JP4293318B2 - Pressure control abnormality detection method, abnormality display method, and semiconductor manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pressure control abnormality detection device in a semiconductor manufacturing apparatus that controls a valve opening based on a pressure setting value to control a pressure in a chamber, and particularly relates to the pressure control abnormality for a pressure setting state. The present invention relates to a pressure control abnormality detection device in a semiconductor manufacturing apparatus that is detected from a behavior of an opening degree.
[0002]
[Prior art]
FIG. 13 is a view showing a pressure control device and a main control device for controlling it in a conventional semiconductor manufacturing apparatus.
In FIG. 13, the pressure control device 1 includes a valve control device 4 for controlling the valve opening based on the pressure set value from the pressure setting unit 3 of the main control device 2.
The valve control device 4 includes a valve opening degree control unit 8 connected to the output side of the pressure setting unit 3 and a valve driving unit 9 connected to the output side of the valve opening degree control unit 8.
[0003]
The pressure control device 1 is connected to the output side of the valve driving unit 9 and is provided on a pipe 13 from a chamber (not shown) to the vacuum pump. The valve 5 opens and closes the pipe 13 and the valve in the pipe 13. 5, provided on the output side of the valve drive unit 9, and a pressure sensor 7 for detecting the pressure in the pipe 13 and outputting the detected pressure to the valve opening degree control unit 8. And a valve opening degree detection unit 6 for outputting the detected opening degree to the valve opening degree control unit 8 and the main controller side.
The valve 5, the valve opening degree detection unit 6 and the like are configured by a pressure control valve APC (air presser controller).
[0004]
The main controller 2 is connected to a pressure setting unit 3 for outputting a pressure set value to the valve opening degree control unit 8 and the output side of the pressure setting unit 3 and the valve opening degree detection unit 6. And a display unit 10 including a data display unit 10a for displaying using numerical values. The display unit 10 is composed of a monitor screen.
[0005]
In the above configuration, the valve control device 4 is configured to detect the detected pressure value from the pressure sensor 7 and the valve opening degree detection unit 6 so that the chamber pressure becomes a desired pressure based on the pressure setting value from the pressure setting unit 3. The opening degree of the valve 5 is controlled while referring to the opening degree.
Further, the display unit 10 displays the pressure set value from the pressure setting unit 3 and the valve opening data from the valve opening detection unit 6 together with time.
[0006]
[Problems to be solved by the invention]
Since the pressure control device and the main control device in the conventional semiconductor manufacturing apparatus are configured as described above, the pressure control abnormality of the semiconductor manufacturing apparatus cannot be automatically detected, and the occurrence of the pressure control abnormality is caused by the data display unit 10a. It was not possible to recognize them other than making individual judgments by referring to the graphs and numerical values or logging data (not shown).
For this reason, the occurrence of pressure control abnormality may be erroneously missed or overlooked. In such a case, a large amount of wafers must be discarded, and various processes up to that point are wasted, increasing the yield rate. However, this also increases the manufacturing cost of semiconductors.
[0007]
In such a case, if the cause of the pressure control abnormality is pursued, it must be performed by analyzing a large amount of data, and elucidating the cause requires a lot of time and labor. Even if a pressure control device that has caused such a pressure control abnormality should be repaired by adjustment, cleaning, replacement of some parts, etc., the entire device is replaced. This is the cause of the increase.
[0008]
Accordingly, the present invention has been made to solve the above-described conventional problems, and can automatically recognize a pressure control abnormality of a semiconductor manufacturing apparatus and can also investigate the cause thereof, thereby determining the occurrence of the pressure control abnormality. An object of the present invention is to provide a pressure control abnormality detection device in a semiconductor manufacturing apparatus that can eliminate the possibility of mistakes and overlooks and that can be easily maintained.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problem, the present invention provides a pressure control abnormality detection device in a semiconductor manufacturing apparatus that controls a valve opening based on a pressure setting value to control a pressure in a chamber, wherein the valve A valve opening degree detecting means for detecting the opening degree, and determining the behavior of the valve opening degree with respect to the pressure setting state based on the valve opening degree detected by the valve opening degree detecting means and the pressure set value. And pressure control abnormality detecting means for detecting pressure control abnormality.
