阅读说明：本技术 一种半导体发光元件 (Semiconductor light-emitting element ) 是由 柯韦帆 吴俊毅 钟秉宪 于 2018-07-27 设计创作，主要内容包括：一种半导体发光元件,其包括键合衬底,该半导体发光元件的键合衬底包括第一表面和第二表面,第一表面上的多层金属层,多层金属层上的半导体发光序列,该键合衬底的边缘形成台阶结构,以使键合衬底的第一表面的边缘部分未被覆盖。(A semiconductor light emitting element includes a bonding substrate, the bonding substrate of the semiconductor light emitting element includes a first surface and a second surface, a multi-layer metal layer on the first surface, a semiconductor light emitting sequence on the multi-layer metal layer, and an edge of the bonding substrate forms a step structure so that an edge portion of the first surface of the bonding substrate is not covered.)

1. A semiconductor light-emitting element comprises a bonding substrate, wherein the bonding substrate of the semiconductor light-emitting element comprises a first surface and a second surface, a plurality of metal layers on the first surface, and a semiconductor light-emitting sequence on the plurality of metal layers, and the edge of the bonding substrate forms a step structure, so that the edge part of the first surface of the bonding substrate is not covered.

2. A semiconductor light emitting element according to claim 1, wherein the step structure width at the edge of the bonding substrate is at least 2 micrometers, more preferably 2 to 10 micrometers, and still more preferably 3 to 6 micrometers.

3. The semiconductor light emitting element according to claim 1, wherein the edge of the multi-layer metal layer forms a second step structure, and the second step structure is formed by removing the semiconductor light emitting sequence on the edge of the multi-layer metal layer, and the width of the second step structure is 1.5-10 microns, and more preferably, the mesa area is 3-8 microns.

4. A semiconductor light emitting element according to claim 1, wherein the bonding substrate sidewall surface has a relatively flat first portion and an uneven second portion.

5. The semiconductor light-emitting element according to claim 1, wherein the second portion of the surface of the sidewall of the bonding substrate which is not flat is a non-flat concave-convex structure.

6. The semiconductor light emitting element according to claim 1, wherein the second portion having the surface unevenness is close to the first surface of the bonding substrate or further extends to the first surface.

7. The semiconductor light emitting element according to claim 1, wherein the second portion having the surface unevenness is close to or extends to the second surface of the bonding substrate.

8. the semiconductor light-emitting element according to claim 1, wherein the second portion of the side wall having the surface unevenness is located at a position from a depth of the first surface to a depth of 1/3 to 1/2, and is a relatively flat first portion near the first surface side and the second surface side.

9. The semiconductor light emitting element according to claim 1, wherein the bonding substrate of the semiconductor light emitting element is a non-metal substrate.

10. The semiconductor light emitting element as claimed in claim 1, wherein the semiconductor epitaxial light emitting sequence has a longitudinal projected area ratio of the substrate of at least 50%.

11. The semiconductor light emitting element as claimed in claim 1, wherein the ratio of the longitudinal projected area of the substrate of the semiconductor epitaxial light emitting sequence is at least 70% or 80%.

12. The semiconductor light emitting element according to claim 1, wherein a transparent insulating layer is present at least at a portion of an interface between the semiconductor light emitting sequence and the plurality of metal layers, and the transparent insulating layer is one or more layers.

13. The semiconductor light emitting element according to claim 1, wherein the semiconductor light emitting element is a gallium arsenide-based light emitting element.

14. The semiconductor light emitting element as claimed in claim 13, wherein a current spreading layer is present between the semiconductor light emitting sequence and the transparent insulating layer.

15. The semiconductor light emitting element as claimed in claim 13, wherein the second step structure is formed on the current spreading layer, and the semiconductor light emitting sequence at the edge of the current spreading layer is removed.

16. The semiconductor light emitting element according to claim 13 or 16, wherein a projected area of at least one of the plurality of metal layers or the transparent insulating layer or the current spreading layer of the semiconductor light emitting element in a direction of the substrate is varied, or at least one step structure is formed at an edge.

