JP6010288B2 - Plasma control device, flow control device used in plasma control device, and flow control program - Google Patents

Description

  The present invention relates to a plasma control device, a flow rate control device, and a flow rate control program for controlling the state of plasma generated when a thin film is formed by sputtering, for example.

  In the production of functional films used for touch panels, organic EL lighting, etc., reactivity that enables film formation at lower temperatures than other film formation methods to avoid damage to the film during film formation A sputtering method is used.

  In this reactive sputtering method, as shown in Patent Document 1, a target such as Al, ITO, Si or the like and a substrate such as a substrate or a film on which the thin film is formed are arranged in a vacuum chamber so as to face each other. At the same time, a film is formed by generating plasma by applying a high magnetic field between the target and the substrate while flowing a rare gas such as Ar and reactive gases such as O 2 and N 2 into the vacuum chamber. Is the method. In this way, the plasma blows off the ions that make up the target and deposits compounds such as oxides and nitrides formed by the reaction between the blown ions and the reactive gas on the surface of the substrate. Thus, film formation can be performed.

  By the way, in the reactive sputtering method as described above, the plasma state changes depending on the flow rate of the reactive gas flowing into the vacuum chamber, and the film formation speed or film formation of the oxide film or the like formed on the substrate is changed. It is known that the form changes. More specifically, when the flow rate of the reactive gas is increased while keeping the Ar gas at a constant flow rate, the deposition rate in the order of the metal mode, transition region, and reactive mode as shown in FIG. The form of film formation changes.

  Explaining each reaction mode, the metal mode in which the reactive gas appears in a small flow rate has a high film forming speed, but the reactive gas flow rate is too small for ions to be blown off from the target. This is a film formation mode in which a target that has not undergone a chemical reaction is deposited on a substrate. In other words, the metal mode is close to the normal sputtering state, and film formation with a desired compound cannot be performed.

  On the other hand, in the reactive mode where the reactive gas appears at a large flow rate, the reactive gas is excessive with respect to the ions ejected from the target, so that not only the ions ejected from the target react with the reactive gas. The reaction with the reactive gas occurs on the surface of the target itself. For this reason, although the target can react with the reactive gas and deposit the compound formed on the surface of the base material, the film formation rate becomes low.

  In contrast to these modes, the transition region between the metal mode and the reactive mode is a very narrow interval as the reactive gas flow rate, as is clear from FIG. Since only the extended ions are a region that reacts with the reactive gas, it is possible to form a desired compound at a rate 5 to 6 times faster than the reactive mode.

  For this reason, in the reactive sputtering method, it is required that the flow rate of the reactive gas flowing into the vacuum chamber is controlled to continuously perform film formation in the transition region. Conventionally, a plasma control apparatus 100A as shown in FIG. 4 is used for the purpose of maintaining the film formation state in such a transition region. This is provided on a flow path L1 for introducing a reactive gas into the vacuum chamber VC, a mass flow controller 1A for controlling the flow rate of the introduced gas, and a plasma monitor 3A for measuring the plasma intensity in the vacuum chamber VC. And. Then, the plasma intensity in the transition region is set as the set plasma intensity, and the flow rate of the introduced gas is feedback-controlled by the mass flow controller 1A so that the deviation between the measured plasma intensity measured by the plasma monitor and the set plasma intensity becomes small. doing.

  However, as shown in FIG. 5, the flow region of the reactive gas serving as the transition region is very narrow and the flow rate value is relatively large, so that the reactivity is maintained even when the plasma state fluctuates. It is difficult to keep the gas flow rate at an optimum value and keep it in the state of the transition region. In practice, the film forming speed cannot be kept high. More specifically, since the flow rate of the reactive gas to be flowed is large, it is necessary to select a mass flow controller with a large controllable range. In such a mass flow controller, the flow rate that actually flows is a narrow flow rate that becomes a transition region. It is difficult to achieve high responsiveness that can be kept in the section. On the other hand, when only a highly responsive valve capable of controlling the flow rate in a narrow flow rate section that is a transition region is used, the movable range of the valve is too small, so that the necessary flow rate value cannot flow in the first place. .

  Furthermore, as shown in FIG. 5, since there is hysteresis in the relationship between the flow rate of the reactive gas and the form of film formation, the responsiveness of the mass flow controller is insufficient, and the follow-up fails and excessive reaction occurs even once. If the sex gas is introduced into the vacuum chamber, it takes a very long time to go around the reaction path to restore the original state.

JP-A-2-290966

  The present invention has been made in view of the above-described problems, and even when the flow rate value of the introduced gas to be introduced into the vacuum chamber is large, the flow rate can be controlled at a high speed in a narrow section near the flow rate value. An object of the present invention is to provide a plasma control device, a flow rate control device, and a flow rate control program capable of maintaining the plasma in a vacuum chamber in a desired state and maintaining the optimum state for film formation.

That is, the plasma control apparatus of the present invention forms a film on the surface of a base material in a vacuum chamber in which plasma is generated, is connected to the vacuum chamber, and is introduced into the vacuum chamber. A first valve provided on the first flow path through which the reactive gas flows, and the flow rate of the reactive gas introduced into the vacuum chamber via the first valve is the first flow rate. A first valve controller that controls the opening of the valve, a plasma monitor that measures the plasma intensity of the plasma generated in the vacuum chamber, and the downstream of the first valve of the first flow path, or A second valve connected to the vacuum chamber and provided on a second flow path through which the reactive gas flows, a measured plasma intensity measured by the plasma monitor, and a preset plasma set in advance A second valve control unit that controls the opening degree of the second valve based on a deviation from the intensity, and the set plasma intensity increases the flow rate of the reactive gas, and the form of film formation is a plasma intensity when the transition from the metal mode to the middle of the transition region extending into a reactive mode from the metal mode, the first flow rate, at a value smaller than the flow rate of the reactive gas when the said transition region And the film forming mode is set to a flow rate at which the metal mode is set. Here, the “vacuum chamber” is a concept including a chamber that is depressurized to a pressure suitable for generating plasma as well as a complete vacuum.

  In such a case, the first valve provided on the first flow path first secures the first flow rate as the flow rate introduced into the vacuum chamber, and then the plasma monitor uses the first flow rate. Only the flow rate corresponding to the measured plasma intensity deviation can be controlled by the second valve provided on the second flow path. From this, the second valve only needs to control the flow rate of the introduced gas corresponding to the deviation that can occur in the measured plasma intensity, so the control range is limited. A responsive valve can be selected. Therefore, even if the optimum flow rate value necessary to obtain the desired set plasma intensity is a relatively large value and the allowable flow rate error is small, the first flow rate is close to the optimum flow rate value. Thus, it is possible to perform high-speed control by controlling the variation with the second flow rate.

  And since the plasma control apparatus of the present invention has the flow rate control characteristics as described above, for example, in the case of film formation by the reactive sputtering method, the flow rate value of the reactive gas to be introduced is relatively large, In addition, it is possible to continue to maintain even a transition region where the range of allowable flow rate values is narrow. Therefore, the film formation rate can be improved 5 to 6 times compared to the conventional case.

  In order to prevent problems such as excessive introduction gas being introduced only by the first flow rate, the desired plasma intensity cannot be achieved, or the second valve is fixed in a fully closed state. When the introduced gas is introduced into the vacuum chamber only at the first flow rate, the first flow rate is set so that the measured plasma intensity measured by the plasma monitor is smaller than the set plasma intensity. It only has to be set. In such a case, particularly when the introduced gas is a reactive gas and the reactive sputtering method is used, the plasma state can be shifted from the metal mode to the transition region, and in a shorter time. A film can be formed.

  In order to make it easy to select a highly responsive valve for the second valve and to improve the accuracy of the flow rate control of the introduced gas introduced into the vacuum chamber, the first valve control is performed with the second flow control. The opening degree of the first valve is controlled so that the second flow rate, which is the flow rate of the introduced gas introduced into the vacuum chamber via a path, is smaller than the first flow rate. The second valve and the valve control unit may be configured to have higher responsiveness than the first valve and the first valve control unit. That is, the second valve may have a movable range narrower than that of the first valve, and a valve specialized for responsiveness can be selected. Here, the responsiveness of each valve and each valve control unit relates to the follow-up performance of the output value with respect to the target value in the open loop or the closed loop, and is based on, for example, a control evaluation value such as an overshoot amount or a settling time. Are compared.

  For example, a specific example of the second valve having high response suitable for maintaining the transition region in the reactive sputtering method includes a piezo valve.

  As a specific embodiment for accurately measuring the plasma intensity and facilitating maintaining a desired plasma state, the plasma monitor is based on the intensity of light emitted from the plasma in the vacuum chamber. One that measures plasma intensity is included.

Compared to conventional plasma control devices, the flow rate control capability of the reactive gas introduced into the vacuum chamber is improved, and it becomes possible to continue to control a desired plasma state such as a transition region in the reactive sputtering method, for example. The flow control device is connected to a vacuum chamber in which plasma is generated, and includes a first valve provided on a first flow path through which a reactive gas introduced into the vacuum chamber flows, and the first valve A first valve control unit for controlling the opening of the first valve so that the flow rate of the reactive gas introduced into the vacuum chamber via the first flow rate becomes a first flow rate, and generated in the vacuum chamber. A flow rate control device used in a plasma control device for forming a film on the surface of a substrate in the vacuum chamber. The second valve connected to the vacuum chamber downstream of the first valve in the first flow path, or provided on the second flow path through which the reactive gas flows, and the plasma monitor. A second valve control unit that controls an opening degree of the second valve based on a deviation between the measured plasma intensity and a preset plasma intensity that is set in advance, and the preset plasma intensity is the reactive gas. The first flow rate is the transition region when the flow rate of the film is increased and the film formation mode shifts from the metal mode to the transition region on the way from the metal mode to the reactive mode. Any value may be used as long as the flow rate is smaller than the flow rate of the reactive gas at the time and the film forming mode is set to a flow rate at which the metal mode is set.

  In such a case, the transition region in the reactive sputtering method can be maintained only by adding the flow rate control device having the second valve and the second valve control unit to the conventional plasma control device. It becomes possible.

For example, in order to be able to control the plasma state accurately by simply rewriting the control program in a computer or the like constituting an existing plasma control device, the plasma is connected to a vacuum chamber in which plasma is generated, A first valve provided on a first flow path through which a reactive gas introduced into the vacuum chamber flows; a plasma monitor for measuring plasma intensity of plasma generated in the vacuum chamber; and the first flow path A second valve provided on a second flow path downstream of the first valve or connected to the vacuum chamber and through which the reactive gas flows, and comprising a substrate in the vacuum chamber A flow rate control program used in a plasma control apparatus for forming a film on a surface, wherein the reactivity is introduced into the vacuum chamber via the first valve. Deviation between the first valve control unit that controls the opening degree of the first valve so that the flow rate of the gas becomes the first flow rate, the measured plasma intensity measured by the plasma monitor, and the preset plasma intensity set in advance A second valve control unit that controls the opening degree of the second valve based on the above, wherein the set plasma intensity increases the flow rate of the reactive gas, and the form of film formation reacts from the metal mode. a plasma intensity when the middle of the transition region leading to sexual mode, the first flow rate is smaller than the flow rate of the reactive gas when a transition from the metal mode to the transition region, the formed Any flow rate control program characterized in that the film form is set to a flow rate in the metal mode . Further, if there is a recording medium in which the flow rate control program is recorded, a new flow rate control program can be installed in a computer constituting various plasma control apparatuses to obtain the above-described effects.

  As described above, according to the plasma control device and the flow rate control device of the present invention, the flow rate corresponding to the deviation between the measured plasma intensity measured by the plasma monitor and the set plasma intensity is set while flowing the predetermined flow rate through the first valve. Since the second valve is configured to be controlled, it is possible to use the second valve having high responsiveness even if the movable range is narrow. Therefore, even when the flow rate of the introduced gas to be introduced into the vacuum chamber is large and the allowable flow rate error is small, the flow rate control of the introduced gas can be performed at a high speed. It is possible to continue to maintain the transition region in the reactive sputtering method.

The schematic diagram which shows the structure of the plasma control apparatus which concerns on one Embodiment of this invention. The typical graph which shows the concept of the flow control in the embodiment. The schematic diagram which shows the case where the flow control apparatus in another embodiment of this invention is added to the existing plasma control apparatus. The schematic diagram which shows an example of the conventional plasma control apparatus. The typical graph which shows the change of the form of film-forming with respect to the flow volume of the reactive gas in the reactive sputtering method, and the change of the film-forming speed | rate.

  An embodiment of the present invention will be described with reference to the drawings.

  The plasma control apparatus 100 of the present embodiment deposits a target T and a reactive gas compound on the surface of a base material B such as a wafer or a film placed in the vacuum chamber VC by reactive sputtering to form a film. belongs to. For example, examples of the target T include Al, ITO, Si, and examples of the reactive gas include oxygen and nitrogen. Then, using this plasma control apparatus 100, an oxide or nitride thin film of a substance constituting the target T is formed on the surface of the base material B, and a material used for a touch panel or the like is formed.

  More specifically, as shown in FIG. 1, the plasma control apparatus 100 includes a rare gas such as Ar, which is an introduction gas introduced into the vacuum chamber VC in which plasma is generated, and a reactive gas such as oxygen. Of these, the flow rate of the reactive gas is mainly controlled. That is, the plasma control apparatus 100 includes a rare gas line NGL connected to the vacuum chamber VC, a fluid control mechanism FC provided in the reactive gas line RGL among the reactive gas lines RGL, and an inside thereof. A plasma monitor 3 that monitors the state of plasma in the vacuum chamber VC, which is a chamber maintained in a decompressed state, and a control unit that controls the fluid control mechanism FC based on an output signal from the plasma monitor 3 C.

  Each part will be described. In the following description, the flow rate is described as including both concepts of mass flow rate and volume flow rate.

  The inside of the vacuum chamber VC is kept at a high vacuum, and a target T which is a lump of metal such as Al or ITO or Si to be attached as a thin film inside the vacuum chamber VC and the target T are provided opposite to the target T. The base material B is accommodated. Between the target T and the base material B, Ar and reactive gas flow from the rare gas line NGL and the reactive gas line RGL, respectively. Furthermore, plasma is generated by the introduced gas by a voltage application unit that applies a high voltage between the target T and the base material B.

  A mass flow controller 4 is provided on the piping constituting the rare gas line NGL, and Ar is introduced into the vacuum chamber VC at a constant flow rate.

  The reactive gas line RGL is connected to the vacuum chamber VC, and is formed in parallel with the first flow path L1 through which the reactive gas introduced into the vacuum chamber VC flows and the first flow path L1. Second flow path L2.

  A mass flow controller 1 is provided on the first flow path L1 in order to keep a predetermined first flow rate always constant. The mass flow controller 1 includes at least a flow rate sensor 13, a flow rate control valve 11 corresponding to the first valve in the claims, and a flow rate control controller 12 that controls the opening degree of the flow rate control valve 11. One package is constituted. The flow controller 12 corresponds to the first valve controller in the claims, and exhibits its function by, for example, a microcomputer or a control board. More specifically, the flow rate controller 12 controls the flow rate control valve 11 so that a deviation between a measured flow rate measured by the flow rate sensor 13 and a first flow rate that is a preset set flow rate becomes small. The opening degree is feedback-controlled. The set flow rate set in the flow rate controller 12 can be input by the mass flow controller 1 itself, or can be appropriately changed by, for example, an external input from the control unit C described later. As described above, the mass flow controller 1 provided on the first flow path L1 performs flow rate control so that the flow rate of the reactive gas passing through its flow rate control valve 11 becomes the first flow rate. At least the first flow rate of the reactive gas continuously flows into the vacuum chamber VC at a substantially constant flow rate.

  The second flow path L <b> 2 is a flow path formed so as to branch from the upstream of the mass flow controller 1 to the first flow path L <b> 1 and join again to the downstream of the mass flow controller 1. A piezoelectric valve 21 corresponding to the second valve in the claims is provided on the second flow path L2. The piezo valve 21 has a narrower movable range than the flow rate control valve 11 and a smaller flow rate range. However, the combination of the piezo valve 21 and a piezo valve control unit 22 to be described later is configured to have higher responsiveness than the combination of the flow control valve 11 and the flow control controller 12. That is, the piezo valve 21 provided in the second flow path L2 is configured so that a small amount of the second flow rate flows compared to the first flow rate passing through the flow rate control valve 11, and flows into the vacuum chamber VC. The flow rate control is performed only for the difference between the target flow rate to be set and the first flow rate.

  Thus, the flow rate of the reactive gas introduced into the vacuum chamber VC is controlled by the mass flow controller 1 provided on the first flow path L1 and the piezo valve 21 provided on the second flow path L2. The fluid control mechanism FC is configured.

  The plasma monitor 3 is provided so as to face between the target T and the base material B in the vacuum chamber VC, and a light acquisition unit that acquires light from the generated plasma, and the light sampling unit 31 and an optical fiber 32 connected to each other to change the light from the plasma into an electrical signal corresponding to the intensity, and the plasma intensity for outputting the plasma intensity of the plasma based on the electrical signal from the photomultiplier 33 And a calculation unit.

  The control unit C is realized by a so-called computer having a CPU, a memory, an A / D, a D / A converter, an input / output interface, and the like. Based on a program stored in the memory, At least the function as the piezo valve control unit 22 is exhibited.

  The piezo valve control unit 22 corresponds to the second valve control unit in the claims, and is based on a deviation between a measured plasma intensity measured by the plasma monitor 3 and a preset plasma intensity set in advance. The opening degree of the piezo valve 21 is controlled.

  The set plasma intensity is determined by measuring in advance in the preparation before starting actual product manufacture. More specifically, the flow rate of the reactive gas introduced into the vacuum chamber VC from the reactive gas line RGL is increased little by little, and the transition of the film formation mode from the metal mode to the reactive mode is made. The plasma intensity when the region is reached is set as the set plasma intensity. For example, when the plasma intensity measured by the plasma monitor 3 reaches the maximum value when the flow rate of the reactive gas is a flow rate suitable for the transition region, the maximum plasma intensity observed in the preparation is Set as set plasma intensity. The first flow rate value set as the flow rate to be flowed to the mass flow controller 1 is smaller than the appropriate flow rate that is the flow rate of the reactive gas when the maximum plasma intensity is reached, that is, when the set plasma intensity is reached. A value slightly smaller than the flow rate of the reactive gas. More preferably, the difference between the first flow rate and the appropriate flow rate at the set plasma intensity is the maximum that can be caused to flow into the vacuum chamber VC via the second flow path L2 by the piezo valve 21. It may be set smaller than the flow rate. In other words, the first flow rate is set so that the difference between the appropriate flow rate and the first flow rate falls within the flow controllable range determined from the movable range of the piezo valve 21.

  The operation of the piezo valve control unit 22 when the plasma intensity reaches the maximum value when the transition region is reached will be described more specifically. From a state in which the reactive gas is kept flowing into the vacuum chamber VC by the first flow rate by the mass flow controller 1, the piezo valve control unit 22 determines the opening degree of the piezo valve 21 and the measured plasma intensity. Increasing the amount of feedback by the PID calculation for the set plasma intensity deviation. If a deviation occurs again between the measured plasma intensity and the set plasma intensity after the plasma intensity in the vacuum chamber VC reaches the set intensity, the piezo valve control unit 22 until the deviation occurs again. The direction in which the opening degree of the piezo valve 21 is changed is changed according to the increase / decrease tendency of the piezo valve 21. That is, the piezo valve control unit 22 determines that the deviation occurs again after the measured plasma intensity measured by the plasma monitor 3 reaches the set plasma intensity in a state where the opening degree of the piezo valve 21 tends to increase. The opening degree of the piezo valve 21 is decreased by the feedback amount obtained by performing the PID calculation on the deviation. Conversely, when a deviation occurs again after the measured plasma intensity measured by the plasma monitor 3 reaches the set plasma intensity in a state where the opening degree of the piezo valve 21 tends to decrease, PID calculation is performed on the deviation. The opening degree of the piezo valve 21 is increased by the amount of feedback performed. For example, an increase / decrease tendency may be acquired based on a time change amount or a time derivative with respect to the opening degree of the piezo valve 21, and the piezo valve control unit 22 may control the opening degree of the piezo valve 21.

  Next, the operation of the piezo valve control unit 22 when the plasma intensity observed from the plasma generated during the transition from the metal mode to the reactive mode through the transition region is monotonically increasing or monotonically decreasing will be described. To do. For example, in the metal mode, the increase rate of the plasma intensity with respect to the flow rate of the reactive gas flowing into the vacuum chamber VC is small, the increase rate of the plasma intensity rapidly increases in the transition region, and the increase rate of the plasma intensity again in the reactive mode. Consider the case where becomes smaller.

  In this way, when the plasma intensity monotonously increases or monotonously decreases with respect to the flow rate of the reactive gas flowing into the vacuum chamber VC, an arbitrary plasma intensity in the transition region obtained in advance as an experiment is set as the set plasma intensity. Just by setting, either plus or minus appears in the deviation from the measured plasma intensity, and the control direction of the piezo valve 21 is uniquely determined. Therefore, the opening degree of the piezo valve 21 is controlled by the piezo valve control unit 22 by normal feedback control without checking the increase / decrease tendency as described above.

  According to the plasma control apparatus 100 configured in this way, as shown in the graph of FIG. 2, the flow rate of the reactive gas necessary for generating the plasma with the set plasma intensity is largely changed. While the mass flow controller 1 provided on the first flow path L1 causes the mass flow controller 1 to flow at a constant flow rate, the required amount of the reactive gas caused by the change in the plasma state is provided on the second flow path L2. In addition, it can be introduced into the vacuum chamber VC by controlling the piezo valve 21 having high responsiveness as the second flow rate. For this reason, according to the plasma control apparatus 100 of the present embodiment, the flow rate of the reactive gas to be flowed into the vacuum chamber VC is large as in the case of continuously performing film formation in the transition region in the reactive sputtering method. Therefore, the flow rate range of the reactive gas must be wide, and the flow rate of the reactive gas is high-speed response even under severe flow rate control conditions where the allowable amount of flow rate control error is very small relative to the order of the flow rate control range. The film formation can be maintained in the transition region.

  Further, since the piezo valve 21 is controlled based on the measured plasma intensity actually measured by the plasma monitor 3 and the deviation of the set plasma intensity, the flow rate can be controlled based on the quantity directly representing the plasma state. It is easy to keep the film formation state in the transition state. In addition, the mass flow controller 1 is configured to keep a constant flow rate without feeding back the deviation between the measured plasma intensity and the set plasma intensity, so that the reactive gas flow control system is kept stable. Cheap.

  Further, in the plasma control apparatus 100 of the present embodiment, the first flow rate of the reactive gas that is flowed at a constant flow rate by the mass flow controller 1 is set to a flow rate that is smaller than the flow rate that is the set plasma intensity. Since the control is performed so that the set plasma intensity is set at the second flow rate caused by the flow 21, the form of film formation can be controlled to shift from the metal mode to the transition region. If the reactive gas is excessively introduced into the vacuum chamber VC and the transition from the reactive mode to the transition region is attempted, the reactive gas reacts with the target T itself and an oxide film or the like is formed on the target T. As a result, ions are less likely to be ejected from the target T, and the film formation rate is delayed for a while. On the other hand, since this embodiment can be shifted from the metal mode to the transition region and stabilized in that state, the film formation rate is 5 to 6 times that in the case where the conventional reactive mode has been stabilized. A film formed by depositing a compound formed by reacting ions of the target T with a reactive gas on the base material B can be formed.

  Next, another embodiment of the present invention will be described. In the following description, the same reference numerals are given to members corresponding to the above-described embodiment.

  In the embodiment shown in FIG. 3, by adding the flow rate control device of the present invention to the existing plasma control device 100, it is possible to improve the flow rate control performance and keep the form of film formation in the transition region. .

  As shown in FIG. 4 described in the background art, the existing plasma control apparatus 100 includes a rare gas line NGL for introducing a rare gas into a vacuum chamber VC where plasma is generated, and a reactive gas in the vacuum chamber VC. The reactive gas line RGL for introducing the plasma, the plasma monitor 3A for measuring the intensity of the plasma generated in the vacuum chamber VC, and the reactive gas line RGL based on the plasma intensity output from the plasma monitor 3A And a control unit C that controls the flow rate of the reactive gas. Here, in the conventional plasma control apparatus 100A, the reactive gas line RGL has only one flow path, and a mass flow controller 1A for controlling the flow rate of the reactive gas is provided on the flow path. . The controller C is configured to perform a PID calculation based on a deviation between the measured plasma intensity measured by the plasma monitor 3A and the set plasma intensity, and to input a flow rate command value to the mass flow controller 1. . Based on the deviation between the flow rate command value and the measured flow rate value, the opening degree of the flow rate control valve 11A inside the mass flow controller 1A is controlled.

  In order to add a flow rate control device 200 of the present invention having a second valve and a second valve control unit to such an existing plasma control device 100, the mass flow controller 1 as shown in FIG. The provided flow path is referred to as a first flow path L1, and a second flow path L2 that is provided in parallel to the first flow path L1 and joins downstream of the mass flow controller 1 is formed. Further, by providing a piezo valve 21 as a second valve on the second flow path L2, and storing a new program in the memory of the control unit C, the measured plasma intensity output from the plasma monitor 3, A second valve control unit that controls the opening degree of the piezo valve 21 based on the deviation from the set plasma intensity is configured. Further, the connection is canceled so that the exchange of plasma intensity is not performed between the mass flow controller 1 and the control unit C, and the reactive gas is continuously supplied to the mass flow controller 1A at the first flow rate. Set to.

  As described above, the piezoelectric valve 21 and a program for controlling the piezo valve 21 are installed in the existing plasma control apparatus 100A and the piezo valve control unit 22 is configured. can do. That is, by using the flow rate control device of the present invention in the existing plasma control device 100 in this way, it is possible to keep the film formation mode in the transition region, and to increase the film formation rate 5-6 times the conventional one. It becomes.

  Other embodiments will be described.

  In the above embodiment, the control of the flow rate of the reactive gas introduced into the vacuum chamber has been described on the assumption that the reactive sputtering method is performed. For example, the flow rate of a rare gas such as Ar to be introduced is controlled. However, the configuration of the present invention may be used. Further, the plasma control device and the flow rate control device of the present invention are not particularly limited to use in the reactive sputtering method, and may be used for plasma control in a normal sputtering method. In other words, the introduced gas in the claims is not particularly limited to the reactive gas, and any gas may be used as long as the state of the plasma in the vacuum chamber is controlled by the flow rate introduced into the vacuum chamber. The present invention may be used for control.

  In the above-described embodiment, the second flow path is provided so as to merge with the first flow path. However, for example, the introduction gas flowing through the first flow path and the introduction gas flowing through the second flow path in the vacuum chamber are You may make it join. The junction of the second flow path with respect to the first flow path only needs to be downstream of the first valve, and the flow rate of the introduced gas actually introduced into the vacuum chamber by being closer to the vacuum chamber. Accuracy can be improved. Furthermore, the second valve is not limited to a piezo valve, and may be any valve that is more responsive than the first valve provided in the first flow path, for example.

  Furthermore, a device for performing flow rate control such as a mass flow controller is not packaged on the first flow path, and each device may be attached alone. That is, the first valve and the flow rate measurement sensor may be provided separately on the first flow path, and the function as the first valve control unit may be exhibited by the control unit. In addition, the first valve control unit and the second valve control unit may be configured in one place using a computer, and the function is realized by a microcomputer or the like provided in each installation place. It may be a thing.

  The plasma monitor measures the plasma intensity based not only on the intensity of the light emitted from the plasma but also on the impedance change of the power source that applies the voltage to generate the plasma. It doesn't matter if you do it.

  In the operation of the embodiment, the flow rate of the introduced gas is controlled so that the plasma state changes from the metal mode to the transition region and then to the reactive mode, but conversely, from the reactive mode to the transition region and the metal mode. It is also possible to maintain the plasma state using a route that leads to That is, an introduction gas slightly larger than the flow rate that becomes the transition region is first introduced into the vacuum chamber, and the flow rate of the introduction gas is gradually reduced by the second valve in accordance with the measured plasma intensity. It doesn't matter if you do.

  In the above embodiment, the mass flow controller provided in the first flow path performs feedback control so that the flow rate passing through the mass flow controller is always kept constant at the first flow rate. Depending on the type of the first flow rate, the first flow rate may change every time. Furthermore, the first valve provided in the first flow path does not necessarily require feedback control, and may be one that controls the flow rate so as to be maintained at the first flow rate by feedforward control, for example. . In addition, the opening degree of the first valve may only be maintained at a predetermined opening degree corresponding to the first flow rate. For example, after the first valve control unit controls the opening degree of the first valve to a predetermined opening degree, the opening degree of the first valve is fixed at the predetermined opening degree without performing any control. May be.

  In addition, it goes without saying that various modifications and combinations of embodiments may be made without departing from the spirit of the present invention.

100 ... Plasma control device
200 ... Flow control device 11 ... Flow control valve (first valve)
12 ・ ・ ・ Flow controller (first valve controller)
21 ... Piezo valve (second valve)
22... Piezo valve control unit (second valve control unit)
3 ... Plasma monitor L1 ... 1st flow path L2 ... 2nd flow path VC ... Vacuum chamber

Claims (6)

A film is formed on the surface of a substrate in a vacuum chamber where plasma is generated,
A first valve connected to the vacuum chamber and provided on a first flow path through which a reactive gas introduced into the vacuum chamber flows;
A first valve controller that controls an opening of the first valve so that a flow rate of the reactive gas introduced into the vacuum chamber via the first valve becomes a first flow rate;
A plasma monitor for measuring the plasma intensity of the plasma generated in the vacuum chamber;
One end is upstream of the first valve of the first flow path, and the other end is merged downstream of the first valve of the first flow path, or the other end is connected to the vacuum chamber. A second valve provided on a second flow path through which the reactive gas flows;
A second valve control unit that controls an opening degree of the second valve based on a deviation between a measured plasma intensity measured by the plasma monitor and a preset plasma intensity set in advance,
The second valve is configured to have higher responsiveness than the first valve;
The set plasma intensity is the plasma intensity when the flow rate of the reactive gas is increased, and the film formation mode shifts from the metal mode to the transition region in the middle from the metal mode to the reactive mode,
The first flow rate is a value smaller than the flow rate of the reactive gas at the time of becoming the transition region, and the film formation mode is set to a flow rate at which the metal mode is set. .   When the reactive gas is introduced into the vacuum chamber only with the first flow rate, the first flow rate is set so that the measured plasma intensity measured by the plasma monitor is smaller than the set plasma intensity. The plasma control apparatus according to claim 1, wherein the plasma control apparatus is set.   In the first valve control, the second flow rate, which is the flow rate of the reactive gas introduced into the vacuum chamber via the second flow path, is smaller than the first flow rate. The plasma control apparatus according to claim 1 or 2, wherein the opening degree of one valve is controlled.   The plasma control apparatus according to claim 1, wherein the second valve is a piezo valve.   The plasma control apparatus according to claim 1, wherein the plasma monitor measures the plasma intensity based on an intensity of light emitted from plasma in the vacuum chamber. A vacuum valve connected to a vacuum chamber in which plasma is generated, a first valve provided on a first flow path through which a reactive gas introduced into the vacuum chamber flows, and the vacuum chamber via the first valve A first valve control unit for controlling the opening of the first valve so that the flow rate of the reactive gas introduced into the first flow rate becomes a first flow rate, and the plasma intensity of the plasma generated in the vacuum chamber. A flow rate control device used in a plasma control device for forming a film on a surface of a base material in the vacuum chamber,
One end is upstream of the first valve of the first flow path, and the other end is merged downstream of the first valve of the first flow path, or the other end is connected to the vacuum chamber. A second valve provided on a second flow path through which the reactive gas flows;
A second valve control unit that controls an opening degree of the second valve based on a deviation between a measured plasma intensity measured by the plasma monitor and a preset plasma intensity set in advance,
The second valve is configured to have higher responsiveness than the first valve;
The set plasma intensity is the plasma intensity when the flow rate of the reactive gas is increased, and the film formation mode shifts from the metal mode to the transition region in the middle from the metal mode to the reactive mode,
The first flow rate is a value smaller than the flow rate of the reactive gas at the time of becoming the transition region, and the flow rate control device is set to a flow rate at which the film formation mode is a metal mode. .