JPS61177728A - Apparatus for irradiation with low-energy ionized particle - Google Patents

Abstract

PURPOSE:To enable the sample substrate to be irradiated with ionized particles of high ion current density. by a method wherein ions particles are transported out of a plasma generation chamber as plasma flows of small spreading, and then the energy of the ionized particles is controlled in the neighborhood of the sample substrate. CONSTITUTION:An end of a plasma generation chamber 1 that is opposed to a microwave introduction window 4 is provided with a plasma lead-out port 8, and plasma is led out into a vacuum sample chamber 2. At this time, since the magnetic field caused by a magnetic coil 7 is in the form of a scattered field at the lead-out port 8, it is led out toward sample table 10 as a plasma flow 9 having kinetic energy. the plasma flow 9 has electrically neutral beams; therefore, the beam spreading reduces. Besides, the kinetic energy when ionized particles contained in the plasma flow 9 collide against the sample substrate 11 can be controlled by voltages A, B, and C impressed on the plasma generation chamber 1, an ion lead-out electrode 12, and the sample table 10, respectively.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a low-energy ionized particle irradiation device used for etching, film formation, etc. for semiconductor manufacturing, and in particular, to a low-energy ionized particle irradiation device that controls ionized particles in a low energy region, and The present invention relates to a low-energy ionized particle irradiation device that efficiently irradiates a sample with ionized particles.

[Conventional technology]

Methods of irradiating sample substrates with plasma, ions, etc. are being considered as etching and film forming techniques for semiconductor manufacturing. Typically, this type of apparatus has a plasma generation chamber that turns supplied gas into plasma, and an ion beam and a plasma stream are extracted from this plasma generation chamber and irradiated onto a sample substrate. At this time, the problem is how to efficiently transport and irradiate ionized particles from the plasma generation chamber to the sample substrate, and how to control the kinetic energy (ion energy) of the ionized particles. In terms of device configuration and operability, it is necessary to maintain a necessary distance between the plasma generation chamber and the sample substrate so that a large amount of particles having a desired ion energy can reach the sample substrate.

[Problem that the invention seeks to solve]

However, O~5 is useful for the etching and film formation.
It is generally difficult to efficiently transport a large amount of ionized particles in the low energy region of 00·V. The extraction of ions K from a plasma generation chamber in a low energy region such as
rgy Ion B@am EtehlngJ(J,M
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vol, 128. N15, PP, 1077~
1083 (1981): 1 is said to be suitable, but the beam spreads with the transport distance of ionized particles9,
There was a problem in that it was not possible to maintain a large distance between the plasma generation chamber and the sample substrate. A known method for suppressing this beam spread is to generate thermoelectrons in the ion beam and neutralize the charges. This method uses a hot filament to generate thermoelectrons, so the hot filament deteriorates in response to reactive gas particles.
It could not be called a practical method, and a more practical method was desired.

In view of the above circumstances, the present invention has been made to solve these drawbacks.The present invention is designed to send a circular plasma beam with a small spread from a plasma generation chamber, and to eliminate the ionized particles contained in the plasma flow. By controlling the kinetic energy near the sample substrate, low-energy ionized particles are efficiently transported.

The present invention provides a low-energy ionized particle irradiation device that can irradiate.

[Means for solving problems]

The low-energy ionized particle irradiation device according to the present invention includes a plasma generation chamber for generating plasma, a plasma extraction port provided in the plasma generation chamber, and ionized particles contained in the Blaze-F flow discharged from the plasma extraction port. a vacuum sample chamber in which the sample substrate is placed on a sample stage and electrically connected to the plasma generation chamber in order to irradiate the sample substrate with the plasma flow emitted from the plasma outlet; In order to transport the plasma beam to the sample substrate, a voltage is applied to each of a plasma transport means using a magnetic field, an electric field, or a gas differential pressure alone or in combination, and a sample stage that supports the plasma generation chamber and the sample substrate. and means for controlling the kinetic energy of ionized particles contained in the plasma flow discharged from the plasma extraction port by applying a potential difference therebetween.

Furthermore, in the low-energy ionized particle irradiation device according to another aspect of the present invention, an ion extraction electrode is disposed in the vicinity of the sample substrate between the plasma extraction port of the plasma generation chamber and the sample substrate. The apparatus includes means for extracting ionized particles contained in the plasma flow discharged from the plasma extraction port by the ion extraction electrode.

[Effect]

In the present invention, after transporting the plasma beam from the plasma generation chamber as a small-spread plasma beam, the energy of ionized particles is controlled near the sample substrate.
(2) Even if the distance between the Prada 1 generation chamber and the sample substrate is increased in the following low ion energy range, it is possible to irradiate the sample substrate with ionized particles with a high ion current density.

In another aspect of the present invention, after the plasma flow is transported from the plasma generation chamber, only the ionized particles contained in the plasma flow can be extracted by an ion extraction electrode near the sample substrate. At this time, the ion current density can be further increased by providing a plasma flow control mechanism around the plasma flow to control the spread of the plasma flow.

〔Example〕

The present invention will be explained below based on embodiments shown in the drawings.

FIG. 1 is a schematic configuration diagram showing a low-energy ionized particle irradiation apparatus according to an embodiment of the present invention, and shows a case where a plasma generation chamber using microwave excitation is used as a plasma generation source. In FIG. 1, 1 is the plasma generation chamber, 2
is the vacuum sample chamber, 3 is the exhaust system, 4 is the microwave introduction window, 5
is a microwave waveguide, 6 is a gas inlet provided in the plasma generation chamber 1, T is a magnetic coil provided outside the plasma generation chamber 1 and generates a DC magnetic field, and 8 is provided in the plasma generation chamber 1. A plasma extraction port, 9 is a plasma flow emitted from this extraction port 8, 10 is a sample stage disposed in the vacuum sample chamber 2, 11 is a sample substrate placed on the sample stage 10, and 12 is a sample substrate placed on the sample stage 10. This is an ion extraction electrode arranged near the sample substrate 11. Note that 21 is a restraining member for electrically insulating and coupling the plasma generation chamber 1 and the microwave waveguide 5.

Here, the plasma generation chamber 1 is electrically insulated from the sample chamber 2 via an insulating support member 22. The gas introduced into the plasma generation chamber 1 and the residual gas are exhausted by an exhaust system 3. For example, a 2.54 GHz magnetron is used as a microwave oscillation source for plasma generation, and a rectangular waveguide 5. Furthermore, a matching device (not shown),
Connected to the microwave power meter via the isolator. The plasma generation chamber 1 is made of stainless steel, and the outside is water-cooled to prevent temperature rise due to plasma generation. Then, a gas of 2.54G was introduced into the plasma generation chamber 1 through the gas inlet 6, and the gas was
Introduce Hz microwave.

In addition, the magnetic coil 7 generates a direct current magnetic field in a direction perpendicular to the microwave electric field to generate electron cyclotron resonance (ECR).
When a magnetic field is generated that satisfies the conditions (875 glass),
The gas introduced by these interactions (ECR) is turned into plasma. Therefore, a plasma extraction port 8 is provided at the other end of the plasma generation chamber 1 facing the microwave introduction window 4, and plasma is extracted into the vacuum sample chamber 2. At this time, since the magnetic field generated by the magnetic coil 1 at the outlet 8 becomes a divergent magnetic field, the plasma from the outlet 8 does not spread uniformly into the vacuum sample chamber 2, but in the direction of the sample stage 10. It is extracted as a plasma stream 9 having kinetic energy. Plasma caused by bipolar diffusion in such a magnetic field can be transported as a plasma stream. Moreover, since the beam of the plasma flow 9 is electrically neutral, beam expansion due to Coulomb force is theoretically small, and the beam expansion is small compared to transporting only low-energy ions. . The kinetic energy when the ionized particles contained in the plasma flow 9 collide with the sample substrate 11 is determined by the plasma generation chamber 1 in FIG. Voltages A, B and C applied to the ion extraction electrode 12 and the sample stage 10, respectively
can be controlled by For example, the ion extraction electrode 12 is removed and the plasma generation chamber 1 is placed at a positive potential (4
), the sample table 10 is set to a negative potential or ground potential (C), and a potential difference [(4
)-(C)], the kinetic energy of the ionized particles colliding with the sample substrate 11 can be controlled. Furthermore, as shown in FIG. 1, the potential of the ion extraction electrode 12 is set to negative potential or ground potential, and the voltage [[
By multiplying (4) - (0), ions are extracted from the ion extraction electrode 12 and the potential (4) is
The ion energy is controlled by the potential difference between C) and C). In this way, after the plasma flow 9 is transported from the plasma generation chamber 1 to the vicinity of the sample substrate 11, the energy of the ionized particles is controlled.
Even with low energy ionized particles of V, the ionized particles can be irradiated onto the sample substrate 11 with high transport efficiency, that is, by increasing the ion current density on the sample substrate 11.

FIG. 2 is a schematic configuration diagram corresponding to FIG. 1 showing another embodiment of the present invention. In FIG. 2, reference numeral 13 indicates a plasma flow control mechanism as a plasma transport means for controlling the spread of the plasma flow 9 emitted from the plasma generation chamber 1, and reference numeral 14 indicates an exhaust small part provided on the side of the plasma flow control mechanism 13. The opening and other features are the same as in FIG. Thus, the plasma flow control mechanism 13 has a hollow cylindrical shape made of metal and has a small exhaust opening 14, through which the plasma flow 9 passes. This cylindrical plasma flow control mechanism 13 is connected to other components, especially the plasma generation chamber 1. It is electrically insulated from the sample stage 1G, the outer wall of the vacuum sample chamber 2, and the ion extraction electrode 12 by insulating support members 23 and 24, respectively. As a result, by applying voltage ) to the plasma flow control mechanism 13, the plasma flow 9
The surrounding area can be controlled to any potential. That is, FIG. 2 shows an apparatus in which a plasma flow control mechanism 13 is installed in the apparatus shown in FIG. 1 so that the potential around the plasma flow 9 can be controlled. By controlling this potential, it is possible to control the spread of the plasma flow 9, thereby improving the ion current density on the sample substrate 11 and improving the ion current density characteristics with respect to ion energy.

The effective characteristics of the present invention will be explained below with reference to specific data shown in FIGS. 3 to 5. The shape of the plasma generation chamber 1 is a microwave cavity resonator, for example, a circular cavity resonance mode TE 111 is adopted, and a cylindrical shape with a circular dimension of 90 my diameter and a height of 100 fl is used to generate microwaves. Improved discharge efficiency. Since the i-microwave discharge using this electron cyclotron resonance phenomenon has high ionization efficiency, the gas pressure in the vacuum sample chamber 2 is lowered, and the
Experiments were conducted at xIP' ~2 x 10-' Torr. FIG. 3 shows the sample stage, that is, the substrate holder 10 when the potential B of the ion extraction electrode (single mesh electrode) 12 is the ground potential and a positive voltage is applied to the plasma generation chamber 1 in the embodiment configuration shown in FIG. showed an ionic current density of In addition, in FIG. 3, the characteristic I is the plasma generation chamber 1 and the substrate holder 1.
When the distance from 0 is 4 crs.

Characteristic ■ indicates the case where the distance is 14 cm.

The ion current density obtained with such a configuration is much higher than that obtained when the distance between the plasma generation chamber 1 and the substrate holder 10 is the same and a monofilament mesh electrode is installed near the plasma generation chamber 1 as the ion extraction electrode. A large value is obtained. Furthermore, similar characteristics can be obtained by removing the ion extraction electrode 12 in the configurations shown in FIGS. 1 and 2 and applying voltages (A, C) between the plasma generation chamber 1 and the substrate holder 10. . On the other hand, as is clear from Fig. 3, the ion current density tends to decrease when the applied voltage input to the plasma generation chamber 1 is 2006 V or more, and the decrease in the ion current density with respect to the distance between the plasma generation chamber and the substrate holder increases as the voltage increases. It tends to get bigger. This is considered to be because the plasma flow 9 spreads due to the influence of the potential distribution around the plasma flow 90. That is, such problems can be solved by installing a plasma flow control mechanism 13 as shown in FIG.

FIG. 4 shows the ion extraction electrode 1 in the arrangement shown in FIG.
Voltage ω applied to 2 (mesh electrode: mesh 100)
) is set to -300V, and the voltage A of plasma generation chamber 1 is set to -300V.
It shows how the ion current density changes on the substrate holder 10 when the voltage (2) applied to the plasma flow control mechanism 13 is changed for 100V, 150V, and 200VK. Here, characteristics III, IV, and V are the applied voltage A of the plasma generation chamber of 100 V and 1, respectively.
Correspondingly, the length of the plasma flow control mechanism 13 is 15 to 20α when the voltage is 50V and 200V. Fourth
In the figure, as the voltage (2) applied to the plasma flow control mechanism 13 increases, the ion current density on the substrate holder 10 increases. The upper limit of the voltage is determined by the voltage applied to the plasma generation chamber, and if a voltage higher than that is applied, the ion current (plasma flow) on the substrate holder 10 becomes unstable.

Further, similar characteristics can be obtained even if the plasma flow control mechanism 13 is left floating without applying a voltage. In this case, the material of the plasma flow control mechanism 13 may be not only metal but also an insulator. These control the ion current density on the substrate holder 10 by controlling the expansion angle of the plasma flow 9.The ion extraction electrode 12 is removed and the plasma generation chamber 1 and substrate holder 10 are
Similarly, the ion current density can be increased by applying a voltage (C) between the two. Figure 5 shows plasma generation when the voltage applied to the plasma control mechanism 13 is set to the same potential as the plasma generation chamber 1 (characteristic ■) and when the plasma control mechanism 13 is electrically floating (characteristic ■). The ion current density on the substrate holder 10 is shown versus the voltage applied to the chamber. When , the voltage applied to the ion extraction electrode 12 'e-2
00V, and a single leaf mesh electrode was used as the ion extraction electrode 12. Furthermore, if the sample substrate 11 is set to the ground potential, the sample substrate is irradiated with ionized particles having an energy several tens of EVs higher than the voltage applied to the plasma chamber. It is known that the ion energy of is several tens of V higher than the applied voltage). FIG. 5 shows that the ion current density is much higher than that of the conventional ion extraction method in the vicinity of the plasma generation chamber, and has good controllability in that it monotonically increases from 0 to 500·V.

In the above embodiment, a method was described in which the energy of ionized particles was controlled by applying a DC voltage.
If the sample substrate 11 is an insulator, or if the film-forming material is an insulator and the sample substrate 11 is charged, it is necessary to take into account its influence.
It goes without saying that the effects of these charges can be eliminated by applying an alternating current voltage and by using a high frequency power source.

In addition, although the above embodiment described an ECR ion source,
It goes without saying that the present invention can be applied to an ion source configured to emit a directional plasma flow using means such as a magnetic field, an electric field, and a gas pressure difference between the plasma generation chamber and the sample chamber.

Furthermore, as the gas pressure in the vacuum sample chamber 2 where the sample substrate 11 is disposed increases, it becomes difficult to apply voltage between the plasma generation chamber 1 and the sample substrate 11.
A low gas pressure of 0-' Torr or less is preferable.

〔Effect of the invention〕

As explained above, according to the present invention, after the ionized particles are transported from the plasma generation chamber as a plasma stream with a small spread, the energy of the ionized particles is controlled near the sample substrate. Even if the distance between the plasma generation chamber and the sample substrate is increased in the energy range, there is an advantage that the sample substrate can be irradiated with ionized particles having a high ion current density. Furthermore, the ion current density can be increased by providing a mechanism for controlling the spread of the plasma flow around the plasma flow. Therefore, if the present invention is used in an etching/deposition device using low-energy ionized particles, the kinetic energy of the ionized particles can be controlled in the low energy range of 500 V or less, and moreover, it can be used more easily than conventional devices. Since it is possible to take an ion current of 1,000 yen, it has the effect of enabling high-performance processing (low-damage, high-speed etching, high-quality, high-adhesion-speed film formation).

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of the device of the present invention, and FIG.
The figure is a schematic configuration diagram showing another embodiment of the apparatus of the present invention, and FIGS. 3, 4, and 5 are characteristic diagrams obtained by the apparatus of the present invention, respectively. 1... Plasma generation chamber, 2... Vacuum sample chamber, 3
...Exhaust system, 4...Microwave introduction window, 5...
...Microwave waveguide, 6...Gas inlet, 7e.
...Magnetic coil, 8...-Plasma outlet, 9.Fist...Plasma flow, 10...Sample stand (substrate holder) 1
1... Sample substrate, 12... Ion extraction electrode,
13...0 Plasma flow control mechanism, 14... Small exhaust opening, 22, 23, 24... Insulating support member. Figure 1 Figure 2 Figure 3 "tX" matkbei ldF yyo Y 3 V, c
A (v) Figure 4

Claims (3)

[Claims] (1) A plasma generation chamber for generating plasma, a plasma outlet provided in the plasma generation chamber, and a sample substrate for irradiating the sample substrate with ionized particles contained in the plasma flow emitted from the plasma outlet. a vacuum sample chamber placed on a sample stage and electrically insulated from the plasma generation chamber; and a vacuum sample chamber for transporting a plasma flow emitted from the plasma outlet as a directional plasma beam to the sample substrate. A voltage is applied to a plasma transport means using either a magnetic field, an electric field, or a gas differential pressure alone or in combination, and a voltage is applied to each of the plasma generation chamber and the sample stage supporting the sample substrate, and the potential difference between the two is applied. A low-energy ionized particle irradiation device comprising means for controlling the kinetic energy of ionized particles contained in the plasma flow discharged from the plasma extraction port. (2) A plasma generation chamber for generating plasma, a plasma outlet provided in the plasma generation chamber, and a sample substrate for irradiating the sample substrate with ionized particles contained in the plasma flow emitted from the plasma outlet. a vacuum sample chamber placed on a sample stage and electrically insulated from the plasma generation chamber; and a vacuum sample chamber for transporting a plasma flow emitted from the plasma outlet as a directional plasma beam to the sample substrate. A voltage is applied to a plasma transport means using either a magnetic field, an electric field, or a gas differential pressure alone or in combination, and a voltage is applied to each of the plasma generation chamber and the sample stage supporting the sample substrate, and the potential difference between the two is applied. means for controlling the kinetic energy of ionized particles contained in the plasma flow emitted from the plasma extraction port; and an ion extraction electrode located near the sample substrate between the plasma extraction port of the plasma generation chamber and the sample substrate. A low-energy ionized particle irradiation device characterized by comprising means for extracting ionized particles contained in the plasma flow by means of the ion extraction electrode. (3) The low-energy ionized particle irradiation device according to claim 2, wherein the plasma transport means includes a plasma flow control mechanism that electrically controls the spread of the plasma flow.