JP2000156374A - Plasma processing apparatus applying sputtering process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma sputtering device capable of attaining high ion concentration, excellent efficiency in utilizing targets, high film forming velocity and uniformity in film thickness. SOLUTION: A plasma processing device to which sputtering is applied is provided with an reaction container 100 comprising an upper electrode 1 and a lower electrode 23 facing in parallel each other via at least one part of the inner space in the reaction container, and a target plate 7 secured on the upper electrode. An electrode 27 which requires a processing by a sputtering process is mounted on the lower electrode. One of the first rf power source 18 which works in an HF region or a VHF region and the other power source which works in an MF region are connected to the upper power source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus for sputter processing applications, and more particularly to a plasma ion density at an rf electrode, which is useful in the semiconductor industry during the process of manufacturing integrated circuits during the sputtering of metal or dielectric materials. And a plasma processing apparatus, such as a plasma-assisted sputtering apparatus, having an improved plasma source capable of independently controlling ion energy.

[0002]

BACKGROUND OF THE INVENTION With future demands in the semiconductor industry, large area, high density plasma sources are needed to process large area substrates. In particular, it is important to develop a new plasma source for the process of spattering a metal or a dielectric material while increasing the uniformity of the deposited film and increasing the utilization efficiency of the target. These facts are illustrated using two conventional plasma sources according to FIGS. 7-10, which are typically used in 200 mm wafer or flat panel plasma processing equipment.

FIGS. 10 to 12 show simplified views of a conventional magnetron-type plasma source used for sputtering applications in the semiconductor industry. The reaction vessel 50
Basically, it is constituted by an upper electrode 51 made of a non-magnetic metal, a cylindrical side wall 52, a bottom plate 53, and a lower electrode 59. Upper electrode 51 and lower electrode 59
Are parallel to each other via at least a main part (inner space) of the reaction vessel 50. The side walls 52 and the bottom plate 53 are made of metal, for example, stainless steel. The upper part of the side wall 52 is made of an insulator 54, and the upper electrode 51 is disposed on the insulator 54. A target plate 55 made of a material that needs to be sputtered is fixed to the lower surface of the upper electrode 51. The target plate 55 has a slightly smaller dimension than the upper electrode 51. A center magnet 56a and an outer magnet 56b are concentrically arranged on the upper surface of the upper electrode 51. The center magnet 56a is a block having a circular shape. The outer magnet 56b has a ring shape. The height and width of the magnets 56a, 56b are not critical and can be selected according to the dimensions of the reaction vessel. Magnets 56a, 56b
Are arranged on the upper electrode 51 so as to have opposite magnetic poles toward the inside of the reaction vessel 50. Such an arrangement of these magnets generates a magnetic field 57 that is directed from the center to the periphery and vice versa, as shown in FIG.

[0004] A substrate 58 to be processed is mounted on a lower electrode 59 which is electrically insulated from the bottom plate 53 by placing it on an insulator 60. Lower electrode 5
9, an rf power supply (high-frequency power supply) through a matching circuit 64
Rf power from 63 may or may not be provided. If rf power is supplied to the lower electrode 59, the frequency of the rf power supply 63 is usually in the MF range. When the rf current is applied to the lower electrode 59,
The lower electrode 59 is negatively biased, thereby causing the substrate 5
An ion bombardment is brought about on the surface of FIG. Ion collisions
The self-bias voltage of the lower electrode 59 is controlled so that the deposition rate of the film exceeds the etching rate of the film, which causes etching of the film deposited on the surface of the substrate.

The upper electrode 51 passes through a matching circuit 62 to rf
Connected to power supply 61. The frequency of the rf power supply 61 is usually 1
Operates at 3.56 MHz. When rf power is applied to the upper electrode 51, a plasma is generated by a capacitive coupling mechanism.

As shown in FIG. 13, a racetrack-shaped magnetic field region 65 is used in another conventional magnetron type sputtering source. Except for the shapes of the center magnet 66a and the outer magnet 66b, all other parts are shown in FIG.
12 are the same as those shown in FIGS. The magnets 66a and 66b have a rectangular shape with rounded corners, and the generated plasma has a similar shape. Therefore, when using this plasma source, the substrate needs to be passed through a plasma region to obtain a uniform film deposition over the substrate surface.

[0007]

The parallel plate plasma reactor shown in FIG. 10 has a large-area plasma by close parallel electrodes 51 and 59, and easy ignition of plasma.
n) and has several advantages, such as controllability of the ion energy of the plasma at the electrode surface. However, due to the inherent attributes of capacitively coupled plasmas, the ion density of these plasma sources will be low, especially if excitation is used with a low rf frequency, eg, 13.56 MHz. The ion density is increased by increasing the rf excitation frequency. However, an increase in the excitation frequency causes a decrease in the self-bias voltage, which results in a decrease in ion energy and thereby a decrease in sputtering rate. in this way,
One of the major disadvantages of this type of plasma source is that the self-bias voltage and plasma ion density cannot be controlled independently.

A second problem with parallel plate plasma reactors is the non-uniform etching rate of the target plate 55 connected to the upper electrode 51. When a plasma is created, the electrons between the two magnets 56a, 56b are confined by the magnetic field 57, resulting in an increase in the plasma density. Since the magnetic field 57 is present in the donut shaped region, the higher density plasma also has the same shape. Therefore, the material portion of the target plate 55 between the magnets 56a and 56b is sputtered at a higher speed.
In contrast, the plasma density in the central and peripheral regions is relatively weaker, and therefore, the sputtering rate at the target portion corresponding to these regions is lower. Due to this non-uniform sputtering rate of the target plate 55, after prolonged operation, the profile of its cross-sectional shape becomes as shown in FIG. The area between the center and the periphery of the surface of the target plate 55 will be initially unusable. Since the region having the highest etching rate determines the life of the target plate 55, the configuration of the magnets 56a and 56b lowers the utilization efficiency of the target material.

A third problem is that the plasma generated below the target plate 55 has a high degree of non-uniformity along the radial lines. This causes a non-uniform flow of target material from the target plate 55 to the substrate 58, which leads to non-uniform film deposition on the surface of the substrate 58. In order to obtain a uniform flow of material to be sputtered, the substrate 58 must be mounted further down in the reaction vessel 50, which
This causes the aspect ratio of 0 to be further increased. However, increasing the electrode spacing results in a reduced film deposition rate.

[0010] A fourth problem is that if the plasma is non-uniform, it will cause a non-uniform ion flow over the surface of the substrate. This causes local charge accumulation on the surface of the substrate 58, especially if the substrate 58 is negatively biased by applying rf power to the This results in electrical breakdown of sub-micron scale elements. Damage due to this charge accumulation is expected to occur particularly in the magnet arrangement shown in FIG. This is because generally only a part of the substrate is exposed to the plasma.

[0011] A fifth problem of the conventional sputtering apparatus is poor bottom coverage in fine contact holes. The problem was that the particles were oriented (collimate
d) The problem can be solved by using a sputtering apparatus or a long throw sputtering apparatus in which the electrodes are further separated from each other and the interval between them is increased, but this apparatus creates a problem that the film forming speed is reduced.

Another way to obtain a flow of ions parallel to the substrate surface is to apply a bias voltage to the substrate 58. This step is called ionization sputtering. Ionized sputtering achieves good bottom coverage in fine contact holes. In this step, the sputtered material is ionized between the electrodes 51 and 59 by charge transfer collision. Therefore, to achieve higher deposition rates, the concentration of ions in the plasma must be increased. However, the plasma ion density is low for a 13.56 MHz discharge. Further, a small portion of these ions are consumed by the target plate 55. Therefore, there is not enough ion concentration to ionize sputtered atoms, resulting in a low deposition rate.

[0013] It is an object of the present invention to provide a plasma processing apparatus for sputter processing applications with higher ion concentration, better target utilization efficiency, higher deposition rate, and better thin film thickness uniformity. is there.

[0014]

According to the present invention, there is provided a plasma processing apparatus to which the present invention is applied.

The plasma processing apparatus includes a reaction vessel having an upper electrode and a lower electrode facing each other in parallel via at least a part of the internal space of the reaction vessel, and a target plate fixed to the upper electrode. ing. The substrate to be processed is mounted on the lower electrode and processed by a sputtering process. Further, the plasma processing apparatus includes one rf power supply (high-frequency power supply) connected to the upper electrode and operating in the HF region or the VHF region, and another rf power supply (high-frequency power supply) connected to the upper electrode and operating in the MF region. It has.

The plasma processing apparatus can include a DC power supply connected to the upper electrode instead of the second rf power supply.

In the above-described plasma processing apparatus, the upper electrode is made of a non-magnetic metal, and a plurality of magnets are separately arranged outside the upper electrode and face the inside of the reaction vessel of the magnet. The poles are alternatively changed (to be either north or south pole) and these magnets create a magnetic field of closed magnetic flux near the inner surface of the top electrode.

In the above-described plasma processing apparatus, the upper electrode has a plate-like circular or rectangular shape, and the magnet is disposed directly on the front surface of the upper electrode.

In the above-described plasma processing apparatus, the plurality of magnets can move at least half the distance between two adjacent magnets having the same polarity.

In the above-described plasma processing apparatus, another rf power source that operates in one of the MF region, the HF region, and the VHF region is connected to the lower electrode.

In the above-described plasma processing apparatus, the rf power source of the MF is connected to the upper electrode via a low-pass filter.

In the above-described plasma processing apparatus for sputter processing applications, preferably, a plurality of bar-shaped magnets are directed toward the inside of the reaction vessel so as to generate a linear cusp magnetic field near the inner surface of the side wall. With an alternative polarity, around the surface of the cylindrical side wall of the reaction vessel, i.e., spaced at or near the outer or inner surface of the side wall, or perpendicular to the inside of the side wall Placed in

In the above-described plasma processing apparatus for sputter processing application, preferably, the plurality of magnets are
Providing alternative magnetic poles toward the inside of the reaction vessel to generate a point cusp magnetic field near the inner surface of the side wall;
They are individually arranged around the surface of the cylindrical side wall of the reaction vessel, ie more preferably on the outer surface of the side wall.

The above-described structure for generating the cusp magnetic field using the bar-shaped magnet or the magnet can prevent the cusp magnetic field from causing plasma loss due to contact with the inner surface of the side wall.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments will be described below with reference to the accompanying drawings. Details of the present invention will be made clear through the description of the embodiments.

The first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a sectional view of a plasma source used in the plasma processing apparatus of the first embodiment. This plasma processing apparatus is of a capacitive coupling type, and is used for sputter deposition. The reaction vessel 100 is substantially the same as the conventional reaction vessel 50 described above. The reaction vessel 100 essentially comprises an upper electrode 1, a cylindrical side wall 3, a bottom plate 2, and a lower electrode 23. The reaction vessel 100 also includes, for example, a gas exhaust port. The gas exhaust port is not shown in FIG. 1 for simplicity. The upper electrode 1 and the lower electrode 23 are parallel to each other via at least a main part (internal space) of the reaction vessel 100. Side wall 3
And the bottom plate 2 are made of metal such as, for example, stainless steel. A target plate 7 made of a material that needs to be sputtered is fixed to the lower surface of the upper electrode 1. The target plate 7 has a slightly smaller dimension than the upper electrode 1. Upper electrode 1 is A
It is made of a metal such as l (aluminum) and is located on the upper part 4 of the cylindrical side wall. Upper part 4
Is made of a dielectric material (or insulating material). The upper electrode 1 may have a circular shape or a square shape. The dimensions of any shape are not critical and can vary depending on the size of the substrate that needs to be processed. The upper electrode 1 is a reaction vessel 10
0, which then becomes the part that is built into the ceiling. The side wall 3 and the bottom plate 2 are electrically grounded.

The target plate 7 is made of, for example, Ti, Ti
It is made of N or SiO ₂ . The shape of the target plate 7 is similar to the shape of the upper electrode 1.
If the upper electrode 1 is circular, the target plate 7 is also circular. Target plate 7
Are smaller than the upper electrode 1. The thickness of the target plate 7 is usually 5 to 10 mm.

The edge of the target plate 7 is covered with a metal plate 8 usually called a shield plate. The distance between the target plate 7 and the shield plate 8 is about 1 to 3 mm. The shield plate 8 is the side wall 3
And is electrically grounded.

The thickness of the upper electrode 1 is not important.
Usually it is 20 to 40 mm. The upper electrode 1 is usually connected to a cooling mechanism (not shown in FIG. 1). The step of cooling the upper electrode 1 is important because the upper electrode 1
Since the target plate 7 and the target plate 7 are heated during the action due to the higher ion flow onto the target material, the target plate 7 must be secured to the upper electrode 1 with a vacuum shield.

The process gas, preferably Ar, is applied to the side wall 3
The gas is supplied to the reaction vessel 100 through a gas introduction port (not shown) formed in the reaction vessel 100. The internal pressure of the reaction vessel 100 is controlled by adjusting the gas flow rate and a well-known variable orifice (not shown) located at the gas exhaust port. The internal pressure of the reactor 100 ranges from 1 mTorr to 100 m depending on the type of plasma process.
Can be changed up to Torr.

The reaction vessel 100 has a high frequency (HF) or very high frequency (VHF) rf power source (power source) 18. The frequency of the rf power supply 18 is about 10 to 100 MHz
And typically 13.56 MHz or 6
Operates at 0 MHz. The rf power supply 18 typically has low impedance, typically around 50 ohms (Ohm), and can produce 0.5-5 kW of rf power. The output of the rf power supply 18 is supplied to the upper electrode 1 through the matching circuit 19.

The reaction vessel 100 further includes an intermediate frequency (MF)
Rf power supply 20 is provided. The frequency of the MF / rf power supply 20 is in the range of 0.5 to 5 MHz, typically 1.6.
Operates at MHz. The rf power supply 20 typically has a low impedance, typically around 50 ohms,
An rf power of 0.5 to 3 kW can be generated. r
The output of the f power supply 20 is supplied to the upper electrode 1 through the matching circuit 21. Further, the low-pass filter 22 detects that the HF or VHF rf current flowing from the upper electrode 1 is MF · r
f is added between the upper electrode 1 and the matching circuit 21 to block the flow to the power supply 20.

