrate S.

[0025] A film thickness measurement unit 50 is further provided on the side of the lower unit 30. The film thickness measurement unit 50 optically measures the film thickness of a liquid film formed on the substrate S as will be described later. Specifically, the film thickness measurement unit 50 includes a rotation mechanism 51 having a movable shaft 52 that rotates around a vertical axis, an arm 53 attached to the movable shaft 52, and a sensor 54 attached to the tip of the arm 53. The sensor 54 irradiates the measurement object with light, receives the reflected light, and outputs a signal corresponding to the received light to the film thickness calculation unit 97 of the control unit 90.

[0026] The film thickness calculation unit 97 detects the film thickness based on the output signal from the sensor 54. As the detection method, for example, those using various optical measurement principles such as the optical interference method and the reflectance spectroscopy method can be applied. As long as it is a method capable of measuring the film thickness of the liquid film non - contact and in a short time, a method based on a measurement principle other than such an optical method may also be used.

[0027] The rotation mechanism 41 rotates in response to a control command from the rotation control unit 96 of the control unit 90, so that the liquid nozzle 44 moves between a processing position where it is positioned above the substrate S and supplies liquid to the upper surface of the substrate S, and a standby position where it retracts to the side of the substrate S. Also, while discharging liquid from the liquid nozzle 44, the liquid nozzle 44 can be scanned and moved along the upper surface of the substrate S.

[0028] In addition to this, the control unit 90 of the substrate processing apparatus 1 includes a process control unit 900 that controls each part of the apparatus according to a previously formulated processing recipe to execute predetermined substrate processing. The process control unit 900 has a CPU (Central Processing Unit) and a storage unit, and the CPU executes a control program stored in the storage unit in advance to realize the substrate processing described below.

[0029] Next, the operation of the substrate processing apparatus 1 configured as described above will be described. The substrate processing apparatus 1 can be used for various applications, but here, as an example, a resist removal process for removing a resist film formed on the surface of a semiconductor substrate will be described. When the resist film is an organic substance, for example, there is a method of oxidatively decomposing the resist film by the strong oxidizing power of concentrated sulfuric acid. Therefore, here, an aqueous sulfuric acid solution at room temperature is used as the processing liquid.

[0030] Conventionally, as a resist removal process using the oxidizing power of sulfuric acid, a method using a mixed solution (SPM) of sulfuric acid and hydrogen peroxide solution as the processing liquid has been widely used. However, since water is generated by the chemical reaction between sulfuric acid and hydrogen peroxide and the sulfuric acid concentration decreases over time, it is necessary to continuously supply the processing liquid. This leads to an increase in the amount of sulfuric acid used, and as a result, the environmental load increases. Also, high-concentration hydrogen peroxide solution requires careful handling.

[0031] Therefore, in this embodiment, by activating sulfuric acid, which is the processing liquid, by plasma irradiation, an equivalent resist removal effect can be obtained without using hydrogen peroxide solution. According to the findings of the inventors of the present application, in this case, it is not necessary to continuously supply the processing liquid, and it is sufficient if the surface of the substrate is covered with a liquid film of the processing liquid required for resist removal. Therefore, the required amount of sulfuric acid as the processing liquid can also be reduced. In view of this, in this embodiment, a liquid film of the processing liquid is formed on the upper surface of the substrate S, and plasma irradiation is performed thereon to execute resist removal.

[0032] Figure 2 is a flowchart showing substrate processing in this embodiment. FIGS. 3 and 4 are diagrams schematically showing the operations of respective parts in this processing. First, the entire apparatus is initialized (step S101). In the initial state of the substrate processing apparatus 1, as shown in FIGS. 1 and 3(a), the plate member 21 of the upper unit 20, the liquid nozzle 44 of the liquid supply unit 40, and the sensor 54 of the film thickness measurement unit 50 are all in standby positions, and neither gas discharge from the gas nozzle 25 nor liquid discharge from the liquid nozzle 44 is performed. Further, the splash guard 35 is in the lower position, and the upper part of the spin base 31 is exposed.

[0033] From this state, the substrate S to be processed is received and appropriate pre-treatment is executed (step S102). Specifically, the substrate S conveyed by an external transfer robot is carried into the processing chamber 10 through a shutter (not shown). The substrate S is placed on the spin chuck 31 in a horizontal posture with the processed surface on which the resist film to be removed is formed facing upward. The content of the pre-treatment is arbitrary, and for example, etching treatment, cleaning treatment using a chemical solution, and subsequent rinsing treatment can be applied. Note that the substrate S after pre-treatment is performed externally may be carried into this substrate processing apparatus 1. That is, the execution of pre-treatment in the substrate processing apparatus 1 may be omitted.

