JP2008311420A - Sputter target manufacturing method, sputter target, sputtering apparatus, group III nitride compound semiconductor light emitting device, group III nitride compound semiconductor light emitting device, and lamp - Google Patents

Abstract

The present invention provides a method for manufacturing a sputter target that can easily optimize the doping concentration of a dopant element in a crystal of a gallium nitride semiconductor formed by sputtering.
A sputtering target manufacturing method including a mixing step of mixing liquid Ga and a dopant element. The mixing step can be a step of dissolving the dopant element in the liquid Ga. Further, the mixing step may be a step of solidifying after dispersing the particulate dopant element in the liquid Ga.
[Selection figure] None

Description

  The present invention relates to a sputter target, a sputter target manufacturing method, a sputter target, and a sputter target that are preferably used for manufacturing a group III nitride compound semiconductor light-emitting element that is preferably used for a light emitting diode (LED), a laser diode (LD), an electronic device, and the like. The present invention relates to a device, a method for manufacturing a group III nitride compound semiconductor light emitting device, a group III nitride compound semiconductor light emitting device obtained by this manufacturing method, and a lamp using the group III nitride compound semiconductor light emitting device.

Group III nitride semiconductor light-emitting devices have a direct transition type band gap of energy corresponding to the range from visible light to ultraviolet light, and are excellent in luminous efficiency, and are therefore used as light-emitting devices such as LEDs and LDs. It has been.
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 (Autumn 2005), 1 volume, 248 pages

However, in the conventional sputtering method, when a gallium nitride semiconductor crystal doped with a dopant element is formed, it is difficult to finely adjust the doping concentration.
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.
Further, a method of forming a film of a gallium nitride semiconductor crystal doped with Si element by using a method of flowing SiH ₄ gas simultaneously with nitrogen gas in plasma is also conceivable. However, in this method, when a crystal film is formed over a long period of time, particles are generated on the inner wall or ceiling of the reaction chamber, which may cause defects on the target or wafer surface.

The present invention has been made in view of the above problems, and provides a method of manufacturing a sputter target that can easily optimize the doping concentration of a dopant element in a crystal of a gallium nitride semiconductor formed by sputtering. For the purpose.
It is another object of the present invention to provide a sputtering target obtained by the above-described sputtering target manufacturing method.

Furthermore, it aims at providing the sputtering device provided with said sputtering target.
It is another object of the present invention to provide a method for manufacturing a group III nitride compound semiconductor light emitting device, a group III nitride compound semiconductor light emitting device, and a lamp formed using the sputtering apparatus.

As a result of intensive studies to solve the above problems, the present inventors have found that the concentration of the dopant element in the sputter target can be easily adjusted with high accuracy by mixing liquid Ga and the dopant element. . And it discovered that it was possible to easily optimize the doping concentration of the dopant element in the crystal of the deposited layer by forming a film using the sputter target thus obtained, and the present invention was completed.
That is, the present invention relates to the following.

[1] A method for producing a sputter target, comprising a mixing step of mixing liquid Ga and a dopant element.
[2] The method for manufacturing a sputter target according to [1], wherein the mixing step is a step of dissolving the dopant element in the liquid Ga.
[3] The method for producing a sputter target according to [1] or [2], wherein the dopant is Mg.
[4] In any one of [1] to [3], in the mixing step, a ratio of the number of Ga and Mg atoms is in a range of 1: 0.01 to 0.0001. Of manufacturing a sputtering target.
[5] In the mixing step, the weight ratio of Ga and Mg is in the range of 1: 0.003 to 0.00003, according to any one of [1] to [3] A method for manufacturing a sputter target.
[6] The method for producing a sputter target according to [1], wherein the mixing step is a step of dispersing the particulate dopant element in the liquid Ga and then solidifying.
[7] The method according to [1] or [6], wherein the dopant is Si.
[8] In the mixing step, the ratio of the exposed area of Ga and Si particles on the target surface is in the range of 1: 0.05 to 0.0005 [1], [6] Or the manufacturing method of the sputtering target as described in [7].
[9] The mixing step, wherein the weight ratio of Ga and Si is in the range of 1: 0.02 to 0.0002. Of manufacturing a sputtering target.

[10] A sputter target obtained by the method for manufacturing a sputter target according to any one of [1] to [9].
[11] A sputtering apparatus for forming a semiconductor layer made of a gallium nitride semiconductor, comprising the sputtering target according to [10].
[12] A method for 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 gallium nitride semiconductor are stacked, A method for producing a group III nitride compound semiconductor light-emitting device, characterized in that a part thereof is formed using the sputtering apparatus according to [11].
[13] A group III nitride compound semiconductor light-emitting device obtained by the production method according to [12].
[14] A lamp comprising the group III nitride compound semiconductor light-emitting device according to [13].

Since the sputtering target manufacturing method of the present invention includes a mixing step of mixing liquid Ga and a dopant element, the concentration of the dopant element in the sputtering target can be easily adjusted with high accuracy.
Then, by forming a film using a sputtering target in which the concentration of the dopant element obtained by the method for manufacturing a sputtering target of the present invention is adjusted with high accuracy, a layer in which the doping concentration of the dopant element is optimized can be formed. .

Further, since the sputtering apparatus of the present invention is equipped with the above-described sputtering target, a layer in which the doping concentration of the dopant element is optimized can be easily formed.
Furthermore, in the method for producing a group III nitride compound semiconductor light emitting device of the present invention, the semiconductor layer is formed using the sputtering apparatus of the present invention, so that the present invention is provided with a semiconductor layer in which the doping concentration of the dopant element is optimized. The group III nitride compound semiconductor light emitting device and the lamp can be easily manufactured.
In addition, the group III nitride compound semiconductor light-emitting device and lamp of the present invention have excellent emission characteristics because the doping concentration of the dopant element in the semiconductor layer is optimal.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a sputtering target manufacturing method, a sputtering target, a sputtering apparatus, a group III nitride compound semiconductor light emitting device, a group III nitride compound semiconductor light emitting device, and a lamp according to the present invention will be referred to as appropriate. To explain.

[Sputtering equipment]
FIG. 1 is a schematic view schematically showing an example of a sputtering apparatus according to the present invention. A sputtering apparatus 40 shown in FIG. 1 is for forming a semiconductor layer made of a gallium nitride semiconductor, and includes the sputtering target of the present invention.

  As shown in FIG. 1, the sputtering apparatus 40 includes a chamber 41, a sputtering target 47 installed in the chamber 41, and power application means 45 that applies power to the sputtering target 47. Further, as shown in FIG. 1, in the chamber 41 of the sputtering apparatus 40, there are mounting means 11 b for mounting the substrate 11 facing the sputtering target 47 downward and a heater 44 for heating the substrate 11. In addition to the chamber 41, a pressure control comprising a matching box 46c conductively connected to the heater 44, a power supply 48 conductively connected to the matching box 46c, a pump for controlling the pressure in the chamber 41, and the like. Means 49a, 49b, 49c and gas supply means 42a, 42b for supplying gas into the chamber 41 are provided.

  The power applying means 45 applies a predetermined power to the sputtering target 47, and as shown in FIG. 1, the electrode 43, the matching box 46a conductively connected to the electrode 43, and the conductive to the matching box 46a. The power supply 48 is connected. The power applied to the sputter target 47 can be adjusted by controlling the matching box 46a.

  In the present embodiment, the power (applied power) applied to the sputtering target 47 is applied by the pulse DC method or the RF (high frequency) method. In the case where the semiconductor layer is formed by the reactive sputtering method using the sputtering apparatus 40 shown in FIG. 1, 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 sputtering apparatus 40 shown in FIG. 1, the sputtering target 47 is charged up when the electric field is continuously applied with 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.

[Sputter target]
Here, an example is given and demonstrated about the sputtering target of this invention, and the manufacturing method of a sputtering target.
The sputter target 47 of this embodiment is obtained by the manufacturing method shown below. The sputter target 47 of the present embodiment contains a Ga element and a dopant element, and is made of a material corresponding to the composition of the semiconductor layer to be formed. In the present embodiment, a solid target may be used as the sputter target 47, or a liquefied target may be used. The liquefied sputter target 47 may be liquefied as a whole, or may be in a state where only the surface layer is liquefied.

[Method of manufacturing sputter target]
Such a sputter target 47 can be produced by a method of mixing liquid Ga and a dopant element (mixing step).
In the mixing step here, for example, when the dopant element can be melted in liquid Ga, the dopant is added to the liquid Ga liquefied by setting the temperature to 29 ° C. or higher, which is the melting point of Ga. An element can be added, mixed, and dissolved. Examples of the dopant element melted in the liquid Ga include Mg, Zn, Cd, etc. Among them, Mg widely used as a dopant for forming a p-type GaN layer is preferable.

  In addition, for example, when the dopant element is in the form of particles, the mixing step may be a step of solidifying after dispersing the particle-like dopant element in the liquid Ga. In this case, the dopant element particles once uniformly dispersed in the liquid Ga are biased due to a difference in specific gravity between the Ga and dopant element particles, and the concentration of the dopant element in the sputter target 4 is biased. It is prevented. Examples of the particulate dopant element dispersed in the liquid Ga include Si, Ge, Sn, Ca, and Be, and Si, which is widely used as a dopant for forming an n-type GaN layer, among others. Is preferred.

  Further, examples of the dopant element include Si, Ge, Sn, Mg, and the like, and are not particularly limited. However, when the sputter target 47 for forming the n-type semiconductor layer is manufactured, it is Si. Preferably, when the sputter target 47 for forming the p-type semiconductor layer is manufactured, Mg is preferable.

When the dopant element is Mg, the ratio of the number of Ga atoms to the number of Mg atoms in the sputter target 47 is in the range of (Ga atom number: Mg atom number) 1: 0.01 to 0.0001. It is desirable to mix them. When the dopant element is Mg, it is preferable that the weight ratio of Ga and Mg in the sputter target 47 is in the range of 1: 0.003 to 0.00003.
When the dopant element is Si, the ratio of the exposed area of Ga and Si particles on the surface of the sputter target 47 is in the range of (Ga particles: Si particles) 1: 0.05 to 0.0005. It is desirable to do. Further, when the dopant element is Si, it is preferable that the ratio of the weight of Ga and Si in the sputter target 47 is in the range of 1: 0.02 to 0.0002.

[Method for Manufacturing Semiconductor Layer of Light-Emitting Element]
Next, as an example of a method for manufacturing a light-emitting element using the sputtering apparatus 40 shown in FIG. 1, a method for forming a semiconductor layer of a light-emitting element on the substrate 11 by reactive sputtering will be described as an example.
In order to form a semiconductor layer of a light emitting element on the substrate 11 using the sputtering apparatus 40 shown in FIG. 1, first, the pressure in the chamber 41 is set to a predetermined pressure by the pressure control means 49a, 49b, 49c. Then, the gas supply means 42a and 42b are used to supply argon gas and an active gas made of a nitride 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, in a state where the substrate 11 is heated, current is supplied to the electrode 43 through the matching box 46a, power is applied to the sputtering target 47, and current is supplied to the heater base 44 to bias the substrate 11. Apply.

As a result, Ga particles and dopant element particles are ejected from the sputter target 47 into the gas phase in the chamber 41. Then, particles such as Ga particles and dopant element particles in the gas phase 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. Be filmed.

In the present embodiment, when it is intended to sputter target 47 is dissolved dopant element, it is preferred that the power applied to the sputtering target 47 and the range of ^{0.1W / cm 2 ~100W / cm 2} , 1W / cm more preferably to ^{2 ~50W} / cm ^{2 range,} and most preferably in the range of ^{1.5W / cm 2 ~50W / cm 2} .
Further, in the present embodiment, when the sputtering target 47 is one that was solidified by dispersing a particulate dopant element, and ranges power applied to the sputtering target 47 of 0.1W ^/ cm ² ~100W ^/ cm 2 it is preferable ^to, and more preferably in the range of ^{1W / cm 2 ~50W / cm 2} , and most preferably in the range of ^{1.5W / cm 2 ~50W / cm 2} .

Here, when the sputter target 47 is one in which a dopant element is dissolved, at least the surface layer of the sputter target 47 is preferably liquefied.
As a method for liquefying the sputter target 47, for example, a method of setting the power applied to the sputter target 47 to a certain level or higher can be used. Here, the power applied to the sputter target 47 in order to liquefy the sputter target 47 is preferably 1.5 W / cm ² or more. When a power of 1.5 W / cm ² or more is applied to the sputter target 47, the surface layer of the sputter target 47 is melted by being exposed to plasma even when the sputter target 47 is in a solid state. It can be liquefied. Further, if the power applied to the sputter target 47 is less than 150 W / cm ² , it may not be liquefied when the sputter target 47 is in a solid state.

  Further, as another method for liquefying the sputter target 47, a method of heating the sputter target 47 by 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.

  By setting the power applied to the sputtering target 47 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.

  Further, when the sputter target 47 is obtained by dispersing and solidifying the particulate dopant element, the temperature around the sputter target 47 of the sputtering apparatus 40 is set to Ga so that the sputter target 47 is not liquefied. It is made to become less than 29 degreeC which is melting | fusing point.

  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.

Since the method of manufacturing the sputter target 47 of this embodiment includes a mixing step of mixing liquid Ga and a dopant element, the concentration of the dopant element in the obtained sputter target 47 can be easily adjusted with high accuracy. Can do.
Further, the doping concentration of the dopant element is optimized by forming the semiconductor layer of the light emitting element using the sputtering apparatus 40 provided with the sputtering target 47 obtained by the method of manufacturing the sputtering target 47 of the present embodiment. Thus, the semiconductor layer of the light emitting element can be easily formed.

Further, in the method for manufacturing a semiconductor layer of the light emitting device of this embodiment, since the semiconductor layer is formed by a sputtering method, compared with a case where the semiconductor layer is formed by a MOCVD method (metal organic chemical vapor deposition method) or the like. The film rate can be increased, and the film formation (manufacturing) time can be shortened. 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.
In addition, since the semiconductor layer manufacturing method of the present embodiment uses the reactive sputtering method in which an active gas made of a nitride material is supplied into the chamber, the crystallinity of the obtained semiconductor layer is good and uniform. Become.

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

  In the semiconductor layer 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. However, the present invention is limited to the reactive sputtering method. It is not a thing.

  The present invention is not limited to the above-described embodiment. For example, when a semiconductor layer is formed, a method of rotating a magnetic field or swinging a magnetic field with respect to the sputtering target 47 may be used. Good. In particular, when the applied power is an RF (high frequency) system, it is preferable to form a film while moving the position of the magnet in the sputter target 47 in order to avoid charge-up of the sputter target 47. A specific magnet movement method can be appropriately selected depending on the type of the sputtering apparatus. For example, the magnet can be swung or rotationally moved.

In addition, the semiconductor layer to be formed may be formed so as to cover the side surface in addition to the surface of the substrate 11, and may further be formed so as to cover the back surface of the substrate 11.
Examples of the method for forming the surface and side surfaces of the substrate include a method of forming a film while changing the position of the substrate facing the sputter target 47 by swinging or rotating the substrate. It is done. By adopting such a method, it becomes possible to form the surface and side surfaces of the substrate 11 in a single process, and then the film formation process on the back surface of the substrate 11 is performed in a total of two processes. It is possible to cover the entire surface. In addition, as another method for forming the surface and side surfaces of the substrate 11, a method of forming a film on the entire surface of the substrate 11 by placing the substrate 11 in the chamber 41 without holding the substrate 11 can be cited.

  Furthermore, the sputtering target 47 may be formed on the entire surface of the substrate 11 without moving the substrate 11 by using a sputtering target 47 having a large area and capable of moving the position. As such a method, there is an RF (high frequency) type sputtering method in which film formation is performed while moving the position of the magnet of the sputtering target 47 within the target by swinging or rotating the magnet. .

  Further, when film formation is performed by RF (high frequency) sputtering, both the substrate 11 side and the sputtering target 47 side may be moved. Further, by arranging the sputter target 47 in the vicinity of the substrate 11, the generated plasma is not supplied to the substrate 11 in the form of a beam, but is supplied so as to wrap the substrate 11. Simultaneous deposition of the surface and side surfaces of the substrate 11 is possible.

Next, the group III nitride compound semiconductor light-emitting device (hereinafter sometimes abbreviated as a light-emitting device) of the present invention and a method for manufacturing the same will be described.
[Group III nitride compound semiconductor light emitting device]
FIG. 2 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. 3 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. 2, the light emitting device 1 of the present embodiment is of a single-sided electrode type, and includes a substrate 11 and an intermediate layer 12 and a group III nitride compound semiconductor containing Ga as a group III element. The semiconductor layer 20 is formed. As shown in FIG. 2, the semiconductor layer 20 is formed by laminating the n-type semiconductor layer 14, the light emitting layer 15, and the 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.

  Furthermore, 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 is in the range of 1 to 70 nm. It 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. 2, 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. 2, 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. 2, the light emitting layer 15 includes six barrier layers 15 a and five well layers 15 b that are alternately stacked, and the barrier layers 15 a are arranged 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. 2 and 3, 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.

[Method for Manufacturing Light-Emitting Element]
To manufacture the light emitting device 1 shown in FIG. 2, 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 sputtering 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. Thereafter, a base layer 14a made of an undoped semiconductor layer is formed on the intermediate layer 12 shown in FIG. 4 by a conventional sputtering method.

  Subsequently, the n-type contact layer 14b is formed on the base layer 14a by the reactive sputtering method using the sputtering apparatus 40 shown in FIG. The sputter target 47 used for forming the n-type contact layer 14b contains a Ga element and a dopant element, and is made of a material corresponding to the composition of the n-type contact layer 14b. Further, the dopant element here is an n-type impurity such as Si, Ge and Sn used when forming the n-type contact layer 14b.

  The sputter target 47 used for forming the n-type contact layer 14b is obtained by a method of mixing liquid Ga and a dopant element. Specifically, for example, when the dopant element is in the form of particles such as Si, the dopant element is obtained by a method of dispersing the particulate dopand element in liquid Ga and then solidifying it.

  Next, the inside of the chamber 41 is set to a predetermined atmosphere for forming the n-type contact layer 14b, and the substrate 11 on which the base layer 14a is formed is heated to a predetermined temperature. Since the deposition temperature of the n-type contact layer 14b needs to be lower than the temperature at which the crystals decompose, it is preferably less than 1200 ° C. If the temperature of the substrate 11 when forming the n-type contact layer 14b is within the above range, the n-type contact layer 14b with good crystallinity can be obtained. Then, a predetermined current is supplied to the electrode 43 through the matching box 46a, power is applied to the sputtering target 47, current is supplied to the heater base 44, bias is applied to the substrate 11, and An n-type contact layer 14b is formed on the base layer 14a at a predetermined film formation rate.

  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 preferable from the viewpoint of film thickness controllability. A film is formed by MOCVD (metal organic chemical vapor deposition).

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 sputtering apparatus 40 shown in FIG.

  The sputter target 47 used for forming the p-type contact layer 16b of the p-type semiconductor layer 16 includes a Ga element and a dopant element, and is made of a material corresponding to the composition of the p-type contact layer 16b. is there. In addition, as a dopant element contained in the sputter target 47, a p-type impurity such as Mg is used.

  The sputter target 47 used for forming the p-type contact layer 16b is obtained by a method of mixing liquid Ga and a dopant element. Specifically, for example, when the dopant element is meltable in liquid Ga such as Mg, the dopant element is obtained by adding the dopant element to the liquefied liquid Ga, mixing, and dissolving. It is a thing.

  In order to form the p-type contact layer 16b, the inside of the chamber 41 in which the sputter target 47 is installed has a predetermined atmosphere for forming the p-type contact layer 16b, and the layers up to the p-type cladding layer 16a are formed. The substrate 11 thus heated is heated to a predetermined temperature. Then, a predetermined power is applied to the sputtering target 47 to form the p-type contact layer 16b at a predetermined film formation rate.

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. 2 and 3 is obtained.

In the light emitting device of this embodiment, 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 of the semiconductor layer 20 are formed by sputtering. Therefore, the productivity is superior to the case where the base layer 14a, the n-type contact layer 14b, and the p-type contact layer 16b are formed by the MOCVD method.
In the light emitting device of this embodiment, the doping concentration of the dopant element in the crystal in the semiconductor layer formed using the sputtering apparatus 40 shown in FIG. 1 in the semiconductor layer 20 is the optimum concentration. It will be a thing. Therefore, the light emitting device 1 of the present embodiment has excellent light emission characteristics.

  In the manufacturing method of the present embodiment, the p-type contact layer 16b of the p-type semiconductor layer 16 is formed by sputtering. On the other hand, for example, when the p-type cladding layer 16a and the p-type contact layer 16b of the p-type semiconductor layer 16 are formed using the MOCVD method, hydrogen is taken into the p-type semiconductor layer 16 and p In some cases, improvement of the carrier concentration of the type semiconductor layer 16 is hindered. For this reason, when the p-type cladding layer 16a and the p-type contact layer 16b of the p-type semiconductor layer 16 are formed using the MOCVD method, activation annealing is performed after the formation.

  However, in the manufacturing method of the present embodiment, since the base layer 14a and the n-type contact layer 14b of the n-type semiconductor layer 14 are formed by sputtering, activation annealing after forming the p-type semiconductor layer 16 is performed. Is not required, and the destruction of the well layer 15b of the light emitting layer 15 which has been generated by the activation annealing is prevented, and the leakage current and the light emission output are not reduced due to the destruction of the well layer 15b.

In the present embodiment, among the semiconductor layers 20 of the light emitting element 1, the n-type contact layer 14 b of the n-type semiconductor layer 14 and the p-type contact layer 16 b of the p-type semiconductor layer 16 are formed using the sputtering apparatus 40 shown in FIG. The method of forming a film by the above-described sputtering method used has been described as an example, but 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 done.
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 (halide vapor deposition), MBE (molecular beam epitaxy), etc. May be.

  The group III nitride compound semiconductor light-emitting device of the present invention can be used for a photoelectric conversion device such as a laser device or a light receiving device, or an electronic device such as HBT or HEMT, in addition to the above light-emitting device. 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. 2 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. 3) 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 sputtering apparatus 40 shown in FIG. 1, the laminated semiconductor 10 shown in FIG. 4 was produced as shown below, and the light emitting device 1 shown in FIGS. 2 and 3 was produced.
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 bias is not applied to the substrate 11, a power of 1 W / cm ² is applied to the metal Al target, and the substrate 11 is deposited at a film formation rate of 0.12 nm / s by sputtering. A 50 nm thick intermediate layer 12 having an AlN single crystal structure was formed thereon.

  Next, a 6 nm-thick underlayer 14a made of undoped GaN was formed on the substrate 11 on which the intermediate layer 12 was formed by reactive sputtering.

  Next, an n-type contact layer 14b made of a GaN layer doped with Si is formed on the substrate 11 on which the base layer 14a is formed by reactive sputtering using the sputtering apparatus 40 shown in FIG. Was deposited.

First, the substrate 11 on which the underlayer 14a was formed and the sputtering target 47 were installed in the chamber 41 of the sputtering apparatus 40 shown in FIG. As the sputter target 47, a material obtained by mixing 1260 mg of spherical particle-shaped Si having a diameter of 1 mm in 1 kg of liquid Ga, uniformly dispersing and solidifying the mixture was used. Thereby, the ratio of the exposed area of the Ga and Si particles on the surface of the target 47 is Ga: Si = 1: 0.0075.
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 (the ratio of nitrogen in the whole gas is 75%) to form the n-type contact layer 14b. An atmosphere to do.

Next, the substrate 11 is heated to 1000 ° C., and a current is supplied to the electrode 43 via the matching box 46 a while moving the position where the magnetic field is applied by sweeping the magnet into the sputter target 47, and 1 W is supplied to the sputter target 47. In addition to applying a power of / cm ² , 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 deposition rate of 1 nm / s on the substrate 11. An n-type contact layer 14b made of a GaN layer doped with Si was formed to a thickness of 2 μm.

Here, the Si concentration in the obtained n-type contact layer 14b was quantified by a general SIMS (secondary ion mass spectrum) method. As a result, it was confirmed that Si was doped at a concentration of 6 × 10 ¹⁸ cm ⁻³ .

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 installed in the chamber 41 of the sputtering apparatus 40 shown in FIG. A p-type contact layer 16b of the p-type semiconductor layer 16 was formed.

  In forming the p-type contact layer 16b of the p-type semiconductor layer 16, the sputtering target 47 was liquefied by mixing 800 mg of Mg in 1 kg of GaAl alloy that was heated and liquefied, and completely melted. What was obtained by solidifying later was used. Thereby, the ratio of the number of atoms of Ga and Mg of the target 47 is Ga: Mg = 1: 0.0023, and the ratio of the weight of Ga and Mg is Ga: Mg = 1: 0.0008.

Then, a current is supplied to the electrode 43 through the matching box 46a, a power of 1 W / cm ² is applied to the sputtering target 47, and a current is supplied to the heater base 44 to supply 0.5 W / cm ² to the substrate 11. An RF (high frequency) bias is applied and a 200 nm film is formed on the p-type cladding layer 16a at a film formation rate of 1 nm / s, thereby forming a p made of an Al _0.02 Ga _0.98 N layer doped with Mg. A mold contact layer 16b was formed to obtain the laminated semiconductor 10 shown in FIG.

The Mg concentration in 16 p contact layers obtained here was quantified by a general SIMS (secondary ion mass spectrum) method. As a result, it was confirmed that Mg was doped at a concentration of 1 × 10 ²⁰ cm ⁻³ .

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. 2 and 3 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 3.0 V in the initial stage. 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 device 1 of the example had excellent light emission characteristics.

[Example 2]
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 2, 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 2, the light-emitting element 1 shown in FIGS. 2 and 3 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 2 had excellent light emission characteristics.

[Comparative example]
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 constituting the semiconductor layer 20 of the light-emitting element 1 were formed using a sputtering apparatus equipped with a conventional target. Except for the above, the laminated semiconductor 10 shown in FIG.
For forming the n-type contact layer 14b, a method of circulating SiH ₄ gas in plasma was used.
The p-type contact layer 16b was formed by sputtering using an ion beam gun attached separately from the Ga target while irradiating Mg ions.

The Si concentration in the n-type contact layer 14b obtained in the comparative example was examined in the same manner as in Example 1. As a result, similarly to Example 1, Si was doped at a concentration of 6 × 10 ¹⁸ cm ⁻³ . However, since SiH ₄ was circulated simultaneously with the nitrogen gas, SiN fine particles were generated in the chamber, and many foreign substances were adhered to the surface of the completed wafer.

The Mg concentration in the p contact layer 14b obtained in Comparative Example 1 was quantified by a general SIMS (secondary ion mass spectrum) method. As a result, it was confirmed that Mg was doped at a concentration of 7 × 10 ¹⁹ cm ^{−3 to} 1.6 × 10 ²⁰ cm ^{−3 in} a 2-inch wafer, and the value was distributed.
Thus, it has been found that it is difficult to finely adjust the doping concentration when a conventional target is used.

Further, a forward current was passed between the positive electrode bonding pad 18 and the negative electrode 19 of the light emitting diode obtained in the comparative example.
As a result, the forward voltage at a current of 20 mA was initially from a 3.0V chip to a 3.8V chip. 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 from a chip of 12 mW to a chip of 15 mW.
Thus, in the comparative example, the characteristic variation was seen compared with Example 1 and Example 2. FIG. Further, in Example 1 and Example 2, no adhesion of foreign matters was observed on the surface, but in the comparative example, the yield of chips exhibiting normal characteristics due to the foreign matters adhering to the surface was shown in Example 1 and Example. Compared with 2, it was about 50% less.

  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 view schematically showing an example of a group III nitride compound semiconductor light emitting device manufacturing apparatus according to the present invention. FIG. 2 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. 3 is a schematic view showing a planar structure of the group III nitride compound semiconductor light-emitting device shown in FIG. FIG. 4 is a view for explaining the manufacturing method of the group III nitride compound semiconductor light-emitting element shown in FIG. 2, 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 ... Sputtering device, 41 ... Chamber, 43 ... Electrode, 45 ... Power application means, 46a, 46c ... Matching box, 47 ... Sputter target.

Claims (14)

  A method of manufacturing a sputter target, comprising a mixing step of mixing liquid Ga and a dopant element.   The method of manufacturing a sputter target according to claim 1, wherein the mixing step is a step of dissolving the dopant element in the liquid Ga. The method for manufacturing a sputter target according to claim 1, wherein the dopant is Mg. The sputter target according to any one of claims 1 to 3, wherein in the mixing step, the ratio of the number of Ga and Mg atoms is in the range of 1: 0.01 to 0.0001. Manufacturing method. 4. The sputter target according to claim 1, wherein a weight ratio of Ga and Mg is in a range of 1: 0.003 to 0.00003 in the mixing step. 5. Production method. 2. The method of manufacturing a sputter target according to claim 1, wherein the mixing step is a step of dispersing the particulate dopant element in the liquid Ga and then solidifying. The method for manufacturing a sputter target according to claim 1, wherein the dopant is Si. The said mixing process WHEREIN: The ratio of the exposure area of the particle | grains of Ga and Si in the target surface is made to be the range of 1: 0.05-0.0005, The claim 1, The claim 6 characterized by the above-mentioned. 8. A method for producing a sputter target according to 7. 8. The sputter target according to claim 1, wherein the ratio of the weight of Ga and Si is in the range of 1: 0.02 to 0.0002 in the mixing step. Manufacturing method. A sputter target obtained by the method for manufacturing a sputter target according to claim 1. A sputtering apparatus for forming a semiconductor layer made of a gallium nitride semiconductor,
A sputtering apparatus comprising the sputtering target according to claim 10. 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 gallium nitride semiconductor are stacked,
A manufacturing method of a group III nitride compound semiconductor light emitting device, wherein at least a part of the semiconductor layer is formed using the sputtering apparatus according to claim 11.   A group III nitride compound semiconductor light-emitting device obtained by the production method according to claim 12.   A lamp comprising the group III nitride compound semiconductor light-emitting device according to claim 13.

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