JP2003224112A - Plasma treatment device and plasma treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment device ensuring homogeneous plasma treatment by grasping high frequency power applied to a plasma excitation electrode accurately thereby controlling exciting power stably. <P>SOLUTION: The plasma treatment device comprises a current detecting means for monitoring a current flowing through a power distributor supplying high frequency power to a plasma excitation electrode (cathode electrode), a means for controlling the output from a high frequency power supply such that a current detected by the current detecting means has a specified level, and a circuit for feeding back a control signal obtained from the control means to the high frequency power supply or a matching circuit in order to regulate power applied to the plasma excitation electrode. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a plasma processing apparatus and a plasma processing method, and more particularly to a high-performance plasma processing apparatus capable of stabilizing effective electric power consumed in a plasma space. And a plasma processing method using the same.

[0002]

2. Description of the Related Art Conventionally, as a plasma processing apparatus, a single frequency excitation type plasma processing apparatus shown in FIG. 3 has been known. In the plasma processing apparatus shown in FIG. 3, the plasma chamber 76 has a CVD (chemical vapor deposition).
) It is a single frequency excitation type plasma processing chamber unit capable of plasma processing such as sputtering, dry etching and ashing. As shown in the figure, a plasma excitation electrode 4 and a susceptor electrode 8 for exciting plasma composed of parallel plates are provided, and a high frequency power source 1 connected to the plasma excitation electrode 4 through a power distributor 3 and the plasma. The chamber 76 and the matching circuit 2A for obtaining impedance matching between the high frequency power source 1 are provided.

More specifically, the plasma chamber 76 is provided with a plasma excitation electrode (cathode electrode) 4 connected to the high frequency power source 1 and a shower plate 5 in an upper position of the chamber 60, and in the lower part of the chamber 60,
A susceptor electrode (counter electrode) 8 which also functions as a susceptor (supporting base) for mounting the substrate 16 to be processed is provided facing the shower plate 5. The plasma excitation electrode 4 is connected to the high frequency power supply 1 via the power distributor 3 and the matching circuit 2A. The plasma excitation electrode 4 and the power distributor 3 are covered by a chassis (shielding conductor) 21, and the matching circuit 2A is housed inside a matching box 2 made of a conductor. The chassis 21 and the matching box 2 are connected to each other, and the matching box 2 is connected to the shield wire (outer conductor) of the feeder line 1A made of a coaxial cable.

In the case of the plasma processing apparatus shown in FIG. 3, the plasma excitation electrode 4 has a circular contour shape with a diameter of about 30 cm, and corresponds to a chamber 60 having a circular cross section in the plasma excitation electrode surface direction. There is. An annular convex portion 4a is provided below the plasma excitation electrode 4,
Below the plasma excitation electrode 4, a shower plate 5 having a large number of holes 7 formed therein is provided in contact with the convex portion 4a. A space 6 is formed between the plasma excitation electrode 4 and the shower plate 5. A gas introduction pipe 17 is connected to the space 6 so as to penetrate the side wall of the chassis 21 and the plasma excitation electrode 4.

The gas introducing pipe 17 is made of a conductor, and an insulator 17a is inserted in the inside of the chassis 21 in the middle of the gas introducing pipe 17, so that the plasma excitation electrode 4
And the gas supply source are insulated. The gas introduced from the gas introduction pipe 17 is supplied into the chamber 60 constituted by the chamber wall 10 through the large number of holes 7 of the shower plate 5. The chamber wall 10 and the plasma excitation electrode 4 are insulated from each other by the insulator 9. On the other hand, in the chamber 60, a susceptor electrode 8 serving as a wafer susceptor on which the plate-shaped substrate 16 is placed is provided.

A shaft 13 is connected to the lower center of the susceptor electrode 8, and the shaft 13 is connected to the chamber bottom portion 10.
The bellows 11 is provided so as to penetrate through A, and the lower end of the shaft 13 and the center of the chamber bottom 10A are hermetically connected by a bellows 11. The susceptor electrode 8 and the shaft 13 can be moved up and down by the bellows 11, and the distance between the plasma excitation electrode 4 and the susceptor electrode 8 can be freely adjusted. Susceptor electrode 8,
The shaft 13, the bellows 11, the chamber bottom portion 10A and the chamber wall 10 have the same DC potential. Furthermore, since the chamber wall 10 and the chassis 21 are connected, the chamber wall 10, the chassis 21, and the matching box 2 are all at the same DC potential.

In this plasma processing apparatus, high frequency power is supplied only to the plasma excitation electrode 4, and the susceptor electrode 8 is grounded. Further, the susceptor electrode 8 and the chamber wall 10 have the same DC potential. The illustration of the exhaust system is omitted.