[0034] Subsequently, the substrate processing method according to the present invention is executed. That is, first, a liquid film is formed by the processing liquid (step S103). As shown in FIG. 3(b), the splash guard 35 moves upward to surround the periphery of the substrate S. Then, the liquid nozzle 44 of the liquid supply unit 40 is positioned above the rotation center of the substrate S, that is, on the rotation axis of the substrate S indicated by the dashed line, and the processing liquid Lq is discharged from the liquid nozzle 44. The total amount of the discharged liquid is predetermined. Specifically, the target value of the film thickness of the liquid film formed on the substrate S is predetermined, and the amount obtained by adding a certain margin to the product of the target value and the surface area of the substrate S is used as the supply liquid amount. When the discharge of the processing liquid is completed, the liquid nozzle 44 is returned to the standby position.

[0035] Furthermore, after the spin base 31 rotates at a predetermined speed for a certain period of time, the rotation stops. As a result, the substrate S rotates, and due to the action of centrifugal force, the processing liquid spreads over the entire upper surface of the substrate S, and finally a part of it is thrown off from the peripheral edge of the substrate S. The thrown-off processing liquid is received by the splash guard 35 and recovered by a recovery unit (not shown). After the rotation of the substrate S is completed, the splash guard 35 descends.

[0036] Finally, the processing liquid remaining on the substrate S forms a paddle-shaped liquid film LP. The thickness of the liquid film is determined by the rotation speed, rotational acceleration, and duration of rotation of the substrate S. Note that the optimum value of the liquid film thickness varies depending on the surface state of the substrate S, specifically, the type and thickness of the resist film, the coverage rate with respect to the substrate surface, etc., and also varies depending on the type and concentration of the processing liquid. Therefore, it is preferable that the target value of the film thickness be appropriately changed and set according to the purpose of the processing. Along with this, parameters such as the supply amount of the processing liquid, the rotation speed of the substrate S, the rotational acceleration, and the duration of rotation are also appropriately changed and set.

[0037] However, due to process variations, it is not always possible to reliably form a liquid film with an appropriate film thickness solely based on these parameter settings. As will be described in detail later, in the resist removal process of this embodiment, the film thickness of the liquid film LP has a great influence on the processing quality. The preferred film thickness is generally on the order of several hundred micrometers. Therefore, the film thickness of the formed liquid film LP is measured (step S104).

[0038] Specifically, as shown in FIG. 3(c), the sensor 54 of the film thickness measurement unit 50 moves on the substrate S and irradiates light toward the liquid film LP on the substrate S, and receives the reflected light. Based on the output signal from the sensor 54, the film thickness calculation unit 97 calculates the film thickness. As indicated by the dotted arrow, it is preferable that the sensor 54 scans and moves along the upper surface of the substrate S and measures the film thickness at a plurality of locations. After the film thickness measurement, the sensor 54 is returned to the standby position.

[0039] Subsequently, it is determined whether the film thickness calculated by the film thickness calculation unit 97 is within an appropriate range including the optimum value (step S105). For example, about (±20)% with respect to the optimum value can be set as the appropriate range. Thus, the target value of the film thickness may be defined not only as a single value but also as a certain range. The target value of the film thickness is stored in the storage unit of the process control unit 900. The CPU of the process control unit 900 acquires the target value of the film thickness from the storage unit and applies it to the determination of the film thickness. Here, the target value of the film thickness may store different values according to the type of the substrate, the type of the processing liquid, or the content of the processing of the processing liquid. When a plurality of types of target values are stored in the storage unit, the target values are associated with the type of the substrate, the type of the processing liquid, or the content of the processing of the processing liquid.

[0040] If the film thickness is not within the appropriate range (NO in step S105), the process returns to step S103 and the liquid film formation is executed again. At this time, at least one of the parameters related to the film thickness, that is, the supply amount of the processing liquid, the rotation speed of the substrate, the rotation duration of the substrate, and the rotational acceleration of the substrate, may be made different from that during the previous liquid film formation. By changing the liquid film formation conditions in this way, it is possible to optimize the film thickness in the re-formed liquid film.

