KR20090048139A - Nitride-based semiconductor light emitting device and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a nitride-based light emitting device and a method of manufacturing the same, and more particularly, by forming a nitride thin film layer on a silicon substrate having a fine pattern, the nitride-based light emitting device and the manufacturing of the same to minimize the crystal defects and stress in the thin film layer It is about a method.

As a silicon substrate, there is provided a nitride based light emitting device including a silicon substrate having a fine pattern formed on an upper surface thereof, and a nitride thin film layer formed on the silicon substrate having the fine pattern formed thereon.

Nitride-based light emitting device, silicon substrate, fine pattern, nitride thin film layer, stress, defect

Description

Nitride-based light emitting device and its manufacturing method {NITRIDE-BASED SEMICONDUCTOR LIGHT EMITTING DEVICE AND METHOD OF MANUFACTURING THE SAME}

The present invention relates to a nitride-based light emitting device and a method of manufacturing the same, and more particularly, by forming a nitride thin film layer on a silicon substrate having a fine pattern, the nitride-based light emitting device and the manufacturing of the same to minimize the crystal defects and stress in the thin film layer It is about a method.

A light emitting diode (LED) is a device used to transmit electrical energy in the form of infrared rays, visible rays, or light using characteristics of a compound semiconductor. Group III-nitride compound semiconductors are direct-transition type semiconductors, and can obtain stable operation at a high temperature than devices using other semiconductors, and are widely applied to light emitting devices such as light emitting diodes (LEDs) and laser diodes (LDs). have. Such a group III nitride compound semiconductor is generally formed thereon using sapphire (Al 2 O 3) or SiC as a substrate. The luminous efficiency of the LED is determined by the internal quantum efficiency and the light extraction efficiency, and as a method for improving the luminous efficiency, researches on light emitting diodes having various structures for improving the light extraction efficiency have been conducted.

1 illustrates a structure in which gallium nitride 130 is grown on a sapphire substrate 110.

The gallium nitride 130 is an organometallic compound containing gallium (Ga) (trimethylgallium, (CH ₃ ) ₃ Ga, triethylgallium, (C ₂ H ₅ ) ₃ Ga and ammonia containing a nitrogen atom (N) It can be obtained by thermal decomposition at high temperature using, the growth of the gallium nitride 130 may be made by chemical vapor deposition (CVD, chemical vapor deposition).

Since the thin film grows at a high temperature of 1000 ° C. or higher, a 34% thermal expansion coefficient and 16% lattice mismatch between the gallium nitride thin film 130 and the sapphire substrate 110 are achieved. As a result, crystal defects (potential defects, point defects, predefects, etc.) and stresses generated from the interface develop up to the upper layer of the gallium nitride thin film 130, making it difficult to grow gallium nitride crystals having excellent structural, optical, and electrical properties.

The most representative method for overcoming this is to use a buffer layer, and the Al _x Ga _y In _z N film (0≤x≤1, 0≤y≤1, 0≤z≤1, x + at about 450 ° C to 600 ° C) After growing y + z = 1), growth is stopped and the temperature is increased to increase Al _x Ga _y In _z N (0≤x≤1, 0≤y≤1, 0≤z≤1, x). + y + z = 1) is formed as a nuclei, and the seed is used to grow a high quality GaN-based nitride film.

As the buffer layer, an AlN buffer layer, an LT-AlGaN buffer layer, an LT-AlGaInN buffer layer, an LT-AlInN buffer layer, or the like is used. However, even when the gallium nitride thin film is grown in this manner, there is a problem that the gallium nitride thin film has a dislocation density of about 10 ¹⁰ to 10 ¹² / cm 2.

In addition, although the buffer layer is not grown on the sapphire substrate at a low temperature as described above, a GaN-based nitride semiconductor may be grown directly on the substrate at a high temperature, but there is still much room for improvement.

