Flip LED chip

Abstract

The invention discloses a flip LED chip, and relates to the technical field of semiconductors, the flip LED chip comprises a substrate and a chip main body structure, the chip main body structure comprises a light-emitting structure, an insulation protection layer and an electrode bonding pad, the light-emitting structure is arranged on the substrate, the insulation protection layer is arranged on the surface of the light-emitting structure, the lower end of the electrode bonding pad is embedded in the light-emitting structure, and the insulation protection layer is arranged on the surface of the electrode bonding pad. The upper end is exposed out of the insulating protection layer; the light-emitting structure comprises an epitaxial structure, a metal electrode, an insulating transparent heat-conducting part and a reflecting layer, the insulating transparent heat-conducting part is embedded between the epitaxial structure and the reflecting layer, the metal electrode is embedded in the insulating transparent heat-conducting part, and the lower end of the electrode bonding pad penetrates through the reflecting layer to be connected with the metal electrode and the insulating transparent heat-conducting part. According to the flip LED chip, the periphery of the metal electrode is wrapped with the insulating transparent heat conduction part to be connected with the epitaxial structure and the electrode bonding pad, so that the heat conduction efficiency between the epitaxial structure and the electrode bonding pad can be effectively improved, and heat dissipation in the flip LED chip is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a flip-chip LED chip. Background Art

[0002] Currently, in existing flip-chip LED chips, heat generated by the epitaxial structure is primarily conducted through the metal electrodes to the electrode pads, and then through the electrode pads to the outside of the chip. Although the metal electrodes have good thermal conductivity, the contact area between the metal electrodes, the epitaxial structure, and the electrode pads is relatively limited. This undoubtedly limits the efficiency of heat conduction between the epitaxial structure and the electrode pads, hindering heat dissipation within the flip-chip LED chip. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art. The present invention provides a flip-chip LED chip. By wrapping an insulating transparent heat-conducting part around the metal electrode to connect the epitaxial structure and the electrode pad, the heat conduction efficiency between the epitaxial structure and the electrode pad can be effectively improved, which is beneficial to the heat dissipation inside the flip-chip LED chip.

[0004] The present invention provides a flip-chip LED chip, comprising a substrate and a chip main body structure disposed on the substrate, wherein the chip main body structure comprises a light-emitting structure, an insulating protective layer, and an electrode pad; the light-emitting structure is disposed on the substrate, the insulating protective layer is disposed on the surface of the light-emitting structure, the lower end of the electrode pad is embedded in the light-emitting structure, and the upper end of the electrode pad is exposed outside the insulating protective layer;

[0005] The light-emitting structure includes an epitaxial structure arranged on the substrate, and a metal electrode, an insulating transparent heat-conducting portion and a reflective layer arranged on the epitaxial structure. The insulating transparent heat-conducting portion is embedded between the epitaxial structure and the reflective layer, the metal electrode is embedded in the insulating transparent heat-conducting portion, and the lower end of the electrode pad passes through the reflective layer to connect the metal electrode and the insulating transparent heat-conducting portion.

[0006] Specifically, the lower end of the electrode pad is embedded in the insulating transparent heat-conducting portion; or

[0007] The lower end of the electrode pad is connected to the upper surface of the insulating transparent heat-conducting part.

[0008] Specifically, the light-emitting structure further includes sidewall passivation walls arranged around the epitaxial structure, and an auxiliary electrode arranged on the sidewall passivation walls, and the insulating transparent heat-conducting portion wraps the auxiliary electrode.

[0009] Specifically, the metal electrode includes an N-type electrode and a P-type electrode; the electrode pad includes an N-type pad and a P-type pad; the insulating transparent thermal conductive portion includes a first insulating transparent thermal conductive block and a second insulating transparent thermal conductive block; the auxiliary electrode includes a first sub-electrode and a second sub-electrode, the first sub-electrode is located on a side close to the N-type electrode, and the second sub-electrode is located on a side close to the P-type electrode;

[0010] The epitaxial structure includes an N-type semiconductor layer, an MQW quantum well layer, and a P-type semiconductor layer sequentially stacked on the substrate; an N-type conductive opening is formed in the epitaxial structure, and the N-type conductive opening extends from the surface of the P-type semiconductor layer into the N-type semiconductor layer; a transparent conductive layer is formed on the P-type semiconductor layer, and the transparent conductive layer avoids the N-type conductive opening;

[0011] The N-type electrode is located in the N-type conductive opening, the bottom of the N-type electrode is connected to the N-type semiconductor layer, and the top of the N-type electrode is connected to the N-type pad; the P-type electrode is located on the transparent conductive layer, the bottom of the P-type electrode is connected to the transparent conductive layer, and the top of the P-type electrode is connected to the P-type pad;

[0012] The first insulating transparent thermally conductive block is embedded between the reflective layer and the N-type conductive opening, and the first insulating transparent thermally conductive block wraps the N-type electrode, the first sub-electrode and a portion of the N-type pad. The first insulating transparent thermally conductive block fills the N-type conductive opening, and the first insulating transparent thermally conductive block extends to all sides of the N-type conductive opening; the second insulating transparent thermally conductive block is embedded between the reflective layer and the transparent conductive layer, and the second insulating transparent thermally conductive block wraps the P-type electrode, the second sub-electrode and a portion of the P-type pad.

