JP3717655B2 - Plasma generator and thin film forming apparatus - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a plasma generating apparatus configured to guide electrons to the outside from plasma generated inside, and a thin film forming apparatus using such a plasma generating apparatus.
[0002]
[Prior art]
Plasma generators are used in thin film forming apparatuses such as ion plating apparatuses and plasma CVD apparatuses.
[0003]
FIG. 1 shows an outline of an ion plating apparatus provided with a plasma generator, and FIG. 2 shows details of the plasma generator. In the figure, reference numeral 1 denotes a vacuum vessel of an ion plating apparatus, and a crucible 3 containing an evaporation material 2 and an electron gun 4 for irradiating the evaporation material with an electron beam are provided at the bottom of the vacuum vessel. Yes. On the other hand, a substrate 6 to which a negative voltage is applied from the substrate power supply 5 is attached to the upper part of the vacuum vessel. In the figure, reference numeral 7 denotes a plasma generator supported at the bottom of the vacuum vessel by a support base 8, the details of which will be described later. An electron beam from the plasma generator is irradiated between the substrate 6 and the crucible 3. It is made like this. In the figure, 9 is a vacuum pump, 10 is a valve, 11 is a reactive gas cylinder, 12 is a valve, 13 is a discharge gas cylinder, and 14 is a valve.
[0004]
FIG. 2 shows an outline of the plasma generator, and 15 is a case for forming a discharge chamber. A cathode 16 is disposed in the case, and the cathode is connected to a heating power source 17 and also to a discharge power source 18. The case is provided with a discharge gas supply pipe 19, and an inert gas such as Ar gas is introduced into the case from the discharge gas cylinder 13 through the discharge gas supply pipe 19. At one end of the case, a ring-shaped anode 21 is provided on the case 15 via an insulator 20. A shield electrode 22 is arranged inside the anode so that electrons from the cathode 16 are not directly irradiated onto the anode. The shield electrode forms an orifice through which an electron beam passes simultaneously. The case 15 is connected to the discharge power source 18 via a resistor R1, and the anode 21 is connected to the discharge power source 18 via a resistor R2. Further, the vacuum vessel 1 is connected to a discharge power source 18 via a resistor R3. The resistance values of these resistors are usually R1 R3> R2, and most of the current flowing through the discharge power supply 18 is a discharge current between the anode 21 and the cathode 16. In the figure, reference numeral 23 denotes a coil constituting an electromagnet for shaping the discharge current in the case, and is provided outside the case.
[0005]
In the ion plating apparatus having such a configuration, first, the valve 10 is opened, and the vacuum vessel 1 and the case 15 are evacuated by the vacuum pump 9 until a predetermined pressure is reached. Then, the valve 14 is opened, a predetermined amount of discharge gas (for example, Ar gas) is introduced into the case 9 from the discharge gas cylinder 13 via the discharge gas supply pipe 19, the pressure in the case 15 is increased, and the cathode 16 is heated to the power source. 17 is heated to a temperature at which thermionic electrons can be emitted.
[0006]
Next, a predetermined current is passed through the coil 23 to generate a magnetic field necessary for ignition of the plasma and maintenance of a stable plasma in the axial direction of the electron beam. In this state, when a predetermined voltage is applied from the discharge power supply 18 to the cathode 16 and the anode 21, an initial discharge is generated between the cathode 16 and the case 15. Plasma is generated in the case 15 by this initial discharge as a trigger. The electrons in the discharge plasma are focused in the axial direction of the electron beam due to the influence of the magnetic field formed by the coil 23, and the vacuum vessel 1 is generated by an accelerating electric field generated near the tip of the shield electrode 22 near the anode 21. Pulled in.
[0007]
On the other hand, in the inside of the vacuum vessel 1, the electron beam from the electron gun 4 is irradiated toward the material to be evaporated 2, and the material to be evaporated is heated and evaporated. Further, a reaction gas (for example, oxygen gas) is introduced into the vacuum container 1 from the reaction gas cylinder 11 by opening the valve 12. The electron beam extracted from the plasma generator 7 collides with the reaction gas and evaporated particles introduced into the vacuum vessel 1, and excites and ionizes them to form plasma P in the vacuum vessel 1. The ionized evaporated particles in the plasma are attracted to and attached to the substrate 6, and evaporated particles are formed on the substrate.
