JP4573450B2 - Sputtering equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to a sputtering apparatus. More specifically, the invention of this application relates to a new sputtering apparatus that is useful for film formation of an optical thin film, has a simple structure, is inexpensive, and enables high-speed and stable high-quality film formation. It is.
[0002]
[Prior art and problems of the invention]
When an optical thin film is to be formed, a vacuum deposition apparatus is generally used in the past, and the film is formed using a very sophisticated control device for forming an optical thin film. On the other hand, recently, sputtering devices with good controllability have been used for forming optical thin films, and several devices have been proposed.
[0003]
The characteristics of the vacuum evaporation apparatus will be described. This apparatus is characterized in that a uniform film is formed on a large-area substrate surrounding the evaporation source from a small evaporation source. The distance between the evaporation source and the substrate is usually 500 mm or more. Keep. The substrate is made uniform using a revolving dome, a planetary jig, or the like.
[0004]
The evaporation source is usually heated by resistance heating or electron beam irradiation, and a method is employed in which a necessary amount of the evaporation material is charged into the evaporation source and evaporated by heating.
Therefore, it was necessary to prepare the evaporation source so that the evaporation source was prepared and the same amount of evaporation material was charged every time the evaporation work was performed, and the same evaporation amount was ensured.
[0005]
In addition, a monitor is provided in the vicinity of the substrate holder, that is, the jig, so that the film thickness of the vapor deposition is the same every time, the evaporation amount directly entering the monitor is read to judge the completion time of vapor deposition, and the film formation speed is detected. Then, the evaporation amount of the evaporation source is controlled. However, controlling the evaporation rate was extremely difficult. This is because the evaporation source is heated by resistance heating or electron beam irradiation, and the evaporation is performed by the energy of the heating. Therefore, the responsiveness cannot be said to be rapid. Therefore, precise control was performed by calculating and controlling the heating input of the evaporation source and the observation of the amount of deposited film with an electronic computer or the like. Deposition monitors include a method of observing the thickness of the film by electrically reading the frequency fluctuations of the crystal oscillator, and a change in transmittance by injecting light of a specific wavelength into the film. There is known a method of reading the deposition amount by electrically reading. Moreover, as a method of reading the film thickness of a transparent film such as an oxide or nitride, an optical film is obtained by depositing a transparent film on a transparent substrate and reading the transmittance or reflectance of allowing the monochromatic light to pass through the film. A method of controlling the vapor deposition film thickness by calculating the thickness is employed.
[0006]
On the other hand, in the sputtering apparatus, unlike the vapor deposition apparatus, the evaporation source is supplied in the form of a plate called a target having a very large area, and the plate that is the evaporation material is heated by the impact of the ions irradiated on the target. It can be evaporated without dissolving it. In many cases, the evaporation amount is proportional to the ionic current, so that it is relatively easy to control the deposition amount. For this reason, it has been used as an apparatus for mass production because of stable control of the evaporation amount and good maintainability of the evaporation source. There is no need to prepare an evaporation source every time as in the vapor deposition apparatus, and it is also a great merit that almost no maintenance is required until the lifetime of the target.
[0007]
However, in the case of a vapor deposition apparatus, the working pressure is a pressure of about 10 ⁻⁴ Pa, but in the case of sputtering, the pressure is about 10 ⁻¹ Pa. This pressure difference has a great influence on the distance from the evaporation source to the substrate. Uniform deposition from a small area evaporation source to a large area can be realized by increasing the deposition distance. Therefore, it is advantageous that the deposition pressure is low. However, since sputtering uses the discharge phenomenon, it must be performed at a higher pressure than the vapor deposition apparatus. Therefore, in order to ensure the evaporation amount, it is necessary to deposit at a deposition distance as short as the particles evaporated from the evaporation source are not scattered. Therefore, a device has been devised so that the evaporation source can be deposited in a large area with a large area.
[0008]
In order to control the deposited film thickness by sputtering, an almost predetermined film thickness can be obtained by accurately controlling the ion current and the required time. Therefore, the advanced vapor deposition control apparatus used for a vapor deposition apparatus is not used. In addition, since the evaporation is performed from a large area evaporation source to almost the same substrate as the evaporation source, there is no place to insert a monitor, and the substrate and film thickness cannot be captured by the monitor, so the ion current power control And time control methods have been established.
[0009]
As for optical films, in general, there is a long history, and a manufacturing method using a vacuum deposition apparatus has been established, so that many attempts have been made because sputtering is not suitable. Since the optical film is a very dense film, in many cases, a dense film is obtained by forming a film by vacuum deposition while heating the substrate in a high vacuum. Since sputtering is performed in an atmosphere of a sputtering gas, it has been said that it is difficult to obtain a dense film by incorporating the gas into the film. In addition, a film of oxide or the like must be performed by high-frequency reactive sputtering, which is not suitable for performing at high speed. Compared with metal sputtering using a normal DC power source, sputtering of a metal compound using a high frequency is so small that the film formation rate becomes half or less.
[0010]
As described above, conventionally, a metal oxide or metal nitride thin film for an optical thin film has not been formed so much by sputtering.
However, due to the good controllability of sputtering and the good maintenance of the evaporation source, the sputtering apparatus has begun to be used for metal oxide thin films. In 1987, a method of forming a thin film having a desired film thickness by repeating a process of depositing an ultra-thin film on a substrate under a reduced pressure atmosphere and a process of irradiating the thin film with an ion beam by Vacuum Instrument Industry Co., Ltd. Is published (JP-A-62-284076: Patent 2163322), and in 1988, an optical coating laboratory, Inc., USA announced a method of oxidizing a film with an ion source after forming a metal film. (USP # 2,851,095). Several methods for oxidizing the film after forming the metal film have been published. C-MAG, Twin-MAG, Plasmaguide method, radical source method and the like.
[0011]
However, these methods have a problem that the apparatus is very expensive and the control is very complicated.
In a sputtering apparatus proposed as a method and apparatus for forming an optical thin film, oxidation or nitridation is performed by irradiating the sputtered metal film with active species of oxygen or nitrogen. An ion source or a plasma source is used as means for obtaining the active species. The ion source, the plasma source, and other mechanisms are methods for ionizing a gas, and the energy levels of ions and active species differ depending on each method. However, the ion source is easy to control the energy of ions, but if it is intended to irradiate a wide area uniformly, a complicated ion beam scanning mechanism must be provided in the control mechanism, which is very expensive. The plasma source uses an electric field or a magnetic field for generating plasma, or a filament for generating thermal electrons. The apparatus for this is also expensive, and the control is complicated and not easy.
[0012]
Therefore, there has been a demand for a new means having a chemical conversion function that is simple, easy to control, and inexpensive as a method of irradiating the sputtered metal film with active species of oxygen and nitrogen.
Therefore, the invention of this application solves the problems of the prior art as described above, is useful for film formation of an optical thin film, etc., is easy to control with a simple structure, is inexpensive, high speed, and An object of the present invention is to provide a new sputtering apparatus that enables stable high-quality film formation and has a chemical conversion function for generating an oxide film, a nitride, or the like from a metal thin film.
[0013]
The invention of this application is to solve the above-mentioned problems. First, together with a metal thin film sputter film forming unit for forming a metal thin film, a metal is formed by a reaction by active gas plasma irradiation immediately after the metal thin film is formed. A sputtering apparatus provided with a metal compound film generating unit for forming a compound film, comprising a drum provided with a rotation mechanism, and a substrate or a group of substrates on which a metal compound thin film is generated on the surface of the drum. The metal thin film sputter film forming unit and the metal compound film generating unit are arranged facing the drum peripheral surface , and the metal compound film generating unit is provided with a reverse sputter electrode unit. Provided is a sputtering apparatus characterized in that a metal compound film is produced by sputtering at a part.
[0014]
The invention of this application, with the above apparatus, the second, with the reverse sputtering electrode portion are disposed the introduction of the active gas, the gas exhaust between the metal thin film sputtering unit providing a sputtering apparatus, wherein a part or the partition wall is provided, the third sputtering apparatus characterized in that it comprises a plurality of metal thin sputtering unit for depositing different metal thin film 4th is providing the sputtering device characterized by including the several metal compound film production | generation part which produces | generates a different metal compound film.
[0015]
And fifth , any one of the above sputtering apparatuses, which is an apparatus for forming an optical thin film, is provided. Regarding the invention of this application as described above, the following should be considered.
[0016]
That is, regarding the chemical conversion function for the formation of the oxide film or nitride film, according to the conventional knowledge, the simplest method is to extract ions from plasma generated by applying a negative bias voltage to the substrate. There is a method of irradiating the substrate. However, in this method, the potential applied to the substrate is determined by the ratio of the area of the substrate holder serving as the cathode and the area of the entire chamber serving as the anode. For this reason, in order to apply a high-frequency potential to the substrate holder in general, there is a problem that the desired bias voltage cannot be applied because the area of the substrate holder is too large or too small. In addition, in order to apply a high-frequency potential only to a necessary portion in a wide substrate, it is necessary to devise the structure of the holder. In order to devise the structure of this electrode, it was necessary to expose only the surface to be discharged and cover the other part with a shield. When the area of the shield portion is increased, the specific capacitance of the holder is increased, and it is difficult to achieve high-frequency power matching.
[0017]
On the other hand, the inventors have developed and obtained a patent for a reverse sputtering gun called a cup gun in order to apply a desired bias voltage as a reverse sputtering technique used in a sputtering apparatus. The patent numbers are Japan 1335314, US 4351714, UK 2077030, West Germany 3116731.
[0018]
This method is a technique invented from the fact that the bias voltage depends on the area ratio of an electrode to which a high frequency is applied and the area ratio of other electrodes surrounding the electrode.
[0019]
In other words, in order to apply a high frequency directly to the substrate holder, a special electrode structure had to be applied to the substrate holder. However, with this method, the substrate holder can be mounted without applying a high frequency. It is only necessary to form another electrode that encloses a part, and the substrate holder, which has to have a complicated structure because of fixing the substrate, has a structure that covers a part of this holder while maintaining the ground potential. The bias mechanism is characterized by being arranged.
[0020]
The reverse sputtering electrode can be freely selected for its surface area and size in order to obtain the optimum value of the reverse sputtering applied voltage.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
The invention of this application has the features as described above, and an embodiment thereof will be described below.
[0022]
In the sputtering apparatus according to the invention of this application, a substrate is set inside a vacuum chamber, and a metal target is also used as a sputtering source to form a metal thin film on the substrate. The vacuum chamber is provided with an inlet for introducing sputtering gas, an inlet for introducing active gas, and an outlet for discharging each of them.
[0023]
After the metal thin film is formed, a metal compound film is formed by a reaction by plasma irradiation with an active gas. The metal compound film generation unit for forming the metal compound film is provided with a reverse sputtering electrode. A high-frequency potential can be applied to the reverse sputtering electrode. By introducing an active gas in the vicinity of the reverse sputtering electrode, an active gas plasma is generated and reacted with the metal thin film for several seconds to form a metal compound film. And In particular, when this method is used for a large-area substrate, in order to improve the uniformity of the metal compound film, means for continuously moving the substrate holder while facing the reverse sputtering electrode is employed.
[0024]
The sputtering apparatus of the invention of this application includes a drum having a substrate or a group of substrates for generating a metal compound film on the surface thereof and is provided with a rotation mechanism. Then, while rotating the drum, a metal thin film and a metal compound film are generated on the substrate surface by the metal thin film sputter film forming unit and the metal compound film generating unit arranged facing the circumferential surface of the drum. A gas exhaust part or a partition is provided between the sputtering source and the metal thin film sputtering film forming part.
[0025]
With the above configuration, the sputtering apparatus of the invention of this application can form a large amount of a metal compound film having a uniform thickness in a short time.
In the sputtering apparatus of the invention of this application, an optical thin film can be formed by appropriately setting the sputtering source and the active gas.
[0026]
According to the invention of this application that can effectively realize the chemical conversion function, a reverse sputtering source is used as a method for oxidizing a metal film after film formation, and it is cheaper and more controllable than before. Is possible.
[0027]
Therefore, an example of this oxide film formation will be described below.
[0028]
【Example】
A drum rotary sputtering apparatus in which a normal metal film forming region and an oxidizing region are alternately provided is configured as shown in FIG. As an example, in a device in which a large number of 50 mm square substrates (1) are attached to a cylindrical outer wall having a diameter of 700 mmφ and a length of 700 mm, and two types of oxides of different materials are formed on this surface, they face each other and face the drum. For example, a metal target of each material is placed in a region 180 degrees apart, and a rectangular target that is long in the axial direction of the drum is used as the sputtering source (2) (3).
A reverse sputtering source (4) for forming an oxide film is disposed at a position 90 degrees away from each of the two targets. An oxygen outlet (5) or a partition wall (6) is provided between the sputtering source (2) (3) and the reverse sputtering source (4) to prevent the sputtering gas from coming and going, and the oxygen introduced into the reverse sputtering source (4). The active gas such as is prevented from flowing into the sputtering sources (2) and (3).
[0029]
In this state, for example, a Si target is mounted on the sputtering source (2), and argon sputtering is introduced from the sputtering gas inlet (7) to perform Si sputtering. The film thickness is, for example, 0.2 to 1.0 nm while the drum passes once through the surface of the sputtering source (2). At the same time, the reverse sputtering source (4) oxidizes the Si film by introducing oxygen gas from the active gas inlet (8). This also forms high-frequency plasma (5) that can be irradiated with ions necessary to oxidize the film of, for example, 0.2 to 1.0 nm formed by the target during one pass. A predetermined metal oxide can be obtained by continuously performing sputtering and reverse sputtering until a predetermined film thickness of, for example, 100 nm is obtained by this method. In the case where films having different refractive indexes such as antireflection films are alternately formed, a predetermined film structure can be obtained by forming and laminating only necessary film thicknesses.
[0030]
The drum-type sputtering apparatus using the reverse sputtering source is optimal as an apparatus capable of forming metal oxide or the like with low cost and good controllability because the plasma source is simple.
[0031]
Several methods for performing an optical thin film using a sputtering apparatus with good controllability have been proposed, but all use an expensive ion source or plasma source. On the other hand, according to the invention of this application, a sputtering apparatus for forming an optical thin film that can perform high-speed and stable sputtering using a reverse sputtering electrode that is simple, inexpensive, and has good controllability, etc. Will be provided.
[0032]
Of course, the invention of this application is not limited to the above drum rotating type sputtering apparatus. Needless to say, various forms and modes may be employed.
[0033]
【The invention's effect】
As described in detail above by the invention of this application, it is useful for film formation of an optical thin film, etc., is easy to control with a simple structure, is inexpensive, and is high-speed, stable and high-quality film formation. A new sputtering apparatus having a chemical conversion function for forming an oxide film, a nitride film and the like from a metal thin film is provided.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a basic configuration of a sputtering apparatus as an embodiment of the present invention.
[Explanation of symbols]
1 Substrate 2 Sputtering Source 3 Sputtering Source 4 Reverse Sputtering Source 5 Exhaust Port 6 Partition 7 Sputtering Gas Inlet 8 Active Gas Inlet

Claims (5)

A sputtering apparatus comprising a metal thin film sputter film forming unit for forming a metal thin film and a metal compound film generating unit for forming a metal compound film by a reaction by plasma irradiation of an active gas immediately after the metal thin film is formed, A drum having a rotation mechanism is provided, and a substrate or a group of substrates for generating a metal compound thin film is disposed on the surface of the drum, and a metal thin film sputter film forming unit and a drum surface facing the drum surface. A sputtering apparatus characterized in that a metal compound film generation unit is disposed , and the metal compound film generation unit includes a reverse sputtering electrode unit, and a metal compound film is generated by sputtering at the reverse sputtering electrode unit. . 2. The sputtering apparatus according to claim 1, wherein an active gas introduction section is provided in the reverse sputtering electrode section, and a gas exhaust section or a partition wall is provided between the reverse sputtering electrode section and the metal thin film sputtering film forming section. apparatus. The sputtering apparatus according to claim 1, further comprising a plurality of metal thin film sputter film forming units for forming different metal thin films. 4. The sputtering apparatus according to claim 1, further comprising a plurality of metal compound film generation units that generate different metal compound films. 5. The sputtering apparatus according to claim 1, wherein the sputtering apparatus is an apparatus for forming an optical thin film.

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