JP4546049B2 - Plasma processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus having a vacuum processing chamber, and more particularly, to a plasma processing apparatus having an automatic return function after performing maintenance that involves releasing the atmosphere of the vacuum processing apparatus such as wet cleaning.
[0002]
[Prior art]
The conventional vacuum processing apparatus automatically or semi-automatically follows a predetermined optimum sequence unique to the apparatus to complete the wet cleaning operation with opening to the atmosphere as described in Patent Document 1 and start the product processing. A pass / fail decision was made. In other words, after the wet cleaning work is completed, evacuation with a vacuum pump is started, and the leak pressure / diagnosis pressure check is performed after reaching the specified ultimate pressure in about 2 hours while diagnosing leak signs. It was. If the leak rate is NG in the leak predictive diagnosis, the retry is made without waiting for the specified pressure. If there is no problem with the leak predictive leak diagnosis and the leak check / arrival pressure check after the specified ultimate pressure is NG, retry is performed at that time. If the leak check / arrival pressure check after the specified ultimate pressure is OK, then transfer confirmation / process gas extraction without plasma and foreign matter check (pre-measurement, QC, post-measurement) are performed. If this is OK, a dummy run (discharge check) is performed. Further, a discharge foreign matter check (previous measurement, QC, post-measurement) is performed. If OK, a rate check (previous measurement, QC, post-measurement) is performed. If this is OK, the wet cleaning operation has been completed.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2003-45847
[Problems to be solved by the invention]
In the above conventional case, it is possible to determine the leak rate NG before reaching the specified ultimate pressure by performing the leak predictor diagnosis, but if there is no problem with the leak predictor diagnosis, it is necessary to wait until the specified ultimate pressure is reached as before. However, there is a problem that it takes a long time to recover, and the start-up time is the same as before. Further, due to safety problems, it has been impossible to introduce plasma discharge and process gas without plasma discharge under the circumstances where the presence or absence of leakage has not been confirmed.
[0005]
An object of the present invention is to provide a plasma processing apparatus capable of further shortening the startup time after wet cleaning when there is no leak.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a plasma processing apparatus for generating a plasma in a processing chamber to perform vacuum processing, and in order to make the processing chamber open to the atmosphere into a vacuum state, a vacuum pump is being evacuated. And a processing sequence for performing a sample etching process after performing a purge exhaust process for purging with an inert gas and a leak prediction for determining whether or not there is a leak.
[0007]
According to the present invention, in a vacuum processing apparatus using plasma having a maintenance return function after wet cleaning with air release, the maintenance return function includes a process processing function in automatic operation and a leak check function in startup, It has a mass flow controller verification function, an exhaust characteristic function, and a diaphragm gauge verification function, and a sequence for performing pass / fail determination automatically or semi-automatically. That is, the present invention adds a leak prediction function that can determine whether or not there is a leak in a low vacuum state before reaching a leak rate reference value, for example, 0.15 Pa · l / s.
[0008]
Another feature of the present invention is that, in the leak prediction, a leak rate hyperbola is obtained from three or more leak amount measurement results, and is determined to be normal if the value of the asymptote with respect to the leak rate hyperbola is within an allowable range. is there.
[0009]
Another feature of the present invention is the addition of a sample etch function for performing plasma discharge, process gas discharge, and heating in the vacuum processing chamber to promote the release of the residual gas contained in the chamber.
[0010]
Furthermore, another feature of the present invention is that a cycle purge for shortening the exhaust time and foreign matter reduction and an additional exhaust function after a high vacuum state are added.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 shows a processing sequence after wet cleaning with air release of a plasma processing apparatus according to an embodiment of the present invention. According to this embodiment, as will be described in detail later, a series of operations proceeds to the next item while performing pass / fail determination automatically or semi-automatically. In the case of NG in the leak prediction (S4) and the start-up process (S8), an abnormality notification (S10) is performed.
[0012]
FIG. 2 is an overall structural diagram of a vacuum apparatus for plasma etching as an application target of an embodiment of the present invention. The vacuum processing apparatus 11 includes a vacuum processing chamber 12, an etching gas supply device 14 for generating plasma, an exhaust device 18 using a vacuum pump, a high-frequency power source 13 for generating plasma 15, and a sample to be processed in the vacuum processing chamber. A sample stage 16 for mounting 17 is provided. Further, a high frequency power source 19 is connected to the sample stage 16 in order to accelerate ions incident on the sample 17. The vacuum processing apparatus 11 also includes a controller (not shown) for executing a plasma etching process and a cleaning process according to a predetermined sequence. This controller performs a purge exhaust process for purging with an inert gas during evacuation by a vacuum pump and a leak prediction for determining the presence or absence of a leak in order to put the processing chamber opened to the atmosphere into a vacuum state. It has a program and data capable of executing a processing sequence for performing a sample etching process later. The controller also has a display device having an input operation function.
[0013]
FIG. 3 shows an example of the operation screen of the display device of FIG. This example of the operation screen corresponds to the series of sequences shown in FIG. 1, and a series of sequences is executed by pressing the start button 110 on the operation screen. Here, there are etching chambers 1 and 2 and ashing chambers 1 and 2 as the vacuum processing apparatus 11 to be operated, and each vacuum processing apparatus is configured to perform a predetermined operation via an operation screen. .
[0014]
Next, the operation after the wet cleaning of the vacuum processing apparatus according to the present embodiment will be described with reference to FIGS.
[0015]
Upon completion of the wet cleaning operation for members constituting the vacuum processing chamber by opening the vacuum processing chamber to the atmosphere, the operator activates a shortened startup button from a menu screen (not shown) of the display device.
[0016]
FIG. 3 is an example of the operation screen display when the shortened startup button is activated, and a series of startup time reduction sequences will be described based on this. First, evacuation by a vacuum pump is started by setting and starting up a startup time reduction sequence item (S1, S2 in FIG. 1). Considering the pressure resistance of the components in the vacuum processing chamber, slow exhaust is performed, for example, up to 1 kPa. When the exhaust pressure is lower than that, the exhaust line is switched, the slow exhaust is stopped, and rough exhaust is started.
[0017]
Next, in addition to the conventional roughing exhaust, a purge exhaust sequence 101 is executed (S3). For example, when the pressure is 100 Pa or less, rough evacuation is continued while simultaneously purging with an inert gas such as nitrogen at a preset number of times and time. After completion of the specified time, the inert gas purge is stopped and the rough exhaust is continued. This has the effect of shortening the exhaust time and reducing foreign matter by replacing residual components such as moisture adhering to the vacuum processing chamber wall with an inert gas and exhausting it, and it is effective to implement it before leak prediction. .
[0018]
Next, as the leak prediction 102 (S4 in FIG. 1), it is possible to determine whether there is a leak at an early stage by repeatedly measuring the leak rate in a low vacuum state of 10 Pa or less, for example. As a determination method, it is not determined to be normal if the determination standard having a width of several steps used in the conventional leak predictor diagnosis is satisfied, but the leakage amount measurement results (start pressure, end pressure, The function expression of the hyperbola is obtained from the leak measurement time), and if the value of the asymptote for the hyperbola is within the allowable range, it is regarded as normal and the process proceeds to the next process.
[0019]
FIG. 4 shows a leak prediction diagnosis determination example, and shows a normal case (A) and a leak case (B).
[0020]
In the leak prediction diagnosis, a hyperbola is predicted from the measurement results of at least three points according to the general formula of hyperbola Y = k / (Xp) + q, and the value of q is obtained. If the value of q is within the hatched range in FIG. 4 obtained from the experience value, it is determined that the value is normal. If the value of q is larger than the leak rate reference value, for example, 0.15 Pa · l / s, it is predicted that an abnormality will occur even if evacuation is continued as it is. Notification (S10 in FIG. 1) can be performed.
[0021]
Next, the process (S5) of the additional exhaust 103 will be described. In the additional exhaust 103, for example, a further exhaust time after a high vacuum state of 0.05 Pa, which is a predetermined value, can be set. Thereby, the optimal ultimate pressure according to various processes can be selected suitably.
[0022]
Next, after completion of the set exhaust time, the sample etch 104 for reducing the residual gas content in the vacuum processing chamber is started (S6). The sample etch 104 is, for example, a function of heating the vacuum processing chamber by plasma heat input by performing plasma discharge under the same recipe conditions as when performing product processing, or of the vacuum processing chamber. For example, a function of accelerating degassing of the residual gas attached to the wall of the vacuum processing chamber by heating to, for example, room temperature or higher, preferably 80 ° C. to 100 ° C. by a heater or a lamp (not shown), or a vacuum processing chamber In addition, it refers to the function of introducing gas without generating plasma under a certain pressure. Also, a combination of the above may be used. In the MFC (mass flow controller) test 107 to be performed later, when the test is performed in a state where the wall of the vacuum processing chamber is heated, it is desirable to heat it here.
