JPS63478A - Formation of thin film - Google Patents

Abstract

PURPOSE:To form a fine semiconductor wire, etc., with which a quantum effect is anticipated by supplying gaseous raw materials onto a substrate in a vacuum vessel, projecting soft X-rays of a specific wavelength having a spatial intensity distribution thereto to form the thin film selectively on the substrate. CONSTITUTION:The substrate 6 is fixed to the sample holder 1 in the vacuum vessel 2 and the substrate 6 is heated by a heater contained in the sample holder 1. The gaseous raw materials are supplied from gas cells 4, 5 onto the substrate 6 and at the same time, radiation light is projected thereto by using synchrotron radiation light. Monochromatic light, interference fringe or standing wave is utilized for said radiation light and the spatial intensity distribution is made to provide the soft X-rays having several - several 100Angstrom wavelength. The thin film-like material is thereby selectively grown and formed only in the place where the light intensity is higher than certain intensity. The fine semiconductor wire or fine metallic wire with which the quantum effect is anticipated is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial application field The present invention mainly relates to a method for forming thin films made of semiconductor materials or metal materials, and is particularly applicable to the production of thin semiconductor wires or thin metal wires that are expected to have quantum effects. It is about effective growth methods.

(b) Conventional technology As a method of forming a thin film material on a substrate, photo-excited CVD is used.
(chemical vapor deposition
tion) method has been developed (for example, applied physics cylinder 5
(See 2-Volume Tube 78 <1983> pages 5ba to 566). The effects expected from photoexcitation can be broadly classified into heating effects and induction of photochemical reactions. Most of the conventional methods utilize the former effect;
Applications are limited to increasing the area of substrates.

On the other hand, regarding the latter, lowering the process temperature and application to microelectronics can be considered.

In order to induce a photochemical reaction, ultraviolet VC or even shorter wavelength light is generally required. However, conventionally only mercury lamps and excimer lasers have been used as light sources in this area, and they have had problems with both wavelength and intensity.

(c) Problems to be Solved by the Invention In the photo-excited CVD method, light in the soft X-ray region is effective for K in order to enable low process temperatures and selective growth with extremely high spatial resolution. In this region, the wavelength ranges from a few to 1
00A, which is about the same as the de Broglie wavelength of electrons in a solid.

Therefore, if we can prepare a light source with high intensity in this wavelength range and develop a method and apparatus xt for introducing it into a photoexcitation reaction vessel, it would be possible to create semiconductor thin wires or thin metal wires with expected quantum effects for KF5. can do.

B) Means for Solving the Problems The present invention uses synchrotron radiation as a light source, supplies raw material gas onto a substrate placed in a vacuum container, and irradiates the synchrotron radiation to form a thin film material. It is something that forms. At that time, if the synchrotron radiation is made monochromatic and an intensity distribution is created using interference fringes or standing waves, selective growth will occur only in areas where the light intensity is stronger than a certain level. Synchrotron synchrotron radiation is white light ranging from visible to X-rays.
If soft X-rays around 0A are used, the spacing between the interference fringes will be several 1OA, making it possible to create thin P-conductor wires or planned NJ wires of the size of human beings, which are expected to produce quantum effects.

Note that similar effects can be obtained by using an X-ray laser as a light source, which is expected to be realized in the future.

(Analysis) In general, the energy of light in the soft x11j region can excite electrons in the inner shell levels of atoms or molecules, and chemical reactions can proceed even without thermal energy.

Gas molecules adsorbed on the substrate absorb light energy and become excited, causing reactions such as decomposition and the growth of a thin film.

On the other hand, in a place not exposed to light, the gas molecules once adsorbed dissociate again and no adhesion occurs. Note that light in the X-ray region with a shorter wavelength than soft X-rays is unsuitable because it passes through substances.

(f) Embodiments Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of the configuration of an apparatus for carrying out the entire invention. A sample holder (]) to which a substrate 16) is fixed is attached in a vacuum container (2), and a heater for heating the substrate (6) is built into the sample holder (li).

The vacuum container (2) is connected to a synchrotron radiation beam line, and an X-ray interferometer consisting of a well-known multilayer interferometer is placed along the way. However, in order to introduce fuel gas, gas conduits lv+41 and (6) are prepared. Note that the drawing number t31 is a liquid nitrogen sheroud.

An example of creating a gallium arsenide (GaAs) thin wire using this device will be described. The preparation conditions are as follows.

Substrate GaAs wafer (100) surface Non-doped, high resistance Substrate temperature Approximately 500℃ Gas introduced amount arsine (AsH8) Icc/mfn Trimethylgallium 0.2cc/min Degree of vacuum during growth 5
X 10-'To r r growth rate 0
．． 2μm/h light source synchrotron radiation 2.5GeV electron storage phosphorus multi-ensulator line synchrotron radiation wavelength 10-100A (variable, 1% band width) synchrotron radiation intensity number of photons 1014-1015 (at storage current 100mA) soft The X-rays reach the surface of the substrate (6) after being modulated by the εχ X-ray interferometer into a spatial intensity distribution consisting of a repeating pattern of intensity as shown in FIG. Therefore,
GaAs thin wires (7) are deposited on the surface of the substrate (6) only in areas exposed to soft X-ray irradiation with an intensity above a certain value.

If Jlil OA's soft X-rays are used, the repetition interval of the pattern in the above spatial intensity distribution will be the minimum, hence 1 OA, and the width of the GaAs thin line (7) will also be about the same. In addition, in order to obtain a larger width of GaAS thin wire, the late 100Ai
Soft X-rays with a wavelength of

Is the above semiconductor m? I mentioned the length of 12 of 8J1,
The invention also applies to the growth of thin metal wires. That is, example tl
d', If trimethylaluminum or trimethylaluminum is used as the anti-E gas, thin aluminum wires can be grown on sapphire, semiconductor, or other substrates in the same manner.

(g) Effects of the Invention Since the method of the present invention uses light in the soft xm@ region, finer selective growth is possible compared to conventional methods. Furthermore, depending on the substance, a non-equilibrium phase that cannot be generated by the thermal action of light may be formed due to the activation of aFIb.

[Brief explanation of the drawing]

FIG. 1 is a side view of an apparatus for carrying out the present invention, and FIG. 2 is a conceptual diagram of the production of semiconductor thin wires using interference fringes. +1)...sample holder, (2)...vacuum container,
(3)...Liquid nitrogen shroud, +41+51...
Gas cell, (6)...Substrate, (7)...GaAs
Thin line.

Claims (1)

[Claims] (1) In the photoexcitation CVD method, which is performed by supplying raw material gas onto the substrate in a vacuum container and simultaneously irradiating soft X-rays with a wavelength of several to several hundred angstroms, soft X-rays with a spatial intensity distribution are used. A thin film forming method characterized by performing selective growth.