CN100403559C - Ternary nitride buffer layer of nitride light-emitting component and manufacturing method thereof - Google Patents

Abstract

A nitride light emitting device having a ternary nitride buffer layer, comprising a substrate, a ternary nitride buffer layer formed on the substrate, a first conductivity type nitride semiconductor stacked layer formed on the buffer layer, a light emitting layer formed on the first conductivity type nitride semiconductor stacked layer, and a second conductivity type nitride semiconductor stacked layer formed on the light emitting layer, the ternary nitride buffer layer being manufactured by: and introducing a first gas reaction source containing a first group III element with the melting point temperature less than the first preset temperature at a first preset temperature, depositing the first group III element on the substrate, introducing a second gas reaction source containing a second group III element and a third gas reaction source containing a nitrogen element at a second preset temperature not less than the melting point temperature of the first group III element, and reacting with the first group III element to form the silicon nitride semiconductor substrate.

Description

A ternary nitride buffer layer of a nitride light-emitting component and its manufacturing method

technical field

The invention relates to a buffer layer of a light-emitting component and a manufacturing method thereof, in particular to a ternary nitride buffer layer of a nitride light-emitting component and a manufacturing method thereof.

Background technique

The development and application of nitride light-emitting components is quite extensive and extremely important. Its applications include sign light sources, electronic product backlight sources, outdoor full-color signage, white light lighting, ultraviolet light, and high-density laser applications. Whether this emerging application field can grow rapidly, the most urgent issues that need to be improved are brightness improvement, electrical properties, and improvement of epitaxial process stability.

Most of the traditional nitride components form an AlGaInN series nitride buffer layer on a sapphire substrate (substrate), and then perform a nitride epitaxy process on this buffer layer; due to the problem of lattice constant matching, even up to now, it is still impossible Effectively reduce the dislocation density; it is generally believed that the dislocation density has a considerable relationship with the quality of the component. In order to improve the quality of nitride growth, the traditional nitride epitaxial process uses a two-step growth method. Low-temperature (500-600°C) GaN is used as a buffer layer, and then undergoes a specific heating process and high-temperature (1000-1200°C) treatment to crystallize (Crystallization), and then continue with each epitaxial stack (stack) Epitaxy grows. Since the quality of the buffer layer directly affects the quality of subsequent epitaxy, hundreds of epitaxy parameters such as the thickness and temperature of the buffer layer, the recovery and recrystallization process of heating, the ratio and flow rate of various reaction gas flows must be carefully controlled, resulting in The complexity and difficulty of the process increase, coupled with the need to increase the growth temperature, switch to low temperature, and the time-consuming process of heating and cooling and waiting for the temperature to stabilize, which virtually reduces the production efficiency.

Contents of the invention

When thinking about how to solve the aforementioned problems, the inventor of the present case thinks that if a nitride light-emitting component is provided, it includes a substrate; a ternary nitride buffer layer formed on the substrate; and a ternary nitride buffer layer formed on the buffer layer. The nitride light-emitting stack is characterized in that the manufacturing method of the ternary nitride buffer layer includes: in the reaction chamber, the first gas reaction source containing the first group III element is passed into the reaction chamber at a predetermined temperature, wherein the predetermined The temperature is higher than the melting point of the first group III element, so that the first group III element decomposes and deposits on the surface of the substrate to form a transition layer. Since the predetermined temperature is higher than the melting point of the first group III element, the transition layer The atoms of the first group III element will not form a tight bond substantially; then, at a temperature not lower than the melting point of the first group III element, the second gas reaction source containing the second group III element and the second gas reaction source containing the second group III element are introduced. The third gas reaction source of nitrogen element makes the second group III element atoms and nitrogen atoms interdiffused with the first group III element atoms in the transition layer and rearranges and bonds to form the ternary nitride buffer layer , and continue the subsequent epitaxial process to form a nitride light emitting stack.

