TWI449219B - Light emitting diode device, and method for fabricating the same - Google Patents

Description

Light-emitting diode device and method of manufacturing same

The present invention relates to a light emitting diode device and a method of fabricating the same, and more particularly to a light emitting diode device having a vertical electrode structure and a method of fabricating the same.

Light Emitting Diode (LED) is widely used in various display products because of its high brightness, small size, light weight, low damage, low power consumption and long life. The principle is as follows: Apply a voltage to the diode to drive the electrons in the diode to combine with the hole, and the energy generated by the combination is released in the form of light.

Fig. 1 is a schematic cross-sectional view showing a conventional light-emitting diode 10 having a sapphire substrate. The light emitting diode 10 includes a sapphire substrate 12, a buffer layer 13, a semiconductor device layer 15, a first electrode 20, and a second electrode 22. The semiconductor device layer 15 includes an N-type semiconductor layer 14, a light-emitting layer 16, and a P-type semiconductor layer 18. The light-emitting diode 10 is formed by sequentially forming the buffer layer 13, the N-type semiconductor layer 14, the light-emitting layer 16, and the P-type semiconductor layer 18 on the sapphire substrate 12, and then etching a groove on one side thereof to expose A part of the N-type semiconductor layer 14 is finally plated with a metal layer and then etched by a photomask to form the first electrode 20 and the second electrode 22 in the N-type semiconductor layer 14 and the P-type semiconductor layer 18, respectively. The first electrode 20 and the second electrode 22 are all on the same side (the opposite side of the substrate). The reason for this arrangement is that the sapphire substrate is not electrically conductive, and the electrodes cannot be fabricated on the reverse side of the wafer. In this way, in addition to the need to sacrifice part of the light-emitting area to form the contact electrode of the N-type semiconductor layer 14 so that the effective light-emitting area of the light-emitting diode 10 is reduced, such a structure also causes current to concentrate between the two electrodes 20, 22. The shortest path 25 is not uniformly distributed to the entire light emitting diode 10, so that the overall luminous efficiency of the light emitting diode 10 is poor and the light emission is uneven.

In order to solve the above problems, a conventional technique for forming a vertical electrode is to first form a desired epitaxial layer on a sapphire substrate, and then further to emit a light-emitting diode by using a laser lift-off process. The sapphire substrate of the bulk wafer is removed and replaced with a heat-dissipating substrate such as a germanium substrate. However, the manufacturing yield of the above method is not high, and the manufacturing cost is greatly increased.

Based on the above, there is an urgent need in the industry for an innovative light emitting diode device to solve the above problems.

The present invention provides a light emitting diode device comprising an insulating substrate having an upper surface and a lower surface; a patterned conductive layer disposed on a portion of the upper surface of the insulating substrate; a buffer layer disposed on the insulating substrate An upper surface covered by the patterned conductive layer; a first semiconductor layer disposed on the buffer layer; a light emitting layer disposed on the first semiconductor layer; and a second semiconductor layer disposed on the light emitting layer Above the layer; and an electrode disposed on the second semiconductor layer.

In addition, the present invention also provides a method for fabricating a light emitting diode device, comprising: providing an insulating substrate having an upper surface and a lower surface; forming a patterned conductive layer on a portion of the upper surface of the insulating substrate; forming a buffer layer on the upper surface of the insulating substrate not covered by the patterned conductive layer; forming a first semiconductor layer over the buffer layer; forming a light emitting layer over the first semiconductor layer; forming a second a semiconductor layer over the light emitting layer; and an electrode formed over the second semiconductor layer.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

In order to solve the problems encountered in the prior art, the present invention provides a light emitting diode device and a manufacturing method thereof, such that a light emitting diode device having an insulating substrate has a vertical electrode structure, except that a portion of the light emitting region is not sacrificed (reduced In addition to the effective light-emitting area, the uniformity of the effective injection of the electron flow into the light-emitting layer can be improved (the current is uniformly distributed through the path to the entire light-emitting diode), and the overall luminous efficiency is improved.

According to an embodiment of the invention, the light emitting diode device may include: an insulating substrate having an upper surface and a lower surface; a patterned conductive layer disposed on a portion of the upper surface of the insulating substrate; a buffer layer, configured An upper surface of the insulating substrate that is not covered by the patterned conductive layer; a first semiconductor layer disposed on the buffer layer; a light emitting layer disposed on the first semiconductor layer; and a second semiconductor layer And disposed on the light emitting layer; and an electrode disposed on the second semiconductor layer. According to another embodiment of the invention, the patterned conductive layer may further extend to the sidewall of the insulating substrate. In addition, the patterned conductive layer may further extend to cover a portion of the lower surface of the insulating substrate.

The upper surface of the insulating substrate of the LED device of the present invention is completely covered by the patterned conductive layer and the buffer layer, and the buffer layer can further cover the patterned conductive layer. It should be noted that at least a portion of the patterned conductive layer formed on the upper surface of the substrate is adjacent to the boundary of the upper surface. In addition, the patterned conductive layer is designed to focus on that the patterned conductive layer formed on the upper surface of the substrate accounts for 10-50% of the surface area of the substrate. If the ratio of the patterned conductive layer to the surface area of the substrate is less than 10%, the current distribution of the light emitting diode device is concentrated, resulting in a decrease in electric field uniformity; on the contrary, the patterned conductive layer accounts for The surface area of the substrate is not too large, otherwise the upper surface area of the substrate occupied by the buffer layer formed on the upper surface of the substrate is too low, which affects the subsequent film layers (the light emitting layer, the first semiconductor layer, the second semiconductor layer). Epitaxial quality. The patterned conductive layer may be disposed around the upper surface of the substrate (close to the boundary of the upper surface) or have a lattice structure. The buffer layer may have a thickness greater than or equal to the patterned conductive layer, and the buffer layer preferably covers the patterned conductive layer. The electrode comprises a transparent electrode, a metal electrode, or a combination thereof.

The LED device of the present invention may further include a lead frame, the lead frame may have a first circuit and a second circuit, wherein the insulating substrate is disposed on the lead frame, and the patterned conductive layer Electrically contacting the first circuit. In addition, the electrode and the second circuit can be electrically connected by a wire.

Hereinafter, the illustration will be made to illustrate a light-emitting diode device and a method of manufacturing the same according to the present invention.

According to an embodiment of the invention, a method of fabricating a light emitting diode device includes the following steps:

First, please refer to FIG. 2A to provide an insulating substrate 102 having an upper surface 101, a lower surface 103, and a sidewall 104. Referring to FIG. 2B, it is tangent to A-A' in FIG. 2A. Profile structure. The insulating substrate 102 can be a conventional insulating substrate such as a sapphire (alumina) substrate, an aluminum nitride substrate, or a zinc oxide substrate.

Next, referring to FIG. 3A, a conductive layer is formed on the upper surface 101 of the insulating substrate 102, and patterned to obtain a patterned conductive layer 106. It should be noted that the patterned conductive layer 106 does not cover the entire upper surface 101 of the insulating substrate 102. Therefore, after the patterned conductive layer 106 is formed on the substrate, the uncovered insulating substrate 102 upper surface 101 is still exposed. Please refer to Figure 3B for the cross-sectional structure along the line A-A' of Figure 3A. The patterned conductive layer 106 may have a lattice, a spiral, a ring, a finger, etc., a dot or a strip structure, and the specific pattern is not limited, and may be changed as needed, as shown in FIGS. 4 and 5. In addition, the patterned conductive layer may also be disposed only around the upper surface of the substrate (close to the boundary of the upper surface), or further cover the side of the substrate, as shown in FIG. The patterned conductive layer 106 may comprise a transparent or opaque conductive material such as: indium tin oxide (ITO), indium zinc oxide (IZO), zinc aluminum oxide (AZO), zinc oxide (ZnO), palladium, Platinum, nickel, gold, silver, aluminum, tungsten, copper, or a combination thereof. In addition, the patterned conductive layer 106 can also be a composite film layer, for example, further comprising an ohmic contact material, a diffusion barrier layer, a metal bonding layer, a reflective layer, or a combination thereof.

According to another embodiment of the present invention, referring to FIG. 7A, when the patterned conductive layer 106 is formed, the patterned conductive layer 106 is preferably formed on the sidewall 104 of the insulating substrate 102 to facilitate subsequent illumination. Electrical connection of the polar body device. Referring to FIG. 7B, which is a cross-sectional structure along the line A-A' of FIG. 7A, the patterned conductive layer 106 further extends from the boundary of the upper surface 101 of the insulating substrate 102 to the sidewall 104 of the insulating substrate 102. The patterned conductive layer 106 can be formed in a wafer step (before cutting) or a wafer step (after cutting the wafer into a plurality of wafers), which can be formed by thermal evaporation, sputtering or plasma-enhanced chemical gas. Phase deposition method. For example, if it is formed in the wafer step, please refer to FIG. 8 , a channel or a plurality of through holes 150 may be formed on the wafer 200 in advance. When the conductive layer is formed on the wafer 200 , the conductive layer is formed. The layer material may be formed on the upper surface of the substrate 102, and may extend through the channel or the through hole 150 and cover the sidewall 104 of the insulating substrate 102. Furthermore, after the step of forming the patterned conductive layer 106 on the upper surface 101 and the sidewalls 104 of the insulating substrate 102, the bottom conductive layer 107 may be further formed on a portion of the lower surface 103 of the insulating substrate 102 and formed. The patterned conductive layer 106 on the sidewall is electrically contacted, in other words, the patterned conductive layer 106 is further extended to cover a portion of the lower surface 103 of the insulating substrate 102. Please refer to FIG.

Here, the structure shown in FIG. 3A is taken as an example to describe the manufacture of the light-emitting diode device according to the present invention. Next, referring to FIG. 10A, a buffer layer 108 is formed on the upper surface 101 of the insulating substrate 102 that is not covered by the patterned conductive layer 106. The buffer layer 108 may have a thickness greater than or equal to the patterned conductive layer 106. Referring to FIG. 10B, it is a cross-sectional structure along the line AA' of FIG. 10A. In addition, according to another embodiment of the present invention, the thickness of the buffer layer 108 is preferably larger than the patterned conductive layer 106, and the patterned conductive layer 106 is covered satisfactorily. Please refer to FIG. 11A and FIG. 11B. It is a cross-sectional structure along the line A-A' of Figure 11A). The present invention is not limited to the material of the buffer layer 108 used, and may be any buffer material for a light-emitting diode, such as an undoped semiconductor layer (which may be selected from the group III-V chemical element, II). - any combination of chemical elements of Group VI, chemical elements of Group IV, and chemical elements of Group IV-IV).

Here, the structure shown in FIG. 11A is taken as an example to describe the manufacture of the light-emitting diode device according to the present invention. Next, referring to FIG. 12A, a semiconductor device composite layer 115 is formed on the buffer layer 108. The semiconductor device composite layer 115 sequentially includes a first semiconductor layer 110, a light emitting layer 112, and a second semiconductor layer 114. Please refer to Fig. 12B (the cross-sectional structure along the line A-A' of Fig. 12A). The luminescent layer 112 is a semiconductor material layer and may have a multiple quantum well (MQW) structure, which may be selected from the group consisting of chemical elements of group III-V, chemical elements of group II-VI, and chemistry of group IV. Element, chemical element of group IV-IV, or a combination thereof, for example: AlN, GaN, AlGaN, InGaN, AlInGaN, GaP, GaAsP, GaInP, AlGaInP, or AlGaAs. The first semiconductor layer 110 and the second semiconductor layer 114 are respectively an N-type epitaxial layer and a P-type epitaxial layer. Of course, they may be interchanged, and are not limited thereto, and the materials may also be respectively selected from the same. a chemical element of Group III-V, a chemical element of Group II-VI, a chemical element of Group IV, a chemical element of Group IV-IV, or a combination thereof. For example, when the first semiconductor layer 110 is an N-type gallium nitride-based semiconductor, the second semiconductor layer 114 is a P-type gallium nitride-based semiconductor, and the first semiconductor layer 110 is a P-type gallium nitride-based semiconductor. The second semiconductor layer 114 is an N-type gallium nitride-based semiconductor, and the light-emitting layer 112 may be a gallium nitride-based semiconductor. After the step of forming the semiconductor device composite layer 115, a transparent electrode 116 is formed on the second semiconductor layer 114. Please refer to FIG. 13A and FIG. 13B (which is tangent to A-A' along FIG. 13A). Section structure). The transparent electrode 116 may be indium tin oxide (ITO), indium zinc oxide (IZO), zinc aluminum oxide (AZO), zinc oxide (ZnO) or a combination thereof, and may be formed by thermal evaporation or sputtering. Shot or plasma enhanced chemical vapor deposition. Next, a metal electrode 118 is formed on the transparent electrode 116 to obtain a light-emitting diode wafer 300. Please refer to FIGS. 14A and 14B (which are cross-sectional structures along the line A-A' of FIG. 13A). The metal electrode 1118 can be palladium, platinum, nickel, gold, silver, aluminum, tungsten, copper, or a combination thereof, and can be formed by thermal evaporation, sputtering, or plasma enhanced chemical vapor deposition.

After the fabrication of the LED substrate 300 is completed, the method for fabricating the LED device of the present invention may further include bonding the LED wafer 300 to a lead frame 120. The lead frame is provided with a first circuit 125 and a second circuit 127 which are pre-designed. When the LED array 300 is bonded to the lead frame 120, the patterned conductive layer 106 needs to be in contact with the protruding portion of the first circuit 125. Furthermore, the metal electrode 118 and the second circuit 127 can be electrically connected by a wire 129. Referring to FIG. 16, the LED chip 300 can be driven to obtain a light-emitting diode. Diode device 400.

In addition, in another embodiment of the present invention, the structure shown in FIG. 7A (the patterned conductive layer extends to the sidewall 104 of the insulating substrate 102) is continued through the manufacturing process shown in FIGS. 11A to 14A. The buffer layer, the N-type semiconductor layer, the light-emitting layer, the P-type semiconductor layer, and the electrode layer) obtain a light-emitting diode wafer 300. Then, the LED chip 300 is fixed to a lead frame 120. The lead frame is provided with a first circuit 125 and a second circuit 127 which are pre-designed. The LED substrate 300 is bonded to the lead frame 120, and a portion of the lower surface 103 of the patterned conductive layer covering the insulating substrate 102 is in contact with the first circuit 125. Furthermore, the metal electrode 118 and the second circuit 127 can be electrically connected by a wire 129. Referring to FIG. 17, a light-emitting diode device 400 is obtained. Since the LED wafer 300 itself has a patterned conductive layer 106 extending to the sidewall 104 of the insulating substrate 102, it can be directly in contact with the flat first circuit 125 to achieve electrical connection.

According to another embodiment of the present invention, the structure shown in FIG. 9 is used (the patterned conductive layer 106 extends to the bottom surface of the insulating substrate 102, and a bottom conductive portion 102 is formed on the bottom surface 103 of the insulating substrate 102. The layer 107 is further electrically connected to the patterned conductive layer 106. A light-emitting diode wafer 300 is obtained through the manufacturing process shown in FIGS. 11A to 14A. Then, the LED chip 300 is fixed to a lead frame 120. The lead frame is provided with a first circuit 125 and a second circuit 127 which are pre-designed. The LED substrate 300 is bonded to the lead frame 120, and a portion of the lower surface 103 of the patterned conductive layer covering the insulating substrate 102 is in contact with the first circuit 125. Furthermore, the metal electrode 118 and the second circuit 127 can be electrically connected by a wire 129. Referring to FIG. 18, a light-emitting diode device 400 is obtained. Since the LED chip 300 itself has the patterned conductive layer 106 extending to the sidewall 104 and the bottom 103 of the insulating substrate 102, it can be directly in contact with the flat first circuit 125 to achieve electrical connection.

Based on the above, the light-emitting diode device and the method of manufacturing the same according to the present invention can enable the light-emitting diode device having an insulating substrate to have a vertical electrode structure, except that a portion of the light-emitting region is not sacrificed (the effective light-emitting area is reduced). In addition, the uniformity of the effective injection of the electron flow into the light-emitting layer can be improved (the current is uniformly distributed through the path to the entire light-emitting diode), and the overall luminous efficiency is improved.

While the invention has been described above in terms of several preferred embodiments, it is not intended to limit the scope of the present invention, and any one of ordinary skill in the art can make any changes without departing from the spirit and scope of the invention. And the scope of the present invention is defined by the scope of the appended claims.

10. . . Light-emitting diode

12. . . Sapphire substrate

13. . . The buffer layer

14. . . N-type semiconductor layer

15. . . Semiconductor component layer

16. . . Luminous layer

18. . . P-type semiconductor layer

20. . . First electrode

twenty two. . . Second electrode

25. . . Shortest path

101. . . Upper surface

102. . . Insulating substrate

103. . . lower surface

104‧‧‧ side wall

106‧‧‧Graphic conductive layer

108‧‧‧buffer layer

110‧‧‧First semiconductor layer

112‧‧‧Lighting layer

114‧‧‧Second semiconductor layer

115‧‧‧Semiconductor component composite layer

116‧‧‧Transparent electrode

118‧‧‧Metal electrode

120‧‧‧ lead frame

125‧‧‧First circuit

127‧‧‧second circuit

129‧‧‧Wire

150‧‧‧through holes

200‧‧‧ wafer

300‧‧‧Light Diode Wafer

400‧‧‧Lighting diode device

A-A’‧‧‧ tangent

Figure 1 is a cross-sectional structural view showing the structure of a light-emitting diode according to the prior art.

2A, 3A, 7A, 10A, 11A, 12A, 13A, and 14A are a series of above diagrams for explaining the manufacturing process of the light-emitting diode device of the embodiment of the present invention.

2B, 3B, 7B, 10B, 11B, 12B, 13B, and 14B are cross-sectional structural views of the A-A' tangent of the 2A, 3A, 7A, 10A, 11A, 12A, 13A, and 14A graphs.

Figures 4, 5, and 6 are a series of above diagrams for illustrating the design of the patterned conductive layer of the light emitting diode device of other embodiments of the present invention.

Figure 8 is a top view for explaining the formation of a patterned conductive layer disposed on the side of an insulating substrate according to another embodiment of the present invention.

Figure 9 is a cross-sectional structural view for explaining the design of a patterned conductive layer of a light-emitting diode device according to another embodiment of the present invention.

15 and 16 are a series of cross-sectional structural views for explaining the manufacturing process of the light-emitting diode device according to another embodiment of the present invention.

Figure 17 is a cross-sectional structural view showing a light-emitting diode device according to another embodiment of the present invention.

Figure 18 is a cross-sectional structural view showing a light-emitting diode device according to still another embodiment of the present invention.

101. . . Upper surface

102. . . Insulating substrate

104. . . Side wall

106. . . Graphical conductive layer

108. . . The buffer layer

110. . . First semiconductor layer

112. . . Luminous layer

114. . . Second semiconductor layer

115. . . Semiconductor component composite layer

116. . . Transparent electrode

118. . . Metal electrode

120. . . Lead frame

125. . . First circuit

127. . . Second circuit

129. . . wire

400. . . Light-emitting diode device

Claims (13)

A light emitting diode device comprising: an insulating substrate having an upper surface and a lower surface; a patterned conductive layer disposed on a portion of the upper surface of the insulating substrate and further extending over the sidewall of the insulating substrate; a layer disposed on the upper surface of the insulating substrate not covered by the patterned conductive layer; a first semiconductor layer disposed on the buffer layer; a light emitting layer disposed on the first semiconductor layer; a second semiconductor layer disposed on the light emitting layer; and an electrode disposed on the second semiconductor layer. The illuminating diode device of claim 1, wherein the patterned conductive layer disposed on the upper surface of the substrate accounts for 10-50% of the surface area of the substrate. The illuminating diode device of claim 1, wherein the patterned conductive layer is disposed around the upper surface of the substrate. The illuminating diode device of claim 1, wherein the patterned conductive layer is a lattice, a spiral, a ring, a finger, or a combination thereof. The illuminating diode device of claim 1, wherein the buffer layer has a thickness greater than or equal to the patterned conductive layer. The illuminating diode device of claim 1, wherein the electrode comprises a transparent electrode, a metal electrode, or a combination thereof. The light-emitting diode device according to claim 1, further comprising: A lead frame has a first circuit and a second circuit, wherein the insulating substrate is disposed on the lead frame, and the patterned conductive layer is in electrical contact with the first circuit. A method for manufacturing a light-emitting diode device, comprising: providing an insulating substrate having an upper surface and a lower surface; forming a patterned conductive layer on a portion of the upper surface and the sidewall of the insulating substrate; forming a buffer layer on The insulating substrate is not covered by the patterned conductive layer; a first semiconductor layer is formed on the buffer layer; a light emitting layer is formed on the first semiconductor layer; and a second semiconductor layer is formed thereon. Above the light emitting layer; and forming an electrode disposed on the second semiconductor layer. The method for manufacturing a light-emitting diode device according to claim 8 , after the step of forming the patterned conductive layer on a portion of the upper surface and the sidewall of the insulating substrate, further comprising: forming a bottom conductive layer A portion of the lower surface of the insulating substrate is electrically contacted with the patterned conductive layer. The method for manufacturing a light-emitting diode device according to claim 8, wherein the patterned conductive layer disposed on the upper surface of the substrate accounts for 10-50% of the surface area of the substrate. The method for fabricating a light-emitting diode device according to claim 8, wherein in the step of forming the buffer layer, the buffer layer is formed to cover the upper surface of the insulating substrate and cover the patterned conductive layer. Floor. The method for fabricating a light-emitting diode device according to claim 8, wherein the step of forming the electrode comprises: forming a transparent electrode on the second semiconductor layer; and forming a metal electrode on the transparent electrode on. The method for manufacturing a light-emitting diode device according to claim 8, further comprising: providing a lead frame having a first circuit and a second circuit; and fixing the insulating substrate to the wire And causing the patterned conductive layer to be in electrical contact with the first circuit.