JPS642437Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an apparatus for growing an epitaxial layer on a substrate, and particularly relates to a molecular beam epitaxy apparatus.

[Conventional technology]

Generally, in the above-mentioned molecular beam epitaxy apparatus, an evaporation source unit equipped with a Knudsen cell or an electron gun is arranged to face the surface of a substrate on which epitaxial growth is to be performed, in order to heat and evaporate a sample for epitaxial growth. The evaporation source unit is surrounded by a liquid nitrogen cooling jacket or the like so as not to prevent the molecules evaporated by the evaporation source unit from being deposited on the substrate.

During epitaxial growth, the molecular beam of the sample evaporated and ejected by the evaporation source unit is deposited on the substrate surface located approximately 150 mm apart. In one growth, several types of samples are deposited on the substrate surface to a thickness of approximately 3 μm. Furthermore, the purity of each deposited substance is subject to strict limitations due to the characteristics of the produced film.
Approximately 0.01ppm is required. The biggest obstacle to maintaining this purity is that the sample deposited on surfaces other than the substrate surface peels off and falls into the Knudsen cell or electron gun, contaminating sample 7 as impurities. .

[Problem that the invention attempts to solve]

For this reason, conventional molecular beam epitaxy equipment
As shown in FIG. 2, an evaporation source unit including a Knudsen cell 3 and an electron gun 4 is placed at the bottom, and a substrate 1 is placed directly above the evaporation source unit with the growth film production surface facing downward. In this case, the sample 7 in the Knudsen cell 3 and the electron gun 4 described above
Contamination with impurities was unavoidable.

As a special case, there is a device in which an evaporation source unit including Knudsen cells 3 and 8 and a substrate 1 are disposed perpendicular to the direction of gravity, as shown in FIG. 3, in order to avoid contamination with impurities. in this case,
The amount of sample 7 charged into the Knudsen cells 3 and 8 becomes extremely small, and the frequency of opening the vacuum system to the atmosphere to charge sample 7 increases significantly, reducing work efficiency. Moreover, the amount of sample that is melted during evaporation is even more limited. Therefore,
In this type of arrangement, some Knudsen cells are equipped with a special lid on the outlet to prevent leakage, but this has not been very effective. Furthermore, depending on the sample to be evaporated, for example, in the case of Si, a Knudsen type cell cannot be used and an electron beam heating type evaporation source is required. In this case, the sample is placed on a mortar-shaped water-cooled hearth, and it is impossible to use it horizontally.

In addition, in FIGS. 2 and 3, 5 is a liquid nitrogen jacket, 2 is a substrate holding component, and 6 is a shutter.

Therefore, the present invention aims to achieve a positional relationship between the evaporation source unit and the substrate that compensates for the above-mentioned drawbacks of the vertically opposed type and the leftwardly opposed type.

According to the present invention, in order to heat and evaporate a sample for epitaxial growth, an evaporation source unit equipped with a Knudsen cell and an electron gun is disposed so as to face the surface of a substrate to be epitaxially grown, and the evaporation source unit The molecular beam epitaxy apparatus has a structure in which the periphery of the evaporation source unit is surrounded by a liquid nitrogen cooling jacket or the like so as not to hinder the deposition of molecules evaporated by the evaporation source unit onto the substrate, the evaporation source unit and the and a substrate, the evaporation source unit is positioned diagonally below the substrate, and the opposing directions are tilted at an angle of 30° to 50° with respect to the direction of gravity without destroying the mutual facing relationship. , and the evaporation source unit is arranged such that the acute angle between the direction in which the electron gun and the substrate face each other and the direction of gravity is smaller than the acute angle between the direction in which the Knudsen cell and the substrate face each other and the direction of gravity. A molecular beam epitaxy apparatus is obtained, which is characterized in that the molecular beam epitaxy apparatus is disposed within

〔Example〕

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

A molecular beam epitaxy apparatus according to an embodiment of the present invention has a Knudsen type cell 3 as shown in FIG.
Then, the evaporation source unit including the electron gun 4 and the substrate 1 are arranged such that the evaporation source unit is located diagonally below the substrate 1, so that the facing direction of each other is 45 degrees with respect to the direction of gravity without destroying the mutual facing relationship. The electron gun is arranged at an angle of ±15°, and the electron gun is arranged below the Knudsen cell. By doing this, 1. Evaporated matter that has come off from parts other than the board 1 surface, such as the board holding part 2, the shutter 6, and the vacuum chamber (not shown) surrounding the part shown in FIG. It is possible to effectively prevent impurities from falling into the Knudsen cell 3 and the electron gun 4 and mixing into the sample 7.

2 As shown in FIG. 3, the electron gun 4 and the substrate 1
The evaporation source unit is arranged in such a way that the acute angle formed between the opposing direction of the Knudsen cell 3 and the substrate 1 and the gravitational direction is smaller than the angle formed between the opposing direction of the Knudsen cell 3 and the substrate 1 and the gravitational direction. 3
By placing the electron gun 4 lower than
Even if the facing direction of the evaporation source unit and the substrate 1 is inclined at an angle of 45 degrees with respect to the direction of gravity, the facing direction of the substrate 1 and the electron gun 4 is substantially tilted with respect to the direction of gravity. In addition, since it can be tilted more gently than 45 degrees (30 degrees), approximately 70% of the amount of sample 7 fed into the Knudsen cell 3 and electron gun 4 can be secured at a tilt angle of 45 degrees.

3 When the above-mentioned inclination angle is larger than 70°, sample 7
The electron gun 4 cannot be used to heat and evaporate the sample 7, but if the above-mentioned inclination angle is set to 70 degrees or less, the amount of sample 7 to be prepared is somewhat limited. can be used.

Effects such as this can be obtained.

In addition, in FIG. 1, 5 is a liquid nitrogen cooling jacket.

[Effect of idea]

As explained above, according to the present invention, it is possible to effectively prevent impurities from entering the sample in the Knudsen cell or electron gun, it is possible to prepare a considerably large amount of sample, and the sample can be heated and evaporated. An electron gun can be used to do this.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the arrangement of a molecular beam epitaxy apparatus according to an embodiment of the present invention, and FIGS. 2 and 3 are sectional views showing the arrangement of a conventional molecular beam epitaxy apparatus. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Substrate holding part, 3...Knudsen type cell, 4...Electron gun, 5...Liquid nitrogen jacket, 6...Shutter, 7...Sample, 8...
Knudsen type cell with leakage prevention lid.

Claims (1)

[Scope of utility model registration request] In order to heat and evaporate the sample for epitaxial growth, an evaporation source unit equipped with a Knudsen cell and an electron gun is disposed so as to face the surface of the substrate to be epitaxially grown, and evaporation is performed by the evaporation source unit. The molecular beam epitaxy apparatus has a structure in which the periphery of the evaporation source unit is surrounded by a liquid nitrogen cooling jacket or the like so as not to hinder the deposition of molecules on the substrate, the evaporation source unit and the substrate are The source units are located diagonally below the board, so that they face each other in the direction of gravity without destroying their mutual facing relationship.
They are arranged at an angle of 30° to 50°, and the acute angle formed between the opposing direction of the electron gun and the substrate and the direction of gravity is the same as the angle between the opposing direction of the Knudsen type cell and the substrate and the gravitational direction. A molecular beam epitaxy apparatus characterized in that the evaporation source unit is arranged within the evaporation source unit so that the angle is smaller than the acute angle formed by the evaporation source unit.