FIG. 2 is a thermal decomposition of an organometallic compound (trimethylaluminum TMAl; (CH ₃ ) ₃ Al) and ammonia containing Al in a conventional silicon substrate 210 at 500-1200 ° C. to a thickness of tens to hundreds of nanometers (nm). After the thin AlN layer 230 is formed, the gallium nitride thin film 250 is formed.

When an AlN layer having a thickness of 20 nm or less is used, the nuclei of AlN do not completely cover the surface of the silicon substrate, and thus do not cause two-dimensional nuclear growth.

In addition, since the AlN thin film 230 does not completely cover the silicon substrate 210, the SiN _x thin film is initially grown, and thus the AlN thin film 230 does not contribute to the improvement of crystallinity of the nitride thin film 250.

In addition, when the AlN thin film of 200 nm or more is used, the grain size of AlN increases, the crystal defect density decreases, but the tensile gallium nitride film 250 grown thereon increases tensile stress. The optical and structural properties become worse.

After all, this method can reduce the lattice mismatch between silicon and gallium nitride using AlN buffer layer, but serious cracking occurs in the grown gallium nitride thin film due to residual stress, or SiN _x thin film at the interface between silicon substrate and AlN thin film. When the device is manufactured using gallium nitride, the gallium nitride has a serious effect on the physical properties of the grown gallium nitride, thereby causing an increase in leakage current, an increase in operating voltage, and a decrease in reliability.

The present invention has been made to overcome the problems of the prior art as described above, the object of the present invention is to reduce the stress in the thin film during the growth of gallium nitride to increase the critical thickness that cracks and to promote horizontal growth To provide a nitride-based light emitting device with improved crystallinity.

According to an embodiment of the present invention for achieving the above object, a nitride system comprising a silicon substrate, a silicon substrate having a fine pattern formed on its upper surface, and a nitride thin film layer formed on the silicon substrate formed with the fine pattern A light emitting element is provided.

The shape of the fine pattern may be a circle or a polygon.

The nitride thin film layer may have a composition of In _x Ga _y Al _z N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, and x + y + z = 1).

The nitride thin film layer may be composed of a single layer or two or more layers.

According to another embodiment of the present invention for achieving the above object, a nitride-based light emitting device comprising the step of forming a fine pattern on a silicon substrate, and forming a nitride thin film layer on the silicon substrate formed with the fine pattern The manufacturing method of is provided.

Forming a fine pattern on the silicon substrate, coating a photoresist on the silicon substrate, forming a predetermined pattern on the photoresist to form a mask photoresist, on the silicon substrate, The method may include removing the uncoated portion of the mask photoresist, and removing the mask photoresist.

The nitride thin film layer may have a composition of In _x Ga _y Al _z N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, and x + y + z = 1).

The forming of the nitride thin film layer may be performed by chemical vapor deposition (CVD), molecular beam deposition (MBE), plasma chemical vapor deposition (PCVD) or sputtering.

The nitride thin film layer may be composed of a single layer or two or more layers.

According to the present invention, by growing a gallium nitride thin film on a silicon substrate on which a fine pattern is formed, crystal defects and stress of gallium nitride are controlled by the patterned silicon substrate so that high quality gallium nitride crystals are grown. Energy loss can be minimized to obtain a high efficiency light emitting device.

In addition, in the nitride-based light emitting device, the crystallinity of gallium nitride can be improved to improve the reliability.

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

3 is a cross-sectional view of a nitride-based light emitting device according to an embodiment of the present invention.

As shown in FIG. 3, the nitride-based light emitting device 300 of the present invention includes a silicon substrate 310 patterned in a predetermined shape, and a nitride thin film layer 350 on the patterned silicon substrate 310. .

The silicon substrate 310 may be a silicon substrate used for a conventional nitride-based light emitting device, and by using such a silicon substrate, gallium nitride crystals can be grown over a large area.

A fine pattern is formed on the surface of the silicon substrate 310 in a predetermined shape.

