Control apparatus, substrate processing apparatus, and substrate processing method

Abstract

To provide a control apparatus, a substrate processing apparatus, and a substrate processing method that can achieve controllability that cannot be obtained with conventional control using feedback control when controlling the amount of state in substrate processing by the substrate processing apparatus.SOLUTION: A control apparatus that controls the amount of state in a substrate processing apparatus that performs processing on substrates comprises: a feedback controller that provides control signals to the controlled object based on the deviation between the target value of the amount of state and the detected value by a detector; and a correction value calculation section that obtains the deviation ej in the jth substrate process (j is an integer greater than or equal to 1) and calculates a correction value to be added to the control signal in the j+1th substrate process from the feedback controller so that the deviation ej+1 in the j+1th substrate process is smaller than the deviation ej.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a control device, a substrate processing apparatus, and a substrate processing method. [Background technology]

[0002] In the manufacturing process of semiconductor devices, substrate processing such as film formation and etching is performed in a processing chamber. In a substrate processing apparatus for performing such substrate processing, it is important to control state quantities such as temperature, pressure, and gas flow rate.

[0003] Feedback control is generally used for controlling state quantities in substrate processing apparatus. For example, Patent Document 1 describes the use of feedback-based control for temperature control in a heat treatment apparatus for semiconductor devices. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-183072 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a control device, a substrate processing apparatus, and a substrate processing method that can achieve controllability that cannot be obtained by conventional feedback control when controlling state quantities during substrate processing by a substrate processing apparatus. [Means for solving the problem]

[0006] A control device according to one aspect of the present disclosure is a control device for controlling a state quantity in a substrate processing apparatus that processes a substrate, the control device including: a feedback controller that gives a control signal to a controlled object based on a deviation between a target value of the state quantity and a detection value by a detector; and a deviation e between the target value and the detection value in a j-th substrate processing (j is an integer equal to or greater than 1). jThe deviation e between the target value and the detected value during the j+1th substrate processing is obtained. j+1 is the deviation e j and a correction value calculation unit that calculates a correction value to be added to the control signal from the feedback controller during the processing of the j+1th substrate so that the correction value is smaller than Effect of the Invention

[0007] According to the present disclosure, there is provided a control device, a substrate processing apparatus, and a substrate processing method that can achieve controllability that cannot be obtained by conventional feedback control when controlling state quantities in substrate processing by a substrate processing apparatus. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a control block diagram for conventional general feedback control. [Diagram 2] 1 is a cross-sectional view showing an example of a film forming apparatus as a substrate processing apparatus to which a control device according to an embodiment is applied; [Diagram 3] FIG. 2 is a control block diagram illustrating a control device according to an embodiment. [Figure 4] FIG. 2 is a diagram illustrating an example of a control target of a control device according to an embodiment. [Diagram 5] FIG. 11 is a control block diagram showing a control device in which a correction value calculation unit is an ILC circuit. [Figure 6] FIG. 1 is a diagram showing the circuit configuration of a control circuit used in a method for designing L(jω) from G(jω)S(jω) which is directly obtained by closed-loop system identification. [Figure 7] 7 is a diagram showing a circuit configuration of a control circuit obtained by equivalently converting the control circuit in FIG. 6. [Figure 8] FIG. 13 shows the frequency response obtained by closed-loop system identification. [Figure 9] FIG. 13 is a diagram showing L(jω) designed by modeling using fitting based on frequency response. [Figure 10]FIG. 1 is a diagram showing a Q filter designed to ensure convergence of the deviation (error) ej in all frequency domains. [Figure 11] FIG. 13 is a diagram showing the stage temperature and the control input when the stage temperature is controlled only by feedback control. [Figure 12] FIG. 13 is a diagram showing a control waveform (temperature behavior) of an existing stage A and a control waveform (temperature behavior) of a new stage A′ obtained by improving the existing stage A. [Figure 13] 13 is a diagram showing the stage temperature, control input, and ILC signal in the case where the stage temperature is controlled only by feedback control without using an ILC circuit in Experimental Example 1. FIG. [Figure 14] FIG. 11 is a diagram showing the stage temperature, control input, and ILC signal when the first ILC experiment was performed in Experimental Example 1. [Figure 15] FIG. 11 is a diagram showing the stage temperature, control input, and ILC signal when a second ILC experiment was performed in Experimental Example 1. [Figure 16] FIG. 13 is a diagram showing the stage temperature, control input, and ILC signal when the third ILC experiment was performed in Experimental Example 1. [Figure 17] FIG. 11 is a diagram showing the stage temperature, control input, and ILC signal when the fourth ILC experiment was performed in Experimental Example 1. [Figure 18] FIG. 13 is a diagram showing the stage temperature, control input, and ILC signal when the fifth ILC experiment was performed in Experimental Example 1. [Figure 19] FIG. 1 is a graph showing the relationship between the number of ILC experiments and the root mean squared error indicating the fluctuation in stage temperature in Experimental Example 1. [Figure 20] 13 is a diagram showing the stage temperature, control input, and ILC signal in the case where the stage temperature is controlled only by feedback control without using an ILC circuit in Experimental Example 2. FIG. [Figure 21] FIG. 13 is a diagram showing the stage temperature, control input, and ILC signal when the first ILC experiment was performed in Experimental Example 2. [Figure 22] FIG. 13 is a diagram showing the stage temperature, control input, and ILC signal when a second ILC experiment was performed in Experimental Example 2. [Figure 23] FIG. 13 is a diagram showing the stage temperature, control input, and ILC signal when the third ILC experiment was performed in Experimental Example 2. [Figure 24] FIG. 13 is a diagram showing the stage temperature, control input, and ILC signal when the fourth ILC experiment was performed in Experimental Example 2. [Diagram 25] FIG. 13 is a diagram showing the stage temperature, control input, and ILC signal when the fifth ILC experiment was performed in Experimental Example 2. [Figure 26] FIG. 13 is a graph showing the relationship between the number of ILC experiments and the root mean squared error indicating the fluctuation in stage temperature in Experimental Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described with reference to the accompanying drawings.

