KR101055266B1 - Substrate for semiconductor device and semiconductor device using same - Google Patents

Abstract

Disclosed are a substrate for manufacturing a semiconductor device which increases the filling density of a lens without increasing the epitaxial growth and increases the external light extraction efficiency, and a high output semiconductor device having improved external light extraction efficiency by using the substrate. The substrate for manufacturing a semiconductor device according to the present invention is a substrate on which a plurality of convex or concave lenses are formed, and the gap between the lenses arranged in a direction orthogonal to the direction in which the lateral growth of the epi layer to be formed on the substrate is good. The plurality of lenses is formed so as to be narrow compared to the interval between the lenses arranged in different directions.

Description

Substrate for semiconductor device and semiconductor device using the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for a semiconductor device and a semiconductor device using the substrate, and more particularly, a substrate having a pattern formed so as to be used for manufacturing a semiconductor light emitting device such as a high output light emitting diode (LED), and a semiconductor using the substrate. It relates to an element.

The LED market grew based on low-power LEDs used in portable communication devices such as mobile phones, keypads of small home appliances, and back light units of liquid crystal displays (LCDs). Recently, as the need for high-power and high-efficiency light sources for interior lighting, exterior lighting, automotive interior and exterior, and large LCD backlight units has emerged, the LED market is shifting to high-power products.

The biggest issue in LED development is to increase luminous efficiency. In general, the luminous efficiency is determined by the light generation efficiency (internal quantum efficiency), the efficiency emitted outside the device (external light extraction efficiency), and the phosphor conversion efficiency. In order to increase the output power of the LED, it is important to improve the active layer characteristics in terms of internal quantum efficiency, but it is very important to increase the external light extraction efficiency of the generated light.

The biggest obstacle to the emission of light outside the LED is internal total reflection due to the difference in refractive index between each layer of the LED. Due to the difference in refractive index between the LED layers, the light exiting the interface corresponds to about 50% of the generated light. In addition, the light that has not exited the interface moves inside the LED and decays into heat, resulting in low luminous efficiency and increased heat generation of the device, thereby shortening the life of the LED.

In order to improve the external light extraction efficiency, a method of increasing the roughness of the surface of the device, and a curved shape (hereinafter, concave or convex) in the base portion of the device and the surface of the substrate on which the epi layer is grown are referred to as "lens". And the like). Forming a lens on the substrate reduces the probability that light above the critical angle is reflected into the device, thereby improving external light extraction efficiency.

FIG. 1A is a schematic cross-sectional view of an LED 30 formed over a lens 12 formed by etching the sapphire substrate 10, and FIG. 1B is an SEM image of the lens 12 formed by etching the sapphire substrate 10. .

When the density of the lens 12 is increased, the external light extraction efficiency is increased, but the gap between the lenses 12 is very narrow, and the growth of the epi layer is very limited when the substrate and the heterogeneous epi layer are grown different from the material grown thereon. There is a problem that you receive. 2 is a micrograph of a surface in which an epitaxial layer is cleanly grown on a substrate on which a lens is formed, and FIGS. 3A and 3B are photographs of a surface in which an epitaxial layer is abnormally grown on a very narrow substrate between lenses.

To understand the cause of such non-ideal growth, look at the initial stage of epilayer growth on the substrate on which the lens is listed, the epilayer 20 at the periphery except for the lens 12 in a water-like appearance as shown in FIG. You can see that this grows up. As such, the preferred thin film growth on the substrate on which the lens 12 is formed is nitride semiconductor epitaxial on a flat portion, for example, a (0002) plane other than the lens 12 without the thin film growing in the other crystal direction on the lens 12. The layer is predominantly formed. At this time, if the lens 12 is too dense, the flat area becomes very small, and if the area of the area is less than or equal to the area, as shown in FIGS. 3A and 3B, dark areas where the surface is not filled are generated. This is a surface defect, which causes fatal yield reduction and defects in device fabrication.

The technical problem to be solved by the present invention is to provide a substrate for a semiconductor device that increases the external light extraction efficiency by increasing the filling density of the lens without limiting epitaxial growth.

Another technical problem to be solved by the present invention is to provide a high output semiconductor device with improved external light extraction efficiency by using such a substrate.

In order to solve the above technical problem, the semiconductor device substrate according to the present invention is a substrate for semiconductor device manufacturing in which a plurality of convex or concave lenses are formed, and the side surface growth of the epi layer to be formed on the substrate is good. And the plurality of lenses are formed such that the distance between the lenses arranged in the direction orthogonal to is narrower than the distance between the lenses arranged in the other direction.

In the substrate for semiconductor devices according to the present invention, the plurality of lenses are arranged to form a plurality of rows in a direction orthogonal to a direction in which the lateral growth of the epi layer is good, and the plurality of rows and the columns are spaced at equal intervals There may be. The lenses forming each row may be in contact with each other.

In the substrate for semiconductor elements according to the present invention, the substrate is sapphire and the epi layer is a nitride semiconductor, and the direction orthogonal to the direction in which the lateral growth of the epi layer is good is the <11-20> direction of the sapphire substrate.

In order to solve the above other technical problem, the semiconductor device according to the present invention is a semiconductor device manufacturing substrate according to the present invention; An epitaxial layer formed on the substrate, the epitaxial layer including at least an n-type semiconductor layer, an active layer and a p-type semiconductor layer; And electrodes formed on the n-type semiconductor layer and the p-type semiconductor layer, respectively.

According to the present invention, by narrowing the interval between the lenses arranged in the direction orthogonal to the direction in which the lateral growth of the epi layer is good, it is possible to grow the epi layer with excellent crystallinity while improving the filling density of the lens. Therefore, if a semiconductor device such as a light emitting diode is manufactured using the substrate on which the lens is formed, it is possible to grow an epitaxial layer having excellent crystallinity with high external light extraction efficiency, thereby improving device performance and increasing yield. Will be imported.

Hereinafter, a semiconductor device substrate and a semiconductor device using the same according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you.

The conventional lens has a pattern with a constant interval as shown in FIG.

5, the lens 12 is located at the apex of the repeating equilateral triangle pattern, the diameter (D) of the lens 12 is 2.5㎛, the lens center along the <11-20> direction of the nitride semiconductor, for example GaN Spacing s1 is 4 µm (i.e., a flat portion other than the lens, i.e., the space d between the lenses is 4-2.5 = 1.5 µm), and the spacing between lens centers along the <1-100> direction of GaN (s2). ) Is 6.9282 µm. The interval s1 between the lens centers corresponds to one side of the repeating equilateral triangle pattern. As an example of a method for calculating the filling density, the parallelograms indicated by dotted lines are unit cells, and the area ratio occupied by the lens is the filling density.

When the filling density of the lens is increased by narrowing only the distance between lenses in a pattern shape in which a conventional distance between lenses is constant, a portion which is not filled with an epitaxial layer appears as shown in FIGS. 3A and 3B. Nitride semiconductors grow very fast in the <11-20> direction and very slowly in the <1-100> direction.

With the above phenomenon and theory, in the present invention, in order to solve the epitaxial growth problem while increasing the packing density of the lens, the direction perpendicular to the direction in which the lateral growth of GaN is good without having a constant gap between lenses <1- 100> (InGaAlN is formed on the sapphire substrate in the vertical direction, the direction of the sapphire substrate is <11-20>) to form a narrowly spaced pattern and to form a wide pattern in the other direction. present.

6 is a lens pattern according to an embodiment of the present invention. In forming a large number of convex or concave lenses on the substrate, the spacing is adjusted while maintaining the planar symmetry of the lens 112. Specifically, the lenses are arranged in a direction perpendicular to the direction in which the lateral growth of the epitaxial layer to be grown thereon is orthogonal to the gap between the lenses in comparison with other directions. That is, after rotating the lens pattern shown in FIG. 5 by 90 °, the lens gap in the vertical direction is narrowly arranged. For example, the substrate is sapphire and the epi layer is a nitride semiconductor, such as GaN, AlGaN, GaInN, InGaAlN, etc. In particular, in the GaN <1-100> direction of GaN (InGaAlN on the sapphire substrate is formed in the vertical direction sapphire The direction of the substrate is <11-20>) to form a narrow gap pattern, and the other direction to form a wide pattern.

Preferably, the lens 112 is arranged such that a plurality of rows are formed in a direction orthogonal to the direction in which the lateral growth of the epi layer is good. The lenses 112 are arranged to be equally spaced apart from the plurality of rows. In particular, when the substrate is sapphire and the epi layer is GaN, as shown in FIG. 6, the lens 112 is formed such that a plurality of rows are formed in the <1-100> direction of GaN (the direction of the sapphire substrate is <11-20>). ) At this time, the lens 112 is arranged such that the distance d ₁ between the lenses 112 formed in each row is narrower than the gap d ₂ between the rows and the rows. The lenses 112 formed in each column may be arranged to be in contact with each other, that is, d ₁ may be zero.

In actual substrate fabrication, an etching mask is formed on a substrate (sapphire, GaAs, InP, Si, SiC, spinel, GaN, etc.) in a pattern as shown in FIG. In this case, the etching mask may be a photoresist, an oxide film, a metal film, or the like. Etch masks are used to dry or wet etch and remove the etch mask. The lens formed on the substrate may be a material of the substrate itself or an etching thereof after depositing a material such as SiO ₂ , SiON, SiN on the substrate. The lens is formed in the shape, intervals as shown in Figure 6 and is formed in an embossed or intaglio may be convex or concave. The flat shape of the lens can be circular or various polygons (square hexagon, equilateral triangle, square, etc.), and the cross-sectional shape can be various shapes such as square, trapezoid, triangle, etc., depending on the type of etching mask, shape or selection ratio of etching. .

