JPS59196600A - Neutral particle implanting method and its device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a material implantation method using high-energy neutral particles instead of ions in an ion implantation method, and an apparatus for the same.

Compared to other thermal diffusion methods and melting methods, the ion implantation method allows various substances to be injected into the target material at a lower temperature, and it has better control over the injection amount, implantation depth, distribution, etc. It has the advantage of being able to inject substances with a certain level of solubility or higher solubility, and is widely used for impurity injection in semiconductor element manufacturing processes, hardening of material surfaces, controlling the coefficient of friction, and synthesis of materials. . However, in the above-mentioned applications, it is not essentially necessary that the implanted material be ions; ionization is merely required for the addition of energy and the metering control of the implanted material flow.

On the other hand, when a target substance is electrically insulated by implanting a substance using ions, charging occurs, which causes various problems.

For example, in the case of semiconductor devices, MO8IC! Dielectric breakdown of the gate oxide film occurs. In particular, recently, ion implantation has become more concentrated than before, and gate oxide films tend to become thinner as semiconductor devices become more highly integrated, making dielectric breakdown due to ion implantation more likely to occur. It has become.

Furthermore, synthesis of new materials requires an order of magnitude higher implantation amount than impurity implantation in the semiconductor device manufacturing process, which increases the degree of charging, making it difficult to apply ion implantation to insulators. ing. A method of simultaneously irradiating an electron beam to prevent charging due to ion implantation has been proposed, but it is difficult to irradiate the entire implanted surface with the electron beam in a manner that neutralizes the ion charge. Heating caused by beam irradiation becomes a problem.

The present invention was developed in view of the above points of the ion implantation method, and the implanted material particles are accelerated to the required energy and separated from other material components in the ion state, and then the ions are neutralized. By doing so, it is an object of the present invention to provide a method and apparatus that can inject a substance into a target substance that is an electrical insulator while preventing charging. The present invention will be explained below based on the drawings.

Figure 1 is a principle diagram of an embodiment of the present invention, where 1 is an ion source, 2 is an ion source, and 2 is an ion source.
is a mass separation magnet, 8 is a particle beam of the substance to be injected,
4 is a gas chamber for neutralization, 5 is a target substance, 6 is a moving table, and 7 is an injection chamber.

Until the ions enter the gas chamber 4, the ions are accelerated to the required energy and only the components of the substance to be implanted are mass separated, just as in the case of normal ion implantation. The ions that have entered the gas chamber 4 undergo charge exchange with gas molecules or atoms within the gas chamber 4, and most of them are neutralized. At energies of several tens of KeV or higher, at which ion implantation is normally performed, beam scattering and energy loss due to this reaction are often negligible. A portion of the incident beam passes through the gas chamber 4 as ions, but most of the beam is neutralized, so that charging due to beam irradiation can be significantly reduced compared to the case of normal ion implantation.

Further, if the supply of gas for neutralization is stopped and the inside of the gas chamber 4 is evacuated to a high vacuum, normal ion implantation can be performed as is.

Unlike ions, neutralized particles are not affected by electric or magnetic fields. Therefore, in order to irradiate a wide area with the neutralizing beam, the target material 5 is mechanically moved and scanned.

By deflecting and removing ions from the beam that has passed through the gas chamber 4 using an electric or magnetic field, it is possible to further reduce the charge caused by beam irradiation. Figure 2 shows the principle of this case. and shows only the deflection part, 8 is the particle beam incident on the gas chamber, 4 is the gas chamber, 5 is the target substance, 8 is the differential pumping system, 9 is the deflection electrode,
10 is a neutralized beam component and 12 is a 7 Alladay cage. The process until the ion beam 8 enters the gas chamber 4 is the same as in the embodiment shown in FIG. 1 or in normal ion implantation. Of the beam that has passed through the gas chamber 4, the components 11 that are not neutralized and remain as ions are bent by the electric field between the deflection electrodes, and only the neutral particles 10 are irradiated onto the target material 5. Electrification can be further reduced than in the case of the embodiment shown in . Neutralized beam 1
When it is desired to irradiate a wide area with 0, scanning is performed by mechanically moving the target substance 5, as in the embodiment shown in FIG. Since the rate at which ions pass through the gas chamber 4 as they are remains constant unless the conditions are changed, by measuring the current of the deflected ion beam with the Faraday cage 12, it is possible to determine the fluctuation of the ion beam and the amount of ions injected into the target material 5. The amount of neutral particles 10 can be indirectly known. Furthermore, by placing the target substance 5 at the position of the Faraday cage 12, it is possible to perform neutral particle injection and normal ion implantation alternately or in parallel.

In addition to using a gas chamber, there is a method for neutralizing positively charged ions by providing an electron generation source in the light layer of the ion beam. Although this method has lower neutralization efficiency than the gas chamber method in the energy range of normal ion implantation, it has the advantage of reducing the burden on the exhaust system. Furthermore, even when using the gas chamber method, the efficiency of neutralization decreases as the energy of the ions increases, but this point can be improved by using negative ions instead of the positive ions used in normal ion implantation. be done. Further, negative ions can be neutralized by utilizing electron desorption by light irradiation. No matter which of the above methods is used for neutralization, the present invention can be carried out without any change in principle.

As shown in FIG. 2, by selecting only neutral particles, it is possible to reduce the charging of the target substance 5 whose surface is an insulator, but this alone cannot completely prevent charging. The reason for this is that secondary electrons are emitted from the target material 5 due to the energy of the injected neutral particles. Since the energy of these secondary electrons is generally below several eV, if the target substance is charged to several eV, secondary electron emission is suppressed and the charging stops at approximately that level. however,
If this charging also becomes a problem, it can be prevented by applying an electric field to the target substance 5 to suppress secondary electron emission.

FIG. 3 is a diagram showing the principle of suppressing secondary electron emission from a target substance, and only shows the vicinity of the injection substance. 5 is the target substance, 6 is the moving stage, 13 is suppressed by the electric field between the child suppression electrodes 18, and the gate 1. l- has the effect of preventing charging of the target material due to secondary electron emission and can perform material injection similar to ion implantation, and is useful for semiconductor device manufacturing, material synthesis, and surface treatment. This will greatly contribute to the field of technology.

[Brief explanation of the drawing]

Figure 1 is a principle diagram for explaining one embodiment of the present invention, Figure 2 is a diagram for explaining an example of implementing the present invention by separating ionic and neutral particles, and Figure 3 is a diagram for explaining secondary electrons. It is a figure for explaining the example which suppresses release and implements this invention. In the figure, ■ is an ion source, 2 is a mass separation magnet, 3 is a particle beam, 4 is a gas chamber, 5 is an object hole, IC, =,:
, :, The remaining beam components are as follows: 12 is the 7 arade sensor, 18 is the secondary electron suppression electrode, and 14 is the power source. -Day 58 Spear 2 Figure 3 +0 13 5 6 590-

Claims (2)

[Claims] (1) A method of material injection by irradiating a solid target material with a high-energy particle beam, characterized in that ions accelerated to the required energy are turned into neutral particles and irradiated to the target material. Particle injection method. (2) Neutralization function for accelerating ions to the required energy and then converting them into neutral particles in the path of the ion beam in equipment that implants materials by irradiating a solid target material with a high-energy particle beam Neutral particle injection device 0 characterized by comprising: