JP3043103B2 - Crystal surface structure control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a surface structure of a crystal, and more particularly, to a method for controlling a terrace portion (flat portion) and a step portion (step portion) inevitably present on a crystal surface. It relates to a control method.

[0002]

2. Description of the Related Art In order to obtain ultra-small, ultra-high-speed, ultra-low-power semiconductor devices required by an advanced information society, researches on devices utilizing quantum mechanical phenomena have been conducted in various fields. I have. An example in which a quantum effect device is industrially applied is a two-dimensional effect of electrons typified by HEMT and the like. Atomic layer epitaxy (AtomicLayer Epit) with one atomic layer as a processing unit to realize good two-dimensional electrical conduction
axy) and Atomic Layer Etching
A technique of crystal growth and crystal removal by a method called “crystal growth” has been studied. In such an atomic layer epitaxy etching, the crystal surface serving as the substrate can be correctly reproduced and two-dimensional crystal growth and crystal removal can be performed, so that the control in the growth direction can be performed well. Also, for a substrate in which terraces and steps on the surface which are inevitably present even after surface polishing are unevenly distributed, the pattern of the terraces and steps is made periodic. It is also possible.

[0003]

When a semiconductor element is manufactured using a substrate whose surface has been polished, a wide terrace portion is required for correct operation of the device without generation of noise. However, the current technology of atomic layer epitaxy has a problem that a substrate having a sufficiently large terrace portion required for the device operation cannot be manufactured. As described above, in order to further reduce the order of electron conduction, atomic layer epitaxy alone is not sufficient, and it is necessary to control the terrace portion and the step portion at the atomic level.

The present invention has been made in view of such circumstances, and by irradiating light having spatial periodicity so as to coincide with a crystal axis, it is possible to obtain a terrace portion which is sufficiently wide for device operation. It is an object of the present invention to provide a crystal surface structure control method capable of obtaining a crystal having a desired surface structure.

[0005]

A crystal surface structure control method according to the present invention is a method for controlling the surface structure of a crystal, wherein the crystal is irradiated with light having spatial periodicity to control the surface structure. It is characterized by the following.

[0006]

According to the crystal surface structure control method of the present invention, the crystal surface is irradiated with light having a spatial periodicity, for example, light whose intensity or wavelength has a spatial periodicity to excite atoms on the surface. Let it. If atomic layer epitaxy is performed while the atoms on the surface are in an excited state, the migration reaction is promoted by the excited atoms, so that the terrace portion of the crystal surface is enlarged and the step portions are multiplexed.

[0007]

Embodiments of the present invention will be specifically described below.

FIG. 1 is a perspective view showing a change in the crystal surface when the method for controlling the crystal surface structure according to the present invention is used, and FIG.
FIG. 4 is a cross-sectional view showing a change in crystal surface of the same. FIG.
FIGS. 2A and 2A show the crystal substrate 1 after surface polishing. Terrace portions 11 and step portions 12 are unevenly distributed on the surface of crystal substrate 1 that has been subjected to surface polishing. Here, the step of the step portion 12 is equivalent to one molecular layer.
Atomic layer epitaxy etching is performed on such a crystal substrate 1. Then, as shown in FIG.
The terrace portions 11 and the step portions 12 are periodically distributed, and the size of each terrace portion 11 is made uniform. This homogenization is caused by a growth mechanism called step flow growth. When the deposited crystal is taken into a stable site (step) while migrating, the probability of being taken in the step portion is one less than that of the deposited crystal. This is an effect brought about by the difference from the probability of being taken into the step portion. At this time, the size of the terrace portion 11 to be equalized is limited by migration.

After irradiating the surface of the thus-formed crystal substrate 1 with light having a spatial periodicity as shown in FIG. 2C, atomic layer epitaxy is performed. Then, the atoms on the surface are excited, and there is no difference in the probability that the crystals deposited at several step portions 12 (every two positions in this embodiment) are taken in. As a result, FIGS. 1B and 2
As shown in (d), several adjacent (three in this embodiment)
Are multiplexed to form the terrace 11 having a large area.

As described above, it is possible to obtain a crystal substrate 1 having a terrace portion having a width necessary for device operation and a multiplex step portion that is periodically controlled.

Here, a specific example of light having spatial periodicity will be described. In the case where the characteristic indicating the spatial periodicity is the light intensity, periodic light is applied such that the intensity is highest at the center in one cycle, and becomes lower toward the periphery. In the case where the characteristic showing the spatial periodicity is the wavelength of light, periodic light is applied such that the wavelength is shortest at the center in one cycle and becomes longer toward the periphery.

Next, a simulation result of controlling the crystal surface structure will be described. FIG. 3 shows a cross section of a crystal substrate to be controlled. The step portion has a step of one molecular layer, and the terrace portion is not uniform in width. FIG. 4 shows a simulation result when 27 atomic layers were grown on such a crystal substrate by atomic layer epitaxy. The terrace portion and the step portion exist periodically, and the area of the terrace portion is uniform. In addition, after growing 10 atomic layers by atomic layer epitaxy on a crystal substrate having a surface structure as shown in FIG. FIG. 5 shows a simulation result when a 27 atomic layer was grown by atomic layer epitaxy after removing every other step portion. In this case, the area of the terrace portion is larger than in the case where the light having no spatial periodicity is not irradiated.

[0013]

As described above, in the present invention, since the crystal surface structure is controlled by irradiating light having spatial periodicity, a sufficiently wide terrace portion necessary for device operation is obtained on the crystal surface. As a result, a crystal substrate having a desired surface structure can be obtained, and a semiconductor element controlled at an atomic level can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a change in a crystal surface when a crystal surface structure control method according to the present invention is used.

FIG. 2 is a cross-sectional view showing a change in crystal surface when the crystal surface structure control method according to the present invention is used.

FIG. 3 is a cross-sectional view showing the surface of the crystal substrate after surface polishing.

FIG. 4 is a diagram showing a simulation result after atomic layer epitaxy growth.

FIG. 5 is a diagram showing a simulation result when the crystal surface structure control method according to the present invention is used.

[Explanation of symbols]

 1 Crystal substrate 11 Terrace section 12 Step section

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-2327 (JP, A) JP-A-2-258694 (JP, A) JP-A-4-213819 (JP, A) (58) Investigation Field (Int. Cl. ⁷ , DB name) C30B 1/00-35/00 H01L 21/26 H01L 29/06 H01L 21/302 H01L 21/461 CA (STN) WPI (DIALOG)

Claims (1)

(57) [Claims] 1. A method for controlling a surface structure of a crystal, comprising irradiating the crystal with only light having spatial periodicity to control the surface structure.