JP2011007053A - Quality determining method for exhaust characteristic of vacuum device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for properly determining whether the condition of a vacuum pump and a vacuum tank is good or not.SOLUTION: In the quality determining method, a main vacuum pump 12 and a sub-vacuum pump 11 are connected to a vacuum tank 10, and the vacuum tank 10 is evacuated by operating the main vacuum pump 12 and the sub-vacuum pump 11, before vacuum treatment. A value of pressure within the range of the exhaust pressure of the main vacuum pump 12 and the sub-vacuum pump 11 is stored in a storage device 18 as a reference pressure. The reference exhaust velocity at the set reference pressure is obtained in advance, and a value smaller than the reference exhaust velocity is set as a threshold. When the vacuum treatment is performed, the main vacuum pump 12 and the sub-vacuum pump 11 are activated to evacuate the vacuum tank 10, the exhaust velocity at the reference pressure set in advance is obtained, and the obtained exhaust velocity is compared with the threshold. If the obtained exhaust velocity is equal to or higher than the threshold, the condition of the vacuum tank 10 including the main vacuum pump 12 and the sub-vacuum pump 11 is determined to be good, and if the obtained exhaust velocity is lower than the threshold, the condition of the vacuum tank 10 including the main vacuum pump 12 and the sub-vacuum pump 11 is determined to be not good.

Description

  The present invention relates to a technique for collecting pressure values of a vacuum apparatus in time series, calculating a time differential value (corresponding to an exhaust speed) of each pressure value, and diagnosing the exhaust characteristics of the apparatus.

Diagnosis of the exhaust of the apparatus has been made based on whether or not a predetermined pressure is reached within a predetermined time. As for maintenance, maintenance has been performed based on the usage time or the number of processed products.
In the following technology, the quality of the entire vacuum processing apparatus is judged from the exhaust speed relative to the exhaust time of the vacuum pump.

Japanese Patent Laid-Open No. 5-251295

The exhaust characteristics of the apparatus are determined by the exhaust capacity of the pump itself to be exhausted and the increase of the gas in the container on the exhaust side consisting of the gas discharged from the inner wall of the vacuum container and the leakage of the vacuum container.
The pumping speed of the pump has a pressure dependency, and when the discharge gas, leakage, etc. are very small, the influence becomes significant after the pressure of the vacuum vessel is lowered.
In contrast, conventional diagnostic methods focus only on the exhaust time. Alternatively, it is only possible to see the trend from the time-series pressure value graph. In this case, the exhaust time varies greatly depending on the exhaust start pressure value and the exhaust sequence, and the magnitude of the exhaust speed is related to the conventional exhaust time. This method cannot accurately determine the deterioration state of the exhaust characteristics.

In order to solve the above-mentioned problems, the present invention is a method for determining the quality of exhaust characteristics for determining the state of a vacuum device, wherein a vacuum pump to be measured is connected to a measurement vacuum chamber, and the vacuum pump is operated. A reference value acquisition step of evacuating the measurement vacuum chamber and obtaining a reference value corresponding to the exhaust speed when the inside of the measurement vacuum chamber is evacuated to a preset reference pressure; and the vacuum When evacuating the inspection vacuum chamber to which the pump is connected from the pressure higher than the reference pressure to the pressure lower than the reference pressure by the vacuum pump, the pressure in the inspection vacuum chamber is measured, A calculated value corresponding to the exhaust speed is calculated from the measured value and the time interval at the time of measurement, and the calculated value at the reference pressure is compared with a threshold value that is smaller than the reference value. From the results, the vacuum pump and A quality decision method of the exhaust characteristics and a test step of determining acceptability of the state of the inspection vacuum chamber. The vacuum pump to be measured is a vacuum pump corresponding to the measurement pressure range.
The present invention is a pass / fail judgment method including a vacuum processing step of carrying in a vacuum processing of the processing object by carrying the processing target into the inspection vacuum chamber when performing the inspection step, The vacuum processing step is a method for determining whether or not the exhaust characteristics are good after the inspection step.
The present invention is a method for determining whether exhaust characteristics are good or bad, wherein the vacuum chamber for measurement and the vacuum chamber for inspection are the same vacuum chamber.

  The exhaust characteristic deterioration state is judged based on the exhaust speed when the inside of the vacuum chamber is at a predetermined pressure value, so the influence of the exhaust start pressure and the exhaust sequence is reduced, and the exhaust characteristic deterioration state can be judged accurately. it can.

Sectional drawing of the film-forming apparatus of an example used in order to demonstrate this invention Diagram showing the relationship between the pressure in the vacuum chamber and the time when the pressure was measured Diagram showing the relationship between the comparison value corresponding to the pumping speed and the pressure in the vacuum chamber

<Device configuration>
Reference numeral 1 in FIG. 1 denotes a film forming apparatus. The film forming apparatus 1 includes a vacuum chamber 10, a sub vacuum pump (rough pump) 11, and a main vacuum pump (main pump) 12.
The sub vacuum pump 11 and the main vacuum pump 12 are connected to the vacuum chamber 10.
The sub-vacuum pump 11 can start evacuation from the atmospheric pressure in the vacuum chamber 10, and the main vacuum pump 12 can start evacuation from a pressure lower than the atmospheric pressure, and vacuum to a pressure lower than the ultimate pressure of the sub-vacuum pump 11. Can be exhausted.
Accordingly, the vacuum chamber 10 is first evacuated by the sub-vacuum pump 11, and after the inside of the vacuum chamber 10 becomes lower than the operation start pressure of the main vacuum pump 12, the operation of the main vacuum pump 12 is started, When the vacuum pump 11 is disconnected from the vacuum chamber 10, the inside of the vacuum chamber 10 can be evacuated from the atmospheric pressure to the ultimate pressure of the main vacuum pump 12.
The vacuum chamber 10 includes a first vacuum gauge 13 capable of detecting pressure within the operating range of the sub vacuum pump 11 and a second vacuum gauge 14 capable of detecting pressure within the operating range of the main vacuum pump 12. It is connected.

A control device 16 is disposed outside the vacuum chamber 10.
The first and second vacuum gauges 13 and 14 are connected to the control device 16.
When the inside of the vacuum chamber 10 is evacuated by one or both of the sub vacuum pump 11 and the main vacuum pump 12, either one or both of the first and second vacuum gauges 13 and 14 are in the vacuum chamber 10. Detect pressure.
A pressure signal indicating the pressure in the vacuum chamber 10 detected by the first and second vacuum gauges 13 and 14 is output to the control device 16.

The control device 16 has the function of a measuring device, and the input pressure signal is converted into a pressure value in Pa units or Torr units and displayed on the display device 19.
Further, the control device 16 has a storage device 18, and a measurement value composed of an input pressure signal and a measurement value composed of a pressure value obtained by converting the pressure signal into a value in Pa unit or Torr unit are stored in the storage device. 18 is stored.
Here, it is assumed that the pressure signal is converted into a pressure in Pa units and handled.
The control device 16 has a built-in clock or an external clock 15 connected thereto, and the measurement value stored in the control device 16 is stored in association with the measurement time so that the time between measurements can be known. It has become. When the time interval between measurements is known, such as when measurements are taken at regular time intervals, the measurement time need not be stored.

<Reference value acquisition process>
First, in order to measure the initial capacity of the exhaust characteristic, the current capacity of the film forming apparatus 1 is recorded.
When the inside of the vacuum chamber 10 is at atmospheric pressure, the door of the vacuum chamber 10 is closed, the sub-vacuum pump 11 is operated to evacuate the inside of the vacuum chamber 10, and then the operation of the main vacuum pump 12 is started. In the case where the pressure inside 10 is the operable pressure of the main vacuum pump 12, the operation of the main vacuum pump 12 is started without operating the sub vacuum pump 11.
After starting the operation of the main vacuum pump 12, the pressure in the vacuum chamber 10 is detected by the second vacuum gauge 14, and the control device 16 stores the measurement value together with the measurement time.
After the pressure measurement is performed until the main vacuum pump 12 that has performed the pressure measurement has a pressure lower than the pressure reached by the vacuum processing, a graph of the relationship between time and pressure is created from the stored measurement value and time data.

FIG. 2 shows the graph, in which the horizontal axis indicates the measurement time, the vertical axis indicates the pressure in the vacuum chamber 10, and the symbols L ₁ , L ₂ , and L ₃ indicate the time and the pressure in the vacuum chamber 10. The reference symbol L ₁ is detected by the first vacuum gauge 13 while operating the sub vacuum pump 11, and the reference symbol L ₂ is the sub vacuum pump 11 while operating the main vacuum pump 12. When detected by the first vacuum gauge 13 used during the operation, the symbol L ₃ is a curve when detected by the second vacuum gauge 14 while operating the main vacuum pump 12.
From the measurement value stored in the storage device 18 and the data of the measurement time, the calculated value is
(Calculated value) = (Difference in measurement value) / (Difference in measurement time) …… (1)
As sought. The difference between the measured values is the pressure difference.

For example, for the sake of convenience, among the measurement values stored in the storage device 18, the difference between the measurement value measured at the current time and the measurement value measured immediately before the current time is defined as a “measurement value difference”. If the difference in measurement time between the two measurements used to determine the difference between the measurement times is the difference in measurement time, the calculation is based on the measurement value at the current time or the measurement value measured one time before the current time. Values can be matched.
The volume of the vacuum chamber 10 is measured and known, and the measured exhaust speed of the main vacuum pump 12 can also be obtained by the following equation.
(Pumping speed) = (Vacuum chamber volume) x (Difference in measured value) / (Difference in measurement time) (2)

   FIG. 3 is a graph in which the horizontal axis indicates the pressure (Pa) in which the pressure unit is Pa, and the vertical axis indicates the calculated value (Pa / second) of the equation (1). Here, the average value of the two measured values is plotted in correspondence with the exhaust velocity and the value converted into the pressure (Pa), and the curve M is drawn by connecting the plots.

When the graph of FIG. 3 is observed with respect to the measured main vacuum pump 12, the pressure is lower than the ultimate pressure of the sub-vacuum pump 11 and higher than the pressure at which a vacuum processing step described later is started, and there is no sudden change in the calculated value. However, when the pressure is selected as the reference pressure and the calculated value associated with the reference pressure or the exhaust velocity obtained from the calculated value is stored in the storage device 18 as the reference value, the control device 16 sets a value smaller than the reference value. A threshold value is calculated and stored in the storage device 18.
Once the reference value is obtained, it is not necessary to create a graph to be created in order to obtain the reference value in the reference value acquisition step using another vacuum pump having the same exhaust capacity.
In order to calculate the threshold value, for example, the reduction coefficient α (0 <α <1) is stored in the storage device 18 and can be obtained by multiplying the reference value by the reduction coefficient α.
In the graph of FIG. 3, for example, the threshold value can be set to the exhaust speed when the pressure is 0.05 Pa.

The reference value for the main vacuum pump 12 as described above is preferably obtained by operating the main vacuum pump 12 and measuring the pressure immediately after the use of the main vacuum pump 12 is started.
Moreover, when maintaining the main vacuum pump 12, it is preferable to obtain | require immediately after a maintenance.
In addition, although the said calculated value uses two measured values, it is also possible to use three or more measured values.

<Inspection process, vacuum processing process>
Next, the processing object is vacuum processed using the main vacuum pump 12 used for the measurement.
Here, the main vacuum pump 12 remains connected to the vacuum chamber 10 for which the reference value has been obtained.
In the vacuum chamber 10, the substrate holder 20 is disposed at the bottom of the vacuum chamber 10 and the sputter target 21 is disposed at the ceiling even when the reference value is obtained. Yes.
The door of the vacuum chamber 10 is opened, the processing object 30 is carried into the vacuum chamber 10 and placed on the substrate holder 20.
The door of the vacuum chamber 10 is closed, first, the sub vacuum pump 11 is operated, and then the main vacuum pump 12 is operated to reduce the pressure in the vacuum chamber 10.
The pressure in the vacuum chamber 10 is detected by the first or second vacuum gauges 13 and 14, the pressure in the vacuum chamber 10 obtained from the pressure signal indicating the pressure is taken as a measured value, and the control device is determined from the measured value and the measurement time. 16 calculates a calculated value by the above equation (1) and compares the calculated value with a stored threshold value as a comparison target value.

  When the pressure in the vacuum chamber 10 is equal to or lower than the reference pressure, the comparison result between the comparison target value and the threshold value when the pressure in the vacuum chamber 10 reaches the reference pressure is that the comparison target value is equal to or higher than the threshold value. , The control device 16 determines that the exhaust characteristics are in a good state, finishes the inspection process, and maintains the vacuum exhaust in the vacuum chamber 10 (here, the sputter target 21). Sputtering) is started, and thin film formation on the processing object 30 is started.

On the other hand, the film forming apparatus 1 including the main vacuum pump 12 is used many times after the reference value is obtained, and when the reference value is obtained, the film forming apparatus 1 is deteriorated or the main vacuum pump 12 has a failure or the like. If it occurs, the calculated value is smaller than the reference value. Therefore, when the comparison result indicates that the comparison target value is smaller than the threshold value, the film forming apparatus 1 including the main vacuum pump 12 is used. Is not in good condition.
When the reduction coefficient α is large and the threshold value is close to the reference value, it is considered that the comparison target value is not greatly separated from the reference value, and an alarm is issued, but the vacuum processing is continued. Replacement or cleaning of the vacuum chamber 10 may be requested. If the threshold value is farther from the reference value than that, the main vacuum pump 12 is stopped because the main vacuum pump 12 cannot be used. Thus, the main vacuum pump 12 may be exchanged.
If an alarm is issued, the number of times of use and the time of use until the deterioration state that requires replacement from the time of the alarm can be obtained by recording the number of times of use and the time of use since the reference value for the main vacuum pump 12 was obtained. As a result, the replacement time can be predicted in advance.

  Moreover, in the said Example, although the test | inspection process of the main vacuum pump 12 was performed before the vacuum processing of the process target object 30 was started, when the process target object 30 needs to be heated before starting a vacuum process process etc. As for, the inspection process of the main vacuum pump 12 may be performed when the processing object 30 is not carried into the vacuum chamber 10 and the vacuum processing is not performed.

In the above embodiment, the same vacuum chamber 10 is used when the reference value for the main vacuum pump 12 is obtained and when the inspection is performed, but if the apparatus configuration is the same, the measurement vacuum vessel for obtaining the reference value and The vacuum chamber may be different from the vacuum chamber for inspection when performing the inspection.
In the above example, when the reference value is S, the reduction rate α times the reference value S is set as a threshold value (S × α). However, a value obtained by subtracting a small numerical value β from the reference value S is a threshold value (S × α). S-β) may also be used.

  In the above embodiment, the reference value S for the main vacuum pump 12 is obtained in advance, the inspection process for the main vacuum pump 12 is performed, and the inspection process for the sub vacuum pump 11 is not performed. In addition, a reference value for the sub vacuum pump 11 may be obtained and an inspection process for the sub vacuum pump 11 may be performed.

  When vacuum processing is performed, when the vacuum chamber 10 is evacuated from the atmospheric pressure by the sub-vacuum pump 11, a calculated value is obtained from the pressure in the vacuum chamber 10 and the measurement time, and the inspection process of the sub-vacuum pump 11 is performed. The condition of the sub vacuum pump 11 and the vacuum chamber 10 is judged as good or bad. If the condition is good, the sub vacuum pump 11 is switched to the main vacuum pump 12 to start the operation of the main vacuum pump 12, and the main vacuum pump 12 is continuously operated. An inspection process may be performed. However, the present invention includes a case where the inspection process of the sub vacuum pump 11 is performed and the inspection process of the main vacuum pump 12 is not performed when the vacuum processing is performed.

  According to the present invention, by obtaining the exhaust speed at any pressure in the exhaust, detailed analysis, pump performance, and comparison with past data become possible, and it is possible to know or predict the deterioration of the exhaust state. It becomes possible.

Also, by measuring the residual gas data and combining the measured residual gas data with the deterioration data of the exhaust speed, the cause of the cause can be identified, and proper maintenance is performed in a timely manner, thereby extending the operating time of the equipment. It is possible to shorten the apparatus maintenance time and improve the apparatus operating rate.
If the residual gas data collected at the same time as the measurement of the pumping speed data and the reference value is displayed in correspondence with the pressure value, this data indicates that the pump performance has deteriorated, the vacuum container has become dirty, the vacuum container has It can be used to determine if there is a leak.

  By mounting on a vacuum device or on a vacuum device data collection system, monitoring the evacuation status of the device, and performing the processing of the present invention, it is possible to grasp the sound state of the exhaust capacity of the device in detail numerically Therefore, appropriate maintenance is possible by comparing numerical values with data of various states of the apparatus, and the operating rate of the apparatus is improved.

DESCRIPTION OF SYMBOLS 1 ... Film-forming apparatus 10 ... Vacuum chamber 11 ... Sub vacuum pump (roughing pump)
12 ... Main vacuum pump (main pump)
13 …… First vacuum gauge 14 …… Second vacuum gauge 15 …… Clock 16 …… Control device 18 …… Storage device 19 …… Display device 20 …… Substrate holder 21 …… Sputter target 30 …… Process target object

Claims (3)

A method for determining the quality of exhaust characteristics for determining the state of a vacuum device,
When a vacuum pump to be measured is connected to a measurement vacuum chamber, the vacuum pump is operated to evacuate the measurement vacuum chamber, and the measurement vacuum chamber is evacuated to a preset reference pressure A reference value acquisition step for obtaining a reference value corresponding to the exhaust speed of
The pressure in the inspection vacuum chamber is measured when the inside of the inspection vacuum chamber to which the vacuum pump is connected is evacuated from the pressure higher than the reference pressure to the pressure lower than the reference pressure by the vacuum pump. Then, a calculated value corresponding to the exhaust speed is calculated from the measured value and the time interval at the time of measurement,
An inspection step of comparing the calculated value at the reference pressure with a threshold value that is smaller than the reference value, and judging whether the state of the vacuum pump and the inspection vacuum chamber is good or bad from the comparison result; A method for determining the quality of exhaust characteristics. When carrying out the inspection step, carry the processing object into the inspection vacuum chamber,
The pass / fail determination method according to claim 1, further comprising a vacuum processing step for performing vacuum processing on the processing object.
The vacuum processing step is a method for determining whether the exhaust characteristics are good or bad after the inspection step.   3. The exhaust quality judgment method according to claim 2, wherein the measurement vacuum chamber and the inspection vacuum chamber are the same vacuum chamber.

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