JP3077009B2 - Plasma processing equipment - Google Patents

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 a predetermined process using plasma.

[0002]

2. Description of the Related Art In the manufacture of semiconductor integrated circuits, for example, plasma is used in various processes such as ashing, etching, CVD, and sputtering to promote the ionization and chemical reaction of a processing gas. Conventionally,
As a method of generating this kind of plasma, a high-frequency induction method using a spiral antenna is known. This high-frequency induction system is described in, for example, European Patent Publication No. 37
As described in Japanese Patent No. 9828, one surface (generally, the upper surface) of a chamber opposed to a wafer mounting table is formed of an insulating material such as quartz glass, and a spiral antenna is fixed to an outer wall surface thereof. A high-frequency electromagnetic field is generated in the chamber by flowing an electric current, and electrons flowing in the electromagnetic field space collide with neutral particles of the processing gas to ionize the gas and generate plasma.

[0003]

In the above-described plasma processing apparatus using the high-frequency induction system, plasma is generated in the space in the chamber immediately below the spiral antenna. The generation density of this plasma is proportional to the electric field strength at each position,
The plasma density is highest at a position corresponding to the middle part of the spiral antenna in the radial direction, and the plasma density becomes lower toward the inside and outside. Since the plasma generated with a non-uniform density distribution in the radial direction is diffused from the high-density region to the low-density region, the plasma density is considerably leveled near the lower semiconductor wafer. However, in the conventional plasma processing apparatus of this type, the plasma density near the center of the wafer on the surface (processed surface) of the semiconductor wafer is higher than the plasma density near the outer peripheral edge of the wafer due to the radial diffusion of the plasma. Therefore, there is a problem that it is difficult to obtain uniformity and reproducibility of the plasma processing.

The present invention has been made in view of the above problems, and in a high frequency induction system using a spiral high frequency antenna, the plasma density near the surface to be processed of the object to be processed is made uniform, and the uniformity of the plasma processing is improved. An object of the present invention is to provide a plasma processing apparatus capable of obtaining reproducibility.

[0005]

According to a first aspect of the present invention, there is provided a plasma processing apparatus for performing a predetermined process using a plasma on an object to be processed disposed in a chamber. In the apparatus, a high-frequency antenna including a spiral coil disposed outside the chamber so as to face a processing surface of the processing target in the chamber, and a paramagnetic metal disposed so as to overlap a part of the high-frequency antenna And a plate made of:

In order to achieve the above object, a second plasma processing apparatus according to the present invention is directed to a plasma processing apparatus for performing a predetermined process using plasma on an object to be processed disposed in a chamber. A central portion disposed outside the chamber facing the surface of the object to be processed in the chamber is opened with a diameter corresponding to the diameter of the object to be processed , and a coil portion is formed in a ring-shaped space around the central portion. Is provided with a high-frequency antenna formed of a ring-shaped spiral coil formed by the above method.

In order to achieve the above object, a third plasma processing apparatus according to the present invention is a plasma processing apparatus for performing a predetermined process using plasma on an object to be processed disposed in a chamber. A center disposed outside the chamber so as to face a processing surface of the processing target in the chamber;
Open the part with the desired diameter and place it in the ring-shaped space around it.
A first high-frequency antenna comprising a ring-shaped spiral coil having a coil portion formed thereon, first high-frequency power supply means for supplying a first high-frequency power to the first high-frequency antenna, And a second high-frequency power supply means for supplying a second high-frequency power to the second high-frequency antenna.

[0008]

In the first plasma processing apparatus, a plate made of paramagnetic metal disposed so as to overlap a part of the high-frequency antenna (for example, the center of the antenna) acts so as to weaken the penetration of magnetic flux. The alternating electric field is weakened at the position of the space in the chamber corresponding to the body, and the plasma generation density is also reduced. By changing the shape, size and arrangement of the paramagnetic metal plate, the plasma generation region is corrected or adjusted, and the plasma near the surface of the object to be processed is diffused through the diffusion of the plasma from the plasma generation region to the surroundings. The density can be made uniform.