17. The semiconductor light emitting element according to claim 13 or 16, wherein a projected area variation of at least one of the plurality of metal layers or the transparent insulating layer or the current spreading layer of the semiconductor light emitting element in a direction of the substrate shows an increasing tendency.

18. The semiconductor light emitting element as claimed in claim 1, wherein the plurality of metal layers comprise at least one of a bonding layer, a metal reflective layer, and an ohmic contact layer.

19. The semiconductor light emitting element as claimed in claim 1, wherein the non-metallic substrate is a conductive substrate, and a conductive metal layer is formed on a side opposite to the semiconductor light emitting sequence.

20. the semiconductor light-emitting element according to claim 1, wherein the conductive substrate is a laser light-absorbing substrate.

21. The semiconductor light-emitting element according to claim 1, wherein the conductive substrate is a silicon or silicon carbide substrate.

22. A method for manufacturing a semiconductor light emitting element includes the steps of: (1) preparing a bonding substrate of the semiconductor light-emitting element to be cut before, wherein the bonding substrate of the semiconductor light-emitting element comprises a first surface, a second surface, a plurality of metal layers on the first surface and a semiconductor light-emitting sequence on the plurality of metal layers; (2) etching the semiconductor light emitting sequence to form a first platform; (3) further etching and removing the multiple metal layers along the first platform to expose the substrate to form a second platform area; (4) the semiconductor light emitting elements are separated along the second land area to obtain a single chip structure.

23. The method of claim 22, wherein: and (3) an insulating protective layer is arranged in a partial region between the multilayer metal reflecting layer and the semiconductor light-emitting sequence, and the preparation method further comprises the step of etching and removing the insulating protective layer in the step (3).

24. The method of claim 22, wherein: the step of scratching comprises laser scratching or laser stealth cutting.

25. The method of claim 23, wherein: the insulating protective layer can be one layer or a plurality of layers, and the etching method is dry etching.

26. The method of claim 24, wherein: the method for removing the multilayer metal layer in the step (3) is a wet etching or dry and wet etching combined mode.

Technical Field

Relates to a semiconductor light-emitting element, in particular to an LED chip structure.

Background

In recent years, in order to obtain an LED structure with higher brightness, high power or high thermal emissivity, a conventional LED epitaxial structure is subjected to substrate transfer onto a transfer substrate having a metal reflective layer or a metal bonding layer, and an original substrate is removed by chemical wet etching or laser lift-off. Aiming at the structure, firstly, etching is carried out to remove the epitaxial structure on the metal reflecting layer and/or the metal bonding layer so as to form a cutting channel, and then a single chip structure is separated through the cutting channel in a blade scribing or laser scribing way. However, after laser scribing, a large amount of metal reflowing material is sputtered to the sidewall of the light emitting layer, which easily causes leakage of the light emitting layer and brightness reduction of the light emitted by the light emitting layer absorbed by the reflowing material.

Disclosure of Invention

In order to achieve the above object, the present invention provides a semiconductor light emitting device with high reliability and light emitting efficiency, which includes a bonding substrate, the bonding substrate of the semiconductor light emitting device includes a first surface and a second surface, a plurality of metal layers on the first surface, and a semiconductor light emitting sequence on the plurality of metal layers, and an edge of the bonding substrate forms a step structure so that the edge of the first surface of the bonding substrate is not covered.

Preferably, the exposed portion of the edge of the bonded substrate has a width of at least 2 microns, more preferably 2-10 microns, and even more preferably 3-6 microns.

Preferably, the edge of the multilayer metal layer forms a second step structure, the second step structure is formed by removing the semiconductor light emitting sequence on the edge of the multilayer metal layer, the width of the second step structure is 1.5 microns-10 microns, and more preferably, the mesa area is 3-8 microns.

Preferably, the bonded substrate sidewall surface has a relatively flat first portion and a non-flat second portion.

Preferably, the uneven second portion of the sidewall surface of the bonding substrate is an uneven convex-concave structure.

Preferably, the second portion of the surface unevenness is close to the first surface of the bonded substrate or further extends to the first surface.

Preferably, the second portion having the uneven surface is close to or extends to the second surface of the bonded substrate.

Preferably, the second portion of the side wall having the surface unevenness is located at a position from 1/3 to 1/2 deep with respect to the first surface, the first portion being relatively flat near the first surface side and the second surface side.

Preferably, the bonding substrate of the semiconductor light emitting element is a non-metal substrate.

Preferably, the longitudinal projection area ratio of the substrate of the semiconductor epitaxial light-emitting sequence is at least 50%.

Preferably, the longitudinal projection area ratio of the substrate of the semiconductor epitaxial light-emitting sequence is at least 70% or 80%.

Preferably, the edge of the bonded substrate forms a step structure, so that the edge of the first surface of the bonded substrate is exposed.

Preferably, a transparent insulating layer is present at least in part of the interface between the semiconductor light emitting sequence of the semiconductor light emitting element and the multilayer metal layer, and the transparent insulating layer is one or more layers.

Preferably, the semiconductor light emitting element is a gallium arsenide-based light emitting element.

Preferably, a current spreading layer is arranged between the semiconductor light emitting sequence and the transparent insulating layer.

Preferably, the second step structure is formed on the current spreading layer, the semiconductor light emitting sequence at the edge of the current spreading layer is removed, the width of the semiconductor light emitting sequence is 1.5 microns to 10 microns, and more preferably, the mesa area is 3 microns to 8 microns.

Preferably, the projected area of at least one of the multiple metal layers or the transparent insulating layer or the current spreading layer of the semiconductor light emitting element along the substrate direction is changed, or at least one step structure is formed at the edge.

Preferably, the change of the projected area of at least one of the multiple metal layers or the transparent insulating layer or the current spreading layer of the semiconductor light emitting element along the substrate direction is a trend of increasing or increasing the projected area.

Preferably, the multilayer metal layer comprises at least one of a bonding layer, a metal reflection layer and an ohmic contact layer.

Preferably, the non-metal substrate is a conductive substrate, and a conductive metal layer is arranged on the side opposite to the semiconductor light-emitting sequence.

Preferably, the conductive substrate is a substrate for absorbing laser.

Preferably, the conductive substrate is a silicon or silicon carbide substrate.

The invention provides a preparation method of a semiconductor light-emitting element, which comprises the following steps: (1) preparing a semiconductor light-emitting element to be cut, wherein a bonding substrate of the semiconductor light-emitting element comprises a first surface, a second surface, a plurality of metal layers on the first surface and a semiconductor light-emitting sequence on the plurality of metal layers; (2) etching the semiconductor light emitting sequence to form a first platform; (3) further etching and removing the multiple metal layers along the first platform to expose the substrate to form a second platform area; (4) the semiconductor light emitting elements are separated along the second land area to obtain a single chip structure.

preferably, an insulating protective layer is further arranged in a partial region between the multilayer metal reflecting layer and the semiconductor light emitting sequence, and the preparation method further comprises the step of etching and removing the insulating protective layer in the step (3).

Preferably, the step of scribing comprises laser scribing or laser stealth scribing.

Preferably, the insulating protective layer can be one or more layers, and the etching method is dry etching.

Preferably, the method for removing the multiple metal layers in step (3) is a wet etching method or a combination of dry and wet etching methods.

The structure of the invention has the following technical effects:

According to the preparation method, the phenomenon that the meltback materials generated by laser scribing are splashed to the side wall of the light emitting area of the semiconductor light emitting element can be reduced, the electric leakage phenomenon is reduced, and the yield of chip separation is improved; meanwhile, the area of the cutting channel can be effectively reduced, and the area ratio of a light-emitting area can be effectively improved, so that the light-emitting efficiency is improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. Furthermore, the drawing figures are for a descriptive summary and are not drawn to scale.

Fig. 1 is a schematic structural diagram obtained by implementing step (1) of the method for manufacturing a light emitting diode according to the present invention.

Fig. 2 is a schematic structural diagram of a first platform formed in step (2) of the method for manufacturing a light emitting diode according to the present invention.

