JP3398639B2 - Electron beam excited plasma generator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an electron beam excited plasma generator, and more particularly to a structure adapted to reduce contamination of an electrode material during a plasma process.

[0002]

2. Description of the Related Art An electron beam excited plasma apparatus is a process gas in which an accelerated electron beam is drawn from a discharge plasma through a bottleneck by applying an accelerating voltage by converting an inert gas such as argon into a plasma by a discharge current. It is used for plasma processing, that is, plasma ion plating, plasma CVD, plasma sputtering, plasma etching, etc.

In plasma processing, it is important to use high-purity reaction plasma, but in the conventional electron beam excitation plasma apparatus, electrode materials may be mixed in the reaction plasma, and it is easy to obtain a good quality product. It wasn't. Contamination of reaction plasma is caused by charged particles in the discharge plasma or reaction plasma colliding with the inner wall of the container with energy exceeding the sputtering yield of the substance forming the wall, and the substance particles jump out of the wall and enter the plasma. Occurs. The entire discharge plasma has a substantially constant plasma potential, and the energy with which the ions in the discharge plasma collide with the wall is determined by the difference between this plasma potential and the wall potential.

Japanese Patent Application Laid-Open No. 11-79 filed by the applicant of the present application
No. 00 discloses an electron beam excitation plasma device in which contamination is suppressed by electrically insulating the extraction bottleneck from other electrodes. However, the disclosed device could not suppress sputtering at the discharge electrode. In particular, in the case where the discharge part has a structure adjacent to the process chamber such as a pressure gradient type electron beam excitation plasma device, contamination by sputtering has been a serious problem. If the energy of the charged particles does not exceed the sputtering yield of the electrode material, the material particles are less likely to jump out. Therefore, if the electrode is made of molybdenum or ceramic having a high sputtering yield, contamination can be suppressed. However, the method of forming an electrode with a substance having a high sputtering yield has problems that the material is limited, it is difficult to work, and the raw material is expensive.

Contamination can be suppressed by measuring the plasma potential in the discharge region, evaluating the potential difference between each electrode and the wall surface, and controlling the discharge conditions based on this. The plasma potential can be measured by, for example, a Langmuir probe. The Langmuir probe measures the plasma potential from the inflection point of the current flowing through the probe when it is inserted into the discharge region and a sweep voltage is applied to the probe. Such a plasma electrometer is not only costly and time-consuming to measure, but also cannot be measured during the process and cannot be used for feedback control.

[0006]

Therefore, the problem to be solved by the present invention is, in an electron beam excitation plasma apparatus equipped with a cathode, an intermediate electrode, a discharge electrode and a process chamber, an electrode, etc. based on an index that can be easily measured. It is to provide a mechanism capable of suppressing the plasma from being contaminated by the substance emitted from the inner wall portion of the container.

[0007]

In order to solve the above problems, the first electron beam excited plasma generator of the present invention is
It is characterized by comprising a controller for measuring the potential of the intermediate electrode with the discharge electrode as a reference so that the potential of the intermediate electrode falls within a predetermined range. The intermediate electrode can be operated so that the potential of the intermediate electrode is +6 V or less, and more preferably -4 V or less.

Further, in order to solve the above-mentioned problems, the second electron beam excitation plasma generator of the present invention measures the electric potential of the short tube interposed between the intermediate electrode and the discharge electrode with reference to the discharge electrode, It is characterized by comprising a controller for controlling the electric potential of the short pipe portion to fall within a predetermined range. In addition, it is preferable to operate so that the short-tube potential is +26 V or less, and further +16 V or less. In addition, the controller adjusts one or more of the discharge current, the flow rate of the inert gas, the acceleration voltage, the process chamber gas pressure, and the cathode heating current to control the intermediate electrode potential or the short tube potential. You can

The inventors of the present invention have closely observed the process behavior when the plasma generation conditions such as the discharge potential, the inert gas flow rate and the process gas pressure are changed, and as a result, the intermediate electrode potential and the intermediate electrode and the discharge electrode are observed. It was discovered that the electric potential of the short tube interposed between the electric field and the discharge electrode sputtered energy corresponded well. The intermediate electrode potential and the potential of the inter-electrode short tube can be easily measured during operation using a normal voltmeter without using a special device such as a Langmuir probe. Therefore, if these potentials are used instead of directly using the discharge electrode sputter energy as a control variable, feedback control can be easily configured and the discharge electrode sputter energy can always be adjusted to an appropriate value. If the discharge electrode sputtering energy is maintained at a value lower than the sputtering yield of the substance forming the electrode by using the electron beam excited plasma generator of the present invention, it is possible to suppress the mixture of substances from the electrode and to obtain a good quality reaction. It is possible to obtain a plasma.

According to the research conducted by the inventors, the intermediate electrode potential corresponding to the sputtering yield range of 20 eV to 30 eV of commonly used metals such as stainless steel is −4 V to +6 V, and the intermediate electrode and the discharge electrode have the same potential. It was found that the electric potential of the mounted short tube was + 16V to + 26V. Therefore, the effect of suppressing contamination can be obtained by operating so that the intermediate electrode potential is +6 V or less or the short tube potential is +26 V or less, and the intermediate electrode potential is -4 V or less or the short tube potential is +1.
Contamination becomes extremely small when operated so as to be 6 V or less. Note that not only the cathode heating current, discharge current, and accelerating voltage, but also the flow rate of the inert gas and the pressure of the process gas can be used to easily change the potential of the intermediate electrode or the short tube. It can be used as a variable.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an electron beam excited plasma generator according to the present invention will be described below in detail with reference to FIGS. FIG. 1 is a configuration diagram illustrating an embodiment in which the present invention is applied to a differential exhaust type electron beam excitation plasma device.

Referring to FIG. 1, the electron beam excited plasma generator comprises a plasma region 1, an electron acceleration region 2 and a plasma process region 3. Plasma region 1 is cathode 11
And an intermediate electrode 12 and a discharge electrode 13, and a gas nozzle 14 for supplying an inert gas such as argon gas. The electron acceleration region 2 is a portion sandwiched between the discharge electrode 13 and the acceleration electrode 21, and has an exhaust port 22. The plasma process region 3 is a portion surrounded by the process chamber 31, has a gas nozzle 32 for supplying a reaction gas and an exhaust port 33, and has an object to be treated 35.
The sample table 34 is mounted.

A heating power source 41 for supplying a heating current is connected to the cathode 11. Further, a discharge power supply 42 is provided between the cathode 11 and the discharge electrode 13. The discharge power supply 42 has a cathode terminal connected to the cathode 11 and an anode terminal connected to the discharge electrode 13. The intermediate electrode 12 is connected to the discharge electrode 13 via a resistor and a switch. An acceleration power source 43 is provided between the discharge electrode 13 and the acceleration electrode 21, and its cathode terminal is connected to the discharge electrode 13 and its anode terminal is connected to the acceleration electrode 21. The wall of the process chamber 31 is grounded, and an RF power source 47 is provided between the ground terminal and the sample stage 34 via a matching unit 48.

The inert gas as the plasma species is supplied to the plasma region 1 via the flow rate controller 54. When the current from the heating power source 41 flows to the cathode 11, thermoelectrons are emitted to the surroundings, and when the voltage of the discharging power source 42 is applied to the discharge electrode 13, the cathode 11 and the cathode 11 are discharged through the initial discharge generated between the intermediate electrodes 12. A discharge is generated between the electrodes 13. Due to this discharge, the inert gas is turned into plasma and fills the plasma region 1. After the discharge plasma is stably formed, the intermediate electrode 12 is switched off and disconnected from the discharge electrode 13 to be in a floating potential state. When the voltage of the acceleration power supply 43 is applied between the discharge electrode 13 and the acceleration electrode 21, the electron flow is extracted from the discharge plasma in the plasma region 1 to the electron acceleration region 2 and accelerated to speed up to reach the plasma process region 3. To do.

The high-speed electron beam ionizes and dissociates the gas molecules of the reaction gas introduced into the process chamber 31 from the introduction port 32 to form plasma into a reaction gas plasma. The gas that is turned into plasma can be used for the sample table 3 depending on the purpose.
4 reacts with the sample 35 mounted on 4 to form a product. An appropriate RF bias is applied to the sample table 34 to control the ion irradiation energy on the sample surface. The reaction gas is supplied from a gas supply port 32 provided in the process chamber 31 via a flow rate controller (not shown), and is exhausted from an exhaust port 33 provided with an exhaust conductance valve 53 for adjusting the pressure in the process chamber. The sample table 34 in the process chamber 3 has a structure in which a sample 35 can be placed and rotated or moved vertically.

An exhaust port 22 is provided in the electron acceleration region 2, and the inert gas in the plasma region 1 and the reaction gas in the plasma process region 3 are vacuum-exhausted together, so that the pressure gradient in the system is appropriately adjusted. Hold on. Further, the plasma region 1 is separated by an intermediate electrode 12 into a cathode chamber and a discharge chamber, and both are configured to have an appropriate pressure state during operation. The coil 15 provided on the outer circumference of the discharge electrode 13 and the coil 23 provided on the outer circumference of the acceleration electrode 21 adjust the magnetic field distribution in order to maintain the electron beam in a desired shape. Further, a spatter prevention plate 24 is installed on the electron acceleration region 2 side of the discharge electrode 13 to prevent the discharge electrode from being sputtered by the ions in the plasma generated in the acceleration region.

The electron beam excited plasma generator of this embodiment comprises a voltmeter 51 for measuring the voltage between the intermediate electrode 12 and the discharge electrode 13, a short tube 16 between the intermediate electrode 12 and the discharge electrode 13, and a discharge electrode. Voltmeter 52 for measuring voltage between 13
And an absolute pressure vacuum gauge 55 for measuring the gas pressure in the process chamber 3. Furthermore, a controller 56 for suppressing contamination of the process gas is provided,
The intermediate electrode potential or the short tube potential measured with the discharge electrode 13 as a reference is input, and a flow rate controller 54 that controls the argon gas flow rate, a heating power supply 41 that controls the cathode heating current, and a gap between the cathode 11 and the discharge electrode 13. The discharge power source 42 that determines the flowing discharge current, the acceleration power source 43 that determines the acceleration voltage, the exhaust valve 53 that determines the gas pressure in the process chamber, or a combination thereof is operated to operate the intermediate electrode 12 or The short tube 16 is kept at a predetermined potential. The controller 56 is an absolute pressure gauge 5.
It is possible to form a minor loop control system for controlling the process chamber pressure by inputting the measurement output of No. 5 and the exhaust valve 53, and using this as a manipulated variable.

It has been conventionally known that the contamination energy of the substance can be reduced by making the collision energy of the electrons in the plasma smaller than the sputtering yield of the substance forming the wall, but the collision energy is measured during the operation of the apparatus. There was no practical way. Therefore, as a result of earnest research, the inventors of the present invention indirectly controlled the potential of the intermediate electrode or the short tube inserted between the intermediate electrode and the discharge electrode to indirectly cause the ions in the plasma to reach the discharge electrode. It has been found that the collision energy can be adjusted. The electric potential of these parts is the normal voltmeter 51,
Since the measurement can be easily performed by using 52, it can be easily controlled even during the operation of the apparatus to prevent contamination of the process plasma.

2 to 4 are graphs showing the relationship between the plasma potential in the discharge plasma and the potential of each part. The discharge current may be changed for the purpose of changing the input current to the process chamber due to operational requirements. FIG. 2 is a graph showing the potential change of each part when the discharge current is changed. The horizontal axis is the discharge current and the vertical axis is the potential, the argon gas flow rate is 5 sccm, the acceleration voltage is 100 V, and the process chamber pressure is 1 mTorr. Is plotted for As can be seen from the figure, when the discharge current is set to 9 A, the plasma potential becomes 2
0V, that is, the collision energy of ions to the discharge electrode is 2
It becomes 0 eV. Furthermore, when the discharge current is 7.5 A, the collision energy is 30 eV, and when the discharge current is 5 A, the collision energy is 4
At 5 eV, the discharge electrode material is sputtered and jumps out of the surface, thus actively contaminating the plasma.

If the material forming the discharge electrode is stainless steel, the sputtering yield is about 20 eV.
Therefore, under this condition, if the discharge current is 9 A or less, spatter does not occur and contamination can be suppressed. When the discharge current is set to 5 A, the sputtering is remarkably generated, and a large amount of the substance released by the sputtering flows into the process chamber, which adversely affects the film forming process and the like. When the potential of the intermediate electrode and the potential of the short tube at this time are plotted, it can be seen that both change in parallel with the plasma potential.

FIG. 3 is a graph similar to FIG. 2 in which the horizontal axis represents the flow rate of argon gas, and is plotted when the discharge current is 15 A, the acceleration voltage is 100 V, and the process chamber pressure is 1 mTorr. The flow rate of argon gas may be adjusted to adjust the current flowing into the process chamber. As can be seen from the figure, under the above conditions, the argon gas flow rate is 4.0 sccm, the collision energy is 20 eV, and the scatter energy is 4.3 sccm.
It becomes 0 eV and further becomes 35 eV at 4.5 sccm.
Also in this case, the short-tube potential changes following the plasma potential, and the intermediate electrode potential also has a good tendency in the region where the argon gas flow rate is a problem.

FIG. 4 is a plot of changes in the electric potential at various places when the gas pressure in the process chamber is changed.
The discharge current is 15 A, the acceleration voltage is 100 V, and the argon gas flow rate is 5 sccm. The reaction in the process chamber can be controlled by adjusting the pressure of the process gas. However, under the above conditions, when the process gas pressure becomes 12 mTorr, the collision energy becomes 20 eV and 1
It becomes 30 eV at 6 mTorr and 42 eV at 20 mTorr. Therefore, by operating the discharge electrode made of stainless steel at 16 mTorr or less, preferably 12 mTorr or less, contamination of the process gas can be prevented.

This finding is important for suppressing contamination and ensuring a good quality reaction. However, in order to utilize such knowledge, the relationship between the discharge current, the flow rate of argon gas, the process gas pressure, and the plasma potential is obtained using other conditions as parameters, and each operation variable is set to an appropriate collision energy. It is necessary to manage each value to be controlled, and the control method becomes extremely complicated. Therefore, the inventors have found a more universal relationship from the relationships typically represented in FIGS. 2 to 4 and have made it possible to perform simple control.

FIGS. 5 and 6 are graphs in which the data points in FIGS. 2 to 4 are reedited and plotted with respect to discharge electrode sputter energy, ie, plasma potential. Figure 5
3 is a graph in which the horizontal axis represents the plasma potential, that is, the discharge electrode sputtering energy, and the vertical axis represents the intermediate electrode potential. The measurement results under different conditions were all plotted on the same line, demonstrating that the intermediate electrode potential can be used as a surrogate variable for the discharge electrode sputter energy, except for the very low energy range around 5 eV. According to this figure, no matter which variable is adjusted, the intermediate electrode potential may be set to +6 V or less in order to prevent the sputtering energy of 30 eV or less so that many materials are not subjected to sputtering. Further, it can be seen that even if stainless steel, which is often used as an electrode material, is set so that the sputter energy is suppressed to 20 eV or less so that the intermediate electrode potential is set to -4 V or less in order to prevent the spatter from being sputtered.

FIG. 6 is a graph similar to FIG. 5, in which the vertical axis represents the potential of the short tube inserted between the intermediate electrode and the discharge electrode. Comparing with the intermediate electrode potential shown in FIG. 5, it can be seen that the potential of this short tube portion more closely corresponds to the discharge electrode sputtering energy. According to this figure, if the sputter energy is to be suppressed to 30 eV or less, the short tube potential should be set to +26 V or less, and the sputter energy should be 20 eV or less.
It can be seen that the intermediate electrode potential should be set to +16 V or less to suppress the voltage to eV or less. Thus, it has been found that the discharge electrode sputtering energy can be substituted by the intermediate electrode potential or the short tube potential between the intermediate electrode and the discharge electrode. The present invention was developed by utilizing this knowledge,
Whether the discharge current, the flow rate of argon gas, or the process chamber pressure is controlled using the above potential as an index, it is possible to manage the sputtering energy and prevent the wall substance from being sputtered, thereby preventing plasma contamination. As long as the potential is used as an index, various operating variables that affect it can be selected, and the cathode heating current and the acceleration voltage that are conventionally known to affect the potential of discharge plasma can also be used. Needless to say.