[0010] <Background and Overview> First, the background and overview will be explained. In substrate processing by a substrate processing apparatus, state quantities such as temperature, pressure, gas flow rate, etc. are conventionally controlled by feedback control. Fig. 1 is a control block diagram for conventional general feedback control. As shown in Fig. 1, a control device 100 controls a controlled object 101 by a feedback controller 102 based on a detection value y detected by a detector 103. The feedback controller 102 provides a control input u to the controlled object 101 so that a deviation (error) e between a target value r calculated by a subtractor 104 and the detection value y by the detector 103 is eliminated.

[0011] However, feedback control has a delay in control because it controls the state quantity based on the actually detected value. Therefore, when the deviation (error) e between the detected value y and the target value r becomes large due to disturbances, etc., overshooting occurs, causing large fluctuations in the state quantity of the controlled object, taking time to settle to the target value, and making it easier for differences between devices to appear, resulting in variation in the process results.

[0012] In addition, there are various states of the substrate. For example, when the substrate is a wafer, there are bare wafers, patterned wafers, wafers with different thicknesses of the film formed thereon, etc. When the state of the substrate differs, the behavior of the state quantity, for example, temperature, may change, which may affect the controllability. In addition, when the process is repeated, the state inside the chamber may change due to, for example, the accumulation of a film inside the chamber or the wear of parts inside the chamber, which may affect the controllability. In addition, when the conditions for transferring the substrate in the recipe differ, or between different chambers or different stage heaters, the controllability of the state quantity may change. Such differences in controllability also affect the process results, but feedback control alone cannot deal with such differences in controllability.

[0013] Furthermore, there is a demand for adjusting the control waveform of a state quantity, such as matching the waveform of the state quantity of a controlled object to the waveform of a different controlled object, but such demands cannot be met by feedback control alone.

[0014] Therefore, in this embodiment, a control device for controlling a state quantity in a substrate processing apparatus that processes substrates is provided, the control device having a feedback controller that gives a control signal to a controlled object based on the deviation between a target value of the state quantity and a value detected by a detector, and a correction value calculation unit having the following configuration. The correction value calculation unit calculates the deviation e between the target value and the detected value in the jth substrate processing (j is an integer of 1 or more). j The deviation e between the target value and the detected value during the j+1th substrate processing is obtained. j+1 is the deviation e jA correction value to be added to the control signal from the feedback controller during the processing of the j+1-th substrate is calculated so that the correction value is smaller than

[0015] This configuration makes it possible to realize controllability that cannot be obtained by conventional control using feedback control. That is, according to this embodiment, a correction value is calculated so that the deviation is smaller in the next j+1th substrate processing than in the jth substrate processing, and the correction value is added to the control signal corresponding to the j+1th substrate processing, so that the deviation converges. This makes it possible to suppress fluctuations in the state quantity of the controlled object due to disturbances, etc., and to settle the state quantity to the target value in a short period of time. In addition, the waveform of the state quantity of the controlled object can be arbitrarily adjusted by using such a correction value.

[0016] <Specific embodiment> Next, a specific embodiment will be described in which the above-described control device is applied to substrate temperature control in a single-wafer deposition apparatus serving as a substrate processing apparatus.

[0017] [Film forming equipment] FIG. 2 is a cross-sectional view showing an example of a film forming apparatus as a substrate processing apparatus to which a control device according to an embodiment is applied.

[0018] The film forming apparatus 1 forms a film on a substrate S by CVD or ALD, and has a chamber 2. A stage 3 is provided in the chamber 2 for horizontally placing and heating the substrate S. In this example, one substrate S is placed on the stage 3, and the film forming apparatus 1 is configured as a single-wafer type apparatus. The stage 3 functions as a holding mechanism for holding the substrate and a heating mechanism for heating the substrate. The stage 3 may be one on which multiple substrates S are placed. For example, the apparatus may be a two- or four-wafer apparatus in which two or four substrates S are placed on the stage 3.

[0019] The stage 3 has a stage body, a heater 4 provided inside the stage body, and a heater power supply (not shown) that supplies power to the heater 4. The heater 4 and the heater power supply constitute a heater system. The stage 3 has an inner zone 3a and an outer zone 3b. The heater 4 is configured as a two-zone heater having an inner heater 4a corresponding to the inner zone 3a and an outer heater 4b corresponding to the outer zone 3b. The stage 3 may have a single heater that is not divided into zones, or may have a heater divided into three or more. A thermocouple 10 that is a temperature detector is provided near the substrate S in the center of the stage 3, and temperature control is performed based on the detection value of the thermocouple 10 as described below. The temperature detector is not limited to a thermocouple, and a resistance temperature detector or a radiation thermometer may be used.

