阅读说明：本技术 一种倒装led芯片及其制备方法 (Flip LED chip and preparation method thereof ) 是由 仇美懿 庄家铭 李进 于 2019-10-12 设计创作，主要内容包括：本发明公开了一种倒装LED芯片,其包括：倒装LED芯片本体,包括第一电极和第二电极；设于所述倒装LED芯片本体上的钝化保护层；和设于所述钝化保护层上的第一焊盘和第二焊盘,第一焊盘与所述第一电极连接,第二焊盘与所述第二电极连接；其中,在所述钝化保护层上设有排气槽,所述排气槽围绕第一电极和第二电极设置。本发明围绕倒装LED芯片电极设计了排气槽,其能够使得电极凹孔中封闭的气泡容易排出,改善了电极与焊盘的接触,从而增加LED可靠性。(The invention discloses a flip LED chip, which comprises: a flip-chip LED chip body comprising a first electrode and a second electrode; the passivation protective layer is arranged on the flip LED chip body; the first bonding pad and the second bonding pad are arranged on the passivation protective layer, the first bonding pad is connected with the first electrode, and the second bonding pad is connected with the second electrode; and the passivation protective layer is provided with an exhaust groove which is arranged around the first electrode and the second electrode. The invention designs the exhaust groove around the electrode of the flip LED chip, which can easily exhaust the bubbles sealed in the concave hole of the electrode, and improves the contact between the electrode and the bonding pad, thereby increasing the reliability of the LED.)

1. A flip LED chip, comprising:

a flip-chip LED chip body comprising a first electrode and a second electrode;

the passivation protective layer is arranged on the flip LED chip body; and

the first bonding pad and the second bonding pad are arranged on the passivation protective layer, the first bonding pad is connected with the first electrode, and the second bonding pad is connected with the second electrode;

and the passivation protective layer is provided with an exhaust groove, and the exhaust groove is arranged around the first electrode and/or the second electrode.

2. The flip LED chip of claim 1, wherein a distance between the air vent groove and the first/second electrode is 5 to 10 μm.

3. The flip LED chip of claim 1 or 2, wherein the vent grooves have a depth of 0.8 to 1.6 μm.

4. The flip LED chip of claim 1, wherein the vent channel has a square, conical, oval, or semi-circular cross-section.

5. The flip LED chip of claim 1, wherein the flip LED chip body comprises:

a substrate;

the epitaxial layer is arranged on the substrate and sequentially comprises a first semiconductor layer, a light emitting layer and a second semiconductor layer;

a transparent conductive layer disposed on the second semiconductor layer;

the composite reflecting layer is arranged on the transparent conducting layer;

a first electrode and a second electrode;

the first electrode is connected with the first semiconductor layer through a plurality of first holes which are formed in the epitaxial layer and penetrate through the first semiconductor layer; the second electrode is connected with the transparent conductive layer through a plurality of second holes penetrating through the composite reflection layer.

6. The flip LED chip of claim 5, wherein the flip LED chip body further comprises a current blocking layer, a first current spreading bar, and a second current spreading bar;

the first current expansion strip is connected with the first electrode and is connected with the first semiconductor layer through a third hole formed in the epitaxial layer;

the second current expansion strip is connected with the second electrode and is connected with the transparent conductive layer through a fourth hole formed in the composite reflection layer;

the current blocking layer is arranged between the transparent conducting layer and the second semiconductor layer.

7. The flip-chip LED chip of claim 5, wherein the first and second holes have a width of 3-10 μm.

8. The flip LED chip of claim 5, wherein the first and third holes are disposed proximate to an edge of the epitaxial layer and the second and fourth holes are disposed proximate to an edge of the composite reflective layer.

9. A method of fabricating a flip LED chip according to any one of claims 1 to 8, comprising:

(1) preparing a flip LED chip body;

(2) forming a passivation protective layer on the surface of the LED chip body;

(3) photoetching the passivation protective layer to form an exhaust groove;

(4) forming a first pad and a second pad on the passivation protection layer; and obtaining the finished product of the flip LED chip.

10. The method of fabricating the flip LED chip of claim 9, wherein the method of fabricating the flip LED chip body comprises:

(1) providing a substrate;

(2) forming an epitaxial layer on the substrate; the epitaxial layer comprises a first semiconductor layer, a light emitting layer and a second semiconductor layer;

(3) photoetching the epitaxial layer to form a plurality of first holes, wherein the first holes penetrate through the first semiconductor layer;

(4) forming a transparent conductive layer on the epitaxial layer;

(5) forming a composite reflective layer on the transparent conductive layer;

(6) photoetching the composite reflecting layer to form a plurality of second holes;

(7) forming a first electrode and a second electrode to obtain a flip LED chip body; the first electrode is connected with the first semiconductor through the first hole, and the second electrode is connected with the transparent conducting layer through the second hole.

Technical Field

The invention relates to the technical field of photoelectron manufacturing, in particular to a flip LED chip and a preparation method thereof.

Background

The flip LED chip is a novel LED chip, and the heat dispersion and the light efficiency of the flip LED chip are superior to those of a common normally-installed LED chip. The flip LED chip is packaged on the traditional forward-mounted LED chip, so that the difference is large, and the realization of effective packaging is the key content of industrialization of the flip LED chip. In the chip design that has now, digging the hole to epitaxial layer and DBR layer, can leading to electrode surface unevenness, after using the tin cream to weld electrode and pad, when carrying out the reflow soldering test, letting in electric current preheats the unable discharge of electrode groove department production bubble, the encapsulation inefficacy appears easily.

On the other hand, in order to improve the light efficiency of the flip-chip LED chip, current expansion strips are often manufactured on the surface of the LED chip, and the current expansion strips are also connected with the semiconductor layer through holes; the above-described unevenness is further increased, resulting in poor packaging.

Disclosure of Invention

The invention aims to provide a flip LED chip which is firm in welding, easy to package and high in reliability.

Correspondingly, the invention also provides a preparation method of the flip LED chip.

In order to solve the above technical problem, the present invention provides a flip LED chip, including:

a flip-chip LED chip body comprising a first electrode and a second electrode;

the passivation protective layer is arranged on the flip LED chip body; and

the first bonding pad and the second bonding pad are arranged on the passivation protective layer, the first bonding pad is connected with the first electrode, and the second bonding pad is connected with the second electrode;

and the passivation protective layer is provided with an exhaust groove, and the exhaust groove is arranged around the first electrode and/or the second electrode.

As an improvement of the technical scheme, the distance between the exhaust groove and the first electrode/the second electrode is 5-10 μm.

As an improvement of the technical scheme, the depth of the exhaust groove is 0.8-1.6 mu m.

As an improvement of the technical scheme, the cross section of the exhaust groove is square, conical, elliptical or semicircular.

As an improvement of the above technical solution, the flip LED chip body includes:

a substrate;

the epitaxial layer is arranged on the substrate and sequentially comprises a first semiconductor layer, a light emitting layer and a second semiconductor layer;

a transparent conductive layer disposed on the second semiconductor layer;

the composite reflecting layer is arranged on the transparent conducting layer;

a first electrode and a second electrode;

the first electrode is connected with the first semiconductor layer through a plurality of first holes which are formed in the epitaxial layer and penetrate through the first semiconductor layer; the second electrode is connected with the transparent conductive layer through a plurality of second holes penetrating through the composite reflection layer.

As an improvement of the above technical solution, the flip-chip LED chip body further includes a current blocking layer, a first current spreading bar, and a second current spreading bar;

the first current expansion strip is connected with the first electrode and is connected with the first semiconductor layer through a third hole formed in the epitaxial layer;

the second current expansion strip is connected with the second electrode and is connected with the transparent conductive layer through a fourth hole formed in the composite reflection layer;

the current blocking layer is arranged between the transparent conducting layer and the second semiconductor layer.

As an improvement of the technical scheme, the width of the first hole and the width of the second hole are 3-10 mu m.

As an improvement of the technical scheme, the first hole and the third hole are arranged close to the edge of the epitaxial layer, and the second hole and the fourth hole are arranged close to the edge of the composite reflection layer.

Correspondingly, the invention also provides a preparation method of the flip LED chip, which comprises the following steps:

(1) preparing a flip LED chip body;

(2) forming a passivation protective layer on the surface of the LED chip body;

(3) photoetching the passivation protective layer to form an exhaust groove;

(4) forming a first pad and a second pad on the passivation protection layer; and obtaining the finished product of the flip LED chip.

As an improvement of the above technical solution, the method for manufacturing the flip-chip LED chip body includes:

(1) providing a substrate;

(2) forming an epitaxial layer on the substrate; the epitaxial layer comprises a first semiconductor layer, a light emitting layer and a second semiconductor layer;

(3) photoetching the epitaxial layer to form a plurality of first holes, wherein the first holes penetrate through the first semiconductor layer;

(4) forming a transparent conductive layer on the epitaxial layer;

(5) forming a composite reflective layer on the transparent conductive layer;

(6) photoetching the composite reflecting layer to form a plurality of second holes;

(7) forming a first electrode and a second electrode to obtain a flip LED chip body; the first electrode is connected with the first semiconductor through the first hole, and the second electrode is connected with the transparent conducting layer through the second hole.

The implementation of the invention has the following beneficial effects:

the invention designs the exhaust groove around the electrode of the flip LED chip, which can easily exhaust the bubbles sealed in the concave hole of the electrode, and improves the contact between the electrode and the bonding pad, thereby increasing the reliability of the LED. Meanwhile, the flip LED chip is provided with the current expansion strips, so that the uniform distribution of current is promoted, and the lighting effect is improved.

Drawings

FIG. 1 is a schematic diagram of a flip-chip LED chip according to an embodiment of the present invention;

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

FIG. 3 is a cross-sectional view taken along line B-B of FIG. 1;

FIG. 4 is a schematic structural diagram of a flip-chip LED chip body according to an embodiment of the present invention;

FIG. 5 is a cross-sectional view taken along line A-A of FIG. 4;

FIG. 6 is a cross-sectional view taken along line B-B of FIG. 4;

FIG. 7 is a flow chart of a method for fabricating a flip-chip LED chip according to the present invention;

FIG. 8 is a flow chart of a method of manufacturing a flip LED chip body according to the present invention;

fig. 9 is a schematic structural diagram of the LED chip after the flip LED chip body preparation step S3;

FIG. 10 is a cross-sectional view taken along line A-A of FIG. 9;

fig. 11 is a cross-sectional view taken along the line B-B in fig. 9.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings. It is only noted that the invention is intended to be limited to the specific forms set forth herein, including any reference to the drawings, as well as any other specific forms of embodiments of the invention.

Referring to fig. 1, 2 and 3, the present invention provides a flip LED chip comprising a flip LED chip body 1 including a first electrode 11 and a second electrode 12; the surface of the flip chip body 1 is provided with a passivation protective layer 2, and a first bonding pad 3 and a second bonding pad 4 are arranged on the passivation protective layer 2; the first pad 3 and the second pad 4 are electrically connected to the first electrode 3 and the second electrode 4 in the flip LED chip body through a hole 21/22 provided in the passivation protective layer 2. In this case, an air vent groove 23 is provided on the passivation layer 2, which is arranged around the first electrode 11 and/or the second electrode 12. The air vent groove 23 enables air bubbles enclosed in the concave hole of the electrode to be easily discharged, improving the contact of the electrode with the pad, thereby increasing the reliability of the LED.

Wherein, the distance between the exhaust groove 23 and the first electrode 11/the second electrode 12 is 5-10 μm; specifically, it may be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, but is not limited thereto. Preferably, the distance is 7 to 10 μm.

Specifically, the depth of the exhaust groove 23 is 0.8-1.6 μm; when the depth of the exhaust groove 23 is less than 0.8 μm, the exhaust function is difficult to be achieved, and simultaneously, the voltage of the LED chip is increased, and the luminous efficiency is reduced. When the depth is larger than 1.6 μm, the voltage of the LED chip is increased, resulting in reduced light efficiency.

Specifically, the shape of the exhaust groove 23 in the length direction thereof is a straight line, a spiral line, an arc line, an elliptical line, or the like; preferably, in the present embodiment, the vent groove 23 is a straight line, which is easy to process. Specifically, the cross section of the exhaust groove 23 is square, conical, elliptical or semicircular; preferably, it is square.

Specifically, referring to fig. 4 to 6, in the present embodiment, the flip LED chip body 1 includes a substrate 13, an epitaxial layer 14, a transparent conductive layer 15, a composite reflective layer 16, a first electrode 11, and a second electrode 12, which are sequentially disposed on the substrate 13. The epitaxial layer 14 includes a first semiconductor layer 141, a light emitting layer 142, and a second semiconductor layer 143. The first electrode 11 is electrically connected to the first semiconductor layer 141 through a plurality of first holes 144 formed in the epitaxial layer 14 and penetrating through the first semiconductor layer 141; the second electrode 12 is electrically connected to the transparent conductive layer 15 through a second hole 161 formed in the composite reflective layer 16.

Specifically, in the present embodiment, the first electrode 11 is electrically connected to the first semiconductor layer through 2 first holes 144; the smaller number of first holes 144 reduces the roughness of the surface of the first electrode 11 and reduces the accumulation of gas during the welding process. Further, the first holes 144 are disposed near the edge of the epitaxial layer 14 to facilitate the venting of gases that accumulate during the soldering process. It should be noted that reducing the number of the first holes 144 also weakens the ohmic contact between the first electrode 11 and the first semiconductor layer 141, and reduces the light efficiency, in order to solve this problem, the width of the first holes 144 is set to be 3 to 10 μm, preferably 5 to 10 μm (the common holes are 2 to 8 μm).

Specifically, in the present embodiment, the second electrode 12 is electrically connected to the transparent conductive layer 15, that is, the second semiconductor layer 143, through the 2 second holes 161. The smaller number of second holes 161 reduces unevenness of the surface of the second electrode 12, and reduces accumulation of gas during welding. Further, the second hole 161 is provided near the edge of the composite reflective layer 16, so that gas accumulated during the welding process is easily discharged. It should be noted that reducing the number of the second holes 161 also weakens the ohmic contact between the second electrode 12 and the second semiconductor layer 143, and reduces the light efficiency, in order to solve this problem, the width of the second holes 161 is set to be 3-10 μm, preferably 5-10 μm (the common holes are 2-8 μm).

Further, in order to improve the luminous efficiency of the LED chip, a current blocking layer 17, a first current spreading bar 18 and a second current spreading bar 19 are further provided. The first current spreading bar 18 is connected to the first electrode 11 and electrically connected to the first semiconductor layer 141 through a third hole 145 disposed in the epitaxial layer 14; it can promote the current evenly distributed, promotes the light efficiency. The second current spreading bar 19 is connected to the second electrode 12 and is electrically connected to the transparent conductive layer 15 through a fourth hole 162 disposed on the composite reflective layer 16. Specifically, in the present embodiment, the LED chip structure includes 1 first current spreading bar and 1 second current spreading bar, but is not limited thereto.

Specifically, the current blocking layer 1 is disposed between the transparent conductive layer 15 and the second semiconductor layer 143, and corresponds to the positions of the second electrode 12 and the second current spreading bar 19, which can further promote uniform diffusion of current and improve the luminous efficiency of the LED chip.

Correspondingly, referring to fig. 7, the invention also discloses a preparation method of the flip LED chip, which comprises the following steps:

s100: preparing a flip LED chip body;

s200: forming a passivation protective layer on the surface of the LED chip body;

s300: photoetching the passivation protective layer to form an exhaust groove;

specifically, firstly, patterning a passivation protective layer by adopting a yellow light process; and then etching by adopting a dry etching process or a wet etching process to obtain the exhaust groove.

S400: forming a first pad and a second pad on the passivation protection layer; and obtaining the finished product of the flip LED chip.

The material of the first bonding pad and the second bonding pad is AuSn, but not limited thereto.

Referring to fig. 8, the invention also discloses a method for manufacturing a flip-chip LED chip body, which includes:

s1: providing a substrate;

wherein, the substrate is sapphire, SiC or spinel, but not limited thereto;

s2: forming an epitaxial layer on a substrate;

the epitaxial layer comprises a first semiconductor layer, a light emitting layer and a second semiconductor layer; specifically, the epitaxial layer is a GaN-based semiconductor layer, i.e., the first semiconductor layer 141 is an N-GaN layer, and the second semiconductor layer 143 is a P-GaN layer; but is not limited thereto.

S3: photoetching the epitaxial layer to form a plurality of first holes;

preferably, the step further comprises forming a third hole at the same time as the first hole.

Specifically, see fig. 9 to 11; forming a plurality of uniformly distributed first holes 144 and third holes 145 on the epitaxial layer by a photolithography etching process; the first hole 144 and the second hole 145 penetrate to the first semiconductor layer 141. The first apertures 144 and the second apertures 145 are positioned as close to the edge of the epitaxial layer 14 as possible to allow easy venting of gases that accumulate during soldering.

Specifically, in the present embodiment, 2 first holes 144 with a width of 3 to 10 μm are formed in the epitaxial layer 14. The first hole can not only realize good ohmic contact between the first electrode 11 and the first semiconductor layer 141, but also reduce the surface unevenness of the first electrode caused by deep etching to a certain extent.

S4: forming a transparent conductive layer on the epitaxial layer;

specifically, a transparent conducting layer is formed on the epitaxial layer, and then photoetching is carried out on the transparent conducting layer to expose the first holes; and removing the transparent conductive layer on the side wall and the bottom of the first hole.

The transparent conductive layer 15 may be an ITO layer, an AZO layer, a GZO layer, or the like, but is not limited thereto. Preferably, in the embodiment, the transparent conductive layer 15 is an ITO layer, which has high light transmittance and can effectively reduce light loss; and the ITO layer has small resistance, thereby being beneficial to current expansion, preventing current congestion and improving quantum efficiency.

S5: forming a composite reflective layer on the transparent conductive layer;

the composite emitting layer 16 is a DBR layer, but is not limited thereto.

S6: photoetching the composite reflecting layer to form a plurality of second holes;

preferably, the step further comprises forming a fourth hole at the same time as forming the second hole.

Specifically, a plurality of second holes 161 and fourth holes 162 which are uniformly distributed are formed on the composite reflective layer through a photoetching process; the third hole 161 and the fourth hole 162 penetrate to the transparent conductive layer 15. The third and fourth holes 161 and 162 are disposed as close to the edge of the composite reflective layer 16 as possible, so that gas accumulated during the soldering process is easily discharged.

S7: forming a first electrode and a second electrode to obtain a flip LED chip body;

specifically, the first electrode 11 and the second electrode 12 are formed by electron beam evaporation, thermal evaporation, or magnetron sputtering.

Specifically, in the present invention, the first electrode 11 and the second electrode 12 sequentially include a first Cr layer, a first Al layer, a second Cr layer, a second Al layer, a Ti layer, and a Pt layer. The first electrodes of the above-described structure can be connected through the third aperture 19. The first electrode 11 with the structure can still keep good ohmic contact with the first semiconductor layer on the contact of the pinhole contact, and ensures the excellent performance of the LED chip.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.