JPH098010A - Plasma processor - Google Patents

Abstract

PURPOSE: To obtain a plasma processor which can secure high plasma density while keeping uniformity in the plasma density and also suppressing plasma diffusion. CONSTITUTION: A susceptor 6 and an upper electrode 32 are oppositely provided in a processing container 3, while high frequency power of relatively low frequency is applied from a first high frequency power source 41 to the susceptor 6 and high frequency power of relatively high frequency is applied from a second high frequency power source 44 to the upper electrode 32. A circular antenna 52 is placed via an insulator 51 on an outer periphery of the processing container 3, and high frequency power from a third high frequency power source is applied to the antenna 52. A variable magnetic field B is formed by the antenna 52 around a space where the susceptor 6 and the upper electrode 32 are opposite to each other so that plasma diffusion is suppressed, thereby increasing plasma density. The incident energy of ions in the high density plasma into a wafer W is controlled by high frequency having relatively low frequency.

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 performing various types of plasma processing such as etching processing on an object to be processed.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing process, a plasma is generated in a processing container during a process such as a sputtering process or a CVD process including an etching process, and a substrate to be processed, for example, a semiconductor wafer, in the plasma atmosphere. A plasma processing apparatus configured to perform a predetermined process on the surface of a wafer (hereinafter, referred to as “wafer”) is used, but today, the degree of integration of devices is increasing, and improvement of throughput is also very important. Therefore, in these plasma processing apparatuses, not only the improvement of the yield but also the high-speed fine processing is emphasized.

In consideration of this point, for example, an etching apparatus will be described as an example. In a so-called cathode-coupled etching apparatus or anode-coupled etching apparatus that uses high-frequency power for generating plasma, the plasma is configured as it is. In order to increase the density, it is necessary to increase the high frequency power.

However, if the high frequency power is increased in this way, then the incident energy of ions is increased, resulting in damage to the wafer and deterioration of the mask resist.

In order to improve this, Japanese Patent Publication No. 58-123
No. 47 proposes that high frequencies having different frequencies are applied to the upper and lower electrodes, plasma is generated at high frequencies, and the energy of ion incidence is independently controlled at high frequencies.

[0006]

However, in the above-mentioned prior art, there is a limit in improving the plasma density,
When the pressure in the processing container is reduced to carry out finer processing, plasma diffuses into the processing container,
As a result, the desired high-density plasma may not be obtained.

Regarding this point, for example, a parallel magnetic field is formed on the object to be processed, and the configuration of a magnetron RIE apparatus utilizing the magnetron discharge by the orthogonal electromagnetic field formed on the surface of the object is introduced to further increase the plasma density. However, this makes it difficult to ensure the uniformity of the plasma density. Moreover, there still remains the problem of confining the plasma in the processing region in order to suppress the diffusion of the plasma.

The present invention has been made in view of the above problems, and provides a plasma processing apparatus capable of ensuring a high plasma density while suppressing the plasma diffusion while ensuring the uniformity of the plasma density. The purpose is to solve the problem.

[0009]

In order to achieve the above object, a plasma processing apparatus according to a first aspect of the present invention has two electrodes facing each other in a processing container, and plasma is generated in the processing container to generate the electrode. A processing device for performing a plasma treatment on an object to be processed on one of the electrodes, wherein the one electrode outputs high frequency power of a relatively low frequency.
Other high frequency power source, and the other electrode is connected to a second high frequency power source that outputs high frequency high frequency power, and by applying high frequency power, the electrode is formed around the area between the opposing electrodes in the processing container. An antenna for generating a fluctuating magnetic field and confining the plasma is provided.

A plasma processing apparatus according to a second aspect of the present invention changes the application path of the high frequency power to the electrode in the plasma processing apparatus according to the first aspect, and outputs the high frequency power of a relatively low frequency through the mixing device. Both the first high-frequency power source and the second high-frequency power source that outputs high-frequency power of a relatively high frequency are connected to one electrode on which the object to be processed is placed, and the other electrode is grounded. To do.

Further, as described in claim 3, the antenna in each of these plasma processing apparatuses is arranged at a position closer to the other electrode, that is, at a position closer to the other electrode than one electrode. At the same time, if the diameter of this antenna is made larger than the diameters of the other electrodes,
More preferable.

[0012]

According to the plasma processing apparatus of claims 1, 2 and 3, plasma is generated in the processing chamber by the high frequency power from the second high frequency power source which outputs high frequency high frequency power, and the ions in the plasma are contaminated. The incident energy to the processing body can be controlled by the low frequency high frequency power from the first high frequency power supply. In consideration of such an action, the frequency of the first high frequency power source is 1M, which is a frequency that ions can follow, for example, a frequency of the order of several hundred kHz.
Frequencies below Hz are preferred. On the other hand, the frequency of the second high frequency power supply is a frequency for generating high density plasma, such as 13.56 MHz, 27.12 MHz,
Frequencies above 1 MHz are preferred.

The antenna generates a fluctuating magnetic field in the area between the opposing electrodes in the processing container, that is, around the processing area, and the fluctuating magnetic field traps the plasma. As a result, the plasma density in the processing area is reduced. To rise. Further, since the fluctuating magnetic field formed by the high frequency power is formed around the region between the opposed electrodes, the uniformity of the plasma density in the processing region is not affected by the fluctuating magnetic field. Particularly, by setting the arrangement position and size of the antenna as in claim 3, the plasma can be more effectively confined.

As the structure of the antenna, for example, an annular one-turn high-frequency antenna, a multi-turn high-frequency antenna, and a spiral-shaped high-frequency antenna can be proposed. The frequency of the high frequency power applied to this antenna is preferably between the frequency of the first high frequency power supply and the frequency of the second high frequency power supply.

The antenna may be provided outside the processing container or inside the processing container. Normally, this type of processing container is made of a conductive material and is grounded, so in this case, when the antenna is provided outside, only the vicinity of the antenna in the processing container, the insulating material,
For example, it may be made of quartz or the like. Further, the antenna may be arranged at the upper part of the portion corresponding to the top plate of the processing container or on the outer periphery of the side wall of the processing container. In any case, it may be appropriately arranged so that a fluctuating magnetic field can be formed around the area between opposed electrodes.

On the other hand, when the antenna is provided inside the processing container, the outer periphery of the antenna may be covered with an insulating material such as quartz in order to prevent sputtering due to plasma. Further, by appropriately setting the output and frequency of the high frequency power applied to the antenna, it is possible to supplementally increase the plasma density in the processing container.

[0017]

EXAMPLE An example in which the present invention is applied to an etching apparatus will be described below. FIG. 1 schematically shows a cross section of an etching apparatus 1 according to this example. The processing chamber 2 is formed in a cylindrical processing container 3 made of anodized aluminum or the like, and the processing chamber 2 is hermetically closed. The processing vessel 3 itself is grounded, for example, by being connected to a ground wire 4. An insulating support plate 5 made of ceramic or the like is provided at the bottom of the processing chamber 2, and an object to be processed, for example, a semiconductor wafer having a diameter of 12 inches (hereinafter referred to as “wafer”) W is provided on the insulating support plate 5. A substantially columnar susceptor 6 for mounting the is accommodated. The susceptor 6 is made of, for example, anodized aluminum and constitutes a lower electrode.

A refrigerant circulation path 7 through which a refrigerant flows is formed in the susceptor 6, and the refrigerant introduced from the refrigerant introduction pipe 8 circulates in the refrigerant circulation path 7 and a refrigerant discharge pipe 9 is formed.
From the processing container 3. With this configuration, the susceptor 6 and the wafer W can be cooled to a predetermined temperature. At the same time, a heating means such as a ceramic heater is separately provided in the susceptor 6 and controlled by an appropriate temperature sensor,
The heating means may be controlled to control the wafer W at a predetermined temperature together with the action of the coolant circulation path 7.

