JPH0627341B2 - Thin film formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Use of the Invention" The present invention relates to a plasma vapor phase reaction method for forming a film with a sputtering effect, and a vapor phase reaction method for forming a film on a large amount of a substrate at once. Regarding

The present invention, as an example of such a thin film, has a Vickers hardness of 2000.
It is intended to obtain a reinforcing material for the surface of these solid materials or a protective material against mechanical stress by coating the surface to be formed of carbon with carbon having a Kg / mm ² or more or a film containing carbon as a main component. is there.

“Prior Art” Generally, in the plasma CVD method, a method of forming a film without spattering (damaging) the surface to be formed is considered to be effective. This is the case in which a film of amorphous silicon or the like is formed. However, there is also known another method, conversely, a method of forming a film with a sputtering effect while using the plasma CVD method. Regarding the coating of a carbon film, which is a typical example thereof, a patent application filed by the present inventor "Composite having carbon coating and method for producing the same" (Japanese Patent Application No. 56-146936 (Japanese Patent Application Laid-Open No. 58-48428), Showa 56 Application dated September 17, 2012) is known. However, in these methods, a substrate is disposed on one electrode (cathode side) of a parallel plate type, and a carbon film is formed on the upper surface thereof. Alternatively, it is a method of strongly exciting active species by a microwave excitation method to form a hard carbon film on a substrate.

"Conventional problems" However, in the conventional example of forming a film with such a sputtering effect, not only a film cannot be formed on a large area, but also a substrate having irregularities or a large amount of a film on the substrate at one time, for example, hard carbon. I can't make a film. Therefore, there has been a demand for a method of arranging a large amount of substrates in a large-capacity space and forming a carbon film on them all at once. The present invention has been made for such a purpose.

"Means for Solving Problems" The present invention has a tubular structure, and a plurality of substrates having a surface to be formed are arranged in the tubular structure. Then, a pair of electrodes is arranged at one end and the other end of the opening of the tubular structure. Then, one end and the other end of the matching coil on the output side of the first alternating electric field are connected to this pair of electrodes, and symmetrical or nearly symmetrical alternating electrodes are applied. Furthermore, another second alternating electric field is applied between the midpoint of the coil and the tubular structure,
The cylindrical structure, the substrate holder (also simply referred to as a holder), or the substrate is made to act as a third electrode, and a thin film is not formed on the substrate with a sputtering effect. As an example of the formation of this thin film, a hydrocarbon gas such as ethylene or methane or a carbon fluoride substrate such as carbon fluoride is used as a second alternating electric field, for example, a high frequency electric field and a first alternating electric field, for example, a high frequency electric field. Is introduced into the atmosphere in which plasma is generated while adding the
Instead of making a C—C bond similar to a diamond with ^three orbitals, resulting in a non-translucent conductive or poorly conductive carbon like graphite, the optical energy bandwidth (called Eg) 1.0eV or more, preferably
It is characterized in that it forms an insulating carbon having 1.5 to 5.5 eV. Further, the carbon of the present invention also has a Vickers hardness of 2000 Kg / mm ² or more, preferably 4500 Kg / mm ² or more, and ideally 6500 Kg / mm ^{2 which} has a diamond-like hardness of amorphous (amorphous) or 5Å ~ 2 μm
With a crystallinity of the size of 25% or less of hydrogen or halogen in this carbon, or with a valence of III or V
A complex in which carbon having a so-called carbon as a main component (hereinafter, simply referred to as carbon in the present invention) to which a valence impurity is 5 atomic% or less or nitrogen is added at a concentration of N / C ≦ 0.05 is provided on a solid It is a provision.

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

In the present invention, especially as plastic, for example,
PET (polyethylene terephthalate), PES, PMMA, Teflon,
There are organic resin substrates such as epoxy and polyimide.

The present invention is also directed to boron which is a trivalent impurity in this carbon.
By adding P-type carbon by adding it to a concentration of 0.1 to 5 atom%, and similarly adding phosphorus and nitrogen, which are V-valent impurities, to a concentration of 0.1 to 5 atom% and providing N-type carbon. Another feature is that the carbon on the upper surface of the substrate is made semiconductive.

The carbon film to which the method of the present invention is applied is a wear resistant material, and is particularly effective for electric parts which require slip resistance on the surface and chemical appliances 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 CVD apparatus for carrying out the thin film forming method of the present invention.

In the drawing, the reaction vessel (7) of the plasma CVD apparatus is partitioned by a loading / unloading preliminary chamber (7 ') and a gate valve (9). Then, in the gas system (10), the carrier gas hydrogen (11), a reactive gas hydrocarbon gas,
For example, methane or ethylene from (12), diborane as a III-valent impurity (diluted with hydrogen to 1%) or ammonia or foshin (V-valent impurity) (diluted with hydrogen to 1%) from (13), and an etching gas such as Oxygen or oxygenate gas
From (14), it is introduced into the reaction system (30) through the nozzle (25) through the valve (28) and the flow meter (29). Before reaching this nozzle,
It is effective to pre-activate by adding microwave energy at (26) for exciting the reactive gas.

The reaction system (30) has a tubular structure (2) (having a cylindrical or square frame structure), and the upper and lower openings of the hood (8), (8) so as to cover the opening. ′). The pair of first and second electrodes (3) and (3 ') arranged on the hoods (8) and (8') are made of metal mesh.
The reactive gas is discharged downward from the nozzle (25). The tubular structure constitutes the third electrode and is electrically insulated from the reaction vessel (7). Holder that is electrically connected to this cylinder structure
(1 '), and is held by this holder and the bases (1-1), (1-
2), ... (1-n), that is, (1) is provided. The reactive gas turned into plasma was uniformly dispersed in the reaction space (60), and was not discharged to the outside (6) in a plasma state from this frame so as not to adhere to the inner wall of the reaction vessel. Two kinds of alternating electric fields can be applied to the power supply system (40). First
The alternating electric field of the matching transformer (1
6). This matching transformer has symmetrical or roughly symmetrical outputs, and one end (4) and the other end (4 ') are connected to a pair of first and second electrodes (3), (3'), respectively. Has been done. Further, another alternating electric field (17) is applied to the output side midpoint (5) of the transformer and is connected to the third electrode (2) constituting the cylindrical structure, the holder or the substrate. The first alternating electric field was a high frequency electric field having a frequency of 1 to 50 MHz, eg 13.56 MHz, and the second alternating electric field was an alternating electric field having a frequency of 1 to 500 MHz, eg 50 KHz. Thus, plasma (60) is generated in the reaction space. The exhaust system (20) has a pressure regulating valve (2
1), the turbo molecular pump (22) and the rotary pump (23) are exhausted to exhaust unnecessary gas.

These reactive gases are 0.001-1.0tor in the reaction space (60).
r is, for example, 0.05 torr, and this tubular structure (2) has a quadrangular shape, and has, for example, a width of 80 cm, a depth of 80 cm, and a length of 40 cm. In such a space 0.5 to 5KW (0.3 to 3W / c per unit area)
m ² ) For example, 1 KW (high energy of 0.6 W / cm ² per unit area)
Is applied to the first high frequency electric field. Further, as the AC bias by the second alternating electric field, -200 to 600 V (for example, its output is 500 W) was applied on the formation surface.

Of course, the height of this quadrangular (rectangular parallelepiped) tubular structure is 20
cm to 1 m, and one side may be 30 cm to 3 m.

Thus the terminals on the output side of the symmetrical matching transformer (16)
(4) and (4 ') were set to the ground level, and the middle point was set to the power source side which should have the sputtering effect on the cathode side. The reactive gas was, for example, methane: hydrogen = 1: 1. Front and rear (not shown) of the reaction vessel have heating or cooling means to keep the gas at 450 ° C to -100 ° C. Thus, plasma generated carbon having a Vickers hardness of 2000 Kg / mm ² or more on the surface to be formed and an amorphous structure or a crystalline structure in which a large number of CC bonds having a thermal conductivity of 2.5 W / cm deg or more were formed. If this plasma density is high, or if the reactive gas has been previously excited by microwaves,
It was also possible to generate crystalline carbon. The film formation rate is 100 to 1000 A / min, and especially the surface temperature is +50
When the temperature is set to ~ 150 ° C (without external heating) and an AC bias of +100 to 300V is applied by the second alternating electric field, the film formation rate is
100 to 200 A / (when methane was used and no microwave) and 500 to 1000 A / min (when methane was used with microwave or ethylene was used with microwave). All of these have Vickers hardness of 2000 Kg / m
Only the condition having m ² or more was regarded as a good product. Of course, if graphite is the main component (50% or more), it is extremely soft,
It is black and completely different from the present invention.

On the contrary to the present invention, when the midpoint is set to the ground potential, this substrate becomes the anode level, and the carbon film has a Vickers hardness.
Only less than 300Kg / mm ² can be obtained. Very soft and impossible for industrial application.

Impurities and unnecessary substances after the reaction are exhausted from the exhaust system (20) through the turbo molecular pump (22) and the rotary pump (23). Especially in a reactive gas reaction system, if the excitation source before the reaction has a frequency of 1 GHz or more, for example 2.45 GHz, hydrogen is separated from the CH bond, and if the frequency is 0.1 to 50 MHz, for example 13.56 MHz. , C—C bond, C = C bond are decomposed,
A C-C bond or a -C-C- bond may be formed, and the unpaired carbon bonds of carbon atoms may collide with each other to form a bond, resulting in a structure having a stable diamond structure locally.

Thus, the base semiconductor (eg, silicon wafer),
On the surface of a substrate on which a ceramic, magnetic substance, metal, oxide superconducting material or electric component substrate is temporarily attached or disposed on a holder, carbon, particularly carbon containing 25 mol% or less of hydrogen, or P, It was possible to form a film containing carbon having a conductivity type of I or N as a main component.

In this embodiment, a large number of dishes are held in a holder, and carbon or a coating film containing carbon as a main component is formed on the upper surface to a thickness of 50Å to 10 µm.

Second Embodiment FIG. 2 shows another embodiment of the present invention. FIG. 2 is the same as FIG. 1 except that only the tubular structure and its inside are shown. That is, the cylindrical structure which is the third electrode also serves as the holder (1 '), and the back surface is brought into contact with this holder to form the base bodies (1-1), (1-2), ...
・ (1-n) That is, (1) is installed. Then, it was possible to prevent the formation of a thin film on the back surface and to form a thin film having a uniform film thickness, for example, a carbon film on the front surface side. in this case,
The tubular structure and the holder were made of aluminum, nickel or stainless steel. In this example, between the substrates
(31-1), (31-2), ... (31- (n-1)) or (31)) are 6
Spaced by ~ 10 cm and evenly spaced. This is to keep the plasma density at each interval constant. This base holder (1 ') is 60 cm x 30 cm (square tube structure is 80 cm (width)
In the case of a size of × 80 cm (depth) × 40 cm (height), it had an effective area of 10 cm in the front and back and 5 cm in the upper and lower sides of the film having an uneven film thickness). That way,
± 5% even if a thickness of 1 μm is applied to the edges and center
The film thickness varied only below, and the film quality such as hardness was uniform.

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

Then, as an example of such a case, it is effective to coat a carbon film as a heat sink on the back surface side of a semiconductor wafer (1), for example, a silicon wafer. Then, this carbon film has a thermal conductivity of 2.5 W / cm deg or more, typically 4.0 to 6.0 W /
Since it has cm deg, it is possible to uniformly dissipate local heat generation such as the power transistor portion in the semiconductor integrated circuit. When it is formed on the back surface of the wafer, the carbon film is formed to a thickness of 0.5 to 5 μm, for example 1 μm. It is preferable that this thickness is as large as possible without impairing the adhesion.

After this coating, a wafer probe test is performed, and in order to make each IC chip, through a scribe and brace process, each semiconductor chip is coated with a carbon film on the back surface by die bonding and wire bonding. Completed

[Embodiment 3] The embodiment of the present invention is shown in FIG. 3 in the embodiment of FIG. Reticulated metal holder (2 ') on the tubular structure (2)
By this, the tweezers (1) and the container (1 ′) were temporarily attached and arranged. Since the reaction space (60) is a space, even if it is uneven or has a rod shape, it is possible to coat all the parts with variations in the film thickness.

[Embodiment 4] In this embodiment, the carbon film produced in Embodiment 1, 2 or 3 is applied, for example, to the upper surface of a silicon wafer on which a semiconductor integrated circuit is previously formed, as shown in FIG. 3 (A). Formed. In this case, after forming a carbon film on the upper surface of the silicon wafer as shown in Example 2, the carbon only in the bonding pad portion was removed by ashing with oxygen plasma.

That is, after forming aluminum pads and wiring on the upper surface of a silicon wafer, 0.3 silicon oxide is entirely deposited on them.
It was formed to a thickness of ˜1 μm. Further, according to Example 1, a carbon film was formed thereon to a thickness of 0.1 to 1 μm, for example 0.3 μm. Form a silicon oxide film again as a mask,
Further, a resist for selective removal was selectively coated, and silicon oxide was plasma-etched with a fluoride gas. Then, the oxide gas such as oxygen and the gas of Example 1 were switched, and the carbon film was removed by plasma etching only in a desired silicon oxide-free portion such as a bonding pad portion. Further thereafter, the silicon oxide and the resist thereunder were removed by plasma etching with a fluoride gas using the carbon film as a mask to expose the aluminum pad. That is, the first
In the example of the figure, a final coat film of a carbon film could be formed on the electric wiring only by sequentially switching the reactive gas.

By doing so, the local heating by the power transistor or the like could be spread more quickly to the whole.

In addition, it became possible to block sodium ions. Of course, this carbon film may leave another silicon oxide film or the like between aluminum wirings or on this carbon film.

The examples of the present invention mainly show the method of forming carbon or a coating film containing carbon as a main component. However, silane and ammonia may be introduced to produce silicon nitride with a sputtering effect. In addition, a conductor of aluminum may be formed by introducing methyl aluminum or the like. However, in the method of the present invention, when the film-formed material is a conductor, a short circuit between electrodes is easily induced, so the material to be film-formed is an insulating material or a material having a sufficiently large electric resistance (oxide superconducting material), ceramics, Magnetic materials) are preferred.

"Effects" The method of the present invention enables industrial mass production by making the substrate side an electrode that should have a sputtering effect on the cathode side and making the reaction space extremely large. And in thin film formation, as an example,
A carbon film was used. This carbon film has a thermal conductivity of 2.5 W / cm deg.
Above, typically 4.0 ~ 6.0 W / cm deg of diamond
Since it vows to 60 W / cmdeg, it is possible to prevent local temperature rise and the characteristic deterioration of the magnetic head due to it, and to combine many characteristics such as wear resistance, high thermal conductivity, and high smoothness peculiar to carbon film. It is used effectively.

As is apparent from the above description, the present invention comprises an organic resin or a glass compounded with it, a magnetic material, a metal or a ceramic, a semiconductor or a composite thereof,
A thin film, for example, carbon or a film containing carbon as a main component is coated on the surface of these solids. The application of this composite is immeasurable as seen in many other examples. In particular, while this carbon can be formed at a low temperature of 150 ° C or lower, its hardness or adhesion to a substrate is extremely excellent. The feature is that

Ceramics in the present invention are alumina, zirconia,
Carborundum, oxide superconducting materials known in _{YBaCu 3 O 6 ~ 8, BiSrCaCu} 2 Ox or the like is effective. Further, the magnetic substance may be a rare earth magnet such as samarium or cobalt, an amorphous magnetic substance, iron oxide or an anisotropically shaped magnetic substance obtained by coating nickel oxide, chromium or the like.

[Brief description of drawings]

FIG. 1 shows an outline of a plasma CVD apparatus manufacturing apparatus of the present invention. 2 and 3 show an embodiment of the main part of another plasma CVD apparatus of the present invention.

Claims (3)

[Claims] 1. A base having a surface to be formed is arranged in a tubular structure having a tubular structure, and a pair of electrodes is provided in one and the other of openings of the tubular structure, the pair of electrodes being a matching coil. Is connected to one end and the other end thereof to apply an alternating electric field symmetrical or nearly symmetrical to each other, and a second electrode is provided between the midpoint of the matching coil and the third electrode of the cylindrical structure, the holder or the substrate. A thin film forming method, characterized in that by applying an alternating electric field, the reactive gas introduced into the cylindrical structure is turned into plasma, and a reaction product is formed into a film on the substrate. 2. The alternating electric field according to claim 1, wherein the alternating electric field is a high frequency electric field, one end and the other end of the matching transformer both have a ground level, and the third electrode of the cylindrical structure constitutes a cathode. A thin film forming method characterized by the above. 3. The holder according to claim 1, wherein the holders constituting the third electrodes are arranged in parallel or substantially in parallel with each other in the cylindrical structure, and the back surfaces of the holders are in contact with each other to form a basic structure. A method of forming a thin film, characterized in that a film of a reaction product is formed on the surface of a substrate by providing the film.