JP2001167896A - Method for measuring current of plasma, method and apparatus for processing surface of object using plasma - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems that is largely influenced by variations of current or transit current in plasma and is difficult to accurately measure current, also is very difficult to measure accurately by removing influences of electrons, ions in plasma, secondary electrons generated by contacting with plasma, and in addition, shifting current due to variation of plasma state, and finally is difficult to measure particles being neutral electrically. SOLUTION: An amount of ions in plasma is measured by measuring only relatively high energy of secondary electrons, an influences of electrons in plasma are removed from functional materials. Further, a luminescence spectroscopy of plasma is carried at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring charged particles, and more particularly to a technical field for measuring ion current in plasma.

[0002]

2. Description of the Related Art In measuring ion current in plasma, a Langmuir probe has been inserted into the plasma or a Faraday cup has been installed.

[0003]

In measuring the ion current in the plasma, the effects of electrons in the plasma and transient changes in the current are so great that accurate current measurement has been difficult. In addition, accurate measurements must be made by excluding ions and electrons present in the plasma, secondary electrons generated by contact with the plasma, and the effects of displacement current caused by fluctuations in the plasma state. Was very difficult. Furthermore, it has been difficult to simultaneously measure electrically neutral particles.

[0004]

The effect of electrons in the plasma is removed by a functional material, and the amount of ions in the plasma is measured by measuring only secondary electrons having relatively high energy. Also, the emission spectrum of plasma is used together.

[0005] By the above means, by measuring the amount of secondary electrons, it is possible to measure the amount of a substance to be injected into an object to be processed in the form of plasma and some neutral particles. It contributes to processing.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first plasma current measuring method according to the present invention is characterized in that a semiconductor element is used when measuring a current in a plasma. Preferably, a PIN diode is used as the semiconductor element.

In the second method for measuring the current of plasma according to the present invention, when processing near the surface of an object as an object to be processed by plasma irradiation, a so-called plasma is generated by contact with the object to be processed. It is characterized by measuring secondary electrons.

According to a third plasma current measuring method according to the present invention, when processing the vicinity of the surface of an object to be processed by irradiating the plasma, the current flowing into the object to be processed is measured separately from the plasma to be measured. The present invention is characterized in that an effective secondary electron emission efficiency is calculated by comparing currents of secondary electrons generated by contact.

In a fourth plasma current measuring method according to the present invention, when processing near the surface of an object by plasma irradiation, the current flowing into the object to be processed is separately measured.
In obtaining the effective secondary electron emission efficiency by comparing the current of the secondary electrons, a so-called transient phenomenon in which the potential of the plasma changes is used, and a value in a steady state is used.

According to a fifth plasma current measuring method of the present invention, when processing near the surface of an object by irradiating the plasma, when measuring the secondary electrons generated by the plasma coming into contact with the object to be processed, The total amount of secondary electrons generated from the object to be processed is calculated in consideration of the solid angle between the non-processed object and the secondary electron measuring means.

A sixth plasma current measuring method according to the present invention is characterized in that a so-called displacement current caused by a change in plasma potential is removed when measuring a current in the plasma.

In a seventh plasma current measuring method according to the present invention, when a current in a plasma is measured using a semiconductor element, electrons having a lower energy than a predetermined energy are captured or interposed between the semiconductor element and the plasma. It is characterized by providing a functional material for shielding. Preferably, a functional material having an electron stopping power of less than 1 keV is preferably provided between the semiconductor element and the plasma.

According to the method of treating a surface of a substance using plasma according to the present invention, when treating the vicinity of the surface of an object by irradiating the plasma, any one of the above-described methods for measuring the current of plasma can be performed in a so-called in-situ manner. The method is characterized in that an object to be processed is irradiated with plasma and a substance is injected while the object is being processed.

In another aspect of the present invention, there is provided a method for treating a surface of a substance using a plasma, comprising the steps of: Before irradiating the object to be treated with plasma by plasma and injecting the substance, use a measuring element having a shape equivalent to the material to be irradiated in advance and perform a measurement in consideration of a solid angle between the object and the measuring element. The method is characterized in that the object to be processed is irradiated with plasma later.

An eighth plasma current measurement method according to the present invention is directed to a plasma surface treatment for irradiating an object with plasma to irradiate the surface of the object with plasma. By using the amount of neutral particles and the quantity of atoms and molecules related to plasma surface treatment calculated by ion current measurement by measuring secondary electrons, the number of atoms and molecules related to plasma surface treatment It is characterized in that the quantity is calculated.

An apparatus for treating a surface of a substance by plasma according to the present invention is characterized in that it is provided with means or a function for performing the above-described plasma current measurement method.

Hereinafter, an embodiment will be described with reference to FIG.

The antenna 20 is installed in the vacuum chamber 10 as an example, and the RF power supply 30 is connected as an example.
The power supply may be another electromagnetic wave such as a microwave.
A matching circuit 40 may be provided between the power supply 30 and the antenna 20 in some cases. The vacuum chamber 10 is provided with an inlet 50 for gas or the like, from which gas is introduced. As an example, Ar is introduced and the degree of vacuum is set to about 1333.
It was kept at 22 Pa (10 mTorr).

On the other hand, the workpiece 60 is set in the vacuum chamber. The object 60 is a pulse generator 70 or a second
Connected to the RF power supply 80 of FIG.

The gas introduced by the energy supplied from the power supply 30 is turned into a plasma state. In this case, power of 100 to 600 W was supplied from the RF power supply. On the other hand, the object 6
0 can be maintained at a constant potential by the action of the pulse generator 70 and the second RF power supply 80. At that time, secondary electrons generated by the incidence of ions on the object to be processed are accelerated by the sheath to about the potential. In this embodiment, the diameter is 3c.
Since a negative high-voltage pulse of −6 kV is applied to the copper ball target 85 of m m, the energy of the secondary electrons is also 6 ke.
V or so. The window 90 can be provided with an optically transparent material such as a glass plate at the opening, and can be used for, for example, emission analysis of plasma observed through the window.

In this embodiment, a reverse-biased PIN diode 100 is used as secondary electron measuring means, and a beryllium window 110 having an electron stopping power of about 1 keV is provided on the front surface thereof, thereby detecting only high-energy secondary electrons. And
The influence of the background charged particles existing in the plasma can be prevented. In addition, the PIN diode suppresses the influence of radiant heat from plasma by electronic cooling.

When the processing is performed at a lower voltage, the energy of the secondary electrons to be measured becomes lower.
It goes without saying that the electron stopping power and the thickness of a substance (beryllium in the above example) for excluding low-energy electrons are taken into consideration according to the energy.

Now, a specific example of measurement will be described with reference to FIG. When high-energy electrons reach the PIN diode and generate charged particles inside the diode, the charged particles are accelerated by the bias voltage, so that a current flows through the diode. Since the diode is grounded by a high impedance element, most of the current flows through the charge amplifier 12.
It flows into 0 and is output as an integrated value of the current flowing through the diode, that is, the charge amount Q. Then, the output of Q is differentiator 13
By passing through 0, a secondary electron current is obtained.

In this embodiment, since only a part of the generated secondary electrons is detected, the solid angle of the secondary electron measuring means with respect to the object 60 and the object The distribution of secondary electrons on the object 60 is considered. According to FIG. 3, the distribution of secondary electrons on the processing target 60 can be obtained from a current density distribution flowing through each electrode in a sample having the same shape as the processing target 60 and having a plurality of electrodes.

FIG. 4 shows the amount of secondary electron charge (FIG. 4 (a)) obtained when a high negative voltage having a pulse width of 10 μs is applied (FIG. 4 (a)) and the temporal change of the secondary electron current (FIG. 4 (b)). Is shown. First, in FIG. 4A, when a high voltage pulse is applied from time 0, 2
The amount of secondary electron charge monotonically increases negatively and stops increasing when the application of the high-voltage pulse ends. FIG. 4 (b) is a time derivative of this, and the secondary electron current corresponding to the differentiated value flows only during the application of the high-voltage pulse, and gradually reaches the peak immediately after the application of the pulse voltage and then gradually reaches the peak. It decreases and becomes almost constant after 5 μs. The peak is due to a sudden spread of the sheath around the object to be processed immediately after application of the pulse voltage, and an increase in the incident ion flux transiently. When the sheath width reaches a steady state, the secondary electron current also becomes a constant value.

[0026] While almost the same waveform as the current I _t is also the secondary electron current I _se flowing through the object to be processed shown in conjunction with FIG. 5, the current ratio (I _t / I _se) is increased with time Change (FIG. 5). The current ratio sharply decreases until 2 μs after the application of the pulse voltage, and thereafter becomes substantially constant. This is because a large displacement current is superimposed on the current flowing through the object up to about 2 μs, and it can be seen that the component of the displacement current can be separated from this. Further, since the steady-state value of the current ratio obtained after 2 μs is expressed as a function of the secondary electron emission rate of the object to be processed, the secondary electron emission rate can be easily evaluated from this, and in this embodiment, for example, as shown in FIG. As described above, 5 was obtained as the secondary electron emission rate of the copper ball target as the processing target 60.

