Plating device

Abstract

In a plating apparatus, the thickness of the plating film formed on a substrate is determined with high precision. A plating apparatus comprises a plating tank for receiving a plating solution, a substrate holder for holding and supporting a substrate, an anode disposed within the plating tank so as to face the substrate held and supported in the substrate holder, a potential sensor disposed near the substrate held and supported in the substrate holder and configured to measure the potential of the plating solution, a database for storing reference data of the distribution of the potential near the substrate, wherein the reference data represents the potential distribution near the substrate in a predetermined reference state, a potential deviation calculation unit configured to calculate the deviation of the potential distribution measured by the potential sensor with respect to the reference data, and a film thickness calculation unit configured to calculate the deviation of the plating film thickness formed on the substrate from the plating film thickness in the reference state based on the deviation of the calculated potential distribution.

Description

Technology Field

[0001] The present invention relates to a plating device. Background Technology

[0002] A plating apparatus comprises a substrate holder that holds and supports a substrate, a plating tank that contains a plating solution, and an anode disposed within the plating tank so as to face the substrate held and supported by the substrate holder. In the plating apparatus, technology development is being carried out to improve the flatness of the film thickness of the plating formed on the substrate (see, for example, Patent Document 1). Prior art literature

[0003] Japanese Patent Publication No. 7373684 The problem to be solved

[0004] In a plating apparatus, it is desired to determine the thickness of the plating film formed on a substrate with higher precision. means of solving the problem

[0005] [Form 1] According to Form 1, a plating apparatus is provided comprising: a plating tank for receiving a plating solution; a substrate holder for holding and supporting a substrate; an anode disposed in the plating tank so as to face the substrate held and supported in the substrate holder; a potential sensor disposed near the substrate held and supported in the substrate holder and configured to measure the potential of the plating solution; a database for storing reference data of the distribution of the potential near the substrate, wherein the reference data represents the potential distribution near the substrate in a predetermined reference state; a potential deviation calculation unit configured to calculate the deviation of the potential distribution measured by the potential sensor with respect to the reference data; and a film thickness calculation unit configured to calculate the deviation of the plating film thickness formed on the substrate from the plating film thickness in the reference state based on the deviation of the calculated potential distribution.

[0006] [Form 2] According to Form 2, in the plating apparatus of Form 1, the reference data includes a plurality of reference data corresponding to different plating current values, and the potential deviation calculation unit is configured to calculate the deviation of the potential distribution using data interpolated from the plurality of reference data.

[0007] [Form 3] According to Form 3, in the plating apparatus of Form 2, the interpolated data corresponds to the value of the plating current when the potential is measured by the potential sensor.

[0008] [Form 4] According to Form 4, in a plating apparatus of Form 1, the reference data includes a plurality of reference data corresponding to a micro-processing pattern on the substrate, and the potential deviation calculation unit is configured to calculate the deviation of the potential distribution by using the reference data corresponding to the micro-processing pattern of the substrate being plated, which is the target of potential measurement by the potential sensor, among the plurality of reference data.

[0009] [Form 5] According to Form 5, in the plating apparatus of Form 1, the predetermined reference state is, at least, a state in which no power supply failure occurs between the substrate and the substrate holder.

[0010] [Form 6] According to Form 6, in the plating apparatus of Form 1, the predetermined reference state corresponds to a state in which a plating film is formed with a flatness higher than a predetermined threshold.

[0011] [Form 7] According to Form 7, the plating apparatus of Form 1 further comprises a plating process control unit configured to perform control according to the deviation of the plating film thickness calculated by the film thickness calculation unit.

[0012] [Form 8] According to Form 8, in the plating apparatus of Form 7, the control comprises at least one of (i) notification of an alarm, (ii) control of rotation of the substrate holder, (iii) control of the position of a shielding body for partially shielding the plating current in the plating solution, and (iv) control of stirring of the plating solution.

[0013] [Form 9] According to Form 9, in a plating apparatus of Form 1, a state-space model configured to estimate the current density flowing along the outer edge of the substrate using a state equation and an observation equation, wherein the state equation is an equation describing the time evolution of the current density flowing along the outer edge of the substrate and the observation equation is an equation describing the relationship between the current density flowing along the outer edge of the substrate and the potential of the plating solution at the position of the potential sensor, and further comprising a current density calculation unit configured to calculate the plating current density in an area inward from the outer edge of the substrate based on the current density estimated by the state-space model, and configured such that the output from the potential deviation calculation unit is input to the state-space model and the output from the current density calculation unit is input to the film thickness calculation unit.

[0014] [Form 10] According to Form 10, the plating apparatus of Form 9 comprises a plating module including at least the plating bath, the substrate holder, the anode, and the potential sensor, and the relationship between the current density and the potential of the plating solution is based on a function representing a 3D model of the plating module.

[0015] [Form 11] According to Form 11, in the plating apparatus of Form 9, the state-space model further comprises a Kalman filter configured to correct the estimation result of the current density flowing along the outer edge of the substrate based on the measurement value of the potential sensor.

[0016] [Form 12] According to Form 12, in the plating apparatus of Form 9, the outer edge of the substrate is a part that is held by the substrate holder of the substrate. Brief explanation of the drawing

[0017] FIG. 1 is a perspective view showing the overall configuration of the plating device of the present embodiment. FIG. 2 is a plan view showing the overall configuration of the plating device of the present embodiment. FIG. 3 is a cross-sectional view schematically showing the configuration of a plating module in one embodiment. Figure 4 is a plan view taken from the direction IV-IV in Figure 3. Figure 5 is a schematic diagram of the shield and substrate viewed from below. FIG. 6 is a block diagram showing the functional configuration of a control module according to one embodiment. Figure 7 is a plan view of the substrate. FIG. 8 is a block diagram showing the functional configuration of a control module according to another embodiment. Figure 9 is a diagram conceptually illustrating the processing by the potential deviation calculation unit. FIG. 10 is a diagram showing an exemplary database storing multiple reference data. Figure 11 is a diagram explaining the interpolation of reference data. Specific details for implementing the invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, identical or equivalent components are given the same reference numerals to omit redundant descriptions.

[0019] <First Embodiment>

[0020] FIG. 1 is a perspective view showing the overall configuration of a plating device according to the present embodiment. FIG. 2 is a plan view showing the overall configuration of a plating device according to the present embodiment. As shown in FIG. 1 and FIG. 2, the plating device (1000) comprises a load port (100), a conveying robot (110), an aligner (120), a pre-wet module (200), a pre-soak module (300), a plating module (400), a cleaning module (500), a spin rinse dryer (600), a conveying device (700), and a control module (800).

[0021] A load port (100) is a module for bringing in a substrate stored in a cassette, such as a FOUP, which is not shown in the plating device (1000), or for taking out a substrate from the plating device (1000) to the cassette. In this embodiment, four load ports (100) are arranged side by side in a horizontal direction, but the number and arrangement of load ports (100) are arbitrary. A transport robot (110) is a robot for transporting substrates and is configured to transport substrates between a load port (100), an aligner (120), and a transport device (700). When transporting substrates between the transport robot (110) and the transport device (700), the transport robot (110) and the transport device (700) may transport the substrates through a temporary stand which is not shown.

[0022] An aligner (120) is a module for aligning the position of an orientation flat or notch of a substrate in a predetermined direction. In this embodiment, two aligners (120) are arranged side by side in a horizontal direction, but the number and arrangement of the aligners (120) are arbitrary. The pre-wet module (200) replaces the air inside the pattern formed on the surface of the substrate with the treatment solution by wetting the plated surface of the substrate with a treatment solution such as pure water or degassed water before plating treatment. The pre-wet module (200) is configured to perform a pre-wet treatment that facilitates the supply of plating solution inside the pattern by replacing the treatment solution inside the pattern with a plating solution during plating. In this embodiment, two pre-wet modules (200) are arranged side by side in an up-down direction, but the number and arrangement of the pre-wet modules (200) are arbitrary.

[0023] The pre-soak module (300) is configured to perform a pre-soak treatment to clean or activate the under-plating surface by etching away, for example, an oxide film with high electrical resistance existing on the surface of a seed layer formed on the plated surface of a substrate prior to plating treatment, using a treatment solution such as sulfuric acid or hydrochloric acid. In this embodiment, two pre-soak modules (300) are arranged side by side in the vertical direction, but the number and arrangement of the pre-soak modules (300) are arbitrary. The plating module (400) performs a plating treatment on the substrate. In this embodiment, there are two sets of 12 plating modules (400) arranged side by side, with three in the vertical direction and four in the horizontal direction, and a total of 24 plating modules (400) are provided, but the number and arrangement of the plating modules (400) are arbitrary.

[0024] The cleaning module (500) is configured to perform a cleaning treatment on the substrate to remove plating solution and the like remaining on the substrate after the plating treatment. In this embodiment, two cleaning modules (500) are arranged side by side in the vertical direction, but the number and arrangement of the cleaning modules (500) are arbitrary. The spin rinse dryer (600) is a module for drying the substrate after the cleaning treatment by rotating it at high speed. In this embodiment, two spin rinse dryers are arranged side by side in the vertical direction, but the number and arrangement of the spin rinse dryers are arbitrary. The conveying device (700) is a device for conveying the substrate between a plurality of modules within the plating device (1000). The control module (800) is configured to control a plurality of modules of the plating device (1000) and can be configured, for example, as a general computer or a dedicated computer equipped with an input / output interface with an operator.

[0025] An example of a series of plating processes by a plating device (1000) is described. First, a substrate stored in a cassette is brought into a load port (100). Subsequently, a return robot (110) takes the substrate out of the cassette in the load port (100) and returns the substrate to an aligner (120). The aligner (120) aligns the position of the substrate, such as an orientation flat or notch, in a predetermined direction. The return robot (110) then transfers the substrate, which has been aligned by the aligner (120), to a return device (700).

[0026] The return device (700) returns the substrate received from the return robot (110) to the pre-wet module (200). The pre-wet module (200) performs a pre-wet treatment on the substrate. The return device (700) returns the substrate that has undergone the pre-wet treatment to the pre-soak module (300). The pre-soak module (300) performs a pre-soak treatment on the substrate. The return device (700) returns the substrate that has undergone the pre-soak treatment to the plating module (400). The plating module (400) performs a plating treatment on the substrate.

[0027] The return device (700) returns the substrate that has undergone plating treatment to the cleaning module (500). The cleaning module (500) performs a cleaning treatment on the substrate. The return device (700) returns the substrate that has undergone cleaning treatment to the spin rinse dryer (600). The spin rinse dryer (600) performs a drying treatment on the substrate. The return device (700) transfers the substrate that has undergone drying treatment to the return robot (110). The return robot (110) returns the substrate received from the return device (700) to the cassette of the load port (100). Finally, the cassette containing the substrate is discharged from the load port (100).

[0028] In addition, the configuration of the plating device (1000) described in FIG. 1 or FIG. 2 is merely an example, and the configuration of the plating device (1000) is not limited to the configuration of FIG. 1 or FIG. 2.