The matching circuit 2A includes a high frequency power source 1 and a power feeding plate 3.
And a plurality of passive elements for adjusting the impedance matching between the high frequency power supply 1 and the plasma excitation electrode 4 in response to changes in the plasma state in the chamber 60. It is equipped with it. Specifically, in the example of FIG. 3, it is composed of three types of passive elements: a load capacitor 22 made of a vacuum variable capacitor, a tuning coil 23, and a tuning capacitor 24 made of an air variable capacitor. Here, in the example of FIG. 3, one tuning coil 23 is connected between the load capacitor 22 and the tuning capacitor 24.

When performing the etching process or film forming process using the plasma processing apparatus as described above, it is important to maintain the processing uniformity. For that purpose, it is necessary to stabilize the generated plasma. As a means for stabilizing the plasma, for example, as disclosed in Japanese Patent Application Laid-Open No. 7-302696, it is possible to positively control the grounded state and control the amount of ions depending on the electrical characteristics to improve the processing characteristics. Discloses a method of plasma processing by monitoring a ground line. FIG. 4 illustrates a method of performing plasma processing by monitoring the ground line.

The plasma processing apparatus shown in FIG. 4 includes an etching apparatus main body 101, a process control unit 102 for controlling vacuum exhaust and etching gas supply state in the etching apparatus main body 101, and high frequency power for plasma formation. It consists of The etching apparatus main body 101 includes a processing chamber 103 vacuum-sealed with a dielectric discharge tube for passing microwaves, and a sample table 105 provided below the processing chamber 103. A semiconductor wafer 104 as a sample is placed in an electrically insulated state.

Further, from the processing chamber 103 to the semiconductor wafer 10
Up to 4, a mirror magnetic field is applied by a solenoid coil and a permanent magnet (both not shown), and in this state, the processing chamber 103 is evacuated to a high vacuum, and then a process gas is introduced at a predetermined gas pressure. Further, the microwave generated by the magnetron is introduced into the processing chamber 103 through a waveguide (not shown) and applied to a plasma excitation electrode (cathode electrode, not shown). This causes a microwave discharge, which results in a plasma state.
In this microwave discharge, the cyclotron motion of electrons in a magnetic field and the resonance phenomenon with microwaves are used.

Further, in the etching apparatus main body 101, the processing chamber 103 as an object to be grounded is actively grounded via a variable resistor (current control means) 111 and an ammeter (measurement means) 112. There is. As a result, the ammeter 112 outputs the measured value of the ground line in the processing chamber 103, and this output is output to the computer 11
Connected to 3. This computer 113 uses the variable resistor 1 based on the measurement value taken by the ammeter 112.
11 is programmed to operate to control the resistance value of 11 to a desired value.

In this case, the ions in the plasma, which depend on the current value of the ground line, disappear on the wall surface of the processing chamber 103 and the surface of the components in the processing chamber 103 which are grounded, and a current flows through the grounding line, thus grounding. It is said that by controlling the current flowing through the line, it is possible to control the amount of ion extinction, that is, the amount of ions in plasma.

[0014]

However, in the above method, as in the case of FIG. 3, the high frequency power applied to the plasma excitation electrode is such that the output of the high frequency power supply becomes a predetermined value at the outlet to the high frequency power supply. Controlled. Further, in measuring the plasma excitation current, a part of the current on the ground line side is guided to the bypass circuit. Therefore, a part of the whole current, for example, 2 to 3% is used to measure the plasma excitation current. However, there is a problem that the measurement error is large. In addition, in the above method, a resistor is used to form a bypass circuit for current measurement, so current loss occurs due to the impedance of this bypass circuit, and the power used for plasma excitation can be accurately determined. There are difficulties that cannot be done.

Further, in the conventional method, since the output of the high frequency power source is adjusted so as to have a predetermined value at the power source output section, the matching circuit is caused due to the temperature rise of the conductor when a high frequency current is passed. The power loss fluctuates, and the effective power actually consumed in the plasma space fluctuates. For example, as the temperature of the conductor rises, the impedance of the high frequency power circuit rises, resulting in a reduction of the effective power consumed in the plasma space. Further, in an apparatus in which a plurality of plasma chambers are connected, there is a drawback that effective power consumed in a plurality of plasma spaces is different. The present invention has been made in view of the above problems, and directly grasps the high frequency power applied to the plasma excitation electrode (cathode electrode) directly, and controls the power to a predetermined set value to stabilize the power. Another object of the present invention is to provide a plasma processing apparatus capable of uniform plasma processing.

