JPH11250854A - Analyzing method and device for incident ion on substrate in etching plasma - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable measurement and mass spectrometry of energy distribution of positive and negative ions and neutral particles incident on a substrate in plasma etching. SOLUTION: Ions outgoing from an orifice of a substrate electrode 24 are introduced to a deflection ion energy analyzer 33 to be analyzed by the deflection energy analyzer 33 to eliminate dependency of sensitivity on energy, and energy distribution of incident ions on the substrate is measured and mass spectro-analyzed by the deflection ion energy analyzer 33 taking a potential of the substrate electrode 24 for reference potential and a mass spectrograph 34. For neutral particles, the neutral particles are ionized, and energy distribution of the neutral particles incident on the substrate is measured and mass spectro-analyzed by the deflection ion energy analyzer 33 taking the potential of the substrate electrode 24 for the reference potential and the mass spectrograph 34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching apparatus for etching a substance on a semiconductor, an electronic component, or another substrate by utilizing plasma, wherein energy of positive and negative ions and neutral particles incident on the substrate from the plasma is obtained. And a method and apparatus for analyzing mass.

[0002]

2. Description of the Related Art In order to know the energy of ions incident on a substrate placed on a substrate electrode to which high-frequency power is applied, the kinetic energy of ions exiting from an orifice provided on the substrate electrode is placed behind the substrate electrode. It is known to measure with an ion energy analyzer. At this time, if the reference potential of the ion energy analyzer is a normal DC potential, a kinetic energy of the ions is changed because a time-varying electric field is generated between the substrate electrode and the potential at a high frequency. Energy cannot be measured correctly. So ADKuypers and HJHopman (J.Appl.Phy
s., 63, 1894 (1988)) proposed and implemented a measurement method in which the reference potential of an ion energy analyzer was used as the potential of a substrate electrode.
As a result, the oscillating electric field between the substrate electrode and the ion energy analyzer disappeared, and the energy could be measured correctly, but mass analysis remained impossible.

Accordingly, the present inventors have previously described Japanese Patent Application No. 8-77159.
We proposed and implemented a method to adjust the reference potential of the mass spectrometer to the potential of the substrate electrode. The structure of the analyzer is shown in FIG. 6 of the accompanying drawings. In FIG. 6, reference numeral 1 denotes a plasma generation chamber, and a plasma generation electrode 2 is provided in the plasma generation chamber 1.
The electrode 2 for plasma generation is connected to a high-frequency power supply 4 via a matching box 3. A substrate electrode 5 is attached to the plasma generation chamber 1 via an insulator 6 so as to face the plasma generation electrode 2 in the plasma generation chamber 1. The substrate electrode 5 has an opening for ion attraction at a position in contact with plasma generated in the plasma generation chamber 1.
5a, and is connected to a high frequency power source 9 for bias via a capacitor 7 and a matching box 8. An energy analyzer 10 is disposed in the substrate electrode 5. The energy analyzer 10 includes a mesh electrode 10a for cutting ions having an energy lower than an ion energy level to be detected, an outer cylinder electrode 10b, and an inner cylinder electrode 10c. Each of these electrodes is connected to an ion energy control power supply 11. Reference numeral 12 denotes a quadrupole mass spectrometer, and each electrode is connected to a control power source 13 for mass spectrometry.
Reference numeral 14 denotes an ion detector, which is inserted into the vacuum vessel 15 together with the mass analyzer 12. The vacuum vessel 15 is connected to the open end of the substrate electrode 5 via an insulator 16. In FIG. 6, reference numeral 17 denotes a photocoupler, reference numeral 18 denotes an optical fiber, reference numeral 19 denotes a measurement circuit, and reference numeral 20 denotes a sweep power supply, which are connected as shown.

In this structure, all analyzers and control power supplies, such as an ion energy analyzer 10, an ion energy control power supply 11, a mass analyzer 12, and a control power supply 13 for mass analysis, are connected to the substrate electrode 5, and are connected to the ground electrode. Floating potential.
Therefore, the energy analyzer 10 passes through the small hole of the substrate electrode 5.
The ions entering the substrate electrode 5 and the energy analyzer 10
Since they have the same potential, energy analysis is performed without receiving any perturbation, and the high-frequency component of the reference potential of the energy analyzer 10 and the mass analyzer 12 is made equal to the high-frequency component of the substrate electrode potential. Thus, the energy and mass of ions incident on the substrate electrode 5 to which the high-frequency power is applied can be correctly analyzed.

[0005]

Since the ion energy analyzer used in the analyzer shown in FIG. 6 proposed above is of the coaxial type, the sensitivity depends on the energy and the energy distribution cannot be obtained correctly. Although the angle of the ion velocity at the orifice spreads with a certain distribution, the coaxial type picks up only a part of it, and furthermore, the angular range and energy range of the velocity of the ion at the orifice that can pass through the energy analyzer. Changes depending on the value of the energy, the sensitivity to the ion current changes depending on the energy. Therefore, the energy value can be obtained correctly, but the relative value of the ion current at each energy value is not correct, so that a correct energy distribution cannot be obtained.
The measured ion current value is proportional to the value integrated over the range of angles that can pass through the angle distribution at the orifice, but the angle distribution due to the plasma state and the angle range specific to the analyzer depend on energy independently of each other. And change,
Energy dependence occurs in sensitivity to ion current.

In a measuring method in which the reference potential of the ion energy analyzer and the mass analyzer is used as the potential of the substrate electrode, a correct energy distribution cannot be obtained unless an ion energy analyzer whose sensitivity does not depend on energy is used. Therefore, an object of the present invention is to provide a method and an apparatus that enable measurement of energy distribution of positive and negative ions and neutral particles incident on a substrate in etching plasma and mass spectrometry.

[0007]

In order to achieve the above-mentioned object, the present invention provides a method for controlling the potential applied to a plurality of electrodes constituting a lens system to analyze ions emitted from an orifice of a substrate electrode by ion energy analysis. Eliminating the energy dependence of sensitivity by leading to the instrument inlet and analyzing with a deflected ion energy analyzer, by setting the reference potential of the lens system, deflected ion energy analyzer and mass analyzer to the potential of the substrate electrode It enables measurement of the energy distribution of positive and negative ions incident on the substrate and mass spectrometry. As for neutral particles, the neutral particles are ionized, and thereafter, measurement of the energy distribution of the neutral particles incident on the substrate and mass analysis can be performed by the above-described method.
With respect to negative ions, the potential distribution applied to the electrode in the case of the above-described positive ions is inverted, so that the energy distribution of the negative ions incident on the substrate can be measured and mass analysis can be performed.

[0008]

[0009]

In the case of a coaxial type energy analyzer, a method of calibrating the energy dependence of sensitivity in advance and correcting the measurement result later can be considered, but this is extremely difficult for the following reasons. That is, since the ion current value measured by passing through the coaxial energy analyzer depends on the angular distribution of the ion velocity at the orifice, the calibration must reproduce the angular distribution in the actual measurement. The angular distribution of ion velocities is not only due to the velocity distribution in the original plasma, but also affected by the electric field distortion near the orifice, i.e., the ion field bends due to the electric field distortion. Can be The angle at which this trajectory is bent depends on the magnitude of the electric field distortion and the kinetic energy of the ions as they pass near the orifice, and the magnitude of the electric field distortion depends on the sheath voltage, sheath length, and orifice diameter. I do. In the case of a substrate electrode to which only DC power is applied, since there is a one-to-one correspondence between the kinetic energy value of ions passing through the vicinity of the orifice and the "sheath voltage, sheath length", the ion trajectory bends Can be reproduced at the time of calibration, but in the case of a substrate electrode to which high-frequency power is applied, since the sheath voltage and the sheath length change over time, there is no one-to-one correspondence as described above. , And furthermore, kinetic energy value and "sheath voltage, sheath length"
It is realistic to accurately reproduce all the angular distributions of ion velocities at the orifice during actual measurements made under various plasma conditions during calibration, since the relationship between Is impossible. Therefore, it is impossible to calibrate a coaxial energy analyzer and obtain a correct energy distribution.

According to the method of the present invention, since the sensitivity of the ion energy analyzer does not depend on energy, the energy distribution of positive and negative ions and neutral particles can be measured.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. First, the principle of the energy distribution measurement will be described. FIG. 2 shows the configuration of an analyzer relating to ions according to the present invention. A plasma generation electrode 22 is arranged in the plasma chamber 21, and the plasma generation electrode 22 is connected to a high frequency power supply 23. A substrate electrode 24 is provided in the plasma chamber 21 so as to face the plasma generation electrode 22.
Is attached via an insulator 25. Board electrode 24
Has an orifice 24a and is connected to a high frequency power supply 27 via a capacitor 26. A lens system 28 is arranged in the substrate electrode 24, and the lens system 28 is composed of a plurality of electrodes. The substrate electrode 24 is a vacuum container via an insulator 29
The vacuum container 30 is hermetically coupled to the differential evacuation system 32 via an insulator 31. In the vacuum vessel 30,
On the exit side of the lens system 28, a deflection type ion energy analyzer 33, a quadrupole mass analyzer 34, and an ion detector 35, which are composed of two opposed spherical electrodes, are sequentially arranged. The distal end of the vacuum vessel 30 is closed as indicated by reference numeral 36.
Each electrode of the lens system 28 and two electrodes of the deflection ion energy analyzer 33 are connected to an energy analysis controller 37, and each electrode of the quadrupole mass analyzer 34 is connected to a mass analyzer.
Connected to 38. In FIG. 2, reference numeral 39 denotes an ion current detector connected to the ion detector 35, 40 denotes a computer, 41 denotes a frequency / voltage converter, 42 denotes an optical fiber, 43 denotes a frequency / voltage converter, and 44 denotes a sweep voltage source. Yes, and connected as shown.

Ions emitted from the orifice 24a provided on the substrate electrode 24 are deflected by a lens system 28 comprising a plurality of electrodes to which an appropriate potential is applied from a sweep voltage source 44 via an energy analysis controller 37. It is led to the entrance of the energy analyzer 33. The deflection ion energy analyzer 33 has an energy analysis controller 37 for the two opposing spherical electrodes.
Different electric potentials are applied by the sweep voltage source 44 via the ion source, whereby the trajectory of the ions is bent by the action of the electric field generated between the electrodes in the deflection type ion energy analyzer 33, and passes according to the value of the potential difference between the electrodes. The kinetic energy of the ions that can be determined is determined. With the potential difference between the electrodes kept constant, the potential of the deflection ion energy analyzer 33 was changed to the substrate electrode.
The orifice 24
The kinetic energy at a is analyzed. This allows the passage of ions through the orifice 24a.

Thereafter, mass separation is performed by a quadrupole mass analyzer 34, and an ion current detector is used in an ion detector 35.
By 39, an ion current is detected. At this time, the lens system
28, the reference potential of the energy analyzer 33 and the mass analyzer 34 is
This is the sum of the potential of the substrate electrode 24 and the sweep voltage. The sweep voltage, the lens system 28, the energy analyzer 33 and the mass analyzer 34 are connected to a frequency-voltage converter 41,
Optical fiber 42, voltage converter 43, energy analysis controller
Controlled through 37 and mass analyzer 38. The energy distribution of the negative ions can be measured by inverting the potential of each electrode in the positive ion analysis.

FIG. 3 shows the configuration of an apparatus for measuring the energy distribution of neutral particles according to another embodiment of the present invention. 3, parts corresponding to the components in FIG. 2 are denoted by the same reference numerals. In the embodiment shown in FIG. 3, an ionization chamber 45 is provided adjacent to the entrance of the lens system 28 for ionizing neutral particles by electron impact. The ionization chamber 45 has a filament 46, and the filament 46 has a filament current. source
Connected to 47. Reference numeral 48 denotes a voltage source for electron energy. Neutral particles are ionized in an ionization chamber 45, and a deflection energy analyzer 33 and a mass analyzer 34 are provided by a lens system 28.
And the energy distribution and mass are analyzed. A charged particle removing electrode plate 49 is provided between the ionization chamber 45 and the orifice 24a of the substrate electrode 24. One electrode plate 49 is connected to an ion removing voltage source 50, and the other electrode plate 49 is connected to the substrate. It is connected to the electrode 24 and has a potential difference. Thereby, the electrode plate 49 can deflect the charged particles and remove them in advance. In this case, instead of the electrode plate 49 to be deflected, a mesh or a ring-shaped electrode with a hole in the center is placed, and a positive potential is applied to create a potential barrier for the positive ions to remove the positive ions. May be. Alternatively, it is also possible to apply a high potential to the ionization chamber 45 and thereafter, such that positive ions cannot reach the ionization chamber, while maintaining the potential relation between the ionization chamber 45, the lens system 28, and the analyzer.

