JP4774140B2 - Method and apparatus for analyzing energy of high-speed neutral particles incident on high-frequency power application electrode - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a method and apparatus for analyzing the energy of high-speed neutral particles incident on a high-frequency application electrode such as an etching process apparatus.
[0002]
[Prior art]
Conventionally, in an etching process apparatus in which plasma is formed by microwaves or high frequency discharge, a high frequency application electrode is provided in a vacuum chamber, a substrate is placed on the high frequency application electrode, and a material on the substrate is processed, the plasma to the substrate The present applicant has previously proposed a method and apparatus for analyzing the energy and mass of negative ions incident on the light source (see Japanese Patent Laid-Open No. 10-199473). That is, negative charged particles incident on the high frequency application electrode are extracted through an opening provided in the high frequency application electrode, and a vertical magnetic field is applied using a magnetic circuit closed in a direction perpendicular to the inflow direction of the extracted negative charged particles. Thus, electrons are removed from the negatively charged particles, and only negative ions are extracted and analyzed.
[0003]
Further, in this type of etching process apparatus, the present applicant has also proposed a method and apparatus for analyzing the energy and mass of positive and negative ions and neutral particles incident on the substrate from plasma (Japanese Patent Laid-Open No. 11-250854). See the official gazette). That is, the ions incident on the high-frequency application electrode are passed through a deflection ion energy analyzer and a mass analyzer with the potential of the high-frequency application electrode as a reference potential. After the particles have been ionized, they are configured to be analyzed through a deflected ion energy analyzer and a mass analyzer.
[0004]
Regarding the measurement of neutral particles, neutral particle species can be identified and separated by a mass analyzer by the previously proposed method disclosed in JP-A-11-250854, but neutral (several hundred eV) is neutral. The ionization efficiency of the particles was considerably low, so when passed through a mass analyzer, the signal was quite small and could not be detected. That is, the flux amount of high-speed neutral particles depends on the pressure, but it is about 10 ¹⁶ cm ² s, which is almost the same as the ion current density under normal etching conditions (pressure 20 mTorr, plasma density 1 × 10 ¹¹ cm ^-3 ). ^{About -1} . The amount of flux that passes through the orifice diameter of 0.05 cm is further reduced by three orders of magnitude, and the ionization efficiency by electrons is low, so the final detected current value is in the region of nA (10 ^-9 A). In normal measurement as a reference, it cannot be detected because it is buried in high-frequency noise.
[0005]
Further, in the conventional energy analyzer, the reference potential of the detection unit is fixed independently of the particle energy. The quantum efficiency of the detector depends on energy. Therefore, unless the quantum efficiency of the detection unit is always kept constant, the sensitivity varies depending on the energy.
[0006]
Furthermore, when using a deflection type energy analyzer and a mass analyzer as disclosed in Japanese Patent Application Laid-Open No. 11-250854, the lens system is controlled to guide ionized neutral particles to their inlets. Necessary and complicated from a structural point of view.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described problems of the prior art, and to provide a substrate incident high-speed neutral particle analysis method and analysis apparatus that do not have high-frequency noise and have no energy dependency.
[0008]
[Means for Solving the Problems]
To achieve the above object, according to the first aspect of the present invention, a high-frequency substrate electrode provided in a vacuum chamber to form a plasma by microwaves or high frequency discharge, placing the substrate on the high frequency substrate electrode in the process apparatus for performing processing on the material on the substrate and location,
The charged particles are removed from the particles incident through the orifice provided in the high-frequency substrate electrode by a deflecting plate,
The charged particles are removed from the ionization chamber, and only high-speed neutral particles are ionized by electron impact.
Analyzing the energy of ionized high-speed neutral particles with an energy analyzer connected to a controllable power source,
Wherein with greater energy than analyzing the potential of the ions was analyzed by energy analysis portion guides only ions, the first electrode and the ion detector comprising a secondary electron multiplier tube connected to a controllable separate power source, the as the potential difference in the first electrode of the the blocking potential energy analysis electrodes of the energy analyzer ion detector is always constant, connected to said controllable power source and the ion detector is connected to the energy analysis portion another supply possible the control and is characterized in that controlled by an external analysis control unit.
