JPH06232089A - Detecting method for abnormal discharge and plasma device - Google Patents

Abstract

PURPOSE:To detect presence or absence of abnormal discharge which is generated in a treatment chamber of a plasma device and its generation part. CONSTITUTION:The device for treating a semiconductor wafer W which is placed at an electrostatic chuck 21 by generating plasma in a treatment chamber 1 by a high-frequency power supply 8 is provided with a current monitor 77 for detecting DC voltage for operating the electrostatic chuck 21 and a VDC monitor 74 for detecting the VDC level from a power supply line 11 of the high- frequency power supply 8. The monitor signal from each monitor is compared and processed by a detection device 75, thus detecting presence or absence of abnormal discharge and its generation part according to comparison processing by a detection device 75 even if the fluctuation width etc. of each monitor signal differs depending on the generation part of abnormal discharge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormal discharge detection method for detecting an abnormal discharge in a processing chamber of a plasma apparatus, and a plasma apparatus having a function of implementing such a detection method.

[0002]

2. Description of the Related Art For example, when plasma is generated in a processing chamber by high-frequency power and a semiconductor wafer mounted on a mounting table in the processing chamber is subjected to plasma processing such as etching processing, when abnormal discharge occurs in the processing chamber, Not only the semiconductor wafer but also various devices and members in the processing chamber may be damaged. In such a case, it is necessary to identify the site where the abnormal discharge has occurred, and immediately take subsequent countermeasures and measures such as parts replacement and repair.

In this respect, conventionally, an abnormal discharge generated in the processing chamber is generally detected by measuring the negative potential V _DC biased to the power supply electrode side when a high frequency voltage is applied. This will be described based on the RIE type plasma processing apparatus shown in FIG. 2. In this type of plasma processing apparatus 101, an upper electrode 103 and a lower electrode 104 are provided above and below in a processing chamber 102, respectively, and a high frequency wave is provided separately. High frequency power from the power supply 105 is applied to the lower electrode 104 via the matching circuit 113 and the blocking capacitor 106 to generate plasma between the upper electrode 103 and the lower electrode 104, and the plasma is provided on the upper surface of the lower electrode 104. Plasma processing is performed on the semiconductor wafer 108 on the electrostatic chuck 107.

Then, an appropriate lead wire 110 is connected to the power supply line 109 between the lower electrode 104 and the blocking capacitor 106 outside the processing chamber 102, and this lead wire 110 is connected to the V _DC through the RF filter 111. connect the monitor 112, the V _DC, which is monitored by the V _DC monitor 112 monitors.

[0005]

However, V biased to the lower electrode 104 side by the method as described above is used.
_When only _DC is measured, it can be inferred to some extent that there is an abnormal discharge in the processing chamber 102 based on the fluctuation of the _VDC level, but it is surely due to the abnormal discharge generated inside the processing chamber 102. It cannot be determined whether or not. For example, an abnormality may occur in the power supply system of the high frequency power supply 105. Moreover, even if an abnormal discharge occurs, it is not possible to know at which part or place in the processing chamber 102 the abnormal discharge has occurred.

The present invention has been made in view of the above points. For example, when an abnormal discharge occurs in the processing chambers of various plasma processing apparatuses such as the plasma processing apparatus as described above, the abnormal discharge is generated. It is possible to solve the above-mentioned problems by providing an abnormal discharge detection method that can identify not only the presence or absence of the occurrence but also the occurrence location from the outside of the processing chamber, and a plasma processing apparatus having a function of implementing such a detection method. It is intended.

[0007]

In order to achieve the above object, in the invention of claim 1, a high frequency power from a high frequency power source is applied to an electrode in the processing chamber to generate plasma in the processing chamber, and the plasma is provided in the processing chamber. In a plasma apparatus for processing an object placed on an electrostatic chuck, the current level of the electrostatic chuck operating current is appropriately compared with the _VDC level monitored from the supply line of the high frequency power source. The purpose is to identify the presence or absence of abnormal discharge that has occurred in the processing chamber and the location where it has occurred.

According to a second aspect of the present invention, there is provided a plasma device having a function for carrying out the above-mentioned abnormal discharge detection method, wherein high frequency power from a high frequency power source is applied to electrodes in the processing chamber to generate plasma in the processing chamber. In an apparatus for processing an object placed on an electrostatic chuck provided in the processing chamber, a monitor for detecting the current level of the electrostatic chuck operating current and a V characterized by providing a V _DC monitor for detecting a _DC level which is a circuit configuration.

