JPH11354456A - Manufacture of semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture the gallium nitride of an excellent crystalline property with excellent reproducibility. SOLUTION: On the inner side of a reaction furnace 10, a raw material gas introduction nozzle 11 provided with an opening part on a bottom surface is provided. To the opening part of the raw material gas introduction nozzle 11, a susceptor 14 for heating and holding a substrate 13 is inserted. The gas introduction side of the raw material gas introduction nozzle 11 is divided into the three layers of a first introduction layer 11a for introducing the raw material gas of a group V and the carrier gas, a second introduction layer 11b for introducing the raw material gas of the group III and the carrier gas, and a third introduction layer 11c for introducing sub-flow gas composed of the inactive gas of hydrogen, nitrogen or argon gas or the like. On the end part on the side of the substrate 13 of a partition wall between the second introduction layer 11b and the third introduction layer 11c, a bend part 12 as a diffusion prevention means composed by bending the end part downwards is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gallium nitride semiconductor used for a light emitting diode device or a semiconductor laser diode device over a wavelength range from blue light to ultraviolet light.
In particular, the present invention relates to a semiconductor manufacturing method for growing a gallium nitride based semiconductor having excellent electrical and optical characteristics with good reproducibility.

[0002]

2. Description of the Related Art A short-wavelength light-emitting element having a wavelength shorter than blue is expected as a light source for an optical disk capable of full-color display and high-density recording.
Group II-VI compound semiconductors such as Se) or silicon carbide (S
Research has been actively made using III-V compound semiconductors such as iC) and gallium nitride (GaN). In recent years, blue light-emitting diode elements and blue-violet laser diode elements using GaN or InGaN have been realized, and light-emitting elements using a gallium nitride-based semiconductor have attracted attention. Gallium nitride based semiconductor crystals can be grown by metal organic chemical vapor deposition (MOVPE) or molecular beam epitaxy (MB).
The E) method is generally used.

For example, Japanese Patent Application Laid-Open No. 2-29114 discloses a conventional vapor phase growth apparatus for gallium nitride-based semiconductor crystals using the MOVPE method. Discloses a method for efficiently supplying a raw material gas to a fuel cell.

[0004]

However, the conventional vapor phase growth apparatus has a horizontal reaction chamber for flowing a gas parallel to the substrate, and has a structure in which a gas inlet nozzle in the reaction chamber has a throttle section. As the number of growth increases, the reaction product adheres above the substrate of the gas introduction nozzle, so the attached reaction product becomes flaky and falls on the substrate,
If the distance between the substrate and the gas introduction nozzle or the gas flow is changed, the reproducibility of crystal growth is degraded.

In the case of the two-flow system disclosed in Japanese Patent Application Laid-Open No. 6-196557, although there is little problem that a reaction product is generated, the sub-flow gas from above the substrate is caused by the flow of the source gas. Therefore, there is a problem that the range of optimal gas supply conditions is narrowed, and the growth conditions are largely changed even if the reaction chamber is slightly contaminated.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and to manufacture a gallium nitride semiconductor having excellent crystallinity with good reproducibility.

[0007]

In order to achieve the above object, a first aspect of the present invention is to introduce a layered source gas in parallel on a substrate and to introduce a layered subflow gas above the source gas. Configuration.

According to a second aspect of the present invention, the flow rate of a gas such as a source gas is made smaller at the time of growing a semiconductor layer containing indium (In) which hardly improves crystallinity than at the time of growing a semiconductor layer containing no indium. And

The third invention has a structure in which means for protecting the semiconductor layer containing indium is provided between the semiconductor layer containing indium and the semiconductor layer not containing indium.

More specifically, the first method of manufacturing a semiconductor according to the present invention comprises introducing a source gas containing a group III source and a nitrogen source into a substrate substantially parallel to the substrate surface and in a layered manner. A method for manufacturing a semiconductor for manufacturing a group III nitride semiconductor on a substrate, comprising a step of introducing a subflow gas in a layer substantially parallel to a substrate surface above a source gas.

According to the first semiconductor manufacturing method, since the source gas is introduced in a layer shape substantially parallel to the substrate surface, turbulence of the gas does not easily occur on the substrate, and the subflow gas is placed above the source gas. Sub-flow gas flowing above the source gas suppresses convection of the source gas due to heating because it is introduced substantially parallel to the substrate surface and in a layered manner. Products are less likely to form.

It is preferable that the first semiconductor manufacturing method further includes a step of introducing the source gas using a diffusion preventing means for preventing the source gas from diffusing to the subflow gas side. This makes it difficult for the diffusion-preventing means to convect the layered source gas upward, so that no extra reaction product is generated.

In the first method for manufacturing a semiconductor, it is preferable that the subflow gas contains hydrogen, nitrogen or argon.

A second method for manufacturing a semiconductor according to the present invention comprises:
Introducing a first source gas containing at least indium and nitrogen to grow a first semiconductor layer on a substrate, and a second source gas containing aluminum or gallium and nitrogen And a second semiconductor layer growing step of growing a second semiconductor layer on the substrate by introducing a first semiconductor gas, wherein a gallium nitride based semiconductor is grown on the substrate. The flow rate is smaller than the flow rate of the second source gas.

According to the second semiconductor manufacturing method, usually,
When growing the first semiconductor layer containing indium,
At the same temperature, the equilibrium vapor pressure of nitrogen in InN is GaN
Therefore, it is necessary to lower the growth temperature as compared with the case where the second semiconductor layer containing no indium is grown. However, when ammonia is used as the nitrogen source, the decomposition efficiency of ammonia decreases at a relatively low temperature, so that the crystallinity of the first semiconductor layer deteriorates. In the production method of the present invention, since the flow rate of the first raw material gas is made smaller than the flow rate of the second raw material gas, the amount of heat supplied per unit time with respect to a unit amount of ammonia increases. The decomposition efficiency is improved.

In the second method for manufacturing a semiconductor, the pressure of the first source gas is higher than the pressure of the second source gas,
Alternatively, the flow rate of the first source gas is preferably smaller than the flow rate of the second source gas.

In the second method for manufacturing a semiconductor, the first source gas is introduced substantially parallel to the substrate surface and in a layered manner, and the subflow gas is layered on the upper side of the first source gas substantially parallel to the substrate surface and in a layered manner. It is preferable to include a step including a step of introducing the compound into In this case, the upward convection of the source gas is suppressed by the subflow gas.

In the second method for manufacturing a semiconductor, the subflow gas preferably contains nitrogen or argon. In this case, since the thermal conductivity of nitrogen or argon is relatively small, it is difficult to diffuse the temperature of the substrate.

According to a third method of manufacturing a semiconductor according to the present invention,
A method for producing a semiconductor in which a gallium nitride-based semiconductor is grown by introducing a gas containing a source gas onto a substrate, wherein a first source gas containing at least indium and nitrogen is introduced into the substrate to form a first gas on the substrate. First to grow semiconductor layer
And a second source gas containing aluminum or gallium and nitrogen is introduced at substantially the same flow rate as the first source gas to form a first semiconductor layer on the upper surface of the first semiconductor layer. A decomposition suppressing layer growing step of growing a decomposition suppressing layer for suppressing decomposition, and introducing a third source gas containing aluminum or gallium and nitrogen to form a second layer on the upper surface of the decomposition suppressing layer.
A second semiconductor layer growing step of growing the semiconductor layer.

According to the third method for manufacturing a semiconductor, the second source gas introduced at a flow rate substantially equal to the flow rate of the first source gas is applied onto the first semiconductor layer containing at least indium. Since the decomposition suppressing layer that suppresses the decomposition of the first semiconductor layer is grown at a flow rate substantially equal to the flow rate of the first source gas, indium does not escape from the first semiconductor layer.

According to a fourth method of manufacturing a semiconductor according to the present invention,
Introducing a first source gas containing at least indium and nitrogen to grow a first semiconductor layer on the substrate by introducing a first source gas containing at least indium and nitrogen; and supplying a second source gas containing aluminum or gallium and nitrogen. A second semiconductor layer growing step of growing a second semiconductor layer on an upper surface of the first semiconductor layer, the method comprising the steps of: growing a gallium nitride-based semiconductor on a substrate; The second semiconductor layer growing step includes a step of introducing a mixed gas containing an inert gas and a nitrogen source gas at substantially the same flow rate as the flow rate of the second source gas before introducing the second source gas. .

According to the fourth semiconductor manufacturing method, after growing the first semiconductor layer containing at least indium on the substrate, before growing the second semiconductor layer containing no indium, an inert gas and Since the mixed gas containing the nitrogen source gas is introduced at substantially the same flow rate as the flow rate of the second source gas for the second semiconductor layer, it is difficult for indium to escape from the first semiconductor layer.

[0023]

(First Embodiment) A first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross-sectional structure of a reactor and a source gas introduction nozzle of a horizontal MOVPE apparatus for realizing a semiconductor manufacturing method according to a first embodiment of the present invention. As shown in FIG. 1, a raw material gas introduction nozzle 11 made of quartz having an opening on the bottom surface and a constricted portion narrowed so that the upper part of the opening is narrowed toward the discharge side is provided inside the reaction furnace 10. Have been.

A susceptor 14 for heating and holding the substrate 13 is provided at an opening of the source gas introduction nozzle 11.
4 and the bottom surface of the raw material gas introduction nozzle 11 are inserted so that there is no step between them. The gas introduction side of the material gas introduction nozzle 11 is, in order from the bottom side, a first introduction layer 11a for introducing a group V material gas and its carrier gas, and a second introduction layer 11a for introducing a group III material gas and its carrier gas. It is divided into three layers: an introduction layer 11b and a third introduction layer 11c for introducing a subflow gas composed of an inert gas such as hydrogen (H ₂ ) gas, nitrogen (N ₂ ) gas or argon (Ar) gas. .

The second introduction layer 11b and the third introduction layer 11c
A bent portion 12 is provided at an end portion of the partition wall on the substrate 13 side (discharge side) between the end portion and the bent end portion as a diffusion preventing means.

As described above, in the source gas introduction nozzle 11, the upper surface of the substrate 13 held by the susceptor 14
A gas containing each source gas is introduced from the first introduction layer 11a and the second introduction layer 11b in a layer shape substantially parallel to the substrate surface, and a subflow gas contains each source gas from the third introduction layer 11c. The gas is introduced in a layer so as to flow on the upper side of the gas and substantially parallel to the substrate surface. This sub-flow gas makes it difficult for the gas containing each source gas to be heated on the susceptor 14 and diffused above the substrate 13 by thermal convection. In addition, by optimizing the flow rate of the sub-flow gas, the reaction product adheres. Can be prevented.

Further, a bent portion 12 is formed at an end of the partition wall between the second introduction layer 11b and the third introduction layer 11c on the substrate 13 side.
Is provided, it becomes more difficult for the gas containing each of the source gases to wind above the substrate 13, so that extra reaction products are less likely to be generated.

Therefore, according to this embodiment, the reaction product does not adhere in a flaky manner above the susceptor 14 of the source gas introduction nozzle 11, whereby the reaction product is deposited on the growing substrate 13. Since the nozzle does not drop or the diameter of the material gas introduction nozzle 11 on the substrate 13 is reduced, the reproducibility of the gas flow is improved even if the number of times of growth is increased. As a result, the crystal quality of the GaN-based semiconductor can be increased, and good reproducibility of the high crystal quality can be maintained.

Further, since each source gas and subflow gas flow in parallel with each other, no turbulence occurs on the substrate 13, so that the flow of each source gas and subflow gas can be easily optimized.

FIG. 2 shows the room-temperature band-edge emission intensity with respect to the number of times of growth of each GaN crystal grown using the source gas introduction nozzle 11 according to the present embodiment and the comparative source gas introduction nozzle having no bent portion 12. It is a graph which shows the relationship of a ratio. In FIG. 2, a circle curve shows a GaN crystal when the gas introduction nozzle according to the present embodiment is used, and a cross curve shows a GaN crystal when a comparison gas introduction nozzle is used. As shown in FIG. 2, when the GaN crystal for comparison is grown 100 times,
The crystal has a band edge emission intensity ratio reduced to about 25% as compared with the initial GaN crystal. On the other hand, in the GaN crystal according to the present embodiment, the intensity ratio hardly decreases even when the number of times of growth is repeated 100 times. As described above, the effect of the bent portion 12 for preventing the source gas from diffusing upward is extremely large.

Here, in the conventional MOVPE method,
In growing a semiconductor layer made of In _x Ga ₁ -xN (where x is 0 <x ≦ 1), H ₂ gas or N ₂ gas has been used as a carrier gas. As described above, it is particularly preferable to use Ar gas as the subflow gas. As shown in FIG. 3, Ar has a thermal conductivity of H ₂ or N.
_Since the heat on the substrate 13 is difficult to dissipate because it is smaller than ₂ , the use of ammonia (NH ₃ ) gas as the group V source improves the thermal decomposition efficiency of ammonia gas, which is difficult to thermally decompose. The effective value of the V / III ratio, which is the value of the ratio between the group V source and the group III source, which tends to be small, can be increased.

Further, since Ar has a larger mass number than H ₂ or N ₂ , it is difficult for the gas to be swirled by thermal convection, so that each source gas can be reliably introduced onto the substrate 13.

This Ar gas is not only effective as a subflow gas, but also may be used as a carrier gas for each of group III and group V source gases.

As shown in FIG. 1, the throttle portion is provided on the gas discharge side of the raw material gas introduction nozzle 11;
Due to the effect of 2, the throttle section does not necessarily have to be provided. The end of the partition between the first introduction layer 11a and the second introduction layer 11b on the substrate 13 side is shorter than the partition having the bent portion 12, but the position of this end is not necessarily limited to this. Absent.

(Second Embodiment) Hereinafter, a method for manufacturing a semiconductor according to a second embodiment of the present invention will be described.

In this embodiment, In _x Ga ₁ -xN (where x is 0 <x ≦ 1), where it is difficult to improve the quality of the crystal.
And ) To improve the crystallinity of the semiconductor layer.

As a conventional MOVPE method for an InGaN-based semiconductor, there is, for example, a method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 6-196557. That is, first, a buffer layer of GaN and Ga on a substrate of sapphire.
N and a semiconductor layer made of N.
A semiconductor layer made of aN is grown. At this time, GaN
It is disclosed that a mixed gas of H ₂ and N ₂ is used as a carrier gas when growing a semiconductor layer made of InGaN, and only a nitrogen gas is used as a carrier gas when growing a semiconductor layer made of InGaN. At this time, the total flow rate of the NH ₃ gas of the nitrogen source and its carrier gas is maintained at a predetermined value irrespective of the type of mixed crystal, which means that the flow rate of the gas containing the source gas on the substrate is constant. Means As described above, when growing a multilayer film using the conventional MOVPE method, it is a common sense that the total flow rate and pressure of the source gas and the carrier gas are maintained at predetermined values, that is, the flow rate is kept constant. I have.

The inventors of the present application have studied various reasons why a high-quality InGaN crystal cannot be obtained, and have found the following problems. That is, because InN has a higher equilibrium vapor pressure of nitrogen at the same temperature than GaN, InGa
Although N is grown at a temperature lower than that of GaN when N is grown, a higher V / III supply ratio is required to suppress the evaporation of nitrogen. Under the condition where is constant, an effectively high V / III ratio is not necessarily ensured.

Therefore, in the present invention, the flow rate of the gas containing the source gas when growing InGaN is made smaller than the flow rate of the gas containing the source gas when growing the semiconductor layer not containing In. Thereby, even if the growth temperature is lowered when growing InGaN, the amount of heat supplied per unit time with respect to the unit amount of ammonia of the nitrogen source increases, so that the decomposition efficiency of ammonia is improved, and as a result, V /
III The value of the ratio can be increased substantially.

FIG. 4 shows a cross-sectional structure of an InGaN-based semiconductor obtained by using the semiconductor manufacturing method according to the second embodiment.

First, the group V source gas composed of NH ₃ gas is supplied to the first introduction layer 11a of the source gas introduction nozzle 11 with respect to the source gas introduction nozzle 11 of the reaction furnace 10 shown in FIG. , Trimethyl gallium (TMG) or trimethyl indium (TMI) can be supplied to the second introduction layer 11b of the source gas introduction nozzle 11, and the inert gas such as H ₂ , N ₂ or Ar The sub-flow gas composed of gas is supplied to the third introduction layer 11.
c. An inert gas such as H ₂ , N ₂ or Ar is also used as a carrier gas for each source gas.

Next, a substrate 21 made of sapphire whose surface has been cleaned and having a C surface on the main surface is placed on the susceptor 1 in the reactor 10.
Hold at 4. Subsequently, the reaction furnace 10 is evacuated, and the substrate 21 is heated for 15 minutes in a hydrogen atmosphere at a temperature of 1050 ° C. and a pressure of 70 Torr to clean the surface of the substrate 21. The heat treatment may be performed by, for example, high-frequency induction heating using a coil provided on the susceptor 14 or resistance heating using a resistor.

Next, after the temperature of the substrate 21 is lowered to 600 ° C., 20 μmol / min of TMG and 5.0 L / min of NH ₃ gas are introduced onto the substrate 21, whereby the main surface of the substrate 21 is A buffer layer 22 made of polycrystalline GaN having a thickness of 50 nm is deposited thereon. Here, H ₂ was used for all of the sub-flow gas, the group III source carrier gas, and the group V source carrier gas, and the flow rate was 9 L each.
/ Min, 5.5 L / min and 0.5 L / min.

Next, the introduction of TMG was stopped, the temperature of the substrate 21 was raised to 950 ° C., and then 20 μmol
/ Minute of TMG is introduced, the temperature of the substrate 21 is set to 1050 ° C.,
The temperature is raised stepwise to 1090 ° C. to grow the first semiconductor layer 23 made of GaN single crystal. Here, the type and flow rate of each carrier gas are the same as in the growth step of the buffer layer 22.

Next, the subflow gas is changed from H ₂ gas to N ₂ gas.
Switch to gas, NH _{3 of} V group source, H _{2 of} carrier gas
Then, the temperature of the substrate 21 is reduced to 800 ° C. in a mixed atmosphere of N ₂ and a subflow gas. Thereafter, the growth pressure in the reactor 10 was increased to 650 Torr, and
Add 1 / min TMI and 1 μmol / min TMG,
On the first semiconductor layer 23, a second semiconductor layer 24 of InGaN is grown. Here, the flow rate of NH ₃ of the group V source is 7.5 L / min, and the flow rates of the subflow gas, the carrier gas for the group III source material and the carrier gas for the group V source material are 12 L / min, 5.5 L / min, and 0 L, respectively. 0.5 L / min.