[0010]
In the embodiment of the present invention, a pressure setting unit 3 for setting a desired pressure, a valve control device 4 for controlling the opening of the valve 5 with respect to the pressure set value from the pressure setting unit 3, The valve opening degree detection unit 6 for detecting the opening degree of the valve 5 and the pressure setting state of the pressure setting unit 3, the behavior of the valve 5 when the set pressure is increased, when the set pressure is decreased, or when the set pressure is constant. The abnormality is detected by detecting based on the detected opening of the valve opening detector 6 and determining its behavior.
[0011]
And according to such a structure, the pressure control abnormality of a semiconductor manufacturing apparatus can be recognized automatically, and the possibility that the judgment of pressure control abnormality generation | occurrence | production may be mistaken or missed can be eliminated.
[0012]
According to the present invention, the pressure control abnormality detecting means further includes pressure control abnormality cause determining means for further determining the cause of the pressure control abnormality based on the behavior of the valve opening.
[0013]
In the embodiment of the present invention, various behavior patterns of the valve opening and failure causes are determined in advance, and the cause of pressure control abnormality is determined according to the detected behavior pattern.
[0014]
And according to such a structure, since a pressure control abnormality is detected with the cause, the maintenance of a pressure control apparatus can also be performed easily.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
FIG. 1 is a block diagram showing a pressure control abnormality detecting device in a semiconductor manufacturing apparatus according to an embodiment of the present invention.
[0016]
In FIG. 1, the pressure control abnormality detection device is composed of a pressure control device 1A and a main control device 2A.
The pressure control device 1A includes a valve control device 4 for controlling the valve opening based on the pressure set value from the pressure setting unit 3 of the main control device 2A. The valve control device 4 includes a valve opening degree control unit 8 connected to the output side of the pressure setting unit 3 and a valve driving unit 9 connected to the output side of the valve opening degree control unit 8.
[0017]
The pressure control device 1A is connected to the output side of the valve drive unit 9 and is provided on the pipe 13 from the chamber (not shown) to the vacuum pump. The valve 5 for opening and closing the pipe 13 and the valve in the pipe 13 are provided. 5, provided on the output side of the valve drive unit 9, and a pressure sensor 7 for detecting the pressure in the pipe 13 and outputting the detected pressure to the valve opening degree control unit 8. And a valve opening degree detection unit 6 for outputting the detected opening degree to the valve opening degree control unit 8 and the main controller side.
The valve 5 can be configured using a pressure control valve APC, for example, as in the prior art.
[0018]
The main controller 2A is connected to a pressure setting unit 3 for outputting a pressure setting value to the valve opening control unit 8, and to the output side of the pressure setting unit 3 and the valve opening detection unit 6, and samples these output values. As will be described later, an abnormality of the pressure control device 1A and the like is detected, and at the output side of the abnormality detection / cause determination unit 12 of the pressure control device for determining the cause and the abnormality detection / cause determination unit 12 And a connected display unit 11.
[0019]
Based on the output of the abnormality detection / determination unit 12, the display unit 11 includes an abnormality display unit 11b that displays the occurrence of the abnormality and the cause of the abnormality when the abnormality occurs, and the opening degree data and the pressure set value as in the conventional case. And a data display unit 11a for displaying data related to the data using graphs and numerical values.
[0020]
In the above configuration, the valve control device 4 is configured to detect the detected pressure value from the pressure sensor 7 and the valve opening degree detection unit 6 so that the chamber pressure becomes a desired pressure based on the pressure setting value from the pressure setting unit 3. The opening degree of the valve 5 is controlled while referring to the opening degree.
In the control of the valve opening, the opening of the valve 5 is actuated by the valve driving unit 9 based on the pressure set value from the pressure setting unit 3, but some abnormality has occurred in the pressure control device. In this case, the valve opening degree behaves differently from the normal time. Further, this behavior differs depending on the cause of pressure control abnormality. Therefore, it is possible to detect a pressure control abnormality and to recognize the cause thereof by storing this behavior pattern in advance and corresponding to which of the patterns the obtained valve opening behavior corresponds. it can.
Various behavior patterns can be obtained experimentally in advance, for example, at the time of setting the apparatus.
[0021]
FIG. 2 is a block diagram illustrating an example of an abnormality detection / cause determination unit of the pressure control device.
The abnormality detection / cause determination unit 12 is connected to the output side of the pressure setting unit 3 and the valve opening degree detection unit 6, and a data sampling unit 12a that samples data output from these, and various behavior patterns of the valve opening degree. The behavior pattern storage unit 12c stores the behavior pattern, and the behavior pattern storage unit 12c and the data sampling unit 12a are connected to the behavior pattern measured by the data sampling unit 12a and correspond to any of the behavior patterns stored in the storage unit 12c. Connected to the behavior pattern associating unit 12b for determining whether to do so, the abnormality cause storage unit 12e that stores various abnormal causes so as to correspond to the behavior pattern, and the abnormality cause storage unit 12e and the behavior pattern association unit 12b. Cause of abnormality corresponding to behavior pattern determined by behavior pattern association unit 12b Search from the abnormality cause storage unit 12e, and is configured by a malfunction cause the search section 12d to be output to the display unit 11 and the search results.
[0022]
6 to 12 are time charts showing examples (behavior patterns) of the behavior of the valve opening with respect to various pressure setting states, (a) showing the pressure setting state, and (b) showing the valve opening with respect thereto. The behavior is shown.
FIG. 6 shows the behavior of the valve opening when the set pressure value is increased at a certain time, and FIG. 6 shows the behavior at the normal time when there is no abnormality in the pressure control. As is clear from this figure, it can be seen that when the pressure setting is changed (increase change) during normal operation, the valve opening is also changed (increase change in opening) almost simultaneously.
FIG. 7 shows a sampling example in which the opening degree is sampled and acquired for the behavior of the valve opening degree as shown in FIG. 6B, and the sampling period is T in the embodiment of the present invention.
[0023]
FIG. 8 shows a behavior pattern in which the valve opening is not changed as the pressure setting increases as an example of pressure control abnormality. In this case, it is considered that a failure (control failure) of the control device or a mechanical failure is a cause.
[0024]
FIG. 9 shows, as an example of pressure control abnormality, a behavior pattern in which the valve opening becomes smaller with respect to the pressure setting increase and the valve opening is changed in the opposite direction to that at the normal time. In this case, it can be considered that the electrical unnecessary such as failure of the control device or failure of the electric circuit (disconnection or short circuit) is the cause.
[0025]
FIG. 10 shows, as an example of pressure control abnormality, a behavior pattern in which the valve opening increases at a moderate speed with respect to the pressure setting increase. In this case, a failure of the control device, a valve motor abnormality, a mechanical failure, etc. can be considered.
[0026]
FIG. 11 shows, as an example of pressure control abnormality, a behavior pattern in which the valve opening periodically drifts when there is no change in pressure setting (when the pressure setting value is constant). In this case, control failure, a vacuum pump motor abnormality, etc. are considered.
[0027]
FIG. 12 shows an example of a saturated abnormality operation in which the valve opening becomes 0% when the set pressure is slightly decreased as an example of the pressure control abnormality. In this case, control failure or electrical failure is considered.
[0028]
The valve behavior pattern shown above is an example, and using these behavior patterns or a part thereof, the pressure control device abnormality detection / cause determination unit 12 detects the pressure control device abnormality and determines the cause thereof. To do.
Hereinafter, the operation of the abnormality detection / cause determination unit 12 of the pressure control device will be described with reference to FIGS. 3 to 6.
[0029]
FIG. 3 shows a flowchart in which an abnormality is detected from the behavior pattern of the valve opening relative to the pressure setting state when the set pressure is mainly increased (pressure increase setting).
First, in step S1, it is determined whether or not it is in the pressure control state. If it is in the control state, the process proceeds to step S2. In step S2, it is determined whether or not there is a change in pressure setting (set pressure). If there is a change, the process proceeds to step S3. On the other hand, when it is determined that there is no change in the pressure setting (when the pressure setting is constant), the process proceeds to step S31 described later in FIG.
[0030]
In step S3, it is determined whether or not the change is a change due to a pressure increase. If the pressure increase is set (pressure increase), the process proceeds to step S4. On the other hand, when the pressure increase setting is not set (when the pressure decrease setting is set), the process proceeds to step S21 described later in FIG.
[0031]
In step S4, sampling of the valve opening is measured over a predetermined time. In step S5, it is determined whether or not there is a change in the valve opening as a result of sampling measurement. If there is a change in the opening, the process proceeds to step S6 and it is determined whether or not the opening is increased. If it is determined that the valve operation has been increased, the process proceeds to step S7 to determine whether or not the valve operation is slow (slow). If it is determined that the operation is slow, the monitor display (abnormality cause display) of “control failure”, “valve motor abnormality”, and “mechanical failure” is performed together with the “abnormality” display in step S8. The process ends.
[0032]
On the other hand, if it is determined in step S5 that there is no change in the valve opening, the process proceeds to step S9, where the monitor display of “control failure” and “mechanical failure” is performed together with the “abnormal” display, and the process is terminated. To do.
If it is determined in step S6 that the valve opening is not increasing (decreasing), it is assumed that the valve is driven in the reverse direction, and “control failure” or “electrical failure” is determined in step S10. "Is displayed together with the" abnormal "display, and the process ends.
If it is determined in step S7 that the valve operation is not slow, the pressure control is determined to be normal in step S11, and the process returns to step S1.
[0033]
Next, the operation when the determination is negative (pressure reduction setting) in step S3 described above will be described with reference to FIG. FIG. 4 shows a flowchart in which an abnormality is detected from the behavior pattern of the valve opening relative to the pressure setting state when the set pressure is mainly reduced.
[0034]
First, sampling of the valve opening is measured over a predetermined time in step S21, and then the process proceeds to step S22. In step S22, it is determined whether or not there is a change in the valve opening. If it is determined that there is a change, the process proceeds to step S23, where it is determined whether or not the valve opening is decreased. If it is determined that the valve opening is decreased, the process proceeds to step S24, where it is determined whether or not the valve operation is slow. If it is determined that the valve operation is slow, in step S25, monitor displays such as “control failure”, “valve motor abnormality”, “mechanical failure” and the like are performed together with the “abnormal” display. finish.
[0035]
On the other hand, if it is determined in step S24 that the valve operation is not slow, the process proceeds to step S28, a normal determination is made, and the process returns to step S1 (FIG. 3).
If it is determined in step S22 that there is no change in the valve opening degree, the process proceeds to step S26, where the “control failure” and “mechanical failure” monitor displays are displayed together with the “abnormal” display, and the process ends.
Furthermore, if it is determined in step S23 that the valve opening is not decreasing, it is assumed that the valve is driven in the reverse direction, and the monitor display of “control failure” and “electrical failure” is displayed as “abnormal” in step S27. This is done together with the process.
[0036]
Next, the operation when the determination in step S2 is negative (no pressure setting change, that is, the set pressure value is constant) will be described with reference to FIG. FIG. 5 shows a flowchart in which an abnormality is detected from the behavior pattern of the valve opening relative to the pressure setting state when the set pressure is mainly constant.
[0037]
First, in step S31, sampling of the valve opening is measured. In step S32, it is determined whether or not there is a drift in the valve opening. If it is determined that there is a drift, the monitor display of “Poor control” and “Vacuum pump motor abnormality” is displayed as “abnormal” in step S33. This is done together with the process.
[0038]
If it is determined in step S32 that there is no drift in the valve opening, the process proceeds to step S34 to determine whether or not the valve opening is decreasing. If it is determined that the valve opening is decreasing, step S35 is performed. The monitor display of “defective pressure sensor” is performed together with the “abnormal” display, and the process ends.
[0039]
When it is determined in step S34 that the valve opening is not decreasing, the process proceeds to step S36, where it is determined whether or not the valve opening is increasing. In S37, “valve clogged” and “vacuum pump sag” are displayed together with “abnormal” display, and the process is terminated.
[0040]
If it is determined in step S36 that the valve opening is not increasing, the process proceeds to step S38, where it is determined whether or not the valve opening is changing randomly. If it is determined that the valve opening is changing randomly, In step S39, the monitor display of “control failure” and “pressure sensor failure” is performed together with the “abnormal” display, and the process is terminated.
[0041]
If it is determined in step S38 that the valve opening has not changed randomly, the process proceeds to step S40, where it is determined whether or not the valve opening remains fully open, and if it is determined that the valve opening remains fully open. In step S41, the monitor display of “vacuum pump sag” and “valve mechanical failure” is performed together with the “abnormal” display, and the process ends.
[0042]
If it is determined in step S40 that the valve opening is not fully opened, the process proceeds to step S42, where it is determined whether or not the valve opening remains closed. In S43, the monitor display of “valve mechanical failure” is performed together with the “abnormal” display, and the process is terminated.
[0043]
On the other hand, if it is determined in step S42 that the valve opening is not closed, it is determined that there is no other abnormal element and normal determination is performed in step 44 and the process returns to step S1 (FIG. 3).
