JP2001316801A - Plasma processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing method which can more freely control the component (composition) of plasma generated by vacuum discharge. SOLUTION: The method includes generating plasma by vacuum discharge between a cathode (first electrode) 102 and an anode (second electrode) 107, and performing on a substrate 109 a vapor deposition or the like utilizing the plasma. Constituent particles of the plasma include the first evaporized particles 112 from the first electrode, introduced gas particles 115, and also the second evaporized particles 113 from the second electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a plasma processing method. In particular, the present invention relates to a plasma processing method suitable for forming a thin film (evaporated film) or modifying the surface using plasma composed of evaporating particles generated by a vacuum arc.

[0002] Here, plasma processing refers to evaporation of particles containing ions generated as a result of molecular dissociation by plasma discharge.
It means that a deposition film (thin film) is formed by deposition on the surface of a base material, or surface layer modification (such as surface hardening) is performed by implantation.

[0003] Here, description will be made mainly taking vacuum arc discharge as an example, but other discharges not based on vacuum arc discharge,
For example, the present invention can be applied to a processing method using plasma (weakly ionized plasma) generated by glow discharge or the like.

[0004]

2. Description of the Related Art In the surface modification of various mechanical materials, the manufacture of electronic devices, optical filters, and the like, a technique of forming a thin film on the surface of the material is indispensable.

[0005] As a thin film forming technique, a wet film forming method such as a sol-gel method and a spray method, and a chemical vapor deposition method (CVD: Chem.
ical Vapor Deposition, physical vapor deposition (PVD: Phys)
(e.g., ical Vapor Deposition).

In the PVD method which is one of the thin film forming methods,
A typical example is a vacuum arc deposition method (Arc Ion Plating method: AIP
Law).

In the vacuum arc evaporation method, a plasma is generated by arc discharge in a vacuum, a target (cathode: cathode) is evaporated and ionized, and a thin film composed of a cathode (evaporation source) or an evaporation source is mixed with an atmosphere gas. This is a method of forming a reaction film on a substrate.

[0008] The vacuum arc evaporation method is suitable for forming a wear-resistant hard coating on tools, machine parts, and the like because a vaporized film (coating) having a high vapor ionization rate, and having a high density and excellent adhesion can be obtained. And has been attracting industrial attention due to its high productivity ("Kobe Steel Engineering Reports vol.39 No.1 (1989)" p32-3
5 "Hard coating by arc ion plating" and "Vol.41 No.4 (1991)" p103-106 "
Formation of Various Hard Coatings by AIP Method and Its Application ").

[0009]

However, in the vacuum arc vapor deposition method, basically, only a reaction film comprising a cathode (target) and an atmospheric gas can be formed.

Therefore, for example, when a ZnO film mixed with Al is to be formed on a substrate, discharge must be performed using a cathode (cathode) with an alloy in which Al and Zn are mixed.

The above-mentioned alloy cathode used for vacuum arc evaporation is difficult to obtain and relatively expensive. Furthermore, when the above alloy was used as the cathode, it was difficult to arbitrarily control the composition ratio of the produced film because the composition ratio of the produced film depends on the composition ratio of the alloy.

In view of the above, it is an object of the present invention to provide a plasma processing method capable of more freely controlling the constituent components (composition) of plasma generated by vacuum discharge.

[0013]

Means for Solving the Problems The inventors of the present invention have enthusiastically worked on research and development to solve the above-mentioned problems.
If not only the particles evaporated from the cathode and the particles of the introduced gas (process gas) but also the material for forming the anode are plasma constituents, the plasma composition and the composition ratio of the deposited film formed by the plasma can be easily controlled. The following plasma processing method was conceived.

A method for processing plasma by generating plasma by vacuum discharge between a cathode (first electrode) and an anode (second electrode), and processing the substrate by using the plasma. The first evaporating particles from the first electrode,
In addition, in addition to the particles of the introduced gas, the second gas and the second vaporized particles from the second electrode are included.

In the above structure, the second electrode may be a crucible-like electrode, and the crucible-like electrode may be filled with an evaporative substance, so that the plasma comprises particles that include third evaporative particles from the evaporative substance. With this configuration, control of the composition of the particles constituting the plasma becomes easier.

In each of the above structures, a magnetic field is applied to the plasma to cause the plasma to be unevenly distributed in the vicinity of one of the electrodes, thereby converging the plasma to increase the efficiency of plasma heating, and increasing the efficiency of the electrode (the electrode container is filled). (Including evaporative substances) can be increased.

Further, in each of the above structures, an inert third electrode is arranged as a sub-anode (auxiliary anode), and discharge plasma is generated between the first electrode (cathode) and the third electrode. , The amount of evaporation of the second electrode itself and / or the evaporation substance can be controlled.

Usually, when the plasma processing method of the present invention is applied to a vacuum arc evaporation method, the effect of the present invention becomes remarkable.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings. It should be noted that the present invention is not limited to the configuration shown in the drawings, and it goes without saying that various design changes are possible.

FIG. 1 is a schematic model diagram of an apparatus used in a vacuum arc evaporation method according to an embodiment of the present invention.

In this embodiment, basically, plasma is generated by vacuum discharge between a cathode (first electrode) 102 and an anode (second electrode) 107, and a substrate 114 is formed by using the plasma. A plasma processing method for processing is assumed. In the present embodiment, the vacuum discharge is an arc discharge, and the machining is
This is a deposition process. The discharge conditions in the arc discharge are as follows: current: 1 to 600 A (preferably 5 to 300 A);
Voltage: 5 to 80 V (preferably 15 to 50 V), degree of vacuum (low pressure state): 10 ^{-4 to} 10 Pa (preferably 10 ^-2)
５5 Pa).

In this plasma processing method, as the constituent particles of the plasma, in addition to the first evaporated particles 112 from the first electrode (cathode) 102 and the reactive particles 115 of the introduced gas, the second electrode (anode) 107 Second evaporated particles 11 from
3 is included.

Here, the constituent particles of the plasma include not only charged particles (gas ions and electrons) but also neutral particles such as gas molecules and gas atoms.

In the vacuum chamber 101, a first electrode (cathode: cathode) 102, a second electrode (anode: anode) 1
07, high melting point metal (for example, Mo (2610 ° C.), W (3
387 ° C.) and the substrate 109 are disposed. The values in parentheses after the element symbols indicate the melting points at 1013 hPa (1 atm) (the same applies hereinafter).

Each electrode is connected to an external electric circuit via a current introduction terminal 104 so as to be insulated from the vacuum chamber 101.

The trigger electrode 103 is an electrode arranged to generate an arc discharge, and is connected to a first power supply 106 via a current limiting resistor 105. Note that the trigger electrode 103 may be connected to the second power supply 108. A vacuum arc discharge is generated by bringing the trigger electrode 103 into contact with the first electrode 102 once. Further, in order to generate a vacuum arc discharge, a laser induction method or a high voltage pulse induction method may be used.

The vacuum chamber 101 is evacuated by a general-purpose exhaust system 111, and a constant flow rate of gas can be introduced by a general-purpose gas introduction system 110. By controlling the exhaust system 111 and the gas introduction system 110, the pressure in the vacuum chamber 101 can be controlled to be constant.

Here, the material for forming the vacuum chamber 101 is made of an inert (passive) material such as stainless steel. This is for use as a third electrode (sub-anode) described later.

Then, a first power supply 106 is connected between the first electrode (cathode) 102 and the second electrode (anode) 107 to generate a vacuum arc discharge. First power supply 106
Are a DC power supply and a pulse power supply (including a high-frequency power supply).

The material for forming the first electrode (cathode) 102 is not particularly limited as long as it is a conductive solid. Regardless of a metal simple substance, an alloy, an inorganic simple substance, an inorganic compound (metal oxide), etc., they can be used alone or in combination of two or more.

Al, Ti, Zn, C
r, Sb, Ag, Au, Zr, Cu, Fe, Mo, W,
Nb, Ni, Mg, Cd, Sn, V, Co, Y, Hf,
Pd, Rh, Pt, Ta, Hg, Nd, Pb, etc. are used as alloys (metal compounds) as TiAl, AlSi, NdF.
e, inorganic simple substances such as C, Si, etc., and inorganic compounds (ceramics) such as TiO ₂ , ZnO, SnO ₂ ,
ITO (Indium tin 0xide: Y ₃ Sn ₅ O ₁₂ ), In ₂
O _3, Cd ₂ SnO _4, oxides such as CuO, TiN, T
Carbon / nitrides such as iAlN, TiC, CrN, TiCN and the like can be respectively mentioned.

Further, the first electrode 1 of the same or different material
02 may be arranged in the arc discharge system. A variety of plasma compositions can be increased.

In the vacuum arc discharge, ions used for film formation (film formation) are released from the first electrode 102 serving as a cathode, and at the same time, molten fine particles (so-called droplets) having a size of submicron to several tens of microns are discharged. ) Often occurs. When the droplets adhere to the formed film, the characteristics of the film may be deteriorated.

In order to remove the droplet, the structure of the first electrode (cathode) 102 is a magnetic filter type, a shield type, a distributed discharge type, or the like.

On the other hand, the surface of the second electrode (anode) 107 is also as high as the first electrode (cathode) 102 (2000 to 6000).
K), but also at a considerably high temperature (700 to 4000 K) due to Joule heat or the like. For this reason, if the second electrode 107 is formed of a low-melting-point metal, particles can also be evaporated from the second electrode 107 and used as constituent particles of plasma. In this case, the second electrode 1
07 can be placed at any position in the vacuum chamber 101. The shape of the electrode is not particularly limited, and may be a general-purpose shape. As the low melting point metal, Al
(660 ° C), Zn (419 ° C), Sb (630 ° C),
Mg (651 ° C.), Sn (232 ° C.) and the like can be mentioned.

The number of the second electrodes 107 may be one, but by providing a plurality of the second electrodes 107, it is possible to control (diversify) the plasma composition. When a plurality of electrodes are provided, the same type of electrodes can be used, or they can be used to evaporate different materials.

In this embodiment, the vacuum chamber 101 and the first electrode 102 are connected via a power supply 108 so that the vacuum chamber itself can be used as the third electrode (auxiliary anode) 101. Thus, the evaporation of the material of the first electrode 102 can be promoted. The power supply 108
Any of direct current, alternating current and pulse current can be used. Note that the third electrode may not be used and the vacuum chamber 10
Instead of using 1 as the third electrode, a third electrode may be separately arranged in a vacuum chamber.

With the above configuration, the first electrode 102 and the third electrode (vacuum chamber) 101 and the first electrode 102
A vacuum arc discharge is generated between the first electrode 107 and the second electrode 107. As a result, the amount of evaporation of the first electrode 102 and the amount of evaporation of the second electrode 107 can be independently controlled, and the plasma composition can be made wider (diversified).

Then, the substrate 109 is placed in the plasma generated by the above-described method, and the surface of the substrate 109 is provided with vaporized particles of the material forming the first and second electrodes 102 and 107 and reactive introduced gas particles 115. If the mixed film formed by vapor deposition is formed by vapor deposition, it becomes possible to easily form (deposit) the vapor deposition film 114 having a composition ratio that has been difficult to form conventionally.

A direct current bias or a pulse bias may be applied to the substrate 109 in order to control the quality of the generated film.

In particular, if a high-voltage pulse bias is applied so that ions in the plasma can be implanted into the surface layer of the substrate 109, a surface-modified film into which ions of multiple elements are simultaneously implanted can be obtained.

As the introduced gas, a non-reactive gas and a reactive gas may be used in combination. This is because the reactive gas is diluted to facilitate control of the reaction with the evaporated particles. If a reactive gas is used as the introduced gas, the reactive first evaporated particles 112 evaporated from the first electrode 102, the reactive second evaporated particles 113 evaporated from the second electrode 102, and the introduced gas particles (reactive atmosphere gas ) Is obtained. Furthermore,
In order to form a gradient film (the composition gradually changes in the film forming direction), the introduction timing of the different gas may be changed to gradually change the ratio of the reactive gas.

Note that the introduced gas is not always necessary.
That is, when a doped diamond-like carbon film is deposited (deposited), the gas need not be introduced.

As the non-reactive gas, a rare gas such as Ar or He is used. Further, as the reactive gas,
Nitrogen (N ₂ ), oxygen (O ₂ ), hydrocarbon gas (CH ₄ ,
C ₂ H ₆ , C ₂ H ₄ , C ₂ H ₂ etc., carbon oxide (CO,
CO ₂ etc.) can be used.

Since plasma is a good conductor, when a magnetic field is applied, the plasma can be localized near one of the electrodes, and the control of the plasma composition becomes easier.

For example, if a magnetic field is applied near the second electrode (anode), the plasma can be concentrated on the second electrode, and the plasma evaporates more from the second electrode. The plasma concentrates in the vicinity of the surface of the second electrode, and the second electrode itself or the surface of the evaporating substance is heated by the heat of the plasma and ion / electron bombardment, so that evaporation easily occurs. When a plurality of second electrodes are provided, it is possible to easily change the plasma composition by applying a magnetic field only to the second electrode whose evaporation amount is desired to be increased (conversely, the material of the second electrode). If it is desired to suppress the evaporation amount, a magnetic field may be applied near the first electrode so that the plasma is not concentrated near the second electrode.)

FIG. 2 shows that the magnet 11 is located below the second electrode 107.
6 is arranged so as to promote the evaporation of the second electrode (anode) 107.

The plasma 118 is converged on the surface of the second electrode 107 by the magnetic flux 117 generated by the magnet 116,
Increase density. As a result, a part of the surface of the second electrode 107 is locally heated, and the evaporation of the second electrode 107 becomes easier.

To generate a magnetic field for plasma convergence,
Use permanent magnets or electromagnets. Further, it is sufficient that the plasma 118 converges on the surface of the second electrode (anode) 107, and a magnet arrangement different from that in FIG. 2 is also possible.

FIG. 3 shows the first electrode (cathode) in FIG.
10 shows a modification of the external electric circuit connected to the second electrode 107 (anode) and the third electrode (auxiliary anode) 101.

The power source 206 includes the first electrode 102 and the second electrode 1
07. The positive electrode side of the power supply 206 is connected to the third electrode (vacuum chamber) 101 via a current limiting variable resistor 205.

The output current i from the power source 206 includes a current i ₂ flowing between the first electrode 102 and the second electrode 107 and a current i ₃ flowing between the first electrode 102 and the third electrode 103.
And shunted. When the value of the variable resistor 205 is adjusted,
You can control the ratio of i ₂ and i _3. By controlling the current value flowing into the second electrode 107 in this way, the amount of evaporation of the second electrode 107 can be adjusted. Using this method,
Since there is only one power supply, the equipment cost (initial cost) and the operating cost during film formation (running cost) can be reduced.

It is also possible to connect the power supply 206 and the third electrode 101 directly and insert the variable resistor 205 between the power supply 206 and the second electrode 107. Further, in addition to the variable resistor 205 provided between the power supply 206 and the third electrode 101, a similar variable resistor is further provided between the power supply 206 and the second electrode 107 to make the variable resistor 2 It may be individual. By using two variable resistors in this manner, finer control of the current between the electrodes is possible.

FIG. 4 is a schematic model diagram of an apparatus used for a vacuum arc evaporation method according to another embodiment of the present invention.

In this embodiment, in order to more easily control the composition of the plasma, the second electrode (anode) is a crucible-shaped electrode container, and the electrode container can be filled with a volatile substance.

As the evaporative substance, one or more kinds are selected from metals, alloys, semiconductors, dielectrics, organic polymers, ceramic fine particles, and carbon fine particles.

The carbon-based fine particles can be selected from those referred to as fullerenes, nanotubes, carbon microcoils, carbon nanocoils, and the like, in addition to conventional carbon fine particles.

