JPH0849072A - Formation of thin film and device therefor - Google Patents

Abstract

PURPOSE:To form a thin film having an almost stoichiometric composition by joining particles sputtered from a target with plasma and a reactive gas separately excited with plasma and supplying the confluence onto the upper face of a substrate. CONSTITUTION:A target 1 is sputtered in a sputtering device 5 provided to a vacuum vessel 3 by high-frequency or DC plasma, and the generated particles are supplied to a deposition field close to a substrate 2. Simultaneously, a reactive gas is excited with high-frequency or DC plasma separately in a plasma device 6 and supplied to the deposition field. Both are joined to form a film on the substrate face. In this case, graphite, carbon, B or BN is used for the target 1 N2 or NH3 is used as the reactive gas, and a thin film consisting of the beta-C3N4, cubic BN, amorphous CNx and BNx having an almost stoichiometric composition and contg. a sufficient amt. of N to exhibit the function is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming method and apparatus using both sputtering and plasma excitation, and particularly stoichiometry in the synthesis of CN _x , BN _{x and the} like having high hardness and chemical stability. Thin film close to the ratio, fine structure,
The present invention relates to a film forming method capable of forming a thin film having a controlled crystal phase and an apparatus thereof.

[0002]

Β-C ₃ N ₄ is a material which is theoretically expected to have a higher hardness than diamond.

On the other hand, diamond-like carbon is applicable to the surface coating of magnetic tapes and magnetic disks because it can be formed into a film at a low temperature, has high hardness, and has excellent sliding characteristics. However, recently, in order to reduce internal stress and stabilize the structure, amorphous CN containing N is used.
_x film formation studies are underway.

Conventionally, β-C ₃ N ₄ and amorphous CN _x
As a typical film forming technique used for forming the film, there is a method using a sputtering device for forming plasma by DC or high frequency by parallel plate electrodes.

As shown in FIG. 2, the sputtering apparatus using the parallel flat plate electrodes described above has one electrode 104 of a pair of parallel flat plate electrodes 102, 104 provided in the vacuum chamber 101 set at the ground potential, and the other of them. Electrode 102
By connecting a DC or high-frequency power source 105 to the battery and introducing a discharge gas (N ₂ + Ar) to perform discharge,
Plasma is formed between the plate electrodes 102 and 104. A magnet may be arranged on the back of the electrode 102 to form high plasma by magnetron discharge. At the same time as the graphite is sputtered by applying a negative potential to the graphite target 103 attached to the electrode 102,
The thin film is formed on the substrate 106 by reacting with plasma-excited N ions / radicals.

[0006]

However, in the above-mentioned conventional sputtering method, since the sputtering and the nitriding and film formation of the sputtered C particles are performed in a single plasma, the following problems occur. .

That is, since the plasma density to be formed and the bias voltage of the target 103 cannot be controlled independently, the supply amount of C particles to be sputtered and N are sputtered.
It is impossible to change the supply amount of ions and radicals separately.

Generally, the supply amount of N ions / radicals is insufficient with respect to the supply amount of C particles, so that a thin film close to the stoichiometric ratio of β-C ₃ N ₄ and a sufficient amount of N for function expression are contained. It is difficult to form an amorphous CN _x thin film,
Further, there is a limit to the controllability of the fine structure and crystal phase.

Further, boron and BN are used as the target 103.
Although it is possible to form a BN _x thin film by using, the same problem as described above occurs.

The present invention is intended to solve the above-mentioned problems, and utilizes sputtering to form stoichiometric ratios of β-C ₃ N ₄ and cubic BN in the formation of films such as CN _x and BN _x. An object of the present invention is to enable formation of an amorphous CN _x or an amorphous BN _x containing a sufficient amount of N, which is close to a thin film, or expression of a function, and control of a fine structure and a crystalline phase.

