JP5582809B2 - Plasma generator - Google Patents

Description

  The present invention relates to a plasma generator suitable for use in processing, sterilization, and sterilization such as etching, sputtering, and film formation by vapor deposition in a manufacturing process of a semiconductor element or the like.

  Since a plasma generator using high frequency has radiation of interference radio waves emitted from the apparatus, it uses a frequency band (ISM band) that is stipulated by law and has a strict regulation of interference radio waves. Even if it is called a band, the bandwidth of the ISM band is narrow, and only a single frequency (13.56 MHz, 27.12 MHz, 40.68 MHz, etc.) is permitted.

  When high-frequency power is sent to the plasma, impedance matching between the high-frequency source and the plasma that is the load is required. To use this at a single frequency, that is, when the frequency is not allowed to move, In addition, it is necessary to match the high frequency source by adding or decreasing the value of the capacitor or coil to the electrical quantities of plasma that is the load. Matching BOX plays this role. Matching BOX is designed to move the capacitors and coils mechanically while measuring the reflected wave (standing wave ratio) by adding a directional coupler or the like to the feeder line (coaxial cable), and to optimize the value (matching can be achieved) Value).

Of course, there are manual ones, but an automatic one using a motor or the like is generally used (see, for example, Patent Document 1).
However, there is a method that can perform impedance matching without using a matching BOX. It is a way to move the frequency. However, this deviates from the conditions for using a single frequency, and measures to prevent jamming are required.

  As a plasma generator, a plasma generating electrode is provided in a vacuum chamber, and a separately excited high frequency oscillator for supplying a high frequency to the plasma electrode is connected by a coaxial cable, and impedance matching is performed between the plasma generating electrode and the separately excited high frequency oscillator. 2. Description of the Related Art A plasma generator using a fixed (single) frequency provided with a matching unit (matching BOX) for taking out a signal is known. (For example, FIGS. 7 to 10)

JP 2002-151417 A

<Prior Art Shown in FIGS. 7 to 10>
High-frequency energy is supplied from a high-frequency oscillator to the plasma chamber via a coaxial cable. It is generally known that from the coaxial feeder, electromagnetic radiation in the normal mode does not occur, but radiation in the common mode occurs, and radiation is stronger when there is a mismatch and there is a reflected wave.
Since the plasma state in the chamber changes constantly, it is necessary to match the impedance with a matching unit (matching BOX).

In the case of FIG. 7, the matching between the high-frequency oscillator and the matching BOX can be made, but the matching between the chamber and the matching BOX is designed so that the chamber including the plasma has the same characteristic impedance as the coaxial cable. However, since the plasma fluctuates, it is not always possible to achieve matching, and common mode radiation occurs, and a reflected wave that intensifies it also occurs.
If the chamber and the matching BOX are integrated as shown in FIG. 8 and the feeding line between them is omitted, the problem as shown in FIG. 7 does not occur.

However, in both cases of FIGS. 7 and 8, it is unavoidable that mismatches are generated either automatically or manually while the mismatch is detected and matching is performed by the matching BOX. Occurs and a reflected wave that strengthens it also occurs.
In the coaxial power supply, the metal that becomes the coaxial outer skin is connected to the chamber metal. Since the chamber is surrounded by a metal wall (conductor), the electromagnetic wave inside the chamber does not leak outside. However, a potential difference is generated on the inner wall of the chamber due to the high-frequency current return path starting from the coaxial core wire. Since the current path changes depending on the plasma state, the potential distribution on the inner wall of the chamber, which is a conductor, also changes. Since this inner wall and chamber metal are one conductor, if a part of the chamber is grounded (grounded), a potential difference is created between other chamber parts due to the potential distribution of the inner wall, which becomes a common mode high frequency source. Radiation to the outside occurs. This is the same result no matter where the earth is placed on the chamber metal.
Further, even if grounding is separately provided on the oscillator side as shown in FIG. 10, the presence or absence of fluctuation in the potential of the chamber does not change, and if both are grounded, a loop antenna is formed, resulting in worse radiation.

As described above, in the conventional method, the chamber metal does not serve as electromagnetic shielding (shielding), and therefore, radiation of disturbing radio waves to the outside occurs.
If a shield effect is to be obtained, the whole chamber is submerged in earth, or the whole chamber, the power supply line, and the oscillator are covered with another metal (metal envelope) insulated so as not to generate a current return path. (For example, covering the entire room where the apparatus is installed is covered with metal). If this is grounded, the radiation of the interfering radio waves can be prevented, but there is a problem that the cost increases.
For these reasons, conventional high-frequency plasma generators generate radiation of jamming radio waves. Therefore, ISM bands (13.56 MHz, 27.12 MHz, 40.68 MHz, 900 MHz band, 2.45 GHz band, 5.7 GHz), which have moderate restrictions on jamming radio waves. Obi etc.).

  As shown in FIG. 9, the conventional apparatus uses chamber (vacuum envelope) metal as an electrode. The high-frequency current fed coaxially starts from the coaxial core line side, that is, the electrode A, and returns to the coaxial outer metal through the generated plasma and the chamber wall (B electrode) which is the counter electrode. Since the electrodes to be discharged do not have the same shape, the electric field distribution is biased and complicated. When the DC component is cut from the coaxial core wire (A electrode side) with a capacitor, the positive ionic molecules gather on the A electrode side to form a sheath, and the A electrode is charged to a negative potential. Presents a phenomenon. This is called a plasma self-bias phenomenon, which is known as a special phenomenon during plasma generation, and is actively used for film formation.

Since positive ion molecules fly from the plasma sheath toward the A electrode, which is a negative electrode, when a work is placed on the A electrode side, the ion molecules collide with the work, and deposit and form a film. The workpiece may be a conductor such as metal or an insulator such as plastic. This is the principle of the film forming method using plasma.
The good point of this method is that if a DC component cut capacitor is added, a self-bias phenomenon occurs naturally, and a potential difference is generated between the plasma sheath and the workpiece, and the above film formation becomes possible. .
The thickness, adhesion, penetration depth, and the like of the film to be formed are controlled by the plasma density, the workpiece temperature processing time, and the like.

As shown in FIG. 9, the high-frequency current starting from the electrode A passes through the plasma and the chamber (electrode B), but the electric field distribution is complicated, so that the current path is I, II, III, etc. depending on the state of the plasma. It changes every time. For this reason, the voltage generated by the resistance of plasma or chamber metal is constantly fluctuating. When one point of the chamber metal is grounded (zero potential), the potential on the surface of the chamber metal other than the ground point is fluctuating (occurrence of common mode). A portion surrounded by a broken line that is electrically connected to the outer surface of the coaxial line also causes a potential fluctuation. That is, it acts as an antenna for common mode radiation.
The same can be said for any grounding point. Further, even if the oscillator side is grounded as shown in FIG. 10, the presence or absence of potential fluctuation does not change, and if both are grounded, a loop antenna is formed, resulting in worse radiation.

  When using a high frequency for plasma generation, a matching BOX is required if the frequency is fixed. If the plasma density is increased or the high frequency output is increased in order to expand the processing speed and processing range, the change in the plasma state becomes more intense due to the temperature unevenness in the streamer and chamber, and the electrical impedance is abrupt. In the operation of the matching BOX that mechanically matches the change, there is a limit in response speed, and there is a problem that the control cannot catch up. On the other hand, since the method of adjusting the impedance by changing the frequency is electrical, it can operate at high speed and with precision. Moreover, if self-excited oscillation is used, there is no need for a device for detecting reflected waves or a device that moves the matching mechanism, and matching can be achieved under its own oscillation conditions, so control is simple, compact, low cost, and simple plasma generation. A device can be constructed. This self-excited plasma generator is not only suitable for etching and sputtering deposition equipment used in the semiconductor manufacturing process, but it is also easy to control, compact, low cost, and simple. It is also extremely suitable for plasma generators used for sterilization.

However, the problem here is the method of moving the frequency, so there is a problem that it cannot be put into practical use as it is.
On the other hand, the deposition method using self-bias is a form that makes good use of natural phenomena, but the bias voltage cannot be adjusted, so the film component, thickness, adhesion, penetration depth, etc. can be adjusted for plasma density. (In other words, adjustment of internal pressure and high-frequency output, etc.) Rough process conditions such as work temperature (heated separately with a heater), processing time, etc. are all linked, so individual precise control cannot be performed. There is a bug.

  Furthermore, it is necessary to once clean the inside of the chamber so that undesired substances (impurities) are not mixed during film formation. For cleaning, it is necessary to pull the inside of the chamber to a high vacuum to discharge impurities together with the gas, or to replace the internal gas with a clean gas. Even once, the chamber, vacuum pump, etc. must be able to withstand a high vacuum or be used to reach this high vacuum. In addition, since the replacement operation requires gas exchange to every corner of the chamber, there is a problem that the work takes time and productivity is deteriorated.

Since the conventional metal chamber does not serve as an electromagnetic shield (shield), if the shield effect is to be obtained, a shield body that covers the entire chamber, the power supply line, and the oscillator with another metal and grounds it. It is necessary to make it a separate enclosure.
In the prior art, since the chamber serves as an electrode, a vapor deposition film that is electrically attracted to the inner wall of the chamber is laminated. Therefore, the inner wall of the chamber tends to become dirty and becomes a tough vapor deposition film. There was a problem that it took time and effort to remove.

Positive ions and radicals collide with the work surface placed on the work table and chemically react, but there is a difference in reaction between the direction of travel and the direction not traveled. (This is called anisotropic reaction.)
The anisotropic etching process is a so-called “deep groove process”, and the reaction in front of the ions in the traveling direction is large and the reaction on the side is small. Therefore, more accurate etching along the resist pattern is possible. This is an indispensable processing method for manufacturing parts in semiconductors and MEMS.

  A lower atmospheric pressure in the chamber is better for taking advantage of the characteristics of anisotropic etching. This is because the ion free path can be increased because the mean free path of ions becomes large. However, since the plasma density decreases at low pressure, the overall etching rate decreases. In order to prevent this, it is sufficient to increase the radio frequency (RF) power and increase the plasma density. Conventionally, however, increasing the radio frequency (RF) power increases the plasma density, but also increases the ion acceleration voltage due to self-bias and increases the damage to the workpiece. (Increase in ion bombardment) Therefore, in order to improve such problems, a method has been proposed in which high-density plasma is separately generated and ion acceleration can be separated and controlled. Magnetron RIE, ECR, helicon wave, and surface wave (microwave) plasma methods are the mainstream etching methods.

  However, these devices have a problem that they are much more complicated and costly than conventional counter electrode type devices (CCP devices).

The present invention has been made in view of the drawbacks of the prior art as described above,
A first object of the present invention is to provide a plasma generating apparatus in which electromagnetic radiation does not occur and a strong vapor deposition film is not formed or etched on the inner wall of a chamber.

  The second object of the invention is that no electromagnetic radiation occurs, no strong vapor deposition film is formed or etched on the inner wall of the chamber, and the inside of the chamber can be cleaned without re-vacuum or replacement of gas, and the next vapor deposition can be performed as it is. An object of the present invention is to provide a plasma generator.

  The third object of the present invention is to provide a plasma generating apparatus that realizes an etching process by an anisotropic reaction with an uncomplicated structure that enables low cost.

  The fourth object of the invention is to perform impedance matching electrically, that is, by frequency, and naturally (self) matching without any matching control from the outside by a self-excited oscillation method, and also enables high-speed and precise control. It aims at providing the plasma generator which becomes.

In order to achieve the above object, the present invention is configured as follows.
<Invention of Claim 1>
A chamber made of a conductive member grounded in a zero potential state, in which high-frequency current does not flow ;
A first plasma generating electrode and a second plasma generating electrode which are provided in an insulating state in the chamber and generate plasma between the electrodes ;
A high frequency oscillating unit having an oscillator and a transformer for supplying electric power to high frequency power and supplying the first plasma generating electrode and the second plasma generating electrode ;
A high frequency oscillation part shield cover made of a conductive member, which is integrated in the chamber in a conductive form and is provided so as to cover the high frequency oscillation part;
A middle point connection formed by grounding the middle point of the transformer and the chamber at a potential of 0;
A shield body that is formed by the chamber and the high-frequency oscillation unit shield cover for preventing generation of noise radiation due to high-frequency generated in the high-frequency oscillation unit and the chamber;
An oscillator power supply for supplying power to the oscillator in an insulated state from the shield body;
A workpiece electrode forming portion for providing a workpiece in an electrode state provided in the chamber in an insulating state with the chamber;
A plasma generating apparatus comprising the shield body and an insulated bias forming DC power source for applying a bias voltage to the work electrode forming portion.
“Work electrode forming part” means that when the work is conductive and is held without being insulated, the work itself becomes an electrode and becomes attractive vapor deposition by the work itself, and when the work is non-conductive, it is in an insulated state. In this case, the workpiece itself is not brought into an electrode state, and a part of ions that are attracted and flew by the workpiece electrode forming portion is deposited on the workpiece surface, both of which are included in the technical scope.
“Power” of “change power to high frequency power” has various power forms such as DC power, AC power, and pulse power.

