JP2001297899A - Plasma processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode structure for forming and controlling uniform high-frequency having a large area, and to provide a plasma processing device which can carry out deposition to a predetermined substrate uniformly using the electrode structure. SOLUTION: In the plasma processing device which generates plasma using the high-frequency discharge in a vacuum container 200 and comprises a high-frequency power source (not shown), the vacuum container 200, an antenna 210 that is installed in the vacuum container 200 and is electrically connected with the high-frequency power source, and a substrate 250 in which a film is formed, the antenna 210 is the antenna that has a Faraday shield 230 having a plurality of conductors provided in the perimeter and a shield short-circuit 220 which is the conductor which short-circuits the Faraday shield 230. By using the antenna, formation and control of the uniform high-frequency discharge plasma covering large area can be performed, and the deposition can be uniformly carried out to a predetermined substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma processing apparatus, and more particularly to a plasma processing apparatus for generating and controlling a large-area and uniform high-frequency discharge plasma.

[0002]

2. Description of the Related Art LSIs (large-scale integrated circuits) assembled by laminating thin films of conductors, semiconductors, and insulators on a substrate made of silicon or the like are used to reduce the size or delay of signals. Today, there is a demand for thinner and finer structures in order to shorten the wiring between components so as to reduce them. Thin film preparation methods can be broadly divided into physical methods and chemical methods. The former is a method in which a substance flying by a vacuum evaporation method or sputtering is deposited on a substrate, and physical vapor deposition (Physical Vapor Deposition, PV
D). In the latter, hydrides and the like are decomposed by some method to form active species, which react and deposit on the substrate surface. Chemical vapor deposition (Chemical Vapor Dep.
osition, CVD). For example, a silicon single crystal film can be manufactured by a CVD method, and SiH ₄
It is created by heating and decomposing (gas) to 900 ° C. or higher to grow crystals. The processing method of generating a film by thermal decomposition is called a thermal CVD method, whereas the processing method of decomposing a gas by discharge plasma to generate a film is called a plasma CVD method.
VD method (Plasma CVD, Plasma-assisted CVD, Plasma-en
hanced CVD). For example, when a discharge is performed to SiH ₄ gas, S generated due to difficult collision with high energy electrons
the active species of the surface reaction such iH _x, it is the silicon thin film. Plasma CVD is a low temperature, dry process
The method is widely used in LSI manufacturing and the like. In order to form a film on a large substrate at high speed by this plasma CVD method, uniform high frequency discharge plasma is generated on the substrate.
It is desired to control. However, the real part of the dielectric constant of the plasma may be negative, and the electromagnetic wave radiated from the antenna rapidly attenuates at a short distance, and it is not always easy to obtain a uniform plasma.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to propose an electrode structure for generating and controlling a large-area and uniform high-frequency discharge plasma, and to uniformly form a film on a predetermined substrate using the same. The purpose of the present invention is to propose a plasma processing apparatus capable of performing the above.

[0004]

In order to achieve the above object, the present invention provides a high-frequency power supply, a vacuum vessel, and an antenna installed in the vacuum vessel and electrically connected to the high-frequency power supply. A plasma processing apparatus using a high-frequency discharge, which is provided in the vacuum vessel and includes a plasma processing target formed by the antenna, wherein the antenna is a single antenna or an antenna array having a Faraday shield. There is a feature. With this configuration, uniform high-frequency discharge plasma can be generated and controlled over a large area. For example, a uniform film can be formed on a predetermined substrate. The Faraday shield includes a plurality of conductors provided around the antenna, and a shield short that is a conductor that electrically shorts the plurality of conductors. By changing the position of the shield / short, etc., a desired uniform electromagnetic field distribution can be obtained, and uniform generation of plasma can be achieved.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention uses a plasma processing apparatus having a plasma generating antenna with a Faraday shield in order to generate and control a large-area and uniform high-frequency discharge plasma. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram of a plasma processing apparatus according to an embodiment of the present invention. Vacuum container 2 for performing CVD processing
00 is vacuum. The vacuum vessel 200 includes a gas inlet 260 for introducing a gas from the outside. An antenna 210 for performing high-frequency discharge to generate plasma is provided inside the vacuum vessel 200. An external high-frequency power supply (not shown) and an antenna 210 are attached and connected to a core wire of a coaxial line 240 for guiding high-frequency power. Inside the vacuum vessel 200, for example, semiconductor substrates 250 are placed on both sides of the antenna 210 in order to form a film using plasma generated by high frequency from the antenna.

[0007] The antenna 210 is provided with a Faraday shield 230 which is constituted by a plurality of ring-shaped conductors and is installed vertically around the antenna 210 so as to surround the antenna 210. This Faraday Shield 2
Reference numeral 30 is supported by a conductor that is a shield short 220 and is electrically short-circuited. After a gas corresponding to a film generated on the semiconductor substrate 250 is externally introduced into the vacuum vessel 200 through the gas inlet 260, high-frequency power is applied to the antenna 21 to generate plasma.
Supply 0. High-frequency power supplied to the antenna is guided from a high-frequency power supply (not shown) to the antenna 210 in the vacuum vessel 200 via the coaxial line 240. The electromagnetic wave is excited by the antenna 210 and the Faraday shield 23
Emitted through 0. The radiated electromagnetic waves interact with gas that has been injected in advance to generate plasma. As a gas to be used, for example, a silane (SiH ₄ ) gas for forming a silicon film is used. The electromagnetic wave radiated from the antenna 210 via the Faraday shield 230 acts on the gas to generate a discharge plasma, and this discharge plasma is several centimeters parallel to the antenna 210.
A predetermined film is formed on the semiconductor substrates 250 arranged on both sides of the semiconductor substrate. Plasma distribution is Faraday Shield 2
By using 30, control can be performed so as to be uniform. This control is performed by the Faraday shield 230
By changing the dimensions and spacing of the ring-shaped conductors and the mounting position of the shield short 220. By making the distribution of plasma uniform, film formation can be performed over a large area. In this embodiment, a folded antenna is used as the antenna 210 in the Faraday shield 230, but another antenna shape or a plurality of such antennas may be arranged.

FIG. 2 shows the configuration of an antenna for generating plasma in the vacuum vessel 200 of FIG. FIG.
As shown in (a), the Faraday shield 230 is composed of a plurality of ring-shaped conductors, and the size, shape, and ring interval can be arbitrarily set. A shield short 220 is provided to support and electrically short these rings. Folded antenna 2
10 is electrically connected to the high-frequency power supply via the coaxial line 240 on the left side of the figure, but the connection relationship with the high-frequency power supply is shown because the coaxial line 240 is omitted in this figure. For this reason, a power supply point 242 is shown using a symbol of an AC power supply at a point intersecting with the vacuum vessel bottom surface 244.

The effects obtained by using the Faraday shield 230 for the plasma generating section generally include the following. (1) Protect the antenna conductor from high-speed particles. (2) Block an electric field component perpendicular to the antenna. (3) The quasi-electrostatic field component is blocked, and only the so-called radiated electromagnetic field component is transmitted. The above effects are also used in the present invention. (4) The distribution can be changed to a smooth distribution over the entire antenna. This is an effect that is mainly useful in the present invention. When the Faraday shield 230 is not provided, the component of the electric field in the axial direction of the antenna (z in FIG.
Component) has a peak having a large peak only in the vicinity of the feeding point 242. However, when the Faraday shield 230 is provided, the distribution can be changed to a smooth distribution over the entire antenna.

FIG. 2B is a cross-sectional view perpendicular to the antenna when the position and the number of the shield shorts 220 are changed. FIG. , (Iii) indicates a short circuit on the power supply side, and (iv) indicates a short circuit on both sides. The effect of the shield short 220 will be described with reference to FIG. Regardless of the position of the four shield shorts,
The short has a role of a reflector for the feeding antenna, and has a function of radiating strongly in the opposite direction of the short conductor in addition to the role of a simple short. Although four shield short positions are shown here, the present invention is not limited to this, and other combinations may be used.

<Embodiment> As a specific embodiment, a configuration of a folded antenna with a Faraday shield as shown in FIG. 3 is shown. As shown in FIGS. 3A and 3B, the antenna 310 is electrically connected to a high-frequency power supply (not shown) at a feeding point 342. This antenna has a vertically provided Faraday shield 330,
A shield short 320 that supports and electrically connects the Faraday shield 330 is included. The total length of the antenna 310 is 1.51 m, and resonates at about 50 MHz in a vacuum. The plasma parameters in this example are plasma frequency: 180 MHz and collision frequency: 5.3 Gs ^-1 . A folded antenna 310 is used as an on-line antenna, and a rectangular ring-shaped conductor is used for a Faraday shield 330 provided perpendicularly to the folded antenna 310 and is supported by a shield short conductor 320. The distance between the shields is 3 cm, which is a dimension surrounding the folded antenna having a diameter of 1 cm at a distance of 1 cm. Each point of y = 3, 4, 5 on the y-axis in FIG. 3B is defined as observation points A, B, and C, and the electric field intensity of the _Ez component of each point will be described later.

FIG. 4 shows the electric field intensity distribution of the _Ez component near the antenna in a vacuum at a working frequency of 50 MHz. In the graph without the Faraday shield shown in FIG. 4A, the electric field _Ez component is concentrated near the feeding portion and the folded portion, and has a non-uniform distribution as a whole. On the other hand, in the graph of FIG. 4B in the case where the Faraday shield is added, the concentration of the electric field near the feeding point is weakened, and a uniform distribution is obtained in the length direction of the antenna. When the observation point is 4 cm away from the Faraday shield, fine vibrations are generated in the electric field, but it is uniform by about 6 cm away, and it is possible to optimize the position where the glass substrate for film formation is installed it can. From the above results, a more uniform electric field intensity distribution can be obtained by optimizing the intervals and dimensions of the ring-shaped conductors of the Faraday shield 330. Similarly, FIG. 5 shows the electric field intensity distribution of the _Ez component near the antenna in the plasma. FIG.
In the graph without the Faraday shield shown in (a), the electric field strength is greatly attenuated as compared with the case of a vacuum. This attenuation is due to the fact that the frequency of 50 MHz is smaller than the plasma frequency and is in a cutoff state. In addition, the electric field _Ez component is concentrated near the feeding portion and the folded portion of the antenna, which is disadvantageous because it may cause local generation of plasma and dielectric breakdown of the antenna conductor. On the other hand, it can be seen that the graph in the case where the Faraday shield is added in FIG. 5B has a distribution close to a uniform shape as in the case of the vacuum. For these reasons, the plasma generation antenna with the Faraday shield, which is one embodiment of the present invention, can generate uniform plasma over a large area in the plasma processing apparatus.

<Another Embodiment> FIG. 6 shows an example in which an antenna for plasma generation according to one embodiment of the present invention is formed into an array, and is similar to the antenna for plasma generation with a Faraday shield shown in FIG. It is an array model. In this way, the Faraday /
By using a plurality of shielded plasma generation antennas, plasma can be generated over a larger area. At this time, the combination such as the distance between the antennas, the position of the shield short-circuit, the distance between the conductor rings of the Faraday shield, and the like can be changed.

[0014]

According to the present invention, an apparatus for generating and controlling a uniform high-frequency discharge plasma over a large area and a plasma processing apparatus having a plasma generating antenna with a Faraday shield as a method have been proposed. Furthermore, a method for generating a uniform plasma over a large area by changing the size of the shield and the position of the shield short was shown.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an antenna according to the present invention.

FIG. 3 is a diagram showing a configuration of an antenna according to an embodiment of the present invention.

FIG. 4 is a graph showing an electric field intensity distribution of an _Ez component near an antenna in a vacuum.

FIG. 5 is a graph showing an electric field intensity distribution of an _Ez component near an antenna in plasma.

FIG. 6 is a diagram showing an example of a configuration in which antennas are arrayed.

[Explanation of symbols]

 200 Vacuum container 210 Antenna 220 Shield short 230 Faraday shield 240 Coaxial line 242 Feed point 244 Vacuum container bottom 250 Semiconductor substrate 260 Gas inlet 310 Antenna 320 Shield short 330 Faraday shield 342 Feed point

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G075 AA24 BC01 BC04 CA25 CA47 4K030 AA06 BA29 CA04 FA04 KA30 KA45 LA15 5F004 BA20 BB11 BC08 BD04 5F045 AA08 AC01 AD13 BB02 DP11 EH02 EH04 EH06

Claims (2)

[Claims] A high-frequency power supply, a vacuum vessel, an antenna installed in the vacuum vessel, and electrically coupled to the high-frequency power supply, and a plasma formed in the vacuum vessel and formed by the antenna. A plasma processing apparatus using a high-frequency discharge including a processing target, wherein the antenna is a single antenna or an antenna array having a Faraday shield. 2. The plasma processing apparatus according to claim 1, wherein the Faraday shield includes a plurality of conductors provided around the antenna, and a shield short that is a conductor that electrically shorts the plurality of conductors. A plasma processing apparatus comprising: