JP3702005B2 - Gas phase excitation device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a gas phase excitation apparatus that excites a raw material gas with high efficiency in thin film crystal growth from a gas phase to reduce a crystal growth temperature, increase a crystal growth rate, and improve crystallinity.
[0002]
[Prior art]
In order to obtain a thin film with good crystallinity at a low temperature and at a crystal growth rate as high as possible, the excitation of the source gas in the vapor phase growth method has been conventionally performed by various methods.
By the way, most of them, as shown in the longitudinal sectional view of FIG. 2, light from a laser or the like from a direction orthogonal to a nozzle 03 for ejecting a gas in a high vacuum (<10 ⁻⁸ Torr) with a molecular beam. 04 is focused by a lens or the like to perform excitation at one point.
[0003]
[Problems to be solved by the invention]
However, in this one-point excitation, the excitation area must be made small because of the necessity of narrowing down the light, and if the collision cross-section between the gas molecule and the light is not so large, efficient excitation can be performed. I can't do it.
Furthermore, since the gas flow axis and the light axis are separate, a great deal of labor is required for alignment in order to optimize the excitation condition and maintain it with good reproducibility.
[0004]
The present invention has been proposed in view of such circumstances, and an object of the present invention is to provide a gas phase excitation apparatus that enables simple and efficient excitation of a gas molecular beam.
[0005]
[Means for Solving the Problems]
To achieve the above object, the gas-phase excitation device of the present invention, the vacuum container and, light or a gas phase excitation light source for generating a charged particle beam, said optical or charged particle beam from the gas phase excitation light source a radiation tube for introducing into said vacuum vessel, comprising a raw material gas introduction pipe connected to the irradiating tube, in the irradiation tube, exhaust between the gas phase excitation light source and a connecting portion of the source gas inlet pipe It is characterized by comprising means .
[0006]
[Action]
In general, when one high-speed particle passes through a gas having a molecular density n, the probability P that the particle collides with the gas molecule and is excited is proportional to n and the passage distance L of the high-speed particle. It becomes.
P = σ _e nL (1)
Here, σ _e is an amount called the collision cross section of excitation, and depends on the type of molecule and the energy of the fast particles. Therefore, assuming a system in which σ _e and n are constant, the excitation probability depends only on the passing distance, so it is clear that the coaxial arrangement used in the present invention provides the maximum excitation effect when introducing gas. .
That is, when light or a charged particle beam is irradiated along the introduction direction of the source gas, the gas molecules are dissociated by the excitation source and excited in energy. The source gas introduction tube is connected to a vapor phase excitation light source and connected to a vacuum vessel, whereby the source gas is introduced into the vessel as an inner molecular beam of collision between molecules with uniform flow.
At this time, the light source operates stably without deteriorating the light emission characteristics by causing the source gas to flow backward to the light emission source by the differential exhaust system provided in the vapor phase excitation light source.
[0007]
【Example】
First, the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall longitudinal sectional view thereof.
The figure shows a reactor for introducing Si ₂ H ₆ as a gas molecular beam source to form an S ₁ thin film, wherein 1 is a growth for growing a thin film on a substrate 2 supported by support means (not shown). It is an apparatus, and comprises a vacuum vessel 13 provided with exhaust means (not shown). Reference numeral 4 denotes a vapor phase excitation light irradiation tube penetratingly connected to the growth apparatus 1. One end is connected to the growth apparatus 1 and the other end is connected to a discharge chamber 7 as a vapor phase excitation light source .
In the discharge chamber 7, a rare gas introduction tube 8 for introducing a rare gas such as pressure-adjusted Xe, Ar, and He, and a discharge electrode 11 for applying a discharge voltage are provided, and a gas phase excitation light source is provided. Is configured.
[0008]
In such an apparatus, light emitted by applying a predetermined discharge voltage passes through the connection position of the first-stage and second-stage differential exhaust means 9, 10, and then is applied to the substrate 2 from the gas ejection nozzle 3. Irradiated.
That is, the light is in alignment structure from the light emitting portion to the substrate 2 of the discharge chamber 7, by crossing the inlet of the raw material gas introduction pipe 5 in the middle of the inlet of light, of the gas flow axis And the optical axis can be arranged coaxially.
At this time, the gas introduced from the source gas introduction pipe 5 in the direction coaxial with the light is efficiently excited and then reaches the substrate 2 to become a growth source.
The excitation light can be changed according to the crystalline (single crystal, polycrystal, amorphous) desired to form a film of the rare gas.
At that time, the two-stage differential exhaust means 9 and 10 prevent the deterioration of the film quality due to the mixing of the rare gas into the reactor and the deterioration of the discharge characteristics due to the reverse diffusion of the raw material gas into the discharge chamber.
[0009]
Incidentally, in this first embodiment, when the substrate was grown at a substrate temperature of 600 ° C. and a source gas introduction pressure of 5 Torr, the same light (Xe: λ = 147 nm, 20 W) was irradiated perpendicularly to the gas flow axis. It was confirmed that a large growth rate was obtained and the crystallinity as a single crystal was maintained as compared with the case of the above.
[0010]
Next, a description will be given of a second embodiment of the present invention, in FIG. _{1, Si 2 H 6 + SiH} 4 / PH 3 and _{Si 2 H 6 + SiH 4 /} B a ₂ H ₆ gas mixture first embodiment the same excitation and Introduced from a molecular beam source.
In this second embodiment, crystal growth of the Si thin film is performed, and impurities (P, B) for making a semiconductor into the thin film are efficiently added to the thin film.
At this time, light having the most efficient energy with respect to the gas species to be added can be freely selected.
[0011]
In this second embodiment, the substrate was grown at a substrate temperature of 500 ° C. and a source gas introduction pressure of 5 Torr (PorB: 100 ppm), and the same light (Xe: 147 nm, 20 W) was irradiated perpendicularly to the gas flow axis. It was confirmed that a larger growth rate and added concentration were obtained than in the case of the above, and the crystallinity as a single crystal was maintained.
[0012]
【The invention's effect】
In the thin film crystal growth by the vapor phase, the present invention is arranged such that the flow axis of the raw material gas to be introduced and the axis of the light to be excited are coaxial, and the vapor phase excitation light source and the connection portion of the raw material introduction tube to the irradiation tube By connecting an evacuation means to the same irradiation tube, it was possible to improve the excitation efficiency of the gas phase and to obtain a good quality thin film crystal at a low temperature and a high speed.
[0013]
In short, according to the present invention, a vacuum container, a gas-phase excitation light source for generating light or charged particle beam, a radiation tube for introducing from the gas phase excitation light source to said light or charged particle beam into the vacuum vessel, comprising a source gas inlet pipe connected to the irradiating tube, in the irradiation tube, Ri by the fact that comprises an exhaust means between the gas phase excitation light source and a connecting portion of the raw material gas introduction pipe, a rare gas when growing the thin-film crystal, with Ru obtained addition concentration and a large deal of growth rate, a shall be maintained crystallinity as the single crystal, thereby the present invention is the extremely valuable industrial .
[Brief description of the drawings]
1 is a schematic longitudinal sectional view of the Si thin film growth apparatus used in real施例of the present invention.
FIG. 2 is a schematic longitudinal sectional view showing a conventional gas phase excitation apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Growth apparatus 2 Substrate 3 Gas ejection nozzle 4 Gas-phase excitation light irradiation tube 5 Raw material gas introduction tube 6 Excitation gas molecular beam 7 Discharge chamber 8 Noble gas introduction tube 9 First stage differential exhaust means 10 Second stage differential exhaust means 11 Discharge electrode 12 High voltage power supply 13 Vacuum vessel

Claims (1)

A vacuum chamber, and gas phase excitation light source for generating light or charged particle beam, a radiation tube for introducing from the gas phase excitation light source to said light or charged particle beam into the vacuum vessel, which is connected to the irradiation tube material A gas phase excitation apparatus comprising: a gas introduction pipe; and an evacuation unit provided between the gas phase excitation light source and a connecting portion of the source gas introduction pipe in the irradiation tube .

Images