<Invention of Claim 2>
2. The plasma according to claim 1, wherein the first plasma generating electrode and the second plasma generating electrode are symmetrical electrodes that are balanced power supply, and a middle point of the symmetrical electrodes is grounded. Ma generator.

<Invention of Claim 3>
The plasma generation apparatus according to claim 1, wherein the high-frequency oscillation unit is a self-excited high-frequency oscillator.

<Invention of Claim 4>
A dummy electrode for attracting positive ions in an insulated state from the chamber is provided in the chamber, and a bias forming DC power source that is insulated from the shield body and applies a bias voltage to the dummy electrode is provided. The plasma generator according to any one of claims 1 to 3.

<Invention of Claim 5>
A work coil in which a high-frequency current that forms a part of the induction heating device flows is provided in the chamber, and a vaporization member holding portion that holds a plurality of vaporization members that are vaporized by the induction heating by the work coil is provided to vaporize the gas. 5. The plasma generating apparatus according to claim 1, further comprising a vaporizing member moving unit configured to move the member and set the heating position of the work coil.
“Vaporization” includes both evaporation and sublimation.

As is clear from the above description, the present invention has the following effects.
<Effect of the Invention of Claim 1>
A chamber made of a conductive member grounded in a zero potential state, in which high-frequency current does not flow ;
A first plasma generating electrode and a second plasma generating electrode which are provided in an insulating state in the chamber and generate plasma between the electrodes ;
A high frequency oscillating unit having an oscillator and a transformer for supplying electric power to high frequency power and supplying the first plasma generating electrode and the second plasma generating electrode ;
A high frequency oscillation part shield cover made of a conductive member, which is integrated in the chamber in a conductive form and is provided so as to cover the high frequency oscillation part;
A middle point connection formed by grounding the middle point of the transformer and the chamber at a potential of 0;
A shield body that is formed by the chamber and the high-frequency oscillation unit shield cover for preventing generation of noise radiation due to high-frequency generated in the high-frequency oscillation unit and the chamber;
An oscillator power supply for supplying power to the oscillator in an insulated state from the shield body;
A workpiece electrode forming portion for providing a workpiece in an electrode state provided in the chamber in an insulating state with the chamber;
Since the plasma generating apparatus is characterized by comprising the shield body for applying a bias voltage to the work electrode forming portion and an insulated DC power source for bias formation, the following effects can be obtained.

(1) The present invention is a configuration in which a shield body is formed by a chamber and a high frequency oscillation part shield cover integrated with the chamber in a conductive form, and the shield body and the energy supply source are connected at any frequency. Since there is no power supply line at all, there is no power supply line, so there is no interference radio wave radiation from the power supply line, so normal mode radio wave radiation and common mode radio wave radiation do not occur. ing. Therefore, a plasma generating apparatus that does not cause radio wave interference without requiring a separate enclosure covering the entire apparatus is realized.
In other words, the present invention is a plasma generation mechanism that is free of interference radio wave radiation (electromagnetic radiation) in principle. The idea of a plasma generation mechanism that does not emit interference radio waves and a plasma generation method that does not generate interference radio waves is the technical idea of the present invention.
In addition, it is possible to realize a plasma generator and method that do not emit jamming radio waves in both self-excited oscillation and separately-excited oscillation, and because frequency matching is possible, a plasma generator and method that do not require a matching BOX as in the past are realized. The effect of doing.

(2) The above (1) realizes a plasma generation mechanism in which unnecessary radiation (radiation of disturbing radio waves) is not generated in principle. The electrical conditions vary depending on the volume, distribution state, electron density, etc. of the plasma generated. However, in the present invention, the frequency is not restricted by the ISM band or the like, is not restricted by the fixed frequency, or is self-excited. A plasma generator capable of freely changing the frequency and injection power that can be varied according to the application is realized.

(3) According to the above (1), since the chamber is not configured as a one-sided electrode, when performing vapor deposition or etching, there is little influence of adhesion and dissociation of ions on the inner wall of the chamber, and the inner wall surface of the chamber is not easily contaminated. Realize an easy-to-use device. If the deposited material is expensive, the consumption amount can be reduced and the recovery from the chamber wall can be facilitated.

  (4) According to the above (2), not only the frequency selection for the purpose of use but also the frequency selection for manufacturing the device can be freely performed. When manufacturing the device, it is possible to change the frequency depending on the size of the workpiece, the discharge power, etc., and also due to restrictions on procured parts and manufactured parts.

  (5) A dummy electrode can be separately provided based on the same idea as the work electrode forming portion according to (1). This is because when no voltage is applied to the work electrode forming portion and a negative voltage is applied to the dummy electrode, + ions are not attracted to the work electrode forming portion but are attracted to the dummy electrode. As a result, the remaining ions in the chamber can be attracted to the dummy electrode, so that the chamber can be cleaned. This makes it possible to perform the transition time to the deposition film formation of other members in a short time without replacing the gas in the chamber as in the prior art and repeating the high vacuum operation, and one of the plasma generators of the present invention. In the plasma vapor deposition film forming apparatus which is a form, a film forming apparatus having high efficiency and high production capacity is realized.

  (6) In the present invention, the high frequency power (RF power) and the accelerating bias voltage can be adjusted separately, so that the plasma density can be increased by increasing the high frequency power (RF power), and in the plasma. The speed of the positive ions (which may be negative ions) toward the work in the work electrode forming portion can be adjusted to the optimum or preferred speed by the voltage of the bias forming power source.

(7) Further, there is an effect that DC plasma can be generated by turning on the bias forming power source in a state in which high-frequency plasma is generated.
by this,
[A] The high-frequency oscillator is turned on and only high-frequency plasma is used.
[B] Use after generating high-frequency plasma, turning on the bias forming power source to generate DC plasma, and forming a mixed plasma state of high-frequency plasma and DC plasma,
[C] After generating the high frequency plasma, the bias forming power source is turned ON to generate DC plasma, the high frequency oscillation unit is turned OFF, and the DC plasma is used only.
It is possible to generate and use three patterns of plasma.

<Effects of Invention of Claim 2>
2. The plasma according to claim 1, wherein the first plasma generating electrode and the second plasma generating electrode are symmetrical electrodes that are balanced power supply, and a middle point of the symmetrical electrodes is grounded. Since the apparatus is a generator, the same effects as those of the first aspect of the invention can be obtained, and the following effects can be obtained.
That is, if an asymmetrical electrode is used, a high-frequency midpoint shift occurs, which may cause unnecessary radiation, and an avoidance means for avoiding this must be taken. By using a symmetric electrode (generally a pair of dipole electrodes), there is an effect that a high frequency midpoint shift is eliminated and a device free from unnecessary radiation is realized.

  In addition, since the plasma generated by the symmetric electrode (also called “balanced electrode” or “dipole electrode”) does not cause a self-bias phenomenon, a negative DC power supply is prepared between the work electrode forming portions to form the work electrode. By applying a bias voltage to the part, the same effect as the self-bias phenomenon conventionally used for film formation can be obtained, so the shield function of the shield body enables film formation on the workpiece while alive There is an effect.

In addition, anisotropic etching is a so-called “deep groove processing”, and the reaction in front of the ions in the traveling direction is large and the reaction on the side is small. Therefore, more accurate etching along the resist pattern is possible. . This is an indispensable processing method for manufacturing parts in semiconductors and MEMS.
A state that makes use of the characteristics of this anisotropic etching is superior in a low-pressure state that can increase the speed of ions, but if the pressure is too low, the plasma density decreases and the overall etching rate decreases.

However, in the present invention, the RF power (plasma density) and the acceleration voltage can be controlled separately. That is, even if the plasma density in the low-pressure state is increased by increasing the high-frequency power, the ion velocity resulting from the conventional self-bias phenomenon does not increase, and the positive electrode (which may be negative ions) work electrode formation portion Since the speed toward the surface can be made optimum or preferred by adjusting the negative voltage of a DC power source provided separately, the etching productivity can be improved and ion bombardment damage can be reduced.
In addition, an anisotropic etching apparatus in a low-pressure state using high-density plasma can be realized at a low cost by a simple configuration such as a conventional counter electrode type.

<Effect of the Invention of Claim 3>
Since the high-frequency oscillating unit is a plasma generator according to any one of claims 1, 2, characterized in that self-excited high-frequency oscillator, the invention described in any one of claims 1, 2 In addition to the same effects, the following effects are achieved.
In other words, self-excited oscillation performs matching by moving the electrical frequency, so it can be realized with a simple circuit configuration, and is much faster and more precise than the conventional method of mechanically moving the values of capacitors and coils. Since the matching operation can be performed and an expensive matching box is not required, high-speed precision control and a low-cost device can be realized.

<Effects of Invention of Claim 4>
A dummy electrode for attracting positive ions in an insulated state from the chamber is provided in the chamber, and a bias forming DC power source that is insulated from the shield body and applies a bias voltage to the dummy electrode is provided. Since it is a plasma generator of any one of Claims 1-3 characterized by these, While having the effect similar to the invention of any one of Claims 1-3, as next described There is an effect.
That is, by providing the dummy electrode, the dummy electrode and the work electrode forming portion are in one chamber. Since the floating ions are attracted to the negative voltage applied, for example, when the inside of the chamber is depressurized and the deposition of the substance A on the work is completed, the voltage application to the work electrode forming part is turned off and the dummy is Residual A substance ions are attracted (deposited) to the dummy electrode to which a negative voltage is applied to the electrode, and the inside of the chamber is cleaned quickly enough to be called instantaneously. Can be vaporized and ionized by plasma, and the B substance can be attracted (deposited) to the workpiece applied with a voltage to the workpiece electrode forming portion.

In this case, a B material film in which the A material is not mixed can be formed on the A material film. That is, a precise laminated film in which other substances are not mixed in each layer can be formed.
The negative DC power supply can be controlled freely by manual control or automatic control, so the workpiece or dummy electrode can be momentarily applied depending on the voltage strength, energization time, variable energization strength, and energization / disconnection timing. Thus, it is possible to control the adhesion intermittently or gradually so that the formation of the deposited film can be finely controlled.
In this regard, by providing a dummy electrode power source for the dummy electrode and separately providing a work electrode power source for the work electrode forming portion, voltage strength, energization time, energization are provided. Variable strength, timing of energization and cutting, etc. are controlled finely while applying voltage to both the dummy electrode and the work electrode formation part, for example, to form higher quality vapor deposition films and functional vapor deposition films It can be made possible.

When a non-target substance is present in the chamber, a negative voltage is applied to the dummy electrode so that the substance in the chamber adheres. This processing time is adjusted by adjusting the dummy bias voltage. (At this time, no negative voltage is applied to the work electrode, so no adhesion or film formation occurs.) In this way, cleaning at the time of film formation can be performed without high vacuum or gas replacement.
Furthermore, when this operation is applied during alloy deposition,
For example, a process such as cleaning-A substance film formation-cleaning-B substance film formation-cleaning-is possible, and high cleaning is performed in a short time before each process. Since the substance is controlled and deposited independently, not only the alloy composition becomes accurate, but also the thickness and depth of the film can be individually controlled accurately and with high quality.
In addition, in the plasma vapor deposition film forming apparatus which is one form of the plasma generating apparatus, a film forming apparatus having high efficiency and high production capacity is realized.