[0023]
Next, by implementing the additional exhaust 105 (S7) which is the same function as the additional exhaust 103, it is possible to cope with various processes.
[0024]
Subsequently, as a start-up process (S8), a leak check 106 for checking the degree of vacuum and leak, an MFC test 107 for verifying a mass flow controller from a gas flow that is actually flowing with respect to a predetermined gas flow rate, and measuring exhaust characteristics A DG (diaphragm gauge) test 109 for testing the VV characteristic 108 and the zero point of the diaphragm gauge is selected and executed as necessary. If the result of these automatic measurements is normal, the start-up operation after wet cleaning is completed (S9).
[0025]
As described above, according to the embodiment of the present invention, the maintenance return function after the wet cleaning in the conventional vacuum processing apparatus, the function of pre-determining whether there is a leak until reaching the specified ultimate pressure, the chamber before and after the leak prediction diagnosis By adding an exhaust sequence such as a cycle purge and a function for promoting the release of the residual gas contained therein, the apparatus can be returned in a short time while performing a pass / fail determination automatically or semi-automatically. Thereby, the maintenance return method of the plasma processing apparatus which can further shorten the recovery time can be provided.
[0026]
The present invention can also be applied to cases other than the maintenance described in the embodiment as a process for bringing the processing chamber opened to the atmosphere into a vacuum state.
[0027]
The plasma processing apparatus of the present invention also has the following characteristics.
(1) In a vacuum processing apparatus using plasma that has a maintenance return function after wet cleaning with air release, the maintenance return function includes a process processing function in automatic operation, a leak check function in startup, and a mass flow controller verification. It has a function to perform pass / fail judgment automatically or semi-automatically, having a function, an exhaust characteristic function, and a diaphragm gauge verification function.
(2) The above sequence has a function of performing cycle purge during roughing exhaust.
(3) In the above (1), it has a function of determining the presence or absence of leak in a short time by repeatedly measuring the leak rate in a low vacuum state.
(4) In (3) above, a predetermined number of times the leak rate is measured from the initial pressure, end pressure, and measurement time, a hyperbolic function expression is obtained from the leak rate, and the value of the asymptote for the hyperbola is allowed Leak is determined by being within the range.
(5) In the above (1), it has a function of starting a temperature adjustment relationship of the vacuum processing chamber inner wall after predicting a leak, or executing a plasma discharge or a process gas discharge process.
[0028]
【The invention's effect】
As described above, according to the present invention, it is possible to predict whether or not a prior leak has passed without reaching the ultimate pressure by leak prediction using an asymptote. In addition, it is possible to accelerate degassing by adding purge exhaust and sample etch functions, and the start-up time after wet work can be greatly shortened. Further, by setting a series of complicated operations in advance, it is possible to realize labor saving of labor until the operation time.
[Brief description of the drawings]
FIG. 1 is a processing sequence flow diagram after wet cleaning according to an embodiment of the present invention.
FIG. 2 is a diagram showing an overall configuration of a vacuum processing apparatus as an application target of an embodiment of the present invention.
FIG. 3 is a diagram illustrating an example of an operation screen display.
FIG. 4 is a diagram illustrating an example of leak predictor diagnosis;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Vacuum processing apparatus 12 ... Processing chamber 13 ... High frequency power supply 14 ... Etching gas supply apparatus 15 ... Plasma 16 ... Sample stand 17 ... Sample 18 ... Vacuum exhaust apparatus.

Claims (3)

Plasma processing method Oite processing to generate plasma in chamber by the plasma processing apparatus for performing a vacuum process,
When starting up after wet cleaning,
In order to make the processing chamber opened to the atmosphere a vacuum state, a vacuum exhaust process is performed by performing a vacuum process by a vacuum pump and a purge by an inert gas at the same time while performing the vacuum process ,
After the purge exhaust process, a leak prediction process is performed to determine whether there is a leak in a low vacuum state before reaching the leak rate reference value ,
After the leak prediction process , perform a sample etch process to reduce the residual gas content in the processing chamber ,
The plasma processing method characterized in that after the sample etch process, to check the ultimate vacuum degree or leak. The plasma processing method according to claim 1,
In the leak prediction processing, a plasma processing method is characterized in that a leak rate hyperbola is obtained from three or more leak amount measurement results, and is determined to be normal if the value of an asymptote with respect to the leak rate hyperbola is within an allowable range. The plasma processing method according to claim 1,
The sample etch process, a plasma process wherein the plasma discharge treatment, or treatment heat treatment chamber wall, or is one of the process for introducing a gas without making a plasma.

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