TW201814074A - Film forming method and film forming apparatus - Google Patents

Abstract

Through the present invention, a black film having good film quality can be formed stably and at lower cost than by the prior art. A film formation method provided with steps (S101, S102) for disposing a target material so as to face the surface of a substrate, a step (S103) for supplying a gas including a sputtering gas and a reactive gas to a treatment space between the surface of the substrate and the target material, a step (S104) for controlling the atmospheric pressure of the treatment space to a predetermined film formation pressure, and a step (S105) for forming an electric field in the treatment space and generating a plasma of the gas. The target material is titanium, the reactive gas is nitrogen, the film formation pressure is set to at least 3 Pa, and a film of titanium nitride is formed by sputtering on the surface of the substrate.

Description

   Film formation method and film formation device   

The present invention relates to a technique for forming a film on a substrate using plasma sputtering technology.

For example, for the purpose of application to building materials, there is a need for a product in which an opaque black film is formed on the surface of a substrate such as a metal plate. As a technology that can be applied to the purpose of manufacturing such a product, for example, there is a technology described in Patent Document 1 (Japanese Patent Application Laid-Open No. 02-047253). Patent Document 1 describes a method for forming a black film on a substrate by a cathode sputtering method using a solid material containing titanium, aluminum, oxygen, and nitrogen as a target material. Technology. In addition, as a material for forming a black film, carbonitride titanium aluminum is known.

In addition, as a technique for performing film formation by such sputtering with high quality and efficiency, the applicant of the present application has previously disclosed a technique described in Patent Document 2 (Japanese Patent Application Laid-Open No. 2015-193863). In this technology, an inductively coupled plasma is generated by a low-inductance antenna and a magnetron-type rotating cathode in a processing space disposed adjacent to a substrate and a target material as a film formation target. (Induction Coupled Plasma: ICP). In this technology, a high-density and relatively low-temperature plasma can be generated, and a good film can be formed at a high film-forming rate while suppressing damage to a substrate.

The black film described above is a quaternary compound. In order to form such a black film by a plasma sputtering technique, a target material containing four elements, a target material containing titanium and aluminum, and two kinds of reactive gases are required at a predetermined ratio. Therefore, costs are required in the preparation of materials. In particular, since the melting points of aluminum and titanium are greatly different, there is also a problem that it is difficult to alloy. In addition, in a multi-component film formation process, it is necessary to perform film formation while accurately controlling the ratio of each component, and the control for this purpose becomes complicated. In this way, the conventional method for producing a black film is likely to increase the manufacturing cost, and leaves room for improvement in terms of practicality and stability.

The present invention has been developed in view of the above-mentioned problems, and an object thereof is to provide a technology capable of forming a black film with a good film quality at a stable and low cost than conventional methods.

One aspect of the present invention is to provide a film forming method, comprising: a step of arranging a target material facing a surface of a substrate; and supplying a processing space between the surface of the substrate and the target material, including sputtering. A gas and a reactive gas; a step of controlling the gas pressure of the processing space to a predetermined film forming pressure; and a step of forming an electric field in the processing space to generate a plasma of the gas; the target material is titanium The reactive gas is nitrogen, the film forming pressure is 3 Pa or more, and a titanium nitride film is formed by sputtering on the surface of the substrate.

Furthermore, another aspect of the present invention is to provide a film forming apparatus including: a substrate holding means for holding the substrate; and a target holding means for holding the target material to face the surface of the substrate; The gas supply means supplies a gas containing a sputtering gas and a reactive gas in a processing space between the surface of the substrate and the target material; a gas pressure control means is used to control the pressure of the processing space to a predetermined level Membrane pressure; and plasma generation means, which forms an electric field in the processing space to generate the plasma of the gas; the target material is titanium, the reactive gas is nitrogen, and the film formation pressure is 3 Pa or more. A titanium nitride film is formed on the surface by sputtering.

In the past, in the reactive plasma sputtering technology, there is a fear that an abnormal discharge (arcing) may occur when the film forming pressure is increased. Therefore, a pressure lower than about 1 Pa has been reviewed as a film forming pressure. However, the present inventors performed various experiments using a plasma generating device capable of generating a stable high-density plasma even at a higher air pressure, and found that by using titanium as a target material and nitrogen as a reactive gas, In addition, a titanium nitride film formed by forming a film with a film forming pressure of 3 Pa or more will be a good black film. Although the contents and results of the experiments will be described later, the knowledge that the black film can be formed from titanium nitride by appropriately adjusting the film formation conditions is unknown at present.

The film thus formed is essentially composed of the two elements of titanium and nitrogen, and can be formed using only titanium as a target material and only nitrogen as a reactive gas. Therefore, it is easier to control the film formation conditions than the multi-layer film formation technology, and stable film formation can be performed. In addition, as long as the monomer titanium and nitrogen are prepared as the material substances, no special target material is required. Therefore, it is possible to perform low-cost film formation as compared with the prior art described above.

As described above, according to the present invention, since a black film can be formed using a single titanium as a target material and nitrogen as a reactive gas, a black film with good film quality can be formed stably and at a lower cost than conventionally.

1‧‧‧ film forming device

2‧‧‧ heater

3‧‧‧ handling mechanism

5‧‧‧Sputter source

6‧‧‧Reactive gas supply unit (gas supply means)

7‧‧‧Sputtering gas supply unit (gas supply means)

8‧‧‧ Power supply unit

10‧‧‧Vacuum chamber

11‧‧‧ chimney

19‧‧‧ Control Department

31‧‧‧Carrier (base material holding means)

32‧‧‧handling roller

51, 52‧‧‧Rotary cathode (target holding means, magnetically controlled rotating cathode)

53, 54‧‧‧magnet unit (magnetron type rotating cathode)

55, 56‧‧‧rotation drive unit (target holding means)

57‧‧‧ Inductive coupling antenna (plasma generation means)

61‧‧‧Nitrogen supply source

62, 72‧‧‧ Piping

63, 73‧‧‧ Nozzles

64, 74‧‧‧Flow adjustment department

71‧‧‧Sputtering gas supply source

81‧‧‧DC Power

82‧‧‧High-frequency power supply (power supply, plasma generation means)

83‧‧‧ matching circuit

191‧‧‧ Probe

192‧‧‧ Beamsplitter

193‧‧‧Pressure sensor (pressure control means)

194‧‧‧Exhaust pump (pressure control means)

511, 521‧‧‧ base members

512, 522‧‧‧ target materials

531, 541‧‧‧ yoke

532, 542‧‧‧ central magnet

533, 543‧‧‧ Peripheral magnets

534, 544‧‧‧Fixed components

535, 545‧‧‧ support members

571‧‧‧conductor

572‧‧‧Dielectric

B‧‧‧ substrate

PS‧‧‧Processing space

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

FIG. 2 is a schematic diagram showing the measurement results of film color when film-forming conditions have been changed.

FIG. 3 is a schematic diagram showing changes in chromaticity of a film with respect to film forming conditions.

FIG. 4 is a schematic diagram showing the relationship between film formation conditions and film formation rate.

FIG. 5 is a flowchart showing a film forming process of the embodiment.

FIG. 1 is a schematic diagram showing an embodiment of a film forming apparatus of the present invention. More specifically, FIG. 1 is a schematic diagram showing a main configuration of a film forming apparatus 1 suitable for implementing the film forming method of the present invention. In addition, the basic configuration of the film forming apparatus 1 is approximately the same as that described in Japanese Patent Application Laid-Open No. 2015-189800 previously disclosed by the applicant of the present application. Therefore, for matters that are not mentioned in the present specification, such as the overall configuration of the device or the operation principle of each part, refer to this publication, and the main configuration and operation of the device according to this embodiment will be described in detail.

This film forming apparatus 1 refers to an apparatus that forms a film on the surface of a substrate B as a processing target by reactive sputtering. For example, there is a need to blacken a surface of a metal plate as a material for building materials, and the film forming apparatus 1 can be suitably used for producing a material corresponding to such a demand. In the following, it is assumed that a black film made of titanium nitride (TiNx) is formed on the surface of a stainless steel plate as the base material B, and the configuration and operation of the film forming apparatus 1 will be described.

The film forming apparatus 1 includes: a vacuum chamber 10; a conveying mechanism 3 and a sputtering source 5 for conveying the substrate B disposed inside the vacuum chamber 10; and integrated control for controlling the entire film forming apparatus 1 Department 19. The vacuum chamber 10 refers to a hollow box-shaped member having a substantially rectangular parallelepiped shape, and is arranged so that the upper surface of the bottom plate has a horizontal posture. In order to display the directions in the following description uniformly, the XYZ orthogonal coordinate axis is set as shown in FIG. 1. Here, the XY plane is a horizontal plane. The Z-axis system indicates a vertical axis, and more specifically, the (-Z) direction indicates a vertical downward direction.

The conveying mechanism 3 is provided with a carrier 31 that holds the substrate B with its lower surface opened, and a plurality of conveying rollers 32 that abut the lower surface of the carrier 31 to support the carrier 31. And a conveyance drive unit (not shown) that moves the carrier 31 in the X direction by rotating the conveyance roller 32. The conveyance driving unit is controlled by the control unit 19. The conveying mechanism 3 configured as described above conveys the substrate B in the vacuum chamber 10 while keeping the substrate B in a horizontal posture, and moves the substrate B in the X direction. The movement of the substrate B by the conveying mechanism 3 can be reciprocated as shown by the dotted line arrows in FIG. 1 and can be moved in either of the (+ X) direction or (-X) direction.

A sputtering source 5 is provided below the substrate B thus carried in the vacuum chamber 10. The sputtering source 5 is provided with: rotating cathodes 51 and 52; magnet units 53, 54 are respectively provided inside the rotating cathodes 51 and 52; and rotation driving units 55 and 56 are configured to hold the rotating cathodes 51 and 52 while maintaining Rotation; and an induction coupled antenna 57 for generating a high-frequency electric field in the vacuum chamber 10.

The rotating cathode 51 and the magnet unit 53 are integrally configured as a magnetron type rotating cathode. Similarly, the rotating cathode 52 and the magnet unit 54 are integrated to constitute a magnetron type rotating cathode. As described above, the present embodiment has a pair of magnetron-type rotating cathodes arranged at different positions in the X direction. Although a pair of magnetron type rotating cathode systems have mutually symmetrical shapes with respect to the YZ plane, the basic structural systems are the same.

