Light-emitting device structure and semiconductor wafer structure with the same

(A) Field of the Invention

The present invention relates to a light-emitting device structure and semiconductor wafer structure with the same, and more particularly, to a light-emitting device structure having a wall structure around the light-emitting device to increase the light-extraction efficiency and semiconductor wafer structure with the same.

(B) Description of the Related Art

Semiconductor light-emitting devices such as light-emitting diodes (LED) have been widely used in traffic lights, vehicle electronics, LCD backing lights, and general illumination. In the light-emitting diode an n-type semiconductor layer, a light-emitting region and a p-type semiconductor layer are essentially made to grow on a substrate to form a layered structure, and the electrodes are formed on the p-type semiconductor layer and on the n-type semiconductor layer. Light is generated through the recombination of holes and electrons that have been injected through the semiconductor layers to the light-emitting region, and then emitted through a light transmitting electrode on the p-type semiconductor layer or from the substrate. The material used for preparing the visible light-emitting diode includes the III-V compound such as AlGaInP for green, yellow, orange or red light-emitting diodes, and GaN for blue or ultraviolet light-emitting diodes, wherein the GaN light-emitting diode is formed on the sapphire substrate.

Extracting the light beams generated by the light-emitting layer to the outside of the light-emitting device is one important issue to be improved in the semiconductor light-emitting device. Researchers use the transparent electrode in the conventional light-emitting device to prevent the upward light beams generated by the light-emitting layer from being blocked on the propagation path to the outside of the light-emitting device, or use the reflection layer to reflect the downward light beams generated by the light-emitting layer back to the top of the light-emitting device. However, in addition to the upward light beams and downward light beams, the light-emitting layer also emits light beams in other directions, and a portion of the light beams are reflected internally into the light-emitting device due to the total reflection effect. Consequently, the light beams may be adsorbed by the light-emitting layer, rather than propagate to the outside of the light-emitting device.

TW 561632 discloses a semiconductor light-emitting device having at least one recess and/or protruding portion created for scattering or diffracting light generated in a light-emitting region on the surface portion of a substrate. The recess and/or protruding portion includes a shape that prevents crystal defects from occurring in semiconductor layers.

In addition, TW 536841 discloses a semiconductor light-emitting element having an undulation formed on the surface of a first layer (substrate), and a second layer having a refractive index different from that of the first layer grown to fill the undulation. Furthermore, a first crystal may be grown in an undulated shape on a crystal layer, which is the foundation of crystal growth. After such undulated refractive interface is formed, a semiconductor crystal layer having a refractive index different from that of the first layer is laminated thereon.

One aspect of the present invention provides a light-emitting device structure having a wall structure around the light-emitting device to increase the light-extraction efficiency and semiconductor wafer structure with the same.

A light-emitting device structure according to this aspect of the present invention comprises a substrate having a first region and a second region outside the first region, a first conductive type semiconductor layer positioned on the first region, a light-emitting structure positioned on the first conductive type semiconductor layer, a second conductive type semiconductor layer positioned on the light-emitting structure, and a wall structure positioned on the second region.

Another aspect of the present invention provides a semiconductor wafer structure comprising a substrate, a plurality of light-emitting devices positioned on the substrate, at least one scribe line separating the light-emitting devices, and a wall structure positioned on the scribe line. The light-emitting device includes a first conductive type semiconductor layer, a light-emitting structure positioned on the first conductive type semiconductor layer, and a second conductive type semiconductor layer positioned on the light-emitting structure.

The foregoing includes outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter, which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures or processes for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.

The objectives and advantages of the present invention will become apparent upon reading the following description and upon reference to the accompanying drawings in which:

FIG. 1 illustrates a semiconductor wafer structure according to one embodiment of the present invention;

FIG. 2 is a cross-sectional view along a cross-sectional line 1 - 1 of FIG. 1 ;

FIG. 3 illustrates a semiconductor wafer structure according to another embodiment of the present invention;

FIG. 4 is a cross-sectional view along a cross-sectional line 2 - 2 of FIG. 3 ;

FIG. 5 illustrates a semiconductor wafer structure according to another embodiment of the present invention; and

FIG. 6 is a cross-sectional view along a cross-sectional line 3 - 3 of FIG. 5 .

FIG. 1 and FIG. 2 illustrate a semiconductor wafer structure 10 A according to one embodiment of the present invention, wherein FIG. 2 is a cross-sectional view along a cross-sectional line 1 - 1 in FIG. 1 . The semiconductor wafer structure 10 A comprises a substrate 12 A, a plurality of light-emitting devices 20 A positioned on the substrate 12 A, a plurality of scribe lines 40 A separating the light-emitting devices 20 A, and a plurality of wall structures 50 A positioned on the scribe lines 40 A. In one embodiment of the present invention, the substrate 12 A includes a first region 14 A and a second region 16 A outside the first region 14 A, the light-emitting device is positioned in the first region 14 A, and the scribe line 40 A is positioned in the second region 16 A. For example, the second region 16 A surrounds the first region 14 A, i.e., the wall structure 50 A surrounds the light-emitting device 10 A. The sidewall surface of the wall structure 50 A can be wavy or arc-shaped, and the lateral thickness of the wall structure 50 A varies non-periodically.

Referring to FIG. 2 , the light-emitting device 10 A includes an n-type semiconductor layer 22 A, a light-emitting structure 24 A positioned on the n-type semiconductor layer 22 A, a p-type semiconductor layer 26 A positioned on the light-emitting structure 24 A, a contact layer 28 A positioned on the p-type semiconductor layer 26 A, a transparent conductive layer 30 A positioned on the contact layer 28 A, a first electrode 32 A positioned on the n-type semiconductor layer 22 A, and a second electrode 34 A positioned on the transparent conductive layer 30 A. In one embodiment of the present invention, the p-type semiconductor layer 26 A includes a top end and a bottom end, and the wall structure 50 A includes a top end between the top end and the bottom end of the p-type semiconductor layer 26 A.

In the conventional light-emitting device, a portion of emitted light beams is reflected internally in the light-emitting device due to the total reflection effect, and consequently the reflected light beams are adsorbed by the light-emitting layer itself, rather than propagate to the outside of the light-emitting device. To solve this problem and to increase the light-extraction efficiency, one embodiment of the present invention introduces the wall structure 50 A surrounding the light-emitting device 20 A to change the incident angle of the light beams propagating from the light-emitting device (high reflection index material) 20 A to the air (low reflection index material) so as to avoid the total reflection effect, i.e., preventing the light beams from being adsorbed by the light-emitting structure itself by avoiding the occurrence of the repeated total reflection in the light-emitting device 20 A. Consequently, the light-extraction efficiency of the light-emitting device 20 A can be increased dramatically.

The layers on the substrate 12 A can be prepared by the epitaxy machine, the lithographic process can be used to pattern the shape (such as wavy or arc-shaped) of the wall structure 50 A on the scribe line 40 A, and the dry etching can be used to etch the layers down to a predetermined depth to prepare the wall structure 50 A. In one embodiment of the present invention, the substrate 12 A includes transparent insulation material such as sapphire; the n-type semiconductor layer 22 A, the light-emitting structure 24 A and the p-type semiconductor layer 26 A include nitride material such as aluminum-gallium-nitride (AlGaN), gallium nitride (GaN), indium-gallium nitride (InGaN), or aluminum-gallium-indium nitride (AlGaInN); the contact layer 28 A includes nitride material such as aluminum-gallium-nitride (AlGaN), gallium nitride (GaN), indium-gallium nitride (InGaN), or aluminum-gallium-indium nitride (AlGaInN); the transparent conductive layer 30 A includes indium oxide, tin oxide or indium tin oxide; and the light-emitting structure 24 A may use the quantum well or multi-quantum well structure.

FIG. 3 and FIG. 4 illustrate a semiconductor wafer structure 10 B according to another embodiment of the present invention, wherein FIG. 4 is a cross-sectional view along a cross-sectional line 2 - 2 in FIG. 3 . The semiconductor wafer structure 10 B comprises a substrate 12 B, a plurality of light-emitting devices 20 B positioned on the substrate 12 B, a plurality of scribe lines 40 B separating the light-emitting devices 20 B, and a plurality of wall structures 50 B positioned on the scribe lines 40 B. In one embodiment of the present invention, the substrate 12 B includes a first region 14 B and a second region 16 B outside the first region 14 B, the light-emitting device is positioned in the first region 14 B, and the scribe line 40 B is positioned in the second region 16 B. For example, the second region 16 B surrounds the first region 14 B, i.e., the wall structure 50 B surrounds the light-emitting device 10 B. The sidewall surface of the wall structure 50 B can be scraggy or zigzag, and the lateral thickness of the wall structure 50 B varies periodically.

Referring to FIG. 4 , the light-emitting device 10 B includes an n-type semiconductor layer 22 B, a light-emitting structure 24 B positioned on the n-type semiconductor layer 22 B, a p-type semiconductor layer 26 B positioned on the light-emitting structure 24 B, a contact layer 28 B positioned on the p-type semiconductor layer 26 B, a transparent conductive layer 30 B positioned on the contact layer 28 B, a first electrode 32 B positioned on the n-type semiconductor layer 22 B, and a second electrode 34 B positioned on the transparent conductive layer 30 B. In one embodiment of the present invention, the light-emitting structure 24 B includes a top end and a bottom end, and the wall structure 50 B includes a top end between the top end and the bottom end of the light-emitting structure 24 B.

In the conventional light-emitting device, a portion of emitted light beams is reflected internally in the light-emitting device due to the total reflection effect, and consequently the reflected light beams are adsorbed by the light-emitting layer itself, rather than propagate to the outside of the light-emitting device. To solve this problem and to increase the light-extraction efficiency, one embodiment of the present invention introduces the wall structure 50 B surrounding the light-emitting device 20 B to change the incident angle of the light beams propagating from the light-emitting device (high reflection index material) 20 B to the air (low reflection index material) so as to avoid the total reflection effect, i.e., preventing the light beams from being adsorbed by the light-emitting layer itself by avoiding the occurrence of the repeated total reflection in the light-emitting device 20 B. Consequently, the light-extraction efficiency of the light-emitting device 20 B is increased.