FIG. 7 is a sectional view showing only the vicinity of the intermediate electrode and the discharge electrode in another mode of the electron beam excited plasma generator of this embodiment. Elements having the same functions as those of the apparatus shown in FIG. 1 are designated by the same reference numerals to simplify the description. In this embodiment, the short tube 16 between the intermediate electrode 12 and the discharge electrode 13 used in the device shown in FIG. 1 is omitted to reduce the size. When the voltage of the intermediate electrode 12 is measured by the voltmeter 51, Since the value corresponds well to the sputter energy in the same manner as the above, the discharge electrode 13 can be prevented from spattering by controlling the intermediate electrode potential to a predetermined value. It should be noted that a spatter prevention plate 24 can be provided on the downstream surface of the discharge electrode 13 to prevent ions in the plasma generated by the accelerated electron beam from spattering the discharge electrode.

FIG. 8 shows still another mode of this embodiment and is a sectional view showing only the discharge electrode portion. Elements having the same functions as those of the apparatus shown in FIG. 1 are designated by the same reference numerals to simplify the description. In this embodiment, the discharge electrode 1
The lead-out bottleneck portion of 3 can be formed of the insulating material 60. By forming the extraction bottleneck portion with an insulating material, it is possible to prevent plasma contamination due to charged particles in the process plasma sputter the extraction bottleneck portion. However, even if the extraction bottleneck is insulated, it is not possible to prevent the portion 62 of the discharge electrode 13 exposed to the outside of the extraction bottleneck from receiving sputtering.
Therefore, the discharge electrode sputtering energy is controlled by adjusting the potential of the intermediate electrode or the short tube so that the ions 61 in the discharge plasma do not attack the portion 62 of the discharge electrode 13 facing the discharge plasma, It is possible to prevent contamination of process plasma.

FIG. 9 is a configuration diagram for explaining an example in which the present invention is applied to a pressure gradient type electron beam excitation plasma device.
Elements having the same functions as those of the apparatus shown in FIG. 1 are designated by the same reference numerals to simplify the description. Referring to FIG. 9, in the electron beam excitation plasma generator, argon gas is supplied to the cathode chamber, and vacuum suction is performed in the process chamber 31 via the exhaust port 33. Due to the bottleneck existing between the intermediate electrode 12 and the discharge electrode 13, the pressure inside the apparatus gradually decreases from the cathode chamber to the process chamber 31. The acceleration electrode 21 is provided inside the process chamber 31. Also in the electron beam excitation plasma apparatus configured as described above, the voltmeter 51
The potential of the intermediate electrode 12 measured in step 1 corresponds well with the discharge electrode sputtering energy. Therefore, by adjusting the manipulated variable so as to maintain the potential of the intermediate electrode 12 at a predetermined value, it is possible to suppress the ions in the discharge plasma from sputtering the discharge electrode 13 and prevent the process plasma from being contaminated. be able to.

In FIG. 10, the cathode chamber, the discharge region, and the process chamber are arranged in the vertical direction, and the chamber filled with the discharge plasma is provided so as to project into the process chamber, and the accelerated electron flow drawn out from the extraction bottleneck is horizontal. This is an example in which the present invention is applied to an electron beam excited plasma generator in which the sample surface is arranged so as to be emitted in parallel with the accelerated electron flow. Also in FIG. 10, elements having the same functions as in FIG. 1 are assigned the same reference numerals to simplify the description. Argon gas is introduced and turned into plasma by the discharge current generated between the cathode 11 and the discharge electrode 13 to fill the plasma chamber 17 as discharge plasma. Electrons extracted from the discharge plasma by the accelerating electrode 21 pass through a bottleneck opened in the wall of the plasma chamber and the process chamber 3
It flows into 1. The extracted electron flow turns the process gas into plasma and acts on the sample 35 on the sample table 34 to produce a product.

At this time, the voltmeter 51 inserted between the intermediate electrode 12 and the discharge electrode 13 measures the potential of the intermediate electrode 12. Also in such an electron beam excitation plasma apparatus, the potential of the intermediate electrode 12 has a linear relationship with the discharge electrode sputtering energy. Therefore, the discharge electrode 13
By adjusting the potential of the intermediate electrode 12 so as not to exceed the value corresponding to the sputtering yield of the substance forming the, the sputtering to the discharge electrode 13 can be suppressed and the contamination of the process plasma can be prevented.

[0031]

As described in detail above, the electron beam excited plasma generator of the present invention automatically controls the potential of the intermediate electrode which can be easily measured or the potential of the short tube sandwiched between the intermediate electrode and the discharge electrode as an index. As a result, it is possible to easily suppress discharge electrode sputtering and prevent contamination of process plasma. Therefore,
By using the present invention, a good plasma process can be performed and a good quality product can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of an electron beam excited plasma generator of the present invention.

FIG. 2 is a graph showing the effect of discharge current in this example.

FIG. 3 is a graph showing the influence of the flow rate of argon in this example.

FIG. 4 is a graph showing the influence of process chamber gas pressure in this example.

FIG. 5 is a graph showing the relationship between discharge electrode sputtering energy and intermediate electrode potential in this example.

FIG. 6 is a graph showing the relationship between the discharge electrode sputtering energy and the potential of the short tube between the intermediate electrode and the discharge electrode in this example.

FIG. 7 is a partial cross-sectional view showing another aspect of the present embodiment.

FIG. 8 is a partial cross-sectional view showing still another aspect of the present embodiment.

FIG. 9 is a configuration diagram illustrating a state in which the present invention is applied to a pressure gradient type electron beam excitation plasma generator.

FIG. 10 is a configuration diagram illustrating a state in which the present invention is applied to another electron beam excitation plasma generator.

[Explanation of symbols]

1 plasma region 11 cathode 12 Intermediate electrode 13 Discharge electrode 14 gas nozzle 15 coils 16 short tube 17 Plasma chamber 2 electron acceleration region 21 Accelerating electrode 22 Exhaust port 23 coils 24 Spatter prevention plate 25 mounting nozzle 3 Plasma process area 31 Process room 32 gas nozzle 33 exhaust port 34 sample table 35 samples 41 Heating power supply 42 Discharge power supply 43 Power supply for acceleration 47 RF power supply 48 Matching device 51,52 Voltmeter 53 Exhaust conductance valve 54 Flow controller 55 Absolute pressure gauge 56 controller 60 insulation 61 ion 62 Area facing discharge plasma

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ identification code FI H01J 37/08 H01J 37/08 H01L 21/3065 H01L 21/302 B (58) Fields investigated (Int.Cl. ⁷ , DB name) ) H01J 27/00-27/26 H01J 37/08 H05H 1/46

Claims (7)

(57) [Claims] 1. A cathode, an intermediate electrode, a discharge electrode, and a process chamber, wherein an inert gas is supplied to the cathode portion to generate discharge plasma by discharge between the cathode and the discharge electrode, and electrons are extracted from the discharge plasma. In an electron beam excitation plasma apparatus that accelerates the gas into the process chamber and introduces the gas into the process chamber into plasma to act on the sample surface, the potential of the intermediate electrode is measured with the discharge electrode as a reference, and the potential of the intermediate electrode is measured. 2. An electron beam excitation plasma apparatus, comprising a controller for controlling the temperature of the electron beam within a predetermined range. 2. The electron beam excited plasma generator according to claim 1, wherein the intermediate electrode is operated so that the potential of the intermediate electrode becomes +6 V or less. 3. The electron beam excited plasma generator according to claim 1, wherein the intermediate electrode is operated so that the potential of the intermediate electrode is −4 V or less. 4. A cathode, an intermediate electrode, a discharge electrode, and a process chamber are provided, and an inert gas is supplied to the cathode portion to generate discharge plasma by discharge between the cathode and the discharge electrode, and electrons are extracted from the discharge plasma. In an electron beam excitation plasma apparatus that accelerates and introduces gas into the process chamber to plasmaize the gas in the process chamber to act on the sample surface, the discharge electrode is connected to a short tube interposed between the intermediate electrode and the discharge electrode. An electron beam excitation plasma generator comprising a controller that measures a reference potential and adjusts the short tube potential to fall within a predetermined range. 5. The electron beam excited plasma generator according to claim 4, wherein the short tube potential is operated to be +26 V or less. 6. The electron beam excited plasma generator according to claim 4, wherein the intermediate electrode is operated so that the potential of the intermediate electrode becomes +16 V or less. 7. The controller according to claim 1, wherein the controller regulates one or more of a discharge current, an inert gas flow rate, an acceleration voltage, a process chamber gas pressure, and a cathode heating current. An electron beam excited plasma generator according to.