JPH11288994A - Transfer error predicting mechanism for substrate processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a substrate processing equipment in productivity by a method wherein a transfer system is lessened in frequency of maintenance. SOLUTION: A cassette raising and lowering mechanism 62 is provided to serve as a transfer system, which transfers a substrate into a processing chamber and to enable a cassette 61 inside a load lock chamber 6 to ascend or descend, wherein the cassette up-down mechanism 62 is composed of a stay 621 fixed to the lower edge of the cassette 61 in the load lock chamber 6, a holding arm 622 which holds the lower end of the stay 621, a driven body 624 which fixes the holding arm 622, a pole screw 624 engaged with the driven body 624, a servo motor 625 which rotates the pole screw 624, and a servo motor controller 626 which controls the servo motor 625, and furthermore the cassette raising and lowering mechanism 62 is equipped with an output unit 81, which outputs monitoring the servo signals of the servo motor 625 and a display means 82 which indicates the probability of occurrence of a transfer error, ion accordance with signals transmitted from the output unit 81.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a large scale integrated circuit (LSI) and a flat panel display (FPD).
TECHNICAL FIELD The present invention relates to a substrate processing apparatus used in the manufacture of, for example, the present invention, and particularly to a transport error predicting mechanism for notifying a transport error of a substrate in advance.

[0002]

2. Description of the Related Art High-tech products such as LSIs and FPDs are manufactured through many surface treatments for substrates. A substrate processing apparatus that performs such a surface treatment is almost 100% automated. In terms of substrate transfer, the substrate is automatically transferred to a processing chamber and processed by a transfer system including a transfer robot or the like.

[0003]

With the demand for higher functionality of products and further improvement of productivity, the demand for the reliability of the transport system of the substrate processing apparatus is becoming more and more severe. For example, in various substrate processing apparatuses used for manufacturing LSI, MTBMA (Meatn Time Between Maintenance) is used.
ance Action, average maintenance action interval) is 100
Time, but recently 300 hours are required.

[0004] In particular, in an apparatus such as a sputtering apparatus, a chemical vapor deposition apparatus, an etching apparatus, or the like, which evacuates a processing chamber to perform processing, it is necessary to open the processing chamber to the atmosphere during maintenance. After the maintenance, the inside of the processing chamber is evacuated again to a predetermined pressure, and after checking the cleanliness of the remaining particles and the like and the reproducibility of the processing, the processing is restarted. Therefore, the operation interruption time of the device required for one maintenance is likely to be longer than that of other devices, and a reduction in maintenance frequency is strongly demanded.

Here, since the transfer system transfers a substrate into or out of the processing chamber, if a failure occurs in the transfer system and a transfer error occurs, the substrate is transferred from the processing chamber. It is often necessary to open the processing chamber to the atmosphere, for example, to manually remove the processing chamber. Therefore, in order to lengthen the MTBMA, it is important to reduce the frequency of maintenance due to the failure of the transport system. In order to reduce the frequency of maintenance due to the failure of the transport system, it is effective to notify the occurrence of the failure of the transport system in advance and to allow for the periodic maintenance.

The present invention has been made to solve such a problem, and has as its object to improve the productivity by reducing the frequency of maintenance of a transport system.

[0007]

According to a first aspect of the present invention, there is provided a mechanism for predicting a transfer error in a substrate processing apparatus for transferring and processing a substrate by a transfer system into a processing chamber. An output unit for monitoring and outputting a servo signal of a servomotor used in the transport system; and a display unit for displaying a possibility of occurrence of a transport error according to a signal from the output unit. Further, in order to solve the above-mentioned problem, the present invention relates to claim 1 of the present application.
According to the invention described in the second aspect, the servomotor is an AC servomotor, and the output unit is a peak hold unit that monitors and holds a peak value of the AC servo current. According to a third aspect of the present invention, in order to solve the above-mentioned problem, in the configuration of the first or second aspect, the display means includes a caution level indicating that inspection should be performed during regular maintenance, and an urgent level. And a warning level indicating that the inspection and repair are required.

