JP2008311421A - Manufacturing method of group iii nitride compound semiconductor light emitting element, group iii nitride compound semiconductor light emitting element, and lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a group III nitride compound semiconductor that can easily optimize doping concentration of a dopant element in crystal of a gallium nitride compound semiconductor and efficiently deposit a film. <P>SOLUTION: Disclosed is the manufacturing method of the group III nitride compound semiconductor light emitting element wherein a Ga target 47a containing a Ga element and a dopant target 47b consisting of a dopant element are used to form at least a portion of a semiconductor layer by exciting the Ga target 47a by sputtering and exciting the dopant target 47b with charged particles in a beam shape. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a group III nitride compound semiconductor light-emitting device, a group III nitride compound semiconductor light-emitting device, and a group III, which are suitably used for a light-emitting diode (LED), a laser diode (LD), an electronic device, and the like. The present invention relates to a lamp using a nitride compound semiconductor light emitting device.

Group III nitride semiconductors have a direct transition type band gap of energy corresponding to the range from the visible light to the ultraviolet light region, and are excellent in luminous efficiency. Therefore, they are used as light emitting elements such as LEDs and LDs. Yes.
Moreover, even when the group III nitride semiconductor is used in an electronic device, an electronic device having excellent characteristics can be obtained as compared with the case where a conventional group III-V compound semiconductor is used.

  Such a group III nitride compound semiconductor is generally manufactured by MOCVD using trimethyl gallium, trimethyl aluminum and ammonia as raw materials. The MOCVD method is a method in which a vapor of a raw material is contained in a carrier gas, transported to the substrate surface, and decomposed by reaction with a heated substrate to grow crystals.

On the other hand, studies have also been carried out to produce a group III nitride compound semiconductor crystal by sputtering. Specifically, for example, a method of forming a GaN layer on the (100) plane of Si and the (0001) plane of Al ₂ O ₃ by high-frequency magnetron sputtering using N ₂ gas has been proposed ( For example, Non-Patent Document 1).

  Further, a method has been proposed in which a GaN layer is formed using an apparatus in which a cathode and a solid target face each other and a mesh is placed between the substrate and the target (for example, Non-Patent Document 2).

Further, when forming a GaN layer made of a group III nitride compound semiconductor crystal as described above, for example, a method of forming a mixed crystal in which a dopant element such as Si or Mg is doped in the GaN layer is used. It is done. At this time, a method of forming a GaN layer by sputtering using a target obtained by mixing a dopant element with a Ga element as a base material has been proposed (for example, Non-Patent Document 3).
Yukiko Ushibuchi (Y. USHIKU) et al., “Proceedings of the 21st Century Union Symposium”, Vol. 2nd, p295 (2003), T. Kikuma et al., “Vacuum”, Vol. 66, P233 (2002) “The 66th Japan Society of Applied Physics” brochure, 7a-N-6, 1 volume, p248 (Autumn 2005)

However, in the conventional sputtering method, when a gallium nitride semiconductor crystal doped with a dopant element is formed, there is a problem that the doping concentration varies if the films are continuously formed. If the doping concentration is not kept constant, a group III nitride compound semiconductor light emitting device having stable characteristics cannot be obtained.
In addition, when AlGaN doped with Mg element is formed as a GaN layer using MOCVD, the amount of Mg taken into the crystal changes depending on the Al composition, so the Al composition is low. In some cases, Mg easily enters, but when the Al composition is high, Mg is difficult to enter.

The present invention has been made in view of the above problems, and can easily optimize the doping concentration of the dopant element in the crystal of the gallium nitride semiconductor, and keep the doping concentration constant even if the films are continuously formed. An object of the present invention is to provide a method for producing a group III nitride compound semiconductor light emitting device capable of producing a group III nitride compound semiconductor light emitting device having stable characteristics.
Furthermore, it aims at providing the group III nitride compound semiconductor light-emitting device and lamp | ramp which are obtained with said manufacturing method.

As a result of intensive investigations to solve the above problems, the present inventors have used a Ga target containing a Ga element and a dopant target made of a dopant element to excite the Ga target by sputtering and simultaneously beam the dopant target. Excited by the charged particles to form a layer made of gallium nitride semiconductor, the doping concentration of the dopant element in the obtained gallium nitride semiconductor layer can be easily optimized and continuously formed Even so, the present inventors have found that the doping concentration can be kept constant and completed the present invention.
That is, the present invention relates to the following.

[1] A method for producing a group III nitride compound semiconductor light-emitting device having a semiconductor layer in which an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer each made of a group III nitride semiconductor are stacked,
Using a Ga target containing Ga element and a dopant target made of a dopant element, the Ga target is excited by sputtering, and the dopant target is excited by charged particles in the form of a beam to at least part of the semiconductor layer Forming a group III nitride compound semiconductor light emitting device.
[2] The method for producing a group III nitride compound semiconductor light-emitting device according to [1], wherein the beam-shaped charged particles are an electron beam or an ion beam.
[3] The method for producing a group III nitride compound semiconductor light-emitting device according to [1] or [2], wherein the n-type semiconductor layer is formed by using Si as the dopant element.
[4] The ratio of Ga element to Si element in the gas phase during the formation of the semiconductor layer is in the range of 1: 0.001 to 1: 0.00001 [3] ] The manufacturing method of the group III nitride compound semiconductor light-emitting device of description.
[5] The method for producing a group III nitride compound semiconductor light-emitting device according to [1] or [2], wherein the p-type semiconductor layer is formed by using Mg as the dopant element.
[6] The ratio of Ga element to Mg element in the gas phase when forming the semiconductor layer is in the range of 1: 0.01 to 1: 0.0001 [5] ] The manufacturing method of the group III nitride compound semiconductor light-emitting device of description.

[7] A group III nitride compound semiconductor light-emitting device obtained by the manufacturing method according to any one of [1] to [6].
[8] A lamp comprising the group III nitride compound semiconductor light-emitting device according to [7].

  The method for producing a group III nitride compound semiconductor according to the present invention uses a Ga target containing a Ga element and a dopant target composed of a dopant element to excite the Ga target by sputtering and to form the dopant target in a beam shape. Since it is excited by charged particles to form at least a part of the semiconductor layer, the doping concentration of the dopant element in the crystal of the semiconductor layer to be formed can be easily optimized. The doping concentration can be kept constant, and a group III nitride compound semiconductor light emitting device having stable characteristics can be manufactured.

  Moreover, the method for producing a group III nitride compound semiconductor of the present invention can efficiently form a film at a higher speed than the case of forming a film by the MOCVD method or the MBE method.

  Furthermore, since the group III nitride compound semiconductor light emitting device and the lamp of the present invention are obtained by the production method of the present invention, they are excellent with stable characteristics.

  Hereinafter, a method for producing a Group III nitride compound semiconductor light emitting device, a Group III nitride compound semiconductor light emitting device, and a lamp according to an embodiment of the present invention will be described with reference to the drawings as appropriate.

[Group III nitride compound semiconductor light emitting device]
FIG. 1 is a schematic cross-sectional view schematically showing an example of a group III nitride compound semiconductor light emitting device according to the present invention. FIG. 2 is a schematic view showing a planar structure of the group III nitride compound semiconductor light emitting device shown in FIG.
As shown in FIG. 1, the light-emitting element of the present embodiment is of a single-sided electrode type, and is a semiconductor made of a group III nitride compound semiconductor containing an intermediate layer 12 and Ga as a group III element on a substrate 11. The layer 20 is formed. As shown in FIG. 1, the semiconductor layer 20 is formed by laminating an n-type semiconductor layer 14, a light emitting layer 15, and a p-type semiconductor layer 16 in this order.

[Laminated structure of light-emitting elements]
<Board>
In the light emitting device 1 of the present embodiment, the material that can be used for the substrate 11 is not particularly limited as long as the group III nitride compound semiconductor crystal is epitaxially grown on the surface, and various materials are selected. Can be used. For example, sapphire, SiC, silicon, zinc oxide, magnesium oxide, manganese oxide, zirconium oxide, manganese zinc iron oxide, magnesium aluminum oxide, zirconium boride, gallium oxide, indium oxide, lithium gallium oxide, lithium aluminum oxide, neodymium gallium oxide Lanthanum strontium oxide aluminum tantalum, strontium titanium oxide, titanium oxide, hafnium, tungsten, molybdenum and the like.

<Intermediate layer>
In the light emitting device 1 of this embodiment, an intermediate layer 12 having a hexagonal crystal structure is formed on a substrate 11.
The group III nitride semiconductor crystal forming the intermediate layer 12 preferably has a single crystal structure. By controlling the growth conditions, the group III nitride semiconductor crystal grows not only in the upward direction but also in the in-plane direction to form a single crystal structure. Therefore, by controlling the film forming conditions of the intermediate layer 12, the intermediate layer 12 made of a crystal of a group III nitride semiconductor having a single crystal structure can be obtained.
When the intermediate layer 12 having such a single crystal structure is formed on the substrate 11, the buffer function of the intermediate layer 12 works effectively, so that the group III nitride semiconductor formed thereon has a good orientation. It becomes a crystal film having the property and crystallinity.

  Further, the group III nitride semiconductor crystal forming the intermediate layer 12 can be formed into a columnar crystal (polycrystal) having a texture based on hexagonal columns by controlling the film forming conditions. In addition, the columnar crystal consisting of the texture here is a crystal that is separated by forming a crystal grain boundary between adjacent crystal grains, and is itself a columnar shape as a longitudinal sectional shape. Say.

  Further, in the intermediate layer 12, the average value of the width of each grain of the columnar crystal is preferably in the range of 0.1 to 100 nm, from the viewpoint of the buffer function, and in the range of 1 to 70 nm. Is more preferable. Here, when the intermediate layer 12 is an aggregate of columnar grains, the grain width means the distance between the crystal interfaces. On the other hand, when the grains are scattered in the form of islands, the grain width means the length of the largest portion of the surface where the crystal grains are in contact with the substrate surface. In order to improve the crystallinity of the crystal layer of the group III nitride compound semiconductor, it is necessary to appropriately control the grain width of each crystal of the columnar crystal. preferable. Moreover, it is preferable that the crystal grains have a substantially columnar shape, and the intermediate layer 12 desirably forms a layer by collecting columnar grains.

 The grain width of each columnar crystal can be easily measured by cross-sectional TEM observation or the like. Note that the width of each columnar crystal cannot be precisely defined, and has a certain width distribution. Therefore, even if there are, for example, several percent of crystals in which the grain width of each columnar crystal is out of the above range, the effect of the present invention is not affected. Further, it is preferable that 90% or more of the grain width of each columnar crystal is in the above range.

Moreover, it is preferable that the intermediate | middle layer 12 is set as the composition containing Al, and can set it as the columnar crystal aggregate efficiently by setting it as the structure which consists of AlN, and is more preferable.
Any material can be used for the intermediate layer 12 as long as it is a group III nitride compound semiconductor represented by the general formula AlGaInN. Furthermore, as V group, it is good also as a structure containing As and P. Further, when the intermediate layer 12 has a composition containing Al, it is preferably GaAlN. In this case, the composition of Al is preferably 50% or more.

Further, the thickness of the intermediate layer 12 is preferably in the range of 10 to 500 nm, and more preferably in the range of 20 to 100 nm.
When the thickness of the intermediate layer 12 is less than 10 nm, the buffer function as described above is not sufficient. In addition, when the intermediate layer 12 is formed with a film thickness exceeding 500 nm, there is a possibility that the film forming process time becomes long and the productivity is lowered although the function as the coat layer is not changed. Note that the film thickness of the intermediate layer 12 can also be easily measured by the cross-sectional TEM photograph as described above.

Further, the intermediate layer 12 needs to cover at least 60% or more, preferably 80% or more, of the surface 11a of the substrate 11, and is preferably formed so as to cover 90% or more. The intermediate layer 12 is most preferably formed so as to cover 100% of the surface 11a, that is, the surface 11a of the substrate 11 without a gap.
When the region where the intermediate layer 12 covers the surface 11a of the substrate 11 is reduced, the substrate 11 is largely exposed. For this reason, the base layer 14a formed on the intermediate layer 12 and the base layer 14a formed directly on the substrate 11 have different lattice constants, resulting in a non-uniform crystal and hillocks and pits. There is a risk.

 In addition, the ratio which the intermediate | middle layer 12 covers the surface 11a of the board | substrate 11 can be measured using a cross-sectional TEM photograph. In particular, when the materials of the intermediate layer 12 and the underlayer 14a are different, the interface between the substrate 11 and the layer on the substrate 11 is scanned in parallel with the surface of the substrate 11 by using EDS or the like. The ratio of the region where 12 is not formed can be estimated. In the present embodiment, the method for measuring the exposed area of the substrate 11 from the cross-sectional TEM photograph has been described. However, a sample in which only the intermediate layer 12 is formed is prepared, and the exposed area of the substrate 11 is obtained by a method such as AFM. Can also be measured.

  Further, the intermediate layer 12 may be formed so as to cover the side surface in addition to the front surface 11 a of the substrate 11, and may further be formed so as to cover the back surface of the substrate 11.

<Semiconductor layer>
As shown in FIG. 1, the semiconductor layer 20 includes an n-type semiconductor layer 14, a light emitting layer 15, and a p-type semiconductor layer 16.
"N-type semiconductor layer"
The n-type semiconductor layer 14 is stacked on the intermediate layer 12, and is composed of a base layer 14a, an n-type contact layer 14b, and an n-type cladding layer 14c. The n-type contact layer can also serve as an underlayer and / or an n-type cladding layer, but the underlayer can also serve as an n-type contact layer and / or an n-type cladding layer. is there.

(Underlayer)
The underlayer 14a of the n-type semiconductor layer 14 of the present embodiment is made of a group III nitride compound semiconductor. The material of the underlayer 14a may be the same as or different from that of the intermediate layer 12, but a group III nitride compound containing Ga, that is, a GaN-based compound semiconductor is preferable, and an Al _X Ga _1-X N layer ( It is more preferable that 0 ≦ x ≦ 1, preferably 0 ≦ x ≦ 0.5, and more preferably 0 ≦ x ≦ 0.1.
For example, when the intermediate layer 12 is an aggregate of columnar crystals made of AlN, the underlayer 14a loops dislocations by migration so that the crystallinity of the intermediate layer 12 that is an aggregate of columnar crystals is not inherited as it is. It is desirable. A GaN-based compound semiconductor tends to cause dislocation looping, and AlGaN or GaN is particularly preferable.

Moreover, the film thickness of the underlayer 14a is preferably 0.1 μm or more, more preferably 0.5 μm or more, and most preferably 1 μm or more. An Al _X Ga _1-X N layer with good crystallinity is more easily obtained when the thickness is increased.

If necessary, the underlayer 14a may be doped with n-type impurities within the range of 1 × 10 ¹⁷ to 1 × 10 ¹⁹ / cm ³ , but undoped (<1 × 10 ¹⁷ / cm ^3). ) And undoped is preferable in terms of maintaining good crystallinity.
For example, when the substrate 11 has conductivity, electrodes can be formed above and below the light emitting element 1 by doping the base layer 14a with a dopant to make it conductive. On the other hand, when an insulating material is used as the substrate 11, a chip structure in which the positive electrode and the negative electrode are provided on the same surface of the light emitting element 1 is employed. It is more preferable that the crystallinity is improved.
Although it does not specifically limit as an n-type impurity, For example, Si, Ge, Sn, etc. are mentioned, Preferably Si and Ge are mentioned.

(N-type contact layer)
The n-type contact layer 14b is made of a group III nitride compound semiconductor. The n-type contact layer 14b is made of an Al _X Ga _1-X N layer (0 ≦ x ≦ 1, preferably 0 ≦ x ≦ 0.5, more preferably 0 ≦ x ≦ 0.1), similarly to the base layer 14a. Preferably, it is configured.
The n-type contact layer 14b is preferably doped with an n-type impurity, and the n-type impurity is preferably 1 × 10 ¹⁷ to 1 × 10 ¹⁹ / cm ³ , preferably 1 × 10 ¹⁸ to 1 × 10 ^19. When it is contained at a concentration of / cm ³ , it is preferable in terms of maintaining good ohmic contact with the negative electrode, suppressing the occurrence of cracks, and maintaining good crystallinity. Although it does not specifically limit as an n-type impurity, For example, Si, Ge, Sn, etc. are mentioned, Preferably it is Si and Ge.

  The gallium nitride compound semiconductor constituting the base layer 14a and the n-type contact layer 14b preferably has the same composition, and the total film thickness thereof is 0.1 to 20 μm, preferably 0.5 to 15 μm, It is preferable to set in the range of 1 to 12 μm. When the film thickness is within this range, the crystallinity of the semiconductor is maintained well.

(N-type cladding layer)
It is preferable to provide an n-type cladding layer 14c between the n-type contact layer 14b and the light emitting layer 15. By providing the n-type cladding layer 14c, it is possible to repair the deterioration of flatness generated on the outermost surface of the n-type contact layer 14b. The n-type cladding layer 14c can be formed of AlGaN, GaN, GaInN, or the like. Alternatively, a heterojunction of these structures or a superlattice structure in which a plurality of layers are stacked may be used. Needless to say, when the n-type cladding layer 14c is made of GaInN, it is preferably larger than the band gap of GaInN of the light emitting layer 15.