In the vacuum chamber 401, the first electrode 40
2. A crucible-shaped second electrode 403 is arranged and connected to a first power supply 412 via a current introduction terminal 404. In order to converge the vacuum arc plasma generated from the first electrode 402 on the surface of the second electrode 403, the first magnet 405
And a second magnet 408.

Thus, the arc current (electron current) supplied from the first power supply 412 flows along the arrow 419. Then, the material forming the first electrode 402 evaporates from the first electrode 402 as indicated by an arrow 417. Second electrode 40
From 3, the material in the crucible evaporates as indicated by arrow 406. Using the continuous fine particle supply device 421, the second electrode 40
3 can be continuously evaporated.

In order to stabilize the generation of the vacuum arc plasma from the first electrode 402, a ring-shaped third magnet 414
Is arranged. In other words, the discharge itself is stabilized by controlling the movement of the cathode spot on the surface of the first electrode 402 of the vacuum arc discharge by the magnetic field. Further, since the movement position of the cathode spot can be controlled by the magnetic field, the consumption shape of the electrode can be controlled (uniform consumption is possible).

A second power supply 413 is connected between a first electrode (cathode) 402 and a ring-shaped third electrode (auxiliary anode) 410 via a current introduction terminal 404. First electrode 40
2 and the direction in which ions are emitted can be controlled. In addition, by connecting the ring-shaped auxiliary third electrode 411 via the variable resistor 413 for limiting the current, it is possible to stabilize the vacuum arc plasma, control the evaporation amount, and control the ion emission direction. The shape of the third electrode and the auxiliary third electrode may be, for example, a coil shape other than the ring shape.

That is, it is originally desired to discharge between the first electrode 402 and the third electrode 410. However, in this case, since the discharge resistance becomes too high, the auxiliary third electrode 411 is inserted on the way. Then, the auxiliary third electrode 411 is provided on the way.
, The auxiliary third electrode 411 is close to the first electrode 402, and therefore, if the variable resistor (limiting resistance) 413 is not inserted,
The discharge is completed between the first electrode 402 and the auxiliary third electrode 411, and the ion extraction efficiency is greatly reduced. In addition, by inserting a resistance between the first electrode 402 and the auxiliary third electrode 411 to provide no resistance between the first electrode 402 and the third electrode 410, the first electrode 402 can be connected to the third electrode 411. An electric field is formed in the direction toward 410 to define the direction of ion emission.

A ring-shaped fourth magnet 415 is provided to control the direction of diffusion of the generated plasma. The fourth magnet 415 has an action of preventing rapid diffusion of plasma. When the plasma is rapidly diffused, the amount of ions flying to the substrate 409 is greatly reduced.

A fifth ring-shaped magnet 416 is arranged to mix the evaporating substance from the first electrode 402 and the evaporating substance from the second electrode 403.

Various inert / reactive gases can be introduced into the vacuum chamber 401 from the gas inlet 420. As a result, the plasma 418 is a mixed plasma composed of the first evaporated particles from the first electrode 402, the second evaporated particles from the second electrode 403, and the introduced gas particles (including the reactive gas particles). Becomes Substrate 409 in plasma 418
Is obtained, a reaction synthetic film of the evaporated particles can be obtained.

[0066]

According to the plasma processing method of the present invention, by using the above method, it is possible to easily and inexpensively generate plasma having a complex composition composed of multi-element ions, atoms and molecules. Become.

Further, the ratio of the elements constituting the plasma can be easily controlled from various aspects.

Therefore, utilizing the generated plasma,
It is possible to provide a method for easily and inexpensively manufacturing a thin film having a complex composition ratio composed of multiple elements.

[0069]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus shown in FIG. 1 will be described below. Here, the first electrode 102 is made of Zn, the second electrode 107 is made of a water-cooled crucible (electrode container) made of copper, and an evaporative In ₂ O ₃ fine particles were filled as a substance.

Introducing O ₂ (introduced gas) into the apparatus,
The pressure in the apparatus was kept at 0.5 Pa. In this state, a film was formed on the substrate 109 for 5 minutes with an arc current between the first electrode 102 and the second electrode 107 of 30 A.

EDX (Energy Dispersive X-ray Spectr)
When the composition of the formed film was analyzed using a meter (“DX-4” manufactured by Philips Japan), Zn: In: O = 3.
5: 8: 57. From this, the first electrode 102
And the vaporized particles and the introduced gas particles (O ₂ ) of the second electrode 107
It can be seen that a mixed film of Furthermore, when the resulting film was subjected to X-ray diffraction analysis (“RINT-2000” manufactured by Rigaku Corporation), diffraction lines of ZnO and In _x O _x were identified.

According to the same conditions as above, the evaporative substance to be filled in the crucible-shaped second electrode was changed from In ₂ O ₃ to Al fine particles and evaporated from the crucible-shaped second electrode.
A reaction film having a composition of n: Al: O = 42: 2: 56 was obtained.

[Brief description of the drawings]

FIG. 1 is a schematic model diagram showing an example of an arc evaporation apparatus used in an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of a method of converging plasma on a second electrode according to the embodiment of the present invention.

FIG. 3 is a schematic model diagram showing a modification of an external power supply circuit in the arc vapor deposition device in FIG.

FIG. 4 is a schematic model diagram showing an example of an arc evaporation apparatus used in another embodiment of the present invention.

[Explanation of symbols]

 101: vacuum chamber / third electrode (auxiliary anode) 102, 402: first electrode (cathode) 107, 403: second electrode (anode) 109, 409: substrate 401: vacuum chamber 410: third electrode (auxiliary anode) 411: auxiliary third electrode (auxiliary anode) 118, 418: plasma

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Ryuichi Miyano 40 F-term (reference) 40 Sumiyoshi-cho, Toyohashi-shi, Aichi 4G075 AA24 BA08 BB02 BC01 BC04 BD14 CA02 CA15 CA47 DA02 DA03 EA05 EB01 EB41 EC21 4K029 BA44 BA45 BA49 CA01 DB17 4M104 BB04 DD36

Claims (11)

[Claims] 1. A method of processing a substrate by generating plasma by vacuum discharge between a cathode (first electrode) and an anode (second electrode), and using the plasma to form a substrate. A plasma processing method characterized by including, as particles, first evaporated particles from the first electrode and particles of the introduced gas, as well as second evaporated particles from the second electrode. 2. The method according to claim 1, wherein the second electrode is a crucible-like electrode, and the crucible-like electrode is filled with an evaporative substance, so that third plasma particles from the evaporative substance are included as the constituent particles of the plasma. The plasma processing method according to claim 1, wherein: 3. The plasma processing method according to claim 2, wherein a magnetic field is applied to said plasma so that the plasma is localized near one of the electrodes. 4. The plasma processing method according to claim 1, wherein a magnetic field is applied to the plasma so that the plasma is localized near one of the electrodes. 5. An inactive third electrode is arranged as a sub-anode, and a discharge plasma is generated between the first electrode (cathode) and the third electrode, so that the second electrode itself and / or 2. The plasma processing method according to claim 1, wherein the evaporation amount of the evaporating substance is controlled. 6. An inactive third electrode is arranged as a sub-anode, and a discharge plasma is generated between the first electrode (cathode) and the third electrode, so that the second electrode itself and / or 3. The plasma processing method according to claim 2, wherein the evaporation amount of the evaporating substance is controlled. 7. The plasma processing method is a vacuum arc evaporation method, wherein the plasma processing method is a vacuum arc evaporation method.
4. The plasma processing method according to 1. 8. A plasma processing apparatus having a configuration usable for the plasma processing method according to claim 1, 2, 3, or 4. 9. The plasma processing apparatus according to claim 8, wherein said plasma processing apparatus is a vacuum arc evaporation apparatus. 10. A plasma processing apparatus comprising a configuration used for the plasma processing method according to claim 5, wherein the third electrode also serves as a vacuum chamber. 11. The plasma processing apparatus according to claim 10, wherein said plasma processing apparatus is a vacuum arc evaporation apparatus.