JP2934465B2 - 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 in 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 in the vicinity of the discharge electrode A, becomes an active species, is transported by diffusion, and the substrate C
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, and the more the amount of active species reaching the substrate C, thereby realizing high-speed film formation.

[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 manner is peeled 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 apparatus is provided with two discharge electrodes facing each other, to which the same potential or different potentials are applied, sandwiching a substrate to be processed.
Magnetic field generating means is provided so that different poles face each other with the substrate to be processed sandwiched between the two discharge electrodes in a direction orthogonal to the axis connecting these discharge electrodes, and the plasma is concentrated near the substrate. It is characterized by having comprised.

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 configured to have a concave shape corresponding to the surface shape of the cylindrical substrate.

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

Further, when the magnetic field generating means is composed of a permanent magnet,
The permanent magnet can preferably be connected to a floating potential.

[Operation] In the plasma CVD apparatus of the present invention configured as described above, the magnetic field is generated by the magnetic field generating means by forming the magnetic field with the different electrodes facing each other with the substrate interposed between the discharge electrodes. The intensity of the magnetic field is higher in the vicinity, and strong plasma concentration occurs in the vicinity of the substrate.
As a result, the source gas is frequently decomposed in the vicinity of the substrate, and a thicker film is deposited on the substrate side than on the discharge electrode side. Therefore, deposition of a film on the discharge electrode side can be effectively suppressed.

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 arranged 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). Between the discharge electrodes 1, for example, a drum base 2 constituting an amorphous silicon photosensitive drum is inserted and grounded. Further, permanent magnets 3 serving as magnetic field generating means are arranged on both sides of the drum base 2 such 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 side toward the drum substrate 2 to be treated.

The magnetic field generated by the permanent magnet 3 is made to be stronger near the drum substrate 2 to be processed than near the discharge electrode 1, so that the plasma density is higher near the drum substrate 2 to be processed. Has been made.

Although not specifically shown in the drawings, each permanent magnet 3
The drum base 2 to be processed 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 be spaced apart from each other, and a discharge electrode 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.

As in the case of FIG. 1, permanent magnets 7 constituting magnetic field generating means are disposed on both sides of the drum base 2 such that different poles are opposed to each other across the drum base 6 to be processed. In this case, each permanent magnet 7 has a convex shape toward the drum base 6 to be processed. The magnetic field generated by these permanent magnets 7 acts to form a plasma condensing portion 8 between each discharge electrode 5 and the drum substrate 6 to be processed, and cross-hatches the vicinity of the drum substrate 6. In particular, the concentration of plasma is observed in the portion where the plasma is generated.

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

Also in this embodiment, each discharge electrode 5 similar to 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 drawing, each permanent magnet 7 or each permanent magnet 7 and the heating source 9 are movable and transportable together with the drum base 6 to be processed, as in the embodiment of FIG. May be configured.

In any of the embodiments shown in FIGS. 1 and 2, when the potential of the discharge electrode and the drum base is any level, if the permanent magnet is set to the ground potential, a discharge occurs between the discharge electrode and the permanent magnet, It becomes difficult to deposit a film on the substrate. Therefore, it is preferable that the permanent magnet has an appropriate floating potential.

As a result of performing an actual film forming experiment using the illustrated embodiment apparatus, assuming that the film thickness deposited on the drum base 2 or 6 is 1, the film thickness until the film thickness on the drum base 2 or 6 reaches 1. The thickness of the film deposited on the discharge electrode during the measurement was about 0.25. As a comparative example, the value varies depending on the location in the planar magnetron system, but is 3 to 7, and is approximately 1 when no magnet is used.

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 8 μm / hour.
was gotten.

From this, it is recognized that a high-speed film formation can be realized and a film can be hardly deposited on the discharge electrode.

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, a magnetic field generating means is provided separately from a discharge electrode, and a density is provided near a substrate to be treated by the action of a magnetic field generated by the magnetic field generating means. Since it is configured to concentrate high plasma,
Film deposition on the substrate can be performed at a high speed with little deposition of the film on the discharge electrode or the inner wall of the vacuum vessel.As a result, the film deposited on the inner wall of the discharge electrode or the vacuum vessel peels off and becomes a frame shape. Is extremely low.

Further, by configuring the magnetic field generating means to be movable and portable together with the substrate to be processed, the apparatus according to the present invention can be incorporated into an in-line process apparatus, and a portion where a thick film is deposited and where a high magnetic flux density is low can be constantly used. It can be taken out to the outside, and maintenance such as cleaning can be easily performed.

[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 (7)

(57) [Claims] 1. Two discharge electrodes to which the same potential or different potentials are applied are provided opposite to each other across a substrate to be treated,
Magnetic field generating means is provided so that different poles face each other with the substrate to be processed sandwiched between the two discharge electrodes in a direction orthogonal to the axis connecting these discharge electrodes, and the plasma is concentrated near the substrate. A plasma CVD apparatus characterized by comprising. 2. The plasma CVD apparatus according to claim 1, wherein the substrate to be treated is a cylindrical substrate, and each discharge electrode has a concave surface corresponding to the surface shape of the cylindrical substrate. 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 convex shape toward the substrate to be processed. 5. The plasma CVD apparatus according to claim 3, wherein the permanent magnet is at a floating potential. 6. The plasma according to claim 1, wherein the magnetic field generating means is movable and portable together with the substrate to be processed.
CVD equipment. 7. The plasma CVD apparatus according to claim 1, wherein the substrate to be processed is an amorphous silicon photosensitive drum.