[0008]

Embodiments of the present invention will be described below. FIG. 1 is a plan view showing a schematic configuration of a substrate processing apparatus according to an embodiment of the present invention. The substrate processing apparatus shown in FIG. 1 is a multi-chamber type apparatus,
The chamber arrangement includes a separation chamber 1 arranged at the center, a plurality of processing chambers 2, 3, 4, 5, and two load lock chambers 6 provided around the separation chamber. Each of the chambers 1, 2, 3, 4, 5, and 6 is a vacuum vessel evacuated by a dedicated or shared exhaust system. In addition, each chamber 2, 3, 4, with respect to the separation chamber 1
Gate valves 10 are provided at connection points 5 and 6, respectively.

A transfer robot 11 is provided in the separation chamber 1. The transfer robot 11
The substrates 9 are taken out one by one from the load lock chamber 6 and sent to each of the processing chambers 2, 3, 4, and 5, where the processing is sequentially performed. Then, after the last processing is completed, the processing is returned to the same load lock chamber 6. As the transfer robot 11, an articulated robot provided with an arm for mounting and holding the substrate 9 at the tip is suitably used. It is preferable to provide two arms so that the two substrates 9 can be moved independently independently at the same time, because the efficiency of transportation is improved. Also,
The interior of the separation chamber 1 is evacuated by an exhaust system (not shown) and is maintained at a predetermined vacuum pressure. Therefore,
As the transfer robot 11, a transfer robot that can operate under vacuum pressure is used.

The configuration of each of the processing chambers 2, 3, 4, 5, and 6 is appropriately determined according to the content of the processing. For example, when an example is shown in which the present apparatus is a sputtering apparatus, one of the processing chambers is configured as an etching chamber 2 for removing an oxide film and a protective film on the surface of the substrate 9 by sputter etching. One of the other processing chambers is configured as a preheat chamber 3 for preheating the substrate 9 before film formation and performing degassing or the like. One of the other processing chambers is configured as a sputter chamber 4 for forming a predetermined thin film by sputtering. Still another processing chamber 5 is configured as a film forming chamber for forming a base film before film formation, or as a cooling chamber for cooling the substrate 9 after film formation.

The external cassette 71 placed on the atmosphere side
An autoloader 7 is provided for transferring the substrate 9 between the substrate and the load lock chamber 6. The autoloader 7 is a robot including an articulated arm,
Are transported while holding one or more sheets at a time.

Next, the overall operation of the substrate processing apparatus shown in FIG. 1 will be described. In FIG. 1, a predetermined number of substrates 9 are carried into one load lock chamber 6 from an external cassette 71 by an autoloader 7 and stored in a cassette (hereinafter referred to as a load lock cassette) 61 in the load lock chamber 6. The transfer robot 11 takes out one substrate 9 from the load lock chamber 6 and sends it to the etching chamber 2 first. In the etching chamber 2, the natural oxide film and the protective film on the surface are removed as described above. Next, the transfer robot 11 sends the substrate 9 to the preheat chamber 3. The substrate 9 is preheated in the preheat chamber 3 and degassing is performed.

Next, the transfer robot 11 sends the substrate 9 to the sputtering chamber 4. In the sputtering chamber 4, a desired thin film is formed on the surface of the substrate 9 by sputtering the target. Then, if necessary, the substrate 9
After cooling, the substrate 9 is transferred to the other load lock chamber 6 by the transfer robot 11 and stored in the cassette 61 in the load lock. In this way, the substrates 9 are sent one by one to each of the processing chambers 2, 3, and 4 to perform the processing, and then are stored in the load lock cassette 61 in the other load lock chamber 6. When a predetermined number of processed substrates 9 are stored in the load lock cassette 61, the external cassette 71 is
Transport to

The transport system to which the present invention is directed is a general term for a system for transporting the substrate 9. In the apparatus of the present embodiment, the cassette 61 in the load lock and the external cassette 7
1 and a transfer robot 11 provided in the separation chamber 1 for transferring the substrate 9 between the processing chambers 2, 3, 4, 5 and the load lock chamber 6. In addition, a cassette elevating mechanism for elevating and lowering the cassette 71 in the load lock for the transfer of the substrate 9 by the transport robot 11 is included in the concept of the transport system. In the following description, as an example, the configuration of the transport error prediction mechanism of the present embodiment will be described in relation to the cassette lifting mechanism. FIG. 2 is a front view showing a schematic configuration of a cassette elevating mechanism provided in the load lock chamber shown in FIG.