[0020] An exhaust pipe 5 is connected to the bottom of the chamber 2, and an exhaust mechanism 6 having a vacuum pump and a pressure control valve for controlling the pressure inside the chamber 2 is connected to this exhaust pipe 5. A transfer port 7 through which the substrate S is transferred is formed in the side wall of the chamber 2, and the transfer port 7 is opened and closed by a gate valve 8.

[0021] A shower head 9 is provided at the top of the chamber 2 so as to face the stage 3. The shower head 9 has a gas chamber 9a therein and a plurality of gas ejection holes 9b at the bottom.

[0022] A gas supply unit 11 is connected to the shower head 9 via a gas flow path 12. The gas supply unit 11 supplies one or more gases required for film formation. The gas supply unit 11 has a valve for starting and stopping the gas supply and a flow rate controller for controlling the gas flow rate (neither of which are shown). The gas from the gas supply unit 11 reaches the gas chamber 9a of the shower head 9 via the gas flow path 12 and is discharged into the chamber 2 via the gas discharge holes 9b.

[0023] The gas supply unit 11 and the shower head 9 constitute a processing mechanism for processing the substrate S in the chamber 2. The processing mechanism may include a plasma generation mechanism for converting the gas supplied from the gas supply unit 11 into plasma.

[0024] The film forming apparatus 1 further includes a control system 20. The control system 20 controls each component of the film forming apparatus 1 based on a process recipe. The control system 20 includes a control device 30 of this embodiment that controls the temperature of the substrate S on the stage 3. The control system 20 may be configured as a single control unit, or may include an apparatus control unit that is a higher-level control unit having a process recipe, and a temperature control unit that is a lower-level control unit.

[0025] [Control device] 3 is a control block diagram showing a control device according to an embodiment. The control device 30 controls a controlled object 31, and includes a feedback controller 32 and a correction value calculation unit .

[0026] In this embodiment, the controlled object 31 is the stage 3, which has a stage body 310, a two-zone heater system 311 for heating the stage body 310, and a power ratio setting unit 312, as shown in the block diagram of FIG. 4, for example. The heater system 311 includes an inner zone having an inner heater, an outer zone having an outer heater, and power supplies for feeding the inner heater and the outer heater, respectively. The power ratio setting unit 312 sets the power ratio between the inner heater and the outer heater. In this example, the power ratio setting unit 312 uses a power ratio fixed to a certain set value, and the control input (power) u is the power u to the inner heater. i and power to the outer heater o The thermocouple 10, which is the detector, corresponds only to the inner heater, so although it is a two-zone heater, it is a one-input, one-output system. As described above, the controlled object 31 (stage 3) may have a single heater that is not divided into zones, or may have a heater that is divided into three or more zones.

[0027] The feedback controller 32 outputs a control signal so as to eliminate the deviation (error) e between the target value r calculated by the subtractor 33 and the detection value y of the thermocouple 10 serving as a detector, thereby controlling the temperature of the controlled object 31 (stage 3). This controls the temperature of the substrate S on the stage 3. The target value r is set, for example, by a setting device (not shown). The control method of the feedback controller 32 is not particularly limited. For example, PID control, PI control, or feedback control using modern control theory can be used.

[0028] The correction value calculation unit 34 calculates the deviation (error) e in the j-th substrate processing (j is an integer equal to or greater than 1). j The deviation (error) e during the j+1th substrate processing is obtained. j+1 is the deviation (error) e during the jth substrate processing j A correction value f is added to the control signal from the feedback controller 32 during the processing of the j+1th substrate so that the correction value f is smaller than the j+1th substrate processing value. j In other words, the correction value f is calculated so that the deviation (error) monotonically converges. j Calculate the correction value f j is added to the control signal in adder 35.

[0029] The correction value calculation unit 34 is not particularly limited as long as it has the above-mentioned functions, but a suitable example is an ILC circuit that performs iterative learning control (ILC).

[0030] Iterative learning control (ILC) is a control technique that reduces error with respect to a target by repeatedly performing tracking control (trials) with respect to a target trajectory of a controlled object.

[0031] ILC is an established technology, and a control device using ILC is described in, for example, JP 2009-205641 A, and the description of ILC described therein can be applied to this embodiment. However, the technology described in JP 2009-205641 A applies ILC to a position control device, and is in a different field from this embodiment, which relates to control of state quantities in substrate processing such as temperature and pressure, and does not suggest this embodiment.

[0032] 5 is a control block diagram when the correction value calculation unit 34 of the control device 30 is an ILC circuit. The ILC circuit constituting the correction value calculation unit 34 has an L filter 41, a Q filter 42, a memory 43, and an adder 44.

[0033] The L filter 41 is a learning filter. The Q filter 42 is a frequency cutoff filter that has a function of cutting off a specific frequency band. The L filter 41 includes a deviation e j is input as an error, and the output of the L filter 41 is input to an adder 44. The deviation e j is time series data. Also, the ILC signal f corresponding to the j-th substrate processing from the ILC circuit is j is also input to the adder 44. The output from the adder 44 is input to the Q filter 42. The output from the Q filter 42 is the j+1th ILC signal f j+1 The ILC signal f stored in the memory 43 is j+1 is the control signal u from the feedback controller 32 in the j+1th substrate processing. fb j+1 Correction value f to be added to j+1 The ILC signal (correction value) f j+1 may be time series data. Note that the deviation (error) e j If the convergence of the above can be guaranteed, the Q filter 42 does not need to be used.

