JPH0768616B2 - Thin film forming method and thin film forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for forming a thin film on a semiconductor substrate by physical vapor deposition such as sputtering.

[0002]

2. Description of the Related Art Conventionally, for example, a photoconductive element U as shown in FIG. 4 has been proposed. That is, the metal film 2, the photoconductive semiconductor substrate 3, and the transparent electrode thin film 4 are laminated in this order on the insulating substrate 1. Semiconductor substrate 3
Is made of, for example, hydrogenated amorphous silicon, and a transparent electrode thin film 4 made of, for example, indium tin oxide is formed on the semiconductor substrate 3 by a physical vapor deposition method (PVD) such as sputtering.

FIG. 5 schematically shows a sputtering apparatus applied when the transparent electrode thin film 4 is formed on the semiconductor substrate 3 as described above. That is, a target 6 made of a transparent electrode material is fixed on the cathode 5, and a semiconductor substrate 3 serving as an anode is arranged facing the target 6 with a predetermined distance.

In such a structure, when DC high-voltage glow discharge is performed between the two electrodes in a low-pressure gas containing argon or another inert gas as a main component, + ions are generated, which collide with the target 6 to cause the target 6 to collide. Knock out the atoms on the surface of. As a result, the particles of the transparent electrode material adhere to the surface 3a of the substrate 3 to form the transparent electrode thin film 4. In addition, in FIG. 5, 7 indicates a glow discharge region.

[0005]

By the way, in the conventional method for manufacturing a photoconductive element as described above, the kinetic energy of the particles of the transparent electrode material when it is attached onto the substrate 3 is generally set to about 1 to 50 eV. To be done. Therefore, in the initial stage of the film deposition process, the surface 3a of the substrate 3 is easily damaged by the collision of the particles having such high kinetic energy.

Further, the collision of such particles having high kinetic energy causes the generation of dangling bonds on the surface 3a of the base body 3 and eventually deteriorates the interface characteristics.

Therefore, the photoconductive element U as shown in FIG.
In the case of, carriers are easily injected from the transparent electrode thin film 4 into the semiconductor substrate 3, that is, amorphous silicon,
The inconvenience of increasing the dark current occurs.

The present invention has been made in view of the above points, and in forming a thin film by the physical vapor deposition method,
An object of the present invention is to provide a thin film forming method and a thin film forming apparatus capable of favorably preventing the surface of a substrate from being damaged.

[0009]

Therefore, in the thin film forming method of the present invention, in the thin film forming method of forming a thin film by depositing a thin film forming material on a substrate by physical vapor deposition, particles of the thin film forming material are The kinetic energy of the particles when they are deposited on the substrate is made small so that the surface of the substrate is not damaged at the initial stage and then increased. That is, a first feature of the present invention is that a base is placed on a first electrode, and a thin film forming material provided on a second electrode is made to face the base, and a space between the first and second electrodes is provided. A thin film forming method using a physical vapor deposition method in which particles of a thin film forming material are adhered onto the substrate by applying an electric field to the first electrode and the second electrode disposed between the first electrode and the second electrode. The third electrode is maintained at a potential equal to or lower than the potential of the first electrode to suppress the kinetic energy of the particles reaching the substrate, and the first electrode and the second electrode A first film forming step of forming a film by applying an electric field between the electrode and the electrode to cause the particles to adhere to the substrate, and controlling a potential applied to the third electrode to reach the substrate. Increase the kinetic energy of the particles and allow them to adhere to the substrate Lies in including a second film forming step of forming a. That is, a third electrode (grid) having an electric potential equal to or lower than the electric potential of the base body serving as an anode is arranged between the base body and the target (thin film forming material), and the glow discharge region is formed between the target and the grid. The kinetic energy of the thin film forming material particles that collide with the substrate is suppressed by trapping them in between. A second feature of the present invention is that a substrate is placed on the first electrode, the thin film forming material provided on the second electrode is made to face the substrate, and the thin film forming material is placed between the first and second electrodes. In a thin film forming method using a physical vapor deposition method in which particles of a thin film forming material are adhered onto the substrate by applying an electric field,
The particles reaching the substrate by controlling the magnetic field generating means arranged in the vicinity of the second electrode to increase the magnetic flux density of the magnetic field formed on the surface of the thin film forming material and in the vicinity thereof. A first film forming step of forming a film by applying an electric field between the first electrode and the second electrode while allowing the particles to adhere to a substrate while suppressing the kinetic energy of A second film forming step of forming a film by controlling the generating means to increase the kinetic energy of the particles reaching the substrate and causing the particles to adhere to the substrate. That is, in the initial stage of film formation, by controlling the magnetic field generating means to increase the magnetic flux density of the magnetic field formed on the surface of the thin film forming material and in the vicinity thereof, the region where the density of ions is high is the target surface. The particles are made to move in the vertical direction (close to the target) to suppress the kinetic energy of the particles reaching the substrate.

Further, the thin film forming apparatus of the present invention comprises a first electrode on which the substrate is placed, and a second electrode facing the substrate and having a thin film forming material on the surface of the substrate side. Then
In the thin film forming apparatus, an electric field is applied between the first electrode and the second electrode to form the thin film forming material into particles, and the particles are deposited on the substrate to form a thin film. Kinetic energy control means is provided for controlling the kinetic energy of the particles of the material so as to be small at the initial stage such that the surface of the substrate is not damaged and then increase. That is, a third feature of the present invention is that a first electrode on which a substrate is placed, a second electrode carrying a thin film forming material so as to face the substrate, the first electrode and the second electrode An electric field applying means for applying an electric field between the first electrode and the electrode, and the thin film forming material is formed into particles, and the particles are deposited on the substrate to form a thin film. A third electrode provided between the second electrode and the second electrode; and a voltage control unit that controls a voltage applied to the third electrode, and by driving the voltage control unit, This is to suppress the kinetic energy of the particles reaching the substrate. A fourth feature of the present invention is that a first electrode on which a substrate is placed, a second electrode carrying a thin film forming material so as to face the substrate, the first electrode and the second electrode An electric field applying means for applying an electric field between the thin film forming material and the electrode, and the thin film forming material is formed into particles, and the particles are deposited on the substrate to form a thin film.
A magnetic field control unit arranged near the second electrode for increasing the magnetic flux density of the magnetic field formed on the surface of the thin film forming material and in the vicinity thereof, and by driving the magnetic field control unit, This is to suppress the kinetic energy of the particles reaching the substrate.

[0011]

By such a thin film forming method or thin film forming apparatus, the kinetic energy of particles is suitably controlled and suppressed to the extent that the substrate surface is not damaged at the initial stage of film formation. In the first and third aspects of the present invention, the kinetic energy of the particles reaching the substrate is suppressed by controlling the electric field. Further, in the second and fourth aspects of the present invention, the magnetic field generating means increases the magnetic flux density on the surface of the thin film forming material (target) and in the vicinity thereof so that the region where the density of ions is high is directed in a direction perpendicular to the target surface. The height of the cycloidal motion is reduced by moving it and bringing it closer to the surface of the target, and the kinetic energy of the particles reaching the substrate arranged opposite thereto is suppressed.

Further, according to such a thin film forming method or thin film forming apparatus, stable thin film formation can be realized without impairing the physical characteristics of the substrate, but the time required for the film forming treatment is
It is as efficient as the time required for the conventional ordinary film deposition process.

[0013]

EXAMPLES Examples of the present invention will be described in detail below.

The present invention suppresses the kinetic energy of the thin film forming material particles when they collide with the substrate in the initial stage of the transparent electrode thin film deposition process. A method shown as the characteristic C or D in 1 can be considered.

That is, assuming that a thin film is conventionally formed with a power of 100 W in a short time as shown by characteristic A in FIG. 1, this is shown as characteristic C or D in FIG. , 20 at the beginning of the film deposition process
Sputtering is performed with an electric power of W, and the electric power is increased stepwise or continuously from the time when a thin film having a thickness of about 100Å is formed.

According to this, even if the photoconductive element as shown in FIG. 4 is manufactured, the surface of the substrate 3 (amorphous silicon) is not damaged in a practical time. It becomes possible to manufacture a photoconductive element.

Further, as a method of suppressing (controlling) the kinetic energy of the thin film forming material particles, there is also a method of limiting the glow discharge region to the vicinity of the target.

For example, as shown in FIG. 2, a grid 8 having a potential equal to or lower than the potential of the substrate 3 serving as an anode is arranged between the substrate 3 and the target 6, and the glow discharge region 7 is provided. Should be enclosed between the target 6 and the grid 8. This also makes it possible to suppress the kinetic energy of the thin film forming material particles that collide with the base body 3.

In this case, the distance between the grid 8 and the substrate 3 is selected to be a distance (several times the mean free path of particles or more) at which the kinetic energy of the particles of the thin film forming material can be sufficiently attenuated. . In addition, the conditions for removing or reducing the kinetic energy suppressing action by the grid 8 when a thin film having a thickness of about 100 Å is formed are as shown in FIG.
The condition is the same as the condition C or D.

Further, the kinetic energy control of the thin film forming material particles corresponding to the characteristic C or D of FIG. 1 can be realized by using the magnetron sputtering apparatus shown in FIG.

That is, in the magnetron sputtering apparatus shown in FIG. 3, the magnet 9 is arranged on the cathode 5 side, and the magnet 9 is formed on the surface of the target 6 and its vicinity in the initial stage of the film deposition process. Increase the magnetic flux density of the magnetic field. Thereby, the glow discharge region 7 as the sputtering device can be limited to the vicinity of the target 6, and the kinetic energy of the thin film forming material particles that collide with the substrate 3 can be suppressed.

For reference, when the apparatus of FIG. 3 was applied to the manufacture of the photoconductive element U shown in FIG. 4, the magnitude of the generated magnetic field was 200 to 300.
By increasing from Gauss to 600 Gauss, the transparent electrode thin film 4 can be deposited without causing dangling bonds on the surface of the amorphous silicon as the base body 3. It was possible to obtain a photoconductive element in which good Schottky junction was realized. Also here, the conditions for removing or reducing the magnetic field thus enhanced at the time when the transparent electrode thin film having a thickness of about 100 Å is formed are the same as the conditions shown as the characteristics C or D in FIG.

[0023]

As described above, according to the present invention,
At the beginning of the thin film formation process in sputtering,
The kinetic energy of particles of the thin film forming material when deposited on the substrate is suppressed to such an extent that the surface of the substrate can be prevented from being damaged by the collision of the particles, and thereafter the suppression of the kinetic energy is released. From the above, for example, in the case of the photoconductive element U shown in FIG. 4, the generation of dangling bonds on the surface of the amorphous silicon is favorably suppressed,
It is possible to highly efficiently obtain a photoconductive element having excellent characteristics with a small amount of carriers injected from the transparent electrode thin film into the semiconductor substrate 3, and thus with a small dark current.

The thin film forming method and the thin film forming apparatus of the present invention can be applied not only to the above-mentioned sputtering but also to a thin film forming step by another physical vapor deposition method such as ion plating.

Further, the thin film forming method and the thin film forming apparatus of the present invention are not limited to the case where the substrate is made of a semiconductor and the metal thin film is formed thereon, but also when the semiconductor thin film is formed on the semiconductor substrate. The same can be applied to the case of forming a semiconductor thin film on a substrate.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a thin film forming method according to the present invention in comparison with a conventional method.

FIG. 2 is a schematic view showing a schematic configuration of an embodiment of a thin film forming apparatus according to the present invention.

FIG. 3 is a schematic view showing a schematic configuration of another embodiment of the thin film forming apparatus according to the present invention.

FIG. 4 is a cross-sectional view showing the structure of a photoconductive element as an example to which a thin film forming process is applied.

FIG. 5 is a schematic view showing a schematic configuration of a sputtering apparatus used for a thin film forming process.

[Explanation of symbols]

1 ... Insulating substrate, 2 ... Metal film, 3 ... Semiconductor substrate, 4 ... Transparent electrode thin film, 5 ... Cathode, 6 ... Target, 7 ... Glow discharge region, 8 ... Grid, 9 ... Magnet.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/203 S 8719-4M 21/285 S 8826-4M 31/0248 31/04

Claims (4)

[Claims] 1. A substrate is placed on a first electrode, and a thin film forming material provided on a second electrode is made to face the substrate,
A thin film forming method using a physical vapor deposition method in which an electric field is applied between the first and second electrodes to deposit particles of a thin film forming material on the substrate, wherein the first electrode and the second electrode While maintaining a third electrode disposed between and a potential equal to or less than the same as the first electrode, while suppressing the kinetic energy of the particles reaching the substrate, The first electrode and the second
The first film forming step of forming a film by applying an electric field between the first electrode and the second electrode to adhere the particles onto the substrate, and controlling the potential applied to the third electrode to reach the substrate. And a second film forming step of forming a film by increasing the kinetic energy of the particles and adhering the particles onto a substrate. 2. A substrate is placed on the first electrode, and the thin film forming material provided on the second electrode is made to face the substrate,
A thin film forming method using a physical vapor deposition method in which an electric field is applied between the first and second electrodes to cause particles of a thin film forming material to adhere to the substrate, the thin film forming method being arranged in the vicinity of the second electrode. By controlling the magnetic field generating means to increase the magnetic flux density of the magnetic field formed on the surface of the thin film forming material and in the vicinity thereof, the kinetic energy of the particles reaching the substrate is suppressed, and the first A first film forming step of forming a film by applying an electric field between the electrode and the second electrode to attach the particles to the substrate, and controlling the magnetic field generating means to form a film on the substrate. A second film forming step of forming a film by increasing the kinetic energy of the particles that reach and by making the particles adhere to a substrate. 3. A first electrode on which a substrate is placed, a second electrode carrying a thin film forming material so as to face the substrate, and between the first electrode and the second electrode. An electric field applying means for applying an electric field to the first electrode and the second electrode, wherein the thin film forming material is formed into particles, and the particles are deposited on the substrate to form a thin film. A third electrode provided between the electrode and a voltage control means for controlling a voltage applied to the third electrode is provided, and the voltage control means is driven to reach the substrate. A thin film forming apparatus characterized in that the kinetic energy of the particles can be suppressed. 4. A first electrode on which a substrate is placed, a second electrode carrying a thin film forming material so as to face the substrate, and between the first electrode and the second electrode. An electric field applying means for applying an electric field to the thin film forming material, wherein the thin film forming material is formed into particles, and the particles are deposited on the substrate to form a thin film. And a magnetic field control means for increasing the magnetic flux density of the magnetic field formed on the surface of the thin film forming material and in the vicinity thereof, and the kinetic energy of the particles reaching the substrate by driving the magnetic field control means. A thin film forming apparatus characterized in that it is possible to suppress