JP2934466B2 - Plasma CVD equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plasma CVD apparatus. The present invention can be advantageously used in an apparatus for manufacturing an amorphous silicon photosensitive drum.

[Prior Art] Conventionally, a method of confining plasma using a magnetic field to realize high-speed processing in a film forming apparatus using glow discharge has been known. An example of this is, for example,
One using a planar magnetron as disclosed in JP-A-15982 can be mentioned.

In this apparatus, as shown in FIG. 3 of the accompanying drawings, a magnet B is arranged inside a discharge electrode A, and a magnetic field line exiting from the discharge electrode A and entering the discharge electrode A again is formed by the magnet B. High-density plasma is confined in the vicinity.

The electrons in the plasma rotate in a plane perpendicular to the lines of magnetic force, but when the discharge electrode A incorporating the magnet B is a cathode, the electrons are repelled before colliding with the discharge electrode A. As a result, the discharge electrode The cycloid motion is repeated near A. Thus, high-density plasma is confined in the vicinity of the discharge electrode A. On the other hand, when this apparatus is a film forming apparatus utilizing a chemical reaction, the gas is decomposed near the discharge electrode A, becomes an active species, is transported by diffusion, and
And the thin film grows. Therefore, the higher the plasma density in the vicinity of the discharge electrode A, the more efficiently the gas is decomposed, the more the amount of active species reaching the substrate C is increased, and constrained film formation can be realized.

[Problems to be Solved by the Invention] In the above-described conventionally proposed apparatus, the decomposition of the source gas is performed in the vicinity of the discharge electrode A facing the substrate C, so that a film thicker than the substrate C is formed on the discharge electrode side. Will be deposited on the surface. In particular, in a portion where the plasma is concentrated and where the magnetic flux density is high, an extremely thick film is deposited as compared with other portions. The film deposited in this way peels off after repeating the film formation several times, and the resulting flakes adversely affect the properties of the film deposited on the substrate side. To prevent this, the discharge electrode may be cleaned every time, but doing so has to sacrifice productivity.

Therefore, the present invention is to solve the above-mentioned problems in the conventional planar magnetron type plasma CVD process, and to provide a plasma CVD apparatus capable of reducing the deposition of a film on an electrode facing a substrate. It is an object.

Means for Solving the Problems In order to achieve the above object, a plasma according to the present invention is provided.
The CVD device is provided with two discharge electrodes facing each other with the substrate to be processed sandwiched between them. Outside the respective discharge electrodes, the opposite electrodes are opposed to the substrate to be processed, and the direction in which the facing discharge electrodes are connected. Characterized in that a magnetic field generating means for forming a magnetic field along is provided.

According to one embodiment of the present invention, the substrate to be treated is a cylindrical substrate, and the surface of each discharge electrode may be formed in a concave shape corresponding to the surface shape of the cylindrical substrate.

Also, the magnetic field generating means may be constituted by a permanent magnet or an electromagnet, preferably a permanent magnet or an electromagnet having a concave shape toward the substrate to be treated.

[Operation] In the plasma CVD apparatus of the present invention configured as described above, the lines of magnetic force generated by the magnetic field generating means reach not only the vicinity of the discharge electrode but also the base, and also the lines of magnetic force near the discharge electrode. Is less biased, and high-density plasma can be uniformly generated as a whole. As a result, the thickness of the film deposited on the discharge electrode becomes substantially uniform, and the film is not locally thickened locally on the discharge electrode during the short-time film formation.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 of the accompanying drawings.

FIG. 1 shows a basic configuration according to an embodiment of the present invention. Reference numeral 1 denotes a discharge electrode, which is disposed in a vacuum vessel (not shown) so as to face each other at an interval. Appropriate RF power is applied from an RF power supply (not shown).

A drum base 2 constituting, for example, an amorphous silicon photosensitive drum is inserted between the discharge electrodes 1, and the drum base 2 is electrically connected to ground. Further, a permanent magnet 3 serving as a magnetic field generating means is arranged outside each discharge electrode 1 so that different poles are opposed to each other with the drum base 2 to be processed interposed therebetween. The reaction gas is introduced from the discharge electrode 1 toward the drum substrate 2 to be treated.

The magnetic field generated by the permanent magnet 3 is uniformly distributed in the space between the discharge electrodes 1, whereby a uniform and high-density plasma is formed around the drum substrate 2 to be treated.

Although not specifically shown in the drawings, the drum substrate 2 to be processed can be rotated during film formation, and can be configured to be movable and transportable.

FIG. 2 shows another embodiment of the present invention. Reference numeral 5 denotes a discharge electrode which is provided in a vacuum vessel (not shown) so as to face each other at an interval, and is rotatably inserted between these discharge electrodes. 1 is provided with a concave arcuate surface portion 5a extending concentrically with a drum substrate 6 to be processed similar to that shown in FIG. As shown, a supply outlet 5b for a reactive gas such as SiH ₄ is provided on the surface 5a of each discharge electrode 5.

Outside the concave arc-shaped surface portion 5a of the discharge electrode 5, a permanent magnet 7 constituting a magnetic field generating means is arranged so that different poles face each other with a drum base 6 to be processed sandwiched therebetween as in the case of FIG. Have been. In this case, each permanent magnet 7 extends along the surface 5a and has a concave shape toward the drum base 6 to be processed. By the action of the lines of magnetic force 8 generated by these permanent magnets 7, uniform and high-density plasma is formed between each discharge electrode 5 and the drum base 6 to be processed.

As shown, a heating source 9 for heating the drum substrate 6 is disposed inside the drum substrate 6 to be processed.

In this embodiment, as in the case of FIG.
The drum substrate 6 to be processed is connected to an RF power source (not shown) and grounded. The reaction gas is supplied to the drum substrate 6 through a reaction gas supply outlet 5b provided in each discharge electrode 5.
Spilled out towards. Further, although not specifically shown in the drawings, the heating source 9 can be configured to be movable and transportable together with the drum base 6 to be processed, as in the embodiment of FIG.

As a result of performing an actual film forming experiment using the illustrated apparatus, a film having a thickness similar to the film thickness deposited on the drum substrate 2 or 6 was deposited on the discharge electrode 1 or 5 side on average. . For comparison, a film was formed by replacing the magnet for planar magnetron discharge with the permanent magnet in the illustrated device.
A film about 7 times as thick as the substrate side in the portion having a high magnetic flux density and about 3 times as thick as the other portions was deposited on the discharge electrode.

In addition, powdery polysilane dust generated during the reaction was smaller at lower pressures, and was hardly generated at 0.1 Torr or less. In this pressure range, the deposition rate of amorphous silicon on the drum substrate is about 6 μ / hour.
m was obtained, and an improvement about 2 to 3 times as compared with the case where no magnet was used was observed.

By the way, in the illustrated embodiment, a permanent magnet is used as the magnetic field generating means, but an electromagnet can of course be used.

In addition, the RF discharge electrodes sandwiching the substrate to be processed are configured to be connected to the same RF power supply, but each discharge electrode should be powered by a separate power supply with a slightly different frequency. Can also. Furthermore, only one of the discharge electrodes can be at RF potential and the other discharge electrode can be at ground potential, in which case the substrate to be treated can be at floating potential.

[Effects of the Invention] As described above, according to the present invention, the magnetic field generating means is provided outside the discharge electrode, and the magnetic field generated by the magnetic field generating means is used to uniformly surround the substrate to be treated. Since it is configured to form a high-density plasma, it is possible to form a film on a substrate at a high speed while avoiding local deposition of a film on a discharge electrode or the inner wall of a vacuum vessel. The probability that the film is deposited on the electrode or the inner wall of the vacuum vessel and peeled off to form a flake can be extremely low.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a basic embodiment of the present invention, FIG. 2 is a schematic sectional view showing another embodiment of the present invention, and FIG. 3 shows an example of a conventional planar magnetron type apparatus. It is a schematic diagram. In the figure, 1: discharge electrode 2: drum base 3: magnetic field generating means 5: discharge electrode 6: drum base 7: magnetic field generating means 9: heating source

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masamichi Matsuura 5-9-7 Tokodai, Tsukuba, Ibaraki Japan Japan Vacuum Engineering Co., Ltd. Tsukuba Super Materials Research Laboratory (56) References JP-A-63-303065 (JP, A JP-A-62-103370 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C23C 16/00-16/50

Claims (5)

(57) [Claims] 1. Two discharge electrodes are provided opposite to each other with a substrate to be treated interposed therebetween. Outside the respective discharge electrodes, different electrodes are opposed to the substrate to be treated, and the opposite discharge electrodes are connected. A plasma CVD apparatus comprising a magnetic field generating means for forming a magnetic field along a direction. 2. The plasma CVD apparatus according to claim 1, wherein the substrate to be treated is a cylindrical substrate, and the surface of each discharge electrode has a correspondingly concave surface. 3. A magnetic field generating means comprising a permanent magnet.
The plasma CVD apparatus according to item 1. 4. The plasma CVD apparatus according to claim 1, wherein the magnetic field generating means comprises a permanent magnet having a concave shape toward the substrate to be processed. 5. The discharge plasma CVD apparatus according to claim 1, wherein the substrate to be processed is an amorphous silicon photosensitive drum.