<Effects of Invention of Claim 5>
A work coil in which a high-frequency current that forms a part of the induction heating device flows is provided in the chamber, and a vaporization member holding portion that holds a plurality of vaporization members that are vaporized by the induction heating by the work coil is provided to vaporize the gas. The plasma generating apparatus according to any one of claims 1 to 4, further comprising: a vaporizing member moving means for moving a member and setting the heating position of the work coil. In addition to the same effects as the invention described in any one of Items 1 to 4, the following effects are achieved.
That is, for example, when vaporizing members made of different materials are divided into the rear and the work coils are plural, it is possible to vaporize at the same time, or to vaporize one first and vaporize the other later.

1 is a schematic configuration diagram of Example 1 of the present invention. FIG. 2 is an equivalent circuit diagram of noise radiation according to the first embodiment of the present invention. 1 is a conceptual diagram of a first embodiment of the present invention. 1 is an apparatus configuration diagram of Embodiment 1 of the present invention. Example 2 composition conceptual diagram of the present invention. FIG. 3 is a conceptual diagram of a configuration of Example 3 of the present invention. The schematic block diagram of a prior art, and the equivalent circuit schematic of noise radiation. The schematic block diagram of a prior art, and the equivalent circuit schematic of noise radiation. FIG. FIG.

  Examples of the present invention will be described below. However, the present invention is not limited to these examples. In the description of the embodiments to be described later, the same reference numerals are given to the same configurations as those of the embodiments described above, and the description thereof is omitted.

In Embodiment 1 of the present invention shown in FIGS. 1 to 4, reference numeral 1 denotes a plasma generator, and the plasma generator 1 has the following configuration.
A chamber 2 made of a conductive member grounded at a potential of 0, and a dipole electrode (a symmetric electrode) made up of an electrode A and an electrode B that are insulated from the chamber 2 in the chamber 2 and generate plasma. A plasma generating electrode 3, a self-excited high-frequency oscillating unit 6 (which may be separately excited) having an oscillator 4 and a transformer 5 for supplying DC power to high-frequency power and supplying the plasma generating electrode 3, and the chamber 2 The high-frequency oscillation part shield cover 7 made of a conductive member, which is integrated in a conductive form so as to cover the high-frequency oscillation part 6, and the middle point of the transformer 5 and the chamber 2 in a potential 0 state. The middle point connection portion 8 that is grounded, the high frequency oscillation portion 6 and the chamber 2 for preventing noise radiation due to high frequency generated in the chamber 2. A shield body 9 formed by the high-frequency oscillation unit shield cover 7, an oscillator power supply 10 that supplies power to the oscillator 4 in an insulated state from the shield body 9, and the chamber 2 is insulated from the chamber 2. The work electrode forming part 11 for bringing the work 14 into an electrode state provided in a state, and a negative DC power source 12 insulated from the shield body 9 for applying a negative voltage to the work electrode forming part 11 It is made up of.

The inner wall of the chamber 2 is a corrosion-resistant wall 13 such as a glass member or a ceramic member.
In FIG. 4, a decompression unit 18 connected to a vacuum pump (not shown) for decompressing or evacuating the inside of the chamber 2 is provided, and argon, nitrogen, oxygen gas, etc. are sent into the chamber 2. For this purpose, a gas injection part 19 is provided.

The high-frequency current starts from the electrode A and is fed through the electrode B, which is an electrode having the same shape as the plasma. Since the shield body 9 is not used as an electrode, no plasma self-bias voltage is generated. The plasma is at the same potential as the shield body 9 (conductor such as metal) in terms of DC potential. When a positive bias voltage of plasma is required, a bias potential may be applied from the middle point 15 of the transformer 5 to the work electrode forming unit 11. The high frequency power is balanced and fed, and no high frequency current flows through the shield body 9. Therefore, the potential fluctuation of the shield body 9 does not occur.
On the other hand, there is a problem of leakage radiation through AC power lines and control lines as energy supply, but these are not limited to devices that generate plasma, such as this device, but are common to all devices that use high frequencies. These leakage countermeasures and unnecessary radiation reduction techniques are currently at a level that is basically solved.
In addition, there are various bias methods such as a DC bias, an AC bias, and a pulse bias applied to the workpiece forming electrode.

Self-excited oscillation means that the plasma circuit is designed to include the electrical conditions in the resonance circuit (coil, capacitor, and resistor) necessary for oscillation, and without any external operation (automatic It means “oscillating” by itself in this resonant circuit (not manually).
On the other hand, self-excited oscillation is one type of frequency conversion method (self-excited / excited, inverter), and may be converted from alternating current to alternating current. Since it is easier to convert from direct current to alternating current, it is common to supply power to the oscillator with a direct current power source.
Electrons, + ions, and radicals exist in the ionized gas (plasma state), but when the radio frequency (RF) power is increased, the electrons and ions move faster between electrodes, the frequency of collisions and recombination increases, and the density increases. It becomes deeper (increased plasma density).

  The bias voltage is negative (the bias voltage may be positive) and + ions are attracted to this electrode. However, since electrons are negative, they are repelled and not sucked. When these + ions collide with the negative electrode, they are neutralized with the negative voltage of the electrode, but electrons are emitted from the electrode member by collision impact. These electrons once leave the electrode, but recombine with flying + ions to neutralize and emit light. When the negative voltage (bias voltage) of the electrode to be attracted is increased, + ions are accelerated, but collisions occur on the way, so they do not reach an infinite speed but settle down to an appropriate speed. In other words, in a low-density plasma, if the bias voltage is slightly increased, + ions are rapidly accelerated and reach a considerable speed, but in a dense plasma, a very high speed cannot be reached.

Advantages of the plasma generator 1 (1) A shield body is formed by a chamber and a shield cover which is integrated with the chamber in a conductive form. What is the shield body and energy supply source in terms of high frequency? Since there is no power supply line, the power supply line is completely eliminated. Since there is no power supply line, there is no radiation of interfering radio waves from the power supply line, and high frequency power to the plasma is balancedly supplied from the dipole electrode. That is, neither normal mode radio wave radiation nor common mode radio wave radiation occurs. Therefore, a plasma generating apparatus that does not cause radio wave interference without requiring a separate enclosure covering the entire apparatus is realized. That is, it is a plasma generation mechanism free from interference radio wave radiation (electromagnetic radiation).
A negative DC power source is prepared between the plasma generated by a pair of balanced electrodes (dipole electrodes) and the work electrode forming part so as to apply a bias voltage to the work electrode forming part. Thereby, since the same effect as the self-bias phenomenon conventionally used for film formation can be obtained, the shield function of the shield body has an effect of enabling film formation on the workpiece while alive.