An electrostatic chuck 11 for attracting and holding the wafer W is provided on the susceptor 6. The electrostatic chuck 11 has a structure in which a conductive thin film 12 is sandwiched between polyimide resin films 13 from above and below, and a high-voltage DC power supply 1 installed outside the processing container 3 is provided.
4 is applied to the thin film 12 with a predetermined DC voltage, for example, a voltage of 1.5 kV to 2 kV, the resin film 13
The wafer W placed on the electrostatic chuck 11 is adsorbed and held on the upper surface of the electrostatic chuck 11 by the Coulomb force based on the electric charges generated above.

In the susceptor 6, there is provided a heat transfer gas introducing pipe 15 penetrating the bottom of the processing container 3 and the insulating support plate 5, and a gas passage 16 penetrating the electrostatic chuck 11.
Is connected to Then, an appropriate heat transfer gas, for example, He (helium) gas supplied from the outside of the processing container 3 is passed through the heat transfer gas introducing pipe 15 and the gas flow path 16 to the back surface of the wafer W held on the electrostatic chuck 11. The heat transfer efficiency between the wafer W and the electrostatic chuck 11, that is, the susceptor 6 is improved.

An annular focus ring 17 is provided around the electrostatic chuck 11 on the outer peripheral edge of the upper surface of the susceptor 6 so as to surround the electrostatic chuck 11. The focus ring 17 has a function of improving the uniformity of plasma density around the wafer W when formed of, for example, conductive single crystal silicon or the like, and is formed of an insulator such as quartz. In this case, it has a function of not attracting ions in the plasma and improving the efficiency of incidence on the wafer W. In consideration of such an action, if the conductive focus ring is arranged inside and the insulating focus ring is arranged around the outer periphery thereof, the uniformity of the plasma density around the wafer W is improved, and The effect of increasing the plasma density on the wafer W is obtained.

A baffle plate 18 having a large number of through holes is arranged around the susceptor 6, and an exhaust port 19 is provided below the baffle plate 18 near the bottom of the processing container 3. The exhaust port 19 is provided and is connected to an exhaust pipe 21 that communicates with a vacuuming means 20 such as a turbo molecular pump. Therefore, the evacuation means 20
By the operation of, the inside of the processing container 3 can be evacuated to a predetermined decompression degree, for example, to 10 mTorr, and in that case, the gas inside the processing container 3 is exhausted through the baffle plate 18, so that the gas can be uniformly discharged. It is possible to exhaust to. Such evacuation of the processing container 3 and maintenance of the degree of pressure reduction in the processing container 3 by the operation of the evacuation means 20 are automatically performed based on a detection signal from a pressure sensor (not shown) provided in the processing container 3. Controlled.

An upper electrode 32 is provided above the processing chamber 2 via an insulating material 31 made of alumina, for example. The upper electrode 32 is made of a conductive material, for example, aluminum that has been subjected to alumite oxide treatment. At least the surface 32a facing the wafer W is made of another conductive material, for example, single crystal silicon. Good. The upper electrode 32 has a hollow portion 32b inside.
And a gas inlet 33 is formed in the upper center of the upper electrode 32, and the gas inlet 33 communicates with the hollow portion 32b. A large number of ejection ports 32c are formed on the surface 32a facing the wafer W.

A gas introduction pipe 34 is provided at the gas introduction port 33.
Is connected to the gas introduction pipe 34, and the valve 3 is connected to the gas introduction pipe 34.
5. A processing gas supply source 37 is connected via a mass flow controller 36 for adjusting the flow rate. In this embodiment, a predetermined processing gas, for example, a CF-based etching gas such as CF ₄ gas or C ₄ F ₈ gas is supplied from the processing gas supply source 47, and the etching gas is a mass flow. The flow rate is adjusted by the controller 36,
The ejection port 32c of the upper electrode 32 is configured to uniformly eject the wafer W.

Next, the high-frequency power supply system of the etching apparatus 1 will be described. First, the susceptor 6 serving as the lower electrode has a frequency of about several hundred kHz, for example, 80.
First high frequency power supply 41 that outputs high frequency power of 0 kHz
Power is supplied from the matching unit 42 having a blocking capacitor or the like. On the other hand, for the upper electrode 32, from the second high frequency power supply 44 that outputs a high frequency power of 1 MHz or higher, for example, 27.12 MHz, whose frequency is higher than that of the first high frequency power supply 41, via the matching unit 43. Is configured to be supplied with power.

A ring-shaped insulating material 51 made of, for example, quartz is disposed on the upper side wall of the processing container 3, and the ring-shaped antenna 52 as shown in FIG. Are arranged. This antenna 52
When the so-called one-turn configuration is used and high-frequency power from the third high-frequency power source 53, for example, high-frequency power having a frequency of 13.56 MHz is applied, as shown in FIG. 1, the space between the upper electrode 32 and the susceptor 6 is increased. A fluctuating magnetic field B according to the frequency is formed around the space.

The main part of the etching apparatus 1 according to this embodiment is constructed as described above, and a wafer transfer means or the like is provided on the side surface of the etching apparatus 1 via, for example, a gate valve (not shown). Load lock chambers (not shown) housed therein are arranged in parallel.

Next, by using the etching apparatus 1 having the above-mentioned structure, for example, an oxide film (SiO ₂ ) of a silicon wafer W is formed.
The process, action, etc. in the case of etching will be described. First, the wafer W as the object to be processed is carried into the processing chamber 2 from the load lock chamber, and the electrostatic chuck 1
When the wafer W is placed on the electrostatic chuck 11, a predetermined voltage is applied from the high-voltage DC power supply 14 to the conductive thin film 12 in the electrostatic chuck 11, and the wafer W is attracted and held on the electrostatic chuck 11.

Next, the inside of the processing chamber 2 is evacuated by the evacuation means 20 to a predetermined degree of vacuum, for example, 10
After reaching mTorr, a predetermined processing gas, for example CF _4, is supplied from the processing gas supply source 37 at a predetermined flow rate ratio, and the pressure in the processing chamber 2 is set and maintained at a predetermined vacuum degree, for example, 20 mTorr.

Next, when a high frequency power having a frequency of 13.56 MHz and a power of, for example, 500 W to 2000 W is applied to the antenna 52 from the third high frequency power supply, as described above, the upper electrode 32, the susceptor 6 and A fluctuating magnetic field B according to the frequency is formed around the space between.

A frequency of 27.12 MHz and a power of 2 k are supplied from the second high frequency power source 44 to the upper electrode 32.
When the high frequency power of W is supplied, plasma is generated between the upper electrode 32 and the susceptor 6. With a slight delay (timing delay of 1 second or less) from this, the frequency from the first high frequency power supply 41 to the susceptor 6 becomes 80%.
High frequency power of 0 kHz and power of 1 kW is supplied.
In this way, by supplying the high frequency power to the susceptor 6 with a timing delayed from the upper electrode 32,
The wafer W can be prevented from being damaged by an excessive voltage.

The plasma generated by the application of the high frequency (27.12 MHz) from the second high frequency power source 44 dissociates the etching gas in the processing chamber 2, that is, the gas molecules of the CF ₄ gas, and the etchant ions generated thereby. However, while the incident speed is controlled by the high frequency (800 kHz) having a relatively low frequency supplied from the first high frequency power supply 41 to the susceptor 6 side, the wafer W
The silicon oxide film (SiO ₂ ) on the surface is etched.

In this case, as described above, the upper electrode 32
Since the fluctuating magnetic field B is formed around the space between the susceptor 6 and the susceptor 6, the fluctuating magnetic field B suppresses the diffusion of the plasma generated between the upper electrode 32 and the susceptor 6. Therefore, the plasma density in the region between the upper electrode 32 and the susceptor 6 is correspondingly high.
Therefore, a high etching rate under high density plasma can be obtained.

Further, since the fluctuating magnetic field B is formed around the space between the upper electrode 32 and the susceptor 6 and has a strength enough to prevent plasma diffusion, the magnetic field on the wafer W is It can be set to almost 0 (zero) and does not affect the uniformity of plasma density. Therefore, the uniformity of the etching process on the wafer W, which is the object to be processed, is extremely good.

Although depending on the strength of the fluctuating magnetic field B, the cycloidal motion of electrons causes collisions with gas molecules at a position orthogonal to the electric field, resulting in the generation of plasma, and the plasma in the processing chamber 2 is auxiliary. Further, the plasma density can be further increased by increasing the density.