Fig. 3 is a schematic structural diagram of a second platform formed in step (3) of the method for manufacturing a light emitting diode according to the present invention.

Fig. 4 (a) is a side view of the light emitting diode manufacturing method of the present invention after step (4) of laser stealth cutting.

Fig. 4 (b) is a top view of the light emitting diode manufacturing method according to the present invention after step (4) of laser stealth cutting.

Fig. 5 is a schematic view of a final structure obtained by implementing the method for manufacturing a light emitting diode according to the present invention.

Description of numbering: 1. back metal electrode, 2 bonding substrate, 3, multilayer metal layer, 4, transparent insulating layer, 5, semiconductor light-emitting sequence, 6, front electrode.

Detailed Description

Referring to fig. 1 ~ and fig. 5, it should be noted that the illustration provided in this embodiment is only a schematic illustration of the basic idea of the present invention, and only shows the components related to the present invention rather than the number, shape and size of the components in actual implementation, and the type, number and ratio of the components in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.

As shown in fig. 1, the manufacturing process of the light emitting device of the present invention includes the following steps, (1) obtaining the following light emitting structure before cutting, as shown in the figure: the LED packaging structure comprises a bonding substrate, wherein a back metal electrode 1 is arranged on the back side of the bonding substrate, a multilayer metal layer is arranged on the front side of the bonding substrate from bottom to top, the multilayer metal layer specifically comprises a metal bonding layer, a metal reflecting layer, a transparent insulating layer 4, a semiconductor light-emitting sequence and a front metal electrode, the semiconductor light-emitting sequence comprises a p-type cladding layer which is a 1 st semiconductor layer of a 1 st conduction type, an n-type cladding layer which is a 2 nd semiconductor layer of a 2 nd conduction type different from the 1 st conduction type, and a light-emitting layer which is clamped between the p-type cladding layer and the n-; the light-emitting layer, the n-type contact layer and the p-type contact layer are each formed of a III-V compound semiconductor. Specifically, the compound semiconductor can be formed using a compound semiconductor such as GaAs, GaP, or InP, a ternary compound semiconductor such as InGaAs, InGaP, or AlGaAs, or a quaternary compound semiconductor such as AlGaInP. For example, the light-emitting layer has a structure in which an n-type cladding layer 106 (which is formed by containing n-type AlGaInP) and a P-type cladding layer (which is formed by containing P-type AlGaInP) sandwich an active layer (which is formed by a body of an undoped AlGaInP-based compound semiconductor that is not doped with a dopant as an impurity), and the P-type cladding layer preferably includes a P-GaP layer (which is located on the transparent insulating layer 4 and is not shown) for facilitating current spreading on the P-layer semiconductor layer side, and the present invention is specifically a semiconductor light-emitting element after the gallium arsenide-based epitaxial structure is transferred to a bonded substrate.

An n-type contact layer formed on a part of a surface of the light-emitting layer on the opposite side of the light-extraction surface from the active layer side of the n-type clad layer; more preferably, in order to improve the light emitting efficiency, concave-convex portions are formed on the other surface side of the light emitting layer and the side surface of the light emitting layer, respectively; and a transparent insulating film covering the uneven portions on the other surface of the light-emitting layer and the uneven portions on the side surfaces of the light-emitting layer. A front electrode provided on the n-type contact layer on the side opposite to the reflective layer of the light-emitting layer; a pad electrode for wire bonding provided on the front electrode; the front electrode is not limited to such a shape, and may be formed in a circular shape or a polygonal shape (for example, a hexagonal shape) when viewed from above. In addition, the pad electrode is formed in contact with the surface of the front surface electrode. The front electrode is formed by metal material in ohmic contact with the n-type contact layer. For example, the surface electrode is formed of a metal material containing Au, Ge, Ni, or the like. The pad electrode is formed of a metal material containing Ti, Au, or the like, for example.

A reflective layer formed of a metal, provided on one surface side of the light-emitting layer, and reflecting light emitted from the active layer; is formed of a conductive material having a high reflectance with respect to light emitted from the active layer. As an example, the reflective layer is formed of a conductive material having a reflectance of 80% or more with respect to the light. The reflective layer reflects light that has reached the reflective layer out of light emitted from the active layer, toward the active layer side. The reflective layer is formed of a metal material such as Al, Au, Ag, or an alloy containing at least one metal material selected from these metal materials. As an example, the reflective layer is formed of Au of a prescribed film thickness. The reflective layer may be formed by further including a barrier layer made of a metal material such as Ti or Pt, or a bonding film which is easily bonded to the bonding layer.

A dielectric layer, i.e., an insulating film, provided between the light-emitting layer and the reflective layer, between the p-type contact layer and the reflective layer, in a region other than the region where the ohmic contact portion is provided; the insulating film may be formed of, for example, silicon oxide, silicon nitride. The insulating film may be formed of a plurality of insulating layers having different refractive indices, that is, a multilayer film in which a film made of silicon oxide and a film made of silicon nitride are laminated in a plurality of layers. The multilayer films as the plurality of insulating layers may be stacked in such a manner that the refractive index decreases in a direction away from the other surface (i.e., light extraction surface) of the light-emitting layer and the side surface of the light-emitting layer, for example. The dielectric layer may be formed of a laminated structure of thin films made of a plurality of materials having different refractive indices. For example, the dielectric layer may also be made as a distributed bragg mirror structure. As an example, a dielectric layer having the following DBR structure may be formed: SiO with a predetermined film thickness₂Formed layer of TiO of predetermined thickness₂The formed layers are formed into pairs, and the resulting pairs of layers are stacked multiple times to form a DBR structure. The ohmic contact portion is formed in an opening provided through a partial region of the dielectric layer, and electrically connects the p-type contact layer and the reflective layer. As an example, the ohmic contact is formed of a metal material containing Au, Zn, such as AuZn alloy.

The conductive supporting substrate is preferably a substrate that can absorb laser beam and is stealthy cut, and a back surface electrode provided on a surface of the supporting substrate opposite to a surface in contact with the bonding layer. The bonding layer may be formed of a barrier layer made of a metal material such as Ti or Pt, or a bonding film which is easily bonded to the reflective layer, including an ohmic contact electrode layer in ohmic contact with the supporting substrate. As one example, the ohmic contact electrode may be formed of a metal material including Au, Ti, Al, or the like; the barrier layer may be formed of Pt having a predetermined film thickness. In addition, the barrier layer inhibits the material constituting the junction film from being transferred to the ohmic contact electrode. Further, the bonding layer is formed of a material that is electrically and mechanically bonded to the reflective layer, and as an example, may be formed of Au of a prescribed film thickness as described above.

The back electrode is formed of a material electrically joined to the supporting substrate, for example, a metal material such as Ti or Au. In this embodiment, the back electrode is gold.

(2) Etching at least the semiconductor light emitting sequence to form a first platform;

Firstly, coating a layer of photoresist on the light emitting surface of the N side, and manufacturing a photoresist pattern in an exposure and development mode to expose the area needing to manufacture the cutting street. Then, etching is performed through the light emitting layer and stays in the GaP layer of the current spreading layer, preferably by dry etching, to form a first platform as shown in fig. 2, the GaP layer is at the bottom of the first platform, and a part of the GaP layer in the thickness direction of the bottom is remained.

(3) Further removing the multiple metal layers by etching;

As shown in fig. 3, the mirror layer in the scribe line region is further removed, the bonding layer is exposed to the silicon substrate to form a second mesa for subsequent separation, and the first mesa is converted into a first step structure. Specifically, photoresist is formed on the side wall of the first platform and the surface of the light-emitting surface on the top surface, a photoresist pattern is manufactured in an exposure and development mode, the bottom of the first platform is exposed, the edge part of the bottom of the first platform is covered by the photoresist, and the light-emitting area loss caused by etching the side wall of the semiconductor sequence by a subsequent etching process is avoided. And then, removing the GaP layer and the insulating layer by dry etching aiming at the exposed part of the photoresist, and removing the metal layer by wet etching or a dry-wet combined etching mode, wherein for example, the gold zinc and the gold reflecting layer are subjected to wet etching, the titanium platinum barrier layer is subjected to a dry etching combined mode to expose the substrate, a plurality of step structures can be formed at the edge after the etching is switched among a plurality of etching processes, for example, after the GaP layer and the insulating layer are removed by dry etching, the reflecting layer such as gold and gold zinc is removed by wet etching by adopting another process, and the inclined side wall can be formed on the GaP layer, the insulating layer and the plurality of metal layers in the etching process, so that the width change along the direction of the thickness penetrating into the substrate is caused, preferably, the trend of increasing or increasing the projection area is presented, the angle of light reflection is favorably formed.

(4) Separating the semiconductor light emitting elements to obtain a single chip structure;

The semiconductor light emitting element is separated on the exposed substrate surface, and a conductive substrate which absorbs laser light is preferable, and a semiconductor substrate, a Si substrate, a silicon carbide substrate, or the like is preferable. Then, the substrate is laser-stealth cut, as shown in fig. 4 (a) and 4 (b), the front surface is preferably stealth cut in the present embodiment, continuous or discontinuous nodes are formed at a depth of 1/3 to 1/2 of the nodes formed on the first surface of the substrate by controlling the intensity of the laser, as shown in fig. 5, and finally the front surface is cleaved to separate the chips. As shown in fig. 5, when the substrate is cleaved, due to the reduction of stress at the node generated by the laser, a fracture of the substrate occurs, and the sidewall surface of the bonded substrate forms a relatively flat first portion and a non-flat second portion, wherein the non-flat second portion of the sidewall surface of the bonded substrate is an uneven convex-concave structure, the uneven convex-concave structure of the sidewall surface of the bonded substrate is caused by continuous or discontinuous nodes generated by laser recessing, and the roughness of the uneven convex-concave structure is higher than that of a region where the sidewall is not formed and the fracture of the sidewall occurs.

Thus, a light emitting diode obtained by the present invention comprises a bonded substrate, the bonded substrate of the semiconductor light emitting element comprising a first surface and a second surface, a plurality of metal layers on the first surface, a semiconductor light emitting sequence on the plurality of metal layers, wherein the sidewall surface of the bonded substrate has a relatively flat first portion and an uneven second portion.

The second part with the uneven surface is close to the first surface of the bonding substrate, the second part with the uneven surface is close to the second surface of the bonding substrate or is positioned in the middle of the substrate, the side wall close to the first surface side and the second surface side is the second part of the opposite platform, or the second part with the uneven surface directly extends to the first surface or the second surface. And a step structure is arranged on the edge of the first surface of the substrate, the surface of the step structure is free of a plurality of metal layers, and the step structure is caused by the fact that the laser stealth cutting position is away from the side wall of the metal layer by a certain distance, so that the laser is prevented from directly striking the plurality of metal layers to generate metal meltback materials.

As an alternative embodiment, laser stealth dicing may be replaced by laser scribing, in which a groove with a certain depth is first etched on the first surface of the substrate using a continuous laser, and then the semiconductor light emitting element is cleaved using a cleaver to form a single light emitting element.

As an alternative embodiment, the fabrication method of the present invention is also applicable to the structure separation of a nitride-based transfer substrate to form a single light emitting chip, and more preferably, a transfer substrate capable of absorbing laser light, such as a silicon or silicon carbide substrate, is used, and a structure using a metal reflective layer or a metal layer as an electrical contact or a metal bonding layer is used below a semiconductor light emitting sequence on the substrate.

According to the preparation method provided by the invention, the second platform is formed by further etching the multiple metal layers to the surface of the substrate, so that the phenomenon that meltback substances generated by laser scribing crack are splashed to the side wall of the light-emitting area of the semiconductor light-emitting element can be reduced, the electric leakage phenomenon is reduced, and the yield of chip separation is improved. The laser scribing method can effectively reduce the area of the cutting channel and effectively improve the area ratio of the light-emitting area, thereby improving the light-emitting efficiency.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.