JPH04210472A - Thin film forming device - Google Patents

Abstract

PURPOSE:To eliminate the oozing out of a melted vapor deposition material, to stably operate the device, to prevent corrosion and to improve ionization efficiency by generating a glow discharge between a target and a sputtering electrode and accelerating the formed ion. CONSTITUTION:This thin film forming device is formed with a target 22 of vapor deposition material, a sputtering electrode 23 having a through-hole 24, a vessel 25 for housing the material, a device 27 for introducing a gas into the vessel, a power source 36 and an accelerator 30. A voltage is impressed between the target 22 and the electrode 23 from the power source 36, and a glow discharge is generated in between. The accelerator 30 is arranged on the opposite side of the target 22, opposed to the electrode 23 and has a potential difference from the electrode 23.

Description

[Detailed description of the invention]

[00011

[Industrial Application Field] The present invention relates to an ion source device for a thin film forming apparatus, particularly for forming a high quality thin film by physical vapor deposition (PVD) using plasma. . [0002] [Prior Art] Conventionally, semiconductor films, optical thin films, magnetic films,
High quality thin films such as insulating films are formed by sputtering or low energy ion beam assisted deposition. Figure 2 shows low energy (20eV to 500eV
) is a cross-sectional view schematically showing a conventional thin film forming apparatus using the latter method using ions, and only the ion source device is shown. In the figure, 1 is a vapor deposition material that is a material of a thin film formed on a substrate not shown above, 2 is a vapor generation source that generates vapor of the vapor deposition material 1, 3 is a closed crucible containing the vapor deposition material 1, 4 is an orifice provided at the top of the crucible 3, 5
This is a heater that heats the crucible 3, and the crucible 3, orifice 4, and heater 5 constitute a steam generation source 2. [0003] 6 is an ionization device provided above the crucible 3 to ionize the vapor of the vapor deposition substance 1; 7 is a cathode that emits electrons; 8 is an anode that extracts electrons from the cathode 7; 8 constitutes an ionization device 6. Reference numeral 9 denotes an accelerator which is provided above the ionization device 6 and accelerates the vapor deposition material 1 ionized by the device @6 using an electric field, 10 is an acceleration electrode given a positive potential with respect to the ground, and 11 is a ground potential. The acceleration electrode 10 and the earth electrode 11 constitute an accelerator 9. The above components are housed together with the substrate in a vacuum chamber (not shown). [0004] Next, the operation will be explained. First, the inside of the vacuum chamber is evacuated by a vacuum evacuation system (not shown) to a degree of vacuum of about 10-' Torr or less, and then the crucible 3 is heated with the heater 5, so that the vapor deposited substance 1 in the crucible 3 evaporates, and the orifice 4 through which it is ejected into the ionizer 6. There, part of the vapor of the vapor deposition material 1 collides with the electrons emitted from the cathode 7 and is ionized. The vapor of the ionized vapor deposition substance 1 is transferred to an accelerating electrode 10 and a grounding electrode 11.
It is accelerated by the electric field formed by the vapor and collides with the substrate together with non-ionized vapor, forming a thin film on the surface. [0005]

[Problem to be Solved by the Invention] Since the conventional thin film forming apparatus is constructed as described above, when a vapor deposition substance having good wettability with the crucible material such as silicon or aluminum is used, the molten vapor deposition substance can flow into the orifice. As a result, the ion source device cannot be stably operated due to the phenomenon that the ion source creeps up to the surface or seeps out along the outer wall surface of the crucible. Furthermore, since the molten vapor deposition material generally exhibits strong reactivity with the materials constituting the ion source device, there is a problem in that the parts wetted by the vapor deposition material are corroded and the service life is extremely shortened. Furthermore, the performance of thin films is improved by accelerating the ions of the vapor deposition material and controlling their energy, but in the vapor deposition method using low-energy ions such as the one described above, the proportion of the generated ions in the vapor increases. Since the ionization efficiency (ionization efficiency) is at most 5% or less, and the percentage of usable ions is small, there is a limit to how thin film performance can be improved by ion energy. [0006]Also, there is a method of forming a film by sputtering, but in this case, the particles of the vapor deposition material are not accelerated, so there are problems such as the inability to improve the performance of the thin film using the energy of the vapor deposition material. This invention was made in order to solve the above-mentioned problems.It is possible to operate stably even when using a deposited substance with good wettability, to prevent corrosion caused by the deposited substance, and to create a thin film with high ionization efficiency. The purpose is to obtain a forming device, and
The object of the present invention is to obtain a thin film forming apparatus that can control the degree of acceleration while maintaining a constant amount of ions irradiated onto a substrate. [0007]

[Means for Solving the Problems] A thin film forming apparatus according to the present invention includes a target made of a vapor deposition material and a sputtering electrode in which a through hole is formed, and a target made of a vapor deposition material facing the sputtering electrode on the opposite side of the target. An accelerator is arranged to generate a glow discharge between the target and the sputtering electrode, and the accelerator is composed of an extraction electrode and an acceleration control electrode that have different potentials from each other. [0008]

[Operation] The thin film forming apparatus according to the present invention generates a glow discharge to sputter the vapor deposition material of the target, accelerates ions in the plasma, and irradiates the substrate with the accelerated ions. Further, after the ions are extracted from the ionization device and accelerated by the extraction electrode of the accelerator, the acceleration control of the ions is performed by the acceleration control electrode. [0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a thin film forming apparatus according to an embodiment of the present invention, and in the figure, reference numeral 21 is an ionization device for ionizing a vapor deposition substance that is a material of a thin film to be formed on a substrate not shown above. , 22 is a target made of a vapor deposition material, 23 is a sputtering electrode placed opposite to the target 22, 24 is a first through hole formed in a large number in the sputtering electrode 23, and 25 is a housing for accommodating the target 22 and the sputtering electrode 23. The container 26 is a first insulating part that insulates between the target 22 and the container 25, and 22 to 26 constitute the ionization device 21. [0010127 is a gas introduction device that introduces gas into the container 25, and 28 is a magnetic field generating device provided around the container 25, which is composed of a permanent magnet or a DC coil, and generates a magnetic field inside the container 25 in the vertical direction in the figure. is designed to occur. A magnet 29 is provided below the target 22 in the figure, and is designed to generate a magnetic field component in the direction along the surface of the target 22 in the vicinity of the target 22. [0011130 is an accelerator provided facing the sputtering electrode 23 on the opposite side of the target 22, 31
32 is an extraction electrode arranged opposite to the sputtering electrode 23, and 32 is a second through hole formed in large numbers in the extraction electrode 31.
Reference numeral 33 designates a ground electrode as an acceleration control electrode, which is grounded and arranged in the order of sputtering electrode 23, extraction electrode 31, and ground electrode 33 from the bottom in the figure. 3
Reference numeral 4 designates a large number of third through holes formed in the ground electrode 33, and 31 to 34 constitute the accelerator 30. 35 is a second insulating part that insulates the sputtering electrode 23, the extraction electrode 31, and the ground electrode 33 from each other. [001, 2136 is a power supply device that applies a voltage between the target 22 and the sputtering electrode 23, and generates a high frequency voltage or a DC voltage. 37 and 38 are first ones that provide a potential difference between the sputtering electrode 23 and the accelerator 30;
With the second DC power source, the first DC power source 37 connects the extraction electrode 31, and the second DC power source 38 connects the ground electrode 3.
3 is given a negative potential with respect to the sputtering electrode 23, and the extraction electrode 31 and the ground electrode 33 are at different potentials. In this embodiment, the voltage of the second DC power supply 38 is lower than the voltage of the first DC power supply 37. [0013] Next, the operation will be explained. Gas is introduced into the container 25 from the gas introduction device 27, and a high frequency voltage or a DC voltage is applied between the target 22 and the sputtering electrode 23 by the power supply device 36. target 22
When the glow discharge shown at 39 in the figure is generated between the target 22 and the sputtering electrode 23, and the vapor deposition material of the target 22 is sputtered, a plasma of the introduced gas is generated, and the sputtered vapor deposition material is also partially ionized. be done. [0014] This embodiment is provided with a magnetic field generator 28 that increases the plasma density of the glow emission @39.
The spiral movement of the electrons promotes the ionization of atoms in the gas and the vapor deposited material, allowing more efficient ionization. In addition, since the magnet 29 is provided below the target 22, the electrons move in a spiral manner near the target 22.
This has the effect of stabilizing the plasma and efficiently sputtering the deposition material. [0015] The ions of the vapor deposition material and gas generated in the ionization device 21 in this manner 7 pass through the first through hole 24 formed in the sputtering electrode 23 and move upward in the figure. Since metals that are often used as vapor deposition materials have positively charged ions, they are accelerated by the accelerator @30 with a negative potential with respect to the sputtering electrode 23, and pass through the second and third through holes 32 and 34. It reaches the substrate and forms a thin film on its surface. [0016] At this time, the extraction electrode 3 negatively biased with respect to the sputtering electrode 23 by the first DC power supply 37
The ions extracted by 1 are accelerated once during this period. Since the voltage of the first DC power supply 37 is higher than the voltage of the second DC power supply, the extraction electrode 31 has a lower potential than the ground electrode 33, and the ions that have been accelerated and passed through the second through hole 32. is decelerated between the extraction electrode 31 and the ground electrode 33. Eventually, the ions are given kinetic energy according to the potential difference (acceleration voltage) between the sputtering electrode 23 and the earth electrode 33, and enter the substrate through the third through hole M. [0017] If the voltage between the sputtering electrode 23 and the extraction electrode 31 is set to a certain constant value, even if the accelerating voltage is changed, a certain amount of ions can be extracted. Therefore, when it is desired to form a thin film that takes advantage of the characteristics of low-energy ions, it is possible to form the film at a low accelerating voltage while ensuring the necessary amount of ions. Furthermore, in this embodiment, the potential of the extraction electrode 31 is always negatively biased with respect to the grounded substrate.
This has the effect of suppressing electrons ejected from the portion where the glow discharge 39 is occurring from entering the substrate. [0018] In the above embodiment, the magnetic field generator 28,
Although the magnet 29 and the extraction electrode 31 are provided, the present invention can also be applied to a device without these, and the resulting decrease in efficiency can be compensated for by increasing the pressure of the introduced gas. Furthermore, although the potential of the accelerator 30 is made negative with respect to the sputtering electrode 23 so as to be able to handle positively charged ions, the potential may be made positive in order to handle negatively charged ions. [00191] [Effects of the Invention] As described above, according to the present invention, a glow discharge is generated between a target and a sputtering electrode, and the generated ions are accelerated. Since it is composed of an extraction electrode and an acceleration control electrode, there is no need to melt the vapor deposition material in a crucible, so even if a vapor deposition material with good wettability is used, stable operation is possible without the molten vapor deposition material seeping out. In addition, ions can be extracted from the plasma in the glow discharge section and used, thus increasing the ionization efficiency. moreover,
By controlling the acceleration of the ions extracted by the extraction all with the acceleration control electrode, there is an effect that the degree of acceleration can be controlled while retaining a certain amount of ions.

[Brief explanation of the drawing]

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

FIG. 2 is a sectional view of a conventional thin film forming apparatus.

[Explanation of symbols]

22 Target 2:3 Sputtering electrode 24 First through hole 25 Container 27 Gas introduction device 30 Accelerator 31 Extraction electrode 32 Second through hole 33 Earth electrode 34 Third through hole 36 Power supply device 37 First DC power supply 38 Second DC power supply 39 Glow discharge

Claims (2)

[Claims] 1. A target made of a vapor deposition material, a sputtering electrode having a through hole formed therein and disposed facing the target, a container accommodating the target and the sputtering electrode, and a gas introduction method for introducing gas into the container. a power supply device that applies a voltage between the target and the sputtering electrode to generate a glow discharge therebetween; A thin film forming apparatus equipped with an accelerator that has a potential difference. 2. The acceleration electrode is composed of an extraction electrode and an acceleration control electrode each having a through hole formed therein, and the sputtering electrode, the extraction electrode, and the acceleration control electrode are arranged in this order, and the extraction electrode and the acceleration control electrode are arranged in this order. 2. The thin film forming apparatus according to claim 1, wherein different potentials are applied to the electrodes.