[0008]
The electrons drawn out from the plasma generator 7 into the vacuum vessel 1 and the electrons in the plasma P flow into the vacuum vessel 1 and the anode 21 and maintain stable discharge. The strength of the plasma P can be controlled by the discharge gas flow rate and the heating temperature of the cathode 16. In addition, for the resistors R2 and R3, the relationship between these resistance values is R3> R2, but the relationship between the resistance values is arbitrarily changed to R3 = R2, R3> R2, R3 <R2, R3 R2. The amount of current flowing through the anode 21 and the vacuum vessel 1 can be freely selected.
[0009]
[Problems to be solved by the invention]
Now, such a plasma generator actively draws electrons in the plasma in the case 15 into the vacuum vessel 1, and ions in the plasma P formed in the vacuum vessel 1 are in the vacuum. The plasma is captured by the magnetic field formed by the electron beam itself drawn into the container 1, and travels backward according to the trajectory of the electron beam to sputter the plasma generator. In particular, the tip of the shield electrode 22 provided so as to surround the trajectory of the electron beam is significantly consumed by such sputtering. Therefore, the shield electrode 22 must be periodically replaced.
[0010]
However, the shield electrode 22 is usually made of, for example, an expensive refractory metal material (eg, tantalum) in order to minimize the influence of the radiant heat from the facing cathode 16. Therefore, if the shield electrode is periodically replaced, the cost becomes extremely high.
[0011]
Further, since the shield electrode is fixed to the case 15, when replacing the shield electrode, the plasma generator itself must be taken out of the vacuum vessel 1 and disassembled. This task is cumbersome and time consuming. Moreover, if this work is performed regularly, poor work efficiency and time loss become a major problem.
[0012]
The present invention has been made to solve such problems, and an object of the present invention is to provide a novel plasma generating apparatus and thin film forming apparatus.
[0013]
[Means for Solving the Problems]
The plasma generator according to the present invention is provided with a discharge chamber, a cathode disposed in the discharge chamber, and an end electrically insulated from the discharge chamber at the end of the discharge chamber, and the discharge chamber is provided at the center of the discharge chamber. A ring-shaped anode having an opening to be opened with respect to the vacuum vessel, and a cylinder attached to the discharge chamber so as to surround a cathode facing surface of the anode including at least an inner surface of the opening of the anode with respect to the cathode And a discharge power source for applying a discharge voltage between the cathode and the anode, and means for supplying a discharge gas into the discharge chamber. plasma the electrons in the plasma were configured to irradiate in the vacuum container through the inner portion of the tubular shield member surrounds an opening inside of the anode relative to the cathode In raw device, wherein the ions in the plasma formed in the vacuum vessel is captured by the magnetic field formed by the electron beam itself drawn into the vacuum chamber from the discharge chamber and enters retrograde accordance trajectory of the electron beam The portion of the cylindrical shield body facing the inside of the opening of the anode is made of a heat-resistant shielding material, the other portion is made of an ion-resistant sputtering material, and the former part is formed separately from the latter part, It is characterized in that it is detachably attached to the latter part .
[0015]
The thin film forming apparatus of the present invention is provided with a discharge chamber, a cathode disposed in the discharge chamber, an end of the discharge chamber electrically insulated from the discharge chamber, and a discharge chamber at a central portion thereof. A ring-shaped anode having an opening for opening an external vacuum vessel, and a cathode-facing surface of the anode including at least an inner surface of the opening of the anode with respect to the cathode. A cylindrical shield body, a discharge power source for applying a discharge voltage between the cathode and the anode, and means for supplying a discharge gas into the discharge chamber, and formed in the discharge chamber The vacuum vessel is configured such that electrons in the plasma are irradiated into the vacuum vessel through the inside of the cylindrical shield body that surrounds the inside of the opening of the anode with respect to the cathode. Ions in the plasma formed inside are captured by the magnetic field formed by the electron beam itself drawn into the vacuum chamber from the discharge chamber, and the tube shield of the cylindrical shield body incident in reverse according to the trajectory of the electron beam. The part facing the inside of the opening of the anode is made of heat-resistant shielding material, the other part is made of ion-resistant sputtering material, the former part is formed separately from the latter part, and is detachably attached to the part The plasma generating apparatus is provided, and ions in the plasma generated by irradiating the vapor deposition material in the vacuum vessel with electrons from the plasma generating apparatus are attached to the substrate.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0017]
FIG. 3 shows an example of the plasma generator of the present invention. In the figure, the same reference numerals as those used in FIG. 2 denote the same components.
[0018]
Differences in configuration between the apparatus shown in FIG. 3 and the apparatus shown in FIG. 2 will be described below.
[0019]
In FIG. 2, the shield electrode 22 is an integral body, and is made of a refractory metal material such as tantalum or molybdenum, and is fixed to the case 15. On the other hand, in the apparatus of FIG. 3, the shield electrode 25 has two parts, that is, a shield body 26 for preventing electrons from the cathode 16 from being directly irradiated to the anode 21 and the case 15, and the inside and outside of the case. And an orifice body 27 for passing electrons from plasma generated in the case. The shield body 26 is made of a refractory metal material such as tantalum or molybdenum, and is fixed to the case 15. On the other hand, the orifice portion 27 is made of a material that is difficult to be ion-sputtered, for example, carbon, and is detachably attached to the distal end portion of the shield body 26 by, for example, a screw-in type or a plug-in type.
[0020]
When the plasma generating apparatus provided with the shield electrode having such a configuration is applied to, for example, an ion plating apparatus as shown in FIG. 1, it operates as follows.
[0021]
First, the valve 10 is opened, and the vacuum vessel 1 and the case 15 are evacuated by the vacuum pump 9 until a predetermined pressure is reached. Then, the valve 14 is opened, a predetermined amount of discharge gas (for example, Ar gas) is introduced into the case 9 from the discharge gas cylinder 13 via the discharge gas supply pipe 19, the pressure in the case 15 is increased, and the cathode 16 is heated to the power source. 17 is heated to a temperature at which thermionic electrons can be emitted.
[0022]
Next, a predetermined current is passed through the coil 23 to generate a magnetic field necessary for ignition of the plasma and maintenance of a stable plasma in the axial direction of the electron beam. In this state, when a predetermined voltage is applied from the discharge power supply 18 to the cathode 16 and the anode 21, an initial discharge is generated between the cathode 16 and the case 15. Plasma is generated in the case 15 by this initial discharge as a trigger. Electrons in the discharge plasma are focused in the axial direction of the electron beam due to the magnetic field formed by the coil 23, and enter the vacuum chamber 1 by an accelerating electric field generated near the tip of the orifice body 27 of the shield electrode 25. It is pulled out. The thermoelectrons from the cathode 16 are not directly applied to the anode 21 or the case 15 by the shield body 26 of the shield electrode 25.
[0023]
On the other hand, in the inside of the vacuum vessel 1, the electron beam from the electron gun 4 is irradiated toward the material to be evaporated 2, and the material to be evaporated is heated and evaporated. Further, a reaction gas (for example, oxygen gas) is introduced into the vacuum container 1 from the reaction gas cylinder 11 by opening the valve 12. The electron beam extracted from the plasma generator 7 collides with the reaction gas and evaporated particles introduced into the vacuum vessel 1, and excites and ionizes them to form plasma P in the vacuum vessel 1. The ionized evaporated particles in the plasma are attracted to and attached to the substrate 6, and evaporated particles are formed on the substrate.
[0024]
Now, the ions in the plasma P formed in the vacuum vessel 1 are captured by the magnetic field formed by the electron beam itself extracted in the vacuum vessel 1, and reversely generate according to the trajectory of the electron beam. Coming towards device 7 Most of the ions hit the tip of the orifice body 27 of the shield electrode 25 provided so as to surround the trajectory of the electron beam.
[0025]
However, since the orifice body 27 is made of a material that is difficult to be sputtered by the impact of ions, the wear due to sputtering is extremely small. For this reason, the frequency of replacement of the shield electrode due to the consumption of the shield electrode is remarkably reduced. When replacing the shield electrode, the entire shield electrode is not replaced, but only the orifice body 27 is replaced. In addition, since this orifice body is made of a material that is considerably cheaper than the refractory metal material that has been used in the past, the cost of replacing the shield electrode (substantially replacing the orifice body) can be significantly reduced. .
[0026]
Moreover, since the orifice body 27 is attached to the shield body 26 fixed to the case 15 by a screw-in type or a plug-in type, at the time of replacement, the plasma generator itself is taken out from the vacuum vessel and disassembled. Since it is no longer necessary and only the orifice body needs to be removed from the shield body 26, the replacement work is extremely simple and can be done in a short time.
[Brief description of the drawings]
FIG. 1 shows an outline of an ion plating apparatus provided with a plasma generator.
FIG. 2 shows an outline of a conventional plasma generator.
FIG. 3 shows an example of a plasma generator of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Vacuum container, 2 ... Material to be evaporated, 3 ... Crucible, 4 ... Electron gun, 5 ... Substrate power supply, 6 ... Substrate, 7 ... Plasma generator, 8 ... Support stand, 9 ... Vacuum pump, 10 ... Valve, 11 ... reactive gas cylinder, 12 ... bulb, 13 ... discharge gas cylinder, 14 ... valve, 15 ... case, 16 ... cathode, 17 ... heating power supply, 18 ... discharge power supply, 19 ... discharge gas supply pipe, 20 ... insulator, 21 ... anode, 22, 25 ... Shield electrode, 26 ... Shield body, 27 ... Orifice body

Claims (2)

A discharge chamber, a cathode disposed in the discharge chamber, and an end portion of the discharge chamber are provided to be electrically insulated from the discharge chamber, and the discharge chamber is opened to an external vacuum vessel at the center thereof A ring-shaped anode having an opening, a cylindrical shield body mounted in the discharge chamber so as to surround a cathode facing surface of the anode including at least an inner surface of the opening of the anode with respect to the cathode , and the cathode And a discharge power supply for applying a discharge voltage between the anode and the anode, and means for supplying a discharge gas into the discharge chamber, and electrons in the plasma formed in the discharge chamber in the plasma generating apparatus configured to irradiate in the vacuum vessel opening inner through the inner portion of the tubular shield member surrounds with respect to the cathode in the vacuum vessel The ions in the formed plasma are captured by the magnetic field formed by the electron beam itself drawn into the vacuum chamber from the discharge chamber, and enter the back of the anode of the cylindrical shield body according to the trajectory of the electron beam. The part facing the inside of the opening is made of heat-resistant shielding material, the other part is made of ion-sputtering material, the former part is formed separately from the latter part, and it is detachably attached to the latter part. A plasma generator characterized by the above. A discharge chamber, a cathode disposed in the discharge chamber, and an end portion of the discharge chamber are provided to be electrically insulated from the discharge chamber, and the discharge chamber is opened to an external vacuum vessel at the center thereof A ring-shaped anode having an opening, a cylindrical shield body mounted in the discharge chamber so as to surround a cathode facing surface of the anode including at least an inner surface of the opening of the anode with respect to the cathode, and the cathode And a discharge power source for applying a discharge voltage between the anode and the anode, and means for supplying a discharge gas into the discharge chamber. Electrons in the plasma formed in the discharge chamber are transferred to the anode. The inside of the opening is configured to irradiate the vacuum vessel through the inside of the cylindrical shield body surrounding the cathode, and in the plasma formed in the vacuum vessel On is captured by the magnetic field formed by the electron beam itself drawn into the vacuum chamber from the discharge chamber, and is opposed to the inside of the opening of the anode of the cylindrical shield body that enters backward according to the trajectory of the electron beam. The plasma generator is equipped with a part made of heat-resistant shielding material, the other part made of ion-sputtering-resistant material, the former part is formed separately from the latter part, and detachably attached to the latter part. A thin film forming apparatus in which ions in plasma generated by irradiating electrons from the plasma generating apparatus to a vapor deposition material in a vaporized state in the vacuum container are attached to a substrate .

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