JPH0627344B2 - 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.
By coating carbon having a Kg / mm ² or more or a film containing carbon as a main component, a silicon nitride film, a silicon oxide film, titanium nitride or a multilayer film of these on the surface on which the substrate is formed, It is intended to obtain a reinforcement material or a protection material against mechanical stress.

“Prior Art” Generally, in the plasma CVD method, it is said that a method of forming a film with care so as not to sputter (damage) the surface to be formed is 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 entitled “Composite with carbon coating and method for producing the same” filed by the present inventor (Japanese Patent Application No. 56-14)
6936 (Japanese Patent Laid-Open No. 58-48428, filed September 17, 1981) is known. However, these are methods in which a substrate is disposed on one electrode (cathode side) of the 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.

"Problems of the prior art" However, in the conventional example of forming a film with such a sputtering effect, it is not possible to form a coating film over a large area, and it is not possible to form a substrate having irregularities or a large number of films on the substrate at one time. Can not. Therefore, there has been a demand for a method of arranging a large amount of substrates in a large capacity space and forming a coating film on them at one time. 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 voltage are connected to the pair of electrodes, and a symmetrical or nearly symmetrical alternating electrode is applied. Further, another second alternating voltage is applied between the midpoint of the coil at the ground level and the base body or base body holder having the surface to be formed, and this base body holder (also simply referred to as a holder) or the third base body By acting as an electrode, a thin film is not formed on this substrate with a sputtering effect.

Then, the first alternating voltage is set to a frequency of 1 to 50 MHz at which glow discharge is likely to occur, and the second alternating voltage is set to 1 to 500 KHz.
The kinetic energy is applied to the reactive gas as a frequency that is easy to add. Further, one of the second alternating voltage and the midpoint of the matching coil are both at the ground level, that is, a negative DC self-bias is superimposed and applied to the output side of the second alternating voltage. Then, the gas activated by the first alternating voltage is accelerated on the substrate by the self-bias, and unnecessary charge-up charges on the substrate are removed by the second alternating voltage. Thus, a film can be formed on the surface.

And as an example of the formation of this thin film, ethylene (C ₂ H ₄ ),
Introducing a hydrocarbon gas such as methane (CH ₄ ), acetylene (C ₂ H ₂ ) or a carbon fluoride gas such as carbon fluoride, and decomposing it, the CC bond similar to diamond having an SP ³ orbital With an optical energy band width (called Eg) of 1.0 eV or more, preferably 1.5 to 5.5 eV and a Vickers hardness of 2000 Kg / mm ² or more, preferably 4500 Kg / mm ²
As described above, ideally, a carbon film having a diamond-like hardness of 6500 Kg / mm ² was formed. Furthermore, disilane (Si
_A silicon nitride film was formed at room temperature (without intentionally heating the substrate temperature) by reacting ₂ H ₆ ) with ammonia (NH ₃ ). This silicon nitride film has a resistivity of 1.7 to 2.0 and an etching rate of 2 to 10 Å / sec with 1/10 hydrofluoric acid and is extremely dense (a normal silicon nitride film has an etching rate of about 30 Å / sec). Further, a multilayer film is formed by forming a silicon nitride film on the substrate and the carbon film described above on the silicon nitride film.

Also, by the reaction of silane (SiH ₄ ) with nitrous oxide (N ₂ O),
A silicon oxide (SiO ₄ ) film was formed. In this film formation, the substrate was at room temperature, but the formed silicon oxide film was an extremely dense film. At the time of this film formation, phosphorus or boron may be added at the same time using fossine or diborane to form phosphorus glass or boron glass.

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

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). And in the gas system (10), hydrogen or nitrogen as a carrier gas from (11), a hydrocarbon gas as a reactive gas such as methane or ethylene from (12), and a silicide gas such as monosilane or disilane ( 13) and ammonia or oxygenate gas from (14) to the valve (2
8) Introduce the flow meter (29) into the reaction system (30) through the nozzle (25). Then, a silicon nitride film can be formed by introducing disilane and ammonia, and a diamond-like carbon film can be formed by introducing a carbide gas. A silicon oxide film can be formed by introducing a monosilane oxide 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. ′). Then, the pair of first and second electrodes (3) and (3 ') having the same shape, which are arranged on the hoods (8) and (8'), are made of a metal mesh of aluminum. Reactive gas is discharged from the nozzle (2
5) It is released downward. The holder of the third electrode was made of aluminum, and its surface was coated with alumina by alumite treatment to insulate it in terms of direct current and make it conductive in terms of alternating current. Then, a substrate having a surface to be formed was arranged on this insulating film. The substrate (1-1), (1-
2), ... (1-n) That is, in (1), an alternating voltage of 1 to 1000 KHz to which a negative DC bias is applied from the second alternating voltage is applied. The reactive gas that has been turned into plasma by the alternating voltage of the first high frequency is uniformly dispersed in the reaction space (60), and is prevented from being discharged in the plasma state from the frame (2) to the outside (6). So that it doesn't stick to. Power system
Two types of alternating voltage can be applied to (40). The first alternating voltage reaches the matching transformer 16 from the high frequency power source 15 of 1 to 1000 MHz, for example 13.56. The matching transformer has a symmetrical or roughly symmetrical output, and one end (4) and the other end (4 ') have a pair of first and second outputs.
Of electrodes (3) and (3 '). Also, the output output midpoint (5) is held at ground level and
The alternating voltage (17) of 1 to 500 KHz, for example 50 KHz, is applied. And the output is the holder (1'-1 '), (1'-2'),
(1'-n '), that is, (1') or the third electrode (2) constituting the substrate (1). If the base is conductive, the output end may be directly connected to the base. If the substrate is insulative, the film can be formed by connecting the output end to a holder of a conductor coated with an insulating film, which is AC conductive. Thus, plasma (60) is generated in the reaction space. The exhaust system (20) exhausts unnecessary gas through the pressure control valve (21), the turbo molecular pump (22), and the rotary pump (23).

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 space 0.5 ~5KW (per unit area 0.3 ~3W / cm ²⁾
For example, a first high frequency electric field of 1 KW (high energy of 0.6 W / cm ² per unit area) is applied. Furthermore, by applying the AC bias with the second alternating voltage, -200 to -600 on the surface to be formed.
A negative self-bias voltage of V (for example, its output is 500 W) is applied, and the reactive gas accelerated by this negative self-bias voltage is sputtered on the substrate to form a film.
Moreover, it was possible to obtain a dense film.

Of course, the height of the rectangular (rectangular parallelepiped) tubular structure may be 20 cm to 1 m, and one side may be 30 cm to 3 m, depending on the design requirements. The first alternating voltage may also be applied between the front and back, as shown in the drawing from above the device, instead of between the top and bottom.

Thus the terminals on the output side of the symmetrical matching transformer (16)
(4) and (4 ') were set to the ground potential so that the midpoint is on the power source side which should have the sputtering effect on the cathode side. The reactive gas was ethylene or acetylene, for example. Front and rear (not shown) of this reaction vessel have heating or cooling means to keep the substrate at 450 ° C to -100 ° C, typically room temperature. Thus, the Vickers hardness of 2000 on the surface to be formed
Carbon having an amorphous structure or a crystalline structure, which has a Kg / mm ² or more and a large number of CC bonds with a thermal conductivity of 2.5 W / cm deg or more, was generated. Deposition rate is 100 to 10
Had 00Å / min. Particularly, for example, the surface temperature is set to room temperature (without external heating), the AC bias Vpp is set to ± 300 to ± 1000 V by the second alternating voltage, and the DC negative bias is set to -100.
~ -500V, the film forming speed is 100 ~ 200
A / (when methane was used) and 500 to 1000 A / min (when ethylene was used) were obtained. All of these were regarded as good products only under the condition that the Vickers hardness was 2000 Kg / mm ² or more.

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).

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, A coating film containing carbon having an I or N conductivity type as a main component can be formed.

Example 2 This example is an example of producing a silicon nitride film produced by the apparatus used in Example 1.

In Figure 1, disilane (Si ₂ H ₆ ) and ammonia (NH ₃ )
The carrier gas (N ₂ ) and the flow ratio were 1: 3: 5. Further, the first alternating voltage was applied at a frequency of 13.56 MHz and an output of 800 W. A frequency of 50 KHz was applied as the second alternating voltage, and a Vpp voltage of ± 750 V was applied. Self bias
It was -130V. The reaction pressure was 0.05 torr. The film forming temperature is room temperature. Then, a film deposition rate of 3.1 Å / sec was obtained. The silicon nitride film had a refractive index of 1.774 and the etching tray with 1/10 hydrofluoric acid was 3.75Å / sec. Infrared absorption spectrum indicates a silicon nitride film with 880 cm ^-1 Si-N bond
The absorption of Si-O bond was not observed at the wavelength of 1100 cm ^-1 . This 1/10 hydrofluoric acid etch rate is 30 Å / sec when the surface to be formed is on the anode side, even if the substrate temperature is 350 ° C. .

At this time, the substrate used was a final coating on a silicon wafer on which an integrated circuit was formed, or an IC chip formed on a lead frame and further wire-bonded. In this embodiment, the holder is made of aluminum, a second alternating voltage is applied thereto, and a film is formed on the substrate through the insulating film on the upper surface.

Example 3 In this example, the carbon film made in Example 1 was formed on the silicon nitride film made in Example 2.

Generally, if the carbon film is not directly formed on the glass substrate, it causes peeling for long-term use. This is because oxygen and carbon, which are glass components, react with each other to form COx in the form of gas, which causes separation from the interface.

Therefore, in this example, a silicon nitride film was first formed on the glass substrate to a thickness of 100 to 1000Å. Further, after removing the reactive gas for forming the nitride film in the same reaction furnace, the reactive gas for forming the carbon film is introduced, and the carbon film is deposited on the carbon film by 0.1 to 1 μm.
Formed to a thickness of.

Then, even when this substrate was placed in an atmosphere of 85 ° C. and a relative humidity of 85% for 1000 hours, it did not peel at all.

Example 4 This example is an example of producing a silicon oxide film using the apparatus of Example 1. Monosilane N ₂ O and N ₂ were mixed in a ratio of 1: 3: 10. As in Example 2, the first alternating voltage of 13.56 MHz and the second alternating voltage of 50 KHz were formed at room temperature. A film formation rate of 300 to 1000Å / sec was obtained.
This film was also etched at 1/10 HF, but the etch rate was about 50 Å / sec, which was about 1/5 of the etch rate of the plasma CVD silicon oxide film of the anode type at 300 ° C. It is a very dense film and has an infrared absorption spectrum of 1100 cm ^-1 .
The Si-O peak was clearly seen. This silicon oxide film was also formed in a thickness of 0.1 to 1 .mu.m on the wire-bonded substrate on the lead frame as in Example 2, and then plastic molded.

In the case of the silicon oxide film of this example, the humidity resistance was not sufficient, but it was sufficient for stress relaxation and was effective for improving the reliability in the operation life test.

[Example 5] In this example, a substrate having an organic resin formed on a conductor was used as a substrate. A typical example of this is an OPC (Organic Photo Conductor) electrostatic copying machine drum.

In this example, the second alternating voltage was applied to the tubular conductor. Then, a carbon film was formed on the OPC in the same manner as in Example 1 by 100
It was formed with a film thickness of ~ 500Å. The film formation was performed at room temperature.

Other examples of such a substrate include a silicon wafer and a thermal head substrate.

As an example of such a case, it is effective to code 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, the local heat generation of the power transistor section in the semiconductor integrated circuit can be uniformly released to the whole. 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 breakco process, each semiconductor chip is completed by die-bonding and wire-bonding the carbon film coating on the back surface. Let

The examples of the present invention mainly show the method for producing carbon, a film containing carbon as a main component, a silicon nitride film, or a silicon oxide film. However, only silane may be introduced to produce hydrogen-added non-single-crystal silicon 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.

As will be apparent from the above description, the present invention provides a surface of a magnetic disk, an optical disk, a thermal head, or other solid material which is made of an organic resin or a glass, a magnetic material, a metal or a ceramic compounded with the organic resin, a semiconductor or a composite material thereof. A thin film such as carbon or a coating containing carbon as a main component, silicon nitride, or a multilayer film of these. 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 and adhesion to a substrate are 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 the outline of the plasma CVD apparatus of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsunori Sakama 398 Hase, Atsugi City, Kanagawa Prefecture, Semiconducting Energy Laboratory Co., Ltd. (72) Inventor Takeshi Fukada 398, Hase, Atsugi City, Kanagawa Prefecture, Ltd., Semiconducting Energy Laboratory Co., Ltd. 72) Inventor Naoki Hirose 398 Hase, Atsugi City, Kanagawa Prefecture, Semiconducting Energy Laboratory Co., Ltd. (72) Inventor, Mitsunori Tsuchiya, 398, Hase, Atsugi City, Kanagawa Prefecture, Semiconducting Energy Laboratory Co., Ltd. (72) Inventor, Atsushi Kawano, Kanagawa Prefecture 398 Hase, Atsugi-shi, Semi-conductor Energy Laboratory Co., Ltd. (72) Inventor, Kazutoshi Nakashita 398, Hase, Atsugi-shi, Kanagawa Pref., Semi-conductor Energy Laboratory, Inc. (72) Inventor, Junichi Takeyama, 398, Hase, Atsugi-shi, Kanagawa Company Semiconductor Energy Research Institute Examiner Sadao Kinashi

Claims (3)

[Claims] 1. A pair of electrodes is provided on one side and the other side, the pair of electrodes being connected to one end and the other end of a matching coil to apply alternating voltages that are symmetrical or nearly symmetrical to each other, and the matching coil is grounded. Applying a second alternating voltage between the midpoint at the level and the third electrode of the holder or substrate to plasmatize the reactive gas and deposit a reaction product on the substrate. And a method for forming a thin film. 2. The alternating voltage according to claim 1, wherein the alternating voltage is a high frequency electric field, and the third electrode has a negative voltage of 100 to 100 nm.
A method of forming a thin film, characterized in that a cathode having a DC bias of 500 V is superposed. 3. A plurality of holders constituting a third electrode are arranged in parallel or substantially in parallel with each other so as to be spaced apart from each other, and are brought into contact with the back surface of the conductor holder via an insulating film. A method for forming a thin film, which comprises forming a film of a reaction product on the surface of a substrate by disposing the substrate.