[0013] Specifically, the sidewall passivation wall is made of SiO2; or

[0014] The material of the sidewall passivation wall is GaN containing high-resistance dopant, the high-resistance dopant is F, C or Fe, and the concentration range of the high-resistance dopant is 10 18 ~10 20 atoms / cm3.

[0015] Specifically, the auxiliary electrode includes a Cr layer, an Al layer, a Ti layer, a Pt layer, an Au layer and a Ni layer stacked in sequence on the sidewall passivation wall, the thickness of the Cr layer is in the range of 2.5 to 25 nm, the thickness of the Al layer is in the range of 100 to 200 nm, the thickness of the Ti layer is in the range of 50 to 100 nm, the thickness of the Pt layer is in the range of 25 to 100 nm, the thickness of the Au layer is in the range of 100 to 500 nm, and the thickness of the Ni layer is 20 nm.

[0016] Specifically, the electrode pad includes an adhesion layer, a barrier layer, a welding layer and a test layer from bottom to top. The material of the adhesion layer is Cr, Ti, Pt or Ni, and the thickness range of the adhesion layer is 10 to 200 nm; the material of the barrier layer is one or more of Ti, Pt, and Ni, and the thickness range of the barrier layer is 50 to 300 nm; the material of the welding layer is one or more of Au, AuSn, Pb, and Sn, and the thickness range of the welding layer is 25 to 100 μm; the material of the test layer is one or more of Au, Ag, and Cu, and the thickness range of the test layer is 20 to 500 nm.

[0017] Specifically, the reflective layer is a distributed Bragg reflector, which is formed by stacking a pair of silicon dioxide film layers and aluminum oxide film layers; or

[0018] The reflective layer is composed of an Ag reflective mirror layer and an insulating oxide layer stacked in sequence, and the Ag reflective mirror layer directly contacts the epitaxial structure; the insulating transparent thermal conductive part is embedded between the epitaxial structure and the insulating oxide layer, and the lower end of the electrode pad passes through the insulating oxide layer to connect the metal electrode and the insulating transparent thermal conductive part.

[0019] Specifically, there are 15 to 20 pairs of silicon dioxide film layers and aluminum oxide film layers.

[0020] Specifically, the insulating transparent heat-conducting portion is a diamond-like carbon film, and the thickness of the diamond-like carbon film ranges from 500 to 1000 nm.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The flip-chip LED chip of the present invention has an insulating transparent heat-conducting portion wrapped around the metal electrode, and uses the insulating transparent heat-conducting portion to connect the electrode pad and the epitaxial structure, thereby widening the heat conduction path between the epitaxial structure and the electrode pad. The heat generated by the epitaxial structure can be conducted to the electrode pad not only through the metal electrode, but also through the insulating transparent heat-conducting portion, thereby effectively improving the heat conduction efficiency between the epitaxial structure and the electrode pad, which is beneficial to the heat dissipation inside the flip-chip LED chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is a schematic diagram of the first structure of a flip-chip LED chip according to an embodiment of the present invention;

[0025] Figure 2 2 is a schematic diagram of a second structure of a flip-chip LED chip according to an embodiment of the present invention;

[0026] Figure 3 3 is a schematic diagram of the third structure of the flip-chip LED chip in an embodiment of the present invention;

[0027] Figure 4 1 is a schematic diagram of the preparation process of a flip-chip LED chip according to an embodiment of the present invention;

[0028] Figure 5 Schematic diagram of the structure of the substrate and epitaxial layer in an embodiment of the present invention;

[0029] Figure 6 is a schematic structural diagram of an epitaxial structure in an embodiment of the present invention;

[0030] Figure 7 is a schematic structural diagram of a metal electrode in an embodiment of the present invention;

[0031] Figure 8 Schematic diagram of the structure of the sidewall passivation wall and the auxiliary electrode in an embodiment of the present invention;

[0032] Figure 9 2 is a schematic structural diagram of an insulating transparent heat-conducting portion according to an embodiment of the present invention;

[0033] Figure 10 is a schematic structural diagram of a reflective layer in an embodiment of the present invention;

[0034] Figure 11 1 is a schematic structural diagram of an insulating protective layer in an embodiment of the present invention;

[0035] Figure 12 Schematic diagram of the structure of the conductive through hole in an embodiment of the present invention.