[0044]
As described above, according to the embodiment of the present invention, the cause of the abnormality can be recognized together with the detection of the pressure control abnormality by the behavior pattern of the valve opening, and the pressure control abnormality of the semiconductor manufacturing apparatus is automatically recognized. In addition, the cause of the failure can be pursued, so that the possibility of erroneous or missed determination of the occurrence of pressure control abnormality can be eliminated, and the maintenance thereof can be facilitated.
[0045]
The embodiment shows an example of the present invention. For example, a more detailed abnormal behavior pattern of the valve opening degree can be combined with the flowcharts shown in FIGS. For example, the handling of the behavior pattern shown in FIG. 12 is omitted in the flowchart shown in FIG. 4, but when this abnormal behavior pattern is considered in FIG. 4, for example, it is shown in FIG. 12 between step S24 and step S28. Obviously, a step for judging the behavior and a display step corresponding to the step may be provided.
[0046]
【The invention's effect】
As is clear from the above description, according to the present invention, based on the behavior of the valve opening with respect to the pressure setting state, it is possible to display the pressure control abnormality of the semiconductor manufacturing apparatus and its cause. It is possible to automatically recognize pressure control abnormalities in semiconductor manufacturing equipment, and to investigate the cause, thereby eliminating the possibility of erroneous or overlooked occurrences of pressure control abnormalities and facilitating maintenance. There is an effect.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a pressure control abnormality detecting device of a semiconductor manufacturing apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram showing an abnormality detection / cause determination unit of the pressure control device.
FIG. 3 is a flowchart showing an operation when the pressure increase setting is changed in the embodiment.
FIG. 4 is a flowchart showing an operation when the pressure reduction setting is changed in the embodiment.
FIG. 5 is a flowchart showing an operation when the pressure setting is not changed in the embodiment.
FIG. 6 is a time chart showing an example of a behavior pattern of a valve opening degree.
FIG. 7 is a time chart showing an example of a behavior pattern of a valve opening degree.
FIG. 8 is a time chart showing an example of a behavior pattern of a valve opening degree.
FIG. 9 is a time chart showing an example of a behavior pattern of a valve opening degree.
FIG. 10 is a time chart showing an example of a behavior pattern of a valve opening degree.
FIG. 11 is a time chart showing an example of a behavior pattern of a valve opening degree.
FIG. 12 is a time chart showing an example of a behavior pattern of a valve opening degree.
FIG. 13 is a block diagram showing a pressure controller and a main controller in a conventional semiconductor manufacturing apparatus.
[Explanation of symbols]
1A Pressure control device 2A Main control device 3 Pressure setting unit 4 Valve control unit 5 Valve 6 Valve opening detection unit 7 Pressure sensor 8 Valve opening control unit 9 Valve drive unit 11 Display unit 11b Abnormal display unit 12 Abnormal pressure control unit Detection / cause determination unit 12a Data sampling unit 12b Behavior pattern association unit 12c Behavior pattern storage unit 12d Abnormal cause search unit 12e Abnormal cause storage unit

Claims (11)

A valve provided in the piping between the vacuum pump for evacuating the chamber and the chamber, and controls the valve opening of the valve based on the pressure setpoint, the pressure in the semiconductor control device designed to control the pressure in the chamber A control abnormality detection method ,
The valve opening degree of the valve is detected, the valve opening pattern and the pressure set value are sampled at predetermined time intervals to obtain a valve behavior pattern, and at least one behavior pattern stored in advance In the semiconductor manufacturing apparatus, the pressure control abnormality is detected by searching for at least one abnormality cause stored in advance for an abnormality cause corresponding to the associated behavior pattern Pressure control abnormality detection method. An abnormality in a semiconductor manufacturing apparatus in which a valve is provided in a pipe between a chamber and a vacuum pump that exhausts the chamber, and the valve opening degree of the valve is controlled based on a pressure setting value to control the pressure in the chamber. Display method,
Detecting the valve opening, obtaining a behavior pattern by sampling the detected valve opening and the pressure setting value at a predetermined time interval, and associating with at least one behavior pattern stored in advance; The abnormality cause corresponding to the associated behavior pattern is searched from at least one abnormality cause stored in advance, the pressure control abnormality is detected, the occurrence of the pressure control abnormality is displayed, and the An abnormality display method in a semiconductor manufacturing apparatus, characterized by displaying an abnormality cause. A semiconductor manufacturing apparatus in which a valve is provided in a pipe between a chamber and a vacuum pump that exhausts the chamber, and the valve opening degree of the valve is controlled based on a set pressure value to control the pressure in the chamber. And
A pressure sensor for detecting the pressure of the pipe provided with the valve;
Valve opening degree detecting means for detecting the valve opening degree of the valve;
Valve control means for controlling the valve opening and controlling the pressure to the pressure set value;
A pressure control device comprising:
Pressure setting means for setting the pressure set value;
An abnormality detection cause determination means that is connected to the pressure setting means and the output side of the valve opening detection means, detects an abnormality of the pressure control device, and determines an abnormality cause that is the cause of the abnormality;
Display means connected to the output side of the abnormality detection cause determination means;
A main controller comprising:
A semiconductor manufacturing apparatus comprising: The abnormality detection cause determination means includes
  A sampling unit for acquiring the valve opening and the pressure set value;
  A behavior pattern storage unit storing at least one pattern of the valve opening;
  An associating unit that associates a sampled behavior pattern with a stored behavior pattern;
  An abnormality cause storage unit storing at least one abnormality cause corresponding to the behavior pattern;
  An abnormality cause search unit that searches an abnormality cause corresponding to the behavior pattern associated with the association unit from the abnormality cause storage unit and outputs a result of the search to the display unit;
  4. The semiconductor manufacturing apparatus according to claim 3, further comprising:   The abnormality detection cause determination means includes
  A sampling unit for acquiring the valve opening and the pressure set value;
  A behavior pattern storage unit storing at least one pattern of the valve opening;
  An associating unit that associates a sampled behavior pattern with a stored behavior pattern;
  An abnormality cause storage unit storing at least one abnormality cause corresponding to the behavior pattern;
  An abnormality cause search unit that searches the abnormality cause storage unit for an abnormality cause corresponding to the behavior pattern associated with the association unit, and outputs a result of the search to the display unit,
  The behavior of the valve according to the pressure setting value of the pressure setting means is detected based on the valve opening, and the behavior pattern is obtained by sampling the valve opening data at a predetermined time interval, and stored in advance. A pressure control abnormality is detected by associating the at least one behavior pattern and searching for at least one abnormality cause corresponding to the attached behavior pattern from the stored abnormality causes. Item 4. The semiconductor manufacturing apparatus according to Item 3.   When the pressure set value is constant, the abnormality detection cause determination means determines whether the valve opening drift has occurred, whether the valve opening has a random change, The pressure control abnormality is detected by determining whether there is an increase or whether the valve opening is fully open or fully closed according to the behavior of at least two valve openings. 5. The semiconductor manufacturing apparatus according to 5.   When the pressure set value is changed, the abnormality detection cause determination means is at least two of whether the valve opening is changed, whether the valve opening is increased, and whether the valve operation is slow. 6. The semiconductor manufacturing apparatus according to claim 5, wherein the pressure control abnormality is detected by judging the behavior of the valve.   4. The semiconductor manufacturing apparatus according to claim 3, wherein the display means displays that the pressure control abnormality has occurred and displays the cause of the abnormality.   When the pressure control abnormality is detected, the display means, as the abnormality cause,
  If there is a drift in the valve opening, it is indicated that there is at least one of control failure and vacuum pump motor abnormality,
  If the valve opening is decreasing, display a flow sensor failure,
  When the valve opening is increased, it is indicated that at least one of valve clogging and vacuum pump sag,
  When the valve opening is changing randomly, it is indicated that there is at least one of control failure and flow sensor failure,
  When the valve opening remains fully open, it is indicated that at least one of a vacuum pump sag and a mechanical failure of the valve,
  9. The semiconductor manufacturing apparatus according to claim 8, wherein when the valve opening remains fully closed, a mechanical failure of the valve is displayed.   When the pressure control abnormality is detected, the display means, as the abnormality cause,
  When the valve operation is slow, it is indicated that at least one of control failure, valve motor abnormality, and mechanical failure,
  When there is no change in the valve opening, it is indicated that there is at least one of control failure and mechanical failure,
  9. The semiconductor manufacturing apparatus according to claim 8, wherein when the valve opening degree is increasing, it is displayed as at least one of a control failure and an electrical failure.   The semiconductor manufacturing apparatus according to claim 3, wherein the valve is a valve used in an air presser controller.

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