The layers on the substrate 12 B can be prepared by the epitaxy machine, the lithographic process can be used to pattern the shape (such as scraggy or zigzag) of the wall structure 50 B on the scribe line 40 B, and the dry etching can be used to etch the layers down to a predetermined depth to prepare the wall structure 50 B. In one embodiment of the present invention, the substrate 12 B includes transparent insulation material such as sapphire; the n-type semiconductor layer 22 B, the light-emitting structure 24 B and the p-type semiconductor layer 26 B include nitride material such as aluminum-gallium-nitride (AlGaN), gallium nitride (GaN), indium-gallium nitride (InGaN), or aluminum-gallium-indium nitride (AlGaInN); the contact layer 28 B includes nitride material such as aluminum-gallium-nitride (AlGaN), gallium nitride (GaN), indium-gallium nitride (InGaN), or aluminum-gallium-indium nitride (AlGaInN); the transparent conductive layer 30 B includes indium oxide, tin oxide or indium tin oxide; and the light-emitting structure 24 B may use the quantum well or multi-quantum well structure.

FIG. 5 and FIG. 6 illustrate a semiconductor wafer structure 10 C according to another embodiment of the present invention, wherein FIG. 6 is a cross-sectional view along a cross-sectional line 3 - 3 in FIG. 5 . The semiconductor wafer structure 10 C comprises a substrate 12 C, a plurality of light-emitting devices 20 C positioned on the substrate 12 C, a plurality of scribe lines 40 C separating the light-emitting devices 20 C, and a plurality of wall structures 50 C positioned on the scribe lines 40 C.

In one embodiment of the present invention, the substrate 12 C includes a first region 14 C and a second region 16 C outside the first region 14 C, the light-emitting device is positioned in the first region 14 C, and the scribe line 40 C is positioned in the second region 16 C. For example, the second region 16 C surrounds the first region 14 C, i.e., the wall structure 50 C surrounds the light-emitting device 10 C. The wall structures 50 C are arranged in a ring-shaped manner and separated from each other, and the sidewall surface of the wall structure 50 C includes at least two concavities. In addition, the wall structures 50 C in the inner ring and the outer ring are arranged in a staggered manner.

Referring to FIG. 6 , the light-emitting device 10 C includes an n-type semiconductor layer 22 C, a light-emitting structure 24 C positioned on the n-type semiconductor layer 22 C, a p-type semiconductor layer 26 C positioned on the light-emitting structure 24 C, a contact layer 28 C positioned on the p-type semiconductor layer 26 C, a transparent conductive layer 30 C positioned on the contact layer 28 C, a first electrode 32 C positioned on the n-type semiconductor layer 22 C, and a second electrode 34 C positioned on the transparent conductive layer 30 C. In one embodiment of the present invention, the light-emitting structure 28 C includes a top end and a bottom end, and the n-type semiconductor layer 22 C includes a top end between the top end and the bottom end of the n-type semiconductor layer 22 C.

In the conventional light-emitting device, a portion of emitted light beams is reflected internally in the light-emitting device due to the total reflection effect, and consequently the reflected light beams are adsorbed by the light-emitting layer itself, rather than propagate to the outside of the light-emitting device. To solve this problem and to increase the light-extraction efficiency, one embodiment of the present invention introduces the wall structure 50 C surrounding the light-emitting device 20 C to change the incident angle of the light beams propagating from the light-emitting device (high reflection index material) 20 C to the air (low reflection index material) so as to avoid the total reflection effect, i.e., preventing the light beams from being adsorbed by the light-emitting layer itself by avoiding the occurrence of the repeated total reflection in the light-emitting device 20 C. Consequently, the light-extraction efficiency of the light-emitting device 20 C is increased.

The layers on the substrate 12 C can be prepared by the epitaxy machine, the lithographic process can be used to pattern the shape of the wall structure 50 C on the scribe line 40 C, and the dry etching can be used to etch the layers down to a predetermined depth to prepare the wall structure 50 C. In one embodiment of the present invention, the substrate 12 C includes transparent insulation material such as sapphire; the n-type semiconductor layer 22 C, the light-emitting structure 24 C and the p-type semiconductor layer 26 C include nitride material such as aluminum-gallium-nitride (AlGaN), gallium nitride (GaN), indium-gallium nitride (InGaN), or aluminum-gallium-indium nitride (AlGaInN); the contact layer 28 C includes nitride material such as aluminum-gallium-nitride (AlGaN), gallium nitride (GaN), indium-gallium nitride (InGaN), or aluminum-gallium-indium nitride (AlGaInN); the transparent conductive layer 30 C includes indium oxide, tin oxide or indium tin oxide; and the light-emitting structure 24 C may use the quantum well or multi-quantum well structure.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. For example, many of the processes discussed above can be implemented in different methodologies and replaced by other processes, or a combination thereof.

Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.