[0036] In the accompanying drawings, 10, substrate; 20, chip main structure; 100, light-emitting structure; 110', epitaxial layer; 110, epitaxial structure; 111, N-type semiconductor layer; 112, MQW quantum well layer; 113, P-type semiconductor layer; 114, N-type conductive opening; 115, isolation trench; 120, metal electrode; 121, N-type electrode; 122, P-type electrode; 130, insulating transparent heat-conducting portion; 131, first insulating transparent Thermal conductive block; 132, second insulating transparent thermal conductive block; 140, reflective layer; 150, side wall passivation wall; 160, auxiliary electrode; 161, first sub-electrode; 170, transparent conductive layer; 200, insulating protective layer; 300, electrode pad; 301 adhesion layer; 302, barrier layer; 303, welding layer; 304, test layer; 310, N-type pad; 320, P-type pad; 410, N-type through hole; 420, P-type through hole. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0038] The present invention provides a flip-chip LED chip. Figure 1 FIG1 shows a first structural schematic diagram of a flip-chip LED chip in an embodiment of the present invention, wherein the flip-chip LED chip comprises a substrate 10 and a chip main body structure 20 disposed on the substrate 10, wherein the chip main body structure 20 comprises a light-emitting structure 100, an insulating protective layer 200, and an electrode pad 300, wherein the light-emitting structure 100 is disposed on the substrate 10, the insulating protective layer 200 is disposed on the surface of the light-emitting structure 100, the lower end of the electrode pad 300 is embedded in the light-emitting structure 100, and the upper end of the electrode pad 300 is exposed to the insulating layer 200. The light emitting structure 100 includes an epitaxial structure 110 arranged on the substrate 10, and a metal electrode 120, an insulating transparent heat-conducting portion 130 and a reflective layer 140 arranged on the epitaxial structure 110, the insulating transparent heat-conducting portion 130 is embedded between the epitaxial structure 110 and the reflective layer 140, the metal electrode 120 is embedded in the insulating transparent heat-conducting portion 130, and the lower end of the electrode pad 300 passes through the reflective layer 140 to connect the metal electrode 120 and the insulating transparent heat-conducting portion 130.

[0039] The flip-chip LED chip of the present invention has an insulating transparent heat-conducting portion 130 wrapped around the metal electrode 120, and uses the insulating transparent heat-conducting portion 130 to connect the electrode pad 300 and the epitaxial structure 110, thereby widening the heat conduction path between the epitaxial structure 110 and the electrode pad 300. This allows the heat generated by the epitaxial structure 110 to be conducted to the electrode pad 300 not only through the metal electrode 120, but also through the insulating transparent heat-conducting portion 130. This effectively improves the heat conduction efficiency between the epitaxial structure 110 and the electrode pad 300, which is beneficial to the heat dissipation inside the flip-chip LED chip.

[0040] Moreover, since the present invention improves the heat dissipation performance of the flip-chip LED chip, the reliability and light efficiency of the flip-chip LED chip are significantly optimized.

[0041] In some specific embodiments, see Figure 1 The lower end of the electrode pad 300 is embedded in the insulating transparent heat-conducting part 130, so that the contact area between the electrode pad 300 and the insulating transparent heat-conducting part 130 is larger, and the heat in the insulating transparent heat-conducting part 130 can be better transferred to the electrode pad 300.

[0042] Figure 2 A second structural schematic diagram of the flip-chip LED chip in an embodiment of the present invention is shown, in which the lower end of the electrode pad 300 is connected to the upper surface of the insulating transparent heat-conducting portion 130, so that there is no need to etch the insulating transparent heat-conducting portion 130, which is conducive to simplifying the preparation process.

[0043] Figure 3 A third schematic diagram of a flip-chip LED chip according to an embodiment of the present invention is shown. The light-emitting structure 100 further includes sidewall passivation walls 150 disposed around the epitaxial structure 110, and an auxiliary electrode 160 disposed on the sidewall passivation walls 150. The insulating, transparent, and thermally conductive portion 130 wraps around the auxiliary electrode 160. The sidewall passivation walls 150 enhance the impedance around the edges of the epitaxial structure 110, reducing leakage at the edges of the epitaxial structure 110 and thereby reducing heat generation caused by this leakage. Furthermore, the auxiliary electrode 160 and the insulating, transparent, and thermally conductive portion 130 cooperate to further conduct heat away from the sidewall passivation walls 150.

[0044] Moreover, based on the auxiliary electrode 160, the resistance between the auxiliary electrode 160 and the metal electrode 120 can be measured by a resistance meter, that is, the passivation resistance between the sidewall passivation wall 150 and the epitaxial structure 110 can be measured, so as to facilitate the judgment of whether the edge of the epitaxial structure 110 is leaking; if the passivation resistance between the sidewall passivation wall 150 and the epitaxial structure 110 is greater than 10,000 ohms, then there is no leakage risk at the edge of the epitaxial structure 110; if the passivation resistance between the sidewall passivation wall 150 and the epitaxial structure 110 is less than 10,000 ohms, then there is a leakage risk at the edge of the epitaxial structure 110.

[0045] In addition, based on the auxiliary electrode 160 , the offset of the photolithography overlay can be obtained by measuring the distance difference between the auxiliary electrode 160 and the two sides of the sidewall passivation wall 150 .

[0046] For details, please refer to Figure 3 The metal electrode 120 includes an N-type electrode 121 and a P-type electrode 122; the electrode pad 300 includes an N-type pad 310 and a P-type pad 320; the insulating transparent thermal conductive portion 130 includes a first insulating transparent thermal conductive block 131 and a second insulating transparent thermal conductive block 132; the auxiliary electrode 160 includes a first sub-electrode 161 and a second sub-electrode, the first sub-electrode 161 is located on a side close to the N-type electrode 121, and the second sub-electrode is located on a side close to the P-type electrode 122;

[0047] The epitaxial structure 110 includes an N-type semiconductor layer 111, an MQW quantum well layer 112, and a P-type semiconductor layer 113 sequentially stacked on the substrate 10. An N-type conductive opening 114 is formed in the epitaxial structure 110, and the N-type conductive opening 114 extends from the surface of the P-type semiconductor layer 113 into the N-type semiconductor layer 111. A transparent conductive layer 170 is formed on the P-type semiconductor layer 113, and the transparent conductive layer 170 avoids the N-type conductive opening 114.

[0048] The N-type electrode 121 is located in the N-type conductive opening 114 , with the bottom of the N-type electrode 121 connected to the N-type semiconductor layer 111 , and the top of the N-type electrode 121 connected to the N-type pad 310 ; the P-type electrode 122 is located on the transparent conductive layer 170 , with the bottom of the P-type electrode 122 connected to the transparent conductive layer 170 , and the top of the P-type electrode 122 connected to the P-type pad 320 ;

[0049] The first insulating transparent thermally conductive block 131 is embedded between the reflective layer 140 and the N-type conductive opening 114, and the first insulating transparent thermally conductive block 131 wraps the N-type electrode 121, the first sub-electrode 161 and a portion of the N-type pad 310. The first insulating transparent thermally conductive block 131 fills the N-type conductive opening 114 and extends to the four sides of the N-type conductive opening 114; the second insulating transparent thermally conductive block 132 is embedded between the reflective layer 140 and the transparent conductive layer 170, and the second insulating transparent thermally conductive block 132 wraps the P-type electrode 122, the second sub-electrode and a portion of the P-type pad 320.

[0050] The first insulating transparent thermally conductive block 131 wraps around the N-type electrode 121, the first sub-electrode 161, and a portion of the N-type pad 310, fills the N-type conductive opening 114, and extends around the N-type conductive opening 114, effectively transferring heat from the N-type electrode 121 and its surrounding area to the N-type pad 310. The second insulating transparent thermally conductive block 132 wraps around the P-type electrode 122, the second sub-electrode, and a portion of the P-type pad 320, effectively transferring heat from the P-type electrode 122 and its surrounding area to the P-type pad 320. The first insulating transparent thermally conductive block 131 and the second insulating transparent thermally conductive block 132 cooperate with each other to effectively transfer heat generated by the epitaxial structure 110 to the N-type pad 310 and the P-type pad 320, while preventing heat from accumulating at the bottom of the N-type electrode 121 and the bottom of the P-type electrode 122.

[0051] Optionally, the sidewall passivation wall 150 is made of SiO 2 , which has good insulation properties and can effectively enhance the impedance around the edges of the epitaxial structure 110 , reduce edge leakage of the epitaxial structure 110 , and thus reduce heat caused by leakage.

[0052] Optionally, the material of the sidewall passivation wall 150 is GaN containing a high-resistance dopant, the high-resistance dopant is F, C or Fe, and the concentration of the high-resistance dopant is 10 18 ~10 20 atoms / cm3, and also has good insulation properties, which can effectively enhance the impedance of the edges around the epitaxial structure 110, reduce the edge leakage of the epitaxial structure 110, and thus reduce the heat caused by leakage. Preferably, the high-resistance dopant is F, and the concentration of the high-resistance dopant is 10 19 atoms / cm3.

[0053] In some specific embodiments, the auxiliary electrode 160 includes a Cr layer, an Al layer, a Ti layer, a Pt layer, an Au layer and a Ni layer sequentially stacked on the sidewall passivation wall 150, the thickness of the Cr layer is in the range of 2.5 to 25 nm, the thickness of the Al layer is in the range of 100 to 200 nm, the thickness of the Ti layer is in the range of 50 to 100 nm, the thickness of the Pt layer is in the range of 25 to 100 nm, the thickness of the Au layer is in the range of 100 to 500 nm, and the thickness of the Ni layer is 20 nm.

[0054] The Cr layer (2.5-25 nm) has excellent adhesion and serves as an adhesion base layer to ensure a firm bond between the upper metal layer and the sidewall passivation wall 150 to prevent falling off; the Al layer (100-200 nm) has high conductivity and low cost, and the thick layer design can reduce the overall resistance and undertake most of the current transmission function; the Ti layer (50-100 nm) can prevent the mutual diffusion of the Al layer and the upper Pt metal layer, avoid the formation of unfavorable intermetallic compounds, and at the same time enhance the interlayer bonding force between the Al layer and the upper Pt metal layer, improving structural stability; the Pt layer (25-100 nm) is chemically inert and resistant to high-temperature oxidation, which can block the mutual diffusion of the lower metal layer (such as Ti) and the upper Au metal layer, and at the same time provide a stable conductive interface; the Au layer (100-500 nm) has excellent conductivity and oxidation resistance, ensuring that the electrode maintains low contact resistance during long-term use; the Ni layer (20 nm) provides mechanical wear resistance and protects the lower metal layer.

[0055] In some specific embodiments, see Figure 1 The electrode pad 300 includes an adhesion layer 301, a barrier layer 302, a welding layer 303 and a test layer 304 from bottom to top. The material of the adhesion layer 301 is Cr, Ti, Pt or Ni. The thickness of the adhesion layer 301 ranges from 10 to 200 nm, which is conducive to the strong bonding of the electrode pad 300 with the metal electrode 120, the insulating transparent thermal conductive part 130 and the reflective layer 140. The material of the barrier layer 302 is one or more of Ti, Pt and Ni. The thickness of the barrier layer 302 ranges from 50 to 30 0nm, which can prevent the welding layer 303 from diffusing toward the adhesion layer 301, thereby increasing the reliability of the electrode pad 300; the material of the welding layer 303 is one or more of Au, AuSn, Pb, and Sn, and the thickness of the welding layer 303 ranges from 25 to 100μm, which is convenient for effective welding of the flip-chip LED chip and the packaging substrate; the material of the test layer 304 is one or more of Au, Ag, and Cu, and the thickness of the test layer 304 ranges from 20 to 500nm, with low contact resistance, which is convenient for contact with the test probe.

[0056] For details, please refer to Figure 1The N-type pad 310 and the P-type pad 320 are of equal size, that is, the cross-sectional area and height of the N-type pad 310 and the P-type pad 320 are the same, which can balance the current density of the N-type region and the P-type region, which is beneficial to uniform current distribution; it also facilitates welding operations during packaging, is beneficial to achieving welding consistency, and improves production yield.

[0057] For further information, see Figure 1 The adhesion layer 301 contacts the insulating transparent heat-conducting part 130, the metal electrode 120 and the reflective layer 140, ensuring a firm bond between the electrode pad 300 and the metal electrode 120, the insulating transparent heat-conducting part 130 and the reflective layer 140; the barrier layer 302 partially protrudes out of the insulating protective layer 200, which can effectively prevent the welding layer 303 from diffusing into the insulating protective layer 200 during welding.

[0058] In some specific embodiments, the reflective layer 140 is a distributed Bragg reflector, which is composed of a stack of paired silicon dioxide film layers and aluminum oxide film layers, and can achieve high reflectivity through the difference in material refractive index and the multiple interference effect of light. The distributed Bragg reflector achieves high reflectivity by periodically alternating high refractive index (Al2O3, about 1.7 to 1.8) and low refractive index (SiO2, about 1.45) material layers, so that light of a specific wavelength (Bragg wavelength) undergoes constructive interference at the interface. Moreover, the thermal expansion coefficients of SiO2 and Al2O3 are well matched, which can reduce thermal stress and improve the stability of the chip in high temperature environments. In addition, SiO2 and Al2O3 are insulated to avoid short circuits with the electrode pad 300.

[0059] Specifically, the paired silicon dioxide and aluminum oxide layers are provided in 15 to 20 pairs to ensure high reflectivity of the distributed Bragg reflector. Optionally, the layers can be provided in 15, 16, 17, 18, 19, or 20 pairs.

[0060] In some specific embodiments, the reflective layer 140 is composed of a sequentially stacked Ag reflective mirror layer and an insulating oxide layer. The Ag reflective mirror layer directly contacts the epitaxial structure 110. The insulating transparent thermal conductive portion 130 is embedded between the epitaxial structure 110 and the insulating oxide layer. The lower end of the electrode pad 300 passes through the insulating oxide layer to connect the metal electrode 120 and the insulating transparent thermal conductive portion 130. The Ag reflective mirror layer can directly and efficiently reflect light. The insulating oxide layer can protect the Ag reflective mirror layer and also block the electrode pad 300 from the Ag reflective mirror layer.

[0061] In some specific embodiments, the insulating transparent heat-conducting portion 130 is a diamond-like carbon film, which has excellent insulation performance (resistivity up to 109 ~10 16 Ω·cm), transparency (light transmittance can reach 80% to 90%) and thermal conductivity (thermal conductivity coefficient is 100 to 2000W / (m·K)), which fully meets the needs of insulation, light transmission and thermal conductivity.

[0062] Specifically, the thickness of the diamond-like carbon film ranges from 500 to 1000 nm, which can provide sufficient lateral and longitudinal thermal diffusion capabilities while ensuring mechanical strength; a thickness above 500 nm can effectively suppress pinhole defects and ensure insulation reliability; and, within the thickness range of 500 to 1000 nm, its transparency is good.

[0063] The flip-chip LED chip of the present invention has an insulating transparent heat-conducting portion 130 wrapped around the metal electrode 120, and uses the insulating transparent heat-conducting portion 130 to connect the electrode pad 300 and the epitaxial structure 110, thereby widening the heat conduction path between the epitaxial structure 110 and the electrode pad 300. This allows the heat generated by the epitaxial structure 110 to be conducted to the electrode pad 300 not only through the metal electrode 120, but also through the insulating transparent heat-conducting portion 130. This effectively improves the heat conduction efficiency between the epitaxial structure 110 and the electrode pad 300, which is beneficial to the heat dissipation inside the flip-chip LED chip.

[0064] Furthermore, in the flip-chip LED chip of the present invention, the sidewall passivation wall can enhance the impedance around the edges of the epitaxial structure 110, reducing leakage at the edges of the epitaxial structure 110, thereby reducing heat generation caused by leakage. Furthermore, the auxiliary electrode 160 and the insulating transparent thermal conductive portion 130 cooperate to further conduct heat away from the sidewall passivation wall 150. Based on the auxiliary electrode 160, the resistance between the auxiliary electrode 160 and the metal electrode 120, i.e., the passivation resistance between the sidewall passivation wall 150 and the epitaxial structure 110, can be measured using a resistance meter to facilitate determining whether there is leakage at the edge of the epitaxial structure 110. If the passivation resistance between the sidewall passivation wall 150 and the epitaxial structure 110 is greater than 10,000 ohms, there is no risk of leakage at the edge of the epitaxial structure 110. If the passivation resistance between the sidewall passivation wall 150 and the epitaxial structure 110 is less than 10,000 ohms, there is a risk of leakage at the edge of the epitaxial structure 110. Based on the auxiliary electrode 160 , the offset of the photolithography overlay can be obtained by measuring the distance difference between the auxiliary electrode 160 and the two sides of the sidewall passivation wall 150 .

[0065] In addition, since the present invention improves the heat dissipation performance of the flip-chip LED chip, the reliability and light efficiency of the flip-chip LED chip are significantly optimized, thereby effectively reducing the brightness decay of the flip-chip LED chip.

[0066] The flip-chip LED chip of the present invention is prepared by the following method: Figure 4The schematic diagram of the preparation process of the flip-chip LED chip in the embodiment of the present invention is shown, which includes the following steps:

[0067] S1, growing an epitaxial layer on a substrate;

[0068] Figure 5 A schematic structural diagram of a substrate and an epitaxial layer in an embodiment of the present invention is shown.

[0069] The substrate 10 may be made of sapphire, gallium nitride, silicon carbide, or silicon.

[0070] Specifically, an N-type semiconductor layer 111 , an MQW quantum well layer 112 and a P-type semiconductor layer 113 are sequentially grown on the substrate 10 to form an epitaxial layer 110 ′; wherein the main material of the N-type semiconductor layer 111 and the P-type semiconductor layer 113 is gallium nitride.

[0071] S2, performing patterning on the epitaxial layer to obtain an epitaxial structure;

[0072] Figure 6 A schematic structural diagram of the epitaxial structure in an embodiment of the present invention is shown, wherein an N-type conductive opening 114 and an isolation trench 115 are formed in the epitaxial layer 110', and the isolation trench 115 avoids the N-type conductive opening 114; the N-type conductive opening 114 extends from the surface of the P-type semiconductor layer 113 to the inside of the N-type semiconductor layer 111; the isolation trench 115 extends from the surface of the P-type semiconductor layer 113 to the surface of the substrate 10.

[0073] S3, forming a metal electrode on the epitaxial structure;

[0074] Figure 7 A schematic structural diagram of the metal electrode in an embodiment of the present invention is shown. A transparent conductive layer 170 is first grown on the P-type semiconductor layer 113, and the transparent conductive layer 170 avoids the N-type conductive opening 114; the metal electrode 120 includes an N-type electrode 121 and a P-type electrode 122, and the N-type electrode 121 is formed in the N-type conductive opening 114, and the bottom of the N-type electrode 121 is connected to the N-type semiconductor layer 111; the P-type electrode 122 is formed on the transparent conductive layer 170, and the bottom of the P-type electrode 122 is connected to the transparent conductive layer 170.

[0075] In some specific embodiments, after forming the metal electrode 120, the method further includes:

[0076] Optional, Figure 8A schematic structural diagram of the sidewall passivation wall and the auxiliary electrode in an embodiment of the present invention is shown. A sidewall passivation wall 150 is deposited around the epitaxial structure 110, and an auxiliary electrode 160 is deposited on the sidewall passivation wall 150; the auxiliary electrode 160 includes a first sub-electrode 161 and a second sub-electrode, the first sub-electrode 161 is located on a side close to the N-type electrode 121, and the second sub-electrode is located on a side close to the P-type electrode 122.

[0077] Optionally, high-resistance dopants are injected around the epitaxial structure 110 by ion implantation, and the peripheral area of the epitaxial structure 110 is converted in situ into a sidewall passivation wall 150, and an auxiliary electrode 160 is deposited on the sidewall passivation wall 150; the auxiliary electrode 160 includes a first sub-electrode 161 and a second sub-electrode, the first sub-electrode 161 is located on the side close to the N-type electrode 121, and the second sub-electrode is located on the side close to the P-type electrode 122.

[0078] S4, forming an insulating transparent heat-conducting portion on the epitaxial structure, wherein the insulating transparent heat-conducting portion wraps the metal electrode;

[0079] Figure 9 A schematic structural diagram of the insulating transparent heat-conductive portion in an embodiment of the present invention is shown. The insulating transparent heat-conductive portion 130 includes a first insulating transparent heat-conductive block 131 and a second insulating transparent heat-conductive block 132. The first insulating transparent heat-conductive block 131 wraps the N-type electrode 121, fills the N-type conductive opening 114, and extends to all sides of the N-type conductive opening 114; the second insulating transparent heat-conductive block 132 wraps the P-type electrode 122.

[0080] Furthermore, the first insulating transparent thermally conductive block 131 further wraps the first sub-electrode 161 , and the second insulating transparent thermally conductive block 132 further wraps the second sub-electrode.

[0081] S5, forming a reflective layer on the epitaxial structure, wherein the reflective layer covers the insulating transparent heat-conducting portion;

[0082] Figure 10 A schematic structural diagram of the reflective layer in an embodiment of the present invention is shown. The main body of the reflective layer 140 directly contacts the epitaxial structure 110 , and a portion of the reflective layer 140 covers the surface of the insulating transparent heat-conducting portion 130 .

[0083] S6, forming an insulating protective layer along the side surfaces of the epitaxial structure, the side surfaces of the insulating transparent heat-conducting portion, and the side surfaces and top surface of the reflective layer;

[0084] Figure 11A schematic structural diagram of the insulating protective layer in an embodiment of the present invention is shown. If sidewall passivation walls 150 are provided around the epitaxial structure 110, an insulating protective layer 200 is formed along the side surfaces of the sidewall passivation walls 150, the side surfaces of the insulating transparent heat-conducting portion 130, and the side surfaces and top surface of the reflective layer 140.

[0085] Furthermore, the insulating protection layer 200 may be made of silicon dioxide, aluminum oxide, or silicon nitride, etc., which have good insulation properties.

[0086] S7, etching downward from the upper surface of the insulating protective layer to the top of the metal electrode to form a conductive through hole; the conductive through hole exposes the insulating transparent heat-conducting portion and the metal electrode;

[0087] Figure 12 FIG. 4 shows a schematic structural diagram of a conductive through hole in an embodiment of the present invention.

[0088] Optionally, the conductive through hole may only expose the upper surface of the insulating transparent heat-conducting portion 130 and the upper surface of the metal electrode 120 ; optionally, the conductive through hole may also extend into the insulating transparent heat-conducting portion 130 while exposing the upper surface of the metal electrode 120 .

[0089] Specifically, the conductive through holes include an N-type through hole 410 and a P-type through hole 420 . The N-type through hole 410 exposes the N-type electrode 121 and the first insulating transparent thermal conductive block 131 , and the P-type through hole 420 exposes the P-type electrode 122 and the second insulating transparent thermal conductive block 132 .

[0090] S8, forming an electrode pad in the conductive through hole, wherein the lower end of the electrode pad is connected to the metal electrode and the insulating transparent heat-conducting portion, and the upper end of the electrode pad is exposed outside the insulating protective layer;

[0091] See also Figure 3 The electrode pads 300 include an N-type pad 310 and a P-type pad 320. The N-type pad 310 is formed in the N-type through-hole 410, and the P-type pad 320 is formed in the P-type through-hole 420. The upper ends of the N-type pad 310 and the upper ends of the P-type pad 320 are both exposed outside the insulating protective layer 200. The lower end of the N-type pad 310 is connected to the top of the N-type electrode 121, and the lower end of the P-type pad 320 is connected to the top of the P-type electrode 122. In addition, the lower end of the N-type pad 310 is connected to the upper surface of the first insulating transparent thermally conductive block 131, or the lower end of the N-type pad 310 is embedded in the first insulating transparent thermally conductive block 131; the lower end of the P-type pad 320 is connected to the upper surface of the second insulating transparent thermally conductive block 132, or the lower end of the P-type pad 320 is embedded in the second insulating transparent thermally conductive block 132.

[0092] The above is a detailed introduction to a flip-chip LED chip provided in an embodiment of the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of the present invention. At the same time, for those skilled in the art, according to the idea of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A flip-chip LED chip, characterized in that: The chip comprises a substrate and a chip main body structure provided on the substrate, wherein the chip main body structure comprises a light-emitting structure, an insulating protective layer and an electrode pad, wherein the light-emitting structure is provided on the substrate, the insulating protective layer is provided on the surface of the light-emitting structure, the lower end of the electrode pad is embedded in the light-emitting structure, and the upper end of the electrode pad is exposed outside the insulating protective layer; The light-emitting structure includes an epitaxial structure arranged on the substrate, and a metal electrode, an insulating transparent heat-conducting portion and a reflective layer arranged on the epitaxial structure. The insulating transparent heat-conducting portion is embedded between the epitaxial structure and the reflective layer, the metal electrode is embedded in the insulating transparent heat-conducting portion, and the lower end of the electrode pad passes through the reflective layer to connect the metal electrode and the insulating transparent heat-conducting portion.

2. The flip-chip LED chip according to claim 1, wherein: The lower end of the electrode pad is embedded in the insulating transparent heat-conducting portion; or The lower end of the electrode pad is connected to the upper surface of the insulating transparent heat-conducting part.

3. The flip-chip LED chip according to claim 1, wherein: The light emitting structure further includes a sidewall passivation wall arranged around the epitaxial structure, and an auxiliary electrode arranged on the sidewall passivation wall, and the insulating transparent heat conductive portion wraps the auxiliary electrode.

4. The flip-chip LED chip according to claim 3, wherein: The metal electrode includes an N-type electrode and a P-type electrode; the electrode pad includes an N-type pad and a P-type pad; the insulating transparent heat-conducting portion includes a first insulating transparent heat-conducting block and a second insulating transparent heat-conducting block; the auxiliary electrode includes a first sub-electrode and a second sub-electrode, the first sub-electrode is located on a side close to the N-type electrode, and the second sub-electrode is located on a side close to the P-type electrode; The epitaxial structure includes an N-type semiconductor layer, an MQW quantum well layer, and a P-type semiconductor layer sequentially stacked on the substrate; an N-type conductive opening is formed in the epitaxial structure, and the N-type conductive opening extends from the surface of the P-type semiconductor layer into the N-type semiconductor layer; a transparent conductive layer is formed on the P-type semiconductor layer, and the transparent conductive layer avoids the N-type conductive opening; The N-type electrode is located in the N-type conductive opening, the bottom of the N-type electrode is connected to the N-type semiconductor layer, and the top of the N-type electrode is connected to the N-type pad; the P-type electrode is located on the transparent conductive layer, the bottom of the P-type electrode is connected to the transparent conductive layer, and the top of the P-type electrode is connected to the P-type pad; The first insulating transparent thermally conductive block is embedded between the reflective layer and the N-type conductive opening, and the first insulating transparent thermally conductive block wraps the N-type electrode, the first sub-electrode and a portion of the N-type pad. The first insulating transparent thermally conductive block fills the N-type conductive opening, and the first insulating transparent thermally conductive block extends to all sides of the N-type conductive opening; the second insulating transparent thermally conductive block is embedded between the reflective layer and the transparent conductive layer, and the second insulating transparent thermally conductive block wraps the P-type electrode, the second sub-electrode and a portion of the P-type pad.

5. The flip-chip LED chip according to claim 3, wherein: The material of the sidewall passivation wall is SiO2; or The material of the sidewall passivation wall is GaN containing high-resistance dopant, the high-resistance dopant is F, C or Fe, and the concentration range of the high-resistance dopant is 10 18 ~10 20 atoms / cm3.

6. The flip-chip LED chip according to claim 3, wherein: The auxiliary electrode includes a Cr layer, an Al layer, a Ti layer, a Pt layer, an Au layer and a Ni layer stacked in sequence on the sidewall passivation wall, the thickness of the Cr layer ranges from 2.5 to 25 nm, the thickness of the Al layer ranges from 100 to 200 nm, the thickness of the Ti layer ranges from 50 to 100 nm, the thickness of the Pt layer ranges from 25 to 100 nm, the thickness of the Au layer ranges from 100 to 500 nm, and the thickness of the Ni layer is 20 nm.

7. The flip-chip LED chip according to claim 1, wherein: The electrode pad includes an adhesion layer, a barrier layer, a welding layer and a test layer from bottom to top. The material of the adhesion layer is Cr, Ti, Pt or Ni, and the thickness range of the adhesion layer is 10 to 200 nm; the material of the barrier layer is one or more of Ti, Pt, and Ni, and the thickness range of the barrier layer is 50 to 300 nm; the material of the welding layer is one or more of Au, AuSn, Pb, and Sn, and the thickness range of the welding layer is 25 to 100 μm; the material of the test layer is one or more of Au, Ag, and Cu, and the thickness range of the test layer is 20 to 500 nm.

8. The flip-chip LED chip according to claim 1, wherein: The reflective layer is a distributed Bragg reflector, which is formed by stacking a pair of silicon dioxide film layers and aluminum oxide film layers; or The reflective layer is composed of an Ag reflective mirror layer and an insulating oxide layer stacked in sequence, and the Ag reflective mirror layer directly contacts the epitaxial structure; the insulating transparent thermal conductive part is embedded between the epitaxial structure and the insulating oxide layer, and the lower end of the electrode pad passes through the insulating oxide layer to connect the metal electrode and the insulating transparent thermal conductive part.

9. The flip-chip LED chip according to claim 8, wherein: There are 15 to 20 pairs of silicon dioxide film layers and aluminum oxide film layers.

10. The flip-chip LED chip according to claim 1, wherein: The insulating transparent heat-conducting portion is a diamond-like carbon film, and the thickness of the diamond-like carbon film ranges from 500 to 1000 nm.

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