JPS63126220A - Impurity doping method - Google Patents

Abstract

PURPOSE:To prevent the electrification of the insulator on the surface of a sample and to obtain the impurity doping effect almost equal to the ion implantation method by a method wherein impurities are implanted by injecting neutral grains into a semiconductor or an insulator. CONSTITUTION:The beam led out from a neutral beam source 6 directly passes a beam line 7, and it is injected to the sample such as the wafer and the like which is placed in a sample chamber 5. Pertaining to the beam source 6, there is one having the structure in which ions are once generated by performing an electric discharge and the like, the ions are led out using the desired energy, electric potential is generated by applying voltage to argon gas and the like, and said electrons and the led out ions are recombined. As a result, the electrification of the insulator on the surface of the sample can be prevented, and the effect of impurity addition almost equal to the ion implantation method can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of adding impurities to a semiconductor substrate in order to control electrical characteristics, and particularly relates to an impurity addition method of accelerating and implanting impurities. It is.

[Conventional technology]

Conventionally, ion implantation has been widely used as a method for doping impurities into semiconductors. This ion implantation method is
This is a method that allows doping in the desired amount to the desired location with high precision. This method has also been used to accurately change the surface characteristics of semiconductors and insulators.

FIG. 3 shows a schematic diagram of a commonly used ion implanter. The operation will be explained below with reference to this figure.

Ions generated in the ion source section 1 are extracted and enter an analysis section 2 using a magnetic field, where desired ions are selected. The selected ions are accelerated to a desired energy in an accelerator 3, beam-shaped or scanned at a location called a beam line 4, and then implanted into a wafer in a sample chamber 5.

Note that when ion implantation is performed using only the energy extracted from the ion source section 1, the acceleration section 3 is not necessary, and this type of ion implanter is also commonly used. Furthermore, in the case of a large current ion implanter with a beam current of 1 mA or more, beam shaping, scanning, etc. are not performed in the beam line 4, and the shape of the beam is often determined by a slit or the like. In that case, the wafer is loaded onto a disk in the sample chamber 5, and the disk is rotated to uniformly irradiate the wafer with a beam.

[Problem that the invention seeks to solve]

In a conventional impurity addition method using an ion implantation device, when a sample such as a wafer is irradiated with a beam, a phenomenon occurs in which the insulator becomes electrically charged because the ions are electrically charged. When adding impurities to semiconductors such as silicon, charged beams such as ion implantation are used when the silicon surface is covered with an insulating material such as silicon dioxide, silicon nitride, or photoresist, or is buttered. When such impurities are added, charging causes electrostatic breakdown of the insulator and non-uniform impurity implantation.

This phenomenon is particularly noticeable when performing large current ion implantation with a beam current of 1 mA or more, but it occurs even when the beam current is 1 mA or less as long as a charged beam is used.

As one method for alleviating this charging phenomenon, a method has been proposed in which electron beam irradiation is performed for the purpose of lowering the charged surface potential. However, since the charging status of the wafer varies depending on the state of the sample into which ions are implanted and the pattern shape, the electron beam irradiation amount must be controlled in real time. If the amount of electron beam irradiation becomes excessive, the surface of the sample will become negatively charged, and this effect will cause dielectric breakdown and the like, greatly reducing the yield of good products from wafers.

As described above, neutralization by electron beam irradiation is difficult to control and difficult to put into practical use.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to provide an impurity addition method that can obtain a semiconductor device having almost the same performance as that obtained by adding impurities.

[Means for solving problems]

The impurity addition method according to the present invention is such that neutral particles are implanted into a semiconductor or an insulator.

[Effect]

In this invention, by implanting impurities by implanting neutral particles into a semiconductor or insulator, it is possible to obtain an impurity addition effect almost equivalent to that of ion implantation without charging the insulator on the surface of the sample. .

〔Example〕

As long as impurities are added using a charged beam, charging of the insulator is essentially unavoidable unless there is a mechanism for neutralizing it, and realizing such a mechanism requires complicated equipment and is difficult. be.

In the method using a neutral beam according to the present invention, there is no charging of charged particles by the beam, and there is only a slight increase in potential due to weaning of secondary electrons generated when the beam collides with the insulator surface. This is so small that it can be ignored compared to the amount of charge relative to the beam amount in conventional ion implantation methods.

Embodiments of the present invention will be described below with reference to the drawings.

Several methods can be considered to achieve neutral beam injection, but first, as shown in Figure 1, a neutral beam source 6 is
There is a method in which the beam that has been extracted further is directly passed through the beam line 7 and is struck into a sample such as a wafer loaded in the sample chamber 5. As the neutral beam source 6, ions are once generated by electric discharge, etc., and then extracted with a desired energy, a voltage is applied to argon gas, etc. to generate a potential, and these electrons and the extracted ions are recombined. There are structural ones.

Next, as shown in FIG. 2, there is a method of injecting neutral particles using a conventional ion implantation device with a charge neutralization mechanism 9 added thereto. In this case, desired ions are selected in the analysis section 2 from among the ions extracted from the ion source 1, accelerated in the acceleration section 3, passed through the beam line 4, and then passed through the ion neutralization mechanism section 9. , can be introduced into the sample chamber 5 as neutral particles. Note that the ion neutralization mechanism 9 can be realized by providing an airtight chamber filled with argon gas or nitrogen gas. The ions passing through this gas collide and recombine to become neutralized, and are led to the sample chamber 5.

Further, the neutralization mechanism 9 does not need to be based on this gas, and can also be realized by generating electrons, supplying them to ions in a plasma state, and causing recombination. This second
In the case of the method shown in the figure, the effect as an impurity implantation method can be almost the same as that of ion implantation.

By using neutral beam particles in this way, problems with conventional ion implantation methods, such as electrostatic breakdown caused by charging of insulators and non-uniform implantation, are eliminated. Therefore, when forming semiconductor elements on wafers etc., a high-density beam can be used, and when forming layers with high impurity concentration, such as source/drain electrodes of MOS type transistors and emitter electrodes of bipolar type transistors, it is possible to use a high-density beam. There is no need to consider the effects, and the performance of the injection device can be fully utilized.

Note that the neutralization of charged particles does not need to be 100%,
If it is 50% or more, it can be said that the particles are neutralized. Also,
Even with a neutralization rate of 50% or less, considerable results can be obtained in preventing static electricity on insulators.

Further, as the neutral particles, atoms such as boron and arsenic, or molecules such as boron fluoride can be used.

〔Effect of the invention〕

As described above, according to the impurity doping method according to the present invention, neutral particles are implanted into a semiconductor or an insulator, so that it covers all the applicable ranges of conventional ion implanters that use a charged beam, and It is possible to suppress the charging of insulators, prevent electrostatic damage from occurring, greatly increase the yield of non-defective semiconductor devices, and have the effect of obtaining highly reliable products.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an impurity doping device according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing an impurity doping device according to another field example of the present invention, and FIG. 3 is a schematic diagram showing a conventional ion implantation device. FIG. ■Ion source section, 2 analysis section, 3 acceleration section, 4 beam line, 5 sample chamber, 6 neutral beam source, 7 neutral beam beam line, 9 ion neutralization mechanism section . In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] (1) A method for adding impurities to control the physical properties of a semiconductor or insulator, which method comprises implanting neutral particles into the semiconductor or insulator. (2) The above neutral particles are extracted directly from the neutral particle source,
2. The impurity addition method according to claim 1, wherein the impurity addition method is performed by accelerating the impurity to a predetermined energy. (3) The impurity addition method according to claim 1, wherein the neutral particles are obtained by extracting charged particles from a charged particle source, accelerating them to a predetermined energy, and then neutralizing them.