[0041] When the film thickness is within the appropriate range (YES in step S105), step S106 is executed. Specifically, as indicated by the solid-line arrow in FIG. 4(a), gas discharge is started from the gas nozzle 25, and a high voltage for plasma ignition is applied from the plasma power supply 92 to the plasma reactor 24. Also, as indicated by the dotted-line arrow, the plate member 21 descends from the standby position to the opposing position, and the plasma reactor 24 is positioned at a position close to and facing the upper surface of the substrate S. The two finally approach to a distance of several millimeters. As a result, as shown in FIG. 4(b), the plasma P generated in the vicinity of the lower surface of the plasma reactor 24 by voltage application is irradiated onto the liquid film LP on the substrate S (step S107).

[0042] By supplying gas from the gas nozzle 25 between the plasma reactor 24 and the substrate S, the atmosphere in the gap space between them can be controlled. As the atmosphere control for promoting plasma generation, it is preferable to supply a gas containing a noble gas such as helium or argon. Also, in the case of a resist removal process using a treatment liquid containing sulfuric acid, it has been found that plasma irradiation in an atmosphere containing oxygen is effective in improving the processing quality. For this reason, for example, a mixed gas of oxygen and a noble gas can be discharged from the gas nozzle 25.

[0043] Also, depending on the type and thickness of the resist film, there may be cases where the treatment can be performed well using only oxygen in the atmosphere. In such cases, it may not be necessary to perform gas discharge from the gas nozzle 25. Also, if the apparatus only performs processes that do not require gas discharge, it is possible to omit the gas nozzle itself.

[0044] When the plasma irradiation continues for a predetermined time, the plasma reactor 24 rises together with the plate member 21 (step S108), and subsequently, a rinsing process is performed (step S109). That is, as shown in FIG. 4(c), the splash guard 35 rises, and an appropriate rinsing liquid Lr, for example, de-ionized water (DIW), is supplied from the rinsing liquid supply unit 95 to the substrate S through the liquid nozzle 44 of the liquid supply unit 40. Thereby, the substrate processing by the processing liquid is stopped. The substrate S rotates at a predetermined rotational speed, and the rinsing liquid Lr is shaken off from the peripheral portion of the substrate S.

[0045] In the processing recipe, when the repetition of steps S103 to S109 is specified (YES in step S110), the process returns to step S103 and the above processing is repeated. Depending on the type and thickness of the resist film, it may not be possible to completely remove everything in the above processing. In such a case, by repeatedly performing the formation of the liquid film and the plasma irradiation, it becomes possible to more surely remove the resist film.

[0046] When the repeated processing is no longer necessary (NO in step S110), an appropriate post-treatment is performed (step S111), and finally, a drying process for drying the substrate S is performed (step S112). The content of the post-treatment is arbitrary and can also be omitted. For example, in order to prevent the collapse of the fine pattern formed on the substrate S, a process of replacing the liquid adhering to the substrate S with a liquid having a lower surface tension can be performed as the post-treatment. Also, as shown in FIG. 4(d), the drying process is performed by rotating the substrate S at a high speed and shaking off the liquid components remaining and adhering to the substrate S.

[0047] The processed substrate S can be carried out of the processing chamber 10. Next, if there is a substrate to be processed (YES in step S113), the process returns to step S101, and a new substrate is received from the initial state and the above processing is executed. If there is no next substrate (NO in step S113), the processing ends. The above is the outline of the resist removal process in this embodiment.

[0048] Figure 5 is a timing chart showing the operation timings of respective parts. In step S106, the plasma reactor 24 descends from the standby position (time T1) to the opposing position (time T2), and during this period, gas discharge from the gas nozzle 25 and plasma lighting in the plasma reactor 24 are performed. In this example, gas discharge is started after the time T1 when the plasma reactor 24 starts to descend, but gas discharge may be started earlier than the time T1.

[0049] The gas supply amount is initially relatively large and is changed to a smaller flow rate before the time T2. As shown by the solid line in the figure, the flow rate may be changed stepwise, or as shown by the dotted line, the gas supply amount may gradually decrease with time. By initially supplying gas at a large flow rate, even when the distance between the plasma reactor 24 and the substrate S is large (for example, 10 millimeters or more), the atmosphere control of the plasma generation space directly below the plasma reactor 24 can be performed well.

[0050] On the other hand, in a state where the plasma reactor 24 and the substrate S are close (for example, up to 3 millimeters or less), the gas supply amount is reduced in order to prevent the liquid film LP formed on the upper surface of the substrate S from being disturbed. Since the volume of the gap space is small, it is possible to perform good atmosphere control even with a small flow rate.

[0051] Regarding the voltage application to the plasma reactor 24 for lighting the plasma, in order to stabilize the plasma lighting state, it is started at a timing sufficiently earlier than the time T2. In this example, in order to light the plasma in a state where the atmosphere control in the plasma generation space is performed, the voltage application is started after the gas discharge from the gas nozzle 25 is started. However, for example, the plasma may be lit earlier than the gas discharge, or it may be in a constantly lit state.

[0052] The plasma reactor 24 is disposed at a position close to and facing the substrate S, and the plasma is lit in a state where the atmosphere between the plasma reactor 24 and the substrate S is controlled. Thereby, the gap space between the plasma reactor 24 and the substrate S becomes a plasma generation space, and the gas in the gap space is turned into plasma.

[0053] FIG. 6 is a diagram schematically showing the principle of the resist removal process by plasma lighting. As shown in FIG. 6(a), the plasma P generated in the gap space GS between the plasma reactor 24 and the substrate S irradiates the liquid film LP. Thereby, the active species A dissolved in the liquid promotes the oxidative decomposition reaction of the resist film R by sulfuric acid in the liquid. Thereby, the removal process of the resist film R proceeds.

[0054] Regarding the thickness Tp of the liquid film LP, it is necessary to make it thick enough so that at least a sufficient amount of sulfuric acid, which is the main component of the oxidative decomposition reaction, is supplied to decompose the resist film R. On the other hand, as shown in FIG. 6(b), if the liquid film LP is too thick, the active species A dissolved in the liquid will be deactivated before reaching the interface with the resist film R, and the effect of plasma irradiation will be reduced. To enhance this effect, the liquid film LP is preferably thinner. From these facts, there is an appropriate range for the thickness Tp of the liquid film LP.

[0055] For example, in a certain system experimented by the inventor of the present application, a 100% resist removal rate was obtained by irradiating a liquid film with a thickness of 200 micrometers with plasma. However, when the film thickness was 220 micrometers under the same plasma irradiation conditions, the resist removal rate decreased to about 98%, and when it was about 300 micrometers, it decreased to about 52%. Thus, a small difference in film thickness causes a large difference in resist removal performance.

[0056] A method of controlling the thickness of the liquid film LP only by the amount of the processing liquid supplied to the substrate S is also conceivable. For example, the amount of liquid required to form a liquid film with a thickness of 200 micrometers on a circular substrate with a diameter of 300 millimeters is about 14 milliliters. However, since there are unevenness and differences in wettability due to position on the substrate surface, it is practically difficult to form a uniform liquid film only by supplying the required amount of liquid. Therefore, it is preferable to supply a processing liquid in an amount larger than the required amount and adjust the film thickness by spinning off a part by rotating the substrate S. In this case, it is possible to achieve a desired film thickness by controlling the rotation speed, acceleration, duration thereof, and the like.

[0057] It is preferable that the rotation of the substrate S is stopped while the plasma irradiation is being performed. In order for a sufficient amount of active species generated in the liquid to reach the interface with the resist film by plasma irradiation, it is effective to keep the liquid film LP in a stationary state. In addition, for example, in order to achieve uniformity in processing over the entire substrate, the substrate S may be rotated at a low speed such that the liquid film LP is not disturbed. If the rotation speed at this time is made smaller than the rotation speed during liquid film formation, it is possible to prevent the processing liquid from dropping from the substrate S and avoid breakage of the liquid film LP formed on the substrate S.

[0058] In the resist removal process of the present embodiment, it is determined in step S110 whether or not the process needs to be repeated. And when repetition is necessary, a series of processes of liquid film formation, film thickness measurement, and plasma irradiation are executed a plurality of times. Thereby, the following effects can be obtained.

[0059] First, the resist removal effect can be made more reliable. Specifically, it is as follows. For example, when the resist film is thick or when hardening has progressed due to ion implantation, it may not be possible to completely remove all the resist films in one treatment. Here, if the liquid film is thickened to enhance the resist removal action, the effect of plasma irradiation is reduced, and as a result, the resist removal effect is not necessarily improved. By repeating the combination of a thin liquid film and plasma irradiation a plurality of times, it is possible to more effectively achieve resist removal.

[0060] Second, the thickness of the liquid film can be varied for each process. The surface of the substrate has irregularities, and the state of the resist film varies depending on the position within the substrate due to differences in ion implantation density and the like. Therefore, the appropriate thickness of the liquid film required in the process for removing the resist film is not uniform within the substrate. When forming the liquid film multiple times, the target value of the film thickness can be set each time according to the purpose, so that good processing results can be obtained for the entire substrate.

[0061] Third, the sulfuric acid concentration in the processing liquid decreases due to being consumed in the chemical reaction with the resist film, but this can be reset by newly forming a liquid film. By processing the substrate with the newly supplied fresh processing liquid, it becomes possible to obtain good processing quality.

[0062] In such a repeated process, it is possible to set each parameter such as the supply amount of the processing liquid to the substrate S, the rotation speed and acceleration of the substrate S, the rotation duration, the target value of the film thickness, and the plasma irradiation conditions for each process.

[0063] As described above, in this embodiment, the removal process of the resist film formed on the substrate S is performed by a combination of liquid film formation using a processing liquid mainly composed of sulfuric acid and plasma irradiation. Since the processing liquid can be activated by plasma irradiation, there is no need to add hydrogen peroxide, and there is no need to continuously supply the processing liquid. Furthermore, in order for the plasma active species to reach the interface between the processing liquid and the resist film, a thinner liquid film is more suitable, and thereby the amount of the processing liquid used can be further reduced.

[0064] As described above, in the above embodiment, the spin chuck mechanism (spin base 31, chuck pin 32, rotary support shaft 33, rotary drive mechanism 34) functions as the "substrate holding part" of the present invention, and the plasma reactor 24 functions as the "reactor" of the present invention. And the plasma reactor 24 and the plasma power supply 92 function as the "plasma generation source" of the present invention. Also, the control unit 90 functions as the "control part" of the present invention.

[0065] Also, the liquid supply unit 40 and the processing liquid supply part 94 function as the "processing liquid supply part" of the present invention. Further, the film thickness measurement unit 50 functions as the "film thickness measurement part" of the present invention. And the gas nozzle 25 and the gas supply part 93 function as the "gas supply part" of the present invention.

[0066] Note that the present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit thereof. For example, in the above embodiment, the supply of the processing liquid to the substrate S is performed by discharging the processing liquid from the liquid nozzle 44 positioned above the rotation center of the substrate S. However, the supply mode of the processing liquid is not limited to this, and for example, a method of spray coating using a spray nozzle or a method of discharging the processing liquid while scanning and moving the nozzle with respect to the substrate S may be used.

[0067] Also, the plasma reactor 24 in the above embodiment is a flat plate-shaped member having a planar size equal to or larger than the planar size of the substrate S. Instead of this, as shown below, it is also possible to use a smaller plasma reactor.

[0068] FIG. 7 is a plan view illustrating another form of the plasma reactor. In the example shown in FIG. 7(a), a plasma reactor 24a smaller than the substrate S is attached to the tip of a swing arm 24b, and the swing arm 24b swings by the operation of a drive mechanism (not shown), so that the plasma reactor 24a scans and moves along the upper surface of the substrate S. Since the plasma lighting is limited to the space between the plasma reactor 24a and the substrate S, the entire substrate S can be processed by scanning and moving the plasma reactor 24a with respect to the substrate S. Also, only a specific position on the substrate S can be processed. In order to process the entire substrate S in a short time, the substrate S may be rotated at a low speed. The rotation speed at this time is preferably lower than the rotation speed during the liquid film formation.

[0069] Also, in the example shown in FIG. 7(b), an elongated plasma reactor 24c that is larger than the size of the substrate S in one direction and smaller than the size of the substrate S in the orthogonal direction is provided. A scanning movement mechanism (not shown) scans and moves the plasma reactor 24c with respect to the substrate S in a direction intersecting the longitudinal direction thereof, so that the entire surface of the substrate S is processed. The scanning movement mechanism includes a motor and a coupling member that couples the plasma reactor 24c and the motor. In this example, the rotation of the substrate S is not necessarily required.

[0070] Also, in the above embodiment, sulfuric acid is used as the processing liquid and a gas containing oxygen is introduced into the plasma generation space for the purpose of removing the resist film, which is an organic substance formed on the surface of the substrate S. These materials are shown as an example of the processing, and the substrate processing apparatus and the substrate processing method of the present invention are also applicable to the processing using various other materials.

[0071] As described above by exemplifying specific embodiments, in the substrate processing method according to the present invention, for example, after the formation of the liquid film, the rotation of the substrate can be stopped and plasma irradiation can be performed. According to such a configuration, the disturbance of the liquid film formed on the substrate can be suppressed, and the active species dissolved in the liquid by the plasma irradiation can be efficiently reached to the substrate surface.