The cassette 61 in the load lock has a structure in which a large number of substrates can be accommodated in a state where they are stacked in a horizontal position at predetermined intervals. The height of the internal space of the load lock chamber 6 is slightly more than twice the height of the cassette 61 in the load lock, and the cassette 61 in the load lock is located at a position lower than the middle height of the load lock chamber 6 (hereinafter, a lower limit position). ) And a position above the middle height (hereinafter, upper limit position).

The cassette elevating mechanism 62 for elevating and lowering the cassette 61 in the load lock at the above two positions includes a column 621 fixed to the lower portion of the cassette 61 in the load lock, a holding arm 622 holding the lower end of the column 621, The driven body 623 to which the arm 622 is fixed, and the driven body 62
3 is engaged with the ball screw 624 and the ball screw 6
It mainly comprises a servo motor 625 for rotating the motor 24 and a servo motor controller 626 for controlling the servo motor 625.

An opening is formed in the bottom plate portion of the load lock chamber 6, and a column is inserted through the opening. The support 621 is provided with a linear guide (not shown) so that the support 621 moves up and down with good linearity.
Note that a bellows 627 is provided so as to cover the periphery of the support column projecting downward from the load lock chamber 6. This prevents leakage (vacuum leakage) through the opening in the bottom plate portion. When the servomotor 625 operates and the ball screw 624 rotates, the ball screw 24
Arm 62 fixed to driven body 623 that meshes with
2 goes up and down. As a result, the column 621 also moves up and down, and the cassette 616 in the load lock also moves up and down integrally.

In FIG. 2, a gate valve provided on the right side (hereinafter, a vacuum side gate valve 101) is used.
The separation chamber 1 shown in FIG. The case where the substrate 9 is taken out of the load lock chamber 6 will be described. First, the load lock inner cassette 61 is located at the lower limit position, and in this state, the vacuum side gate valve 101 is opened. Then, the tip of the arm of the transfer robot 11 enters below the uppermost substrate 9 of the cassette 61 in the load lock. Then, the cassette elevating mechanism 62 operates to lower the cassette 61 in the load lock by a predetermined short distance. As a result, the uppermost substrate 9 rides on the tip of the arm. Thereafter, the transfer robot 11 sends the substrate 9 to each of the processing chambers 2, 3, 4, and 5, and performs the processing. During this time, the cassette lifting mechanism 62 operates to raise the cassette 61 in the load lock by a predetermined distance. As a result,
The substrate 9 at the accommodation position one level lower than the uppermost stage is the transfer robot 1
The arm is located at a position slightly higher than the entry line of the first arm. Then, after the arm has entered below the substrate 9 at this stage, the cassette elevating mechanism 62 operates to further lower the cassette 61 in the load lock by a predetermined short distance. As a result, the substrate 9 rides on the arm and is transferred by the transfer robot 11.

In this way, the transfer robot 11 takes out the substrate 9 sequentially from the upper stage, and
Send to 3, 4, 5 for processing. During this time, when the processing of the substrate 9 taken out is completed and the substrate 9 returns to the load lock chamber 6, the substrate 9 is loaded into the cassette 6 in the load lock.
Return to the original position in 1. Specifically, the cassette elevating mechanism 62 operates, and the cassette inside the load lock is moved so that the position where the substrate 9 is initially accommodated is higher than the entrance line of the arm of the transfer robot 11 by a predetermined short distance. 61 is raised or lowered. After the arm holding the substrate 9 advances on the entry line and reaches the cassette 61 in the load lock, the cassette lifting mechanism 62
Raises the cassette 61 in the load lock by a predetermined short distance. As a result, the substrate 9 is stored at the original position.
When all the processed substrates 9 are stored in their original positions in this manner, the atmosphere-side gate valve 102 on the left side of FIG.
Opens, and the unloading operation of the processed substrate 9 is performed by the autoloader 7.
It is performed by

In the present embodiment, the following transport error prediction mechanism is provided in order to increase the reliability of the operation of lifting and lowering the cassette 61 in the load lock. This point is illustrated in FIG.
This will be described with reference to FIG. FIG. 3 is a diagram showing a schematic configuration of the transport error prediction mechanism. The transport error predicting mechanism mainly includes an output unit 81 that monitors and outputs a servo signal of a servomotor, and a display unit 82 that displays a possibility of occurrence of a transport error according to a signal from the output unit 81. .