(2) The above (1) realizes a plasma generation mechanism in which unnecessary radiation (radiation of disturbing radio waves) is not generated in principle. The electrical conditions of the plasma vary depending on the volume, distribution state, electron density, etc. generated by the plasma. However, in this embodiment, the frequency is not restricted by the ISM band or the like, not restricted by the fixed frequency, or by self-excited oscillation. A plasma generator capable of freely changing the frequency and injection power according to the application is realized.

  (3) According to the above (1), since the chamber is not configured as a one-sided electrode, when performing vapor deposition or etching, there is little influence of adhesion and dissociation of ions on the inner wall of the chamber, and the inner wall surface of the chamber is not easily contaminated. Realize an easy-to-use device. If the deposited material is expensive, the consumption amount can be reduced and the recovery from the chamber wall can be facilitated.

(4) According to the above (2), not only the frequency selection for the purpose of use but also the frequency selection for manufacturing the device can be freely performed. When manufacturing the device, it is possible to change the frequency depending on the size of the workpiece, the discharge power, etc., and also due to restrictions on procured parts and manufactured parts.

  (5) Since the self-excited oscillation is matched by moving the electrical frequency, it can be realized with a simple circuit configuration, and it is much faster and more precise than the conventional method of mechanically moving the capacitor and coil values. High-speed precision control and a low-cost apparatus can be realized because a high-precision matching operation is possible and an expensive matching BOX is unnecessary.

  (6) A dummy electrode can be separately provided based on the same idea as the work electrode forming portion according to (1). This is because when no voltage is applied to the work electrode forming portion and a negative voltage is applied to the dummy electrode, + ions are not attracted to the work electrode forming portion but are attracted to the dummy electrode. As a result, the remaining ions in the chamber can be attracted to the dummy electrode, so that the chamber can be cleaned. As a result, the gas in the chamber is replaced as in the prior art, and the transition time to the deposition film formation of other members can be performed in a short time without repeating the high vacuum operation, which is one form of a plasma generator. The plasma deposited film forming apparatus realizes a highly efficient film forming apparatus with excellent efficiency.

(7) Further, there is an effect that DC plasma can be generated by a bias forming power source in a state where high-frequency plasma is generated.
by this,
[A] Use only high-frequency plasma with the high-frequency oscillator turned on.
[B] Use after generating high-frequency plasma and turning on the bias forming power source to generate DC plasma to form a mixed plasma state of high-frequency plasma and DC plasma.
[C] After generating the high frequency plasma, the bias forming power source is turned on to generate DC plasma, and the high frequency oscillating unit is turned off to use only the DC plasma.
It is possible to generate and use three patterns of plasma.

  (8) Since the high frequency power (RF power) and the bias voltage to be accelerated can be adjusted separately, the plasma density can be increased by increasing the high frequency power (RF power), and positive ions (negative ions in the plasma) can be increased. In some cases, the speed of the work electrode forming portion toward the work can be adjusted to the optimum or preferred speed according to the voltage of the bias forming power source.

  Even if it is not self-excited oscillation, that is, separately-excited oscillation, if a plasma generator without the interference wave radiation described above is constructed, a method of matching by moving the frequency can be taken. However, reflected wave detection (for example, a directional coupler) for detecting changes in the plasma state is at a minimum, and can be put into practical use by taking measures against leakage of these devices.

  In the second embodiment of the present invention shown in FIG. 5, the main difference from the first embodiment is that a dummy electrode 21 insulated from the chamber 2 is provided in the chamber 2 and a bias voltage is applied to the dummy electrode 21. The plasma generating device 23 is formed by connecting the bias forming power source 12 and providing the changeover switch 22 for switching the voltage application of the bias forming power source 12 between the dummy electrode 21 and the work electrode forming unit 11.

The changeover switch 22 is set to the dummy electrode 21 side. As a result, the + ions in the plasma are not attracted to the grounded (potential 0) work electrode forming portion 11 side but are attracted to the dummy electrode 21 serving as a negative electrode. Next, when the changeover switch 22 is used to switch to the work electrode forming part 11 side, the work electrode forming part 11 is now sucked. These speeds and amounts can be controlled by the applied voltage and time. This is true for all + ions in the plasma.
When this operation is used, for example, a plurality of various metal ions mixed in the plasma in the chamber 2 can be all attached to the dummy at the initial stage of processing. That is, cleaning can be performed.
After being cleaned, a target metal element is generated in the chamber 2 and ionized by being injected into the plasma. By switching the changeover switch 22 to make the work electrode forming part 11 a negative electrode and the dummy electrode 21 to ground, only the target metal ions can be directed to the work electrode forming part 11 and attached to the work.

  This method not only prevents the mixing of unnecessary ions with respect to the metal ions attached to the workpiece, but also makes it easy to control the amount of attachment. In addition, the “evacuation work” for cleaning the inside of the chamber can be eliminated, and a highly efficient apparatus is realized.

  6 mainly differs from the second embodiment in that a bias forming power source 24 dedicated to the dummy electrode 21 is provided and a bias forming power source 25 dedicated to the work electrode forming portion 11 is provided. One or more work coils 27 in which a high-frequency current for heating and sublimating (vaporizing) a substance to be attached which is a part of the induction heating device 26 flows (for example, 2 MHz) are provided in the chamber 2 and heated by the work coils 27. The plasma generating device 30 is formed in which the raw material support portions 28 for supporting the sublimating raw materials A, B, C,... For sublimation are provided in the chamber 2.

The plasma generator 30 can generate a precisely controlled alloy film using the dummy electrode 21.
If metal ions such as A, B, and C are mixed in the plasma, when the work electrode forming portion 11 is made negative (cathode), the metal atoms adhering to the work electrode forming portion 11 have these ion concentrations. It does not necessarily adhere in proportion to It is difficult to control the ratio of adhering components and the penetration depth with the bias voltage and processing time. This is because the weight of metal atoms and the distance to the electrode are related. However, with a single metal ion, it is easy to control the amount and penetration depth of this single component with a bias voltage and time.
Therefore, it is desirable that only a single element ion always exist in the chamber 2 so that it adheres to the work table. The plasma generator 30 realizes this. Using the induction heating device 26, the raw material is heated and sublimated (vaporized) in the reduced pressure chamber 2 to diffuse into the plasma.
And it is good also as what has the raw material exchange mechanism function for the raw material support part 28 so that a several metal can be selectively heated sequentially.

