JPH09232282A - Apparatus and method for plasma treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a plasma treatment apparatus which restrains a sputtering operation from being generated especially near the center and whose maintenance frequency is lowered by a method wherein the inside wall surface of a dielectric plate is formed as a plane and a spiral discharge coil is constituted in such a way that the distance between it and the inner wall surface of the dielectric plate is large when the coil is closer to the center. SOLUTION: The upper wall of a vacuum container 1 is constituted of a dielectric plate 3 composed of quartz glass. A dome-shaped spiral discharge coil 4 is arranged along the outer wall surface of the dielectric plate 3. While a mixed gas of C4 F8 and H2 is being introduced into the vacuum container 1 from a gas supply port 7, it is evacuated from a gas evacuation port 8, and a pressure inside the vacuum container 1 is kept at 10mTorr. At this time, a high-frequency voltage at 1000W is applied to the dome-shaped spiral discharge coil 4 from a high-frequency power supply 2, and a plasma is generated inside the vacuum container 1. Thereby, a silicon substrate 6 which is placed on an electrode 5 can be etched.

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 and method such as dry etching, sputtering and plasma CVD, and more particularly to a high frequency floating type plasma processing apparatus and plasma processing method.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductor elements, in order to realize high aspect ratio processing in dry etching technology and in order to realize high aspect ratio embedding in plasma CVD technology, It is required to perform plasma treatment in a high vacuum.

For example, in the case of dry etching, when high density plasma is generated in a high vacuum, the probability that the ions collide with neutral gas particles in the ion sheath formed on the surface of the substrate to be processed. Is smaller, the directionality of the ions is aligned in the direction perpendicular to the surface of the object to be processed. Further, since the ionization degree of the processing gas is high, the ratio of the ion incident particle flux reaching the substrate to the neutral radicals becomes large. Therefore, the etching anisotropy is enhanced, and processing with a high aspect ratio becomes possible.

In the case of plasma CVD,
When high-density plasma is generated in a high vacuum, a fine pattern can be embedded / planarized by the sputtering effect of ions, and high aspect ratio burying becomes possible.

As one of plasma processing apparatuses capable of generating high density plasma in a high vacuum, a high frequency induction type plasma is generated in a vacuum vessel by applying a high frequency voltage to a planar spiral discharge coil. There is a processing device. This type of plasma processing device
A high-frequency magnetic field is generated in the vacuum container, an induction electric field is generated in the vacuum container to accelerate electrons, and plasma is generated.If the discharge coil current is increased, high density is achieved even in high vacuum. Plasma can be generated and a sufficient processing speed can be obtained.

An example of a conventional high frequency induction type plasma processing apparatus is shown in FIG. FIG. 4 shows a cross section of a conventional plasma processing apparatus. The upper wall of the vacuum container 1 is composed of a dielectric plate 3 made of quartz glass. A planar spiral discharge coil 9 shown in the plan view of FIG. 5 is arranged on the dielectric plate 3. In order to apply a high frequency voltage to the planar vortex discharge coil 9, the center of the planar vortex discharge coil 9, point A, is connected to the high frequency power supply 2, and the other end of the planar vortex discharge coil 9 is connected. , Point B is grounded.

While introducing the processing gas into the vacuum container 1 through the gas supply port 7, the gas is exhausted through the gas exhaust port 8 to maintain the inside of the vacuum container 1 at an appropriate pressure. At this time, when a high-frequency voltage is applied to the planar vortex discharge coil 9, plasma is generated in the vacuum container 1, and the silicon substrate 6 placed on the electrode 5 is subjected to plasma treatment such as etching, deposition, and surface modification. It can be performed. At this time, the high frequency power source 2 is used to
By applying a high frequency voltage to the silicon substrate 6
Can be controlled.

[0008]

However, in the conventional plasma processing method shown in FIG. 4, the inner wall surface of the dielectric plate is sputtered in the vicinity of the center, and the substance forming the dielectric plate 3 is deposited on the substrate 6. There are problems that the dielectric plate 3 falls down and is taken in as impurities on the surface of the substrate 6, and that the life of the dielectric plate 3 is short. This is because the amplitude of the high-frequency voltage applied to the planar vortex discharge coil 9 arranged on the dielectric plate 3 is larger toward the center of the planar vortex discharge coil 9, and the inner wall surface of the dielectric plate 3 is near the center. Is greatly negatively charged.

As a method for avoiding this problem, as shown in FIG. 6, the dielectric plate 3 is thickened in the vicinity of its center so that the distance between the planar vortex discharge coil 9 and the inner wall surface of the dielectric plate 3 becomes equal to the planar vortex. It has been considered that by increasing the size near the center of the shape discharge coil 9, the negative charge generated particularly near the center of the inner wall surface of the dielectric plate 3 is alleviated. However, in such a structure, the inner wall surface of the dielectric plate 3 has a corner. The deposit due to the processing gas that adheres to the dielectric plate 3 is peeled off when the film thickness exceeds a certain level and contaminates the substrate 6, but at the stage where the film thickness is smaller at the corners than at the flat surface,
The deposit will come off. Therefore, in the dielectric plate 3 having the corners, there is a problem that the maintenance for removing the deposits is performed more frequently. In addition, since the shape of the inner wall surface of the dielectric plate 3 is complicated, the efficiency of maintenance work is low.

In view of the above-mentioned conventional problems, the present invention suppresses the sputtering that particularly occurs near the center of the inner wall surface of the dielectric plate 3, has a low maintenance frequency, and is excellent in the efficiency of maintenance work. And to provide a method.

[0011]

In order to solve the above problems, in the present invention, in the plasma processing apparatus, the inner wall surface of the dielectric plate constituting the upper wall of the vacuum container is a flat surface and is provided outside the dielectric plate. The vortex discharge coil has a structure in which the closer it is to the center, the greater the distance from the inner wall surface of the dielectric plate (hereinafter, dome-shaped vortex discharge coil). This can prevent the vicinity of the center of the inner wall surface of the dielectric plate from being particularly sputtered.

Further, since the inner wall surface of the dielectric plate is flat, it is possible to provide a plasma processing apparatus and method in which the frequency of maintenance work for removing deposits on the dielectric plate is low and the maintenance work efficiency is excellent. Becomes

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a vacuum container having an upper wall made of a dielectric plate, a dome-shaped vortex discharge coil provided outside the dielectric plate, and the vortex shape. The plasma processing apparatus includes a high-frequency power source for applying a high-frequency voltage to the center of the discharge coil. The inner wall surface of the dielectric plate is a flat surface.

According to the present invention, among the inner wall surfaces of the dielectric plate,
In particular, it is possible to prevent the vicinity of the center from being sputtered. Also, since the inner wall surface of the dielectric plate is flat,
It is possible to provide a plasma processing apparatus in which the frequency of maintenance work for removing deposits on the dielectric plate is low and the maintenance work is highly efficient.

According to a second aspect of the present invention, the upper wall is a vacuum vessel having a dielectric plate, a dome-shaped spiral discharge coil provided outside the dielectric plate, and a center of the spiral discharge coil. And a high frequency power source for applying a high frequency voltage to the plasma processing method, wherein the inner wall surface of the dielectric plate is a flat surface.

According to the present invention, among the inner wall surfaces of the dielectric plate,
In particular, it is possible to prevent the vicinity of the center from being sputtered. Also, since the inner wall surface of the dielectric plate is flat,
The frequency of maintenance work for removing deposits on the dielectric plate is low, and plasma processing with excellent maintenance work efficiency is possible.

According to a third aspect of the present invention, there is provided a plasma processing apparatus in which a part or all of the vortex discharge coil is composed of multiple vortex discharge coils.

According to the present invention, since the inductance of the spiral discharge coil is extremely small, it is possible to provide a plasma processing apparatus having excellent matching characteristics between the high frequency power supply and the spiral discharge coil.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 shows a sectional view of a plasma processing apparatus according to an embodiment of the present invention. The upper wall of the vacuum container 1 is composed of a dielectric plate 3 made of quartz glass. Along the outer wall surface of this dielectric plate 3, a dome-shaped spiral discharge coil 4 is formed.
Is arranged. This dome-shaped vortex discharge coil 4 is shown in FIG.
As shown in FIG. 5, it is composed of multiple, that is, four dome-shaped spiral discharge coils. In order to apply a high-frequency voltage to these four dome-shaped vortex discharge coils 4, the center of each dome-shaped vortex-shaped discharge coil 4, point A, is connected to the high-frequency power supply 2, and the dome-shaped vortex-shaped discharge coil 4 is also connected. The other end of each of points 4, points B1 to B4, is grounded.

In FIG. 1, C ₄ F ₈ and H are supplied from the gas supply port 7.
While introducing the mixed gas of ₂ into the vacuum container 1, the gas is exhausted from the gas exhaust port 8 to adjust the pressure in the vacuum container 1 to 10 mTo
rr. At this time, a high-frequency voltage of 1000 W is applied to the dome-shaped spiral discharge coil 4 from the high-frequency power source 2 to generate plasma in the vacuum container 1, and the silicon substrate 6 placed on the electrode 5 is etched. be able to. At this time, by applying a high-frequency voltage of 300 W to the electrode 5 using the high-frequency power source 2, the ion energy reaching the silicon substrate 6 can be controlled. The flow rates of C ₄ F ₈ and H ₂ are 50 sccm and 1 respectively.
It is 5 sccm.

Under this condition, 100 silicon substrates 6 each having a silicon oxide film with a thickness of 500 nm were continuously etched for about 1 minute and 30 seconds. For comparison, an experiment was conducted using the conventional plasma processing apparatus shown in FIGS. 4 and 6. As a result, near the center of the inner wall surface of the dielectric plate 3 is sputtered in the conventional plasma processing apparatus shown in FIG. 4, and adheres to the inner wall surface of the dielectric plate 3 in the conventional plasma processing apparatus shown in FIG. While the fluorocarbon-based polymer that is a deposit dropped and adhered onto the silicon substrate 6, in the plasma processing apparatus of the present invention, the sputtering of the dielectric plate 3 and the silicon substrate 6 were performed.
No fall of deposits was observed.

In the present embodiment, multiple dome-shaped vortex discharge coils 9 are used as the dome-shaped vortex discharge coil 4, but a partially multiple dome as shown in FIG. 3 (a) or 3 (b) is used. A spiral vortex discharge coil or a single dome-shaped vortex discharge coil that is not multiple, that is, the dome-shaped planar vortex discharge coil 9 shown in FIG. 5 may be used.

Further, in the present embodiment, the method of supporting the dome-shaped vortex discharge coil 4 by the dielectric plate 3 having an outer wall having a dome shape is shown. However, the inner wall surface of the dielectric plate 3 is a flat surface and the vortex discharge is formed. If the coil has a dome shape, the effect of the present invention can be obtained. Therefore, for example, the dielectric plate 3 may have a structure in which both the inner wall surface and the outer wall surface are flat and the dome-shaped spiral discharge coil 4 is suspended from above.

[0024]

As described above, according to the present invention, in the plasma processing apparatus, the inner wall surface of the dielectric plate constituting the upper wall of the vacuum vessel is a flat surface, and the spiral discharge coil provided outside the dielectric plate has a dome shape. By doing so, it is possible to prevent the center portion of the inner wall surface of the dielectric plate from being particularly sputtered.

Further, since there are no corners on the inner wall surface of the dielectric plate, the adhered deposits are less likely to be peeled off, and the frequency of maintenance work for removing the deposits on the dielectric plate is low. Furthermore, since the inner wall surface of the dielectric plate is flat, it also has the effect of being highly efficient in maintenance work.

[Brief description of drawings]

FIG. 1 is a sectional view of a plasma processing apparatus used in an embodiment of the present invention.

FIG. 2 is a plan view of multiple domed vortex discharge coils used in the embodiment of the present invention.

FIG. 3 is a plan view of a partially multiple dome-shaped vortex discharge coil.

FIG. 4 is a sectional view of a conventional plasma processing apparatus.

FIG. 5 is a plan view of a planar vortex discharge coil.

FIG. 6 is a sectional view of a conventional plasma processing apparatus.

[Explanation of symbols]

 1 Vacuum Container 2 High Frequency Power Supply 3 Dielectric Plate 4 Dome Vortex Discharge Coil 5 Electrode 6 Silicon Substrate 7 Gas Supply Port 8 Gas Exhaust Port 9 Planar Vortex Discharge Coil

Claims (3)

[Claims] 1. A vacuum container having an upper wall made of a dielectric plate, a vortex discharge coil provided outside the dielectric plate, and a high-frequency power supply for applying a high-frequency voltage to the center of the vortex discharge coil. A plasma processing apparatus, wherein an inner wall surface of the dielectric plate is a flat surface, and the vortex discharge coil is configured such that a distance from the inner wall surface of the dielectric plate increases as the center of the spiral discharge coil is closer to the center. 2. A vacuum container having an upper wall made of a dielectric plate, a vortex discharge coil provided outside the dielectric plate, and a high-frequency power source for applying a high-frequency voltage to the center of the vortex discharge coil. In the plasma processing method using plasma treatment, the inner wall surface of the dielectric plate is a flat surface, and the vortex discharge coil is configured such that the closer to the center thereof, the larger the distance from the inner wall surface of the dielectric plate. Plasma processing method for performing plasma processing by using a plasma treatment method. 3. The plasma processing apparatus according to claim 1, wherein a part or all of the spiral discharge coil has a multiple spiral shape.