阅读说明：本技术 一种反向稳压led芯片及其制备方法 (reverse voltage-stabilizing LED chip and preparation method thereof ) 是由 王硕 庄家铭 崔永进 于 2019-09-25 设计创作，主要内容包括：本发明公开了一种反向稳压LED芯片,其包括：衬底、外延层、第一刻蚀道、第一发光结构和至少一个第二发光结构；所述外延层设于所述衬底上,并通过刻蚀至所述衬底的第一刻蚀道分为第一区域与第二区域；所述第一发光结构设于所述第一区域；所述第二发光结构设于所述第二区域；所述第一发光结构和第二发光结构相互串联；且所述第一发光结构和第二发光结构电流传输方向相反。本发明通过将多个第二发光结构相互串联,可将反向击穿电压提高至3n V(其中,n为第二发光结构的个数),大幅提升了有反向电流存在时,LED芯片的安全性、可靠性,使得本发明中的LED芯片可应用于多种不同的使用场合。(the invention discloses a reverse voltage stabilization LED chip, which comprises: the LED chip comprises a substrate, an epitaxial layer, a first etching channel, a first light emitting structure and at least one second light emitting structure; the epitaxial layer is arranged on the substrate and is divided into a first area and a second area through a first etching channel etched to the substrate; the first light-emitting structure is arranged in the first area; the second light-emitting structure is arranged in the second area; the first light-emitting structure and the second light-emitting structure are connected in series; and the current transmission directions of the first light-emitting structure and the second light-emitting structure are opposite. According to the invention, the plurality of second light-emitting structures are connected in series, so that the reverse breakdown voltage can be increased to 3n V (wherein n is the number of the second light-emitting structures), and the safety and reliability of the LED chip in the presence of reverse current are greatly improved, so that the LED chip can be applied to various different use occasions.)

1. a reverse voltage stabilization LED chip, comprising: the LED chip comprises a substrate, an epitaxial layer, a first etching channel, a first light emitting structure and at least one second light emitting structure; the epitaxial layer is arranged on the substrate and is divided into a first area and a second area through a first etching channel etched to the substrate;

The first light-emitting structure is arranged in the first area; the second light-emitting structure is arranged in the second area; the first light-emitting structure and the second light-emitting structure are connected in series; and the current transmission directions of the first light-emitting structure and the second light-emitting structure are opposite.

2. The reverse stabilized LED chip of claim 1, further comprising a first secondary electrode and a second secondary electrode;

The first light emitting structure includes a first electrode and a second electrode, and the second light emitting structure includes a third electrode and a fourth electrode;

The first electrode and the fourth electrode are electrically connected through the second secondary electrode crossing the first etching track;

The second electrode and the third electrode are electrically connected by the first secondary electrode crossing the first etching lane.

3. the reverse voltage-stabilized LED chip according to claim 1 or 2, wherein the second region is further provided with a second etching track and a third secondary electrode; the second etching channel is etched to the substrate;

and adjacent second light-emitting structures are separated by the second etching channel and are electrically connected through the third secondary electrode.

4. the reverse stabilized LED chip of claim 1, wherein the area of said first region is: the area of the second region is (2-5): (0.5 to 1.5).

5. the reverse voltage stabilization LED chip of claim 1, wherein the second region is provided with 2-8 second light emitting structures and 1-7 second etching tracks.

6. The reverse stabilized LED chip of claim 1, wherein the first etched street and the second etched street have sloped sidewalls.

7. The LED chip of claim 6, wherein the angle of inclination is less than or equal to 60 degrees.

8. the reverse voltage stabilization LED chip of claim 1, wherein the first and second light emitting structures further comprise a current blocking layer, a current spreading layer, and a passivation layer.

9. the reverse voltage stabilization LED chip of claim 1, wherein the first and second light emitting structures are arranged in parallel.

10. the method of preparing a reverse stabilized LED chip according to any of claims 1 to 9, comprising:

(1) providing a substrate, and forming an epitaxial layer on the substrate;

(2) Forming a first exposed area and a second exposed area on the epitaxial layer;

(3) forming a first etching channel;

(4) Forming a first light emitting structure and a second light emitting structure;

(5) connecting the first and second light emitting structures in series with each other; and obtaining a reverse voltage-stabilizing LED chip finished product.

Technical Field

The invention relates to the technical field of light emitting diodes, in particular to a reverse voltage-stabilizing LED chip and a preparation method thereof.

background

An LED, also called a light emitting diode, is one type of semiconductor diode, which has unidirectional conductivity. When the reverse voltage applied to the LED chip does not exceed a certain range, the current passing through the diode is reverse current formed by the drift motion of minority carriers, the reverse current is very small, and the diode is in a cut-off state. This reverse current is also known as reverse saturation current or leakage current. However, when the applied reverse voltage exceeds a certain value, the reverse current suddenly increases, and this phenomenon is called electrical breakdown. The critical voltage causing electrical breakdown is called the diode reverse breakdown voltage. The diode loses one-way conductivity during electric breakdown, if the diode is not overheated due to electric breakdown, the one-way conductivity is not necessarily permanently destroyed, and after the external voltage is removed, the performance of the diode can still be restored, otherwise, the diode completely loses one-way conductivity and is permanently damaged. Therefore, the reverse voltage applied by the diode is prevented from being too high when the diode is used.

since a reverse voltage situation is rarely occurred in the existing usage, the existing LED chip is not designed with a reverse protection circuit. One occasion where reverse current often appears is when testing whether the chip leaks electricity, because the LED chip leaks electricity and can't be distinguished through the forward applied voltage, so adopt the method of the reverse applied voltage to test; however, in this test scenario, since the forward voltage of the LED is usually less than 4V, the reverse test voltage is only slightly larger than the forward voltage, so the industry provides a 5V voltage, but this 5V voltage is by no means the reverse breakdown voltage. Therefore, it is far from proving that the safety is not enough to meet the condition that the LED chip does not leak electricity under the reverse voltage of 5V, so that the existing LED chip can not be applied to the use occasions with larger reverse current and the safety is lower.

disclosure of Invention

the technical problem to be solved by the invention is to provide a reverse voltage-stabilizing LED chip, which has high reverse breakdown voltage, can effectively prevent reverse current from damaging the LED chip, and improves the reliability of the LED chip.

the technical problem to be solved by the present invention is to provide a method for manufacturing a reverse voltage stabilization LED chip.

in order to solve the above technical problem, the present invention provides a reverse voltage stabilization LED chip, which includes: the LED chip comprises a substrate, an epitaxial layer, a first etching channel, a first light emitting structure and at least one second light emitting structure; the epitaxial layer is arranged on the substrate and is divided into a first area and a second area through a first etching channel etched to the substrate;

the first light-emitting structure is arranged in the first area; the second light-emitting structure is arranged in the second area; the first light-emitting structure and the second light-emitting structure are connected in series; and the current transmission directions of the first light-emitting structure and the second light-emitting structure are opposite.

As an improvement of the above technical solution, the device further comprises a first secondary electrode and a second secondary electrode;

the first light emitting structure includes a first electrode and a second electrode, and the second light emitting structure includes a third electrode and a fourth electrode;

the first electrode and the fourth electrode are electrically connected through the second secondary electrode crossing the first etching track;

the second electrode and the third electrode are electrically connected by the first secondary electrode crossing the first etching lane.

As an improvement of the above technical solution, the second region is further provided with a second etching channel and a third secondary electrode; the second etching channel is etched to the substrate;

and adjacent second light-emitting structures are separated by the second etching channel and are electrically connected through the third secondary electrode.

as an improvement of the above technical solution, an area of the first region: the area of the second region is (2-5): (0.5 to 1.5).

As an improvement of the technical scheme, the second area is provided with 2-8 second light-emitting structures and 1-7 second etching channels.

As an improvement of the above technical solution, the sidewalls of the first etching channel and the second etching channel have an inclination angle.

As an improvement of the technical scheme, the inclination angle is less than or equal to 60 degrees.

As an improvement of the above technical solution, the first light emitting structure and the second light emitting structure further include a current blocking layer, a current diffusion layer, and a passivation layer.

As an improvement of the above technical solution, the first light emitting structure and the second light emitting structure are arranged in parallel.

correspondingly, the invention also discloses a preparation method of the reverse voltage stabilization LED chip, which comprises the following steps:

(1) providing a substrate, and forming an epitaxial layer on the substrate;

(2) forming a first exposed area and a second exposed area on the epitaxial layer;

(3) Forming a first etching channel;

(4) Forming a first light emitting structure and a second light emitting structure;

(5) Connecting the first and second light emitting structures in series with each other; and obtaining a reverse voltage-stabilizing LED chip finished product.

the implementation of the invention has the following beneficial effects:

The LED chip of the invention designs two light-emitting structures with opposite current transmission directions on the surface of the substrate, namely a first light-emitting structure and a second light-emitting structure; the second light-emitting structures are connected in series, reverse breakdown voltage can be increased to 3nV (wherein n is the number of the second light-emitting structures), safety and reliability of the LED chip are greatly improved when reverse current exists, and the LED chip can be applied to various different use occasions.

drawings

Fig. 1 is a schematic structural diagram of an inverse voltage-stabilizing LED chip according to an embodiment of the present invention;

3 FIG. 32 3 is 3 a 3 cross 3- 3 sectional 3 view 3 taken 3 along 3 line 3 A 3- 3 A 3 of 3 FIG. 31 3; 3

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

FIG. 4 is a cross-sectional view taken along line C-C of FIG. 1;

FIG. 5 is a schematic structural diagram of an LED chip with reverse voltage regulation according to another embodiment of the present invention;

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

FIG. 7 is a sectional view taken in the direction B-B in FIG. 5;

FIG. 8 is a cross-sectional view taken in the direction of C-C in FIG. 5;

fig. 9 is a flow chart of a method for manufacturing a reverse voltage stabilization LED chip according to the present invention.

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 to 4, the present embodiment provides a reverse voltage stabilization LED chip, which includes: the light emitting device comprises a substrate 1, an epitaxial layer 2, a first etching track 3, a first light emitting structure 4 and at least one second light emitting structure 5. Wherein, the epitaxial layer 2 is arranged on the substrate 1, and the first etching path 3 is arranged on the epitaxial layer 2; the epitaxial layer 2 is divided into a first region 21 and a second region 22 by a first etching track 3 etched to the substrate 1. The first light emitting structure 4 is disposed in the first region 21, and the second light emitting structure 5 is disposed in the second region 22. The first light emitting structure 4 and the second light emitting structure 5 are connected in series; and the current transmission directions of the two are opposite. The LED chip is provided with two light-emitting structures, the current transmission directions of the two light-emitting structures are opposite, namely, an additional protection circuit is added in the LED chip structure, so that the chip damage caused by reverse voltage is avoided.

specifically, referring to fig. 2, the epitaxial layer 2 includes, from bottom to top, a first semiconductor layer 23, an active layer 24, and a second semiconductor layer 25 in sequence; the specific type of the epitaxial layer is not particularly limited, and those skilled in the art can select the epitaxial layer according to the specific type of the LED chip. Specifically, in the present embodiment, the epitaxial layer 2 is a GaN type semiconductor layer, the first semiconductor layer 23 is an N-GaN layer, and the second semiconductor layer is a P-GaN layer.

Specifically, referring to fig. 2 and 3, in the present embodiment, the first light emitting structure 4 includes a first electrode 41 and a second electrode 43, wherein the first electrode 41 is connected to the first semiconductor layer 23, and the second electrode 43 is connected to the second semiconductor layer 24. The second light emitting structure 5 includes a third electrode 51 and a fourth electrode 52, the third electrode 51 is connected to the first semiconductor layer 23, and the fourth electrode 52 is connected to the second semiconductor layer 24. The first light emitting structure 4 and the second light emitting structure 5 are separated by a first etching track 3 etched to the substrate 1; so that the first electrode 41 is insulated from the third electrode 51 and the second electrode 42 is insulated from the fourth electrode 52 on the epitaxial layer 2.

in particular, see fig. 1, 3, 4; in this embodiment, a first secondary electrode 6 and a second secondary electrode 7 are also included. Wherein the first secondary electrode 6 crosses over the first etching track 3 and connects the first electrode 41 and the fourth electrode 52; the second sub-electrode 7 crosses the first etching lane 3 and connects the second electrode 42 and the third electrode 51; the first light emitting structure 4 and the second light emitting structure 5 are connected in series with each other by the connection of the first secondary electrode 6 and the second secondary electrode 7; and the current transmission directions of the two are opposite.

specifically, in the invention, n second light-emitting structures 5 are arranged on the surface of the LED chip, specifically, n is more than or equal to 2 and less than or equal to 8; the reverse breakdown voltage of the LED chip may be increased to 3n V by the n second light emitting structures. Preferably, 2. ltoreq. n.ltoreq.5; more preferably, n is 3. The number of the second light emitting structures 5 is not particularly limited, and those skilled in the art can select the second light emitting structure according to specific application.

Specifically, referring to fig. 2, in the present embodiment, 2 second light emitting structures 5 are disposed on the surface of the LED chip; the second light emitting structures 5 are passed through second etching tracks 8 that penetrate the substrate 1 so that different second light emitting structures are not in conduction with each other on the epitaxial layer 2. Further, a third secondary electrode 9 is further disposed on the surface of the LED chip, and crosses over the second etching channel 8, and connects the third electrode 51 and the fourth electrode 52 of the adjacent second light emitting structures 5, so as to realize the mutual series connection of the adjacent second light emitting structures 5.

it should be noted that, although the reverse breakdown voltage of the LED chip can be increased by arranging the opposite light-emitting structures on the surface of the LED chip, the safety of the LED chip is improved. However, the reverse light-emitting structure also occupies the surface area of the LED chip, so that the light-emitting area is reduced, and the LED lighting effect is reduced. Therefore, in order to balance the light effect and the reverse voltage stabilization effect, the occupied areas of the two light emitting structures need to be controlled. Specifically, in the present invention, the area of the first region 21 is controlled: the area of the second region 22 is (2-5): (0.5 to 1.5); wherein the first region 21 is used to form the first light emitting structure 4, which is mainly used for emitting light in the forward conduction condition; the second region 22 is used to form a second light emitting structure 5, which is mainly used to boost the reverse breakdown voltage in the case of reverse conduction. The ratio of the first area to the second area is controlled, so that the brightness of the LED chip can be effectively improved. Preferably, the area of the first region: the area of the second region is (2-5): 1.

furthermore, in order to improve the brightness of the LED chip, the first light-emitting structure and the second light-emitting structure are arranged in parallel, so that the surface area of the LED chip is fully utilized.

further, in order to improve the brightness of the LED chip, the side walls of the first etching channel 3 and the second etching channel 8 are provided with an inclination angle, which can improve the side light emitting efficiency of the LED chip and improve the brightness. Specifically, the inclination angle is less than or equal to 60 degrees; preferably 30 to 50 degrees.

In addition, referring to fig. 4 to 8, in another embodiment of the present invention, in order to improve the overall performance of the LED chip, the first light emitting structure 4 and the second light emitting structure 5 further include a current blocking layer 43/53, a transparent conductive layer 44/54, and a passivation layer 45/55. The current blocking layer 43/53 is disposed between the first electrode 41, the third electrode 51 and the second semiconductor layer 25, which can effectively prevent current or breakdown and current crowding when the chip area is too large. The transparent conductive layers 44/54 are disposed between the second semiconductor layer 25, the current blocking layer 43/53, and the first and third electrodes 41 and 51, and may function to expand current distribution. The passivation layer 45/55 is disposed on the entire surface of the LED chip, and holes are formed in the first electrode, the second electrode, the third electrode, and the fourth electrode to expose the electrodes.

correspondingly, referring to fig. 9, the invention also discloses a method for manufacturing the reverse voltage-stabilizing LED chip, which includes the following steps:

s100: providing a substrate, and forming an epitaxial layer on the substrate;

Specifically, the substrate 1 may be made of sapphire, silicon carbide, or silicon, or may be made of other semiconductor materials, and preferably, a sapphire substrate is selected in the present invention.

Specifically, a first semiconductor layer 23, an active layer 24 and a second semiconductor layer 25 are sequentially formed on a substrate by a Metal Organic Chemical Vapor Deposition (MOCVD) method to obtain an epitaxial layer 2; but are not limited to, the above-described methods.

S200: forming a first exposed region and a second exposed region on the epitaxial layer;

Specifically, S200 includes:

s201: forming a first photoresist on the surface of the epitaxial layer;

The first photoresist can be a positive photoresist or a negative photoresist;

S202: exposing the first photoresist to form a first exposure area;

Specifically, the pattern on the original negative film is transferred to a photosensitive bottom plate through exposure and the light source, and then the photoresist on the exposed area or the unexposed area is removed.

Photoetching to form a first graph photoetching area, forming a first light-emitting structure exposed area and a second light-emitting structure exposed area, checking the positive and negative poles of the two light-emitting structures, and ensuring reverse arrangement;

S203: etching the first exposure area to form a first exposed area and a second exposed area;

The epitaxial layer may be etched by dry etching, which can well control the critical dimension and ensure the uniformity, but is not limited to the above etching process.

S204: and removing the first photoresist.

s300: forming a first etching channel;

Specifically, step S300 includes:

S301: forming a second photoresist on the surface of the epitaxial layer;

S302: exposing the second photoresist to form a second exposure area;

S303: etching the second exposed region;

specifically, the epitaxial layer may be etched by dry etching, which can form a well-controlled critical dimension and ensure uniformity, but is not limited to the above etching process.

Specifically, in order to improve the connection stability of the first light emitting structure 4 and the second light emitting structure 5, the side wall of the first etching channel 3 has a certain inclination angle, and the first etching channel 3 of the structure can also improve the side light emitting efficiency of the light emitting structure and improve the light emitting efficiency of the chip. Preferably, the inclination angle is less than or equal to 60 degrees, and when the inclination angle is too large, the metal film is difficult to form and is easy to break in the later secondary electrode evaporation process. Preferably, the inclination angle is 30-50 degrees, which can ensure that the electrode is not broken during evaporation, and simultaneously, the light-emitting efficiency of the chip is improved to a higher extent.

further, in order to ensure the connection stability between the first light emitting structure 4 and the second light emitting structure 5, the width of the first etching channel 3 is set to be 10-20 μm; the too narrow width of the deep etching channel can cause too large inclination angle and easy disconnection; the deep etching channel is too wide, so that the light-emitting area is reduced, and the light-emitting efficiency of the chip is reduced. Preferably, the width of the first etching channel 3 is set to be 12-18 μm; and more preferably 16 μm, the width of the first etching track 3 can ensure high light emitting efficiency of the LED chip, and ensure the connection stability between the first light emitting structure 4 and the second light emitting structure 5.

s304: and removing the second photoresist.

s400: forming a first light emitting structure and a second light emitting structure;

Specifically, S400 includes:

s410: forming a current blocking layer on the surface of the epitaxial layer;

specifically, S410 includes:

s411: depositing a current barrier layer;

specifically, silicon dioxide can be selected as a current blocking layer, and the current blocking layer has better light transmittance; but is not limited to, silicon dioxide.

S412: forming a third photoresist on the surface of the current blocking layer;

s413: exposing the third photoresist to form a third exposure area;

s414: etching the exposed area;

S415: removing the third photoresist; and obtaining a finished product of the current barrier layer.

specifically, when the current blocking layer is designed, a hole can be formed below the primary electrode to prevent the electrode from falling off due to silicon oxide, and the periphery of the current blocking layer is larger than 5um of the primary electrode, so that the current blocking effect can be achieved, and light transmission at other places can not be influenced;

s420: forming a transparent conductive layer;

specifically, S420 includes:

S421: depositing a transparent conductive layer;

specifically, indium tin oxide may be used as the transparent conductive layer, but is not limited thereto;

s422: forming a fourth photoresist on the surface of the transparent conducting layer;

S423: exposing the fourth photoresist to form a fourth exposure area;

s424: etching the exposed area;

Specifically, the transparent conductive layer is etched by wet etching. Specifically, the transparent conducting layer is etched by adopting a mixed solution of ferric chloride and hydrochloric acid, the etching time is 150-220s, and at the moment, the etching time can not only fully etch the current diffusion layer, but also can ensure that the whole thickness of the ITO layer is not greatly reduced and the current expansibility of the chip is influenced.

S425: and removing the fourth photoresist to form the transparent conductive layer.

Specifically, when the transparent conducting layer is designed, the transparent conducting layer is set to shrink inwards by at least 2 micrometers according to the specific width of the second semiconductor layer; therefore, the LED chip can not only play a role in current diffusion, but also prevent the transparent conducting layer from contacting the side wall to cause electric leakage of the LED chip;

s430: forming a first electrode, a second electrode, a third electrode and a fourth electrode;

Specifically, S430 includes:

S431: forming a fifth photoresist on the surface of the epitaxial layer;

S432: exposing the fifth photoresist to form a fifth exposure area;

s433: performing primary electrode evaporation on the fifth exposure area;

the evaporation of the primary electrode is performed by electron beam evaporation, thermal evaporation or magnetron sputtering, but not limited thereto.

S444: and tearing gold and removing the fifth photoresist to obtain a first electrode, a second electrode, a third electrode and a fourth electrode.

s450: forming a passivation layer;

specifically, S450 includes:

S451: depositing a passivation layer;

specifically, Metal Organic Chemical Vapor Deposition (MOCVD) is used for passivation layer deposition. The passivation layer is made of silicon dioxide or silicon nitride, but is not limited thereto, and silicon dioxide is preferred. The thickness of the passivation layer is 80-500nm, preferably 100-300 nm.

s452: forming a sixth photoresist;

S453: exposing the sixth photoresist to form a sixth exposure area;

specifically, the sixth exposure region needs to make an area smaller than 5um of the primary electrode region above the primary electrode region for etching the passivation layer.

S454: etching the sixth exposed area;

Specifically, wet etching is adopted for etching, and specifically, a solution of ammonium fluoride and hydrofluoric acid in a ratio of 15 to 1 can be selected for etching to ensure that the etching reaches the surface of the primary electrode; to form openings for the primary electrodes.

s455: removing the sixth photoresist; and forming a passivation layer.

S500: connecting the first light emitting structure and the second light emitting structure in series; and obtaining a reverse voltage-stabilizing LED chip finished product.

specifically, S500 includes:

S501: forming a seventh photoresist;

s502: exposing the seventh photoresist to form a seventh exposure area;

s503: evaporating the seventh exposure area;

wherein, the secondary electrode is evaporated by adopting an electron beam evaporation, thermal evaporation or magnetron sputtering process. Referring to fig. 4 and 8, a first secondary electrode 6, a second secondary electrode 7 and a third secondary electrode 9 are evaporated; so that the first and second light emitting structures are connected in series and the adjacent second light emitting structures are connected in series.

S504: and tearing gold and removing the seventh photoresist to form a first secondary electrode, a second secondary electrode and a third secondary electrode finished product, thereby obtaining a reverse voltage-stabilizing LED chip finished product.

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.