The lower electrode 23 is fixed to the bottom plate 2 via an insulator 28. The lower electrode 23 is electrically insulated from the bottom plate 2. The substrate 27 is disposed on the lower electrode 23.

The reaction vessel 100 may or may not have a third rf power supply connected to the lower electrode 23. In the configuration shown in FIG. 1, the reaction vessel 100 has a third rf power supply 24. If the reaction vessel 100 is provided with a third rf power supply 24, whereby rf power is applied to the lower electrode 23, the frequency of the rf power is M
It is in the F region, HF region or VHF region. This rf
Power supply 24 also has a low impedance, typically 50 ohms, and can produce up to 1 kW of rf power. The rf power is supplied to the lower electrode 23 via the matching circuit 25. Here high-pass filter 2
One end of 6 is connected to a transmission line between lower electrode 23 and matching circuit 25. The other end of the high-pass filter 26 is grounded. The purpose of using the high-pass filter is to create a ground path for the rf current of HF coming from the lower electrode 23. This method uses the rf r of the third rf power supply 24.
Protects against potential damage from f-currents.

Reaction vessel 100 provided with the above-mentioned plasma source
Will be described. From the rf power supply 18 and the rf power supply 20 to the
When given an rf current acting in the region of the HF, a plasma is created by the mechanism of capacitive coupling of these rf powers. Since the electrons have a higher thermal velocity than the ions, the upper electrode 1 is negatively biased. Upper electrode 1
The self-bias voltage at depends greatly on the excitation frequency of the plasma. Increasing the plasma excitation frequency causes a decrease in self-bias voltage and an increase in plasma density.
The value of the negative bias voltage at the top electrode 1 also depends on the ratio of the surface area of the top electrode to the anode area. Here, the anode area is the total surface area of all grounded surfaces. The anode area is usually
In any plasma source, it is larger than the surface area of the top electrode (cathode). This causes a negative self-bias voltage of the upper electrode 1. Due to this negative bias, ions in the plasma are accelerated toward the upper electrode 1 and cause the target plate material to be sputtered into the plasma. In order to obtain a higher sputtering rate, both the ion density and the self-bias voltage of the upper electrode 1 must be increased.

[0036] Increasing the rf power increases the plasma ion density. However, if the plasma excitation frequency is V
When in the HF region, eg, 60 MHz, even at higher rf powers, the self-bias voltage is not sufficient for economical sputtering rates. Therefore, another intermediate frequency rf current is provided to the upper electrode 1. Capacitive coupling of the lower frequency rf current to the plasma results in a higher negative bias voltage on the top electrode. The value of the negative bias voltage is independently controlled by changing the rf current of the MF. Therefore, the HF r
The combination or combination of the f current and the rf current of the MF is
A solution is provided for independent control of plasma ion density and ion energy.

The ionization rate of the sputtered atoms is VH
Augmented by the high density plasma generated by the F current. The ionized atoms are accelerated toward the substrate surface by the bias potential generated on the lower electrode 23 due to the application of the rf current (third rf power supply), and the movement direction becomes parallel. If the rf current applied to the lower electrode 23 is in the VHF region, a high density plasma will be generated close to the lower electrode 23. This increases the ionization rate of the sputtered atoms, resulting in a higher deposition rate. This mechanism produces good bottom coverage on the patterned substrate without degrading the deposition rate.

Next, a second embodiment will be described with reference to FIG. In the second embodiment, except for the electrical connection to the upper electrode 1, all other configurations are the same as those provided in the first embodiment.

The upper electrode 1 is connected to an rf power supply 18 operating in the HF region or the VHF region via a matching circuit 19, similar to the first embodiment. The details of the rf power supply 18 are the same as those given in the first embodiment. Further, the upper electrode 1 is connected to a DC voltage supply 29 through a dielectric (L) 30. One terminal of the capacitor (C) 31 is connected to a transmission line between the inductor 30 and the upper electrode 1. The other terminal of the capacitor 31 is grounded. This electrical connection protects DC voltage supply 29 from parasitic rf currents. DC voltage source 29 is -100
Voltages up to 0 volts can be provided.

According to the configuration of the second embodiment described above, r
When an f-current is applied to the upper electrode 1, a plasma is generated by a capacitive coupling mechanism. By controlling the applied rf power, the ion density in the plasma is adjusted. The upper electrode 1 in the second embodiment is electrically grounded with respect to the VHF current. Therefore, no self-bias voltage is generated on the upper electrode 1 by the rf current applied to the upper electrode 1. Instead, a DC voltage supply 29 is used to apply a negative bias to the upper electrode 1, which is required to accelerate the ions onto the target plate 7. The superposition of a negative DC bias on the upper electrode 1 has no effect on the plasma potential. Therefore, the ion density of the plasma and the bias voltage of the upper electrode 1 can be independently controlled with this configuration similar to the first embodiment. The main advantage of the second embodiment is that only one rf power supply is required for the upper electrode 1. That is, M shown in FIG.
The rf power supply 20, matching circuit 21, and low-pass filter circuit 22 of F can be omitted.

Next, a third embodiment will be described with reference to FIGS. FIG. 3 shows the overall configuration of the third embodiment. This configuration is largely similar to the first embodiment except that a magnet is added on the upper electrode 1. FIG. 3-
In 5, each of the elements corresponding to the elements described in the first embodiment has the same reference number or reference numeral. Furthermore, for example, two gas discharge ports 17 are formed in the bottom plate 2. The plurality of magnets 5 are connected to the upper electrode 1
Outside, are individually spaced apart. The polarity of the plurality of magnets 5 facing the interior of the reaction vessel 100 is alternatively changed (to be one of the north pole and the south pole), and the magnet 5 is positioned inside the upper electrode 1. A magnetic field 6 with a closed magnetic flux near the surface is generated.

The thickness of the upper electrode 1 is not important.
Usually, 20 to 40 mm is adopted. Above the upper electrode 1, a plurality of grooves 9 are provided for disposing the magnet 5.
The corner portion of the groove 9 has a square or circular shape depending on the sectional shape of the magnet 5. The width of the groove 9 is selected to be approximately 1 mm larger than the width of the magnet 5. The length of the groove 9 is selected to be at least (1/2) × x when the distance between adjacent magnets 5 having the same polarity is x. The depth of the groove 9 is such that the bottom surface of the magnet is
Is usually adopted as 2 to 5 mm shorter than the thickness of the upper electrode 1 so as to approach the internal space of the upper electrode 1. However, it is also possible to have a groove passing through the upper electrode 1 so that the lower surface of the magnet contacts or comes closer to the target plate 7.

The arrangement relating to the plurality of magnets 5 corresponds to the reaction vessel 1
A higher magnetic field is created in the internal space of 00. The grooves 9 are preferably made with parallel groove lines, as shown in FIG. 3, so that there is a space between each two groove lines. In these spaces, long passages are formed inside the upper electrode 1, and these passages are connected to each other so as to have a zigzag-shaped passage 10 as shown in FIG. The cross-sectional shape of the zigzag passage 10 is circular, square, or rectangular. The zigzag-shaped passage 10 is completely buried in the upper electrode 1 except for the start point and the end point. As shown in FIG. 5, the starting point is connected to the water intake port 11 and the ending point is connected to the water discharge port 12. Thus, during operation of the device, water flows through the zigzag-shaped passages 10 in the upper electrode 1 to cool the upper electrode 1. The water cooling step of the upper electrode 1 is important because the upper electrode 1 and the target plate 7 are heated during operation of the device due to the irradiation of the target material with a higher ion flux. The rise in the temperature of the upper electrode 1 causes the magnetic field strength of the magnet 5 to decrease. Note that different methods for cooling the upper electrode 1 can be used.

The shape of the magnet 5 is preferably cubic, rectangular or cylindrical (or cylindrical). The magnet 5 is arranged in each of the grooves 9 formed on the upper electrode 1. The plurality of magnets are arranged at equal distances, for example, at the corners of individual squares drawn on top electrode 1. The polarity of the plurality of magnets can be alternatively changed as shown in FIG. The dimensions of the cross section of the magnet 5 are not important. If the cross-section is circular, its diameter is in the range of 5 to 15 mm. If the cross-sectional shape is square, one comparable to that of a circular shape is employed. The spacing between any two adjacent magnets is not critical and can vary from 15 to 50 mm. Next, the upper surfaces of all the magnets 5 are connected together using a metal plate (strip: elongated plate) 13. One end of each metal plate 13 has a rotating plate 15 rotated by an electric motor 16.
The rotation of the rotating plate 15 causes all of the magnets 5 to move horizontally inside the groove 9. The moving distance can be changed by changing the diameter of the rotating plate 15, while
The moving speed can be selected by changing the rotating speed of the rotating plate 15.

The arrangement of the magnets 5 forms a magnetic field cusp below the upper electrode 1 as shown in FIG. That is, the line 6 representing the magnetic field is bent directly toward the adjacent magnet without penetrating deeply into the reaction vessel 100. The magnetic field lines 6 parallel to the upper electrode 1 are stronger between two magnets having opposite polarities, and thus the confinement of electrons is stronger between two opposite magnets 5. The magnetic field line 6 is weak between two having the same polarity. That is, electron confinement is weak between two magnets having the same polarity. Thus, electrons trapped between two magnets of opposite polarity can escape through the space between two magnets of the same polarity. Therefore, the above-described magnet arrangement only partially confines electrons. Due to the partial confinement of the electrons, they can impact the upper electrode 1 and create a negative bias voltage for the upper electrode 1. Furthermore, due to the partial confinement of the electrons, the higher ion flow to the upper electrode 1 is easily electrically neutralized by the electrons, resulting in a stable plasma environment.