The process of the buffer layer formed according to the method of the present invention is simplified, which can simplify the complex heating and cooling process and time in the traditional process, and depending on the process requirements, the second group III element can be selected as gallium element, so that after the completion After the transition layer of the first group III elements with an appropriate thickness, the subsequent epitaxial step of the high-temperature GaN stack can be directly carried out, during which the ternary nitride buffer layer can be formed naturally without special treatment, so the process can be greatly simplified Complexity, effectively improve the quality control of epitaxial film, and reduce the cost of production at the same time.

The main purpose of the present invention is to provide a buffer layer of a nitride light-emitting component. The manufacturing method of the buffer layer replaces the known manufacturing method of the nitride buffer layer, so as to simplify the epitaxial process and reduce the production cost.

Description of drawings:

FIG. 1 is a schematic diagram showing a nitride light-emitting component with a ternary nitride buffer layer according to a preferred embodiment of the present invention;

FIG. 2 is a schematic diagram showing a nitride light-emitting component with a ternary nitride buffer layer according to a preferred embodiment of the present invention;

Figure 3a is a photo taken with an interferometric optical microscope, showing the surface of the GaN layer grown without using a buffer layer;

Figure 3b is a photograph taken with an interferometric optical microscope showing the surface of a GaN layer grown using a conventional two-stage low-temperature GaN buffer layer;

Figure 3c is a photo taken with an interference optical microscope, showing the surface of the GaN layer grown using the AlGaN buffer layer of the technology of the present invention;

Figure 4 is a cross-sectional image observed by a transmission electron microscope (TEM);

Fig. 5 is a real-time reflectance spectrum diagram of epitaxial growth;

Figure 6a is an X-ray (X-Ray) (0004) diffraction spectrum diagram, the GaN layer X-ray spectrum line produced by the traditional two-stage growth method;

Fig. 6b is an X-ray (0004) diffraction line diagram, the X-ray line of the GaN layer prepared by the present invention.

Symbol Description

10 sapphire substrate

11 AlGaN buffer layer

12 N-type nitride semiconductor light emitting stack

121 epitaxial area

122 N-type electrode contact area

13 Nitride multiple quantum well light-emitting layer

14 P-type nitride semiconductor stack

15 Metal transparent conductive layer

16 N-type electrode

17 P-type electrode

28 transparent oxide conductive layer

29 reverse tunnel contact layer

Detailed ways

Example 1

Please refer to FIG. 1, according to a preferred embodiment of the present invention, it is a nitride light-emitting component 1 with an aluminum gallium nitride (AlGaN) buffer layer, including a sapphire substrate 10; the aluminum gallium nitride formed on the sapphire substrate Buffer layer 11; N-type nitride semiconductor stack 12 formed on the aluminum gallium nitride buffer layer 11, wherein the surface of the N-type nitride semiconductor stack 12 away from the substrate 10 includes an epitaxial region 121 and an N-type electrode contact Region 122; gallium nitride/indium gallium nitride multiple quantum well light-emitting layer 13 formed on the epitaxial region 121; P-type nitride semiconductor stack 14 formed on the nitride multiple quantum well light-emitting layer 13; The metal transparent conductive layer 15 formed on the P-type nitride semiconductor stack 14 ; the N-type electrode 16 formed on the N-type electrode contact region 122 ; and the P-type electrode 17 formed on the metal transparent conductive layer 15 .

The formation step of the aluminum gallium nitride buffer layer in this embodiment includes passing through the organic aluminum reaction source TMAl at 800°C to form an aluminum-rich transition layer; under the condition of a low V/III ratio (V/III<1000) , feed organic gallium reaction source TMGa and nitrogen reaction source NH3; then grow a high-temperature gallium nitride layer with V/III ratio (V/III>2000) at 1050°C. During this time, the aluminum atoms in the Al-rich transition layer will diffuse upwards, and the nitrogen atoms and gallium atoms above it will also diffuse downwards to form bonds with the aforementioned aluminum atoms and rearrange, thereby forming the AlGaN buffer layer.

Example 2

Another preferred embodiment of the present invention is a nitride light-emitting component 2 with an aluminum gallium nitride (AlGaN) buffer layer. Its component structure is similar to that of embodiment 1, only the material and manufacturing method of the buffer layer are different. The formation steps of the aluminum gallium nitride buffer layer are as follows:

The organic aluminum reaction source TMAl is introduced at 1020°C to form an aluminum-rich transition layer; the organic gallium reaction source TMGa and the nitrogen reaction source NH ₃ are introduced at the same temperature to directly grow a high-temperature gallium nitride stack; The aluminum atoms in the aluminum transition layer will diffuse upwards, and the nitrogen atoms and gallium atoms above it will also diffuse downwards to form bonds with the aforementioned aluminum atoms and rearrange them, thereby forming the AlGaN buffer layer.

In the nitride light-emitting devices with aluminum gallium nitride (AlGaN) buffer layer in Embodiments 1 and 2 of the present invention, the metal transparent conductive layer can also be replaced by a transparent oxide conductive layer. Since the transparent oxide conductive layer has higher transmittance than the traditional metal transparent conductive layer, the luminous efficiency can be further improved.

Example 3

Please refer to FIG. 2 , according to another preferred embodiment of the present invention, a nitride light-emitting component 3 with an aluminum gallium nitride (AlGaN) buffer layer, and a nitride light-emitting component with an aluminum gallium nitride (AlGaN) buffer layer The difference between 1 and 2 is that the metal transparent conductive layer on the P-type nitride semiconductor stack 14 is replaced by a transparent oxide conductive layer 28, and a high concentration of N is formed between the P-type nitride semiconductor stack 14 and the transparent oxide conductive layer 28. type reverse tunnel contact layer 29, its thickness is less than 10 nm, and its carrier concentration is higher than 1×10 ¹⁹ cm ⁻³ or more. Since the transparent oxide conductive layer 28 and the P-type nitride semiconductor stack 14 are less likely to form a good ohmic contact (Ohmic contact), the high-concentration N-type reverse tunnel contact layer 29 formed therebetween makes this A good ohmic contact is formed between the transparent oxide conductive layer 28 and the high-concentration N-type reverse tunnel contact layer 29; The interface of the nitride semiconductor stack is just under the effect of reverse bias to form a depletion layer, and therefore the N-type reverse tunnel contact layer 29 is not thick in nature, so the carriers in the transparent oxide conductive layer 28 can pass through the tunnel The effect enters the P-type semiconductor stack 14, and makes the device maintain the characteristic of low operating bias. In the nitride light-emitting element 1, 2 or 3 with an aluminum gallium nitride (AlGaN) buffer layer, the aluminum gallium nitride (AlGaN) buffer layer can be replaced by other ternary nitride buffer layers, such as indium gallium nitride ( InGaN) or indium aluminum nitride (InAlN) buffer layer.

Figure 3 is the surface of a small piece taken with an interference optical microscope, respectively 3a without using a buffer layer, 3b using a traditional two-stage growth low-temperature GaN buffer layer, and 3c using the AlGaN ternary nitride buffer of the present invention Layer, the surface state of the small piece after growing the high-temperature gallium nitride layer, it can be found that the small piece without the buffer layer has a foggy surface and no specific crystal form. However, the surface of the chip using the AlGaN ternary nitride buffer layer of the present invention can achieve the same good mirror-like surface as the traditional two-stage growth method.

We have found that the thickness of the buffer layer required to make the surface of the epitaxial chip appear mirror-like according to the method of the present invention is thinner than that of the traditional two-stage growth buffer layer. Please refer to Figure 4, which is a cross-sectional image observed with a transmission electron microscope (TEM). It can be seen that the thickness of the buffer layer is only about 7nm, which can make the surface of the small piece appear mirror-like, and the optimal thickness of the buffer layer for the traditional two-stage growth The range is about 20 ~ 40nm, in order to get the mirror state of the surface of the small pieces.

