JPS63146337A - Ion beam device - Google Patents

Abstract

PURPOSE:To perform a simple, accurate feedback to variations in an ion beam current, by fixing sample potential, controlling only a potential difference between a plasma chamber and an ion drawing electrode, and holding the beam current to the specified value. CONSTITUTION:Electric potential 32 of a plasma chamber is determined by output voltage 27 of an iron accelerating high-tension power source 27 and another output voltage 35 of an ion drawing high-tension power source 35, while ion drawing voltage 39 is determined by the output voltage 35 of the ion drawing high-tension power source 23 and output voltage 37 of a controlling high-tension power source 29. Here, when an ion beam current value 34 is varied, the output voltage 37 of the power source 29 is controlled, making the current value constant. At the time of this control, since ground potential in the plasma chamber is always invariable, kinetic energy of an ion beam to be reached to a substrate is constant, and a potential difference between the plasma chamber and mass spectrometric magnetic pressure is also invariable, so that it is unnecessary to change the excitation of an analytic electromagnet. That is to say, the current value of the ion beam is controllable only adjusting output of a controlling high-tension source.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is used to control the physical properties of a solid material by injecting arbitrary ion species into a solid material, for example in a semiconductor backing process. A plasma chamber that turns raw material gas or metal vapor into plasma, an extraction electrode that extracts ions of a specific polarity from this plasma chamber by the action of an electric field, and a specific charge/mass from among the ions extracted by this extraction electrode. Mass spectrometry that extracts only ions with specific ratios! , an electromagnet, and an acceleration tube that forms a travel path until the ions extracted by the 5i quantity analysis electromagnet are accelerated by an electric field to a predetermined kinetic energy, and the surface of the sample at ground potential is charged with the specific charge/mass. The present invention relates to an ion beam device that irradiates a beam of ions having a specific ratio.

[Conventional technology]

FIG. 7 shows the main configuration of an ion beam apparatus conventionally used in semiconductor manufacturing processes.

In other words, the ion beam device consists of a plasma chamber 1 for turning introduced raw material gas or metal vapor into plasma, an extraction electrode 2 for extracting ions of a specific polarity from this plasma chamber by the action of an electric field, and a plasma chamber 1 for applying an electric field to the plasma chamber 1. An ion extraction high-voltage electric current 113 for applying voltage between the plasma chamber 1 and the extraction electrode 2, and a mass spectrometer for extracting only ions with a specific charge/mass ratio from among the ions extracted by the extraction electrode. A magnet 4, a metal container 5 containing these four components, namely a plasma chamber, an extraction electrode, an ion extraction high-voltage power supply, and a JX quantity analysis 'Ks stone.
The main components are an acceleration tube 6, which forms a travel path for ions extracted by a mass spectrometer electromagnet 4 to be accelerated to a predetermined kinetic energy by an electric field, and an ion acceleration high-voltage power source 7, which are arranged in this apparatus. The substrate 8 is irradiated with an ion beam 10 to implant ions. Although not particularly illustrated here, this apparatus also includes equipment such as a vacuum container and an exhaust device that surround the main components.

The process up to ion implantation using the ion beam apparatus configured as described above is as follows. That is, a raw material gas or metal vapor is introduced into the plasma chamber 1, and electrons emitted from, for example, a hot cathode are accelerated in the plasma chamber by an electric field and collide with the raw material gas or metal vapor to become plasma. A positive voltage of several kV to several tens of kV is applied to the plasma chamber 1 by an ion extraction high-voltage power supply 3 using an ion extraction electrode 2 as a base, and a group of ion beams is generated from a slit formed on the extraction electrode side of the plasma chamber. Pull out 9. Since this ion beam group contains various ion species, it is passed between the parallel opposing magnetic poles of the mass spectrometer electromagnet, and the ions with a specific charge/mass ratio are It is accelerated to a desired kinetic energy in the acceleration tube 6 and injected into the substrate 8.

[Problem that the invention seeks to solve]

The problems to be solved by the present invention in the conventional device described above are as follows. Namely.

Conventionally, in order to uniformly implant ions onto a substrate, an alternating electromagnetic field was applied to the ion beam accelerated in an acceleration tube, and the scanning line was moved vertically while moving horizontally over the substrate surface. Operations such as mechanically moving the board itself are performed.

However, since the current value of the ion beam changes, for example, due to pressure fluctuations in the source gas, the current injected into the sample is measured by the measuring device M, and based on this measurement result, the scanning speed can be changed or the moving speed of the substrate can be changed. Do you have to adjust the control system? It was inviting Jfi'll. As another method for uniformly implanting ions, as shown in FIG. 8, control is also performed to keep the current value of the ion beam constant by adjusting the output voltage of the ion extraction high-voltage power supply 3. That is, in the same figure, when the ion beam current 14 decreases as shown in a due to a decrease in the pressure of the source gas, the output voltage of the ion acceleration high voltage IKfi 7 is increased to raise the ground potential of the plasma chamber 1, that is, the potential to the sample, and the ion beam is increased. 10 to restore the ion beam current to its original value. However, since the individual ions forming the ion beam are increasing in speed, at time t2 when the ion beam current has recovered to its original value, the output voltage of the ion accelerating high voltage power supply 7 is lowered from the original voltage, and Increase the output voltage of the ion extraction high voltage power supply 3 to increase the voltage applied between the plasma chamber 1 and the extraction electrode 2,
The voltage to the sample in the plasma chamber is restored based on the voltage and the ion beam current is maintained constant. In this operating state, when the pressure of the source gas increases and the ion beam current attempts to increase as shown in b, the output voltage of the ion accelerating high-voltage power supply 7 is lowered to lower the ground voltage of the plasma chamber 1, that is, the potential with respect to the sample. The traveling speed of the ion beam 10 is reduced to return the ion beam current to its original value. At the time t5 when the ion beam current returns to its original value, the output voltage of the ion accelerating high voltage power supply 7 is reduced. The voltage is raised higher than the original voltage, and the output voltage of the ion extraction high-voltage power supply 3 is lowered to restore the potential of the plasma chamber 1 to the sample to the original level.
and the extraction electrode 2 to keep the ion beam current constant. In other words, according to this method, it is necessary to control the output voltage of the ion accelerating high-voltage power supply and the output voltage of the ion extraction high-voltage power supply in relation to each other to perform uniform ion implantation. The potential difference between the tMi stones fluctuates with the output voltage of the ion extraction high-voltage power supply, and the charge/mass ratio impedes the extraction accuracy of specific ions, making it necessary to control the excitation S current of the tMi stones as well. An object of the present invention is to provide an ion beam apparatus that does not require the complicated control system required in the conventional apparatus and is capable of simple and accurate feedback control of fluctuations in the ion beam current. It is to be.

[Means for solving problems]

In order to achieve the above object, the present invention provides a plasma chamber for converting raw material gas or metal vapor into plasma, and a drawer for extracting ions of a specific polarity from the plasma chamber by the action of an electric field. An electrode, a mass analysis electromagnet that extracts only ions with a specific charge/mass ratio from the ions extracted by the extraction electrode, and an electric field that accelerates the ions extracted by the mass analysis electromagnet to a predetermined kinetic energy. In the ion beam apparatus, which is equipped with an acceleration tube that forms a traveling path until the plasma chamber reaches the ground potential, and irradiates a beam of ions having the specific charge/mass ratio onto the surface of a sample at ground potential, the ground potential of the plasma chamber is An electric field is applied between the extraction electrode and the plasma chamber, which is fixed at a predetermined potential and applies an electric field to the plasma chamber in response to a change from a predetermined value in the amount of ions and ions irradiated onto the sample surface. [Function] As described above, in order to maintain the ion beam amount at a predetermined value, the output voltage of the ion accelerating high voltage power supply is changed to maintain the ion beam amount at a predetermined value. Since only the output voltage of the ion extraction high-voltage power supply, which applies the ion extraction voltage between the plasma chamber and the extraction electrode while being fixed, is controlled in relation to the fluctuation of the ion beam amount from a predetermined value, the control system is It is significantly simpler and thus facilitates precise and precise control.

〔Example〕

FIG. 1 shows a first embodiment of the present invention. In this embodiment, the apparatus includes a plasma chamber 21. Ion extraction high voltage power supply with ion extraction electrode n and constant output voltage.

Mass spectrometry electromagnet U, control high-voltage power supply with variable output voltage, and a metal container housing these 5. Accelerator tube.

The main component is a high-voltage power supply r for ion acceleration with a constant output voltage. The introduced raw material gas and metal vapor are turned into plasma in the plasma chamber, and the ion beam group 9 is extracted by the potential difference between the plasma chamber and the ion extraction electrode n, that is, the output of the ion extraction high voltage power supply n and the control high voltage power supply.

This ion beam group is subjected to mass analysis using separate mass analysis electromagnets and further accelerated to a predetermined kinetic energy, as in the conventional case shown in FIG.

In such a configuration, as shown in FIG. 2, the potential 32 of the plasma chamber is determined between the output voltage of the ion acceleration high voltage power supply n and the output voltage of the ion extraction high voltage power supply,
The ion extraction voltage 39 that acts on ion extraction is determined by the output voltage of the ion extraction high voltage power supply and the output voltage 37 of the control high voltage power supply. Here, if the ion beam current value a changes due to various reasons, for example, when it decreases as shown in C, the output voltage 37 of the control high voltage power supply is controlled to increase, and when it increases as shown in d, the reverse is done. Control is performed to keep the current value constant.

During this control, the ground potential of the plasma chamber, that is, the potential to the substrate, remains constant, so the kinetic energy of the ion beam reaching the substrate remains constant.

Furthermore, since the potential difference between the plasma chamber and the mass spectrometer electromagnet remains unchanged, there is no need to change the excitation of the mass spectrometer electromagnet. In other words, the current value of the ion beam can be controlled by simply adjusting the output of the control high-voltage power supply without changing other conditions.

FIG. 3 shows a second embodiment of the invention. In this embodiment, an ion accelerating high voltage power source γ with a constant output voltage is used to apply a positive high voltage to the plasma chamber 21 using the earth as a base, and an ion extraction high voltage power source n with a variable output voltage is used. A negative polarity 'iE'fL pressure is applied to the ion extraction electrode B using the plasma chamber 21 as a base. If the apparatus is configured in this way, as shown in Fig. 4, when the ion beam current value changes, constant current control can be performed by changing only the output voltage range of the ion extraction high voltage power supply, and the plasma Since the chamber potential 32 is always constant, the energy of the ion beam reaching the substrate remains unchanged.

FIG. 5 shows an example of the tea ceremony. In this example, an ion accelerating high voltage power source γ with a constant output voltage is used to apply a positive high voltage to the plasma chamber 21 using the ground as a base, and an ion extraction high voltage power source n with a variable output voltage is used. A positive high voltage is applied to the ion extraction electrode n with the ground as its base. If the device is configured in this way, as shown in Figure 6, when the ion beam current value changes, constant current control can be performed by changing the output voltage of the high-voltage power supply for extracting ions. . The difference from the second embodiment is that the output voltage of the ion extraction high voltage power supply is lowered when the flow of the ion beam is reduced.

〔Effect of the invention〕

As described above, according to the present invention, the potential to the ground of the plasma chamber, that is, the potential to the sample is fixed and maintained unchanged, and only the potential difference between the plasma chamber and the ion extraction electrode is controlled to control the beam current to a predetermined value. Since the ion beam current is maintained at a predetermined value, the control for maintaining the ion beam current at a predetermined value is extremely simple. Therefore, it is easy to maintain the ion beam current at a predetermined value with high accuracy, and the energy of the ion beam incident on the sample is reduced. is kept unchanged, making it possible to perform highly uniform ion implantation.