[0029] Next, the configuration of the plating module (400) is described. Since the 24 plating modules (400) in this embodiment have the same configuration, only one plating module (400) is described. FIG. 3 is a cross-sectional view schematically showing the configuration of the plating module (400) according to one embodiment. The plating module (400) is provided with a plating tank for receiving a plating solution. The plating tank is configured to include a cylindrical inner tank (412) with an open top surface and an outer tank (not shown) provided around the inner tank (412) to collect the plating solution that overflows from the upper edge of the inner tank (412).

[0030] The plating module (400) is provided with a substrate holder (440) for holding and supporting a substrate Wf with the surface to be plated Wf-a facing downward. The substrate holder (440) is provided with a power supply contact for supplying power to the substrate Wf from a power source not shown. The plating module (400) is also provided with a lifting mechanism (442) for raising and lowering the substrate holder (440). In addition, in one embodiment, the plating module (400) is provided with a rotation mechanism (448) for rotating the substrate holder (440) around a vertical axis. The substrate holder (440) can be rotated in a forward direction (e.g., clockwise) and a reverse direction (e.g., counterclockwise) by the rotation mechanism (448), and it is also possible to change the rotation speed. Such rotation of the substrate holder (440) is controlled by a control module (800). Additionally, the lifting mechanism (442) and the rotating mechanism (448) can be realized by known mechanisms, such as a motor, for example.

[0031] The plating module (400) is provided with a membrane (420) that divides the interior of the inner tank (412) in the vertical direction. The interior of the inner tank (412) is divided into a cathode region (422) and an anode region (424) by the membrane (420). A plating solution is filled in each of the cathode region (422) and the anode region (424). In addition, although an example in which the membrane (420) is provided has been shown in this embodiment, the membrane (420) does not need to be provided.

[0032] An anode (430) is provided on the bottom surface of the inner tank (412) of the anode region (424). Additionally, an anode mask (426) for adjusting the electric field between the anode (430) and the substrate Wf is disposed in the anode region (424). The anode mask (426) is a roughly plate-shaped member made of, for example, a dielectric material, and is provided on the front surface of the anode (430) (above the anode (430) in FIG. 3). The anode mask (426) has an opening through which the current flowing between the anode (430) and the substrate Wf passes. The anode mask (426) is configured to allow the opening dimensions to be changed, and the opening dimensions may be adjusted by a control module (800). The opening dimensions refer to the diameter when the opening is circular, and the length of one side or the maximum opening width when the opening is polygonal. Changes to the opening dimensions in the anode mask (426) may be made using known mechanisms. Although an example in which the anode mask (426) is provided has been shown in this embodiment, the anode mask (426) does not need to be provided. Additionally, the above-mentioned membrane (420) may be provided in the opening of the anode mask (426).

[0033] In the cathode region (422), a resistor (450) is disposed facing the membrane (420). The resistor (450) is a component for promoting uniformity of the plating process on the plating surface Wf-a of the substrate Wf. In one embodiment, the resistor (450) is configured to be movable in the up and down direction within the plating bath by means of a driving mechanism (452), and the position of the resistor (450) is adjusted by a control module (800). However, the plating module (400) does not need to have a resistor (450). The specific material of the resistor (450) is not particularly limited, but as an example, a porous resin such as polyetheretherketone may be used.

[0034] Near the surface of the substrate Wf in the cathode region (422), an unillustrated paddle is provided for stirring the plating solution. The paddle is made of, for example, titanium (Ti) or resin. By reciprocating parallel to the surface of the substrate Wf, the paddle stirs the plating solution so that sufficient metal ions are uniformly supplied to the surface of the substrate Wf during plating of the substrate Wf. The paddle may also be configured to move perpendicularly to the surface of the substrate Wf. The movement of the paddle is controlled by the control module (800) by a driving mechanism not illustrated. Additionally, the plating module (400) may not have a paddle.

[0035] Additionally, a potential sensor (470) is provided in the cathode region (422). If a resistor (450) is provided in the cathode region (422), the potential sensor (470) may be provided between the substrate Wf and the resistor (450). The potential sensor (470) is supported by a sensor support (468). Alternatively, the potential sensor (470) may be supported by a side wall of the inner tank (412) or by a resistor (450) instead of the sensor support (468). Additionally, the sensor support (468) may be a paddle for stirring the plating solution. Here, it is preferable that the paddle moves parallel to the plate surface of the substrate Wf to stir the plating solution, but it is not limited to this example. In this embodiment, a plurality of potential sensors (470) are provided along the radial direction of the substrate Wf. However, it is not limited to such examples, and the plating module (400) may be provided with at least one potential sensor (470).

[0036] FIG. 4 is a plan view taken in the direction IV-IV of FIG. 3. As shown in FIG. 3 and FIG. 4, the potential sensor (470) is positioned at a first location within the area between the substrate Wf and the anode (430). That is, the potential sensor (470) is positioned between the substrate Wf and the anode (430) in a direction perpendicular to the plate surface of the substrate Wf, and is positioned at a location that overlaps with the substrate Wf when viewed from a direction perpendicular to the plate surface of the substrate Wf. It is preferable that the potential sensor (470) be positioned close to the plated surface Wf-a, and as an example, the distance between the potential sensor (470) and the plated surface Wf-a is hundreds of micrometers, several millimeters, or tens of millimeters. The potential sensor (470) detects the potential at the position (first location) between the substrate Wf and the anode (430).

