JPS6380449A - Microwave metallic ion source - Google Patents

Abstract

PURPOSE:To improve ionization efficiency of sputtered neutral atoms by using coils linked with a microwave source in order to obtain a microwave radiant means by which microwaves are radiated inside a plasma generating chamber. CONSTITUTION:A plasma generating chamber 21 is equipped with a gas introduction port 22 for introducing a discharge holding gas, an ion introduction port 23, and a microwave introduction port 25. coils 26 are installed inside the introduction port 25. A target holder 28 equipped with water-cooled pipes 27 is mounted on an end of the coils 26, and a sputtering target 29 is mounted on the holder 28, and they are insulated from the generating chamber 21 by the use of insulators 30. A magnet coil 31 is installed on the periphery of the generating chamber 21. Microwaves are introduced into the coils 26 from the microwave source 32, and a negative voltage to the generating chamber 21 is impressed on the target 29 by the use of a sputtering power source 34. Ionization efficiency of neutral atoms sputtered in this way can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ion source for thin film processing such as film deposition and ion implantation using an ion beam in semiconductor processing technology, surface treatment technology, etc. Conventional technology for high-speed metal ion beam transport In recent years, thin film processing technology such as film formation that uses ion energy to control physical properties has been attracting attention. In particular, in order to form metal films or metal oxide films, it is generally necessary to irradiate a substrate with a large amount of high-purity metal ions at low energy, but ion sources that use compound gases have a limited number of metal ion species. , and sufficient metal ions for film formation have not been obtained.

Therefore, in order to obtain an arbitrary metal ion beam, a metal sputtering target is provided in the ion source, and the metal neutral atoms sputtered with the sustaining gas are ionized in the plasma and extracted together with the ions of the sustaining gas. , a method of separating using a mass separator is considered.

Examples of technologies that adopt this concept include "M, Y"
amashita and J, Shimizu:
Proceedings of the Interna
tionalIon EngineeringCon
gress, l5IAT's3&IPAT'83
, Kyot.

(1983), P, 385. Figure 2 shows an overview of this ion source.

A target 2 and a high-frequency coil 3 are provided in a cylindrical plasma generation chamber 1, and the plasma generation chamber 1 has a gas inlet 4 and an ion outlet 5. An extraction electrode 6 is provided.

A discharge sustaining gas such as argon is introduced through the gas inlet 4, and a high frequency wave of 13.56 MHz is emitted from the high frequency coil 3 to cause high frequency discharge. When a part of the sputtering target 2 to which a negative voltage is applied is filled with a substance to be ionized, ions generated by high-frequency discharge strike this negative electrode and sputter the substance.

Sputtered neutral atoms are ionized in the plasma,
O is extracted together with ions of the discharge sustaining gas by the ion extraction electrode 6, and separated by a mass separator.

In FIG. 2, 7 is a target holder, 8 is a cooling water pipe, 9, 9a and 9b are insulating insulators, 10 is a high frequency power source, 11 is a sputtering power source, and 12 is an ion extraction power source.

This structure has the advantage that the high-frequency radiation coil is located inside the plasma generation chamber, so it operates stably even if sputtered matter adheres to it, and that the plasma is confined within the coil, resulting in good power efficiency.

Problems to be Solved by the Invention However, in order to utilize high-frequency discharge without a magnetic field,
Since the plasma density is low, in order to correct this problem, the pressure inside the ion source must be increased to 10 Torr, and the pressure in the ion transport chamber also becomes high, resulting in the problem that the ion beam cannot be transported sufficiently.

Means for Solving the Problems The present invention solves the above problems, and uses microwave discharge using electron cyclotron resonance to generate plasma, and uses a rigid coil to radiate microwaves into the plasma generation chamber. This is what was used.

Operation With the above configuration, microwave electron cyclotron resonance generates high density (10"3 Torr) low pressure (10"3 Torr)
By the action of the rigid coil, which is a microwave radiation means, the high-density plasma causes a local discharge to the sputtering target (kJ), and the ionization rate of the sputtered neutral atoms is also improved.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

In FIG. 1, 21 is a plasma generation chamber, 22 is a gas inlet for introducing discharge sustaining gas into the plasma generation chamber 21, 23 is an ion outlet, and 24 is an ion extractor for extracting ions from the ion outlet 23. It is an electrode. There is a microwave inlet 25 in the plasma generation chamber 21, and a rigid coil 26 (for example, inner diameter 28mm, thickness 2mm) inside.
(2) A copper pipe with a length of 80 mI is provided with a spiral groove with a slit width of 2 mm and a pitch of 18 grooves over a total length of 360 + a++. This so-called Rigitano coil is a slot line type helical coil developed by Rigitano, and is used as a microwave radiation antenna. At one end of the rigid coil 26 there is a target holder 28 with a water cooling pipe 27 attached.
A sputtering target 29 is attached to the target holder 28, and these targets are connected to the plastic and sputtering generation chamber 21.
It is electrically insulated from the insulating insulator 30. Also,
A magnet coil 31 is installed around the outer periphery of the plasma generation chamber 21 to obtain a magnetic field that causes electron cyclotron resonance in response to microwaves.

In such a structure, a discharge sustaining gas such as argon is introduced through the gas inlet 22.

From a microwave source 32 (eg, a magnetron with a frequency of 2.45 GHz), an average power of 50 W t t is conducted through a coaxial line 33 via a microwave inlet 26 to a rigid coil 26 . At this time, the magnetic field of the magnet coil 31 is set so that electron cyclotron resonance occurs on the rigidano coil 26 (for example, 2.45 GHz
876 Gauss for a frequency of ), a high-density plasma is generated in the rigidanocoil 26 (Reference: R, De Dionigi).

M, FontaneBi, E, 5indoni and
G. Li5itano: Applied Phys.
ics Letters, Vol. 19. (1971)
.

P, 19). A negative voltage (for example, -1KV) is applied to the sputtering target 29 attached to the target holder 28 from the sputtering power supply 34 to the plasma generation chamber 21.
), ions generated by microwave electron cycloton resonance discharge strike this sputtering target 29 and sputter the material. The target material released by sputtering is ionized in the plasma within the rigidano coil 26. Optimize the length and gas pressure of the rigid coil 26 (for example, when the length of the rigid coil 26 is 80W+, the gas pressure is 2 x 1O-2
Torr), the ionization efficiency of the target material can be increased. In addition, the ion extraction power source 3
6, if a negative voltage (for example, -30 KV) is applied to the ion extraction electrode 24 with respect to the plasma generation chamber 21, a mixed ion beam of target material ions and discharge sustaining gas ions can be obtained. A pure ion beam of the target material can be obtained by separating the target material.

In this embodiment, the rigid coil 26 is of a helical type with spiral cuts, but the same effect can be achieved even if it is of a digital type with cuts perpendicular to the axis. Further, although 33 is a coaxial line, the same effect can be achieved even if a coaxial tube is used.

Effects of the Invention According to the present invention, high-density plasma is generated even at low gas pressure by microwave electron cyclotron resonance discharge using a rigidanocoil, and by introducing a sputtering target into this plasma, sputtered neutral Since the ionization efficiency of atoms can be increased, a metal (71, T6.Mo, etc.) ion beam with an ion current of 100 μA or more can be efficiently transported in a high vacuum.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a microwave metal ion source according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional metal ion source. 21... Plasma generation chamber, 22... Gas inlet, 23... Ion outlet, 24...
... Ion extraction electrode, 26 ... Rigidano coil, 29 ... Sputtering target, 31
...Magnet coil (magnetic field applying means), 32
......Microwave source, 34...Sputter power supply. Name of agent: Patent attorney Toshio Nakao and one other person? /
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° Sojidenoko 1 le 27 --- Crest, ) 1 2 δ-11 Tate Iwashi Gu 29・-Dar γ, Do

Claims (2)

[Claims] (1) a plasma generation chamber having a gas inlet and an ion outlet; a sputtering target disposed within the plasma generation chamber; and means for applying a negative potential to the sputtering target with respect to the plasma generation chamber; a magnetic field applying means for applying a magnetic field within the plasma generation chamber;
A microwave metal ion source comprising an ion extraction electrode and a microwave radiating means for radiating microwaves into the plasma generation chamber, wherein a rigidano coil connected to a microwave source is used as the microwave radiating means. . (2) The microwave metal ion source according to claim 1, wherein the magnetic field applying means supplies the microwave emitting means with a magnetic field that satisfies electron cyclotron resonance.