Fig. 5 is a growth real-time reflectance spectral line diagram of a trace amount of silicon-doped GaN thin film prepared by using the AlGaN ternary nitride buffer layer technology of the present invention. It can be seen from the figure that the signal formed by the transition layer and the signal of subsequent high-temperature gallium nitride thin film growth can be seen. After the growth of the GaN thin film is completed, it is measured by X-ray diffractometer and Hall (Hall), and the half-maximum width of the X-ray diffraction spectrum of (0004) is 232 arc seconds (arcsec) respectively (see Figure 6b ), the carrier concentration of Hall is 1×10 ¹⁷ cm ^-3 , and the carrier mobility (mobility) is 690cm ² /Vs. ) X-ray diffraction spectrum half maximum width of 269 arc seconds (see Figure 6a), Hall's carrier concentration is 1×10 ¹⁷ cm ^-3 , carrier mobility (mobility) is 620cm ² /Vs , showing that the quality of the epitaxial film prepared according to the present invention is indeed significantly improved.

Table 1 is a comparison of the characteristics of the light emitting diode prepared according to the technology of the present invention and the blue light emitting diode (wavelength ~ 470nm) produced by the traditional two-stage buffer layer technology. According to the data, it can reach a level similar to that of traditional two-stage growth technology in terms of brightness, forward bias voltage, reverse current or reverse bias voltage characteristics, and its life test results are also incomparable with traditional technology. There are obvious differences, but as mentioned above, the technology of the present invention can greatly omit the complicated heating and cooling process and time, simplify the process complexity, effectively improve the controllability of the quality of the epitaxial film, and reduce the production cost at the same time, so it has obvious advantages. progress.

Table 1 Comparison of LED characteristics between the technology of the present invention and the traditional technology

Brightness at 20mA (mcd) Forward Bias Voltage (V) at 20mA Reverse current at 5V reverse bias (μA) Reverse bias voltage at 10μA reverse current (V) Traditional two-stage growth method buffer layer 37～40 3.14-3.25 0.00-0.01 24-32 The ternary nitride buffer layer technology of the present invention 38～42 3.17-3.24 0.00-0.01 20-33

In each of the above embodiments, the P-type nitride semiconductor stack includes a P-type nitride contact layer, and a P-type nitride confinement layer; the N-type nitride semiconductor stack includes an N-type nitride contact layer, and an N-type nitride Confinement layer; the P-type nitride contact layer includes a material selected from the material group consisting of AlN, GaN, AlGaN, InGaN and AlInGaN; the N-type nitride contact layer includes a material selected from AlN, GaN, AlGaN , a material in the material group consisting of InGaN and AlInGaN; the N-type or P-type nitride confinement layer contains at least one material selected from the material group consisting of AlN, GaN, AlGaN, InGaN and AlInGaN; The sapphire substrate can also be replaced by at least one material or other alternative materials in the material group formed by SiC, GaAs, CaN, AlN, GaP, Si, ZnO, MgO and glass; the ternary nitride buffer layer can include A material selected from the material group consisting of InGaN, AlGaN, and InAlN; the N-type nitride semiconductor stack may include a material selected from the material group consisting of AlN, GaN, AlGaN, InGaN, and AlInGaN The nitride multi-quantum well light-emitting layer may include a material selected from the material group consisting of GaN, InGaN, and AlInGaN; the P-type nitride semiconductor stack may include a material selected from AlN, GaN, AlGaN, InGaN, and A material in the group of materials composed of AlInGaN; the metal transparent conductive layer includes at least one material selected from the group of materials composed of Ni/Au, NiO/Au, Ta/Au, TiWN and TiN; the The transparent oxide conductive layer contains at least one material selected from the material group consisting of indium tin oxide, cadmium tin oxide, antimony tin oxide, zinc aluminum oxide and zinc tin oxide.

