JP7620094B2 - SPUTTERING APPARATUS, METHOD FOR CONTROLLING SPUTTERING APPARATUS, AND CONTROL APPARATUS FOR SPUTTERING APPARATUS - Google Patents

Description

The present invention relates to a sputtering apparatus having one or more cathodes with one or more magnet units arranged behind a target, a control method thereof, and a control device for the sputtering apparatus.

A magnetron sputtering device, in which one or more magnet units are arranged on the back surface (non-sputtering surface) of the target, is known as a deposition device for large-area substrates. The deposition uniformity (e.g., film thickness and sheet resistance) on the substrate surface on which a film is deposited using a magnetron sputtering device is an important performance factor for the substrate, and maintaining this uniformity is an extremely important function required of a sputtering device.

In magnetron sputtering devices, the higher the horizontal magnetic flux density (magnetic flux density perpendicular to the electric field) on the target surface (sputtering surface), the higher the erosion rate of the target surface by the plasma, and as a result, more deposition material is released from the target surface, enabling high-speed deposition on the substrate surface. Typically, the higher the horizontal magnetic flux density in an area on the target surface, the higher the deposition rate on the surface area of the substrate facing that area tends to be relative to other surface areas.

Therefore, when depositing films on large substrates using a magnetron sputtering device, the distribution of horizontal magnetic field density has a large effect on the uniformity of film quality within the substrate surface. In order to deposit films with uniform quality, it is necessary to appropriately set the position or movement pattern of the magnet unit and the magnetic force strength or magnetic force strength fluctuation pattern.

Known methods for homogenizing film quality by setting the position or movement pattern of the magnet unit include a technique for moving the magnet unit back and forth along the back surface of the target (see, for example, Patent Document 1) and a technique for moving the magnet unit in a direction toward or away from the back surface of the target (see, for example, Patent Document 2). Patent Document 3 discloses a rotary cathode that includes a cylindrical target and multiple magnet units arranged inside it, and that rotates the surface of the target in a circumferential direction to scan the area where a magnetic field is formed on the surface of the target in a circumferential direction.

JP 2000-239841 A JP 2020-200525 A JP 2016-113646 A

Because the shape of the target surface changes as erosion progresses, the distribution of film quality also changes over time. Therefore, in order to maintain the homogeneity of the film quality, it is necessary to continually set the optimal magnet unit position or movement pattern and magnetic force strength or magnetic force strength variation pattern over time.

However, it is difficult to accurately predict the progression of erosion because the rate at which erosion progresses is affected by a variety of factors, including pressure, applied voltage, amount of sputtering gas inflow, target constituent material, and target quality differences. In addition, because erosion progresses faster in areas with higher horizontal magnetic flux density, the difference between the predicted and actual erosion progression accelerates over time.

Therefore, it is difficult to preset the optimal magnet unit position or movement pattern and magnetic strength or magnetic strength fluctuation pattern as a function of time, and in reality, it is necessary to periodically carry out a series of tasks: checking the deposition state of the deposited substrate, stopping the apparatus, and adjusting the magnet unit position or movement pattern and magnetic strength or magnetic strength fluctuation pattern. The implementation of this task is one of the causes of reduced equipment operating rates, and this problem is more likely to occur as the substrate becomes larger.

In addition, individual differences are generally unavoidable even among industrial products produced to the same design. Therefore, when installing multiple sputtering equipment, it may not be possible to obtain the same distribution of film quality even if all recognizable film formation conditions are unified. In such cases, tuning of the magnet unit position or movement pattern and magnetic strength or magnetic strength fluctuation pattern is required for each device, which becomes one of the problems that must be solved when operating the equipment.

In view of the above circumstances, the object of the present invention is to provide a sputtering apparatus, a control method thereof, and a control device for a sputtering apparatus that can improve film deposition uniformity and equipment operating rate.

A sputtering apparatus according to one aspect of the present invention comprises:
One or more targets arranged opposite the substrate and made of a deposition material;
one or more magnet units disposed on a rear surface of the target;
a control device having an optimal solution calculation unit that calculates an optimal solution of the setting conditions for at least one of the magnet units based on input information including at least one of setting conditions including a position of each of the magnet units, a movement pattern of each of the magnet units, and an inflow current or an inflow current fluctuation pattern of an electromagnet constituting each of the magnet units, and a measurement value of a film quality of a film formed on the substrate by the sputtering device;
and an adjustment unit capable of individually adjusting the setting conditions of the magnet units based on the optimal solution.

The sputtering apparatus may be connected to an apparatus for measuring the film quality of the film-forming material on the substrate, so as to automatically acquire the measured values, calculate the optimal solution, and adjust the setting conditions based on the optimal solution.

The target may be a flat target used with a planar cathode or a cylindrical target used with a rotary cathode. One target may correspond to one or more magnet units.

The position of the magnet unit indicates the relative positional relationship between the target corresponding to the magnet unit and the magnet unit. That is, for a flat target, it indicates the relative position of the magnet unit with respect to any reference plane parallel to the target. For a cylindrical target, it indicates the relative position of the magnet unit with respect to the central axis of rotation of the target.

The movement pattern of the magnet unit refers to the pattern of change in the position of the magnet unit over time when film formation is performed on a substrate while varying the position of the magnet unit.

The inflow current of the magnet unit refers to the current flowing through the coil to generate magnetic force when some or all of the magnets constituting the magnet unit are electromagnets.

The inflow current variation pattern of the magnet unit refers to the pattern of change over time in the inflow current of the magnet unit when a film is formed on a substrate while varying the inflow current of the magnet unit.

The film quality includes one or more of the physical properties that indicate the characteristics of the film formed by the sputtering device. The physical properties that indicate the characteristics of the film include, for example, film thickness, sheet resistance, light transmittance, film stress, refractive index, etching characteristics, and film density.

The measured values of the film quality of the film-forming material on the substrate include measurement data regarding the film quality of the film-forming material at multiple measurement points on the substrate.

The input information may further include information on one or more factors that may affect the distribution of the film quality. The factors that may affect the distribution of the film quality include, for example, the type of the film-forming material, the surface shape of the target, the voltage applied to the target, the discharge time, the type of sputtering gas, and the pressure during film formation.

The optimal solution calculation unit is configured to calculate, based on the input information, an optimal solution for at least one of the position of each magnet unit, the movement pattern of each magnet unit, the inflow current of the electromagnets constituting each magnet unit, and the inflow current fluctuation pattern of the electromagnets constituting each magnet unit that can satisfy a specified film quality distribution control value.

The optimal solution can be calculated using, for example, a machine learning machine that has learned actual film formation results, a simulation using a mathematical model, or a degenerate model in which the parts of the mathematical model that have a large computational load are reconstructed using a machine learning machine.
In addition, the machine learning machine, the mathematical model, or the degenerated model that directly outputs the optimal solution may be used, or a combination of the machine learning machine, the mathematical model, or the degenerated model that outputs a predicted film quality distribution for any candidate for the optimal solution and a mathematical optimization program that searches for a candidate for the optimal solution that optimizes the predicted film quality distribution may be used.

A method for controlling a sputtering apparatus according to one embodiment of the present invention is a method for controlling a sputtering apparatus including one or more targets arranged facing a substrate and made of a film forming material, and one or more magnet units arranged on a rear surface of the targets, the method comprising the steps of:
Calculating an optimal solution of the setting conditions for at least one of the magnet units based on input information including at least setting conditions including a position of each of the magnet units, a movement pattern of each of the magnet units, and at least one of an inflow current or an inflow current fluctuation pattern of an electromagnet constituting each of the magnet units, and a measurement value of a film quality of a film formed on the substrate by the sputtering apparatus;
Based on the optimal solution, the setting conditions of the magnet units are individually adjusted.

A sputtering apparatus control device according to one embodiment of the present invention is a control device for controlling a sputtering apparatus including one or more targets arranged opposite a substrate and made of a film forming material, and one or more magnet units arranged on a rear surface of the targets,
and an optimal solution calculation unit that calculates an optimal solution of the setting conditions for at least one of the magnet units based on input information including at least setting conditions including the position of each of the magnet units, the movement pattern of each of the magnet units, and at least one of the inflow current or inflow current fluctuation pattern of the electromagnets that constitute each of the magnet units, and measured values of the film quality of the film formation material on the substrate formed by the sputtering apparatus.

According to the present invention, it is possible to improve the film deposition uniformity and the equipment operating rate.

1 is a schematic cross-sectional view of a sputtering apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view illustrating one configuration example of a magnet unit in the sputtering apparatus. 5A and 5B are schematic diagrams for explaining the relationship between the relative position of a magnet unit with respect to a target and the uniformity of film quality. 11A and 11B are schematic diagrams illustrating suppression of temporal change in film quality distribution by adjusting the rocking motion of a magnet unit. FIG. 4 is a front view showing an arrangement of magnet units. FIG. 2 is a schematic configuration diagram of an adjustment unit in the sputtering apparatus. 2 is a block diagram showing a configuration of a control device in the sputtering apparatus. FIG. 8 is a flowchart showing an example of a processing procedure executed in the control device shown in FIG. 7 . FIG. 4 is a schematic cross-sectional view of a sputtering apparatus according to another embodiment of the present invention. FIG. 10 is a schematic diagram of a rotary cathode in the sputtering apparatus shown in FIG. 9 . 11A and 11B are schematic diagrams illustrating suppression of temporal change in film quality distribution by adjusting the rocking motion of a magnet unit. 5A and 5B are schematic diagrams for explaining the relationship between the swing position of the magnet unit relative to the target and the film quality uniformity. 10 is a block diagram showing a configuration of a control device in the sputtering apparatus shown in FIG. 9 . 14 is a flowchart showing an example of a processing procedure executed in the control device shown in FIG. 13 . 2 is a schematic diagram of a main part for explaining a modified example of the configuration of the sputtering apparatus shown in FIG. 1.

Below, an embodiment of the present invention is described with reference to the drawings.

First Embodiment
[Basic configuration of sputtering device]
Fig. 1 is a schematic cross-sectional view of a sputtering apparatus 100 according to an embodiment of the present invention. In Fig. 1, the X-axis, the Y-axis, and the Z-axis indicate three axial directions perpendicular to each other, and the Z-axis corresponds to the up-down direction (height direction).

The sputtering apparatus 100 is a magnetron sputtering apparatus, and includes a vacuum chamber 1, a substrate holder 2, a target 3, a backing plate 4, a plurality of magnet units 5, and an adhesion prevention plate 6. The sputtering apparatus 100 may be a vertical sputtering apparatus of a single-wafer type, or may be a vertical sputtering apparatus of an in-line type. Note that, when the size of the substrate is equal to or smaller than a predetermined size, the sputtering apparatus 100 may be a horizontal sputtering apparatus.

The vacuum chamber 1 is connected to a vacuum pump 7 and is configured to be able to evacuate or maintain the interior at a predetermined reduced pressure atmosphere. The substrate holder 2 is disposed inside the vacuum chamber 1 and supports the substrate W in a vertical position. The vacuum chamber 1 and the substrate holder 2 are typically connected to ground potential. The substrate W is, for example, a rectangular glass substrate with a width of 1850 mm or more and a length of 1500 mm or more.

Although not shown, the vacuum chamber 1 is provided with an entrance and exit for the substrate holder 2. The entrance and exit may be common or separate. The entrance and exit are configured to be able to be opened and closed via a gate valve or the like not shown.

The target 3 is composed of a film-forming material for forming a film on the substrate W. Typical examples of the film-forming material include metals, alloys, metal oxides, metal nitrides, and synthetic resins. In this embodiment, a metal or alloy target having electrical conductivity is used.

The target 3 may be an ingot target or a sintered target. The number, size, arrangement, etc. of the targets 3 are not particularly limited, but in this embodiment, the target 3 is composed of a single rectangular plate material having an area larger than the substrate W, and is arranged in the vacuum chamber 1 facing the substrate W at a predetermined distance (TS distance) in the X-axis direction.

The backing plate 4 is a metal plate that supports the back surface of the target 3 and is fixed to the vacuum chamber 1 via an insulating member 11. The backing plate 4 is typically joined to the target 3 via a brazing material such as indium. The backing plate 4 is connected to a power supply 8 having an RF power supply or a DC power supply installed outside the vacuum chamber 1.