[0011]

Means for solving the problem will be described with reference to FIG. 1. In the invention of claim 1,
Particles sputtered from the target 1 by high frequency or DC plasma are supplied to the precipitation field near the substrate 2, and a reactive gas that is separately plasma-excited is supplied to the precipitation field, and both are merged to form a film on the surface of the substrate 2. This is what you are going to do.

Further, in the invention of claim 6, as shown in FIG. 1 according to one embodiment, particles sputtered from the target 1 by high frequency or DC plasma are set on the substrate holder 4 in the vacuum container 3. The thin film forming apparatus has a sputtering device 5 for supplying the vicinity of the substrate 2 and a plasma device 6 for supplying a plasma-excited reaction gas near the substrate 2.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the invention of claim 6 will be described with reference to FIG. 1, and the invention of claim 1 will be further described.

In FIG. 1, reference numeral 3 is a vacuum container to which an exhaust device 7 is connected via a pressure regulator 21.

In the vacuum container 3, the substrate 2 on which a film is to be formed is formed.
A substrate holder 4 for setting is set.

A heater 8 is preferably provided on the substrate holder 4 so that the temperature of the substrate 2 during film formation can be controlled. Reference numeral 9 is a temperature controller for controlling heating by the heater 8.

The vacuum chamber 3 includes a sputtering device 5
A plasma device 6 for exciting the reactive gas is provided toward the deposition field near the substrate 2, respectively.

The sputtering device 5 is shown on the right side of the drawing. In the illustrated sputtering device 5, a magnet 11 is provided on the back side of the high frequency electrode 10 in order to improve high frequency efficiency and form high density plasma. It is a magnetron type sputtering apparatus 5. A target 1 is attached to the front surface of the high-frequency electrode 10, and an intermediate electrode 12 for forming stable plasma in front of the target 1 is provided in front of the target 1.

The vacuum chamber 3 and the intermediate electrode 12 are connected to the ground potential, a sputtering gas is introduced near the target 1, and a high frequency power source (generally including a matching device) 13 is supplied.
By applying the high frequency of the high frequency electrode 10 from
Plasma is formed near the target 1 and a negative bias voltage is generated on the surface thereof.

The sputtering device 5 may be any device as long as it sputters the target 1 and supplies the sputtered particles to the deposition field near the substrate 2, and does not have the magnet 11 or the intermediate electrode 12 on the back side of the high frequency electrode 10. But it's okay. Further, instead of the high frequency power source 13, a DC power source may be used to apply a negative bias voltage to the target 1 to form plasma.

As another method of sputtering, there is a method of sputtering the target 1 using an ion source. In this ion beam sputtering method, a high film forming rate cannot be obtained because the ion current incident on the target 1 is small. Further, since the operating pressure is as low as 0.1 mTorr level, stable plasma formation of the reactive gas by the plasma device 6 described later and supply to the deposition field near the substrate 2 or plasma formation in the deposition field near the substrate 2 are performed. Becomes difficult.

On the other hand, the left side in the figure is a plasma device 6, which is a DC type plasma device 6 in which an arc chamber 14 is provided with a hot cathode 15.

By introducing a reactive gas into the arc chamber 14 and heating the hot cathode 15 by the heating power source 16 and applying an arc voltage between the hot cathode 15 and the arc chamber 14 by the arc power source 17, heat is generated. The reactive gas is ionized by the impact of the electron beam emitted from the cathode 15, and plasma is formed. The plasma-excited reactive gas is supplied to the precipitation field near the substrate 2 and merges with the sputtered particles.

A magnet is preferably installed around the arc chamber 14 in order to form a stable and high-density plasma in the arc chamber 14 and to guide the plasma to the deposition field.

The plasma device 6 may be any device capable of supplying a plasma-excited reactive gas to the deposition field. In addition to the DC type plasma device 6 shown in FIG. It may be done. Preferably, stable and high-density plasma can be formed in a wide pressure range, and plasma is formed by electron beam bombardment.
The C-type plasma device 6 and the high-frequency plasma device 6 capable of forming stable plasma in a large area. In particular, the former DC type plasma device 6 can control the dissociation state of the reactive gas by controlling the arc voltage and the arc current.

Further, the plasma device 6 having the same structure as the sputtering device 5 can be used. In this case, the sputtering of the high frequency electrode 10 may be prevented by removing the unnecessary target 1 and connecting the high frequency electrode 10 and the ground with an RF filter.

On the other hand, in order to further improve the controllability of the fine structure, crystal phase, chemical composition, etc. of the thin film formed by controlling the types and energy of the ions and radicals incident on the substrate 2, the precipitation field near the substrate 2 is improved. It is preferable to perform plasma formation.

The substrate holding surface of the substrate holder 4 in this embodiment has a high-frequency electrode 19 provided via an insulating layer 18.
And a high frequency power supply (usually including a matching box)
Twenty are connected to form another plasma device. This plasma device uses the high frequency electric field to generate the substrate 2
Plasma is formed and maintained by accelerating electrons in the vicinity and causing the sputtering gas and the reactive gas to collide and ionize.

The other plasma device described above performs plasma excitation by high frequency and improves the efficiency of high frequency.
A magnet may be provided to perform high-density plasma formation, or plasma may be formed by microwave or electron beam impact.

Next, the thin film forming method of the present invention will be described together with the operation of the thin film forming apparatus of the present invention described above.

First, the exhaust device 7 is operated to activate the vacuum container 3.
After the inside is made to have a required degree of vacuum, a sputtering gas is introduced into the sputtering device 5 and a reactive gas is introduced into the plasma device 6. Next, a high frequency power is applied to the high frequency electrode 10 by the high frequency power supply 13 to form plasma near the target 1, and the hot power supply 16 causes the hot cathode 15
Is heated and an arc voltage is applied between the hot cathode 15 and the arc chamber 14 by the arc power supply 17 to excite the reactive gas into plasma.

As an example of the combination of the target 1 and the reactive gas, in the case of depositing CN _x , the target 1 of graphite or carbon material and N ₂ and / or NH
A reactive gas of ₃ is used. When depositing BN _x ,
A target 1 of boron or BN material is used, and a reactive gas of N ₂ and / or NH ₃ is used. In order to stabilize the plasma and improve the film quality, an inert gas such as Ar or He or H ₂ can be mixed with the reactive gas.

As the sputtering gas, the above reactive gas, an inert gas such as Ar or He, or a mixed gas thereof is used.

For example, when graphite is used as the material of the target 1 and N ₂ is used as both the sputtering gas and the reactive gas, the sputtered C particles react with the N ions / radicals excited by plasma in the vicinity of the target 1. Nitrogen is formed to form an intermediate, CN _x, but N ions / radicals are insufficient with respect to the amount of C particles, and therefore a sufficient amount of N is not contained.

While this intermediate is supplied to the precipitation field,
N ions / radicals are also supplied to the deposition field from the plasma of the reactive gas formed in the plasma device 6, so that the two join together.
Mixed. As a result, nitriding of the intermediate CN _x is further promoted, and a thin film close to the stoichiometric ratio of β-C ₃ N ₄ or an amorphous CN containing a sufficient amount of N for exhibiting the function.
_A thin film is formed on the substrate 2.

The fine structure, crystal layer, and chemical composition of the thin film to be formed are: film formation pressure, target 1 type, sputtering gas and reactive gas types and their plasma excited states, apparatus configuration, substrate 2 temperature. Not only the film forming conditions such as the above, but also the type and energy of ions / radicals incident on the substrate 2 are deeply related. Particularly, as in the thin film forming apparatus shown in FIG. 1, when a plasma can be formed in the deposition field near the substrate 2 to apply a bias voltage to the substrate 2, the fine structure of the thin film, the crystal layer, and the controllability of the chemical composition can be controlled. Can be further increased.

In addition to the above-mentioned CN _x and BN _x , the present invention selects SiN _x , AlN _x , AlN _x , by selecting the material of the target 1, the gas for sputtering and the reactive gas.
TiN _x , ZrN _{x and} other nitrides, SiO _x , AlO _x ,
Oxides such as TiO _x and TaO _x , SiC _x , TiC _x ,
It can be applied to the film formation of carbides such as BC _x .

Next, examples of the invention relating to the present film forming method will be shown.

Examples 1 to 5 A CN _x film formation test was conducted using the thin film forming apparatus shown in FIG. 1, and the composition ratio (N / C) of the obtained film was measured.

Graphite is used as the material of the target 1, and the sputtering gas and the reactive gas are both N ₂
Was used.

The sputtering device 5 has a diameter of 25.4 m.
13. The high-frequency electrode 10 having the graphite target 1 of m, thickness of 3 mm, and purity of 99.999% attached to the high-frequency electrode 10.
The matching device of the 56 MHz high frequency power source 13 was connected to perform plasma formation of the sputtering gas.

The plasma device 6 has a diameter of 70 mm and a length of 1.
00mm stainless steel arc chamber 1
The tungsten hot cathode 15 inside 4 was heated by the heating power source 16 and an arc voltage was applied between the hot cathode 15 and the arc chamber 14 by the arc power source 17 to perform plasma formation of the reactive gas.

The sputtering device 5 and the plasma device 6 are the vacuum container 3 having an outer diameter of 400 mm and a height of 400 mm.
Was attached toward the deposition field near the substrate 2 provided inside.

The substrate holder 4 has a (100) orientation of Si.
The substrate 2 is set, and the inside of the vacuum container 3 is set to 2 × 10 ⁻⁶ Torr by using a composite turbo molecular pump prior to film formation.
Exhausted to. Then, with a mass flow controller, 30 ccm of N ₂ gas was introduced into the sputtering device 5, 20 ccm of N ₂ was introduced into the plasma device 6, and the pressure inside the vacuum container 3 was adjusted to 200 mTorr using the pressure adjusting device 21. .

A high frequency of 200 W is applied to the sputtering apparatus 5 to form plasma, and the target 1 is -120.
A bias voltage of 0V was applied. In addition, the plasma device 6
An arc voltage of 100 V was applied to the heating cathode 15, and the heating current of the hot cathode 15 was adjusted so that an arc current of 3 A was obtained.

The temperature of the substrate 2 was changed by the heater 8 in the temperature range from room temperature to 500 ° C. In addition, in the fifth embodiment, the high-frequency electrode 18 of the substrate holder 4 has 13.5 mm.
A high frequency of 6 MHz is applied to form plasma near the substrate 2 so that the bias voltage of the substrate 2 becomes −50 V.
The high frequency power was adjusted.

After the film formation, ESCA analysis was performed and the N / C ratio was measured. The results are shown in Table 1. As is clear from Table 1, according to the present invention, a CN _x film having a higher N / C ratio can be obtained as compared with Comparative Examples described below.

In particular, the CN _x thin film of Example 5 was β-C ₃ N
_While the C / N ratio of ₄ is 1.33, a composition close to this stoichiometric ratio is obtained. When the microstructure of this sample was observed by a transmission electron microscope, it was found that
It was confirmed by electron beam diffraction that this crystal had a β-C ₃ N ₄ crystal structure.

Comparative Example 1 A film of CN _x was formed using the sputtering apparatus shown in FIG.

A flat plate electrode 1 having a diameter of 160 mm and a graphite target 103 attached in a vacuum container 101.
02 (high frequency electrode) and a flat plate electrode 104 of the same size
The (ground electrodes) are provided so as to face each other. 50 ccm N ₂
After introducing, the pressure in the vacuum vessel 101 is adjusted to 10 mTorr.
adjusted to r, 1000 W of 13.56 MHz high frequency was applied to the plate electrode 102, and the target 103 was -1200.
A bias voltage of V was applied. The temperature of the substrate 106 was room temperature.

Other test conditions and measurement methods were the same as in the examples. The results are shown in Table 1.

Comparative Example 2 Film formation was performed at room temperature in the same manner as in Example except that plasma formation in the plasma device 6 and plasma formation in the vicinity of the substrate 2 were not performed, and the same measurement was performed. went.

The results are shown in Table 1.

Comparative Example 3 A Kuffman type ion source was attached to the vacuum container 3 of the thin film forming apparatus shown in FIG. 1 toward the target 1 of the sputtering apparatus 5, and 5 ccm of N ₂ was introduced into the plasma apparatus 6, and the vacuum container 3 The internal pressure was 0.2 mTorr. High frequency was not input to the sputtering device 5 and plasma was not formed. Instead, the arc voltage 1 was applied inside the Kuffman ion source.
Plasma was formed under the conditions of 00 V and an arc current of 2 A, an ion beam was extracted at an accelerating voltage of 1200 V, and the target 1 was irradiated to perform sputtering.

A high frequency was applied to the high frequency electrode 19 of the substrate holder 4, but it was difficult to form plasma because the pressure was low. Therefore, the introduction of this high frequency was stopped and the film formation was advanced.

The temperature of the substrate 2 is room temperature, and the plasma device 6
The plasma forming conditions and other test conditions were measured in the same manner as in the example. In addition, the plasma device 6
The plasma was unstable and the film formation rate was 1/10 or less as compared with the example.

Table 1 shows the results.

[0058]

[Table 1]

[0059]

The present invention is as described above, and is a thin film having a stoichiometric ratio close to that of β-C ₃ N ₄ or cubic BN, or an amorphous material containing a sufficient amount of N to exhibit its function. CN
_It is possible to form a thin film of _x or amorphous BN _x , and further to control the fine structure, crystal phase and the like of these.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a thin film forming apparatus according to the present invention.

FIG. 2 is an explanatory diagram of a conventional sputtering device.

[Explanation of symbols]

 1 Target 2 Substrate 3 Vacuum Container 4 Substrate Holder 5 Sputtering Device 6 Plasma Device 7 Exhaust Device 8 Heater 9 Temperature Controller 10 High Frequency Electrode 11 Magnet 12 Intermediate Electrode 13 High Frequency Power Supply 14 Arc Chamber 15 Hot Cathode 16 Heating Power Supply 17 Arc Power Supply 18 Insulation Layer 19 High frequency electrode 20 High frequency power supply 21 Pressure regulator

Claims (8)

[Claims] 1. Particles sputtered from a target by high-frequency or DC plasma are supplied to a precipitation field near the substrate, and a reactive gas that is separately plasma-excited is supplied to the precipitation field, and both are merged to form on the substrate surface. A method of forming a thin film, which comprises performing a film. 2. The thin film forming method according to claim 1, wherein the plasma excitation of the reactive gas is performed by high frequency or DC. 3. The thin film forming method according to claim 1, wherein plasma excitation is performed separately in the deposition field. 4. Graphite or a carbon material is used as a target, and N ₂ and / or NH ₃ is used as a reactive gas.
A film of CN _x is formed by using the method of claim 1.
4. A thin film forming method according to any one of 3 to 3. 5. The thin film forming method according to claim 1, wherein B or BN is used as a target, and N ₂ and / or NH ₃ is used as a reactive gas to form a film of BN _x. . 6. A sputtering device for supplying particles sputtered from a target by high frequency or DC plasma to the vicinity of a substrate set in a substrate holder in a vacuum container, and a plasma device for supplying a plasma-excited reaction gas to the vicinity of the substrate. A thin film forming apparatus comprising: 7. The thin film forming apparatus according to claim 6, wherein the plasma apparatus is one for exciting plasma by high frequency or DC. 8. The thin film forming apparatus according to claim 6, further comprising plasma forming means for forming plasma near the substrate.