JPH0223021B2 - - Google Patents

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 hot substances or inject substances that exceed their solubility, and is widely used for impurity injection in semiconductor element manufacturing processes, hardening of material surfaces, controlling friction coefficients, and material synthesis. . 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 the target material is an electrical insulator, charging occurs when the material is implanted using ions, which causes various problems. For example, in the case of semiconductor devices, dielectric breakdown of the MOSIC gate oxide film occurs. Especially 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. ing.

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 the implanted surface with an electron beam has been proposed to prevent charging due to ion implantation, 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 electron beam irradiation poses a problem.

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

FIG. 1 is a principle diagram of an embodiment of the present invention, in which 1 is an ion source, 2 is a mass separation magnet, 3 is a particle beam of the substance to be injected, 4 is a gas chamber for neutralization, and 5 is an object. 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. Number of ion implantations typically performed
At energies above 10 KeV, beam scattering and energy loss due to this reaction are otherwise 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 neutralized 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, charging due to beam irradiation can be further reduced.

Figure 2 is a diagram of the principle in this case, showing only the neutralization gas chamber and the deflection part, 3 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 a deflection electrode, 10 is a neutralized beam component, and 12 is a Faraday cage. The process until the ion beam 3 enters the gas chamber 4 is the same as the embodiment shown in FIG. 1 or the case of 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 FIG. When it is desired to irradiate a wide area with the neutralized beam 10, scanning is performed by mechanically moving the target material 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 detect fluctuations in the ion beam and the rate at which the ions are being injected into the target material 5. It is possible to indirectly know the amount of sexual particles 10. In addition, Faraday Cage 12
If the target material 5 is placed at the position, neutral particle implantation and normal ion implantation can be performed alternately or in parallel.

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 most of these secondary electrons is less than a few eV,
If the target material 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 a target substance, 6 is a moving table, 13 is a secondary electron suppression electrode, and 14 is a power source. If the movable stage 6 on which the target substance 5 is placed has a positive potential with respect to the secondary electron suppression electrode 13 by the power source 14, the emission of negatively charged secondary electrons will occur between the movable stage 6 and the secondary electrons. This is suppressed by the electric field between the suppressing electrodes 13, and therefore it is possible to prevent charging of the target substance due to secondary electron emission.

As explained above, the neutral particle implantation method and its device of the present invention can neutralize ions to prevent charging of the target material, which is an electrical insulator, while achieving the same effect as the ion implantation method. It has the effect of making it possible to perform similar material injection, and will greatly contribute to the fields of semiconductor device manufacturing, material synthesis, and surface treatment technology.

[Brief explanation of drawings]

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, 1 is an ion source, 2 is a mass separation magnet, and 3
is a particle beam, 4 is a gas chamber, 5 is a target substance, 6 is a moving stage, 7 is an injection chamber, 8 is a differential pumping system, 9 is a deflection electrode, 10 is a neutral particle beam, and 11 remains as an ion. Beam component, 12 is Faraday cage,
13 is a secondary electron suppression electrode, and 14 is a power source.

Claims (1)

[Claims] 1. In a method of injecting a substance by irradiating a solid target material with a high-energy particle beam, ions accelerated to the required energy are passed through a gas chamber to become neutral particles, and the target material is A neutral particle injection method characterized by irradiation with 2 A device that injects a solid target material by irradiating a high-energy particle beam with a gas chamber in the path of the ion beam to convert the ions into neutral particles after accelerating the ions to the required energy. A neutral particle injection device featuring: