JP2001140066A - Thin film deposition method and deposition system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deposit a thin film having high characteristics with the incidence of plasma, high energy particles, electromagnetic waves or the like on a substrate suppressed and moreover to deposit a thin film on a substrate of the material easy to be damaged by plasma or the like without injuring the same. SOLUTION: In a thin film deposition method and a device by a transportation type sputtering method in which the inside of a vacuum chamber is arranged with a substrate and a hollow target, a high speed sputtering gas is introduced from one end of the target, a voltage is applied to the target to generate plasma, and sputtering particles generated on the hollow part of the target are transported on the substrate by the sputtering gas and are deposited thereon, an exhaust port exhausting the sputtering gas containing the above sputtering particles is provided in the direction vertical to the central axis of the target, the substrate is arranged at a position on the side of the exhaust port from the central axis or in the exhaust port, and a thin film is deposited in such a manner that the substrate is not influenced by plasma, high energy particles, electromagnetic waves or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for forming a thin film, and more particularly to a method for forming a thin film of a material whose characteristics are easily degraded or deteriorated by plasma, high energy particles, electromagnetic waves, and the like, and from such a material. The present invention relates to a method for forming a thin film on a substrate.

[0002]

2. Description of the Related Art A thin film forming technique using a sputtering phenomenon is capable of forming a film from a crystal to an amorphous state for almost all materials from metals to semiconductors and insulators. , Alloys, etc. are possible, and since they are superior in mass productivity compared to other film forming techniques such as vapor deposition, semiconductors, display devices,
It is used in various fields such as surface processing.

[0003] Since sputtering is premised on the principle of generating plasma, charged particles such as ions and electrons having extremely higher energy than thermal energy, and high energy particles such as sputtered atoms are generated. Utilizing this energy positively, films having high mechanical strength such as adhesion and various functional thin films have been produced and put to practical use. However, as research progresses, for example, GaA
In the case of functional materials such as semiconductors such as s, yttrium, and bismuth-based oxide high-temperature superconductors, in order to further improve their properties, the energy of the particles is precisely controlled and the energy is higher than necessary. It has become apparent that particles need to be removed. On the other hand, the substrate on which a thin film is formed is exposed to high-energy particles and is heated to a high temperature. Therefore, most of the substrates are inorganic substrates. Application of the sputtering method to a system substrate is limited to a very narrow range. For example, in a multilayer wiring of a semiconductor device, only polyimide having relatively high durability from the above viewpoint is currently practically used as an organic interlayer insulating film.

In such a situation, research for controlling the energy of particles to further improve the performance of a functional thin film and research for extending sputtering technology to organic substrates have been actively conducted. For example, a method to control the energy of charged particles by applying a bias to the substrate, an off-axis sputtering method to separate the substrate from the sputtering space, a method to reduce the discharge voltage by optimizing the magnetic field strength of the sputtering cathode magnet, etc. Has been proposed. Furthermore, as a method of forming a thin film on a substrate on which an organic thin film is formed, a Kr or Xe gas is used as a sputtering gas, and a DC sputtering method with an operating pressure of 10 Pa or more reduces the high-speed electron generation rate and reduces A method for reducing the energy of particles to be formed (Japanese Patent Application Laid-Open No. 10-12572),
A method of arranging a coil of the same material as the target material at a distance close to the substrate and applying an AC voltage to restrain electrons and ions near the target surface and prevent incidence on the substrate (JP-A-10-140344) Gazette) has been proposed.

[0005]

However, the above-mentioned conventional methods have advantages and disadvantages, and are not enough to remove high-energy particles from any of electrons, ions, and neutral particles. This is considered to be a factor that hinders progress in improving the characteristics of the used device and the like. In such a situation, the present inventor studied various sputtering methods and conditions thereof, and found that the arrangement of the target and the substrate of the transport type sputtering method using a hollow target, the transport gas flow rate, the operating pressure, and the like, respectively. It has been found that the selection within the relationship allows efficient removal of high energy charged particles and neutral particles before reaching the substrate. When a thin film is further formed on an organic film as in an organic EL device, the final device characteristics are affected not only by high-energy particles but also by electromagnetic waves such as ultraviolet rays radiated from plasma. I understood.

The present invention has been completed based on the findings obtained in the course of examining the above-described conventional problems and solutions, and has as its object the purpose of the present invention is to generate electrons, ions and neutrals generated by discharge. It is an object of the present invention to provide a method and an apparatus for forming a thin film which can suppress the incidence of all high energy particles on a substrate and can form a thin film with higher performance and higher characteristics. Further, the present invention provides a thin film formation method capable of forming a thin film thereon without damaging a substrate on which a layer of a material (such as an organic substance) easily damaged by plasma, high energy particles, or electromagnetic waves is formed. A method and a manufacturing apparatus are provided.

[0007]

In order to achieve the above object, a thin film forming method according to the present invention comprises disposing a substrate and a hollow target in a vacuum chamber, and introducing a high-speed sputtering gas from one end of the target. Then, a voltage is applied to the target to generate plasma, and a sputtered particle generated in a hollow portion of the target is transported by the sputtering gas onto the substrate to be deposited on the substrate by a transport-type sputtering method. An exhaust port for exhausting a sputter gas containing the sputter particles in a direction perpendicular to the central axis of the target, disposing the substrate at a position on the exhaust port side or within the exhaust port from the central axis, and A thin film is formed without being affected by charged particles. Further, a distance between the substrate and the end of the target in the central axis direction is set to be longer than a length of plasma emitted from an end of the target by a gas flow of the sputtering gas.

[0008] In the present invention, the operating pressure is 13 to 133
3 Pa, and the flow rate of the sputtering gas is 1 to 50 m / s.
It is preferable to adjust the flow rate of the sputtering gas and the pumping speed so as to satisfy the following condition. Further, it is preferable to provide a shielding plate in order to prevent plasma and electromagnetic waves or charged particles of the plasma from being incident on the substrate. Further, a negative voltage is applied to the substrate to suppress incidence of electrons on the substrate surface.

A thin film forming apparatus according to the present invention comprises a vacuum chamber having an exhaust port, a substrate holder for holding a hollow target and a substrate disposed inside the vacuum chamber, and a high-speed sputtering from one end of the target. Gas supply means for introducing a gas, applying a voltage to the target to generate plasma, and transporting and depositing sputter particles generated in a hollow portion of the target on the substrate by the sputtering gas. A thin film forming apparatus based on a transport type sputtering method, wherein the exhaust port is provided in a direction perpendicular to a central axis of the target, and the substrate holder is arranged at a position on the exhaust port side or in the exhaust port from the central axis. Features.

Here, it is preferable that a distance between the substrate holder and the end of the target in the direction of the central axis is 10 cm or more, and in a flow path of a sputtering gas between the substrate holder and the target, It is preferable that a shielding plate is disposed at a position where electromagnetic waves emitted from plasma toward the substrate are shielded from the front surface of the substrate holder.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the method and apparatus for forming a thin film according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing one configuration example of the thin film forming apparatus of the present invention. At one end of the vacuum chamber 10, insulators 14, 1
The hollow cathode 12 and the flat anode plate 13 are electrically insulated and fixed via 4 ′ (for example, Teflon or alumina), and the hollow cathode 12 has a hollow target 11 attached thereto. The anode plate 13 is made of a metal material such as SUS, and has a gas inlet 1 at its center.
5, a gas supply pipe 18, a flow control device (M
FC) 19 and a gas supply source (not shown) via a gas purifier 26 to supply a high-purity gas into the target at a desired flow rate. The hollow cathode 12 and the anode plate 13 are connected to a DC power source 17 for generating discharge.
Further, a cooling water pipe for cooling the target is attached to the hollow cathode 12.

At the end of the vacuum chamber 10 opposite to the target, an exhaust port 25 is provided in a direction orthogonal to the central axis of the hollow target 11, and is connected to an exhaust system (not shown). The exhaust system is composed of two systems: a high vacuum exhaust system composed of an oil diffusion pump and an oil rotary pump, and a high flow exhaust system composed of a mechanical booster pump and an oil rotary pump.

In FIG. 1, reference numeral 20 denotes a substrate holder, 21 denotes a substrate, and 22 denotes a shutter for preventing film deposition during pre-sputtering. The substrate is moved from its central axis so that its surface is parallel to the target central axis. It is located on the remote exhaust port side. In this way, a high velocity gas stream is formed from the target to the exhaust, and the sputtered atoms are transported and deposited on the substrate placed in this stream, while at the same time the fast energy particles and the plasma are deposited on the substrate. Suppress the incidence,
Damage to the substrate and the formed thin film can be reduced, and a high-performance thin film can be formed. In the present invention, since the plasma 16 is emitted from the target end by the high-speed sputtering gas flow, the distance between the substrate and the target end in the direction of the target central axis is preferably set to be larger than the emission distance of the plasma, particularly If an organic thin film is formed on the substrate, this distance should be at least 10c.
m is preferable. The reason is that as the plasma moves away from the target, its density decreases sharply,
at a distance of more than 10 cm
This is because the effect of the plasma can be greatly suppressed by separating the electrodes. Further, the distance between the substrate surface and the central axis is preferably 5 cm or more, and the substrate may be arranged inside the exhaust port. With such a substrate arrangement, it is possible to reduce the influence of not only the high energy particles but also the plasma itself and the electromagnetic waves emitted from the plasma. In particular, in the case of a substrate on which an organic thin film is formed, the incidence of electromagnetic waves such as ultraviolet rays and soft X-rays from plasma is restricted, and deterioration due to bond breaking and the like can be suppressed.

In the present invention, as shown in FIG. 2, the substrate holder 20 is provided with a means 24 for applying a bias voltage to the substrate, and a thin film is formed by applying a predetermined negative voltage to the substrate as necessary. The formation can take place. This makes it possible to repel flying electrons and prevent the performance of the substrate and the thin film on the substrate from being deteriorated by the electrons. This substrate bias applying means is particularly effective for forming a thin film on a substrate on which an organic film or another insulating film is formed.

Next, an example of the thin film forming method of the present invention using this thin film forming apparatus will be described. The vacuum chamber 10 is evacuated to a degree of vacuum of about 1 × 10 ⁻⁴ Pa by a high vacuum evacuation system of an oil diffusion pump. Next, the flow controller 19 is set to a predetermined flow rate, a high-purity sputtering gas is introduced into the vacuum chamber 10, the exhaust system is switched to a mechanical booster pump, and the vacuum gauge 27 is set to a predetermined operating pressure. The main valve (not shown) provided on the downstream side of the exhaust port is adjusted. Subsequently, the hollow cathode 1 is
2, a predetermined negative voltage is applied to the target 11 having a hollow shape.
And an anode 13 is generated. After performing the pre-sputtering for a predetermined time, the shutter 22 is opened to start film formation. The sputtered atoms generated inside the target 11 are transported by the flow of the high-speed sputter gas to the substrate 21 disposed at a position separated from the target 11,
A thin film is formed thereon.

In the present invention, the sputter gas is introduced not only for the purpose of impacting the target 11 to generate a sputtering phenomenon but also for the purpose of transporting the emitted sputter atoms onto the substrate 21. Accordingly, the gas species may be any gas that does not react with the target material, and for example, an inert gas such as Ar gas is used. Further, in order to transport the sputtered atoms, a gas flow having a high flow rate is required, and the flow rate is selected according to a desired film forming speed and film quality.
It is preferably set to ５０50 m / s. Within this range, the transport efficiency of the sputtering gas is improved, a practical film formation rate is obtained, the uniformity of the film formation is improved, and a dense film having a small sputter gas content can be obtained. On the other hand, if the speed is higher than 50 m / s, there is a disadvantage that the exhaust system becomes large. Note that the gas flow rate can be determined by the operating pressure, the gas flow rate, and the inner diameter of the target, and by adjusting these, a gas flow having a desired flow rate can be obtained.

The operating pressure may be any pressure near the viscous flow region, but is preferably 13 to 1333 Pa. With this pressure range, high-energy sputter atoms generated by the sputtering phenomenon, neutral recoil gas particles and negative ions rebounding from the target collide with the sputter gas with a higher probability, and the kinetic energy , Can lose direction. As a result, the sputtered atoms that have lost energy can be carried on the substrate surface by forcing it into a high-speed gas flow, and a thin film of the target material can be formed on the substrate. Further, high-energy particles that damage the substrate and the like lose their energy before reaching the substrate, so that damage to the substrate surface and the formed thin film can be suppressed.

As described above, the operating pressure is set to 13 to 1333.
By forming a thin film at Pa and a gas flow rate of 1 to 50 m / s, the energy of the particles can be reduced to the heat energy level, and a dense, high-performance thin film with few defects can be manufactured. . Further, as described above, in the present invention, unlike the conventional sputtering apparatus, the substrate is set at a position distant from the inside of the target generating the plasma and at a position sufficiently distant from the plasma. In addition, damage to the substrate due to the plasma itself and electromagnetic waves such as ultraviolet rays and soft X-rays emitted from the plasma can be reduced.

FIG. 3 shows another embodiment of the present invention. FIG.
As shown in (1), a shielding plate 23 is provided in the flow path of the sputtering gas between the substrate and the target so as to hide the substrate from plasma. Accordingly, it is possible to prevent high-energy particles flying toward the substrate without colliding with the sputtering gas from being incident on the substrate, and to prevent incidence of various electromagnetic waves radiated from the plasma. Then, even if the gas flow velocity increases and the degree to which the plasma is emitted from the target increases, the use of such a shielding plate can reliably prevent the influence of the plasma itself and electromagnetic waves radiated from the plasma. Therefore, in the apparatus having the configuration shown in FIG. 3, for example, when a thin film is formed on a substrate on which an organic thin film is formed, the substrate itself is easily damaged by electromagnetic waves such as charged particles, ultraviolet rays, and soft X-rays. It is suitably applied to the above thin film formation. In the present invention, depending on the shape of the inside of the vacuum chamber, it is preferable to provide a gas flow control member that forms a uniform gas flow,
By making the gas flow uniform, the uniformity of film formation can be improved. For example, the above-mentioned shielding plate may be used also as a gas flow control member.

FIG. 4 is a schematic diagram showing another embodiment of the present invention. In this embodiment, the vacuum chamber 10 and the exhaust port 25 are connected to make the flow of the sputtering gas uniform. With the configuration as shown in the figure, the film forming uniformity is further improved, and without providing the shielding plate shown in FIG.
The incidence of electromagnetic waves from plasma and the direct incidence of high-speed particles can be prevented, and a thin film having the same characteristics as those of the apparatus shown in FIG. 3 can be formed.

In FIGS. 1 to 4, the substrate surface is arranged parallel to the center axis of the target. However, the present invention is not limited to this arrangement, and the substrate is affected by plasma, charged particles, electromagnetic waves and the like. The substrate may be placed in any position, or the substrate may be placed in any position as long as measures are taken to avoid these effects. In the above description, the DC sputtering method using a DC power supply has been described, but the present invention is not limited thereto.
It is also possible to perform high-frequency sputtering using power supplies of various frequencies. For example, using a dielectric target, a yttrium or bismuth-based oxide high-temperature superconductor thin film or a strontium-based ferroelectric thin film used for a DRAM can be formed. Also, a semiconductor insulating film,
It can be suitably applied to the formation of a protective film. In addition, InP,
The present invention can also be applied to compound semiconductors that are vulnerable to plasma such as GaAs. Here, as the sputtering gas, a mixture of the above inert gas and a gas containing a thin film component element may be used. Needless to say, these compound thin films and the like can also be formed by reactive sputtering using a metal target and a DC power supply. In this case, it may be arranged so that the reactive gas is injected into the sputtering gas flow at the target outlet.

In the present invention, the hollow target is not particularly limited as long as it has a hollow shape in which gas can flow and plasma can be generated. The cross section may be circular, square, or slit. The desired pressure and gas flow rate determine the gas flow rate at the target outlet to be the desired flow rate. Further, the operating pressure of the sputtering is adjusted so that the mean free path of the sputtered particles becomes sufficiently smaller than the target diameter.

In order to confirm the effect of the present invention, an experiment was conducted in which a cathode was formed on an organic EL film which was easily damaged by plasma, high energy particles, electromagnetic waves, etc., and an EL device having the structure shown in FIG. Fabrication was performed and the thin film formation method was evaluated. First, an anode (I) was placed on a 5 cm square glass plate 71.
TO) 72, a hole injection layer (MTDATA) 73, a hole transport layer (α-NPD) 74, and a light emitting layer (Al oxine complex Alq ₃ ) 75 on a substrate in which 2 mm × 2
A mask having an opening of mm was placed, and a cathode film (Mg / Ag) 76 was formed using an apparatus having the configuration shown in FIG.

Here, the target has an inner diameter of 40 mm,
The main valve was adjusted such that a cylindrical target having an outer diameter of 50 mm and a length of 60 mm was used, the flow rate of Ar gas was 500 sccm, and the pressure in the vacuum chamber was 133 Pa.
Note that a mechanical booster pump having a displacement of 280 m ³ / h was used as the high flow rate exhaust system. The substrate is located 10 cm away from the target end and 7
It was placed just above the exhaust port at a distance of cm. When plasma was generated under the conditions of this experimental example, the plasma was emitted from the end of the target by about 5 cm. As described above, Mg / Ag
The film was formed for 10 minutes.

With respect to the manufactured EL element, an anode (IT
O) 72 and a cathode (Mg / Ag) 76 were applied with a DC voltage to evaluate the device performance. FIG. 6 and Table 1 summarize typical examples of film forming conditions and results.

[Table 1] As shown in Table 1 and FIG. 6, high-intensity light emission with a light emission start voltage of 10 V or less and a peak luminance of 12000 cd / m ² can be confirmed as initial performance, and characteristics similar to those obtained when a cathode is formed by an evaporation method are obtained. I was able to.

On the other hand, for comparison, an element manufactured in the same manner except that the substrate surface was arranged perpendicular to the center axis of the target hardly emitted light, or the intensity of emitted light was extremely weak. From this, it was found that the cathode forming method of the present invention can form a binary metal thin film without damaging the functional organic thin film of the substrate. In addition, an EL element was manufactured in the same manner using the apparatus shown in FIGS. 3 and 4, and the element performance was evaluated.
Each of the luminance curves had substantially the same shape as that of FIG. 6, and as a whole, a luminance curve shifted to a low voltage side of 1.5 V and 1.0 V was obtained. That is, as shown in FIGS. 3 and 4, it was found that by arranging the substrate outside the field of view of the plasma, damage to the substrate could be reduced and a device with higher characteristics could be manufactured. This seems to suggest that ultraviolet rays and the like radiated from the plasma affect the characteristics of the functional thin film.

[0027]

As is clear from the above description, according to the present invention, any of high-energy particles of electrons, ions and neutrals generated by electric discharge can be suppressed from entering the substrate. Oxide film high-temperature superconductor, ferroelectric, etc.
Further improvement in performance of various functional thin films can be realized. Also,
Not only high-energy particles but also a structure that reduces the influence of plasma makes it possible to form thin films of various materials on substrates, such as organic films, which are extremely susceptible to deterioration and deterioration due to plasma, etc. In addition, the application range of the thin film forming technology can be greatly expanded. That is, according to the present invention, not only functional elements such as organic EL elements, but also resins other than polyimide can be used for the organic interlayer insulating film of the multilayer wiring, so that higher integration and higher performance of semiconductor devices can be achieved. Can contribute to.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing one configuration example of a thin film forming apparatus of the present invention.

FIG. 2 is a conceptual diagram showing another configuration example of the thin film forming apparatus of the present invention.

FIG. 3 is a conceptual diagram showing another configuration example of the thin film forming apparatus of the present invention.

FIG. 4 is a conceptual diagram showing another configuration example of the thin film forming apparatus of the present invention.

FIG. 5 is a schematic sectional view showing an example of an organic EL element structure.

FIG. 6 is a graph showing voltage / luminance and voltage / current characteristics of an organic EL element.

[Explanation of symbols]

 Reference Signs List 10 vacuum chamber, 11 target, 12 hollow cathode, 13 anode, 14, 14 'insulator, 15 gas inlet, 16 plasma, 17 DC power supply, 18 gas supply pipe, 19 flow control device (MFC), 20 substrate holder Reference Signs List, 21 substrate, 22 shutter, 23 shield plate, 24 DC power supply, 25 exhaust port, 26 gas purifier, 27 vacuum gauge, 71 glass substrate, 72 anode, 73 hole injection layer, 74 hole transport layer, 75 light emitting layer , 76 cathode.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K007 AB18 CA01 CB01 CB03 DA00 DB03 EB00 FA01 4K029 AA11 AA24 CA05 CA13 DA02 DA10 EA00 EA03 EA04

Claims (9)

[Claims] 1. A substrate and a hollow target are provided in a vacuum chamber, a high-speed sputtering gas is introduced from one end of the target, a voltage is applied to the target to generate plasma, and the hollow of the target is generated. A method of forming a thin film by a transport sputtering method in which sputter particles generated in a portion are transported and deposited on the substrate by the sputter gas, wherein the sputter gas containing the sputter particles in a direction perpendicular to a central axis of the target is applied. Providing an exhaust port for exhausting, arranging the substrate at a position on the exhaust port side from the central axis or in the exhaust port, and forming a thin film so that the substrate is not affected by plasma and high energy particles. A thin film forming method. 2. The apparatus according to claim 1, wherein a distance between the substrate and the end of the target in the central axis direction is longer than a length of plasma emitted from the end of the target by the sputtering gas. 3. The method for forming a thin film according to item 1. 3. An operating pressure of 13 to 1333 Pa and a flow rate of the sputtering gas of 1 to 50 m / s.
3. The method according to claim 1, wherein the sputtering gas flow rate and the pumping speed are adjusted. 4. The thin film forming method according to claim 1, further comprising a shielding plate for preventing electromagnetic waves radiated from plasma from being incident on the substrate. 5. The method according to claim 1, wherein a negative voltage is applied to said substrate to suppress the incidence of electrons on the substrate surface.
3. The method for forming a thin film according to item 1. 6. The method according to claim 1, wherein at least the surface of the substrate is made of an organic material. 7. A vacuum chamber having an exhaust port, a substrate holder provided inside the vacuum chamber for holding a hollow target and a substrate, and a gas supply for introducing a high-speed sputtering gas from one end of the target. Means, a plasma is generated by applying a voltage to the target, and is based on a transport sputtering method in which sputter particles generated in a hollow portion of the target are transported and deposited on the substrate by the sputtering gas. A thin film forming apparatus, wherein the exhaust port is provided in a direction perpendicular to a central axis of the target, and the substrate holder is disposed at a position on the exhaust port side from the central axis or in the exhaust port. . 8. The thin film forming apparatus according to claim 7, wherein a distance between said substrate holder and said target end in said central axis direction is 10 cm or more. 9. A shielding plate is disposed at a position in a flow path of a sputtering gas between the substrate holder and the target at a position for shielding electromagnetic waves emitted from plasma toward the substrate on the front surface of the substrate holder. The thin film forming apparatus according to claim 7 or 8, wherein