KR20110090877A - Plasma processing apparatus - Google Patents

Abstract

PURPOSE: An apparatus for processing plasma is provided to improve the ignitability of plasma by using an ECR(Electron Cyclotron Resonance) breakdown. CONSTITUTION: A vacuum process room(1) comprises a cover for a vacuum process room, a high frequency induction antenna, and a faraday shield(9). The high frequency induction antenna forms the electrical field of rotation inducement through a high frequency current. The electrical field of rotation inducement rotates right to the induction line of a magnetic field. The high frequency induction antenna is composed to accord the rotation frequency of the electrical field of rotation inducement with an electron cyclotron frequency by the magnetic field.

Description

Plasma Processing Equipment {PLASMA PROCESSING APPARATUS}

The present invention relates to a plasma processing apparatus using an inductively coupled electron cyclotron resonance plasma.

In response to the miniaturization of semiconductor devices, in the plasma process, process conditions (process windows) for realizing uniform processing results in the wafer surface are narrowed year by year, and in the future plasma processing apparatus, more complete process state control is provided. It is required. In order to realize this, an apparatus capable of controlling the distribution of plasma, the dissociation of process gas, and the surface reaction in the reactor with high accuracy is required.

At present, a typical plasma source used in these plasma processing apparatuses is a high frequency inductively coupled plasma (ICP: Inductively Coupled Plasma: hereinafter abbreviated as ICP) source. In the ICP source, first, the high frequency current I flowing through the high frequency induction antenna generates an induction magnetic field H around the antenna, and the induction magnetic field H forms the induction electric field E. At this time, if electrons exist in the space where plasma is to be generated, the electrons are driven by the induction electric field E, and ionize a gas atom (molecule) to generate a pair of ions and electrons. The electrons generated in this manner are driven by the induction electric field E together with the original electrons, and ionization occurs. Finally, this ionization occurs in the form of sulphate, and plasma is generated. The region where the density of the plasma is highest is the space where the induction magnetic field H or the induced electric field E is strongest, i.e., the space closest to the antenna, among the spaces for generating the plasma. In addition, the intensities of the induction magnetic field H and the induction electric field E have the characteristic of attenuating by the power of the distance centering on the line of the current I flowing through the high frequency induction antenna. Therefore, the intensity distribution of these induction magnetic fields H and the induction electric field E, and also the distribution of plasma can be controlled by the shape of the antenna.

As described above, the ICP source generates plasma by the high frequency current I flowing through the high frequency induction antenna. In general, when the number of turns (winding number) of the high frequency induction antenna is increased, the inductance increases and the current decreases, but the voltage increases. When the turn is lowered, the voltage is lowered but the current is increased. In the design of the ICP source, how much current and voltage is preferable is determined not only from the viewpoint of the uniformity, stability and generation efficiency of the plasma, but also from various reasons in terms of mechanical and electrical engineering. For example, an increase in current has a problem of heat generation, a problem of power loss due to this, and a problem of the withstand current characteristics of the variable capacitor used in the matching circuit. On the other hand, the increase in voltage includes abnormal discharge, influence of capacitive coupling between the high frequency induction antenna and the plasma, and problems with the withstand voltage characteristics of the variable capacitor. Therefore, the designer of the ICP source has the shape and the number of turns of the high frequency induction antenna while taking into account the current resistance and withstand voltage characteristics of the electric element such as the variable capacitor used in the matching circuit, cooling of the high frequency induction antenna or problems of abnormal discharge. Determine.

Such an ICP source has the advantage of controlling the intensity distribution of the induction magnetic field H or the induction electric field E generated by the antenna, that is, the distribution of plasma, by the winding method or the shape of the high frequency induction antenna. Based on this, various studies have been conducted in ICP.

As a practical example, there is a plasma processing apparatus which processes a substrate on a substrate electrode using an ICP source. In this plasma processing apparatus, a high frequency induction antenna is constituted by a part or all of a multi-vortex antenna to obtain a more uniform plasma and power efficiency by matching parallel coils of a matching circuit for a high frequency induction antenna. It is proposed to reduce the decrease and to decrease the temperature rise (for example, refer to Patent Document 1).

In addition, a structure in which a plurality of completely identical high frequency induction antennas are provided in parallel at predetermined angles has been proposed. For example, it is proposed to improve the uniformity in the circumferential direction by providing three systems of high frequency induction antennas at 120 ° pitch (see Patent Document 2, for example). The high frequency induction antenna is wound vertically, wound in a plane, or wound along a dome. As in Patent Literature 2, there is an advantage that the total inductance of the high frequency induction antenna composed of the plurality of antenna elements is reduced by connecting a plurality of antenna elements that are exactly the same in parallel.

In addition, the high frequency induction antenna is constituted by connecting two or more identical antenna elements in parallel in a circuit, and is arranged concentrically or radially so that the center of the antenna element coincides with the center of the workpiece. It is proposed to arrange the input end of the antenna element at an angle pitch obtained by dividing 360 ° by the number of antenna elements, and to configure the antenna element to have a three-dimensional structure in the radial direction and the height direction (for example, Patent Document 3). Reference).

Regarding an ICP source, an electron cyclotron resonance (ECR) is referred to as an ECR. A plasma source is a plasma generator using resonance absorption of electromagnetic waves by electrons. It is excellent and has the characteristics that a high density plasma is obtained. At present, the use of microwaves (hereinafter referred to as μ waves) (2.45 GHz) and electromagnetic waves in the UHF and VHF bands has been devised. Electromagnetic radiation into the discharge space is electrodeless discharge using a waveguide or the like in μ waves (2.45 GHz), and parallel plate type capacitive coupling discharge using a capacitive coupling between an electrode and a plasma that emits electromagnetic waves in UHF and VHF. There are many cases.

There is also a plasma source using an ECR phenomenon using a high frequency induction antenna. This is to generate a plasma by waves accompanying a kind of ECR phenomenon, also called Whistler wave. Whistler wave is called a helicon paradox, and the plasma source using this is also called a helicon plasma source. In the configuration of the helicon plasma source, for example, a high frequency induction antenna is wound on the side of a cylindrical vacuum vessel, and a high frequency power of a relatively low frequency, for example, 13.56 MHz is applied thereto and a magnetic field is applied thereto. At this time, the high frequency induction antenna generates electrons rotating in the right direction in one half cycle of 13.56 MHz, and electrons rotating in the left direction in the other half cycle. Among these two kinds of electrons, the ECR phenomenon occurs due to the interaction between the electrons in the right direction and the magnetic field. However, in this helicon plasma source, the time at which the ECR phenomenon occurs is limited to half a period of high frequency, and since the place where the ECR is generated is dispersed and the absorption field of the electromagnetic wave is long, a long cylindrical vacuum vessel is required. There are some problems such as difficulty in obtaining uniformity of the particles, difficult to control by proper plasma characteristics (electron temperature, gas dissociation, etc.) because of the change in plasma characteristics in addition to the long vacuum vessel. Not very suitable

Already, the vertically long vacuum vessel peculiar to a helicon plasma source is proposed (for example, refer patent document 5). However, in the technique described in this document, a high frequency induction antenna is not used, and studies have been made to generate a helicon wave by a method of controlling a phase of a voltage applied to a patch electrode capacitively coupled with plasma. Further, in order to compensate for the disadvantages of the controllability of the plasma distribution as described above, two or more sets of electrode groups have been studied at intervals that are a function of the wavelength of the helicon wave in accordance with the vertically long vacuum vessel. However, whether to use an inductively coupled antenna or a capacitively coupled patch electrode, when using a helicon wave, it cannot be avoided from a vertically long vacuum vessel having poor plasma controllability. This is well reflected by patent document 5. Moreover, when it is going to improve plasma controllability using this vertically long vacuum container, there also exists a problem that it is necessary to have the structure of a very complicated electrode and a magnetic field, and this is also reflected by patent document 5 well.

In order to generate the electrons in the right direction, there are a plurality of methods for generating a rotating electric field. As a simple method, the patch antenna method as described in Patent Document 5 has been known since ancient times, and n (for example, four) antennas of a patch shape (circular or rectangular small surface shape) are arranged on the circumference. When the phase of the voltage having the frequency of the electromagnetic wave to be radiated is shifted by π / n (for example, π / 4), the right-side polarized electromagnetic wave can be emitted.

First, the method of actively generating the electric field of the right turn will be described. In the case of an active antenna, near fields (both electric and magnetic fields) and far fields (electromagnetic fields) are formed around the antenna. Which field is generated strongly or weakly depends on the design and usage of the antenna. At this time, when the plasma and the antenna are capacitively coupled, the main process of power transport for the plasma becomes the electric field (near field). In addition, when the plasma and the antenna are inductively coupled, the main process of power transmission to the plasma becomes a magnetic field (near field). If neither capacitive coupling nor inductive coupling is active, the main process of power transport to the plasma is far-field use. Hereinafter, a method for generating a right turn electric field by electromagnetic radiation, an electric field, and a magnetic field will be described.

(1) Electromagnetic radiation (far field)

The far-field leader is the electromagnetic wave propagating to the far side. This method is divided into a case in which the positively polarized electromagnetic field is emitted into a plasma generating space and a case in which a right polarization component included in the electromagnetic wave is used without being actively polarized. The method of arranging n patch antennas described above is the former, and the conventional electrodeless ECR discharge using a μ wave is the latter example. The plasma and antenna are not actively coupled so that the near field does not interfere. Only the radiated electromagnetic waves are incident on the plasma. It is known that the whole antenna, such as a patch antenna or a dipole antenna (refer patent document 4, but this technique does not actively rotate the electromagnetic field right) can be used. That is, in this method, the following (A), (B) and (C) can be said.

(A) Apply power to the antenna (electrode). In order to raise the radiation efficiency of an electromagnetic field, resonance of an antenna is actively used in many cases. If resonance is not used, the radiation efficiency of electromagnetic waves is poor, and thus it is difficult to do practically. Since the radiated electromagnetic waves are not actively directed to the plasma (they propagate far away, they fly to various places), they are not absorbed well by the plasma and are difficult to use for high power transportation. In large power transportation, a waveguide in which the propagation direction of electromagnetic waves is limited is often used. However, since the size of the waveguide is determined by the wavelength of the electromagnetic wave, the waveguide size becomes too large at a frequency of μ wave or less, so that a waveguide is rarely used.

(B) When an electrode (antenna) is used instead of the waveguide, there is a terminal for applying electric power to the electrode. The terminal for grounding the electrode is divided into a case where it does not exist and a case where it exists. This is determined by how to generate resonance of the antenna.

(C) With or without an antenna, the penetration limit of the electromagnetic field radiated to the plasma is determined by the cutoff density (nc) (m ^-3 ), in which case the electromagnetic waves penetrate the plasma to the skin depth. The skin depth is 138 mm when the resistivity of the plasma is 15? M at 200 MHz, and is longer than the sheath (several mm or less). That is, it penetrates deeper into the plasma than in the case of the capacitive coupling described below.

30 shows the relationship between the frequency f of the electromagnetic wave and the cutoff density nc. In the region below the µ wave, the cutoff density nc is generally lower than the plasma density (10 ^15-17 m ⁻³ ) used in industry. That is, the electromagnetic waves of μ wave or less cannot propagate freely in the ordinary plasma, and penetrate to the skin depth.

(2) near field (near field)

In order to generate an electric field, an active electrode which generates a near field (electric field) is required, and a patch electrode (for example, refer patent document 5), a parallel plate type electrode, etc. can be used. In this case, since the electric field (voltage generated in the electrode) must be strong (high), the load of the electrode needs to be high impedance. In other words, the electrode used here is designed to be capacitively coupled to the plasma, but not to be extremely coupled to the grounded component. In other words, it is not possible to ground a part of this electrode or to ground by connecting a capacitor or a coil. Since the electric field is a near field, by studying the positional relationship between the electrode and the plasma, large power can be efficiently transported to the plasma, but in order to strengthen the capacitive coupling, a sufficient area (large capacitance) is required for the plasma. . Because of the capacitive coupling of the electrode and the plasma, not only an antenna (electrode for emitting electromagnetic waves) but also an electrode for generating a simple electric field (near field) even though its ability to radiate electromagnetic waves is the same (the electrode of a capacitively coupled parallel flat plasma source) Can also be used.

In this method, the following can be said.

(A) A voltage is applied to the electrode. In particular, when positively polarized waves are actively generated, a voltage subjected to phase control is applied to the electrode.

(B) The electrode has only a terminal for applying a voltage, and no other terminal, for example, a terminal for grounding the electrode, does not exist.

(C) The capacitively coupled electric field is shielded by the former mass motion (sheath). In order to prevent this shielding, the magnetic field perpendicular to the electric field of the sheath is applied to limit the movement of the electrons. In other words, limiting the movement of the electrons can be said to extend the wavelength of the electric field in the plasma.

(D) In the technique of patent document 5, it can be concluded that the electrode which capacitively couples with a plasma is used by the following arguments.

(D-1) A voltage is used as a high frequency signal. This means that high frequency energy is directly converted into a voltage, that is, an electric field, and transmitted to the plasma. This indicates that the electrode is capacitively coupled with the plasma. In this regard, when inductive coupling is used, a current must be used as a high frequency. The inductive coupling is performed by the induction magnetic field, but the induction magnetic field is generated by the high frequency current, not the voltage.

(D-2) Describes shielding by electron motion, but this means that the electrode is capacitively coupled to the plasma. Although the technique can eliminate this shielding with a static magnetic field, it is an effective means only if the electrodes are capacitively coupled to the plasma. Because it is impossible to change the depth of the epidermis with a static field. The high frequency induction field can only be canceled by the high frequency induction field, and cannot be eliminated by the static field. Because of the magnetic field, it is impossible to offset the high frequency induction magnetic field (ie, fluctuation value) by the physical quantity that can be added and subtracted or by the static magnetic field (that is, the constant value). The skin effect of plasma is shielding effect by the high frequency magnetic field component of the electromagnetic field, and the effect of the skin effect itself is the high frequency induction magnetic field generated in the plasma (because it has the opposite polarity to the induction field applied by current, Acts in a direction to cancel the induced magnetic field generated by

(D-3) The electrode used for the reference document 5 states that it is not an antenna. This is only the electrode used mainly uses the near field. That is, it is either an induced electric field or one of the induction magnetic fields described below.

(D-3-1) In Reference Document 5, it is shown in the drawings that a patch-shaped electrode having a small area having low efficiency of emitting electromagnetic waves is used. This is only an electrode used mainly using a near field and is either an induction field or one of the induction fields described below. However, in the case of the electric field, a large area (large capacitance) is required in order to strengthen the coupling with the plasma, whereas in the case of the magnetic field, a line through which a current flows in order to realize a transformer (inductive coupling) is thin and parallel to the plasma. You need to pull it long. In patent document 5, only the capacitive coupling is carried out rather than the type of an electrode. There is neither a technique nor a drawing for grounding a patch-shaped electrode. As described in (D-3-2), the size of the patch-shaped electrode is shorter than the wavelength of the high frequency wave, and the voltage and current generated in the patch-shaped electrode also change depending on the frequency of the applied high frequency, The same voltage is generated without the influence of the wavelength, and the same current flows in. Although the patch electrode is a near field, it has a strong induction field and a weak induction field, but in this case, the induction field has an area capacitively coupled with the plasma. However, the length of the line is long enough for the patch electrode to be strongly trans-coupled with the plasma. Don't have

(D-3-2) An example of using 13.56 MHz is cited, but the wavelength of 13.56 MHz is about 22 m, and it is not considered that the patch-shaped electrode in the figure is resonating with this wavelength (if it resonates, If necessary, the size of the electrode needs to be 1/2 or 1/4 of the wavelength, and for example, resonance does not occur without using a method of actively resonating as in Patent Document 4. This patch-shaped electrode does not necessarily resonate even if it is not described. In addition, there is no plasma processing apparatus that performs a predetermined process for forming a semiconductor device that requires such a large electrode. This is only that the electrode used mainly uses the near field. Induction field or any of the following induction fields. However, in the case of the electric field, a large area (large capacitance) is required in order to strengthen the coupling with the plasma, whereas in the case of the magnetic field, a line through which current flows in order to realize a transformer (inductive coupling) is thin and parallel to the plasma. You need to pull it long. The electrode is patch-shaped and there are few current lines for transcoupling with the plasma. In other words, the patch-shaped electrodes are only capacitively coupled.

(D-3-3) There is neither a technique nor a drawing for grounding a patch-shaped electrode. Therefore, the current flowing through the patch-shaped electrode is introduced into the earth through the plasma. That is, the plasma is the load of this patch-shaped electrode, and the current value greatly changes according to the impedance of the plasma to be generated. As is well known, in inductively coupled plasma, basically, current is supplied to one end of the line inductively coupled with the plasma, and the other end is grounded. This causes the current flowing in the line mainly to flow directly into the ground (earth), thereby generating a large current due to ground (low impedance of the load). This high current generates an induction magnetic field so that power can be efficiently transported to the plasma. Of course, the grounding terminal is separated from the earth and a capacitor is inserted therein, but a large current is generated by electrical circuit studies, and a strong induction magnetic field is generated by the large current to efficiently transport power to the plasma. There is no change in what is done. In other words, neither the technique nor the drawing of grounding the patch-shaped electrodes is nothing but the capacitive coupling of the patch-shaped electrodes with the plasma.

A semiconductor plasma processing apparatus for processing a target object by plasma includes an exhaust chamber for processing the target object inside, an antenna including a plurality of linear conductors inside the reaction chamber, and one end of the plurality of linear conductors. The RF antenna is connected to each other. The antenna includes at least three linear conductors disposed radially from the center of the antenna at equal intervals from each other, and each of the linear conductors has one end grounded and the other end. It is connected to this RF high frequency power supply. The surface of the linear conductor of the antenna is insulated. As a result, an inductively coupled plasma processing apparatus that generates a plasma that is equally stable and has a high density. In addition, the plasma processing apparatus includes an electromagnet for generating a magnetic field in a direction orthogonal to the induction electric field, and by applying an external magnetic field, the plasma density can be further improved without changing the applied RF power.

[Patent Document 1]

Japanese Patent Application Laid-Open No. 8-83696

[Patent Document 2]

Japanese Patent Application Laid-Open No. 8-321490

[Patent Document 3]

Japanese Patent Application Laid-Open No. 2005-303053

[Patent Document 4]

Japanese Patent Application Laid-Open No. 2000-235900

[Patent Document 5]

Japanese Patent No. 3269853

[Patent Document 6]

Japanese Patent Application Laid-Open No. 11-135438

[Patent Document 7]

Japanese Patent Laid-Open No. 11-74098 (U.S. Patent No. 6388382)

[Patent Document 8]

U.S. Patent No. 5811022

[Patent Document 9]

Japanese Patent Laid-Open No. 2006-156530

[Non-Patent Documents]

L. Sansonnens et al., Plasma Sources Sci. Technol. 15, 2006, pp 302

[Non-Patent Document 2]

J. Hoopwood et al., J. Vac. Sci. Technol., All, 1993, pp 147

[Non-Patent Document 3]

M. Yamashita et al., Jpn. J. APP 1. Phys., 38, 1999, pp 4291

[Non-Patent Document 4]

K. Suzuki et al., Plasma Source Sci. Technol., 9, 2000, pp 199

With respect to the conventional technique for generating the right turn electric field, it is not conventional to produce an electric field that is actively turned right using a near field (near field). Moreover, no technology has been developed to cause ECR using the positively turning induction field generated by induction. Since the induction magnetic field is generated by the electric current, a design opposite to the use of the electric field is required. That is, in the use of an induction magnetic field, an active electrode which generates a strong near field (magnetic field) is required, and since the current must be strong, the load of the electrode needs to be made low impedance. In other words, the electrode used here is inductively coupled to the plasma (trans coupling), but it is necessary to actively ground it or to ground by connecting a capacitor or a coil. Since the use of the induction field is a near field, by studying the positional relationship with the plasma, large power can be efficiently transported to the plasma. In this method, in order to strengthen the inductive coupling, a sufficient line length (coil length) to be combined with the plasma is required. This method uses an inductive coupling (trans coupling) of an electrode and a plasma, and therefore not only an antenna (electrode radiating electromagnetic waves) but also an electrode (coil) that generates a simple magnetic field (near field) even though its ability to radiate electromagnetic waves is weak. Can be used. According to this method, the following can be said.

(A) A phase controlled current is applied to the electrode.

(B) An electrode has a terminal for applying a current, and another terminal for actively flowing a large current from the electrode to the ground portion exists. This terminal is grounded or grounded through a capacitor or coil.

(C) The inductively coupled electric field is shielded by the epidermal effect as in the far field. It is impossible to prevent this shielding with a static field.

In the ICP source, the high frequency current I flows into the plasma or earth through the stray capacitance while causing the high frequency induction antenna to circulate, causing loss. This causes the phenomenon that the induced magnetic field H has a distribution of strength and weakness in the circumferential direction, and as a result, the phenomenon that the uniformity of the plasma in the circumferential direction is impaired may be remarkable. This phenomenon is influenced by not only the permittivity but also the permeability of the space around the high frequency induction antenna, and is a wavelength shortening phenomenon which appears as a reflection wave effect or a skin depth effect. This phenomenon is a general phenomenon that occurs even in a general high frequency transmission cable such as a coaxial cable, but the wavelength shortening effect is more remarkable when the high frequency induction antenna is inductively coupled or capacitively coupled to the plasma. In addition to the ICP source, in general plasma sources such as an ECR plasma source or a parallel plate capacitively coupled plasma source, traveling waves toward the inside of the antenna or vacuum chamber and returning reflected waves are generated in the antenna or the space surrounding the high frequency radiation. A standing wave is generated by overlapping. This is because the reflected wave is returned from the antenna end, the plasma, and a large portion of the vacuum vessel in which high frequency radiation is emitted. This standing wave is also largely involved in the wavelength shortening effect. Under these circumstances, even in the case of an ICP source, even if the frequency of the RF power source is 13.56 MHz with a long wavelength of about 22 m, when the high frequency induction antenna length exceeds about 2.5 m, standing waves having a wavelength shortening effect in the antenna loop are generated. Occurs. Thus, a problem arises in that the current distribution in the antenna loop becomes nonuniform and the plasma density distribution becomes nonuniform.

In the ICP source, the high frequency current I flowing through the antenna periodically reverses the phase, i.e., the direction in which it flows, and accordingly, the direction of the induced magnetic field H (the inductive field E), i.e., the driving direction of the electrons, There is a problem of reversal. That is, for every half period of the high frequency to be applied, the electron stops once and then accelerates in the reverse direction. In such a state, when the sulfonate ionization by electrons is insufficient at any half period of the high frequency, a problem arises that a plasma having a sufficiently high density is difficult to be obtained when the electrons once stopped. This is because the generation efficiency of the plasma decreases while the electrons are decelerated and stopped once. In general, the ICP source has a lower ignition of plasma than an ECR plasma source or a capacitively coupled parallel plate type plasma source, but this is caused by the above causes. In addition, the plasma generation efficiency is deteriorated every half period of the high frequency, as is the case with the helicon plasma source using inductive coupling without phase control.

As described above, in the ICP source, various studies have been made to improve the uniformity of the plasma, but the more complicated the structure of the high frequency induction antenna becomes, the more difficult it is to be established as an industrial device. Moreover, in the prior art, it is not intended to dramatically improve the flammability of the plasma while maintaining good plasma uniformity, and the poor flammability is not solved.

On the other hand, since the ECR plasma source has a short wavelength, it is easy to cause complex electric field distribution in the apparatus, and there is a problem that it is difficult to obtain a uniform plasma.

That is, because the wavelength of the µ wave (2.45 GHz) is short, the µ wave propagates in various high-order propagation modes in the discharge space in the large-diameter ECR plasma source. As a result, the electric field is concentrated locally in every corner of the plasma discharge space, and a high-density plasma is generated in that portion. In addition, since the standing wave is generated by overlapping the electric field distribution by the high-order propagation mode of the incident mu wave, the reflected wave returned from inside the plasma apparatus, the electric field distribution in the apparatus tends to be more complicated. For the above two reasons, it is generally difficult to obtain uniform plasma characteristics over a large diameter. In addition, once such a complex full length distribution occurs, it is practically difficult to control the full length distribution and change it into a good full length distribution for the process. This is because it is necessary to change the structure of the device so that a higher order propagation mode does not occur or the reflected wave reflected from the device and returned does not form a complex electric field distribution. There is almost no single device structure that is optimal for various discharge conditions. In addition, in order to generate an ECR discharge at μ waves (2.45 GHz), a strong magnetic field of 875 gauss is required, and there is a disadvantage in that the structure including the power and yoke consumed by the coil generating this is very large.

In terms of the magnetic field strength among these problems, the magnitude of the problem is alleviated because UHF and VHF become relatively weak magnetic fields. However, even in UHF and VHF with relatively long wavelengths, the standing wave problem is serious, the electric field distribution in the discharge space becomes uneven, the plasma density distribution generated is not flat, and there is a problem in the process uniformity. About this, theoretical experimental research is continued still now (for example, refer nonpatent literature 1).

As described above, in the conventional ICP source, generation of plasma having good uniformity has been examined, but there is a problem that the structure of the antenna must be complicated and the ignition of the plasma is poor. On the other hand, although the ECR plasma source has good ignition property, there is a problem that the plasma uniformity due to the higher-order propagation mode of electromagnetic waves and the standing wave is poor.

The present invention has been made in view of the above problems, and makes it possible to use the ECR discharge phenomenon in a plasma processing apparatus using an ICP source. As a result, the antenna structure can be optimized with a minimum of research to improve the uniformity of the plasma and to significantly improve the ignition of the plasma.

That is, an object of the present invention is to provide a uniform plasma source having good ignition even in a large diameter plasma processing apparatus.

The plasma processing apparatus according to the present invention for solving the above problems includes a vacuum vessel constituting a vacuum processing chamber capable of accommodating a sample, a gas inlet for introducing a processing gas into the vacuum processing chamber, and an induction electric field in the vacuum processing chamber. A high frequency induction antenna to be formed, a magnetic field coil for forming a magnetic field in the vacuum processing chamber, a high frequency power supply for plasma generation for supplying a high frequency current to the high frequency induction antenna, and a power supply for supplying power to the magnetic field coil, A plasma processing apparatus for supplying a high frequency current from a high frequency power source to a high frequency induction antenna, and plasma treating gas supplied into a vacuum processing chamber to plasma-process a sample, wherein the vacuum processing chamber is hermetically fixed to an upper portion of the vacuum container. A vacuum chamber cover made of a dielectric and the high frequency fluid And a Faraday shield disposed between the antenna and the vacuum chamber cover, wherein the high frequency induction antenna is divided into n high frequency induction antenna elements, each of the divided high frequency induction antenna elements Are arranged in series, and a plurality of sets of each of the high frequency induction antenna elements arranged in a row are provided, and the high frequency induction antenna elements of each high frequency induction antenna of each set are sequentially delayed by λ (wavelength of a high frequency power supply) / n. The high frequency current is formed by delaying the high frequency current in order in a predetermined direction, and rotating the electric field E which rotates in the right direction with respect to the magnetic line direction of the magnetic field B formed by supplying electric power to the magnetic field coil. And configured to match the rotation frequency of the rotation induction field E with the electron cyclotron frequency caused by the magnetic field B. The.

Preferably, an electrode on which the sample is mounted, a high frequency power supply for bias applying high frequency power to the electrode, a high frequency power supply for faraday shield applying high frequency power to the faraday shield, the high frequency power supply for bias and the bias And a phase controller for controlling a phase difference between the bias high frequency power supply and the faraday shielded high frequency power supply.

In order to solve the above problems, another aspect of the plasma processing apparatus according to the present invention includes a vacuum container constituting a vacuum processing chamber capable of accommodating a sample, a gas inlet for introducing a processing gas into the vacuum processing chamber, and the vacuum. A high frequency induction antenna for forming an induction electric field in the processing chamber, a magnetic field coil for forming a magnetic field in the vacuum processing chamber, a high frequency power supply for plasma generation for supplying a high frequency current to the high frequency induction antenna, and a power supply for supplying power to the magnetic field coil And a plasma processing apparatus for supplying a high frequency current to the high frequency induction antenna from the high frequency power source, and plasma treating the gas supplied into the vacuum processing chamber to plasma-process the sample. Vacuum chamber cover made of dielectric secured to air And a Faraday shield disposed between the high frequency induction antenna and the vacuum processing chamber, wherein the high frequency induction antenna is divided into n high frequency induction antenna elements, each of which is divided into high frequency induction antenna elements. The induction antenna elements are arranged in a column, and a plurality of sets of each of the high frequency induction antenna elements arranged in a row are provided, and lambda (wavelength of a high frequency power supply) / n is sequentially applied to the high frequency induction antenna elements of each high frequency induction antenna of each set. The delayed high frequency current is sequentially delayed in a predetermined direction to flow, and a rotating induction electric field E rotating in a right direction with respect to the direction of the magnetic field lines of the magnetic field B formed by supplying electric power to the magnetic field coil is applied to the high frequency current. Formed so as to match the rotational frequency of the rotating induction field (E) with the electromagnetic cyclotron frequency caused by the magnetic field (B). At the same time, a plurality of sets of high frequency induction antennas and magnetic fields are provided such that the relationship of E × B ≠ 0 is satisfied at any place between the induction electric field E and the magnetic field B. Is configured to generate plasma, and the sample is plasma-processed by the plasma.

In this plasma processing apparatus, an electrode on which the sample is mounted, a high frequency power supply for bias for applying high frequency power to the electrode, a high frequency power supply for Faraday shield for applying high frequency power to the Faraday shield, and the bias And a phase controller for controlling a phase difference between the high frequency power source for the Faraday shield and the high frequency power source for the Faraday shield, and the phase difference between the high frequency power source for the bias and the high frequency power source for the Faraday shield. This avoids the electrical circuit difficulty of drawing a voltage having a single phase from a power supply having n current outputs phase controlled for n antenna elements. In addition, the nonuniform voltage distribution is prevented from occurring throughout the Faraday shield due to the wavelength shortening effect, so that a uniform self bias can be applied to the inner surface of the vacuum chamber lid. The application of a high frequency voltage of the same frequency to which the voltage phase is controlled is applied to the Faraday shield and the object W having the same electrode configuration as that of the parallel plate capacitively coupled plasma source. It works.

In this plasma processing apparatus, the Faraday shield is grounded through a plurality of filters, and the filters are appropriately provided at intervals of 1/4 or less of the high frequency wavelength for plasma generation, so that the Faraday shield and the ground potential are separated. The impedance of? May be substantially 0? As seen at the frequency of the high frequency power supply for plasma generation, and not substantially 0? As seen at the frequency of the Faraday shield high frequency power supply. By such a configuration, it is possible to prevent the voltage of the high frequency for plasma generation from occurring in the Faraday shield, and to generate the voltage of the Faraday shield for the Faraday shield. Thereby, the voltage of the said Faraday shield can be controlled simply by the output of the high frequency power supply for Faraday shield.

In this plasma processing apparatus, the frequency of the Faraday shield high frequency power supply and the bias high frequency power supply can be lower than the frequency of the plasma generation high frequency power supply. By setting the frequencies of the high frequency power supply for the Faraday shield and the high frequency power supply for the bias in this way, the voltage distribution having the same frequency as the high frequency power supply for the plasma generation is avoided in the Faraday shield, and the uniform voltage is applied to the entire Faraday shield. Can cause a distribution.

In this plasma processing apparatus, the Faraday seal can be said to have a structure covering the whole of the vacuum chamber cover. By constructing the structure of the Faraday shield in this manner, the Faraday shield disposed between the antenna and the plasma can block the capacitive coupling between the antenna and the plasma. As a result, the portion of the insulator cover (just below the antenna) is thinned with a sputterer, making it impossible to use or preventing foreign matter from occurring in this portion. Further, since the insulator cover is sputtered with ions throughout the entire body so that no foreign matter adheres to the insulator cover, foreign matters can be prevented from falling onto the semiconductor wafer.

According to this plasma processing apparatus, the Faraday shield is provided between the high frequency induction antenna and the vacuum processing chamber, and the voltage can be controlled by the Faraday shield high frequency power supply. As a result, a sufficiently strong and uniform electric field due to capacitive coupling from the Faraday shield can be applied to the entire plasma during plasma ignition, so that even a large-diameter plasma processing apparatus can provide a uniform plasma source having good ignition. have.

In this plasma processing apparatus, the Faraday shield may have a structure including a first Faraday shield disposed near the high frequency induction antenna and a second Faraday shield disposed near the vacuum chamber cover. By grounding the first Faraday shield disposed near the high frequency induction antenna, capacitive coupling of the high frequency induction antenna and the plasma can be interrupted. By this structure, the high frequency voltage by the high frequency for plasma generation hardly arises in the 2nd Faraday shield arrange | positioned near the vacuum processing chamber cover. Therefore, the second Faraday shield maintains the function of inductively coupling the high frequency induction antenna and the plasma by the slit, and then prevents the nonuniform voltage of the high frequency for plasma generation from being applied to the plasma, and at the same time, the vacuum vessel cover. A uniform high frequency voltage from the Faraday shield high frequency power supply can be applied.

In this plasma processing apparatus, the first Faraday seal can be arranged only around the high frequency induction antenna. The first Faraday shield close to the high frequency induction antenna blocks the capacitive coupling between the high frequency induction antenna and the plasma by being a ring-shaped conductor, and a large number of slits have a circumferential current in the direction of the high frequency induction antenna to the Faraday shield. By preventing the flow, it can function as a Faraday shield for inductively coupling the high frequency induction antenna and the plasma.

In this plasma processing apparatus, the second Faraday seal may be configured to cover the entire vacuum chamber cover. The second Faraday shield may apply a function of applying a uniform high frequency voltage to the cover of the vacuum vessel, in addition to blocking the capacitive coupling between the antenna and the plasma, which is a basic function of the Faraday shield, but not inhibiting the inductive coupling.

In this plasma processing apparatus, an electrode on which the sample is mounted, a high frequency power supply for bias for applying high frequency power to the electrode, a high frequency power supply for Faraday shield for applying high frequency power to the second Faraday shield, and And a phase controller for controlling a phase difference between the bias high frequency power supply and the Faraday shield high frequency power supply, and the bias high frequency power supply and the Faraday shield high frequency power supply. According to this plasma processing apparatus, the Faraday shield inductively couples the high frequency induction antenna and the plasma by a slit and is phase controlled between the high frequency power supply for bias by the first Faraday shield disposed near the lid of the vacuum chamber. The high frequency voltage output from the shielded high frequency power supply can be applied to the vacuum container cover, and even in an inductively coupled type ECR plasma source, a uniform high frequency voltage can be applied to the vacuum container cover via the Faraday shield.

In this plasma processing apparatus, the frequency of the bias high frequency power supply can be set lower than that of the plasma generation high frequency power supply. By setting the frequency of the bias high frequency power supply in this way, an uneven voltage distribution having the same frequency as that of the plasma generating high frequency power supply can be prevented from being generated in the Faraday shield, so that a uniform voltage distribution can be generated throughout the Faraday shield. have.

In this plasma processing apparatus, the first Faraday seal is a ring-shaped conductor with a slit and can be grounded over its entire circumference. In this way, by grounding the first Faraday shield disposed around the high frequency induction antenna, the capacitive coupling of the high frequency induction antenna and the plasma is interrupted, but the impedance between the first Faraday shield and the ground potential is higher than that of the high frequency power supply for plasma generation. In terms of frequency, it can be substantially 0 ?, and high frequency voltage can be prevented from occurring throughout the first Faraday shield.

According to the present invention, the ECR discharge phenomenon can be used in the plasma processing apparatus using the ICP source. As a result, the antenna structure can be optimized with a minimum of research to improve the uniformity of the plasma and to significantly improve the ignition of the plasma.

That is, according to the present invention, even in a large diameter plasma processing apparatus, it is possible to provide a uniform plasma source having good ignition.

1 is a longitudinal cross-sectional view for explaining the outline of a configuration of a plasma processing apparatus to which the present invention is applied;
2 is a diagram for explaining a power feeding method for a high frequency induction antenna element according to a first embodiment of the present invention;
3 is a view for explaining the relationship between the phase of the current supplied to the high frequency induction antenna in the present invention and the direction of the induced electric field thereby;
4 is a diagram illustrating a distribution of electric field strengths generated by a conventional high frequency induction antenna;
5 is a view for explaining the distribution of electric field strength generated by the high frequency induction antenna of the present invention;
6 is a view for explaining a modification of the power feeding method for the high frequency induction antenna element according to the fifth embodiment of the present invention;
7 is a diagram for explaining a power feeding method for a high frequency induction antenna element according to a sixth embodiment of the present invention;
8 is a view for explaining a power feeding method for a high frequency induction antenna element according to a seventh embodiment of the present invention;
9 is a view for explaining a power feeding method for a high frequency induction antenna element according to an eighth embodiment of the present invention;
10 is a diagram for explaining a power feeding method for a high frequency induction antenna element according to a ninth embodiment of the present invention;
11 is a view for explaining a power feeding method for a high frequency induction antenna element according to a tenth embodiment of the present invention;
12 is a view for explaining a power feeding method for a high frequency induction antenna element according to an eleventh embodiment of the present invention;
13 is a view for explaining various modifications of the lid shape of the vacuum vessel in the plasma processing apparatus according to the present invention;
FIG. 14 is a view for explaining an example in which the cover shape of the vacuum container in the plasma processing apparatus according to the present invention is a hollow hemispherical shape;
FIG. 15 is a view for explaining an example in which the lid shape of the vacuum container in the plasma processing apparatus according to the present invention is a trapezoidal rotating body shape;
FIG. 16 is a view for explaining an example in which the lid shape of the vacuum container in the plasma processing apparatus according to the present invention is a bottomed cylinder; FIG.
17 is a view for explaining the relationship between the magnetic field surface (ECR surface) and the magnetic field lines formed in the present invention,
18 is a view for explaining the relationship between the ECR surface and the plasma generation region corresponding to the shape of the vacuum container lid in the present invention;
19 is a diagram for explaining a power feeding method for a plurality of sets of high frequency induction antenna elements according to the twelfth embodiment of the present invention;
20 is a diagram for explaining a power feeding method for a plurality of sets of high frequency induction antenna elements according to the thirteenth embodiment of the present invention;
21 is a diagram for explaining a power feeding method for a plurality of sets of high frequency induction antenna elements according to the fourteenth embodiment of the present invention;
22 is a diagram for explaining a power feeding method for a plurality of sets of high frequency induction antenna elements according to the fifteenth embodiment of the present invention;
23 is a view for explaining the arrangement of a plurality of sets of high frequency induction antenna elements corresponding to various modifications of the lid shape of the vacuum vessel in the plasma processing apparatus according to the present invention;
24 is a view for explaining a power feeding method for a plurality of sets of high frequency induction antenna elements arranged in a rectangular shape according to the sixteenth embodiment of the present invention;
25 is a view for explaining a power feeding method for a plurality of sets of high frequency induction antenna elements arranged in a rectangular shape according to the seventeenth embodiment of the present invention;
FIG. 26 is a diagram for explaining the distribution of standing waves of voltage and current generated in the antenna element when the standing wave cannot be ignored among one antenna element; FIG.
27 is a view for explaining a method for applying a bias high frequency to the Faraday shield according to the eighteenth embodiment of the present invention;
FIG. 28 is a view showing a state in which a filter is inserted into a plurality of portions in the Faraday shield shown in FIG. 27;
29 is a view for explaining another method of applying a bias high frequency to a Faraday shield according to a nineteenth embodiment of the present invention;
It is a figure explaining the relationship between the frequency f of electromagnetic waves, and cutoff density nc.

The use of the plasma processing apparatus according to the present invention is not limited to the field of manufacturing a semiconductor device, but can be applied to various fields of plasma processing such as the manufacture of liquid crystal displays, the deposition of various materials, the surface treatment, and the like. Here, an embodiment is shown taking a plasma etching apparatus for semiconductor device manufacturing as an example.

1, the outline | summary of the structure of the plasma processing apparatus to which this invention is applied is demonstrated. A high frequency inductive coupling (ICP) type plasma processing apparatus includes a vacuum chamber 11 having a vacuum processing chamber 1 having a vacuum inside thereof, and a vacuum processing chamber including an insulating material for introducing electric fields generated by high frequency into the vacuum processing chamber. Of the lid 12, the vacuum evacuation means 13 coupled to, for example, a vacuum pump to hold the inside of the vacuum processing chamber 1 in a vacuum, and an electrode on which the object to be processed (semiconductor wafer) W is mounted (sample stand). 14, a conveying system 2 having a gate valve 21 for conveying a semiconductor wafer W as an object to be processed between the outside and the inside of a vacuum processing chamber, and a gas inlet for introducing a processing gas ( 3), a bias high frequency power supply 41 for supplying a bias voltage to the semiconductor wafer W, a bias matcher 42, a plasma generation high frequency power source 51, and a plasma generation matcher 52 ), A plurality of delay means [6-2, 6-3 (not shown), 6-4], and a vacuum destination. High frequency induction antenna elements 7-1 (not shown) disposed on the periphery of the chamber 1 and arranged in circumference and divided into a plurality of parts forming the high frequency induction antenna 7 [7-1 (not shown), 7-2, 7-3. (Not shown), 7-4], an electromagnet constituting the box coil 81 and the defect coil 82 for applying a magnetic field, a yoke 83 made of a magnetic material controlling the distribution of the magnetic field, Faraday shield 9 for controlling capacitive coupling of the high frequency induction antenna elements 7-1 (not shown), 7-2, 7-3 (not shown), 7-4 with plasma, and the electromagnet It is comprised with the power supply for magnetic field coils not shown in the figure which supplies electric power.

The vacuum vessel 11 is, for example, an aluminum or stainless steel vacuum vessel with anodized surface, and is electrically grounded. As the surface treatment, not only alumite but also other high plasma resistance substances (for example, yttrium oxide: Y ₂ O ₃ ) can be used. The vacuum processing chamber 1 is provided with the conveying system 2 which has the vacuum exhaust means 13 and the gate valve 21 for carrying in and out of the semiconductor wafer W which is a to-be-processed object. In the vacuum processing chamber 1, an electrode 14 for mounting the semiconductor wafer W concentrically with the cylindrical vacuum container 11 is provided concentrically with the cylindrical vacuum container 11. The wafer W carried into the vacuum processing chamber by the transfer system 2 is transported onto the electrode 14 and held on the electrode 14. A bias high frequency power supply 41 is connected to the electrode 14 via a bias matching device 42 for the purpose of controlling the energy of ions incident on the semiconductor wafer W during the plasma processing. The etching processing gas is introduced into the vacuum processing chamber 1 from the gas introduction port 3.

On the other hand, high frequency induction antenna elements 7-1 (not shown), 7-2, 7-3 (not shown), 7-4] are planar quartz or alumina at positions facing the semiconductor wafer W. It is provided in the air side via the vacuum container cover 12 which consists of insulating materials, such as a ceramic. The high frequency induction antenna elements (..., 7-2, ..., 7-4) are arranged concentrically so that the center thereof coincides with the center of the semiconductor wafer (W). Although the high frequency induction antenna elements (..., 7-2, ..., 7-4) are not specified in Fig. 1, they are composed of antenna elements having a plurality of identical shapes. The power supply terminals A of the plurality of antenna elements are connected to the plasma generation high frequency power supply 51 via the plasma generation matching unit 52, and the ground terminal B is connected to the ground potentials exactly the same. .

Between the high frequency induction antenna elements (..., 7-2, ..., 7-4) and the plasma generating matching unit 52, a current flowing through each of the high frequency induction antenna elements (..., 7-2, ..., 7-4) Delay means 6-2, 6-3 (not shown), 6-4 are provided to delay the phase of the signal.

The vacuum container lid 12 is provided with a cooling refrigerant path not shown in the drawings, and is cooled by flowing a fluid such as water, fluorinate, air, nitrogen, and the like into the refrigerant passage. The antenna, the vacuum vessel 11, and the wafer mounting table 14 are also subject to cooling and temperature control.

(Example 1)

2, a first embodiment of a plasma processing apparatus according to the present invention will be described. In this embodiment, as shown in FIG. 2 (a) seen from above in FIG. 1, n = 4 (an integer of n ≧ 2) high frequency induction antenna elements 7-1 on one circumference. To 7-4). The feed end A or ground end B of each of the high frequency induction antenna elements 7-1, 7-2, 7-3, 7-4 is 360 ° / 4 (360 ° / n in the clockwise direction). Are disposed apart from each other, and are fed to each of the high frequency induction antenna elements 7-1, 7-2, 7-3, and 7-4 from the plasma generation high frequency power source 51 through the plasma generation matching unit 52, The high frequency current is supplied from the feed point 53 via each feed end A. FIG. In this embodiment, each of the high frequency induction antenna elements 7-1 to 7-4 is about λ / 4 (λ / n) away from the feed end A side in the same circumferential right direction, respectively. ) Side is arranged. The length of each of the high frequency induction antenna elements 7-1 to 7-4 need not be λ / 4 (λ / n), but is preferably equal to or less than λ / 4 (λ / n) of the generated standing wave. In addition, depending on the configuration of the antenna, the length of each high frequency induction antenna element may be λ / 2 or less. Between the feed point 53 and the feed ends A of the high frequency induction antenna elements 7-2, 7-3, and 7-4, the? / 4 delay circuit 6-2 and? / 2 delay circuit ( 6-3), a 3λ / 4 delay circuit 6-4 is inserted. As a result, the currents I ₁ , I ₂ , I ₃ , and I ₄ flowing through each of the induction antenna elements 7-1 to 7-4 are sequentially lambda / 4 (lambda) as shown in FIG. The phase is delayed by / n). Electrons in the plasma driven by the current I ₁ continue to be driven by the current I ₂ . The electrons in the plasma driven by the current I ₃ continue to be driven by the current I ₄ .

3, the driving mode of the electrons in the plasma in the case of using the high frequency induction antenna shown in FIG. 2 will be described. In Fig. 3, the configurations of the feed end A and the ground end B of the high frequency induction antenna elements 7-1, 7-2, 7-3, and 7-4 are the same as in Fig. 2. In addition, it is indicated that the directions of currents I ₁ to I ₄ flowing through each induction antenna element are all directed from the feed end A to the ground end B. FIG. As for the current flowing through each of the high frequency induction antenna elements, the phases of I ₁ to I ₄ are shifted by 90 degrees, respectively. The phase shift of 90 ° has a relationship of 360 ° / 4 = 90 ° in order to allocate one period (360 °) of high frequency current to four high frequency induction antenna elements. The electric current I and the induction electric field E here are related to the Maxwell's equation shown by following formula (1) and formula (2) using the induction magnetic field (H). In Equations (1) and (2), E, H, and I are vectors of all electric fields (fields) and magnetic fields (magnetic fields) and currents of the plasma by the high frequency induction antenna, μ is the permeability, ε is Permittivity.

The right side of Fig. 3A shows the phase relationship of the currents. The direction in the area | region enclosed by the high frequency induction antenna of the induction electric field E at the specific time (t = t1) shown here is shown by the dotted line and the arrow to the left of FIG. As can be seen from this direction, the distribution of the induction electric field E becomes linearly symmetric in the plane where the antenna is arranged, that is, the plane produced by the antenna. Fig. 3 (b) shows the direction of the induced electric field E when the phase of the current is further advanced by 90 degrees from this Fig. 3 (a). The direction of the induction electric field E is rotated 90 degrees clockwise. 3 shows that the high frequency induction antenna according to the present invention generates an induction electric field E that rotates right with time, that is, rotates clockwise. When electrons exist in the induction electric field E rotating to the right, the electrons are also driven to the induction electric field E and rotate right. In this case, the rotation period of the former coincides with the frequency of the high frequency current. However, it is possible to make an induction electric field (E) having a rotation period different from the frequency of the high frequency current by engineering research, wherein the electrons rotate at the same period as the rotation period of the induction electric field (E), not the frequency of the high frequency current. do. As described above, in the present invention, electrons are driven in the induction electric field E as in the case of a normal ICP source. However, the driving of electrons in a certain direction (right direction in this figure) irrespective of the phase of the current I of the high frequency induction antenna, and there is no moment when the rotation stops, the conventional ICP source of the present invention This is different from helicon plasma sources.

Here, a description will be given of what induced electric field E is generated in the plasma by the high frequency induction antenna of the present invention. Here, the induction electric field E is described, but as shown in Equation (1), the induction electric field E and the induction magnetic field H are physical quantities which can be converted to each other, and are equivalent. First, FIG. 4 schematically shows the distribution of the induced electric field E produced by the conventional ICP source. In the conventional ICP source, since the antenna is circumferential and circles or the antenna is divided, in-phase current flows through the antenna, so the induced electric field E generated by the antenna becomes the same in the circumferential direction. That is, as shown in FIG. 4, the maximum value of the induction electric field E appears directly under the antenna, and the electric field distribution of the donut shape which attenuates with respect to the center of the antenna and the antenna periphery is made. This distribution is point symmetrical about the center point O in the X-Y plane. In theory, the induced electric field E at the center point O of the antenna is E = 0. This donut-shaped electric field distribution rotates to the right or to the left in accordance with the direction (half cycle) of the current. The rotational direction of the induction field E is reversed when the current becomes zero, and the induction field E is once E = 0 in all regions. Such an induction electric field E has already been measured as an induction magnetic field H and confirmed (for example, refer nonpatent literature 2).

Next, the induction electric field E produced by the antenna of the present invention will be described. First, the same current state as in Fig. 3A can be considered. That is, a positive peak current flows through I ₄ , and a reverse peak current flows through I ₂ . On the other hand, I ₁ and I ₃ are small. In this case, the maximum value of the induction electric field E is shown below the antenna element 7-4 through which I ₄ flows and the antenna element 7-2 through which I ₂ flows. In addition, under the antenna elements 7-1 and 7-3 where almost no current flows, a strong induced electric field E does not appear. 5 schematically illustrates this. Here, two peaks appear on the axis of the XY plane. As apparent from Fig. 5, the induction electric field E of the present invention has two large peaks on the periphery of the antenna and is also axisymmetric in the XY plane (Y-axis symmetry in this figure). Then, a distribution having a gentle peak appears on the Y axis. The peak height of this gentle distribution is low and its position appears in the center coordinate (O). In other words, the induced electric field at the center point O of the antenna is not E = 0. Thus, in the structure of FIG. 2 by this invention, the induction electric field E which is completely different from a conventional ICP source and a helicon plasma source is produced | generated, and it is different from the phase of the current I of a high frequency induction antenna. Regardless, it rotates in a constant direction (the right direction in this figure). 3, there is no instant when the current I flowing through all the high frequency induction antenna elements becomes I = 0 at the same time. Therefore, it is also a feature of the present invention that there is no instant when the rotating induction electric field E becomes E = 0.

In the present invention, an induction field distribution having such a local peak is generated, but this does not deteriorate the uniformity of the generated plasma. First, the induction field distribution on the X axis of FIG. 5 is determined by the induction field distribution generated by the antenna. That is, when the same current flows, the distribution of the induction field distribution on the axis of FIG. 4 and the induction field on the axis of FIG. 5 is a symmetric induction field having two peaks around the center point O. same. In addition, since the induction electric field of the present invention rotates at the same frequency as the high frequency current flowing through the antenna, when it is averaged in one cycle of the high frequency current, an induction electric field distribution that is point symmetric with respect to the center point O in the X-Y plane is generated. That is, in the present invention, a completely different induction field distribution can be produced, but a good feature of the conventional ICP source, that is, the induction field distribution is determined by the structure of the antenna, and point symmetry can generate a uniform plasma in the circumferential direction. It retains its features.

Here, by using the upper and lower magnetic field coils 81 and 82 and the yoke 83 shown in FIG. 1, the magnetic field B having the magnetic field component perpendicular to the rotational surface of the induction electric field E can be applied. In the present invention, there are two conditions under which this magnetic field B must be satisfied. First, the rotation direction of the rotating induction electric field E is applied with the magnetic field B which always turns right with respect to the direction of the magnetic field lines of the magnetic field B. For example, in the structure of FIG. 2, as demonstrated so far, the induction electric field E rotates clockwise direction, ie, right direction with respect to the ground. In this case, the component of the direction from the surface of the paper surface to the back surface is required for the direction of the magnetic force line. As a result, the rotational direction of the induced electric field E coincides with the rotational direction of the Larmor motion of the former. This first condition can also be expressed as applying a magnetic field B in which the rotational direction of the induced electric field E coincides with the rotational direction of the Larmor motion of the former.

The remaining condition is to apply a magnetic field B such that E × B ≠ 0 to the induction electric field E. However, this condition E x B? 0 is required somewhere in the space where the plasma is to be generated, but is not necessary in all the spaces where the plasma is to be generated. There are various methods of applying a magnetic field, but this condition "E x B? 0" is included in the first condition described above, unless a magnetic field having a locally complex structure is used. Under the condition of "E x B? 0", the former performs a rotational movement called a Larmor motion with the magnetic force line as the center. This Larmor motion is not called the rotational motion by the rotation induction field described above, and is called electron cyclotron linkage. The rotation frequency is called electron cyclotron frequency (ωc) and is represented by the following equation (3). In the following formula (3), q is a small charge of an electron, B is a magnetic field strength, and me is a mass of an electron. The characteristic of this electronic cyclotron motion is that the frequency is determined only by the magnetic field strength.

Here, if the rotation frequency f of the rotating induction electric field E is matched with the cyclotron frequency ωc such that 2πf = ωc, electron cyclotron resonance occurs, and the high frequency power flowing through the high frequency induction antenna resonates resonantly. It can be absorbed by the electrons and generate a high density plasma. However, the condition of "matching the rotational frequency f of the induction electric field E with this cyclotron frequency ωc" is necessary somewhere in the space where the plasma is to be generated, but is necessary in all the spaces where the plasma is to be generated. It is not. The conditions for generating this ECR are represented by the following equation (4) as described above.

The magnetic field B applied here may be a static magnetic field or a variable magnetic field. However, in the case of the fluctuating magnetic field, the fluctuation frequency fB must satisfy the relation of 2πfB < ωc between the rotational frequency (electron cyclotron frequency ωc) of the Larmor motion. This relationship means that the change in the fluctuating field is small enough and can be regarded as a static field in the circumferential cycle of electrons carrying out the electron cyclotron motion.

By the above, using the plasma heating method called electron cyclotron (ECR) heating, the plasma generation capability of an electron can be raised dramatically. In consideration of obtaining desired plasma characteristics in industrial applications, however, the antenna structure is optimized to control the intensity and distribution of the induced electric field E, and the intensity distribution of the magnetic field B is variably controlled. As a result, it is preferable to form a space that satisfies the conditions of the magnetic field B and the frequency as necessary and control plasma generation and its diffusion. 1 is an embodiment considering this.

The method for enabling ECR discharge in the ICP source described in the present invention can be used as long as it satisfies the conditions described so far, regardless of the high frequency or magnetic field strength to be used. Of course, with respect to engineering applications, there are limitations on the frequencies and magnetic field strengths that can be used by realistic limitations such as what size of the vessel of the plasma to generate. For example, when the radius rL of the Larmor motion of the electrons represented by the following equation is larger than the container confining the plasma, the ECR phenomenon does not occur because the electrons collide with the container wall without rotating. In Equation (5), v is the velocity of electrons in the direction parallel to the plane of the electric field shown in FIG.

In this case, naturally, it is necessary to increase the frequency of the high frequency to be used and to increase the magnetic field strength so that the ECR phenomenon occurs. However, the selection of the frequency and the magnetic field strength should be freely selected according to the purpose, and the principle itself shown by the present invention is not impaired at all.

Here, the necessary sufficient conditions of the principle for enabling ECR discharge in the ICP source shown in the present invention are summarized as follows. The first is to form the distribution of the induced electric field E which always rotates right with respect to the direction of the magnetic force line of the magnetic field B to be applied to the space generating the plasma. Second, a magnetic field B that satisfies E x B? 0 is applied to the distribution of the magnetic field B and the induced electric field E that rotates right with respect to the direction of the magnetic force line. The third is to match the rotational frequency f of the rotating induction electric field E with the electromagnetic cyclotron frequency ωc caused by the magnetic field B. Fourth, the change in the magnetic field B is small enough and can be regarded as a static magnetic field when viewed in the cyclic period of electrons carrying out the electron cyclotron motion. If the embodiments satisfying the above four conditions satisfy the above-mentioned necessary and sufficient conditions even if the embodiment of Fig. 1 or Fig. 1 is modified, ECR discharge can be performed from the ICP source even if any modification is made. In other words, no matter how the apparatus configuration of Fig. 1 is modified, it must be noted that the above-mentioned sufficient condition is satisfied to be an embodiment of the present invention. The modifications are merely a matter of engineering design and do not alter the physical principles represented by the present invention. Below, the modified example of FIG. 1 is put together.

In Fig. 1, the vacuum container cover 12 is made of a flat insulating material, and a high frequency induction antenna 7 is formed thereon. This configuration means that the induced electric field E always rotates right with respect to the direction of the magnetic field lines of the magnetic field B in a space where a plasma is to be generated, that is, a space sandwiched between the vacuum container cover 12 and the object W to be processed. It is possible to form a distribution of. The above is the first content of the necessary sufficient conditions. Therefore, neither the vacuum container cover 12 is a flat insulator nor the high frequency induction antenna 7 is comprised on the vacuum container cover 12 is not an essential structure in this invention. For example, the vacuum container cover 12 may be a trapezoidal rotating body shape or a hollow hemispherical shape, that is, a dome shape or a bottomed cylindrical shape. Moreover, the high frequency induction antenna may be in any position with respect to the vacuum container cover. According to the principle of the present invention, the shape of the vacuum container cover 12 and the antenna position with respect to the vacuum container cover are all one embodiment of the present invention as long as the configuration satisfies the necessary and sufficient conditions.

However, in industrial use, the shape of the vacuum container cover and the antenna position with respect to the vacuum container cover have an important meaning. This is because uniform processing within the surface of the object W is required. That is, the components of the gas species constituting the plasma such as ions and radicals used for the treatment on the target object W must form a uniform distribution.

The plasma is generated by dissociation, excitation and ionization of the process gas by high energy electrons. The radicals and ions generated at this time have a strong electron energy dependency, and not only the generation amount but also their generation distribution differs from the radical and the ion. As a result, it is virtually impossible to generate radicals and ions in exactly the same distribution. The generated radicals and ions are diffused by diffusion, but their diffusion coefficients vary depending on the type of radicals and ions. In particular, the diffusion coefficient of ions is usually larger than the neutral radical diffusion coefficient. That is, it is virtually impossible to make uniform distribution of radicals and ions simultaneously on the to-be-processed object W using diffusion. Moreover, when a process gas is a molecule | numerator or a mixture of many kinds of gas generate | occur | produces plasma, since a plurality of types of radicals and ions generate | occur | produce, it is further impossible to make uniform distribution of all radicals and ions. However, what is important for the uniform treatment is by which gas species the process in which the plasma is applied proceeds. For example, if the reaction proceeds to a particular radical subject, it is important to make the distribution of that radical uniform. On the contrary, if the reaction proceeds mainly by sputtering by ions, it is important to make the distribution of the ions uniform. In addition, radicals and ions may compete with each other for the reaction to proceed. In order to cope with these various processes, it is required to control the generation distribution of the plasma and its diffusion, and to advance each process with more preferable uniformity.

There are two kinds of countermeasures to this request in the present invention. The reason for this is that in the present invention, the energy of electrons for generating plasma is determined by E x B, in simple terms, the induced electric field E and the magnetic field B. The first countermeasure is related to the induction electric field E, and, for each process, optimizes the shape of the vacuum container lid 12 made of an insulator and the antenna position thereof. As described above, in the present invention, the generation distribution of plasma is determined by the configuration of the antenna as in the normal ICP source. This is because the strongest induced electric field E is formed near the antenna. In addition, it is possible to control the distribution of radicals and ions generated by the vacuum container lid and the width of the space to be processed and the vacuum container. This is deeply related to the second countermeasure magnetic field B, but in order to make the description easy to understand, it is explained without considering the magnetic field.