In this embodiment, an AC servomotor is used as the servomotor 625. FIG. 3 schematically shows the drive control of the AC servomotor. The input from the commercial AC power supply is converted by the converter unit 83 into three DC currents. The DC current is converted into an alternating current (three-phase alternating current) having a phase difference of 120 degrees by the inverter 84, and is sent to the motor body 85. As a result, the rotor of the motor main body 85 rotates.

The motor body 85 includes a magnetic pole position detector 86
And a speed detector 87 are provided. The speed signal detected by the speed detector 87 is compared with a speed command sent from the outside to generate a speed control signal (deceleration signal or acceleration signal). A current reference signal is created by combining the speed control signal with the detection signal of the magnetic pole position detector 87. Then, each exciting current monitored by the transformer is compared with this current reference signal, and a final control signal is sent to the inverter 84. The inverter section 84 performs pulse width modulation (PWM) control. The final control signal is a gate signal of each transistor included in the inverter unit 84, and each transistor is turned on and off according to the control signal. As a result, the exciting current of each phase is subjected to negative feedback control.

Here, in the present embodiment, the inverter unit 8
An output unit 81 is provided so as to monitor each exciting current sent from the device 4. More specifically, the output from the transformer for monitoring the excitation current is branched and output unit 8
1 is input. The output unit 81 is a peak hold unit that holds the peak value of each exciting current. The peak hold unit holds, for example, a peak value on the + side of each excitation current. More specifically, the maximum value on the positive side is always stored.

The output of the output unit 81 is sent to the display means 82. In the present embodiment, a display of a microcomputer is employed as the display means 82. In accordance with the output of the output unit 81, the microcomputer displays three information, "normal operation", "caution level", and "warning level", as the transport error prediction information. This display content will be described with reference to FIG. FIG. 4 is an explanatory diagram of display contents on the display means. FIG. 4 shows an example of the result of monitoring the exciting current.

In the waveform of the exciting current shown in FIG. 4, the peak hold unit used as the output unit 81 always holds the maximum value of the peak on the + side. That is,
After holding the first peak P1 after the start of detection, since the next peak P2 is higher than P1, P2 is held instead of P1. Then, the next P3 is similarly held instead of P2. Then, since the subsequent peak is lower than P3, P3 is held as it is, and when P4 is detected,
P4 is held instead of P3.

On the other hand, information of "attention level" and "warning level" is stored in the memory of the microcomputer as a criterion for judging the magnitude of the servo current. The logic circuit of the microcomputer compares the signal of the peak value sent from the output unit 81 with this information to generate a display signal on the display. That is, if the peak value is lower than the caution level, “normal operation” is displayed. If the peak value is higher than the caution level and lower than the warning level, “caution level” is displayed.
Is displayed. If the level is equal to or higher than the warning level, "warning level" is displayed. In the example shown in FIG.
Is displayed at the stage when is detected, and is maintained at the stage when P4 is detected.

The caution level is a level that indicates that inspection should be performed during regular maintenance. By performing this prediction, the maintenance of the cassette elevating mechanism 62 can be performed without forgetting the periodic maintenance.
Therefore, it is not necessary to stop the operation of the apparatus later only due to the failure of the cassette elevating mechanism 62, thereby preventing a decrease in productivity. In addition, the warning level is a level for notifying that it should be checked and repaired immediately. In this case, maintenance is performed immediately after the processing of the current lot is completed. The output unit 81 is provided with a reset circuit, and the reset circuit is operated after maintenance is performed. As a result, the held peak value is deleted, and “0” is set as the signal of the initial peak value.