The pattern may be any of a straight line, a circle, a square, or a hexagonal pattern, but is not limited to this particular form.

Further, in these patterns, the distance between the centers of the patterns is preferably 0.01 to 500 µm, and one pattern width is 0.01 µm ² to 100 mm ² , but is not limited thereto.

On the other hand, the depth of the pattern is preferably 1 nm to 50,000 nm, but this is also not limited thereto.

The nitride thin film layer 350 is formed on the patterned silicon substrate 310.

The nitride thin film layer 350 includes a gas containing a group III atom on the periodic table (for example, a gas such as trimethylindium (TMIn), trimethylgallium (TMGa), trimethylaluminum (TMAl), etc.) and a nitrogen atom (for example, For example, the material may be formed using ammonia (NH ₃ ), hydrazine (H ₂ NNH ₂ , etc.) as a raw material, but is not limited thereto. For example, In _x Ga _y Al _z N (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, x + y + z = 1). By growing the nitride thin film layer 350, gallium nitride crystals can be obtained.

As such, by forming the nitride thin film layer 350 of the silicon substrate 310 having the fine pattern, the silicon substrate 310 serves to prevent the crystal defects and the stress from being transferred to the nitride thin film layer 350, thereby providing gallium nitride. Defects of the crystal can be minimized and stress can be reduced, thereby minimizing energy loss, thereby obtaining a light emitting device having high efficiency and high reliability.

4A through 4F are process diagrams illustrating a manufacturing process of the nitride-based light emitting device of FIG. 3. A photolithography process may be used to manufacture the nitride-based light emitting device.

First, as shown in FIGS. 4A and 4B, a silicon substrate 310 is prepared, and a photoresist 370 for photolithography is uniformly coated thereon. As the photoresist 370, any type of photoresist such as a positive photoresist, a negative photoresist, or an image reverse photoresist may be used, and other types of photoresists may be selectively used as necessary. Can be.

Thereafter, as shown in FIG. 4C, the photoresist 370 is formed in the shape of a three-dimensional structure, that is, a pattern, through an exposure process. This pattern should be formed to correspond to the shape of the pattern to be formed on the silicon substrate 310, and the shape of the pattern may vary as necessary. Although FIG. 4C illustrates a rectangular pattern, the present invention is not limited thereto. As described above, various patterns of a circle, a straight line, a square, and a polygonal shape may be formed.

For example, when forming a square pattern, it is preferable that the width of a pattern is 0.1-10 micrometers, and the space | interval between patterns is 0.1-100.0 micrometers. When the rectangular pattern is formed, the stress between the silicon substrate 310 and the nitride thin film layer 350 to be grown later can be alleviated, whereby the nitride thin film layer 350 having excellent crystallinity can be obtained. The patterned photoresist 370 is used as an etching mask in the lithography process.

Next, as shown in FIG. 4D, the portion of the silicon substrate 310 where the patterned photoresist 370 is not deposited is removed using an etching process.

Thereafter, as shown in FIG. 4E, the photoresist 370 is removed. As a removal method, various methods, such as a solvent washing method and a dry washing method, can be used. When removing the photoresist 370 by using a solvent washing method, a solvent such as H ₂ SO ₄ : H ₂ O ₂ may be used, and when using a dry washing method, a plasma type eliminator using a mixed gas such as Ar and oxygen may be used. Can be removed using

Finally, as shown in FIG. 4F, the nitride thin film layer 350 is grown on the patterned silicon substrate 310. As described above, the nitride thin film layer 350 includes a gas containing a group III atom on the periodic table (for example, a gas such as trimethylindium (TMIn), trimethylgallium (TMGa), trimethylaluminum (TMAl)) and nitrogen atoms. It may be formed using a gas containing (for example, a gas such as ammonia (NH ₃ ), hydrazine (H ₂ NNH ₂ )) as a raw material.