FIG. 13 schematically shows what shape the distribution on the object W to be formed has with respect to the shape and the antenna position of the vacuum container cover 12 made of four kinds of insulators. For simplicity of explanation, this distribution is referred to as distribution of ions. FIG. 13A shows a case where the vacuum container cover 12 made of an insulator has a flat plate shape. The high frequency induction antenna element 7 is above the vacuum vessel cover 12 which is an insulator, and a space P for generating ions (plasma) appears just below the antenna. The ions generated at this time diffuse and spread to the space surrounded by the vacuum container cover 12 and the vacuum container 11. If described qualitatively, the diffusion direction at this time is mainly downward. It is assumed that the M-type ion distribution is formed on the workpiece W by the diffusion. Here, it is assumed that the distance d between the antennas is made small as d 'shown in Fig. 13B. By the change of the antenna position, the diffusion of ions is further directed toward the center of the object W. Therefore, the ion distribution on the to-be-processed object W can be made higher center. In addition, although not shown, when the antenna spacing is further widened, the M-type distribution of ions is changed in the more emphasized direction. That is, the structure change of the antenna is very useful for controlling the distribution of ions. However, only by changing the antenna structure, the same distribution change occurs for ions and radicals other than ions considered here. This is because there is little change in the area of the plasma generating area relative to the antenna, and the space formed by the vacuum container cover 12 and the vacuum container 11 made of an insulator has the same shape.

Such distribution control is possible by changing the shape of the vacuum container lid 12 made of an insulator. 13 (c), (d) and (e), a hollow hemispherical shape, that is, a dome-shaped vacuum container cover, a vacuum container cover having a space inside the rotating trapezoid (a trapezoidal rotating body shape) and a bottomed cylindrical shape, respectively. The ion distribution at the time of changing to the vacuum container lid of the present invention is schematically shown. As can be understood by this, as the shape of the vacuum container lid 12 made of the insulator is changed from (a) to (c), (d) and (e) in FIG. 13, the diffusion of ions toward the center increases more. It is. Therefore, as shown in (a) to (c), (d) and (e) in FIG. 13, the ion distribution on the workpiece W becomes higher in the center.

Here, in Fig. 13 (b) and (d), the ion distribution on the workpiece W is shown to be of the same type. This can be realized by appropriately designing the structure of the actual apparatus. However, there is a critical difference between the change from Fig. 13A to Fig. 13B and the change from Fig. 13A to Fig. 13D. This is different from the volume of the space made by the vacuum container cover 12 and the vacuum container 11 made of an insulator and its surface area.

First, ions are very unlikely to dissipate in space, and their dissipation is mainly due to charge release on the wall surface. This is because, in order to extinguish in space, a very rare reaction is required, for example, colliding with two electrons simultaneously (three collision). In addition, there is a limitation that the collision of ions to the wall must not be equivalent to electrons (semi-neutral conditions of plasma). However, radicals are neutral excitation species and easily collide with single electrons or other molecules to lose their active energy. The opposite can also be the case. The radicals also impinge on the walls and lose their excitation energy, but their inflow is independent of the semi-neutral condition of the plasma and is determined only by the amount of diffusion into the walls. Of course, as mentioned above, the diffusion coefficients of ions and radicals differ greatly. In other words, by changing the volume and the surface area of the space created by the vacuum container lid 12 and the vacuum container 11 made of an insulator, the degree of generation, diffusion and extinction of radicals to ions can be further changed. As mentioned above, it turns out that the change from FIG. 13 (a) to (d) can control distribution of ion and radical more dynamically compared with the change from FIG. 13 (a) to (b).

The second countermeasure is to optimize the generation and diffusion of the plasma by variably controlling the shape of the vacuum container cover 12 which is related to the magnetic field B and made of an insulator and its magnetic field distribution. In the embodiment shown in FIG. 1, the intensity of the magnetic field and its distribution are controlled by the current flowing through the upper and lower magnetic field coils 81 and 82 and the shape of the yoke 83. At this time, for example, a magnetic field as shown in FIG. 17 can be generated. The characteristic of this magnetic field is that the direction of the magnetic field lines is downward. The direction of the magnetic force line, the rotational direction of the electric field shown in FIG. 3 and the Larmor motion of the former from the electric field direction shown in FIG. 3 become the same right turn with respect to the magnetic force line direction. In other words, this magnetic field is an example of satisfying the first and second of the necessary and sufficient conditions.

The stirrup is formed in a plane perpendicular to the lines of magnetic force. Although there are a number of stirrups, the example is shown in FIG. Here, when the rotation period of the induction field distribution rotating in the constant direction is 100 MHz, from the equation (3), about 35.7 gaussian magnetic field surface is the magnetic field strength surface that causes the ECR discharge. This is called the ECR plane. In this example, the ECR plane is convex downward, but may be flat or upward convex. In the present invention, it is essential to make the ECR plane in the plasma generation unit, but the shape of the ECR plane is arbitrary. The ECR surface can be moved up and down by varying the current flowing through the upper and lower magnetic field coils 81 and 82, and the surface shape can be further convex downward, and can be flat or upward. It can also be convex.

Next, what effect occurs when the ECR surface and the deformation | transformation of a vacuum container cover form are combined is demonstrated using FIG. Fig. 18A is exactly the same as Fig. 13A, and schematically shows a plasma generation region (check-shaped region) and its diffusion direction when there is no magnetic field. An example of when the ECR surface is formed in FIG. 13 (a) is shown in FIG. 18 (b). Here, the important thing is that (1) The plasma generation area | region by ECR exists along the ECR surface. With this alone, it can be understood qualitatively that the areas where ions and radicals in the plasma are different are compared when there is no magnetic field and when the ECR surface is formed. Next, (2) the intensity of the discharge becomes stronger depending on the size of the induced electric field E when there is no magnetic field, but becomes stronger according to the size of E × B in the ECR discharge. (3) In the ECR, since the electrons resonantly absorb the energy of the electric field, the intensity of the discharge is overwhelmingly strong in the ECR, even when there is no magnetic field, even with the same induction field (E). These (2) and (3) also show that, in comparison with the absence of the magnetic field and the formation of the ECR plane, the ions and radicals generated in the plasma are different in principle. Of course, in the embodiment shown in Fig. 1, by changing the current flowing through the upper and lower magnetic field coils 81 and 82 and the shape of the yoke 83, the upper and lower positions of the surface shape of the ECR face and the vacuum container cover of the ECR face are greatly increased. Since it can be changed, compared with the case where there is no magnetic field and when the ECR surface is formed, it becomes possible to change the generation area | region of the ion and radical in a plasma significantly.

The formation of the ECR surface also differs in the state of diffusion compared with the absence of a magnetic field. That is, since the ions and electrons in the plasma are charged particles, they tend to diffuse along the magnetic field and are difficult to diffuse vertically into the magnetic field. This is because electrons diffuse along the lines of magnetic force in the state wound around the lines of magnetic force by Larmor motion, and ions diffuse in the same direction as the electrons by request from the semi-neutral condition of plasma. However, since the radical is a neutral particle, there is no influence of the magnetic field on its diffusion. In other words, the formation of the ECR surface not only changes the generation region of ions and radicals, but also affects the distribution shape due to diffusion of ions and radicals. In other words, the magnetic field is a very useful means of controlling plasma live vesicles and diffusion. (C), (d), (e) is a figure corresponding to FIG. 13 (c), (d), (e), and the shape of the vacuum container cover 12 which consists of an insulator is a hollow hemispherical shape, respectively. In other words, the plasma generation area when the dome-shaped vacuum container cover, the trapezoidal rotating vacuum container cover having a space inside the trapezoidal rotating body (the trapezoidal rotating body shape), and the cylindrical vacuum container cover with the bottom are shown schematically. Of course, since the size of the space and surface area made by each vacuum container cover is different, the difference between diffusion and extinction described using FIG. 13 is also the same in principle.

There is another thing that can be said in FIG. In this invention, when using the helicon wave represented by patent document 5, it does not need the characteristic longitudinally long vacuum container. In the present invention, as shown in Fig. 18 (b), it is possible to freely select either a horizontally long vacuum vessel or a vertically long vacuum vessel as shown in Fig. 18 (e). This is possible when the helicon wave is excited, but the absorption length must be long (the vacuum vessel is lengthened) so that the helicon wave propagating is sufficiently absorbed during the propagation. This is because a long absorption length is unnecessary because is absorbed. In the present invention, the space for absorbing the energy of the induced electric field is large enough to form the ECR plane (the magnetic field surface and the rotating surface of the electron). This is because the ECR plane is a simple resonance plane, not a wave propagating in any direction. This is a crucial difference between using a helicon wave and using an ECR plane, which is why the present invention has sufficient practicality compared with a helicon plasma source.

As described above, the present invention provides an apparatus for adjusting the generation, diffusion, and extinction of plasma, which includes (1) an antenna structure, (2) a structure of a vacuum container cover 12 made of an insulator, and (3) a magnetic field. It has three kinds. Such a feature is a feature that cannot be easily obtained from a plasma source such as an ICP source, an ECR plasma source, or a parallel flat plate type. In particular, the magnetic field is variable by the current flowing through the upper and lower magnetic field coils 81 and 82 even after the device structure such as the shape of the antenna container or the shape of the vacuum container cover 12 made of the insulator is varied, thereby further generating the plasma generation region and its diffusion. It can be controlled dynamically.

(Example 2)

As a second embodiment, a second example of the shape of the vacuum chamber lid will be described with reference to FIG. In Fig. 14, except for the shape of the vacuum chamber cover 12, the structure of the plasma processing apparatus of Fig. 1 is substantially the same, and the same parts are denoted by the same reference numerals, and their description is omitted. Although the vacuum chamber cover 12 of FIG. 1 is comprised with the plate-shaped (disk-shaped) insulating material, in this example, the vacuum chamber cover 12 which consists of an insulator is formed in hollow hemispherical shape, ie, dome shape, As described above, the vacuum processing chamber 1 is configured to be hermetically fixed to the apex of the cylindrical vacuum container 11. This configuration forms a plasma generation region on the ECR surface as shown in Fig. 18C.

(Example 3)

As a third embodiment, a third example of the shape of the vacuum chamber lid will be described with reference to FIG. In FIG. 15, except for the shape of the vacuum chamber chamber 12, the structure of the plasma processing apparatus of FIG. 1 is substantially the same, and the same parts are denoted by the same reference numerals, and description thereof is omitted. In this example, the vacuum chamber cover 12 made of an insulator is formed in a shape having a flat ceiling by removing the apex of the hollow cone and having a space therein, and as shown in the apex of the cylindrical vacuum vessel 11. It is hermetically fixed to a part and comprises the vacuum processing chamber 1. In this specification, the shape of this vacuum container cover 12 is called a trapezoidal rotating body. This configuration forms a plasma generation region P on the ECR surface as shown in Fig. 18D.

(Example 4)

As a fourth embodiment, a fourth example of the shape of the vacuum chamber lid will be described with reference to FIG. In Fig. 16, except for the shape of the vacuum chamber cover 12, the structure of the plasma processing apparatus of Fig. 1 is substantially the same, and the same parts are denoted by the reference numerals, and the description thereof is omitted. In this example, the vacuum chamber cover 12 made of an insulator is formed in a shape having a space inside as a cylinder having a bottom, and airtight at the apex of the cylindrical vacuum chamber 11 so that the bottom is upward as shown. It is fixed so as to constitute the vacuum processing chamber (1). In this specification, the shape of this vacuum container cover 12 is called a cylinder with a bottom. By this configuration, as shown in Fig. 18E, the plasma generation region P is formed on the ECR surface.

In these examples, the functions are the same as in the embodiment shown in FIG. The difference is that the range of the distribution control of the ions and radicals of the plasma generated by each plasma source (the generation region and the degree of diffusion / dissipation) is different. The selection of these plasma sources should be selected by which process the present invention is applied.

(Example 5)

In Fig. 1 (Fig. 2), the feed end A and the ground end B of the arc-shaped high frequency induction antenna elements 7-1, 7-2, 7-3, and 7-4 obtained by dividing the circle into four are shown. They are arranged on one circumference to be pointymmetric to ABABABAB. This "arrangement so that the feed terminal and the ground terminal are point symmetrical" is also not an essential configuration for realizing the first content of the necessary sufficient condition. The feed end A and the ground end B can be arranged freely. As a fifth embodiment, this embodiment corresponding to FIG. 2 is shown in FIG. In FIG. 6, as an example, the positions of the feed end A and the ground end B of the high frequency induction antenna element 7-1 are reversed to reverse the direction of the high frequency current I ₁ . In this case, however, the phase of the high frequency current I ₁ flowing in the high frequency induction antenna element 7-1 is inverted from the phase shown in Fig. 2 (for example, delayed by 3λ / 2), and is shown in Fig. 5. It can produce a rotating induced electric field (E). It can be seen from this that inverting the positions of the feed terminal A and the ground terminal B is the same as inverting the phase: delaying [lambda] / 2.

(Example 6)

By using this, the structure of FIG. 2 can be further simplified, and this is shown in FIG. 7 as a sixth embodiment. Each of the 7 of the arrangement, in FIG. 2 I ₁ and I _3, I ₂ and I ₄ λ / 2 delay, that is to be used that are inverted, in each statue to I ₁ and I _3, I ₂ and I ₄ The current flows, but the feed terminal A and ground terminal B of I ₃ and I ₄ are inverted. In addition, since the lambda / 4 delay (6-2) is inserted between I ₁ and I ₃ , I ₂ and I ₄ , an induction electric field E (shown in FIG. 5) which rotates in the same manner as in FIG. 2 is formed. can do. As described above, many variations can be produced by combining the configuration of the high frequency induction antenna and the phase control. However, these modifications are only engineering designs, and all of them constitute one embodiment of the present invention when they are configured to satisfy the first content of the necessary sufficient condition.

(Example 7)

In Fig. 1, a phase delay circuit is provided between the matching unit in the power supply output section and the high frequency induction antenna elements 7-1 to 7-4. This "providing a phase delay circuit between the matcher and the high frequency induction antenna elements 7-1 to 7-4" is also not an essential structure for realizing the first content of the necessary sufficient condition. In order to satisfy the first content of the necessary sufficient condition, only a current is passed through the high frequency induction antenna so as to form the rotating induction electric field E shown in FIG. Here, similarly to Fig. 2, a rotating induction electric field E shown in Fig. 5 is formed, but as a seventh embodiment, an embodiment of another configuration is shown in Fig. 8. The configuration of Fig. 8 is the high frequency induction antenna elements 7-1 to 7-4 by the same number of high frequency power supplies 51-1 to 51-4 as the high frequency induction antenna elements 7-1 to 7-4. The current flows through the output of one transmitter 54, but without delay means and with the? / 4 delay means 6-2 and? / 2 delay means 6-3 and 3λ / 4 delay means 6-4. The high frequency power supplies 51-1 to 51-4 and matching devices 52-1 to 52-4 are respectively connected to each other to perform necessary phase delays. By increasing the high frequency power supply 51 in this manner, the matching circuit 53 increases, but the amount of power of the high frequency power supply alone can be reduced, and the reliability of the high frequency power supply can be increased. Further, by finely adjusting the power supplied to each antenna, the uniformity of the plasma in the circumferential direction can be controlled.

