JP2007266365A - Plasma treatment apparatus, and method of measuring high-frequency current quantity in plasma - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correctly detect a high-frequency current quantity flowing through plasma between upper and lower electrodes, and to know the flow of a high-frequency current in the plasma. <P>SOLUTION: Two coil-like probes 40, 41 for detecting the strength of a magnetic field around a center axis of a processing space K are provided in a processing container 2 of a plasma etching apparatus 1. In the probes 40, 41, the shafts of the coils are directed to the circumferential direction of the center axis of the processing space K. The lower probe 40 is provided at a height near the lower electrode 12, and the upper probe 41 is provided at a height near the upper electrode 20. The probes 40, 41 each detect an induced electromotive force generated in each coil as the strength of a magnetic field, and a computer 51 calculates high-frequency current quantities Az1, Az2 from the induced electromotive force on the basis of a predetermined calculating principle. The difference between the high-frequency current quantities Az1 and Az2 in the probes 40 and 41 is obtained to calculate a loss output high-frequency current quantity Ar to be flown out from a plasma region P between the upper and lower electrodes. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus that generates a plasma in a processing container to process a substrate, and a method for measuring a high-frequency current amount in plasma in the plasma processing apparatus.

  For example, plasma processing is widely used in substrate processing such as etching and film formation in manufacturing processes of semiconductor devices and liquid crystal display devices.

  The plasma processing is usually performed by a plasma processing apparatus. In this plasma processing apparatus, electrodes that are vertically opposed to each other are provided in a processing container. For example, high-frequency power is supplied to a lower electrode on which a substrate is placed, and plasma is generated between the lower electrode and the upper electrode to generate a substrate. Is being processed.

  In the above-described plasma processing, a high frequency current flows in the plasma from the lower electrode toward the upper electrode by supplying high frequency power. This high-frequency current contributes to plasma generation and has a close relationship with plasma states such as plasma density and self-bias (Vdc), and is an important factor in evaluating the processing state of the substrate. For this reason, conventionally, in a plasma processing apparatus, a current sensor is attached to the output side of the matching device connected to the lower electrode, and the amount of high-frequency current flowing from the matching device to the electrode has been measured (Patent Document 1). reference).

JP 2002-43402 A

  However, when the current sensor is provided on the output side of the matching device as described above, the measurement point of the high frequency current amount is away from the plasma, and the power is consumed due to the influence of the impedance of the processing container. The amount of high-frequency current passing through the plasma differs from the amount of current measured by the current sensor. For this reason, it has been difficult to accurately evaluate the processing state of the substrate from the measured amount of high-frequency current. In particular, at a high frequency of about several tens of MHz used for the etching process, the difference between the amount of current at the measurement point on the output side of the matching device and the amount of current actually entering the plasma often becomes large. I could not know the condition accurately.

  By the way, a change in the condition in the processing vessel, for example, contamination or damage to the inner wall surface of the processing vessel or the upper and lower electrodes can be detected by a change in the flow of high-frequency current in the plasma. However, the current sensor described above cannot detect the flow of high-frequency current in the plasma, and thus cannot detect a change in the condition in the processing vessel. For this reason, the change in the processing state of the substrate due to the change of the condition in the processing container was detected at an early stage and could not be dealt with.

  Even if the plasma processing equipment has the same specifications, the conditions in the processing vessel are slightly different for each plasma processing equipment. However, as described above, the flow of high-frequency current in the plasma to know the conditions is known. Because it was not possible, it was not possible to match the differences in the conditions (machine differences) of each plasma processing equipment. As a result, when a plurality of plasma processing apparatuses process a substrate in parallel, the processing state of the substrate may vary between apparatuses.

  The present invention has been made in view of this point, and an object of the present invention is to accurately detect the amount of high-frequency current flowing in the plasma in the processing vessel and to grasp the flow of high-frequency current in the plasma.

  In order to achieve the above object, the present invention has a high-frequency electrode facing up and down in a processing vessel, and supplies high-frequency power to at least one of the high-frequency electrodes to generate plasma in the processing vessel. A plasma processing apparatus for processing a substrate, wherein the probe is installed in the processing container and detects a time change amount of a magnetic field in a circumferential direction with respect to a vertical center axis of the processing container, and the probe A calculation unit that calculates an amount of high-frequency current flowing in the axial direction in the plasma by the supply of the high-frequency power based on the detection result of the time change amount of the magnetic field by the probe. It is provided at a plurality of locations in the vertical direction.

  According to the present invention, the amount of time change of the magnetic field actually generated around the central axis in the processing container can be detected, and the amount of high-frequency current can be calculated from the amount of time change of the magnetic field. The amount of high-frequency current flowing in the axial direction can be accurately detected. As a result, the processing state of the substrate can be accurately evaluated. In addition, since high-frequency current amounts at a plurality of locations can be calculated by arranging probes at a plurality of locations in the vertical direction in the processing vessel, it is possible to detect a change in the high-frequency current amount in the processing chamber and grasp the flow of the high-frequency current. Thereby, the change of the condition in a processing container is detectable. In addition, the condition can be adjusted among a plurality of devices.

  The probe may be formed in a coil shape, and the axis of the coil may be directed in the circumferential direction around the central axis of the processing container.

  The probe may detect an induced electromotive force generated in the coil as a time change amount of the magnetic field, and the calculation unit may calculate the high-frequency current amount from the induced electromotive force.

  The probe may be provided at a height between the upper and lower high-frequency electrodes.

  The probe may be provided outside the substrate held by any one of the upper and lower high-frequency electrodes in the processing container.

  At least one of the probes may be provided at a height immediately below the upper high-frequency electrode, and at least one of the probes may be provided at a height immediately above the lower high-frequency electrode.

  The calculation unit subtracts the high-frequency current amount detected by the probe close to the other high-frequency electrode side from the high-frequency current amount detected by the probe close to the one high-frequency electrode side, and increases or decreases the axial direction between the probes. The amount of high-frequency current flowing in the radial direction may be calculated from the amount of high-frequency current.

  The plasma processing apparatus calculates a high-frequency current amount between the probes during the processing of the substrate, and stops the processing of the substrate based on the calculated high-frequency current amount and a preset threshold value of the high-frequency current amount. You may have a control part.

  The plasma processing apparatus has an analysis unit for decomposing the time variation of the detected magnetic field into each frequency component included therein, and the calculation unit performs a high-frequency operation between the probes for each frequency. The amount of current may be calculated.

  The plasma processing apparatus may include an adjustment unit that adjusts the high-frequency current amount of a specific frequency based on the calculated high-frequency current amount of each frequency.

  The probe may be covered with an insulating cover.

  The probe may be embedded in a member facing the generated plasma. For example, the probe may be embedded in a wall portion of the processing container.

  The lowermost probe may be embedded in an annular member surrounding the outer periphery of the substrate held by the lower high-frequency electrode in the processing container.

  The probe may be movable up and down in the processing container.

  According to another aspect of the present invention, the processing vessel has high-frequency electrodes facing vertically, and high-frequency power is supplied to at least one of the high-frequency electrodes to generate plasma in the processing vessel. In a plasma processing apparatus for processing a substrate, a method for measuring the amount of high-frequency current flowing in plasma, wherein the center of the processing container in the vertical direction is measured by probes installed at a plurality of vertical positions in the processing container. The amount of high-frequency current flowing in the plasma in the axial direction by the supply of the high-frequency power based on the step of detecting the amount of time change of the magnetic field in the circumferential direction with respect to the axis and the detection result of the time change amount of the magnetic field of each probe Detected by the probe near the other high-frequency electrode side from the step of calculating the amount of high-frequency current detected by the probe near the one high-frequency electrode side The frequency current amount is subtracted, to a step of calculating a high-frequency current amount that flows from the high-frequency current amount of axially increased or decreased between the probes in the radial direction, characterized in that it has a.

  According to the present invention, since the amount of high-frequency current flowing in the generated plasma can be detected accurately, the processing state of the substrate can be accurately grasped by the amount of high-frequency current. In addition, since the flow of the high-frequency current in the plasma can be grasped, it is possible to detect a change in the device condition and to adjust the machine difference between the devices.

  Hereinafter, preferred embodiments of the present invention will be described. FIG. 1 is an explanatory view of a longitudinal section showing an outline of a configuration of a plasma etching apparatus 1 as a plasma processing apparatus according to the present invention. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, the plasma etching apparatus 1 includes a processing container 2 having a substantially cylindrical shape, for example. A processing space K is formed inside the processing container 2. The inner wall surface of the processing container 2 is covered with a protective film such as alumina. The processing container 2 is grounded.

  For example, a cylindrical electrode support 11 is provided at the bottom of the central portion in the processing container 2 with an insulating plate 10 interposed. On the electrode support 11, a lower electrode 12 is provided as a high-frequency electrode that also serves as a mounting table on which the substrate W is mounted. For example, the center of the upper surface of the lower electrode 12 protrudes in a columnar shape, and the substrate W is held by the protruding portion 12a. The protruding portion 12a is an electrostatic chuck. Around the protrusion 12a of the lower electrode 12, a focus ring 13 made of quartz as an annular member is provided.

  For example, a substantially disk-shaped upper electrode 20 is attached to the ceiling of the processing container 2 facing the lower electrode 12. On the lower surface of the upper electrode 20, for example, a large number of gas discharge holes 20a are formed. The gas discharge hole 20 a communicates with a gas supply source 23 through a gas supply pipe 22 connected to the upper surface of the upper electrode 20. The gas supply source 23 stores a processing gas for the etching process. The processing gas introduced into the upper electrode 20 from the gas supply pipe 22 is supplied to the processing space K from the plurality of gas discharge holes 20a.

  A high-frequency power source 31 is electrically connected to the lower electrode 12 via a matching unit (not shown). The high frequency power supply 31 can output high frequency power having a frequency of, for example, 40 MHz or more, for example, 60 MHz. In addition to the matching unit, an impedance adjustment unit 30 capable of correcting the impedance of the circuit on the lower electrode 12 side is provided between the high frequency power supply 31 and the lower electrode 12. The operation of the high-frequency power supply 31 and the impedance adjustment unit 30 is controlled by the control unit 60 described later.

  In the vicinity of the side wall 2a of the processing container 2, two probes 40 and 41 are installed in the vertical direction. For example, as shown in FIG. 2, the lower probe 40 is constituted by a circular two-turn coil 40a having a diameter of about 3 mm. The direction of the axis of the coil 40 a is directed in the circumferential direction θ around the central axis in the vertical direction of the processing container 2. In other words, the coil 40a is installed such that the coil surface is perpendicular to both the surface of the substrate W on the lower electrode 12 and the inner surface of the side wall 2a of the processing vessel 2 as shown in FIG. Yes. Thereby, the magnetic flux in the circumferential direction θ generated in the processing space K penetrates the coil 40a, and an induced electromotive force can be generated in the coil 40a by the change of the magnetic flux. Therefore, the lower probe 40 can detect the time variation of the magnetic field in the circumferential direction θ as an induced electromotive force.

  The upper probe 41 has the same configuration as that of the lower probe 40, and is constituted by, for example, a circular two-winding coil 41a. The coil 41a has an axial direction in a circumferential direction θ around the central axis in the vertical direction of the processing vessel 2. Is directed. Therefore, the upper probe 41 penetrates the magnetic flux in the circumferential direction θ generated in the processing space K into the coil 41a, and the induced electromotive force induced in the coil 41a by the change of the magnetic flux is converted into the amount of time change of the magnetic field in the circumferential direction θ. Can be detected as

  The lower probe 40 is installed, for example, immediately above the lower electrode 12, that is, outside the substrate W on the lower electrode 12 and at the same height as the substrate W. For example, the lower probe 40 is installed at a position where the lower end of the coil 40a is about 5 to 10 mm higher than the surface of the substrate W. Thereby, the lower probe 40 can detect the amount of time change of the magnetic field in the circumferential direction θ at the height near the lower electrode 12. Further, as shown in FIG. 3, the lower probe 40 is disposed in the vicinity of the side wall 2a and at a position of 15 to 25 mm, more preferably 20 mm from the inner surface of the side wall 2a. The lower probe 40 is covered with a cover 42 made of an insulator, such as quartz or ceramics, fixed to the side wall 2a.

  As shown in FIG. 1, the upper probe 41 is installed, for example, at a height immediately below the upper electrode 20. For example, the upper probe 41 is installed at a position where the upper end portion of the coil 41 a is about 5 to 10 mm lower than the lower surface of the upper electrode 20. Similarly to the lower probe 40, the upper probe 41 is provided in the vicinity of the side wall 2a and at a position of 15 to 25 mm, more preferably 20 mm from the inner surface of the side wall 2a. The upper probe 41 is covered with a cover 43 made of an insulating material such as quartz or ceramics fixed to the side wall 2a.

  The coil 40a of the lower probe 40 and the coil 41a of the upper probe 41 are connected to an analyzer box 50 as an analysis unit. The analyzer box 50 can decompose the time variation (induced electromotive force) of the magnetic field detected by the probes 40 and 41 into each frequency component included therein.

  The analyzer box 50 is connected to a computer 51 as a calculation unit. The computer 51 can calculate the amount of high-frequency current flowing in the plasma of the processing space K from the induced electromotive force of each frequency component decomposed by the analyzer box 50, and store the information. The high-frequency current amount here is the total amount of high-frequency current flowing in the plasma region P at the positions of the probes 40 and 41.

Here, the calculation principle of the high-frequency current amount Az of the high-frequency current Iz flowing in the axial direction in the plasma region P will be described with reference to FIG. FIG. 4 schematically shows the inside of the processing vessel 2 having the plasma region P. In FIG. 4, r is the distance from the central axis of the processing vessel 2, H _θ (r) is the strength of the magnetic field in the circumferential direction θ, and V (r) is the induced electromotive force generated in the coil 40a (41a). Show. The high frequency current Iz is expressed by the following equation (1) using the high frequency current amount Az.

(Ω is the frequency of the high frequency). From Ampere's law, the following equation (2)

Holds. If the magnetic flux is Φ, the following equation (3) is given by Faraday's law:

Holds. When N is the number of turns of the coil 40a (41a), S is the area of the coil surface, μ ₀ is the magnetic permeability, and the equations (1) and (2) are substituted into the equation (3) and transformed,

It becomes. Therefore,

Thus, the high-frequency current amount Az is calculated from the induced electromotive force V (r) generated in the coil 40a (41a).

  Hereinafter, the induced electromotive force generated in the coil 40a of the lower probe 40 is V (r) 1, and the high-frequency current amount calculated from the induced electromotive force V (r) 1 is Az1. Further, the induced electromotive force generated in the coil 41a of the upper probe 41 is V (r) 2, and the high-frequency current amount calculated from the induced electromotive force V (r) 2 is Az2. In this example, the high-frequency current amount Az1 calculated by the lower probe 40 is the high-frequency current amount input from the lower electrode 12 to the plasma region P as shown in FIG. The amount Az2 is the high-frequency current amount Az2 output from the plasma region P to the upper electrode 20.

  The computer 51 further obtains a difference between the high-frequency current amount Az1 and the high-frequency current amount Az2, and causes a loss high-frequency current amount Ar (Ar = Az1) to flow out to the radial side wall portion 2a between the upper electrode 20 and the lower electrode 12. -Az2) can be calculated. The computer 51 can output information on the calculated loss high-frequency current Ar to the control unit 60 of the plasma etching apparatus 1, for example.

  For example, the control unit 60 compares the output loss high-frequency current amount Ar with a preset threshold value, and outputs an error when the value of the loss high-frequency current amount Ar exceeds the threshold value. Can be stopped. As for the threshold value, for example, a value of the loss high-frequency current amount Ar when a problem occurs in the condition of the processing container 2 or the processing state of the substrate W is obtained in advance, and the value is set as the threshold value.

  An exhaust pipe 70 communicating with an exhaust mechanism (not shown) is connected to the lower portion of the processing container 2. By evacuating the processing container 2 through the exhaust pipe 70, the processing space K can be reduced to a predetermined pressure.

  Next, the operation of the plasma etching apparatus 1 configured as described above will be described.

  When performing an etching process in the plasma etching apparatus 1, first, the substrate W is loaded into the processing container 2 and placed on the lower electrode 12 as shown in FIG. Exhaust is performed from the exhaust pipe 70, the inside of the processing container 2 is decompressed, and a predetermined processing gas is supplied from the gas discharge hole 20a. Next, high frequency power for plasma generation is supplied to the lower electrode 12 by the high frequency power supply 31. As a result, a high frequency voltage is applied between the lower electrode 12 and the upper electrode 20, plasma is generated in the processing space K between the lower electrode 12 and the upper electrode 20 in the processing container 2, and a plasma region P is formed. Is done. The plasma generates active species and ions from the processing gas, and the surface film of the wafer W is etched. After etching is performed for a predetermined time, the supply of high-frequency power and the supply of processing gas are stopped, the wafer W is unloaded from the processing container 2, and a series of etching processes is completed.

  In the plasma etching apparatus 1, for example, when detecting a change in the amount of high-frequency current in the plasma region P, first, during the generation of plasma, the magnetic field in the circumferential direction θ near the lower electrode 12 in the processing space K is generated by the lower probe 40. A time change amount is detected. At this time, a magnetic flux Φ in the circumferential direction θ near the lower electrode 12 in the processing space K passes through the coil 40a of the lower probe 40, and an induced electromotive force V (r) is generated in the coil 40a due to a change in the magnetic flux Φ in the coil 40a. ) 1 is generated. This induced electromotive force V (r) 1 is detected as a time change amount of the magnetic field in the vicinity of the lower electrode 12. Further, the amount of time change of the magnetic field in the circumferential direction θ near the upper electrode 20 in the processing space K is detected by the upper probe 41. A magnetic flux Φ in the circumferential direction θ near the upper electrode 20 in the processing space K passes through the coil 41a of the upper probe 41, and an induced electromotive force V (r) 2 is applied to the coil 41a due to a change in the magnetic flux Φ in the coil 41a. Arise. This induced electromotive force V (r) 2 is detected as a time change amount of the magnetic field in the vicinity of the upper electrode 20.

  The detection information of the induced electromotive forces V (r) 1 and V (r) 2 is input to the analyzer box 50. In the analyzer box 50, the detected induced electromotive forces V (r) 1 and V (r) 2 are It is decomposed into each frequency component such as fundamental wave and harmonics of high frequency power. The induced electromotive forces V (r) 1 and V (r) 2 decomposed into the respective frequency components are sent to the computer 51. The computer 51 uses the calculation principle such as the above equation (4) to generate each induced electromotive force. High-frequency current amounts Az1 and Az2 corresponding to V (r) 1 and V (r) 2 are calculated. Further, the computer 51 calculates a loss high-frequency current amount Ar obtained by subtracting the high-frequency current amount Az2 from the high-frequency current amount Az1.

  The calculated high-frequency current amounts Az1, Az2, Ar are output to, for example, the control unit 60. For example, the loss high-frequency current amount Ar is compared with a threshold value set in advance for each frequency component. If it is determined that the threshold value is exceeded, an error is output, for example, and the processing of the substrate W is stopped. Information on the high-frequency current amounts Az1, Az2, Ar is stored in the control unit 60 and used as information for evaluating the processing state of the substrate W and the condition in the processing container 2. Note that an error may be output when the threshold value is exceeded, depending on how the threshold value is set.

  According to the above embodiment, since the probes 40 and 41 are installed in the processing container 2, the high-frequency current amounts Az and Ar flowing in the plasma can be directly detected. Therefore, accurate high-frequency current amounts Az and Ar can be detected, and for example, the processing state of the substrate W can be accurately evaluated based on the high-frequency current amounts Az and Ar.

  Further, since the probes 40 and 41 are provided in the vicinity of the upper and lower electrodes 12 and 20 in the processing chamber 2, respectively, the high-frequency current amount Az1 input from the lower electrode 12 into the plasma region P and the upper electrode 20 from the plasma region P. The high-frequency current amount Az2 that is output to the side wall surface 2a between the lower electrode 12 and the upper electrode 20 can be detected from the high-frequency current amounts Az1 and Az2. Thereby, the fluctuation | variation of the high frequency current amount in the plasma area | region P is detected, and the flow of the high frequency current in the plasma area | region P can be grasped | ascertained. As a result, for example, the condition in the processing container 2 can be grasped. For example, when the inner wall surface of the processing container 2 and the electrodes 12 and 20 are soiled or cracked, the protective film on the inner wall surface is reduced, or abnormal discharge occurs in the gas hole 20a of the upper electrode 20 or the like. The flow of the high-frequency current amount Iz in the direction of the upper electrode 20 is hindered or the outflow of the high-frequency current amount Iz in the direction of the side wall surface 2a is hindered to change the high-frequency current amounts Az and Ar. Therefore, by grasping the flow of the high-frequency current from the high-frequency current amounts Az and Ar as in the present embodiment, it is possible to detect a change in the condition in the processing container 2. In addition, since the condition in the processing container 2 can be grasped, the machine difference with other plasma etching apparatuses can be corrected based on the condition.

  Further, since the probes 40 and 41 are formed in a coil shape and the axes of the coils 40a and 41a are oriented in the circumferential direction θ of the processing space K, the magnetic flux Φ is passed through the coils 40a and 41a, and electromagnetic induction is used. By generating an induced electromotive force in the coils 40a and 41a, it is possible to easily and accurately detect the time change amount of the magnetic field in the circumferential direction θ as the induced electromotive force V (r).

  Since the probes 40 and 41 are covered with covers 42 and 43 made of insulating quartz or ceramics, corrosion of the probes 40 and 41 due to plasma can be prevented.

  Since the probes 40 and 41 are provided outside the substrate W in the processing container 2 and in the vicinity of the side wall portion 2a, even if the probes 40 and 41 are provided in the processing container 2, the substrate W in the processing space K is provided. The processing of the substrate W can be appropriately performed without hindering the processing.

  The probes 40 and 41 are provided at positions of 15 mm to 25 mm from the inner surface of the side wall 2a of the processing container 2. FIG. 5 is a graph showing the amount of current detected by the probe when the other conditions are the same and the distance between the probe and the side wall 2a is changed. From the graph of FIG. 5, it can be seen that when the probe is at a distance of 15 mm to 25 mm from the side wall 2a, the detected current amount increases. Therefore, the sensitivity of the probes 40 and 41 can be optimized by positioning the probes 40 and 41 within the range of 15 mm to 25 mm from the side wall 2a.

  In the above embodiment, since the lower probe 40 is arranged at a height immediately above the lower electrode 12 having the same height as the substrate W, the high-frequency current amount Az1 flowing into the plasma region P from the lower electrode 12 is calculated. It can be detected accurately. Further, since the upper probe 41 is disposed at a height immediately below the upper electrode 20, the high-frequency current amount Az2 flowing out from the plasma region P to the upper electrode 20 can be accurately detected. In addition, the amount of high-frequency current Ar flowing out from the lower electrode 12 to the upper electrode 20 can be detected accurately.

  In the above embodiment, since the processing of the substrate W is stopped by the controller 60 when the loss high-frequency current amount Ar exceeds the threshold value, the processing state of the substrate W or the condition in the processing container 2 is abnormal. Therefore, it is possible to prevent a large number of defective substrates W from being manufactured.

  In the computer 51, the analyzer box 50 decomposes the induced electromotive forces V (r) 1 and V (r) 2 output from the probes 40 and 41 into respective frequency components such as a fundamental wave and a harmonic wave of the high frequency power. The high-frequency current amounts Az1 and Az2 and the loss high-frequency current amount Ar can be calculated for each frequency component. For this reason, the processing state of the substrate W and the condition in the processing container 2 can be grasped in more detail.

  In the above-described embodiment, the impedance to the fundamental wave and harmonics in the circuit on the lower electrode 12 side may be controlled based on the fundamental frequency and harmonic high-frequency current amount Ar that are the calculated specific frequency components. In this case, for example, the impedance adjustment unit 30 includes a variable capacitor 75 as a variable element, a fixed coil 76, and the like as shown in FIG. 6, and the entire circuit on the lower electrode 12 side is changed by changing the capacitance of the variable capacitor 75. Impedance for fundamental wave and harmonics can be changed. Then, the control unit 60 controls the impedance adjustment unit 30 based on the calculated high-frequency current amounts Az and Ar of the fundamental wave and harmonics, and controls the impedance of the circuit on the lower electrode 12 side with respect to the fundamental wave and harmonics. To do. By doing so, the high-frequency current amounts Az and Ar of the fundamental wave and harmonics in the plasma can be adjusted, and the plasma state, the processing state of the substrate W, or the condition in the processing container 2 can be adjusted to a more appropriate one.

  In the above embodiment, the probes 40 and 41 are attached to the side wall 2a of the processing vessel 2. However, the probes 40 and 41 may be embedded in the side wall 2a as shown in FIG. In this case, for example, two upper and lower spaces 80 and 81 are formed in the side wall 2a, and the probes 40 and 41 are installed in the spaces 80 and 81, respectively. By doing so, the probes 40 and 41 do not protrude into the processing space K in the processing container 2, so that the plasma in the processing space K is not affected by the probes 40 and 41. Further, since the probes 40 and 41 are protected by the side wall portion 2a, corrosion of the probes 40 and 41 by plasma can be prevented. In this case, it is conceivable that the amount of current detected by the probes 40 and 41 is reduced as shown in FIG. 5 described above. In this case, for example, the amount of high frequency current Az is taken into consideration in advance. May be evaluated.

  In the above example, when the material of the focus ring 13 is a dielectric, the lower probe 40 may be embedded in the focus ring 13 around the substrate W as shown in FIG. In such a case, for example, a space 90 is formed in the focus ring 13, and the lower probe 40 is installed in the space 90. Also in this case, since the lower probe 40 does not protrude into the processing space K in the processing container 2, the plasma in the processing space K is not affected by the lower probe 40. Further, since the lower probe 40 is protected by the focus ring 13, corrosion of the lower probe 40 due to plasma can be prevented. Furthermore, since the position of the lower probe 40 is close to the surface of the substrate W, it is possible to accurately detect the high-frequency current amount Az1 that flows out immediately above the substrate W that most affects the etching process.

  The probes 40 and 41 are not limited to the side wall 2a and the focus ring 13, but other dielectrics facing the plasma region P such as a window (not shown) for viewing the inside of the processing vessel 2 and the upper electrode 20. It may be embedded in the member.

  In the above embodiment, the probes 40 and 41 are fixed to the side wall 2a. However, the probes 40 and 41 may be movable in the vertical direction. In this case, for example, as shown in FIG. 9, a rail 100 extending in the vertical direction is provided on the side wall 2 a of the processing container 2, and two sliders 101 and 102 that move up and down may be provided on the rail 100. . The lower probe 40 and its cover 42 may be attached to the lower slider 101, and the upper probe 41 and its cover 43 may be attached to the upper slider 102, respectively. When detecting the high-frequency current amounts Az1, Az2, Ar, either the lower probe 40 or the upper probe 41, or both the lower probe 40 and the upper probe 41 are moved up and down, and the magnetic field is detected at an arbitrary position in the vertical direction. The amount of time change is detected, and the high-frequency current amounts Az1, Az2 at each position and the loss high-frequency current amount Ar are calculated. By doing so, for example, a position where the loss high-frequency current amount Ar is large or small can be specified in the side wall 2a surface. As a result, for example, it is possible to specify a position such as a crack in the side wall 2a or a peeling of the protective film that causes a change in the condition in the processing container 2. Further, the flow of the high-frequency current Iz in the plasma region P can be grasped in more detail, and the processing state of the substrate W and the condition in the processing container 2 can be accurately known.

  The preferred embodiment of the present invention has been described above with reference to the accompanying drawings, but the present invention is not limited to such an example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the spirit described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs. For example, the number of turns of the coils 40a and 41a of the probes 40 and 41 is not limited to two, but may be one or three or more. The shapes of the coils 40a and 41a may not be circular but may be square. In the above embodiment, the high frequency power is supplied to the lower electrode 12, but the high frequency power may be supplied to the upper electrode 20. Further, high frequency power may be supplied to both the lower electrode 12 and the upper electrode 20. Further, the number of probes is not limited to two, and may be provided at three or more locations. In the above embodiment, the present invention is applied to the plasma etching apparatus 1, but the present invention can also be applied to a substrate processing other than the etching process, for example, a plasma processing apparatus that performs a film forming process. Further, the substrate processed by the plasma processing apparatus of the present invention may be any of a semiconductor wafer, an organic EL substrate, a substrate for FPD (flat panel display), and the like.

  The present invention is useful for accurately detecting the amount of high-frequency current flowing in the plasma and grasping the flow of high-frequency current in the plasma in the substrate plasma processing apparatus.

It is explanatory drawing of the longitudinal cross-section which shows the outline of a structure of the plasma etching apparatus concerning this Embodiment. It is a schematic diagram of the coil of a probe. It is explanatory drawing which shows the installation position of a probe. It is a schematic diagram of the processing space for calculating the amount of high frequency current. It is a graph which shows the relationship between the distance from the side wall part of a probe, and the detected electric current amount in the position. It is a schematic diagram which shows the structure of an impedance adjustment part. It is explanatory drawing of the longitudinal cross-section which shows the outline of a structure of the plasma etching apparatus at the time of providing a probe in a side wall part. It is explanatory drawing of the longitudinal cross-section which shows the outline of a structure of the plasma etching apparatus at the time of providing a probe in a focus ring. It is explanatory drawing of the longitudinal cross-section which shows the outline of a structure of the plasma etching apparatus at the time of making a probe movable up and down.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma etching apparatus 2 Processing container 12 Lower electrode 20 Upper electrode 40 Lower probe 41 Upper probe 51 Computer 60 Control part P Plasma area K Processing space W Substrate

