JP4370949B2 - Deposition method - Google Patents

Description

  The present invention relates to a film forming method by sputtering using a high resistance material such as an insulator as a target.

Conventionally, there is a sputtering method as a method for forming a film on a substrate. In the sputtering method, for example, when a voltage is applied between the substrate and the target in an inert gas such as argon gas or a reactive gas such as oxygen or nitrogen, the gas is ionized (plasmaized) to generate positive ions. When the positive ions are accelerated and incident on the target, the target is sputtered and particles constituting the target are ejected. The ejected particles are deposited on a substrate disposed opposite to the target to form a film.
At this time, high energy secondary electrons are emitted from the target simultaneously with the particles. The emitted secondary electrons collide with the gas and turn into plasma, thereby sustaining the discharge.

In recent years, a film is formed by sputtering using a high resistance material such as a fluororesin such as polytetrafluoroethylene (PTFE) or an insulator such as SiO ₂ as a target.
Currently, when a film is formed by a sputtering method using a high-resistance material as a target, radio frequency (RF) sputtering in which power having a high frequency of 1 MHz or more, and actually a commercial frequency of 13.56 MHz is applied to the target. The method is used (see, for example, Patent Documents 1 and 2). This is because when a high resistance material is used as a target, the discharge can be continued only by the RF sputtering method, and the film can be formed. For example, the film is formed because the discharge is not sustained by the DC sputtering method in which a DC voltage is applied. Can not.
The main reasons are as follows. That is, when positive ions are incident on the target, the target surface is positively charged. At this time, when the target is a conductive material such as a metal, electrons from the cathode are supplied to the target surface, so that the positive charge on the target surface due to the positive ion incidence is neutralized and the negative potential on the target surface is maintained. The As a result, positive ions are always incident on the target, sputtering and secondary electron emission from the target are maintained, and discharge continues.
However, when the target is a high resistance material such as an insulator, electrons from the cathode are not supplied to the target surface. Therefore, for example, in the DC sputtering method in which a DC voltage is applied to the target, the target surface gradually becomes positively charged, and a negative potential sufficient for positive ions to enter the target cannot be maintained. As a result, the number of positive ions incident on the target and the acceleration voltage at the time of incidence decrease, the number of secondary electrons generated decreases, and the collision probability between gas molecules and electrons decreases, so that the gas is not turned into plasma. As a result, the discharge cannot be maintained.
In contrast, in the RF sputtering method, a negative potential is intermittently applied to the target at a cycle shorter than the time until the target surface is charged, and electrons are supplied to the target surface. Therefore, the charge on the target surface is neutralized and the discharge is maintained. In addition, by applying high frequency power of several tens of MHz, even if the electron density between the target and the substrate is low, the number of collisions between the reaction gas molecules and the electrons increases, and the ion generation efficiency increases, so Maintained.

However, in the RF sputtering method, it is necessary to perform matching using a high-performance matching device that matches impedance with a high-frequency power source. In addition, it is difficult to adjust, and in particular, when the target size is large and application of high power is required, stable discharge is obtained, for example, in film formation on a large area substrate having an area of 0.5 m ² or more. It is difficult. In addition, there is a problem that the power source becomes large and expensive.
JP-A-56-98475 JP 56-98469 A

  The present invention has been made in view of the above problems, and an object thereof is to provide a film forming method capable of forming a film by a sputtering method using a high-resistance material as a target at a low frequency of less than 1 MHz.

As a result of intensive studies to solve the above-mentioned problems, the present inventors installed a conductive material having a specific resistance of 1 × 10 ² Ω · cm or less in a non-erosion region, and applied the magnetic field formed by the magnet to the magnetic field. By capturing the electrons emitted from the conductive material or by supplying the electrons to the ion sheath region using an electron gun, electrons having a density necessary to neutralize the charge on the target surface are obtained. It has been found that the above problems can be solved by supplying the target surface, and the present invention has been completed based on the knowledge.
That is, in the first invention of the present application (hereinafter referred to as the present invention 1), sputtering is performed by using a target made of a material having a specific resistance of 1 × 10 ³ Ω · cm or more and intermittently applying a negative voltage to the target. There is provided a film forming method characterized by applying a negative voltage at a frequency of less than 1 MHz while supplying electrons to the target surface.
The second invention of the present application (hereinafter referred to as “Invention 2”) uses a target made of a material having a specific resistance of 1 × 10 ³ Ω · cm or more and applies a negative voltage to the target to form a film formation method by sputtering. A film forming method is provided, which is performed while supplying electrons to the target surface using an electron gun.

The film formation method of the present invention enables film formation by sputtering using a high resistance material as a target at a low frequency of less than 1 MHz.
Therefore, organic film formation on large area substrates by sputtering method, organic / inorganic mixture film formation, low refractive index film formation in ultraviolet to visible range, water repellency / antifouling property, high insulation and gas barrier properties. It becomes easy to form a film having a high dielectric constant and a low dielectric constant film.

Hereinafter, the present invention will be described in more detail.
The present invention 1 is a film forming method by sputtering using a target made of a high-resistance material having a specific resistance of 1 × 10 ³ Ω · cm or more, and intermittently applying a negative voltage to the target. In this film forming method, a negative voltage is applied at a frequency of less than 1 MHz while supplying electrons to the surface.
The present invention 2 is a film-forming method by a sputtering method using a target made of a material having a specific resistance of 1 × 10 ³ Ω · cm or more, and applying a negative voltage to the target. A film forming method characterized in that the film formation is performed while supplying electrons to the surface.

As a material used for the target, the present invention can be suitably applied to a material having a specific resistance of 1 × 10 ³ Ω · cm or more.
As a material having a specific resistance of 1 × 10 ³ Ω · cm or more, for example, polytetrafluoroethylene (PTFE, specific resistance 1 × 10 ¹⁸ Ω · cm), tetrafluoroethylene / hexafluoropropylene copolymer (FEP, specific resistance) 1 × 10 ¹⁸ Ω · cm), tetrafluoroethylene / ethylene copolymer (ETFE, specific resistance 1 × 10 ¹⁷ Ω · cm), polyvinylidene fluoride (PVDF, specific resistance 2 × 10 ¹⁴ Ω · cm), poly Fluoro-resin such as chlorotrifluoroethylene (specific resistance 1 × 10 ¹⁹ Ω · cm), polyvinyl fluoride (specific resistance 4 × 10 ¹³ Ω · cm), silicon dioxide (specific resistance 1 × 10 ¹² Ω · cm), etc. Can be mentioned.
Among these, an insulator having a specific resistance of 1 × 10 ¹⁰ Ω · cm or more is preferable, an insulator having a specific resistance of 1 × 10 ¹⁰ to 1 × 10 ²⁰ Ω · cm is more preferable, and PTFE and silicon dioxide are particularly preferable.
These may be used alone or in combination of two or more.

  The substrate on which the film is formed is not particularly limited. For example, glass, plastic, metal, ceramics, or the like, or a functional film such as an antireflection film, a reflection mirror, an optical filter, an electromagnetic wave shielding film, or a conductive film on the surface thereof. Can be used, and electronic parts on which wiring or the like is formed can be used.

  In the present invention 1, sputtering is performed by intermittently applying a negative voltage at a frequency of less than 1 MHz. By using a frequency of less than 1 MHz, matching can be easily performed, the configuration of the power source is simplified, and the power source to be used can be reduced in price and size. Moreover, since it is not necessary to provide a matching device etc. that a frequency is 100 kHz or less, it is more preferable. The lower limit is preferably 1 kHz or more because positive charges can be efficiently neutralized.

  From the viewpoint of maintaining stable discharge, the applied positive voltage is preferably 1 kV or less, particularly preferably 10 V or more and 200 V or less. It is preferable that electrons can be efficiently supplied to the target surface because a lower voltage can be obtained.

  In the present invention 1, in the case of a method of installing a conductive material near the target as a material for supplying electrons to the target surface, which will be described later, a positive voltage is applied while a negative voltage is not applied. Is preferred. By doing so, electrons can be efficiently introduced into the target surface. The positive voltage in this case is preferably 10V to 200V.

  In the case of the present invention 2 in which electrons are supplied to the target surface using an electron gun, a DC sputtering method in which a direct negative voltage is applied to the target may be used. In this case, the configuration of the power supply is simpler and preferable. Further, since electrons can be efficiently supplied to the target surface, a method of intermittently applying a negative voltage as in the first aspect of the present invention can also be employed.

  The power source for applying the negative voltage may be any power source that can intermittently apply a negative voltage to the target at a frequency of less than 1 MHz, and a power source device conventionally used for sputtering or the like can be used. . For example, intermittent application can be performed by using a combination of a DC discharge power source conventionally used for DC sputtering or the like and a commercially available pulsed module.

In the present invention, the sputtering method is not particularly limited, and can be performed using a conventionally known sputtering apparatus.
FIG. 1 is a schematic diagram showing an example of a sputtering apparatus that can be used for carrying out the film forming method of the present invention.
This sputtering apparatus is roughly constituted by a target 11, a backing plate 12 in which the target 11 is disposed, and a cathode 13 for applying a negative voltage to the target 11 in a film forming chamber 10 that can be evacuated. A target unit 14, a base body 15 disposed to face the target unit 14, and a base body holder 16 on which the base body 15 is disposed are provided.
Further, a sputtering gas supply source (not shown) such as a gas cylinder is connected to the film forming chamber 10 so that a sputtering gas such as argon gas can be supplied into the film forming chamber 10.
The cathode 13 and the base holder 16 are each connected to a power source (not shown) so that a voltage is applied.

  Film formation using such a sputtering apparatus can be performed, for example, as follows. First, the inside of the film formation chamber 10 is evacuated by an exhaust pump (not shown). When a sputtering gas is introduced into the film forming chamber 10 and power is supplied from a power source connected to the cathode 13 and the substrate holder 16, electrons are generated, plasma is formed, and the sputtering gas is ionized. The generated ions are accelerated and incident in the direction of the target 11, and the target 11 is sputtered to generate particles. The generated particles adhere to the surface of the substrate 15 disposed opposite to the target 11 to form a film.

Examples of such a sputtering apparatus include a bipolar sputtering apparatus and a magnetron sputtering apparatus. Among these, a magnetron sputtering apparatus is preferably used in the present invention.
Magnetron sputtering is performed by forming a magnetic field on the surface side of the target with a magnet provided on the back side of the target. Electrons are restrained by the magnetic field formed near the target, so that ions are efficiently generated. Therefore, a high film formation rate can be obtained.

Hereinafter, the present invention will be described in more detail by taking a magnetron sputtering method which is a preferred embodiment of the present invention as an example.
Examples of the method for supplying electrons to the target surface include the following (a) corresponding to the preferred embodiment of the present invention 1 and (b) corresponding to the preferred embodiment of the present invention 2.
(A) Method of installing a conductive material having a specific resistance of 1 × 10 ² Ω · cm or less in a non-erosion region (b) Method of supplying electrons to the target surface using an electron gun In the present invention, the non-erosion region Is a region where sputtering of the target does not substantially occur, and includes all regions other than the erosion region where sputtering occurs substantially. In the magnetron sputtering method, if the magnitude of the magnetic field is usually 50 gauss or less, substantially no sputtering occurs, that is, it becomes a non-erosion region.

<Method (a)>
As the conductive material used in the method (a), any material may be used as long as the specific resistance is 1 × 10 ² Ω · cm or less. Examples include metals such as iron, nickel, copper, titanium, aluminum, zinc, chromium, molybdenum, zirconium, cobalt, tin, and indium, alloys or compounds containing these metals, carbon, silicon mixed with dopants, and the like. .

More specifically, the method (a) includes, for example, the following methods (a-1), (a-2), (a-3) and the like.
(A-1) By installing a conductive material in a location that is a non-erosion region and an ion sheath region, electrons are generated from the conductive material, and the generated electrons are generated by a magnetic field formed in the vicinity of the cathode. A method of performing charge neutralization by supplying electrons to the ion sheath region by supplying the electrons and supplying electrons of a necessary density to the target surface. Here, the ion sheath region is a positively charged region formed in the plasma near the target when a negative voltage is applied to the target. In this region, positive ions in the plasma are directed toward the target. It is accelerated and incident on the target surface.
That is, in a place that is a non-erosion region and an ion sheath region, sputtering is hardly generated while secondary electrons are generated by the incidence of ions accelerated in the ion sheath region. Therefore, by installing a conductive material in that region, the conductive material supplies electrons to the target surface without being taken into a film formed on the substrate, and discharge is maintained.
However, when the conductive material is intentionally mixed into the film, the conductive material may be provided in a part of the erosion region.

  In the magnetron sputtering method, the ion sheath region is a region where the magnitude of the magnetic field exceeds 0 Gauss, and is usually a region within 10 mm from the target surface. Therefore, in magnetron sputtering, it is preferable to install the conductive material in a place where the magnitude of the magnetic field is greater than 0 gauss and less than 50 gauss, and further in the place where the magnitude of the magnetic field is greater than 0 gauss and less than 20 gauss. It is particularly preferable to install.

(A-2) A conductive material is placed in the non-erosion region, and electrons are emitted by heating at a temperature of 1000 K to 4000 K, for example.

(A-3) In a non-erosion region adjacent to a cathode having a high resistance material target, a cathode having a conductive material as a target is installed, and adjacent to a time when a negative voltage is not applied to the high resistance material target. A negative voltage is applied to the conductive material target installed.
In this case, an electric field gradient is generated between the cathodes when no negative voltage is applied to the high-resistance material target, so electrons in the plasma generated by the discharge of the conductive material target are drawn into the vicinity of the high-resistance material target. , Electrons are supplied to the target surface.
Application of power to both cathodes may be controlled independently using two power supplies, or inverted power may be applied between both cathodes using one power supply. Further, it is not always necessary to apply a negative voltage to the conductive material target at a time when a negative voltage is not applied to the high-resistance material target, and the frequencies of both do not need to match.
In addition, when carbon or the like is used as the conductive material target, when an organic material is used as the high resistance material target, in-line film formation that transports the substrate facing the adjacent high resistance material target and the conductive material target in particular. In the case of using an apparatus, it is preferable because different elements are not mixed, and it is also preferable for the purpose of improving the strength of the film.

<Method (b)>
An electron gun is a device that emits electrons from an electron source. Examples of the electron gun include a thermionic emission type electron gun that emits electrons into a vacuum by heating, a field emission type electron gun that emits electrons into a vacuum by an electric field, and the like.
In the method (b), since electrons can be directly supplied to the target surface, the magnetron sputtering method is not necessarily required. However, since the positive charge on the target surface can be efficiently neutralized, the magnetron sputtering method is used. It is preferable to apply to. In the case of the magnetron sputtering method, electrons are supplied to the vicinity of the cathode, for example, the ion sheath region described above by supplementing the electrons emitted from the electron gun with the magnetic field formed by the magnet installed on the cathode, and Sputtering is maintained by supplying electrons having a density necessary for neutralizing the charge to the target surface to effect charge neutralization.

Hereinafter, the present invention will be described in more detail based on the drawings.
<First Embodiment>
The present embodiment is an embodiment corresponding to the method (a-1) described above.
When a fluororesin is used as the high resistance material, it is preferable to employ the first embodiment.
FIG. 2 shows a schematic schematic configuration diagram of the target unit 14 in the sputtering apparatus shown in FIG. 1, which is preferably used in the present embodiment. 2A is a top view and FIG. 2B is a longitudinal sectional view.
The target unit 14 includes a circular sheet-like target 11, a circular backing plate 12, an annular magnet 21 and a columnar magnet 22 disposed on the back side of the backing plate 12 (the back side of the target 12). And the cathode 13. A water cooling pipe 23 is arranged in the cathode 13 so that the cathode 13 can be cooled.
The magnet 21 is installed with the N pole facing the target 11 side, and the magnet 22 is installed with the S pole facing the target 11 side. Therefore, a ring-shaped magnetic field is formed on the surface side of the target 11.

  In the present embodiment, eight through holes are formed in the target 11 and the backing plate 12 at positions outside the magnet 21. The target 11 is fixed to the backing plate 12 by fitting a screw 24 made of a conductive material into each through hole.

In the present embodiment, the position of the screw 24 is important. That is, since these screws 24 are installed at positions outside the magnet 21 on the target 11, that is, at a location that is an ion sheath region and a non-erosion region, discharge is maintained.
The following reasons can be considered as the reason. That is, since the ring-shaped magnetic field is formed on the surface side of the target 11 as described above, the ionization density is high in the magnetic field, that is, in the region inside the magnet 21. This region becomes a region where the target 11 is sputtered and eroded, that is, an erosion region. On the other hand, in a region (non-erosion region) deviated from this erosion region, the ionization density does not increase, so that the sputtering of the target 11 does not occur much. In this non-erosion region, target particles sputtered from the erosion region tend to adhere, and discoloration or the like due to the deposit may be seen.
However, even in the non-erosion region, ions are incident on the target 11 because it is an ion sheath region to which a negative voltage is applied from the cathode 13. Therefore, if the screw 24 made of a conductive material that easily emits secondary electrons is installed in the ion sheath region and the non-erosion region, a relatively large number of secondary electrons are generated by the incidence of ions. . The generated secondary electrons are captured by the magnetic field formed on the surface side of the target 11 and supplied to the target surface. Thereby, it is thought that discharge is maintained.

  Hereinafter, other embodiments will be described with reference to the drawings. In the embodiments described below, the same reference numerals are given to the components corresponding to the first embodiment, and the detailed description thereof is omitted.

Second Embodiment
In FIG. 3, the typical schematic block diagram of the target unit 14 used by this embodiment is shown. 3A is a top view and FIG. 3B is a longitudinal sectional view.
When silicon dioxide is used as the high resistance material, the second embodiment is usually adopted.
In this embodiment, in the first embodiment described above, the screw 24 made of a conductive material is directly bonded to the backing plate 12 with a low melting point metal material such as indium without using the target 31. This is different from the first embodiment.
The screw 24 is attached via a nut 32 made of a conductive material, and its head protrudes above the surface of the target 31.

<Third Embodiment>
The present embodiment is an embodiment corresponding to the method (a-3) described above. In the present embodiment, another target unit 41 using a conductive material as a target is disposed at a position adjacent to the target unit 14 shown in FIG.
4 and 5 are schematic schematic configuration diagrams of the target unit 14 and the target unit 41 used in the present embodiment. 4 is a top view, and FIG. 5 is a longitudinal sectional view.

In the present embodiment, the target unit 14 has the same configuration as that shown in the first embodiment, except that the shape is square and 12 screws 24 are attached.
The target unit 41 has a square shape, and uses a target 42 made of a conductive material as a target. The twelve screws 24 do not go through the nut 32 and the head is below the surface of the target. The thing of the structure similar to having shown in 2nd Embodiment except being attached so that it may become is used.
Further, the target unit 14 and the target unit 41 are accommodated in cathode covers 43 and 44 that are open above the erosion region, respectively.

The target unit 41 targeting a conductive material may be applied with a negative voltage when no voltage is applied to the target unit 14 targeting a high resistance material or when a positive voltage is applied. That is, a negative voltage may be alternately applied to the target units 14 and 41, and a voltage may not be applied or a positive voltage may be applied when no negative voltage is applied. The negative voltage and the positive voltage may be alternately applied to the target unit 14 or only the negative voltage may be intermittently applied to the target unit 14.
Further, it is not always necessary to apply a negative voltage to the target unit 14 for a time during which no voltage is applied or a positive voltage is applied, and the frequency and the negative / positive voltage application time for one cycle may be different.
Further, the negative voltage applied to the target unit 41 may be a voltage sufficient for generating glow discharge, or may be a voltage smaller than the discharge start voltage.
As described above, when a negative voltage is alternately applied to the target 14 and the target 41, an electric field gradient is generated between the targets 14 and 41. Therefore, electrons generated by applying a negative voltage to the target 41 made of a conductive material move in the direction of the target 14 when a positive voltage is applied to the target 14 or when no voltage is applied, and in the vicinity of the target. It is drawn and supplied to the target surface to neutralize the charge. As a result, discharge is maintained and film formation is possible.

  In addition, although the circular target was illustrated in 1st, 2nd embodiment, and the square target was demonstrated in 3rd Embodiment, this invention is not limited to this, Each may be square or circular, Other shapes may be used. Also, the number and position of the screws can be arbitrarily set within a range not impairing the effects of the present invention.

Hereinafter, the present invention will be described in more detail with reference to examples.
Example 1
First, a target unit having the same configuration as in FIG. 2 was created. That is, 8 holes with a diameter of 12.7 cm and a diameter of 1 mm were prepared on the outer periphery of a PTFE sheet having 8 mm diameter, fixed together with a copper backing plate to the cathode of a magnetron sputtering apparatus with SUS304 screws, and the PTFE sheet was used as the target 11 A SUS304 screw was used as the electron source.
Next, after the film formation chamber was evacuated to 267 μPa, argon gas was introduced into the film formation chamber, and the vacuum valve between the film formation chamber and the exhaust system was adjusted to a degree of vacuum of 6.8 Pa.
When a negative voltage was applied to the cathode using a DC power source and a pulse generation module, and a positive voltage was applied intermittently at a constant period, a discharge was generated on the PTFE target.
After starting the discharge, the vacuum bulb was adjusted to a degree of vacuum of 0.54 Pa, but the discharge was stably sustained. At this time, the negative voltage and the positive voltage set value applied to the cathode were 744 V and 135 V, respectively, the effective voltage and the positive voltage application time of one cycle of negative voltage were each 25 μs, and the frequency was 20 kHz. . The set value of the effective power of the DC power supply was 0.2 kW.
FIG. 6 shows the measurement results of the voltage and current values input to the cathode during discharge. In the graph of FIG. 6, the horizontal axis represents time (1 scale: 2 μsec, between broken line grids: 10 μsec), and the vertical axis represents the voltage and current values applied to the cathode (1 scale: voltage 100 V, current 0. 1A, between broken line grids: voltage 500V, current 0.5A, arrow 1 indicates 0V, and arrow 2 indicates 0A. In the graph, the upper wavy line indicates a voltage waveform, and the lower wavy line indicates a current waveform. From this graph, it can be seen that the discharge occurred continuously.
Further, the shutter was opened, and a film was formed on the glass substrate for 20 minutes. When the contact angle of water was measured after film formation, the water contact angle, which was 30 ° before film formation, was 89 °.
Furthermore, when the film formation chamber was brought to atmospheric pressure and the PTFE sheet after discharge was observed, the erosion region where the most intense sputtering caused by the magnet installed on the cathode in the magnetron sputtering apparatus was observed in white. On the other hand, a non-erosion region in which the reaction product was deposited without sputtering in the same apparatus on the outer periphery was observed in yellow. When the contact angles of water in the erosion region and the non-erosion region were measured, they were 110 ° and 54 °, respectively. From this, it was confirmed that spatter occurred in the erosion region.

Comparative Example 1
A PTFE sheet similar to that of Example 1 was fixed to the cathode of a magnetron sputtering apparatus using a SUS304 screw whose upper surface was covered with a PTFE tape together with a copper backing plate, and the PTFE sheet was used as the target 11.
After the film formation chamber was evacuated to 267 μPa, argon gas was introduced into the film formation chamber, and the vacuum valve between the film formation chamber and the exhaust system was adjusted to a degree of vacuum of 6.8 Pa. A voltage was applied to the cathode using a DC power supply and a pulse generation module, but no discharge occurred. At this time, the setting of the negative voltage and the positive voltage application time in one cycle was 25 μs, respectively, and the setting value of the effective power of the DC power supply was 0.4 kW.

Example 2
A PTFE sheet similar to that of Example 1 was fixed to a cathode of a magnetron sputtering apparatus together with a copper backing plate with a SUS304 screw, the PTFE sheet was used as a target 11, and a SUS304 screw was used as an electron source.
After the film formation chamber was evacuated to 267 μPa, argon gas was introduced into the film formation chamber, and the vacuum valve between the film formation chamber and the exhaust system was adjusted to a degree of vacuum of 6.8 Pa. When a negative voltage was intermittently applied to the cathode using a DC power supply and a pulse generation module, a discharge was generated on the PTFE target. After starting the discharge, the vacuum bulb was adjusted to a degree of vacuum of 0.54 Pa, but the discharge was stably maintained. At this time, the effective voltage of the negative voltage applied to the cathode was 750 V, the time of one cycle and the negative voltage application time were 50 μs and 25 μs, respectively, and the frequency was 20 kHz. Except for the negative voltage application time, it was set to 0V. The set value of the effective power of the DC power source was 0.2 kW.
After opening the shutter and forming a film on the glass substrate for 20 minutes, the contact angle of water was measured and found to be 90 °.

Example 3
A PTFE sheet similar to that of Example 1 was fixed to a cathode of a magnetron sputtering apparatus together with a copper backing plate with a SUS304 screw, the PTFE sheet was used as a target 11, and a SUS304 screw was used as an electron source.
After the film formation chamber was evacuated to 267 μPa, argon gas was introduced into the film formation chamber, and the vacuum valve between the film formation chamber and the exhaust system was adjusted to a degree of vacuum of 6.8 Pa. When a negative voltage with an effective voltage of 920 V and a positive voltage with a set value of 200 V were intermittently applied to the cathode using a DC power source and a pulse generation module alternately at a constant cycle, a discharge was generated on the PTFE target. . After starting the discharge, the vacuum bulb was adjusted to a degree of vacuum of 0.54 Pa, but the discharge was stably maintained. One cycle of negative voltage and positive voltage application time was 25 μs, respectively, and the frequency was 20 kHz. The set value of the effective power of the DC power supply was 0.4 kW.
After opening the shutter and forming a film on the glass substrate for 10 minutes, the contact angle of water was measured and found to be 93 °.

Example 4
A PTFE sheet similar to that of Example 1 was fixed to a cathode of a magnetron sputtering apparatus together with a copper backing plate with a SUS304 screw, the PTFE sheet was used as a target 11, and a SUS304 screw was used as an electron source.
After the film formation chamber was evacuated to 267 μPa, argon gas was introduced into the film formation chamber, and the vacuum valve between the film formation chamber and the exhaust system was adjusted to a degree of vacuum of 6.8 Pa. When a negative voltage with an effective voltage of 925 V and a positive voltage with a set value of 200 V were alternately applied intermittently at a constant cycle to the cathode using a DC power source and a pulse generation module, a discharge was generated on the PTFE target. . After starting the discharge, the vacuum bulb was adjusted to a degree of vacuum of 0.54 Pa, but the discharge was stably maintained. One cycle of negative voltage and positive voltage application time was 50 μs and 25 μs, respectively, and the frequency was 13.3 kHz. The set value of the effective power of the DC power supply was 0.4 kW.
After opening the shutter and forming a film on the glass substrate for 10 minutes, the contact angle of water was measured and found to be 91 °.

Example 5
A PTFE sheet similar to that in Example 1 was fixed to a cathode of a magnetron sputtering apparatus together with a copper backing plate with a SUS304 screw, the PTFE sheet was used as a target 11, and a SUS304 screw was used as an electron beam source.
After the film formation chamber was evacuated to 267 μPa, argon gas was introduced into the film formation chamber, and the vacuum valve between the film formation chamber and the exhaust system was adjusted to a degree of vacuum of 6.8 Pa. When a negative voltage with an effective voltage of 932 V and a positive voltage with a set value of 200 V were alternately applied intermittently at a constant cycle to the cathode using a DC power supply and a pulse generation module, a discharge was generated on the PTFE target. . After starting the discharge, the vacuum bulb was adjusted to a degree of vacuum of 0.54 Pa, but the discharge was stably maintained. One cycle of negative voltage and positive voltage application time was 100 μs and 25 μs, respectively, and the frequency was 8 kHz. The set value of the effective power of the DC power supply was 0.4 kW.
After opening the shutter and forming a film on the glass substrate for 10 minutes, the contact angle of water was measured and found to be 89 °.

Example 6
First, a target unit having the same configuration as in FIG. 3 was created. That is, a SiO ₂ target having a diameter of 10.2 cm and a thickness of 5 mm was fixed to the cathode of the same magnetron sputtering apparatus as in Example 1. At this time, using a SUS304 nut, the top surface of the SUS304 screw was adjusted to be 1 mm higher than the SiO ₂ target surface.
After the film formation chamber was evacuated to 267 μPa, argon gas was introduced into the film formation chamber, and the vacuum valve between the film formation chamber and the exhaust system was adjusted to a degree of vacuum of 6.8 Pa. When a negative voltage was applied to the cathode using a DC power source and a pulse generation module and a positive voltage was intermittently applied at a constant period, a discharge was generated on the SiO ₂ target. After starting the discharge, the vacuum bulb was adjusted to a degree of vacuum of 0.54 Pa, but the discharge was stably maintained. At this time, the effective voltage and positive voltage set value of the negative voltage applied to the cathode are 771 V and 135 V, the negative voltage and positive voltage application time in one cycle are 25 μs and 25 μs, respectively, and the frequency is 20 kHz. It was. The set value of the effective power of the DC power supply was 0.20 kw.
The measurement results of the voltage / current values during discharge are shown in FIG. In the graph of FIG. 7, the horizontal axis represents time (1 scale: 2 μsec, between broken line grids: 10 μsec), and the vertical axis represents the voltage and current values applied to the cathode (1 scale: voltage 100 V, current 0. 1A, between broken line grids: voltage 500V, current 0.5A, arrow 1 indicates 0V, and arrow 2 indicates 0A. In the graph, the upper wavy line indicates a voltage waveform, and the lower wavy line indicates a current waveform. From this graph, it can be seen that the discharge occurred continuously.

Example 7
First, a target unit having the same configuration as that shown in FIGS. In other words, a 1 mm thick PTFE sheet was cut into a 22 cm x 9 cm rectangle in accordance with a 22 cm x 9 cm copper backing plate, and further aligned with the fixing screw hole position of the backing plate, producing 12 screw holes with a diameter of 6 mm on the outer periphery. To do. The PTFE sheet is fixed to the cathode together with the backing plate with a SUS screw, and then a SUS cathode cover is attached to obtain the target 11.
Similarly, after fixing a P-doped Si target (specific resistance: 0.01Ω · cm, 20 cm × 7 cm, 5 mm thickness) bonded to a copper backing plate to another cathode adjacent to the cathode, a SUS cathode cover is attached. The target 42 is attached.
Next, after evacuating the film formation chamber containing these two cathodes to 267 μPa, a mixed gas of argon and oxygen (Ar flow rate: O ₂ flow rate = 8: 2) was introduced into the film formation chamber, and the degree of vacuum was 0.27 Pa. To do. Electric power is applied to the cathode for fixing the PTFE sheet and the cathode for fixing the P-doped Si target by changing the phase at a frequency of 50 kHz using a single power source. That is, a positive voltage is applied to the cathode that fixes the P-doped Si target during the time when a negative voltage is applied to the cathode that fixes the PTFE sheet, and a positive voltage is applied to the cathode that fixes the PTFE sheet. A negative voltage is applied to the cathode that fixes the doped Si target. A stable discharge is obtained on the PTFE target and the P-doped Si target.

Example 8
In Example 7, instead of the P-doped Si target, a carbon target (specific resistance: 0.1 Ω · cm) was used, and the power was changed in the same manner as in Example 7 except that the mixed gas of argon and oxygen was replaced with argon gas. Is applied. Stable discharge is obtained on the PTFE target and the carbon target.

Example 9
As in Example 7, a 1 mm thick PTFE sheet was cut into a 22 cm × 9 cm rectangle, and further aligned with the fixing screw hole positions of a 22 cm × 9 cm copper backing plate to produce 12 screw holes with a diameter of 6 mm on the outer periphery. . The PTFE sheet is fixed to the cathode of the magnetron sputtering apparatus together with the backing plate with a SUS screw, and a SUS cathode cover is attached as a target. Further, a P-doped Si target (specific resistance: 0.01 Ω · cm) bonded to a copper backing plate is fixed to a cathode adjacent to the cathode to which the PTFE sheet is fixed, and then a SUS cathode cover is attached as a target.
After the film formation chamber is evacuated to 267 μPa, a mixed gas of argon and oxygen (Ar flow rate: O ₂ flow rate = 8: 2) is introduced into the film formation chamber so that the degree of vacuum is 0.27 Pa. First, when a negative voltage is applied to a cathode for fixing a P-doped Si target using a DC power source and a pulse generation module and a positive voltage is intermittently applied at a constant period, a discharge is generated on the P-doped Si target. Next, when a negative voltage is applied to the cathode that fixes the PTFE sheet using a DC power source and a pulse generation module different from the DC power source, and a positive voltage is applied intermittently at a constant cycle, a discharge is generated on the PTFE target. Occurs.

Example 10
As in Example 7, a 1 mm thick PTFE sheet was cut into a 22 cm × 9 cm rectangle, and further aligned with the fixing screw hole positions of a 22 cm × 9 cm copper backing plate to produce 12 screw holes with a diameter of 6 mm on the outer periphery. . The PTFE sheet is fixed to the cathode of the magnetron sputtering apparatus together with the backing plate with a SUS screw, and a SUS cathode cover is attached as a target. A carbon target (specific resistance: 0.1 Ω · cm) bonded to a copper backing plate is fixed to a cathode adjacent to the cathode to which the PTFE sheet is fixed, and then a SUS cathode cover is attached as a target.
After the film formation chamber is evacuated to 267 μPa, argon gas is introduced into the film formation chamber and the degree of vacuum is 0.27 Pa. First, when a negative voltage is applied to the carbon target using a DC power source, discharge starts on the carbon target. Next, when a negative voltage is applied to the cathode by using a DC power source and a pulse generation module to fix the PTFE sheet, and a positive voltage is intermittently applied at a constant period, a discharge is generated on the PTFE target. One period of negative voltage and positive voltage application time is 100 μs and 25 μs, respectively, and the frequency is 8 kHz.

Comparative Example 2
In FIG. 3, except for the SUS304 nut (32 in FIG. 3), a SiO ₂ target having a thickness of 5 mm was applied to the same target unit as in Example 6 except that the upper surface of the screw 24 was the same height as the upper surface of the backing plate 12. Fixed. After the film formation chamber was evacuated to 267 μPa, argon gas was introduced into the film formation chamber, and the vacuum valve between the film formation chamber and the exhaust system was adjusted to a degree of vacuum of 6.8 Pa. A voltage was applied to the cathode using a DC power supply and a pulse generation module, but no discharge occurred. At this time, the setting of the negative voltage and the positive voltage application time for one cycle was 25 μs, respectively, and the setting value of the effective power of the DC power supply was 0.4 kW.

Example 11
3 except for the SUS304 nut (32 in FIG. 3) in the same manner as in Comparative Example 2, except that the top surface of the screw 24 is the same as the top surface of the backing plate 12, and the target unit is 5 mm in the same target unit as in Example 6. Secure a thick PTFE target. After the film formation chamber is evacuated to 267 μPa, argon gas is introduced into the film formation chamber to 0.54 Pa. A voltage is applied to the cathode using a DC power source and a pulse generation module, and at the same time, electrons are supplied to the ion sheath region and further to the target surface using a field emission electron gun. The electron beam is incident parallel to the target surface so as to maintain a vertical distance of 1 mm from the target surface. Further, by scanning the electron beam, electrons are supplied to the entire erosion region. At this time, the current value of the electron beam is set to 5 mA. By doing so, a discharge is generated on the PTFE target.

It is a schematic block diagram which shows an example of the sputtering device used in this invention. It is a figure which shows the typical schematic block diagram of the target unit used by 1st Embodiment, (a) is a top view, (b) is a longitudinal cross-sectional view. It is a figure which shows the typical schematic block diagram of the target unit used by 2nd Embodiment, (a) is a top view, (b) is a longitudinal cross-sectional view. It is a top view which shows the typical schematic block diagram of the target unit used in 3rd Embodiment. It is a longitudinal cross-sectional view which shows the typical schematic block diagram of the target unit used in 3rd Embodiment. In Example 1, it is a graph which shows the measurement result of the voltage and electric current value during discharge. In Example 6, it is a graph which shows the measurement result of the voltage and electric current value during discharge.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Film-forming chamber, 11 ... Target, 12 ... Backing plate, 13 ... Cathode, 14 ... Target unit, 15 ... Base | substrate, 16 ... Base | substrate holder, 21 ... Magnet, 22 ... Magnet, 23 ... Water-cooling piping, 24 ... Screw 31 ... Target, 32 ... Nut, 41 ... Target unit, 42 ... Target, 43 ... Cathode cover, 44 ... Cathode cover

Claims (5)

A film forming method using a sputtering method in which a target made of a material having a specific resistance of 1 × 10 ³ Ω · cm or more is used and a negative voltage is intermittently applied to the target while supplying electrons to the surface of the target A film forming method comprising applying a negative voltage at a frequency of less than 1 MHz.   The film forming method according to claim 1, wherein the sputtering method is a magnetron sputtering method in which a magnetic field is formed on the surface side of the target by a magnet installed on the back side of the target. A conductive material having a specific resistance of 1 × 10 ² Ω · cm or less is placed in the non-erosion region, and the electrons emitted from the conductive material are captured by the magnetic field formed by the magnet, so that the electrons are captured on the target surface. The film-forming method of Claim 2 to supply. A film forming method by sputtering using a target made of a material having a specific resistance of 1 × 10 ³ Ω · cm or more and applying a negative voltage to the target, and supplying electrons to the surface of the target using an electron gun A film forming method characterized in that the film forming method is performed. The film forming method according to claim 4, wherein the sputtering method is a magnetron sputtering method in which a magnetic field is formed on the surface side of the target by a magnet installed on the back side of the target.

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