Assuming a transport error in the cassette elevating mechanism 62 having the above configuration, one example of reaching a caution level or a warning level is that the ball screw 624 runs out of oil. When the oil runs out, the required torque of the servomotor 625 increases, and the peak value of the exciting current increases.
In any case, in the present embodiment, the servo motor 625
Since the servo signal is monitored and the possibility of occurrence of a transport error is displayed, the necessity of maintenance of the transport system can always be determined. For this reason, by carrying out maintenance of the transport system together with regular maintenance of the equipment,
It is not necessary to perform maintenance due to only the transport error. Therefore, the productivity of the device is improved. In the case of the sputtering apparatus described above, the replacement of the target is an example of regular maintenance because the target is a consumable item.

In the above description, the cassette lifting mechanism 62
Although a mechanism for predicting a transport error has been adopted for the above, it is preferable that the autoloader 7 and the transport robot 11 be similarly configured. It is optimal that all the drive units of the transport system of the apparatus are servomotors, and the servo signals are monitored to indicate the possibility of a transport error.

The concept of the present invention can be applied not only to an AC servomotor but also to a DC servomotor. In this case, since the servo signal is often a direct current, it is not necessary to hold the peak value, the servo signal is output as it is, and it is determined whether or not the magnitude of the servo signal exceeds the caution level or the warning level. To Also, in the case of an AC servomotor, not only the case where the maximum value of the peak value is held but also the case where the minimum value of the peak value is held. This corresponds to a case where a transport error due to a decrease in torque is predicted.

The "servo signal" in the present invention is:
This is a general term for signals used for servo control, which can predict a transport error by monitoring the signals.
Therefore, there may be a signal other than the above-described excitation current (voltage, frequency, etc.).

[0032]

As described above, according to the invention of each claim of the present application, the servo signal of the servomotor is monitored to indicate the possibility of occurrence of a transport error. Sex can always be determined. For this reason,
By performing the maintenance of the transport system together with the periodic maintenance of the apparatus, it is not necessary to perform the maintenance caused only by the transport error. Therefore, the productivity of the device is improved.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a schematic configuration of a substrate processing apparatus according to an embodiment of the present invention.

FIG. 2 is a front view showing a schematic configuration of a cassette elevating mechanism provided in the load lock chamber shown in FIG.

FIG. 3 is a diagram showing a schematic configuration of a transport error prediction mechanism.

FIG. 4 is an explanatory diagram of display contents on a display unit.

[Explanation of symbols]

 Reference Signs List 6 load lock chamber 61 cassette in load lock 62 cassette elevating mechanism 621 support column 622 holding arm 623 driven body 624 ball screw 625 servo motor 81 output unit 82 display unit 9 substrate

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 6, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Explanation of sign

[Correction method] Change

[Correction contents]

[Description of Signs] 6 Load lock chamber 61 Load lock cassette 62 Cassette raising / lowering mechanism 621 Support 622 Holding arm 623 Driven body 624 Ball screw 625 Servo motor 81 Output unit 82 Display unit 9 Substrate ───────────────────────────────────────────

[Procedure amendment]

[Submission date] February 9, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0003

[Correction method] Change

[Correction contents]

[0003]

With the demand for higher functionality of products and further improvement of productivity, the demand for the reliability of the transport system of the substrate processing apparatus is becoming more and more severe. For example, in various substrate processing apparatuses used in the manufacture of LSI, MTBMA ( Mean Time Between Maintena) is used.
nce Action, average maintenance action interval) is 100
Time, but recently 300 hours are required.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

[0007]

According to a first aspect of the present invention, there is provided a mechanism for predicting a transfer error in a substrate processing apparatus for transferring and processing a substrate by a transfer system into a processing chamber. An output unit for monitoring and outputting a servo signal of a servomotor used in the transport system; and a display unit for displaying a possibility of occurrence of a transport error according to a signal from the output unit. Further, in order to solve the above-mentioned problem, a second aspect of the present invention is described.
According to the invention described in the first aspect , the servo motor is an AC servo motor, and the output unit is a peak hold unit that monitors and holds a peak value of the AC servo current. According to a third aspect of the present invention, in order to solve the above-mentioned problem, in the configuration of the first or second aspect, the display means includes a caution level indicating that inspection should be performed during regular maintenance, and an urgent level. And a warning level indicating that the inspection and repair are required.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008]

