JP3762985B2 - Plasma deposition method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention systematically formable combinatorial forming a plurality of thin films, a novel plasma deposition method capable of performing at atmospheric pressure.
[0002]
[Prior art]
Combinatorial synthesis methods that have started in the fields of organic synthesis and pharmaceutical synthesis are now beginning to be applied to inorganic materials in general, and have become indispensable methods for finding materials with new functions.
For example, according to a combinatorial laser MBE (Molecular Beam Epitaxy) apparatus that combines a thin film technology by laser ablation and a mask mechanism, high-speed synthesis and function search of oxide thin films such as zinc oxide and titanium dioxide can be performed effectively. .
[0003]
In a film forming process using an example of a conventional combinatorial apparatus, when forming a thin film based on an oxide or the like, a target is placed below the substrate and a movable mask is set on the substrate surface on the target side. In this case, the atmosphere in the chamber is set to a high vacuum level.
[0004]
However, in the method of screening a movable mask on a substrate as in the conventional combinatorial apparatus, it is substantially impossible to perform a plasma decomposition reaction particularly in an atmosphere of atmospheric pressure.
Further, when a mask or the like is used, there is a problem that plasma generated under atmospheric pressure is extremely sensitive to electric field disturbance and the like, and it is difficult to control the plasma appropriately.
As described above, in the past, the combinatorial synthesis method could not be applied to atmospheric pressure plasma CVD (Chemical Vapor Deposition).
[0005]
[Problems to be solved by the invention]
In view of the above points, and an object thereof is to provide a particularly novel plasma deposition method capable of performing combinatorial deposition at atmospheric pressure.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has the following configuration.
That is, an invention according to claim 1, a plasma film forming method so as to combinatorial formed on the substrate a material gas by plasma decomposition, to form a material gas of desired composition, the material gas atmospheric The material gas is discharged from the minute opening formed in the cathode electrode while generating a plasma decomposition reaction while feeding the electrode unit installed under atmospheric pressure and moving the substrate relative to the cathode electrode. Then , a plurality of combinatorial films are systematically formed on the substrate by changing the supply amount of the material gas having the desired composition according to time .
[0011]
The invention of claim 2 provides the plasma film forming method according to claim 1, in a preliminary plasma decomposition chamber within said cathode electrode, which is characterized in that in advance plasma decomposing the fed the material gas It is.
[0012]
According to a third aspect of the present invention, in the plasma film forming method according to the first or second aspect , material particles outside the plasma generation region generated between the cathode electrode and the substrate are removed by an exhaust means. It is characterized by.
[0013]
The operation of the present invention is as follows. Atmospheric pressure plasma CVD can be performed by generating a plasma decomposition reaction by releasing a material gas from a minute opening of the cathode electrode while moving the substrate with respect to the electrode of the electrode unit installed under atmospheric pressure. it can. Thereby, a large number of samples in which parameters such as the composition of the material gas and the substrate temperature are changed can be efficiently manufactured on one substrate.
[0014]
Further, in the above case, in the preliminary plasma decomposition chamber inside the cathode electrode, it is possible to perform the plasma decomposition reaction more completely and properly by previously performing plasma decomposition on the material gas fed thereto.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, based on the drawings, illustrating a preferred embodiment of the plasma film forming method according to the invention.
1 and 2 show a schematic configuration of a plasma film forming apparatus used in the present invention in this embodiment. The plasma film forming apparatus used in the present invention is one in which a material gas is plasma-decomposed to form a film on a substrate.
In FIG. 1, the plasma film forming apparatus includes an electrode unit including a material gas unit 10 that forms and feeds a material gas having a desired composition, and a cathode electrode 21 and an anode electrode 22 that generate a plasma decomposition reaction on a substrate 23. 20 and a stage unit 40 that supports the substrate 23 so as to be movable with respect to the cathode electrode 21.
