KR0119281B1 - Nitrogen radical generator for nitrogen compound semiconductor manufacturing - Google Patents

Abstract

The present invention is a source for generating nitrogen radicals in ultra-high vacuum, in particular the formation of activated nitrogen radicals in the reaction and extracting the plasma by its own shape of the plasma chamber to increase the uniformity using ultrasonic waves, crystallinity and electrical properties when manufacturing a nitride compound semiconductor It relates to a nitrogen radical generating device that can improve the.

The present invention provides a nitrogen radical generator using molecular beam epitaxy equipment, comprising: a substrate capable of chemically bonding with charged nitrogen radicals to form a nitride semiconductor; A chamber having a conical structure such that plasma can be incident toward the substrate by a density difference; A magnet formed on an outer wall of the chamber to form a plasma; A needle valve for injecting nitrogen which is an inert gas into the chamber; A diffuser for diffusing nitrogen gas introduced from the needle valve into the chamber; Filaments for ionizing the diffused nitrogen gas; And an ultrasonic vibrator attached to the lower outer wall of the chamber to achieve a uniform distribution with the formed plasma.

Description

Nitrogen radical generator for nitrogen compound semiconductor manufacturing

1 is a view showing the structure of a conventional Kaufman type ion generating device.

2 is a schematic view showing the structure of the nitrogen radical generating device according to the present invention.

The present invention relates to a nitrogen radical generating device capable of producing a high quality nitride semiconductor thin film by generating nitrogen radicals capable of reacting well with a group III element as a source for generating nitrogen radicals in ultra-high vacuum.

In general, the compounds in Groups 3 and 5 and the compounds in Groups 2 and 6 on the periodic table exhibit the same semiconductor characteristics as the elements in Group 4.

These compounds are referred to as group III-V compound semiconductors and group II-VI compound semiconductors, and are used as optical devices and microwave devices because they have excellent light emission characteristics, light reception characteristics, and high speed compared with element semiconductors.

On the periodic table, among the compound semiconductors in which the elements in the same column are bonded, the inter-material properties from the top to the bottom of the bonded column are smaller in the band cap, the smaller the bonding force, and the lower the melting point.

On the other hand, the material in the left and right directions of the periodic table has a characteristic that the group II-VI compound semiconductor material outside the group III-V compound semiconductor bonded inward has a large band cap, a large bonding force, and a high melting point.

Accordingly, since the compound semiconductor has different electrical and optical properties depending on the amount and type of elements to be bonded, there is an advantage that the characteristics required by the system can be used to make the device using this diversity.

Among these compound semiconductors, a nitrogen compound semiconductor, which is a kind of group III-V compound semiconductor, is made by combining nitrogen of Group 5 and elements of Group 3.

In particular, gallium nitride (GaN) has a bandgap of direct transition type, so that laser light can be produced by using the laser diode.

Therefore, blue light-emitting diodes, which have the possibility of realizing among the three primary colors of light for displaying natural colors among light-emitting diodes or laser diodes, can also realize laser diodes, and thus are important materials having various application ranges.

Its manufacturing methods include molecular beam epitaxy (NBE), organometallic chemical vapor deposition (MOCVD) and liquid phase epitaxy (LPE).

Among them, the molecular beam epitaxy method is a method in which different elements are independently grown in ultra-high vacuum to make molecular beams or radicals and incident on a substrate.

The molecular beam generator of nitrogen for manufacturing nitrogen compound semiconductors using such molecular beam epitaxy equipment is still in the research stage.

1 schematically shows a Kaufman-type ion generating device, which is used to ionize an inert gas.

That is, the gas entering the gas inlet 1 is bombarded and ionized by the hot electrons from the heated filament 2, which in turn undergoes a circular motion by the magnetic field of the magnet 3 and with other heavy atoms, atoms and ions. The collision causes plasma to form in the chamber 4.

At this time, a charge such as ions to be extracted is applied to the cathode 5 to form a repulsive force, and an electric field in which an attractive force is applied to the grid 6 of the outlet portion extracts the ions 7.

A conventional ion and radical generating device having such a configuration requires a relatively large source when using a large area substrate with parallel acceleration by the grid 6, so that at least five or more sources are required to grow the compound semiconductor. As required, it is almost impossible to attach them to the growth apparatus geometrically so that only one to three or less sources are mounted and used only for the single purpose of etching or deposition.

That is, the conventional apparatus is inefficient because only one charged particle such as nitrogen can be extracted from the generated plasma.

In addition, the extraction and acceleration of ions has a disadvantage in that it is possible to use only a particle having only one charge, and it is very consumable depending on the ionization rate, and when the charged particles are extracted by the acceleration voltage and pass through the grad, the passing particles can There was a problem that the hole of the grid is impacted and the size is changed as it is used for a long time is impossible.

Therefore, the present invention has been made to solve such a conventional problem, the object is to extract the generated nitrogen plasma by its own shape of the chamber, by applying ultrasonic waves to increase the uniformity to produce a high quality nitrogen compound semiconductor It is to provide a nitrogen radical generating device.

In order to achieve the above object, the present invention provides a nitrogen radical generating device using a molecular beam epitaxy device, comprising: a substrate capable of chemically bonding with charged nitrogen radicals to form a nitride semiconductor; A chamber having a conical structure such that plasma can be incident toward the substrate by a density difference; A magnet formed on an outer wall of the chamber to form a plasma; A needle valve for injecting nitrogen which is an inert gas into the chamber; A diffuser for diffusing nitrogen gas introduced from the needle valve into the chamber; Filaments for ionizing the diffused nitrogen gas; And an ultrasonic vibrator attached to the lower outer wall of the chamber so that the formed plasma can achieve a uniform distribution.

According to the present invention, it is possible to produce a nitride compound semiconductor having high crystallinity and good electrical properties in the production of a nitride compound semiconductor by molecular beam epitaxy by generating high quality nitrogen radicals.

A characteristic of the nitrogen radical generating device of the present invention is to have a tantalum chamber shape capable of applying a conical high negative voltage, extract the plasma by its own shape, and increase the uniformity of the plasma extracted by the ultrasonic vibrator on the substrate. It is to improve the characteristics of the grown epitaxial layer.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 shows the structure of the nitrogen radical generating device according to the present invention. When the conical high negative voltage tantalum needle 14 is applied to a substrate and a high negative voltage is applied, the nitrogen gas controlled by the needle valve 11 is applied. After being introduced and diffused through the diffuser 19 into the chamber, it is ionized by a shock caused by the thermal electrons emitted from the heated filament 12, causing a circular motion in the magnetic field of the installed magnet 13, Ionized atoms and electrons combine to form a plasma.

Since the formed plasma exists in the conical chamber 14, there exists a density difference of its own and a flow by the density difference is formed and is incident toward the substrate.

At this time, by the ultrasonic vibrator 17 attached to the bottom outer wall of the chamber 14, the plasma has a uniform shape while having a form of a small wave.

Therefore, in the conventional gas radical generating device, only one charged particle can be extracted from the plasma generated in the chamber by applying a voltage to the grid, whereas in the present invention, the plasma itself, which is a mixture of neutral atoms, pruses, negatively charged particles, and electrons, is extracted. It is possible to inject nitrogen radicals into the substrate itself by the conical plasma chamber shape, it is possible to form a uniform distribution by using an ultrasonic vibrator.

In addition, since the conical chamber is adopted, the generator can be made small due to the diffusion of the extracted plasma, so that the generator can be made small.

As described above, according to the present invention, by using a conical charge chamber while forming nitrogen as an inert gas into an easy-to-react nitrogen radical, the plasma is extracted by the chamber's own form, and the ultrasonic wave is applied to increase the uniformity of the plasma. By diffusing the area, the generator can be made small, and the nitride semiconductor, which is difficult to grow, can be produced at a low temperature with a high quality thin film having good crystallinity and improved electrical characteristics.

Claims (1)

An apparatus for generating nitrogen radicals using molecular beam epitaxy equipment, comprising: a substrate capable of chemically bonding with charged nitrogen radicals to form a nitride semiconductor; A chamber having a conical structure such that plasma can be incident toward the substrate by a density difference; A magnet formed on an outer wall of the chamber to form a plasma; A needle valve for injecting nitrogen which is an inert gas into the chamber; A diffuser for diffusing nitrogen gas introduced from the needle valve into the chamber; Filaments for ionizing the diffused nitrogen gas; And an ultrasonic vibrator attached to the lower outer wall of the chamber so that the formed plasma can achieve a uniform distribution.