JP2013187156A - Plasma processing apparatus and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a dielectric window 4 from being cut with ions of plasma 8 by reducing the plasma potential, and to increase the plasma density by processing the plasma potential while suppressing occurrence of RF oscillation thereof.SOLUTION: The plasma processing apparatus generating plasma by receiving high frequency power supply includes a high frequency power supply which supplies high frequency power, a plasma potential detection unit which detects the potential of plasma and outputs a detection signal corresponding to the level of the potential, and a control unit which controls the high frequency power being supplied from the high frequency power supply in response to the detection signal output from the plasma potential detection unit.

Description

  Embodiments described herein relate generally to a plasma processing apparatus that generates plasma by supplying high-frequency power (RF power) and plasma-processes an object to be processed, and a control method thereof.

  In the semiconductor manufacturing process, various processes such as etching and sputtering are performed. In these processes, for example, plasma processing apparatuses such as RIE and CVD are used, and as these plasma processing apparatuses, inductively coupled plasma processing apparatuses are often used. Such a plasma processing apparatus generates a plasma in the chamber by supplying a reactive gas into the chamber and a high-frequency power to the antenna, and plasma-treats an object to be processed such as a semiconductor substrate disposed in the chamber. To do.

JP-A-9-266098

In the inductively coupled plasma apparatus, an antenna is provided in a dielectric window provided in the chamber, and high frequency power is supplied from the antenna into the chamber through the dielectric window. However, the antenna has a capacitive coupling component, and this capacitive coupling component increases the self-bias voltage generated in the dielectric window, and the dielectric window is scraped by plasma ions.
In addition, RF vibration of the plasma potential is also caused by the capacitive coupling component, and this RF vibration leads to an increase in plasma potential and a decrease in plasma density. For this reason, when a plurality of inductively coupled plasma devices are installed, if the oscillation of the plasma potential differs between these devices, the plasma density may vary, and as a result, the process performance may be different among the devices. ing.

  According to the embodiment, in the plasma processing apparatus that generates plasma by supplying high-frequency power and performs plasma processing, the high-frequency power source that supplies the high-frequency power, and the potential of the plasma is detected to correspond to the height of the potential A plasma potential detector that outputs a detection signal; and a controller that controls the high-frequency power supplied from the high-frequency power source according to the detection signal output from the plasma potential detector.

The block diagram which shows the plasma processing apparatus of 1st Embodiment. FIG. 3 is a structural diagram showing attachment of a probe in the apparatus. The figure which shows adjustment of the phase of the 1st high frequency electric power and the 2nd high frequency electric power in the apparatus. The block diagram which shows the plasma processing apparatus of 2nd Embodiment. The block diagram which shows the plasma processing apparatus of 3rd Embodiment. The block diagram which shows the plasma processing apparatus of 4th Embodiment.

[First Embodiment]
Hereinafter, a first embodiment will be described with reference to the drawings.
FIG. 1 shows a configuration diagram of a plasma processing apparatus. This plasma processing apparatus is, for example, an inductively coupled plasma apparatus. This plasma processing apparatus can also be applied to various processes such as etching and sputtering.
A lower electrode 2 is provided in the chamber 1. A semiconductor wafer 3 is placed on the lower electrode 2. A dielectric window 4 is provided on the upper portion of the chamber 1. An antenna 5 is provided on the upper surface of the dielectric window 4. A first high frequency power source 6 is connected to the lower electrode 2, and a second high frequency power source 7 is connected to the antenna 5. These high frequency power sources 6 and 7 each output high frequency power of 13.56 MHz. The first high frequency power source 6 supplies high frequency power to the lower electrode 2, and the second high frequency power source 7 supplies high frequency power to the antenna 5. To supply. The antenna 5 has one end connected to the second high-frequency power source 7 and the other end grounded.

  The chamber 1 is supplied with a reaction gas and a high frequency power is supplied to the lower electrode 2 and the antenna 5 to generate plasma 8. The plasma 8 generates plasma 8 on the semiconductor wafer 3. Processing such as etching and sputtering is performed.

  A probe 10 as a plasma potential detector is inserted into the chamber 1. The probe 10 detects the potential of the plasma 8 generated in the chamber 1 and outputs a detection signal corresponding to the height of the potential. The intensity of the detection signal output from the probe 10 is proportional to the magnitude of the RF oscillation (voltage) of the potential of the plasma 8.

FIG. 2 shows the mounting structure of the probe 10. The side wall 1a of the chamber 1 is provided with a probe hole 1b. A probe 10 is inserted into the probe hole 1b. The probe hole 1b and the probe 10 are kept airtight.
The probe 10 includes a dielectric tube 11 and a coaxial cable 12 disposed in the dielectric tube 11. The dielectric tube 11 is formed with a dielectric window 11a for detecting the potential of the plasma 8 at the head portion thereof. The coaxial cable 12 includes a central conductor 13 and a hollow cylindrical body 14 disposed around the central conductor 13. The hollow cylinder 14 is made of an insulator and a conductor, and the conductor is grounded. Note that stray capacitances C <b> 1 and C <b> 2 exist between the center conductor 13 and the plasma 8. The coaxial cable 12 is connected to the control unit 15 and transmits a detection signal output from the probe 10 to the control unit 15.

The control unit 15 supplies the reaction gas into the chamber 1 and controls the first and second high-frequency power sources 6 and 7 to supply high-frequency power to the lower electrode 2 and the antenna 5, respectively. The plasma 8 is generated, and the plasma 8 is used to control the semiconductor wafer 3 to perform plasma processing such as etching or sputtering.
The control unit 15 receives a detection signal output from the probe 10 and controls the high-frequency power supplied from the first and second high-frequency power sources 6 and 7 in accordance with the detection signal. Specifically, the control unit 15 adjusts the phase difference between the high frequency powers output from the first and second high frequency power supplies 6 and 7 so as to minimize the intensity of the detection signal output from the probe 10. . For example, as shown in FIG. 3, when the high-frequency power output from the first high-frequency power source 6 is P1, and the high-frequency power output from the second high-frequency power source 7 is P2, the control unit 15 determines that the high-frequency power P1 is The phase between the first high-frequency power P1 and the second high-frequency power P2 output from the first and second high-frequency power supplies 6 and 7 is set so that the phase difference with the second high-frequency power P2 is 180 °. Adjusted.

Next, plasma processing control in the apparatus configured as described above will be described.
The reaction gas is supplied into the chamber 1, and the high frequency power supplies 6 and 7 output high frequency power of 13.56 MHz, respectively. Among these, the high frequency power source 6 supplies high frequency power to the lower electrode 2, and the high frequency power source 7 supplies high frequency power to the antenna 5. As a result, plasma 8 is generated inside the chamber 1, and plasma processing such as etching or sputtering is performed on the semiconductor wafer 3 by the plasma 8.
The probe 10 detects the potential of the plasma 8 generated in the chamber 1 and outputs a detection signal proportional to the magnitude of the RF vibration of the potential. This detection signal is transmitted to the control unit 15.

  The control unit 15 receives the detection signal output from the probe 10 and sets the phase difference between the high-frequency powers output from the first and second high-frequency power sources 6 and 7 so as to minimize the intensity of the detection signal. adjust. For example, the control unit 15 is output from the first and second high frequency power supplies 6 and 7 so that the phase difference between the high frequency power P1 and the second high frequency power P2 is 180 ° as shown in FIG. The phases of the high frequency power P1 and the second high frequency power P2 are adjusted. As a result, when the phase difference between the high frequency power P1 and the second high frequency power P2 reaches 180 °, the vibrations of the high frequency power P1 and the second high frequency power P2 cancel each other, and the potential of the plasma 8 is reduced. The magnitude of the RF vibration is minimized.

  When the RF oscillation of the plasma potential is small, the plasma potential (DC component) tends to decrease. When the plasma potential is low, the energy loss of ions on the side wall 1a of the chamber 1 is reduced, so that the plasma generation efficiency is improved and the plasma density is increased. Thereby, it is possible to increase the plasma density by minimizing the RF oscillation of the plasma potential.

  As described above, according to the first embodiment, the level of the high-frequency power output from the first and second high-frequency power supplies 6 and 7 is minimized so that the intensity of the detection signal output from the probe 10 is minimized. Since the phase difference is adjusted, it is possible to increase the plasma density by suppressing the generation of RF oscillation of the plasma potential and lowering the plasma potential. Furthermore, variation in plasma density among a plurality of plasma processing apparatuses can be reduced.

  Generally, in a mass production process of semiconductor manufacturing, a semiconductor wafer is often manufactured by arranging a plurality of plasma processing apparatuses in the same process. In this case, if the RF oscillation of the plasma potential is different for each plasma processing apparatus, it can be a factor that causes variations in the plasma density of each plasma processing apparatus. The difference between the plasma processing apparatuses of the RF vibration is due to the phase shift of both power sources of the first and second high-frequency power sources 6 and 7 and the variation of the capacitive coupling components of the antenna 5 and the lower electrode 2 between the devices. Although this is considered to occur, it is possible to reduce the variation in plasma density among the plasma processing apparatuses by minimizing the RF oscillation component of the plasma potential as in this embodiment.

[Second Embodiment]
Next, a second embodiment will be described with reference to the drawings. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
FIG. 4 shows a configuration diagram of the plasma processing apparatus. Two antennas 5 are provided from the viewpoint of controlling the plasma density distribution. That is, the antenna 5 is provided with a first antenna 5-1 and a second antenna 5-2. These antennas 5-1 and 5-2 are connected to two systems of high-frequency power sources, that is, the first antenna 5-1 is connected to the first high-frequency power source 7-1, and is connected to the second antenna 5-2. Is connected to a second high-frequency power source 7-2.

  These high frequency power supplies 7-1 and 7-2 each output high frequency power of 13.56 MHz, and the first high frequency power supply 7-1 supplies high frequency power to one end of the first antenna 5-1. The second high frequency power supply 7 supplies high frequency power to one end of the second antenna 5-2. The other ends of the first and second antennas 5-1 and 5-2 are grounded. Note that the first high-frequency power source 6 is not connected to the lower electrode 2. It is not always necessary to connect the first high-frequency power source 6 to the lower electrode 2.

  The control unit 15 receives a detection signal output from the probe 10 and controls high-frequency power supplied from the first and second high-frequency power sources 7-1 and 7-2 in accordance with the detection signal. Specifically, the control unit 15 determines the level of the high-frequency power output from the first and second high-frequency power sources 7-1 and 7-2 so as to minimize the intensity of the detection signal output from the probe 10. Adjust the phase difference. For example, the control unit 15 causes the phase difference between the high frequency power output from the first high frequency power supply 7-1 and the second high frequency power output from the second high frequency power supply 7-2 to be 180 °. The phases of the first high-frequency power and the second high-frequency power output from the first and second high-frequency power supplies 6 and 7 are adjusted.

Next, plasma processing control in the apparatus configured as described above will be described.
Plasma 8 is generated inside the chamber 1, and plasma processing such as etching or sputtering is performed on the semiconductor wafer 3 by the plasma 8.
In this state, the probe 10 detects the potential of the plasma 8 generated in the chamber 1 and outputs a detection signal proportional to the magnitude of the RF vibration of the potential. This detection signal is transmitted to the control unit 15.

  The control unit 15 receives the detection signal output from the probe 10 and the high-frequency power output from the first high-frequency power supply 7-1 and the second high-frequency power supply 7 so as to minimize the intensity of the detection signal. -2 and the second high-frequency power output from the first and second high-frequency power supplies 7-1 and 7-2 so that the phase difference from the second high-frequency power output from -2 is 180 °. And adjust the phase. As a result, when the phase difference between these high frequency powers reaches 180 °, the vibrations of these high frequency powers cancel each other, and the magnitude of the RF vibration of the potential of the plasma 8 is minimized.

  As described above, according to the second embodiment, the first and second antennas 5-1 and 5-2 are provided, and the first signal is output so as to minimize the intensity of the detection signal output from the probe 10. And the second high frequency power sources 6 and 7 connected to the second antennas 5-1 and 5-2, respectively, to adjust the phase difference between the high frequency powers output from the first and second high frequency power sources 6 and 7, respectively. The plasma density can be increased by reducing the plasma potential. Furthermore, variation in plasma density among a plurality of plasma processing apparatuses can be reduced. Thereby, similarly to the first embodiment, the plasma generation efficiency is improved and the plasma density is increased. Thereby, it is possible to increase the plasma density by minimizing the RF oscillation of the plasma potential. In addition, it is possible to reduce variation in plasma density among a plurality of plasma processing apparatuses.

  Since no high frequency power source is connected to the lower electrode 2, no high frequency power is supplied to the lower electrode 2, RF vibration of the plasma potential can be reduced, and ion energy and electron energy with respect to the object 3 to be processed such as a semiconductor wafer. Can be reduced. As a result, it is possible to realize a semiconductor manufacturing process with little damage to the object 3 such as a semiconductor wafer.

[Third Embodiment]
Next, a third embodiment will be described with reference to the drawings. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
FIG. 5 shows a configuration diagram of the plasma processing apparatus. The antenna 5 has a high-frequency power source 7 connected to one end, and a variable capacitor 20 connected between the other end and the ground. The variable capacitor 20 varies the capacitance on the terminal end side when viewed from the high frequency power supply side of the antenna 5.

  The control unit 15 receives a detection signal output from the probe 10 and controls the variable capacitor 20 according to the detection signal. Specifically, the control unit 15 variably controls the capacitance of the variable capacitor 20 so as to minimize the intensity of the detection signal according to the detection signal output from the probe 10. That is, since the antenna 5 has an inductance component, by changing the capacitance of the variable capacitor 20 connected to the antenna 5, an LC circuit composed of the inductance component (L) and the variable capacitor (C) 20 in the antenna 5 can be used. The impedance value will be variable. By changing the impedance value, the control unit 15 minimizes the intensity of the detection signal according to the detection signal output from the probe 10. The variable capacitor 20 is provided with, for example, a drive mechanism for changing the variable capacitor 20, and the capacity is varied by the drive mechanism.

Next, plasma processing control in the apparatus configured as described above will be described.
Plasma 8 is generated inside the chamber 1, and plasma processing such as etching or sputtering is performed on the semiconductor wafer 3 by the plasma 8.
In this state, the probe 10 detects the potential of the plasma 8 generated in the chamber 1 and outputs a detection signal proportional to the magnitude of the RF vibration of the potential. This detection signal is transmitted to the control unit 15.
The control unit 15 receives the detection signal output from the probe 10 and variably controls the capacitance of the variable capacitor 20 so as to minimize the intensity of the detection signal.

  As a result, by changing the capacitance of the variable capacitor 20 connected to the antenna 5, the impedance value of the LC circuit composed of the inductance component (L) and the variable capacitor (C) 20 is changed and output from the probe 10. Depending on the detection signal, the intensity of the detection signal can be minimized.

  As described above, according to the third embodiment, since the capacitance of the variable capacitor 20 is variably controlled so as to minimize the intensity of the detection signal output from the probe 10, the self-bias voltage generated in the dielectric window. The plasma window can be increased by reducing the plasma potential and lowering the plasma potential by suppressing the generation of RF oscillation of the plasma potential without cutting the dielectric window 4 by the ions of the plasma 8. Thereby, the plasma generation efficiency is improved and the plasma density is increased. In addition, variation in plasma density among a plurality of plasma processing apparatuses can be reduced.

  Since no high-frequency power source is connected to the lower electrode 2, high-frequency power is not supplied to the lower electrode 2 as in the second embodiment, so that RF oscillation of the plasma potential can be reduced, and a semiconductor wafer or the like It is possible to reduce the ion energy and the electron energy of the object 3 to be processed, and to realize a semiconductor manufacturing process with little damage to the object 3 such as a semiconductor wafer.

[Fourth Embodiment]
Next, a fourth embodiment will be described with reference to the drawings. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
FIG. 6 shows a configuration diagram of the plasma processing apparatus. This figure is a view of the chamber 1 as viewed from above, and the semiconductor wafer 3 and the like are omitted.
In the chamber 1, a plurality of antenna electrodes, for example, antenna electrodes 30-1 to 30-4 divided into four are provided. These antenna electrodes 30-1 to 30-4 are connected to high-frequency power sources 31-1 to 31-4, respectively. A probe 10 is inserted into the chamber 1.

  The control unit 15 receives a detection signal output from the probe 10 and controls each high frequency power supplied from each high frequency power supply 31-1 to 31-4 in accordance with the detection signal. Specifically, the control unit 15 adjusts the phase difference between the high-frequency powers output from the high-frequency power sources 31-1 to 31-4 so as to minimize the intensity of the detection signal output from the probe 10.

With such an apparatus, plasma 8 is generated inside the chamber 1, and plasma processing such as etching or sputtering is performed on the semiconductor wafer 3 by the plasma 8.
In this state, the probe 10 detects the potential of the plasma 8 generated in the chamber 1 and outputs a detection signal proportional to the magnitude of the RF vibration of the potential. This detection signal is transmitted to the control unit 15.
The control unit 15 receives the detection signal output from the probe 10 and outputs it from each of the high frequency power sources 31-1 to 31-4 so as to minimize the intensity of the detection signal, that is, minimize the RF oscillation of the plasma potential. Since the phase difference of the high frequency power to be adjusted is adjusted, the vibrations of the respective high frequency powers cancel each other, and the magnitude of the RF vibration of the potential of the plasma 8 can be minimized.

  As described above, according to the fourth embodiment, the phase difference between the high-frequency powers output from the high-frequency power sources 31-1 to 31-4 so as to minimize the intensity of the detection signal output from the probe 10. Therefore, as in the first embodiment, the plasma generation efficiency is improved and the plasma density is increased. Thereby, it is possible to increase the plasma density by minimizing the RF oscillation of the plasma potential. In addition, it is possible to reduce variation in plasma density among a plurality of plasma processing apparatuses.

According to each of the above embodiments, it is possible to provide a plasma processing apparatus and a control method therefor that can suppress the generation of RF oscillation of the plasma potential and lower the plasma potential to increase the plasma density.
Furthermore, according to each of the above-described embodiments, it is possible to provide a plasma processing apparatus and a control method thereof that can reduce variations in plasma density among a plurality of plasma processing apparatuses.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  1: chamber, 1a: chamber side wall, 1b: probe hole, 2: lower electrode, 3: semiconductor wafer, 4: dielectric window, 5: antenna, 6: first high frequency power supply, 7: second high frequency Power supply, 8: Plasma, 10: Probe, 11: Dielectric tube, 11a: Dielectric window, 12: Coaxial cable, 13: Center conductor, 14: Hollow cylindrical body, 15: Control unit, 5-1: First Antennas, 5-2: second antenna, 7-1: first high frequency power supply, 7-2: second high frequency power supply, 20: variable capacitor, 30-1 to 30-4: electrode for antenna, 31- 1-31-4: High frequency power supply.

Claims (5)

In a plasma processing apparatus that generates plasma by supplying high-frequency power and performs plasma processing,
A high frequency power supply for supplying the high frequency power;
A plasma potential detector that detects the potential of the plasma and outputs a detection signal corresponding to the height of the potential;
A control unit for controlling the high-frequency power supplied from the high-frequency power source according to the detection signal output from the plasma potential detection unit;
A plasma processing apparatus comprising: A plurality of the high-frequency power sources are provided,
The control unit controls each phase of the high-frequency power supplied from the plurality of high-frequency power sources so that the output signal of the plasma potential detection unit is minimized.
The plasma processing apparatus according to claim 1. A plurality of antennas for generating the plasma;
A plurality of the high-frequency power supplies for supplying the high-frequency power to the plurality of antennas;
The control unit controls each phase of the high-frequency power supplied from the plurality of high-frequency power sources so that the output signal of the plasma potential detection unit is minimized.
The plasma processing apparatus according to claim 1. In a plasma processing apparatus that generates plasma by supplying high-frequency power and performs plasma processing,
An antenna for generating the plasma;
A variable capacitor connected to the antenna;
A plasma potential detector that detects the potential of the plasma and outputs a detection signal corresponding to the height of the potential;
A control unit for controlling the variable capacitor according to the detection signal output from the plasma potential detection unit;
A plasma processing apparatus comprising: In a plasma processing control method for generating plasma by supplying high-frequency power from a high-frequency power source and performing plasma processing,
Detecting the potential of the plasma and controlling the high-frequency power supplied from the high-frequency power source in accordance with the height of the potential;
The plasma processing control method characterized by the above-mentioned.

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