FIG. 5 shows the result of comparing the photoluminescence spectra of an InGaN crystal obtained by using the manufacturing method according to the present embodiment and a comparative InGaN crystal obtained by using the conventional manufacturing method. In FIG. 5, curve 1 represents the spectrum of the InGaN crystal of the present invention, and curve 2 represents the spectrum of a comparative InGaN crystal. Here, the comparative InGaN crystal is
The reaction pressure during the growth of the second semiconductor layer is 70 Torr, which is the same as the reaction pressure during the growth of the first semiconductor layer, and the subflow gas is N ₂ gas. As can be seen from FIG.
If the second semiconductor layer made of InGaN is grown at the same gas flow rate as the first semiconductor layer made of GaN, the composition of In decreases, so that the band edge emission shifts to a shorter wavelength side and a longer wavelength. On the side, light emission from a deep level due to defects is observed.

FIG. 6A shows the relationship between the flow rate of the gas containing the source gas in the InGaN crystal and the value of the ratio of the emission intensity from a deep level to the emission intensity of the band edge emission. As shown in FIG. 6 (a), the flow rate of the gas containing the source gas was set to 0.1 m / sec, 0.5 m / sec, 1.5 m / sec,
Five types of InGa at 2.0 m / sec and 3.0 m / sec
When an N crystal is grown and room temperature photoluminescence is observed to evaluate the crystallinity of each InGaN crystal, a gas flow rate of 1 m / sec is obtained to obtain high quality crystallinity with small emission from deep levels. It turns out that it is good to set it before and after.

FIG. 6B shows the relationship between the flow rate of the gas containing the source gas in the GaN crystal and the value of the ratio of the emission intensity from a deep level to the emission intensity of the band edge emission. In the case of a crystal, the crystallinity is improved at a flow rate of 3 m / sec or more, which is higher than that of the InGaN crystal.

As described above, when growing a GaN-based semiconductor layer containing In, if the flow rate of the gas containing the source gas is reduced as compared with growing a GaN-based semiconductor containing no In with good crystallinity, The crystallinity of a GaN-based semiconductor containing In can be improved.

In order to reduce the flow velocity of the gas, the total flow rate of the gas may be reduced in addition to increasing the pressure of the gas containing the source gas.

Although InGaN is used as the semiconductor containing In, AlGaInN containing Al may be used.

When a Group V mixed crystal represented by the general formula of AlGaInNAsP, such as GaNAs or GaNP, is prepared, the raw material gas introducing nozzle according to the present invention and the growth pressure or the total flow rate are changed to change the raw material gas. It goes without saying that a manufacturing method in which the flow rate of gas containing gas is changed is effective.

In particular, when growing GaN or GaNP, GaAs or InP has a lower equilibrium vapor pressure than GaN, so it is effective to increase the flow rate of the gas containing the raw material gas as compared with the case of growing GaN. It is.

(Third Embodiment) Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.

The feature of this embodiment is that an active layer decomposition suppressing layer is formed on the surface of an active layer made of InGaN crystal which is easily decomposed during crystal growth, so that a light emitting device having excellent characteristics can be formed.

FIG. 7 shows In according to the third embodiment of the present invention.
1 shows a cross-sectional configuration of a GaN-based semiconductor light emitting device. The semiconductor layer for the semiconductor light emitting device according to the present embodiment may use the reaction furnace and the source gas introduction nozzle of the MOVPE apparatus according to the first embodiment, or may use a normal MOVPE apparatus.

First, a substrate 21 made of sapphire whose surface has been cleaned and having a C-plane on the main surface is held on a susceptor in the reactor. Subsequently, the reactor was evacuated and the temperature was set at 1050.
The surface of the substrate 31 is cleaned by heating the substrate 31 for 15 minutes in a hydrogen atmosphere at 70 ° C. and a pressure of 70 Torr.

Next, after the temperature of the substrate 31 is lowered to 600 ° C., the subflow gas, the carrier gas for the group III source material and the carrier gas for the group V source material are all set to H ₂ ,
1 on top of 20 μmol / min TMG and 5.0 L / min N
By introducing H ₃ gas, a buffer layer 32 made of polycrystalline GaN having a thickness of 50 nm is deposited on the main surface of the substrate 31.

Next, the introduction of TMG was stopped, the temperature of the substrate 31 was raised to 950 ° C., and then 20 μmol
/ Min of TMG and monosilane (SiH ₄ ) as an n-type dopant of 10 cc / min.
The temperature is gradually increased to 050 ° C. and 1090 ° C., and an n-type contact layer 33 made of n-type GaN single crystal is grown on the buffer layer 32.

Next, 5 μm is formed on the n-type contact layer 33.
The n-type cladding layer 34 of n-type AlGaN is grown by further adding mol / min of trimethylaluminum (TMA), and then the introduction of TMA is stopped to grow the n-type guide layer 35.

Next, the sub-flow gas is changed from H ₂ gas to Ar
The gas and the carrier gas for the group V source are switched from H ₂ gas to N ₂ gas, and the substrate 31 is mixed in a mixed atmosphere of NH _{3 of} the group V source, H ₂ and N ₂ of the carrier gas, and Ar of the subflow gas. The temperature is lowered to 800 ° C. After that, the growth pressure in the reactor 10 is increased to 650 Torr,
TMI of 10 μmol / min and TMG of 1 μmol / min are added to grow a first well layer of InGaN on the n-type guide layer 35. Subsequently, introduction of TMI is stopped and 10 μmol / min. And a first barrier layer made of GaN is grown on the well layer. The MQW active layer 36 serving as a multiple quantum well layer is formed by repeating the well layers and the barrier layers until a predetermined number of layers are formed. Here, the barrier layer may contain In. Further, the flow rate of NH ₃ of the group V source is set to 7.5 L / min, and the flow rates of the subflow gas, the carrier gas for the group III raw material and the carrier gas for the group V raw material are 12 L / min, 5.5 L / min and 0.5 L / min, respectively. 5 L / min.

Next, the introduction of TMI was stopped, and the active layer decomposition suppressing layer 3 made of GaN having a thickness of 20 nm was formed on the MQW active layer 36 while keeping the growth pressure high at 650 Torr.
Grow 7. Thereafter, both the subflow gas and the carrier gas for the group V raw material are returned to H ₂ gas.

Next, the temperature of the substrate 31 was increased to 1090 ° C. in a mixed atmosphere of NH ₃ gas and H ₂ gas, the growth pressure was reduced to 70 Torr, and the T
A p-type guide layer 38 made of p-type GaN is grown on the active layer decomposition suppressing layer 37 by adding MG and biscyclopentadienyl magnesium (Cp ₂ Mg) as a p-type dopant at 1 μmol / min to the raw materials. . Then, 5μmo
The p-type cladding layer 39 of p-type AlGaN is grown on the p-type guide layer 38 by further adding 1 / min of TMA.

Next, while the introduction of TMA is stopped, Cp ₂ Mg of about 1 μmol / min is introduced to form a first 0.5 μm-thick p-type GaN film on the p-type cladding layer 39. Of a p-type contact layer 40 of
0 μmol / min of Cp ₂ Mg was introduced to achieve a film thickness of 0.1 μm.
A second p-type contact layer 41 made of p-type GaN having a high concentration of m is sequentially grown.

Next, the substrate 31 on which the epitaxial layer has been formed is taken out of the reaction furnace, and nickel (Ni) or an alloy containing Ni is formed on the second p-type contact layer 41 by photolithography or the like. The positive electrode 42 is selectively formed. Subsequently, using the positive electrode 42 as a mask, for example, using a mixed gas of hydrogen and chlorine at a mixing ratio of 1: 1 in a plasma atmosphere at a pressure of 1 Torr,
1 as room temperature, the second p-type contact layer 41,
Dry etching is performed on the upper portions of the first p-type contact layer 40 and the p-type cladding layer 39 to remove them. Here, the mixing ratio of hydrogen and chlorine is preferably 1 to 1, but is not limited thereto. Also, a typical etching rate is about 50 nm / min.

Next, a mask pattern made of, for example, SiO ₂ is formed on the entire surface of the substrate 31 except for the negative electrode formation region, and the mask pattern is used to etch the negative electrode formation region under the same etching conditions as described above. By performing dry etching, the portion from the p-type cladding layer 39 to the upper portion of the n-type contact layer 33 in the negative electrode forming region is removed. Thereafter, the mask pattern is removed, and subsequently, a negative electrode 43 made of Al is formed in the negative electrode forming region on the n-type contact layer 33.

Next, dry etching is performed on the substrate 31 in the same plasma atmosphere as when the electrodes are formed, thereby forming a laser light emitting end face (resonator end face) on the side surface of the light emitting element shown in FIG. The light emitting element needs to reflect the generated light at the emission end face to resonate, and the emission end face is required to have a flatness of about 1 nm or less.

Next, a pressure of 1 atmosphere (760 Torr) and a temperature of 7
Heat treatment is performed for 30 minutes in a nitrogen atmosphere at about 00 ° C. Here, the atmosphere gas is preferably only nitrogen, but may be a mixed gas of hydrogen and nitrogen. The heat treatment temperature may be 500 ° C. or higher.

It has been confirmed that the semiconductor light emitting device thus manufactured can stably output a laser beam having a wavelength of 405 nm at room temperature, and that the reliability has been dramatically improved.

According to the semiconductor light emitting device of this embodiment, the MQW active layer 36 containing InGaN is
An active layer decomposition suppressing layer 37 for suppressing the decomposition of the upper part of the MQW active layer 36 while maintaining the same gas flow rate as the W active layer 36.
Is formed, a desired MQW active layer 36 can be reliably obtained.

When the active layer decomposition suppressing layer 37 is grown,
The growth may be performed while the growth pressure is set to 70 Torr and the growth temperature is gradually increased from 800 ° C. to 1090 ° C.

As a modification of the present embodiment, MQ
After growing the W active layer 36, an inert gas such as N ₂ gas is used instead of forming the active layer decomposition suppressing layer 37 so as to have a flow rate similar to that of the gas for growing the p-type guide layer 38. A mixed gas of nitrogen and an NH ₃ gas as a nitrogen source may be introduced onto the substrate 31. Thereafter, the MQW active layer 3 is formed under a predetermined condition.
A p-type guide layer 38 is formed on 6.

In this manner, the active layer decomposition suppressing layer 37 is formed.
Is formed, the p-type guide layer 38 is grown before the p-type guide layer 38 is grown on the MQW active layer 36.
Inert gas and NH ₃ at a flow rate almost the same as the flow rate during the growth of
Since the introduction of the gas mixture with the gas makes it difficult for In atoms to escape from the surface of the MQW active layer 36, the decomposition of the MQW active layer 36 is suppressed.

[0075]

According to the first semiconductor manufacturing method of the present invention, the sub-flow gas flowing above the raw material gas suppresses the upward convection of the raw material gas due to the heating, so that the sub-flow gas on the substrate of the reaction furnace or the gas introduction nozzle is formed. Extra reaction products are less likely to be generated on the inner wall, and the concentration of the source gas on the substrate is relatively high. Therefore, a gallium nitride-based semiconductor having excellent crystallinity can be manufactured with good reproducibility, so that a blue-violet semiconductor laser device having high efficiency and excellent optical characteristics can be manufactured.

If the first semiconductor manufacturing method further includes a step of introducing the source gas using a diffusion preventing means for preventing the source gas from diffusing to the subflow gas side, the layered source gas is moved upward. Since convection hardly occurs, no extra reaction product is generated, and the reproducibility of the crystal is remarkably improved.

In the first semiconductor manufacturing method, if the subflow gas contains hydrogen, nitrogen, or argon, these gases are inert gases that do not react with the raw materials of the group III-V semiconductor, so that the desired semiconductor crystal is formed. Will surely grow.

According to the second semiconductor manufacturing method of the present invention, the flow rate of the first source gas for the first semiconductor
When the ammonia is used as the nitrogen source, the amount of heat supplied per unit time to the unit amount of ammonia increases in order to make the flow rate smaller than the flow rate of the second source gas for the semiconductor layer. Efficiency is improved. As a result, radical nitrogen atoms increase on the substrate, and the increased radical nitrogen atoms take indium, whereby a desired semiconductor layer containing indium can be obtained.

In the second method of manufacturing a semiconductor, the pressure of the first source gas is higher than the pressure of the second source gas,
Alternatively, when the flow rate of the first source gas is smaller than the flow rate of the second source gas, the flow rate of the first source gas is surely smaller than the flow rate of the second source gas.

In the second method of manufacturing a semiconductor, the first source gas is introduced substantially parallel to the substrate surface and in a layered manner, and the subflow gas is layered on the upper side of the first source gas substantially parallel to the substrate surface and in a layered manner. Including the step of introducing the raw material gas, the controllability of the gas is improved because the raw material gas and the like are flown in a layer parallel to the substrate surface, and the layer is formed on the upper side of the first raw material gas substantially parallel to the substrate surface. Since the upward convection of the raw material gas is suppressed by the subflow gas introduced into the reactor, unnecessary reaction products are less likely to adhere to the substrate above the substrate of the reaction furnace or the gas introduction nozzle, and the reproducibility of crystal quality is improved. .

In the second method for manufacturing a semiconductor, the subflow gas preferably contains nitrogen or argon. In this case, since the thermal conductivity of nitrogen or argon is relatively small, it is difficult to dissipate the temperature of the substrate, so that the thermal decomposition efficiency of the ammonia gas of the nitrogen source can be kept high. In particular, since argon has a larger mass number than nitrogen, it is difficult for the gas to be swirled by thermal convection, so that the source gas can be reliably introduced onto the substrate.

According to the third method of manufacturing a semiconductor of the present invention, the second source gas introduced at a flow rate substantially equal to the flow rate of the first source gas onto the first semiconductor layer containing at least indium. Is used to grow a decomposition suppressing layer that suppresses decomposition of the first semiconductor layer, so that indium does not escape from the first semiconductor layer; thus, a desired first semiconductor layer containing indium can be obtained. .

According to the fourth method of manufacturing a semiconductor of the present invention, after growing the first semiconductor layer containing at least indium on the substrate, before growing the second semiconductor layer containing no indium, Since the mixed gas containing the active gas and the nitrogen source gas is introduced at substantially the same flow rate as the flow rate of the second source gas for the second semiconductor layer, indium hardly escapes from the first semiconductor layer. Thus, a desired first semiconductor layer containing indium can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration sectional view showing a reactor and a material gas introduction nozzle of a horizontal MOVPE apparatus for realizing a semiconductor manufacturing method according to a first embodiment of the present invention.

FIG. 2 shows room-temperature band-edge luminescence with respect to the number of times of growth of each GaN crystal grown using a source gas introduction nozzle used for a semiconductor manufacturing method according to the first embodiment of the present invention and a source gas introduction nozzle for comparison. It is a graph which shows the relationship of an intensity ratio.

FIG. 3 is a table comparing the thermal conductivity of each gas.

FIG. 4 is a sectional view showing a configuration of an InGaN-based semiconductor obtained by using a method for manufacturing a semiconductor according to a second embodiment of the present invention.

FIG. 5 is a graph comparing photoluminescence spectra of an InGaN crystal obtained by using the semiconductor manufacturing method according to the second embodiment of the present invention and a comparative InGaN crystal obtained by using the conventional manufacturing method. is there.

FIG. 6A is a graph showing a relationship between a flow rate of a gas including a source gas in an InGaN crystal and a value of a ratio of light emission intensity from a deep level to light emission intensity of band edge emission. (B) is a graph showing the relationship between the flow rate of the gas containing the source gas in the GaN crystal and the value of the ratio of the emission intensity from a deep level to the emission intensity of band edge emission.

FIG. 7 is a configuration sectional view showing an InGaN-based semiconductor light emitting device according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Reactor 11 Source gas introduction nozzle 11a First introduction layer 11b Second introduction layer 11c Third introduction layer 12 Bent part (diffusion prevention means) 13 Substrate 14 Susceptor 21 Substrate 22 Buffer layer 23 First semiconductor layer 24 second semiconductor layer 31 substrate 32 buffer layer 33 n-type contact layer 34 n-type cladding layer 35 n-type guide layer 36 MQW active layer 37 active layer decomposition suppression layer (decomposition suppression layer) 38 p-type guide layer 39 p-type clad Layer 40 First p-type contact layer 41 Second p-type contact layer 42 Positive electrode 43 Negative electrode

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Ayumi Tsujimura 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (9)

[Claims] 1. A semiconductor manufacturing method for producing a group III nitride semiconductor on a substrate by introducing a source gas containing a group III source and a nitrogen source into the substrate substantially in parallel with the substrate surface and in a layered manner. A method for producing a semiconductor, comprising a step of introducing a subflow gas into a layer substantially parallel to a substrate surface above a source gas. 2. The semiconductor device according to claim 1, further comprising a step of introducing said source gas using a diffusion preventing means for preventing diffusion of said source gas to said subflow gas side. Production method. 3. The method according to claim 1, wherein the sub-flow gas contains hydrogen, nitrogen, or argon. 4. A first semiconductor layer growing step of introducing a first source gas containing at least indium and nitrogen to grow a first semiconductor layer on a substrate, comprising: aluminum or gallium and nitrogen. A second semiconductor layer growth step of introducing a second source gas to grow a second semiconductor layer on the substrate, wherein the method comprises growing a gallium nitride-based semiconductor on the substrate. And a flow rate of the first source gas is smaller than a flow rate of the second source gas. 5. The pressure of the first source gas is higher than the pressure of the second source gas, or the flow rate of the first source gas is lower than the flow rate of the second source gas. The method for manufacturing a semiconductor according to claim 4, wherein: 6. The first semiconductor layer growing step, wherein the first source gas is introduced substantially in parallel with the substrate surface in a layered manner, and a sub-flow gas is applied to the substrate surface above the first source gas. 5. The method for manufacturing a semiconductor according to claim 4, further comprising a step of introducing in a substantially parallel and layered manner. 7. The method according to claim 6, wherein the subflow gas includes nitrogen or argon. 8. A semiconductor manufacturing method for growing a gallium nitride-based semiconductor by introducing a gas containing a source gas onto a substrate, the method comprising: introducing a first source gas containing at least indium and nitrogen; A first semiconductor layer growing step of growing a first semiconductor layer thereon; and introducing a second source gas containing aluminum or gallium and nitrogen at substantially the same flow rate as the first source gas,
A decomposition suppressing layer growing step of growing a decomposition suppressing layer for suppressing the decomposition of the first semiconductor layer on the upper surface of the first semiconductor layer; and introducing a third source gas containing aluminum or gallium and nitrogen. And a second semiconductor layer growing step of growing a second semiconductor layer on the upper surface of the decomposition suppressing layer. 9. A first semiconductor layer growing step of introducing a first source gas containing at least indium and nitrogen to grow a first semiconductor layer on a substrate, and a step of containing aluminum or gallium and nitrogen. And a second semiconductor layer growing step of growing a second semiconductor layer on the upper surface of the first semiconductor layer by introducing a second source gas, wherein a gallium nitride based semiconductor is grown on the substrate. In the manufacturing method, the second semiconductor layer growing step may include, before introducing the second source gas, mixing a mixed gas containing an inert gas and a nitrogen source gas with a flow rate of the second source gas. A method for manufacturing a semiconductor, comprising a step of introducing at substantially the same flow rate.