JPH0529215A - Beam annealing method - Google Patents

Abstract

PURPOSE:To accomplish formation of single crystal at high speed and at the temperature lower than the temperature of ordinary solid-phase epitaxial growth by a method wherein an ion beam is irradiated from the surface of a substrate, and at the same time, X-rays, ultraviolet rays and the like are irradiated additionally. CONSTITUTION:An ion beam is made to irradiate on the defective region (m) formed in the single crystal substrate 2 located under an amorphous layer 1, the defect is recovered by projecting the secondary radiation rays such as X-rays and the like, and the amorphous phase, formed on the single crystal substrate, is single crystallized. A plurality of paired electron and holes are formed in the substrate 2 to be projected by the energy beam of the secondary radiation rays making almost no vacant lattice parts 3 and interstitial atoms 4. The high density electron and hole pairs electrically work on the neutral vacant lattice parts 3 formed when an ion beam is irradiated, and the neutral vacant lattice points 3 are substituted with the vacant lattice points electrified on the bivalent negative electricity. As a result, the supply of the vacant lattice points 3, by the heat diffusion from the single crystal substrate 2 to the amorphous layer 1, can be made active, the rate of non-elastic scattering is made larger and the speed of single crystallization is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam annealing method for irradiating and heating (annealing) an object to be processed of a sample.

[0002]

2. Description of the Related Art Generally, as a method for heat-treating a sample such as a semiconductor substrate using various heat sources, there is a heat treatment called an annealing method. These methods are distinguished by the type of heating source, and are classified into an electric furnace annealing method, an electron beam annealing method, a laser beam annealing method, an ion beam annealing method, a lamp annealing method, and the like.

The heat treatment for irradiating the beam-like energy in the annealing method is to irradiate the substrate surface with the beam-like energy to heat the substrate in order to single-crystallize the amorphous layer on the single-crystal substrate. . These heat treatment methods were methods of crystal recovery, that is, single crystallization in a state where the surface temperature of the substrate was higher than the normal solid phase epitaxial growth temperature or liquid phase epitaxial growth temperature.
Among these methods, only by the method of irradiating with an ion beam, a single crystal can be crystallized at a temperature lower than a usual solid phase epitaxial growth temperature.

[0004]

However, in the conventional ion beam annealing method described above, the amorphous layer on the single crystal substrate is single crystallized at a low temperature lower than the normal solid phase epitaxial growth temperature. The growth rate is slow, and particularly with light ion irradiation, the single crystallization rate is further slowed down.

Therefore, an object of the present invention is to provide an annealing method for realizing a high single crystallization rate at a low temperature below the normal solid phase epitaxial growth temperature by ion beam irradiation.

[0006]

In order to achieve the above-mentioned object, the present invention single crystallizes an amorphous layer formed on a single crystal substrate at a temperature lower than a solid phase epitaxial growth temperature, and In an ion beam irradiation annealing method for annealing defects generated in a single crystal of a crystal substrate at the low temperature, an ion beam irradiation step of irradiating a beam-like ion on the surface of one main surface of a semiconductor substrate, and the ion beam irradiation step And a secondary energy beam irradiation step of simultaneously irradiating a secondary energy beam for forming a large number of electron-hole pairs during the irradiation with the ion beam, the ratio due to inelastic scattering in the single crystal substrate is A beam annealing method for increasing the number is provided. Also provided is a beam annealing method in which the secondary energy beam is an X-ray, an ultraviolet ray, or an electron beam.

[0007]

With the beam annealing method having the above-described structure, the ion beam is irradiated from the surface of the substrate, and X
By irradiating a single line, an ultraviolet ray, an electron beam, etc. together, the epitaxial single crystallization can be performed at a temperature lower than the normal solid-phase epitaxial growth temperature by increasing the proportion of inelastic scattering in the single crystal substrate. Be speeded up.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram for explaining the concept of the beam annealing method of the first embodiment of the present invention, and FIG.
FIG. 3 is a diagram showing a schematic appearance of a beam annealing apparatus for carrying out the beam annealing method, and FIG.
FIG. 3 is a diagram showing a cross section taken along the line AA ′ of FIG.

This beam annealing apparatus is provided with an introduction port 11 for introducing an ion beam and an introduction port 12 for introducing an X-ray, an electron beam, an ultraviolet ray, etc. in a target chamber 10 which is evacuated by an exhaust system. In the target chamber 10, a semiconductor substrate 13 is installed so that the main surface thereof is irradiated with the ion beam perpendicularly. The target chamber 10 is provided with a transport port 15 for loading the semiconductor substrate 13.

That is, the present invention irradiates an ion beam to single crystallize an amorphous layer on a substrate single crystal at a temperature lower than a normal solid phase epitaxial growth temperature, and at the same time, X-ray, ultraviolet ray, electron beam, etc. Simultaneous irradiation of energy beam
Aim to increase the single crystallization speed.

Next, the beam annealing method of the present invention will be described with reference to FIG.

In FIG. 1, a defect region composed of columnar vacancy points 3 and interstitial atoms 4 in a single crystal substrate 2 under an amorphous layer 1 centering on each ion track incident from the surface. m is formed. The defect region m has a high concentration of vacancies near the central portion a of the column along the ion track, and has a high concentration of interstitial atoms at the peripheral portions b and b ′ in the radial direction.

The defect regions m are irradiated with an ion beam to recover the defects, and the amorphous phase formed on the single crystal substrate 2 is single-crystallized.

First, when the ion beam is irradiated from the surface of the substrate, the vacancy points are changed from the vicinity of the central portion a of the high concentration region to the peripheral region of the low concentration region at a temperature lower than the normal solid phase epitaxial growth temperature. Heat is diffused in the direction (arrow e).

By diffusing in this way, in the vicinity of the central portion a along the ion track, crystals recombine to recover the crystallinity, and in the vicinity of the peripheral portion a, interstitial atoms that have already existed are present. By recombining with 4, the crystal is recovered.

The vacancies 3 are cylindrical peripheral portions b, b.
Thermal diffusion occurs not only in the direction of arrow '(arrow f) but also in the direction of the amorphous layer 2 (arrow g) perpendicular thereto. At this time, the vacancies 3 are recoiled by the incident ions, and are more thermally diffused than the interstitial atoms 4 supplied from the amorphous layer 1 to the single crystal substrate 2, so that the single crystal substrate is amorphous. When the number of vacancies 3 supplied to the layer is large, the vacancies 3 and the interstitial atoms 4 are recombined at the amorphous-single-crystal interface 5, and thereafter, the surplus vacancies 3 remain. It is supplied to the amorphous layer 1.

The extra vacancies 3 supplied to the amorphous layer 1 are vacant spaces corresponding to the vacancies near the interface with the single crystal present in the amorphous layer 1.
6 is formed. When the irradiation of the ion beam is further continued, the vacancies 3 are continuously supplied, and the space region 6 in the amorphous layer near the interface is expanded.

By this expansion, the degree of freedom of thermal vibration of the atoms forming the amorphous layer 1 is increased, and epitaxial single crystallization is induced at a temperature lower than the normal solid phase epitaxial growth temperature.

Secondly, as described above, X-rays, ultraviolet rays, electron beams and the like (hereinafter referred to as secondary irradiation rays) are also irradiated during irradiation of the ion beam.

By simultaneously irradiating the secondary irradiation lines in this manner, first, the energy beam of the secondary irradiation lines hardly forms vacancies and interstitial atoms in the substrate to be irradiated,
Many electron-hole pairs are formed.

The highly concentrated electron-hole pairs electrically act on the neutral vacancies 3 formed during irradiation of the ion beam, and the neutral vacancies 3 are generated. 3 is converted to a divalent negatively charged vacancy. The divalent negatively charged vacancies are the single crystal substrate 2 rather than the neutral vacancies.
It has the property of being able to move easily inside.

That is, the supply of vacancies 3 (arrow h) from the single crystal substrate 2 shown in FIG. 1 to the amorphous layer 1 by thermal diffusion is activated, and the single crystallization speed is increased.

Therefore, in accordance with the ion beam irradiation, the above 2
By irradiating the next irradiation ray at the same time to raise the overall level of irradiation energy, the rate of inelastic scattering is increased and the single crystallization rate is increased. here,
The inelastic scattering is scattering caused by elastic collision, and part of the kinetic energy before scattering is used to excite electrons in atoms and ionize atoms. The kinetic energy becomes smaller than that before scattering.

That is, the simultaneously irradiated secondary irradiation lines in the first embodiment are absorbed by the substance so as to be used for excitation and ionization of electrons of atomic nuclei. As a result, the amount of energy received by the substance for exciting or ionizing electrons can be made larger than the amount of energy received by elastic scattering from the ion beam.

Further, by irradiation with only secondary irradiation rays such as electron beams and X-rays, it is possible to perform single crystallization by irradiating with the ion beam at the same time even if the beam intensity does not cause single crystallization at all. .

Next, referring to the characteristic diagrams shown in FIGS. 3 and 4,
A second embodiment of the present invention will be described.

This second embodiment is only for ion beam irradiation, but the ratio of inelastic scattering is increased by increasing the level of irradiation energy, and the same effect as that of simultaneously irradiating the secondary irradiation line is obtained. Is given to increase the single crystallization rate.

FIG. 3 is a characteristic diagram showing the single crystal acceleration with respect to the irradiation energy. Here, the horizontal axis represents irradiation energy and the vertical axis represents single crystal acceleration. As is clear from this figure, the single crystallinity increases as the irradiation energy increases.

If the single crystallization rate is limited only by the vacancy concentration, the higher the irradiation energy, the smaller the single crystallization rate. This is because, as shown in FIG. 4 (a), from the stored energy distribution due to the nuclear elastic collision, the higher the irradiation energy, the smaller the stored energy in the vicinity of the amorphous layer-single crystal interface. is there. That is, the concentration of vacancies decreases, the number of vacancies supplied to the amorphous layer also decreases, and the single crystallization rate decreases (dotted line in FIG. 3).

However, in reality, as the measured value shown by the solid line in FIG. 3, conversely, the higher the irradiation energy, the higher the single crystallization rate. That is, as shown in FIG. 4B, from the stored energy distribution due to electronic inelastic collision, the higher the irradiation energy, the larger the number of electron-hole pairs formed, and the neutral vacancy point. Is converted into vacancy points charged with negative divalent charges that are easy to move, and the vacancy points are efficiently supplied to the amorphous layer, and the single crystal speed is increased.

As described above, according to the present invention, the single crystallization rate at which the amorphous layer on the single crystal substrate is single-crystallized at a temperature lower than the normal solid phase epitaxial growth temperature by the irradiation of the ion beam is controlled by X-ray and electron. It can be increased by simultaneously irradiating an external energy beam such as a ray or an ultraviolet ray.

Further, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and applications can be made without departing from the scope of the invention.

[0034]

As described in detail above, according to the present invention, it is possible to provide an annealing method for realizing a high single crystallization rate at a low temperature below the normal solid phase epitaxial growth temperature by ion beam irradiation. Also, during ion beam irradiation, X
By simultaneously irradiating an energy beam such as an electron beam, an electron beam, or an ultraviolet ray, the single crystallization speed can be increased.

[Brief description of drawings]

FIG. 1 is a diagram showing a concept of a beam annealing method according to a first embodiment of the present invention.

FIG. 2 (a) is a diagram showing a schematic appearance of a beam annealing apparatus for carrying out the beam annealing method of the present invention, and FIG. 2 (b) is a beam annealing device of FIG. 2 (a). It is a figure which shows the AA 'cross section of an apparatus.

FIG. 3 is a characteristic diagram showing a single crystal acceleration with respect to irradiation energy.

FIG. 4 (a) is a characteristic diagram showing a nuclear accumulated energy concentration with respect to a depth of a substrate, and FIG. 4 (b) is a characteristic diagram showing an electron accumulated energy concentration with respect to a depth of a substrate.

[Explanation of symbols]

1 ... Amorphous layer, 2 ... Single crystal substrate, 3 ...
Vacancies, 4 ... interstitial atoms, 5 ... amorphous single crystal interface,
6 ... Vacant space, 7 ... Substitution nucleus, 10
... target chamber, 11 ... ion beam introduction port, 12 ... X-ray, electron beam, ultraviolet ray, etc. introduction port, 13
... Semiconductor substrate, 14 ... Introducer, 15 ... Transport port, m
… Defect area.

Claims (3)

[Claims] 1. An amorphous layer formed on a single crystal substrate is single crystallized at a temperature lower than a solid phase epitaxial growth temperature, and defects generated in the single crystal of the single crystal substrate are annealed at the low temperature. In the ion beam irradiation annealing method, an ion beam irradiation step of irradiating the surface of the main surface of the semiconductor substrate with beam-like ions, and a large number of electron-hole pairs are externally applied during the ion beam irradiation of the ion beam irradiation step. A secondary energy beam irradiation step of irradiating a secondary energy beam to be formed together, and increasing the ratio of inelastic scattering in the single crystal substrate. 2. The beam annealing method according to claim 1, wherein the secondary energy beam is an X-ray, an ultraviolet ray, or an electron beam. 3. Ions for crystallizing an amorphous layer formed on a single crystal substrate at a temperature lower than a solid phase epitaxial growth temperature, and for annealing defects generated in the single crystal of the single crystal substrate at a low temperature. In the beam irradiation annealing method, a beam annealing method is characterized in that the ratio of inelastic scattering in the substrate is increased by increasing the energy of the ion beam with which the surface of the main surface of the semiconductor substrate is irradiated.