[0034] In the ILC, the ILC signal is updated for each substrate processing, thereby improving the control accuracy. In addition, the settings of the ILC circuit (L filter 41, etc.) can be changed according to the conditions of the substrate processing. For example, the L filter can be designed as follows.

[0035] Let L(jω) be the L filter 41, G(jω) be the controlled object 31, K(jω) be the feedback controller 32, and S(jω) be the sensitivity function in the feedback control system. S(jω) is expressed by the following equation (1), where the deviation (error) in the processing of the j+1th substrate is e j+1 can be expressed by the following equation (2). S(jω)=1 / (1+G(jω)K(jω)) ···(1) e j+1 =(1-G(jω)S(jω)L(jω)))e j (2) In equation (2), G(jω)S(jω) is a frequency response determined by the configuration of feedback controller 32+controlled object 31.

[0036] From equation (2), the deviation (error) e j The condition for monotonically converging (i.e., e j+1 G j The condition for the impedance to be smaller than 100 kΩ is to satisfy the following equation (3) at all frequencies. |1-G(jω)S(jω)L(jω))|<1 ···(3) In equation (3), if we can design the following equation (4), then G(jω)S(jω)L(jω)) = 1, and theoretically the deviation (error) e j+1 =0. L(jω)=(G(jω)S(jω)) -1 (4)

[0037] When the model of the controlled object and the model of the sensitivity function obtained from the estimated value are expressed by G(jω) and S(jω), respectively, with a hat, L(jω) is expressed by the following equation (5), and L(jω) (i.e., the L filter 41) can be designed using this relationship.

number

[0038] In this case, the following (a) or (b) can be used as a design method for L(jω).

[0039] (a) is a method for designing L(jω) from G(jω)S(jω) (with a hat) which is obtained directly by closed-loop system identification. This method has the advantage that it is easy to implement when the frequency response of the feedback controller is unknown. However, if the gain of the feedback controller is changed, closed-loop system identification must be performed again.

[0040] (b) is a method for designing L(jω) from G(jω) (with a hat) and K(jω), which is a model of the feedback controller. K(jω) can be found using the following equation (6). With this method, when the gain of the feedback controller changes, it is only necessary to find the transfer function of the feedback controller, and since there is no need to perform closed-loop system identification, it is easy to redesign L(jω). Therefore, this method is easy to use when the frequency response of the feedback controller can be calculated.

number

[0041] Next, an experiment for actually designing L(jω) of the L filter 41 in the ILC using the above method (a) will be described. In the following description, the design of the Q filter 42 will also be described.

[0042] Closed-loop system identification was performed by adding a multisine signal as an external input (time series data) while applying feedback in a feedback control circuit having a circuit configuration as shown in Figure 6. The control circuit in Figure 6 can be equivalently converted to the control circuit shown in Figure 7. The control circuit in Figure 7 takes a multisine signal (time series data) as input and outputs temperature (time series data), and can directly obtain G(jω)S(jω) as the frequency response. Figure 8 shows the frequency response in this case. In Figure 8, the gain and phase at each frequency are plotted. From these data, modeling of G(jω)S(jω) (hereinafter referred to as GS) was performed by fitting. Figure 8 shows GS (with a hat) modeled by fitting.

[0043] From the results of this modeling, L(jω) (hereinafter, written as L as shown in FIG. 9) was obtained based on the relationship of the above formula (4), and the L filter 41 was designed. In addition to L, FIG. 9 also shows plots of GS and G(jω)S(jω)L(jω) (hereinafter, written as GSL as shown in FIG. 9).

[0044] However, with only L designed in this way, the value of |1-GSL| becomes larger than 0 dB in the high frequency range, and the deviation (error) e j The convergence of Q(e -jω )Q(e jω )(=|Q(jω)| 2 (hereinafter |Q| 2 A Q filter 42 represented as |Q| 2 The Q filter is designed so that the convergence of the deviation (error) evaluated by |1-GSL| satisfies the following equation (7) at all frequencies. |Q| 2 |1-GSL|<1 (7) In the example shown in FIG. 10, |1-GSL| is greater than 0 dB in the high frequency range. However, by designing the Q filter 42 to satisfy the formula (7), |Q| 2|1-GSL| can be made equal to or less than 0 dB in all frequency ranges.

[0045] From the above, using the frequency domain model, the deviation (error) e j It was confirmed that it is possible to design L and Q with guaranteed convergence.

[0046] In addition, the deviation (error) e j If the convergence of the above can be guaranteed, the Q filter 42 does not need to be used, as described above.

[0047] When the control system 20 has an upper control unit, that is, an equipment control unit, and a lower control unit, that is, a temperature control unit, the feedback controller 32 of the control device 30 is included in the temperature control unit, but the correction value calculation unit 34 may be included in either the equipment control unit or the temperature control unit.

[0048] When the correction value calculation unit 34 is included in the device control unit, the calculations in the correction value calculation unit 34 are performed in the device control unit, which has the advantage of not using many resources in the temperature control unit. However, the disadvantage is that it takes time to transmit deviation (error) signals and correction value signals.

[0049] On the other hand, when the correction value calculation unit 34 is included in the temperature control unit, the calculation in the correction value calculation unit 34 is performed in the temperature control unit, and there is an advantage that there is no need to transmit a correction value signal, and also that not many changes are required in the device control unit when testing the correction value calculation unit 34. However, there are disadvantages in that the number of recipes and steps to which the correction value calculation unit 34 is applied increases, the amount of data stored in the temperature control unit increases, and the correction value needs to be calculated so as not to affect the temperature control cycle.

