JP2012222226A - Plasma processing apparatus and operation method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing apparatus and its operation method which reduce non-operating time of the plasma processing apparatus and can improve processing efficiency by further properly setting the timing of processing for removing deposits attached to a plasma processing chamber.SOLUTION: The plasma processing apparatus provides a wafer in the processing chamber arranged inside a vacuum vessel and forms plasma in the processing chamber to perform plasma processing. The operation method of the plasma processing apparatus comprises a mode for cleaning operation in which the deposit on the wall of inside the processing chamber is removed by forming plasma in the processing chamber with a predetermined interval, and the mode for cleaning is terminated when a deposition amount due to cleaning with plasma, which is detected in the cleaning mode, and a leak amount in the processing chamber after cleaning with plasma are not more than predetermined values respectively.

Description

  The present invention relates to a plasma processing apparatus that forms plasma in a processing chamber inside a vacuum vessel and processes a substrate-like sample such as a semiconductor wafer disposed in the processing chamber, and an operating method thereof.

  In the plasma processing apparatus as described above, a plurality of wafers are continuously processed one by one. As the number of wafers to be processed increases, reaction products accumulate on the wall surface inside the processing chamber, and affect the product wafer differently. In order to prevent the occurrence of product defects, it has been conventionally performed to clean the inside of the processing chamber at predetermined intervals.

  Patent Document 1 is known as an example of such a conventional technique. Patent Document 1 corresponds to the intensity and amount of the reaction and plasma generated in the container, the amount and type of the product, etc., and by detecting the intensity of the spectrum of these wavelengths (light intensity), Determining the status of the device is disclosed.

Japanese Patent Laid-Open No. 2004-47628

  The prior art described above has a problem because the following points are not sufficiently considered. The invention of Patent Document 1 detects the amount of adhering matter from light emission, but a device for making the detected result useful for improving the efficiency of the operation of the plasma processing apparatus has not been sufficiently studied.

  An object of the present invention is to provide a method for operating a plasma processing apparatus that reduces the non-operation time of the processing apparatus and improves the processing efficiency by making the processing timing for removing deposits in the processing chamber more appropriate. There is to do.

  The operating method of the plasma processing apparatus of the present invention is an operating method of a plasma processing apparatus in which a wafer is placed in a processing chamber disposed inside a vacuum vessel, and plasma is formed in the processing chamber to perform processing. A cleaning mode for performing a cleaning operation for forming plasma in the processing chamber at a predetermined interval and removing deposits on the wall on the processing chamber side, and during cleaning using the plasma detected in this mode The cleaning mode is terminated when each of the amount of deposits and the leakage amount of the processing chamber after cleaning using the plasma is equal to or less than a predetermined value.

  ADVANTAGE OF THE INVENTION According to this invention, the non-operation time of a plasma processing apparatus can be reduced and the efficiency of a process can be improved.

FIG. 1 is a cross-sectional view schematically showing a schematic configuration of a plasma processing apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing a production management HOST computer connected to the apparatus of FIG. 1 via a network such as a LAN. FIG. 3 is a conventional specification of a flowchart showing a flow of operation of the plasma processing apparatus according to the embodiment shown in FIG. FIG. 4 is a flowchart that realizes labor saving of work involving humans by reviewing the manual work process between the etching processes according to the embodiment of the present invention and making it automatic / semi-automatic. FIG. 5 is a time chart showing changes with time of the flow of operation of the plasma processing apparatus according to the embodiment of the present invention. FIG. 6 is a time chart showing the work of resetting the number of times of plasma cleaning and performing the etching process if the leak rate is within a predetermined value after the leak check of the plasma processing apparatus according to the embodiment of the present invention. . FIG. 7 is a time chart showing the operation of repeating the process of performing the next etching process after removing the deposits attached to the process chamber by performing the plasma cleaning of the plasma processing apparatus according to the embodiment of the present invention. It is.

  Embodiments will be described below with reference to the accompanying drawings.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view schematically showing a schematic configuration of a plasma processing apparatus according to an embodiment of the present invention. In particular, in this embodiment, an etching apparatus using microwave ECR (Electron Cyclotron Resonance) is described.

  The plasma etching apparatus 100 includes a processing chamber (vacuum vessel), a sample stage 113 for installing a sample to be processed in the vacuum processing chamber, and an exhaust means for discharging gas in the processing chamber.

  When a wafer to be processed is placed on the sample stage 113 in the processing chamber, microwaves are introduced into the vacuum processing chamber from a plasma generating high frequency power source 101 that is a microwave power source. A solenoid coil 107 is installed around the vacuum processing chamber, and electron cyclotron resonance (ECR) is caused by a magnetic field generated therefrom and incident microwaves. As a result, the process gas is efficiently converted into plasma in the vacuum processing chamber. The process gas from the gas supply system 112 is supplied into the vacuum processing chamber via a mass flow controller 111 that controls the flow rate to be constant.

  A high frequency power supply 114 for bias is connected to the lower part of the sample stage 113. By applying high-frequency power from the bias high-frequency power source 114, ions are attracted from the plasma 102 to the wafer, and ions incident on the sample are accelerated.

  The treated gas is exhausted by a dry pump and a turbo molecular pump which are the exhaust system vacuum pump 110. At this time, the pressure in the vacuum processing chamber is controlled to be constant by the pressure gauge 108 by adjusting the opening of the variable conductance valve 109 in the middle of exhaust.

  An observation window 103 for measuring the inside state of the processing chamber is provided on the side wall of the processing chamber. Plasma 102 that emits light in the vacuum processing chamber is transmitted to an emission spectrometer 105 through an optical fiber 104 attached to the observation window 103. OES (OES: Optical Emission Spectroscopy) analysis is performed from the emission spectrometer 105, and the emission of the plasma 102 is split into each wavelength. The emission intensity (spectral spectrum) of each spectrum is transferred to the control device 115 via the interface 106 at every sampling period of the emission spectrometer 105. By detecting the spectral intensity of each wavelength of emitted light, a relative change with time is confirmed.

  The control device 115 includes an arithmetic unit, an input device, and a storage device. The computing unit computes processing conditions for processing, operating conditions of the apparatus, etc., gives commands to each component, and adjusts the operation of the apparatus. The input device is a device for inputting instructions to a computing unit such as a mouse or a keyboard. The storage device stores a plurality of recipes to be processed, device parameters, and the like.

  The values gathered in the control controller from each unit are notified to the operator by the screen display device 116 which is a display, the lighting signal 117, the alarm 118, and the HOST computer 120. A HOST computer 120 is shown in FIG. The host computer 120 for production management connected to the apparatus of FIG. 1 via a network 119 such as a LAN can be operated from a remote location.

  Next, the operation of the plasma processing apparatus in the present embodiment will be described in more detail. 3 and 4 are flowcharts showing the flow of operation of the plasma processing apparatus according to the embodiment shown in FIG.

  FIG. 3 is a conventional specification of a flowchart showing a flow of operation of the plasma processing apparatus. In step 201, a leak check time is set. The leak check is to stop the exhaust in the processing chamber and measure the pressure increase difference per unit time. A value obtained by the leak check is called a leak rate. The leak rate is the sum of the gas generated from the deposits in the processing chamber (outgas flow rate) and the leak flow rate from the atmosphere.

  In step 202, an etching process is performed. When the leak check setting time is reached, in step 203, the leak check is automatically started. If there is a lot being processed at the leak check setting time, after the lot being processed is finished, the processing is temporarily stopped and a leak check is performed.

  In step 204, the leak rate, which is a value obtained from the leak check, is compared with a predetermined value. If the leak rate is within the predetermined value (Y), it is determined that the apparatus is in a normal state. In step 205, the etching process is performed. To implement. On the other hand, if the leak rate is outside the predetermined value (N) in step 204, the etching process is not activated, and the leak rate result is reported to the user using the screen display device 116 or the HOST computer 120 in step 206.

  The time chart of FIG. 3 is shown in FIG. If the leak rate is outside the predetermined value (N) in step 204, all the operations up to the next etching process are conventionally performed manually.

  In the present invention, the manual work process between the etching processes is reviewed and automatic / semi-automatic is realized, thereby realizing labor saving of work involving humans. This is shown in FIG.

  In FIG. 4, the operations from setting the leak check time in step 207 to comparing the leak rate in step 210 with a predetermined value are the same as those in step 201 to step 204 in FIG. 3.

  In step 210, the leak rate is compared with a predetermined value. If the leak rate is outside the predetermined value (N), the etching process is not performed, and in step 212, the plasma cleaning frequency is incremented by +1. In step 213, the plasma cleaning recipe is added. Set.

Plasma cleaning is a method of removing deposits adhering to the processing chamber by plasma emission. Deposits adhering to the processing chamber can be estimated from the following two points.
(1) Processed etching recipe (2) Results of OES analysis performed from emission spectrometer 105 performed simultaneously with the etching process in step 208

  When the type of deposit adhering to the processing chamber is determined, a cleaning gas for removing the deposit is determined according to the type of deposit. In the plasma cleaning recipe, items other than gas are determined based on actual measurement values. In addition, the implemented results are stored in the storage device for reference after the plasma cleaning setting.

  The plasma cleaning processing time is within a predetermined time. If the plasma cleaning process time is outside the predetermined time, other values in the recipe are adjusted.

  In step 214, the selected plasma cleaning recipe is executed. At this time, OES analysis by the emission spectrometer 105 is activated. After the plasma cleaning is completed, the deposit amount is compared with a predetermined value in step 215. If the deposit amount is within the predetermined value (Y), a leak check is performed in step 216.

  After the leak check, in step 217, the leak rate is compared with a predetermined value. If the leak rate is within the predetermined value (Y), the number of plasma cleaning executions is reset in step 218, and the process proceeds to step 211 to perform the etching process. carry out. FIG. 6 shows the above work in a time chart.

  In step 215 of the flowchart of FIG. 4, if the amount of deposit is not within the predetermined value (N), in step 219, the number of executions of plasma cleaning (predetermined value ≧ 2) is confirmed. If it is within the predetermined number of times (N), the process proceeds to step 212 where the plasma cleaning execution count is incremented by one, a plasma cleaning recipe is set in step 213, and a plasma cleaning process is executed in step 214.

  However, even if the above operations (step 212 to step 214) are repeated, if the deposit is not within the predetermined value in step 215 and the number of times of plasma cleaning exceeds the predetermined value in step 219 (Y) , WET cleaning is performed to remove deposits in the processing chamber.

  WET cleaning is performed manually by the following procedure. After returning the vacuum processing chamber of the apparatus to atmospheric pressure with an inert gas such as nitrogen, the processing chamber is opened, wiped with water or a volatile chemical solution, and the internal parts are replaced. In this way, the vacuum processing chamber is opened to the atmosphere, and every corner inside the apparatus is cleaned. It takes several hours to perform the WET cleaning.

  If it is necessary to carry out the WET cleaning, in step 220, the WET cleaning is notified. The notification method is a screen display device 116, a lighting signal 117, and an alarm 118.

  In that case, the throughput decreases as the number of plasma cleaning operations is increased. Therefore, it is necessary to stop the plasma cleaning process at an appropriate number of times. Therefore, in step 212, the number of plasma cleaning processes is incremented by +1, and in step 219, the number of plasma cleanings is limited.

  Also, in step 215, if the amount of deposit is within a predetermined value (Y), but the leak rate is not a predetermined value (N) in step 217, the notification of WET cleaning is performed in step 220.

  In the above case, it can be seen that deposits adhere to the lower part of the sample stage 113 in the processing chamber. This is for the following reason. Since the upper part of the sample stage 113 is in contact with the plasma 102 in the processing chamber, the deposits attached to the upper part of the sample stage 113 in the processing chamber can be removed by plasma cleaning. However, since the lower part of the sample stage 113 is not in contact with the plasma 102 in the processing chamber, deposits attached to the lower part of the sample stage 113 cannot be removed by plasma cleaning.

  After the WET cleaning notification, the operator can execute a process other than the WET cleaning. However, the WET cleaning is periodically notified until the WET cleaning is executed, and the warning is continued.

  After the etching process, a leak check is performed. If the leak rate is outside a predetermined value, the plasma adhering is performed to remove deposits attached to the processing chamber, and the next etching process is performed. FIG. 7 shows a time chart in which these processes are repeated.

  As shown in FIG. 7, the time T outside the etching process increases with the number of etching processes. This is because, as the etching process is repeated, the amount of deposits attached to the process chamber increases, so that the necessary plasma cleaning process time becomes longer.

  Therefore, in the present invention, the frequency of the leak check is automatically adjusted according to the leak rate. If the leak rate is good, reduce the frequency of leak checks as much as possible. If the leak rate is not good, the frequency of leak check is increased. This increases the safety of the device.

DESCRIPTION OF SYMBOLS 100 Plasma etching apparatus 101 Plasma generating high frequency power supply 102 Plasma 103 Observation window 104 Optical fiber 105 Luminescence spectrometer 106 Interface 107 Solenoid coil 108 Pressure gauge 109 Variable conductance valve 110 Exhaust system vacuum pump 111 Mass flow controller 112 Gas supply system 113 Sample stand 114 Bias High-frequency power supply 115 Control device 116 Screen display device 117 Lighting signal 118 Alarm 119 Network 120 HOST computer

Claims (12)

An operation method of a plasma processing apparatus for processing a wafer by forming a plasma in a processing chamber disposed inside a vacuum vessel and forming a plasma in the processing chamber,
A cleaning mode for performing a cleaning operation of forming plasma in the processing chamber at a predetermined interval to remove deposits on the wall surface on the processing chamber side;
When the amount of deposits at the time of cleaning using the plasma detected in the cleaning mode and the amount of leakage in the processing chamber after cleaning using the plasma are equal to or less than a predetermined value, A method of operating a plasma processing apparatus, wherein the mode is terminated. An operation method of the plasma processing apparatus according to claim 1,
The plasma processing is characterized in that the length of the interval of the operation of the cleaning mode or the detection of the leakage amount of the processing chamber is adjusted according to the detected value of the leakage amount of the processing chamber. How to operate the device. An operation method of the plasma processing apparatus according to claim 1 or 2,
The cleaning of the processing chamber using plasma is performed again when it is determined that the amount of deposits at the time of cleaning using the plasma detected in the cleaning mode is larger than the predetermined value. Of operating a plasma processing apparatus. An operation method of the plasma processing apparatus according to claim 1 or 2,
When the amount of deposits at the time of cleaning using the plasma detected in the cleaning mode is equal to or less than the predetermined value and the amount of leakage after cleaning using the plasma is larger than the predetermined value again A method of operating a plasma processing apparatus, wherein the processing chamber is cleaned using plasma. An operation method of the plasma processing apparatus according to claim 3,
When it is determined that the amount of deposits during cleaning using the plasma in the cleaning mode is greater than the predetermined value, the number of cleanings using the plasma after the start of the mode exceeds a predetermined value. A method for operating a plasma processing apparatus, characterized in that, when it is determined that it is determined, the result of the determination or the necessity of WET cleaning is notified. An operation method of the plasma processing apparatus according to claim 4,
This is when the amount of deposits during cleaning using the plasma detected in the cleaning mode is less than or equal to the predetermined value and the amount of leakage after cleaning using the plasma is greater than a predetermined value. A method of operating a plasma processing apparatus, characterized in that if it is determined that the number of cleanings using plasma after the start of a mode exceeds a predetermined value, the result of the determination or the need for WET cleaning is notified. A wafer is placed in a processing chamber disposed inside the vacuum vessel, plasma is formed in the processing chamber and processed, plasma is formed in the processing chamber at a predetermined interval, and the wall on the processing chamber side is formed. In a plasma processing apparatus having a cleaning mode for performing a cleaning operation to remove deposits,
When the amount of deposits at the time of cleaning using the plasma detected in the cleaning mode and the amount of leakage in the processing chamber after cleaning using the plasma are equal to or less than a predetermined value, A plasma processing apparatus comprising a control unit for terminating the mode. The plasma processing apparatus according to claim 7, wherein
The controller is configured to adjust and set the length of the cleaning mode operation or the processing chamber leakage amount detection according to the detected value of the processing chamber leakage amount. A plasma processing apparatus. The plasma processing apparatus according to claim 7 or 8,
The control unit cleans the processing chamber using plasma again when it is determined that the amount of deposits during cleaning using the plasma detected in the cleaning mode is greater than the predetermined value. A plasma processing apparatus is provided. The plasma processing apparatus according to claim 7 or 8,
The controller is configured such that the amount of deposits at the time of cleaning using the plasma detected in the cleaning mode is equal to or less than the predetermined value, and the amount of leak after cleaning using the plasma is less than the predetermined value. In the plasma processing apparatus, cleaning of the processing chamber using plasma is performed again in the case where the size is larger. The plasma processing apparatus according to claim 9, wherein
When the controller determines that the amount of deposits during cleaning using the plasma in the cleaning mode is greater than the predetermined value, the number of cleanings using the plasma after the start of this mode is increased. A plasma processing apparatus, wherein when it is determined that the predetermined value is exceeded, the result of the determination or the necessity of WET cleaning is notified. The plasma processing apparatus according to claim 10, wherein
The controller is configured such that the amount of deposits at the time of cleaning using the plasma detected in the cleaning mode is equal to or less than the predetermined value, and the amount of leak after cleaning using the plasma is less than the predetermined value. If it is determined that the number of cleanings using plasma after the start of this mode exceeds a predetermined value in the case of a large value, the result of the determination or the necessity of WET cleaning is notified. apparatus.

Images