[0072] For example, the plasma generation source may include a reactor having a planar size equal to or larger than the planar size of the substrate. According to such a configuration, the entire surface of the substrate can be processed simultaneously. Alternatively, for example, the plasma generation source may include a reactor having a planar size smaller than the planar size of the substrate, and the reactor may be scanned and moved relative to the substrate while rotating the substrate at a rotational speed equal to or lower than the time of forming the liquid film to perform plasma irradiation. According to such a configuration, by sequentially changing the facing position between the reactor and the substrate, it is possible to process the entire substrate. Further, it is also possible to process only a specific position on the substrate as necessary.

[0073] For example, after forming the liquid film, the rotation of the substrate can be stopped to detect the film thickness. By detecting the film thickness with the rotation of the substrate stopped, it is possible to detect the film thickness without being affected by vibrations associated with rotation or film thickness variations due to centrifugal force.

[0074] For example, for a substrate whose detected film thickness is different from the target value, the formation of the liquid film can be re-executed. By doing so, plasma irradiation can be executed in a state where the thickness of the liquid film is optimized. In this case, at least one of the supply amount of the processing liquid, the rotational speed of the substrate, the continuous rotation time of the substrate, and the rotational acceleration of the substrate may be made different from that during the previous liquid film formation to re-execute the formation of the liquid film. According to such a configuration, by changing the liquid film formation conditions and re-executing the formation of the liquid film, it is possible to optimize the film thickness of the newly formed liquid film.

[0075] For example, in the step of forming the liquid film, a predetermined amount of the processing liquid that is more than the liquid amount constituting the liquid film when the film thickness is the target value is supplied to the upper surface of the substrate, and a part of the processing liquid can be shaken off by rotation. According to such a configuration, the parameters that determine the thickness of the liquid film mainly relate to the rotation of the substrate. That is, by appropriately controlling the rotation of the substrate, it is possible to realize a desired film thickness.

[0076] For example, the formation of a liquid film, the detection of the film thickness, and the plasma irradiation can be repeatedly executed in this order a plurality of times. According to such a configuration, by repeating the process a plurality of times, the processing result can be made more reliable. Further, for example, by varying the processing conditions for each execution, it is also possible to further enhance the processing effect.

[0077] Here, the processing liquid may contain sulfuric acid. As a substrate treatment using sulfuric acid, a treatment using sulfuric acid-hydrogen peroxide water mixed with hydrogen peroxide water is known, but by performing activation by plasma irradiation, hydrogen peroxide water can be made unnecessary.

[0078] In this case, in the step of performing plasma irradiation, a gas containing oxygen can be supplied between the plasma generation source and the upper surface of the substrate. According to the findings of the inventors of the present application, in the treatment with a treatment liquid mainly composed of sulfuric acid, it has been found that the treatment effect is improved by lighting the plasma in an atmosphere containing oxygen. Therefore, by setting the atmosphere between the plasma generation source and the upper surface of the substrate to an oxygen atmosphere, it is possible to enhance the treatment effect.

[0079] In this case, further, after detecting the film thickness, while lowering the plasma generation source from the standby position above the substrate to the opposing position with the substrate, a gas is supplied to the gap space between the plasma generation source and the substrate, and preferably, the supply amount of the gas is decreased with time as the plasma generation source descends. The plasma generation source moves from a standby position largely separated from the substrate to an opposing position close to and facing the substrate. At this time, by supplying a gas to the gap space between the plasma generation source and the substrate, the atmosphere in the gap space can be appropriately controlled.

[0080] From the viewpoint of atmosphere control, it is effective to supply the gas at a relatively large flow rate when the gap between the plasma generation source and the substrate is large. On the other hand, when the gap becomes small, there is a risk that the gas flow may disturb the liquid film formed on the substrate. To prevent this, it is effective to reduce the supply amount of the gas with time.

[0081] For example, the present invention can also be applied to a process of removing a resist film formed on the upper surface of a substrate with a processing liquid. That is, in order to decompose and remove the resist film, a process combining liquid film formation with the processing liquid and plasma irradiation can be applied. Since the reactive species in the processing liquid can be activated by plasma irradiation, it is possible to perform good resist removal even with a small amount of liquid.

[0082] For example, the present invention may further include a target value acquisition step of acquiring a target value, and the target value can correspond to any one of the type of the substrate, the type of the processing liquid, and the content of the process by the processing liquid. According to such a configuration, it is possible to set a target value of the film thickness according to the application, and for example, a plurality of target values can be switched and applied.