[0037] A second potential sensor (472a) and a third potential sensor (472b) may be provided within the plating tank (410). The second potential sensor (472a) and the third potential sensor (472b) are placed in a location within the plating tank (410) where there is relatively little change in potential. Specifically, the second potential sensor (472a) and the third potential sensor (472b) are placed in a second location and a third location outside the area between the substrate Wf and the anode (430). That is, as shown in FIG. 4, the second potential sensor (472a) and the third potential sensor (472b) are placed in a location that does not overlap with the substrate Wf when viewed from a direction perpendicular to the plate surface of the substrate Wf. The second potential sensor (472a) and the third potential sensor (472b) detect the potential at a placement location (second location, third location) spaced apart from the substrate Wf and the anode (430). The second and third potential sensors (472a, 472b) are supported by sensor supports (469a, 469b). Additionally, the second and third potential sensors (472a, 472b) may be supported by the side wall of the inner tank (412) or a resistor (450), etc., instead of the sensor supports (469a, 469b).

[0038] Each of the potential sensor (470), the second potential sensor (472a), and the third potential sensor (472b) may be composed of electrodes of the same material and / or the same shape, for example. As the electrode material, at least one of platinum (Pt), gold (Au), carbon (C), and copper (Cu) may be used.

[0039] Detection signals from the potential sensor (470), the second potential sensor (472a), and the third potential sensor (472b) are input to the control module (800). The control module (800) can estimate the thickness of the plating film formed on the substrate Wf based on the detection value of the potential from the potential sensor (470), or based on the detection signals from the potential sensor (470), the second potential sensor (472a), and the third potential sensor (472b). As an example, the control module (800) can estimate the distribution of plating current within the substrate surface undergoing plating processing based on the detection signal from the potential sensor (470), and estimate the film thickness distribution of the plating film on the substrate based on the estimated distribution of plating current.

[0040] Additionally, the control module (800) may detect the end point of the plating process based on the detection value of the potential sensor (470) and may predict the time until the end point of the plating process. For example, the control module (800) may terminate the plating process when the film thickness of the plating film estimated based on the detection value of the potential sensor (470) reaches a desired thickness. Also, for example, the control module (800) may calculate the film thickness increase rate from the film thickness of the plating film estimated based on the detection value of the potential sensor (470), and predict the time until the plating film reaches a desired thickness, i.e., the time until the end point of the plating process, based on the obtained film thickness increase rate.

[0041] Returning to FIG. 3, in one embodiment, a shield (480) is provided in the cathode region (422) to partially or locally shield the current flowing from the anode (430) to the substrate Wf. The shield (480) is, for example, a roughly plate-shaped member made of a dielectric material. FIG. 5 is a schematic diagram of the shield (480) and the substrate Wf of this embodiment viewed from below. Also, in FIG. 5, the illustration of the substrate holder (440) that holds and supports the substrate Wf is omitted. The shield (480) is configured to be movable to a shield position interposed between the plated surface Wf-a of the substrate Wf and the anode (430) (a position indicated by a dashed line in FIG. 3 and FIG. 5) and to a retracted position retracted from between the plated surface Wf-a and the anode (430) (a position indicated by a solid line in FIG. 3 and FIG. 5). In other words, the shield (480) is configured to be movable to a shield position located below the plated surface Wf-a and to a retracted position located away from the plated surface Wf-a. The position of the shield (480) is controlled by a control module (800) by a driving mechanism not shown. The movement of the shield (480) can be realized by a known mechanism such as a motor or a solenoid. In the example shown in FIG. 3 and FIG. 5, the shield (480) shields a portion of the periphery of the outer area of ​​the plated surface Wf-a of the substrate Wf at the shield position. Also, in the example shown in FIG. 5, the shield (480) is formed in a tapered shape that tapers toward the center of the substrate Wf. However, it is not limited to these examples, and the shield (480) may use any shape that is predetermined by experiment, etc.

[0042] The plating process in the plating module (400) is described. By using a lifting mechanism (442), the substrate Wf is immersed in the plating solution of the cathode region (422), thereby exposing the substrate Wf to the plating solution. In this state, the plating module (400) can perform plating on the surface to be plated Wf-a of the substrate Wf by applying a voltage between the anode (430) and the substrate Wf. In addition, in one embodiment, the plating process is performed while rotating the substrate holder (440) using a rotating mechanism (448). Through the plating process, a conductive film (plating film) is deposited on the surface to be plated Wf-a of the substrate Wf. During the plating process, the potential is measured by a potential sensor (470). By performing a measurement by the potential sensor (470) accompanied by the rotation of the substrate holder (440) (substrate Wf), the measurement position of the potential sensor (470) can be changed, and the potential can be measured at multiple points in the circumferential direction of the substrate Wf, or over the entire circumferential direction. Then, the control module (800) estimates the film thickness of the plating film based on the detected value of the potential by the potential sensor (470). By doing so, the change in the film thickness of the plating film formed on the plated surface Wf-a of the substrate Wf during the plating process can be determined in real time.

[0043] FIG. 6 is a block diagram showing the functional configuration of a control module (800) according to one embodiment of a plating device (1000). The control module (800) is configured to estimate the distribution of current density flowing through a substrate Wf during plating processing using a state space model (804). The state space model (804) includes a state estimation unit (806), an observation value calculation unit (808), and a Kalman filter (810). In addition to the state space model (804), the control module (800) is equipped with a 3D model creation unit (802), a current density calculation unit (812), a film thickness calculation unit (814), and an endpoint determination unit (816). The control module (800) can be configured as a computer equipped with an input / output device, a computing device, a memory device, etc. For example, the control module (800) is configured to realize the functions of each part (802, 806, 808, 810, 812, 814, 816) by having an arithmetic unit (e.g., a processor) read and execute a computer program stored in a memory device.

[0044] The 3D model creation unit (802) creates a three-dimensional (3D) model of the plating module (400). The 3D model of the plating module (400) is data that describes the shape, arrangement, and physical property values ​​of various components in the plating module (400) by modeling them. This 3D model includes at least, components that affect the electric field inside the plating tank (inner tank (412)) of the plating module (400). Such components include, for example, an anode (430), an anode mask (426), a membrane (420), a resistor (450), a substrate Wf, a seed layer provided on the substrate Wf, a plating solution contained in the plating tank, and a potential sensor (470). The 3D model of the plating module (400) can be constructed based on information regarding the shape, arrangement, and physical property values ​​(e.g., conductivity, dielectric constant, etc.) of each of these components. For example, this information may be input to the control module (800) through the input / output interface of the control module (800) by an operator of the plating device (1000), and the 3D model creation unit (802) may create a 3D model of the plating module (400) based on the input information. Some of the information, for example, some physical property values, may be stored in advance in the memory of the control module (800), and the operator may select an appropriate value from among them.

[0045] The state estimation unit (806) is configured to estimate the "state" of the plating module (400) using a state equation. Specifically, the state estimation unit (806) estimates the current density of the plating current at the outer edge of the substrate Wf as the "state" of the plating module (400).

[0046] FIG. 7 shows a plan view of a substrate Wf. The outer edge (62) of the substrate Wf is the part where the substrate Wf is held by the substrate holder (440) and is not exposed to the plating solution. As shown in FIG. 7, the substrate Wf has one or more electrical contacts (441) on the outer edge (62). In the example of FIG. 7, the substrate Wf has six electrical contacts (441) at equal intervals on the outer edge (62). The electrical contacts (441) are connected to the terminals of a power source (not shown) through electrical wiring (not shown) embedded in the substrate holder (440), and plating current flows through the electrical contacts (441) to the substrate Wf.

[0047] In the following, the current density of the plating current at the outer edge (62) of the substrate Wf is referred to as the "outer edge current density," and the outer edge current density at time t is j t Described as (θ). However, θ represents a position within the outer edge (62) of the substrate Wf measured as an angle around the center of the substrate Wf (see FIG. 7). Here, the outer edge current density j t (θ) is expressed as a Fourier series as follows.

[0048]

[0049] outer edge current density j t The estimation of (θ) is the Fourier coefficient a i,t and b i,t It results in the estimation of. In one embodiment, the state estimation unit (806) uses the state equation of the following formula to estimate the outer edge current density j at time t-1. t-1 The outer margin current density j at time t from (θ) t Estimate (predict) (θ).

[0050]

[0051] However, the matrix Fi is given by the following equation and represents the rotation of the substrate Wf using the rotation mechanism (448). Also, the vector vt is noise. In this model, it is assumed that the outer edge current density at time t is given by rotating the outer edge current density at time t-1 in conjunction with the rotation of the substrate Wf. Furthermore, in the following equation, ω is the angular velocity of the rotation of the substrate Wf, and Δt is the time step (i.e., the time difference between time t and time t-1).

[0052]

[0053] In addition, to estimate the outer edge current density, a state equation different from the above equation may be used.

[0054] The observation value calculation unit (808) is configured to estimate an "observation value" from the "state" of the plating module (400) using an observation equation. Specifically, the observation value calculation unit (808) estimates the value of the potential of the plating solution in the plating bath, which is expected to be measured by the potential sensor (470), as an "observation value" in the plating module (400), with respect to the outer edge current density j t It is estimated (calculated) from (θ). Hereinafter, the value calculated by this observation value calculation unit (808) is referred to as the "potential estimate value," and the potential estimate value at time t is φ t Described as.

[0055] As described above, the potential measured by the potential sensor (470) is the potential near the plating surface Wf-a of the substrate Wf where the plating process is being performed. This potential is determined by the distribution of the plating current flowing from the plating solution in the plating bath to the substrate Wf. Furthermore, this distribution of the plating current depends on the physical structure of the plating module (400). Accordingly, the estimated potential value φ t It is possible to calculate this using the 3D model of the plating module (400) created in the 3D model creation unit (802). That is, the dislocation estimate value φ t It can be expressed as follows.

[0056]

[0057] Here, F is a function representing a 3D model of the plating module (400), and a i,t , b i,t The etc. are the outer edge current density j described above. t These are the Fourier coefficients of (θ). Additionally, the function F can be numerically determined based on the 3D model obtained from the 3D model creation unit (802). The function F of the above equation is also as follows, a i,t =0 and b i,t Taylor expansion is performed around =0. Additionally, the following equation is an approximation up to the first-order term, but terms of the second order or higher may be considered.

[0058]

[0059] In one embodiment, the observation value calculation unit (808) uses the following observation equation to calculate the outer edge current density j at time t. t Estimated potential φ at time t from (θ) t Calculates. Where w t is noise.

[0060]

[0061] This observation equation is based on the equation of the Taylor expansion of the function F representing the 3D model of the plating module (400) shown above. In addition, the dislocation estimate φ t To obtain this, a different observation equation may be used.

[0062] The Kalman filter (810) is configured to correct the "state" of the plating module (400) estimated by the state estimation unit (806) using actual measurement results in the plating module (400). Specifically, the Kalman filter (810) uses the actual measured value of the potential obtained from the potential sensor (470) for correction. In one embodiment, the Kalman filter (810) uses the measured value of the potential obtained from the potential sensor (470) and the estimated value of the potential φ calculated by the observation value calculation unit (808). t According to the difference, the outer edge current density j estimated by the state estimation unit (806) t (θ)(i.e., Fourier coefficient a i,t and b i,t Corrects )

[0063] In addition, as described above, since the substrate Wf is rotated by the rotation mechanism (448), the potential sensor (470) obtains the potential measurement values ​​at multiple measurement points along the circumferential direction of the substrate Wf. Therefore, by making corrections based on the measurement values ​​at these multiple measurement points, an accurate outer edge current density can be obtained.