The film thickness of the n-type cladding layer 14c is not particularly limited, but is preferably in the range of 5 to 500 nm, more preferably in the range of 5 to 100 nm.
Further, the n-type doping concentration of the n-type cladding layer 14c is preferably in the range of 1 × 10 ¹⁷ to 1 × 10 ²⁰ / cm ³ , more preferably in the range of 1 × 10 ¹⁸ to 1 × 10 ¹⁹ / cm ³ . A doping concentration within this range is preferable in terms of maintaining good crystallinity and reducing the operating voltage of the light emitting element.

<Light emitting layer>
As shown in FIG. 1, the light emitting layer 15 includes a barrier layer 15 a made of a gallium nitride compound semiconductor and a well layer 15 b made of a gallium nitride compound semiconductor containing indium, which are alternately stacked, and n A barrier layer 15a is disposed on the p-type semiconductor layer 14 side and the p-type semiconductor layer 16 side. In the example shown in FIG. 1, the light emitting layer 15 includes six barrier layers 15 a and five well layers 15 b that are alternately and repeatedly stacked, and the barrier layer 15 a is disposed on the uppermost layer and the lowermost layer of the light emitting layer 15. The well layer 15b is arranged between the barrier layers 15a.

As the barrier layer 15a, for example, a gallium nitride-based compound semiconductor such as Al _c Ga _1-c N (0 ≦ c <0.3) having a larger band gap energy than the well layer 15b can be preferably used.
Furthermore, the well layer 15b can be formed using indium as the semiconductor gallium nitride-based compound containing, for _example, can be used _{Ga 1-s In s N (} 0 <s <0.4) GaN such as indium.

  The film thickness of the entire light emitting layer 15 is not particularly limited, but is preferably a film thickness that can obtain a quantum effect, that is, a critical film thickness. For example, the thickness of the light emitting layer 15 is preferably in the range of 1 to 500 nm, and more preferably around 100 nm. When the film thickness is in the above range, it contributes to an improvement in light emission output.

<P-type semiconductor layer>
The p-type semiconductor layer 16 includes a p-type cladding layer 16a and a p-type contact layer 16b. The p-type contact layer may also serve as the p-type cladding layer.

(P-type cladding layer)
The p-type cladding layer 16a is not particularly limited as long as it has a composition larger than the band gap energy of the light emitting layer 15 and can confine carriers in the light emitting layer 15. Preferably, the Al _d Ga _{1-d is used.} N (0 <d ≦ 0.4, preferably 0.1 ≦ d ≦ 0.3). When the p-type cladding layer 16a is made of such AlGaN, it is preferable in terms of confining carriers in the light emitting layer 15.
The thickness of the p-type cladding layer 16a is not particularly limited, but is preferably 1 to 400 nm, and more preferably 5 to 100 nm.

The p-type doping concentration of the p-type cladding layer 16a is preferably 1 × 10 ¹⁸ to 1 × 10 ²¹ / cm ³ , more preferably 1 × 10 ¹⁹ to 1 × 10 ²⁰ / cm ³ . When the p-type dope concentration is in the above range, a good p-type crystal can be obtained without reducing the crystallinity. Although it does not specifically limit as a p-type impurity, For example, Preferably Mg is mentioned.

(P-type contact layer)
The p-type contact layer 16b is a nitride containing at least Al _e Ga _1-e N (0 ≦ e <0.5, preferably 0 ≦ e ≦ 0.2, more preferably 0 ≦ e ≦ 0.1). This is a gallium compound semiconductor layer. When the Al composition is in the above range, it is preferable in terms of maintaining good crystallinity and good ohmic contact with a p-ohmic electrode (see translucent electrode 17 described later).
Although the film thickness of the p-type contact layer 16b is not specifically limited, 10-500 nm is preferable, More preferably, it is 50-200 nm. When the film thickness is within this range, it is preferable in that the light emission output can be kept high.

Further, when the p-type contact layer 16b contains a p-type dopant at a concentration in the range of 1 × 10 ¹⁸ to 1 × 10 ²¹ / cm ³ , good ohmic contact can be maintained, cracking can be prevented, and good It is preferable at the point of crystalline maintenance, More preferably, it is the range of 5 * 10 < ¹⁹ > -5 * 10 < ²⁰ > / cm < ³ >. Although it does not specifically limit as a p-type impurity, For example, Preferably Mg is mentioned.

In addition, the semiconductor layer 20 which comprises the light emitting element 1 of this invention is not limited to the thing of embodiment mentioned above.
For example, as the material of the semiconductor layer constituting the present invention, addition to the foregoing, for example, the general formula _{Al X Ga Y In Z N 1} -A M A (0 ≦ X ≦ 1,0 ≦ Y ≦ 1,0 ≦ Z ≦ 1 and X + Y + Z = 1, a symbol M represents a group V element different from nitrogen (N), and 0 ≦ A <1)) is known. Also in the present invention, these known gallium nitride compound semiconductors can be used without any limitation.
In addition, a group III nitride compound semiconductor containing Ga as a group III element can contain other group III elements in addition to Al, Ga, and In. If necessary, Ge, Si, Mg, Ca, Zn , Be, P, and As can also be contained. Furthermore, it is not limited to the element added intentionally, but may include impurities that are inevitably included depending on the film forming conditions and the like, as well as trace impurities that are included in the raw materials and reaction tube materials.

<Translucent positive electrode>
The translucent positive electrode 17 is an electrode having translucency formed on the p-type semiconductor layer 16.
The material of the translucent positive electrode 17 is not particularly limited, but ITO (In ₂ O ₃ —SnO ₂ ), AZnO (ZnO—Al ₂ O ₃ ), IZO (In ₂ O ₃ —ZnO), GZO (ZnO— A material such as Ga ₂ O ₃ ) can be used. Further, as the translucent positive electrode 17, any structure including a conventionally known structure can be used without any limitation.
The translucent positive electrode 17 may be formed so as to cover the entire surface on the p-type semiconductor layer 16, or may be formed in a lattice shape or a tree shape with a gap.

<Positive electrode bonding pad>
The positive electrode bonding pad 18 is a substantially circular electrode formed on the translucent positive electrode 17 as shown in FIG.
As the material of the positive electrode bonding pad 18, various structures using Au, Al, Ni, Cu and the like are well known, and those known materials and structures can be used without any limitation.
The thickness of the positive electrode bonding pad 18 is preferably in the range of 100 to 1000 nm. Further, in view of the characteristics of the bonding pad, the larger the thickness, the higher the bondability. Therefore, the thickness of the positive electrode bonding pad 18 is more preferably 300 nm or more. Furthermore, it is preferable to set it as 500 nm or less from a viewpoint of manufacturing cost.

<Negative electrode>
The negative electrode 19 is in contact with the n-type contact layer 14 b of the n-type semiconductor layer 14 constituting the semiconductor layer 20. Therefore, as shown in FIGS. 1 and 2, the negative electrode 19 is formed by removing a part of the light emitting layer 15, the p-type semiconductor layer 16, and the n-type semiconductor layer 14 to expose the n-type contact layer 14b. A substantially circular shape is formed on the exposed region 14d.
As materials for the negative electrode 19, negative electrodes having various compositions and structures are well known, and these known negative electrodes can be used without any limitation.

Here, in explaining the manufacturing method of the light emitting element of the present invention, first, the manufacturing apparatus and manufacturing method of the semiconductor layer of the light emitting element will be described.
[Device for manufacturing semiconductor layer of light-emitting element]
FIG. 3 is a schematic view schematically showing an example of a group III nitride compound semiconductor light emitting device manufacturing apparatus according to the present invention. A manufacturing apparatus 40 for a group III nitride compound semiconductor light emitting device (hereinafter sometimes abbreviated as a light emitting device) shown in FIG. 3 is a semiconductor made of a group III nitride compound semiconductor containing Ga as a group III element of the light emitting device. The layer is used to form a film on the substrate 11.

  As shown in FIG. 3, the light emitting element manufacturing apparatus 40 includes a chamber 41, a Ga target 47 a installed in the chamber 41, a power applying unit 45 that applies power for exciting the Ga target 47 a by sputtering, A dopant target 47b made of a dopant element installed in the chamber 41 and a dopant excitation means 46b are provided.

  In addition, as shown in FIG. 3, in the chamber 41 of the light emitting device manufacturing apparatus 40, the substrate 11 is attached to the Ga target 47a and the dopant target 47b so as to face downward, and the substrate 11 is heated. And a heater 44 for conducting the operation. Outside the chamber 41, a matching box 46c conductively connected to the heater 44, a power supply 48 conductively connected to the matching box 46c, and a pressure in the chamber 41 are controlled. Pressure control means 49 a, 49 b, 49 c composed of a pump or the like, and gas supply means 42 a, 42 b for supplying gas into the chamber 41.

  The Ga target 47a contains a Ga element, may be composed of only the Ga element, or may contain other elements, and corresponds to the composition of the semiconductor layer to be deposited. It consists of materials. In particular, a ternary mixed crystal or a quaternary mixed crystal can be formed by mixing a group III element such as Al or In into a target. In the present embodiment, a solid target may be used as the Ga target 47a, or a liquefied one may be used. The liquefied Ga target 47a may be liquefied as a whole or in a state where only the surface layer is liquefied.

  Further, as shown in FIG. 3, the power applying means 45 includes an electrode 43a for supplying power to the Ga target 47a, a matching box 46a conductively connected to the electrode 43a, and a power source conductively connected to the matching box 46a. 48. The power applied to the Ga target 47a can be adjusted by controlling the matching box 46a.

  In the present embodiment, the power (applied power) applied to the Ga target 47a is applied by a pulse DC method or an RF (high frequency) method. In the case where the semiconductor layer is formed by the reactive sputtering method using the manufacturing apparatus 40 shown in FIG. 3, the applied power is set to the RF (high frequency) method because the film formation rate can be easily controlled. More preferred. Further, when the semiconductor layer is formed by the reactive sputtering method using the manufacturing apparatus 40 shown in FIG. 3, the Ga target 47a is charged up when the electric field is continuously applied by DC, and the film formation rate is increased. Therefore, it is preferable to use a pulsed DC system in which the applied power is biased in a pulsed manner.

  The dopant excitation means 46b excites the dopant target 47b with beam-shaped charged particles, and is an electron beam or an ion beam.

  In the light emitting element manufacturing apparatus 40 shown in FIG. 3, examples of the dopant element constituting the dopant target 47b include Si, Ge, Sn, Mg, and the like. In the case of a type semiconductor layer, Si is preferable, and in the case where the semiconductor layer to be formed is a p-type semiconductor layer, Mg is preferable.

[Method for Manufacturing Semiconductor Layer of Light-Emitting Element]
In the present embodiment, a method for forming a semiconductor layer of a light emitting element on a substrate 11 by reactive sputtering will be described as an example of a method for manufacturing a light emitting element using the manufacturing apparatus 40 shown in FIG.
In order to form a semiconductor layer of a light emitting element on the substrate 11 by sputtering using the manufacturing apparatus 40 shown in FIG. 3, first, the pressure in the chamber 41 is set to a predetermined pressure by the pressure control means 49a, 49b, 49c. At the same time, the gas supply means 42a and 42b are used to supply argon gas and an active gas made of a nitride raw material into the chamber 41 at a predetermined supply amount, respectively, so that the chamber 41 has a predetermined atmosphere.

  The pressure in the chamber 41 is preferably 0.3 Pa or higher. If the pressure in the chamber 41 is less than 0.3 Pa, the abundance of nitrogen becomes too small, and the sputtered metal may adhere to the substrate 11 without becoming nitride. Further, the upper limit of the pressure in the chamber 41 is not particularly limited, but it is necessary to suppress the pressure to such a level that plasma can be generated.

Moreover, as a nitride raw material used as an active gas in the present embodiment, generally known nitrogen compounds can be used without any limitation, but ammonia and nitrogen (N ₂ ) are easy to handle. It is preferable because it is relatively inexpensive and available.
Ammonia has good decomposition efficiency and can be deposited at a high growth rate. However, because of its high reactivity and toxicity, it requires a detoxification facility and a gas detector. It is necessary to make these materials chemically stable.
When nitrogen (N ₂ ) is used, a simple apparatus can be used, but a high reaction rate cannot be obtained. However, if the nitrogen is decomposed by an electric field, heat, or the like and then introduced into the apparatus, a sufficient film formation rate that can be used for industrial production can be obtained although the reaction rate is lower than that of ammonia. For this reason, considering the balance with the apparatus cost, nitrogen (N ₂ ) is most preferable as the active gas.

Next, the heater table 44 is heated by heating means (not shown) provided in the heater table 44 so that the substrate 11 has a predetermined temperature, that is, an optimum growth temperature for a semiconductor layer grown on the substrate 11. Warm up.
The temperature of the substrate 11 when forming the semiconductor layer is preferably in the range of room temperature to 1200 ° C, more preferably in the range of 300 to 1000 ° C, and most preferably in the range of 500 to 800 ° C. preferable. In addition, although room temperature here is temperature influenced also by the environment of a process, etc., as specific temperature, it is the range of 0-30 degreeC.
When the temperature of the substrate 11 is lower than the lower limit, migration on the substrate 11 is suppressed, and a crystal of a semiconductor layer with good crystallinity may not be formed. Further, if the temperature of the substrate 11 exceeds the above upper limit, the crystals of the semiconductor layer may be decomposed.

  Then, while the substrate 11 is heated, current is supplied to the electrode 43a through the matching box 46a, power is applied to the Ga target 47a to excite the Ga target 47a, and dopant target by the dopant excitation means 46b. 47b is excited. Further, a current is supplied to the heater base 44 to apply a bias to the substrate 11.

  As a result, particles containing Ga particles are ejected from the Ga target 47a into the gas phase in the chamber 41, and dopant element particles are ejected from the dopant target 47b. Then, Ga particles in the gas phase, dopant element particles and the like are supplied and deposited so as to collide with the surface of the substrate 11 attached to the heater base 44, thereby forming a semiconductor layer on the substrate 11. The

Here, in this embodiment, by changing the amount of Ga and dopant element particles supplied to the gas phase, the Ga element and the dopant element in the gas phase when the semiconductor layer is formed are changed. It is desirable to control the ratio.
Since the amount of Ga and dopant element particles supplied in the gas phase matches the ratio of Ga and dopant element in the crystal of the semiconductor layer to be deposited, Ga and dopant element supplied in the gas phase By controlling the amount of the particles, the doping concentration in the crystal of the semiconductor layer to be formed can be controlled.

When the dopant element is Si, the ratio of Ga element to Si element in the gas phase when the semiconductor layer is formed is (Ga element: Si element) 1: 0.001 to 1: 0. It is desirable to control to be in the range of 00001.
When the dopant element is Mg, the ratio of Ga element to Mg element in the gas phase when the semiconductor layer is formed is (Ga element: Mg element) 1: 0.01 to 1: It is desirable to control to be in the range of 0.0001.

  The amount of Ga element particles in the gas phase during the formation of the semiconductor layer can be adjusted by causing the power source 48 to control the power density applied to the Ga target 47a. In addition, the amount of Ga element particles includes the atmospheric pressure in the chamber 41, the type of gas supplied into the chamber 41, the mixture ratio of the mixed gas when a mixed gas is used as the gas supplied into the chamber 41, Ga It can also be controlled by the intensity of the magnetic field applied to the target 47a, the shape of the magnetic field confining the plasma, the frequency when the applied power is RF, and the duty ratio when the applied power is pulsed DC.

Further, the amount of the dopant element particles in the gas phase during the formation of the semiconductor layer is controlled by the dopant excitation means 46b. The parameters to be controlled are the density, speed, type, charged particle beam cross-sectional area, cross-sectional shape, etc. of charged particles injected into the dopant target 47b.
For example, when the dopant target 47b is excited by an electron beam, the control is mainly performed by the acceleration voltage and the current amount. Further, when the dopant target 47b is excited by an ion beam, the control is mainly performed by the acceleration voltage and the ion density.
A generally used filament or the like is suitable for generating an electron beam. In many cases, the ion beam is generated by plasma cracking of a gas. As an element used for an ion beam, an element having a certain atomic weight and not chemically active is desirable. Examples of the optimum element include rare gases other than He, such as Ne, Ar, Kr, and Xe. If the element has a small atomic weight, the impulse at the time of collision is small, so that the dopant element may not be sufficiently knocked out from the dopant target 47b. Further, when a chemically active element such as oxygen is used as an element used for the ion beam, a film may be formed on the surface of the dopant target 47b.

  Further, when the temperature around the Ga target 47a of the sputtering apparatus 40 when the semiconductor layer is formed is 29 ° C. or higher, Ga is a low melting point metal having a melting point of 29 ° C. May be liquid. Further, when the temperature around the Ga target 47a of the sputtering apparatus 40 when the semiconductor layer is formed is less than 29 ° C., the Ga target 47a becomes solid.

When forming the semiconductor layer, when the Ga target 47a is solid, it is preferable to liquefy at least the surface layer of the Ga target 47a.
As a method for liquefying the Ga target 47a, for example, a method of changing the water temperature by placing the Ga target 47a on a target dish capable of controlling the temperature of the Ga target 47a by circulating water in the pipe, or a heater And a method of irradiating the Ga target 47a with radiant heat when the substrate 11 is heated.

  Further, as another method for liquefying the Ga target 47a, a method of heating the Ga target 47a with a heating means can be mentioned. The heating means used in this case is not particularly limited, and an electric heater or the like can be appropriately selected and used.

Further, in the present embodiment, more it is preferably in the range of power applied to the Ga target 47a of ^{0.1W / cm 2 ~100W / cm 2} , 1W / cm 2 ~50W / cm 2 range ^preferably, and most preferably in the range of ^{1.5W / cm 2 ~50W / cm 2} .
By setting the power applied to the Ga target 47a within the above range, a reactive species having a large power can be generated, and this reactive species can be supplied to the substrate 11 with high kinetic energy. As a result, migration on the substrate 11 becomes active, and it becomes easy to loop dislocations so that the deposited semiconductor layer does not inherit the crystallinity of the underlying layer.

  In the present embodiment, the film formation rate when forming the semiconductor layer is preferably in the range of 0.01 nm / s to 10 nm / s. If the film formation rate is less than 0.01 nm / s, the film formation process takes a long time, and waste is increased in industrial production. Further, when the film formation rate exceeds 10 nm / s, it is difficult to obtain a good film.

  In the manufacturing method of the present embodiment, a Ga target 47a containing a Ga element and a dopant target 47b made of a dopant element are used to excite the Ga target 47a by sputtering, and at the same time, the dopant target 47b is an electron beam or an ion beam. Since at least a part of the semiconductor layer is formed by being excited by the dopant excitation means 46b that generates charged particles in the form of a beam, the doping concentration of the dopant element in the crystal of the semiconductor layer to be formed can be easily optimized. Even if the films are continuously formed, the doping concentration can be kept constant, and a group III nitride compound semiconductor light emitting device having stable characteristics can be manufactured.

In addition, the manufacturing method of the present embodiment can increase the film formation rate compared to the case where the film is formed by the MOCVD method or the MBE method, and the film can be formed efficiently at high speed. Further, by reducing the manufacturing time, impurities can be prevented from entering the chamber to a minimum, and a good semiconductor layer with little contamination can be obtained.
Further, in the manufacturing method of the present embodiment, since the reactive sputtering method for supplying an active gas made of a nitride material into the chamber is used, the crystallinity of the obtained semiconductor layer becomes good and uniform.

Further, in the manufacturing method of the present embodiment, when at least the surface layer of the Ga target 47a is liquefied, particles having high energy can be taken out and supplied onto the substrate 11, so that the crystallinity is good on the substrate 11. A semiconductor layer made of a group III nitride semiconductor can be grown with higher efficiency.
Further, when at least the surface layer of the Ga target 47a is liquefied, the Ga target 47a can be used uniformly without being partially biased, so that the material constituting the Ga target 47a can be used efficiently. .

  In the manufacturing method of the present embodiment, the reactive sputtering method for supplying an active gas made of a nitride material into the chamber has been described as an example, but the present invention is not limited to the reactive sputtering method. .

[Method for Manufacturing Light-Emitting Element]
In order to manufacture the light emitting element 1 shown in FIG. 1, first, the laminated semiconductor 10 shown in FIG. 4 in which the semiconductor layer 20 is formed is formed on the substrate 11. In order to form the laminated semiconductor 10 shown in FIG. 4, first, the substrate 11 is prepared. It is desirable to use the substrate 11 after pretreatment.
As the pretreatment of the substrate 11, for example, when the substrate 11 made of silicon is used as the substrate 11, a wet method such as a well-known RCA cleaning method is performed and the surface is hydrogen-terminated. be able to. This stabilizes the film forming process.

Further, the pretreatment of the substrate 11 may be performed, for example, by a method in which the substrate 11 is placed in a chamber of a sputtering apparatus and sputtering is performed before the intermediate layer 12 is formed. Specifically, a pretreatment for cleaning the surface can be performed by exposing the substrate 11 to plasma of Ar or N _{2 in} the chamber. By causing plasma such as Ar gas or N ₂ gas to act on the surface of the substrate 11, organic substances and oxides attached to the surface of the substrate 11 can be removed. In this case, if a voltage is applied between the substrate 11 and the chamber without applying power to the target, the plasma particles efficiently act on the substrate 11.

After pre-processing the substrate 11, the intermediate layer 12 shown in FIG. 4 is formed on the substrate 11 by sputtering.
Then, in accordance with the semiconductor layer manufacturing method described above, the reactive sputtering method using the light emitting element manufacturing apparatus 40 shown in FIG. 3 described above is performed on the substrate 11 on which the intermediate layer 12 is formed as shown in FIG. A base layer 14a and an n-type contact layer 14b of the n-type semiconductor layer 14 are continuously formed.

  First, the manufacturing apparatus 40 shown in FIG. 3 in which the substrate 11 on which the intermediate layer 12 is formed, the Ga target 47a, and the dopant target 47b made of a dopant element are installed in the chamber 41 is prepared. The dopant element here is an n-type impurity such as Si, Ge, or Sn used when forming the n-type contact layer 14b or when forming the base layer 14a and the n-type contact layer 14b.

Next, the pressure in the chamber 41 is set to a predetermined pressure, and an argon gas and an active gas made of a nitride raw material are supplied into the chamber 41 at predetermined supply amounts, respectively, and a chamber for forming the base layer 14a is formed. The inside of 41 is set to a predetermined atmosphere, and the substrate 11 is heated to a predetermined temperature.
Here, it is preferable that the temperature of the substrate 11 when forming the base layer 14a, that is, the growth temperature of the base layer 14a, be 800 ° C. or higher. This is because by increasing the temperature of the substrate 11 when forming the base layer 14a, atom migration is easily caused, and dislocation looping easily proceeds. Note that the temperature of the substrate 11 when forming the base layer 14a needs to be lower than the temperature at which the crystal decomposes, and is preferably less than 1200 ° C. If the temperature of the substrate 11 when forming the underlayer 14a is within the above temperature range, the underlayer 14a with good crystallinity can be obtained.

  Here, when an undoped semiconductor layer is formed as the base layer 14a, the Ga target 47a is sputtered by introducing predetermined power into the Ga target 47a and the chamber 41 without exciting the dopant target 47b. A bias voltage is applied between the heater base 44 supporting the substrate 11 and the ground, and simultaneously the heater is energized to heat the substrate 11, and the intermediate layer 12 of the substrate 11 is heated at a predetermined film formation rate. A base layer 14a is formed.

  In addition, when a doped semiconductor layer is formed as the underlayer 14a, a predetermined power is introduced into the Ga target and the chamber to perform sputtering of the Ga target, and the dopant target 47b is excited by the dopant excitation means 46b. A bias voltage is applied between the heater base 44 supporting the substrate 11 and the ground, and simultaneously the heater is energized to heat the substrate 11 so that the base layer 14a is formed on the intermediate layer 12 at a predetermined film formation rate. Is deposited.

  The amount of dopant element particles in the gas phase during the formation of the underlayer 14a is controlled by the dopant excitation means 46b.

  Subsequently, in the same manner as when the base layer 14a made of a doped semiconductor layer is formed, the inside of the chamber 41 is set to a predetermined atmosphere for forming the n-type contact layer 14b, and the base layer 14a is formed. The substrate 11 is heated to a predetermined temperature. The deposition temperature of the n-type contact layer 14b is the same as that of the base layer 14a. Then, similarly to the case where the underlayer 14a made of a doped semiconductor layer is formed, the Ga target 47a and the dopant target 47b are excited to form an n-type contact on the underlayer 14a of the substrate 11 at a predetermined film formation rate. Layer 14b is deposited.

  The amount of dopant element particles in the gas phase during the formation of the n-type contact layer 14b is controlled by the dopant excitation means 46b.

  It is to be noted that the base layer 14a is a doped semiconductor layer, and the base layer 14a and the n-type contact layer 14b have the same Ga target 47a and dopant target 47b, or the base layer 14a is an undoped semiconductor. When the Ga target 47a used is the same for the underlayer 14a and the n-type contact layer 14b, the underlayer 14a and the n-type contact layer 14b can be continuously formed. Although preferable, the Ga target 47a and the dopant target 47b to be used may be different between the base layer 14a and the n-type contact layer 14b.

  Next, the n-type cladding layer 14c of the n-type semiconductor layer 14, the light-emitting layer 15 including the barrier layer 15a and the well layer 15b, and the p-type cladding layer 16a of the p-type semiconductor layer 16 are preferably MOCVD from the viewpoint of film thickness controllability. The film is formed by the (metal organic chemical vapor deposition method) method.

