JPS6047238B2 - crystal growth method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion beam crystal growth method, and more particularly to a method for forming a single crystal thin film having a two-dimensional pattern.

The ion beam crystal growth method uses one or more ion guns under a high vacuum of 10-orr or less to generate one or more types of ion beams, and these ion beams are used to grow heated single crystals. This is a method of forming a single crystal thin film of a semiconductor on the surface of a single crystal substrate by irradiating the surface of the substrate with the elements constituting each ion beam as constituent elements or impurity elements.

Therefore, in the ion beam crystal growth method, the number of ions reaching the substrate during crystal growth can be accurately measured in the form of ion current and controlled purely electronically.
Compared to the vacuum evaporation method or the molecular beam crystal growth method, the control accuracy of the thickness, impurity distribution, or composition ratio of a single crystal semiconductor thin film is extremely high. Furthermore, since the energy of the ions reaching the substrate is obtained by electrical acceleration, it is compared to the thermally obtained energy of atoms or molecules reaching the substrate in vacuum evaporation or molecular beam crystal growth. With two axes, the size is several hundred centimeters. Most of the energy is converted into heat once the ions reach the substrate. Therefore, in the ion beam crystal growth method, the substrate temperature required for forming a semiconductor single crystal thin film on a single crystal substrate can be lowered compared to the vacuum evaporation method or the molecular beam crystal growth method. This is especially true for compound semiconductor MIS (Metal-Insulators).
It has an important meaning in that it becomes possible to prevent the generation of metamorphic layers in the creation of r-semiconductor structures. On the other hand, regarding the formation of a semiconductor single crystal thin film having a two-dimensional pattern, the conventional ion beam crystal growth method is no different from the vacuum evaporation method or the molecular beam crystal growth method.

In other words, an ion beam is irradiated through a metal mask that is close to or in close contact with the surface of a single crystal substrate, or a semiconductor single crystal thin film is once formed over the entire surface of the substrate, and then it is physically or chemically irradiated outside the growth apparatus. The method used was etching. however,
It is extremely difficult to obtain a two-dimensional pattern with independent regions using a metal mask, and the process using physical and chemical etching outside the growth apparatus is long and complicated. There was a problem.
By the way, since the ion beam is a charged particle beam, it can be focused and scanned like an electron beam.

In addition, the interaction between ions and the solid surface is such that when the energy of the ions is low, (1) the ions attach to the solid surface, and when the energy is high, (Ii) the ions sputter on the solid surface. There are two cases. The ion energy threshold that separates these two cases is determined by the ion species and the type of solid material. An object of the present invention is to provide an improved crystal growth method that eliminates the above-mentioned difficulties of conventional ion beam crystal growth methods by utilizing the above-mentioned characteristics of the ion beam.

According to the present invention, one or more types of ion beams are focused and scanned over the surface of a single crystal substrate, and at the same time, the accelerating voltage of the one or more types of ion beams is temporarily adjusted in synchronization with the ion beam scanning pulse. By increasing the voltage to a level sufficient to sputter the crystal substrate, grooves with an arbitrary two-dimensional pattern are formed on the surface of the single crystal substrate, and at the same time, a semiconductor single crystal thin film is formed on the portions of the surface of the single crystal substrate where grooves are not formed. A crystal growth method characterized by forming .

The present invention will be explained in detail below using GaAs as an example! do.

FIGS. 1A, 1B, and 1C are illustrated to explain one embodiment of the present invention. The As+ ion beam passes through the focusing electrode and the scanning electrode, and uniformly irradiates the entire surface of the single-crystal GaAs substrate.
s Scan the substrate surface. Same figure a! This is a diagram showing the relationship between the horizontal scanning voltage, vertical scanning voltage, and accelerating voltage of a 1Ga+ ion beam, and the horizontal scanning pulse period is 32.55μ.
s TV whose vertical scanning pulse period is 16.67TLs (
7) Scanning is performed in the same way as the NTSC system. Also Ga
The threshold of Ga + ion energy for sputtering single crystal GaAs with + ion beam is approximately 20 ('V).
However, the sputtering rate is significantly lower than 0 for ion beam crystal growth.
．． In order to obtain 01p1hr or more, the acceleration voltage of the Ga+ ion beam must be 500V or more. Therefore, the acceleration voltage during GaAs growth is set at 10V, and the acceleration voltage during substrate sputtering is set at 500V. Figure b shows single-crystal GaA grown on a single-crystal GaAs substrate 1 with the Ga+ ion beam acceleration voltage shown in figure a.
2 shows a thin film 2 and a sputter-etched portion 3. The width of the sputter-etched portion 3 is limited (the upper limit is limited by the time the accelerating voltage is 500 V, and the lower limit is limited by the diameter of the Ga + ion beam). Also, figure c is the same figure b.
2 is a cross-sectional view of the A-A″ portion shown in FIG.
Here, the scanning area of the Ga+ ion beam is 1cm x 1C
77! , the horizontal scanning pulse period is 32.55μ
s, the diameter of the focused Ga+ ion beam on the surface of the single crystal GaAsl must be 19.5 μm or more in order for the grown single crystal GaAs thin film 2 to have a uniform thickness.

Therefore, the width of the sputter-etched portion 3 is also 19.5
It becomes more than μm. The width of the sputter-etched part 3 is set to 1
In order to make the thickness of the single crystal GaAs thin film 2 μm, the diameter of the focused Ga+ ion beam on the single crystal QaAsl surface must be at most 1 μm. Horizontal scanning pulse period is 1
．． It must be less than 6 μs. Note that if the interlaced scanning method is also used, even if the horizontal scanning pulse period is doubled or the diameter of the Ga+ ion beam is increased to 1:2, the uniformity of the thickness of the grown single-crystal GaAs thin film will be lost. I can't get used to it. FIGS. 2A, b, and c are diagrams for explaining a second embodiment of the present invention.

As in the first embodiment, the As+ ion beam uniformly irradiates the entire surface of the single-crystal GaAs substrate, and only the Ga+ ion beam is focused and scans the surface of the single-crystal GaAs substrate. In addition, the horizontal scanning pulse period and the vertical pulse period are the same as those in the first embodiment, but the acceleration voltage pulse of the Ga + ion beam is Growth is accomplished by varying the phase and number of synchronization pulses for each. Figure b shows a GaAs single-crystal thin film obtained in this example, where 1 is a single-crystal GaAs substrate, 2
3 shows the grown single-crystal GaAs thin film, and 3 shows the sputter-etched part. In addition, Figure c shows a cross-sectional view of the section B-B'' shown in Figure b.As explained above, by using the present invention, it is possible to form a two-dimensional pattern on a single crystal substrate. To electrically easily form a single crystal semiconductor thin film by controlling the heating voltage of ions without using a metal mask or performing physical or chemical etching outside a crystal growth apparatus. I can do it.

In the above explanation, the ion species were limited to Ga+ ions and As+ ions, and the single crystal substrate was limited to GaAs.
It is not necessary to limit the material to the above materials. For example, ion species include S1+ ions, Sn+ ions, In+ ions and P+ ions, or Cd+ ions and Te+ ions, and single crystal substrates include Si, . Exactly the same effect can be obtained even if the present invention is implemented using Gel NP or the like.

[Brief explanation of drawings]

FIGS. 1A, b, and c are diagrams for explaining one embodiment of the present invention.

Claims (1)

[Claims] 1. Generate one or more types of ion beams using one or more ion guns, and irradiate these ion beams onto the surface of a heated single crystal substrate to extract elements constituting each ion beam. In the ion beam crystal growth method for forming a single crystal thin film of a semiconductor on the surface of a single crystal substrate, one or more types of ion beams are focused and scanned over the surface of the single crystal substrate, and at the same time the one or more types of ion beams are scanned over the surface of the single crystal substrate. Grooves with arbitrary two-dimensional patterns can be formed on the surface of a single crystal substrate by increasing the acceleration voltage of multiple types of ion beams to a voltage sufficient to temporarily sputter the single crystal substrate in synchronization with the ion beam scanning pulse. A crystal growth method characterized by forming a semiconductor single-crystal thin film on a portion of a single-crystal substrate surface where grooves are not formed at the same time as the formation.