First, the raw material A is heated and sublimated by induction heating, diffused in the plasma, and is attached to the workpiece 14 as + A ions. In order to stop the adhesion, the voltage application of the bias forming power supply 25 is stopped.
Next, + A ions (metal ions) remaining in the chamber 2 are attached and cleaned by applying a voltage from the bias forming power source 24 with the dummy electrode 21 serving as a cathode to float + A ions floating on the dummy electrode 21. The voltage application of the power supply 24 is stopped.
This time, the raw material support portion 28 is moved to heat and sublimate the raw material B, and the voltage of the bias forming power supply 25 is applied to adhere to the work 14.
Similarly, + B ions remaining in the chamber 2 are attached to the dummy electrode 21 to make it clean. Similarly, + C ions may be generated and deposited, or the layer can be made thicker or compounded by returning to + A ions. This may be repeated.
In this way, an alloy film can be formed on the surface of the workpiece with the amount and depth of each metal being accurately controlled.

{Appendix device}
The purpose of the additional apparatus is to provide a plasma generating apparatus that can clean the inside of the chamber without re-vacuum or replacement of gas and enable the next vapor deposition or etching as it is.
<Apparatus 1>
A chamber;
A plasma generating electrode provided in the chamber for generating plasma;
A high frequency oscillator for supplying a high frequency current to the plasma generating electrode;
A dummy electrode provided in the chamber in an insulated state; and
A plasma generator comprising: a bias power supply for supplying a bias current to the dummy electrode, the chamber being insulated from the chamber.
The invention is not limited to the self-excited high-frequency oscillator, and the plasma generator using the separately-excited high-frequency oscillator shown in FIGS.

<Effect of the apparatus of appendix 1>
By providing the dummy electrode, the dummy electrode and the work electrode forming portion are in one chamber. Since the floating ions are attracted to the applied voltage, for example, when the inside of the chamber is depressurized and the deposition of the substance A on the work is completed, the bias voltage is not applied to the work electrode forming portion, and the dummy electrode Residual A substance ions are attracted (deposited) to the dummy electrode to which the bias voltage is applied, and the inside of the chamber is cleaned quickly enough to be instantaneous, the application of the bias voltage to the dummy electrode is turned off, and the B substance is removed. It can be said that the substance B is vaporized and ionized by plasma, and the B substance is attracted (deposited) to the workpiece applied with a bias voltage to the workpiece electrode forming portion.

In this case, a B material film in which the A material is not mixed can be formed on the A material film. That is, a precise laminated film in which other substances are not mixed in each layer can be formed.
The bias forming power supply can be freely controlled by manual control or automatic control. Depending on the bias voltage strength, energization time, variable energization strength, energization and disconnection timing, etc. Since it can be controlled to be attracted intermittently or gradually in a moment, it is possible to finely control the formation of the deposited film.
In this regard, by providing a dummy electrode bias forming power source on the dummy electrode and providing a work electrode bias forming power source separately on the work electrode forming portion, by providing a separate bias forming power source, Bias voltage strength, energization time, variable energization strength, energization and disconnection timing, etc., for example, by finely controlling the amount of current while supplying current to both the dummy electrode and work electrode forming part, resulting in higher quality It is possible to form a simple vapor deposition film or a functional vapor deposition film.

When a non-target substance exists in the chamber, a bias voltage is applied to the dummy electrode so that the substance in the chamber adheres and forms a film. This processing time is adjusted by adjusting the dummy bias voltage. (At this time, since no bias is applied to the work electrode, adhesion and film formation are not performed.) In this way, cleaning at the time of film formation can be performed once without high vacuum or gas replacement.
Furthermore, when this operation is applied during alloy deposition,
For example, a process such as cleaning-A substance film formation-cleaning-B substance film formation-cleaning-can be performed, and high cleaning is performed in a short time before each process. Since the substance is controlled and deposited independently, not only the alloy composition becomes accurate, but also the thickness and depth of the film can be individually controlled accurately and with high quality.

<Apparatus 2>
A work coil in which a high-frequency current that forms a part of the induction heating device flows is provided in the chamber, and a vaporization member holding portion that holds a plurality of vaporization members that are vaporized by the induction heating by the work coil is provided to vaporize the gas. 2. The plasma generating apparatus according to claim 1, further comprising vaporizing member moving means for moving the member and setting the member at a heating position of the work coil.
<Effect of the apparatus of appendix 2>
The effect similar to the effect of the device described in the device of Appendix 1 is achieved, and for example, vaporizing members made of different materials are separated at the rear, and if there are a plurality of work coils, the other is vaporized at the same time, or one is vaporized first. There is an effect that can be vaporized later.

<Apparatus 3>
The chamber is grounded at zero potential,
A plasma generating electrode is provided in the chamber in an insulated state from the chamber, and generates a plasma between the electrodes.
An oscillator power supply for supplying power to the oscillator in an insulated state from the shield body is provided,
A high-frequency oscillator converts power from the oscillator power supply into high-frequency power and supplies it to the plasma generating electrode, and a self-excited high-frequency oscillation unit having an oscillator and a transformer,
A high frequency oscillation part shield cover made of a conductive member is provided so as to be integrated with the chamber in a conductive form and cover the high frequency oscillation part,
The middle point of the transformer and the chamber are grounded at a potential zero state at the middle point connection portion,
A shield body is formed by the chamber and the high-frequency oscillation unit shield cover in order to prevent generation of noise radiation due to high-frequency generated in the chamber and the high-frequency oscillation unit,
In the chamber, provided with a work electrode forming portion for making the work in an electrode state in an insulated state from the chamber,
A bias voltage is applied to the work electrode forming portion, and a bias forming power source that is insulated from the shield body is provided.
The plasma generator according to any one of appendices 1 and 2, wherein the power source for supplying power to the dummy electrode is a bias forming power source that is connected to the shield body in an insulated state and applies a bias voltage .