[0027]

As described above, by measuring the amount of secondary electrons, it is possible to determine how much substance is actually injected when the surface of the object is processed using plasma. Can be measured. In addition, if the measurement in consideration of the solid angle or the like is performed in advance, it is possible to easily measure and calculate the amount of the substance to be injected into the entire processing object.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of an apparatus used to explain an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a PIN diode and the like used in one embodiment of the present invention.

FIG. 3 is a diagram for explaining a solid angle and the like based on a positional relationship between a spherical workpiece and a PIN diode used in an embodiment of the present invention.

FIG. 4 is a diagram for explaining a relationship between electric charges flowing between a processing object and plasma when a pulse voltage is applied to the processing object in one embodiment of the present invention.

FIG. 5 is a view for explaining handling of a displacement current generated at an initial time in an example of pulse application in one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vacuum chamber 20 Antenna 30 RF power supply 40 Matching circuit 50 Inlet of gas etc. 60 Processing object 70 Pulse generator 80 2nd RF power supply 90 Window 100 PIN diode 110 Beryllium window 120 Charge amplifier 130 Differentiator

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Michihiko Takase 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Keiji Nakamura 126-4, Rakuen-cho, Showa-ku, Nagoya City, Aichi Prefecture (72) Inventor Hideo Sugai 2-4-6 Nakashincho, Kasugai City, Aichi Prefecture

Claims (13)

[Claims] 1. A method for measuring a current in a plasma, comprising measuring a current in the plasma by using a semiconductor element. 2. The method according to claim 1, wherein a PIN diode is used as the semiconductor element. 3. A method for measuring a so-called secondary electron generated when a plasma comes into contact with a processing object when measuring a current in the plasma when processing the vicinity of the surface of the object as the processing object by plasma irradiation. A method for measuring current of plasma. 4. When the vicinity of the surface of an object to be processed is processed by plasma irradiation, a current flowing into the object to be processed is compared with a separately measured current of secondary electrons generated by contact between the plasma and the object to be processed. And calculating an effective secondary electron emission efficiency. 5. The method according to claim 1, wherein when the vicinity of the surface of the object is treated by irradiating the plasma, the current flowing into the object to be treated is compared with the current of a so-called secondary electron which is measured separately to obtain an effective secondary electron.
A plasma current measurement method characterized by using a value in a steady state, excluding a so-called transient phenomenon in which the potential of the plasma changes when obtaining the secondary electron emission efficiency. 6. A method for measuring secondary electrons generated by contact of a plasma with an object when processing the vicinity of the surface of the object by plasma irradiation. And calculating a total amount of secondary electrons generated from the object in consideration of the solid angle of the plasma. 7. A method for measuring a current in a plasma, comprising measuring a current in the plasma by removing a so-called displacement current caused by a change in the potential of the plasma. 8. When a current in a plasma is measured using a semiconductor element, a functional material for capturing or shielding electrons having energy lower than a predetermined energy is provided between the semiconductor element and the plasma. Plasma current measurement method. 9. When the current in a plasma is measured using a semiconductor device, an electron stopping power of 1 k between the semiconductor device and the plasma is measured.
9. The method according to claim 8, wherein a functional material of less than eV is provided. 10. A method for measuring the current of a plasma according to claim 1, wherein the method is performed in-situ when treating the vicinity of the surface of the object by plasma irradiation. A method of surface treatment of a substance using plasma, in which the substance is injected by irradiating the plasma. 11. A plasma current measuring method according to claim 6, wherein the method includes the steps of: irradiating a plasma to an object to be processed and implanting a substance; Using a measuring element having a shape equivalent to the material to be irradiated in advance, performing measurement in consideration of the solid angle between the processing target and the measuring element, and irradiating the processing target with plasma later. A surface treatment method for a substance using plasma. 12. A plasma surface treatment for treating a surface of a processing object by irradiating the processing object with plasma, in combination with an amount of electrically neutral particles such as radicals calculated by plasma emission analysis. Using the number of atoms and molecules related to the plasma surface treatment calculated by the ion current measurement by measuring the secondary electrons to calculate the number of atoms and molecules related to the plasma surface treatment; Measurement method. 13. An apparatus for treating a surface of a substance by plasma, comprising means or a function for performing the plasma current measurement method according to any one of claims 1 to 9.