[0016]

As described above, in the analysis of neutral particles, since the electric field is not sensed until ionization, only the relationship of the potential between the ionization chamber 45, the lens system 28, and the analyzer 33 after ionization is a problem. Therefore, the ionization chamber 45, the lens system 28,
It is not necessary to swing the potential of the analyzer 33 at a high frequency in accordance with the potential of the substrate electrode 24, and those reference potentials may be used as DC potentials. However, according to the present invention, by setting the reference potential to the substrate electrode potential, switching between ion energy distribution measurement and neutral particle energy distribution measurement can be performed by the charged particle removal voltage source 50 and the ionization filament current source 47. On,
It becomes possible only by turning off, and great convenience is obtained.

Next, an embodiment of the positive ion energy distribution measurement will be described with reference to FIG. FIG. 4 shows the configuration of the lens system and the deflection type energy analyzer. Lens system
28 comprises five electrodes a, b, c, d and e, and the deflection energy analyzer 33 is of a 90 degree deflection type and comprises two opposed spherical electrodes f, g and h. The potentials of the electrodes a and b of the lens system 28 are made equal to the potential of the substrate electrode 24, and the electrode e of the lens system 28 and the deflection type energy analyzer are used.
The potential of the electrode h of 33 is made equal to the sum of the potential of the substrate electrode 24 and the sweep voltage. The potential of one spherical electrode f of the deflection energy analyzer 33 is set to 2 V higher than the sum of the potential of the substrate electrode 24 and the sweep voltage, and the potential of the other spherical electrode g of the deflection energy analyzer 33 is The voltage is made 2 V lower than the sum of the potential of the substrate electrode 24 and the sweep voltage. The potentials of the electrodes c and d of the lens system 28 are set to optimal values so that the ion beam converges after passing through the energy analyzer 33 at each sweep voltage value. Two spherical electrodes f of the energy analyzer 33,
A constant positive or negative potential is given to g based on the sum of the potential of the substrate electrode 24 and the sweep voltage, and the kinetic energy of the ions when passing through the energy analyzer 33 is set. Substrate electrode
The kinetic energy of the ions at the orifice 24a is given by the sum of the sweep voltage and the kinetic energy when passing through the energy analyzer 33, and the sweep voltage sweeps the substrate electrode.
The kinetic energy of the ions at the 24 orifices 24a is analyzed. FIG. 5 shows a calculation result of the local sensitivity in the illustrated configuration example in comparison with the conventional coaxial type.

[0019]

[0020]

As described above, according to the present invention, ions coming out of the orifice of the substrate electrode are guided to the ion energy analyzer, and analyzed by the deflection type ion energy analyzer, whereby the energy dependence of the sensitivity is obtained. To eliminate
Deflection type ion energy analyzer and mass analyzer that use the potential of the substrate electrode as the reference potential are used to measure and mass analyze the energy distribution of the ions incident on the substrate. After that, the deflection ion energy analyzer and the mass analyzer that use the potential of the substrate electrode as the reference potential are used to measure the energy distribution of the neutral particles incident on the substrate and perform mass analysis. Analysis of positive and negative ions and neutral particles incident on the substrate to which power is applied, and accurate measurement of energy distribution can be performed, and information on positive and negative ions, neutral particles, and their relation to energy in the etching process can be obtained. Will be able to Therefore, the present invention can provide a deeper understanding of the reactive ion etching process particularly used for processing semiconductors and electronic components.
An analysis method and an analysis device that greatly contribute to process development can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a coordinate system and a distribution function in the analysis method of the present invention.

FIG. 2 is a schematic diagram showing a configuration of an analyzer according to an embodiment of the present invention.

FIG. 3 is a schematic diagram showing a configuration of an analyzer according to another embodiment of the present invention.

FIG. 4 is a schematic diagram showing a configuration of a lens system and a deflection ion energy analyzer in the analyzer of the present invention.

5 is a graph showing a calculation example of local sensitivity of the deflection ion energy analyzer shown in FIG. 4 in comparison with a calculation example of local sensitivity of the coaxial ion energy analyzer.

FIG. 6 is a schematic diagram showing a configuration of a conventional analyzer using a coaxial ion energy analyzer.

[Explanation of symbols]

 21: Plasma chamber 22: High frequency coil for plasma generation 24: Substrate electrode 24a: Orifice 27: High frequency power supply 28: Lens system 33: Deflection type ion energy analyzer 34: Mass analyzer 37: Energy analysis controller 38: Mass analysis control Unit 44: Swept voltage source

Claims (4)

[Claims] 1. A gas mainly comprising a reactive gas is introduced into a vacuum, and a plasma is formed at a low pressure by using alternating power, high frequency power, microwave power, or the like, and the introduced gas is decomposed into plasma to generate atoms and molecules. In a method for analyzing a substrate incident ion in an etching plasma of an etching apparatus in which a substrate is placed on a substrate electrode in contact with plasma using radicals and ions, and a substrate is etched, high-frequency power is applied to the substrate electrode, The ions incident on the substrate to the deflection ion energy analyzer and the mass analyzer, and measure the energy distribution of the ions incident on the substrate electrode using the reference potential of the deflection ion energy analyzer and the mass analyzer as the potential of the substrate electrode. A method for analyzing ions incident on a substrate in an etching plasma, characterized in that: 2. A gas mainly composed of a reactive gas is introduced into a vacuum, and a plasma is formed at a low pressure by using alternating power, high frequency power, microwave power or the like, and the introduced gas is decomposed into plasma to generate atoms and molecules. In a method for analyzing a substrate incident ion in an etching plasma of an etching apparatus in which a substrate is placed on a substrate electrode in contact with plasma using radicals and ions, and a substrate is etched, high-frequency power is applied to the substrate electrode, Neutral particles incident on the substrate electrode are ionized after neutralizing the neutral particles incident on the substrate electrode, and then guided to the deflection ion energy analyzer and the mass analyzer, and the reference potential of the deflection ion energy analyzer and the mass analyzer is used as the substrate electrode potential. A method for analyzing ions incident on a substrate in an etching plasma, comprising measuring an energy distribution of the substrate. 3. A gas mainly containing a reactive gas is introduced,
It has a plasma generation chamber that generates etching plasma at low pressure with alternating power, high frequency power, microwave power, etc., and uses the generated atoms, molecules, radicals, and ions to perform plasma decomposition of the introduced gas in the plasma generation chamber. In an analyzer for etching substrate incident ions in an etching plasma of an etching device for etching a substrate on a substrate electrode arranged at a position in contact with the plasma, an analyzer for analyzing ions incident on the substrate electrode to which high-frequency power is applied, Analysis of substrate incident ions in an etching plasma, comprising a deflection type ion energy analyzer and a mass analyzer having a substrate electrode potential as a reference potential and configured to measure an energy distribution of ions incident on the substrate electrode. apparatus. 4. A gas mainly comprising a reactive gas is introduced,
It has a plasma generation chamber that generates etching plasma at low pressure with alternating power, high frequency power, microwave power, etc., and uses the generated atoms, molecules, radicals, and ions to perform plasma decomposition of the introduced gas in the plasma generation chamber. In an analyzer for etching substrate incident ions in an etching plasma of an etching apparatus for etching a substrate on a substrate electrode arranged at a position in contact with plasma, the ions incident on the substrate electrode are analyzed with the substrate electrode to which high-frequency power is applied. An ionization chamber for ionizing neutral particles incident on the substrate electrode is provided between the analyzer and the analyzer, and the analyzer is operated together with the ionization chamber by a deflection type ion energy analyzer and a mass analyzer using the substrate electrode potential as a reference potential. Characterized in that it is configured to measure the energy distribution of neutral particles incident on the substrate electrode. Analyzer of substrate incident ions in the etching plasma that.