Hereinafter, the uniformity of the plasma and the utilization efficiency of the target will be described. Similar to the first embodiment, the target plate 7 holds the upper electrode 1 in a state where a vacuum shield is applied.
Fixed to The plasma is non-uniform due to the non-uniform magnetic field in contact with the target plate 7. However, since the plurality of magnets 5 are arranged close to each other, the non-uniform plasma becomes uniform plasma at a short distance from the target plate 7. Thus, there is a uniform plasma over the substrate surface. For example, even if the sputtering rates between two opposite polarity magnets on the target plate 7 and between magnets of the same polarity are different, their regions are close to each other. Therefore, the sputtered material from the target plate diffuses within a short distance from the target plate,
A uniform thin film is formed on the surface of the substrate 27.

The low or zero etching rate near the poles of the magnet compared to the area between the magnets on the surface of the target plate 7 is a consequence of the non-uniformity of the plasma close to the target plate, Is done. The highest etching rate of the target plate 7 is observed at the center of the magnet 5 where the density of the magnetic flux perpendicular to the surface of the target plate 7 is lowest. Therefore,
When the magnet 5 is fixed, a uniform etching rate on the target plate cannot be observed. When the magnet is moved at (1/2) × x, the pole is at the highest etch rate position. Therefore, the time-averaged uniform etching rate of the target material is obtained by the vibration of the magnet by (1/2) × x. This increases target utilization efficiency.

Next, a fourth embodiment will be described with reference to FIG. FIG. 6 shows a sectional view of the fourth embodiment. All other configurations are the same as those of the third embodiment except for the configuration of the electrical connection made to the upper electrode 1. The electrical connection made to the upper electrode 1 is similar to that of the second embodiment. Actually, the fourth embodiment corresponds to a combination of the second embodiment and the third embodiment. In FIG. 6, each of the components corresponding to the components described in the second and third embodiments has the same reference numeral or reference number.

The upper electrode 1 shown in FIG.
Is connected to the rf power supply 18 of the VHF. The details of the VHF rf power supply 18 are the same as those given in the first embodiment. The upper electrode 1 is connected to a DC voltage supply 29 via an inductor 30. One terminal of the capacitor 31 is connected to a transmission line between the inductor 30 and the upper electrode 1. Capacitor 3
One other terminal is grounded. This electrical connection is DC
Protects voltage supply 29 from parasitic rf currents. DC voltage source 29 can supply voltages up to -1000 volts.

With this configuration, the upper electrode 1 is electrically
It becomes grounded for f current. Therefore, a negative bias cannot be obtained due to the rf current applied to the upper electrode 1. Instead, a DC voltage supply 29 is used to provide a negative bias to the upper electrode 1. The negative bias on the upper electrode 1 accelerates ions on the target plate 7. The main advantage of the fourth embodiment is that it employs only one rf power supply for the upper electrode 1. That is, with this configuration, the rf power supply of the MF, the low-pass filter circuit, and the matching circuit described above can be omitted.

A fifth embodiment of the present invention will be described with reference to FIGS. FIG. 7 shows a sectional view of the fifth embodiment, which is similar to FIG. 1, and FIG. 8 is a sectional view taken along line AA in FIG. The reference numerals of the components shown in FIGS. 7 and 8 correspond to those shown in FIG. Except for the structure related to the magnet and the parts related to this structure, the remaining structure of the fifth embodiment is the same as that shown in FIG. Therefore, description of the remaining structure is omitted here. In this embodiment, the reaction vessel 10
The zero cylindrical side wall 3 is made of a non-magnetic metal such as aluminum, and a plurality (or several) of bar magnets 32 are provided with alternative polarities (N-pole and As shown in FIG. 7, the cylindrical side wall 3 has one of the south poles.
Arranged vertically around the outer surface of the The arrangement of the bar magnets 32 surrounding the cylindrical side wall 3 is shown in FIG. These bar magnets 32 are mounted directly on the outer surface of the side wall 3 or are arranged on the outer surface with a small spacing. If an interval is provided between the bar-shaped magnet 32 and the side wall 3, the interval is usually 10 mm or less.

The outer surface of the rod-shaped magnet 32 is usually
Ferromagnetic metal such as soft iron
They are connected by 33 plates. Rod magnet 32
The size is not important. The cross-sectional shape of the bar-shaped magnet 32 is usually a square or a rectangle. If the cross section is square, its size is 5 × 5m
It is in the range from m ² to 30 × 30 mm ² . If the cross-sectional shape is rectangular, its size is chosen to have a surface area comparable to that of a square shape. The length of the bar-shaped magnet 32 in the vertical direction is usually equal to the distance between the shield plate 8 and the substrate loading / unloading slot 36. The substrate loading / unloading slot 36 is an opening used for loading and unloading the substrate 27, and usually includes a gate. 2
The spacing between two adjacent bar magnets 32 is likewise not critical and is typically between 20 mm and 100 mm.
In the range. Usually, the bar-shaped magnets 32 are arranged at equal intervals. The strength of the magnetic field at the poles of the bar magnet 32 is likewise not critical,
The range is selected from uss (gauss) to 12 kGauss (kilogauss). However, the strength of the magnetic field of the bar-shaped magnet and the distance between the magnets are different depending on the strength of the magnetic field of the substrate 2.
7 must be chosen to be negligible on the surface. The relationship between the magnetic field strength of the bar-shaped magnet 32 and the distance between two adjacent bar-shaped magnets 32 is as follows.
Increasing the strength of the magnetic field promotes a decrease in the spacing, and vice versa.

When several bar magnets 32 having the above-described structure are arranged around the cylindrical side wall 3 of the reaction vessel 100, a cusp (linear cusp) magnetic field 34 is generated on the inside of the cylindrical side wall 3, that is, As shown in FIG. 8, it is formed near the inner surface of the sidewall. These cusp magnetic fields 3
4 reduces plasma loss at the cylindrical side wall 3 by trapping electrons by the cusp magnetic field 34. This results in increased plasma density in the plasma, which results in increased sputtering efficiency.

In FIG. 7, lower electrode 23 is made of insulator 28.
And is fixed to the bottom plate 2 via. However, a movable lower electrode can be used instead of a fixed lower electrode. If a movable lower electrode were used, the substrate 27 would be raised to a height above the lower end of the bar magnet 32, where the plasma would be very well confined. This process can increase the deposition rate of the sputtered material.

The fifth embodiment has been described by using the plasma processing apparatus described in the first embodiment.
The same structure of the rod-shaped magnet 32 can be applied to the plasma processing apparatus described in the second, third, and fourth embodiments for the same purpose.

Furthermore, the arrangement of the bar magnets described above can also be arranged around the inside surface of the side wall 3, ie inside, on the inside surface of the side wall 3, or inside the side wall. However, in the case of the arrangement inside the side wall, each bar magnet must be covered with an insulating member or a non-magnetic metal. Regardless of whether the bar magnet is inside or outside the side wall 3, the magnetic field between the bar magnet 32 and the strength of the magnetic field at the bar magnet 32 is adjusted so that the magnetic field becomes zero at the position of the substrate stage. It is important to adjust the spacing.

A sixth embodiment of the present invention will be described with reference to FIG. FIG. 9 is an external view showing the cylindrical side wall 3 of the reaction vessel 100 and another magnet arrangement outside the side wall. For simplicity, other parts of the plasma processing apparatus are not shown in FIG. Further, as in the fifth embodiment, the reaction vessel has the same configuration as that in the first, second, third, and fourth embodiments. The side wall 3 of the reaction vessel is made of a non-magnetic metal,
For example, it is made of metal such as aluminum. A plurality of magnets 35 are arranged on the outer surface of the side wall 3 with either polarity towards the inside of the reaction vessel. The other magnetic pole of the magnet 35 facing the outside of the reaction vessel is connected by a ferromagnetic metal plate 36 such as soft iron, for example. In FIG. 9, only a small number of ferromagnetic metal plates 37 are shown for easy understanding. The size and shape of the magnet 35 are not important. If a cubic magnet 35 is used, its size is 5
It can vary between × 5 × 5 mm ³ and 20 × 20 × 20 mm ³ . If a cylindrical magnet is used, its cross-sectional size will vary from 5 mm to 20 mm and its height can vary from 5 mm to 50 mm. The strength of the magnetic field at the magnetic poles of the magnet 35 and the distance between the magnets are selected so that the magnetic field becomes zero at the substrate stage. Usually, the magnetic field strength is from 500 Gauss to 1
It can be changed by 2KGauss, and the distance between magnets can be changed from 5mm to 40mm.

When a plurality of magnets 35 are arranged as shown in FIG. 9, a cusp (point cusp) magnetic field is created on the inner surface of the cylindrical side wall 3. Because the magnetic flux lines of the magnetic field bend towards the nearest opposite pole without penetrating deep into the interior of the reaction vessel. When the plasma is created, electrons are trapped by these point cusp fields, resulting in reduced electron losses at the sidewalls. This leads to an increase in plasma density,
This leads to an increase in sputtering efficiency as in the example described in the first embodiment.

The aforementioned magnet 35 exists around the outer surface or the inner surface of the side wall 3, similarly to the bar-shaped magnet 33.