[0064] In this way, the outer edge current density j estimated and corrected using the state-space model (804) t(θ) is output to the current density calculation unit (812). The current density calculation unit (812) calculates the current density of the plating current in the region (64) (see FIG. 7) that is inner to the outer edge (62) of the substrate Wf, based on the outer edge current density obtained from the state space model (804). Unlike the outer edge (62) of the substrate Wf, the region (64) is not held by the substrate holder (440) and is exposed to the plating solution. Current flows into the region (64) from the plating solution in the plating bath. That is, the current density calculation unit (812) calculates the current density of the current flowing into the substrate Wf from the plating solution in the plating bath through the interface between the plating solution and the substrate Wf. The thickness of the plating film formed on the substrate Wf depends on this current density. In the following description, this current density is simply referred to as "plating current density," and the plating current density at position k and time t on the substrate Wf (region (64)) is j k,t Described as.

[0065] Plating current density j k,t is the outer edge current density j t (θ) is associated with a specific relationship. Specifically, the plating current density is determined by the outer edge current density and the physical structure of the plating module (400). Therefore, the plating current density j k,t is the aforementioned potential estimate φ t Likewise, using a 3D model of the plating module (400), it can be expressed as follows.

[0066]

[0067] Here, G k is a function representing a 3D model of the plating module (400), and a i,t , b i,t The edum is the outer edge current density j t These are the Fourier coefficients of (θ). Function G kThis can be numerically determined based on the 3D model of the plating module (400) obtained from the 3D model creation unit (802). The function G of the above equation k , also as follows, a i,t =0 and b i,t Taylor expansion is performed around =0. Additionally, the following equation is an approximation up to the first-order term, but terms of the second order or higher may be considered.

[0068]

[0069] In one embodiment, the current density calculation unit (812) calculates the plating current density j using the above formula. k,t It can produce.

[0070] The film thickness calculation unit (814) is the plating current density j obtained from the current density calculation unit (812). k,t Based on this, the film thickness of the plating formed on the substrate Wf is configured to calculate. In one embodiment, the film thickness calculation unit (814) calculates the plating film formation rate v at position k and time t on the substrate Wf using the following formula. k,t and film thickness w k,t Calculates.

[0071]

[0072] However, M and ρ are the molecular weight and density of the plating deposited on the substrate Wf, z is the valence of the plating reaction, and F is the Faraday constant. The film thickness calculation unit (814) predicts the future plating current density and film formation rate using the equation of state described above, thereby determining the current film thickness w k,t Rather, the film thickness w at the end of the plating process (time t=T). k,T It is acceptable to calculate .

[0073] The endpoint determination unit (816) determines the endpoint of the plating process for the substrate Wf based on the plating film thickness obtained by the film thickness calculation unit (814). For example, the endpoint determination unit (816) determines the endpoint of the plating process for the substrate Wf based on the estimated current film thickness w k,t The plating process may be terminated when the desired thickness is reached, or, the estimated current film thickness w k,t and predicted future Tabernacle speed v k,s Based on (s=t, …, T), the time to the end of the plating process may be predicted.

[0074] As described above, according to the plating apparatus (1000) of the present embodiment, the thickness of the plating film can be estimated based on the measurement value of the potential sensor (470) by using a state-space model. By doing so, the change in the thickness of the plating film formed on the plated surface Wf-a of the substrate Wf during the plating process can be determined in real time.

[0075] <Second Embodiment>

[0076] FIG. 8 is a block diagram showing the functional configuration of a control module (801) according to another embodiment. The control module (801) of this embodiment is configured to calculate the deviation from the reference state of the film thickness distribution of the plating film formed on the substrate Wf based on the deviation from the reference state of the potential distribution measured by the potential sensor (470). For example, when plating treatment is performed on the substrate Wf in an imperfect state, such as when a power supply failure occurs between some of the electrical contacts (441) (see FIG. 7) provided on the substrate Wf and the substrate holder (440), there may be irregularities (concave and / or convex parts) caused by power supply failure, etc., in the signal indicating the potential distribution near the substrate obtained from the potential sensor (470). Meanwhile, when a substrate Wf having a micro-processing pattern on the plating surface Wf-a is the target for plating, even if plating is performed in an ideal state, irregularities according to the micro-processing pattern may appear in the potential distribution signal from the potential sensor (470). Accordingly, as described in detail below, the control module (801) of the present embodiment can calculate the deviation of the film thickness distribution actually formed on the substrate Wf from the film thickness distribution obtained when plating is performed in an ideal state by using the difference between the potential distribution obtained from the potential sensor (470) and the potential distribution in an ideal state (reference state).

[0077] The plating device (1000) may be equipped with a control module (801) according to the present embodiment instead of the control module (800) of the first embodiment (Fig. 6) described above, or in addition to the control module (800).

[0078] As illustrated in FIG. 8, the control module (801) comprises a 3D model creation unit (802), a state space model (804), a current density calculation unit (812), a film thickness calculation unit (814), a database (818), a potential deviation calculation unit (820), and a plating process control unit (822). The state space model (804) includes a state estimation unit (806), an observation value calculation unit (808), and a Kalman filter (810). The 3D model creation unit (802), the state space model (804), the state estimation unit (806), the observation value calculation unit (808), the Kalman filter (810), the current density calculation unit (812), and the film thickness calculation unit (814) in the control module (801) are identical to the corresponding units in the control module (800) of the first embodiment described above. Similar to the control module (800), the control module (801) can be configured as a computer equipped with an input / output device, an arithmetic unit, a memory device, etc. For example, the control module (801) is configured to realize the functions of each part (802, 806, 808, 810, 812, 814, 820, 822) by having an arithmetic unit (e.g., a processor) read and execute a computer program stored in a memory device.