The rotating cathode 51 (52) includes a cylindrical base member 511 (521), which uses the Y direction orthogonal to the paper surface in FIG. 1 as an axial direction, and a target material 512 (522), which covers the base member 511 ( 521). The base member 511 (521) is a conductive body, and is supported by a bearing portion (not shown) provided on the rotation driving portion 55 (56) corresponding to both ends in the Y direction so as to be rotatable about a central axis. The rotation driving unit 55 (56) is controlled by the control unit 19.

The target material 512 (522) is a material including a film formed on the substrate B, and in the example of forming a titanium nitride film, it is metallic titanium. In this way, when the target material has conductivity, the base member can be omitted. That is, the base member may be omitted by using a target material that is formed into a cylindrical shape in advance. In this case, the rotation driving unit 55 (56) is configured to rotate the target material while directly supporting the target material.

In the process of generating plasma in the processing space PS facing the substrate B and the target material 512 (522), the target material exposed in the processing space PS can be rotated by rotating the target material 512 (522). The surface of 512 (522) moves constantly. With this, it is possible to avoid that only a specific position on the surface of the target material 512 (522) is consumed by sputtering, so that the utilization efficiency of the target material can be improved. In addition, since the electric field concentration caused by the local deformation of the target can be suppressed, it is possible to improve the resistance to abnormal discharge such as an arc effect.

The magnet unit 53 (54) disposed inside the rotating cathode 51 (52) includes: a yoke 531 (541) formed of a magnetic material such as a magnetically permeable steel; and a yoke 531 (541) ), That is, a central magnet 532 (542) and a peripheral magnet 533 (543) provided to surround the central magnet 532 (542). The yoke 531 refers to a flat plate-shaped member extending in the Y direction, and is arranged opposite to the inner peripheral surface of the rotating cathode 51.

On the upper surface of the yoke 531, a central magnet 532 extending in the Y direction is arranged on the center line along the longitudinal direction (Y direction). Further, a ring-shaped (endless) peripheral magnet 533 is provided on the outer edge portion of the upper surface of the yoke 531 so as to surround the periphery of the central magnet 532. The central magnet 532 and the peripheral magnet 533 are, for example, permanent magnets. The magnetic systems of the central magnet 532 and the peripheral magnet 533 facing the inner circumferential surface of the rotating cathode 51 are different from each other.

Below the yoke 531 (541), one end of the fixing member 534 (544) can be fixed, and the other end of the fixing member 534 (544) is mounted on a rod-shaped support member 535 (545). The rod-shaped support The member 535 (545) is provided at the center of the rotating cathode 51 (52) so as to extend in the Y direction. The support member 535 (545) is not rotated by the rotation of the rotating cathode 51 (52), so that the position of the fixing member 534 (544) is also fixed. The fixing member 534 provided on the rotating cathode 51 is arranged upward from the supporting member 535 but inclined toward the other rotating cathode 52 side. On the other hand, the fixing member 544 provided on the rotating cathode 52 is arranged obliquely upward from the supporting member 545 and toward the other rotating cathode 51 side. Therefore, a static magnetic field can be concentratedly formed in the processing space PS by the magnet units 53 and 54.

An inductive coupling antenna 57 is provided on the bottom surface of the vacuum chamber 10 so as to protrude toward a space surrounded by the pair of rotating cathodes 51 and 52. The inductive coupling antenna 57 is also called LIA (Low Inductance Antenna; registered trademark of EMD Co., Ltd.), and the surface of the conductor 571 having a substantially U-shape is made of a dielectric 572 such as quartz. Covered structure. The inductive coupling antenna 57 extends through the bottom surface of the vacuum chamber 10 and extends in the Y direction in a state where the U-shape is inverted. A plurality of inductive coupling antennas 57 are arranged at different positions in the Y direction. By adopting a structure in which the surface of the conductor 571 is covered with the dielectric 572, the conductor 571 can be prevented from being exposed to the plasma. Thereby, the constituent elements of the conductor 571 can be avoided from being mixed into the film on the base material B.

The inductive coupling antenna 57 configured in this way can be regarded as a loop antenna with the X direction as the winding axis direction and the number of windings less than 1. For this reason, the inductive coupling antenna 57 has a low inductance. By arranging a plurality of such small antennas in a direction orthogonal to the winding axis direction, it is possible to form an induced electric field for plasma generation described later in a wide range while suppressing an increase in inductance. .

The film forming apparatus 1 further includes a chimney 11 which is arranged in the vacuum chamber 10 so as to surround the periphery of the sputtering source 5. Chimney 11 refers to a cylindrical or box-shaped shielding member whose upper portion is slenderly opened in the Y direction, and has a scattering of plasma generated in a sputtering source 5 or sputtering particles sputtered from a target The range functions as a shield.

The upper surfaces of the rotating cathodes 51 and 52 and the lower surface of the base material B held by the carrier 31 face through the opening in the upper part of the chimney 11. As described later, the space PS surrounded by these is a processing space where a plasma is generated and a target is sputtered and a substrate B is formed into a film.

In the processing space PS, a reactive gas is introduced from the reactive gas supply unit 6, and an inert gas as a sputtering gas is introduced from the sputtering gas supply unit 7. Specifically, the reactive gas supply unit 6 includes a nitrogen supply source 61, a pipe 62 connected to the nitrogen supply source 61, nozzles 63 and 63 provided inside the chimney 11, and a flow rate adjustment unit 64. Is installed in the middle of the pipe 62. The nitrogen supply source 61 supplies nitrogen as one of the materials of the titanium nitride film formed on the base material B in the form of nitrogen. The piping 62 guides nitrogen to the processing space PS. The nozzles 63 and 63 communicate with the nitrogen supply source 61 through a pipe 62 and a flow rate adjustment unit 64.

The nozzles 63 and 63 are disposed above the rotating cathodes 51 and 52 and discharge nitrogen gas as a reactive gas between the rotating cathodes 51 and 52 and the substrate B which are opposed in the processing space PS. The flow rate adjustment unit 64 has a function of controlling the flow rate of nitrogen gas supplied to the processing space PS in accordance with a control command from the control unit 19. The flow rate adjustment unit 64 is preferably capable of automatically controlling the flow rate of nitrogen gas, and may include, for example, a mass flow controller.

On the other hand, the sputtering gas supply unit 7 is provided with a sputtering gas supply source 71, nozzles 73 and 73 that discharge the sputtering gas into the vacuum chamber 10, and a pipe 72 that supplies the sputtering gas supply source 71 and the nozzle 73 And 73; and the flow rate adjustment unit 74 is provided in the middle of the piping 72. The sputtering gas supply source 71 supplies an inert gas, such as an argon gas or a xenon gas, which is introduced into the processing space PS as a sputtering gas.

The pair of nozzles 73 and 73 are disposed on the bottom surface of the vacuum chamber 10 in such a manner as to sandwich the inductive coupling antenna 57 and emit an inert gas as a sputtering gas to the processing space PS in the vacuum chamber 10. The flow rate adjustment unit 74 has a function of controlling the flow rate of the sputtering gas supplied to the processing space PS in accordance with a control command from the control unit 19. The flow rate adjustment unit 74 is preferably capable of automatically controlling the flow rate of the sputtering gas, and may include, for example, a mass flow controller.

An appropriate voltage is applied from the power supply unit 8 between the rotating cathodes 51 and 52 and the inductive coupling antenna 57. Specifically, the base members 511 and 521 of the rotating cathodes 51 and 52 are connected to a DC power supply 81 provided in the power supply unit 8, and an appropriate DC negative potential can be supplied from the DC power supply 81. On the other hand, a high-frequency power source 82 provided in the power supply unit 8 is connected to the inductive coupling antenna 57 through a matching circuit 83, and an appropriate high-frequency voltage can be applied from the high-frequency power source 82. The voltage value or waveform output from each of the DC power source 81 and the high-frequency power source 82 is controlled by the control unit 19.

By providing an appropriate DC potential to the rotating cathodes 51 and 52 from the DC power source 81, it is possible to form the surfaces of the rotating cathodes 51 and 52, more specifically, near the surfaces of the target materials 512 and 522 facing the processing space PS. There is an electric field. As a result, a plasma (magnetron plasma) of a sputtering gas can be generated. That is, the DC power source 81 applies a voltage required for generating a magnetron plasma in the processing space PS to the rotating cathodes 51 and 52 through a static magnetic field formed by the magnet units 53 and 54. For this purpose, an appropriate pulse voltage or AC voltage may be superimposed on the voltage applied to the rotating cathodes 51 and 52.

In addition, by supplying high-frequency power (for example, high-frequency power of 13.56 MHz) to the inductive coupling antenna 57 from the high-frequency power source 82, a high-frequency induced electric field is generated between the inductive coupling antenna 57 and the rotating cathodes 51 and 52. In addition, an inductively coupled plasma of a sputtering gas and a reactive gas supplied to the processing space PS is generated. The plasma generated in this way is also attracted by the static magnetic field formed in the processing space PS. As a result, a high-density plasma can be generated in the processing space PS.

In this way, the titanium surface of the target materials 512 and 522 can be sputtered by the plasma generated in the processing space PS, and formed by attaching titanium particles to the lower surface of the substrate B together with nitrogen as a reactive gas species. Film of titanium nitride. In order to improve the quality of the film formed on the substrate B, a heater 2 is provided in the vacuum chamber 10 on the opposite side of the processing space PS with the substrate B interposed therebetween. The heater 2 has a heat source, such as a ceramic heater, which can be temperature-controlled by the control unit 19, and heats the substrate B to be conveyed so as to face the processing space PS, thereby facilitating the film to be fixed to the substrate B. lower surface.

In addition, the film forming apparatus 1 includes a mechanism for detecting the plasma light emission in the processing space PS, and a mechanism for controlling the air pressure in the processing space PS. Specifically, a probe 191 made of, for example, an optical fiber is disposed near the nozzle 63 that supplies nitrogen to the processing space PS. Part of the plasma light emission generated in the processing space PS is incident on the probe 191. The probe 191 is connected to the spectroscope 192, and the output signal of the spectroscope 192 is input to the control unit 19.

The control unit 19 detects the intensity of the plasma in the processing space PS by a plasma emission method (PEM) based on an output signal of the spectroscope 192. Then, the flow rate adjustment unit 64 is controlled as necessary, and the flow rate of the reactive gas supplied to the processing space PS is controlled.

A pressure sensor 193 is provided in the vacuum chamber 10 to output a signal corresponding to the air pressure in the processing space PS to the control unit 19. The exhaust pump 194 is operated in accordance with a control command provided from the control unit 19 in accordance with the signal and maintains the air pressure in the vacuum chamber 10 at a predetermined value. The exhaust pump 194 is connected to the vacuum chamber 10. By such actions, the air pressure in the processing space PS during film formation, that is, the film formation pressure can be controlled to a predetermined value.

The control unit 19 is provided with a CPU (Central Processing Unit), a memory, a storage, and an interface. The CPU performs various arithmetic processing. The memory and the storage are stored The program or various data executed by the CPU, the interface is responsible for the exchange of information with external devices and users. For example, a general-purpose computer device can be used as the control unit 19.

The film forming apparatus 1 configured as described above is configured by arranging a plurality of inductive coupling antennas 57 which are small antennas with low inductance in the Y direction, and supplying high-frequency power thereto, thereby forming a high-frequency induction electric field for plasma generation . With such a configuration, a low-potential, low-temperature, high-density plasma can be generated. Moreover, by appropriately setting the arrangement of the antennas, a uniform plasma having an arbitrary shape and size can be generated.

Furthermore, by using the rotating cathodes 51 and 52 which function as a magnetron type rotating cathode in combination, a particularly high-density plasma can be concentratedly generated in a limited area in the processing space PS.

Next, a method for forming a black film made of titanium nitride using the film forming apparatus 1 configured as described above will be described. In the past, in reactive plasma sputtering technology, abnormal discharge (arc effect) may occur when the film formation pressure is increased, and the film formation rate is lowered when the film formation pressure is higher, so it is generally carried out. Film formation with relatively low pressure (for example, 1 Pa or less).

On the other hand, the film-forming apparatus 1 of this embodiment can achieve high density, uniformity, and low potential of the plasma by having the configuration described above. Therefore, a film formation process with a higher film formation pressure can be performed. In particular, by using a rotating cathode exposed in the plasma generation space, the target surface of the rotating cathode changes steadily with rotation, and the resistance to arcing can be increased.

The inventor of the present case conducted an experiment of forming a titanium nitride (TiNx) film while changing the film formation conditions with various film formation pressures by using the film formation apparatus 1 having the above-mentioned configuration, and the results were Film-forming conditions for black film with good film quality were achieved for locking.

In the blackening process of the substrate, that is, the process of forming a black film on the surface of the substrate, titanium aluminum oxynitride (TiAlOxNy) or titanium aluminum nitride (TiAlCxNy) is currently known as the material of the black film . Since such a multi-component material requires a special target material, the cost is high. When multiple reactive gases are used, the gas supply system and process control will become complicated. In particular, carbon-based gases have many highly flammable substances, and further safety measures are required when such gases are used.

As long as a black film can be formed from titanium nitride, and the titanium nitride system can be formed from a monomer target material and a monomer reactive gas, it is possible to reduce costs larger than conventional techniques. Although the current titanium nitride film is used as a film for obtaining a metallic color such as gold or bronze, it has not been used as a material for a black film. The inventors of the present invention found that a good black opaque film can be obtained by titanium nitride by appropriately setting the film formation conditions.

Hereinafter, the results of experiments performed by the inventors of the present case and the knowledge and insights obtained from the results will be described. In the experiments described below, the target materials 512 and 522 are made of metal titanium, the reactive gas is made of nitrogen, and the film forming conditions are variously changed to form a film on the stainless steel plate as the base material B. The obtained film system was evaluated for its film color using the L * a * b * color system specified by CIE (Commission Internationale de l'Eclairage; International Lighting Commission). Furthermore, since the film formation rate varies depending on the film formation conditions, in the experiment, the film color was evaluated after film formation to a degree that completely shielded the base color of the stainless steel as the base material B. Therefore, the film formation time and film thickness vary depending on the film formation conditions.

Here, the total flow rate of argon as the sputtering gas and nitrogen as the reactive gas is maintained approximately constant at approximately 200 sccm (standard cubic centimeter per minute), and the total gas flow is changed relative to the total amount of gas. The ratio of the nitrogen gas is set in multiple steps from 0.3 Pa to 5 Pa, and the experimental results of the case where the respective film forming pressures are formed separately will be described as the center.

FIG. 2 is a schematic diagram showing a measurement result of a film color for a combination of a film forming pressure and a nitrogen ratio. The graph shown in the column (a) of FIG. 2 uses the film formation pressure as a parameter, and the nitrogen (N ₂ ) ratio is plotted on the horizontal axis, and the a * value is plotted on the vertical axis. Similarly, the field (b) shows the vertical axis as the b * value, and the field (c) shows the vertical axis as the L * value. As shown in the fields (a) and (b), the a * value and b * value representing the chromaticity of the film show various changes by the film formation pressure or the nitrogen ratio.

On the other hand, as shown in the column (c), the L * value indicating the brightness of the film shows a roughly similar change regardless of the film forming pressure. That is, the L * value is larger in a region where the nitrogen ratio is relatively low, and the L * value is smaller in a region where the nitrogen ratio is higher. Then, a sharp change in the L * value can be seen in a region where the nitrogen ratio is about 10% to 30%. However, it can be understood from the graph in the field (c) that when the film formation pressure is 0.3 Pa or 1.0 Pa, even if the nitrogen ratio is increased, the L * value is not reduced, and the minimum value is still about 60.

FIG. 3 is a schematic diagram showing a change in chromaticity of a film for a combination of a film forming pressure and a nitrogen ratio. More specifically, the results shown in FIG. 2 are schematic diagrams showing how the combination of a * value and b * value of the color tone of the formed film is changed by the film formation pressure and the nitrogen ratio.

The column (a) in Fig. 3 is a graph showing changes in a * value and b * value with respect to the nitrogen ratio when the film formation pressure is fixed at 0.3 Pa. From this, it can be understood that the combination of the a * value and the b * value draws a large loop and fluctuates by the ratio of nitrogen in the gas. Specifically, as the nitrogen ratio increases, a clockwise ring shape is drawn. It can be understood that when the numerical ranges of the a * value and the b * value, which are regarded as achromatic, are set to, for example, 5 or less, the range of the nitrogen ratio will greatly exceed the range and have a unique color.

(b) The fields are drawn with the film formation pressure fixed at 1.0 Pa and the same drawing. Similarly, the fields (c), (d), and (e) are the results when the film formation pressure was set to 3.0 Pa, 4.0 Pa, and 5.0 Pa, respectively. From these, it can be understood that the ring shape becomes smaller as the film forming pressure becomes higher. Especially when the film-forming pressure is 3 Pa or more and less than 3 Pa, a significant difference can be seen in the size of the ring. Further, when the film formation pressure is 4 Pa or more, the a * value and the b * value are not affected by the nitrogen ratio and become about 5 or less. At this time, it can be said that a substantially achromatic film can be obtained without being affected by the nitrogen ratio.

When the film formation pressure is 3.0 Pa, although the a * value and the b * value are relatively low to about 10 or less, there may be cases where the b * value exceeds 10 depending on the value of the nitrogen ratio. Here, when the film formation pressure is also set to 3.0 Pa and the gas flow rate is increased to 500 sccm, as shown in the column (f) in FIG. 3, compared with the example in the column (c), compared with the nitrogen The change in chromaticity of the ratio becomes smaller. In other words, the change in chromaticity can be mitigated by adjusting the gas flow rate.

According to these results, it can be said as follows. That is, when the film formation pressure is less than 3 Pa, the formed film system is relatively bright and has a unique color. Such a film system is hardly a black film. Then, the chromaticity of the film is highly susceptible to changes in film formation conditions. In other words, a small change in film formation conditions can cause a large change in film color. This means that in order to obtain the required chromaticity, or to obtain uniform chromaticity, strict control of film formation conditions is required.

On the other hand, when the film formation pressure is 3 Pa or more, the ratio of nitrogen in the gas and the relatively wide setting range of the gas flow rate can be obtained regardless of any of the L * value, a * value, and b * value. Low, that is, the film can be described as black. Then, since the change of the chromaticity and brightness of the film with respect to the change of the film formation conditions is small, the sensitivity to the change of the film formation conditions is low. In other words, even if the film-forming conditions are somewhat changed, there is still no significant change in the color of the obtained film. Therefore, the strict density required for the control of the film formation conditions can be eased, and a film with less color unevenness can be formed stably even by relatively simple control.

Especially when the film formation pressure is 4 Pa or more, the L * value, a * value, and b * value of the formed film can be maintained even if the film formation pressure, the gas flow rate, and the nitrogen ratio in the gas have changed to some extent. The numerical value of the "black" level is, for example, that the L * value can be maintained below 50, and the a * value and b * value can be maintained below 5 respectively. but. As shown in the column (c) of FIG. 2, since the L * value tends to be higher in a region where the nitrogen ratio in the gas is lower than 20%, the nitrogen ratio is more preferably 20% or more. At this time, a good black film with less color unevenness can be obtained, and the allowable range of film forming conditions required to obtain such a black film is relatively wide. When the film-forming pressure is 3.0 Pa, although the allowable range of the film-forming conditions is slightly narrower than the above, as long as the condition setting is appropriately completed, a good black film can be sufficiently obtained.

FIG. 4 is a schematic diagram showing the relationship between film formation conditions and film formation rate. As shown in the figure, generally, the lower the film forming pressure is, the higher the film forming rate is, and as long as the film forming pressure is fixed, the film forming rate will decrease when the nitrogen ratio in the gas becomes high. However, when the nitrogen ratio becomes higher than a certain level, the change in the film formation rate becomes smaller. When observing the film formation pressure of 3 Pa or more that can obtain a good black film, a relatively high film formation rate can be obtained when the nitrogen ratio is 20% or less. On the other hand, when the nitrogen ratio exceeds 40%, the film formation rate can be obtained. It will be roughly fixed.

When a high film-forming rate is simply required, the nitrogen ratio in the gas may be reduced, for example, it may be set to 20% or less. However, as described above, since the L * value of the film becomes higher in the region where the nitrogen ratio is low, it is preferable to set the nitrogen ratio to 20% or more in consideration of the quality of the black film. Although as long as the nitrogen ratio is set to 20% or higher, the value of the film formation rate itself will become low, but because the sensitivity to changes in film formation conditions will also be lowered, it can also be controlled with high accuracy by the film formation time. Film thickness.

FIG. 5 is a flowchart showing a film forming process of the embodiment. First, titanium base metal 512 (522) is mounted on the base member 511 (521) of the rotating cathode 51 (52) (step S101). Alternatively, the base member 511 (521) on which the target material 512 (522) is surface-mounted may be mounted on the main body of the film forming apparatus 1.

Next, the carrier 31 is provided with a substrate B as a film formation target (step S102). In this state, the opening of the vacuum chamber 10 is closed, and inside the vacuum chamber 10, argon gas is supplied from the sputtering gas supply unit 7 as a sputtering gas, and from the reactive gas supply unit 6 respectively. There is nitrogen as a reactive gas (step S103). Then, based on the pressure value in the vacuum chamber 10 detected by the pressure sensor 193, the control unit 19 causes the exhaust pump 194 to operate so that the air pressure in the processing space PS becomes a predetermined film formation pressure. The air pressure in the vacuum chamber 10 is controlled (step S104).

In this state, the rotating cathodes 51 and 52 rotate, and a predetermined voltage is applied to each part from the power supply unit 8 (step S105). As a result, a plasma generates an electric field in the processing space PS, and a plasma is generated, and sputtering and film formation are started. By scanning and moving the substrate B and sequentially changing the position of the substrate B facing the opening of the chimney 11 (step S106), a titanium nitride film can be formed on the entire lower surface of the substrate B.

When the scanning movement of the substrate B is completed (step S107), each process for film formation is stopped, that is, the power supply from the power supply unit 8, the gas from the reactive gas supply section 6, and the sputtering gas supply section 7 Supply, etc., and stop film formation (step S108). When there is a new base material B as a film formation target (YES in step S109), the process returns to step S102, the base material B is exchanged, and the new base material B is formed into a film. As long as the film formation of all the base materials is completed (NO in step S109), the film formation process is ended.

As described above, in the present embodiment, it is possible to form a film which has not been used as a current film by sputtering at a relatively high film forming pressure which has not been used in a conventional reactive plasma sputtering process. A black film made of titanium nitride (TiNx), which is a black film material. In this film formation method, a black film can be formed using titanium as a target material and nitrogen as a reactive gas. Therefore, it is not necessary to prepare a target made of a multi-component material, and the gas supply system can be made relatively simple. Therefore, a black film can be formed at a low cost.

In addition, since the range of film formation conditions for obtaining a black film is wide, and the sensitivity of the film color to changes in the conditions is low, even if there are some changes in the film formation conditions, the effect on the film color is still small. . Therefore, a good black film with less color unevenness can be obtained stably. In addition, since high precision is not required for controlling film forming conditions, the film forming cost can be further reduced.

Although the film formation pressure is preferably 3 Pa or more, from the viewpoint of widening the allowable range for variations in film formation conditions, it is more preferably 4 Pa or more. When the film formation pressure is 4 Pa or more, even if there is a change in the gas flow rate or the nitrogen ratio in the gas, the change in film color is extremely small, and a black film with less color unevenness can be formed stably. When the film formation pressure is 3 Pa, a stable black film can be formed by appropriately setting the gas flow rate and the nitrogen ratio (that is, the amount of nitrogen supplied to the processing space PS).

A good black film can be obtained in the range of 200 sccm to 500 sccm as the flow rate of the entire gas combining an inert gas (argon) as a sputtering gas and nitrogen as a reactive gas. The ratio of nitrogen in the total gas is in the range of 20% to 80%, and stable film formation can be performed on both the film quality and the film formation rate.

In the plasma generation process using a combination of a low-inductance antenna and a magnetically controlled rotating cathode, it is possible to locally and uniformly generate a low-temperature, low-potential, and high-density plasma. By making the plasma concentrated near the target, the target can be sputtered at a higher rate, and on the other hand, damage to the substrate B can be suppressed. Thereby, a uniform and good titanium nitride film can be formed on the surface of the substrate B.

As described above, in the film forming apparatus 1 of this embodiment, the carrier 31 has a function as the "substrate holding means" of the present invention. On the other hand, the rotary driving sections 55 and 56 have functions as the "target holding means" of the present invention together with the rotary cathodes 51 and 52. The reactive gas supply unit 6 and the sputtering gas supply unit 7 are integrated as a unit and have a function as a "gas supply means" of the present invention.

Further, in the above-mentioned embodiment, the pressure sensor 193 and the exhaust pump 194 are integrated and have a function as the "air pressure control means" of the present invention. The inductive coupling antenna 57 and the high-frequency power source 82 are integrated and have a function as a "plasma generating means" of the present invention. The group of the rotating cathode 51 and the magnet unit 53 and the group of the rotating cathode 52 and the magnet unit 54 each have a function as the "magnetron type rotating cathode" of the present invention.

In addition, the present invention is not limited to the embodiments described above, and various changes other than the above can be made as long as the scope does not depart from the gist thereof. For example, in the above embodiment, although two sets of magnetron type rotating cathodes are provided facing the processing space PS, the rotating cathodes may be one set. In addition, as long as the film can be formed without causing abnormal discharge under the above-mentioned preferable film forming pressure, it may be a flat cathode instead of a rotating cathode.