[0060]

The plasma processing apparatus according to the present invention has a large area uniformly distributed over a plane over the entire surface of the substrate, with independent control of ion density and ion energy and a uniform etching rate of the target material. A high-density plasma can be created, and a plasma source having a low aspect ratio can be realized.

Further, a plasma treatment with a rod-shaped magnet or a magnet for generating a cusp magnetic field,
Plasma loss due to the inner surface of the side wall can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a first embodiment showing a reaction vessel, capacitive electrodes, and their electrical connection relationships.

FIG. 2 is a cross-sectional view of a second embodiment showing a reaction vessel, capacitive electrodes, and their electrical relationships.

FIG. 3 is an explanatory view of the external appearance of a third embodiment showing the internal and external characteristic structures of the plasma processing apparatus according to the present invention.

FIG. 4 is a cross-sectional view showing an arrangement of a plurality of magnets and an internal structure of a third embodiment.

FIG. 5 is a plan view of the upper electrode without showing a metal plate attached to the magnet for moving the magnet.

FIG. 6 is a fourth view showing the inner and outer structures of the plasma source.
It is a sectional view of an embodiment.

FIG. 7 is a sectional view of a plasma processing apparatus according to a fifth embodiment.

FIG. 8 is a sectional view taken along line AA in FIG.

FIG. 9 is an external view showing a cylindrical side wall of the reaction vessel and an arrangement of magnets outside the side wall.

FIG. 10 is a cross-sectional view showing a first conventional plasma source used for plasma processing.

FIG. 11 is an explanatory diagram of a magnetic field formed by a magnet used in the first conventional plasma source.

FIG. 12 is a cross-sectional view of a conventional target plate showing non-uniform etching.

FIG. 13 is a schematic diagram showing an arrangement of magnets in a second conventional plasma source used for plasma processing.

[Description of reference numerals]

 DESCRIPTION OF SYMBOLS 1 Top electrode 2 Bottom plate 3 Side wall 5 Magnet 6 Magnetic field line 7 Target plate 9 Groove 10 Zigzag passage 13, 14 Metal plate 15 Rotating plate 16 Motor 18 rf power supply of HF or VHF 20 rf power supply of MF 22 Low pass filter 23 Lower electrode 24 MF rf power supply 26 High pass filter 27 Substrate 29 DC power supply (DC voltage supply source) 32 Rod magnet 33, 36 Ferromagnetic metal 34 Cusp magnetic field 35 Magnet

Claims (9)

[Claims] 1. A reaction container comprising an upper electrode and a lower electrode facing each other in parallel through at least a part of the internal space of the reaction container, and a target plate fixed to the upper electrode, A plasma processing apparatus in which a substrate mounted on the lower electrode is processed by a sputtering process; a first rf power supply connected to the upper electrode and operating in an HF region or a VHF region; And a second rf power supply connected and operating in the MF region. 2. A reaction vessel comprising an upper electrode and a lower electrode facing each other in parallel across at least a part of the internal space of the reaction vessel, and a target plate fixed to the upper electrode, A plasma processing apparatus in which a substrate mounted on the lower electrode is processed by a sputtering process; a first rf power supply connected to the upper electrode and operating in an HF region or a VHF region; A plasma processing apparatus for sputter processing, which is configured by a DC power supply connected thereto. 3. The upper electrode is made of a non-magnetic metal, a plurality of magnets are individually arranged outside the upper electrode, and the polarity of the magnet facing the inside of the reaction vessel is alternatively selected. 3. A plasma processing apparatus according to claim 1 or 2, wherein said magnet is varied and said plurality of magnets generate a magnetic field formed by a closed magnetic flux near an inner surface of said upper electrode. 4. The plasma processing apparatus according to claim 3, wherein the upper electrode has a flat circular or rectangular shape, and the magnet is disposed directly on an outer surface of the upper electrode. 5. The plasma processing apparatus according to claim 3, wherein the plurality of magnets move at least one half of a distance between two adjacent magnets having the same polarity. 6. The plasma processing apparatus according to claim 1, wherein another rf power source operating in one of MF, HF, and VHF regions is connected to the lower electrode. . 7. The plasma processing apparatus according to claim 1, wherein an rf power source of the MF is connected to the upper electrode via a low-pass filter. 8. An alternate polarity disposed vertically around the surface of the cylindrical side wall of the reaction vessel and toward the inside of the reaction vessel to generate a cusp magnetic field near an inner surface of the side wall. The plasma processing apparatus according to any one of claims 1 to 7, further comprising a plurality of rod-shaped magnets having the following. 9. An alternative, individually disposed around the surface of the cylindrical side wall of the reaction vessel, facing towards the inside of the reaction vessel to generate a cusp magnetic field near the inner surface of the side wall. The plasma processing apparatus according to any one of claims 1 to 7, further comprising a plurality of magnets having polarities.