JPH05343322A - Method of forming crystalline layer of compound semiconductor - Google Patents

Abstract

PURPOSE:To grow a heavily doped compound semiconductor layer, having a correspondingly high carrier concentration, on a semiconductor wafer. CONSTITUTION:A plasma 8 is produced from a source gas 15 alone or together with a reductive gas or inactive gas by microwave electron cyclotron resonance. The plasma is introduced over a semiconductor wafer 2-1 so that a solid impurity 2-2 may be excited. As a result, a crystalline compound semiconductor layer doped with the impurity is grown on the semiconductor wafer 2-1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound semiconductor crystal layer forming method for forming a compound semiconductor crystal layer into which impurities are introduced on a semiconductor substrate.

[0002]

2. Description of the Related Art Conventionally, C, Be, and Z as p-type impurities are formed on a semiconductor substrate by a molecular beam epitaxial method.
n, Mg, Sn as an n-type impurity, Ge, Ti,
InP, G in which high melting point impurities such as W have been introduced
Attempts have been made to form a compound semiconductor crystal layer made of aP, AlAs, InAs, a mixed crystal thereof, or the like.

[0003]

However, in the case of such a conventional compound semiconductor crystal layer forming method, since the compound semiconductor crystal layer in which impurities are introduced is formed by the molecular beam epitaxial method, it is formed now. Since the energy of particles of impurities to be introduced into the compound semiconductor crystal layer, which is being injected into the compound semiconductor crystal layer, is as low as 1 eV or less, the compound semiconductor crystal layer is high. It has a drawback that it has a certain limit to be formed as having an impurity concentration.

For example, G in which an impurity of C is introduced
When a compound semiconductor crystal layer made of aAs is formed, C which is to be incident on the GaAs crystal layer which is being formed
Since the incident energy of the particles is as low as 1 eV or less, the fact that C has a low thermal diffusivity is combined with the fact that C particles are incident on the GaAs crystal layer that is being formed. GaA being formed now
Since the lateral migration distance on the surface of the s crystal layer is small, GaA is being formed continuously.
There is a high probability that C particles incident on the s crystal layer will encounter a Ga lattice position already occupied by C on the surface of the GaAs crystal layer that is being formed,
For this reason, a precipitate of C is formed on the surface of the GaAs crystal layer being formed, or C is an As lattice position not occupied by C on the surface of the GaAs crystal layer being formed. Ga without reaching
Since it enters the lattice position and becomes a donor, Ga
The As crystal layer cannot be formed as one having a high C impurity concentration of 2 × 10 ¹⁹ cm ⁻³ or more,
It had the drawback.

Further, when an attempt is made to add impurities in a high concentration by the molecular beam epitaxial method, there is a drawback that the carrier concentration does not increase but rather decreases even if the amount is increased above a certain concentration. Taking the addition of carbon (C), which is an acceptor impurity and has a small thermal diffusion coefficient, to GaAs, the above decrease is observed at 2 × 10 ¹⁹ cm ⁻³ or more. The reason for this is that C does not enter the lattice position of As in the GaAs crystal, and the cause is that the method of adding C is by thermal evaporation in the conventional method, and the energy of flying C on the crystal surface is 1 Because it is less than an electron volt. That is, when the incident energy is as small as 1 electron volt or less, the lateral migration distance on the substrate surface is also small, so that the incident C was already occupied by C on the substrate surface as the addition amount was increased. The probability of encountering the Ga lattice position increases, so that a precipitate of C is formed, or the As lattice position not occupied by C reaches the Ga lattice position and becomes a donor.

Therefore, the present invention does not have the above-mentioned drawbacks.
It proposes a new compound semiconductor crystal layer forming method.

[0007]

In the method for forming a compound semiconductor crystal layer according to the first invention of the present application, a microwave electron cyclotron resonance plasma of a source gas of a compound semiconductor crystal layer to be formed is generated to generate the above-mentioned source gas. The microwave electron cyclotron resonance plasma is transported onto the semiconductor substrate, and a part of the microwave electron cyclotron resonance plasma of the raw material gas transported onto the semiconductor substrate excites impurities in a solid phase state. A compound semiconductor crystal layer having the impurities introduced therein is formed on the semiconductor substrate.

In the method for forming a compound semiconductor crystal layer according to the second aspect of the present invention, a microwave electron cyclotron resonance plasma of a reducing gas or an inert gas is generated, and a microwave electron cyclotron resonance of the reducing gas or the inert gas is generated. The source gas of the compound semiconductor crystal to be formed and the impurities in the solid state are excited by the plasma, so that the compound semiconductor crystal layer into which the impurities are introduced is formed on the semiconductor substrate.

The method for forming a compound semiconductor crystal layer according to the third invention of the present application is a microwave electron cyclotron resonance plasma of a source gas of a compound semiconductor crystal layer to be formed and a microwave electron cyclotron resonance of a reducing gas or an inert gas. Generate plasma, microwave electron cyclotron resonance plasma of the source gas and microwave electron cyclotron resonance plasma of the reducing gas or inert gas, while transporting on the semiconductor substrate,
The impurities in the solid phase are excited by the microwave electron cyclotron resonance plasma of the source gas and the microwave electron cyclotron resonance plasma of the reducing gas or the inert gas transported onto the semiconductor substrate, and thus the semiconductor A compound semiconductor crystal layer introduced with the above impurities is formed on a substrate.

More specifically, in the compound semiconductor crystal layer forming method according to the present invention, when a semiconductor thin film crystal is grown from a substance in a vapor phase state, the substance in the vapor phase state is excited by microwave electron cyclotron resonance plasma. In the method of performing crystal growth, the excited substance is transported onto a substrate crystal by a divergent magnetic field, and crystal growth is performed by adding an impurity onto the substrate crystal.

In this case, the excitation by the microwave electron cyclotron resonance plasma is applied to one or more gas phase substances selected from the group consisting of the constituent elements of the crystal to be grown and the reducing or inert element. Do it.
Further, the substance in the plasma state excited by the microwave electron cyclotron resonance excites the substance in the solid state containing the impurity element to be added.

[0012]

According to the compound semiconductor crystal layer forming method of the present invention, the microwave electron cyclotron resonance plasma of the source gas of the compound semiconductor crystal layer to be formed, or the microwave electron cyclotron of the reducing gas or the inert gas. Resonance plasma, or using microwave electron cyclotron resonance plasma of the source gas and microwave electron cyclotron resonance plasma of the reducing gas or inert gas, and by exciting the impurities in the solid state, the introduction of impurities Since the compound semiconductor crystal layer is formed, the energy of the particles of the impurities incident on the compound semiconductor crystal layer that is being formed is larger than that in the conventional compound semiconductor crystal layer forming method described above. The compound semiconductor crystal layer is so high as not to give damage, so that the compound semiconductor Crystal layer to have a higher impurity concentration than in the case of the conventional compound semiconductor crystal layer forming method as described above, yet, no good - can be easily formed as having no di.

More specifically, the present invention uses a combination of a microwave electron cyclotron resonance plasma source and a divergent magnetic field to combine ions of one or more semiconductor constituent elements or reducing or inactive elements with the substrate and solid phase. Crystals are grown on the substrate with a high concentration of impurities while being transported to an impurity substance to be added in a phase state and introducing or not introducing a gas containing another semiconductor constituent element into the substrate installation chamber.

That is, according to the present invention, low energy particles of several tens of electron volts can be transported to the substrate,
A crystal growth method for a compound semiconductor is provided, which is characterized in that it does not cause damage in the growth film, and that the crystal growth can be performed with energy sufficiently larger than that in the case of thermal equilibrium crystal growth.

In the method according to the present invention as described above, crystal growth is performed with energy sufficiently larger than thermal equilibrium, so that the migration distance of atoms on the substrate surface increases. As a result, a thin film with a high concentration of impurities, which is an effective carrier supply source, can be grown on the substrate, and since the energy is relatively small, a high-quality crystal free from damage can be obtained. ..

In the method of the present invention, the substance excited by microwave electron cyclotron resonance into a plasma state is at least one of a semiconductor constituent element used for growing a compound semiconductor crystal, a reducing gas or an inert gas.
Alternatively, a plurality of combinations or all of them may be excited by microwave electron cyclotron resonance. In the method of the present invention, other substances in the gas phase which are not excited by direct microwave electron cyclotron resonance are also interacted with the plasma and transported onto the substrate crystal.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows the outline of a manufacturing apparatus used in the present invention.

In FIG. 1a, reference numeral 1 denotes a growth chamber, inside of which a substrate crystal 2-1 is supported adjacent to a doping impurity solid substance 2-2. 3 is a connection port to an exhaust pump, 4 is a gas introduction port, 5 is a plasma shield plate, 6 is a solid material evaporation cell,
Reference numeral 7 is a cavity resonance type plasma generation chamber, 8 is plasma, 9 is a rectangular waveguide, 10 is a magnet, and 11 is a quartz window. As shown in FIG. 1b, the strength of the magnetic field is reduced from the cavity resonance type plasma generation chamber 7 toward the growth chamber 1, and as a result, plasma is diverged and extracted.

Next, examples of the growth method according to the present invention will be described.

Example 1 For a microwave electron cyclotron resonance plasma source, arsine (A) diluted with hydrogen (reducing) gas was used.
sH ³ ) was introduced and gallium atoms were added to the substrate installation room.
The metal gallium in the Dosen cell is supplied by evaporation to grow crystals. High-purity carbon was used as the impurity substance for addition. The growth conditions are as follows.

Growth conditions of the example: Arsine flow rate: 40 sccm Ga cell temperature: 900 ° C. Microwave frequency: 2.45 GHz Microwave power: 100 W Growth rate: 0.5 μm / h Growth time: 1 hour Substrate temperature: 500 ° C

FIG. 2 shows the carrier concentration of the GaAs growth layer doped with carbon as an impurity under the conditions of the above embodiment and the carbon atom in the film measured by secondary ion mass spectrometry. The relationship with the concentration is shown. The solid line shows the GaAs film grown according to the present invention, as shown in FIG.
As shown in, the proportional relationship is established up to 10 ²⁰ cm ^-3 . The dotted line in the drawing, there is shown a case grown by conventional molecular beam epitaxy for comparison 10 ¹⁹
When it becomes cm ^-3 or more, the carrier concentration becomes saturated, and then decreases even if the amount of addition is increased.

[0022]

[Embodiment 2] According to the method of the present invention, a p-type carbon-doped compound semiconductor crystal having a carrier concentration of about 10 ²⁰ cm ^-3 can be easily realized, so that a p-layer having a high concentration and a steep distribution is preferable. It is possible to obtain excellent pn junction diode characteristics. Fig. 3 shows that carbon is 10 ²⁰ cm ^-3 by the above method.
FIG. 3 is a diagram showing forward-direction and reverse-direction current-voltage characteristics of a pn junction diode having p-type GaAs formed by adding a high concentration of p-type GaAs. A rectification ratio of 5 digits or more can be obtained at a current of 1.0 V, and an n value is 1.1, and good diode characteristics can be obtained.

In the first and second embodiments described above, GaAs was used as the compound semiconductor to be grown, but InP,
In the case of compound semiconductor crystal growth such as GaP, AlAs, InAs and their mixed crystals, the same crystal growth as in the case of GaAs growth can be performed. Although the p-type impurity C is used as an impurity to be added, for example, other p-type impurities Be, Zn, Mg, and an n-type impurity S are used.
In the case of n, Ge, and titanium (Ti) and tungsten (W) which are refractory metals that are difficult to add only by a thermal reaction process, the same effect as in the case of adding C can be expected.

Further, the excitation by the microwave electron cyclotron resonance was performed on the gas containing the group V element,
For example, a gas containing a group III element, or a gas such as hydrogen or argon that hardly remains in the growth layer may be used. In the latter case, the growth film constituent elements are supplied by the same method as the conventional molecular beam epitaxial method.

In the above, arsine gas is H
It can be used after diluting with ² (reducing), Ar (inert) or He (inert) gas.

[0026]

As is apparent from the above description, according to the compound semiconductor crystal layer forming method of the present invention,

The action and effect described in the section [Action and effect] can be obtained.

Further, since the migration distance of the impurity particles reaching the surface of the substrate can be increased, the substantial sticking probability is increased and the impurities can be added at a high concentration, so that good pn junction characteristics can be obtained. it can. Further, in the method according to the present invention, since the energy of the particles is low, there is an advantage that a high quality crystal with few defects can be obtained.

In the method of the present invention, the characteristics of the growth method applying microwave electron plasma (appropriate energy
(Except that the particles having a) can be transported to the substrate), the following two items can be mentioned.

A high-purity film can be obtained because there is no source of contamination such as electrodes in the plasma generation chamber. The gas is efficiently ionized by using electron cyclotron resonance. Therefore, compared to other plasma methods, 2-3
It can be grown at pressures that are orders of magnitude lower and is less susceptible to impurities in the gas.

In the above description, only one embodiment of the present invention is shown, and

From [Example]

It will be apparent that the various modifications and changes described in the section "Means for Solving the Problems" can be made.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus that can be used for a compound semiconductor crystal layer forming method according to the present invention (FIG. 1a) and a distribution of its divergent magnetic field (FIG. 1b).

FIG. 2 is a diagram showing a relationship between a C atom concentration and a carrier concentration in a film of an impurity-doped compound semiconductor crystal obtained by an example of a compound semiconductor crystal layer forming method according to the present invention.

FIG. 3 is a diagram showing pn junction characteristics using a p-type high-concentration impurity-added compound semiconductor crystal formed by an example of a compound semiconductor crystal layer forming method according to the present invention.

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[Procedure amendment]

[Submission date] January 30, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Method for forming compound semiconductor crystal layer

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound semiconductor crystal layer forming method for forming a compound semiconductor crystal layer having impurities introduced on a semiconductor substrate.

[0002]

2. Description of the Related Art Conventionally, C, Be, Zn, Mg as p-type impurities and S as n-type impurities are formed on a semiconductor substrate.
n, Ge, and GaAs, InP, GaP, AlA into which impurities such as high melting point impurities such as Ti and W are introduced.
Various compound semiconductor crystal layer forming methods have been proposed in which a compound semiconductor crystal layer made of s, InAs, a mixed crystal thereof or the like is formed by a molecular beam epitaxial method.

[0003]

In the case of the conventional compound semiconductor crystal layer forming method in which the compound semiconductor crystal layer into which such impurities are introduced is formed by the molecular beam epitaxial method, the compound semiconductor crystal layer currently being formed is being formed. Since the energy of particles of impurities to be introduced into the compound semiconductor crystal layer to be incident on the inside is as low as 1 eV or less, the compound semiconductor crystal layer has a high impurity concentration. However, it also has a drawback that it has a certain limit in forming a film having a correspondingly high carrier concentration.

Now, in this regard, the compound semiconductor crystal layer to be formed is a GaAs crystal layer, and its G
Supposing that the impurity to be introduced into the aAs crystal layer is C as a p-type impurity, in the case of the conventional compound semiconductor crystal layer forming method by the molecular beam epitaxial growth method,
Since the energy of C particles that are incident on the GaAs crystal layer that is being formed is as low as 1 eV or less, in combination with the fact that C has a low thermal diffusion coefficient, GaAs being formed now
The migration distance in the lateral direction of the C particles incident on the crystal layer on the surface of the GaAs crystal layer that is being formed is small. Therefore, a C precipitate is formed on the surface of the GaAs crystal layer that is being formed, or C
On the surface of the GaAs crystal layer which is being formed, without reaching the lattice position of Ga which is not occupied by C, it enters the lattice position of As and acts as a donor. Therefore, GaA
The s crystal layer, 2 × ¹⁰ 19 ^{cm -3} have a more high impurity concentration, 2 × ¹⁰ 19 ^{cm -3} accordingly
It has a defect that it cannot be formed as one having the above high carrier concentration.

Therefore, the present invention does not have the above-mentioned drawbacks.
It proposes a new compound semiconductor crystal layer forming method.

[0006]

In the method for forming a compound semiconductor crystal layer according to the first invention of the present application, a microwave electron cyclotron resonance plasma of a source gas of a compound semiconductor crystal layer to be formed is generated to generate the above-mentioned source gas. The microwave electron cyclotron resonance plasma is transported onto the semiconductor substrate, and a part of the microwave electron cyclotron resonance plasma of the raw material gas excites impurities in a solid phase state. A compound semiconductor crystal layer having impurities introduced is formed.

In the method for forming a compound semiconductor crystal layer according to the second aspect of the present invention, a microwave electron cyclotron resonance plasma of a reducing gas or an inert gas is generated, and a microwave electron cyclotron resonance of the reducing gas or the inert gas is generated. Plasma is transported onto the semiconductor substrate, and by the microwave electron cyclotron resonance plasma of the reducing gas or inert gas transported onto the semiconductor substrate, the source gas of the compound semiconductor crystal to be formed and the solid state To excite the impurities present therein to form a compound semiconductor crystal layer into which the impurities are introduced on the semiconductor substrate.

The method for forming a compound semiconductor crystal layer according to the third aspect of the present invention is a microwave electron cyclotron resonance plasma of a source gas of a compound semiconductor crystal layer to be formed and a microwave electron cyclotron resonance of a reducing gas or an inert gas. Plasma and generate the microwave electron cyclotron resonance plasma of the raw material gas and the microwave electron cyclotron resonance plasma of the reducing gas or inert gas, while transporting on the semiconductor substrate, the microwave of the raw material gas Part of the electron cyclotron resonance plasma and part of the microwave electron cyclotron resonance plasma of the reducing gas or inert gas excite the impurities in the solid state, and thus, on the semiconductor substrate, Shape the compound semiconductor crystal layer that has been introduced Make.

[0009]

According to the method for forming a compound semiconductor crystal layer according to the present invention, (a) microwave electron cyclotron resonance plasma of the source gas of the compound semiconductor crystal layer to be formed, or (b) a reducing gas or an inert gas. Microwave electron cyclotron resonance plasma of gas, or (c)
A microwave electron cyclotron resonance plasma of the source gas and a microwave electron cyclotron resonance plasma of the reducing gas or the inert gas are used, and thereby, the impurities in the solid state are excited to introduce the impurities. Since the compound semiconductor crystal layer is formed as described above, the energy of the impurity particles entering the compound semiconductor crystal layer that is being formed is smaller than that in the conventional compound semiconductor crystal layer forming method described above. , So high as not to damage the compound semiconductor crystal layer, so that the impurities incident on the compound semiconductor crystal layer being formed are laterally distributed on the surface of the compound semiconductor crystal layer being formed. Migration distance is larger than that of the conventional compound semiconductor crystal layer forming method described above. Therefore, it is possible to avoid formation of precipitates of impurities on the surface of the compound semiconductor crystal layer that is being formed, and the particles of impurities can form a compound semiconductor crystal layer that is not occupied by impurity elements. Easily reach the lattice positions of the elements that are to be composed. Therefore, the compound semiconductor crystal layer has the same high impurity concentration as in the case of the conventional compound semiconductor crystal layer forming method described above, and has a higher carrier concentration than that in the case of the conventional compound semiconductor crystal layer forming method described above. And yet, as it has no damage,
It can be easily formed.

Further, according to the compound semiconductor crystal layer forming method according to the present invention described above, the electron cyclotron resonance plasma is generated by the source gas, and the compound semiconductor crystal layer is formed by using the electron cyclotron resonance plasma. As in the case of the conventional compound semiconductor crystal layer forming method in which plasma other than electron cyclotron resonance plasma is generated and the compound semiconductor crystal layer is formed using the plasma, an electrode that becomes a pollution source in the plasma generation chamber 7 Since it is possible to form the compound semiconductor crystal layer without using the source gas to generate plasma using the source gas, it is possible to easily form the compound semiconductor crystal layer having high purity.

Further, since the electron cyclotron resonance plasma is generated by the source gas and is used to form the compound semiconductor crystal layer, plasma other than the electron cyclotron resonance plasma is generated by the source gas,
Compared with the conventional method of forming a compound semiconductor crystal layer using the compound semiconductor crystal layer, plasma of the source gas can be efficiently obtained. Therefore, plasma other than electron cyclotron resonance plasma of the source gas can be obtained. 2 to 3 in comparison with a conventional compound semiconductor crystal layer forming method in which a compound semiconductor crystal layer is formed by using
The compound semiconductor crystal layer can be formed with a pressure in the plasma generation chamber and the crystal growth chamber that is as low as an order of magnitude. Therefore, the compound semiconductor crystal layer that is not affected by undesired impurities can be easily formed. ..

[0012]

EXAMPLES Next, examples of the compound semiconductor crystal layer forming method according to the present invention will be described with reference to FIG.

In the embodiment of the compound semiconductor crystal layer forming method according to the present invention shown in FIG. 1, a compound semiconductor crystal layer in which an impurity is introduced is formed on a semiconductor substrate by using a microwave electron cyclotron resonance plasma device. Let

Since the microwave electron cyclotron resonance plasma device is known per se, detailed description thereof will be omitted. (I) (a) The gas introducing pipe 4 from the outside is connected at one end side, and ( b) Square waveguide 9 from the outside
At the one end side where the gas introduction tube 4 is connected through a microwave introduction window 11 made of quartz, and (c) a plasma generation chamber in which the electromagnet 10 is arranged around 7), and (ii) (a) is connected to the plasma generation chamber 7 via the plasma drawing window 12 on the side where the gas introduction tube 4 is connected, and (b) a Knudsen cell. For evaporation of solid materials such as 6
Is disposed inside the plasma generating chamber 7 side, and (c) the plasma shielding plate 5 having the plasma extraction window 12 'is viewed from the solid material evaporation cell 6 and is not connected to the plasma extraction window 12 side. On the opposite side, the plasma extraction window 1
2 has a crystal growth chamber 1 which is disposed so as to oppose thereto and (d) the exhaust pipe 3 is connected on the side opposite to the plasma generation chamber 7 side. In this case, the electromagnet 10 has a magnetic field as seen through them in the plasma generation chamber 7 and the crystal growth chamber 1 from the center of the plasma generation chamber 7 to the crystal growth chamber 1 side, as shown in FIG. 1b. It is arranged around the plasma generation chamber 7 so as to exhibit a distribution that gradually weakens as the temperature reaches.

According to the microwave electron cyclotron resonance plasma device having such a configuration, (i) (a)
In the crystal growth chamber 1, on the side opposite to the plasma growth chamber 7 side when viewed from the plasma shielding plate 5, the substrate mounting table 13 is provided.
Is used to dispose the semiconductor substrate 2-1 and (b) the solid material evaporation cell 6 stores the solid material which is the first material for the compound semiconductor crystal layer, and (c) is used for evacuation. Using the tube 3, the crystal growth chamber 1 and the plasma growth chamber 7 are
A raw material configured to have a second material for a compound semiconductor crystal layer to be turned into plasma from the outside by using the gas introduction tube 4 in the plasma growth chamber 7 while evacuating from the outside. The gas 15 is introduced, and (d) the semiconductor substrate 2-1 is heated at this time, and the microwave 16 is externally supplied to the plasma growth chamber 7 by using the rectangular waveguide 9. Is introduced, the electromagnet 10 is energized, and the solid material evaporation cell 6 is energized,
(Ii) (a) In the plasma growth chamber 7, the microwave electron cyclotron resonance plasma 8 is generated by the source gas 15 introduced using the gas introduction tube 4, and the microwave electron cyclotron resonance plasma 8 is generated. It is introduced into the crystal growth chamber 1 through the plasma extraction window 12,
Next, the semiconductor substrate 2-through the plasma extraction window 12 '.
1) and (b) the solid material gas 17 contained therein is obtained from the solid material evaporation cell 6, and the solid material gas 17 is transferred onto the semiconductor substrate 2-1. Is excited by the microwave electron cyclotron resonance plasma 8 and is transported onto the semiconductor substrate 2-1, and thus (iii) the compound semiconductor crystal layer 14 of the first and second materials is formed on the semiconductor substrate 2-1. Can be formed.