Claims (16)

A plasma processing apparatus having a high-frequency electrode facing vertically in a processing vessel, supplying high-frequency power to at least one of the high-frequency electrodes, generating plasma in the processing vessel, and processing a substrate. And
A probe that is installed in the processing container and detects the amount of time change of the magnetic field in the circumferential direction with respect to the central axis in the vertical direction of the processing container;
A calculation unit that calculates the amount of high-frequency current flowing in the axial direction in the plasma by the supply of the high-frequency power based on the detection result of the time change amount of the magnetic field by the probe;
The plasma processing apparatus, wherein the probe is provided at a plurality of locations in the vertical direction in the processing container. The plasma processing apparatus according to claim 1, wherein the probe is formed in a coil shape, and an axis of the coil is oriented in the circumferential direction around a central axis of the processing container. The probe detects an induced electromotive force generated in the coil as a time change amount of the magnetic field,
The plasma processing apparatus according to claim 2, wherein the calculation unit calculates the high-frequency current amount from the induced electromotive force. The plasma processing apparatus according to claim 1, wherein the probe is provided at a height between the upper and lower high-frequency electrodes. 5. The plasma processing apparatus according to claim 1, wherein the probe is provided outside a substrate held by any one of upper and lower high-frequency electrodes in the processing container. The at least one of the probes is provided at a height immediately below the upper high-frequency electrode, and at least one of the probes is provided at a height immediately above the lower high-frequency electrode. The plasma processing apparatus according to claim 5. The calculation unit subtracts the high-frequency current amount detected by the probe close to the other high-frequency electrode side from the high-frequency current amount detected by the probe close to the one high-frequency electrode side, and increases or decreases the axial direction between the probes. The plasma processing apparatus according to claim 1, wherein the amount of high-frequency current flowing in the radial direction is calculated from the amount of high-frequency current. A controller that performs a calculation of the high-frequency current amount between the probes during the processing of the substrate, and stops the processing of the substrate based on the calculated high-frequency current amount and a preset threshold value of the high-frequency current amount; 8. The plasma processing apparatus according to claim 7, wherein the plasma processing apparatus is characterized. An analysis unit for decomposing the time variation of the magnetic field detected by each probe into frequency components included therein;
The plasma processing apparatus according to claim 7, wherein the calculation unit calculates a high-frequency current amount between the probes for each frequency. 10. The plasma processing apparatus according to claim 9, further comprising an adjustment unit configured to adjust a high-frequency current amount of a specific frequency based on the calculated high-frequency current amount of each frequency. The plasma processing apparatus according to claim 1, wherein the probe is covered with an insulating cover. The plasma processing apparatus according to claim 1, wherein the probe is embedded in a member facing the generated plasma. The plasma processing apparatus according to claim 12, wherein the probe is embedded in a wall portion of the processing container. The plasma processing apparatus according to claim 12, wherein the lowermost probe is embedded in an annular member surrounding an outer periphery of a substrate held by a lower high-frequency electrode in the processing container. The plasma processing apparatus according to claim 1, wherein the probe is movable up and down in the processing container. In a plasma processing apparatus having a high-frequency electrode opposed vertically in a processing container, supplying high-frequency power to at least one of the high-frequency electrodes to generate plasma in the processing container, and processing a substrate, A method for measuring the amount of high-frequency current flowing in plasma,
Detecting a time change amount of a magnetic field in a circumferential direction with respect to a central axis in the vertical direction of the processing container by using probes installed at a plurality of vertical positions in the processing container;
Calculating the amount of high-frequency current flowing in the axial direction in the plasma by supplying the high-frequency power based on the detection result of the time change amount of the magnetic field of each probe;
The amount of high-frequency current detected by the probe close to the one high-frequency electrode is subtracted from the amount of high-frequency current detected by the probe close to the one high-frequency electrode, and the amount of axial high-frequency current increased or decreased between these probes is subtracted. And a step of calculating the amount of high-frequency current flowing in the radial direction.

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