KR100984041B1 - Substrate for semiconductor device, method for fabricating the same and semiconductor device using the same - Google Patents

Abstract

Disclosed are a substrate for a semiconductor device that increases external light extraction efficiency without limiting epitaxial growth, a manufacturing method thereof, and a high output semiconductor device having improved external light extraction efficiency by using the substrate. The substrate for semiconductor elements according to the present invention includes a plurality of convex lenses, and a recess is formed along the lens outer periphery, which is recessed from the surface of the substrate between the lenses. In the method of manufacturing a substrate for a semiconductor device according to the present invention, an etching mask is formed on a substrate, and then dry etching is performed through the etching mask to form a convex lens on the substrate, and a substrate between the lenses along the lens circumference. Form recesses recessed from the surface.

Description

Substrate for semiconductor device, method for fabricating the same 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, a method for manufacturing the same, and a semiconductor device using the substrate, and more particularly, a substrate having a pattern formed thereon so as to be used for manufacturing a semiconductor light emitting device such as a high power light emitting diode (LED), A method and a semiconductor device using the substrate.

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 light actually generated.

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. .

If the lens 12 is densely arranged to increase the density, the external light extraction efficiency is increased, but the gap between the lenses 12 becomes very narrow, so that the epitaxial layer grows when the heterogeneous epitaxial layer is grown on the substrate and other materials. There is a problem that is very limited. FIG. 2A is a micrograph of a surface where an epi layer is neatly grown on a substrate on which a lens is formed, and FIG. 2B is a photograph of a surface where an epi layer is abnormally grown on a very narrow substrate between lenses, and GaN is grown on a sapphire substrate. It is the case. As shown in FIG. 2B, the dark portion where the surface is not filled 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 is a semiconductor device substrate and a manufacturing method that can increase the external light extraction efficiency even if the lens is not closely arranged through the lens shape change To provide.

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 substrate for semiconductor elements according to the present invention for solving the above problems includes a plurality of convex lenses, and a recess is formed along the lens outer circumference, which is recessed than the substrate surface between the lenses.

In the method of manufacturing a substrate for a semiconductor device according to the present invention, an etching mask is formed on a substrate, and then dry etching is performed through the etching mask to form a convex lens on the substrate, and a substrate between the lenses along the lens circumference. Form recesses recessed from the surface.

According to another aspect of the present invention, there is provided a semiconductor device 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, by forming the convex periphery of the lens, the lens also has a deep effect and the same effect as increasing the density of the lens. Thus, by modifying the shape of the lens, it is possible to increase the external light extraction efficiency even if the lens is not deliberately arranged, it is possible to grow the epi layer with excellent surface and crystallinity by smoothing the epi layer growth. 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.

3A is a schematic cross-sectional view of a substrate for semiconductor devices according to the present invention.

A plurality of convex lenses 112 protruding from the reference plane G are formed on the substrate 110, and recesses 115 are formed in each lens 112 around the lens 112. The five neck 115 is recessed than the reference plane (G). The reference plane G may be defined as a surface of the substrate 110 or may be defined as an interface between the substrate 110 and the material when a predetermined material is deposited on the substrate 110. In any case, the reference plane G is referred to as the surface of the substrate 110 between the lenses 112, and thus the recess 115 may be defined as being recessed than the surface of the substrate 110 between the lenses 112. In some cases, the recesses 115 may be formed between the lenses 112 without a flat portion between the lenses 112, that is, without the reference plane G.

The substrate 110 may be any one of materials such as sapphire, GaAs, InP, Si, SiC, spinel, GaN, and the like, and the lens 112 may be a material of the substrate 110 itself, or SiO ₂ on the substrate 110. After depositing a material such as SiON, SiN, etc. may be etched. The flat shape of the lens 112 may be circular or various polygons (eg regular hexagon, equilateral triangle, square, etc.), and the cross-sectional shape may have various shapes such as a rectangle, a trapezoid, and a triangle depending on the type of the etching mask, the shape or the selection ratio of the etching. This is possible. 3A illustrates a case in which the cross-sectional shape is a triangle.

FIG. 3B is an SEM photograph of a substrate actually manufactured according to the present invention, which will be described later. FIG. 3C is an enlarged SEM photograph of a lens portion. Here, it can be seen that the cross-sectional shape of the lens is a pentagonal shape close to the trapezoid, and the concave portion is formed for each lens. The recess is formed in a ring shape surrounding the lens outer periphery by etching the substrate to a predetermined depth.

As described above, the substrate for a semiconductor device according to the present invention has a deep effect by forming a concave around the convex lens and an effect such as increasing the density of the lens. Therefore, the external light extraction efficiency can be increased even if the lens is not deliberately arranged, and the epi layer can be grown by smoothly growing the epi layer.

4 is a plan view of the lens pattern.

For example, the substrate is sapphire and the lens has a pattern with a constant shape and spacing as shown in FIG. For example, the lens 112 is located at the apex of the repeating equilateral triangle pattern, and the diameter D of the lens 112 is 2.5 μm, and the distance s1 between the centers of the lenses along the <11-20> direction of the nitride semiconductor, eg, 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. Conventionally, in order to increase the filling density, the lenses are arranged closely by narrowing the distance between the lenses. However, the present invention is characterized in that the concave portion is formed around the lens with the gap between the lenses intact to obtain an effect such that the lens filling density is actually increased.

5 is a cross-sectional view illustrating a process of manufacturing a substrate for a semiconductor device according to the present invention by forming a lens in the same pattern as in FIG. 4.

As shown in FIG. 5A, an etching mask 111 is formed on a substrate 110 such as sapphire, GaAs, InP, Si, SiC, spinel, GaN, or the like. The lens formed on the substrate 110 may be a material of the substrate 110 itself or an etching thereof after depositing a material such as SiO ₂ , SiON, SiN on the substrate 110. Therefore, if necessary, an etching mask 111 is formed on the substrate 110 after deposition of a material such as SiO ₂ , SiON, SiN, or the like. In this case, the etching mask 111 may select a photoresist, an oxide film, a metal film, or the like. In order to simultaneously form the intaglio and the embossed according to the present invention, it is preferable that the material of the etching mask 111 is formed in a form having a vertical wall surface as shown in FIG.

Next, as shown in FIGS. 5B to 5E, etching is performed to form the lens 112 and the recess 115 around the lens 112. It mainly uses dry etching, especially by RIE method. At this time, the lens 112 and the concave portion 115 may be formed at the beginning, but once the lens 112 is formed, the pressure and the bias are then adjusted to increase the incident amount of ions and the lens as indicated by the arrow E. An intaglio recess 115 may be generated around the convex lens 112 by adjusting the incident direction with respect to the circumference 112.

The depth of the recess 115 is adjustable in the form of the hardness (hardness) of the etching mask 111. When the hardness of the etch mask 111 is small and easily etched away, the depth of the recess 115 is shallow. On the contrary, when the hardness is large, the depth of the recess 115 is deep. can do. In addition, when the etching mask 111 has a vertical wall surface, the recess 115 may be formed deeper. However, when the etching mask 111 has a round wall surface like an island, the recess 115 may be shallow. Can be.

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

An epitaxial layer 130 is formed on the semiconductor device substrate 110 according to the present invention. The substrate 110 is an example in which a lens having a shape and a gap as shown in FIG. 3B is formed.

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. Since the concave portion 115 is formed around the lens 112, there is an effect that the actual lens 112 is deepened and the density is increased. However, since the space between the lenses 112 is secured without being narrowed, 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 described above, 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 lens 112 and the lens peripheral recess 115 are formed.

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 spirit of the present invention. It is obvious. Embodiments of the invention have been considered in all respects as illustrative and not restrictive, which include 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.

3A is a schematic cross-sectional view of a substrate for semiconductor devices according to the present invention.

3B is an SEM photograph of a substrate actually manufactured according to the manufacturing method of the present invention, and FIG. 3C is an enlarged SEM photograph of a lens portion.

4 is a plan view of the lens pattern.

FIG. 5 is a cross-sectional view illustrating a process of manufacturing a semiconductor device substrate according to the present invention by forming a lens in the same pattern as FIG. 4.

6 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 111 ... etch mask 112 ... lens

115 ... recessed part 120 ... n-type semiconductor layer 122 ... active layer

124 ... p-type semiconductor layer 130 ... epi layer 140, 142 ... electrode

Claims (5)

delete Forming an etch mask on the substrate; Performing dry etching through the etching mask to form a convex lens on the substrate; And Adjusting at least one of the pressure and the bias of the dry etching to increase the incident amount of ions and to adjust the incident direction with the directionality around the lens to form recesses recessed than the surface of the substrate between the lenses along the lens periphery; Substrate manufacturing method for a semiconductor device comprising a. The method of claim 2, wherein the mask is formed in a shape having a vertical wall surface. delete delete

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