The multiple magnet units 5 are arranged facing the back surface (non-sputtering surface) of the target 3 via the backing plate 4. The multiple magnet units 5 form a magnetic circuit that forms a magnetic field on the surface (sputtering surface) of the target 3.

2 is an enlarged view of the magnet unit 5. The magnet unit 5 has a first magnet 51, a second magnet 52, and a yoke 53 that supports the first magnet 51 and the second magnet 52. The end of the first magnet 51 on the target 3 side and the end of the second magnet 52 on the target 3 side are magnetized so that they have opposite magnetic poles. The shapes and arrangements of the first magnet 51 and the second magnet 52 are not particularly limited, but in this embodiment, the first magnet 51 is formed in a linear shape extending in the Z-axis direction, and the second magnet 52 is formed in a rectangular ring shape so as to surround the periphery of the first magnet 51. The shapes and numbers of the first and second magnets 51 and 52 that constitute the magnetic circuit are not limited to this example and can be set arbitrarily.

The adhesion prevention plate 6 is disposed between the substrate holder 2 and the target 3 to prevent the sputtering material (film-forming material) flying from the target 3 from adhering to the inner surface of the sidewall of the vacuum chamber 1 and the outer peripheral region of the substrate W (the peripheral portion of the substrate holder 2), and to define a plasma space P in which plasma is generated between the target 3 and the substrate holder 2. The vacuum chamber 1 is fitted with a gas introduction line 9 that introduces a sputtering gas such as Ar (argon) from a gas source 9s into the plasma space P.

When a film is formed on a substrate W by the sputtering apparatus 100, a sputtering gas is introduced from the gas inlet line 9 into the plasma space P, and an RF or DC power supply is input from the power supply source 4 to the target 3 via the backing plate 4, generating a magnetron discharge in the plasma space P. A plurality of magnet units 5 arranged on the rear side of the target 3 form a magnetic field on the surface of the target 3 that is perpendicular to the electric field, confining electrons in the plasma near the surface of the target 3. This increases the electron density even with a small sputtering power, and increases the amount of ions entering the target.

In a magnetron sputtering device, the higher the horizontal magnetic flux density (magnetic flux density perpendicular to the electric field) on the target surface (sputtering surface), the higher the erosion rate of the target surface by the plasma, and therefore more film-forming material is sputtered from the target surface, enabling high-speed film formation on the substrate surface. Typically, the higher the magnetic flux density of the horizontal magnetic field B of each magnet unit 5 in an area on the surface of the target 3, the higher the film deposition rate on the surface area of the substrate W facing that area tends to be relatively higher than in other surface areas. For this reason, in order to uniformly distribute the film quality on the substrate W, it is necessary to strictly control the magnetic flux density distribution of the horizontal magnetic field B on the surface of the target 3.

[Explanation of how film quality distribution can be adjusted by adjusting the position of the magnet unit in the X-axis direction]
For example, when the position of the magnet unit in the X-axis direction is fixed, the distance from the target surface to the magnet unit gradually decreases as the erosion of the target surface progresses, resulting in a higher horizontal magnetic flux density on the target surface. Also, as shown in Figures 3A and 3B, the erosion 3e progresses faster in areas of the target surface with higher horizontal magnetic flux density, so the difference in horizontal magnetic flux density on the surface of the target 3 becomes more noticeable as time passes. Therefore, the uniformity of the film deposited on the substrates W tends to deteriorate as the number of substrates processed increases.

Therefore, as shown in Figure 3 (C), in order to lower the horizontal magnetic flux density in the surface region of the target 3 where the erosion 3e progresses at a high rate, the magnet unit 5 constituting the magnetic circuit is moved in a direction away from the surface of the target 3, thereby suppressing the accelerated increase in the horizontal magnetic flux density in that region and achieving uniformity in the amount of film deposition.

In addition, when some or all of the first magnet 51 and second magnet 52 constituting the magnetic circuit are electromagnets, the horizontal magnetic flux density in the surface region of the target 3 can be adjusted not only by adjusting the position of the magnet unit 5 in the X-axis direction, but also by adjusting the magnitude and direction of the flowing current into the coils constituting the first magnet 51 and second magnet 52, thereby achieving homogenization of the amount of film deposition.

[Explanation of how film quality distribution can be adjusted by adjusting the oscillation of the magnet unit in the Y-axis direction]
Since the utilization efficiency of the target 3 is low when only a limited area of the target 3 is eroded, a technique is known in which a wider area is eroded by swinging the magnet unit 5 in the Y-axis direction (see Patent Document 1).

In general, erosion caused by a single magnet unit 5 oscillating in the Y-axis direction at a constant speed is fastest at the center of the oscillation, so the target surface shape becomes bowl-shaped. Figures 4(A) and (B) respectively show the change in the surface shape of the target 3 a predetermined time after the start of sputtering of the target 3, and the change over time in the position of the magnet unit 5 in the Y-axis direction relative to the target 3. Since the speed at which the surface of the target 3 and the magnet unit 5 approach each other is fast in the center of the bowl of the surface of the target 3, the difference in the progression speed between the erosion center 3e-center and both erosion sides 3e-side becomes more pronounced over time, as shown in Figure 4(B).

Therefore, if oscillation continues at a constant speed, the balance of the progression speeds of the erosion center 3e-center and both sides 3e-side will change, and as the erosion progresses, the difference in these speeds will become even more pronounced, causing changes in the film quality distribution and reducing the target utilization efficiency.

As shown in Fig. 4(C), in order to keep the speed of the erosion center 3e-center and both sides 3e-side erosion balanced, the magnet unit 5 can be rotated longer in the Y-axis direction and/or the speed of movement at both ends of the rotation can be slowed down so that the magnet unit 5 stays longer around the erosion side 3e-side area, thereby suppressing changes in the film quality distribution and maintaining a homogeneous film quality. Specifically, the magnet unit 5 can be rotated longer around the ends of the rotation (see Countermeasure Example 1 in Fig. 4(C)), the magnet unit 5 can be stopped for a longer period at the ends of the rotation (see Countermeasure Example 2 in Fig. 4(C)), the width of the rotation of the magnet unit 5 can be increased (see Countermeasure Example 3 in Fig. 4(C)), or any combination of Countermeasure Examples 1 to 3 can be used.

In addition, when some or all of the first magnet 51 and second magnet 52 constituting the magnetic circuit are electromagnets, adjusting the current flowing through the coils constituting the first magnet 51 and second magnet 52, which changes depending on the position of the magnet unit 5 during oscillation (hereinafter, referred to as the inflow current fluctuation pattern), has the same effect as adjusting the movement pattern of the magnet unit 5 in the Y-axis direction. Specifically, by increasing the current when the magnet unit 5 is near the end of the oscillation and decreasing the current when it is near the center of the oscillation, it is possible to suppress changes in the film quality distribution.

As described above, the setting conditions of the magnet unit 5 include changing the position of the magnet unit 5 in the X-axis direction, the movement pattern in the Y-axis direction, and the inflow current or inflow current fluctuation pattern over time, which is important in order to maintain film quality uniformity.

However, it is difficult to accurately predict the progression of erosion because the rate at which erosion progresses is affected by a variety of factors, including pressure, applied voltage, amount of sputtering gas inflow, target constituent material, and target quality. In addition, erosion progresses faster in areas with higher horizontal magnetic flux density, so the difference between the actual and predicted erosion progression accelerates over time.

Therefore, it is difficult to preset the optimal magnet unit's X-axis position, Y-axis movement pattern, and inflow current or inflow current fluctuation pattern as a function of time, and in reality it is necessary to periodically carry out a series of tasks to check the deposition state of the deposited substrate, stop the equipment, and adjust the magnet unit's X-axis position, Y-axis movement pattern, and inflow current or inflow current fluctuation pattern. The implementation of these tasks is one of the causes of reduced equipment operating rates, and this problem is more likely to occur as the substrate becomes larger.

Therefore, in this embodiment, in order to improve the deposition uniformity and the equipment operating rate, the sputtering apparatus 100 is configured as follows.

[Details of the sputtering device]
(Magnet unit)
5 is a front view of the arrangement of a plurality of magnet units 5 as viewed from the X-axis direction. In the example shown in the figure, each magnet unit 5 is composed of a first block 5a elongated in the height direction (Z-axis direction) and a pair of second blocks 5b arranged at both ends of the first block 5a, and the first and second magnets 51 and 52 shown in FIG. 2 are arranged in each of these blocks 5a and 5b. Then, a plurality of magnet units 5 (9 pairs in the illustrated example) each consisting of a pair of the first block 5a and the pair of second blocks 5b are arranged in the horizontal direction (Y-axis direction). Therefore, the magnetic circuit arranged on the back surface of the target 3 is divided into a total of 27 places.

In each magnet unit 5, the length of the first block 5a along the Z-axis direction is longer than that of the second block 5b, but this is not limited to this, and each block 5a, 5b may be formed with the same length. The number of blocks constituting each magnet unit 5 is not limited to three, but may be two, four or more. The number of magnet units 5 arranged is not limited to nine, but may be less or more than this. In other words, the number of divisions of the magnetic circuit composed of multiple magnet units 5 and the size of the divided magnetic circuits are not limited to the illustrated example, and can be set arbitrarily depending on the size of the target 3 or substrate W, the position on the substrate W where the deposition amount should be adjusted, the in-plane distribution of the deposition amount on the target substrate W, etc.

The sputtering apparatus 100 further includes an adjustment unit 10 capable of individually adjusting the relative distance of the first and second blocks 5a, 5b of each magnet unit 5 to the target 3, and a control device 20 that controls the adjustment unit 10.

(Adjustment unit)
6 is a plan view showing a schematic configuration of the adjustment unit 10 as viewed from the Z-axis direction. The adjustment unit 10 is disposed outside the vacuum chamber 1, and has a plurality of driving units 11 disposed corresponding to the first and second blocks 5a, 5b of each magnet unit 5. Each driving unit 11 is, for example, configured with a driving cylinder or a driving motor having driving shafts 11a and 11b whose one ends are connected to the first and second blocks 5a, 5b. The driving shaft 11a moves the first and second blocks 5a, 5b in a direction approaching or moving away from the target 3 by expanding and contracting in the X-axis direction. The driving shaft 11b moves the first and second blocks 5a, 5b in a direction horizontal to the target 3 by expanding and contracting in the Y-axis direction.

In addition, when some or all of the magnets constituting each magnet unit 5 are electromagnets, the adjustment unit 10 may be provided with a device for adjusting the current flowing through each electromagnet. The device for adjusting the current flowing through the electromagnet may adjust the current flowing through the electromagnet so that a constant current always flows, or may adjust the inflow current so that it changes in conjunction with the oscillation of the magnet unit 5 in the Y-axis direction.

The adjustment unit 10 may be configured to manually adjust the X-axis position, Y-axis movement pattern, and inflow current or inflow current fluctuation pattern of each magnet unit 5 by an operator, or may automatically adjust the X-axis position, Y-axis movement pattern, and inflow current or inflow current fluctuation pattern based on a control command from the control device 20.

(Control device)
The control device 20 is configured with a computer including a CPU (Central Processing Unit), an internal memory, an input/output interface, etc. In this embodiment, the control device 20 controls the operation of the entire sputtering apparatus 100 including the adjustment unit 10, the vacuum pump 7, the power supply source 8, and the gas introduction line 9.

Figure 7 is a block diagram showing the configuration of the part of the control device 20 that is related to the present invention. The control device 20 has an input unit 21, an optimal solution calculation unit 22, and an output unit 23.

The input unit 21 has a function of acquiring various film formation conditions when each substrate is formed and measurement values of the film quality formed on each substrate from the sputtering device 100. In addition, when the film quality formed on each substrate is measured by a measurement device other than the sputtering device 100, the control device 20 is connected to the measurement device, and the input unit 21 also has a function of acquiring the measurement values of the film quality formed on each substrate.

The various deposition conditions when the substrate is deposited include, as setting conditions for each magnet unit 5, one or more of the position of each magnet unit 5 in the X-axis direction, the movement pattern in the Y-axis direction, and the inflow current or the inflow current fluctuation pattern, and may also include the type of deposition material constituting the target 3, the consumption of the target 3 (surface shape of the target 3), the applied voltage to the target 3 (input voltage from the power supply source 8), the inflow amount of sputtering gas, and the pressure inside the chamber.

The measured values of the film quality deposited on each of the substrates are measured values of the film quality at measurement points at multiple specific positions on the substrate W. The arrangement of the measurement points is not particularly limited, but from the viewpoint of managing the distribution of the film quality deposited on each of the substrates, it is desirable that they are arranged widely on the substrate W and that they include positions where the film quality is maximum or minimum within the surface of the substrate W. These measurement points may be determined in advance before the start of film deposition, or may be determined arbitrarily after film deposition.

The optimal solution calculation unit 22 calculates an optimal solution (or optimal value) of the setting conditions for at least one of the magnet units 5 based on input information including at least the setting conditions and measured values of the film quality of the film-forming material on the substrate W formed by the sputtering apparatus 100.

The optimal solution calculation unit 22 has a function of calculating the optimal X-axis position, Y-axis movement pattern, and inflow current or inflow current fluctuation pattern of each magnet unit 5 that can obtain homogeneity of film quality based on various input information acquired by the input unit 21. Details of the optimal solution calculation unit 22 are described below.

The optimal solution calculation unit 22 in this embodiment is composed of a prediction unit 221, a correction unit 222, and an optimization unit 223.

The prediction unit 221 calculates a predicted value of the homogeneity of the film quality for the set conditions of each of the magnet units. The prediction unit 221 is a function that takes various film formation conditions as arguments and returns a predicted value of the film quality assuming that film formation is performed under those conditions. The method of calculating the predicted value of the film quality is not particularly limited, and in this embodiment, a machine learning device that has previously learned the relationship between various film formation conditions and film quality is used.

The algorithm of the machine learning machine is not particularly limited, and for example, multiple linear regression, neural networks, decision trees, support vector machines, or an ensemble learning model that combines two or more of these can be applied.

The arguments of the prediction unit 221 must include the X-axis position of each magnet unit 5, the Y-axis movement pattern, and the inflow current or inflow current fluctuation pattern. Furthermore, by including additional deposition conditions that affect the film quality distribution, such as the type of deposition material, the surface shape of the target, the voltage applied to the target, the discharge time, the type of sputtering gas, and the deposition pressure, in the arguments, it is possible to build a more accurate machine learning machine.

The predicted film quality value, which is the return value of the prediction unit 221, is the predicted film quality value at all measurement points on the actual substrate W. The reason for using the same measurement points as on the actual substrate W is that it is necessary to compare with the actual film quality measurement value acquired by the input unit 21.

By inputting the actual film formation conditions into the arguments of the prediction unit 221, a predicted value of the film quality in the actual film formation can be calculated. However, since the film quality is affected by various factors such as the position of each magnet unit 5 in the X-axis direction, the movement pattern in the Y-axis direction and the inflow current or inflow current fluctuation pattern, pressure, applied voltage, sputtering gas inflow amount, target constituent material, and target quality difference, and it is difficult to measure all of these factors, the predicted value of the film quality in the actual film formation rarely matches the measured value.

Therefore, it is necessary to correct the predicted value of the film quality in the actual film formation so that the predicted value matches the measured value. The correction unit 222 compares the predicted value of the film quality in the actual film formation with the measured value, calculates correction parameters, and corrects the predicted value of the film quality. If the accuracy of the prediction by the prediction unit 221 is sufficiently high, the effect of the correction will be small, so the correction method by the correction unit 222 may be simple addition or multiplication.

By correcting the predicted value of the film quality calculated by the prediction unit 221 using the correction unit 222, it becomes possible to predict the film quality for any film formation conditions. Hereinafter, the predicted value of the film quality corrected by the correction unit 222 will be described as the corrected predicted value of the film quality.

The optimization unit 223 searches for film formation conditions that will yield optimal corrected predicted values of film quality. In this embodiment, a mathematical optimization algorithm is used to search for the X-axis position, Y-axis movement pattern, and inflow current or inflow current fluctuation pattern of each magnet unit 5 that minimizes the statistics representing the homogeneity of the corrected predicted values of film quality. The statistics representing the homogeneity of the corrected predicted values of film quality use (Max-Min)/(Max+Min) or a coefficient of variation, which are homogeneity indices commonly used in the sputtering field. The mathematical optimization algorithm may be, for example, gradient descent, grid search, brute force, or Bayesian optimization.

According to this embodiment, in order to obtain optimal homogeneity of the film quality for the actual most recent film formation, information (optimum film formation conditions) can be obtained regarding how the X-axis position, Y-axis movement pattern, and inflow current or inflow current fluctuation pattern of each magnet unit 5 should have been set. Since erosion of the target 3 progresses over a time span of several days to several weeks, if the time from when the most recent film formation is performed to when the calculation of the optimal film formation conditions is completed is sufficiently short compared to the rate at which the erosion progresses, the optimal film formation conditions are considered to be valid film formation conditions even at the time when the calculation is completed.

The output unit 23 transmits the X-axis position, Y-axis movement pattern, and inflow current or inflow current fluctuation pattern of each magnet unit 5 calculated by the optimal solution calculation unit 22 to the adjustment unit 10, causing it to perform adjustment.

By automatically using the control device 20 for each actual film formation data, it is possible to adjust the X-axis position of each magnet unit 5, the Y-axis movement pattern, and the inflow current or inflow current fluctuation pattern before the uniformity of the film quality is significantly compromised, thereby maintaining the uniformity of the film quality.

Furthermore, by referring to actual film formation results when calculating the optimal solution, it is not only possible to respond to changes over time, but also to automatically absorb individual differences that exist among multiple devices, making it possible to make optimal adjustments for each device.

Figure 8 is a flowchart showing an example of a processing procedure executed in the control device 20 of this embodiment.

The input unit 21 acquires input information (step 101). The input information includes various film formation conditions when each substrate is formed and measurement values of the film quality formed on each substrate.

Next, the optimal solution calculation unit 22 (prediction unit 221) calculates a predicted value of the homogeneity of the film quality of the film forming material on the substrate W based on the input information acquired by the input unit 21, and determines whether the homogeneity of the film quality is within the target range based on the calculated predicted value (steps 102, 103).

Next, if the homogeneity of the film quality is not within the target range, the optimal solution calculation unit 22 (correction unit 222) compares the measured value of the film quality obtained by the input unit 21 with the predicted value calculated by the prediction unit 221, and determines a correction coefficient for correcting the predicted value (steps 104, 105).

Next, the optimal solution calculation unit 22 (optimization unit 223) searches for an optimal solution that can satisfy the target film quality homogeneity for the setting conditions such as the position of each magnet unit 5 that optimizes the corrected film quality prediction value (step 106).

Next, the output unit 23 calculates the current adjustment amount for each magnet unit 5 to the above-mentioned optimal solution based on the optimal solution calculated by the optimal solution calculation unit 22 and outputs it to a display unit (not shown) (step 107). Alternatively, the output unit 23 generates a control command based on the calculated optimal solution for each magnet unit 5, outputs the control command to the adjustment unit 10, and sets the setting condition of each magnet unit 5 to the above-mentioned optimal solution.

As described above, according to this embodiment, it is possible to determine whether the homogeneity of the film quality of the material formed on the substrate W is within a predetermined target range based on input information such as the setting conditions of each magnet unit 5 and actual measurement values. Furthermore, based on this information, the optimal solution calculation unit 22 can calculate the optimal solution of the setting conditions of each magnet unit 5 that will achieve homogeneity of film quality.

In the conventional sputtering apparatus (comparison example), the film quality uniformity on the substrate W on which the film was formed was evaluated periodically, and if the evaluation result was within the target range (below the control value), the processing was continued as is, and if the evaluation result was outside the target range (above the control value), the operation of the apparatus was stopped and the position of each magnet unit 5 was adjusted manually. For this reason, the apparatus had to be stopped every time the magnet unit 5 was adjusted, which caused a problem of a decrease in the apparatus operating rate. In addition, since the adjustment of the position of each magnet unit 5 required skill, there was a limit to the improvement of the apparatus operating rate. Furthermore, since the control value could not be set strictly to prevent a decrease in the apparatus operating rate, it was difficult to obtain stable uniformity of the film quality within or between lots.

In contrast, according to this embodiment, the position of each magnet unit 5 can be automatically adjusted without stopping the operation of the sputtering apparatus 100, thereby significantly improving the operation rate of the apparatus. In addition, since the homogeneity is evaluated based on the calculated film quality as the sputtering process progresses, it is possible to adjust the position of the magnet unit 5 before the homogeneity of the film quality is significantly impaired. Furthermore, since the control values can be set more strictly than in the comparative example, the variation in homogeneity within or between lots is suppressed, thereby enabling stable film formation to be continued with homogeneous film quality.

Second Embodiment
Next, a second embodiment of the present invention will be described. Fig. 9 is a schematic cross-sectional view of a sputtering apparatus 200 according to another embodiment of the present invention. In Fig. 9, the X-axis, the Y-axis, and the Z-axis indicate three axial directions perpendicular to each other, and the Z-axis corresponds to the up-down direction (height direction).

The sputtering apparatus 200 includes a vacuum chamber 201, a substrate holder 202, multiple rotary cathodes RC, and an adhesion prevention plate 206. The multiple rotary cathodes RC are arranged at equal intervals along the Y-axis direction. Each rotary cathode RC has a cylindrical target 203, a cylindrical backing tube 204 that supports the inner surface of the target 203, and a magnet unit 205 arranged inside the target 203.

The vacuum chamber 201 is connected to a vacuum pump 207 and is configured to be able to evacuate or maintain the interior at a predetermined reduced pressure atmosphere. The substrate holder 202 is disposed inside the vacuum chamber 201 and supports the substrate W in a vertical position. The vacuum chamber 201 and the substrate holder 202 are typically connected to ground potential. The substrate W is, for example, a rectangular glass substrate with a width of 1850 mm or more and a length of 1500 mm or more.

Each target 203 is configured to be rotatable around an axis parallel to the Z-axis direction (circumferential direction of the target 203). The target 203 is composed of a film-forming material for forming a film on the substrate W. Typical examples of the film-forming material include metals, alloys, metal oxides, metal nitrides, and synthetic resins. In this embodiment, a metal or alloy target having electrical conductivity is used.

Each backing tube 204 is a metal plate that supports the back surface of the target 203 and is connected to a power supply having an RF power supply or a DC power supply (not shown) installed outside the vacuum chamber 201.

A plurality of magnet units 205 are arranged inside each target 203 along the axial direction of each target 203. They form a magnetic circuit that forms a magnetic field on the surface (sputtering surface) of the target 203 facing the substrate W. As described with reference to FIG. 2, each magnet unit 205 has a first magnet 51, a second magnet 52, and a yoke 53 that supports the first magnet 51 and the second magnet 52.

The adhesion prevention plate 206 is disposed around the rotary cathode RC to prevent the sputtering material (film forming material) flying from the target 3 from adhering to the inner sidewall surface of the vacuum chamber 201 and the outer peripheral region of the substrate W (the peripheral portion of the substrate holder 2), and to define a plasma space P in which plasma is generated between the target 203 and the substrate holder 202. The vacuum chamber 201 is fitted with a gas introduction line 209 that introduces a sputtering gas such as Ar (argon) from a gas source 209s into the plasma space P.

When forming a film on a substrate W using the sputtering apparatus 200, sputtering gas is introduced into the plasma space P from the gas inlet line 209, each target 3 is rotated around its axis at a constant speed, and an RF or DC power supply is applied to the target 203 from the power supply source via the backing tube 204, thereby generating a magnetron discharge in the plasma space P.

In the sputtering device 200, the target 203 rotates around its axis, so that erosion progresses evenly in the circumferential direction of the target 203. This increases the utilization efficiency of the target 203.

In this embodiment, as shown in FIG. 10, each rotary cathode RC has a drive unit 211 capable of moving each magnet unit 205 in the radial direction of the target 203 and oscillating each magnet unit 205 in the circumferential direction of the target 203. Since each magnet unit 205 is configured to be movable in the radial direction of the target 203, the sputtering rate of the target 203 can be controlled. Furthermore, since each magnet unit 205 is configured to be oscillating in the circumferential direction of the target 203, the shape of the film to be formed can be manipulated to some extent. The drive unit 211 is configured to be capable of adjusting the oscillation width and oscillation speed of the magnet unit 205.

[Explanation of the possibility of adjusting the film quality distribution by adjusting the radial direction of the magnet unit]
In general, it is desirable for the erosion rates of multiple aligned rotating cylindrical cathodes (rotary cathodes) to be equal, but in some cases equal erosion rates cannot be obtained due to factors that affect the behavior of electrons (distance from the anode or other rotary cathodes), slight differences in the quality of the targets, etc. Also, in some cases, different erosion rates are intentionally set to obtain the desired film quality distribution.
As the targets erode, their diameter decreases and the distance from the magnet unit decreases, accelerating the erosion rate. However, if there is a difference in the erosion rate among multiple rotary cathodes, the difference becomes significant over time, causing changes in the film quality distribution.
Therefore, in order to maintain a desired balance of erosion rates, it is necessary to adjust the radial position of the magnet unit as erosion progresses.
Furthermore, in the case where some or all of the magnets used in the magnet unit are electromagnets, the same effect can be obtained by adjusting the inflow current.
In other words, the erosion rate of the target surface can be adjusted by changing the magnitude and direction of the current passed through the electromagnet coil.

[Explanation of the possibility of adjusting the film quality distribution by adjusting the circumferential oscillation of the magnet unit]
The film thickness distribution on the substrate formed by the cylindrical target No. 1 is affected by the circumferential position of the magnet unit. In general, when the magnet unit is disposed at a position facing the substrate, the distribution is symmetrical and bell-shaped, whereas when the magnet unit is disposed at a position rotated from the position facing the substrate, the distribution is asymmetrical and bell-shaped with the peak position shifted in the rotation direction. This is because the position where the target particles are emitted changes depending on the position of the magnet unit (see FIGS. 11A and 11B).
A technique is known that utilizes this property to manipulate the film thickness distribution obtained by oscillating the magnet unit in the circumferential direction during film formation (FIG. 12(A)).
As the erosion of the target progresses, the diameter of the target shrinks, and the film thickness distribution changes accordingly. In general, the film thickness distribution changes to a gentler bell shape as the particle emission position moves away from the substrate (Fig. 12(B)). To counter this change, it is effective to adjust the circumferential oscillation pattern of the magnet unit (Fig. 12(C)).
As erosion progresses, it is possible to maintain the film thickness distribution by reducing the oscillation width of the magnet unit and adjusting the oscillation speed so that the magnet unit remains in a position facing the substrate for a long period of time.
Furthermore, in the case where some or all of the magnets used in the magnet unit are electromagnets, the same effect can be obtained by adjusting the pattern of the inflow current according to the swing position.

The above-mentioned radial position, circumferential oscillation pattern, and inflow or inflow current variation pattern of the magnet unit are concepts corresponding to the X-axis position, Y-axis movement pattern, and inflow or inflow current variation pattern of each magnet unit 5 shown in the first embodiment. Therefore, if the above description of the first embodiment is interpreted in a reverse manner, it can be seen that the first embodiment can also be applied to a rotary cathode. Similarly, this embodiment can also be applied to a planar cathode (first embodiment).

[Control unit]
The sputtering apparatus 200 of this embodiment further includes a control device 220 that controls the positions of the magnet units 5. Fig. 13 is a block diagram showing the configuration of the portion of the control device 220 that is related to the present invention, among its functions. The control device 220 includes an input unit 21, an optimal solution calculation unit 22, and an output unit 23, similar to the first embodiment.

In this embodiment, the configuration of the optimal solution calculation unit 22 differs from that of the first embodiment described above. The optimal solution calculation unit 22 in this embodiment is composed of a prediction unit 221, a state estimation unit 224, and an optimization unit 223. In addition, the function of the prediction unit 221 also differs from that of the first embodiment.

The prediction unit 221 in this embodiment is a function that takes the deposition conditions and the hidden parameter, the equipment state, as arguments, and returns the predicted value of the film quality when it is assumed that the film is deposited under those deposition conditions and equipment state. The method of calculating the predicted value of the film quality is based on a mathematical model that reproduces the physical phenomenon related to sputtering by a program.

The hidden parameters, or equipment states, are physical quantities that are known to affect film formation, such as the progression of target erosion, but whose values are unknown due to the absence of measuring equipment, or completely unknown factors that affect film formation, modeled as white noise and expressed as vectors.

It is possible to predict the film quality distribution for any film formation conditions by inputting the film formation conditions and an appropriate apparatus state to the prediction unit 221. Since the apparatus state, which is the hidden parameter, is usually unknown, it is essential to estimate the apparatus state in order to use the prediction unit 221.
Therefore, it is the state estimation unit 224 that plays a role in estimating the apparatus state using the actual film formation results.

The state estimation unit 224 calculates an estimate of the device state using the maximum likelihood estimation method or the MAP estimation method based on the actual deposition conditions and deposition results. The calculation may use various mathematical optimization algorithms such as the gradient descent method or the Markov chain Monte Carlo method.

Whereas the first embodiment mechanically compensates for the error between the predicted and measured film quality values, the second embodiment can theoretically explain why the error occurred by estimating the device state. Therefore, the prediction is highly reliable, and even if actual film formation results are not obtained for a long period of time, the advantage is that the homogeneity of the film quality can be maintained by predicting the transition of the device state during that time.

Both the correction unit 221 of the first embodiment and the state estimation unit 224 of the second embodiment are introduced for the purpose of improving prediction accuracy. Therefore, the state estimation unit 224 can be regarded as one form of the correction unit 221.

Figure 14 is a flowchart showing an example of a processing procedure executed in the control device 220 of this embodiment.

The input unit 21 acquires input information including the film formation conditions and measurement values of the sputtering device 200 (step 201). Next, the optimal solution calculation unit 22 (prediction unit 221) calculates a predicted value of the homogeneity of the film quality of the film formation material on the substrate W based on the input information acquired by the input unit 21, and determines whether the homogeneity of the film quality is within a target range based on the calculated predicted value (steps 202, 203).

Next, if the homogeneity of the film quality is not within the target range, the optimal solution calculation unit 22 (state estimation unit 224) calculates (estimates) the film formation conditions that maximize the likelihood of the current equipment state based on the input information acquired by the input unit 21 (step 204).

Next, the optimal solution calculation unit 22 (optimization unit 223) searches for an optimal solution that can satisfy the target homogeneity of film quality for the setting conditions such as the position of each magnet unit 205 that maximizes the likelihood of the device state (step 205).

Next, the output unit 23 calculates the current adjustment amount of each magnet unit 205 to the above-mentioned optimal solution based on the optimal solution calculated by the optimal solution calculation unit 22, and outputs it to a display unit (not shown) (step 206). Alternatively, the output unit 23 generates a control command based on the calculated optimal solution of each magnet unit 205, and sets the setting conditions of each magnet unit 205 to the above-mentioned optimal solution via an adjustment unit (not shown).

The above describes an embodiment of the present invention, but it goes without saying that the present invention is not limited to the above-described embodiment and various modifications can be made.

For example, in the above embodiment, the adjustment unit 10 automatically adjusts the position of the magnet unit 5, 205 based on a control command from the control device 20, 220, but this is not limited to the above, and the position of the magnet unit 5, 205 may be adjusted by an operator. In this case, the position adjustment work can be performed for the magnet unit 5, 205 specified in the control unit 20, 220 based on the adjustment amount calculated by the control unit 20, 220, so that the position adjustment of the magnet unit 5, 205 can be performed quickly regardless of the skill level of the operator.

In addition, in the above embodiment, the control device 20, 220 is configured as part of the sputtering device 100, but this is not limited, and the control device 20, 220 may be configured independently of the sputtering device 100, 200. For example, the control device 20, 220 may be configured as part of a management device connected to multiple sputtering devices via a network. In this case, evaluation of the homogeneity of film quality in multiple sputtering devices, calculation of optimal solutions such as the position of the magnet unit, generation of control commands to adjust the position of the magnet unit, etc. can be performed by a single control device 20, 220.

Furthermore, in the above first embodiment, an example in which multiple magnet units 5 are arranged for a single target 3 has been described, but the present invention can also be applied to a multi-cathode type magnetron sputtering device in which multiple targets 3 are arranged on the same plane. In this case, as shown in schematic form in Figures 15(A) and (B), each magnet unit 5 arranged on the back surface of each target 3 can be moved in the X-axis direction and swung in the Y-axis direction in accordance with the progress of erosion of each target 3, so that the desired homogeneity of film quality can be obtained, thereby obtaining the same effect as in the first embodiment.

Furthermore, in each of the above embodiments, examples of application to a magnetron sputtering device in which multiple magnet units are arranged for each of multiple targets have been described, but the present invention is also applicable to a magnetron sputtering device in which a single magnet unit is arranged for a single target.

1, 201: Vacuum chamber 3, 203: Target 5, 205: Magnet unit 10: Adjustment unit 20, 220: Control device 21: Input section 22: Optimum solution calculation section 23: Output section 100, 200: Sputtering device 221: Prediction section 222: Correction section 223: Optimization section 224: State estimation section W: Substrate

Claims (8)

One or more targets arranged opposite the substrate and made of a deposition material;
one or more magnet units disposed on a rear surface of the target;
a control device having an optimal solution calculation unit that calculates an optimal solution of the setting conditions for at least one of the magnet units based on input information including at least one of setting conditions including a position of each of the magnet units, a movement pattern of each of the magnet units, and an inflow current or an inflow current fluctuation pattern of an electromagnet constituting each of the magnet units, and a measurement value of a film quality of a film formed on the substrate by the sputtering device;
and an adjustment unit capable of individually adjusting the setting conditions of the magnet units based on the optimal solution,
The optimum solution calculation unit calculates a predicted value of the homogeneity of the film quality for the setting conditions of each of the arbitrary magnet units, derives the setting conditions of each of the magnet units that can satisfy a predetermined film quality homogeneity based on the predicted value, and corrects the predicted value based on the input information.
Sputtering equipment. 2. The sputtering apparatus according to claim 1 ,
The optimal solution calculation unit corrects the predicted value by estimating a state of the sputtering apparatus based on the input information. The sputtering apparatus according to claim 1 or 2 ,
The measurement value of the film quality of the film forming material on the substrate includes measurement data on the film quality of the film forming material at a plurality of measurement points set in advance on the substrate. 4. The sputtering apparatus according to claim 3 ,
The film quality includes at least one of a film thickness, a sheet resistance, a light transmittance, a film stress, a refractive index, an etching characteristic, and a film density. The sputtering apparatus according to any one of claims 1 to 4 ,
The optimal solution calculation unit calculates the optimal solution using a machine learning device that has previously learned the relationship between film formation conditions and film quality. The sputtering apparatus according to any one of claims 1 to 5 ,
The input information further includes at least one of a type of the film-forming material, a surface shape of the target, a voltage applied to the target, a discharge time, a type of sputtering gas, and a pressure during film formation. A method for controlling a sputtering apparatus including one or more targets arranged opposite a substrate and made of a film forming material, and one or more magnet units arranged on a rear surface of the target, comprising:
Calculating an optimal solution of the setting conditions for at least one of the magnet units based on input information including at least setting conditions including a position of each of the magnet units, a movement pattern of each of the magnet units, and at least one of an inflow current or an inflow current fluctuation pattern of an electromagnet constituting each of the magnet units, and a measurement value of a film quality of a film formed on the substrate by the sputtering apparatus;
and individually adjusting the setting conditions of the magnet units based on the optimal solution .
In the process of calculating the optimal solution for the setting conditions,
Calculating a predicted value of the uniformity of the film quality for the set conditions of each of the arbitrary magnet units;
deriving the setting conditions for each of the magnet units that can satisfy a predetermined film quality uniformity set in advance based on the predicted values;
The predicted value is corrected based on the input information.
A method for controlling a sputtering apparatus . A control device for controlling a sputtering device including one or more targets arranged opposite a substrate and made of a film forming material, and one or more magnet units arranged on a rear surface of the targets,
an optimal solution calculation unit that calculates an optimal solution of the setting conditions for at least one of the magnet units based on input information including at least one of setting conditions including a position of each of the magnet units, a movement pattern of each of the magnet units, and an inflow current or an inflow current fluctuation pattern of an electromagnet constituting each of the magnet units , and a measurement value of a film quality of a film formed on the substrate by the sputtering apparatus;
The optimum solution calculation unit calculates a predicted value of the homogeneity of the film quality for the setting conditions of each of the arbitrary magnet units, derives the setting conditions of each of the magnet units that can satisfy a predetermined film quality homogeneity based on the predicted value, and corrects the predicted value based on the input information.
Control device for sputtering device.

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