KR100775137B1 - Method of growing nitride semiconductor layer - Google Patents

Abstract

A method of growing a nitride semiconductor layer is provided to decrease crystal defects at a window region by growing the nitride semiconductor layer on the window region between masks, as well as a wing region of the mask. A nitride semiconductor layer(110) is grown on a substrate(100), and then plural spaced masks(120) are formed on the nitride semiconductor layer. The nitride semiconductor layer exposed between the spaced masks is etched through wet etching so that the semiconductor layer has an inclined surface. After the etching, the nitride semiconductor layer is regrown on the remaining nitride semiconductor layer.

Description

Method of growing nitride semiconductor layer

1 to 4 are cross-sectional views sequentially showing the growth method of a nitride semiconductor layer using a conventional ELOG method.

5 to 8 are cross-sectional views sequentially showing the growth method of the nitride semiconductor layer using the ELOG method according to an embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

100: substrate 110: GaN layer

120: mask d: dislocation

The present invention relates to a method for growing a nitride semiconductor layer, and more particularly, to a method for growing a nitride semiconductor layer that can contribute to improving the quality of a nitride-based semiconductor light emitting diode by reducing lattice defects such as dislocations.

Recently, nitride semiconductors using nitrides, including gallium nitride (GaN), have been in the spotlight as core materials of optoelectronic materials and electronic devices due to their excellent physical and chemical properties. In particular, the nitride semiconductor light emitting device can generate light in the green, blue and ultraviolet regions, and has been applied to fields such as full color display boards, lighting devices, etc., as the brightness is dramatically improved due to the development of technology.

Such a nitride semiconductor uses a nitride semiconductor material having an Al _x In _y Ga _(1-xy) N composition formula, where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ x + y ≦ 1. In particular, research on semiconductor light emitting devices using GaN has been actively conducted. In the nitride semiconductor light emitting device, since there is no commercial substrate having the same crystal structure and lattice matching with a nitride semiconductor material such as GaN, a sapphire substrate which is an insulating substrate is widely used.

In general, single crystal thin film growth made of a nitride semiconductor material is performed by a hetero epitaxy method using a MOCVD (Metal Organic Chemical Vapor Deposition) method on a sapphire substrate which is a heterogeneous substrate. In this case, a lattice defect called dislocation occurs between the sapphire substrate and the thin film of nitride semiconductor material due to the mismatch of lattice constant and thermal expansion coefficient.

Until now, as a technique for reducing the dislocation, the epitaxial lateral overgrowth (ELOG) method, the latent epitaxy on patterned sapphire substrate (LEPS) method, the peneo epitaxy (PE) method, etc. for growing GaN laterally have been proposed. .

In particular, the ELOG method is known as a technique capable of ensuring the formation of a high quality epitaxial layer having a low dislocation density. The ELOG method is a method of growing GaN in the lateral direction to suppress movement of defects formed at the interface between the sapphire substrate and the GaN layer to the upper layer portion. In the ELOG method, a dielectric mask is formed on the sapphire substrate or on the upper surface of the first grown GaN epitaxial layer, and then GaN is grown again on the portion where the mask is not formed to grow GaN laterally.

Hereinafter, the growth method of the nitride semiconductor layer using the ELOG method will be described in detail with reference to FIGS. 1 to 4.

1 to 4 are sectional views sequentially shown to explain a method of growing a nitride semiconductor layer using a conventional ELOG method.

First, as shown in FIG. 1, the GaN layer 110 is first grown by a predetermined thickness on the sapphire substrate 100. At this time, a lattice defect called dislocation d is inevitably generated in the GaN layer 110 grown on the sapphire substrate 100.

Next, as shown in FIG. 2, on the first grown GaN layer 110, a plurality of masks 120 spaced apart from each other by using SiO ₂ or the like are formed.

Then, as shown in FIG. 3, the GaN layer 110 is regrown on the GaN layer 110 in the portion where the mask 120 is not formed.

At this time, as the GaN layer 110 is regrown after the mask 120 is formed as described above, a region between the masks 120 (hereinafter, referred to as a "window region") will be referred to. In the GaN layer 110 grown in the vertical direction, the GaN layer 110 grows in the vertical direction, and in the upper region of the mask 120 (hereinafter, referred to as a " wing region "), the GaN layer 110 is formed as shown by an arrow in FIG. Will grow in the direction.

As shown in FIG. 4, after the lateral growth of the GaN layer 110 is completed, the dislocation d propagates in the vertical direction to the GaN layer 110 in the window region where the mask 120 is not formed. In the GaN layer 110 of the wing region where the mask 120 is formed, growth in the lateral direction occurs, so that the potential d of the lower portion of the mask 120 does not propagate upwards, so that the entire region of the GaN layer 110 is increased. Lattice defects in can be reduced.

However, even when the GaN layer 110 is grown using the ELOG method, since the potential d is still high in the window region, the nitride-based semiconductor light emitting diode due to the reduction of lattice defects that can be obtained by the conventional ELOG method. Quality improvement effect is not enough.

Therefore, there is a need in the art for a new way to maximize the quality improvement effect by reducing the grid defects.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to grow a nitride semiconductor layer capable of further improving the quality of nitride-based semiconductor light emitting diodes by reducing lattice defects such as dislocations. To provide.

In order to achieve the above object, the present invention comprises the steps of growing a nitride semiconductor layer on a substrate; Forming a plurality of masks spaced apart from each other by a predetermined distance on the nitride semiconductor layer; Etching portions of the nitride semiconductor layer between the masks; And re-growing the nitride semiconductor layer on the nitride semiconductor layer remaining after the etching.

In the growth method of the nitride semiconductor layer of the present invention, the etching of the nitride semiconductor layer is preferably performed such that the nitride semiconductor layer has a groove having a facet structure.

In the growth method of the nitride semiconductor layer of the present invention, the etching of the nitride semiconductor layer is preferably performed by a wet etching method.

In addition, in the growth method of the nitride semiconductor layer of the present invention, the wet etching is performed using an etching solution including any one selected from the group consisting of KOH, NaOH, H ₃ PO ₄ , H ₂ SO ₄ and HCl. It is desirable to.

In addition, in the growth method of the nitride semiconductor layer of the present invention, the wet etching is preferably performed at a temperature of 50 ℃ to 200 ℃. This is because when the wet etching temperature of the nitride semiconductor layer is less than 50 ° C., etching may not be performed properly, and when it exceeds 200 ° C., the etching solution may evaporate or it may be difficult to control the concentration of the etching solution composition. to be.

In the growth method of the nitride semiconductor layer of the present invention, the nitride semiconductor layer is preferably made of any one selected from the group consisting of GaN, AlGaN, InGaN, and AlInGaN.

In the growth method of the nitride semiconductor layer of the present invention, the mask is preferably made of SiO ₂ or Si ₃ N ₄ .

In the growth method of the nitride semiconductor layer of the present invention, the substrate is preferably made of any one selected from the group consisting of sapphire, Si, AlN, ZnO, AlGaN and SiC.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like reference numerals designate like parts throughout the specification.

Now, a method of growing a nitride semiconductor layer according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

5 to 8 are cross-sectional views sequentially showing the growth method of the nitride semiconductor layer using the ELOG method according to an embodiment of the present invention.

First, as shown in FIG. 5, the nitride semiconductor layer 110 is first grown by a predetermined thickness on the substrate 100.

The substrate 100 is generally made of sapphire, but in addition to sapphire, the substrate 100 may be made of Si, AlN, ZnO, AlGaN, or SiC.

In addition, the nitride semiconductor layer 110 may be made of GaN, and may be made of AlGaN, InGaN, or AlInGaN in addition to GaN. The nitride semiconductor layer 110 is preferably grown by HVPE (Hydride Vapor Phase Epitaxy), MOCVD (Metal Organic Chemical Vapor Deposition), MOVPE (Metal Organic Vapor Phase Epitaxy), or the like. At this time, in the nitride semiconductor layer 110 grown on the substrate 100, as described above, a lattice defect such as dislocation d is inevitably generated.

Next, as shown in FIG. 6, a plurality of masks 120 spaced apart from each other by a predetermined interval are formed on the first grown nitride semiconductor layer 110.

The mask 120 may deposit a dielectric film, such as SiO ₂ or Si ₃ N ₄ , on the nitride semiconductor layer 110 by a plasma enhanced chemical vapor deposition (PECVD) method, and then, through the photolithography method, the dielectric material. It is preferable to form by etching part of the film selectively.

Then, as shown in FIG. 7, portions of the nitride semiconductor layer 110 between the masks 120 are etched. The etching of the nitride semiconductor layer 110 may be performed such that a specific crystal surface of the nitride semiconductor layer 110 is exposed, that is, the nitride semiconductor layer 110 has a facet-shaped groove. Do. The etching of the nitride semiconductor layer 110 is preferably performed by a wet etching method. At this time, the wet etching is preferably performed using an etching solution containing KOH. In addition, as the etching solution, a solution containing NaOH, H ₃ PO ₄ , H ₂ SO _4, HCl, or the like other than KOH may be used.

In addition, the wet etching is preferably performed at a temperature of 50 ℃ to 200 ℃. This is because when the wet etching temperature is less than 50 ° C., the etching may not be performed properly, and when the wet etching temperature is higher than 200 ° C., the etching solution may have difficulty in controlling the concentration of the etching solution composition.

Next, the nitride semiconductor layer 110 is regrown on the nitride semiconductor layer 110 remaining after the etching. In this case, as in the embodiment of the present invention, when the nitride semiconductor layer 110 remaining after etching is regrown, the nitride semiconductor layer 110 grown in the window region between the masks 120 is shown in FIG. 7. As shown by the arrow, the growth in the lateral direction, also in the wing area of the mask 120 is also grown in the lateral direction.

As shown in FIG. 8, after the lateral growth of the nitride semiconductor layer 110 is completed, the nitride semiconductor layer 110 of the window region as well as the nitride semiconductor layer 110 of the wing region has a potential d. It has a high quality crystallinity that contains little.

As described above, according to the growth method of the nitride semiconductor layer according to the present embodiment, the nitride semiconductor layer 110 between the masks 120 is etched and then regrown, so that the wing region of the upper part of the mask 120 may be formed. In addition, growth in the lateral direction may occur in the window region between the masks 120.

Therefore, it is possible to drastically reduce the dislocation d density in the window region, that is, the crystal defect. The reduction of the crystal defects is known to play an important role in extending the life of the nitride-based semiconductor light emitting diode and reducing leakage current, the present invention can contribute to the quality improvement of the nitride-based semiconductor light emitting diode .

Although the preferred embodiments of the present invention have been described in detail above, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the scope of the present invention is not limited to the disclosed embodiments, but various modifications and improvements of those skilled in the art using the basic concept of the present invention as defined in the following claims also belong to the scope of the present invention.

As described above, according to the growth method of the nitride semiconductor layer according to the present invention, the nitride semiconductor layer between the masks are etched and then regrown to form the nitride in the wing region of the upper part of the mask as well as the window region between the masks. By causing the lateral growth of the semiconductor layer to occur, the dislocation density in the window region, that is, the crystal defect, can be drastically reduced.

Therefore, the present invention has the effect of further improving the quality of the nitride semiconductor light emitting diode.

Claims (8)

Growing a nitride semiconductor layer on the substrate; Forming a plurality of masks spaced apart from each other by a predetermined distance on the nitride semiconductor layer; Etching the portion of the nitride semiconductor layer between the masks so as to have only an inclined surface; And Regrowing the nitride semiconductor layer on the nitride semiconductor layer remaining after the etching; Method of growing a nitride semiconductor layer comprising a. The method of claim 1, The etching of the nitride semiconductor layer, the nitride semiconductor layer growth method characterized in that it is performed to have a groove of a facet (facet) structure. The method of claim 1, The etching of the nitride semiconductor layer is a growth method of the nitride semiconductor layer, characterized in that the wet etching method. The method of claim 3, The wet etching may be performed using an etching solution including any one selected from the group consisting of KOH, NaOH, H ₃ PO ₄ , H ₂ SO ₄ and HCl. The method of claim 3, The wet etching is a growth method of the nitride semiconductor layer, characterized in that performed at a temperature of 50 ℃ to 200 ℃. The method of claim 1, The nitride semiconductor layer is a growth method of the nitride semiconductor layer, characterized in that any one selected from the group consisting of GaN, AlGaN, InGaN and AlInGaN. The method of claim 1, The mask is a growth method of the nitride semiconductor layer, characterized in that consisting of SiO ₂ or Si ₃ N ₄ . The method of claim 1, The substrate is a growth method of the nitride semiconductor layer, characterized in that any one selected from the group consisting of sapphire, Si, AlN, ZnO, AlGaN and SiC.

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