<Effect of the apparatus of appendix 3>
In addition to the same effects as the apparatus described in any one of Appendices 1 and 2, the following effects can be achieved.
(1) This device has a configuration in which a shield body is formed by a chamber and a high frequency oscillation part shield cover integrated with the chamber in a conductive form. There is no power supply line at all, and since there is no power supply line, there is no radiation of the interference wave (normal mode) from the power supply line, and the shield body itself, which is a conductor such as metal, has no electric potential (the electrode and As the power supply to the plasma (energy injection) is from the balanced electrode, the shield body wall is not a current path through which high-frequency current does not flow (potential bias does not occur). There is an effect that does not happen. That is, a normal mode radio interference and a common mode radio interference do not occur. Therefore, a plasma generating apparatus that does not cause radio interference without requiring a cost and a separate enclosure that requires a ground volume is required. .

  At the same time, a power source for forming a bias is prepared between the plasma and the work electrode forming part so that a bias voltage is applied to the work electrode forming part, and the chamber is grounded at a potential of 0 (potential zero). Therefore, the shield function of the shield body has the effect of allowing film formation on the workpiece while alive.

(2) The above (1) realizes a plasma generator that is free of unnecessary radiation (radiation of disturbing radio waves) in principle. Therefore, a plasma generator with a suitable and optimum high frequency can be obtained without being restricted by the ISM band. Realize.
The electrical conditions of the plasma vary depending on the volume, distribution state, electron density, etc. generated by the plasma. In this device, the frequency and injection power can be freely selected according to the intended use. It is possible to realize a plasma generator capable of freely selecting a frequency suitable for generating plasma without considering the above.

  (3) According to the above (2), the frequency can be selected from discharge power, ease of control, procurement of parts, etc., in addition to the required frequency from the application, There is an effect of realizing frequency selection suitable for a device to be manufactured such as cost and system construction.

  (4) Since self-excited oscillation allows automatic frequency adjustment techniques, high-speed and precise control using electrical frequency (variable) matching can be realized with a simple control configuration, and the values of capacitors and coils can be mechanically adjusted. Compared to the conventional method of moving, the matching can be performed at a much higher speed and an expensive matching BOX is not required, so that the cost is low.

(5) According to the above (1), since the shield and the shield body are set to the same potential so that the shield body is not used as an electrode, there is no phenomenon that ions are violently collided with the inner wall of the chamber during deposition. because of the order of deposition in a state resting on the inner wall surface, hard dirt chamber walls, thereby realizing a washing removed is easily performed apparatus, the configuration of the plasma and the shield body is not the electrode shield body at the same potential Therefore, since the work electrode forming portion insulated from the chamber is connected to the bias forming power source insulated from the shield body , the work is used as an electrode in the state of (4). There is an effect that ions can be attracted by attractive collision deposition.
Further, if the deposited material is expensive, the consumption amount can be reduced and the recovery from the wall can be facilitated.

(6) According to the above (5), it is possible to provide a dummy electrode connected to the bias forming power source in the same way as the work electrode forming portion.
As a result, when no current is supplied to the work electrode forming portion and current is supplied to the dummy electrode, the residual ions in the chamber are attracted to the dummy electrode to which voltage is applied intermittently or gradually. As a result, the chamber can be cleaned. As a result, the gas in the chamber is replaced as in the prior art, and the transition time to the deposition film formation of other members can be performed in a short time without repeating the vacuum operation. Realize a plasma generator with high productivity and high production capacity.
“Power” of “change power to high frequency power” has various power forms such as DC power, AC power, and pulse power.

  The present invention is used in the industry for manufacturing plasma generators.

1: Plasma generator,
2: chamber,
3: Plasma generating electrode,
4: Oscillator,
5: Transformer
6: High-frequency oscillation unit,
7: High frequency oscillator shield cover,
8: Middle point connection,
9: Shield body,
10: Power supply for oscillator
11: Work electrode forming part,
12: Power supply for bias formation,
13: Corrosion resistant wall,
14: Work,
15: Middle point,
18: decompression part,
19: Gas injection part,
21: Dummy electrode
22: changeover switch,
23: Plasma generator,
24: Power supply for bias formation,
25: Bias forming power supply,
26: induction heating device,
27: Work coil,
28: Raw material support,
30: Plasma generator.

Claims (5)

A chamber made of a conductive member grounded in a zero potential state, in which high-frequency current does not flow;
A first plasma generating electrode, a second plasma generating electrode, which are provided in an insulating state in the chamber and generate plasma between the electrodes;
A high frequency oscillating unit having an oscillator and a transformer for supplying electric power to high frequency power and supplying the first plasma generating electrode and the second plasma generating electrode;
A high frequency oscillation part shield cover made of a conductive member, which is integrated in the chamber in a conductive form and is provided so as to cover the high frequency oscillation part;
A middle point connection formed by grounding the middle point of the transformer and the chamber at a potential of 0;
A shield body that is formed by the chamber and the high-frequency oscillation unit shield cover for preventing generation of noise radiation due to high-frequency generated in the chamber and the high-frequency oscillation unit, and in which the high-frequency current does not flow,
An oscillator power supply for supplying power to the oscillator in an insulated state from the shield body;
A workpiece electrode forming portion for providing a workpiece in an electrode state provided in the chamber in an insulating state with the chamber;
A plasma generator comprising: the shield body that applies a bias voltage to the work electrode forming portion; and a bias forming DC power source that is insulated.   2. The plasma according to claim 1, wherein the first plasma generating electrode and the second plasma generating electrode are symmetrical electrodes that are balanced power supply, and a middle point of the symmetrical electrodes is grounded. 3. Generator. The plasma generator according to claim 1, wherein the high-frequency oscillation unit is a self-excited high-frequency oscillator.   A dummy electrode for attracting positive ions in an insulated state from the chamber is provided in the chamber, and a bias forming DC power source that is insulated from the shield body and applies a bias voltage to the dummy electrode is provided. The plasma generator according to any one of claims 1 to 3.   A work coil in which a high-frequency current that forms a part of the induction heating device flows is provided in the chamber, and a vaporization member holding portion that holds a plurality of vaporization members that are vaporized by the induction heating by the work coil is provided to vaporize the gas. 5. The plasma generating apparatus according to claim 1, further comprising a vaporizing member moving unit configured to move the member and set the heating position of the work coil.

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