[0009]
Good Mashiku the detection signal detected by the detection unit is transmitted through an optical fiber or infrared transmission means to the outside of the analysis control unit, the energy distribution can be calculated.
In the method of the present invention, a secondary electron multiplier is used for the detection unit.
[0010]
Further, according to the second aspect of the present invention, a high-frequency substrate electrode provided in a vacuum chamber to form a plasma by microwaves or high frequency discharge, on the substrate by placing the substrate on the high frequency substrate electrode In process equipment that processes materials,
And deflecting means for removing charged particles from particles incident through an orifice provided in the high frequency substrate electrode,
Ionization means for ionizing only high-speed neutral particles;
A blocking potential type energy analyzer that is connected to a controllable power source and analyzes the energy of ionized fast neutral particles;
An ion detector comprising a first electrode connected to another controllable power source and a secondary electron multiplier, and detecting the analyzed ions;
With greater energy than analyzing the potential of the ions was analyzed by the energy analysis portion, ions alone, in the ion detection unit consisting of the first electrode and the secondary electron multiplier tube connected to another power source capable of the controlled guided, such that a potential difference is always constant in the first electrode of the blocking potential energy analytical electrode of the blocking voltage-gated energy analysis portion wherein the ion detecting unit, the controllable connected to the blocking potential energy analyzer It is characterized by having a power supply and an external analysis control means for generating a control signal for controlling the different power possible the control connected to the ion detector.
[0011]
Et al of an external analysis control means transmission means or infrared transmission means and frequency comprised from the optical fiber - can be configured to via a voltage converter receiving a detection signal from the ion detector.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 schematically shows a high-speed neutral particle energy analyzer according to an embodiment of the present invention. In the drawing, reference numeral 1 denotes a substrate electrode which is disposed in a plasma chamber (not shown) and to which high frequency power is applied, and has an orifice 1a through which particles generated in the plasma pass. Two deflection electrodes 2 are arranged coaxially with the orifice 1a, and the deflection electrode 2a adjacent to the orifice 1a of the two deflection electrodes 2 is connected to the power sources 3 and 4 of 500V and -500V in the illustrated embodiment. It is connected. The deflection electrode 2 serves to remove charged particles that have entered through the orifice 1a in the substrate electrode 1.
[0013]
An ionization chamber 5 that ionizes only high-speed neutral particles by electron bombardment is disposed behind the two deflection electrodes 2, and the ionization chamber 5 is connected to an 8 V power source 6 in the illustrated embodiment. The ionization chamber 5 includes a filament 7, and the filament 7 is connected to a power source 8.
[0014]
A blocking potential type energy analysis electrode 9 for analyzing the energy of the ionized high-speed neutral particles is provided at the subsequent stage of the ionization chamber 5, and this blocking potential type energy analysis electrode 9 can be controlled as will be described later. Connected to a power source 10. A first electrode 12 of the ion detector 11 is disposed adjacent to the blocking potential type energy analysis electrode 9, and the first electrode 12 is connected to a controllable power source 13. A controllable power source 13 for the first electrode 12 of the ion detector 11 is provided to control a potential difference between the blocking potential type energy analysis electrode 9 and the first electrode 12 of the ion detector 11. The ion detector 11 includes a secondary electron multiplier 14, which is covered with a cover 15 and connected to the current detection means 16.
[0015]
The detection signal obtained by the current detection means 16 is transmitted to an external analysis control means 19 which can be constituted by, for example, a suitable computer system via a frequency-voltage converter 17 and an optical fiber 18, and the detected current value is differentiated by energy. By doing so, an energy distribution is obtained. The external analysis control means 19 generates control signals for the controllable power supply 10 of the blocking potential type energy analysis electrode 9 and the controllable power supply 13 of the first electrode 12 of the ion detector 11, and this control signal In order to make the energy of ions incident on the secondary electron multiplier 14 constant, both power sources are used so that the potential difference between the blocking potential energy analysis electrode 9 and the first electrode 12 of the ion detector 11 is always constant. To control.