[Brief explanation of the drawing]

FIG. 1 shows a configuration diagram of a device according to a first embodiment of the present invention;
The figure is a diagram showing the relationship between the ground potential, potential difference, or voltage of each part of the device in FIG. 1 and the ion beam current, FIG. Ground potential of each part of the device shown in the figure. Figure 6 is a diagram showing the relationship between the ground potential, potential difference or voltage and ion beam current of each part of the apparatus shown in Figure 5, and Figure 7 is an example of a conventional apparatus. The configuration diagram, FIG. 8, is a diagram showing the relationship between the ground potential, potential difference, or voltage of each part of the device in the device shown in FIG. 7, and the ion beam current. 1.21... Plasma chamber, 2.22... Ion extraction electrode, 3.23... Ion extraction high voltage power supply, 4.2
4...Mass spectrometry room $stone, 6,26...acceleration, tube, 7
．． 27... Ion accelerating high voltage power supply, 8, 28... Substrate (sample), 10... Ion beam, 11, 31...
・Earth potential, 12.32... Ground potential of the plasma chamber,
4 toe back = middle "Gayaihan Yui II Masu 4... High voltage power supply for control. M1 diagram 2nd section 3rd factor time → Maki 400 million diagram 6

Claims (1)

[Claims] 1) A plasma chamber that turns introduced raw material gas or metal vapor into plasma, an extraction electrode that extracts ions of a specific polarity from this plasma chamber by the action of an electric field, and ions extracted by this extraction electrode. A mass spectrometry electromagnet that extracts only ions with a specific charge/mass ratio from among the ions, and an acceleration tube that forms a travel path for the ions extracted by the mass spectrometer electromagnet to be accelerated by an electric field to a predetermined kinetic energy. In an ion beam apparatus that irradiates the surface of a sample at ground potential with a beam having the specific charge/mass ratio, the ground potential of the plasma chamber is fixed at a predetermined potential, and the surface of the sample is irradiated with a beam having the specific charge/mass ratio. A voltage applied between the plasma chamber and an extraction electrode that applies an electric field to the plasma chamber in response to a change in the ion beam amount from a predetermined value maintains the ion beam amount at a predetermined value. An ion beam device characterized in that it can be changed. 2) In the apparatus according to claim 1, the ground potential of the plasma chamber is fixed to a predetermined potential by connecting one terminal to the ground potential and the other terminal having a constant positive electrode with respect to the one terminal. a first high voltage power supply that generates a positive high voltage; and a ground potential of the plasma chamber when one terminal is connected to the positive high voltage terminal of the first high voltage power supply and the other terminal is connected to the plasma chamber. is applied between the plasma chamber and the extraction electrode, and the ion beam amount is varied to maintain the ion beam amount at a predetermined value. The voltage applied is
a third high voltage power source, one terminal of which is connected to the positive high voltage terminal of the first high voltage power source, the other terminal of which generates a variable positive or negative polarity voltage, and which is connected to the extraction electrode; An ion beam device characterized in that it can be obtained between the high voltage power source of No. 2. 3) In the apparatus according to claim 1, the ground potential of the plasma chamber is fixed to a predetermined potential by having one terminal connected to the ground potential and the other terminal being connected to the predetermined potential with respect to the one terminal. The first one generates a positive high voltage equal to the value of
This is done by connecting the other terminal of the high-voltage power supply to the plasma chamber, and the voltage applied between the plasma chamber and the extraction electrode and changed to maintain the ion beam amount at a predetermined value is controlled by one terminal. Ions characterized in that a terminal is connected to the plasma chamber side terminal of the first high-voltage power source and generates a variable negative polarity voltage at the other terminal, which is supplied by a second high-voltage power source connected to the extraction electrode. Beam device. 4) In the apparatus according to claim 1, the ground potential of the plasma chamber is fixed to a predetermined potential by connecting one terminal to the ground potential and the other terminal to the predetermined potential with respect to the one terminal. The first one generates a positive high voltage equal to the value of
This is done by connecting the other terminal of the high-voltage power supply to the plasma chamber, and the voltage applied between the plasma chamber and the extraction electrode and changed to maintain the ion beam amount at a predetermined value is controlled by one terminal. between the first high-voltage power source and a second high-voltage power source whose terminal is connected to ground potential and whose other terminal generates a variable positive high voltage with respect to the one terminal and is connected to the extraction electrode; An ion beam device characterized by being obtained by: