JPS6339667B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention includes an ionization region that ionizes at least a portion of a vaporized substance, and the ionization region imparts kinetic energy to the ionized vaporized substance, thereby ionizing the ionized vaporized substance. The present invention relates to an ion beam deposition apparatus that transfers a vaporized substance that is not ionized to a substrate and deposits it on the substrate. [Prior Art] Conventionally, there are ion plating methods, ion beam evaporation methods, cluster ion beam evaporation methods, etc. as vapor deposition film forming techniques, in which the substance on which the vapor deposition film is to be formed is ionized and an accelerating voltage is applied to it. The aim is to control the crystallinity and physical properties of the film by applying kinetic energy or by using the effect of the electric charge of ions. In these techniques, it is necessary to ionize the evaporation material vapor evaporated from the crucible by using a shower of electrons for ionization, and then provide an accelerating electrode for acceleration in the vicinity of the ionized electron shower. For example, in the ion beam deposition method, as shown in FIG. 1, a substance 2 to be vaporized and deposited is extruded into a crucible 1, and the temperature of the crucible 1 is increased. The crucible 1 can be heated by radiation heating using a filament 3 for heating the crucible, by electron impact heating by applying a voltage between the filament 3 and the crucible 1 and emitting electrons from the filament 3, or by directly heating the crucible 1 on the outer wall. Any direct heating method using current may be used. Of course, a combination method of these methods is also possible. And crucible 1
The vapor deposition substance 2 is vaporized by the temperature rise, and vapor 4
and rises. In this case, it is usually in the form of atoms, molecules, or a small group of atoms made up of several atoms. An electronic shower 5 is involved in order to ionize a portion of this vapor 4. The electron shower 5 is formed by an ionizing electron emitting filament 6 and a mesh-like ionizing electron extraction grid 7 for extracting electrons therefrom. In order for the electronic shower 5 to efficiently direct the steam 4, the surroundings of the filament 6 are usually
A positive voltage of about 200 V to 1 KV is applied to the filament 6 and the shield electrode 8 to the ionizing electron extraction grid 7, which is surrounded by a shield electrode 8 having the same potential as the filament 6 and the shield electrode 8.
However, this is a case where atoms and molecules are positively ionized by ionization. These filament 9, grid 7, and shielding electrode 8 are referred to as an ionization electrode group, and the region where the electronic shower 5 collides with the vapor rising from the crucible 1 is referred to as an ionization region 9. By the way, since the ionized vapor is positively charged, in order to accelerate it and give it kinetic energy, an accelerating electrode 10 for applying a negative high voltage is provided, and a negative acceleration of about 0 to 10 KV is provided. Voltage must be applied. Therefore, the equipotential line 11 due to this applied voltage
As shown in the figure, the group has a concave shape when viewed from above within the ionization region 9, and the ionized particles are gradually accelerated while being subjected to a force perpendicular to the equipotential line 11, so that they move toward the central axis. will be focused on. As is clear from the figure, the 11 equipotential lines also become convex toward the top and become a divergent system, but since the speed of the particles that have already been accelerated here is high, the overall system is necessarily a focused system. becomes. Furthermore, the degree of focusing will vary significantly depending on the applied negative high voltage, that is, the optimum voltage for forming a deposited film, which is determined based on the application. On the other hand, vaporized particles that have not been ionized in the ionization region 9 arrive at the substrate 12 without being accelerated or focused and are deposited thereon. Therefore, in the film 13 formed on the substrate 12, the proportion of ionized and accelerated particles is large in the center, and extremely small in the peripheral part, and the quality of the film 13 formed is not uniform. This phenomenon can be achieved not only by the technology shown in Figure 1, which ionizes the vapor of atomic or molecular particles, but also by the so-called cluster ion technology, which uses a cluster of atoms in which 500 to 2000 atoms are loosely bonded to each other. The situation is the same in beam evaporation methods. Next, the cluster ion beam evaporation method was applied to the second
This will be explained with figures. This vapor deposition method utilizes adiabatic expansion caused by injection.
Insert the electron emitting filament 1 for heating the crucible.
The material 16 to be deposited is vaporized by an electron impact heating method in which the crucible 15 is impact-heated by electron emission from the crucible 7 . Note that the crucible 1 is a direct heating method in which a large current is passed directly through the furnace wall of the crucible 15.
It is also possible to use a method in which a heater is provided around 5 for heating, or a combination method thereof. Then, the vaporized material vaporized in the crucible 15 and turned into high-pressure steam of about 10 ^-2 to several torr is injected into a high vacuum from the nozzle 16, and due to the supercooling phenomenon based on adiabatic expansion, The particles form a cluster of atoms, and become a cluster flow 18 that flies toward the substrate with the energy of the injection.
At that time, as in the case of FIG. 1, a positive electron extraction voltage (approximately 200V to 1KV) applied to the ionization electron emission filament 19 and the mesh-like ionization electron extraction grid 20 for extracting electrons from it. An electronic shower is thus formed, and the shielding electrode 21 is at the same potential as the filament 19.
The cluster flow 18 is efficiently irradiated with the help of this method, and a part of the clusters are ionized. This portion is the so-called ionization region 22. In the figure, 23 is an accelerating electrode, 24 is a substrate holder, 25 is a substrate, a thermocouple 26, and a heater 2 for heating the substrate.
7. Attach the shutter 28 as appropriate depending on the purpose. And in the case of clusters, even though it is called ionization,
Only one atom among the 500 to 2000 cluster constituent atoms is ionized, but the electric field generated by the accelerating electrode 23 leaks toward the ionization region 22 to accelerate the ionized cluster, causing a focusing lens. Create a system. This is the same as in the case of FIG. Therefore, the clusters ionized by the accelerating voltage are focused toward the central axis, and the film formed on the substrate 25 provided on the substrate holder 24 is
The ratio of cluster ions that are ionized and focused in the ionization region 22 and neutral clusters that are not ionized and go straight and hit the substrate 25 is not uniform, and furthermore, the accelerating voltage suitable for the application changes. This causes the inconvenience that the distribution changes every time. FIG. 3 shows an example of this using a computer simulation. This figure shows an enlarged view of the area from the ionization region 22 of FIG. 2 to the substrate 25 using silver clusters. Electron extraction grid 20 for ionization in Figure 2
and the electron emitting filament 19 for ionization.
Since it is necessary to apply an electron extraction voltage of 200V to 1KV, this voltage is set to 500V in Figure 3,
The electrode corresponding to the ionization electron extraction grid 20 in FIG. 2 is also represented by 20 in FIG. It was set to -500V. Then, a third electrode corresponding to the accelerating electrode 23 in FIG.
Figure 23 shows the trajectory of the ionized cluster when -3KV is applied, and Figure 3a shows the trajectory of the ionized cluster when -6KV is applied.
Fig. 3b shows the result when . As is clear from these figures, the distribution of ionized clusters on the surface of the substrate 25 changes significantly depending on the voltage applied to 23 in FIG. By the way, in Fig. 2, it was explained that the effect of the electric field of the accelerating voltage penetrating into the ionization region 22 is a focusing effect, but in the simulation of Fig. 3, especially in case a, it is not very focused. The reason is as follows. The simulation program used here is an extremely advanced and state-of-the-art technology, and the simulation does not simply consider the divergence and convergence effects of the electric field. If a conventional program that only considers the so-called electric field distribution is used, if it corresponds to Fig. 3a, it will be shown in Fig. 3c, and if it corresponds to Fig. 3b, it will be shown in Fig. 3d. The trajectory will intersect and diverge. However, in the simulation used this time, the space charge effect of ions was strictly considered, and the resulting repulsion between ionized clusters and minute displacements in the space potential due to the charges of ions were calculated and converged. Figures 3a and 3b are very close to the actual situation. In other words, even if the amount of ionized electron current changes and the amount of ionized particles changes, the trajectory can be traced. On the other hand, since neutral clusters that have not been ionized are not related to the accelerating voltage, the ratio of neutral clusters to ionized clusters changes, which greatly affects the crystallinity and physical properties of the deposited film, causing practical problems. [Object of the Invention] An object of the present invention is to provide an ion beam evaporation apparatus that can uniformly distribute an ionized vaporized substance over a predetermined area of a substrate. [Structure of the Invention] The present invention includes an ionization region that ionizes at least a portion of a vaporized substance, and the ionization region imparts kinetic energy to the ionized vaporized substance, converting the ionized vaporized substance into non-ionized vapor. In an ion beam evaporation apparatus in which the ionized material is transferred to a substrate and deposited on the substrate, a necessary kinetic energy is applied to the ionized vaporized material and the vaporized material is transferred between the ionized region and the substrate. An ion beam evaporation apparatus characterized by being provided with at least two or more electrodes that give a trajectory to the vaporized substance so as to form a uniform concentration or distribution over a predetermined area when it reaches the substrate. . [Effects of the Invention] The present invention provides the necessary kinetic energy for the ionized vaporized substance between the ionization region and the substrate;
By providing at least two or more electrodes that give a trajectory to the vaporized substance so that it forms a uniform concentration or distribution over a predetermined area when the vaporized substance reaches the substrate, the vaporized substance is provided with the necessary It is capable of imparting kinetic energy and forming a uniform concentration or distribution over a predetermined area of the substrate. [Example] Next, the present invention will be explained in detail with reference to the drawings from FIG. 4 showing an example of the invention. First, FIG. 4 showing one embodiment will be explained. In the same figure, the same symbols as those in FIG. be. Next, an accelerating voltage determined depending on the application is applied to the accelerating electrode 23, and in response to this, the intermediate electrode 2
The results of investigating the focusing state of ionized clusters by changing the voltage of 9 will be explained. For this investigation, we used the ion trajectory simulation method described above, which takes into account the space charge effect of ions and the fluctuation of space potential due to the charge of ions, and extracted the area shown by the dashed line in Fig. 4.
It was modeled as shown in the figure. Then, the energy of the nozzle jet (approximately
100 eV) was considered as the initial condition, and the cluster ion trajectories were investigated in the case of the cluster ion current shown in Table 1 with a cluster ion current of 20 μA.

[Table] Based on these results, the substrate 25 of the ionized cluster
FIG. 6 shows the relationship between the voltage applied to the accelerating electrode 23 (the same voltage is applied to the substrate holder 24) and the voltage applied to the intermediate electrode 29 to make the distribution uniform. In the embodiment shown in FIG. 4, the accelerating electrode 23 and the intermediate electrode 29 impart the necessary kinetic energy to the ionized vaporized substance and uniform distribution over a predetermined area of the substrate 25. Although shown, it goes without saying that two or more electrodes may be provided as the intermediate electrode 29. Next, another embodiment of the present invention will be described with reference to FIG. 7. In the same figure, the same symbols as those in FIG. The power supply 30 applies the optimum voltage that can realize the heating of the crucible 15 to the filament 17
The filament 17 itself is heated by a power source 32. The vaporized substance injected from the nozzle 14 in this way becomes a cluster and flies toward the substrate 25, but on the way it hits the ionizing electron-emitting filament 1.
Electrons from 9 are emitted by an ionizing electron extraction grid 20, and are ionized. The filament 19 is heated by a suitable power source (not shown), and the electrons are extracted by a power source 33. In this way, the ionized clusters and neutral clusters fly toward the substrate 25 in a mixed state, so the relationship shown in FIG. 6 is determined in advance, and the voltage of the power supply 34 is automatically adjusted according to this. manually or manually to obtain a predetermined distribution of ionized clusters. In addition, a beam profiler 35 for measuring the distribution of the ion beam is placed in front of the substrate 25, and it is moved manually or automatically to observe the profile of the cluster ion beam, and while observing this, the power supply 34 is turned on. According to the relationship shown in FIG. 6, the voltage of the intermediate electrode 29 is automatically or manually changed so that the distribution on the substrate 25 becomes uniform. Note that the beam profiler 35 can be a rod-shaped one, one that forms a rectangular coordinate system, or one that is normally used to observe a beam profile, such as a Fara de cup type. Furthermore, the necessary ion distribution is stored in the logic circuit 36 in advance, and the beam distribution data obtained from the beam profiler 35 is automatically determined by the logic circuit 36, and this and the signal from the accelerating voltage of the power source 30 are combined. In addition, the power supply 34 is automatically adjusted to obtain a predetermined cluster ion beam distribution. As with the case of Fig. 3, examples of computer simulations of the above are shown in Fig. 8 a, b, c, and d.
The electron extraction grid 20 for ionization is
0V, electron emitting filament 19 for ionization -
Table 2 shows the trajectory of cluster ions when the voltage is 500V.

[Table] In other words, when a voltage corresponding to the kinetic energy required by the ions is applied to the accelerating electrode 23 at the last stage, the ions that have obtained the kinetic energy are uniformly distributed over a predetermined area when they reach the substrate 25. The voltage applied to the intermediate electrode 29 is controlled according to a predetermined program using a signal from the beam profiler 35 so that the ions are distributed appropriately over the entire required kinetic energy range. This is what I did. Although the crucible 15 side is grounded in FIG. 7, the substrate 25 side may also be grounded. Furthermore, although the above description has been made regarding the case of positive ionization, there is essentially no difference in the case of negative ionization, except that the polarity of the voltage changes.

[Brief explanation of the drawing]

Figures 1 and 2 are front views of conventional ion beam evaporation equipment, Figures 3 a, b, c, and d are computer simulations of the case in Figure 2, and Figure 4 is the ion beam of the present invention. A front view of one embodiment of the vapor deposition apparatus, FIG. 5 is a schematic diagram of a part of FIG. 4,
Figure 6 is a diagram of the relationship between accelerating electrode voltage and intermediate electrode voltage.
FIG. 7 is a front view of another embodiment of the invention, and FIGS. 8a, b, c, and d are computer simulation diagrams for the case of FIG. 14... Injection nozzle, 17, 19... Filament, 20... Grid, 21... Shielding electrode, 2
2...Ionization region, 23...Acceleration electrode, 24...
... Substrate holder, 25 ... Substrate, 29 ... Intermediate electrode, 30, 31, 32, 33, 34 ... Power supply, 3
5...Beam profiler, 36...Logic circuit.

Claims (1)

[Claims] 1. An ionization region that ionizes at least a portion of the vaporized substance, the ionization region imparts kinetic energy to the ionized vaporized substance, and the ionized vaporized substance is transferred to the substrate together with the non-ionized vaporized substance. In an ion beam evaporation apparatus that performs evaporation on the substrate,
between the ionization region and the substrate to impart a required kinetic energy to the ionized vaporized substance and to form a uniform concentration or distribution over a predetermined area when the vaporized substance reaches the substrate; An ion beam evaporation apparatus characterized in that at least two or more electrodes are provided for giving a trajectory to the vaporized substance.