Embodiments of the present invention will be described below. FIG. 1 is a plan view showing a schematic configuration of a substrate processing apparatus according to an embodiment of the present invention. The substrate processing apparatus shown in FIG. 1 is a multi-chamber type apparatus,
The chamber arrangement includes a separation chamber 1 arranged at the center, a plurality of processing chambers 2, 3, 4, 5, and two load lock chambers 6 provided around the separation chamber 1 . Each of the chambers 1, 2, 3, 4, 5, and 6 is a vacuum vessel evacuated by a dedicated or shared exhaust system. Further, each chamber 2, 3, with respect to the separation chamber 1
Gate valves 10 are provided at connection points of 4, 5, and 6, respectively.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

The cassette 61 in the load lock has a structure in which a large number of substrates 9 can be accommodated in a horizontal position in a stacked state at a predetermined interval. The height of the internal space of the load lock chamber 6 is slightly more than twice the height of the cassette 61 in the load lock, and the cassette 61 in the load lock is located at a position lower than the middle height of the load lock chamber 6 (hereinafter, a lower limit position). ) And a position above the middle height (hereinafter, upper limit position).

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

An opening is formed in the bottom plate portion of the load lock chamber 6, and a column is inserted through the opening. The support 621 is provided with a linear guide (not shown) so that the support 621 moves up and down with good linearity.
Note that a bellows 627 is provided so as to cover the periphery of the support column projecting downward from the load lock chamber 6. This prevents leakage (vacuum leakage) through the opening in the bottom plate portion. When the servomotor 625 operates and the ball screw 624 rotates, the ball screw 24
Arm 62 fixed to driven body 623 that meshes with
2 goes up and down. As a result, the column 621 is also moved up and down, and the cassette 61 in the load lock is also moved up and down integrally.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

In this way, the transfer robot 11 takes out the substrate 9 sequentially from the upper stage, and
Send to 3, 4, 5 for processing. During this time, when the processing of the substrate 9 taken out is completed and the substrate 9 returns to the load lock chamber 6, the substrate 9 is returned to the original position in the cassette 61 in the load lock. Specifically, the cassette elevating mechanism 62 operates, and the cassette inside the load lock is moved so that the position where the substrate 9 is initially accommodated is higher than the entrance line of the arm of the transfer robot 11 by a predetermined short distance. 61 is raised or lowered.
Then, after the arm holding the substrate 9 advances on the entry line and reaches the cassette 61 in the load lock, the cassette elevating mechanism 62 raises the cassette 61 in the load lock by a predetermined short distance. As a result, the substrate 9 is stored at the original position. When all the processed substrates 9 are stored in the original positions in this way, the left air-side gate valve 102 in FIG. 2 is opened, and the unloading operation of the processed substrates 9 is performed by the autoloader 7. Will be

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0023

[Correction method] Change

[Correction contents]

Here, in the present embodiment, the inverter unit 8
An output unit 81 is provided so as to monitor each exciting current sent from the device 4. Specifically, the excitation current model
The output from the transformer to be monitored is branched and input to the output unit 81. The output unit 81 is a peak hold unit that holds the peak value of each exciting current. The peak hold unit holds, for example, a peak value on the + side of each excitation current. More specifically, the maximum value on the positive side is always stored.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] Explanation of sign

[Correction method] Change

[Correction contents]

[Description of Signs] 6 Load lock chamber 61 Load lock inner cassette 62 Cassette elevating mechanism 621 Support 622 Holding arm 623 Driven body 624 Ball screw 625 Servo motor 81 Output unit 82 Display means 9 Substrate

Claims (3)

[Claims] 1. A mechanism for predicting a transport error in a substrate processing apparatus that transports a substrate into a processing chamber by a transport system and processes the substrate. The mechanism monitors and outputs a servo signal of a servomotor used in the transport system. A transport error predicting mechanism in a substrate processing apparatus, comprising: an output unit; and display means for displaying a possibility of occurrence of a transport error according to a signal from the output unit. 2. The transport error according to claim 1, wherein the servomotor is an AC servomotor, and the output unit is a peak hold unit that monitors and holds a peak value of the AC servo current. Foresight mechanism. 3. The display means is capable of displaying a caution level notifying that inspection should be performed during regular maintenance and a warning level notifying that inspection and repair should be performed immediately. 3. The transport error predicting mechanism in the substrate processing apparatus according to claim 1, wherein: