KR20050092575A - Method of fabricating gan-based iii - v group compound semiconductor light emitting device - Google Patents

Abstract

A method for producing a II-VIII compound compound semiconductor light emitting device is disclosed. The disclosed light emitting device manufacturing method includes the steps of sequentially forming an active layer, a p-type GaN layer and a p-type electrode on an n-type GaN layer, disposing an etching plate on the lower surface of the n-type GaN layer, Forming a plurality of protrusions on the lower surface of the n-type GaN layer by ion etching from above the etching plate, and forming an n-type electrode on the etched n-type GaN layer.

Description

Method for fabricating GaN-based III-V group compound semiconductor light emitting device

The present invention relates to a method of manufacturing a III-V GaN compound semiconductor light emitting device, and more particularly, to a method of forming protrusions on an emission surface of an n-GaN layer.

Like a light emitting diode (LED), a semiconductor light emitting device that converts an electrical signal into light using characteristics of a compound semiconductor has a longer lifespan than other light emitters, uses a low voltage, and consumes less power. There is an advantage. In addition, it has the advantages of excellent response speed and impact resistance as well as small size and light weight. The semiconductor light emitting device may generate light having different wavelengths according to the type and constituent material of the semiconductor to be used, and thus, light having various wavelengths may be used as needed. In particular, a high brightness semiconductor light emitting device capable of emitting very bright light has been developed due to the development of production technology and improvement of the device structure, and its use has been widened. In the past, high-brightness semiconductor light emitting devices that mainly emit green, yellow, or red light or infrared light have been developed and used. However, in the mid-1990s, high-brightness semiconductor light emitting devices emitting blue light were developed. By using it, natural full natural colors can be displayed.

1 is a cross-sectional view showing an example of a general vertical GaN LED.

Referring to FIG. 1, the light emitting device 20 is flip bonded to the substrate 10. The light emitting element 20 is formed by sequentially stacking a p-type electrode 21, a p-GaN layer 22, an active layer 23, an n-GaN layer 24, and an n-type electrode 25.

The substrate 10 is connected to the light emitting device 20 through the solder bumper 30. Silicon or carbon blocks may be used as the substrate 10. The epoxy resin 40 covers the substrate 10 and the light emitting device 20.

The refractive index of the active layer 23, for example, the active layer 23 formed of the InGaN layer, is approximately 3, and the refractive indices of the p-GaN layer 22 and the n-GaN layer 24 of the upper and lower portions of the active layer 23 are approximately 2.54. The epoxy resin 40 has a refractive index of approximately 1.5.

When a voltage equal to or higher than a threshold voltage required for light emission is applied to the p-type electrode 21 and the n-type electrode 25, light is emitted from the active layer 23. A part L1 of the light emitted from the active layer 23 is emitted toward the light emitting surface 24a of the n-type GaN layer 24, and the other part L2 is emitted toward the p-type electrode 21. When the p-type electrode 21 uses a highly reflective conductive metal such as silver (Ag), the light L2 is reflected by the p-type electrode 21 so that the light emitting surface 24a of the n-GaN layer 24 is formed. Proceeds toward).

On the other hand, the light from the n-GaN layer 24 having a high refractive index toward the epoxy layer 40 having a low refractive index passes through the epoxy layer 40 when the incident angle is within about 30 degrees, and the incident angle is 30 degrees or more. In this case, the light is totally reflected from the light emitting surface 24a and disappears in the light emitting device 20. Therefore, there is a problem that the amount of emitted light is reduced.

U. S. Patent No. 3,739, 217 discloses a surface roughening technique for roughening the surface of a substrate through which light passes to increase the emission amount of the light. However, the chemical and mechanical roughness processes disclosed in the above-mentioned US patents are difficult to achieve fine size roughness, and thus are limited in improving light emission efficiency.

It is an object of the present invention to provide a method for forming a predetermined uniform protrusion on a surface from which light of an n-GaN layer is emitted.

Method for manufacturing a semiconductor light emitting device according to one type of the present invention,

a first step of sequentially forming an active layer, a p-type GaN layer, and a p-type electrode on the n-type GaN layer;

Disposing an etching plate on a lower surface of the n-type GaN layer;

A third step of forming a plurality of protrusions on the lower surface of the n-type GaN layer by ion etching from above the etching plate; And

And forming a n-type electrode on the etched n-type GaN layer.

In the etching plate, it is preferable that an intersection line exposed in a matrix form is formed so as to expose a region other than the region corresponding to the protrusion.

The protrusions are preferably formed in a size of 0.1 nm ~ 100 nm.

Method for manufacturing a semiconductor light emitting device according to another type of the present invention,

a first step of sequentially forming an active layer, a p-type GaN layer, and a p-type electrode on the n-type GaN layer;

Disposing a deposition plate having a plurality of holes formed on a lower surface of the n-type GaN layer;

Depositing a plurality of dots on a lower surface of the n-type GaN layer from above the deposition plate; And

And forming a n-type electrode on the n-type GaN layer of the resultant of the third step.

The third step may further include forming protrusions under the dot by ion etching the upper surface of the n-type GaN layer using the dots as a mask.

The hole is preferably formed in the size of 0.1 nm ~ 100 nm.

The dot is preferably formed in a size of 0.1 nm ~ 100 nm.

In addition, the dots are preferably a metal material or an oxide.

Method for manufacturing a semiconductor light emitting device according to another type of the present invention,

a first step of sequentially forming an active layer, a p-type GaN layer, and a p-type electrode on the n-type GaN layer;

A second step of forming a plurality of protrusions by irradiating a laser beam on a lower surface of the n-type GaN layer; And

And forming a n-type electrode on the protrusions.

In the second step, the laser beam is preferably irradiated with the straight lines intersecting in a matrix form.

Hereinafter, a method for manufacturing a III-V GaN compound semiconductor according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thicknesses of layers or regions illustrated in the drawings are exaggerated for clarity.

FIG. 2 is a cross-sectional view illustrating an improvement in light extraction efficiency of a light emitting device manufactured according to the present invention. The same reference numerals are used for members substantially the same as in FIG. 1, and detailed descriptions thereof will be omitted.

Referring to FIG. 2, the surface of the n-GaN layer 24 serving as the light emitting surface 24a is partially etched to form a plurality of protrusions 24b. The protrusions 24b have a size d of 1 nm to 100 μm, preferably 0.1 μm to 1 μm.

The active layer 23, the p-GaN layer 22, and the p-type electrode 21 are sequentially formed below the surface opposite to the surface 24a on which the protrusion 24b is formed.

The protrusion 24b may be formed of a metal or an oxide layer on the n-GaN layer 24, which is a material different from that of the n-GaN layer 24.

The n-type electrode 25 is formed on the protrusions 24b.

When light emitted from the active layer 23 is incident on the light emitting surface 24a, even if the incident angle is larger than a predetermined angle, for example, 30 °, the angle of incidence on the light reflection surface at the projection 24b is smaller than 30 °. Light is easily emitted to the epoxy resin layer (40 in FIG. 1). Thus, the light emitting effect on the light emitting surface 24a in which the protrusions 24b are formed uniformly increases.

In the above embodiment, the light emitting device was shown to be covered with an epoxy resin, but is not necessarily limited thereto. That is, the light emitting effect is generated even in an air state in which a fluorescent layer is formed instead of an epoxy resin or in which such a protective layer is not formed.

3 is a cross-sectional view illustrating a method of forming the protrusion according to the first embodiment of the present invention.

Referring to FIG. 3, the active layer 23 and the p-type GaN layer 22 are sequentially formed on the n-type GaN layer 24. The p-type electrode 21 is formed on the p-type GaN layer 22 by electron beam deposition or thermal deposition.

Subsequently, the exposed bottom of the resultant surface, that is, the n-type GaN layer 24 is faced up, and an etch template 50 is placed on the exposed face 24a. The etching template 50 is formed with lines crossing the regions other than the regions corresponding to the protrusions described later in a matrix shape. The projections described later are formed in the region corresponding to the region between these intersection lines.

Next, the region 50a exposed by the etching template 50 is ion-etched from above the exposed surface 24a. In this case, when argon ions (Ar ⁺ ) are etched using a reactive ion etcher, an area corresponding to the exposed area 50a of the etching template 50 is etched on the surface of the n-type GaN layer 24. Then, the protrusions 24b corresponding to the unexposed region 50b are formed.

The protrusions 24b are disposed at predetermined intervals from each other in a size of 1 nm to 100 μm. More preferably, the protrusions 24b are formed to have a size of 0.1 μm to 1 μm.

Subsequently, an n-type electrode 25 of FIG. 2 is formed on the protrusions 24b. The light emitting device (20 of FIG. 2) manufactured as described above is flip-bonded on the substrate 10, and the epoxy resin 40 is formed on the surface thereof, thereby completing the light emitting device of FIG. 1.

4 is a cross-sectional view illustrating a method of forming the protrusion according to the second embodiment of the present invention.

Referring to FIG. 4, the active layer 23 and the p-type GaN layer 22 are sequentially formed on the n-type GaN layer 24. The p-type electrode 21 is formed on the p-type GaN layer 22 by electron beam deposition or thermal deposition.

Subsequently, the bottom surface of the resultant, i.e., the exposed side of the n-type GaN layer 24 is faced up, and a deposition template 60 is placed on the exposed side 24a. Holes 60a having a size of 1 nm to 100 μm are disposed in the deposition template 60 at predetermined intervals. More preferably, the holes 60a are formed to have a size of 0.1 μm to 1 μm. These holes 60a are preferably arranged at equal intervals from each other.

Subsequently, a metal or oxide is deposited on the area exposed by the deposition template 60 from above the exposed surface 24a to form dots 60b similar to the size of the hole 60a of the deposition template 60. Create

These dots 60b prevent the light from the active layer 23 from totally reflecting inside, like the protrusions in the first embodiment, and consequently improve the luminous efficiency.

FIG. 5 is an explanatory diagram showing a third embodiment of performing ion etching using the dots of FIG. 4.

Referring to FIG. 5, in the result of FIG. 4, the region 60c exposed by the dots 60b is etched from above the exposed surface 24a in a state where the deposition template 60 is removed. In this case, when argon ions (Ar ⁺ ) are etched using a reactive ion etcher, an area between the dots 60b is etched on the surface of the n-type GaN layer 24, and the lower portion of the dots 60b is etched. The projections 60d similar to the size of the dot 60b are generated in the. In the ion etching process, the dots 60b may be evaporated.

Subsequently, an n-type electrode 25 is formed on the n-type GaN layer 24 on which the protrusions 60d are formed. When the light emitting device 20 manufactured as described above is flip-bonded on the substrate 10 and the epoxy resin 40 is formed on the surface of the light emitting device 20, the light emitting device shown in FIG. 1 is completed.

6 is a cross-sectional view illustrating a method of forming the protrusions according to the fourth embodiment of the present invention.

Referring to FIG. 6, the active layer 23 and the p-type GaN layer 22 are sequentially formed on the n-type GaN layer 24. The p-type electrode 21 is formed on the p-type GaN layer 22 by electron beam deposition or thermal deposition.

Subsequently, the bottom surface of the resultant, that is, the exposed surface of the n-type GaN layer 24 is turned upward and the laser beam is irradiated from above the exposed surface 24a. When the laser beam is irradiated in a lattice shape, an area to which the laser beam is irradiated is concave, and thus an area not irradiated with the laser beam protrudes to form the protrusion 70a. The size of the protrusion 70a is determined by the line spacing d2 of the laser beam, and is preferably irradiated at an interval of 1 nm to 100 μm in size (diameter). The line spacing is more preferably irradiated with a size of 0.1 ㎛ ~ 1 ㎛.

Subsequently, an n-type electrode 25 is formed on the protrusions 70a. When the light emitting device 20 manufactured as described above is flip-bonded on the substrate 10 and the epoxy resin 40 is formed on the surface of the light emitting device 20, the light emitting device shown in FIG. 1 is completed.

The protrusions or dots formed by the embodiments of the present invention improve the efficiency with which light from the active layer is extracted to the outside. The size of the projections according to the embodiment of the present invention can be adjusted to the line width of the template or the size of the hole, it can also be constantly adjusted to the line width of the laser beam.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be defined only in the appended claims.

1 is a cross-sectional view showing an example of a general vertical GaN LED.

2 is a cross-sectional view illustrating that the light extraction efficiency of the light emitting device manufactured according to the present invention is improved.

3 is a cross-sectional view illustrating a method of forming the protrusion according to the first embodiment of the present invention.

4 is a cross-sectional view illustrating a method of forming the protrusion according to the second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a third embodiment of performing ion etching using the dots of FIG. 4.

6 is a cross-sectional view illustrating a method of forming the protrusions according to the fourth embodiment of the present invention.

* Description of Signs of Major Parts of Drawings *

10: substrate 20: light emitting element

21: p-type substrate 22: p-type GaN layer

23: active layer 24: n-type GaN layer

24a: light emitting surface 25: n-type electrode

30: solder bump 40: epoxy resin (layer)

50: etching template 24b, 60d: projection

60: deposition template 60a: hole

60b: dots

Claims (11)

a first step of sequentially forming an active layer, a p-type GaN layer, and a p-type electrode on the n-type GaN layer; Disposing an etching plate on a lower surface of the n-type GaN layer; A third step of forming a plurality of protrusions on the lower surface of the n-type GaN layer by ion etching from above the etching plate; And And a fourth step of forming an n-type electrode on the etched n-type GaN layer. The method of claim 1, The etching plate is a manufacturing method of the semiconductor light emitting device, characterized in that the intersection line exposed in the matrix form to expose the region other than the region corresponding to the projection. The method of claim 1, The protrusion is a method of manufacturing a semiconductor light emitting device, characterized in that formed in the size of 0.1 nm ~ 100 nm. a first step of sequentially forming an active layer, a p-type GaN layer, and a p-type electrode on the n-type GaN layer; Disposing a deposition plate having a plurality of holes formed on a lower surface of the n-type GaN layer; Depositing a plurality of dots on a lower surface of the n-type GaN layer from above the deposition plate; And And forming a n-type electrode on the n-type GaN layer of the resultant of the third step. The method of claim 4, wherein The third step may further include forming protrusions on the lower portion of the dot by ion etching from above the lower surface of the n-type GaN layer using the dots as a mask. Way. The method according to claim 4 or 5, The hole is a method of manufacturing a semiconductor light emitting device, characterized in that formed in the size of 0.1 nm ~ 100 nm. The method according to claim 4 or 5, The dot is a method of manufacturing a semiconductor light emitting device, characterized in that formed in the size of 0.1 nm ~ 100 nm. The method of claim 4, wherein The dot is a manufacturing method of a semiconductor light emitting device, characterized in that the metal material or oxide. a first step of sequentially forming an active layer, a p-type GaN layer, and a p-type electrode on the n-type GaN layer; A second step of forming a plurality of protrusions by irradiating a laser beam on a lower surface of the n-type GaN layer; And And a third step of forming an n-type electrode on the protrusions. The method of claim 9, The second step is a method of manufacturing a semiconductor light emitting device, characterized in that for irradiating the laser beam in a matrix form in a straight line cross. The method of claim 9, The protrusion is a method of manufacturing a semiconductor light emitting device, characterized in that formed in the size of 0.1 nm ~ 100 nm.