KR100956200B1 - Manufacturing method of nitride semiconductor light emitting device - Google Patents

Abstract

A method of manufacturing a nitride semiconductor light emitting device is disclosed. The method of manufacturing the nitride semiconductor light emitting device includes the steps of nitriding a m-plane sapphire substrate, forming a high-temperature buffer layer of an appropriate thickness range on the m-plane sapphire substrate, and semipolar (11-22) plane nitride on the high-temperature buffer layer. Depositing a series thin film, and sequentially depositing a first nitride semiconductor layer, an active layer, and a second nitride semiconductor layer on the semipolar (11-22) plane nitride based thin film to form a light emitting structure. As such, by forming the high temperature buffer layer in an appropriate thickness range, the growth characteristics of the high temperature buffer layer are improved, and the semipolar (11-22) plane nitride thin film can have a high quality single crystal structure.

Light emitting element, m surface sapphire substrate, semipolar, (11-22) surface, high temperature buffer layer

Description

Manufacturing method of nitride semiconductor light emitting device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a nitride semiconductor light emitting device, and more particularly, a nitride semiconductor light emitting device for growing a semipolar (11-22) plane nitride thin film by forming a high temperature buffer layer within an appropriate thickness range on an m plane sapphire substrate. A method for manufacturing a device.

In general, in the manufacture of nitride semiconductor light emitting devices, nitride-based thin films such as gallium nitride are mostly c (0001) -side nitride-based thin films, mainly organic metal chemical vapor deposition (MOCVD) on c-plane sapphire substrates, It can be grown by molecular beam deposition (MBE: Molecurlar Beam Epitaxy) or HVPE (Hydride Vapor Phase Epitaxy).

As described above, the c-plane nitride-based thin film has a gallium layer and a nitrogen layer repeatedly stacked in the c-crystal axial direction, thereby exhibiting polarity, which induces generation of an internal electric field. In this case, the generation of an internal electric field in the light emitting device is a cause of reducing the recombination rate of electrons and holes, thereby lowering the luminous efficiency of the light emitting device. In addition, the emission wavelength is shortened due to the generation of piezoelectric polarization, it is difficult to implement a long wavelength element.

In order to solve this problem, a semipolar nitride based thin film should be grown, but when using a c-plane sapphire substrate, it is difficult to grow a nitride based thin film into a semipolar plane. Therefore, there is a need for a technique for growing a semipolar nitride based thin film using a sapphire substrate having a nonpolar surface. In addition, when the semi-polar nitride-based thin film is grown, it is necessary to implement high quality crystallinity to improve the reliability of the light emitting device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to grow a semi-polar (11-22) plane nitride based thin film using an m plane sapphire substrate, thereby increasing the luminous efficiency of the light emitting device. The present invention provides a semiconductor light emitting device and a method of manufacturing the same.

In addition, another object of the present invention is to form a nitride semiconductor light emitting device for forming a semi-polar (11-22) plane nitride-based thin film having a high quality crystallinity by forming a high temperature buffer layer of an appropriate thickness on the m-plane sapphire substrate and It is to provide a method of manufacturing the same.

In the method of manufacturing a nitride semiconductor light emitting device according to an embodiment of the present invention for achieving the above object, the step of nitriding the m surface sapphire substrate, forming a high temperature buffer layer of an appropriate thickness range on the m surface sapphire substrate Depositing a semipolar (11-22) plane nitride thin film on the high temperature buffer layer, and a first nitride semiconductor layer, an active layer, and a second layer on the semipolar (11-22) plane nitride thin film. Sequentially depositing a nitride semiconductor layer to form a light emitting structure.

In this case, nitriding the m-plane sapphire substrate may include: charging the m-plane sapphire substrate in a MOCVD chamber to increase the temperature to 750 to 900 ° C, and introducing ammonia (NH ₃ ) gas into the MOCVD chamber. Steps.

In the forming of the high temperature buffer layer, the m surface sapphire substrate is charged into a MOCVD chamber to form a gas atmosphere including nitrogen, and the MOCVD chamber is heated to a temperature of 900 to 1100 ° C. to provide Al _x Ga ₍ Epitaxially growing a semiconductor material of _1-x N (0 ≦ _x ≦ 1).

The method of manufacturing the nitride semiconductor light emitting device may include exposing the first nitride semiconductor layer by etching a portion of the light emitting structure, and forming a first electrode at a position where the first nitride semiconductor layer is exposed. The method may further include forming a second electrode on the second nitride semiconductor layer.

In the present invention, the appropriate thickness range is preferably 1000 to 4000 mm 3.

According to the present invention, by using the m-plane sapphire substrate, the semi-polar (11-22) plane nitride-based thin film can be deposited. Accordingly, it is possible to prevent the generation of the internal electric field and to reduce the piezoelectric polarization to improve the luminous efficiency.

In addition, by forming a high temperature buffer layer formed on the m-plane sapphire substrate to a thickness of about 1000 to 4000 Pa, more preferably 2000 Pa, it is possible to form a semi-polar (11-22) plane nitride thin film of high quality single crystal structure. do. Accordingly. It is possible to easily form the light emitting structure on the semi-polar (11-22) surface nitride-based thin film, thereby improving product reliability of the light emitting device.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

1A to 1D are vertical cross-sectional views illustrating a method of manufacturing a nitride semiconductor light emitting device according to an embodiment of the present invention.

Referring to FIG. 1A, the high temperature buffer layer 12 is formed on the m surface sapphire substrate 11. In this case, the surface of the m plane sapphire substrate 11 is in a state of being nitrided. Specifically, the m-plane sapphire substrate 11 is charged into the MOCVD chamber, and ammonia (NH 3) gas is flowed into the chamber to perform nitriding treatment. In this case, during the nitriding of the m surface sapphire substrate 11, the temperature in the chamber may be about 750 to 900 ° C. Alternatively, the temperature in the chamber may be gradually raised to about 450 to 1050 ° C. As described above, according to the nitriding treatment of the m surface sapphire substrate 11, the surface may be modified to improve growth characteristics of the high temperature buffer layer 12.

When the nitriding process of the m surface sapphire substrate 11 is completed, the high temperature buffer layer 12 is formed. Specifically, in the state where the m-plane sapphire substrate 11 is charged in the MOCVD chamber, epitaxial growth is performed in a gas atmosphere containing nitrogen and in a temperature range of 900 to 1100 ° C. Accordingly, the high temperature buffer layer 12 can be grown into a semiconductor material having a compositional formula of Al _x Ga _(1-x) N (0≤x <1).

Meanwhile, the crystallinity of the semipolar (11-22) plane nitride thin film may be changed depending on the growth characteristics (eg, surface characteristics) of the high temperature buffer layer 12. Specifically, the high temperature buffer layer 12 is a thin film for preventing strain caused by the lattice constant difference between the m-plane sapphire substrate 11 and the semi-polar (11-22) surface nitride-based thin film. Therefore, the crystallinity of the semipolar (11-22) plane nitride based thin film may depend on the growth characteristics of the high temperature buffer layer 12.

In order to realize stable growth characteristics of the high temperature buffer layer 12, it is necessary to grow to have an appropriate thickness range. In this case, the appropriate thickness range of the high temperature buffer layer 12 may be about 1000 to 4000 mm 3. Preferably, the high temperature buffer layer 12 can be produced with a thickness of 2000 kPa.

The thickness of the high temperature buffer layer 12 can be easily controlled by adjusting the growth time. For example, when the high temperature buffer layer 12 is to be grown to a thickness of 1000 mW, the growth time may be set to about 5 minutes. In addition, when growing to a thickness of 2000 kPa, the growth time can be set to about 10 minutes. As such, by controlling the growth time, the thickness of the high temperature buffer layer 12 may be easily controlled. In addition, the growth thickness proportional to the growth time of the high temperature buffer layer 12 is different depending on the growth capacity of the MOCVD chamber, the growth environment, and the like, and is not limited to the above examples.

Next, as shown in FIG. 1B, a semipolar (11-22) plane nitride based thin film 13 such as gallium nitride (GaN) is formed on the high temperature buffer layer 12. In this case, the semipolar (11-22) plane nitride based thin film 13 is manufactured on the m plane sapphire substrate 11, grows to the m plane, and has a form parallel to the m plane sapphire substrate 11. In addition, having a semi-polar characteristic, the luminous efficiency can be improved by preventing the generation of an internal electric field during light emission of the light emitting device, and reducing the piezoelectric polarization.

In addition, the semi-polar (11-22) plane nitride-based thin film 13 is formed on the high temperature buffer layer 12 having a suitable thickness range of 1000 ~ 4000Å, it can be grown into a high quality single crystal structure. Accordingly, the light emitting structure can be easily formed, and the deposition characteristics are good, thereby improving product reliability of the light emitting device.

Referring to FIG. 1C, a light emitting structure including a first nitride semiconductor layer 14, an active layer 15, and a second nitride semiconductor layer 16 is formed on a semipolar (11-22) plane nitride based thin film 13. Form. In detail, the first nitride semiconductor layer 14 may be formed by doping an n-type dopant such as Si, In, or Sn into a GaN semiconductor material. In addition, the active layer 15 may be formed in a form having a single or multiple quantum well structure using a GaN-based material such as GaN or InGaN. The second nitride semiconductor layer 16 may be formed by doping a p-type dopant such as Zn, Cd, Mg, or the like into the GaN semiconductor material. In this case, each of the first nitride semiconductor layer 14, the active layer 15, and the second nitride semiconductor layer 16 is formed using a deposition method such as metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). can do.

Thereafter, as illustrated in FIG. 1D, some surfaces of the light emitting structures are etched to expose the first nitride semiconductor layer 14. The first electrode 17 is formed on the exposed first nitride semiconductor layer 14, and the second electrode 18 is formed on the light emitting structure, that is, on the second nitride semiconductor layer 16. In this case, the first electrode 17 may be an n-electrode, and the second electrode 18 may be a p-electrode.

As described above, the nitride semiconductor light emitting device 100 provided in the present invention uses the m-plane sapphire substrate 11 to form a nitride-based thin film having semipolar characteristics. In addition, the high temperature buffer layer 12 may be formed to a thickness of about 1000 to 4000 mm 3 so that the semipolar (11-22) plane nitride based thin film 13 has a high quality single crystal structure.

2A to 2C are OM images of the surface of the semi-polar (11-22) plane nitride thin film according to the growth thickness of the high temperature buffer layer.

FIG. 2A is an OM photograph of the surface of a semipolar (11-22) plane nitride based thin film 13a formed on a high temperature buffer layer having a thickness of 500 kHz. As shown in Figure 2a, it can be seen that the semi-polar (11-22) plane nitride-based thin film (13a) has a plurality of hillock is formed on the surface. As described above, in the case of the 500 Å thin high temperature buffer layer, since its growth characteristics are not stable, the crystallinity of the semipolar (11-22) plane nitride thin film 13a is lowered.

FIG. 2B is an OM photograph of the surface of the semi-polar (11-22) plane nitride based thin film 13a formed on the high temperature buffer layer having a thickness of 2000 kV. Referring to FIG. 2B, it is confirmed that the occurrence of hillock is significantly reduced in the semipolar (11-22) plane nitride thin film 13a compared with the semipolar (11-22) plane nitride thin film 13a shown in FIG. 2A. Can be. This can be formed to have a high quality single crystal structure by growing the semipolar (11-22) plane nitride thin film 13b on the high temperature buffer layer having stable growth characteristics.

2C is an OM photograph of the surface of the semipolar (11-22) plane nitride thin film 13c formed on a high temperature buffer layer having a thickness of 5000 kPa. Referring to FIG. 2C, in the case of the semipolar (11-22) plane nitride-based thin film 13c, it can be seen that a pit is formed on the surface. Pits formed on the surface of the semi-polar (11-22) plane nitride-based thin film 13c are one of the causes of lowering the reliability of the light emitting device, and thus have difficulty in manufacturing the light emitting device.

As described above, when the high temperature buffer layer is formed to have a thickness outside the appropriate thickness range of 1000 to 4000 kPa, the crystallinity of the semipolar (11-22) plane nitride thin film formed on the high temperature buffer layer is reduced. Therefore, as shown in FIG. 2B, it is preferable to reduce the number of hillocks generated in the semipolar (11-22) plane nitride thin film and prevent the occurrence of pit by forming the high temperature buffer layer at 2000 kPa.

3 is a graph showing the crystallinity of the semi-polar (11-22) plane nitride thin film according to the high temperature buffer layer deposition thickness. A graph showing X-ray diffraction (XRD) oscillation lines in which x-ray rays are incident on a semi-polar (11-22) plane nitride-based thin film. The x direction of the graph represents the thickness of the high temperature buffer layer and the y direction. Represents full width at half maximum (FWHM). The full width at half maximum indicates the crystallinity of the semipolar nitride-based thin film, and the lower the numerical value, the better the crystallinity.

Referring to the graph of FIG. 3, when the thickness of the high temperature buffer layer is 1000 kPa or 3000 kPa, the semipolar (11-22) plane nitride-based thin film shows an FWHM of about 650 arcsec. In addition, when the thickness of the high temperature buffer layer is 4000 kPa, the semipolar (11-22) plane nitride-based thin film exhibits an FWHM of about 725 arcsec. And when the thickness of the high temperature buffer layer is 2000 kPa, the semipolar (11-22) plane nitride-based thin film exhibits an FWHM of about 525 arcsec. Thus, the semi-polar (11-22) plane nitride based thin film formed on the high temperature buffer layer of about 1000-4000 micrometers thickness shows FWHM of 525-725 arcsec, and it turns out that it has a high quality single crystal structure. In this case, it can be seen that the crystallinity of the semipolar (11-22) plane nitride-based thin film was most improved when the high temperature buffer layer had a thickness of 2000 kPa. Therefore, it is preferable to form a semi-polar (11-22) plane nitride thin film by growing the high temperature buffer layer to a thickness of 2000 kPa.

While the above has been shown and described with respect to preferred embodiments of the invention, the invention is not limited to the specific embodiments described above, it is usually in the art to which the invention belongs without departing from the spirit of the invention claimed in the claims. Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

1A to 1D are vertical cross-sectional views illustrating a method of manufacturing a nitride semiconductor light emitting device according to an embodiment of the present invention;

2A to 2C are OM images of the surface of the semi-polar (11-22) plane nitride based thin film according to the deposition thickness of the high temperature buffer layer, and

3 is a graph showing the crystallinity of the semi-polar (11-22) plane nitride-based thin film according to the high temperature buffer layer deposition thickness.

<Description of the symbols for the main parts of the drawings>

100 nitride semiconductor light emitting device 11 m-plane sapphire substrate

12 high temperature buffer layer 13 semi-polar (11-22) surface nitride based thin film

14: first nitride semiconductor layer 15: active layer

16: second nitride semiconductor layer 17: first electrode

18: second electrode

Claims (5)

nitriding the m-plane sapphire substrate; Forming a high temperature buffer layer on the m surface sapphire substrate at a temperature of 900 ° C. to 1100 ° C. in a thickness range of 1000 kPa to 4000 kPa; Depositing a semipolar (11-22) plane nitride based thin film on the high temperature buffer layer; And, And sequentially depositing a first nitride semiconductor layer, an active layer, and a second nitride semiconductor layer on the semi-polar (11-22) plane nitride based thin film to form a light emitting structure. Forming the high temperature buffer layer, Charging the m-plane sapphire substrate into a MOCVD chamber to form a gas atmosphere containing nitrogen, and heating the MOCVD chamber to a temperature of 900 ° C. to 1100 ° C. to give Al _x Ga _(1-x) N (0 ≦ A method of manufacturing a nitride semiconductor light emitting device comprising epitaxially growing a semiconductor material of x≤1). The method of claim 1, Nitriding the m-plane sapphire substrate, Charging the m-plane sapphire substrate into a MOCVD chamber to raise the temperature to 750 to 900 ° C; And, Introducing ammonia (NH ₃ ) gas into the MOCVD chamber; manufacturing method of the nitride semiconductor light emitting device comprising a. delete The method of claim 1, Etching a portion of the light emitting structure to expose the first nitride semiconductor layer; And, And forming a first electrode at a position at which the first nitride semiconductor layer is exposed and forming a second electrode on the second nitride semiconductor layer. delete

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