KR100808012B1 - Light emitting diode having improved efficiency and manufacuring method thereof - Google Patents

Abstract

The present invention relates to a light emitting diode having improved luminous efficiency and a method of manufacturing the same. In the light emitting diode, a plurality of scattering points are irregularly disposed in a semiconductor film, and the scattering points are formed of an oxide film or a nitride film or formed into an empty space, and a plurality of irregularities are irregularly formed on a lower surface of the scattering point. Its surface is not flat. The scattering points may be formed of an oxide film or a nitride film, or may be formed of a spatial scattering point having a hollow inside.

According to the present invention, a light emitting diode having scattering points having an uneven bottom surface prevents the generated light from totally reflecting inside the active layer, thereby increasing the scattering effect, and as a result, the luminous efficiency.

Scatter Point, Light Emitting Diode, Total Reflection

Description

Light emitting diode having improved luminous efficiency and manufacturing method thereof

1 is an exemplary cross-sectional view for explaining scattering points according to the related art.

FIG. 2 is a cross-sectional view illustrating scattering points in which a lower surface of the lower surface formed by a method of manufacturing a light emitting diode according to an exemplary embodiment of the present invention is not flat.

3 is a cross-sectional view sequentially illustrating a process of manufacturing a light emitting diode having a scattering point, such as an oxide film having a non-flat lower surface, according to a first embodiment of the present invention.

FIG. 4 is an SEM image exemplarily illustrating a surface of a semiconductor film in which a plurality of irregularities are irregularly formed on a surface according to the first embodiment of the present invention.

FIG. 5 is an SEM image exemplarily showing a state in which scattering points are formed in which the lower surface is not flat according to the first embodiment of the present invention.

6 is a cross-sectional view sequentially illustrating a process of manufacturing a light emitting diode having a spatial scattering point of which the lower surface is not flat according to the second embodiment of the present invention.

7 is a cross-sectional view sequentially illustrating a process of manufacturing a light emitting diode having a spatial scattering point of which the lower surface is not flat according to the third embodiment of the present invention.

FIG. 8 is a cross-sectional view sequentially illustrating a process of manufacturing a light emitting diode having a scattering point and a spatial scattering point of an oxide film having an uneven bottom surface according to a fourth embodiment of the present invention.

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

300, 600, 700, 800: substrate

101, 102, 103, 201, 202, 203: scattering point

332, 632, 832: oxide film scattering point

652, 750, 840: space scattering point

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode having an improved luminous efficiency and a method of manufacturing the same, and more particularly to a light emitting diode and a semiconductor film fabricated using a semiconductor film having scattering points whose bottom surface is not flat. It relates to a manufacturing method for forming scattering points that do not.

A light emitting diode is a semiconductor optical device that directly converts an electric current applied from the outside into light using a PN junction of a semiconductor. The light emitting diode is largely composed of a P-type semiconductor film, an N-type semiconductor film, and an active layer formed between the P-type semiconductor film and the N-type semiconductor film, and light generated in the active layer is emitted to the outside.

Currently, the three primary colors of light, red, green, and blue can all be implemented as light emitting diodes, and the light emitting diodes have excellent advantages in terms of size, environment, and energy saving. Recently, the light emitting diodes have been widely used as light sources of small mobile communication devices such as mobile phones and PDAs, and their application fields have also been expanded to light sources of medium and large liquid crystal displays. As the field of application is expanded and used as a light source, there is a great demand for improvement of luminous efficiency for LEDs.

Briefly looking at the operation principle of the light emitting diode, as a current is applied to the light emitting diode, holes of the P-type semiconductor film and electrons of the N-type semiconductor film is recombined in the active layer to emit light. Light generated in the active layer is emitted in all directions. When the light encounters a dissimilar material, light having an angle of incidence that satisfies the condition causing total reflection at the interface does not penetrate through the dissimilar material and is totally reflected inside the diode. Over and over again. The angle causing the total reflection is determined by the refractive indices of the two media. The larger the difference in the refractive index at the interface between the two media, the narrower the angle that can pass through without total reflection. Therefore, the light emitted from the actual light emitting diode is a part of the light emitted from the active layer escapes the LED without total reflection, and the rest is extinguished inside the LED.

