JPH05174779A - Ion implantation device - Google Patents

Abstract

PURPOSE:To make irradiation with electron beam for neutralization in order to prevent electrostatic charge at the time of ion implantation. CONSTITUTION:A coil 3 is installed in such a way as surrounding an ion beam 5 to be implanted into a specimen approx. perpendicularly thereto, and at the left and right ends of the coil 3, shielding magnetic pieces 2a, 2b are installed to prevent leakage of the magnetic field. An electron gun 1 is composed of a cathode 1a, anode 2b, and an electrode 1c to adjust the final emission energy. An electron beam 6 flies toward the specimen 4 while drawing a spiral track by the interaction with the magnetic field. According to this constitution, a large current electron beam with low energy can be transported onto the specimen effectively, and its bearing low energy prevents damage to the specimen and generation of secondary electrons, and it is possible to prevent electrostatic charge and make neutralization of eventually generated charges effectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion implantation device,
In particular, it relates to a device for implanting impurity ions into a semiconductor device such as a high density LSI in which charging is a problem.

[0002]

2. Description of the Related Art Ion implantation devices are most widely used as impurity ion introduction devices in semiconductor device manufacturing processes. In recent years, with the miniaturization and high density of semiconductor elements,
Due to the high-current ion beam implantation for the purpose of improving the throughput in the manufacturing process, destruction of the device due to charging of the semiconductor surface has become a problem. In order to prevent charging, a method of spraying electrons on the semiconductor surface has been put into practical use. For example, in Japanese Patent Application Laid-Open No. 2-295048, FIG.
As shown in, a neutralization method using a high-energy electron beam is proposed. A primary electron beam 1a of several hundred eV is extracted from the electron gun 1 and irradiated on the electrode 7. The irradiation generates secondary electrons 6b on the electrode 7. By setting the potential of the electrode 7 higher than the potential of the sample 4 in advance, the secondary electrons 6
b is deflected in the direction of the sample 4 and irradiated.

[0003]

In the above conventional technique, the electron beam of several hundred eV is irradiated on the sample, so that secondary electrons are generated on the sample. Some of the secondary electrons return to the sample,
Some scatter on other electrodes. Therefore, even if the ion beam current amount and the primary electron current amount are controlled to be equal, sufficient neutralization cannot be realized. In addition, if the amount of secondary electrons on the surface of the sample exceeds the amount of primary electrons, there is a problem such that charging is reversed.

It is an object of the present invention to provide an ion implanter equipped with an electron shower that efficiently neutralizes charge by using low energy that produces a small amount of secondary electrons on a sample. To do.

[0005]

In order to achieve the above object, a means for efficiently transporting an electron beam of low energy, that is, several tens eV to the sample surface is indispensable. In the present invention, the electron beam is made to fly while drawing a spiral orbit in the magnetic field generated by the coil on the cylinder, and the electron beam is transported to the sample surface while preventing divergence due to the space charge created by the electron beam itself. At this time, the electron gun is installed outside the coil magnetic field, and the electron beam is made incident near the center of the coil magnetic field.

[0006]

The electron beam once wrapped around the magnetic flux near the center always flies near the center and never diverges. Therefore, even a low-energy electron beam can be efficiently transported to the surface of the sample, and the secondary electron generation efficiency due to the irradiation of the low-energy electron beam is small, so that the charge can be efficiently neutralized.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

An ion beam 5 is implanted almost vertically into a sample 4 such as a semiconductor wafer. The coil 3 is installed so as to surround the ion beam 5. Shielding magnetic bodies 2a and 2b are installed at the left and right ends of the coil 3 to prevent magnetic field leakage. The electron gun 1 is composed of a cathode 1a, an anode 2b, and an electrode 1c for adjusting the final emission energy. The electron beam 6 extracted from the cathode 1a first advances linearly and enters the coil magnetic field. The electron beam 6 flies toward the sample 4 while drawing a spiral orbit by the interaction with the magnetic field. By adjusting the coil current so that the radius of gyration of the electron beam 6 becomes smaller than the radius of the coil 3, the electron beam 6 can be transported to the sample 4 while being adjusted to the range where the ion beam 5 exists. In this embodiment, magnetic bodies 2a and 2b are provided at the ends of the coil to limit the magnetic field range. This eliminates the influence of the magnetic field inside the electron gun,
The electron beam 6 can be transported linearly to the entrance of the coil.
In addition, since the pinch magnetic field is seen from the sample 4,
It is possible to return slightly generated secondary electrons onto the sample 4.

The cathode 1a of the electron gun 1 uses a tungsten filament or the like. However, when tungsten is disliked as an unnecessary impurity element, the coil 3 is lengthened, and
The tungsten vapor can be prevented from reaching the sample 4 by moving the electron gun position away from the beam center.

The electron gun 1 may be installed axially symmetrically at 360 degrees, or a plurality of individual electron guns may be arranged on the circumference.

[0011]

According to the present invention, a low-current high-current electron beam can be efficiently transported onto a sample, and since the energy is low, damage to the sample and generation of secondary electrons are prevented, which is efficient. It is possible to prevent static electricity and neutralize static electricity.
Moreover, since a pinch magnetic field is generated on the sample, it can be returned to the sample even if secondary electrons are generated. Furthermore, this configuration
Since the electron gun position can be moved away from the sample and the ion beam to some extent, the influence of the tungsten vapor from the electron gun cathode can be avoided. By using the ion implanter equipped with such electron showers, ion implantation for submicron-sized semiconductor devices can be realized with high throughput.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an electron shower according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conventional electron shower.

[Explanation of symbols]

1 ... Electron gun, 1a ... Cathode, 1b ... Anode, 1c ...
Electrodes, 2a, 2b ... Magnetic material, 3 ... Coil, 4 ... Sample, 5
… Ion beam, 6… electron beam.

Claims (1)

[Claims] 1. An ion implanting apparatus comprising an ion source for producing ions, an ion optical system for accelerating and converging the ions, and an implanting chamber for irradiating a sample with the ions. An ion implanting device, comprising: an electron gun for generating an electron current beam of the same degree; and a coil installed between the electron gun and the sample so as to surround the ion beam.