The above-mentioned ones are only preferred embodiments of the present invention, and the scope of the present invention is not limited to these preferred embodiments. Any changes made according to the present invention belong to the scope of patent application of the present invention. Therefore, those skilled in the art can make any changes without departing from the claims and spirit of the present invention.

Claims (14)

1. A method for manufacturing a ternary nitride buffer layer of a nitride light-emitting component, the steps of which at least include: provide the substrate; Passing a first gas reaction source containing a first group III element at a first predetermined temperature, the melting point temperature of the first group III element being lower than the first predetermined temperature, wherein the first group III element is deposited on the substrate ;as well as At the second predetermined temperature, the second gas reaction source containing the second group III element and the third gas reaction source containing nitrogen element are introduced to react with the first group III element deposited on the substrate to form a ternary nitride The buffer layer, wherein the temperature at the second predetermined temperature is not less than the melting point of the first group III element. 2. The manufacturing method of the ternary nitride buffer layer of the nitride light-emitting component as claimed in claim 1, wherein, the substrate is composed of sapphire, GaN, AlN, SiC, GaAs, GaP, Si, ZnO, MgO , MgAl ₂ O ₄ and glass constitute at least one material in the material group. 3. The method for manufacturing the ternary nitride buffer layer of the nitride light-emitting device as claimed in claim 1, wherein the first predetermined temperature is substantially above 500°C. 4. The method for manufacturing the ternary nitride buffer layer of the nitride light-emitting device as claimed in claim 1, wherein the second predetermined temperature is substantially above 700°C. 5. The manufacturing method of the ternary nitride buffer layer of the nitride light-emitting component as claimed in claim 1, wherein, the first group III element system comprises at least a material. 6. The manufacturing method of the ternary nitride buffer layer of the nitride light-emitting component as claimed in claim 1, wherein, the second group III element system comprises at least a material. 7 . The method for manufacturing the ternary nitride buffer layer of the nitride light-emitting device according to claim 1 , wherein the thickness of the ternary nitride buffer layer is between 1 nm and 500 nm. 8. The manufacturing method of the ternary nitride buffer layer of the nitride light-emitting device as claimed in claim 1, wherein the ternary nitride buffer layer comprises a material selected from the group consisting of InGaN, AlGaN and InAlN. at least one material. 9. A nitride light-emitting component, comprising the ternary nitride buffer layer manufactured by the manufacturing method according to any one of claims 1 to 8. 10. The nitride light-emitting component according to claim 9, wherein the nitride light-emitting component at least comprises a substrate, the ternary nitride buffer layer formed on the substrate, and the ternary nitride buffer layer formed on the substrate The nitride semiconductor layer of the first conductivity type on the top, the light emitting layer formed on the nitride semiconductor layer of the first conductivity type, and the nitride semiconductor layer of the second conductivity type formed on the light emitting layer. 11. The nitride light-emitting _device as claimed in claim 10, wherein the substrate is composed of materials selected from sapphire, GaN, AlN, SiC, GaAs, GaP, Si, ZnO, MgO, _MgAl2O4 and glass At least one material in the group. 12. The nitride light-emitting device as claimed in claim 10, wherein the nitride semiconductor layer of the first conductivity type comprises at least one material selected from the group consisting of AlN, GaN, AlGaN, InGaN and AlInGaN. 13. The nitride light-emitting device as claimed in claim 10, wherein the light-emitting layer comprises at least one material selected from the group consisting of AlN, GaN, AlGaN, InGaN and AlInGaN. 14. The nitride light emitting device according to claim 10, wherein the second conductivity type nitride semiconductor layer comprises at least one material selected from the group consisting of AlN, GaN, AlGaN, InGaN and AlInGaN .

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