JPH01244610A - Manufacture of semiconductor - Google Patents

Abstract

PURPOSE:To obtain ZnSe semiconductor crystals effectively doped with an acceptor in the molecular beam epitaxial process, by applying atomic or molecular ions of nitrogen, phosphorus or arsenic or molecular ions containing atoms of one of said elements to the surface of a substrate on which a semiconductor thin film is being formed, while applying electronic beams. CONSTITUTION:Highly pure Zn and Se as raw materials are charged separately in molecular beam sources 13 and 14. A substrate 17 whose surface has been cleaned is mounted on a substrate holder 15. Practically, the substrate is preferably formed of GaAs crystals having crystal lattice constants close to those of ZnAs. A vacuum vessel is evacuated to ultra-high vacuum and then the molecular beam sources are heated so that molecular beams with appropriate intensities can be obtained. The intensities of the Zn and Se molecular beams are set in a ratio of 1:1 for example. A shutter 18 is opened and crystal growth is initiated while a nitrogen ion beam 16a from an ion gun 16 and an electronic beam 20a from an electronic gun 20 are applied continuously to the substrate 17. Ion density on the surface of the substrate is selected such that a desired quantity of nitrogen is given to the substrate in a range of 1/100 and below of the intensity of the molecular beams incident on the substrate surface, or density of the deposited atoms.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing semiconductor materials used in light emitting elements such as light emitting diodes and laser diodes, and in particular to
The present invention relates to a method for producing a zinc selenide semiconductor or a zinc sulfide selenide semiconductor exhibiting type conductivity.

Conventional technology Zinc selenide (Zn5e), a ■-■ group compound semiconductor
), zinc sulfide selenide (Zn5Sa) is promising as a material constituting light-emitting elements such as light-emitting diodes and laser diodes in the blue region. However, this Zn
In general, it is difficult to obtain a crystal exhibiting p-type conduction for the 5e semiconductor and the ZnSSe semiconductor, and therefore a highly efficient pn junction light emitting device has not been realized. Conventionally, as an attempt to obtain a p-type Zn8e semiconductor, a method is known in which phosphorus (P) is added as an impurity to make the semiconductor p-type during the crystal growth process using the molecular beam Ebiki method (e.g., published by the Electronics Technology Research Institute). Business Report Vol. 48, No. 5, 6 (1988), 1), 39
1-403) o This is a method for processing Zn, Se and Zn in vacuum.
3P2 is heated and evaporated to form Z containing P on the substrate.
This is a method of forming a thin film of n5e crystal.

Problems to be Solved by the Invention However, in the conventional method as described above, the P attached to the substrate re-evaporates due to the high vapor pressure of P, making it impossible to add a sufficient amount of P. For this reason, it has been impossible to obtain a crystal exhibiting p-type conduction.

The present invention has been made in view of this point, and an object of the present invention is to provide a method for manufacturing a Zn5e semiconductor, a ZnSSe semiconductor, or the like exhibiting p-type conductivity by effectively adding impurities.

Means for Solving the Problems In order to solve the above problems, the present invention aims to solve the above problems by using atomic ions such as nitrogen 1) or phosphorus CP) or arsenic (S), molecular ions thereof, or This method irradiates the surface of a substrate on which a semiconductor thin film is being formed with ions of molecules containing any of the atoms and an electron beam.

Effect By the above means, ionized impurity atoms or molecules are added to the semiconductor with high reactivity, but at the same time, by irradiating the semiconductor surface with an electron beam, the semiconductor surface becomes electrically neutralized and the positively ionized impurities interact with each other. By preventing repulsion and re-evaporation, highly reactive ionized impurities can be efficiently added to semiconductors using an electron beam.

Example Below, an example of the present invention will be described. In this example, zinc selenide (Z
Let us consider the case of manufacturing a thin film crystal of nS·). 1st
As shown in the figure, the equipment used for manufacturing is basically the same as a conventional molecular beam epitaxy equipment. That is,
This is a type of vacuum evaporation apparatus in which a plurality of molecular beam sources (evaporation crucibles) 13, 14, a substrate support mechanism 16, etc. are provided in a vacuum container equipped with an ultra-high vacuum evacuation apparatus 11. In this embodiment, in addition to this, an ion gun 16 and an electron gun 2o capable of generating a nitrogen ion beam are provided.

Actual thin film crystal growth is performed in the following steps.

First, high-purity Zn and Ss as raw materials are loaded into separate molecular beam sources 13 and 14, respectively. Further, the substrate 17 whose surface has been cleaned is mounted on the substrate holder 16. The most desirable substrate material is Zn8 single crystal, but good quality and large Zn.
Since it is difficult to obtain n5e single crystal, Z
Gallium arsenide (GaAs) has a crystal lattice constant close to that of n8e.
) crystals are preferred.

Next, the vacuum container is evacuated to an ultra-high vacuum of about 10' Torr or less. Thereafter, each molecular beam source is heated to obtain an appropriate molecular beam intensity. The molecular beam intensity ratio of Zn and Ss is, for example, about 1:1.

(During this time, the substrate 17 is shielded from the molecular beam by the shutter 18.) Next, the substrate 17 is heated to about 600° C. to further clean the surface. Thereafter, the temperature of the substrate 17 is lowered to a temperature suitable for crystal growth. In this case, the temperature is, for example, 326°C. After that, the shutter 18 is opened to start crystal growth, and the ion gun 16 and the nitrogen ion beam 161L and the electron gun 20 continuously send the electron beam 20& to the substrate 17.
The direction is irradiated. The density of ions on the substrate surface is 1/1 of the molecular beam intensity incident on the substrate surface, that is, the density of evaporated atoms.
It is preferable to select the desired nitrogen addition amount within the range of 100 or less. If the ion density exceeds 1/100, the amount added will be excessive and crystallinity may deteriorate.

In the above method, since ionized impurity atoms or molecules can be electrically neutralized by electron beam irradiation, it is possible to prevent repulsion between impurities and efficiently add highly reactive impurities to a semiconductor. Note that the density of the electron beam on the substrate surface is preferably greater than the ion irradiation amount.

This is because if the electron beam irradiation amount is less than the ion irradiation amount, the positive charge of the ions will be excessive on the substrate surface, and the next incoming ion will be electrically repelled and re-evaporated.

Note that the nitrogen ions used in this example are nitrogen atom ions (
N+) or nitrogen molecular ion (12+). It may also be an ion of a molecule containing a nitrogen atom, such as ammonia (NHs), or a mixture of these ions.

Furthermore, not all of the incident beam needs to be ions; it is also possible for the incident beam to contain neutral particles.

Although the above-mentioned example is for producing nitrogen-doped Zn5e, the method of the present invention can be similarly applied to phosphorus and arsenic in addition to nitrogen as the impurity to be added, and in that case, the ions are simple ions. In addition, phosphine (PFi)
s ), arsine (mgH3) and the like molecular ions are used. In addition, the method of the present invention involves doping nitrogen, phosphorus, and arsenic by ionizing a zinc sulfide selenide (ZnSSe) semiconductor in which sulfur (S) is added to Zn5e in order to reduce the lattice mismatch between the GIL S substrate and Zn8e. The same applies to other cases.

Effects of the Invention As described above, according to the present invention, a Zn5e semiconductor crystal to which acceptor impurities are effectively added can be obtained, and p-type conduction, which has been difficult to achieve in the past, can be achieved. As a result, a highly efficient pn junction light emitting device can be realized, which is extremely useful in practice.

[Brief explanation of the drawing]

The figure is a schematic diagram of an apparatus used in an embodiment of the present invention. 11...Ultra-high vacuum exhaust equipment, 12...
Vacuum container, 13.14... Molecular beam source, 15...
...Substrate holder, 16...Ion gun, 17
... Board, 18 ... Shutter, 19.
...Zn5a thin film crystal, 20 ...electron gun.

Claims (3)

[Claims] (1) A method of manufacturing a semiconductor characterized by irradiating an electron beam onto the substrate while depositing the semiconductor on the substrate in vacuum while irradiating ions in which some or all of the raw materials are positively charged. Production method. (2) Using atomic or molecular ions of nitrogen, phosphorus, or arsenic as ions, and producing a zinc selenide semiconductor or sulfide selenide semiconductor incorporating nitrogen, phosphorus, or arsenic as an acceptor impurity by irradiating the ions with the ions. A method for manufacturing a semiconductor according to claim 1. (3) A method for manufacturing a semiconductor according to claim 1 or 2, in which the density of ions irradiated onto the substrate is 1/100 or less of the density of evaporated atoms incident on the substrate.