[0009] In the second plasma processing apparatus, by spiral antenna is formed in a ring shape, the field strength of the alternating electric field the number of magnetic flux passing through the antenna center is reduced, is induced electromotive just below its And the plasma generation region is displaced outward in the radial direction. Thus, the plasma density in the vicinity of the surface of the object to be processed can be made uniform through diffusion of the plasma from the plasma generation region to the surroundings.

In the third plasma processing apparatus, the first and second high-frequency power supply means supply independent first and second high-frequency powers to the first and second spiral high-frequency antennas, respectively. The plasma generation region in the chamber space can be arbitrarily adjusted or controlled in the radial direction. Therefore, the plasma density in the vicinity of the surface of the object to be processed can be made uniform through diffusion of the plasma from the plasma generation region to the surroundings.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. 1 and 2 are a perspective view and a schematic sectional view schematically showing the configuration of a plasma processing apparatus according to one embodiment of the present invention.

As shown in FIG. 1, a chamber 10 of this plasma processing apparatus is a cylindrical closed container whose bottom and side surfaces are made of aluminum, and whose top surface is made of quartz glass 12. A disk-shaped or column-shaped mounting table 14 is disposed at the center of the bottom surface of the chamber 10, and a semiconductor wafer W is mounted on the mounting table 14 as an object to be processed. When the present plasma processing apparatus is configured as an etching apparatus, a high frequency power supply 18 for etching at 13.56 MHz, for example, is connected to the mounting table 14 via a tuning capacitor 16. Cooling water is supplied into the mounting table 14 from a cooling water supply unit (not shown) to prevent heating by high frequency.

A gas inlet 10a is provided on the upper side of the chamber 10, and a gas supply pipe 20 is connected to the gas inlet 12b. Chamber 1 from gas supply pipe 20
The processing gas supplied in the chamber varies depending on the type of processing. For example, in the case of etching processing, CHF3 or CF is used.
An etching gas such as 4 is supplied. In the illustrated example, 1
Although only the gas supply pipes 20 are shown, a number of gas supply pipes corresponding to the type of the processing gas may be connected to the chamber 10.

A gas outlet 10b is provided at a lower portion of the side surface of the chamber 10, and a gas exhaust pipe 22 is connected to the gas outlet 10b. The gas exhaust pipe 22 is connected to a vacuum pump (not shown) so that the inside of the chamber 10 is exhausted to a predetermined degree of vacuum.

A high frequency antenna 24 composed of a spiral coil is fixed to the outer surface of the quartz glass 12 on the upper surface of the chamber, facing the semiconductor wafer W mounted on the mounting table 14 in the chamber 10. Both terminals (inner terminal 24a and outer terminal 24b) of this spiral antenna 24
In between, a high frequency voltage of, for example, 13.56 MHz is applied from a high frequency power supply 28 for plasma generation via a matching circuit 26. As a result, the high-frequency current iRF flows through the antenna 24, and plasma is generated in the space in the chamber immediately below the antenna 24 as described later.

In this embodiment, the spiral antenna 24
A circular thin plate 30 made of a paramagnetic metal, for example, copper, is inserted between the center of the glass plate and the quartz glass 12. The diameter of the circular thin plate 30 depends on the shape and dimensions of the antenna 24, the output power of the high frequency power supply 28, the diameter of the semiconductor wafer W, the antenna 24
The predetermined diameter is selected according to the distance between the wafer W and the like. As described later, the plasma generation region (density distribution) in the space in the chamber immediately below the antenna 24 is corrected or adjusted by the copper plate 30 so that the plasma density is made uniform near the surface of the semiconductor wafer W through the diffusion of the plasma. Has become.

Next, the operation of plasma generation and plasma processing in the plasma processing apparatus of this embodiment will be described with reference to FIG. The semiconductor wafer W to be processed is placed on the mounting table 1
4, the inside of the chamber 10 is evacuated to a predetermined degree of vacuum through an exhaust pipe 22, and a predetermined processing gas is supplied from the gas supply pipe 20 into the chamber at a predetermined pressure and flow rate. A high frequency voltage from a high frequency power supply 28 is applied to the spiral antenna 24.

When a high-frequency current iRF flows through the spiral antenna 24 due to the application of the high-frequency voltage, an alternating magnetic field is generated around the antenna conductor, and most of the magnetic flux B passes through the center of the antenna in the vertical direction to form a closed loop. I do. Such circumferential alternating electric field E substantially concentrically immediately below the antenna 24 by an alternating magnetic field B is induced electromotive collision electrons accelerated in the circumferential direction in the neutral particles of the process gas by the alternating electric field E By doing so, the gas is ionized and plasma is generated.

The plasma generated immediately below the antenna 24 has the highest density at a position corresponding to the intermediate portion of the antenna 24 in the radial direction as schematically shown in FIG. The density decreases as going toward. In this embodiment, an eddy current flows in the copper plate 30 so as to prevent the penetration of the magnetic flux B. Therefore, the magnetic flux B hardly passes through the center of the antenna, and the magnetic flux B is located outside the magnetic flux B ′ indicated by the dotted line when the copper plate 30 is not provided. Pass. For this reason, the plasma generation region P immediately below the antenna is displaced radially outward from the plasma generation region P ′ indicated by the dotted line when there is no copper plate 30. Then, as a result of the plasma diffusing in the radial direction and the downward direction, as shown conceptually by a straight line Pd, the plasma density becomes substantially constant in the radial direction near the surface of the semiconductor wafer W mounted on the mounting table 14. You.

Therefore, the ions contained in the plasma,
Electrons and other active species are uniformly supplied or irradiated over the entire surface of the semiconductor wafer W, and a predetermined plasma process is performed uniformly over the entire wafer surface. For example, in plasma etching, gas molecules excited into an active state by plasma chemically react with a material to be processed on a wafer surface to vaporize a reaction product, and the wafer surface is scraped off. Plasma CV
In D, gas molecules excited into an active state by the plasma react with each other, and a solid reaction product is deposited on the wafer surface to form a film. In any plasma processing, in the plasma processing apparatus of the present invention, since the plasma acts on the entire surface of the semiconductor wafer W at a uniform density, the plasma processing is performed uniformly on the wafer surface.

In FIG. 2, a curve Pd 'indicated by a dotted line is shown.
Is a plasma density distribution in the radial direction near the surface of the semiconductor wafer W when the copper plate 30 is not provided. In this case, since the plasma density near the center of the wafer is higher than the plasma density near the outer peripheral edge of the wafer, uneven processing is performed on the wafer surface.

As described above, in the plasma processing apparatus of the present embodiment, the thin plate 30 made of paramagnetic metal is disposed near the center of the spiral antenna 24 so that the plasma generation region P immediately below the antenna is radially outward. Displaced to
As a result, the plasma density is made uniform on the surface (the surface to be processed) of the semiconductor wafer W, so that the wafer W can be subjected to uniform and reproducible plasma processing.

Although a preferred embodiment has been described above, the present invention is not limited to the above-described embodiment, and various modifications and changes can be made within the scope of the technical idea. For example, even if the antenna 24 is modified to the configuration shown in FIGS. 3 to 7, the same or similar operation and effect as described above can be obtained.

The modified example shown in FIG.
In FIG. 4, the antenna 24 is formed in a ring-shaped space by omitting the antenna conductor at the center of the antenna , and the paramagnetic metal thin plate 30 is arranged at the center opening. The diameter of the central opening is selected to be an appropriate diameter according to the number of spirals (number of turns) of the antenna 24, the output power of the high-frequency power supply 28, the diameter of the semiconductor wafer W, the distance between the antenna 24 and the wafer W, and the like.

The modification shown in FIG. 4 is obtained by removing the paramagnetic metal sheet 30 from the modification shown in FIG. Diameter R of the antenna central opening in this case, the action of the paramagnetic metal sheet 30 is internally divided, it becomes larger than the diameter in the case of FIG. 3, for example, be chosen diameter corresponding to the diameter of the semiconductor wafer W.
As described above, even when the high-frequency antenna 24 is configured by a ring-shaped spiral coil formed by opening a center portion with an appropriate diameter and forming a coil portion in a ring-shaped space around the center portion,
Since the number of magnetic flux passing through the antenna center in the vertical direction is reduced, just below the field strength of the alternating electric field is reduced to be induced electromotive in that the plasma generation region P is displaced outward in the radial direction. Thereby, the same effect as in the above embodiment can be obtained.

The modified example shown in FIG.
4 is divided into two in the radial direction, and an independent high-frequency current flows through each of them. The outer high-frequency antenna 24A has a ring-shaped vortex similar to that shown in FIG.
A first high-frequency power supply 28A is connected between the inner terminal 24Aa and the outer terminal 24Ab via a matching circuit or a tuning circuit 26A. The inner high-frequency antenna 24B is composed of a spiral coil having an outer diameter smaller than the inner diameter of the outer high-frequency antenna 24A, and its inner terminal 24Ba and outer terminal 24Bb.
And a matching circuit or tuning circuit 2
The second high frequency power supply 28B is connected via 6B.

First and second high frequency power supplies 28A, 28
B supplies independent first and second high-frequency powers to the outer and inner high-frequency antennas 24A and 24B at the same frequency (for example, 13.56 MHz) and in the same phase. When applied to the plasma processing apparatus of FIGS. 1 and 2, the second high frequency power is selected to be lower than the first high frequency power. Thus, a relatively large high-frequency current iARF flows through the outer high-frequency antenna 24A, and a relatively small high-frequency current iBRF flows through the inner high-frequency antenna 24B. Also in this case, the plasma generation region P in the space in the chamber immediately below the antenna is shifted to the outside of the plasma generation region P 'when the same high-frequency current iRF flows through the single spiral antenna 24. The same effect as the example can be obtained.

Further, in the configuration example shown in FIG. 5, since the high-frequency power can be set independently at the central portion and the outer peripheral portion of the spiral antenna, the plasma generation region can be controlled more precisely and over a wide range. The high-frequency power supply and both antennas 24
A, 24B, a first power distribution circuit
It is also possible to share the second high-frequency power supply 28A, 28B with one high-frequency power supply.

As shown in FIG. 6, each of the outer spiral antenna 24A and the inner spiral antenna 24B has an arbitrary spiral shape and an arbitrary number of spirals (number of turns) independently of each other. It is possible.

In the configuration example shown in FIG. 7, in a single spiral antenna 24, the spiral density (pitch) of the antenna conductor is changed in the radial direction. Part) is sparsely wound. According to such a spiral structure, the concentric alternating electric field that is induced electromotive directly under the antenna is reduced at a relatively inner peripheral portion (central portion), the plasma generation region is also shifted radially outward, the above-described The same effect as the example can be obtained.

In the present invention, the spiral coil (conductor) constituting the high-frequency antenna may have any shape such as a plate, a rod, or a tube, and the conductor diameter (thickness) may not be constant. Alternatively, a hollow pipe may be used, and a cooling medium may flow through the pipe to cool the pipe. Further, the plate body made of a paramagnetic metal according to the present invention may be arranged at a place other than the center of the antenna, or may be arranged at a plurality of places (for example, the center of the antenna and the outer periphery of the antenna) as needed. . Further, the plate made of a paramagnetic metal according to the present invention may be arranged so as to overlap the antenna.

In the above embodiment, quartz glass is provided between the antenna and the processing chamber. However, instead of this, another insulator such as ceramics or high-resistance SiC may be used. It is.

FIG. 8 is a view showing an example of a structure in which the shower head 34 is mounted on the upper surface of the chamber 10, and FIG.
Is a schematic perspective view, (B) is a bottom view, and (C) is a schematic sectional view. The shower head 34 is made of, for example, ceramics, has a gas inlet 34a and a buffer chamber 34b inside, and has many vents 34c on the back surface. The gas supply pipe 20 is connected to the gas inlet 34a. Gas inlet 3
The processing gas introduced from 4c into the buffer chamber 34b is once blocked there and then discharged or injected into the lower processing chamber at a uniform pressure and flow rate from each vent hole 34c.

Further, the present invention is not limited to a plasma etching apparatus and a plasma CVD apparatus.
The present invention is also applicable to other plasma processing apparatuses such as a plasma sputtering apparatus and a plasma ashing apparatus, and the object to be processed is not limited to a semiconductor wafer, but may be an LCD substrate or another object to be processed.

[0035]

As described above, according to the first plasma processing apparatus of the present invention, a plate made of paramagnetic metal for weakening the penetration of magnetic flux is disposed so as to overlap a part of the spiral high-frequency antenna. As a result, the plasma generation region in the chamber can be arbitrarily adjusted or controlled, so that the plasma density near the surface to be processed of the object to be processed is made uniform through the diffusion of the plasma, thereby performing uniform and reproducible plasma processing. Can be.

According to the second plasma processing apparatus of the present invention, the spiral antenna is formed in a ring shape to reduce the number of magnetic fluxes penetrating through the central portion of the antenna, and the radial direction of the plasma generation region in the chamber is reduced. Since it is displaced outward, it is possible to make the plasma density in the vicinity of the processing surface of the processing object uniform through the diffusion of the plasma, and to perform a uniform and reproducible plasma processing.

According to the third plasma processing apparatus of the present invention, the first and second high-frequency powers independent of the first and second high-frequency power supply means are supplied to the first and second spiral high-frequency antennas, respectively. By supplying, it is possible to arbitrarily adjust or control the plasma generation region in the chamber space in the radial direction, so that the plasma density in the vicinity of the surface of the object to be processed can be made uniform through plasma diffusion. Thus, uniform and reproducible plasma processing can be performed.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of a plasma processing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view illustrating a configuration of a plasma processing apparatus according to an embodiment.

FIG. 3 is a schematic plan view showing a configuration of a high-frequency antenna according to a modification and an arrangement configuration of a plate made of paramagnetic metal.

FIG. 4 is a schematic plan view showing a configuration of a high-frequency antenna according to another modification.

FIG. 5 is a schematic plan view showing a configuration of a high-frequency antenna according to another modification.

FIG. 6 is a schematic plan view showing a configuration of a high-frequency antenna according to another modification.

FIG. 7 is a schematic plan view showing a configuration of a high-frequency antenna according to another modification.

FIG. 8 is a diagram showing another configuration example of the processing gas introduction unit in the plasma processing apparatus of the embodiment.

[Explanation of symbols]

 Reference Signs List 10 chamber 12 quartz glass 14 mounting table 18, 18A, 18B high frequency power supply 24, 24A, 24B spiral antenna

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification code FI H05H 1/46 H01L 21/302 B (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 16/00-16 / 56 C23F 4/00-4/04 H01L 21/205 H01L 21/3065 H01L 21/31 H01Q 9/27 H05H 1/46

Claims (7)

(57) [Claims] 1. A plasma processing apparatus for performing a predetermined process using plasma on a processing target disposed in a chamber, wherein the processing target is disposed outside the chamber opposite to a processing target surface of the processing target in the chamber. A plasma processing apparatus, comprising: a high-frequency antenna including a spiral coil disposed therein; and a plate made of a paramagnetic metal disposed so as to overlap a part of the high-frequency antenna. 2. A plate made of paramagnetic metal is circular.
The plasma processing apparatus according to claim 1, wherein
Place. 3. The high-peripheral plate body made of the paramagnetic metal.
Be placed so as to overlap the center of the wave antenna.
The plasma processing according to claim 1 or 2, wherein
apparatus. 4. A plasma processing apparatus for performing a predetermined process using plasma on a processing target disposed in a chamber, wherein the processing target is disposed outside the chamber opposite to a processing target surface of the processing target in the chamber. The placed central part is the object to be processed.
A plasma processing apparatus comprising: a high-frequency antenna comprising a ring-shaped spiral coil having an opening having a diameter corresponding to the diameter of a coil formed in a ring-shaped space around the opening. 5. An object to be processed placed in a chamber is
In a plasma processing apparatus that performs a predetermined process using a zuma
And facing the surface to be processed of the object to be processed in the chamber.
Open the center part outside the chamber to the desired diameter.
Do not form a coil in the ring-shaped space around the
First high-frequency antenna comprising a ring-shaped spiral coil
And supplying a first high-frequency power to the first high-frequency antenna.
A first high-frequency power supply means disposed radially inside the first high-frequency antenna.
Second high-frequency antenna comprising a spiral coil placed
And supplying the second high frequency power to the second high frequency antenna.
And second high frequency power supply means.
Plasma processing equipment. 6. A spiral coil of the first high-frequency antenna.
And the spiral coil of the second high-frequency antenna
Contractors with independent spiral shapes or number of spirals
The plasma device according to claim 5. 7. A spiral coil of the second high-frequency antenna.
Is characterized by having substantially one spiral number
The plasma device according to claim 5.