[0016]
The material gas unit 10 has a material gas 11 filled in a gas cylinder or the like. The material gas 11 includes a plurality of types of material gases such as A-type gas 11a, B-type gas 11b, and C-type gas 11c. These material gases 11 may be vaporized from a gas or liquid state, and are mixed by the gas mixer 12 so as to have a desired composition. The material gas 11 includes an organic material such as acetylene, ethylene, or benzene, or a gas that is a raw material of an inorganic material such as SiO ₂ or TiO ₂ .
[0017]
The gas mixer 12 can mix a total of four types of gas, that is, at least two temperature-controlled gas systems and two systems having a function of vaporizing a liquid raw material. The gas mixer 12 is configured to be controlled by the computer 1, and feeds the mixed material gas 11 to the electrode unit 20 via the feed pipe 13.
In order to easily generate plasma discharge at atmospheric pressure, it is preferable to simultaneously feed a rare gas such as Ar or He gas that is easily ionized together with the material gas 11. The material gas 11 may be a mixed gas with these rare gases. Therefore, the material gas includes a mixed gas of a gas containing a film forming material and a rare gas.
[0018]
The electrode unit 20 is installed under atmospheric pressure and includes a cathode electrode 21 and an anode electrode 22. The cathode electrode 21 is arranged and fixed at a predetermined position by a frame or a frame body 24 (see FIG. 2), and high frequency power (13.56 MHz) generated by the high frequency generator 25 is applied via the matching circuit 26. ing.
[0019]
FIG. 2 is a cross-sectional view showing a configuration example around the electrode unit in the embodiment of the present invention. The high frequency power passed through the matching circuit 26 from the high frequency generator 25 is connected to the connector 27. A copper wire 28 connected to the connector 27 is connected to the cathode electrode 21 and the connector 29 through the feed pipe 13.
Although not shown, the connector 29 is connected to a well-known high-frequency force meter to monitor the high-frequency power and reflected power supplied to the plasma and generate a high-frequency so that an optimum matching state can be obtained. The device 25 and the matching circuit 26 are configured to be controlled by the computer 1.
[0020]
Further, in FIG. 2, a substrate 23 is placed on the anode electrode 22, and the cathode electrode 21 is disposed in parallel above the substrate 23. This arrangement is a capacitively coupled plasma generation method. A dielectric (alumina) 30 around the cathode electrode 21 is provided to insulate the cathode electrode 21 from the frame 24.
The gap (gap) between the cathode electrode 21 and the substrate 23 is, for example, about 2 mm. At this time, the power of the high frequency generator 25 applied for plasma generation is approximately 30 W to 120 W.
The power of the high-frequency generator 25 varies depending on the shape of the cathode electrode 21, the gap, the material gas, and the like.
[0021]
The anode electrode 22 has a built-in heater 31 for heating the substrate, and the heater 31 can raise the temperature. At this time, the temperature of the substrate 23 is detected by the thermocouple 32. The substrate temperature may be appropriately selected according to the film formation target.
Further, in order to adjust the plasma potential, a predetermined bias voltage is applied to the anode electrode 22 by the bias power source 33 so as to be superimposed on the high frequency power. The bias power supply 33 is configured to be controlled by the computer 1.
[0022]
The stage unit 40 supports the anode electrode 22 via the insulating plate 34. The anode electrode 22 can be moved in the XY axis and further in the Z direction using the stepping motor as a drive source. Operation of the stage unit 40 is controlled by the computer 1. Thereby, the board | substrate 23 installed on the anode electrode 22 can be moved to a desired position at a desired speed.
[0023]
As shown in FIG. 2, plasma P is generated between the cathode electrode 21 and the substrate 23. In this case, an exhaust means for removing material particles outside the plasma P generation region is provided. In this embodiment, as exhaust means, a plurality of communication holes 35 communicating with the upper inside of the cathode electrode 21 are formed around the center of the cathode electrode 21.
[0024]
FIG. 3 is a plan view and a perspective view showing a configuration example around the cathode electrode in the embodiment of the present invention.
FIG. 3A is a plan view of the cathode electrode 21 of the plasma film forming apparatus of the present invention as viewed from the substrate 23 side. As shown in the figure, the cathode electrode 21 has a substantially box-shaped bottomed structure, and a minute opening for releasing the material gas 11 is formed at the lower end (bottom). In this embodiment, a slit 21a is formed as a minute opening. The slit 21 a is formed in the Y direction orthogonal to the moving direction X of the anode electrode 22. The specific dimensions of the slit 21a are set to, for example, a width of 0.5 mm and a length of 30 mm. The specific dimension of the slit 21a as the minute opening of the cathode electrode 21 is not limited to the case of the above embodiment, and can be appropriately changed as necessary.
In addition to the slit, a large number of small holes may be formed in a dot shape. In this case, dot-like patterns of small holes can be arranged in a staggered pattern, for example.
[0025]
FIG. 3B is a perspective view around the cathode electrode. The figure also shows the arrangement of the substrate 23 arranged on the cathode electrode 21 and the anode electrode 22. The arrows in the figure indicate that the anode electrode 22 is driven in the X direction by the stage unit 40. Material gas is released from the slit 21 a of the cathode electrode 21, and plasma P is generated between the cathode electrode 21 and the anode electrode 22.
[0026]
FIG. 4 is a diagram showing the operation of the plasma film forming apparatus in the embodiment of the present invention. In the figure, when the film is formed by changing the amounts of the A-type gas 11a and the B-type gas 11b in the material gas 11 according to time, the composition of the film changes to the products A ′ and B ′ according to the change in the gas composition to be supplied. Is obtained.
[0027]
The plasma film forming apparatus used in the present invention is configured as described above, and the plasma film forming apparatus and film forming method operate as follows.
A material gas 11 having a desired composition is formed by the gas mixer 12, and the mixed material gas 11 is fed to the electrode unit 20 through the feed pipe 13. Then, it is possible to generate a plasma decomposition reaction under atmospheric pressure by discharging the material gas 11 from the slit 21 a formed in the cathode electrode 21 while moving the substrate 23 relative to the cathode electrode 21.
[0028]
At that time, by arbitrarily changing parameters such as the moving speed of the substrate 23, the composition of the gas flow rate during film formation, the temperature of the substrate 23, etc., samples of a plurality of types of systematic conditions are placed on one substrate. Can be produced efficiently.
Thereby, what is called a combinatorial film | membrane which can form a some thin film systematically by atmospheric pressure plasma reaction can be produced efficiently.
[0029]
FIG. 5 is a diagram showing an example of the film forming composition in the embodiment of the present invention, and the composition of a sample obtained by changing the film forming composition of the composition plasma copolymer of ethylene and CO ₂ was examined. As film forming conditions, ethylene was first supplied and then CO ₂ supply was increased. In the figure, the horizontal axis is the position (mm) in the X direction of the sample, and the vertical axis is the infrared absorption ratio of C = O and C—H determined from the infrared absorption spectrum measured by the FTIR analyzer. The infrared absorption ratio is a ratio of a signal of C = O wave number 1716 cm ^-1 and C-H wave number 2957 cm ^-1 .
As is apparent from the figure, when X = 0, the infrared absorption ratio is about 0.01, and when X = 60 mm, the ratio increases almost linearly to 0.15. This shows that the amount of CO ₂ taken up gradually increases.
[0030]
When plasma deposition is performed while changing the composition of the film as described above, if the material particles as shown by the dotted arrows in FIG. Can no longer be controlled. In this case, unnecessary material particles as described above can be sucked and discharged from the communication hole 35.
Thereby, the film-forming composition can be accurately controlled by discharging particles outside the region where the plasma P is generated.
[0031]
FIG. 6 is a cross-sectional view showing a configuration example around the electrode unit in the second embodiment of the present invention.