In this embodiment, an appropriate infrared transmission means can be used instead of the optical fiber 18.
[0016]
FIG. 2 shows the potential applied to each electrode during analysis. High-speed neutral particles generated by charge exchange in the plasma sheath have energy of several hundred eV and pass through the orifice 1a of the substrate electrode 1 together with ions and electrons and enter the analyzer. Ions and electrons that have entered along with the high-speed neutral particles are removed at the deflection electrode 2, and only the high-speed neutral particles enter the ionization chamber 5 and are ionized by electron impact. At this time, the energy of the ionized high-speed neutral particles becomes the initial energy + the potential of the ionization chamber 5 (8 V in the illustrated embodiment) and enters the blocking potential type energy analysis electrode 9. In the blocking potential type energy analysis electrode 9, only ions having energy larger than the analysis potential can pass. Passed ions are amplified by the secondary electron multiplier 14 and detected by the current detection means 16. The detected current value is transmitted to the external analysis control means 19 via the frequency-voltage converter 17 and the optical fiber 18, and is processed so as to obtain an energy distribution by differentiating the current value with energy.
[0017]
When the energy of ions incident on the secondary electron multiplier 14 changes, the quantum efficiency of the secondary electron multiplier 14 changes, so that it is necessary to make it incident with a constant energy. Therefore, as described above, the control signal from the external analysis control means 19 makes these potential differences between the blocking potential type energy analysis electrode 9 and the first electrode 12 of the ion detector 11 always constant. The power supply is controlled.
[0018]
3 and 4 show the energy distribution of fast neutrons measured using the analyzer shown in FIG. 1. The etching conditions are Ar 25 sccm, O ₂ 3.5 sccm mixed gas, pressure 28 mTorr, about 1 × 10 ¹⁰ cm ^{−. 3} plasma density.
The measurement example of FIG. 3 is a case where the high frequency bias power is 140 W, and the measurement example of FIG. 4 is a case where the high frequency bias power is 310 W.
[0019]
【The invention's effect】
As described above, according to the analysis method of the present invention, the charged particles are removed from the particles incident through the orifice provided in the high-frequency substrate electrode by the deflecting plate, and only the high-speed neutral particles are ionized. Since the energy of the neutral particle is analyzed by the energy analyzer, the energy of the analyzed ion and the potential of the detector are controlled so that the energy of the analyzed ions is always kept constant and incident on the detector. In addition, there is no energy dependency of the detection unit, and high-speed neutral particle energy analysis becomes possible.
Further, in the analysis method of the present invention, the detection signal detected by the detection unit is transmitted to an external analysis control unit via an optical fiber or an infrared transmission unit, and the energy distribution is calculated. The influence can be eliminated, so that the energy analysis of high-speed neutral particles can be performed accurately and easily.
[0020]
According to the analysis apparatus of the present invention, the deflection means for removing charged particles from the particles incident through the orifice provided in the high-frequency substrate electrode, the ionization means for ionizing only the high-speed neutral particles, and the energy of the ionized high-speed neutral particles The energy of the ions analyzed by the blocking potential energy analyzer is controlled by controlling the potential difference between the blocking potential energy analyzer, the detected ion detector, and the blocking potential energy analyzer and the ion detector. Because it is configured with a potential difference control means that always makes it constant and incident on the detection unit, it does not depend on the energy of the detection unit and enables high-speed neutral particle energy analysis. In comparison, the lens system and its control system are not required, and the analyzer can be configured relatively easily.
In addition, since the measuring device is arranged below the substrate electrode to which high-frequency power is applied, in the case of ground potential reference, a high-frequency electric field exists between the measuring device and becomes a noise source. Alternatively, an external analysis control unit connected via an infrared transmission unit is provided, and the analysis control unit receives a detection signal from the ion detection unit via a transmission unit comprising an optical fiber or an infrared transmission unit and a frequency-voltage converter. In this case, the power supply of the energy analyzer and the signal line are superimposed on the high frequency power supply, and exchange of signals with the outside can be performed through an optical fiber or infrared transmission means, so that the electrode potential can be set as the reference potential. The high frequency electric field is not generated between the electrode and the energy analyzer, and measurement can be performed without creating a noise source.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing one embodiment of the present invention.
FIG. 2 is a diagram showing the potential of each part of the analyzer shown in FIG.
FIG. 3 is a graph showing the energy distribution of high-speed neutral particles measured using the analyzer of FIG.
4 is a graph showing the energy distribution of high-speed neutral particles when a high-frequency bias power different from that in FIG. 3 is applied using the analyzer of FIG.
[Explanation of symbols]
1: substrate electrode 1a: orifice 2: deflection electrode 5: ionization chamber 7: filament 9: blocking potential type energy analysis electrode 10: controllable power source 11: ion detector 12: first electrode 13 of the ion detector 11: Controllable power supply 14 of the first electrode 12: secondary electron multiplier 16: current detection means 17: frequency-voltage converter 18: optical fiber 19: external analysis control means

Claims (5)

In the process apparatus where the high-frequency substrate electrode is provided and the substrate is placed on the high frequency substrate electrode subjected to processing in the material on the substrate in a vacuum chamber to form a plasma by microwaves or high-frequency discharge,
The charged particles are removed from the particles incident through the orifice provided in the high-frequency substrate electrode by a deflecting plate,
The charged particles are removed from the ionization chamber, and only high-speed neutral particles are ionized by electron impact.
Analyzing the energy of ionized high-speed neutral particles with an energy analyzer connected to a controllable power source,
Wherein with greater energy than analyzing the potential of the ions was analyzed by energy analysis portion guides only ions, the first electrode and the ion detector comprising a secondary electron multiplier tube connected to a controllable separate power source, the as the potential difference in the first electrode of the the blocking potential energy analysis electrodes of the energy analyzer ion detector is always constant, connected to said controllable power source and the ion detector is connected to the energy analysis portion The method for analyzing energy of high-speed neutral particles, wherein the controllable power source is controlled by an external analysis control means. 2. The energy analysis method for high-speed neutral particles according to claim 1, wherein a detection signal detected by the ion detector is transmitted to the external analysis control means via an optical fiber to calculate an energy distribution. . The detection signal detected by the ion detecting unit transmits to the outside of the analysis control unit via an infrared transmission unit, the high-speed neutral particles according to claim 1, characterized in that to calculate the energy distribution energy Analysis method. In the process apparatus where the high-frequency substrate electrode is provided and the substrate is placed on the high frequency substrate electrode subjected to processing in the material on the substrate in a vacuum chamber to form a plasma by microwaves or high-frequency discharge,
And deflecting means for removing charged particles from particles incident through an orifice provided in the high frequency substrate electrode,
Ionization means for ionizing only high-speed neutral particles;
A blocking potential type energy analyzer that is connected to a controllable power source and analyzes the energy of ionized fast neutral particles;
An ion detector comprising a first electrode connected to another controllable power source and a secondary electron multiplier, and detecting the analyzed ions;
With greater energy than analyzing the potential of the ions was analyzed by the energy analysis portion, ions alone, in the ion detection unit consisting of the first electrode and the secondary electron multiplier tube connected to another power source capable of the controlled guided, such that a potential difference is always constant in the first electrode of the blocking potential energy analytical electrode of the blocking voltage-gated energy analysis portion wherein the ion detecting unit, the controllable connected to the blocking potential energy analyzer energy analyzer of the high-speed neutral particles characterized by having a power supply and an external analysis control means for generating a control signal for controlling the different power possible the control connected to the ion detector. According to claim 4, characterized in that it is configured via the voltage converter receiving the detected signal from the ion detector - the external analysis control unit transmitting means or infrared transmission means and frequency comprised from the optical fiber High-speed neutral particle energy analyzer.

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