JPS63286578A - Device for producing thin film - Google Patents

Abstract

PURPOSE:To prevent the clouding of the light introducing window of a vacuum vessel and to effectively carry out a light excited reaction by impressing voltage on an electrode placed in front of the window so as to form an electric field and to stick produced fine particles to the electrode and the inner wall of the vessel. CONSTITUTION:In a device for producing a thin film by a light excited reaction, excitation light 30 enters the vacuum vessel 1 through the light introducing window 3 and passes over a substrate 2 held on a support stand 4. At this time, gaseous starting material introduced into the vessel 1 is excited and deposits on the window 31, etc., as fine particles and radicals. In order to prevent the clouding of the window 31 and to increase the rate of deposition of a thin film, a clouding preventing electrode 32 insulated from the vessel 1 with an insulator 21 is placed on the inside of the window 31 and connected to a power source 33 and voltage is impressed on the electrode 32 to such a degree that glow discharge is not caused. An ununiform electric field is formed between the inner wall of the vessel 1 and the electrode 32, so fine particles, etc., produced by a light excited reaction can be stuck to the electrode 32 or the inner wall of the vessel 1 and captured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film manufacturing apparatus, and more particularly to a thin film manufacturing apparatus suitable for preventing fogging of a light introduction window of a thin film manufacturing apparatus that utilizes a photoexcitation reaction.

[Conventional technology]

One of the most important issues in conventional thin film manufacturing equipment that utilizes photoexcitation reactions is to prevent fogging of the light introduction window.

The most common countermeasures include applying a thin layer of nonvolatile material to the window to suppress gas adsorption, and spraying a gas that does not absorb light as shown in Figure 2.

In FIG. 2, a substrate 2 is held in a vacuum chamber 1, and source gas is supplied from a source gas cylinder 3. The substrate holder 4 that holds the substrate 2 has a built-in heating mechanism that raises the temperature of the substrate to a constant temperature. For other source gases, source gas supply port 5
Supplied from. The excitation light for the photoexcitation reaction is a mercury lamp 6.
The raw material gas is supplied into the vacuum chamber 1, activated, and a part of it is deposited on the substrate. At this time, an inert gas such as argon, helium, nitrogen, etc. is supplied from the inlet 8 to prevent the activated raw material gas and fine particles generated due to the excited reaction from adhering and depositing on the light introduction window 31. When the protective gas (arrow 9) is poured along the inner wall of the vacuum chamber, the protective gas (arrow 9) moves along the inner wall toward the discharge lower and is discharged. However, this method has the disadvantage that it is necessary to introduce a large amount of inert gas in order to prevent deposition on the light introduction window, which increases the reaction pressure. As another method,
Japanese Patent Application Publication 1986. -52013 discloses a method of spraying etching gas onto the light introduction window to remove a film deposited on the window, and JP-A-60-52014 discloses a method in which a movable window is provided inside the light introduction window and a cleaning vacuum is installed in a vacuum chamber. Japanese Patent Publication No. 60-6540 discloses a method of removing the particles in a tank, and a method of preventing precipitation on the window by movably disposing a transparent film inside the light introduction window and sequentially exposing new surfaces.

[Problem that the invention seeks to solve]

Considering that photoexcitation reactions are increasingly being carried out in vacuum with few impurities as semiconductor devices become more highly integrated, the above conventional techniques may cause impurities to be generated or reduce the degree of vacuum. It has the disadvantage of causing a decrease in

In addition, as a method for removing impurities by installing electrodes in a thin film manufacturing apparatus, as described in Japanese Patent Laid-Open No. 61-200865, there is a system for introducing a substrate into a sample stage and a sample chamber equipped with a sample stage. An electrode plate is provided on the inner surface of the vacuum chamber, and a DC high voltage is applied to the electrode plate to collect dust floating in the vacuum chamber and prevent the dust from adhering to the wafer. An example of this is shown in FIG. After the sample substrate 2 is placed on the sample introduction stage 14 of the sample introduction chamber 13, preliminary evacuation is performed, and then it is mounted on the sample stage 16 inside the sample chamber 17. The material chamber 17 is made of inexpensive iron and has a thickness of 1 mm in contact with the vacuum inner surface.
A dragon-sized permalloy electrode plate 20 is stretched. Therefore, this electrode plate 20 is insulated from the ground potential by an insulator 21, and a DC voltage of, for example, plus several kV is applied from a high voltage introduction terminal. As a result, the electrode plate 20 has a high potential with respect to the ground potential, and the negatively charged dust floating near the substrate 2 in the sample chamber 17 adheres to the electrode plate 20. In this way, particulates will be removed. However, in this known example, the charge that the fine particles have is limited to only negative ones, and which charge they actually have depends on the conditions during the reaction, so this known example limits the charge that the fine particles have to only negative ones. Moreover, this known example does not mention the prevention of fogging of the light introduction window due to the photoexcitation reaction.

An object of the present invention is to provide a thin film manufacturing apparatus using a photoexcitation reaction in which fogging of a light introduction window is prevented.

[Means for solving problems]

The above purpose is achieved by providing an electrode to which a voltage is applied in front of the light introduction window and forming an electric field, thereby causing a photoexcitation reaction.
This is achieved by attaching the generated fine particles to the electrodes or the inner wall of the vacuum chamber.

Furthermore, by making the electrode a hollow electrode and gas pipe through which a purge gas can flow, it is possible to prevent the light introduction window from fogging due to radicals in addition to removing the fine particles, or to make the electrode into a rod shape. In addition, by arranging the substrate on the holding table in an electric field, in addition to removing the fine particles, it is possible to prevent the light introduction window from fogging due to radicals, and to improve the deposition rate of the thin film. By doing so, the above objectives can be achieved even better, and additional effects can be expected.

[For production]

The operation corresponding to the structure in which an electrode electrically insulated from the vacuum chamber and a power source for applying voltage to the electrode are provided inside the light introducing window of the present invention is based on the schematic diagram shown in FIG. 4. I will explain. This schematic diagram is an enlarged view of the light introduction window and the window fog prevention portion of the photoexcitation reaction device. The excitation light 30 is transmitted through the light introduction window 31 and passes over the substrate 2 held on the substrate holder 4 . At this time, the raw material gas introduced into the vacuum chamber is excited and becomes fine particles and radicals. Some of these fine particles adhere and deposit on the substrate to form a thin film,
Most of it adheres and deposits on the surrounding inner walls of the vacuum chamber and the light introduction window.

However, when a voltage supplied from the power source 33 that does not generate glow discharge is applied to the window fog prevention electrode 32 which is electrically insulated from the vacuum chamber 1 by the insulator 21, the inner wall of the vacuum chamber 1 and the window fog prevention electrode 32 are electrically insulated from the vacuum chamber 1. An unequal electric field is formed between the electrodes 32, and when fine particles generated due to a photoexcitation reaction enter this unequal electric field, if the fine particles have an electric charge, they will be blown away by the window fogging prevention electrode 32 or It is collected on the inner wall of the vacuum chamber. In addition, (if it is a fine particle that does not have an electric charge, the window fog prevention electrode 3
Collected in 2.

At this time, the behavior of the fine particles generated by the photoexcitation reaction was determined by He-N
When observed through visualization using an e-sheet laser, when no voltage is applied to the electrodes, the particles generated by the photoexcitation reaction move along with the gas flow. It can be seen that when a voltage is applied in this state, the fine particles are separated from the gas flow and move toward the electrode.

In this manner, the generated fine particles are deposited on the window fog prevention electrode 32 or the inner wall of the vacuum chamber 1 due to the photoexcitation reaction, so that deposition on the light introduction window 31 can be suppressed.

In addition, in the present invention, when the electrode is an electrode-cum-gas pipe composed of a hollow member for flowing purge gas inside, it is possible to eliminate not only the fine particles generated by the photoexcitation reaction but also the radicals generated at that time. It is also possible to suppress fogging of the light introducing window.

Furthermore, in the present invention, when the electrode is a rod-shaped electrode located above the substrate holding stand and arranged so that the substrate on the holding stand is in an electric field, the same as in the above case is applied. Not only can fogging of the light introduction window caused by radicals be suppressed, but also the deposition rate of the thin film can be improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

Inside the vacuum chamber 1, there is provided a substrate holding table 4 having a built-in heating mechanism 29 for raising the temperature of the substrate 2 to a constant value. The raw material gas is supplied into the vacuum chamber 1 by controlling the raw material cylinder 22 to a predetermined temperature in the bathtub 23, or by directly controlling the gaseous raw material gas to a predetermined amount by the mass flow controller 24 from the gas supply nozzle 25. . Excitation light 3
0 is projected from the excitation light source 26, focused by the lens 34, transmitted through the light introduction window 31, and introduced into the vacuum chamber 1.

This excitation light 30 excites the raw material gas introduced into the vacuum chamber 1 and generates fine particles and radicals. These are deposited on the substrate 2 heated to a predetermined temperature to form a thin film.

The thickness of the thin film at that time is measured by the film thickness measuring terminal 27, and the signal thereof is analyzed by the film thickness controller 28 and controlled to have a predetermined thickness. The reaction pressure during the photoexcitation reaction is controlled by the exhaust device 40 and the amount of raw material gas supplied, and at the same time, the particulates that did not adhere to and accumulate on the substrate 2 and the inner wall of the vacuum chamber 1 and the raw material gas that did not participate in the reaction are removed. is exhausted to the outside of the vacuum chamber 1 by an exhaust device 40, and harmful components are discharged through a detoxification treatment device. Light introduction window 31 in vacuum chamber l
A voltage is applied to the window fog prevention electrode 32 provided on the front surface from a power source 33 via an insulator 21 provided for electrical insulation from the vacuum chamber 1.

As a raw material gas, iron carbonyl (Fe(Co)s) in a container placed in a bath at 11.5°C was flowed through IOCCM with a helium carrier, the reaction pressure was set to I Torr, and argon fluorine (Arc) laser light (
193 nm), and the irradiation time was 8 minutes.

(Example 1) As the anti-fogging electrode for the light introduction window, copper electrodes each having a square shape with rounded ends were installed parallel to each other at intervals of 20 squares and parallel to the laser beam. The light transmittance when no voltage was applied to the electrode decreased to 10% compared to the initial value, but when
When v was applied, it decreased only to 50%. However, this was not able to achieve a sufficient effect. Therefore, when we take out the electrode at this time and observe it in detail, we see black coloring, which is thought to be fine iron particles, on the electrode surface where the radius of curvature is small and where the electric field is concentrated, and the fine particles adhere to the areas where the electric field is uneven. This was confirmed.

Next, we conducted experiments to find a more efficient configuration for the electrodes that form this unequal electric field.

(Example 2) As an example of an unequal electric field, a coaxial cylindrical system is adopted, and φ1.6
A rod made of 5US316 was installed so that the tip of the rod was located at the center of the light introduction part (φ40). It was found that when +300V was applied to this electrode as in Example 1, the light transmittance was 80%, which was a decrease of only 20% from the initial level. The cloudy state of the light introduction window at this time was compared with the case where no voltage was applied to the electrodes. When no voltage was applied, it was observed that the brown deposits, thought to be iron oxide, were extremely difficult for light to pass through, whereas when a voltage was applied, the coloring was extremely difficult. It was found that the window was in a state where sufficient light was transmitted, and it became clear that the fogging condition of the window had been significantly improved. That is, according to this example, the reaction time can be extended five times by applying a voltage without lowering the reaction pressure.

(Example 3) Under the conditions of Example 2, the polarity of the applied voltage was changed to negative,
The influence of voltage polarity was investigated. As a result, the light transmittance decreased by only 20% from the initial level, similar to when a positive voltage was applied. Therefore, according to this embodiment, the reaction time can be extended regardless of the polarity of the applied voltage.

(Example 4) Next, the applied voltage was further increased to create a condition where plasma is generated only in front of the light introduction window, that is, the applied voltage was increased to -850.
The experiment was conducted as v. The light transmittance in this case is only 5% lower than the initial value, and under these conditions the reaction time is 2.
It was found that the effect could be extended to 0 times, and the effect was great. At this time, when visually observing the state of the plasma, it could only be observed in front of the light introduction window. Therefore, it was confirmed that the influence on other parts was small. Comparing the fogging state of the light introduction window at this time with the case where no voltage is applied, when the voltage is applied, the coloring that is thought to be iron oxide on the light introduction window 31 is reduced, and the fogging state of the window is significantly improved. It became clear that According to this example, there is an effect that the reaction time can be extended by 20 times.

(Example 5) In the above embodiment, the window fog prevention electrode 32 only applied a voltage, but in this embodiment, the window fog prevention electrode 32
By changing the electrode to a rod and making it hollow, the electrode can be configured to double as an inert gas pipe for introducing an inert gas such as argon, helium, or nitrogen gas. In this case, the fifth
The tip of the window fog prevention electrode 32 shown in the figure is an opening, through which the inert gas is introduced. However, it goes without saying that even if this tip portion is not an opening, as long as the structure is such that the light is introduced into the vicinity of the light introduction window 31, the purpose of the present invention is achieved.

It goes without saying that this embodiment is effective not only in removing fine particles generated in the photoexcitation reaction, which is the main purpose of the present invention, but also in preventing fogging of the light introduction window 31 caused by radicals generated at that time. .

In particular, when a fluorine or chlorine gas is used, etching is performed, and it goes without saying that this is more effective in preventing fogging of the light introducing window.

(Example 6) Still another example of the present invention is shown in the photograph of FIG. This figure differs from FIG. 1 in that a rod equipped with a window fog prevention electrode 32 is installed on the top of the substrate holder 4, so that the substrate 2 on the holder is placed in an electric field. In this configuration, the reaction pressure was 30 Torr and the substrate temperature was 5 Torr.
An experiment was conducted at 0°C and the applied voltage was -350V, and the anti-fogging effect on the window was the same as in the previous example, but as shown in the photograph in Figure 7, compared to (a) when no voltage was applied. In case (b), the surface condition changes significantly and the particle size of the deposit becomes thicker, indicating that the particles are growing. In other words, the thin film deposited on the substrate 3 It was found that the speed was improved by about 10 times.

According to this embodiment, there is an effect of improving the deposition rate of the thin film.

Of course, in this case, as shown in FIG. Needless to say, if a hole is made for supplying the raw material gas and the electrode is configured to also serve as a raw material gas nozzle for supplying the raw material gas, the same effects as in this embodiment can be produced.

〔Effect of the invention〕

According to the present invention, fine particles and radicals generated by a photoexcitation reaction can be removed by the effect of an electric field, so that fogging of the light introduction window can be prevented and the photoexcitation reaction can be carried out effectively.Furthermore, the rod-shaped electrode By arranging the substrate so that it is in an electric field, there is also the effect of increasing the deposition rate of the thin film.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Figs. 2 and 3 are block diagrams of a conventional example, Fig. 4 is a schematic diagram of the main parts of the present invention, and Fig. 5 is a block diagram of an embodiment of the present invention.
．． FIG. 6 is a block diagram of another embodiment of the present invention, and FIG. 7 is a photograph showing the grain structure of a thin film deposit with and without voltage application. DESCRIPTION OF SYMBOLS 1... Vacuum chamber, 2... Substrate, 3... Raw material gas cylinder, 4... Substrate holding stand, 9... Inert gas, 21...
... Insulator, 25 ... Gas supply nozzle, 30 ... Excitation light, 31 ... Light introduction window, 32 ... Anti-fog electrode, 3
2′... Anti-fog electrode and inert gas pipe, 32″・
...Anti-fogging electrode and raw material gas nozzle, 33...Power source.

Claims (1)

[Claims] 1. A nozzle for supplying raw material gas, a substrate holding table capable of heating the substrate to a certain temperature, a light introduction window, and a vacuum level of at least 5×10^-^3 Torr or less. In a thin film manufacturing apparatus having at least an evacuable vacuum chamber as a component, an electrode electrically insulated from the vacuum chamber and a power source for applying voltage thereto are provided inside the light introduction window. A thin film manufacturing device characterized by: 2. The electrodes are characterized in that a plurality of electrodes with rounded ends are arranged near the inside of the light introduction window and at predetermined intervals in parallel to the light beam introduced from the light introduction window. A thin film manufacturing apparatus according to claim 1. 3. A nozzle for supplying raw material gas, a substrate holder that can heat the substrate to a certain temperature, a light introduction window, and a vacuum chamber that can evacuate these to a vacuum level of at least 5 x 10^-^3 Torr or less. In the thin film manufacturing apparatus serving as at least a component, an electrode/gas pipe is provided inside the light introduction window and is electrically insulated from the vacuum chamber, and is configured with a hollow member for flowing a purge gas inside. 1. A thin film manufacturing apparatus comprising: and a power source for applying voltage thereto. 4. The thin film manufacturing apparatus according to claim 3, wherein the electrode/gas pipe is installed parallel to the substrate and both ends thereof are open in the vicinity of the light introducing window. 5. A patent characterized in that the purge gas is an inert gas such as nitrogen or argon, and the electrode/gas pipe is arranged so that the entire surface of the light introduction window is an area where glow discharge occurs. A thin film manufacturing apparatus according to claim 3 or 4. 6. A nozzle for supplying raw material gas, a substrate holder that can heat the substrate to a certain temperature, a light introduction window, and a vacuum chamber that can evacuate these to a vacuum level of at least 5 x 10^-^3 Torr or less. In the thin film manufacturing apparatus which is at least a component, the light introduction window is electrically insulated from the vacuum chamber and located above the substrate holding table;
A thin film manufacturing apparatus comprising: a rod-shaped electrode disposed so that the substrate on the holding table is placed in an electric field; and a power source for applying a voltage to the rod-shaped electrode. 7. A patent characterized in that the rod-shaped electrode has a cavity for supplying raw material gas, the end thereof is closed, and a hole is bored in the part facing the substrate in the vacuum chamber. A thin film manufacturing apparatus according to claim 6.