JPH0748477B2 - Semiconductor manufacturing equipment - Google Patents

Description

The present invention relates to a semiconductor manufacturing apparatus. More specifically, the present invention relates to a new semiconductor manufacturing apparatus using hydrogen plasma, which is useful for cleaning a semiconductor substrate, forming a semiconductor thin film, and the like.

(Conventional technology and its problems) With the remarkable development of Si semiconductor technology,
The technological progress of compound semiconductors such as GaAs and InP is rapid. This compound semiconductor is becoming more and more important as a light emitting device. It is expected that even higher performance devices will be realized in the future.

The production of such a compound semiconductor has been attempted by various methods and its practical application has been advanced. However, in order to further improve the performance, the stable oxide film remaining on the semiconductor substrate is removed, It is necessary to conserve the periodicity of the crystal lattice on the surface and combine a compound semiconductor composed of elements having different vapor pressures to continuously grow a so-called heterojunction.

However, at present, there is still no technically established technique effective for cleaning the substrate surface or solving the problems of thin film formation, and an apparatus therefor.

That is, for example, as a method of removing an oxide film on a silicon substrate, a heat treatment method at a high temperature of 900 ° C to 1000 ° C in a high vacuum is adopted. There is a problem that an element having a high pressure is released and the compound semiconductor is significantly deteriorated. Instead of this heat treatment method, it has been considered to perform etching with hydrogen plasma that enables low-temperature treatment, but the hydrogen plasma etching methods proposed so far cannot avoid substrate damage due to ion bombardment. .

On the other hand, in the growth of compound semiconductors, generally, the energy required for each process of decomposition of the feedstock, migration of surface-adhered molecules, and incorporation into the crystal lattice is applied by heating, so that it is optimal for the type of compound semiconductor. The combination of compound semiconductors having different growth temperatures and capable of forming a high-quality heterojunction is limited.

For this reason, beyond the limits of conventional technology, new means and devices for surface cleaning such as removal of the oxide film of the substrate, which is indispensable for high performance of compound semiconductors, and new means for thin film growth of high quality compound semiconductors have been developed. Realization was strongly desired.

The present invention has been made in view of the above circumstances, and for producing a high-performance semiconductor, without the drawbacks of the prior art, for cleaning the surface of a semiconductor substrate and forming a semiconductor thin film. It aims to provide a new means of.

(Means for Solving the Problems) As a solution to the above problems, the present invention introduces a hydrogen plasma chamber for generating hydrogen plasma and a beam from the hydrogen plasma generated in this plasma chamber 1 ×
It has a growth chamber for semiconductor manufacturing under a high vacuum of 10 ⁻³ to 1 × 10 ⁻⁵ Torr, and the growth chamber has a substrate holder facing a beam from hydrogen plasma and a front side of the substrate holder. A semiconductor manufacturing apparatus having an electrode for applying a voltage for generating an electric field orthogonal to the beam, which is disposed in a portion, wherein a beam from hydrogen plasma is generated by a hydrogen radical beam and a hydrogen ion beam by the electric field generated by the electrode. Beam, the hydrogen radical beam is at an angle substantially perpendicular to the growth surface of the substrate held by the substrate holder, and the hydrogen ion beam is about 10 ° from the horizontal plane to the growth surface of the substrate. Provided is a semiconductor manufacturing apparatus characterized in that irradiation is performed at a shallow angle, independently or simultaneously. Furthermore, the present invention is also characterized in that the above-mentioned high vacuum growth chamber is provided with an organic metal beam irradiation device for irradiating the substrate with an organic metal beam, facing the substrate holder.

(Operation) In the apparatus of the present invention as described above, the cleaning and cleaning of the surface of the semiconductor substrate and the formation of a high-performance thin film can be performed by irradiation with a hydrogen radical beam or a hydrogen ion beam without causing damage due to ion bombardment. It can be carried out. In order to avoid collisions between beam particles in the gas phase, the present invention introduces a beam from a hydrogen plasma into a high vacuum chamber whose pressure is kept below 10 ^-3 Torr so that the mean free path is kept above 10 cm. I am going to do it. The beam from the hydrogen plasma is separated into a hydrogen radical beam, a hydrogen ion beam, and an electron beam by applying an electric field through the electrodes. That is, in order to separate the hydrogen radical beam and the ion beam, an electrode parallel to the beam from the hydrogen plasma is provided, and a positive and negative voltage is applied to the electrode to generate an electric field orthogonal to the beam to separate the ion and the electron. Alternatively, the electron beam is removed by applying only a positive voltage. Of these, the hydrogen radical beam and the hydrogen ion beam are used in the apparatus of the present invention.

More specifically, the hydrogen radical beam is incident on the growth surface of the substrate at an angle substantially perpendicular to the growth surface. Also, the beam of hydrogen ions is made incident at a shallow angle of about 10 ° from the horizontal plane of the substrate growth surface.

In cleaning the substrate surface, the excitation energy of hydrogen radicals or the kinetic energy component of the hydrogen ion beam, which is mainly parallel to the growth surface, is used to gasify and remove the oxide film and organic residues on the substrate surface.

When irradiating with an organometallic beam, hydrogen plasma or hydrogen ions are reacted with the organometallic beam for forming a compound semiconductor on the surface of the semiconductor substrate. In this case, the excitation energy of hydrogen radicals or the kinetic energy of hydrogen ions enables epitaxial growth at low temperature. The organic group of the organometallic compound forming the organometallic beam is terminated with hydrogen and removed as a gas. According to this method, it is possible to avoid damage due to electron impact and hydrogen ions, and suppress the generation of defects in the grown semiconductor thin film.

(Example) The apparatus of the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 shows an example in which a hydrogen radical beam is used. Hydrogen (2) is introduced into the hydrogen plasma chamber (1) from the outside. Hydrogen converted into plasma in the plasma chamber (1) is introduced into the growth chamber (3) as a beam without collision between particles. At that time, a pair of electrodes (4) and (5) are arranged in parallel with this beam, and positive and negative voltages are applied to each of them. Hydrogen ions and electrons are removed to the electrode side by the orthogonal electric field with respect to the beam generated by the application of this voltage.

The hydrogen radical beam (6) is applied to the surface of the substrate (8) held by the substrate holder (7).

The spread of the hydrogen radical beam (6) is almost determined by the size of the inlet from the plasma chamber (1) and cannot be converged to increase the beam density. Therefore, from the viewpoint of effective use of the beam, the hydrogen radical beam (6) is almost not formed on the substrate surface. Irradiate vertically.

When the surface of a semiconductor before growth is irradiated with this hydrogen radical beam (6), the excitation energy of the radical combines hydrogen with oxygen in the surface oxide film to form H ₂ O, which is gasified and removed from the surface. At this time, the substrate, for example, 300 ℃
If heated to a temperature of about this level, the vapor pressure of H ₂ O on the surface of the substrate rises, vaporization becomes easier, and removal becomes easier. Further, in the case of a compound semiconductor such as GaAs, As is likely to escape due to the bond with hydrogen. Therefore, it is also effective to supply As at the time of cleaning the surface.

In the apparatus of FIG. 1, the hydrogen radical beam (6)
At the same time, when the substrate (8) is irradiated with the organometallic beam for forming the compound semiconductor through the irradiation device (9) provided in the growth chamber (3), both react on the surface of the substrate (8) and the excitation energy of hydrogen radicals. The organic components such as methyl group and ethyl group of the organometallic compound are separated by this, and hydrogen atoms are bonded to this to be gasified into methane, ethane, etc. and removed.

Atoms forming the compound semiconductor are taken into the crystal lattice to form a compound semiconductor thin film.

Most existing metallic materials can be used as the organometallic compound in the device of the present invention, and can be applied to the growth of a wide range of semiconductor materials.

Further, in this apparatus, it is also an important requirement to maintain the degree of vacuum at a high vacuum of 10 ^-3 Torr or less, preferably 10 ^-3 to 10 ^-5 Torr and avoid collision between particles. When collisions between particles occur, it is difficult to obtain a pure hydrogen radical beam by exchanging energy due to collisions between particles, even if an electric field is applied as shown in FIG.

FIG. 2 shows an example in which a hydrogen ion beam is used.

In this example as well, hydrogen turned into plasma in the plasma chamber (1) is introduced into the growth chamber (3) as a plasma beam without collision between particles. A pair of electrodes (4) and (5) are arranged in the path of the plasma beam, grounded on the wall surface of the growth chamber (3), and a positive voltage is applied to both electrodes. The electron beam is removed here.

By controlling the applied voltage, the hydrogen ion beam is converged and the traveling direction is changed appropriately. Since hydrogen ions are repelled by Coulomb force from the electrodes, it is also effective to provide a negatively applied ion extraction electrode (10).

In this way, the hydrogen ion beam (11) whose beam shape and beam density have been adjusted by controlling the applied voltage is 10 °.
The light is incident on the semiconductor surface at a shallow front and back angle.

For example, when the incident angle is 5 °, the kinetic energy of the ions is 99.6% and 8.7%, respectively, parallel to the semiconductor surface and perpendicular to the semiconductor surface, and the vertical kinetic energy components causing ion irradiation damage to the surface. Is reduced to 1/10.

Generally, the cohesive energy that stabilizes the crystal lattice is estimated to be 5eV to 10eV per atom in a diamond crystal, whereas the ion energy of the high frequency discharge plasma is distributed over several hundreds of eV, so that the ion irradiation The damage is great. In the electron cyclone resonance plasma (FCR plasma), the ion energy can be made as low as 20 eV, but it is still higher than the above-mentioned cohesive energy of crystals, and it is difficult to suppress the generation of crystal defects.

When the transfer of kinetic energy at the time of collision between the hydrogen ion beam and the atoms constituting the semiconductor is obtained by the Rutherford model, the kinetic energy of the incident hydrogen ion is
About 5 to 15% of Si, Ga, As, etc. will be given to these atoms. In the case of ECR plasma, this shows that the kinetic energy of hydrogen ions is about 1 eV ~ 3
It is lower than eV and the cohesive energy of the crystal lattice. However, in reality, the kinetic energy of the generated ions is distributed even on the higher energy side, so that it is difficult to precisely suppress the generation of defects.

However, as in the present invention, when incident at a shallow angle, the vertical kinetic energy component of the incident ions is 2e.
It can be made as low as V. Therefore, the energy component applied to the semiconductor constituent atoms can be sufficiently reduced to 0.1 eV to 0.3 eV, and the generation of defects can be completely suppressed.

In the apparatus of the present invention shown in FIG. 2, when the hydrogen ion beam is irradiated to the semiconductor surface before growth at an angle of about 10 ° from the horizontal plane, the kinetic energy of hydrogen ions parallel to the semiconductor surface. Depending on the component, hydrogen and oxygen in the surface oxide film combine to form H ₂ O, which is gasified and removed from the surface. Further, at this time, the semiconductor constituent atoms that have been bound to oxygen move on the surface by collision with hydrogen and obtain kinetic energy for being incorporated into the lattice position.

According to the above Rutherford model, when the incident energy of hydrogen ions is 20 eV, these atoms weakly bound to the semiconductor surface obtain a moving velocity of about 1 × 10 ⁵ cm / sec. Therefore, it is possible to move to a stable grid position.

Actually, the GaAs (001) crystal surface was irradiated with a hydrogen ion beam at temperatures of 400 ° C and 450 ° C to remove oxide films and clean the surface, and the atomic arrangement on the surface was observed by high-speed electron diffraction ( When evaluated by the RHEED method, the following was confirmed.

<1> When the hydrogen ions are irradiated perpendicularly to the crystal surface, the atomic arrangement on the substrate surface is disturbed, and disorder occurs at the atomic level to give damage.

<2> When hydrogen ions are irradiated at a shallow angle of 10 ° from the direction parallel to the crystal surface, a substantially flat surface is obtained at the atomic level.

Further, when an organometallic beam for forming a compound semiconductor is introduced together with hydrogen ions by the irradiation device (9), the compound semiconductor constituent atoms receive surface transfer energy due to collision with the ions. Therefore, the compound semiconductor constituent atoms are stably incorporated at the lattice position. To obtain a compound semiconductor thin film.

Both the apparatus shown in FIG. 1 and the apparatus shown in FIG. 2 enable epitaxial growth of a compound semiconductor at a low temperature.

It goes without saying that the device of the present invention can be variously modified in its specific embodiment.
1 and 2 only schematically show the basic structure.

The apparatus of FIGS. 1 and 2 may be the same, and the voltage application to the electrodes and the position of the substrate holder may be adjusted. Further, in order to use the hydrogen radical beam and the hydrogen ion beam together, for example, the third
It is also possible to make it like the example of a figure.

(Effects of the Invention) According to the present invention, it is possible to grow a compound semiconductor thin film at a low temperature without generating defects as described above. In addition, excellent effects can be achieved in cleaning the semiconductor substrate.

It is possible to improve the performance of semiconductors, especially compound semiconductors, and further improve the performance by forming a multilayer film.

[Brief description of drawings]

1, 2 and 3 are schematic views showing an example of the apparatus of the present invention. The numbers in the figure indicate the following. 1 ... Hydrogen plasma chamber, 2 ... Hydrogen gas, 3 ... Growth chamber, 4,5
... electrode, 7 ... substrate holder, 8 ... substrate, 9 ... organometallic irradiation device, 10 ... ion extraction electrode.

Claims (2)

[Claims] 1. A semiconductor production under high vacuum of 1 × 10 ⁻³ to 1 × 10 ⁻⁵ Torr in which a hydrogen plasma chamber for generating hydrogen plasma and a beam from the hydrogen plasma generated in this plasma chamber are introduced. And a substrate holder facing the beam from the hydrogen plasma, and a voltage applied to the substrate in the front part of the substrate holder for generating an orthogonal electric field with respect to the beam. A semiconductor manufacturing apparatus including an electrode for separating a beam from a hydrogen plasma into a hydrogen radical beam and a hydrogen ion beam by an electric field generated by the electrode, and the hydrogen radical beam being a substrate held by the substrate holder. Of the substrate, and the hydrogen ion beam has a shallow angle of about 10 ° from the horizontal plane with respect to the growth surface of the substrate, independently of each other, or The semiconductor manufacturing apparatus characterized by sometimes irradiated. 2. A hydrogen plasma chamber for generating hydrogen plasma, and semiconductor manufacturing under high vacuum of 1 × 10 ⁻³ to 1 × 10 ⁻⁵ Torr for introducing a beam from the hydrogen plasma generated in this plasma chamber. And a substrate holder facing the beam from the hydrogen plasma, and a voltage applied to the substrate in the front part of the substrate holder for generating an orthogonal electric field with respect to the beam. And an organic metal beam irradiation device facing the substrate holder, wherein a beam from hydrogen plasma is separated into a hydrogen radical beam and a hydrogen ion beam by an electric field generated by the electrode. The hydrogen radical beam is directed at an angle substantially perpendicular to the growth surface of the substrate held by the substrate holder, and the hydrogen ion beam is directed toward the growth surface of the substrate. At a shallow angle of about approximately 10 ° from the horizontal plane, each independently, or together are irradiated simultaneously hydrogen plasma semiconductor manufacturing apparatus characterized by organometallic beam is irradiated to the growth surface of the substrate.