In addition, the film forming apparatus 1 of the above-mentioned embodiment is provided with a chimney 11 opened upward above the sputtering source 5 and a titanium nitride film is formed on the lower surface of the base material B passing through the upper portion of the opening. However, the positional relationship between the sputtering source 5 and the substrate B as a film formation target is not limited to this. For example, a configuration may be adopted in which a sputtering source is arranged on the side of the substrate conveyed in a substantially vertical posture. As another example, a film can be formed on the upper surface of the substrate transported below the sputtering source, but in this case, it is preferable to take measures to prevent the target from being deposited by sputtering. Contaminants such as small particles generated on the surface and released fall on the surface of the substrate.

Moreover, in the said embodiment, the target regarding "black" is set to 50 or less with respect to L * value, and 5 or less with respect to a * value and b * value, respectively. However, the values of these goals can also be changed depending on the purpose. Therefore, it is necessary to slightly change the above-mentioned preferred film forming conditions.

Moreover, although the stainless steel plate was used as the base material B of the film formation object in the said embodiment, the material of a base material is not limited to this and is arbitrary. For example, the above technique can be applied to the purpose of forming a black film on another metal plate, a glass plate, or the like. In particular, in a configuration capable of generating a low-temperature plasma, a resin-made flat plate or film, etc., which does not have high heat resistance, can be used as a film formation target, and a black film can be formed on the surface. The surface of the substrate is not limited to a flat surface. For example, a substrate having a curved surface may be used as a film formation target.

As mentioned above, as the specific embodiment has been exemplified, in the present invention, the film formation pressure may be 4 Pa or more. According to the knowledge and knowledge of the inventor of the present case, when the film formation pressure is 4 Pa or more, the sensitivity of the film color and film formation rate with respect to the nitrogen supply amount supplied to the processing space becomes extremely low. In other words, the change in the nitrogen supply amount has less influence on the film color and film formation rate. Thereby, film formation with more stable quality can be performed.

As another example, the film formation pressure may be 5 Pa or less. As described above, as long as the film formation pressure is 4 Pa or more, even if the nitrogen supply is further increased, the film quality or film formation rate will not change significantly. Therefore, even if the film-forming pressure is further increased, there is no particular advantage, but rather the probability of occurrence of undesirable phenomena such as arcing is increased. According to the knowledge and knowledge of the inventors of the present invention, when the film forming pressure is 5 Pa or less, problems such as arcing do not occur and good film formation can be performed.

As another example, the volume ratio of nitrogen to the entire gas supplied to the processing space may be 20% or more and 80% or less. By supplying nitrogen to the processing space within such a numerical range, film formation with particularly stable film color and film formation rate can be performed.

For another example, a configuration in which a high-frequency voltage is applied between an inductive coupling antenna and a target material provided to face the processing space to generate a plasma can also be adopted. According to such a configuration, a high-density plasma can be stably generated in a processing space, and a film formation by plasma sputtering can be performed stably.

As another example, a target material and a magnetron-type rotating cathode may be integrated. More specifically, for example, the target holding means may have a magnetron type rotating cathode, and the surface of the rotating cathode may be covered with a target material. By using such a rotating cathode, abnormal discharge such as arcing can be prevented, and the film forming pressure can be increased more than conventionally known, so it is suitable for realizing the film forming conditions of the present invention.

    (Industrial availability)    

The present invention can be used for various purposes of forming an opaque and uniform black film on the surface of a suitable substrate. Although the use of products such as building materials and optical parts may be considered, they are not limited to these and are arbitrary.

Claims (9)

    A film forming method includes the steps of: arranging a target material facing a surface of a substrate; and supplying a gas containing a sputtering gas and a reactive gas in a processing space between the surface of the substrate and the target material. A step of controlling the gas pressure of the processing space at a predetermined film forming pressure; and a step of forming an electric field in the processing space to generate a plasma of the gas; the target material is titanium, the reactive gas is nitrogen, and The film formation pressure is 3 Pa or more, and a titanium nitride film is formed by sputtering on the surface of the substrate.         The film-forming method according to claim 1, wherein the film-forming pressure is 4 Pa or more.         The film-forming method according to claim 1, wherein the film-forming pressure is 5 Pa or less.         The film formation method according to claim 1, wherein a volume ratio of nitrogen to the entire gas supplied to the processing space is 20% to 80%.         The film-forming method according to any one of claims 1 to 4, wherein a high-frequency power source is applied between the inductive coupling antenna provided in front of the processing space and the target material to generate the plasma.         The film forming method according to claim 5, wherein the target material is integrated with a magnetron type rotating cathode.         A film forming device includes: a substrate holding means for holding a substrate; a target holding means for holding a target material facing a surface of the aforementioned substrate; and a gas supply means for a surface of the aforementioned substrate A processing space between the target material and the target material is supplied with a gas including a sputtering gas and a reactive gas; a pressure control means for controlling the pressure of the processing space to a predetermined film forming pressure; and a plasma generating means, An electric field is formed in the processing space to generate a plasma of the gas; the target material is titanium, the reactive gas is nitrogen, and the film forming pressure is 3 Pa or more. A titanium nitride film is sputtered on the surface of the substrate.         The film-forming device according to claim 7, wherein the plasma generating means includes: an inductive coupling antenna, which is provided facing the processing space; and a power source, which is applied between the inductive coupling antenna and the target material. High-frequency voltage.         The film formation device according to claim 8, wherein the target holding means includes a magnetically controlled rotating cathode, and a surface of the rotating cathode is covered with the target material.