[0050] [Processing Operation] Next, a processing operation in the film forming apparatus 1 configured as above will be described. In the film formation apparatus 1, the substrate S is carried into the chamber 2 and placed on the stage 3, the chamber 2 is brought to a predetermined vacuum pressure, the stage 3 is brought to a predetermined temperature, and a gas for film formation is supplied from the gas supply unit 11 through the shower head 9 into the chamber 2 at a predetermined flow rate to perform a film formation process. In this film formation process, based on a process recipe stored in the control system 20, the pressure in the chamber 2 is controlled by the pressure control valve, the gas flow rate is controlled by the flow rate controller, and the temperature of the stage 3 constituting the controlled object 31 is controlled by the control device 30.

[0051] The temperature control by the control device 30 is performed based on the feedback control by the feedback controller 32 and the correction value calculated by the correction value calculation unit 34. The correction value calculation unit 34 calculates the deviation (error) e j The deviation (error) e during the j+1th substrate processing is obtained. j+1 is the deviation (error) e during the jth substrate processing j The control signal u for the j+1-th substrate process from the feedback controller 32 is set to be smaller than fb j+1 Correction value f to be added to j+1 Calculate.

[0052] A specific case where an ILC circuit is used as the correction value calculation unit 34 will be described. The L filter 41 includes a deviation e in the j-th substrate processing (j is an integer equal to or greater than 1). j is input to the L filter 41, and the output of the L filter 41 is input to the adder 44. In addition, the j-th ILC signal (correction value) f j is also input to the adder 44. The output from the adder 44 is input to the Q filter 42. The output from the Q filter 42 is the j+1th ILC signal f j+1 The ILC signal f stored in the memory 43 is j+1 is the correction value f for the j+1th substrate processing j+1 as the control signal u from the feedback controller 32. fb j+1During the first substrate processing, the temperature is controlled only by feedback control.

[0053] The feedback controller 32 can always continue to perform calculations, but the correction value calculation unit 34 calculates the deviation (error) e j and the correction value f to be used in the next substrate processing j+1 (i.e., ILC signal f j+1 ) is calculated at once, the correction value f j+1 It is not possible to calculate

[0054] Therefore, the calculation of the correction value in the correction value calculation unit 34 needs to be performed during a period when the substrate processing is not being performed. For example, the calculation of the correction value in the correction value calculation unit 34 is performed when the substrate processing is completed or when any step is completed.

[0055] Specifically, in the substrate processing apparatus, when a plurality of substrates are processed consecutively, during a period in which no substrate is being processed after the processing of the j-th substrate (j is an integer of 1 or more), the feedback controller 32 continues feedback control while the correction value calculation unit 43 calculates a correction value f j+1 and adding a correction value f to the control signal of the feedback controller 32 during the next j+1th substrate processing. j+1 and controlling the temperature of stage 3, which is a state quantity, by adding

[0056] Furthermore, the timing at which the correction value starts to be added to the control signal for feedback control can be the start of the process recipe or a timing specified in the process recipe.

[0057] In substrate processing, processing may be performed in one chamber according to a plurality of process recipes. If the process recipes are different, the timing at which the substrate is loaded into the chamber, the gas flow rate, pressure, etc. may change, and there is a possibility that disturbances in the stage temperature will not be reproducible. ILC is highly effective against disturbances with high reproducibility, but is weak in situations where disturbances that differ greatly are introduced. For this reason, it is effective to associate a correction value (ILC signal) with each process recipe, store it in the memory of the control system 20, and call up the correction value associated with the process recipe to be executed. In addition, the correction value may be associated with a plurality of process recipes, not limited to the case where a correction value is associated with each process recipe in this way. For example, when there are a plurality of process recipes in which the stage is heated to a specific temperature (for example, 200 to 300° C.) but the subsequent process conditions are different, the correction value for the heating portion of the specific temperature can be used as a common value across these multiple process recipes.

[0058] Furthermore, the controllability of the control object 31 (stage 3) differs depending on the chamber 1. Even in the same chamber, the controllability differs depending on the state of the control object 31 (stage 3) (for example, the number of substrates on stage 3 (one substrate, two substrates, four substrates, etc.)). For this reason, a correction value may be provided for each combination of a process recipe and a chamber, or each combination of a process recipe and a control object 31 (stage 3), and stored in memory to be called up as appropriate.

[0059] Furthermore, the chamber conditions may change while processing multiple substrates, in which case a different correction value may be used for each substrate, for example, for the first to 25th substrates in one lot.

[0060] Furthermore, common ILC information may be provided for the substrate placement step rather than the process recipe.

[0061] As described above, in a specific embodiment, the control device 30 is configured to include a correction value calculation unit 34 in addition to the feedback controller 32. The correction value calculation unit 34 calculates the deviation (error) e jThe deviation (error) e during the j+1th substrate processing is obtained. j+1 is the jth deviation (error) e j The control signal u for the j+1-th substrate process from the feedback controller 32 is set to be smaller than fb j+1 Correction value f to be added to j+1 Then, the control signal u for the j+1th substrate processing from the feedback controller 32 is calculated. fb j+1 Correction value f j+1 In other words, the correction value f j+1 is used as a feedforward signal. This makes it possible to suppress temperature fluctuations in the stage 3 due to disturbances and the like, and to settle the temperature within a desired range in a shorter time. In addition, by using such a correction value, the temperature behavior (temperature waveform) of the stage 3 constituting the controlled object 31 can be adjusted to a desired temperature behavior (temperature waveform).

[0062] The specific details will be explained below. Conventionally, the temperature control of the stage, which is the object of control, was generally performed only by feedback control. However, feedback control causes delays in control because it controls the object of control based on the actually detected detection value. For this reason, when the deviation (error) e between the detection value y and the target value r becomes large due to disturbances such as the substrate temperature, overshooting occurs, causing large fluctuations in the stage temperature, and it takes time to settle to the target value, resulting in a decrease in throughput. For example, when a substrate is placed on a stage controlled to a temperature for processing, the temperature of the stage decreases as shown in FIG. 11(a). For this reason, as shown in FIG. 11(b), the feedback controller tries to return the temperature, increasing the control input, and conversely, the temperature rises too much, resulting in a long time until it converges to the target temperature range. In addition, when the fluctuations in the stage temperature are large, the energy applied to the substrate is likely to vary between devices, and the process results are likely to show differences between devices. In addition, with feedback control alone, when the set temperature of the stage is lowered, the range that can be controlled against disturbances is limited, and there is a period in which the control input is 0 and there is an uncontrolled state, resulting in a decrease in controllability.

[0063] Furthermore, there are various states of the substrate. For example, when the substrate is a wafer, there are bare wafers, patterned wafers, wafers with different thicknesses of the film formed thereon, etc. When the substrate state differs, the behavior of the stage temperature may change, which may affect the controllability of the stage temperature. In addition, when the process is repeated, the state inside the chamber may change due to, for example, the accumulation of a film inside the chamber or the wear of parts inside the chamber, which may affect the controllability of the stage temperature. In addition, the controllability of the stage temperature may change when the substrate transfer conditions in the recipe differ, between different chambers, between different stages, etc. Such differences in controllability also become disturbances and affect the process results, but feedback control alone cannot handle such differences in controllability.

[0064] In response to this, the correction value calculation unit 34 calculates a correction value so that the deviation is smaller for the (j+1)th substrate processing than for the jth substrate processing, and adds this correction value to the control signal from the feedback controller 32, thereby suppressing temperature fluctuations of the stage due to such disturbances, etc., and solving the above problem.

[0065] Furthermore, there is a demand to adjust the temperature behavior (control waveform) of the stage 3, which is the controlled object, to a desired temperature behavior. In such a case, a target value is set as time series data so that the stage has the desired temperature behavior, and as described above, the correction value calculated by the correction value calculation unit 34 is added to the control signal of the feedback controller 32, so that the temperature of the stage can be made to follow the target value, which is the desired temperature behavior. For example, when a new stage A' is developed by improving an existing stage A, the control waveform (temperature behavior) of the stage A' by feedback control may differ from the control waveform (temperature behavior) of the stage A. In such a case, there is a demand to match the temperature behavior of the stage A' to the temperature behavior of the stage A. Specifically, when the temperature behavior of the stage A is shown in FIG. 12(a) and the temperature behavior of the stage A' is shown in FIG. 12(b), it is desired to match the temperature behavior of the stage A' to FIG. 12(a). In such a case, the temperature behavior of stage A is set as the target temperature of stage A', and as described above, the correction value calculated by correction value calculation unit 34 is added to the control signal from feedback controller 32, thereby making it possible to match the temperature behavior of stage A' to the temperature behavior of stage A, which is the target temperature.

[0066] <Experimental Example> Next, an experimental example will be described.

[0067] [Experimental Example 1] Here, we explain the effect of adding an ILC signal (correction value) calculated using an ILC circuit as a correction value calculation unit to the control signal of the feedback controller when controlling the substrate wafer to 420°C on the stage.

[0068] In the first experiment, the stage temperature was controlled using only feedback control without using the ILC circuit. The results are shown in Figure 13. As shown in this figure, the stage temperature dropped rapidly when the wafer was placed on it, and the control input increased rapidly accordingly, resulting in a corresponding increase in the stage temperature fluctuation.

[0069] Next, an ILC signal was generated by the ILC circuit using the stage temperature from the experiment without the ILC circuit, and the ILC signal was added as a correction value to the control signal of the feedback controller to perform the first ILC experiment. The results are shown in Figure 14. As shown in this figure, by adding the ILC signal, the control input was adjusted and the temperature fluctuation of the stage was sufficiently suppressed, resulting in an extremely small temperature fluctuation of within 0.6°C.

[0070] Next, an ILC signal was generated by the ILC circuit using the stage temperature from the first ILC experiment, and the ILC signal was added as a correction value to the control signal of the feedback controller to perform a second ILC experiment. The results are shown in Figure 15. As shown in this figure, adding the second ILC signal maintained the suppressed state of the stage temperature fluctuation, and the temperature fluctuation became even smaller, within 0.4°C.

[0071] Similarly, an ILC signal was generated by the ILC circuit using the stage temperature from the previous experiment, and the ILC signal was added as a correction value to the control signal of the feedback controller to perform the third to fifth ILC experiments. The results are shown in Figures 16 to 18, respectively. As shown in these figures, the suppressed state of temperature fluctuations in the stage was maintained even in the third and subsequent ILC experiments, with the temperature fluctuations in the third ILC experiment being within 0.5°C, and those in the fourth and fifth ILC experiments being within 0.4°C.

[0072] 19 is a diagram showing the relationship between the number of ILC experiments and the root mean squared error (RMS) indicating the fluctuation in stage temperature in Experimental Example 1. As shown in this diagram, it was confirmed that the temperature fluctuation of the stage was sufficiently converged by the first ILC experiment, and that the state in which the temperature fluctuation was sufficiently converged was maintained in the subsequent second to fifth ILC experiments.

[0073] [Experimental Example 2] Here, we will explain the effect of adding an ILC signal (correction value) calculated using an ILC circuit designed at 420°C similar to that of Experimental Example 1 when controlling the substrate wafer on the stage to 250°C.

[0074] In the first experiment, the stage temperature was controlled using only feedback control, without using an ILC circuit. The results are shown in Figure 20. As shown in this figure, the stage temperature drops rapidly when the wafer is placed, and the control input increases rapidly accordingly. Then, due to an overshoot in the stage temperature caused by the increase in control input, the control input becomes stuck at 0%, resulting in an uncontrolled state, and large fluctuations in the stage temperature.

[0075] Next, an ILC signal was generated by the ILC circuit using the stage temperature from the experiment without the ILC circuit, and the ILC signal was added as a correction value to the control signal of the feedback controller to perform the first ILC experiment. The results are shown in Figure 21. As shown in this figure, adding the ILC signal adjusted the control input and suppressed the stage temperature fluctuations to some extent. However, it was confirmed that the ILC signal became increasingly negative and the stage temperature tended to decrease in the latter half, and the temperature fluctuations were somewhat large.

[0076] Next, an ILC signal was generated by the ILC circuit using the stage temperature from the first ILC experiment, and the ILC signal was added as a correction value to the control signal of the feedback controller to perform a second ILC experiment. The results are shown in Figure 22. As shown in this figure, adding the second ILC signal sufficiently suppressed the temperature fluctuation of the stage, and the temperature fluctuation was extremely small at within 0.4°C.

[0077] Similarly, an ILC signal was generated as a correction value by the ILC circuit using the stage temperature from the previous experiment, and the ILC signal was added to the control signal of the feedback controller to perform the third to fifth ILC experiments. The results are shown in Figures 23 to 25, respectively. As shown in these figures, the suppression of stage temperature fluctuations was maintained even in the third and subsequent ILC experiments, and the temperature fluctuations were all within 0.2°C.

[0078] 26 is a diagram showing the relationship between the number of ILC experiments and the root mean squared error (RMS) indicating the fluctuation in stage temperature in Experimental Example 2. As shown in this diagram, in the first ILC experiment, the temperature fluctuation of the stage decreased but was still somewhat large, but it was confirmed that the temperature fluctuation converged sufficiently by the second ILC experiment, and the state in which the temperature fluctuation was sufficiently converged was maintained in the subsequent third to fifth ILC experiments.

[0079] <Other applications> Although the embodiments have been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0080] For example, in the above embodiment, an example was shown in which the temperature fluctuations with respect to the target temperature were converged, but the present invention can also be applied to the case in which the fluctuations during temperature rise or fall until the target temperature is reached are converged.

[0081] In addition, in the above embodiment, the state quantity to be controlled is described as temperature, but the state quantity is not limited to temperature as long as it is a state quantity when processing a substrate in a substrate processing apparatus, and may be other state quantities such as pressure and gas flow rate.

[0082] In the above embodiment, the substrate processing apparatus is described as a substrate processing apparatus in which a substrate is placed on a stage and the temperature of the stage is controlled by a one-input, one-output system, but the present invention can also be applied to a case where a stage has multiple heaters divided into zones and heaters in each zone are controlled separately. In the above embodiment, an example is shown in which substrate processing is performed one by one, but the present invention is not limited to this, and a batch-type processing apparatus may be used in which multiple substrates are stacked and placed in a processing vessel and processed. The substrate processing is described as an example in which a gas is supplied to a substrate to perform CVD or ALD film formation, but the present invention is not limited to this, and PVD film formation in which a target is sputtered may be used. In addition, the present invention is not limited to film formation, and other substrate processing may be performed, such as etching, oxidation, and diffusion.

[0083] Furthermore, in the above embodiment, an example was shown in which a correction value calculation unit using iterative learning control or the like was applied to feedback control, but the correction value calculation unit may also be applied to two-degree-of-freedom control, for example, control that combines feedback control and feedforward control.

[0084] Furthermore, in the above embodiment, the correction value calculation unit has been described by taking an example in which iterative learning control (ILC) is used as the correction value calculation unit, but the present invention is not limited to this, and may use numerical control using AI or the like. [Explanation of symbols]

[0085] 1. Film forming equipment (substrate processing equipment) 2. Chamber 3. Stage 4;Heater 6; Exhaust system 9. Shower head 10; Thermocouple (detector) 11: Gas supply section 20. Control system 30: Control device 31; Control object 32: Feedback control section 34: Correction value calculation section 41;L filter (learning filter) 42;Q filter (frequency shielding filter) 43;Memory S; Substrate

Claims

1. A control device for controlling a state quantity in a substrate processing apparatus that processes a substrate, a feedback controller that provides a control signal to a controlled object based on a deviation between a target value of the state quantity and a value detected by a detector; The deviation e between the target value and the detected value in the j-th substrate processing (j is an integer of 1 or more) ｊ The deviation e between the target value and the detected value during the j+1th substrate processing is obtained. ｊ＋１ is the deviation e ｊ a correction value calculation unit that calculates a correction value to be added to the control signal during the j+1-th substrate processing from the feedback controller so that the correction value is smaller than A control device having the above configuration.

2. 2. The control device according to claim 1, wherein the correction value calculation unit is an iterative learning control circuit that performs iterative learning control and outputs an iterative learning control signal as the correction value.

3. The iterative learning control circuit comprises: a learning filter to which the deviation is input; The deviation e ｊ The iterative learning control signal f, which is the correction value during the j-th substrate processing, is input to the output of the learning filter when ｊ an adder for adding The output of the adder is the iterative learning control signal f ｊ＋１ and memory to store as The control device according to claim 2 , further comprising:

4. 4. The control device according to claim 3, wherein the iterative learning control circuit further comprises a frequency cutoff filter having a function of cutting off a specific frequency band of the output of the adder.

5. The learning filter is L(jω), the frequency response determined by the configuration of the feedback controller and the controlled object is G(jω)S(jω), and the frequency shielding filter is |Q(jω)| ２ In this case, N9(ω)9 ２ 11(Qω)S(ω)4(Qω))9 The control device according to claim 4 , wherein

6. the substrate processing apparatus has a plurality of processing recipes for controlling processing of the substrate; The control device according to claim 2 , wherein an iterative learning control signal of the iterative learning control circuit linked to each of the process recipes is stored as the correction value, and the correction value linked to a process recipe to be executed is called up.

7. The control device according to claim 1 , wherein the state quantity is a temperature, a pressure, or a gas flow rate.

8. The control device according to claim 1 , wherein the substrate processing apparatus has, as a controlled object, a stage for placing and heating a substrate in a chamber, and controls a temperature of the stage as the state quantity.

9. The control device according to claim 8 , wherein the control device suppresses temperature fluctuations of the stage due to disturbances by adding the correction value calculated by the correction value calculation unit to a control signal of the feedback controller.

10. The control device according to claim 9 , wherein the disturbance is a difference between a temperature of the stage and a temperature of the substrate before being placed on the stage, a difference in a state of the substrate, or a change in a state inside the chamber.

11. 9. The control device according to claim 8, wherein the control device sets the target value as time series data so that the stage exhibits a desired temperature behavior, and causes the temperature of the stage to follow the target value by adding the correction value calculated by the correction value calculation unit to a control signal of the feedback controller.

12. A chamber; a substrate holding mechanism for holding a substrate within the chamber; a processing mechanism for processing a substrate in the chamber; a control system having a control device for controlling a state quantity during the processing; having The control device includes: a feedback controller that provides a control signal to a controlled object based on a deviation between a target value of the state quantity and a value detected by a detector; The deviation e between the target value and the detected value in the j-th substrate processing (j is an integer of 1 or more) ｊ The deviation e between the target value and the detected value during the j+1th substrate processing is obtained. ｊ＋１ is the deviation e ｊ a correction value calculation unit that calculates a correction value to be added to the control signal during the j+1-th substrate processing from the feedback controller so that the correction value is smaller than The substrate processing apparatus includes:

13. The substrate processing apparatus according to claim 12 , wherein in the control device, the correction value calculation unit is an iterative learning control circuit that performs iterative learning control and outputs an iterative learning control signal as the correction value.

14. The substrate processing apparatus of claim 13 , wherein the control system stores a plurality of processing recipes for controlling processing on the substrate and the iterative learning control signal of the iterative learning control circuit linked to each of the processing recipes as the correction value, and the correction value linked to the processing recipe to be executed is called up.

15. The substrate processing apparatus according to claim 14 , wherein the correction value is common to a plurality of processing recipes.

16. 16. The substrate processing apparatus according to claim 12, further comprising a stage for placing a substrate thereon as the substrate holding mechanism, the stage having a heater and functioning as the controlled object, and the control device controlling a temperature of the stage as the state quantity.

17. 17. The substrate processing apparatus according to claim 16, wherein the control system includes a host equipment control unit that controls the substrate processing apparatus based on a process recipe, and a temperature control unit that performs temperature control and includes the feedback controller, and the correction value calculation unit is included in the equipment control unit.

18. 17. The substrate processing apparatus of claim 16, wherein the control system includes a host equipment control unit that controls the substrate processing apparatus based on a process recipe, and a temperature control unit that performs temperature control and includes the feedback controller, and the correction value calculation unit is included in the temperature control unit.

19. 1. A substrate processing method for continuously processing a plurality of substrates in a substrate processing apparatus, comprising: The substrate processing apparatus includes a chamber, a substrate holding mechanism for holding a substrate in the chamber, a processing mechanism for processing the substrate in the chamber, and a control device for controlling a state quantity during the processing, the control device including a feedback controller that gives a control signal to a controlled object based on a deviation between a target value of the state quantity and a detection value by a detector, and a deviation e between the target value and the detection value in a j-th substrate processing (j is an integer of 1 or more). ｊ The deviation e between the target value and the detected value during the j+1th substrate processing is obtained. ｊ＋１ is the deviation e ｊ a correction value calculation unit that calculates a correction value to be added to the control signal from the feedback controller during the j+1-th substrate processing so that the correction value is smaller than During a period in which the j-th substrate is not being processed after the processing of the j-th substrate, the correction value calculation unit calculates a correction value f ｊ＋１ Calculating When starting the next (j+1)th substrate processing, a correction value f is added to the control signal of the feedback controller. ｊ＋１ and performing control by adding The substrate processing method comprises:

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