[0016]

In order to solve the above problems, a plasma processing apparatus according to the present invention comprises a plasma processing chamber having electrodes for exciting plasma, and a high frequency power for supplying high frequency power to the electrodes. A power source, an input terminal, and an output terminal, the high-frequency power source is connected to the input terminal via a high-frequency power feeder, and the electrodes are connected to the output terminal via a high-frequency power distributor. A plasma processing apparatus having a ground potential portion connected between output terminals and comprising a matching circuit for obtaining impedance matching between the plasma processing chamber and the high frequency power supply, wherein a current flowing through the power distributor. A current detecting means for monitoring the current, and a controlling means for controlling the output of the high frequency power source so that the current value detected by the current detecting means becomes a predetermined value. The control signal obtained by said control means and a plasma processing apparatus which includes a feedback circuit for feeding back the high frequency power supply or matching circuit for adjusting the power applied to the electrodes for exciting plasma.

With such a plasma processing apparatus, it is possible to directly and accurately grasp the high frequency power applied to the plasma excitation electrode and control it to a predetermined power for stable and homogeneous plasma processing.

In the plasma processing apparatus of the present invention, a current probe can be used as the current detecting means.
This is because the high frequency power can be accurately grasped with a simple device.

The plasma processing method of the present invention is a method of plasma processing using the above apparatus, in which the power applied to the electrodes for exciting the plasma is controlled to be maintained at a predetermined value. It was decided to process while processing. Specifically, the current flowing through the distributor of the high frequency power applied to the electrode for exciting the plasma is monitored by the current detecting means, and the plasma is controlled so that the current detected by the current detecting means becomes a predetermined value. The method of controlling the high frequency power applied to the electrodes for excitation was adopted.

According to such a plasma processing method, it is possible to maintain the uniformity of processing when etching, film-forming, sputtering or the like is performed.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail with reference to the drawings. (First Embodiment) FIG. 1 is a sectional view showing a schematic configuration of a first embodiment of a plasma processing apparatus of the present invention. The main configuration of the plasma processing apparatus of the present invention is the same as that of the conventional plasma processing apparatus shown in FIG. Therefore, parts having the same function are given the same numbers as in FIG. The plasma processing apparatus of the present invention differs from the conventional plasma processing apparatus shown in FIG. 3 in that a current detecting means is attached to a distributor to detect a high frequency current, and the high frequency current applied to the plasma excitation electrode is utilized. This is the point that is controlled to be a predetermined value. Therefore, this control circuit will be mainly described.

As shown in FIG. 1, in the plasma processing apparatus of the present invention, a plasma excitation electrode 4 for exciting plasma.
The clamp meter 12 is attached to the power distribution body 3 for applying a high-frequency current, the magnitude of the current flowing through the power distribution body 3 is detected, and the detected current is input to the control circuit 15. The control circuit 15 calculates the difference between the detected current and the preset value input in advance, generates a signal for increasing or decreasing the output of the high frequency power supply 1 until the difference becomes zero (0), and outputs the signal. It feeds back to the power supply 1 or the matching circuit 2A. One method is to increase or decrease the output of the high frequency power source 1 based on the signal fed back to the high frequency power source 1.
The other method is to load the load capacitor 22 of the matching circuit 2A based on the signal fed back to the matching circuit 2A.
Or by changing the capacitance of the tuning capacitor 24,
The high frequency power applied to the plasma excitation electrode 4 is adjusted.
In this way, the current detection and the feedback of the control signal are repeated, and control is performed so that the difference between the detected current and the preset current value becomes zero (0).

An example of the structure of the control circuit 15 is shown in FIG.
In the example shown in FIG. 2, the clamp meter 12 including the coil 12a is attached to the power distribution body 3. The clamp meter 12 may be a fixed type that is attached in advance, or may be a movable type that opens and closes the coil 12a and is attached at a required time. A coil 12b having a different number of turns is attached to the coil 12a, the current of the coil 12a is converted and taken out, and the bridge circuit 18 detects it. The ammeter 19 of the bridge circuit 18 is controlled to be zero (0).
A control circuit for issuing a control signal in accordance with the instruction of the ammeter 19 is provided, and the control signal is fed back to the high frequency power supply or the matching circuit.

Next, a method of performing plasma processing using the plasma processing apparatus of the present invention will be described. The plasma processing method of the present invention employs a method of processing while controlling the electric power applied to the electrodes for exciting plasma so as to maintain a predetermined value. Specifically, the current flowing through the distributor of the high frequency power applied to the electrode for exciting the plasma is monitored by the current detecting means, and the current detected by the detected current detecting means is set to a predetermined value so that the plasma do. In the plasma processing method of the present invention, since the high frequency power applied to the plasma excitation electrode is directly detected and controlled to reach the set value, for example, the matching circuit is caused due to the temperature rise of the conductor when a high frequency current is passed. Even if the power loss fluctuates and the effective power actually consumed in the plasma space fluctuates, it is possible to follow up with compensation. Further, even in an apparatus in which a plurality of plasma chambers are connected, it is possible to uniformly hold the effective electric power consumed in the plurality of plasma processing spaces. According to such a plasma processing method, it is possible to maintain the uniformity of processing when performing etching processing, film forming processing, sputtering processing, or the like.

[0025]

[Function] The present invention is a plasma excitation electrode (cathode electrode).
The plasma processing apparatus is capable of performing stable and uniform plasma processing by directly and accurately grasping the high frequency power applied to the device and performing stable power control.

[0026]

According to the present invention, since the effective electric power consumed in the plasma space can be kept constant, a uniform and stable process can be carried out in the processes such as etching process, film forming process and sputtering process. It becomes possible to

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a plasma processing apparatus of the present invention.

FIG. 2 is a diagram illustrating an outline of a control method in the plasma processing apparatus of FIG.

FIG. 3 is a cross-sectional view showing a schematic configuration of an example of a conventional plasma processing apparatus.

FIG. 4 is a cross-sectional view showing a schematic configuration of another example of the conventional plasma processing apparatus.

[Explanation of symbols] 1 ... High frequency power source, 2 ... Matching box, 2A
・ ・ ・ ・ Matching circuit, 3 ・ ・ ・ Distributor, 4 ・ ・ ・ Plasma excitation electrode, 5 ・ ・ ・ ・ ・ ・ Shower plate, 6 ・ ・ ・ ・ ・ ・ Space, 7 ・ ・
.... Hole, 8 ..., susceptor electrode, 9 ... Insulator, 10
・ ・ ・ ・ ・ ・ Chamber wall, 11 ・ ・ ・ ・ Bellows, 12 ・ ・ ・ ・ Clamp meter, 13 ・ ・ ・ ・ Shaft, 15 ・ ・ ・ ・ Control circuit, 16 ・ ・.... Substrate, 17 ..., Gas introduction pipe, 18 ...
.... Bridge circuit, 19 ..., Ammeter, 22 ... Load capacitor, 23 ... Tuning coil, 24 ...
··· Tuning capacitor, 60 ··· Chamber, 7
5, 76 ... Plasma chamber, 101 ... Etching device main body, 102 ... Process control unit, 103 ...
・ ・ ・ Processing chamber, 104 ・ ・ ・ Semiconductor wafer, 111 ・ ・ ・
Variable resistor, 112 ... Ammeter.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tadahiro Omi             2-1-17 Yonegabukuro, Aoba-ku, Sendai City, Miyagi Prefecture             301 F-term (reference) 4K030 FA03 JA16 KA30 KA41                 5F004 AA01 BA04 BB18 BD03 BD04                       BD05 CB05                 5F045 AA08 AA19 DP03 EF05 EH14                       EH19 GB04

Claims (4)

[Claims] 1. A plasma processing chamber having an electrode for exciting plasma, a high frequency power source for supplying high frequency power to the electrode, an input terminal and an output terminal, and high frequency power feeding to the input terminal. The high frequency power source is connected via a body, the electrode is connected to the output terminal via a high frequency power distributor, a ground potential portion is connected between these input / output terminals, and the plasma processing chamber and the A plasma processing apparatus comprising: a matching circuit for obtaining impedance matching with a high-frequency power source, wherein a current detection means for monitoring a current flowing through the power distributor,
Control means for controlling the output of the high frequency power supply so that the current value detected by the current detection means becomes a predetermined value;
A plasma processing, comprising: a feedback circuit that feeds back a control signal obtained by the control means to a high frequency power source or a matching circuit to adjust the power applied to the electrode for exciting plasma. apparatus. 2. The plasma processing apparatus according to claim 1, wherein the current detecting means is a current probe. 3. A method of plasma processing using a plasma processing apparatus, characterized in that plasma processing is performed while controlling the electric power applied to the electrodes for exciting the plasma at a predetermined value. Plasma processing method. 4. The current flowing through the power distributor applied to the electrode for exciting the plasma is monitored by the current detecting means, and the plasma is excited so that the current detected by the detecting electric means has a predetermined value. The plasma processing method according to claim 3, wherein the electric power applied to the electrode for controlling is controlled.