[0083] In addition, in the substrate processing apparatus according to the present invention, for example, the reactor can have a planar size equal to or larger than the planar size of the substrate and can be configured to face the entire upper surface of the substrate at the opposing position. According to such a configuration, it is possible to process the entire surface of the substrate simultaneously.

[0084] For example, a gas supply unit for supplying gas between the reactor and the upper surface of the substrate may be further provided. According to such a configuration, it is possible to control the atmosphere between the reactor and the substrate to conditions suitable for plasma lighting and stably generate plasma. In addition, the types of active species generated by plasma lighting can be controlled.

[0085] Here, the gas supply unit may have a gas nozzle that is integrally coupled to the reactor and discharges gas, and further, the gas nozzle may be configured to discharge gas substantially horizontally from the peripheral edge side of the substrate toward the rotation center. Since the positional relationship between the two is fixed by integrating the gas nozzle with the reactor, the atmosphere control on the lower surface of the reactor can be performed more reliably. Further, by discharging gas in a substantially horizontal direction from the peripheral edge side of the substrate toward the rotation center, the atmosphere between the reactor and the substrate can be made uniform, which contributes to stable plasma lighting.

Industrial Applicability

[0086] This invention is applicable to various substrate processes for processing a substrate with a processing liquid, and can be suitably applied, for example, to a process of removing a resist film from a substrate.

Explanation of Signs

[0087] 1 Substrate processing apparatus 24 Plasma reactor (plasma generation source, reactor) 25 Gas nozzle (gas supply unit) 31 Spin base (substrate holding unit) 32 Chuck pin (substrate holding unit) 33 Rotation support shaft (substrate holding unit) 34 Rotation drive mechanism (substrate holding unit) 40 Liquid supply unit 50 Film thickness measurement unit (film thickness measurement unit) 90 Control unit (control unit) 92 Plasma power supply (plasma generation source) 93 Gas supply unit (gas supply unit) 94 Processing liquid supply unit (processing liquid supply unit) 97 Film thickness calculation unit Lq Processing liquid S Substrate

Claims

1. a step of holding the substrate in a horizontal posture; a step of supplying a processing liquid onto the upper surface of the substrate and rotating the substrate about a vertical axis to form a liquid film of the processing liquid on the upper surface of the substrate; a step of detecting the film thickness of the liquid film; when the detection result of the film thickness is a predetermined target value, arranging a plasma generation source opposite to the upper surface of the substrate and performing plasma irradiation on the liquid film from the plasma generation source; comprising; the plasma generation source faces the entire upper surface of the substrate with a reactor having a planar size equal to or larger than the planar size of the substrate, and the plasma irradiation is performed with the rotation of the substrate stopped, a substrate processing method.

2. The substrate processing method according to claim 1, wherein after the formation of the liquid film, the rotation of the substrate is stopped and the film thickness is detected.

3. The substrate processing method according to claim 1 or 2, wherein when the detection result of the film thickness is different from the target value, the formation of the liquid film is re-executed on the substrate.

4. The substrate processing method according to claim 3, wherein at least one of the supply amount of the processing liquid, the rotation speed of the substrate, the rotation duration of the substrate, and the rotational acceleration of the substrate is made different from that during the previous liquid film formation, and the formation of the liquid film is re-executed.

5. In the step of forming the liquid film, a predetermined amount of the processing liquid that is more than the liquid amount constituting the liquid film when the film thickness is the target value is supplied onto the upper surface of the substrate, and a part of the processing liquid is shaken off by rotation, the substrate processing method according to any one of claims 1 to 4.

6. The substrate processing method according to any one of claims 1 to 5, wherein the formation of the liquid film, the detection of the film thickness, and the plasma irradiation are repeatedly executed in this order a plurality of times.

7. The substrate processing method according to any one of claims 1 to 6, wherein the processing liquid contains sulfuric acid.

8. In the step of performing the plasma irradiation, a gas containing oxygen is supplied between the reactor and the upper surface of the substrate, the substrate processing method according to claim 7.

9. After the detection of the film thickness, while the reactor is lowered from a standby position above the substrate to a position facing the substrate, the gas is supplied into the gap space between the plasma generation source and the substrate, and as the reactor is lowered, the supply amount of the gas is decreased over time, the substrate processing method according to claim 8.

10. The substrate processing method according to any one of claims 1 to 9, wherein a resist film formed on the upper surface of the substrate is removed by the processing liquid.

11. further comprising a target value acquisition step of acquiring the target value, wherein the target value corresponds to any one of the type of the substrate, the type of the processing liquid, and the content of the processing with the processing liquid, and the substrate processing method according to any one of claims 1 to 10.

12. a substrate holding unit that holds the substrate in a horizontal posture and rotates it around a vertical axis; a processing liquid supply unit that supplies a processing liquid to the upper surface of the substrate held by the substrate holding unit; a control unit that supplies a predetermined amount of the processing liquid from the processing liquid supply unit and rotates the substrate by the substrate holding unit to form a liquid film of the processing liquid on the upper surface of the substrate; a film thickness measurement unit that measures the film thickness of the liquid film; a reactor that generates plasma; and a moving mechanism that moves the reactor between an opposing position close to and facing the upper surface of the substrate and a standby position separated from the upper surface of the substrate, wherein the reactor has a planar size equal to or larger than the planar size of the substrate and faces the entire upper surface of the substrate at the opposing position, the control unit has a film thickness calculation unit that calculates the film thickness from a signal from the film thickness measurement unit, and when the calculation result of the film thickness is a predetermined target value, positions the reactor at the opposing position and stops the rotation of the substrate, and performs plasma irradiation on the liquid film on the upper surface of the substrate, a substrate processing apparatus.

13. The substrate processing apparatus according to claim 12, further comprising a gas supply unit that supplies gas between the reactor and the upper surface of the substrate.

14. The substrate processing apparatus according to claim 13, wherein the gas supply unit has a gas nozzle that is integrally coupled to the reactor and discharges the gas.

15. The substrate processing apparatus according to claim 14, wherein the gas nozzle discharges the gas substantially horizontally from the peripheral edge side of the substrate toward the rotation center.

16. A step of holding the substrate in a horizontal posture; a step of supplying a processing liquid to the upper surface of the substrate and rotating the substrate around a vertical axis to form a liquid film of the processing liquid on the upper surface of the substrate; a step of detecting the film thickness of the liquid film; a step of arranging a plasma generation source facing the upper surface of the substrate and performing plasma irradiation on the liquid film from the plasma generation source when the detection result of the film thickness is a predetermined target value; wherein the formation of the liquid film, the detection of the film thickness, and the plasma irradiation are repeatedly executed a plurality of times in this order, a substrate processing method.

17. A step of holding the substrate in a horizontal posture; A step of supplying a processing liquid onto the upper surface of the substrate and rotating the substrate around a vertical axis to form a liquid film of the processing liquid on the upper surface of the substrate; A step of detecting the film thickness of the liquid film; A step of arranging a plasma generation source opposite to the upper surface of the substrate and performing plasma irradiation on the liquid film from the plasma generation source when the detection result of the film thickness is a predetermined target value; comprising; The processing liquid contains sulfuric acid; In the step of performing the plasma irradiation, a gas containing oxygen is supplied between the plasma generation source and the upper surface of the substrate; A substrate processing method, after detecting the film thickness, while lowering the plasma generation source from a standby position above the substrate to a facing position with the substrate, supplying the gas into the gap space between the plasma generation source and the substrate, and reducing the supply amount of the gas over time as the plasma generation source descends.

18. A substrate holding part that holds the substrate in a horizontal posture and rotates it around a vertical axis; A processing liquid supply part that supplies a processing liquid onto the upper surface of the substrate held by the substrate holding part; A control part that supplies a predetermined amount of the processing liquid from the processing liquid supply part and rotates the substrate by the substrate holding part to form a liquid film of the processing liquid on the upper surface of the substrate; A film thickness measurement part that measures the film thickness of the liquid film; A reactor that generates plasma; A moving mechanism that moves the reactor between a facing position close to and opposite to the upper surface of the substrate and a standby position spaced apart from the upper surface of the substrate; comprising; The processing liquid contains sulfuric acid; The control part has a film thickness calculation part that calculates the film thickness from a signal from the film thickness measurement part. When the calculation result of the film thickness is a predetermined target value, the reactor is positioned at the facing position to perform plasma irradiation on the liquid film on the upper surface of the substrate. After measuring the film thickness, the reactor is moved from the standby position above the substrate to the facing position with the substrate while supplying a gas containing oxygen into the gap space between the reactor and the substrate, and reducing the supply amount of the gas over time as the reactor descends. A substrate processing apparatus.

19. The plasma irradiation is performed under atmospheric pressure. The substrate processing method according to any one of Claims 1 to 11, 16, and 17.

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