JP3525134B2 - Cluster ion beam mass separation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mass separation method for cluster ion beams. More specifically, the present invention relates to a mass separation method of a cluster ion beam of a gaseous substance at room temperature, which is useful for surface cleaning of semiconductors and other electronic devices, modification thereof, sputtering and the like.

[0002]

2. Description of the Related Art Conventionally, various gas phase reaction methods have been developed for the purpose of surface cleaning of electronic devices such as semiconductors, surface modification by ion implantation, or thin film formation. Methods such as vapor deposition, CVD, and ion beam vapor deposition have been put to practical use.

However, in the case of these conventional methods, it is difficult to avoid undesired effects such as damage and deterioration of the target solid surface, which is a major problem for manufacturing high-precision and high-quality electronic devices. Was there. That is, for example, as a surface cleaning method, there is known a method in which an inert gas ion such as Ar ion is used to irradiate a solid surface and the impurity atoms and oxides adsorbed on the surface are sputtered to be cleaned. There is. However, in the case of this conventional method, when the incident energy is 100 eV or less, the ion current is extremely small, so that it is necessary to use an ion beam having a high incident energy of several keV. Therefore, it may cause defects on the solid surface,
Alternatively, since Ar is injected into the surface and becomes an impurity atom,
There was a defect that a clean surface could not be obtained. Further, in ion irradiation of a solid surface using monatomic or molecular ions, it is difficult to modify only an extremely shallow surface layer because the ions are implanted inside the solid.

Therefore, as a basic technique for the development of advanced electronics such as ULSI, the solid surface can be cleaned and cleaned without damage while using an ion beam, or to the extremely shallow surface layer portion of the solid surface. There has been a strong demand for the realization of a new ion beam technology capable of performing ion implantation, high quality sputtering, etc.

Such a situation has been a serious problem for the inventor of the present invention who has been studying the cluster ion beam (CIB) technique. As a result of extensive studies, it was found that a gas cluster ion beam generated by ionizing gas clusters of a gas at room temperature overcomes conventional problems as a new technology that has not been known so far. It was revealed. Based on this knowledge, we are already proposing a new technology.

As a result of further study, clusters of various sizes are formed in this cluster. Therefore, in order to improve the selectivity of the gas phase reaction, selective extraction of clusters to be used is performed. Has emerged as a challenge. The present invention has been made in view of the circumstances as described above, and further develops the conventional cluster ion beam technology to further improve high-quality non-damaged surface cleaning and ion implantation into only an extremely shallow surface layer portion. It is an object of the present invention to provide a new method in which layer formation, sputtering, and the like can be easily performed with a small device.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention forms clusters, which are lumpy atomic groups or molecular groups of a gaseous substance at room temperature, and produces clusters by exposing them to electrons. When accelerating ions with an accelerating voltage, a cluster beam is passed through the apertures of a plurality of aperture electrodes, and a voltage is applied to the electrodes to separate the clusters by mass. provide.

That is, usually, a substance which is in a gaseous state at room temperature as described above, for example, a carbide, an oxide, a fluoride, a chloride, a hydride, a sulfide, a noble gas substance and a mixed gas thereof in an appropriate ratio. When a cluster-like substance is used and the cluster ions of these substances are used as an ion beam, the cluster is usually composed of several hundred atoms, so even if the applied voltage is 1 kV, each atom is 10 eV or less. The solid surface is irradiated with the ultra-slow ion beam.

However, in this state, cluster ion beams of various cluster sizes coexist. Therefore, in the present invention, in order to remove, for example, a single atom or ions having a small cluster size, an energy analyzer / accelerating electrode is used, and the cluster size is selected and used within a required range.

Therefore, according to the method of the present invention, the reaction by the cluster ion beam and the high degree of selectivity of the surface treatment are possible, and the excellent action and effect are expected even in a simple and compact device. Hereinafter, the method of the present invention will be described in more detail with reference to Examples.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 of the accompanying drawings is a schematic view of a surface treatment apparatus using an ultra-slow ion beam according to the present invention. When the surface cleaning method will be described using the cluster ion beam along the Figure 1, first, CO ₂ and fluorides or introducing a gaseous gas at ordinary temperature, such as chloride hole (1)
Through the gas source (2) until the gas pressure reaches several atmospheres. Next, the introduced gas is used as a gas source (2).
It is ejected from a nozzle (3) provided at the tip of. At this point, adiabatic expansion forms clusters of hundreds of atoms, that is, clustered atomic groups or clustered molecular groups. This cluster is led to the ionization part (5) through the skimmer (4). When passing through the ionization part (5), a part of the cluster is ionized and becomes a cluster ion. Then, the cluster ions are accelerated by the negative accelerating voltage applied to the acceleration electrode (6) and the substrate holder (7) and collide with the substrate (8). Since one cluster consists of hundreds of atoms, the applied voltage is 1
Even at kV, each atom becomes an ultra-slow beam of 10 eV or less and collides with the substrate.

At this time, since clusters of different sizes coexist, upon ionization, as shown in FIG. 2, a cluster of a specific size is formed by a mass separation means such as an energy analyzer / accelerating electrode system (60). Take it out and use it. The analyzer as this separating means can be realized by combining a plurality of electrode plates having holes and applying an appropriate voltage to each electrode. This allows
For example, those with a small cluster size can be removed.

Of course, the nozzle (3) may have various shapes. In addition, the length and diameter of the nozzle differ depending on the type of gas, and are dimensioned so that clusters are formed by adiabatic expansion. The material of the nozzle may be made of metal other than glass. Further, as an actual device configuration, it is desirable that the space in which the nozzle (3) is placed is exhausted by a differential exhaust pump.

In fact, according to the present invention, it is possible to selectively use, for example, cluster ions having a size of 100 or more.

[0015]

According to the present invention, it is possible to treat a solid surface of high quality and high performance by selectively utilizing the cluster size.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an apparatus for forming a gas cluster ion beam.

FIG. 2 is a cross-sectional view showing an example of an apparatus incorporating a mass separation means.

[Explanation of symbols]

1 gas inlet 2 gas sources 3 nozzles 4 Skimmer 5 Ionization section 6 Accelerating electrode 7 Board holder 8 base plates 60 Energy analyzer / accelerating electrode system

Claims (4)

(57) [Claims] 1. When forming clusters, which are a group of massive atoms or groups of molecules of a gaseous substance at room temperature, and accelerating ions generated by exposing electrons to the clusters by an accelerating voltage, a plurality of aperture electrodes are opened. A mass separation method for a cluster ion beam, characterized in that a cluster beam is passed through a portion and a voltage is applied to this electrode to separate the clusters by mass. 2. The surface treatment method according to claim 1, wherein the solid surface is cleaned without damage. 3. The method according to claim 1, wherein ions are implanted into a shallow surface layer portion of the solid surface. 4. The method of claim 1, wherein the solid surface is sputtered.