JPH08225967A - Magnetic neutral line discharge plasma treatment device - Google Patents

Abstract

PURPOSE: To electrically adjust the characteristic and the generating position of plasma arbitrarily by generating the plasma with a magnetic neutral line discharge in the plasma treatment device. CONSTITUTION: The electric discharge is generated with a high frequency or DC electric field generating means 10 along the magnetic neutral line 9 generated with an AC magnetic field generating means composed of electromagnetic coils 4-6 or a linear current rod and consisting of positions of continued zero- magnetic field in the space to generate the plasma.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic neutral line discharge plasma processing apparatus in which an object to be processed such as a substrate and a target is subjected to processing such as coating, etching, sputtering and CVD using plasma. Is.

[0002]

2. Description of the Related Art Conventionally, for example, in plasma etching, a chemically active gas is brought into a plasma state by discharge under a low pressure, and active species such as ions and neutral radicals generated thereby react with a material to be etched. The reaction product is desorbed into the gas phase, and various types are known. As an example, an etching gas is introduced into a vacuum container, and a magnetron discharge between a DC electric field and a magnetic field is used. An electron cyclotron resonance (ECR) is caused by an interaction between a microwave (2.45 GHz) and a magnetic field to generate an electron. Using an ECR plasma source that produces a high-ionization plasma under low pressure by accelerating the
There is one that applies a high-frequency electric field of 6 MHz to make it into a plasma state. There are also various types of plasma CVD related to the formation of a film by the formation of a high-energy plasma state by RF plasma excitation, which decomposes the chemical bonds of the reaction gas and the reaction between activated particles. Have been proposed.

[0003]

Conventionally, in such a plasma utilizing apparatus, in most cases, spatial nonuniformity of density and temperature and nonuniformity in velocity space due to acceleration due to electric field exist. Therefore, when these are used to perform the intended action on the substrate, non-uniformity of the effect is likely to occur, especially not only charged particles but also radicals (chemically active species)
However, in a process such as etching, in which the existence of the above-mentioned phenomenon must be taken into consideration, the desired distribution, for example, uniformity can be ensured extremely empirically. In addition, in sputtering, the structure of the electromagnet or permanent magnet was devised to improve the efficiency of use of the target, or the position of plasma was changed by mechanically displacing the electromagnet or permanent magnet provided on the back side of the cathode to change the position of the plasma. However, in any case, there is a problem in that the use efficiency of the cathode is difficult to improve, and the apparatus itself becomes complicated or bulky.

In order to solve such a problem, the present inventor previously disclosed in Japanese Patent Application No. 6-52418 a magnetic neutral wire in a vacuum chamber in which plasma is used to process an object to be processed. Discharge plasma provided with a magnetic field generating means for generating a discharge plasma in the magnetic neutral line by applying an electric field along the magnetic neutral line formed in the vacuum chamber by the magnetic field generating means. A processing device was proposed. According to this proposal, the position and size of the magnetic neutral line formed by only controlling the exciting current in the magnetic field generating means can be arbitrarily adjusted, and therefore, the plasma generating position can be easily displaced, and as a result, It became possible to obtain a uniform effect in the process treatment. Also, since plasma is formed by magnetic neutral line discharge, charged particles of electrons or ions that are accelerated in the direction perpendicular to the magnetic field by the electric field will orbit due to the presence of the magnetic field if the magnetic neutral line deviates even slightly. Since it is bent, it is less likely that only high-speed electrons will be accelerated by the electric field as compared to the case of being parallel to the magnetic field, so the velocity distribution of the plasma is less likely to deviate from the Maxwell distribution, and therefore the energy absorption of the electric field is better , The effect that damage due to accelerated particles is hard to occur is now obtained.

However, in the previously proposed apparatus, the vacuum chamber and peripheral devices tend to be easily magnetized by the magnetic field generated by the magnetic field generating means depending on the mode of operation (for example, long-time operation of the apparatus). Was found.

An object of the present invention is to provide a magnetic neutral line discharge plasma processing apparatus which can solve the problems of the prior art and avoid the problems of the previously proposed magnetic neutral line discharge plasma apparatus.

[0007]

In order to achieve the above object, according to the present invention, in a discharge plasma processing apparatus for processing an object to be processed by utilizing plasma in a vacuum chamber, A magnetic field generated by the AC magnetic field generating means, which is excited by an AC current having a frequency and forms a magnetic neutral line which is a position where the magnetic field is zero continuously existing in the vacuum chamber. An electric field generating means for applying an electric field along the neutral line to generate discharge plasma in the magnetic neutral line is provided. In this case, the term "alternating current having a constant frequency" means an alternating current having a frequency of a preselected value including commercial frequencies such as 50 Hz and 60 Hz, depending on the application example of the device. The optimum frequency is selected. The alternating magnetic field generating means may be a coil whose surface is covered with an insulator. The AC magnetic field generating means is composed of at least two AC magnetic field generating coils coaxially arranged at intervals, and at least one annular magnetic neutral wire is formed between adjacent coils by passing an AC current through these coils. Can be done. At this time, the relative position of the generated annular magnetic neutral wire to the alternating magnetic field generating coil can be adjusted by controlling the magnitude of each alternating current flowing in each alternating magnetic field generating coil and the mutual phase difference. .
In addition to the above configuration, the present invention may be provided with control means for controlling the magnitude and phase of the alternating current supplied to the alternating magnetic field generating means. The control means may be arranged to control the frequency and / or the phase of the AC power supply supplied to the AC magnetic field generating means.

[0008]

In the magnetic neutral line discharge plasma processing apparatus of the present invention having the above-mentioned structure, the characteristics of the AC exciting current flowing through the coil constituting the magnetic field generating means or the spatial structure of the AC magnetic field generating means (size, By changing the frequency, phase difference, etc.), the position or shape (for example, the size of the ring) of the magnetic neutral line, that is, the zero magnetic field with respect to the substrate can be arbitrarily changed, and the position of the plasma formed in the ring shape can be changed. It can be moved arbitrarily, and since the AC magnetic field is used, the vacuum chamber and peripheral equipment are less likely to be magnetized even when the transport device is operated for a long time, and the device can be used without considering the effect of the residual magnetic field. Like Plasma is generated by introducing a gas into the vacuum chamber, preheating it and igniting it, and then applying an electric field along the ring-shaped magnetic neutral line formed by the electric field generating means, and diffuses to the surroundings. . Since it is an alternating magnetic field, the pulsation corresponding to the alternating current is seen in the diffusion state. When the discharge current flowing along the magnetic neutral line is small, the charged particles of electrons or ions accelerated in the direction perpendicular to the magnetic field by the electric field are orbited by the magnetic field existing in the perpendicular direction if they deviate even slightly from the magnetic neutral line. Since the electric field is bent, it is less likely that only high-speed electrons will be accelerated by the electric field as compared with the case of being parallel to the magnetic field. Therefore, even if the electric field is present, the plasma velocity distribution is less likely to deviate from the Maxwell distribution. This means that the electric field energy is well absorbed after the electric discharge. Therefore, damage due to high-speed acceleration particles is unlikely to occur.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a plasma processing apparatus according to an embodiment of the present invention, in which a vacuum chamber 1 is provided with a cylindrical plasma generating chamber 2 made of an insulating material and a substrate processing chamber 3. Three electromagnetic coils 4, 5 and 6 forming an AC magnetic field generating means are provided on the outer side of the cylindrical peripheral wall forming the cylindrical plasma generating chamber 2, and these electromagnetic coils are frequency / phase control devices. It is connected to a power source (not shown) via 7. For example the alternating current I _4, I ₆ of the same phase is flowed in two electromagnetic coils 4, 6 down by frequency and phase control apparatus 7, also in the middle of the electromagnetic coil 5 is AC current I ₅ of the antiphase Shed As a result, as shown by reference numeral 8 in the magnetic force diagram of FIG. 2, a continuous magnetic field zero position is formed inside the electromagnetic coil 5 at the intermediate level, and a ring-shaped magnetic neutral line 9 is formed. The position and size of the ring-shaped magnetic neutral wire 9 are the same as the alternating currents I ₄ and I ₆ flowing through the upper and lower electromagnetic coils 4 and ₆ and the alternating current I ₅ flowing through the intermediate electromagnetic coil 5. It can be appropriately set by changing the characteristics of. A high frequency coil 10 forming an electric field generating means is concentrically wound outside the cross section of the intermediate electromagnetic coil 5 to form a double coil, and a thin electric insulating layer is provided between the cross sections of both coils. By applying a high frequency induction electric field (for example, 13.56 MHz) along the ring-shaped magnetic neutral line 9 by the high frequency coil 10, a strong electric field can be generated along the magnetic neutral line at the position where the magnetic field is zero. . At this time, since the high frequency flows on the surface of the coil due to the skin effect, the high frequency coil has an intermediate coil cross-section skin structure, so that the interaction between the coils can be avoided and the control becomes easier. A gas introduction port 11 for plasma generation is provided at the top of the cylindrical plasma generation chamber 2, and a gas to be plasma is introduced from this gas introduction port 11. At this time, preheating and ignition means (not shown) may be provided, if necessary, in order to easily cause discharge. According to related empirical consideration, the discharge can be easily initiated by using ultraviolet light. The substrate processing chamber 3 located below the plasma generation chamber 2 is provided with a gas introduction port 12 and an exhaust port 13 for a chemical process such as etching, and they are connected to appropriate gas supply sources and exhaust pumps, respectively. Further, 14 is a substrate to be processed.

In the operation of the illustrated apparatus thus configured, the high frequency discharge plasma generated by the high frequency coil 10 in the magnetic neutral wire 9 formed in the plasma generation chamber 2 is
It is diffused to the surroundings and used for processing the substrate 14 in the substrate processing chamber 3. In this case, since a high frequency is used, plasma is always generated and springs in the magnetic neutral line. The alternating currents I ₄ and I ₆ flowing through the upper and lower two electromagnetic coils 4 and ₆ and the alternating current I ₅ flowing through the intermediate electromagnetic coil ₅
The diameter of the ring-shaped magnetic neutral wire 9 and the distance to the substrate 14 are changed by respectively controlling and, and uniform treatment on the surface of the substrate 14 becomes possible.

FIG. 3 shows another embodiment of the present invention. The AC magnetic field generating means for forming a magnetic neutral line consisting of continuous magnetic field zero positions is composed of two circular coils 15 and 16 of the same size, and an AC or DC power supply (not shown) is provided via a frequency / phase control device 17. It is connected to the. Double circular coil 15, 16
AC currents 180 ° out of phase with each other are applied to the coil, and by changing the ratio of the absolute values of these currents significantly, the coil through which the smaller current flows (coil 16 in the illustrated embodiment)
In the vicinity of, a circular magnetic neutral wire 18 is formed at a position determined by the ratio of absolute values of current. Reference numeral 19 is an electric field generating coil,
An electric field for generating discharge plasma is generated in the circular magnetic neutral wire 18. Further, reference numeral 14 is a substrate to be processed.

FIG. 4 shows another embodiment of the present invention implemented as a surface cleaning or film forming apparatus. In FIG. 4, the AC magnetic field generating means is composed of three linear current bars 21, 22,
23, and these current bars 21, 22, 23 are connected via a frequency / phase control device 24 to an AC or DC power supply (not shown). In this case, the magnetic neutral wire 25 formed is linear, plasma is formed there, and the surface of the strip-shaped member 27 delivered from the roll 26 is cleaned or deposited.
An alternating current with the same characteristics is applied to two horizontally arranged linear current bars 21 and 22, and a linear magnetic neutral wire 25 is placed at an intermediate position.
To form. An alternating current for adjusting the vertical position of the magnetic neutral wire 25 is supplied to the linear current bar 23 located below the magnetic neutral wire 25. Also, this linear magnetic neutral wire 25
A plasma is formed by applying an AC or DC electric field between the two electrodes 28, 29 respectively located at both ends of the. The plasma thus formed easily extends upward and cleans or forms a film on the surface of the strip-shaped member 27 delivered from the delivery roller 26.

FIG. 5 shows a surface vapor deposition apparatus as a modification of the apparatus shown in FIG. In this case, the AC magnetic field generating means is composed of a pair of linear current bars 31 and 32, and is connected to a power source (not shown) via the frequency / phase control device 24. A linear magnetic neutral line is placed between these linear current bars.
33 is formed. When the direct current flowing in the plasma generated along the linear magnetic neutral line 33 increases,
The plasma does not have a columnar shape, but has a sheet shape, and the magnetic neutral wire 33 also deforms into a sheet shape. The plasma spreads in the vertical direction in response to the magnetic neutral wire thus deformed into a sheet shape, and its lower edge touches the metal 35 in the crucible 34 to evaporate the metal. On the other hand, the upper end of the sheet-shaped plasma is the delivery roller 26.
To change the surface characteristics of the strip-shaped member 27 delivered from the. Electrodes 36 and 37 are provided on both ends of the sheet-shaped magnetic neutral wire 33, respectively.

FIG. 6 is a block diagram showing an example of a control system of the current flowing through each coil of the apparatus of the embodiment shown in FIG.
The illustrated control system has a control device 40 composed of a computer or a sequencer, and the control device 40 causes the first, second and third AC magnetic field forming coils, that is, the electromagnetic coils 4, 5, 6 to flow according to a preset program. Control signals 41, 42, 43 indicating the value, frequency and phase of the alternating current are supplied to the electromagnetic coils 4, 5, 6 via the interface circuits 44, 45, 46.
Frequency / phase control circuits 47, 48 provided in the power supply circuit of
49 and controls the frequency and / or phase of the alternating current flowing from these control circuits to each electromagnetic coil. Each of the frequency / phase control circuits 47, 48, 49 is connected to a common (or separate if necessary) power source (not shown). Further, the control device 40 supplies a control signal 50 for instructing ON / OFF of the current flowing to the high frequency coil 8 and power to the high frequency power supply 52 of the high frequency coil 8 via the interface circuit 51. The high frequency power source 52 is connected to the high frequency coil 8 via a matching box 53. Further, if necessary, a detector 54 for detecting the film thickness rate on the substrate, the discharge state, the ion density, etc. in the vacuum chamber 1 is provided, and the detection signal from this detector 54 is sent to the control device 40 as a feedback signal, and each power source is supplied. It is also possible to adjust the control signal for. A bias voltage (DC or high frequency) suitable for plasma processing is applied to the cathode 56 from the cathode bias power supply 55.

In the illustrated embodiment, the magnetic field generating coil is provided outside the plasma generating chamber, but it may be provided inside from the viewpoint of the function of the apparatus. Regarding the shape, it is possible to form a polygonal ring shape or a rectangular ring shape instead of the ring shape according to the shapes of the object to be processed (substrate or wafer) and the target. The illustrated embodiment has a configuration in which the frequency / phase control means is provided in the power supply circuit of the magnetic field generation coil, but it also includes that the magnetic field generation coil is directly excited by a commercial AC current of 50 Hz or 60 Hz. Be done. Further, although the number of magnetic field generating coils is three in the illustrated embodiment, it is sufficient if magnetic neutral lines can be formed,
Basically, two coils are enough. However, when it is intended to form multiple layers of annular plasma, multiple electromagnetic coils of three or more are provided and the annular magnetic neutral wire is formed in multiple layers instead of one annular magnetic neutral wire to generate plasma. It can also be operated precisely. Further, in the embodiment shown in FIG. 1 as an electric field generating means, a high frequency coil is provided as an outer layer in the middle coil, but basically, if an electric field is applied along the magnetic neutral line, it is separately provided as shown in FIG. It may be provided or may be provided in combination with another coil.

Further, in each of the above-mentioned embodiments, a circuit for supplying a current to the coil and the current bar is generated by coating the surfaces of the coil and the current bar with an insulator having a low outgas such as a ceramic having a low outgas. It can be electrically insulated from the ring-shaped or band-shaped plasma and is easy to handle.

Further, the present invention can be similarly applied to other process devices utilizing plasma such as a sputtering device and an etching device in addition to the illustrated device. In the case of sputtering, the target used is installed on the side opposite to the substrate, but even in the case of the racetrack type as shown in FIG. 7, the discharge part 57 (in this case, the coil is also the racetrack type) is moved from the outside to the center. And can be moved arbitrarily,
As a result, the usage efficiency of the target 58 can be improved.

[0018]

As described above, according to the present invention, the electric field generating means is provided along the magnetic neutral line formed by the alternating magnetic field generating means and having the spatially continuous magnetic field zero positions. Since it is configured to discharge and generate plasma, the position and size of the magnetic neutral line formed can be arbitrarily adjusted only by controlling the exciting current to the AC magnetic field generating means, and therefore the position where the plasma is generated. In addition to the effect of the previously proposed invention in that it can be easily displaced, and as a result, a uniform effect can be obtained in the process treatment, even if the vacuum chamber or the surrounding area is operated even when the long-time operation device is operated. The device is less likely to be magnetized, and the device can be used without being affected by the residual magnetic field. In addition, since the plasma is formed by the magnetic neutral line discharge, the charged particles of electrons and ions that are accelerated in the direction perpendicular to the magnetic field by the electric field can absorb the energy of the electric field well due to the special morphology of this method. Further, the effect that the damage due to the accelerated particles is less likely to occur is obtained. In addition, if the AC magnetic field generating means is designed so that the magnetic neutral line can be formed in a free shape according to the shape of the object to be processed, it can be generated simply by electrically controlling the exciting current to the AC magnetic field generating means. Since the position and shape of the plasma can be adjusted arbitrarily and easily, the structure of the device can be simplified and downsized, and the operation can be arbitrarily performed by a computer or the like.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing the configuration of a magnetic neutral wire discharge plasma processing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a magnetic field formation state in the apparatus of FIG.

FIG. 3 is a schematic cross-sectional view showing another embodiment of the present invention.

FIG. 4 shows another embodiment of the present invention, (a) is a schematic partial perspective view, and (b) is a schematic front view.

FIG. 5 shows still another embodiment of the present invention, (a) is a schematic partial perspective view, and (b) is a schematic front view.

6 is a schematic block diagram showing an example of a control system of the apparatus shown in FIG.

FIG. 7 is a schematic perspective view showing the displacement of the discharge part when the present invention is applied to a racetrack type sputtering cathode.

[Explanation of symbols]

 1: Vacuum chamber 2: Plasma generation chamber 3: Substrate processing chamber 4: Electromagnetic coil 5: Electromagnetic coil 6: Electromagnetic coil 7: Frequency / phase control device 8: Magnetic force line 9: Magnetic neutral line 10: High frequency coil 11: Gas introduction Port 12: Gas inlet 13: Exhaust port 14: Substrate

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/3065 9216-2G H05H 1/46 C H05H 1/46 H01L 21/302 B

Claims (7)

[Claims] 1. A discharge plasma processing apparatus adapted to process an object to be processed using plasma in a vacuum chamber, which is excited by an alternating current having a constant frequency,
AC magnetic field generating means for forming a magnetic neutral line which is a position of a magnetic field zero spatially continuously existing in the vacuum chamber, and along the magnetic neutral line formed by the AC magnetic field generating means A magnetic neutral wire discharge plasma processing apparatus comprising: an electric field generating means for forming an electric field to generate discharge plasma in the magnetic neutral wire. 2. The magnetic neutral line discharge plasma processing apparatus according to claim 1, wherein the AC magnetic field generating means comprises a coil whose surface is covered with an insulator. 3. The alternating magnetic field generating means comprises at least two alternating magnetic field generating coils coaxially arranged at intervals, and at least an annular magnetic neutral wire is provided between adjacent coils by passing an alternating current through these coils. The magnetic neutral line discharge plasma processing apparatus according to claim 1, wherein one is formed. 4. The relative position of the generated annular magnetic neutral wire to the alternating magnetic field generating coil is adjusted by controlling the magnitude of each alternating current flowing in each alternating magnetic field generating coil and the mutual phase difference. The magnetic neutral line discharge plasma processing apparatus according to claim 3, wherein 5. A discharge plasma processing apparatus configured to process an object to be processed using plasma in a vacuum chamber, which is excited by a constant alternating current and has a position of zero magnetic field continuously existing in the vacuum chamber. AC magnetic field generating means for forming a magnetic neutral line, and an electric field is applied along the magnetic neutral line formed by the AC magnetic field generating means to generate discharge plasma in the magnetic neutral line. A magnetic neutral wire discharge plasma processing apparatus comprising: an electric field generating means and a control means for controlling the magnitude and phase of an alternating current supplied to the alternating magnetic field generating means. 6. The magnetic neutral line discharge plasma processing apparatus according to claim 5, wherein the control means is configured to control the frequency of the AC power supply supplied to the AC magnetic field generation means. 7. The magnetic neutral line discharge plasma processing apparatus according to claim 5, wherein the control means is configured to control the phase of the AC power supply supplied to the AC magnetic field generation means.