As shown in the figure, the plasma film forming apparatus is provided with a preliminary plasma decomposition chamber 36 for previously decomposing the material gas 11 into the cathode electrode 21. The preliminary plasma decomposition chamber 36 is formed of an insulator (quartz tube or the like), and a high frequency coil 37 is wound around it.
Although not shown, the high frequency coil 37 wound around the preliminary plasma decomposition chamber 36 is supplied with high frequency power by a separate 13.56 MHz high frequency generator independently of the high frequency generator 25. Yes. This arrangement is an inductively coupled plasma generation method.
[0032]
According to the second embodiment, the material gas 11 fed to the electrode unit 20 is plasma-decomposed in advance in the preliminary plasma decomposition chamber 36 (plasma P ′), and then released from the slit 21a to be plasma-decomposed (plasma). P).
As described above, the material gas 11 is previously plasma-decomposed in the preliminary plasma decomposing chamber 36, whereby the plasma decomposing reaction can be performed more completely and properly.
[0033]
Plasma deposition method of the present invention can be further applied to adhesion of the coating film for modifying the surface of plastic or rubber. At this time, since the apparatus operates at atmospheric pressure, the apparatus and time required for evacuation become unnecessary, and the cost can be greatly reduced.
[0034]
Although the present invention has been described above with reference to the embodiment, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. An effect can be obtained.
In the above-described embodiment, it has been described that the slit 21a of the cathode electrode 21 has a slit or dot shape, but the shape can be appropriately determined according to the purpose of film formation.
Further, the frequency for generating plasma is not limited to 13.56 MHz, and may be another frequency or microwave, and can be appropriately selected to be an optimum frequency.
[0035]
【The invention's effect】
According to the present invention described above, the plasma in the film forming method, can be effectively applied to combinatorial methods, one substrate a number of samples of systematic conditions of changing parameters such as substrate temperature It can be efficiently produced on top.
Furthermore, since the plasma film-forming reaction can be appropriately performed under atmospheric pressure, there is an advantage that it can be operated at a low cost without requiring a large vacuum facility or the like.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a plasma film forming apparatus in an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a configuration example around an electrode unit in the embodiment of the present invention.
FIGS. 3A and 3B are a plan view and a perspective view showing a configuration example around an electrode unit in the embodiment of the present invention. FIGS.
FIG. 4 is a diagram showing the operation of the plasma film forming apparatus in the embodiment of the present invention.
FIG. 5 is a graph showing an example of a film formation composition in the embodiment of the present invention.
FIG. 6 is a cross-sectional view showing a configuration example around an electrode unit in a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Computer 10 Material gas unit 11 Material gas 12 Gas mixer 13 Feed pipe 20 Electrode unit 21 Cathode electrode 21a Slit 22 Anode electrode 23 Substrate 24 Frame 25 High frequency generator 26 Matching circuit 27, 29 Connector 28 Conductor 30 Dielectric 31 Heater 32 Thermocouple 33 Bias power supply 34 Insulating plate 35 Multiple communication holes 36 Preliminary plasma decomposition chamber 37 High frequency coil 40 Stage unit P Plasma

Claims (3)

A plasma film forming method in which a material gas is plasma decomposed to form a combinatorial film on a substrate,
A material gas having a desired composition is formed, the material gas is fed to an electrode unit installed under atmospheric pressure, and the substrate is moved relative to the cathode electrode, while the minute gas formed on the cathode electrode is formed. A plurality of combinatorial films are systematically formed on the substrate by discharging the material gas from the opening to generate a plasma decomposition reaction and changing the supply amount of the material gas having the desired composition according to time. A plasma film forming method. 2. The plasma film forming method according to claim 1 , wherein the supplied material gas is plasma-decomposed in advance in a preliminary plasma decomposition chamber inside the cathode electrode. And removing the exhaust means of the plasma generation region outside of the material particles generated between the substrate and the cathode electrode, a plasma film forming method according to claim 1 or 2.

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