(Example 8)

Such variations in power supply configuration and high frequency induction antenna configuration are not limited to this one. For example, if the configuration shown in Figs. 2 and 8 is applied, the rotating induction electric field E shown in Fig. 5 is formed similarly to Fig. 2, but other configurations can be made. As an eighth embodiment, this embodiment is shown in FIG. In the embodiment of Fig. 9, two high-frequency power supplies 51-1 connected to the transmitter 54 and two high-frequency power supplies 51-2 connected via the lambda / 2 delay means 6-3 are mutually connected. High frequency delayed lambda / 2 is output to feed points 53-1 and 53-2, and lambda / 4 delay means 6-2 between these outputs and high frequency induction antenna elements 7-2 and 7-4. ) To make the necessary delay.

(Example 9)

The following embodiment combines the embodiment of Fig. 9 and Fig. 7, which is shown as Fig. 10 as the ninth embodiment. In FIG. 10, two high frequency power sources 51-1 and 51-2 connected to the same transmitter 54 as in FIG. 9 are used, but the phase is one high frequency power source 51- at the output of the transmitter 54. In FIG. The phase shifter is shifted by inserting the lambda / 4 delay means 6-2 on the 3) side, and the high frequency induction antenna elements 7-1 and 7-2 are provided with a feed end A and a ground end ( B) is set in the same manner as in FIG. 9, and the high frequency induction antenna elements 7-3 and 7-4 have a feed end A and a ground end B in the same manner as in FIG. , 7-2) in the reverse direction (inverted). If the reference of the phase of this output is the phase of I ₁ , I ₁ and I ₃ become in-phase currents, but the direction of I ₃ (feeding stage A and grounding stage B) is inverted compared with FIG. 2. As a result, the induced electric field E formed by I ₁ and I ₃ becomes as shown in FIG. 2. In addition, I ₂ and I ₄ have a λ / 4 delay in phase compared to I _1, and I ₂ and I ₄ also become in-phase currents, but in the direction of I ₄ (feeding end A and ground end B). ] Is inverted in comparison with FIG. 2, so that the induced electric field E formed by I ₂ and I ₄ becomes the same as in FIG. 2. As a result, the embodiment shown in FIG. 10 has a configuration different from that in FIG. 2, but forms the same induction electric field E as in FIG.

That is, this embodiment includes a vacuum vessel constituting a vacuum processing chamber capable of accommodating a sample, a gas inlet for introducing a processing gas into the vacuum processing chamber, a high frequency induction antenna provided outside the vacuum processing chamber, and a magnetic field in the vacuum processing chamber. And a high frequency power supply for plasma generation, and a power supply for supplying electric power to the magnetic field coil, and supplying a high frequency current from the high frequency power supply to the high frequency induction antenna. In the plasma processing apparatus for plasma-processing a sample by converting a gas supplied into a vacuum processing chamber, in particular, the high frequency induction antenna is divided into s (s is a positive even number) of high frequency induction antenna elements, The high frequency induction antenna elements of the column arranged in a column on the circumference and arranged in the column The high frequency induction antenna element is delayed by λ (wavelength of the high frequency power supply) / s in advance from each of the s / 2 high frequency power supplies to the high frequency induction antenna elements from the first high frequency induction antenna element to the s / 2th high frequency induction antenna element. Supplied to the high frequency induction antenna element, and from the s / 2 + 1th high frequency induction antenna element to the sth high frequency induction antenna element, in order from the first to s / 2th high frequency induction opposite to the high frequency induction antenna element Supply the high frequency current of the same phase as that of the antenna element, but configure the high frequency induction antenna element so that the direction of the current flowing through the high frequency induction antenna element is reversed, and form an electric field rotating in a predetermined direction to plasma-process the sample. Thus, the magnetic field coil is formed in a right direction with respect to the direction of the magnetic field of the magnetic field formed by supplying electric power. Spilling the delays in the order, it will configured to generate a plasma to form electric field rotating in a certain direction so that the sample and the plasma treatment.

In Fig. 1 (Fig. 2), circular arc-shaped high frequency induction antenna elements 7-1, 7-2, 7-3, and 7-4 are arranged on one circumference. This configuration of " four divisions " is not an essential configuration for realizing the first content of the necessary sufficient condition. The division number of the high frequency induction antenna may be considered an integer n that satisfies n ≧ 2. One circumferential high frequency induction antenna 7 may be configured using n circular arc antennas (high frequency induction antenna elements). In addition, although FIG. 1 shows the method of forming the induction electric field E which rotates right with respect to the direction of the magnetic field by the phase control of the electric current which flows in a high frequency, it can form reliably as n≥3. The case of n = 2 is special, for example, two semicircular antennas are used to form one circumference, each with a phase difference of (360 °) / (2 antennas) = (180 °) Means shedding. In this case, only by passing the electric current, the induction electric field E can turn right and left, and it does not seem to satisfy the first content of the necessary sufficient condition. However, if a magnetic field satisfying the necessary sufficient conditions of the present invention is applied, the former spontaneously turns right by the Larmor motion, and as a result, the induced electric field E also turns right. Therefore, the division number of the high frequency induction antenna according to the present invention may be considered as an integer n satisfying n ≧ 2 as described above.

(Example 10)

As described above, when the dividing number n of the high frequency induction antenna is n = 2, the induction electric field E formed by the high frequency induction antenna is applied by applying a magnetic field B that satisfies the second content of the necessary sufficient condition. ) Turns right with respect to the direction of the line of magnetic force. In this embodiment, two high frequency induction antenna elements are supplied with high frequency in which the λ / 2 phase is shifted. As a tenth embodiment, the basic structure of this embodiment is shown in FIG. In the configuration of Fig. 11, the feed end A and the ground end B of the antenna element 7-1 and the feed end A and the ground end B of the antenna element 7-2 are ABAB in the circumferential direction. The two outputs of the transmitter 54 are configured to be point symmetrically arranged at the top of the high frequency induction antenna element 7-1 through one of the two outputs of the transmitter 54 via a high frequency power source 51-1 and a matching unit 52-1. It is connected to the feed point 53-1 of the front end A, and the other is the high frequency induction via the lambda / 2 delay means 6-3, the high frequency power supply 51-2, and the matching unit 52-2. It is connected to the feed point 53-2 of the feed end A of the antenna element 7-2.

Thus, as shown in Fig. 11, the direction of the current of each high frequency induction antenna element is the direction indicated by arrows in I ₁ and I ₂ . By the way, since the current of which the phase was reversed ((lambda / 2/2 phase shifted)) flows to the elements 7-1 and 7-2 of each high frequency induction antenna, as a result, each high frequency induction antenna element 7-1 and 7 The high frequency current flowing through -2) becomes either up or down in each half cycle of the phase with respect to the drawing. Therefore, the induction electric field E forming FIG. 11 has two peaks similar to FIG. Only by this, the electron driven by the induction electric field E becomes possible to turn rightward and leftward. However, if this is applied to the magnetic field B (magnetic field of the magnetic force line from the surface surface to the rear surface) satisfying the necessary sufficient conditions, the electrons in the right direction resonantly receive the high frequency energy by the ECR phenomenon, resulting in high efficiency. However, the ionization efficiency is poor because electrons in the left direction cannot receive high frequency energy resonancely. As a result, the plasma is generated mainly by electrons in the right direction, and electrons accelerated to high speeds by receiving energy of high frequency efficiently remain. At this time, the current component flowing in the plasma is mainly composed of the low-speed electrons in the left direction and the high-speed electrons in the right direction, but of course, the current by the electrons in the right-direction that has reached the high speed becomes dominant. As can be seen in (1) and (2), the induced electric field E rotates to the right. This is the same as that of a conventional ECR plasma source using μ waves, UHF, or VHF, especially when an ECR discharge occurs without rotating the electric field in a specific direction.

(Example 11)

With respect to Fig. 11, if the effects of Fig. 6 (or Figs. 7, 10) are added, the ECR phenomenon can be generated with a simple configuration as in Fig. 12, which is the eleventh embodiment. In Fig. 12, the in-phase high frequency is supplied to each of the high frequency induction antenna elements without supplying the high frequency inverted phase, but the current is made equal by the feed end A and the ground end B of each high frequency induction antenna element. Since the direction of is reversed, the same effect as in FIG. 11 can be obtained. However, when the split number n of the high frequency induction antenna is n = 2, the current flowing through the two high frequency induction antenna elements may be zero at the same time. There is a moment. When the division number n of the high frequency induction antenna is n ≧ 3, as is clear from the same drawing as in FIG. 3 in each case, since current flows in at least two high frequency induction antenna elements, the induction electric field ( There is no moment when E) becomes E = 0.

It is shown that it consists of at least three linear conductors radially arranged from the center of the antenna at equal intervals from each other, and each of the linear conductors has one end grounded and the other end connected to an RF high-frequency power supply (Example For example, refer patent document 6). In this patent document 6 (c) and (e), (a) the antenna is introduce | transduced in a vacuum, (b) Moreover, the antenna is comprised from the linear conductor, (c) Moreover, the said linear conductor Is coated with insulation, and (d) the structure which applies a magnetic field is disclosed. These configurations are similar to the configuration of n = 2 in FIG. 12 of the present invention. The purpose of the configuration of Patent Document 6 is to stably input a large power to an antenna introduced into a vacuum to generate a high-density plasma, control its diffusion by a magnetic field, and obtain a uniform distribution. However, this configuration has a fatal defect as compared with the present patent. The basic cause is that the antenna is introduced into the vacuum. As described in this document, when a conductor antenna is introduced in a vacuum, it is difficult to generate a stable plasma by abnormal discharge or the like. This is a fact described also in nonpatent literature 3. For this reason, in invention of patent document 6, in order to insulate and coat an antenna from plasma stably, it is set as a linear conductor. However, the antenna not only inductively couples to the plasma but also performs capacitive coupling. That is, the antenna conductor and the plasma are connected by the capacitance of the insulating coating, the self-bias voltage by the high frequency voltage is generated on the plasma side surface of the insulating coating, and the insulating coating surface is always sputtered by the ions of the plasma. This causes a problem. First, the insulating coating is sputtered, so that the semiconductor wafer subjected to the plasma treatment is contaminated with the raw material of the insulating coating, or the insulating coating becomes foreign matter by the sputter and rises on the semiconductor wafer, thereby preventing normal plasma processing. The next problem is that the insulating coating becomes thinner with time, and the capacitive coupling between the antenna conductor and the plasma becomes stronger as the capacitance of the insulating coating increases. By this, first, the characteristics of the plasma generated by the capacitive coupling change with time, so that plasmas of constant characteristics cannot be generated. In other words, a change in the plasma characteristics over time occurs. In addition, as the insulating coating becomes thinner and the capacitive coupling becomes stronger, higher self bias voltage is generated, the insulating coating is accelerated to be consumed, and foreign matter generation and contamination also increase rapidly. Finally, the weakest insulation coating is torn, and the antenna conductor directly contacts the plasma, causing abnormal discharge, and the plasma treatment cannot continue. Naturally, the lifetime of the antenna is finite. That is, the structure of invention of patent document 6 is not suitable for industrial use. Even if it starts to be used, the characteristics deteriorate and become unusable during use, and the antennas need to be replaced as consumables, resulting in a device that takes time and cost. On the other hand, the structure of this patent is in the air | atmosphere side of the insulator cover 12, and the life is semi-permanent, and it does not take time and cost to replace it as a consumable. In addition, as shown in FIG. 1, there is a Faraday shield between the antenna and the plasma, and capacitive coupling between the antenna and the plasma can be blocked. Therefore, the insulator cover 12 is sputtered with ions, so that there is no contamination or foreign matter on the semiconductor wafer, and the insulator cover 12 is thinned by the sputter so that it cannot be used. The difference between the invention of the present invention and Patent Document 6 is that neither the invention of Patent Document 6 is intended to produce a rotating induction electric field nor to generate an ECR by the rotating induction electric field and magnetic field.

In FIG. 1 (FIG. 2), the high frequency induction antenna elements 7-1, 7-2, 7-3, and 7-4 divided into four are arranged on one circumference. This configuration of " one columnar shape " is not an essential configuration for realizing the first content of the necessary sufficient condition. For example, considering the two circumferences of large and small, and even if a high frequency induction antenna divided into an inner circumference and an outer circumference of the plate-shaped insulator 12 or an upper and lower quadrant is arranged, the first content of the necessary sufficient condition can be realized. have. That is, if the first content of the necessary sufficient condition can be realized, the number of circumferences and their arrangement can be freely configured. As in the case of the flat vacuum container cover 12, the vacuum container cover 12 made of an insulator has a high frequency induction antenna in the case of a trapezoidal rotating body shape or a hollow hemisphere, that is, a dome shape or a cylindrical shape having a bottom. It can also arrange | position on an outer periphery, and it can also arrange | position at an angle or obliquely.

The following aspect of the invention is in the form of providing a plurality of sets of high frequency induction antennas comprising a plurality of high frequency induction antenna elements. Here, the number of sets of antennas composed of a plurality of high frequency induction antenna elements forming the rotating induction electric field E is set to m. In the case of the present invention, m can be constructed as long as it is a natural number. In other words, it is possible not only to consider two circumferences but also to arrange the divided antennas on three or more circumferences. 1, 2, 6-12, and 14-16 are the cases of m = 1. How many m should be chosen according to the purpose. In industrial applications, the number of m must be determined by how much area of plasma is required, how much area to be processed, or how uniformity of plasma is required. There is a decisive difference between the case where m is 1 and the case of 2 or more. As described later, when m is 2, compared to the case where m is 1, the tuning knob increases by one to control the generation distribution of plasma by controlling the amount of current flowing through each set of antennas. to be. When m is three or more, it only becomes complicated, and the case of m = 2 is demonstrated here.

(Example 12)

A twelfth embodiment will be described with reference to FIG. FIG. 19 shows a case where the configuration (m = 1) of FIG. 2 or FIG. 8 is expanded to m = 2 (plural sets). Drawing the high frequency power supply, matching device, current delay circuit, feed line, etc., makes the drawing complicated, so only the feed end A (arrow) and ground end B for each high frequency induction antenna element are used here. FIG. 19 shows antenna elements 7'-1, 7'-2, which are paired inside each of the high frequency induction antenna elements 7-1, 7-2, 7-3, 7-4 of FIG. 7'-3, 7'-4) are installed. Then, the high frequency induction antenna elements 7-1, 7-2, 7-3, and 7-4 are replaced with the outer antenna 7, and the high frequency induction antenna elements 7 '-1, 7'-2, 7 '-3. , 7'-4) is called the inner antenna 7 '. In order to generate a highly uniform plasma, these outer antenna 7 and inner antenna 7 'are comprised so that it may become concentric circles. In this configuration, for example, the phase in the circumferential direction of the feed end A and the ground end B of the high frequency induction antenna element 7-1 and the antenna element 7'-1 corresponding thereto, for example. The angles are in agreement. In this case, as shown on the right side of FIG. 19, in-phase current flows as I ₁ , I ₁ ′, and I ₂ , I ₂ ′, I ₃ , I ₃ ′, I ₄ , and I ₄ ′ are respectively λ / 4. The phases are shifted gradually. In this case, the sum of the induced electric fields (induction magnetic fields) generated by the currents I ₁ and I ₁ ′ is the highest, and the efficiency of transporting power from the antenna to the plasma is maximum. In the generation of plasma, the inside of the inner antenna 7 '(which becomes circular) is mainly the inner antenna 7', and the periphery of the outer antenna 7 is rounded the outer antenna ( 7) will be in charge. Therefore, the distribution control of the plasma includes the absolute value of current | I ₁ | (= | I ₂ | = | I ₃ | = | I ₄ |) and | I ₁ '| (= | I ₂ ' | = | I ₃ This can be achieved by changing the ratio of '| = | I ₄ ' |). This is a tuning knob not obtained in the case of m = 1. Current ratio _{| I 1 '| / | I} 1 | _{is, 0 (| I 1' |} = 0, | I 1 | takes values of Co.) to infinity (from | I ₁ '| is assuming a value of Co. It is possible to freely set up to | I ₁ | = 0).

In the present invention, one high-frequency induction antenna set must be controlled in phase with a current in the set of high-frequency induction antennas, for example, as illustrated in FIG. This also applies to the inner antenna 7 '(high frequency induction antenna element 7') in the outer antenna 7 (high frequency induction antenna elements 7-1, 7-2, 7-3, 7-4) of FIG. -1, 7'-2, 7'-3, 7'-4)]. In the example described in Fig. 19, the phase difference between the current of the outer antenna 7 and the inner antenna 7 'is controlled to 0 degrees. However, in the configuration of FIG. 19, the phase difference between the inner antenna and the outer antenna does not necessarily need to be controlled to 0 degrees. The electric field is a physical quantity that can be added and subtracted, and the induction electric field produced by the outer antenna and the induction electric field produced by the inner antenna must be strong in one place and weak in each other. In Fig. 19, when the phase difference is 0 °, the electric field weakening with each other becomes minimum and the electric field weakening with each other becomes maximum. Therefore, the transportation efficiency of power from the antenna to the plasma is maximum. Outside of 0 degrees, compared with the case of 0 degrees, the electric field weakening each other increases, and the electric field hardening each other only decreases. From the viewpoint of plasma distribution control, there is no necessity to minimize the electric field weakening each other and the electric field stronging each other. In order to make the description easy to understand, in FIG. 19, the phase difference between the currents of the inner antenna and the outer antenna is 0 °, but may be set to other than 0 °.

(Example 13)

A thirteenth embodiment will be described with reference to FIG. 20 is an embodiment in which the phase difference between the current of the outer antenna and the inner antenna is set to 45 degrees. In this case, since the number of the high frequency induction antenna elements (the number of antenna divisions) is n = 4, 45 ° is 2π / mn (radian). In FIG. 20, the inner antenna and the outer antenna are shifted by 45 ° in the circumferential direction so as to have the strongest electric field produced by the inner antenna 7 'and the outer antenna 7. This is, for example, the feed end A of the high frequency induction antenna element 7-1 of the outer antenna and the feed end A of the high frequency induction antenna element 7'-1 of the inner antenna in the circumferential direction. It means to rotate 45 °. In such a configuration, the phase difference of the current to be passed to each high frequency induction antenna element is 45 ° (λ / mn), as shown in the right side of FIG.

The structure of FIG. 20 has an advantage compared with the structure of FIG. For this reason, first, the disadvantage of the structure of FIG. 19 is demonstrated. Although the same applies to FIG. 2, the condition under which the induction electric field generated by the outer antenna 7 of FIG. 19 smoothly rotates is that one high frequency induction antenna element, for example, the length l of 7-1, is l ≦ λ. satisfies / n (when the outer antenna satisfies l &amp;le; lambda / n, since the inner antenna always satisfies l &amp;le; lambda / n, only the outer antenna will be described here). Here, in the case of l << lambda / n, it can be considered that the high frequency current I1A flowing through the feed end A of the antenna element 7-1 and the high frequency current I1B flowing through the ground end B are the same. I ₁ A = I ₁ B. However, when l is close to the length of lambda / n, the current distribution occurs in the high frequency induction antenna element due to the standing wave (wavelength?). This shape is shown in Fig. 26A. The impedance in the I ₁ direction (arrow direction) seen from the power supply terminal A is taken from the ground terminal B, while taking any finite impedance (L described later) of the antenna element 7-1. I ₁ The impedance in the direction is approximately 0Ω. Therefore, in the case shown it is significantly affected by standing waves, are usually A I ₁ <I ₁ B as shown in Fig. 26 (a). Naturally, the induced electric field strength E immediately under the feed end A, that is, the density of the plasma, is lower than the plasma density just under the ground end B. FIG. That is, plasma distribution occurs in the circumferential direction of the outer antenna. The largest change in the plasma distribution is at the joint of the antenna element and the antenna element, for example, the ground end B of the antenna element 7-1 of FIG. 19 and the feed end of the antenna element 7-2. It is between (A).

There are two ways to make the plasma distribution in the circumferential direction more uniform. One, as shown in FIG. 20, does not directly ground the ground terminal B, but grounds through the capacitor C. FIG. By appropriately designing the value of the capacitor C, I ₁ A = I _l B can be realized. This shape is shown in Fig. 26 (b). If the inductance of the antenna element 7-1 is set to L, I ₁ A = I _l B means that the relationship of 1 / ωC = ωL / 2 between the capacitor C (capacity C) and L It is time to establish. As shown in Fig. 26B, at this time, the distribution of the current I ₁ takes the maximum value at the center of the antenna element 7-1, and the distribution of the voltage V ₁ is the antenna element 7. 0V at the center of -1). This is described in detail in Non-Patent Document 3 and Non-Patent Document 4.

Another method is to shift the circumferential position of the feed end A and the ground end B of the inner antenna relative to the circumferential position of the outer antenna feed end A and the ground end B. That is, the phase angle is attached. In Fig. 20, this phase angle is 45 degrees. With such a configuration, it is possible to disperse the darkness of the plasma into the chamber and to improve the uniformity due to the diffusion of the plasma. 20 is one embodiment which satisfies these two requirements simultaneously.

(Example 14)

A fourteenth embodiment will be described with reference to FIG. As described with reference to Fig. 20, when the plasma distribution occurs in the circumferential direction of the antenna under the influence of the standing wave, there is another antenna configuration that makes this plasma distribution even more uniform. This overlaps the antenna elements, which shows this embodiment in FIG. 21. In FIG. 21, half of the high frequency induction antenna element 7-1 overlaps the high frequency induction antenna element 7-4, and the other half overlaps the high frequency induction antenna element 7-2. In the portion where the high frequency induction antenna elements overlap, the induction electric field generated by the current flowing through the two high frequency induction antenna elements is added. That is, half of the high frequency induction antenna element 7-1 forms an induction electric field by currents I ₁ and I ₄ , and the other half forms an induction electric field by currents I ₁ and I ₂ . Therefore, this structure can form a rotating electric field in the state which made the induction electric field of the circumferential direction more smooth. 21 shows this structure for all antenna elements.

20 and 21 have described a method of forming a smoother electric field using the outer antenna 7 and the inner antenna 7 '. (1) a method of setting the installation phase angle in the circumferential direction of the outer and inner antennas, (2) grounding of the ground terminal (B) via a capacitor, and (3) a method of overlapping the antenna elements described here. Although described in other drawings, it is possible to carry out these methods simultaneously.

(Example 15)

A fifteenth embodiment will be described with reference to FIG. FIG. 22 shows an embodiment of the configuration in which the length l of the high frequency induction antenna element is the simplest n = 2, m = 2, where l &lt; λ / n, that is, I _l A = I _l B. . This configuration uses the configuration described in Fig. 12 for the inner antenna 7 'and the outer antenna 7, respectively. In this case, the currents I ₁ , I ₁ ′, I ₂ , and I ₂ ′ flowing through the high frequency induction antenna element can all be currents in phase. Therefore, a current can be supplied from one power source to the feed point A of the inner antenna and the feed point A of the outer antenna. In this case, it is preferable to insert the current regulator 55 for adjusting the amount of current supplied to the inner antenna and the outer antenna at the position shown in the figure. Of course, you may supply electric current to each of the inner antenna 7 'and the outer antenna 7 from each power supply.

As in the case of the flat vacuum container cover 12, the vacuum container cover 12 made of an insulator has a high frequency induction antenna in the case of a trapezoidal rotating body shape or a hollow hemisphere, that is, a dome shape or a cylindrical shape having a bottom. It can also arrange | position on an outer periphery, and it can also arrange | position at an angle or obliquely. As described in FIG. 13, the position of the antenna with respect to the vacuum container cover 12 is very important in controlling the generation distribution and the diffusion distribution of the plasma. In the same sense, it is important how the inner and outer antennas are arranged with respect to the vacuum vessel cover 12.

23 shows a variation of the arrangement of the inner antenna 7 'and the outer antenna 7 with respect to the vacuum vessel cover 12. Fig. 23A is an example in which the inner antenna 7 'and the outer antenna 7 are provided on the flat plate-shaped vacuum container cover 12. Figs. Compared with FIG. 13 (a), it is possible to produce a plasma distribution that is more centrally focused. Of course, if one current of the inner antenna 7 'or the outer antenna 7 is 0A, Figs. 23A and 13A are equivalent configurations. Since the flat vacuum container cover 12 has only one surface (upper surface), it becomes such a structure. FIG. 23B is a variation of the arrangement of the inner antenna 7 'and the outer antenna 7 with respect to the dome-shaped vacuum container cover 12. As shown in FIG. The outer and inner antennas are arranged on the curved surface of the dome, and the distribution control of plasma is enhanced. As shown in Fig. 23A, when one current of the inner antenna 7 'or the outer antenna 7 is 0A, Figs. 23B and 13B are equivalent configurations.

23 (c) and 23 (d) are variations of the arrangement of the inner antenna 7 ′ and the outer antenna 7 with respect to the trapezoidal rotary vacuum container cover 12. Since the trapezoidal rotary vacuum container cover 12 has an inclined side surface and a flat upper surface, deformations as shown in Figs. 23 (c) and 23 (d) are possible. In Fig. 23C, the outer antenna 7 is disposed on the inclined side surface, and the inner antenna 7 'is disposed on the upper surface. In Fig. 23 (d), the inner antenna 7 'and the outer antenna 7 are disposed on the inclined side surface. 23 (c) and 23 (d) have an equivalent configuration to FIG. 13 (d) when a current of one of the inner antenna 7 'or the outer antenna 7 is 0A. 23 (d) can control the plasma distribution of the central portion more than that shown in FIG. 23 (c). Although not shown, it is also possible to arrange both antennas on the upper surface.

23 (e), 23 (f) and 23 (g) are variations of the arrangement of the inner antenna 7 'and the outer antenna 7 with respect to the bottomed cylindrical vacuum container cover 12. FIG. Since the bottomed cylindrical vacuum container cover 12 has a vertical side surface and a wide flat top surface, deformations as shown in Figs. 23 (e), 23 (f) and 23 (g) are possible. In Fig. 23E, the inner antenna 7 'and the outer antenna 7 are disposed on the side surface. In Fig. 23 (f), the outer antenna 7 is disposed on the side surface, and the inner antenna 7 'is disposed on the upper surface. In Figs. 23E and 23F, when the current of one of the inner antenna 7 'or the outer antenna 7 is 0A, the configuration is equivalent to that of Fig. 13E.

In FIG. 23G, the outer antenna 7 and the inner antenna 7 'are disposed on the upper surface. Fig. 23G shows the same configuration as that of Fig. 13A when the current of one of the inner antenna 7 'or the outer antenna 7 is 0A. However, FIG. 13 (a) shows that the side wall is a vacuum vessel (grounded) of the conductor, whereas in FIG. 23 (g), the side wall is a vacuum vessel lid 12 (floating electrically) made of an insulator. The distribution of induced electric fields is different and is not the same. The type of vacuum chamber lid 12 described above and the number and arrangement of high frequency induction antennas for it must be determined by which process plasma is generated.

In Fig. 1 (Fig. 2), circular arc-shaped high frequency induction antenna elements 7-1, 7-2, 7-3, and 7-4 are arranged on one circumference. This " circumferential arrangement " is also not an essential configuration for realizing the first content of the necessary sufficient condition. For example, even if it arrange | positions in rectangle using four linear high frequency induction antenna elements, the 1st content of the said necessary sufficient condition can be implement | achieved. Naturally, n high frequency induction antennas 7 of n-angles (if n = 2, the distance should be opposed to each other) may be configured using n linear high frequency induction antenna elements satisfying n ≧ 2. .

(Example 16)

A sixteenth embodiment of the present invention will be described with reference to FIG. In this embodiment, the high frequency induction antenna elements 7-1 to 7-4 and 7'-1 to 7'-4 shown in Fig. 19 are linear, and each set of outer antennas 7, In this embodiment, the inner antenna 7 'has a rectangular shape. 24 shows the configuration of the high frequency induction antenna when the antenna division number n = 4 and the antenna set number m = 2. FIG. The outer antenna 7 constitutes a rectangle (rectangular) because the high frequency induction antenna elements 7-1 to 7-4 arranged in a straight line and divided are arranged, and the number of antenna divisions is four. The inner antenna 7 'is also configured in the same way. This may be considered that the antenna configuration shown in FIG. 19 is rectangular. However, in the square, the induction electric field of the square rotates. This may be understood that the shape of the full length made into a circle in FIG. 3 becomes a rectangle. However, there is no such thing as a perfectly rectangular full-length distribution. This is because the electric field is always formed with a differential surface. However, the configuration in FIG. 24 has the effect that the outer electrode corrects the collapse in the quadrangle of the induction field distribution produced by the inner antenna. In FIG. 24, the phase difference between the currents of the inner antenna and the outer antenna is 0 °, but can be set to other than 0 ° as in FIG. 19.

(Example 17)

25, a seventeenth embodiment of the present invention will be described. This embodiment is an embodiment related to the configuration of the high frequency induction antenna configured to further rotate the induction electric field in a rectangular shape than in FIG. 24. This configuration extends the way of thinking described in FIG. 20 to n-squares, and the phase of the current flowing through each antenna element is also the same as in FIG. 20. That is, the outer side (the 1st) antenna 7 which consists of high frequency induction antenna elements 7-1-7-4, and the inside (2nd) which consists of high frequency induction antenna elements 7'-1-7'-4. The right-side induction electric field is formed by arranging the antenna 7 'at a 45 ° shift. The first antenna 7 arranges linear high frequency induction antenna elements 7-1 to 7-4 in a rectangular shape. Each of the high frequency induction antenna elements 7-1 to 7-4 is supplied with a current having a λ / 4 phase shifted from the power supply terminal A, and the ground terminal B is grounded. Similarly, the 2nd antenna 7 'has arrange | positioned the linear high frequency induction antenna elements 7'-1-7'-4 in a rectangle. Each of the high frequency induction antenna elements 7'-1 to 7'-4 is supplied with a current having a λ / 4 phase shifted from the power supply terminal A, and the ground terminal B is grounded. Corresponding high frequency induction antenna elements 7-1, 7'-1 are supplied with currents out of λ / 8 phase and other high frequency induction antenna elements 7-2, 7'-2, 7-3, 7 'are supplied. -3, 7-4, 7'-4) is similarly supplied with a current of λ / 8 out of phase. The 1st antenna 7 and the 2nd antenna 7 'are overlapped up and down, and are arrange | positioned at 45 degree shifts. According to this, the currents I ₁ , I ₁ ′, I ₂ , I ₂ ′, I ₃ , I ₃ ′, I ₄ , I ₄ ′ in which adjacent λ / 8 phases are respectively shifted to adjacent high frequency induction antenna elements. Flows, the right turn induction electric field can be formed in a shape closer to the square than in FIG.

As mentioned above, although the structure of the high frequency induction antenna of Example 5 thru | or 17 is all different in structure, as shown in FIG. 5, the same induction electric field distribution E which rotates right with respect to a magnetic line direction is formed. In all, it is a deformation | transformation which satisfy | fills the 1st content of the above-mentioned necessary enough conditions. Moreover, it can apply also to any of the shape of the vacuum container cover 12 of the said Example 2-Example 4.

2, 13, 18 and 23 will be summarized again. In the present invention, a plurality of plasma distribution control functions such as the number of divisions n of the antenna, the shape of the vacuum chamber cover 12, the number of sets of the high frequency induction antenna m, and the arrangement of the antennas with respect to the vacuum container cover 12 are provided. Have However, these can be realized as an apparatus configuration even in a conventional ICP source. Regarding the plasma distribution control, the most important thing in the present invention is the introduction of an electrically externally controllable tuning knob called the ECR plane in addition to the flexible plasma controllability in terms of their apparatus configuration. Creating a rotating induction field from an ICP source and enabling ECR discharge not only enables excellent plasma ignition, but also enables plasma generation at lower gas pressures, and also provides excellent plasma control of the ECR plane. Means to give controllability. There is no conventional example of a plasma source having such flexible plasma controllability.

In addition, according to the present invention, since a high-frequency induction magnetic field is always formed in the processing chamber, plasma ignition performance is improved and a high density plasma is obtained. Moreover, according to this invention, the length of a high frequency induction antenna can be controlled, it can respond to the requirement of any large diameter, and can improve the plasma uniformity of a circumferential direction.

In FIG. 1, the Faraday shield 9 is shown. Since the Faraday shield originally has a function of suppressing capacitive coupling between an antenna emitting high frequency radiation and plasma, it cannot be used in a capacitively coupled ECR plasma source (for example, Patent Document 5). In the present invention, a Faraday shield can be used similarly to a normal ICP source. However, "Faraday Shield" is not an essential configuration in the present invention. This is because it does not have to be sufficient condition. However, similar to a normal ICP source, Faraday seals are useful for industrial use. This is because Faraday seal has little effect on the induction magnetic field H (that is, the induction electric field E) emitted from the antenna, and has a function of blocking capacitive coupling between the antenna and the plasma. To make this isolation more complete, the Faraday shield must be grounded. Usually, in the ICP source, blocking the capacitive coupling worsens the ignition of the plasma. However, in the present invention, since high-efficiency ECR heating by induction electric field E generated by inductive coupling is used, there is no instant when the induction electric field E becomes E = 0 in the configuration of n≥3. Therefore, even if the capacitive coupling is completely blocked, good ignition is obtained. This is a great feature of the present invention. However, it is also possible to connect an electric circuit to this Faraday shield for various reasons, and to control the high frequency voltage which generate | occur | produces in a Faraday shield above O or 0 or more.

One of the advantages of applying a high frequency potential to the Faraday shield is that a self bias can be applied to the inner surface exposed to the plasma of the vacuum vessel lid 12. If a large amount of the reaction product is attached to the inner surface of the vacuum container cover 12, when the attached reaction product is peeled off, the reaction product falls onto the object W and causes foreign substances. In addition, when a conductive reaction product adheres to this surface, the strength and distribution of the high frequency induction field formed by the high frequency induction antenna may change with time, thereby making it impossible to continue processing the object. As described above, the attachment of the reaction product to the inner surface of the vacuum container lid 12 causes many obstacles in processing the product. However, if the reaction product is controlled so as not to attach the reaction product by applying a self bias to the surface, Obstacles can be avoided, and stable product processing can be continued for a long time, and an apparatus excellent in mass production stability is obtained. At this time, it is important to apply a uniform self bias voltage to the inner surface of the vacuum container lid 12, that is, to apply a uniform high frequency voltage over the entire Faraday shield.

Conventionally, several techniques for applying a high frequency voltage to a Faraday shield have been developed. First, when these conventional methods are used, the present invention is shown to cause disadvantages. There is patent document 7, or patent document 8 as one of this developed technology. A feature of these methods is that the voltage generated using the plasma generation power supply is applied to the Faraday shield. Naturally, the frequency of the high frequency voltage generated in the Faraday shield is the frequency of the high frequency power supply for plasma generation. If this method is used in the present invention, two disadvantages arise. The first disadvantage is that it is difficult to achieve phase control of n currents for n antenna elements and to draw a voltage with a single phase from the power supply used for it. Extreme limitations are placed on either the current flowing to the antenna element or the voltage applied to the Faraday shield, which results in no practical benefit. A second disadvantage is that if the frequency of the high frequency power supply for plasma generation is, for example, VHF, a nonuniform voltage distribution is generated throughout the Faraday shield by the wavelength shortening effect, as shown in the non-patent document 1. That is, it becomes impossible to apply a uniform self bias to the inner surface of the vacuum container cover 12.

In order to solve these disadvantages, the high frequency power supply for supplying the voltage to the Faraday shield must be a separate power supply from the high frequency power supply for generating plasma. In addition, the frequency of the high frequency power supply applying voltage to the Faraday shield needs to be a frequency (for example, 30 MHz or less) that causes a uniform voltage distribution over the entire Faraday shield.

(Example 18)

Patent document 9 is a method of applying a high frequency voltage to a Faraday shield than other high frequency power sources. The feature of this method is that the phase controlled high frequency voltage is applied to the object W and the Faraday shield, respectively, using the same frequency as the high frequency bias applied to the object W. As shown in the present invention, the Faraday shield and the object W are capacitively coupled to the plasma, respectively, and have the same electrode configuration as that of the parallel plate capacitively coupled plasma source. Applying the high frequency voltage of the same frequency which controlled the voltage phase to this system has the effect of preventing abnormal diffusion of a plasma, etc., and is a very excellent method. However, even if this configuration is used in the present invention, the above second disadvantage cannot be avoided. This is because the Faraday shield is capacitively coupled to the high frequency induction antenna, so that even with this configuration, an uneven voltage distribution having the same frequency as the high frequency power supply for plasma generation cannot be generated in the Faraday shield.

A method of applying a high frequency voltage to a Faraday shield which solves the disadvantages described above is shown in FIG. 27 as an eighteenth embodiment. The plasma generation method in FIG. 27 is the same as that in FIG. 16, but can also be applied to FIGS. 1, 14, and 15 in the same manner. In the configuration of FIG. 27, the output of the transmitter 43 is input to the phase controller 44. The phase controller 44 finally monitors the phases of the high frequency voltages applied to the object W and the Faraday shield 9 using phase detectors 47-1 and 47-2, and controls them to the required phases. The high frequency signal is output to the bias high frequency power supply 41 and the Faraday shield high frequency power supply 45. The high frequency power amplified by the two high frequency power sources 41 and 45 is applied to the workpiece W and the Faraday shield 9 via the matching units 42 and 46, respectively.

At this time, it is necessary to use the filter 49 so as not to generate an uneven voltage distribution having the same frequency as the high frequency for plasma generation generated in the Faraday shield 9. This filter 49 must have at least a finite (nonzero) impedance for the high frequency output from the transmitter 43 and a small impedance that can be regarded as zero for the high frequency for plasma generation. That is, it is necessary to be a high pass filter or a notch filter as long as the impedance can be regarded as zero with respect to the high frequency for plasma generation. However, as shown in FIG. 27, only one filter 49 needs to be inserted on the feed line to the Faraday shield 9. This is important. Because the voltage having the same frequency as the plasma generating high frequency has a distribution on the Faraday shield 9, even if the high frequency voltage at the place where the filter is inserted can be shorted to ground (the voltage becomes 0V). This is because the other part of the Faraday shield 9 is not able to short-circuit the high frequency voltage to ground. Therefore, this filter 49 needs to be inserted into the plural parts in the Faraday shield 9.

28 shows a state in which a plurality of filters 49 are inserted into different portions in the Faraday shield 9. First, the Faraday shield 9 is a component of a conductor prepared according to the type of the vacuum container cover 12 of FIG. 27. On the surface facing the high frequency induction antenna 7 (side surface in FIG. 27), a plurality of slits are inserted at right angles to the direction of the high frequency induction antenna. The Faraday shield 9 blocks the capacitive coupling between the high frequency induction antenna and the plasma by being a conductor, and the plurality of slits allow the circulating current to flow in the direction of the high frequency induction antenna to the Faraday shield 9. To inductively couple the high frequency induction antenna to the plasma. It is the basic principle of the well-known Faraday shield. FIG. 28 shows a state in which the filter 49 is inserted into five parts [49-1, 49-2, 49-3, 49-4 (not shown), 49-5] in total. The condition that the insertion portion of the filter 49 must satisfy is that all the creepage distances fd along the Faraday shield 9 between the filters are sufficiently shorter than the wavelength lambda of the plasma generation frequency, that is, fd &lt; Need to be. The number of insertions of the filter 49 is not limited to five parts, and the number which is sufficient to satisfy fd &lt;

(Example 19)

In the method shown in FIG. 27, the some filter 49 must be connected to the Faraday shield 9, and it becomes a complicated apparatus structure, but FIG. 29 shows another Example (19th Example) which avoids this. In comparison with the example shown in FIG. 27, in the example shown in FIG. 29, the Faraday shield 9 is divided into an outer Faraday shield 9-1 and an inner Faraday shield 9-2. In other words, it is a double Faraday shield. The outer Faraday shield 9-1 faces the high frequency induction antenna 7, and grounds it to block capacitive coupling of the high frequency induction antenna 7 and plasma. The Faraday shield 9-1 should be grounded for the entire circumference of the Faraday shield 9-1 so as not to generate a high frequency voltage in the Faraday shield 9-1. Of course, the Faraday shield 9-1 also includes the same slit as in Fig. 28, and does not interfere with the inductive coupling of the high frequency induction antenna 7 and the plasma. By the outer Faraday shield 9-1, the inner Faraday shield 9-2 does not generate a high frequency voltage due to the high frequency for plasma generation. Therefore, the action of the inner Faraday shield 9-2 causes the high frequency induction antenna 7 and the plasma to be inductively coupled by the same slit as shown in FIG. 28, and the high frequency power supply 45 for the phase controlled Faraday shield is output. The high frequency voltage is applied to the vacuum container cover 12. As described above, even in the inductively coupled type ECR plasma source, it is possible to apply a uniform high frequency voltage to the vacuum container cover 12 via the Faraday shield 9.

In FIG. 1, the upper coil 81, the lower coil 82, and the yoke 83 which are two electromagnets are shown as a structure requirement of a magnetic field. However, what is essential in this invention is only realizing the magnetic field which satisfy | fills the said necessary sufficient conditions, neither yoke 83 nor two electromagnets are essential structures. For example, even if it is only the upper coil 81 (or the lower coil 82), what is necessary is just to satisfy | fill the said sufficient requirements. The magnetic field generating means may be an electromagnet or a fixed magnet, or may be a combination of an electromagnet and a fixed magnet.

In addition to the components described so far, Fig. 1 shows a gas inlet 3, a gate valve 21, a wafer bias (bias power supply 41 and matching device 42). Since it is irrelevant to this, it is not an essential structure in this invention. The gas inlet is necessary to generate a plasma, but the position may be at the wall surface of the vacuum vessel 11 or at the electrode 14 on which the wafer W is mounted. Moreover, the gas blowing method may also be sprayed in planar shape, or may be ejected in point shape. The gate valve 21 has only shown the structure for the purpose of conveying a wafer in industrial use. In addition, the wafer bias (bias power supply 41 and matching device 42) is not necessarily required in the industrial use of the plasma processing apparatus, and is not essential in the industrial use of the present invention.

In the present invention, the induction electric field E formed by the high frequency induction antenna rotates right with respect to the direction of the magnetic field lines of the magnetic field. The shape of the rotating surface is determined by the structure of the high frequency induction antenna, and is circular or elliptical. Thus, the central axis of rotation necessarily exists. In industrial applications, such a central axis exists in addition to a magnetic field B, an object to be processed (a circular wafer or a rectangular glass base, etc.), a vacuum container, a gas jet port, an electrode or a vacuum on which an object to be processed is mounted. And an exhaust port. In the present invention, these central axes do not need to coincide at all, and are not essential configuration requirements. This is because it is not related to the necessary sufficient condition. However, when uniformity (etching rate, deposit, shape, etc.) of the treatment of the surface of the workpiece is a problem, it is preferable that these central axes coincide.

1: vacuum processing chamber 11: vacuum container
12: vacuum container cover (insulation material) 13: vacuum exhaust means
14 electrode (sample bed) 2 conveying system
21: gate valve 3: gas inlet
41: high frequency power supply for bias 42: matcher for bias
51: high frequency power supply for plasma generation 52: matching device for plasma generation
53: feed point 54: transmitter
55 current regulator 6: delay means
7: high frequency induction antenna
7-1 to 7-4: High frequency induction antenna element
78: feed line 79: ground line
81: box coil 82: fault coil
83: York 9: Faraday Seal
A: Feeding stage B: Grounding stage
C: Capacitor W: Object to be processed (semiconductor wafer)

Claims (2)

A vacuum container constituting a vacuum processing chamber capable of accommodating a sample, a gas inlet for introducing a processing gas into the vacuum processing chamber, a high frequency induction antenna forming an induction electric field in the vacuum processing chamber, and a magnetic field in the vacuum processing chamber. A magnetic field coil, a high frequency power supply for plasma generation for supplying a high frequency current to the high frequency induction antenna, a power supply for supplying electric power to the magnetic field coil, and supplying a high frequency current from the high frequency power source to the high frequency induction antenna, and vacuum A plasma processing apparatus for plasma-processing a sample by converting a gas supplied into a processing chamber into a plasma,
The vacuum processing chamber includes a vacuum processing chamber cover made of a dielectric that is hermetically fixed on an upper portion of the vacuum chamber, and a Faraday shield disposed between the high frequency induction antenna and the vacuum processing chamber cover,
The high frequency induction antenna is divided into n (integers of n ≧ 2) high frequency induction antenna elements, and each of the divided high frequency induction antenna elements is arranged in a row, and a set of each high frequency induction antenna elements arranged in a column A plurality of sets are provided, and a high frequency current delayed by λ (wavelength of a high frequency power supply) / n in order to each of the high frequency induction antenna elements of each set of high frequency induction antennas is sequentially delayed in a predetermined direction and flows into the magnetic field coil. A rotation induction field E that rotates in the right direction with respect to the direction of the magnetic force line of the magnetic field B formed by supplying the power is formed by the high frequency current, and the rotation frequency and the magnetic field B of the rotation induction field E Plasma processing apparatus characterized in that it is configured to match the electron cyclotron frequency by. The method of claim 1,
An electrode on which the sample is mounted, a high frequency power supply for bias applying high frequency power to the electrode, a high frequency power supply for faraday shield applying high frequency power to the faraday shield, a high frequency power supply for bias and the high frequency power for the faraday shield And a phase controller for controlling a phase difference between the bias high frequency power supply and the Faraday shielded high frequency power supply.

Images