JP2810931B2 - Method for removing unnecessary carbon in carbon production equipment - Google Patents

Description

The present invention relates to a plasma gas phase reaction method for forming a film with a sputtering effect, and forming a carbon film on a large number of substrates at one time. The present invention relates to a method for removing unnecessary carbon in a plasma processing apparatus.

The present invention uses a plasma CVD method to achieve a Vickers hardness of 2000K.
g / mm ² or more of carbon or a coating containing carbon as a main component is coated on the surface of the substrate to form a reinforcing material for these solid surfaces and a protective material against mechanical stress. is there. Further, after taking out the substrate to the outside, the inner wall of the container constituting the reaction space, the electrode,
The present invention relates to a method for removing a carbon film simultaneously formed on an upper surface of a holder by introducing a fluoride gas into a reaction space.

[Prior Art] In general, in a plasma CVD method, a method of forming a film without sputtering (damaging) a formation surface is considered to be effective. These are cases where a film of amorphous silicon or the like is produced. On the other hand, on the other hand, despite being a plasma CVD method,
A method of forming a film with a sputtering effect is also known. Regarding the coating of a carbon film, which is a typical example, with respect to the patent application “Composite having a carbon film and a method for producing the same” filed by the present inventors (Japanese Patent Application No. 56-146936, Showa 56)
(Filed on September 17, 2008). However, in these, a substrate is arranged on one electrode (cathode side) of a parallel plate type,
This is a method of forming a carbon film on the upper surface. Alternatively, the active species is strongly excited by a microwave excitation method to form a hard carbon film on the substrate.

However, in the conventional method of forming a film with such a sputtering effect, not only a large number of films can be simultaneously formed on a substrate having a large area of 20 cm □, 15 cm × 120 cm,
A film, for example, a hard carbon film, cannot be formed on a substrate having irregularities or a large amount at a time. Until now, it has not been pointed out that the plasma etching of the reaction space simply by changing the reactive gas helps to prevent the flakes from adhering to the substrate, and the importance of adding a higher alternating bias to the substrate and the holder has not been pointed out. Or, no attempt has been made. Therefore, not only a method of disposing a large amount of substrates in a large-capacity space and forming a hard carbon film on them at once but also a method of automating the inside of a reaction vessel while constantly performing cleaning is required. The present invention has been made for such a purpose.

"Means to Solve the Problem" In the method of the present invention, carbon or a film containing carbon as a main component is formed on a substrate and a holder by a plasma CVD method. Then, after removing the substrate coated with carbon from the reaction space, a fluoride gas is introduced into the reaction space, and an alternating voltage is applied between the electrodes to form plasma, thereby activating fluorine and unnecessary adhered carbon. Were reacted in accordance with the formula of 3C + 4NF ₃ → 3CF ₄ {12N ₂ }, removed, and cleaned. Then, at the time of the next carbon film formation, the remaining carbon can be prevented from flying as particles and adhering to the surface to be formed. In particular, since the sputtering effect is positively used on the surface on which the carbon film is formed, it is effective to remove the carbon attached to the reaction vessel, the holder, and the like in the previous step.

In the present invention, in order to form such a carbon film, a reaction space having a hexahedral structure is formed, and a pair of first and second electrodes are arranged on a pair of front and rear surfaces so as to be separated from each other. Further, a third electrode of a base or holder for forming a carbon film is provided, and an alternating voltage, particularly the first alternating voltage, is applied between the third electrode and the pair of first and second electrodes by the base or holder. Apply as much as possible on the cathode side. Further, the second frequency having a higher frequency as compared with this alternating voltage (first alternating voltage).
Are applied so as to have a complementary phase relationship between the pair of first and second electrodes. Then, as an example of the plasma treatment, a carbon thin film was formed by a plasma CVD method. A hydrocarbon gas such as ethylene or methane or a carbon fluoride gas such as carbon fluoride is subjected to a first medium frequency alternating electric field, for example, an alternating voltage of 50 KHz and a second alternating electric field, for example, 13.56 MHz.
introduced into an atmosphere in which the plasma is generated while applying a high frequency electric field of z, by allowed to decompose, making C-C bonds of similar diamond having SP ₃ orbit. As a result, instead of producing non-translucent conductive or poorly conductive carbon such as graphite, an insulating material having an optical energy bandwidth (Eg) of 1.0 eV or more, preferably 1.5 to 5.5 eV It is characterized by forming carbon. Furthermore, the carbon of the present invention has a Vickers hardness of 2000 kg / m.
m ² or more, preferably 4500 Kg / mm ² or more, ideally 6500
Kg / mm ^2, amorphous carbon having a hardness similar to diamond, or carbon having a crystallinity of 5 to 2 μm, or hydrogen and halogen elements in this carbon
In the present invention, carbon having a concentration of 25 atomic% or less or a trivalent or V-valent impurity of 5 atomic% or less, and nitrogen added at a concentration of N / C ≦ 0.05 (5%) is used. (Hereinafter simply referred to as carbon) on a solid.

The present invention is further applied to glass, ceramics, metals, magnetic materials, plastics (also referred to as organic resins), and oxide superconducting materials as base materials on which the carbon is formed. The shape of the substrate may be plate-shaped, dish-shaped,
It is also possible for containers, tweezers, cassettes for wafer holders, jigs, and rod-like materials.

In the present invention, plastics include organic resin substrates such as PET (polyethylene terephthalate), PES, PMMA, Teflon, epoxy, and polyimide.

The carbon film to which the method of the present invention is applied is a wear-resistant material,
In addition, the present invention is particularly effective for electric parts requiring chemical resistance on the surface and chemical instruments having chemical resistance.

The method for producing the composite used in the present invention will be described below with reference to the drawings.

Example 1 FIG. 1 shows an outline of a plasma processing apparatus for performing a plasma processing method of the present invention. FIG. 2 shows a vertical cross section taken along line AA ′ of FIG. 1 as viewed from the right.

In the drawing, the reaction vessel (7) of the plasma processing apparatus has a preloading chamber (7-1) and an unloading preparatory chamber (7-).
2) and a gate valve (14-2),
(14-3) and the gate valve (14-1) between the atmosphere and
(14-4), that is, partitioned by (14).

In the reaction space (6), the substrates (1-), (1-2),.
(1-m), that is, (1) is the holder (2-1), (2-
2),... (2-n), that is, on (2). The substrate (1) has a configuration in which only one surface is subjected to plasma processing. However, when plasma treatment is to be performed on the front and back surfaces of the base, a hole may be formed in the holder (2), and the holder may be disposed with the base interposed therebetween.

In this embodiment, the carbon film can be formed on the upper surface even if the holder is a plate-shaped conductor and an insulating base such as a glass, a silicon substrate, or a ceramic is provided on both surfaces thereof as shown in the drawing. The distance between the holders (31-1),
(31-2),... (31-n-1) are made equal or substantially equal to each other so that the degree of processing on each substrate is the same (the film thickness and film quality are the same in film formation). did. In the load chamber (17-1) and the unload chamber (17-2), the base and the holder are spaced apart (32) to save space.
-1), (32-2) ... (32-n-2) were made narrower than the intervals in the reaction space.

Further, these holders are held (held) by being hung on guide rails (9), and current is passed from the guide rails (9) to the holders so that the holders or electrodes can be used as third electrodes.

In the gas system (10), the carrier gas, hydrogen or argon gas, is converted from (10-1) to the reactive gas (10-
From (3), a fluoride gas such as NF ₃ or SF _{6 as} an etching gas is introduced into the reaction system (30) from (10-4) through a valve (28) and a flow meter (29) into a nozzle (30). 25) I will introduce more.

The reaction system (30) has cylindrical structures (8) and (8 ') (having a rectangular frame structure) and, as shown in FIG. 2, the front in FIG. 1 (the left side in FIG. 2). ) And on the rear side (right side in FIG. 2), a pair of first and second electrodes (3) and (3 ') are formed of a metal mesh. Halogen heaters (11) and (11 ') are provided outside of them, and infrared reflection plates (12) and (12') are further provided outside thereof. The substrate was then brought to a temperature of -100 ° C (with cooling means) to 850 ° C. The holder (2) forms a third electrode, and is electrically insulated from the reaction vessel (7). The substrates (1-1), (1)
-2),... (1-n), that is, (1).
A first alternating voltage is applied from a power source (17) between the third electrode of the holder (2) and the first and second electrodes (3), (3 ').

In addition, the matching transformer (1
6) via a second higher frequency than the first alternating electric field
The alternating voltage of (4), (3),
(4 ') is applied.

The matching transformer has a symmetric or substantially symmetric output, and one end (4) and the other end (4 ') are respectively connected to a pair of first and second electrodes (3) and (3'). Have been. A first alternating voltage (17) is applied to the output middle point (5) of the transformer. As the first alternating voltage, a high-frequency electric field having a frequency of 1 to 50 MHz, for example, 13.56 MHz was applied, and as the second alternating voltage, an alternating electric field having a frequency of 1 to 500 KHz, for example, 50 kHz was applied.

Thus, plasma (6) is generated in the reaction space. The exhaust system (20) exhausts unnecessary gas through the pressure adjustment valve (21), the turbo molecular pump (22), and the rotary pump (23).

These reactive gases are present in the reaction space (60) at 0.001 to 1.0
torr For example, 0.05 torr, and this cylindrical structure (8),
(8 ') has a rectangular parallelepiped shape, for example, 160cm in width and 40c in depth
m, 160 cm long. The pair of electrodes was set to 150 cm square in order to have an effective area of 120 cm square. In such a space, 1.0-30
Adding a second high-frequency voltage of KW (per unit area 0.04~1.3W / cm ²⁾ example 10 KW (high energy per unit area 0.44W / cm ^2). Further, the AC bias by the first alternating voltage is applied on the surface on which the AC voltage is formed by -200 to 600 V (for example, the output is 500 V
The output of 3kw was added by pumping out the frequency of 50KHz so that it became W).

Of course, the height of this rectangular parallelepiped cylindrical structure is 20cm-5m,
One side of the electrode may be 30 cm 3 to 3 m □.

"Example 2" This example is an example in which carbon or a film containing carbon as a main component is formed on a substrate using the plasma processing apparatus described in Example 1.

For example, methane or ethylene was used as the reactive gas. No self-heating was used after heating. For this purpose, first introduce argon gas and adjust the pressure to
The surface was sputtered and the substrate was heated. Then, the surface could be heated to 100 to 500 ° C, for example, 300 ° C. The outputs of the first and second voltages were 3 KW and 10 KW, respectively. Thereafter, the introduction of methane, which is a reactive gas, was increased, and the introduction of argon was reduced and stopped.
The self-heating temperature on the substrate was made constant. The same output alternating voltage was applied. Thus, carbon having an amorphous structure or a crystalline structure having a Vickers hardness of 2000 kg / mm ² or more on the surface to be formed and a large number of CC bonds having a thermal conductivity of 2.5 w / cm deg or more was formed by the plasma. When the plasma density is high, carbon having crystallinity can be generated. The deposition rate was between 100 and 1000 A / min, especially for example between 100 and 200 A / min. All of these were evaluated as good only under conditions having a Vickers hardness of 2000 kg / mm ² or more. Of course, if graphite is the main component (50% or more), it is very soft, black and completely different from the present invention.

Contrary to the present invention, when the potential on the substrate side is set to the anode level, the carbon film has a Vickers hardness of only 300 kg / mm ² or less, and is extremely soft and cannot be applied industrially.

In the present invention, when the frequency of the alternating voltage applied to the first and second electrodes is 1 to 500 KHz, which is the same as the bias voltage, it is difficult to convert the reactive gas into plasma. For this reason,
In order to further improve the deposition rate, the second alternating voltage is 1 to
A frequency of 5000 MHz, for example, 13.56 MHz is used. In particular, a CC bond and a C = C bond are decomposed, and a CC bond or -CC-
Make binding, covalently bound to collide with each other dangling bonds comrades carbon, capable of a locally have diamond structures having a secure SP ³ bond.

Thus, carbon, especially hydrogen in carbon, is deposited on the surface of a substrate on which a substrate of a semiconductor (for example, a silicon wafer), a ceramic, a magnetic material, a metal, an oxide superconducting material, or an electric component is temporarily attached or disposed on a holder. It was possible to form a coating containing carbon of 25 mol% or less or carbon having P, I or N type conductivity as a main component.

Thus, even if a thickness of 1 μm was provided at the end and the center, the thickness was not more than ± 5%, and the film quality such as hardness was uniform.

Examples of such a base include a silicon wafer and a substrate for a thermal head.

And the productivity was able to increase the productivity of 10K sets / month.

As an example of such a case, a semiconductor wafer (1)
For example, it is effective to coat a carbon film as a heat sink on the back side of a silicon wafer. Then, this carbon film has a thermal conductivity of 2.5 w / cm deg or more, typically 4.0 to
Since it has 6.0 W / cm deg, local heat generation in the power transistor section and the like in the semiconductor integrated circuit can be uniformly dissipated as a whole. And when forming on the back side of the wafer,
The carbon film was formed to a thickness of 0.5 to 5 μm, for example, 1 μm. Thickness is better as long as this thickness does not hinder adhesion.

After this coating, a probe test of the wafer is performed, and further, a scribe and break process is performed to make each IC chip, and then a structure in which each semiconductor chip is coated with a carbon film on the back surface is completed by die bonding and wire bonding I let it.

"Example 3" In this example, after forming a carbon film on the substrates in Example 2, these substrates were taken out of the reaction vessel (7). In Example 2, since the carbon film was formed not only on the substrate but also on the inner wall of the reaction vessel, it was removed by a plasma etching method.

That is, in Example 1, the doping system (10) gave NF ₃
Was introduced from (10-4), and argon was further introduced from (10-1).
More introduced. Then, the pressure in the reaction space was adjusted to 0.05 torr, and then the pressure was applied with the same strength as when forming the carbon film. The first and second alternating voltages used the same power supply having the same frequency. Then, when the carbon film was formed to a thickness of 1 μm, the carbon film on the holder, the inner wall of the reaction vessel, and the electrode could be removed in about 15 minutes. Thereafter, the cleaned holder was taken out of the reaction system, and a new substrate was held. Then, a new carbon film is coated by the plasma CVD method in the second embodiment.
Was performed as shown in Table 1. By this cleaning operation in the reaction vessel, flakes were generated due to the sputtering effect at the time of the second carbon film formation, and the flakes could be prevented from adhering to the surface to be formed.

This etching may be performed every time the carbon film is coated. However, if the total thickness of the carbon film is not enough, the reaction is performed once after the formation of the carbon film three to five times. A method of etching the inner wall of the container and the holder may be employed.

When the holder is not provided in the reaction vessel, this etching may be performed by applying an alternating voltage only between the pair of the first and second electrodes.

When only the holder is not cleaned, plasma cleaning may be performed by applying only the first alternating electric field.

[Effect] The method of the present invention enables industrial mass production by making the substrate side the electrode side that should have a sputtering effect on the cathode side and making the reaction space extremely large. Then, film formation using a carbon film, chamber cleaning, and film formation can be continuously performed.

The present invention provides a plasma in which the surface to be formed has a cathode-side potential.
In the CVD method, it is extremely effective in preventing the generation of flakes. When such a plasma CVD method is used, it is effective not only in forming a carbon film but also in forming another film.

Furthermore, when a large-capacity reaction space as shown in the present invention is provided, cleaning of the inner wall cannot be performed manually. Therefore, what can be done only by changing the reactive gas using the same device on the inner wall has the effect of two birds per stone. In particular, carbon films cannot be etched with any liquid chemical. However, the present inventors have found that plasma fluorine can be easily etched, and have positively applied the results.

As is clear from the above description, when the present invention is used as a CVD method, the formed thin film is not only carbon but also silicon nitride, boron nitride, an insulating thin film such as tantalum oxide, metal aluminum, and oxide superconducting material. There may be.

Ceramics of the present invention is alumina, zirconia, _carborundum, YBaCu ₃ O 6~8, an oxide superconducting material known in BiSrCaCuyOx like are effective. The magnetic material may be a rare earth magnet such as samarium or cobalt, an amorphous magnetic material, iron oxide, or an anisotropic magnetic material coated with nickel, chromium, or the like.

[Brief description of the drawings]

FIG. 1 shows an outline of a plasma processing apparatus manufacturing apparatus according to the present invention. FIG. 2 is a longitudinal sectional view of a main part of the plasma processing apparatus of FIG.

Claims (1)

(57) [Claims] 1. A product gas consisting of a carbonaceous gas containing hydrogen is introduced into a reaction space under reduced pressure to form a coating containing carbon or carbon as a main component on a surface of a substrate on which a film is to be formed by a plasma gas phase method. Generating, removing the substrate having the carbon or carbon-based coating from the reaction space, and then introducing a fluoride gas into the reaction space to cause a plasma reaction, Electrodes in the reaction space,
A method of removing unnecessary carbon in a carbon production apparatus, comprising etching and removing the carbon or a film containing carbon as a main component adhered to an unnecessary portion such as an inner wall.