A planar SEM photograph of the substrate on which the lenses 112 are arranged using this method is shown in FIG. 7. The interval in the GaN <1-100> direction of the lens 112 arranged on the substrate shown in FIG. 7 is almost zero. When the GaN epitaxial layer is grown by using the substrate shown in FIG. 7, the GaN epitaxial layer grows vertically through the exposed portions of the substrates between the lenses 112, and then the GaN epitaxial layer rapidly moves toward the GaN <11-20> direction. As it grows, the GaN epitaxial layer grows cleanly without filling the portion. After growing the GaN epilayer using the substrate shown in FIG. 7, the SEM photograph of the surface of the GaN epilayer is shown in FIG. As shown in FIG. 8, it can be seen that when the substrate according to the present invention is used, an epi layer having a clean surface can be obtained.

In FIG. 6, the parallelogram represented by a dotted line is a unit cell, and the area ratio occupied by the lens therein becomes the filling density. The filling density of FIG. 6 is controlled by d ₁ and d ₂ to be larger than the filling density of FIG. 5. Can be arranged. And even if the lens 112 is arranged to be larger than the filling density of Figure 5, the epi layer grows normally.

Meanwhile, in the embodiments, the substrate has been described as an example of sapphire, but as a substrate capable of growing a nitride semiconductor epitaxial layer, materials such as GaAs, InP, Si, SiC, spinel, GaN, and the like may be used. Depending on the type, the direction in which the lateral growth of the epitaxial layer grown therein may be more predominant. Therefore, the lenses may be arranged by selecting a direction to narrow the space between the lenses.

9 is a cross-sectional view of a semiconductor device according to the present invention.

9, an epitaxial layer 130 is formed on a substrate 110 for manufacturing a semiconductor device according to the present invention. The substrate 110 has a lens 112 having a shape and a gap as shown in FIG. 6.

The epi layer 130 includes at least an n-type semiconductor layer 120, an active layer 122, and a p-type semiconductor layer 124. If necessary, a semiconductor single crystal film may be first grown on the lens 112 under the n-type semiconductor layer 120. As described above, the lens 112 narrows the space between the lenses in a direction orthogonal to the direction in which the lateral growth of the epi layer 130 is good, while increasing the filling density and smoothly growing the epi layer 130. can do. As a result, the epitaxial layer 130 having excellent surface and crystallinity can be grown. This directly leads to the improvement of the performance and the yield of the semiconductor device.

The n-type semiconductor layer 120 is formed by doping impurities such as Si, Ge, Se, Te, and the like to GaN, AlGaN, GaInN, InGaAlN, and the like, and are formed through a deposition process such as MOCVD, MBE, or HVPE. The active layer 122 is a layer for emitting light, and is usually formed by forming a multi-quantum well using an InGaN layer as a well and a GaN layer as a wall layer. The p-type semiconductor layer 124 is formed by doping impurities such as GaN, AlGaN, GaInN, InGaAlN, and the like with Mg, Zn, and Be. Electrodes 140 and 142 are formed on the n-type semiconductor layer 120 and the p-type semiconductor layer 124, respectively.

As described above, the semiconductor device according to the present invention uses the substrate 110 having a narrow gap between the lenses 112 arranged in a direction orthogonal to the direction in which the lateral growth of the epi layer 130 is good, thereby extracting external light. It can be implemented as a light emitting device such as a high power LED with improved efficiency.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific preferred embodiments described above, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

1A is a cross-sectional view of an LED formed on a substrate on which a lens is formed.

1B is an SEM image of a lens formed by etching a sapphire substrate.

2 is a micrograph of the surface of the epi layer on which the lens is formed on the substrate.

3A and 3B are photographs of a surface on which an epitaxial layer is grown abnormally on a very narrow substrate between lenses.

FIG. 4 is an SEM image of an initial stage in which an epitaxial layer is grown on a substrate on which lenses are listed. FIG.

5 is a conventional lens arrangement with a pattern having a constant shape and spacing.

6 is a lens arrangement diagram according to the present invention.

7 is a planar SEM photograph of a substrate for manufacturing a semiconductor device according to the present invention.

FIG. 8 is a SEM photograph of the epi layer surface after the epi layer is grown using the substrate shown in FIG. 7.

9 is a cross-sectional view of a semiconductor device according to the present invention.

Claims (5)

In a substrate for manufacturing a semiconductor element, in which a plurality of convex or concave lenses are formed, The plurality of lenses are formed such that the distance between the lenses arranged in the direction orthogonal to the direction in which the lateral growth of the epi layer to be formed on the substrate is orthogonal is smaller than the distance between the lenses arranged in the other direction, Wherein the substrate is a sapphire substrate, the epi layer is a nitride semiconductor, and a direction orthogonal to a direction in which the lateral growth of the epi layer is well formed is a <11-20> direction of the sapphire substrate. The method of claim 1, The plurality of lenses are arranged to form a plurality of rows in a direction orthogonal to the direction in which the lateral growth of the epi layer is good, the substrate and the semiconductor device manufacturing substrate, characterized in that spaced apart at equal intervals. The method of claim 2, A lens for forming a semiconductor device, wherein the lenses forming each row are in contact with each other. delete A substrate for manufacturing a semiconductor device according to claim 1; An epitaxial layer formed on the substrate, the epitaxial layer including at least an n-type semiconductor layer, an active layer and a p-type semiconductor layer; And And an electrode formed on the n-type semiconductor layer and the p-type semiconductor layer, respectively.

Images