[0009]

When an abnormal discharge occurs in the processing chamber, the current level for operating the electrostatic chuck and the _VDC level monitored from the supply line of the high frequency power supply have a difference or a variation width depending on the place where the abnormal discharge occurs. Occurs. Therefore, by appropriately comparing each of these currents and the _VDC level at that time, it is possible to detect the occurrence of the discharge and the place where the discharge has occurred.

According to another aspect of the plasma apparatus of the present invention, the fluctuation of each level is detected by the monitor for detecting the current level of the electrostatic chuck operating current and the _VDC monitor for detecting the _VDC level from the supply line of the high frequency power source. Therefore, while monitoring the electrostatic chuck system, the high frequency power / plasma system, and further processing their fluctuations by, for example, an appropriate comparison processing device, the presence or absence of an abnormal discharge that has occurred in the processing chamber and the location where the abnormal discharge has occurred. Can be specified.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. This embodiment is an example configured as an etching processing apparatus, and FIG. 1 schematically shows a cross section of a side surface thereof, such as aluminum. A susceptor support 3 is provided at the bottom of the processing chamber 1 which is a grounded airtight container made of the above material through an insulating plate 2 made of ceramic or the like. A cooling chamber 4 such as a cooling jacket is formed inside the susceptor support 3. The cooling chamber 4 is introduced into the cooling chamber 4 through a refrigerant introducing pipe 5 provided at the bottom of the processing chamber 1. The cooling refrigerant discharged from the discharge pipe 6 is circulated.

A susceptor 7 made of a material such as aluminum and constituting a lower electrode is detachably provided on the upper surface of the susceptor support base 3. The susceptor 7 has a high-frequency power source provided outside the processing chamber 1. For example, the frequency from 8 is 1
High frequency power of 3.56 MHz is supplied by the power supply line 11 via the matching circuit 9 and the blocking capacitor 10.

On the upper surface of the susceptor 7, there is provided an electrostatic chuck 21 having the same size as the semiconductor wafer W on which the semiconductor wafer W, which is an object to be processed, is directly placed and suction-held. The electrostatic chuck 21 has a structure in which a conductive layer 22 made of, for example, an electric field foil copper is sandwiched between upper and lower sides with an insulator such as a polyimide film or the like, and is bonded to the outside of the processing chamber 1 via a supply lead wire 23. When a DC voltage is applied to the conductive layer 22 by the high-voltage DC power supply 24, the semiconductor wafer W is moved to the electrostatic chuck 2 by Coulomb force.
1 is suction-held.

The bottom of the processing chamber 1, the insulating plate 2, the upper susceptor support 3, the susceptor 7, and the electrostatic chuck 21 have through holes 31 and 32 penetrating them vertically. Each through hole 31, 3 is drilled
The pusher pins 33 and 34 for transporting the semiconductor wafer W are inserted into the inside of the device 2 so as to be inserted therethrough.

The lower end portions of the pusher pins 33 and 34 are fixed to the support portions 36 and 36 of the vertical movement plate 35 outside the processing chamber 1, and the vertical movement plate 3 is provided.
5 is configured to be vertically movable by a drive mechanism 37 such as a pulse motor. Therefore, when the drive mechanism 37 is operated to move the vertical movement plate 35 up and down, the pusher pins 33,
34 rises and falls, and their respective upper end surfaces project from the upper surface (mounting surface) of the electrostatic chuck 21 or are housed in the electrostatic chuck 21. The semiconductor wafer W to be processed is, in that state, a transfer arm (not shown) provided separately.
Is placed on the upper end surface of each pusher pin 33, 34 or transported from the upper end surface.

Between the support portions 36, 36 of the vertical movement plate 35 and the outer surface of the bottom of the processing chamber 1,
Bellows 38, 38 are provided respectively, and the respective bellows 38, 38 enable the pusher pins 33,
The through holes 31 and 32, which serve as the vertical movement path of 34, have an airtight structure with respect to the atmosphere.

The through holes 31 and 32 communicate with the gas introduction pipe 39 introduced from the outside of the processing chamber 1 into the susceptor support base 3 and the susceptor 7, and a separately provided gas supply device (not shown). ), For example, He gas is supplied into the gas introduction pipe 39, the cold heat of the susceptor support 3 which has been brought to a predetermined temperature by the above-mentioned cooling refrigerant is thermally conducted to the He gas. Each of the through holes 31 and 32 is filled with the He gas thus cooled, so that the semiconductor wafer W mounted on the electrostatic chuck 21 is cooled to a predetermined temperature.

An annular focus ring 41 having an insulating property is provided around the upper edge of the susceptor 7 so as to surround the semiconductor wafer W, and the reactive ions generated when plasma is generated are the focus ring 41. Due to the existence of the above, it is effectively incident on the semiconductor wafer W.

On the other hand, in the upper part of the processing chamber 1, the upper electrode 51, which is arranged electrically insulated from the processing chamber 1, has a hollow structure made of Al, and has a ground wire 5
The upper electrode 51, which is grounded through 2, has a surface 51a facing the susceptor 7 made of a material such as amorphous carbon or silicon. A large number of ejection openings 53 are formed in the upper surface 51a of the upper electrode 51 facing the semiconductor wafer W, and the gas introduction opening 5 provided above the upper electrode 51.
The processing gas supplied from No. 4 is discharged toward the semiconductor wafer W from these many discharge ports 53.

Further, an exhaust pipe 61 leading to a vacuum pump (not shown) for exhausting gas in the processing chamber is connected to the bottom of the processing chamber 1 so that the inside of the processing chamber 1 can be evacuated. Thus, for example, the inside of the processing chamber 1 can be maintained at 0.5 Torr.

The structure for detecting abnormal discharge in this embodiment is as follows. That is, the lead wire 71 is drawn out from the power supply wire 11 of the high frequency power source 8, the monitor lead wire 72 is connected to the lead wire 71, and the RF filter 7 is connected to the monitor lead wire 72.
A V _DC monitor 74 is connected via the switch 3, and the output of the V _DC monitor 74 is constantly introduced into the detection device 75.

On the other hand, in order to operate the electrostatic chuck 21, a monitor lead wire 76 is also drawn out from the supply lead wire 23 of the high voltage DC power supply 24, and a current monitor 77 is connected to the monitor lead wire 76. The output of the current monitor 77 is constantly introduced into the detection device 75.

The detection device 75 is configured to compare the outputs from the _VDC monitor 74 and the current monitor 77 as will be described later, and display the result on a separate display 78.

The display 78 is usually provided in a plasma processing apparatus such as this type of etching processing apparatus so that the process currently in progress can be visually recognized. Normal signal output as a result of the comparison process in He, He gas warning signal,
Necessary display is performed in response to the input of the electrostatic chuck system warning signal and the workpiece system warning signal.

This embodiment is constructed as described above,
The operation and the like will be described. For example, in the case where an etching process is performed on a semiconductor wafer that is an object to be processed, first, the drive mechanism 37 is activated to raise the vertical movement plate 35,
The upper end surface of each pusher pin 32, 33 projects from the mounting surface of the electrostatic chuck 21.

Then, a gate valve (not shown) provided on the side surface of the processing chamber 1 is opened, and a transfer arm (not shown).
When the semiconductor wafer W is loaded into the processing chamber 1 by the above and placed on the upper end surfaces of the pusher pins 32 and 33, the drive mechanism 37 is actuated again and the vertical movement plate 35 is lowered. Along with that, the pusher pins 32 and 33 are also lowered and housed in the electrostatic chuck 21, and the semiconductor wafer W is placed on the electrostatic chuck 21 at a predetermined position. Thereafter, when the electrostatic chuck 21 is operated by applying a DC voltage from the high voltage DC power supply 24, the semiconductor wafer W is attracted and held at that position.
At this time, the direct current is monitored by the current monitor 77, and the monitor signal is input to the detection device 75.

A process gas such as CF ₄ gas supplied from a separate process gas supply device is supplied to the gas inlet 5.
4 is discharged toward the dummy wafer of the semiconductor wafer W through the discharge port 53 of the upper electrode 51, and at the same time, the pressure in the processing chamber 1 is maintained at 0.5 Torr, for example.

When high-frequency power whose frequency is set to 13.56 MHz and power is set to 1 kw is applied to the susceptor 7 by the high-frequency power source 8, plasma is generated in the processing chamber 1 and the semiconductor wafer W is exposed. On the other hand, an etching process is performed. V _DC biased at this time susceptor 7 side is monitored by V _DC monitor 74, the monitor signal is input to the detector 75. Then, in the state where the etching process is normally performed, the detection device 75 outputs a normal signal to the display 78 described above.

However, for example, during the etching process, H
Gas introduction pipe 39 and through holes 31, 32 through which e gas flows
When a discharge occurs in each of the pusher pins 33 and 34 in the inside, the _VDC level monitored by the _VDC monitor 74 greatly changes, and a monitor signal corresponding to the _VDC level is input to the detection device 75. On the other hand, at this time, the DC current for operating the electrostatic chuck 21 detected by the current monitor 77 does not change, and the monitor signal does not change.
Therefore, the detection device 75 compares the above monitor signals and immediately outputs the He gas system warning signal to the display 78, so that the worker discharges to the He gas system in the processing chamber 1. Can be perceived as occurring.

Further, for example, when the electrostatic chuck 21 is discharged during the etching process, the _VDC monitor 7
The V _DC level monitored by 4 and the DC current for operating the electrostatic chuck 21 detected by the current monitor 77 greatly vary. Then, the detection device 75 compares and processes the large fluctuations of the respective monitor signals, and as a result, outputs an electrostatic chuck system warning signal to the display 78, whereby the worker can quietly operate in the processing chamber 1. It can be perceived that there was a discharge on the electric chuck 21.

Further, in this embodiment, the deviation of the semiconductor wafer W placed on the electrostatic chuck 21 can also be detected. That is, when the semiconductor wafer W to be mounted on the electrostatic chuck 21 at a predetermined position is displaced from the predetermined position for some reason, the high voltage DC power supply 24 for operating the electrostatic chuck 21 is activated. Then, when the high voltage DC is applied, the fluctuation range of the monitor signal from the current monitor 77 is detected to be relatively small. On the other hand, when the high frequency power for plasma generation is applied in such a shifted state, the mounting surface of the electrostatic chuck 21 is directly exposed to the plasma, so that the _VDC level monitored by the _VDC monitor 74 greatly changes. To do. Then, based on the signals from these monitors, the detection device 7
Reference numeral 5 outputs an object-to-be-processed warning signal to the display 78, whereby an operator places the semiconductor wafer W, which is an object to be processed, on the electrostatic chuck 21 in a state of being displaced from a predetermined position. You can perceive what is being done.

Further, in issuing the warning signal as described above, comparison processing is performed on the basis of the monitor signals from two completely different systems, the _VDC level of the high frequency power system and the high voltage DC system. Since it is judged, its reliability is extremely high. Of course, the V _DC monitor 74 and the current monitor 77 themselves monitor the DC current from the high-voltage DC power supply 24 and the V _DC level of the generated plasma, so that the respective systems are monitored and controlled. In addition, it is possible to detect even if there is an abnormality unique to each system. Furthermore, it is possible to detect the end point in the etching process.

In the above embodiment, the etching processing apparatus is applied, but the present invention is not limited to this, and for example, an ashing apparatus or C
The present invention is applicable to other plasma devices including a VD device, which has an electrostatic chuck in a processing chamber and generates plasma in the processing chamber.

[0034]

According to the abnormal discharge detection method of claim 1,
It is possible to detect the presence or absence of the abnormal discharge that has occurred in the processing chamber of the plasma device and the location where the abnormal discharge has occurred, and it is also easy to detect the deviation of the object to be processed such as a semiconductor wafer placed on the electrostatic chuck.

According to the second aspect, while monitoring the two states of the electrostatic chuck system and the high frequency power system in the plasma device, the presence or absence of the abnormal discharge occurring in the processing chamber and the place where the abnormal discharge occurs can be detected. Further, it is easy to detect the deviation of the object to be processed such as a semiconductor wafer placed on the electrostatic chuck.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a side cross-section of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

1 Processing Room 7 Susceptor 8 High Frequency Power Supply 21 Electrostatic Chuck 24 High Voltage DC Power Supply 33, 34 Pusher Pin 39 Gas Introducing Tube 51 Upper Electrode 74 _VDC Monitor 75 Detector 77 Current Monitor W Semiconductor Wafer

Claims (2)

[Claims] 1. A plasma apparatus for applying a high-frequency power from a high-frequency power source to an electrode in a processing chamber to generate plasma in the processing chamber and processing an object to be processed placed on an electrostatic chuck provided in the processing chamber. An abnormal discharge detection method, characterized in that an abnormal discharge in the processing chamber is detected by the current level of the electrostatic chuck actuating current and the _VDC level monitored from the supply line of the high frequency power supply. 2. An apparatus for processing an object placed on an electrostatic chuck provided in the processing chamber by applying high-frequency power from a high-frequency power source to electrodes in the processing chamber to generate plasma. A plasma apparatus comprising: a monitor for detecting a current level of the electrostatic chuck operating current; and a _VDC monitor for detecting a _VDC level from the high frequency power supply line.