JP4901626B2 - Automatic matching unit and automatic matching unit life judgment method - Google Patents

Description

  The present invention relates to an automatic matching machine, and more particularly to an automatic matching machine using a vacuum capacitor used in a plasma processing apparatus or the like.

  In a plasma processing apparatus using a high-frequency power source such as a plasma etching apparatus, the impedance on the vacuum processing chamber side is matched with the output impedance of the high-frequency power source in order to maximize the high-frequency power supplied from the high-frequency power source to the vacuum processing chamber. An automatic aligner is used.

  Automatic matching machines often use a variable vacuum capacitor as a variable reactance element for realizing impedance matching. This variable vacuum capacitor uses a bellows, and holds a pair of electrodes arranged to be displaceable with each other via the bellows so that they can be displaced with respect to each other in a space held in a vacuum.

  The bellows expands and contracts when the capacitance of the variable vacuum capacitor is changed. When this expansion and contraction is repeated, the bellows may break along with the repeated operation.

  That is, since the bellows expands and contracts when the capacitance value of the variable vacuum capacitor is changed, there is a possibility that the bellows may be broken by repeatedly changing the electrode position of the variable vacuum capacitor.

  The automatic matching machine used in the plasma processing apparatus must change the electrode position of the variable vacuum capacitor frequently in order to achieve impedance matching with respect to the impedance on the vacuum processing chamber side that changes during processing. Since the bellows expands and contracts every time the electrode position of the variable vacuum capacitor changes, the bellows may break during long-term use. When the bellows breaks, impedance matching cannot be achieved and the plasma processing apparatus stops.

  FIG. 2 is a diagram illustrating a mechanical life curve of a bellows used for a variable vacuum capacitor. In FIG. 2, the vertical axis represents the amount of expansion and contraction of the bellows, and the horizontal axis represents the number of expansions and contractions. As shown in the figure, the number of expansions and contractions until it is broken differs according to the amount of expansion and contraction, and the larger the amount of expansion and contraction, the smaller the number of expansions and contracts. The solid line indicates the number of times that 50% of the bellows breaks, and the dotted line indicates the number of times that the 0.5% bellows breaks.

  As a preventive maintenance measure for the mechanical life of the bellows of such a variable vacuum capacitor, the variable vacuum capacitor has been replaced every several years.

Patent Documents 1 and 2 are known as techniques for extending the life of a bellows used in a variable vacuum capacitor.
JP 2005-174988 A JP 2005-303215 A

  However, the operation of exchanging the variable vacuum capacitor in the automatic matching machine is performed by removing the motor that drives the electrode and the driving mechanism of the variable vacuum capacitor such as a rotary encoder that measures the rotational position of the motor, Capacity adjustment work is necessary and is not easy. For this reason, it is desirable to reduce the replacement frequency of the variable vacuum capacitor as much as possible.

  Further, the lifetime of the bellows depends on the amount of expansion and contraction as shown in FIG. In addition, it depends on the number of expansions and contractions, not the usage time. For this reason, when the change in the electrode position of the variable vacuum capacitor is small, or when the frequency of the change in the electrode position is small, the replacement may not be necessary over a period of several years or more depending on the operation situation.

On the other hand, when the change in the electrode position of the variable vacuum capacitor is large, or when the change frequency is high, the bellows breaks in a relatively short period of time. Therefore, if the variable vacuum capacitor is not frequently replaced, the bellows may break during operation of the plasma processing apparatus, and the apparatus may stop. Such an unexpected stoppage of the apparatus during operation greatly affects the production plan and the like. Therefore, the present invention has been made in view of these problems. It is an object of the present invention to provide an automatic matching machine capable of predicting the lifetime of a capacitor and avoiding the stoppage of the apparatus during operation.

  In order to solve the above problems, the present invention employs the following means.

A capacitor having a pair of electrodes disposed in a space held in a vacuum so as to be mutually displaceable via a bellows; and a coil, wherein one of the pair of electrodes is displaced with respect to the other, and the capacitor In the automatic matching machine that adjusts the impedance of the matching circuit composed of the coil and the coil, a life addition value is set in advance for each displacement amount of the electrode position, and the maximum value continuously observed of the displacement of the electrode position For each difference between the minimum value and the minimum value, the previously set lifetime addition value is accumulated, and the elapsed amount of lifetime of the automatic matching machine is calculated based on the accumulated value.

  Since the present invention has the above-described configuration, it is possible to predict the lifetime of the variable vacuum capacitor (the elapsed amount of lifetime) and avoid stopping the apparatus during operation.

  Hereinafter, the best embodiment will be described with reference to the accompanying drawings. FIG. 1 is a diagram for explaining a process for calculating an elapsed amount of life in the automatic matching machine of the present invention.

  First, in step 1, the electrode position of the variable vacuum capacitor (position with respect to the other electrode) is detected. In step 2, it is determined whether or not the electrode position of the variable vacuum capacitor has reached a maximum point and a minimum point. If the maximum or minimum point is reached, the amount of movement from the previous minimum or maximum point is calculated in step 3, and the expansion / contraction amount of the bellows is calculated therefrom. In step 4, a life addition value to be added as a life to the bellows expansion / contraction amount obtained in step 3 is calculated. In step 5, the life addition value calculated in step 4 is added to the life. In step 6, it is determined whether the lifetime has exceeded a preset threshold value, and an alarm is output if the threshold value is exceeded.

  FIG. 3 is a diagram for explaining the processing of steps 1 to 3 in FIG. 1, that is, the processing for calculating the expansion / contraction amount of the bellows from the detection processing of the electrode position of the variable vacuum capacitor.

  As shown in FIG. 3, when the electrode position of the variable vacuum capacitor monotonously increases or monotonously decreases, the detection is continued as it is. When the change is from increase to decrease, or from decrease to increase, the point is set as a maximum point or a minimum point. When the automatic matching machine is used in a plasma processing apparatus, the electrode position of the variable vacuum capacitor may vibrate slightly due to the fluctuation of plasma serving as a load. In such a case, the increase or decrease may be determined as increase or decrease only when the movement amount exceeds a certain value (for example, 5%).

  When a local maximum point or local minimum point is detected, the amount of movement from the previous local minimum point or local maximum point is calculated, and this calculated value can be used as the amount of expansion / contraction of the bellows.

4 and 8 are diagrams for explaining the processing in step 4 of FIG. 1, and a method for calculating a life addition value to be added as a life (elapsed life) to the calculated expansion / contraction amount of the bellows. Show.
For example, as shown in FIG. 8, the expansion / contraction amount of the bellows is divided into six ranges of 20 to 18 mm, 18 to 16 mm, 16 to 14 mm, 14 to 12 mm, 12 to 10 mm, and 10 mm or less. In each expansion / contraction amount range, the lifetime addition value is calculated assuming that the lifetime has been shortened by a value divided by the number of expansion / contraction times until the bellows breaks (a times when the bellows expansion / contraction amount is 20 to 18 mm). For example, when the amount of expansion and contraction is 20 mm to 18 mm, the number of expansions and contractions until the bellows breaks when the amount of expansion and contraction is 20 mm is a, so the life addition value is 1 / a. Similarly, in the case where the amount of expansion / contraction is 18 to 16 mm, 16 to 14 mm, 14 to 12 mm, or 12 to 10 mm, 1 / the number of times of expansion / contraction until the bellows breaks at the longest expansion / contraction amount in the range of the expansion / contraction amount is the life addition value. To do. FIG. 8 shows the lifetime addition value for each expansion / contraction amount.

  In the above calculation method, when the accumulated life (added value) becomes 1, the life (replacement time) is set. 4 and 8, when the amount of expansion / contraction is 10 mm or less, the number of expansion / contraction until the bellows breaks is 10 million or more, so the life addition value is 0. Further, the 0.5% fracture curve of FIG. 4 was used for calculation of the life addition value. This is to predict the lifetime on the safe side.

  FIG. 5 is a diagram for explaining a life (amount of life elapsed) with respect to real time. An alarm is output when the elapsed life amount (cumulative value of the life addition value with respect to the expansion / contraction amount) exceeds a preset alarm threshold. For example, when the threshold is set to 0.8, an alarm is output when the amount of elapsed life exceeds 0.8. The alarm threshold may be set arbitrarily by the user.

  The time change of the elapsed life amount shown in FIG. 5 is stored in the storage device as a graph, for example. Thereby, the stored graph can be displayed according to the user's request. By observing this, the user can confirm, for example, that the amount of elapsed life of the variable vacuum capacitor has increased in a short time. In such a case, it is possible to review the operation method for extending the life of the variable vacuum capacitor, such as reviewing the preset position of the capacitor electrode. These processes can be realized by the controller 21 of the automatic matching machine described later. It can also be realized by a controller of a plasma processing apparatus.

  FIG. 6 is a diagram for explaining the details of the automatic matching machine. The matching circuit constituting the automatic matching machine includes variable vacuum capacitors 11 and 13 and a coil 12. Motors 14 and 23 for driving electrodes are attached to the variable vacuum capacitors 11 and 13, and rotary encoders 15 and 22 are connected to the motors 14 and 23. The motors 14 and 23 and the rotary encoders 15 and 22 are respectively connected to the controller 21, and the electrode positions of the variable vacuum capacitors 11 and 13 are controlled by the controller 21.

  An RF sensor 24 for measuring the input impedance of the automatic matching machine is installed at the input of the automatic matching machine. The input impedance of the automatic matching machine measured by the RF sensor 24 is input to the controller 21. The controller 21 controls the positions of the variable vacuum capacitors 11 and 13 so that the input impedance of the automatic matching machine matches the output impedance of the RF power source. FIG. 6 shows an example in which an example of a π-type matching circuit using two variable vacuum capacitors and one coil is used as an example of a matching circuit, but a T-type matching circuit or an L-type matching circuit is used. Any device using a variable vacuum capacitor as a variable reactance element such as a circuit can be used.

  The controller 21 includes a CPU 16, a storage device 20, a communication device 19, an input device 17, and a display device 18. The CPU 16 processes the calculation of the life of the variable vacuum capacitor (the amount of life elapsed), for example, according to the flow shown in FIG. The above process is applied to both the variable vacuum capacitors 11 and 13.

  Further, the storage device 20 records the elapsed amount of life of the variable vacuum capacitors 11 and 13. The input device 17 is used for various operations such as setting of the alarm threshold. The display device 18 is used for displaying an alarm or displaying a graph showing a change over time in the amount of elapsed life. The communication device 19 is used for communication with the controller of the plasma processing apparatus or communication with an external terminal. Note that an external terminal connected using the communication device 19 may be used instead of the input device 17 or the display device 18. For example, instead of displaying a graph showing a change in life on the display device 18, It may be possible to display.

  FIG. 7 is a diagram for explaining an example in which the automatic matching machine of the present embodiment is applied to a plasma processing apparatus. First, the reactive gas 41 is introduced into the vacuum vessel 36. Next, the output of the source RF power source 32 is introduced into the vacuum vessel 36 via the source RF automatic matching machine 34, and plasma 37 is generated. The substrate (wafer) 38 to be processed is placed on the sample stage 40, and the output of the bias RF power source 43 is applied to the sample stage 40 via the bias RF automatic matching machine 42.

  The source RF automatic matching machine 34 and the bias RF automatic matching machine 42 have a function of outputting information on the electrode position of each variable vacuum capacitor, and the information on the electrode position of each variable vacuum capacitor is input to the controller 31. Is done. The controller 31 executes the process shown in FIG. 1 using the input information on the electrode position of the variable vacuum capacitor.

  The elapsed amount of life of the variable vacuum capacitor calculated by the above process is stored in the storage device 44. The input / output terminal 45 performs various input operations such as setting of an alarm threshold value, alarm display, and graph display representing a change in elapsed life over time.

  As described above, according to the present embodiment, the electrode position of the variable vacuum capacitor is detected and the expansion / contraction amount of the bellows is calculated. In this case, assuming that the mechanical life is consumed every time the bellows expands and contracts once, a life addition value corresponding to the consumption of the life is added. The lifetime addition value is changed according to the expansion / contraction amount of the bellows, for example, from the mechanical lifetime curve of the bellows shown in FIG. When the cumulative value of the life addition values thus added exceeds a preset threshold value (for example, 0.8), an alarm is output to prompt replacement of the variable vacuum capacitor, for example.

  Further, a history (change in time) of the cumulative value of the life addition value is stored in a storage device so that it can be viewed at any time according to a user request. Thereby, the user can always confirm the change of the remaining life.

  The amount of change in the electrode position of the vacuum capacitor may be reduced by changing the position of the vacuum capacitor before starting the operation of the plasma processing apparatus, that is, the preset position. For this reason, the lifetime of the variable vacuum capacitor can be extended by adjusting the preset position based on the history of the cumulative value of the lifetime addition value.

  Thus, the remaining life of the variable vacuum capacitor used in the automatic matching machine can be predicted, and the replacement frequency of the variable vacuum capacitor can be limited to the number of times according to the operation status. In addition, it is possible to prompt the user to replace the variable vacuum capacitor before the lifetime of the variable vacuum capacitor expires, and it is possible to avoid stopping the operating apparatus.

It is a figure explaining the process which calculates the elapsed amount of the lifetime in the automatic matching machine concerning embodiment. It is a figure explaining the mechanical life curve of the bellows used for a variable vacuum capacitor. It is a figure explaining the process of step 1 thru | or 3 of FIG. It is a figure explaining the process of step 4 of FIG. It is a figure explaining the lifetime with respect to real time (the elapsed amount of lifetime). It is a figure explaining the detail of an automatic matching machine. It is a figure explaining the example which applied the automatic matching machine to the plasma processing apparatus. It is a figure explaining the process of step 4 of FIG.

Explanation of symbols

11, 13 Variable vacuum capacitor 12 Coil 14, 23 Motor 15, 22 Rotary encoder 17 Input device 18 Display device 19 Communication device 20 Storage device 21 Controller of automatic matching machine 24 RF sensor
31 Controller of Plasma Processing Apparatus 32 Source RF Power Supply 34 Automatic Source Matching Machine for Source RF 35 Antenna Electrode 36 Vacuum Container 37 Plasma 38 Substrate 39 Exhaust Means 40 Sample Stand 41 Reactive Gas 42 Bias RF Automatic Matching Machine 43 Bias RF Power Supply 44 Storage device 45 Input / output terminal

Claims (5)

A capacitor having a pair of electrodes disposed in a space held in a vacuum so as to be mutually displaceable via a bellows; and a coil, wherein one of the pair of electrodes is displaced with respect to the other, and the capacitor In the automatic matching machine that adjusts the impedance of the matching circuit composed of the
A life addition value is set in advance for each displacement amount of the electrode position,
The preset lifetime addition value is accumulated for each difference between the maximum value and the minimum value that are continuously observed in the displacement of the electrode position, and the elapsed amount of life of the automatic matching machine is calculated based on the accumulated value. Automatic alignment machine characterized by that. In the automatic alignment machine according to claim 1,
An automatic matching machine, wherein an alarm is issued when the calculated elapsed life amount reaches a preset value. In the automatic alignment machine according to claim 1,
An automatic matching machine comprising: a storage unit that stores a history of the calculated elapsed amount of life, and a display device, wherein the stored history of the elapsed amount of life is displayed on the display unit. In the automatic alignment machine according to claim 1,
An automatic matching machine characterized in that a high-frequency power source of a plasma processing apparatus and an antenna electrode for plasma generation are connected via the matching machine. A capacitor having a pair of electrodes disposed in a space held in a vacuum so as to be mutually displaceable via a bellows; and a coil, wherein one of the pair of electrodes is displaced with respect to the other, and the capacitor In the life judgment method of the automatic matching machine that adjusts the impedance of the matching circuit composed of the coil and coil,
A life addition value is set in advance for each displacement amount of the electrode position,
Accumulating the preset lifetime addition value for each difference between the maximum value and minimum value of the continuously observed displacement of the electrode position, and calculating the elapsed amount of life of the automatic matching machine based on the accumulated value. A method for determining the life of an automatic alignment machine, characterized in that an alarm is issued when the calculated elapsed life has reached a predetermined percentage of a preset expected life.

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