[0079] The database (818) stores reference data of the potential distribution in the vicinity of the substrate Wf. The reference data is data representing the potential distribution in the vicinity of the substrate Wf in a predetermined reference state. In this specification, "a predetermined reference state" means a state in which it is possible to perform plating treatment on the substrate Wf ideally. For example, the predetermined reference state may be a state in which no power supply failure occurs between the electrical contact (441) on the substrate Wf and the substrate holder (440), or more generally, a state in which each part of the plating module (400) is appropriately set so that a plating film can be formed on the substrate Wf with a certain degree of flatness. Reference data of the potential distribution in the vicinity of the substrate in such a reference state can be obtained by performing plating treatment on the substrate Wf in the reference state in advance and measuring the potential in the vicinity of the substrate Wf using a potential sensor (470) at that time, and can be stored in the database (818).

[0080] The potential distribution of the reference data may be, for example, the potential distribution near the substrate along the circumferential direction of the substrate Wf. As described above, by performing a plating process while rotating the substrate Wf by the rotation mechanism (448), potential measurement values ​​at multiple points along the circumferential direction of the substrate Wf (or across the entire circumferential direction) are obtained from the potential sensor (470). A series of potential measurement values ​​in the reference state obtained in this way can be stored in the database (818) as reference data representing the potential distribution along the circumferential direction of the substrate Wf. Furthermore, the potential distribution near the substrate Wf depends on the magnitude of the plating current or the micro-processing pattern formed or existing on the plated surface Wf-a of the substrate Wf. Therefore, reference data for each of these various conditions may be stored in the database (818).

[0081] The potential deviation calculation unit (820) is configured to calculate the deviation of the potential distribution measured by the potential sensor (470) relative to the reference data. FIG. 9 is a diagram conceptually illustrating the processing by the potential deviation calculation unit (820). In each graph of FIG. 9, the horizontal axis represents the position (angle) (see FIG. 7) in the circumferential direction of the substrate Wf, and the vertical axis represents the potential. Graph (901) in FIG. 9 represents an example of the potential distribution measured by the potential sensor (470). This potential distribution includes a peak (904) caused by a power supply failure between the electrical contact (441) on the substrate Wf and the substrate holder (440), and peaks (905 and 906) caused by a micro-processing pattern on the plated surface Wf-a of the substrate Wf. Graph (902) in FIG. 9 represents an example of the reference data. As described above, since the reference data is a potential distribution in a reference state, the potential distribution of the graph (902) includes peaks (905 and 906) corresponding to the micro-processing pattern, but does not include peaks corresponding to power supply failure. The graph (903) in FIG. 9 represents the deviation of the potential distribution calculated by the potential deviation calculation unit (820), and is obtained by subtracting the potential distribution of the graph (902) (reference data) from the potential distribution of the graph (901) (potential distribution measured by the potential sensor (470)). As a result of the subtraction, the graph (903) has only peaks (904) corresponding to power supply failure.

[0082] Additionally, before subtracting the potential distribution of graph (902) from the potential distribution of graph (901), an offset of reference data may be performed so that the average levels of both match. Additionally, the database (818) may store multiple reference data corresponding to each of the values ​​of multiple plating currents and multiple micro-processing patterns, for example as shown in FIG. 10, and the potential deviation calculation unit (820) may select reference data corresponding to the plating process currently being performed from the database (818) and use that reference data to calculate the deviation of the potential distribution. Additionally, the potential deviation calculation unit (820) may generate reference data corresponding to the current plating current by interpolating the reference data stored in the database (818) and use that to calculate the deviation of the potential distribution. For example, the potential deviation calculation unit (820) can generate reference data corresponding to a plating current of 4 amperes that is not stored in the database (818) by interpolation using reference data corresponding to a plating current of 3 amperes and reference data corresponding to a plating current of 5 amperes, as shown in FIG. 11.

[0083] In this way, in the control module (801) according to the present embodiment, a potential deviation calculation unit (820) is used to calculate a deviation in the potential distribution (i.e., the graph (903) in FIG. 9) that occurs when the plating process is performed in a non-ideal state (e.g., a state of poor power supply). The deviation in the potential distribution calculated by the potential deviation calculation unit (820) is input into the state space model (804). In the control module (801) of the present embodiment, the state space model (804), the current density calculation unit (812), and the film thickness calculation unit (814) are configured in the same way as the corresponding parts in the control module (800) of the first embodiment described above. Therefore, from the film thickness calculation unit (814), the film thickness (distribution) according to the deviation of the potential distribution calculated by the potential deviation calculation unit (820), that is, the film thickness formed on the substrate Wf currently undergoing plating treatment, is output as a deviation (distribution) from the film thickness formed on the substrate Wf in a reference state. In other words, the film thickness calculation unit (814) in the control module (801) of the present embodiment can calculate the deviation (distribution) of the film thickness formed on the substrate Wf that occurs when the plating treatment is performed in a non-ideal state (e.g., a state of poor power supply). By this, the thickness of the plating film formed on the substrate Wf can be determined with high precision, and it is also possible to easily determine whether the plating process is being performed in an ideal state in the plating device (1000).

[0084] The plating process control unit (822) is configured to perform control based on the deviation of the plating film thickness calculated by the film thickness calculation unit (814). For example, the plating process control unit (822) may notify the operator of the plating device (1000) of an alarm using voice, text, image, sound, light, etc., when the deviation of the film thickness calculated by the film thickness calculation unit (814) is greater than a predetermined threshold. Additionally, the plating process control unit (822) may control the rotation mechanism (448) to change or adjust the rotation direction or rotation speed of the substrate holder (440) according to the magnitude of the deviation of the film thickness calculated by the film thickness calculation unit (814). Additionally, the plating process control unit (822) may control the position of the shielding body (480) between a shielding position and a withdrawal position according to the distribution of the misalignment of the film thickness calculated by the film thickness calculation unit (814), or control the presence or absence of stirring of the plating solution by the paddle or the stirring intensity. By controlling these, the flatness of the plating film formed on the substrate Wf can be improved.

[0085] Although embodiments of the present invention have been described above based on a few examples, the above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from its spirit, and it is understood that the present invention includes equivalents. Furthermore, any combination or omission of each component described in the claims and specification is possible within the scope of solving at least a part of the above-described problem or within the scope of exhibiting at least a part of the effect. Explanation of the symbols

[0086] 1000: Plating device 100: Load port 110: Return robot 120: Aligner 200: Pre-wet Module 300: Free Soak Module 400: Plating Module 500: Cleaning Module 600: Spin Rinse Dryer 700: Return device 800: Control Module 412: Supportive wife 420: Membrane 422: Cathode region 424: Anode area 426: Anode Mask 430: Anode 440: Substrate holder 441: Electrical contact 442: Elevator 448: Rotating mechanism 450: Resistor 452: Driving mechanism 468: Sensor support 470: Potential sensor 480: Shield 801: Control Module 802: 3D Model Creation Section 804: State-space model 806: State Estimation Section 808: Observation Calculation Unit 810: Kalman filter 812: Current Density Calculation Unit 814: Film thickness calculation section 816: Terminal Determination Unit 818: Database 820: Potential deviation calculation unit 822: Plating Process Control Unit 62: outer edge

Claims

Claim 1 A plating apparatus comprising: a plating tank for receiving a plating solution; a substrate holder for holding and supporting a substrate; an anode disposed within the plating tank so as to face the substrate held and supported in the substrate holder; a potential sensor disposed near the substrate held and supported in the substrate holder and configured to measure the potential of the plating solution; a database storing reference data of the potential distribution near the substrate, wherein the reference data represents the potential distribution near the substrate in a predetermined reference state; a potential deviation calculation unit configured to calculate the deviation of the potential distribution measured by the potential sensor with respect to the reference data; and a film thickness calculation unit configured to calculate the deviation of the plating film thickness formed on the substrate from the plating film thickness in the reference state based on the deviation of the calculated potential distribution. Claim 2 A plating apparatus according to claim 1, wherein the reference data includes a plurality of reference data corresponding to different plating current values, and the potential deviation calculation unit is configured to calculate the deviation of the potential distribution using data interpolated from the plurality of reference data. Claim 3 In paragraph 2, the plating device, wherein the interpolated data corresponds to the value of the plating current when the potential is measured by the potential sensor. Claim 4 A plating apparatus according to claim 1, wherein the reference data comprises a plurality of reference data according to a micro-processing pattern on the substrate, and the potential deviation calculation unit is configured to calculate the deviation of the potential distribution by using the reference data among the plurality of reference data that corresponds to the micro-processing pattern of the substrate undergoing plating treatment, which is the target of potential measurement by the potential sensor. Claim 5 A plating apparatus according to any one of claims 1 to 4, wherein the predetermined reference state is, at least, a state in which no power supply failure occurs between the substrate and the substrate holder. Claim 6 A plating apparatus according to any one of claims 1 to 4, wherein the predetermined reference state corresponds to a state in which a plating film is formed with a flatness higher than a predetermined threshold. Claim 7 A plating apparatus comprising, in any one of claims 1 to 4, a plating process control unit configured to perform control according to the deviation of the plating film thickness calculated by the film thickness calculation unit. Claim 8 A plating apparatus according to claim 7, wherein the control comprises at least one of (i) notification of an alarm, (ii) control of rotation of the substrate holder, (iii) control of the position of a shielding body for partially shielding the plating current in the plating solution, and (iv) control of stirring of the plating solution. Claim 9 A plating apparatus according to any one of claims 1 to 4, comprising a state space model configured to estimate a current density flowing along the outer edge of a substrate using a state equation and an observation equation, wherein the state equation is an equation describing the time evolution of the current density flowing along the outer edge of the substrate, and the observation equation is an equation describing the relationship between the current density flowing along the outer edge of the substrate and the potential of the plating solution at the position of the potential sensor, and further comprising a current density calculation unit configured to calculate a plating current density in an area inward from the outer edge of the substrate based on the current density estimated by the state space model, wherein the output from the potential deviation calculation unit is input to the state space model and the output from the current density calculation unit is input to the film thickness calculation unit. Claim 10 A plating apparatus according to claim 9, comprising a plating module including at least the plating bath, the substrate holder, the anode, and the potential sensor, wherein the relationship between the current density and the potential of the plating solution is based on a function representing a 3D model of the plating module. Claim 11 In claim 9, the plating apparatus further comprises a Kalman filter configured to correct the estimation result of the current density flowing along the outer edge of the substrate based on the measurement value of the potential sensor. Claim 12 In claim 9, the plating device wherein the outer edge of the substrate is a portion of the substrate that is held by the substrate holder of the substrate.

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