In the embodiment of the compound semiconductor crystal layer forming method according to the present invention shown in FIG. 1, the above-mentioned microwave electron cyclotron resonance plasma apparatus capable of forming the compound semiconductor crystal layer 14 as described above is used. Then, (i) (a) the semiconductor substrate 2-1 is placed in the crystal growth chamber 1 using the substrate mounting table 13 as described above, and (b) the solid material evaporation cell 6 is provided with a solid Ga
As a solid material made of the first material for the compound semiconductor layer described above, and (c) the semiconductor substrate 2-
1 and the high-precision solid-phase carbon (C) as the impurities 2-2 in the solid-phase state by using the substrate mounting table 13 and (d) the exhaust pipe 3 While evacuating the crystal growth chamber 1 and the plasma growth chamber 7 from the outside, the arsine (AsH ₃ ) gas is introduced into the plasma growth chamber 7 from the outside by using the gas introduction pipe 4. As the source gas 15 composed of the second material for the compound semiconductor crystal layer to be converted into plasma, 40
At a flow rate of sccm, and (e) at this time, the semiconductor substrate 2-1 is heated to a temperature of 500 ° C., and the rectangular waveguide 9 is used in the plasma growth chamber 7.
A microwave having a frequency of 2.45 GHz and an electric power of 100 W is externally introduced as the microwave 16 described above, the electromagnet 10 is energized, and the solid material evaporation cell 6 is energized. (Ii) (a)
In the plasma growth chamber 7, arsine (As) as the source gas 15 introduced using the gas introduction tube 4 is used.
The microwave electron cyclotron resonance plasma generated by the H ₃ ) gas is generated as the microwave electron cyclotron resonance plasma 8 described above, and the microwave electron cyclotron resonance plasma 8 is passed through the plasma drawing window 12 into the crystal growth chamber 1. The gas of solid Ga contained therein is introduced from the solid material evaporation cell 6 through (b) the solid material evaporation cell 6 as described above. Obtained as the solid material gas 17, and the solid Ga gas is excited by the microwave electron cyclotron resonance plasma 8 transported onto the semiconductor substrate 2-1 to be transported onto the semiconductor substrate 2-1. (C) A microwave electron cyclotron resonance probe in which carbon (C) as an impurity 2-2 is introduced into the crystal growth chamber 1. By irradiation by some Zuma 8, the carbon gas is generated as the impurity gas 18, the impurity gas 18, the semiconductor substrate 2-1
It is excited by the microwave electron cyclotron resonance plasma 8 transported above and is transported onto the semiconductor substrate 2-1. Therefore, (iii) carbon (C) as a p-type impurity is deposited on the semiconductor substrate 2-1. The introduced GaAs crystal layer made of a compound semiconductor of Ga and As is formed as the above-mentioned compound semiconductor crystal layer 14 at a growth rate of 0.5 μm / hour.

The above is the embodiment of the compound semiconductor crystal layer forming method according to the present invention.

According to the compound semiconductor crystal layer forming method according to the present invention as described above, the microwave electron cyclotron resonance plasma 8 of the source gas 15 (AsH ₃ gas) of the compound semiconductor crystal layer 14 (GaAs crystal layer) to be formed is formed. And thereby the impurities in the solid state 2-
2 (carbon (C)) is excited to introduce impurities (carbon (C)) into the compound semiconductor crystal layer 14 (G
Since the (aAs crystal layer) is formed, the energy of the particles of the impurity (carbon (C)) entering the compound semiconductor crystal layer 14 (GaAs crystal layer) that is being formed is equal to that of the conventional compound described above. Compared with the method of forming a semiconductor crystal layer, the compound semiconductor crystal layer 14 (GaAs crystal layer) is high enough not to damage it.
The compound semiconductor crystal layer 14 (GaAs) of the impurity (carbon (C)) entering the crystal layer) is being formed.
The lateral migration distance on the surface of the (crystal layer) is larger than that in the conventional compound semiconductor crystal layer forming method described above. Therefore, it is possible to avoid the formation of precipitates of impurities (carbon (C)) on the surface of the compound semiconductor crystal layer 14 (GaAs crystal layer) that is being formed, and to prevent the formation of impurities (carbon (C)). )) Particles easily reach the lattice position of the element (Ga) which is to be included in the compound semiconductor crystal layer 14 (GaAs crystal layer) and is not occupied by the impurity element (C). Therefore, the compound semiconductor crystal layer 14 (GaAs crystal layer) has the same high impurity concentration as in the above-described conventional compound semiconductor crystal layer forming method and a higher carrier concentration, and yet has no damage. As a thing, it can be easily formed.

This means that the GaAs crystal layer is formed by changing the impurity concentration of carbon (C) by the above-described embodiment of the compound semiconductor crystal layer forming method according to the present invention and the above-mentioned conventional compound semiconductor crystal layer forming method. Then, when the carrier concentration with respect to the impurity concentration was measured, in the case of the conventional compound semiconductor crystal layer forming method, in FIG.
As shown by the dotted line, as the impurity concentration increases, the carrier concentration is proportional to the impurity concentration up to 10 ¹⁹ cm ⁻³ or less, but within the impurity concentration range of 10 ¹⁹ cm ⁻³ or more, In contrast to the impurity concentration, which is saturated in proportion to the impurity concentration and then decreases, in the case of the above-described embodiment of the compound semiconductor crystal layer forming method of the present invention, the carrier concentration is 10 ²⁰ as shown by the solid line in FIG. It will be clear from the result that it is proportional to the impurity concentration up to the high impurity concentration range of cm ⁻³ or more.

According to the above-described embodiment of the compound semiconductor crystal layer forming method according to the present invention, the source gas 15 (AsH) is used.
₃ gas) to generate electron cyclotron resonance plasma 8 and use it to generate compound semiconductor crystal layer 14 (GaAs
Since a crystal layer is formed, the source gas 15
As in the case of the conventional compound semiconductor crystal layer forming method in which a plasma other than the electron cyclotron resonance plasma 8 is generated by (AsH ₃ gas) and the compound semiconductor crystal layer 14 (GaAs crystal layer) is formed using the plasma. Since it is possible to form the compound semiconductor crystal layer 14 (GaAs crystal layer) in the generation chamber 7 without the need to generate plasma by the source gas 15 (AsH ₃ gas) using an electrode or the like that is a pollution source, The compound semiconductor crystal layer 1
4 (GaAS crystal layer) can be easily formed with high purity.

Further, since the electron cyclotron resonance plasma 8 is generated by the source gas 15 (AsH ₃ gas) and is used to form the compound semiconductor crystal layer 14 (GaAs crystal layer), the source gas 15 ( A plasma other than the electron cyclotron resonance plasma 8 is generated by AsH ₃ gas) and is used to generate the compound semiconductor crystal layer 14
As compared with the conventional compound semiconductor crystal layer forming method for forming (GaAs crystal layer), plasma generated by the source gas can be efficiently obtained. Therefore, the source gas 15 (AsH
2 to 3 as compared with the conventional compound semiconductor crystal layer forming method in which plasma other than the electron cyclotron resonance plasma 8 is generated by ₃ gas) and the compound semiconductor crystal layer 14 (GaAs crystal layer) is formed using the plasma. The compound semiconductor crystal layer 14 (GaAs crystal layer) can be formed by the pressure in the plasma generation chamber 7 and the crystal growth chamber 1 which are orders of magnitude lower, and thus the compound semiconductor crystal that is not affected by the undesirable impurities. The layer 14 (GaAs crystal layer) can be easily formed.

Further, according to the above-described embodiment of the compound semiconductor crystal layer forming method of the present invention, as is clear from the above description, the compound semiconductor crystal having a high p-type impurity concentration is formed on the semiconductor substrate 2-1. Since the layer 14 (GaAs crystal layer) can be formed, a semiconductor substrate 2-1 having an n-type is used to apply the above-described embodiment of the compound semiconductor crystal layer forming method according to the present invention. As shown in FIG. 3, a pn junction element having a favorable pn junction diode characteristic that a rectification ratio of five digits or more can be obtained at a voltage of 1.0 V and a so-called n value is 1.1 can be easily obtained. Can be manufactured.

In the above description, only one embodiment of the compound semiconductor crystal layer forming method according to the present invention is shown.
In the above-described embodiment of the compound semiconductor crystal layer forming method according to the present invention, arsine (As
H ₃ ) gas is introduced into the plasma generation chamber 7 to generate hydrogen (H ₂ ).
Is diluted with an inert gas such as a reducing gas or Ar or He, and introduced, whereby the semiconductor substrate 2-
It is also possible to form the compound semiconductor crystal layer 14 (GaAs crystal layer) on the first layer.

In the above-described embodiment of the compound semiconductor crystal layer forming method according to the present invention, the case of forming a GaAs crystal layer into which a p-type impurity of C (carbon) is introduced has been described. Be, Zn , P due to Mg, etc.
Type impurities are introduced, or n type impurities such as Sn and Ge are introduced, and further, titanium (T
i), InP, GaP, AlAs, InAs in which impurities made of refractory metal, which are difficult to introduce only by a thermal reaction process such as tungsten (W), are introduced,
It will be apparent that compound semiconductor crystal layers such as mixed crystals thereof can be similarly formed.

Furthermore, in the above-described embodiment of the compound semiconductor crystal layer forming method according to the present invention, a part (As) of the elements (Ga, As) constituting the compound semiconductor crystal layer (GaAs crystal layer) to be formed is used. ), A microwave electron cyclotron resonance plasma of a source gas (AsH ₃ gas) is generated, and is transported onto a semiconductor substrate, and is formed by the microwave electron cyclotron resonance plasma transported onto the semiconductor substrate. To excite the source gas (Ga gas) and the solid phase impurities (carbon (C)) for the rest (Ga) in the elements (Ga, As) that form the compound semiconductor crystal layer (GaAs crystal layer), Therefore, the compound semiconductor crystal layer (Ga) in which impurities (carbon (C)) are introduced is formed on the semiconductor substrate.
As crystal layer) has been described, but a microwave electron cyclotron resonance plasma of reducing gas (H ₂ ) or inert gas (Ar, He, etc.) is generated,
While transporting it onto the semiconductor substrate, the electron cyclotron resonance plasma transported onto the semiconductor substrate causes solidification with the source gas for all or some of the elements forming the compound semiconductor crystal layer to be formed. It is also possible to excite a phase-state impurity and form a compound semiconductor crystal layer into which an impurity is introduced on a semiconductor substrate, and to form a compound semiconductor crystal layer to be formed. A microwave electron cyclotron resonance plasma of a source gas and a microwave electron cyclotron resonance plasma of a reducing gas or an inert gas are generated for all or some of the elements therein, and they are transported onto a semiconductor substrate, and By electron cyclotron resonance plasma transported on the semiconductor substrate, Pure object was excited, therefore, on a semiconductor substrate, it can also be adapted to form a compound semiconductor crystal layer that has been introduced impurities will be apparent.

Besides, various modifications and changes can be made without departing from the spirit of the present invention.

[Brief description of drawings]

1 is an apparatus (FIG. 1a) which can be used for an embodiment of the compound semiconductor crystal layer forming method according to the present invention, and a magnetic field distribution in the plasma generation chamber and the crystal growth chamber of the apparatus (FIG. 1A).
It is a figure shown with b).

FIG. 2 is a diagram showing the relationship between the impurity concentration and the carrier concentration of the compound semiconductor crystal layer formed by the embodiment of the compound semiconductor crystal layer forming method according to the present invention shown in FIG.

FIG. 3 is a diagram showing characteristics of a pn junction device manufactured by applying the example of the compound semiconductor crystal layer forming method according to the present invention shown in FIG. 1.

[Explanation of reference numerals] 1 crystal growth chamber 2-1 semiconductor substrate 2-2 impurities 3 exhaust pipe 4 gas introduction pipe 5 plasma shield plate 6 solid material evaporation cell 7 plasma generation chamber 8 electron cyclotron resonance plasma 9 square conduction Wave tube 10 Electromagnet 11 Microwave introduction window 12, 12 'Plasma extraction window 13 Substrate mounting table 14 Compound semiconductor crystal layer 15 Raw material gas 16 Microwave 17 Solid material gas 18 Impurity gas

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Claims (3)

[Claims] 1. A microwave electron cyclotron resonance plasma of a source gas of a compound semiconductor crystal layer to be formed is generated, and the microwave electron cyclotron resonance plasma of the source gas is transported to a semiconductor substrate and the semiconductor substrate is also formed. Part of the microwave electron cyclotron resonance plasma of the source gas transported above excites the impurities in the solid state, thus forming a compound semiconductor crystal layer into which the impurities are introduced on the semiconductor substrate. A method for forming a compound semiconductor crystal layer, which comprises: 2. A raw material gas of a compound semiconductor crystal to be formed by the microwave electron cyclotron resonance plasma of a reducing gas or an inert gas, the microwave gas cyclotron resonance plasma of a reducing gas or an inert gas being generated. And a solid phase impurity are excited to form a compound semiconductor crystal layer into which the impurity has been introduced, on the semiconductor substrate. 3. A microwave electron of the source gas for generating a microwave electron cyclotron resonance plasma of a source gas of a compound semiconductor crystal layer to be formed and a microwave electron cyclotron resonance plasma of a reducing gas or an inert gas. While transporting the cyclotron resonance plasma and the microwave electron cyclotron resonance plasma of the reducing gas or the inert gas onto the semiconductor substrate,
The impurities in the solid phase are excited by the microwave electron cyclotron resonance plasma of the source gas and the microwave electron cyclotron resonance plasma of the reducing gas or the inert gas transported onto the semiconductor substrate, and thus the semiconductor A method for forming a compound semiconductor crystal layer, which comprises forming a compound semiconductor crystal layer having the above impurities introduced thereinto.