In the MOCVD method, hydrogen (H ₂ ) or nitrogen (N ₂ ) as a carrier gas, trimethyl gallium (TMG) or triethyl gallium (TEG) as a Ga source which is a group III source, trimethyl aluminum (TMA) or triethyl aluminum as an Al source (TEA), trimethylindium (TMI) or triethylindium (TEI) as an In source, ammonia (NH ₃ ), hydrazine (N ₂ H ₄ ), or the like as an N source that is a group V source.

In addition, as the n-type impurity of the dopant element, monosilane (SiH ₄ ) or disilane (Si ₂ H ₆ ) is used as a Si raw material, germane gas (GeH ₄ ) is used as a Ge raw material, and tetramethyl germanium ((CH ₃ ) ₄ Ge ) And tetraethylgermanium ((C ₂ H ₅ ) ₄ Ge) can be used.
For the n-type impurity of the dopant element, for example, biscyclopentadienylmagnesium (Cp ₂ Mg) or bisethylcyclopentadienylmagnesium (EtCp ₂ Mg) can be used as the Mg raw material.

  Next, the p-type contact layer 16b of the p-type semiconductor layer 16 is formed on the p-type cladding layer 16a of the p-type semiconductor layer 16 by reactive sputtering using the above-described light emitting device manufacturing apparatus 40 shown in FIG. To do.

  The p-type contact layer 16b of the p-type semiconductor layer 16 is performed using a p-type impurity such as Mg as a dopant element of the dopant target 47b. More specifically, the inside of the chamber 41 is set to a predetermined atmosphere for forming the p-type contact layer 16b, and the substrate 11 on which the layers up to the p-type cladding layer 16a are formed is heated to a predetermined temperature. Then, a predetermined current is supplied to the electrode 43a through the matching box 46a, power is applied to the Ga target 47a to excite the Ga target 47a, and the dopant target 47b is excited by the dopant excitation means 46b. Further, a current is supplied to the heater base 44, a bias is applied to the substrate 11, and the p-type contact layer 16b is formed at a predetermined film formation rate.

  Here, the amount of the dopant element particles in the gas phase when the p-type contact layer 16b is formed is controlled by the dopant excitation means 46b.

The translucent positive electrode 17 and the positive electrode bonding pad 18 are sequentially formed on the p-type contact layer 16b of the laminated semiconductor 10 shown in FIG. 4 thus obtained by using a photolithography method.
Next, the exposed region 14d on the n-type contact layer 14b is exposed by dry etching the laminated semiconductor 10 on which the translucent positive electrode 17 and the positive electrode bonding pad 18 are formed.
Thereafter, the negative electrode 19 is formed on the exposed region 14d using a photolithography method, whereby the light emitting device 1 shown in FIGS. 1 and 2 is obtained.

In the light emitting device of this embodiment, among the semiconductor layers 20, the base layer 14a and the n type contact layer 14b of the n type semiconductor layer 14 and the p type contact layer 16b of the p type semiconductor layer 16 are shown in FIG. Since the film is formed by the above-described sputtering method using this manufacturing apparatus, the productivity is excellent.
In addition, the light emitting device of this embodiment is a layer made of a doped semiconductor layer among the base layer 14a and the n-type contact layer 14b of the n-type semiconductor layer 14 and the p-type contact layer 16b of the p-type semiconductor layer 16. In this case, the doping concentration of the dopant element in the crystal is the optimum concentration. Therefore, the light emitting device 1 of the present embodiment has stable characteristics.

  In the manufacturing method of the present embodiment, the base layer 14a and the n-type contact layer 14b of the n-type semiconductor layer 14 are formed by sputtering. For this reason, while being able to make a manufacturing facility simple and cheap, it can produce stably and the outstanding reproducibility is obtained.

In the present embodiment, only the base layer 14a and the n-type contact layer 14b of the n-type semiconductor layer 14 and the p-type contact layer 16b of the p-type semiconductor layer 16 among the semiconductor layers 20 of the light emitting element 1 are shown in FIG. However, the present invention is not limited to the above-described example, and at least a part of the semiconductor layer 20 is formed by the sputtering method of the present invention. It only has to be.
For example, in the present embodiment, the n-type cladding layer 14c of the n-type semiconductor layer 14 and the p-type cladding layer 16a of the p-type semiconductor layer 16 are formed by MOCVD, but the n-type cladding layer 14c and the p-type cladding layer 16a are formed. Can also be formed by the sputtering method of the present invention.

  The light-emitting element 1 of the present invention only needs to be formed at least part of the semiconductor layer 20 by the sputtering method of the present invention. The semiconductor layer 20 is formed by the sputtering method of the present invention and the conventional method. Performed in combination with any method capable of growing a semiconductor layer, such as sputtering, MOCVD (metal organic chemical vapor deposition), HVPE (hydride vapor deposition), MBE (molecular beam epitaxy), etc. May be.

  The group III nitride compound semiconductor of the present invention can be used for a photoelectric conversion element such as a laser element or a light receiving element, or an electronic device such as HBT or HEMT, in addition to the above light emitting element. Many of these semiconductor devices have various structures, and the structure of the group III nitride compound semiconductor light emitting device according to the present invention is not limited at all including these known device structures.

[lamp]
The lamp of the present invention uses the light emitting device of the present invention.
As a lamp | ramp of this invention, the thing formed by combining the light emitting element of this invention and fluorescent substance can be mentioned, for example. A lamp in which a light emitting element and a phosphor are combined can have a configuration well known to those skilled in the art by means well known to those skilled in the art. Conventionally, a technique for changing the emission color by combining a light emitting element and a phosphor is known, and such a technique can be adopted in the lamp of the present invention without any limitation.

  For example, by appropriately selecting the phosphor used for the lamp, it becomes possible to obtain light emission having a longer wavelength than the light emitting element, and by mixing the emission wavelength of the light emitting element itself with the wavelength converted by the phosphor. A lamp that emits white light can also be used.

  FIG. 5 is a schematic view schematically showing an example of a lamp configured using the group III nitride compound semiconductor light emitting device according to the present invention. The lamp 3 shown in FIG. 5 is a cannonball type, and the light emitting element 1 shown in FIG. 3 is used. As shown in FIG. 5, the positive electrode bonding pad (see reference numeral 18 shown in FIG. 3) of the light emitting element 1 is bonded to one of the two frames 31 and 32 (the frame 31 in FIG. 5) with a wire 33 to emit light. The light emitting element 1 is mounted by joining the negative electrode of the element 1 (see reference numeral 19 shown in FIG. 2) to the other frame 32 with a wire 34. The periphery of the light emitting element 1 is sealed with a mold 35 made of a transparent resin.

Since the lamp of the present invention uses the light emitting device of the present invention, the lamp is excellent in productivity and has excellent light emission characteristics.
Further, the lamp of the present invention can be used for any purpose such as a bullet type for general use, a side view type for portable backlight use, and a top view type used for a display.

  EXAMPLES Next, although an Example and a comparative example are shown and this invention is demonstrated in detail, this invention is not limited only to these Examples.

[Example 1]
Using the light emitting device manufacturing apparatus 40 shown in FIG. 3, the laminated semiconductor 10 shown in FIG. 4 was manufactured as follows, and the light emitting device shown in FIGS. 1 and 2 was manufactured.
First, a substrate 11 made of mirror-polished sapphire was prepared, and the following pretreatment was performed. That is, the substrate 11 is placed in a chamber of a sputtering apparatus in which a target made of metal Al for forming the intermediate layer 12 is installed, and the substrate 11 is heated to 500 ° C., and nitrogen gas is supplied at a flow rate of 15 sccm. Then, the pressure in the chamber is maintained at 1.0 Pa, a high frequency bias of 50 W is applied to the substrate 11 side without applying power to the target, and the surface of the substrate 11 is cleaned by exposure to nitrogen plasma. did.

After the pretreatment, the pressure in the chamber is set to 0.5 Pa, and 5 sccm of argon gas and 15 sccm of nitrogen gas are circulated in the chamber (the ratio of nitrogen in the whole gas is 75%) to form the intermediate layer 12. And the atmosphere. Next, the substrate 11 is heated to 500 ° C., a power of 1 W / cm ² is applied to the metal Al target without applying a bias to the substrate 11, and the substrate is formed at a film formation rate of 0.12 nm / s by sputtering. An intermediate layer 12 having a thickness of 50 nm and having a single crystal structure of AlN was formed on the substrate 11.

  Next, the substrate 11 on which the intermediate layer 12 is formed is taken out from the sputtering apparatus, and the base layer 14a made of undoped GaN and Si are doped by reactive sputtering using the light emitting element manufacturing apparatus 40 shown in FIG. An n-type contact layer 14b made of a GaN layer was continuously formed.

First, the substrate 11 on which the intermediate layer 12 was formed, the Ga target 47a, and the dopant target 47b made of Si were installed in the chamber 41 of the manufacturing apparatus 40 shown in FIG.
Next, the pressure in the chamber 41 is set to 0.5 Pa, and 5 sccm of argon gas and 15 sccm of nitrogen gas are circulated in the chamber 41 (ratio of nitrogen in the whole gas is 75%), and the base layer 14a and the n-type contact layer An atmosphere for forming a film 14b was used.

Next, the substrate 11 is heated to 1000 ° C., and a current is supplied to the electrode 43a through the matching box 46a while moving the position where the magnetic field is applied by sweeping the magnet into the Ga target 47a. / Cm ² power is applied, a current is supplied to the heater base 44 to apply an RF (radio frequency) bias of 0.5 W / cm ² to the substrate 11, and a film thickness of 6 μm is formed on the substrate 11 at a deposition rate of 1 nm / s. A base film 14a was formed by forming a film.

Thereafter, a current is supplied to the electrode 43a through the matching box 46a, 1 W / cm ² of power is applied to the Ga target 47a to excite the Ga target 47a, and Ar gas is circulated through the plasma cracker cell. Positive ions were generated. The generation of Si was started by irradiating this Ar ion with an electromagnet installed around a dopant target 47b made of Si excited by passing a current and irradiating the dopant target 47b. Furthermore, by supplying an electric current to the heater base 44 and applying an RF (high frequency) bias of 0.5 W / cm ² to the substrate 11, a film thickness of 2 μm is formed on the underlayer 14 a at a film formation rate of 1 nm / s, An n-type contact layer 14b made of a GaN layer doped with Si was obtained.

  Note that the amount of dopant element particles in the gas phase during the formation of the n-type contact layer 14b is such that the ratio of Ga element to Si element (Ga element: Si element) was controlled to be 4000: 1.

Here, the Si concentration in the obtained n-type contact layer 14b was examined by general secondary ion mass spectroscopy (abbreviation: SIMS).
As a result, it was confirmed that Si was doped at a concentration of 1 × 10 ¹⁹ cm ⁻³ (Ga: Si = 4000: 1).
Therefore, the n-type contact layer 14b to be formed is controlled by controlling the amount of the dopant element particles in the gas phase when the n-type contact layer 14b is formed by the dopant excitation means 46b made of an ion beam. It was confirmed that the doping concentration in the crystal can be controlled.

Next, the substrate 11 on which the layers up to the n-type contact layer 14b are formed is introduced into a MOCVD furnace, and the n-type cladding layer 14c and the barrier layer 15a of the n-type semiconductor layer 14 are formed on the n-type contact layer 14b. A light emitting layer 15 composed of the well layer 15b and a p-type cladding layer 16a of the p-type semiconductor layer 16 were formed.
First, a 20 nm In _0.1 Ga _0.9 N-type cladding layer (n-type cladding layer 14c) having an electron concentration of 1 × 10 ¹⁸ cm ⁻³ was formed on the n-type contact layer 14b.
Subsequently, the n-type cladding layer 14c has a laminated structure including a barrier layer 15a that starts at the barrier layer 15a and ends at the barrier layer 15a, and a well layer 15b, and is composed of GaN having a thickness of 16 nm. A light emitting layer (multiple quantum well structure) 15 in which barrier layers 15a of layers and five well layers 15b made of In _0.2 Ga _0.8 N with a thickness of each layer of 3 nm are alternately stacked. A film was formed.
Thereafter, a 5 nm p-type cladding layer 16 a made of Al _0.1 Ga _0.9 N doped with Mg was formed on the light emitting layer 15.

  Next, the substrate 11 on which the layers up to the p-type cladding layer 16a of the p-type semiconductor layer 16 are formed is taken out of the MOCVD furnace and placed in the chamber 41 of the light emitting device manufacturing apparatus 40 shown in FIG. The p-type contact layer 16b of the p-type semiconductor layer 16 was formed by the method.

In forming the p-type contact layer 16b of the p-type semiconductor layer 16, a dopant target 47b made of Mg was used.
Then, a current is supplied to the electrode 43a through the matching box 46a, 1 W / cm ² of power is applied to the Ga target 47a to excite the Ga target 47a, and Ar gas is circulated through the plasma cracker cell. Positive ions were generated. The Ar ions were guided by an electromagnet installed around a dopant target 47b made of Mg that was excited by passing a current and irradiated to the dopant target 47b, thereby starting the generation of Mg. Further, a current is supplied to the heater base 44 to apply an RF (radio frequency) bias of 0.5 W / cm ² to the substrate 11 to form a film of 200 nm on the p-type cladding layer 16a at a film formation rate of 1 nm / s. As a result, a p-type contact layer 16b made of an Al _0.02 Ga _0.98 N layer doped with Mg was formed, and the laminated semiconductor 10 shown in FIG. 4 was obtained.

  Note that the amount of dopant element particles in the gas phase during the formation of the p-type contact layer 16b is such that the ratio of Ga element to Mg element (Ga element: The Mg element was controlled to be 400: 1.

Here, the Mg concentration in the obtained p-type contact layer 16b was examined by general SIMS. As a result, it was confirmed that Mg was doped at a concentration of 1 × 10 ²⁰ cm ⁻³ (Ga: Mg = 400: 1).
Therefore, by controlling the amount of dopant element particles in the gas phase when the p-type contact layer 16b is formed by the dopant excitation means 46b made of an ion beam, the p-type contact layer 16b is formed. It was confirmed that the doping concentration in the crystal can be controlled.

On the p-type contact layer 16b of the laminated semiconductor 10 shown in FIG. 4 thus obtained, a light-transmitting positive electrode 17 made of ITO and titanium, aluminum, and gold are laminated in this order from the surface side using a photolithography method. A positive electrode bonding pad 18 having the above structure was sequentially formed.
Next, dry etching is performed on the laminated semiconductor 10 on which the translucent positive electrode 17 and the positive electrode bonding pad 18 are formed to expose the exposed region 14d on the n-type contact layer 14b, and a photolithography method is performed on the exposed region 14d. Using this, a negative electrode 19 composed of four layers of Ni, Al, Ti, and Au was formed, and the light emitting device 1 shown in FIGS. 1 and 2 was obtained.

  The back side of the substrate 11 of the light-emitting element 1 thus obtained was ground and polished to form a mirror-like surface, which was cut into a 350 μm square to obtain a chip. Then, the chip was placed on the lead frame with the electrode facing up, and was connected to the lead frame with a gold wire to obtain a light emitting diode.

A forward current was passed between the positive electrode bonding pad 18 and the negative electrode 19 of the light-emitting diode thus obtained.
As a result, the forward voltage at a current of 20 mA was 3.0V. Moreover, when the light emission state was observed through the translucent positive electrode 17 on the p-type semiconductor layer 16 side, the light emission wavelength was 460 nm and the light emission output was 15 mW.
Thus, it was confirmed that the light-emitting element 1 of Example 1 had excellent light emission characteristics.

[Example 2]
Using the light emitting device manufacturing apparatus shown in FIG. 3, the laminated semiconductor 10 shown in FIG. 4 was manufactured as follows, and the light emitting device shown in FIGS. 1 and 2 was manufactured.
First, the intermediate layer 12 was formed on the same substrate 11 as in Example 1 in the same manner as in Example 1. Then, an underlying layer 14a made of undoped GaN and a Si-doped GaN layer are formed on the substrate 11 on which the intermediate layer 12 is formed by reactive sputtering using the light emitting device manufacturing apparatus 40 shown in FIG. The n-type contact layer 14b made of was continuously formed.
At this time, unlike Example 1, an electron beam was used as the dopant excitation means 46b.

  The amount of the dopant element particles in the gas phase during the formation of the n-type contact layer 14b is such that the ratio of Ga element to Si element (Ga element: Si element) was controlled to be 4000: 1.

Here, the Si concentration in the obtained n-type contact layer 14b was examined by general SIMS. As a result, it was confirmed that Si was doped at a concentration of 1 × 10 ¹⁹ cm ⁻³ (Ga: Si = 4000: 1).
Therefore, the n-type contact layer 14b to be formed is controlled by controlling the amount of the dopant element particles in the gas phase when the n-type contact layer 14b is formed by the dopant excitation means 46b made of an electron beam. It was confirmed that the doping concentration in the crystal can be controlled.

  Next, in the same manner as in Example 1, the n-type cladding layer 14c, the barrier layer 15a, and the well layer 15b of the n-type semiconductor layer 14 are formed on the substrate 11 on which the layers up to the n-type contact layer 14b are formed. The light emitting layer 15 and the p-type cladding layer 16a of the p-type semiconductor layer 16 were formed.

Next, the substrate 11 on which the layers up to the p-type cladding layer 16a of the p-type semiconductor layer 16 are formed is taken out of the MOCVD furnace and placed in the chamber 41 of the light emitting device manufacturing apparatus 40 shown in FIG. The p-type contact layer 16b of the p-type semiconductor layer 16 was formed by the same method as in Example 1 to obtain the laminated semiconductor 10 shown in FIG.
Here, the p-type contact layer 16b of the p-type semiconductor layer 16 was made of Mg as the dopant target 47b, as in Example 1. However, unlike Example 1, an electron beam was used as the dopant excitation means 46b.

  Note that the amount of dopant element particles in the gas phase during the formation of the p-type contact layer 16b is such that the ratio of Ga element to Mg element (Ga element: Mg element) was controlled to be 400: 1.

Here, the Mg concentration in the obtained p-type contact layer 16b was examined by general SIMS. As a result, it was confirmed that Mg was doped at a concentration of 1 × 10 ²⁰ cm ⁻³ (Ga: Mg = 400: 1).
Accordingly, the p-type contact layer 16b is formed by controlling the amount of the dopant element particles in the gas phase when the p-type contact layer 16b is formed by the dopant excitation means 46b made of an electron beam. It was confirmed that the doping concentration in the crystal can be controlled.

Using the laminated semiconductor 10 shown in FIG. 4 thus obtained, the light-emitting device 1 shown in FIGS. 1 and 2 was manufactured in the same manner as in Example 1. As in Example 1, the light-emitting diode and did.
A forward current was passed between the positive electrode bonding pad 18 and the negative electrode 19 of the light emitting diode thus obtained.
As a result, the forward voltage at a current of 20 mA was 3.2V. Further, when the light emission state was observed through the light transmitting positive electrode 17 on the p-type semiconductor layer 16 side, the light emission wavelength was 460 nm and the light emission output was 16.5 mW).
Thus, it was confirmed that the light-emitting element 1 of Example 2 had excellent light emission characteristics.

[Example 3]
Using the light emitting device manufacturing apparatus 40 shown in FIG. 3, the laminated semiconductor 10 shown in FIG. 4 was manufactured as follows, and the light emitting device shown in FIGS. 1 and 2 was manufactured.
In Example 3, the laminated semiconductor 10 was produced in the same manner as in Example 1 except for the conditions for pretreatment of the substrate 11 and the conditions for forming the intermediate layer 12.

  The pretreatment of the substrate 11 was performed as follows by preparing a substrate 11 made of mirror-polished sapphire. That is, the substrate 11 is placed in a chamber of a sputtering apparatus in which a target made of metal Al for forming the intermediate layer 12 is installed, and the substrate 11 is heated to 750 ° C., and nitrogen gas is supplied at a flow rate of 15 sccm. After the introduction, the pressure inside the chamber is kept at 0.08 Pa, and a high frequency bias of 50 W is applied to the substrate 11 side without applying power to the target, and the surface of the substrate 11 is cleaned by exposure to nitrogen plasma. did.

After the pretreatment, the pressure in the chamber is set to 0.5 Pa, and 15 sccm of argon gas and 5 sccm of nitrogen gas are circulated in the chamber (the ratio of nitrogen in the whole gas is 25%) to form the intermediate layer 12. And the atmosphere. Next, the substrate 11 is heated to 500 ° C., a power of 1 W / cm ² is applied to the metal Al target without applying a bias to the substrate 11, and the substrate is formed at a film formation rate of 0.12 nm / s by sputtering. An intermediate layer 12 having a thickness of 50 nm made of an aggregate of AlN columnar crystals (polycrystal) was formed on the substrate 11.

Using the laminated semiconductor 10 shown in FIG. 4 obtained in Example 3, the light-emitting device 1 shown in FIGS. 1 and 2 is manufactured in the same manner as in Example 1. did.
A forward current was passed between the positive electrode bonding pad 18 and the negative electrode 19 of the light emitting diode thus obtained.
As a result, the forward voltage at a current of 20 mA was 3.0V. Moreover, when the light emission state was observed through the translucent positive electrode 17 on the p-type semiconductor layer 16 side, the light emission wavelength was 460 nm and the light emission output was 15 mW.
Thus, it was confirmed that the light-emitting element 1 of Example 3 had excellent light emission characteristics.

[Comparative example]
Implementation was performed except that the n-type contact layer 14b constituting the semiconductor layer 20 of the light-emitting element 1 and the p-type contact layer 16b of the p-type semiconductor layer 16 were formed using a sputtering apparatus provided with only one target. In the same manner as in Example 1, the laminated semiconductor 10 shown in FIG. 4 was manufactured to obtain a light emitting diode.
The n-type contact layer 14b is formed using a target in which a dopant element is mixed with a Ga element at a predetermined ratio (Ga: Si = 1: 0.0075), and the p-type contact layer 16b is formed. For this, a target in which a dopant element was mixed with Ga element at a predetermined ratio (Ga: Mg = 1: 0.023) was used.

In the comparative example, the characteristics of the obtained light emitting diode were not stably obtained.
In contrast, in Examples 1 to 3, light emitting diodes having stable characteristics were obtained.
This is because in the comparative example, since the distribution of the dopant dispersed in the target is not constant, the doping concentrations of the n-type contact layer 14b and the p-type contact layer 16b of the light-emitting element 1 formed continuously are not constant. On the other hand, in Examples 1 to 3, it is considered that the doping concentration of the n-type contact layer 14b and the p-type contact layer 16b of the light-emitting element 1 formed continuously is constant. .

  The group III nitride compound semiconductor light-emitting device obtained by the present invention has a group III nitride compound semiconductor layer having good crystallinity and has excellent light emission characteristics. Therefore, a semiconductor element such as a light emitting diode, a laser diode, or an electronic device having excellent light emission characteristics can be manufactured.

FIG. 1 is a schematic cross-sectional view schematically showing an example of a group III nitride compound semiconductor light emitting device according to the present invention. FIG. 2 is a schematic diagram showing a planar structure of the group III nitride compound semiconductor light-emitting device shown in FIG. FIG. 3 is a schematic view schematically showing an example of a group III nitride compound semiconductor light emitting device manufacturing apparatus according to the present invention. FIG. 4 is a view for explaining the manufacturing method of the group III nitride compound semiconductor light-emitting device shown in FIG. 1, and is a schematic cross-sectional view schematically showing a laminated semiconductor. FIG. 5 is a schematic view schematically showing an example of a lamp configured using the group III nitride compound semiconductor light emitting device according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Group III nitride compound semiconductor light emitting element (light emitting element), 3 ... Lamp, 10 ... Multilayer semiconductor, 11 ... Substrate, 11a ... Surface, 12 ... Intermediate layer, 13 ... Underlayer, 14 ... N-type semiconductor layer, 15 DESCRIPTION OF SYMBOLS ... Light emitting layer, 16 ... p-type semiconductor layer, 17 ... Translucent positive electrode, 40 ... Manufacturing apparatus, 41 ... Chamber, 43a ... Electrode, 45 ... Power application means, 46a ... Matching box, 46b ... Dopant excitation means, 47a ... Ga target, 47b ... dopant target.

Claims (8)

A method of manufacturing a group III nitride compound semiconductor light emitting device having a semiconductor layer in which an n-type semiconductor layer, a light emitting layer, and a p type semiconductor layer each made of a group III nitride semiconductor are stacked,
Using a Ga target containing Ga element and a dopant target made of a dopant element, the Ga target is excited by sputtering, and the dopant target is excited by charged particles in the form of a beam to at least part of the semiconductor layer Forming a group III nitride compound semiconductor light emitting device.   2. The method for producing a group III nitride compound semiconductor light-emitting device according to claim 1, wherein the beam-shaped charged particles are an electron beam or an ion beam.   The method for producing a group III nitride compound semiconductor light-emitting device according to claim 1, wherein the n-type semiconductor layer is formed by using Si as the dopant element.   The ratio of Ga element and Si element in the gas phase when forming the semiconductor layer is in the range of 1: 0.001 to 1: 0.00001. A method for producing a Group III nitride compound semiconductor light-emitting device of   The method for producing a group III nitride compound semiconductor light-emitting element according to claim 1, wherein the p-type semiconductor layer is formed by using Mg as the dopant element.   6. The ratio of Ga element to Mg element in the gas phase when forming the semiconductor layer is in the range of 1: 0.01 to 1: 0.0001. A method for producing a Group III nitride compound semiconductor light-emitting device of   A group III nitride compound semiconductor light-emitting device obtained by the manufacturing method according to claim 1.   A lamp comprising the group III nitride compound semiconductor light-emitting device according to claim 7.

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