KR100999363B1 - Substrate for semiconductor device and semiconductor device using the 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 according to the present invention is a substrate in which a plurality of convex or concave lenses are formed, and in which the side surfaces of the epi layer to be formed on the substrate are well grown, the lenses are arranged in a narrower space than the other directions. It is characterized by.

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 passed through the interface moves inside the LED and decays into heat. As a result, the luminous efficiency is low and the amount of heat generated by the device is increased, 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. FIG. 2A is a micrograph of a surface where an epitaxial layer is neatly grown on a substrate on which a lens is formed, and FIG. 2B is a photograph of a surface where 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 the lens 12 in a shape that looks like water filling up as shown in FIG. 3. You can see this grows up. The preferred thin film growth on the lens-formed substrate is such that the nitride semiconductor epitaxial layer predominates in a flat portion, for example, a (0002) plane, in addition to the lens 12 without the thin film growing in the other crystal direction on the lens 12. It is formed. At this time, if the lens 12 becomes too dense, the flat area becomes very small, and if the area of the area becomes less than that, a dark part with no filled surface is generated as shown in FIG. 2B. This is a surface defect, which causes fatal yield reduction and defects in device fabrication.

The present invention has been made to solve the conventional problems, the problem to be solved by the present invention provides a semiconductor device substrate for increasing the external light extraction efficiency by increasing the packing density of the lens without limiting epilayer growth. It's there.

Another object of the present invention is to provide a high output semiconductor device having improved external light extraction efficiency by using such a substrate.

The semiconductor element manufacturing substrate which concerns on this subject is a semiconductor element manufacturing substrate in which many convex or concave-shaped lenses were formed, WHEREIN: The lateral growth of the epi layer to form on a said board | substrate is different It is characterized in that the lenses are arranged such that the space between the lenses is narrower than the direction.

According to one embodiment, while maintaining the planar symmetry of the lens, the distance between the lens is arranged closer to the other direction in the direction of the side growth of the epi layer is better. According to another embodiment, the planar shape of the lens is elongated along the lateral growth of the epi layer.

In the present invention, the substrate is sapphire, the epi layer is a nitride semiconductor, and the lateral growth is good in the <1-100> direction of the sapphire.

According to another aspect of the present invention, there is provided a semiconductor device manufacturing substrate, an epitaxial layer including at least an n-type semiconductor layer, an active layer, and a p-type semiconductor layer as an epitaxial layer formed on the substrate. An electrode is formed on each of the n-type semiconductor layer and the p-type semiconductor layer.

According to the present invention, the space between the lenses is narrowed in the direction in which the lateral growth of the epi layer is good, thereby securing a space in the direction in which growth is unlikely in the lens pattern of the same packing density. Thereby, the epi layer can be smoothly grown to grow an epi layer having excellent surface and crystallinity. This directly leads to an improvement in performance and an increase in yield in manufacturing a semiconductor device such as a semiconductor light emitting device.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. The embodiments described below may be modified in many different forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

The conventional lens has a pattern with constant shape and spacing as shown in FIG. For example, the lens 12 is located at the apex of the repeating equilateral triangle pattern, and the diameter D of the lens 12 is 2.5 μm, and the distance s1 between the lens centers along the <11-20> direction of the nitride semiconductor, for example GaN. ) Is 4 µm (i.e., the flat portion other than the lens, that is, the space d between the lenses is 4-2.5 = 1.5 µm), and the distance s2 between the lens centers along the <1-100> direction of GaN is 6.9282 µm. All. 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.

Referring to FIG. 2B again, in which the filling density of such a lens is not filled with the epi layer along with the direction of the substrate, the portion where the epi layer is not grown is arranged in a line, and this direction is <11 of GaN. -20> direction. This means that the growth of the epi layer is not limited to <11-20> and there is a limit in the vertical direction of <1-100>. This feature can also be inferred from the lateral growth rate of the nitride semiconductor epi layer. Nitride semiconductors grow very fast in the <11-20> direction and grow very slowly in the <1-100> direction.

With the above phenomena and theories, in the present invention, in order to solve the epilayer growth problem while maintaining the high packing density of the lens, the GaN direction of <11-20> where lateral growth is good without constant distance between lenses is maintained. (InGaAlN is formed on the sapphire substrate in the vertical direction, so the direction of the sapphire is <1-100>). A method of arranging an asymmetric lens that forms a narrowly spaced pattern and forms a wide pattern in the other direction is presented.

5 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 to have a narrower space between the lenses than the other directions in the direction in which the lateral growth of the epi layer to be grown thereon is good. 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 <11-20> direction (InGaAlN on the sapphire substrate is formed in a vertical direction The direction of the sapphire is <1-100>) to form a narrowly spaced pattern and the other direction to form a wide pattern.

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 FIG. 5 and may be embossed or concave to have a convex or concave shape. 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. .

In FIG. 5, the parallelograms indicated by dotted lines are unit cells, and the area ratio occupied by the lens is the filling density. The filling density of FIG. 5 is the same as the filling density of FIG. 4. In order to maintain the filling density in this way, the lens 112 is located at the apex of the repeating isosceles triangle pattern, and the length of the lower side of the isosceles triangle pattern is the distance between the lens centers (s1 '), and the length of the isosceles (s3) is 4.1942 µm. to be. The diameter D 'of the lens is 2.5 μm, the same as the lens diameter D of FIG. 4, and the distance s1 ′ between the lens centers in the <11-20> direction of GaN is greater than the distance s1 of FIG. 4. 3.7 μm (there is a flat portion other than the lens, i.e., the space d 'between the lenses is 3.7-2.5 = 1.2 μm, which is narrower than the portion d of FIG. 4), and <1-100> of GaN. The distance s2 'between the lens centers along the direction is larger than that distance s2 in FIG. 4 and is 7.5282 mu m. However, the numerical values exemplified herein can be changed as many as possible while maintaining their tendency and magnitude.

As such, if the lens gap in one direction where the lateral growth of the epi layer is well maintained while maintaining a high filling density, the epitaxial layer may be normally grown because the lens interval in the other direction where the epi layer lateral growth is not increased.

6 is a lens pattern according to another embodiment of the present invention. In forming an intaglio or embossed lens on the substrate, the planar shape of the lens 212 is extended in one direction to adjust the gap. Specifically, the lens pattern is formed to have a narrower space than other directions by extending the planar shape of the lens in a direction in which the lateral growth of the epitaxial layer to be grown thereon is good.

The lens of FIG. 6 is arranged at the same position as the lens of FIG. 4 (i.e., at the vertex of the repeating equilateral triangle pattern), wherein the lens has a length r1 of 3 m along the <11-20> direction of GaN. The length r2 of the short axis along the <1-100> direction of GaN is an ellipsoid of 2 μm, and the distance s1 ″ between the lens centers along the <11-20> direction of GaN is the distance s1 of FIG. 4. 4 μm (therefore, a flat portion other than the lens, that is, the space d ″ between the lenses is 4-3 = 1 μm, which is narrower than the portion d of FIG. 4), and <1- of GaN. The interval s2 ″ between the lens centers along the 100> direction is 6.9282 μm, which is the same as the interval s2 in FIG. 4. The distance s1 ″ between the lens centers corresponds to one side of the repeating equilateral triangle pattern. However, the numerical values exemplified herein can be changed as many as possible while maintaining their tendency and magnitude.

Meanwhile, in the embodiments, the substrate is sapphire as an example, but as the substrate on which the nitride semiconductor epitaxial layer can be grown, materials such as GaAs, InP, Si, SiC, spinel, GaN, and the like may be used. According to this, since the direction in which the lateral growth of the epitaxial layer grown therein may vary, the lens may be arranged by selecting a direction to narrow the space between the lenses.

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

Referring to FIG. 7, 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 having a shape and an interval as shown in FIGS. 5 to 6, and the lens 112 as shown in FIG. 5 is formed here.

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. The lens 112 secures a space in a direction in which growth is poor in a lens pattern having the same filling density by narrowing the space between the lenses in a direction in which the lateral growth of the epi layer 130 is well. As a result, the epi layer 130 may be smoothly grown to grow the epi layer 130 having excellent surface and crystallinity. This leads directly to improved performance and increased yield in the fabrication of semiconductor devices.

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 such, the semiconductor device according to the present invention may be implemented as a light emitting device such as a high output LED having improved external light extraction efficiency by using the substrate 110 on which the lenses 112 are arranged asymmetrically.

As mentioned above, the present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the technical idea of the present invention. It is obvious. Embodiments of the invention have been considered in all respects as illustrative and not restrictive, including the scope of the invention as indicated by the appended claims rather than the detailed description therein, the equivalents of the claims and all modifications within the means. I want to.

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.

FIG. 2A is a micrograph of a surface in which an epitaxial layer is neatly grown on a substrate on which a lens is formed.

FIG. 2B is a photograph of a surface in which an epitaxial layer is grown non-ideally on a very narrow substrate between lenses.

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

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

5 is a lens arrangement diagram according to the first embodiment of the present invention having a pattern having a constant shape but different intervals.

6 is a lens arrangement diagram according to a second exemplary embodiment of the present invention in which the distance between lenses has a different pattern according to a direction as the shape is deformed in one direction.

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

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

110 ... substrate 112, 212 ... lens 120 ... n-type semiconductor layer

122 ... active layer 124 ... p-type semiconductor layer 130 ... epi layer

140, 142 ... electrode

Claims (5)

In a substrate for manufacturing a semiconductor element, in which a plurality of convex or concave lenses are formed, While maintaining the filling density when the distance between the lenses is the same A substrate for manufacturing a semiconductor device, characterized in that the plurality of lenses is formed so that the space between the lenses is narrower than the other direction in the direction of the lateral growth of the epi layer to be formed on the substrate. The semiconductor device manufacturing substrate of claim 1, wherein the distance between the lenses is arranged closer to each other in a direction in which the lateral growth of the epi layer is better while maintaining the plane symmetry of the lens. The substrate for manufacturing a semiconductor device according to claim 1, wherein the planar shape of the lens is elongated along a direction in which the lateral growth of the epi layer is well performed. The semiconductor according to any one of claims 1 to 3, wherein the substrate is sapphire, the epi layer is a nitride semiconductor, and the lateral growth direction is a <1-100> direction of the sapphire. Substrate for device manufacturing. A substrate for manufacturing a semiconductor device according to claim 4; An epitaxial layer including at least an n-type semiconductor layer, an active layer and a p-type semiconductor layer as an epitaxial layer formed on the substrate; And And an electrode formed on each of the n-type semiconductor layer and the p-type semiconductor layer.

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