In consideration of the action of the fluctuating magnetic field B as described above, the power of the high frequency power applied to the antenna 52 is sufficient if it can form the fluctuating magnetic field B sufficient to suppress the plasma diffusion. Third to generate
The output of the high-frequency power source of 2 may be small. Therefore, the apparatus configuration around the outside of the processing container 3 is not enlarged, and the etching apparatus 1 as a whole is not large-scaled.

The antenna 52 used in the above embodiment is
It had a one-turn ring configuration, but instead of this,
For example, as shown in FIG. 3, an antenna 63 in which annular one-turn antennas 61 and 62 are vertically arranged may be used.

Further, as shown in FIG. 4, an antenna 64 having a spiral antenna member may be used.

In the etching apparatus 1 according to the above embodiment, the antenna 52 for forming the fluctuating magnetic field B is
An annular insulating member 51 disposed on the upper side wall of the processing container 3.
However, not limited to this, as in the etching apparatus 71 according to the second embodiment shown in FIG.
It may be arranged above the portion corresponding to the top plate portion of the processing container 72. In FIG. 5, members designated by the same reference numerals as those in FIG. 1 have the same configurations as the members in the etching apparatus 1 according to the embodiment.

In this etching apparatus 71, a portion corresponding to a top plate of a cylindrical processing container 72 made of aluminum which has been subjected to alumite oxidation treatment is constituted by an insulating plate 73 made of an insulating material such as quartz. On the plate 73, the etching apparatus 1 of the first embodiment described above is provided.
A one-turn substantially annular (loop-shaped) antenna 74 having a similar shape to the antenna 52 in FIG.
4 has a configuration in which a third high frequency power source 53 is connected.

Etching device 7 having such a configuration
Also in the first embodiment, the antenna 74 allows the upper electrode 3
A fluctuating magnetic field that suppresses plasma diffusion is formed around the space between 2 and the susceptor 6, and like the etching apparatus 1 according to the first embodiment, a high-speed and uniform etching rate under high-density plasma. Is obtained.

The etching apparatus 1 according to each of the above embodiments,
In 71, an antenna 5 for forming a fluctuating magnetic field
Although both 2 and 74 are arranged outside the processing container, they may be arranged inside the processing container 82 like the etching apparatus 81 according to the third embodiment shown in FIG. In FIG. 6, members designated by the same reference numerals as those in FIG. 1 have the same configurations as the members in the etching apparatus 1 according to the embodiment.

That is, in the etching apparatus 81 shown in FIG. 6, the upper part of the side wall inside the cylindrical processing container 82 made of aluminum which has been subjected to alumite oxidation treatment has an annular shape covered with an insulating material 83 such as quartz. An antenna 84 is arranged, and the antenna 84 is connected to the third high-frequency power source 53 described above.

According to the etching apparatus 81 having such a structure, the antenna 84 forms a fluctuating magnetic field around the space between the upper electrode 32 and the susceptor 6 to suppress the diffusion of plasma. Similar to the etching apparatus 1, a high speed and uniform etching rate under high density plasma can be obtained. Moreover, in this etching apparatus 81, since the antenna 84 is housed in the processing container 82, the area around the etching apparatus 81 is further simplified.

Further, in each of the above-described embodiments, the first high frequency power source 41 for generating high frequency power of relatively low frequency is connected to the susceptor 6, and the high frequency power of relatively high frequency is generated for the upper electrode 32. Second high frequency power source 44
However, like the etching apparatus 91 according to the fourth embodiment shown in FIG. 7, the first high frequency power source 41 and the second high frequency power source 41 that generate high frequency power of these two different frequencies are connected. Both of the high frequency power supplies 44 may be connected to the susceptor 6. In FIG. 7, members designated by the same reference numerals as those in FIG. 1 have the same configurations as the members in the etching apparatus 1 according to the first embodiment.

That is, in the etching apparatus 91 shown in FIG. 7, the first high frequency power supply 41 and the second high frequency power supply 44 are used.
Both of them are connected to a mixing device 94 via matching devices 92 and 93 each having a built-in filter or the like for preventing mutual interference, and so to speak, two high frequencies of different frequencies are superposed through the mixing device 94. In the shape, it is configured to be applied to the susceptor 6.

Further, in this etching apparatus 91,
The upper electrode 32 is directly fixed to the processing container 3 without an insulating material, and the processing container 3 and the upper electrode grounded by the ground wire 4 have the same potential, that is, the upper electrode 32 is grounded.

Also with the etching apparatus 91 having such a configuration, etchant ions dissociated by the plasma generated by the application of the high frequency (for example, 27.12 MHz) from the second high frequency power source 44 are applied from the first high frequency power source 41. High frequency of low frequency (eg 8
(00 kHz), the surface of the wafer W is etched while the incident speed is controlled. Therefore,
High-speed etching without damage is possible.

Of course, like the etching apparatus 1 according to the first embodiment, since the variable magnetic field is formed around the space between the upper electrode 32 and the susceptor 6 by the antenna 52, the diffusion of the plasma is prevented. Since it is suppressed, a high speed and uniform etching rate can be obtained.

As described above, the antenna for forming the fluctuating magnetic field may have the configuration shown in FIGS. 3 and 4 even if the high-frequency power of two different frequencies is applied to the susceptor 6. Further, the antenna may be arranged at the upper part of the processing container as shown in FIG. 5 or inside the processing container as shown in FIG.

Although each of the above-described embodiments is an example configured as an etching apparatus, the invention is not limited to this.
The present invention can be embodied as another plasma processing apparatus such as an ashing apparatus, a sputtering apparatus, or a CVD apparatus. Further, the object to be processed is not limited to the wafer but may be an LCD substrate.

[0052]

According to the plasma processing apparatus of the first, second, and third aspects, since the diffusion of plasma is prevented by the antenna, various plasma processing is performed on the object to be processed under a high plasma density. You can Further, the uniformity of the plasma density in the processing region is also good, and high-speed and fine processing can be performed without damaging the object to be processed. Further, particularly in the plasma processing apparatus of the third aspect, the plasma can be more effectively confined.

[Brief description of drawings]

FIG. 1 is a sectional explanatory view of an etching apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view of an antenna used in the etching apparatus of FIG.

FIG. 3 is a perspective view of another antenna applicable to the present invention.

FIG. 4 is a perspective view of another antenna (spiral shape) applicable to the present invention.

FIG. 5 is a sectional explanatory view of an etching apparatus according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional explanatory view of an etching apparatus according to a third embodiment of the present invention.

FIG. 7 is a cross-sectional explanatory diagram of an etching apparatus according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Etching apparatus 2 Processing chamber 3 Processing container 6 Susceptor 11 Electrostatic chuck 20 Vacuuming means 32 Upper electrode 37 Processing gas supply source 41 First high frequency power supply 44 Second high frequency power supply 52 Antenna 53 Third high frequency power supply B Fluctuating magnetic field W wafer

Claims (3)

[Claims] 1. Two electrodes are arranged opposite to each other in a processing container,
A processing apparatus for generating plasma in the processing container to perform plasma processing on an object to be processed on one of the electrodes, the one electrode being a high frequency power of a relatively low frequency. Is connected to a first high-frequency power source that outputs a high-frequency power, and the other electrode is connected to a second high-frequency power source that outputs a high-frequency power having a relatively high frequency. A plasma processing apparatus comprising: an antenna for generating a fluctuating magnetic field around the interspace to confine the plasma. 2. The two electrodes are arranged to face each other in the processing container,
A processing apparatus for generating plasma in the processing container to perform processing on an object to be processed on one of the electrodes, wherein the one electrode is relatively moved through a mixing device. It is connected to both a first high-frequency power source that outputs low-frequency high-frequency power and a second high-frequency power source that outputs relatively high-frequency high-frequency power, and the other electrode is grounded, and A plasma processing apparatus, comprising: an antenna for generating a fluctuating magnetic field around an area between opposed electrodes in the processing container to confine the plasma by application. 3. The plasma according to claim 1, wherein the antenna is located on the side of the other electrode, and the antenna has a diameter larger than that of the other electrode. Processing equipment.