JPH03142921A - Manufacturing device for iii-v compound semiconductor thin film - Google Patents

Abstract

PURPOSE:To make it possible to obtain a high-quality crystal by a method wherein when a III-V compound semiconductor is manufactured by an MBE method, a molecular beam consisting of the element of As or P or a molecular beam consisting of the elements of both of the As and the P is formed by a laser sputtering method. CONSTITUTION:A supporting body (a target holder) 5 for supporting a solid target 4 consisting of at least either one of As or P is provided in a vacuum chamber (a growth chamber) 1 and a laser (a pulsed laser) 6, which irradiates a pulse laser beam on the target 4 on the body 5 through a window 1a, is arranged outside of the chamber 1. The target 4 is sputtered by the irradiation of this laser beam and a molecular beam or an atomic beam consisting of the element of at least either one of the As or the P is formed. That is, when a short pulsed laser beam having a large pulse energy is condensed and irradiated on the metal material, its irradiation part is heated locally and abruptly to a very high temperature and most of evaporation particles which are produced from the metal material are formed into an atomic form. Thereby, a high-quality III-V compound semiconductor thin film can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an apparatus for manufacturing a thin film of a compound semiconductor containing As (arsenic) and P (phosphorus).

<Conventional technology> As a typical method for manufacturing thin films of compound semiconductors,
There is an MBE (molecular beam epitaxy) method.

In the conventional MBE method, a metal material is placed in a crucible called a K-cell (Knudsen cell) and heated to obtain a molecular beam.

When manufacturing a thin film of ■-V group compound semiconductor using such MBE method, molecular beams of As and P are required.
When metal As or P is heated, the generated molecular beam has the form of a four-atom molecule (Asa, P4).

However, rather than depositing such four-atom molecules, two
It has been shown that the use of atomic and molecular beams has a higher probability of adhesion to the substrate and produces high-quality films with good crystallinity.

Conventionally, therefore, a method has been adopted in which a molecular beam from a normal cell is further passed through a high-temperature section and decomposed, thereby generating diatomic molecules. In reality, a cell called a cranking cell that has two heating sections is used to generate a diatomic molecular beam by passing a four-atom molecular beam generated in one heating section through the other heating section. It has gained.

Recently, gas sources (As
Attempts have also been made to obtain As atoms and P atoms by thermally decomposing them using Hs, PH, ).

<Problems to be Solved by the Invention> When manufacturing a thin film of ■-V group compound semiconductor by the conventional MBE method as described above, when a normal cell is used, four-atom molecules are produced as described above. is generated, making it impossible to obtain a high-quality film and resulting in a film with many defects.

Furthermore, since there is a high temperature part in the growth chamber, the amount of gas released increases, making it difficult to maintain an ultra-high vacuum in the growth chamber, and there is a possibility of contamination with impurities.

When using a cranking cell, the number of heated high-temperature parts increases compared to when using a K-cell, so problems such as the difficulty of maintaining an ultra-high vacuum and the possibility of contamination by impurities become more prominent. . Another problem is that the structure of the cell becomes complicated, which tends to cause equipment trouble.

Furthermore, when a gas source is used, there is a risk of toxic gas, and countermeasures against this pose a problem.

The object of the present invention is to be able to obtain a thin film of a high-quality ■-V group compound semiconductor using a solid material, and to avoid the difficulty of maintaining an ultra-high vacuum in the growth chamber and the extremely high possibility of contamination by impurities. The object of the present invention is to provide a thin film manufacturing apparatus with a small number of devices.

Means for Solving the Problems> The configuration for achieving the above objects will be explained with reference to FIG. 1 corresponding to the embodiment. In the present invention, a vacuum chamber (growth chamber) in which a thin film is to be grown A support (target holder) 5 for supporting a solid target 4 of at least one of As and P is provided inside the chamber 1, and a support body (target holder) 5 is provided outside the chamber 1 through a window 1a formed in the chamber 1. A laser device 6 is provided to irradiate a solid target 4 on a support 5 with pulsed laser light. The solid target 4 is sputtered by irradiation with this laser light, and a molecular beam or atomic beam of at least one of As and P is generated.

When a metal material is focused and irradiated with short-pulse laser light with high pulse energy, the irradiated area is rapidly locally heated to a very high temperature, causing evaporation (
Most of the sputtered particles are atomic.

Here, the heated part is a local part on the raw material, and there is no need for a constant heating part in the chamber 1, so that less impurities are generated and the initial purpose can be achieved.

<Example> FIG. 1 shows the constituent countries of the embodiment of the present invention.

The growth chamber 1 is a chamber that is connected to a vacuum pump (not shown) and is capable of maintaining an ultra-high vacuum, and inside thereof is a substrate holder 2 that has a heating function and is rotated.
K-cell 3 and shutter 3a, as well as solid target 4
A target holder 5 is provided to support the target.

This target holder 5 supports the target 4 within the growth chamber 1 at one end of a rotatable shaft, and the other end of the shaft extends outside the growth chamber 1 and is connected to a rotation drive mechanism (not shown). The target 4 is rotated while being supported.

A light-transmitting window 1a is attached to a part of the wall of the growth chamber 1, and a pulse laser device 6 and a laser beam condensing lens 7 are disposed outside the window 1a.

The pulsed laser beam from the pulsed laser device 6 passes through the laser beam focusing lens 7 and is focused onto the target 4 supported by the target holder 5 through the window 1a.

When producing a GaAs thin film using the above-described embodiment of the present invention, Ga is housed in one cell 3 and heated to obtain a molecular beam as in the conventional MBE apparatus, and as for As, a molecular beam is obtained. A metal As is mounted on a target holder 5 as a target 4, and a pulsed laser beam from a pulsed laser device 6 is condensed and irradiated onto its surface while giving rotation to the target. As a result, the metal As is locally and rapidly heated to a very high temperature (of the order of several ions) in the irradiated area, and is sputtered. Most of the particles generated by this pulsed laser sputtering are atomic,
Most of the remaining molecules become diatomic molecules, and almost no tetraatomic molecules are produced.

FIG. 2 is a graph showing the results of mass spectrometry of a product sputtered by irradiating metal A3 with pulsed laser light. In this example, excimer laser light was focused and irradiated onto the surface of metal As through a lens, and it was proven that most of As was decomposed into atoms.

From the above, the As molecular beam, which is mainly composed of atoms generated by laser sputtering, is guided to the surface of the substrate S on the substrate holder 2, and high-quality G
a As crystals are produced.

Note that the direction of the molecular beam (evaporated material) emitted from the target 4 by laser beam irradiation is the perpendicular direction of the target, so the position or attitude of the target 4 should be determined with this in mind. preferable.

Further, as the pulse laser device 6, it is desirable that the pulse laser device 6 has a large pulse energy and can obtain light with a short pulse width.
For example, Pulse CO! A laser, YAG laser, or excimer laser is suitable.

In particular, excimer lasers are thought to be the most suitable because they can provide ultraviolet light with high photon energy and can be expected to cause decomposition due to photochemical effects in addition to thermal effects.

Furthermore, in addition to the configuration of the above embodiment, an ion selector may be provided in front of the target 4 to guide only desired particles from the sputtered particles from the target 4 to the substrate 2. Can be done.

FIG. 3 shows an example of this, in which an ion selector consisting of a deflection plate 10 is provided in front of the metal As target 4, and by adjusting the voltage applied to the deflection plate 10, for example, only As ions can be removed. Alternatively, the configuration is such that only A s z '' ions are selected and guided to the substrate 2 .

In the configuration shown in FIG. 3, A s H” and A S g ”
is effective when the speed immediately after sputtering by the laser beam is the same, that is, when the initial energy is different, and it takes advantage of the difference in the deflection direction due to the difference in mass of the two, but when the energy immediately after sputtering is the same ( If the initial velocity of the dust is different, a so-called magnetic field type mass separator may be used.

By providing such an ion selector, it becomes possible to selectively guide only particles from which better crystals can be obtained to the substrate S, and a thin film of higher quality can be manufactured.

The above also applies to P, and by irradiating a P solid target with focused pulsed laser light, most of the particles generated are decomposed into atomic particles.
■-
A Group V semiconductor thin film is produced.

Therefore, by using an alloy of As and P as the target 4 and providing an ion selector as shown in FIG. 3, it becomes possible to selectively introduce Asl' or Pl' to the substrate.

Regarding molecular beams of group Ⅰ elements, there is no effect on the quality of the thin film because laser sputtering is used, but it goes without saying that laser sputtering can be used for these as well, and a steady heat source from within the growth chamber can be used. The effect can be expected in terms of eliminating impurities and reducing the production of impurities.

Furthermore, although pulsed laser light is preferable as the laser light irradiated to the target, similar effects can be expected by using a normal laser device instead of the pulsed laser device and chipping the output light.

Furthermore, if the substrate S is irradiated with laser light at the same time as the target 4 is irradiated with laser light, migration is promoted and higher quality crystals can be produced at lower temperatures.

Further, it goes without saying that the target holder 5 does not necessarily need to be rotatable, and the irradiated laser beam side may be moved as appropriate and the target side may be fixed.

<Effects of the Invention> As explained above, according to the present invention, when producing a ■-■ group compound semiconductor by the MBE method, As or P
Or both of the molecular beams are generated by the laser spacing method, so atomic species can be generated, and higher quality crystals can be obtained than in the case of using a conventional Niichi cell or graphing cell.

Further, it is possible to eliminate the need for a constant heating section in the growth chamber, making it easier to obtain an ultra-high vacuum, and reducing the influence of impurities. At the same time, since the excitation source is located outside the growth chamber, troubles related to the evaporation source are reduced, and an improvement in the operating rate of the apparatus can be expected.

Furthermore, the molecular dose can be controlled by controlling the number of pulses of the pulsed laser beam, which eliminates the need for a shutter mechanism just before the cell that is required when using a normal cell, and also makes it possible to control the number of pulses. is accurate and easy, so
There is also the advantage that the controllability of the molecular dose is improved, and the controllability of the film thickness and composition is also improved.

Furthermore, if an ion selector is installed in front of the target, it becomes possible to select the molecular beam type, obtain higher quality crystals, and easily examine the effect of the molecular beam type on film formation. There is also the effect that it can be done.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of the vicinity of the growth chamber in an embodiment of the present invention, Fig. 2 is a graph showing the mass spectrometry results of particles generated by pulsed laser sputtering, and Fig. 3 is a main part of another embodiment of the present invention. FIG. 1...Growth chamber 1a...Window 2...Substrate holder 3...K-cell 3a...Shack 4...Target 5...Target holder 6° ... Pulse laser device 7 ... Laser beam focusing lens 10 ... Deflection plate S ... Substrate

Claims (1)

[Claims] A thin film of a III-V compound semiconductor is grown on the substrate surface by irradiating the surface of the substrate placed in a vacuum chamber with a molecular beam of a group III element and a molecular beam of at least one of As and P. In the apparatus, a support for supporting a solid target of at least one of As and P is provided in the chamber, and
A laser device is installed outside the chamber to irradiate the target on the support with pulsed laser light through a window formed in the chamber, and the solid target is sputtered by irradiation with the laser light. III-V characterized in that it is configured to generate a molecular beam or atomic beam of at least one of As and P.
Group compound semiconductor thin film manufacturing equipment.