JP2572270B2 - Ultra-high purity film forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to an apparatus for forming an ultra-high-purity thin film, in particular, a quadrupole mass spectrometer, which allows only specific ions to be applied to the surface of an object under ultra-high vacuum. The present invention relates to an apparatus for forming a high-purity thin film by depositing on a thin film.

(Prior art) At present, various film forming methods have been proposed and put into practical use, but in recent years, it is considered that a film having excellent properties that cannot be formed by ionization vapor deposition using other methods can be formed. ,Attention has been paid.

Among them, recently, there has been a rare attempt to prepare a thin film using a mass-separated ion beam. Since this method can selectively deposit only specific ions, it can be said that this method is suitable for producing a thin film having extremely high purity. Fig. 5 shows an example of the equipment used in these methods. Most of the main parts use the mechanism and technology of the ion irradiation system of the conventional secondary ion mass spectrometer (SIMS). Yes, when used for thin film production, there are the following problems.

(Problems to be Solved by the Invention) (1) A fan magnetic field type is used as a mass separator. Therefore, it is large, heavy, and has a long ion transport distance.

(2) Energy of ion beam (several 100 eV to several tens keV)
Is relatively high, and it is difficult to control the film quality. In order to control the film quality, it is important to use ions in the low energy region (100 eV or less) and control the ions.

(3) A high-intensity complicated ion source is used. Therefore, the versatility is poor, and the generated ionic species are limited.

(4) Long ion transport system (often over 1m)
Also, two or three sets of precise lens systems are required.

(5) As a whole, it is large, complicated, difficult to operate, and expensive.

An apparatus using a method different from that of the SIMS ion irradiation system is not considered as a thin film manufacturing apparatus (for example, the degree of vacuum is low), and is not suitable for manufacturing a high-purity film using the apparatus.

(Means for Solving the Problems) The present invention seeks to obtain a film forming apparatus that does not include the above-described problems, and provides an ionization vapor deposition apparatus that employs a quadrupole mass separator as a mass analyzer. An ultra-high vacuum (10 ⁻⁷ Pa or less) is set in the film growth chamber to enable production of an ultra-high-purity thin film.

(Example) Example 1 Fig. 1 shows a schematic view of an ultra-high purity film forming apparatus of the present invention. This apparatus comprises an ion generation chamber 1, a mass separation chamber 2, and a film growth chamber 3, to which a gas introduction system 4 and an exhaust system are attached.

As a method for generating ions, various plasma generation methods, electron impact methods, surface ionization methods, and the like can be used. In particular, when the electron cyclotron resonance discharge or the electron beam excitation discharge method is used, the pressure in the ion generation chamber 1 is 10 ⁻² Pa or less, which is lower than that of other plasma generation methods (about 1 Pa). Since it can be lowered by about an order of magnitude, differential evacuation is facilitated, which is advantageous for making the film growth chamber 3 into an ultra-high vacuum.

The mass separation chamber 2 contains a quadrupole mass analyzer 6.

The ions generated in the ion generation chamber pass through the hole 5 and are mass-separated by a quadrupole mass spectrometer, and have a predetermined mass-to-charge ratio (m / n, where m is the ion mass and n is the number of charges). Only the ions pass through the hole 7 between the film growth chamber and deposit on the substrate 8 to form the film 10. By attaching a simple cylindrical lens or the like to the holes 5 and 7 as necessary, the control of the ion beam becomes easy.

When the apparatus has the above structure, the following advantages are obtained as compared with the related art.

(1) The distance between the ion generation chamber 1 and the film growth chamber 3 is increased
It can be reduced to 1/5 or less (20cm or less).

(2) Since various methods can be used as an ion generation method, generation of various ions is facilitated, and an application field is expanded. Further, no special ion source (for example, Duoplasmatron) is required. Furthermore, since a high-voltage power supply for extracting and accelerating ions is not required, the operation is safe and easy.

(3) It becomes easy to attach an exhaust system with a large exhaust speed to the mass separation chamber. Accordingly, differential pumping becomes easy, and it becomes relatively easy to make the vacuum in the film growth chamber an ultra-high vacuum of 10 ⁻⁷ Pa or less. Further, if necessary, it is possible to make an ultra-high vacuum of 10 ⁻⁸ Pa or less. Therefore, ultra-high-purity film formation is possible.

(4) No precise lens system is required. Specifically, it is sufficient to attach one set of a simple cylindrical lens to the hole 5.

(5) The ion energy in the low energy region (100 ev or less) can be easily controlled by applying a potential to the substrate.

(6) The structure is simple, lightweight and inexpensive. Also, the operation becomes easy. For example, the weight can be reduced to 1/50 or less as compared with the case where a conventional fan-shaped magnetic field is used.

(7) Not only positive ions but also negative ions can be easily formed. This is because the quadrupole mass spectrometer can perform mass separation regardless of the sign of the ion. Therefore, it is easy to switch between positive and negative ions, and to form a film using positive and negative ions alternately.

(8) Since it can be made small and lightweight, the ion generation chamber 1 and the mass separation chamber 2 can be easily attached to another surface analyzer, and the state of film growth can be easily checked on the spot.

Embodiment 2 FIG. 2 shows another embodiment. One set of the ion generation chamber 1a, the mass separation chamber 2a, and the ion generation chamber 1
b, with a mass separation chamber 2b attached. In addition, members corresponding to the embodiment shown in FIG. 1 are denoted by the same reference numerals.

With such a structure, (1) different ion species and positive and negative ions can be simultaneously or alternately deposited on the substrate. Therefore, (2) film formation of a compound which is difficult to grow and (3) epitaxial growth at a lower temperature can be performed by utilizing the electrostatic attraction between ions. This is an important new epitaxial method. (4) Four to five sets of ion generation chambers 1 and mass separation chambers 2 can be attached to the film growth chamber 3 by the same method, and alternate film formation by simultaneous or plural combinations of 4 to 5 types of elements can be performed. It becomes possible.

Third Embodiment FIG. 3 shows an example in which an electron shower source 11 is provided in the film growth chamber 3. This makes it possible to control the charge-up effect at the time of depositing ions on the insulator or growing the insulator film.

FIG. 4 shows an example in which the ion beam deflecting electrode 13 is mounted inside the film growth chamber 3 at the ion entrance hole 7 in combination with a simple cylindrical lens 12. By doing so, the ion generation chamber 1 or the mass separation chamber 2 during film growth can be obtained.
And mixing of impurity gas directly incident from the substrate.

(Effect of the Invention) As described above, the film forming apparatus of the present invention is an ionization vapor deposition apparatus using a quadrupole mass analyzer as a mass separator. By this method, the ion transport distance can be shortened to 1/5 of the conventional one, and the weight is 1/1 compared to the mass separator using the fan-shaped magnetic field.
Can be less than 50.

Further, switching of positive and negative ions can be easily performed by the same film forming apparatus, and various thin film manufacturing methods can be used, so that the application field is expanded. Furthermore, since the film can be formed with low energy, it is easy to control the ion energy, which is considered to affect the film quality, and it is possible to provide a small, inexpensive, and more operable device as a whole. It was possible to obtain an effect that was not seen.

In addition, the present apparatus has extremely remarkable features, such as a new method of growing an epitaxial film utilizing electrostatic attraction of positive and negative ions, which is completely different from the conventional method.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a configuration of a main body of an ultrahigh-purity film forming apparatus according to a first embodiment of the present invention, FIG. 2 is a conceptual diagram of a two-element simultaneous film forming apparatus according to the second embodiment, FIG. FIG. 5 is a conceptual diagram of a component arrangement showing a modification of the film growth chamber, and FIG. 5 is a conceptual diagram showing a configuration example of an ionization vapor deposition apparatus provided with a conventional mass separator. 1: Ion generation chamber, 2: Mass separation chamber 3: Membrane growth chamber, 4: Gas introduction system 5, 7: Hole, 6: Quadrupole mass analyzer 8: Substrate, 9: Ion 10: Membrane, 11: Electron Shower source 12: cylindrical lens, 13: deflection electrode

Claims (6)

(57) [Claims] An ion generation chamber, a mass separation chamber, and a membrane growth chamber, wherein only specific ions separated by a quadrupole mass analyzer in the mass separation chamber among the ions from the ion generation chamber are separated from each other. An ultra-high-purity film forming apparatus characterized in that it is deposited on an object surface under ultra-high vacuum in a film growth chamber. 2. The ultra-high-purity film forming apparatus according to claim 1, wherein an electron cyclotron resonance discharge is used as a method for generating ions in the ion generation chamber. 3. An ultra-high-purity film forming apparatus according to claim 1, wherein an electron beam-excited discharge is used as an ion generation method in the ion generation chamber. 4. An ultra-high purity film forming apparatus according to claim 1, wherein ions having a positive charge and a negative charge are alternately or simultaneously deposited. 5. An ultra-high purity film forming apparatus according to claim 4, wherein ions having a positive charge and a negative charge are alternately or simultaneously deposited to form a superlattice film. 6. An ultra-high-purity film forming apparatus according to claim 4, wherein positive ions and negative ions are alternately or simultaneously deposited on the substrate for epitaxial growth.