In addition, the nitride thin film layer 350 may be formed of a single layer having the same stoichiometric composition, or may be formed by stacking two or more layers having different stoichiometric compositions.

Meanwhile, growth of the nitride thin film layer 350 may be performed by a method such as chemical vapor deposition (CVD), molecular beam deposition (MBE), plasma chemical vapor deposition (PCVD) or sputtering. As a growth environment, it is preferable to grow at the temperature of 400-1200 degreeC, and it is preferable to grow about 100 micrometers-20 micrometers in total thickness.

By doing so, it is possible to prevent crystal defects and stress from being transferred to the nitride thin film layer 350 of the patterned silicon substrate 310, and thus a nitride based light emitting device having high efficiency and high reliability in which energy loss is minimized. Can be obtained.

6 shows a growth result of the nitride thin film layer 350 in the nitride-based light emitting device 300 according to the present invention.

6 shows a result of nitride growth in the conventional light emitting device shown in FIG. 5, that is, compared with gallium nitride grown on a silicon substrate on which a flat AlN thin film is grown, the crystal defects and stress in nitride crystals are reduced. You can see that.

By reducing such crystal defects and stresses, energy loss is minimized, thereby enabling the implementation of a light emitting device having high efficiency.

In addition, since the nitride-based light emitting device according to the present invention uses a silicon substrate, it is possible to grow a large area gallium nitride crystals, and may be used in FETs, LEDs, sensors, and the like using gallium nitride.

The present invention has been described above in connection with specific embodiments of the present invention, but this is only an example and the present invention is not limited thereto. Those skilled in the art can change or modify the described embodiments without departing from the scope of the present invention, and such changes or modifications are within the scope of the present invention. In addition, the materials of each component described herein can be easily selected and replaced by a variety of materials known to those skilled in the art. Those skilled in the art can also omit some of the components described herein without adding performance degradation or add components to improve performance. In addition, those skilled in the art may change the order of the method steps described herein according to the process environment or equipment. Therefore, the scope of the present invention should be determined not by the embodiments described, but by the claims and their equivalents.

1 is a structural diagram of a gallium nitride thin film grown on a conventional sapphire substrate.

2 is a structural diagram of a gallium nitride thin film grown on a conventional silicon substrate.

3 is a structural diagram showing a configuration of a nitride-based light emitting device according to an embodiment of the present invention.

4A to 4F are process diagrams illustrating a process of manufacturing the nitride-based light emitting device of FIG. 3.

5 is an example of the result of forming gallium nitride on a conventional silicon substrate.

6 is an example of the result of growing a gallium nitride thin film on the surface of a silicon substrate on which a fine pattern of the present invention is formed.

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

110: sapphire substrate 130: gallium nitride thin film

210: silicon substrate 230: aluminum nitride (AlN) layer

250: gallium nitride thin film 300: nitride-based light emitting device

310: substrate 350: nitride thin film layer

370: photoresist

Claims (6)

A silicon substrate, comprising: a silicon substrate having a fine pattern formed on an upper surface thereof; And A nitride-based light emitting device comprising a nitride thin film layer formed on the silicon substrate on which the fine pattern is formed. The method of claim 1, The shape of the fine pattern is a nitride-based light emitting device, circle or polygon. The method of claim 1, The nitride thin film layer has a composition of In _x Ga _y Al _z N (0≤x≤1, 0≤y≤1, 0≤z≤1, x + y + z = 1). The method of claim 1, The nitride thin film layer is composed of a single layer or two or more layers, nitride-based light emitting device. Forming a fine pattern on the silicon substrate; And Forming a nitride thin film layer on the silicon substrate on which the fine pattern is formed. The method of claim 5, wherein the forming of the fine pattern on the silicon substrate comprises: Coating a photoresist on the silicon substrate; Forming a mask photoresist by forming a predetermined pattern on the photoresist; Removing the portion of the silicon substrate that is not coated with the mask photoresist thereon; And And removing the mask photoresist.

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