LIGHT-EMITTING DIODE CHIP AND LIGHT-EMITTING DIODE DEVICE

A light-emitting diode chip includes a semiconductor layer, an insulating layer, a first and a second electrode. The semiconductor layer has a top side, a bottom side opposite to the top side and a sidewall connecting the top side and the bottom side, and a concave-convex structure is at the top side of the semiconductor layer. The insulating layer covers the sidewall and the bottom side of the semiconductor layer, and has a protruding portion extending and protruding above the concave-convex structure along a direction parallel to the sidewall. A vertical distance between a highest point of the concave-convex structure and that of the protruding portion is from 0.5 μm to four times the thickness of the semiconductor layer. The first and the second electrode are on the bottom side of the semiconductor layer and penetrate through the insulating layer. The second electrode is adjacent to the first electrode.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Taiwan Application Serial Number 110130520, filed Aug. 18, 2021, which is herein incorporated by reference in its entirety.

BACKGROUND

Field of Invention

The present disclosure relates to a light-emitting diode chip and a light-emitting diode device. More particularly, the present disclosure relates to an insulating layer of the light-emitting diode chip and the light-emitting diode device.

Description of Related Art

In recent years, various novel displays have gradually become popular. These displays are mainly developed towards a direction of increasing resolution and saving energy. A micro light-emitting diode (μLED) display is one of the important types of displays in development.

Micro light-emitting diodes have reduced the size of conventional light-emitting diodes to approximately 100 microns or below, even to a magnitude of tens of microns. The number of the LEDs in the same area significantly increases at this magnitude, so the yield of the LEDs transferred from a substrate to a display substrate should reach above 99%. With techniques of recent processes, this mass transfer still faces several problems to be solved.

SUMMARY

According to some embodiments of the present disclosure, a light-emitting diode chip includes a semiconductor layer, an insulating layer, a first electrode and a second electrode. The semiconductor layer has a sidewall, a top side and a bottom side opposite to the top side. The sidewall connects the top side and the bottom side, and a concave-convex structure is at the top side of the semiconductor layer. The insulating layer covers the sidewall and the bottom side of the semiconductor layer. The insulating layer has a protruding portion extending and protruding above the concave-convex structure along a direction parallel to the sidewall, and a vertical distance between a highest point of the concave-convex structure and a highest point of the protruding portion is greater than 0.5 μm and is less than four times a thickness of the semiconductor layer. The first electrode is on the bottom side of the semiconductor layer and penetrates through the insulating layer. The second electrode is adjacent to the first electrode, and the second electrode is on the bottom side of the semiconductor layer and penetrates through the insulating layer.

According to some embodiments of the present disclosure, a thickness of the protruding portion of the insulating layer along a direction perpendicular to the sidewall is in a range from about 0.4 μm to about 3.5 μm.

According to some embodiments of the present disclosure, the highest point of the protruding portion and a center point of the concave-convex structure forms a connecting line, and the connecting line and a horizontal cross-section of the semiconductor layer forms a first angle in a range from about 1° to about 10°.

According to some embodiments of the present disclosure, an upper surface of the protruding portion of the insulating layer is flat.

According to some embodiments of the present disclosure, an upper surface of the protruding portion of the insulating layer tilts to the semiconductor layer.

According to some embodiments of the present disclosure, the upper surface and a horizontal cross-section of the semiconductor layer forms a second angle, a surface of the concave-convex structure and the horizontal cross-section of the semiconductor layer forms a third angle, and the second angle is smaller than the third angle.

According to some embodiments of the present disclosure, the protruding portion is a closed ring and is set along a perimeter of the semiconductor layer to surround the semiconductor layer.

According to some embodiments of the present disclosure, the protruding portion is a non-closed ring comprising at least an opening and is set along a perimeter of the semiconductor layer to surround the semiconductor layer.

According to some embodiments of the present disclosure, the protruding portion includes at least a pair of sub-protruding portions, and the at least a pair of sub-protruding portions are point symmetrically centered at a geometric center of the semiconductor layer and are set at a perimeter of the semiconductor layer.

According to some embodiments of the present disclosure, the insulating layer is able to deflect light emitting from the semiconductor layer.

According to some embodiments of the present disclosure, the insulating layer comprises a distributed Bragg reflector (DBR).

According to some embodiments of the present disclosure, a material of the insulating layer comprises an oxide layer, a nitride layer, or combinations thereof.

According to some embodiments of the present disclosure, a light-emitting diode device includes a carrier and a plurality of the light-emitting diode chips arranged on the carrier.

The protruding portion of the insulating layer in the present disclosure can reduce the contact area between the light-emitting diode chip and the adhesive material, thereby reducing adhesion between the light-emitting diode chip and the adhesive material. Therefore, when transferring the light-emitting diode chip, the light-emitting diode chip will not be unable to entirely detached from the adhesive material due to excessively huge adhesion between the light-emitting diode chip and the adhesive material, such that the yield of transferring the light-emitting diode chip may be improved.

DETAILED DESCRIPTION

In various embodiments, description is made with reference to figures. However, certain embodiments may be practiced without one or more of these specific details, or in combination with other known methods and configurations. In the following description, numerous specific details are set forth, such as specific configurations, dimensions and processes, etc., in order to provide a thorough understanding of the present disclosure. In other instances, well-known semiconductor processes and manufacturing techniques have not been described in particular detail in order to not unnecessarily obscure the present disclosure. Reference throughout this specification to “one embodiment,” “an embodiment”, “some embodiments” or the like means that a particular feature, structure, configuration, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of the phrase “in one embodiment,” “in an embodiment”, “in some embodiments” or the like in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more embodiments.

Some embodiments of the present disclosure can enhance yield of transferring light-emitting diodes. Specifically, an insulating layer of a light-emitting diode in some embodiments of the present disclosure has a protruding portion protruding above a semiconductor layer. Hence, when transferring light-emitting diodes by using a carrier including an adhesive material, the light-emitting diodes may insert into the adhesive material with the protruding portion, thereby reducing contact area between the light-emitting diode and the adhesive material. Adhesion between the light-emitting diode and the adhesive material is at a moderate level accordingly. Therefore, the light-emitting diode is well detached from the adhesive material during transfer, thereby enhancing yield of transferring the light-emitting diode chip.

FIGS.1A-14illustrate a manufacturing process of a light-emitting diode device200including light-emitting diode chips100. Referring toFIG.1A, a semiconductor layer110is formed on a wafer102. An upper surface102aof the wafer102is a concave-convex surface, so a concave-convex interface is formed between the semiconductor layer110and the wafer102when forming the semiconductor layer110on the wafer102. In some embodiments, a conformal polymer layer104is additionally formed between the semiconductor layer110and the wafer102, as shown inFIG.1B. Therefore, a concave-convex interface may also be formed between the polymer layer104and the wafer102.

In some embodiments, the wafer102may include semiconductor, silicon, sapphire, or the like. In some embodiments, the semiconductor layer110may at least include a first semiconductor layer, an active layer and a second semiconductor layer (may correspond to the first semiconductor layer114, the active layer116and the second semiconductor layer118inFIG.15). In some embodiments, the first semiconductor layer may be n-doped GaN, the active layer may be GaN added with quantum well structures and/or quantum dot structures, and the second semiconductor layer may be p-doped GaN. The semiconductor layer110may also be made of other materials.

Referring toFIG.2, an etching process is performed to etch the semiconductor layer110to form recesses112in the semiconductor layer110. In some embodiments, a suitable etching process, such as dry etching or wet etching, may be performed to form the recesses112. The recesses112define locations of subsequently formed electrodes (such as the first electrode131inFIG.5).

Referring toFIG.3, the semiconductor layer110is further partially etched to form a plurality of trenches T in the semiconductor layer110. Adjacent trenches T define a patterned semiconductor layer110′ and a sidewall (such as the sidewall111ainFIG.15) of a subsequently formed light-emitting diode chip (such as light-emitting diode chip100inFIG.15). InFIG.3, the semiconductor layer110is only partially etched, i.e. a bottom of the semiconductor layer110is still connected, and the etching process inFIG.3does not etch the wafer102.

Referring toFIG.4, after etching the semiconductor layer110, insulating layers120are conformally formed over the semiconductor layer110, and first electrode holes121and second electrode holes122are formed in the insulating layers120. The first electrode hole121is over the recess112. Therefore, the location of the first electrode hole121is lower than the second electrode hole122. In some embodiments, the first electrode hole121exposes the first semiconductor layer (such as the first semiconductor layer114inFIG.15) and the second electrode hole122exposes the second semiconductor layer (such as the second semiconductor layer118inFIG.15). In some embodiments, the insulating layers120include an oxide layer, a nitride layer, or combinations thereof.

Referring toFIG.5, first electrodes131and second electrodes132are formed in the first electrode holes121and the second electrode holes122. Any suitable conductive materials, such as metal, may be used to form the first electrodes131and the second electrodes132. The first electrode131and the second electrode132connect with different locations in the patterned semiconductor layer110′, such as different types of the semiconductor layers in the patterned semiconductor layer110′ (which will be described inFIG.15in detail).

Referring toFIG.6, a sacrificial layer142and a first carrier144are sequentially formed over the structure shown inFIG.5. The sacrificial layer142may be any suitable dielectric material, and the material has an etching selectivity compared to the insulating layers120. The first carrier144may be made of the material similar to or the same as the material of the wafer102. InFIG.7, the structure inFIG.6is then flipped, such that the first carrier144is at the bottom of the entire structure.

Referring toFIG.8, the wafer102is removed. The wafer102may be removed by an etching process, a laser-lift-off process, or other suitable methods. Because a concave-convex interface is between the patterned semiconductor layer110′ and the wafer102, after removing the wafer102, the patterned semiconductor layer110′ has a concave-convex structure113. When the subsequently formed light-emitting diode chip (such as the light-emitting diode chip100inFIG.15) has a concave-convex structure113, total reflection of light may be reduced, thereby increasing light extraction efficiency.

Referring toFIG.9, the patterned semiconductor layers110′ are partially removed, such that the heights of the patterned semiconductor layers110′ are lower than the heights of the insulating layers120and protruding portions124of the insulating layers120are formed. The protruding portions124of the insulating layers120protrude above the concave-convex structures113of the patterned semiconductor layers110′ and are used to enhance yield of chip transfer in a subsequent transfer process. Any suitable etching method may be used to remove a portion of the patterned semiconductor layers110′. The removal process inFIG.9removes the portion of the patterned semiconductor layers110′ downwardly at the substantially same rate; therefore the patterned semiconductor layers110′ still have the concave-convex structures113after the removal process. After or during removing the portion of the patterned semiconductor layers110′, the protruding portions124of the insulating layers120may be patterned, such that the protruding portions124of the insulating layers120have different plan-view patterns.

In some embodiments where polymer layers are on the patterned semiconductor layers110′ (such as the embodiment developed fromFIG.1B), the polymer layers104(FIG.1B) are partially removed, such that the protruding portions124of the insulating layers120protrude above the concave-convex structures113of the patterned semiconductor layers110′. Therefore, in this embodiment, the concave-convex structures113may also include the polymer layers104(FIG.19).

Referring toFIG.10, a portion of the sacrificial layer142is removed. Specifically, the sacrificial layer142is vertically (anisotropically) removed along outer surfaces of the insulating layers120, and independent light-emitting diode chips100are formed. Subsequently, referring toFIG.11, after flipping over the structure inFIG.10again, the light-emitting diode chips100on the first carrier144are transferred to a second carrier152. The second carrier152is coated with an adhesive material154. During the transfer of the light-emitting diode chips100, the protruding portions124of the insulating layers120easily insert into the adhesive material154and the light-emitting diode chips100are fixed on the adhesive material154. Because the protruding portions124are higher than top sides of the patterned semiconductor layers110′, the top sides of the patterned semiconductor layers110′ may not be in contact with the adhesive material154or only be partially in contact with the adhesive material154. Either way, adhesion between the top sides of the patterned semiconductor layers110′ and the adhesive material154is reduced due to reduction in contact area. And the light-emitting diode chips100are mainly fixed on the adhesive material154by the protruding portions124. In addition, the transfer process may selectively dispose some of the light-emitting diode chips100on the adhesive material154for different requirements. For example, as shown inFIG.11, this transfer process disposes some of the light-emitting diode chips100on the adhesive material154, and the other light-emitting diode chips100still remain on the first carrier144. Subsequently, the remaining sacrificial layers142at the transferred light-emitting chips are removed, as shown inFIG.12.

Referring toFIG.13, the second carrier152is flipped over, and the light-emitting diode chips100on the second carrier152are transferred to a third carrier162. In some embodiments, the third carrier162is a circuit board, and conductive pads164and166are disposed on the third carrier162. When transferring the light-emitting diode chips100, conductive pads164and166are in contact with the first electrode131and the second electrode132respectively to electrically connect with the first electrode131and the second electrode132respectively. As such, because the protruding portions124of the insulating layers120protrude above the patterned semiconductor layers110′, the contact area between the patterned semiconductor layer110′ and the adhesive material154is reduced when the protruding portion124of the insulating layer120inserts into the adhesive material154on the second carrier152. Adhesion between the patterned semiconductor layer110′ and the adhesive material154is also smaller. When transferring the light-emitting diode chips100to the third carrier162, smaller adhesion makes the patterned semiconductor layers110′ easily detached from the adhesive material154and then transfer to the third carrier162without damaging the patterned semiconductor layers110′ of the light-emitting diode chips100. The light-emitting diode chips100transferring to the third carrier162are arranged on the third carrier162and may be used for a light-emitting diode device200in a subsequent application, as shown inFIG.14.

FIG.15illustrates an enlarged diagram of the light-emitting diode chip100inFIG.14. InFIG.15, the light-emitting diode chip100includes a patterned semiconductor layer110′, an insulating layer120, a first electrode131and a second electrode132. The patterned semiconductor layer110′ has a sidewall111a, a top side111band a bottom side111copposite to the top side111b. The sidewall111aconnects the top side111band the bottom side111c, and a concave-convex structure113is at the top side111bof the patterned semiconductor layer110′. The concave-convex structure113may be regular or irregular. In some embodiments, the patterned semiconductor layer110′ may be a multilayer structure and includes a first semiconductor layer114, an active layer116and a second semiconductor layer118arranged from top to bottom. The first semiconductor layer114has a first type semiconductive material, such as n-type, and the second semiconductor layer118has a second type semiconductive material different from the first type semiconductive material, such as p-type. The active layer116may be a layer added with quantum well structures and/or quantum dot structures; therefore the active layer116may emit specific light when current passing through the active layer116.

The insulating layer120covers the sidewall111aand the bottom side111cof the patterned semiconductor layer110′. In some embodiments, the insulating layer120may be penetrated by light emitting from the active layer116of the patterned semiconductor layer110′ to obtain a light pattern with a large beam angle. In some embodiments, the insulating layer120is able to reflect light emitting from the active layer116of the patterned semiconductor layer110′ to obtain a light pattern with concentrated top view light. In some embodiments, the insulating layer120includes a distributed Bragg reflector (DBR). The insulating layer120has a protruding portion124extending and protruding above the concave-convex structure113along a direction parallel to the sidewall111a. The light-emitting diode chip100with the protruding portion124of the insulating layer120is easily fixed to the adhesive material154shown inFIG.11by the protruding portion124. Further, the presence of the protruding portion124of the insulating layer120reduces adhesion between the adhesive material154and the light-emitting diode chip100. Hence, when the light-emitting diode chip100is transferred to the third carrier162(referring toFIG.13), huge adhesion, which makes the adhesive material154damage, stick to, or be not able to detach from the light-emitting diode chip100, is avoided, thereby yield of transferring the light-emitting diode chip100is increased. In some embodiments, a thickness T1of the insulating layer120is in a range from about 0.4 μm to about 3.5 μm. If the thickness of the insulating layer120is out of the disclosed range, the protruding portion124of the insulating layer120is difficult to insert into the adhesive material154, such that the light-emitting diode chip100is difficult to be fixed on the adhesive material154.

In some embodiments, a vertical distance D1is between a highest point of the concave-convex structure113and a highest point of the protruding portion124, and the vertical distance D1is greater than 0.5 μm and is less than four times the thickness T2of the patterned semiconductor layer110′. In some other embodiments, the highest point of the protruding portion124and a center point C of the concave-convex structure113forms a connecting line L1, and the connecting line L1and a horizontal cross-section HL of the patterned semiconductor layer110′ forms a first angle α1 in a range from 1° to 10°. When the light-emitting diode chip100can reflect light emitting from the active layer116, the beam angle of the light-emitting diode chip100is thereby limited in a predetermined range, such as less than 120°. In some embodiments, the horizontal cross-section HL may be the interface between the first semiconductor layer114and the active layer116or the interface between the second semiconductor layer118and the active layer116.

In some embodiments, an upper surface of the protruding portion124tilts to the patterned semiconductor layer110′. Tilt degree of the upper surface of the protruding portion124may be determined based on different situations; for example, when the viscosity of the adhesive material154is higher, greater tilt degree may make the protruding portion124easier to insert into the adhesive material154. In some embodiments, an extending line L2of the upper surface of the protruding portion124and the horizontal section HL forms a second angle α2, and an extending line L3of any surface of the concave-convex structure113and the horizontal section HL forms a third angle α3. And the second angle α2 is less than the third angle α3. When the second angle α2 is smaller than the third angle α3 and the protruding portion124of the insulating layer120may reflect light emitting from the concave-convex structure113, light of the light-emitting diode chip100may concentrate and emit upwards.

The first electrode131and the second electrode132are at the bottom side111cof the patterned semiconductor layer110′, and the second electrode132is adjacent to the first electrode131. The first electrode131penetrates through the insulating layer120and is in contact with the first semiconductor layer114, and the second electrode132penetrates through the insulating layer120and is in contact with the second semiconductor layer118. The first electrode131and the second electrode132may further electrically connect with the conductive pads164and166on the third carrier162respectively.

The protruding portion124of the insulating layer120may have different shapes. For example, the upper surface of the protruding portion124may be flat, as shown inFIG.16, which illustrates the light-emitting diode chip100of some embodiments in accordance with the present disclosure. InFIG.16, the upper surface of the protruding portion124may be substantially parallel to the horizontal section HL. Details related to the light-emitting diode chip100inFIG.16are the same as or similar to details related to the light-emitting diode chip100inFIG.15; therefore detailed descriptions are not described herein.

FIGS.17A-18Billustrate top views of the light-emitting diode chips100of some embodiments in accordance with the present disclosure. In some embodiments, the protruding portion124of the insulating layer120may also have different plan-view patterns. For example, inFIG.17A, the protruding portion124of the insulating layer120is a closed ring and is set along a perimeter of the patterned semiconductor layer110′ to surround the patterned semiconductor layer110′. InFIG.17B, the protruding portion124of the insulating layer120is a non-closed ring including at least an opening123and is set along the perimeter of the patterned semiconductor layer110′ to surround the patterned semiconductor layer110′. It is noted that the location of the opening123is not limited to the location shown inFIG.17B. For example, the opening123may be at the longer side of the protruding portion124, as shown inFIG.17B. The opening123may also be at the shorter side of the protruding portion124. The opening123exposes the insulating layer120below, i.e. in the opening123, the bottom of the opening123of the insulating layer120is leveled with the top side111bof the patterned semiconductor layer110′. In some embodiments, the protruding portion124of the insulating layer120may also include at least a pair of sub-protruding portions126, as shown inFIGS.18A and18B. The sub-protruding portions126may have any suitable shapes, such as rectangles (FIG.18A), circles (FIG.18B) or other suitable shapes. Each pair of the sub-protruding portions126are disposed point-symmetrically about a geometric center P of the patterned semiconductor layer110′ and are set at the perimeter of the patterned semiconductor layer110′. The size of the sub-protruding portions126are large enough to insert into the adhesive material154and provide adhesion to the adhesive material154, and reduce the contact area between the light-emitting diode chip100and the adhesive material154.

FIG.19illustrates a cross-section view of the light-emitting diode chip100of some embodiments in accordance with the present disclosure. In some embodiments, the concave-convex structure113may also include polymer. For example, when the light-emitting diode chip100is developed from the structure shown inFIG.1B, the polymer layer104is not entirely removed in the process. In the final structure of the light-emitting diode chip100, the polymer layer104is still on the patterned semiconductor layer110′. Therefore, the concave-convex structure113may also include polymer, as shown inFIG.19.

As mentioned above, the protruding portion of the insulating layer in the present disclosure can reduce the contact area between the light-emitting diode chip and the adhesive material, thereby reducing adhesion between the light-emitting diode chip and the adhesive material. Therefore, when transferring the light-emitting diode chip, the light-emitting diode chip will not stick on the adhesive material due to huge adhesion, thereby increasing yield of transferring the light-emitting diode chip.