In order to improve these disadvantages, methods for increasing the brightness of LEDs by forming irregularities at the interface where heterogeneous media meet to allow scattering of light have been studied and are actually applied to light emitting diodes.

Korean Patent No. 10-452749, “III-nitride semiconductor light emitting device having a high density fine surface lattice,” has proposed a technique for forming irregularities at an interface where heterogeneous media meet. The proposed patent uses a method of giving irregularities to the exposed N-type semiconductor film during the manufacturing process of the LED chip. However, this has a problem in that the area where the unevenness is formed is limited.

On the other hand, US Patent US 006821804 is 'Enhanced light extraction in LEDs through the use of internal and external optical elements', a light having a different refractive index and semiconductor film on the interface between the P-type semiconductor film or the sapphire substrate and the N-type semiconductor film A technique for inserting an array of extraction elements or a dispenser layer is disclosed. The shape of the element disclosed in the above-mentioned patent is usually a round shape or a shape having a part of an inclined straight line, and the light generated in the active layer is scattered at the interface of the above-described element to facilitate the emission to the outside of the diode chip. Will increase.

On the other hand, conventional techniques of inserting scattering points having different refractive indices into a semiconductor film in order to increase the brightness of the light emitting diodes can be scattered by effectively modifying the shape of the scattering point. 1 is a cross-sectional view illustrating exemplary shapes of a scattering point according to the related art. As shown in FIG. 1, light generated in the active layer is scattered by the inclination angle of the scattering point and reflected back upwards, but some light passes through the scattering point and is reflected back at the interface between the semiconductor film and the lower substrate, You will be directed to. For this light, the flat lower surface of the scattering points reflects the upward light and directs it downward, thereby preventing it from escaping outside.

SUMMARY OF THE INVENTION An object of the present invention for solving the above problems is to provide a light emitting diode having a semiconductor film having scattering points in which irregular irregularities are formed on a lower surface thereof and the lower surface is not flat.

Another object of the present invention is to provide a method of manufacturing a light emitting diode having irregular scattering points formed on the bottom surface of the semiconductor film constituting the light emitting diode, the bottom surface of which is not flat.

A feature of the present invention for achieving the above-described technical problem relates to a light emitting diode comprising a plurality of semiconductor films formed on a substrate, the light emitting diode is a plurality of scattering at the interface formed inside or between the semiconductor film Although the points are provided, the scattering points are irregularities are formed irregularly on the lower surface is characterized in that the lower surface is not flat.

The scattering point of the light emitting diode having the above characteristics is a scattering point consisting of an oxide film or a nitride film, or a space scattering point having a hollow inside.

Another aspect of the present invention relates to a method of manufacturing a light emitting diode having a scattering point of which the lower surface is not flat.

 (a) forming a first semiconductor film on the substrate and irregularly forming at least one first mask particle on the first semiconductor film,

(b) partially etching the first semiconductor film by using the first mask particles as a mask, and then removing the first mask particles to irregularly form irregularities on the surface of the first semiconductor film;

(c) depositing a first material on the first semiconductor film to form a first material film, and irregularly forming at least one or more second mask particles on the first material film,

(d) partially etching the first material film using the second mask particles as a mask, and then removing the second mask particles to form a scattering point formed of the first material;

(e) re-growing the second semiconductor film on the first semiconductor film on which the scattering point is formed, and irregularities are irregularly formed on the lower surface to have a scattering point at which the lower surface is not flat.

According to another aspect of the invention relates to a method of manufacturing a light emitting diode having a scattering point of which the lower surface is not flat,

(a) forming a first semiconductor film on the substrate and irregularly forming at least one first mask particle on the first semiconductor film,

(b) partially etching the first semiconductor film using the first mask particles as a mask, and then removing the first mask particles to irregularly form irregularities on the surface of the first semiconductor film;

(c) depositing a first material on the first semiconductor film to form a first material film, and irregularly forming at least one or more second mask particles on the first material film,

(d) partially etching the first material film using the second mask particles as a mask, and then removing the second mask particles to form scattering points formed of the first material;

(e) deeply etching the first semiconductor film using the scattering points as a mask,

(f) removing the scattering point,

(g) re-growing the second semiconductor film over the entire surface of the first semiconductor film from which the scattering point is removed, so that the second semiconductor film is not regrown in the deeply etched region of the first semiconductor film, and the uneven portion It is irregularly formed and has a spatial scattering point that is hollow inside without having a flat bottom surface.

According to still another aspect of the present invention, there is provided a method of manufacturing a light emitting diode having an uneven scattering point.

(a) forming a first semiconductor film on the substrate and irregularly forming at least one first mask particle on the first semiconductor film,

(b) partially etching the first semiconductor film using the first mask particles as a mask, and then removing the first mask particles to irregularly form irregularities on the surface of the first semiconductor film,

(c) depositing a first material on the first semiconductor film to form a first material film, and irregularly forming at least one or more second mask particles on the first material film,

(d) etching the first material layer using the second mask particles as a mask to form a scattering point formed of the first material;

(e) regrowing a second semiconductor film on the first semiconductor film to expose the scattering point,

(f) removing the scattering point by etching and regrowing the third semiconductor film on the second semiconductor film to have a hollow space scattering point without the bottom surface being flat.

According to still another aspect of the present invention, there is provided a method of manufacturing a light emitting diode having an uneven scattering point.

(a) forming a first semiconductor film on the substrate and irregularly forming at least one first mask particle on the first semiconductor film,

(b) partially etching the first semiconductor film using the first mask particles as a mask and removing the first mask particles to irregularly form irregularities on the surface of the first semiconductor film,

(c) depositing a first material on the first semiconductor film to form a first material film, and irregularly forming at least one or more second mask particles on the first material film,

(d) partially etching the first material film using the second mask particles as a mask to form a first scattering point made of a first material,

(e) deeply etching the first semiconductor film using the first scattering point as a mask;

(f) re-growing the second semiconductor film over the entire surface of the first semiconductor film to form a spatial scattering point, wherein the lower surface is hollow and the hollow space scattering point and the lower surface are not flat. It has a first scattering point made of the first material.

The light emitting diodes according to the present invention having the above-mentioned features have scattering points of which the lower surface is not flat in the semiconductor film or at the interface between the semiconductor films, thereby increasing the luminous efficiency.

First embodiment

Hereinafter, a method of manufacturing a light emitting diode having scattering points in which a lower surface thereof is not flat according to a first embodiment of the present invention will be described in detail with reference to the accompanying drawings. Scattering points according to the present invention is characterized in that the irregular surface is formed on the lower surface is not flat bottom surface. 2 is a cross-sectional view illustrating exemplary scattering points according to the present invention.

Hereinafter, a method of manufacturing a light emitting diode having oxide film scattering points according to a first exemplary embodiment of the present invention will be described in detail with reference to FIGS. 3 to 5. 3 are cross-sectional views sequentially illustrating a method of manufacturing a light emitting diode having oxide film scattering points according to the present embodiment. In this embodiment, a light emitting diode having an oxide film scattering point having an uneven portion formed on a lower surface thereof without a photolithography process (photolithography process) is manufactured.

Referring to FIG. 3A, first, a semiconductor film 310 is grown by a predetermined thickness on a single crystal semiconductor film growth substrate 300.

Next, as shown in FIG. 3B, a predetermined metal thin film is deposited on the grown semiconductor film 310 and then heat-treated under a predetermined condition, thereby melting the metal thin film and surface the molten metal particles. As a result of tension, the adjacent metal particles are locally agglomerated with each other, so that fine metal particles are irregularly formed on the semiconductor film 310. Such agglomerates of metal particles are used as the mask particles 320.

In this case, a material used as the metal thin film for forming the mask particles may be Sn, In, Zn, Cu, Ag, Au, and the like. Temperature and time of the heat treatment for the metal thin film is determined according to the type of metal, in the case of gold (Au) it is preferable to heat treatment for about 1 minute at about 700 ° ~ 900 ° Celsius. The melting point of Au is around 1064 degrees Celsius, but thin films actually form agglomerates of metal particles at temperatures around 700 ° to 900 °.

Therefore, the size and density of the mask particles are determined by the type, thickness, composition of the deposition mixture, conditions of heat treatment and post-treatment, etc. of the metal thin film deposited on the semiconductor film.

Meanwhile, in another embodiment of the mask particle forming process according to a preferred embodiment of the present invention, a pattern having a size of several μm may be formed of a photosensitive film using a photolithography process, and the pattern may be used as an etching mask. However, the present embodiment requires a more expensive and expensive exposure equipment to obtain a particle mask having a fine size (at least several μm or less), and as a result, the overall manufacturing cost can be increased.

Next, as shown in (c) of FIG. 3, by dry etching the semiconductor film 310 using mask particles of irregularly formed metal material formed on the semiconductor film as a mask, irregular irregularities are formed on the surface of the semiconductor film. As a result, the surface of the semiconductor film becomes uneven. After the irregularities are irregularly formed, the mask particles remaining on the semiconductor film are removed using an acid or a base solution. FIG. 4 is an SEM image of the semiconductor film 310 having an uneven surface due to irregular irregularities according to the present exemplary embodiment, in which convex irregularities are formed irregularly as a whole.

Next, as shown in (d) of FIG. 3, the oxide film 330 is deposited to a predetermined thickness on the semiconductor film 310 whose surface is not flat, and a metal thin film is deposited on the oxide film 330, followed by heat treatment. Mask particles 340 made of a material are formed again.

Next, as shown in (e) of FIG. 3, after partially etching the oxide film 330 using the irregularly formed mask particles 340 as a mask, the mask as shown in (f) of FIG. 3. By removing the particles 340, oxide scattering points 332 are irregularly formed on the semiconductor film 310.

Next, as shown in FIG. 3G, the semiconductor film 350 is entirely grown on the semiconductor film on which the scattering point is formed. As a result, an uneven portion is formed on the lower surface, so that oxide film scattering points having an uneven lower surface can be formed in the semiconductor film or at the interface.

FIG. 5 illustrates scattering points formed on an uneven semiconductor film due to irregularities formed on a surface of the semiconductor film in which irregularities are irregularly formed, that is, irregularities formed on a lower surface of the semiconductor film. SEM photograph showing the points by way of example.

Meanwhile, the scattering points according to the present exemplary embodiment are formed by depositing an oxide film and partially etching the oxide film using metal mask particles. Alternatively, the scattering points may be formed using a nitride film instead of the oxide film.

Second embodiment

Hereinafter, a method of manufacturing an LED according to a second exemplary embodiment of the present invention will be described with reference to FIG. 6. A second embodiment of the present invention relates to a method of manufacturing an LED, which is formed of a semiconductor film having space scattering points of which the bottom surface is not flat. On the other hand, description overlapping with the description in the above-described first embodiment will be omitted.

The second embodiment is identical to the process of FIG. 3 (f) in the manufacturing process of the first embodiment. 6A illustrates a semiconductor film 610 having an uneven surface formed on a single crystal semiconductor substrate 600 by the same process as the fabrication process in the first embodiment, and a scattering point formed of an oxide film or a nitride film thereon. 632 are formed. In this case, the deeper the etching depth with respect to the width to be etched, the easier it is to form a spatial scattering point, it is preferable that the semiconductor film 610 is formed thicker, the semiconductor film 610 according to the present embodiment by a predetermined thickness It is preferable to form thick (for example, about 2 micrometers).

Next, as shown in FIG. 6B, the semiconductor film 610 is deeply etched using scattering points 632 formed of an oxide film or the like as a mask. At this time, the dry etching process for the semiconductor film is uniformly partially etched on the entire surface of the semiconductor film, so that the uneven portions originally formed on the surface of the semiconductor film appear on the lower etching surface.

Next, as shown in FIG. 6C, scattering points 632 formed of an oxide film or a nitride film used as a mask are removed, and the semiconductor film 640 is regrown thereon. As a result, the uneven upper surface of the deeply etched semiconductor film is grown in the horizontal and / or vertical direction and bonded to each other so that the semiconductor film is not regrown in the deeply etched portion and consequently the spatial scattering points 650 Is formed.

The spatial scattering points according to the present exemplary embodiment have a lower surface having an irregular concave-convex shape and the lower surface is not flat, and the upper surface has an irregular angle.

Third embodiment

Hereinafter, an LED manufacturing process according to a third exemplary embodiment of the present invention will be described with reference to FIG. 7. The third embodiment relates to a LED manufacturing process having a spatial scattering point consisting of an uneven portion of which the lower surface is not flat, and the LED manufacturing process according to the third embodiment will be sequentially described with reference to FIG. 7. Description overlapping with the description of the above embodiments will be omitted.

As shown in FIG. 7A, a non-flat semiconductor film 710 is formed on the single crystal semiconductor substrate 700, and a scattering point 720 formed of an oxide film or a nitride film is formed on the semiconductor film 710. Are formed.

Next, as shown in FIG. 7B, the semiconductor film 730 is regrown on the semiconductor film 710 on which the scattering points 720 having uneven surfaces are formed. In this case, the regrown semiconductor film 730 may be regrown to expose the surfaces of the scattering points 720.

Next, as shown in FIG. 7C, after scattering the semiconductor film 730, the scattering points 720 formed of an oxide film or a nitride film are etched.

Next, as shown in FIG. 7D, the scattering points 720 are etched by the previous process, so that the positions where the scattering points are disposed are partially etched on the semiconductor film 730 which is partially deeply etched like a trench. The film 745 is regrown again. As a result, the space scattering points 750 are formed in the deeply etched trench by not regrowing the semiconductor film.

Fourth embodiment

Hereinafter, an LED manufacturing method according to a fourth exemplary embodiment of the present invention will be described sequentially with reference to FIG. 8. Description overlapping with the description of the above-described first embodiment will be omitted. The fourth embodiment relates to an LED manufacturing process for providing a semiconductor film having both an oxide film scattering point with an uneven bottom surface and a space scattering point with an uneven bottom surface.

The fourth embodiment is the same as the process of FIG. 3 (f) in the manufacturing process of the first embodiment. As shown in Fig. 8A, a semiconductor film 810 having an uneven surface is formed on the single crystal semiconductor substrate 800 by the same process as the fabrication process in the first embodiment, and an oxide film or Scattering points 832 formed of a nitride film are formed. In this case, the deeper the etching depth with respect to the width to be etched, the easier it is to form a spatial scattering point, it is preferable that the semiconductor film 810 is formed thick, the semiconductor film 810 according to the present embodiment is a predetermined thickness It is preferable to form thick (for example, about 2 micrometers).

Next, as shown in FIG. 8B, the semiconductor film 810 is deeply etched using scattering points 832 made of an oxide film or the like as a mask. At this time, in the dry etching process for the semiconductor film is uniformly etched on the entire surface of the semiconductor film, irregular irregularities that were originally formed on the surface of the semiconductor film appear on the lower etching surface as it is.

Next, as shown in FIG. 8C, the semiconductor film 830 is regrown on the semiconductor film 810 without removing the oxide film scattering points 832 used as a mask. As a result, the semiconductor film is not regrown in some regions of the deeply etched semiconductor film, thereby forming the space scattering points 840.

According to the present embodiment, an oxide film scattering point 832 having an uneven lower surface and a space scattering point 840 having an uneven lower surface are formed in a semiconductor film.

Although the present invention has been described above with reference to preferred embodiments thereof, this is merely an example and is not intended to limit the present invention, and those skilled in the art do not depart from the essential characteristics of the present invention. It will be appreciated that various modifications and applications which are not illustrated above in the scope are possible. For example, in the exemplary embodiment of the present invention, the constituent material of the scattering point, the method of forming the uneven portion on the semiconductor film, and the like may be variously modified to improve the efficiency of the manufacturing process. And differences relating to such modifications and applications should be construed as being included in the scope of the invention defined in the appended claims.

According to the present invention, irregularities are irregularly formed in the lower surface of the light emitting diode, so that the lower surface has an uneven scattering point, so that scattering of light is improved by the inclination of the upper portion of the scattering point, The light that is later reflected back by the uneven portions of the lower surface and directed upward is scattered by the uneven lower surface of the scattering point.

As a result, compared with conventional scattering points having a flat bottom surface, which are totally internally absorbed, the light emitting diode according to the present invention prevents absorption of light by total internal reflection, thereby increasing external emission efficiency, and consequently scattering light. By increasing the effect, it is possible to improve the luminous performance and to improve the luminance performance.

Claims (9)

In a light emitting diode comprising a plurality of semiconductor films formed on a substrate, The irregularities are irregularly formed on the lower surface of the semiconductor film or at the interface formed between the semiconductor films, so that the lower surface has a plurality of scattering points that are not flat, and the scattering points are scattering points formed of an oxide film or a nitride film, A light emitting diode with improved light emission performance, characterized in that the hollow interior space scattering points. delete (a) forming a first semiconductor film on the substrate and irregularly forming a plurality of first mask particles on an upper surface of the first semiconductor film; (b) partially etching the first semiconductor film by using the first mask particles as a mask, and then removing the first mask particles to irregularly form irregularities on the surface of the first semiconductor film; (c) depositing a first material on the first semiconductor film to form a first material film, and irregularly forming a plurality of second mask particles on the first material film; (d) partially etching the first material film using the second mask particles as a mask, and then removing the second mask particles to form a scattering point formed of the first material; (e) regrowing a second semiconductor film on the first semiconductor film on which the scattering point is formed; The method of manufacturing a light emitting diode having a scattering point having irregularities on the lower surface thereof, the lower surface of which is not flat.  (a) forming a first semiconductor film on the substrate and irregularly forming a plurality of first mask particles on an upper surface of the first semiconductor film; (b) partially etching the first semiconductor film using the first mask particles as a mask, and then removing the first mask particles to irregularly form irregularities on the surface of the first semiconductor film; (c) depositing a first material on the first semiconductor film to form a first material film, and irregularly forming a plurality of second mask particles on the first material film; (d) partially etching the first material film using the second mask particles as a mask, and then removing the second mask particles to form scattering points formed of the first material; (e) deeply etching the first semiconductor layer using the scattering points as a mask; (f) removing the scattering point; (g) regrowing the second semiconductor film on the entire surface of the first semiconductor film from which the scattering point is removed; The light emitting diode having a space scattering point having a hollow inside without having a bottom surface is irregular because the second semiconductor film is not regrown in the deeply etched region of the first semiconductor film. Method of preparation. (a) forming a first semiconductor film on the substrate and irregularly forming a plurality of first mask particles on an upper surface of the first semiconductor film; (b) partially etching the first semiconductor film by using the first mask particles as a mask, and then removing the first mask particles to irregularly form irregularities on the surface of the first semiconductor film; (c) depositing a first material on the first semiconductor film to form a first material film, and irregularly forming a plurality of second mask particles on the first material film; (d) etching the first material layer using the second mask particles as a mask to form a scattering point formed of a first material; (e) regrowing a second semiconductor film over the first semiconductor film to expose the scattering point; (f) etching and removing the scattering point, and then regrowing a third semiconductor film on the second semiconductor film; The method of manufacturing a light emitting diode having a space scattering point of which the inside is hollow while the bottom surface is not flat. (a) forming a first semiconductor film on the substrate and irregularly forming a plurality of first mask particles on the first semiconductor film; (b) partially etching the first semiconductor film using the first mask particles as a mask and removing the first mask particles to irregularly form irregularities on the surface of the first semiconductor film; (c) depositing a first material on the first semiconductor film to form a first material film, and irregularly forming a plurality of second mask particles on the first material film; (d) partially etching the first material film using the second mask particles as a mask to form a first scattering point made of a first material; (e) deeply etching the first semiconductor layer using the first scattering point as a mask; (f) regrowing the second semiconductor film over the entire surface of the first semiconductor film to form a space scattering point The manufacturing method of the light emitting diode which has a space scattering point which is hollow inside and whose lower surface is not planar, and a 1st scattering point which consists of a 1st material whose lower surface is not flat. The method of manufacturing a light emitting diode according to any one of claims 3 to 6, wherein the first semiconductor film and the second semiconductor film are made of the same material. The method of manufacturing a light emitting diode according to any one of claims 3 to 6, wherein the first material film is an oxide film or a nitride film. The method of claim 3, wherein the forming of the first or second mask particles comprises first depositing a predetermined metal material to form a metal thin film, and then heat-treating the fine metal particles. A method of manufacturing a light emitting diode, characterized in that to form a mask particle to be formed.

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