WO2022041859A1

WO2022041859A1 - Mini led chip structure and manufacturing method therefor

Info

Publication number: WO2022041859A1
Application number: PCT/CN2021/094249
Authority: WO
Inventors: 张帆; 黄章挺
Original assignee: 福建兆元光电有限公司
Priority date: 2020-08-31
Filing date: 2021-05-18
Publication date: 2022-03-03
Also published as: CN111969088A

Abstract

A mini LED chip structure and a manufacturing method therefor, the mini LED chip structure comprising a P-shaped current-spreading implanted metal layer (1) and an N-shaped current-spreading implanted metal layer (2). The P-shaped current-spreading implanted metal layer (1) and the N-shaped current-spreading implanted layer (2) comprise anti-migration ruthenium, and because the metal ruthenium is used in the N/P-shaped current-spreading implanted metal layers (1, 2) to replace the traditional metal of platinum as an anti-migration layer, a higher anti-electromigration effect is made possible. In addition, the process window of ruthenium is stable and the price thereof is the same as that of platinum, and therefore costs will not increase, ensuring reasonable costs.

Description

A Mini LED chip structure and its manufacturing method

technical field

The invention relates to the field of chip manufacturing, in particular to a Mini LED chip structure and a manufacturing method thereof.

Background technique

Mini LED chips generally refer to LED chips with a side length of 100~200um. Because of their miniaturization, their application fields and manufacturing technologies are quite different from traditional LEDs; Mini LEDs are generally used for ultra-high resolution LED chips. Outdoor large screens, movie screens and direct-lit backlighting of high-end LCD displays, the above three application scenarios cannot be realized by traditional LEDs.

The manufacturing difficulties of Mini LED are: 1. Small size; 2. Complex structure; 3. Very high requirements for reliability in welding, temperature resistance, current resistance, etc.; LEDs are used in backlight, display and other fields, Mini LEDs are arranged in high density. Even if a single chip fails, the maintenance cost is high. Therefore, the reliability of the chip is the most important quality indicator of Mini LED products. The main reason for the reliability problem of Mini LED is the chip structure. Metals migrate under the long-term impact of current. To sum up, developing a metal structure that is resistant to current shocks and is not prone to migration is the core technical requirement for improving the quality of Mini LEDs;

In the prior art, platinum is usually used as an anti-migration layer in Mini LED chips. In the face of ultra-small size, large current density and long-term current impact, the problem of metal layer migration still occurs, including the lower layer covered by platinum. Metal migration issues.

technical problem

The technical problem to be solved by the present invention is to provide a Mini LED chip structure and a manufacturing method thereof, so as to realize a chip structure with higher resistance to current impact and higher resistance to electromigration.

technical solutions

In order to solve the above-mentioned technical problems, a kind of technical scheme adopted in the present invention is:

a Mini The LED chip structure includes a P-type current expansion injection metal layer and an N-type current expansion injection metal layer. The P-type current expansion injection metal layer and the N-type current expansion injection metal layer include anti-migration metal ruthenium.

beneficial effect

The beneficial effects of the present invention are: in the N/P type current spreading injection metal layer, metal ruthenium is used to replace the traditional metal platinum as the anti-migration layer; Current impact can achieve higher anti-electromigration effect, and the process window of ruthenium metal is stable, and the price is comparable to platinum, so it will not cause cost increase, and can achieve better anti-electricity under the condition of ensuring appropriate cost. Migration effect.

Description of drawings

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

2 is a schematic structural diagram of a P/N type current spreading injection metal layer according to an embodiment of the present invention;

3 is a top view of a P/N type current spreading injection metal layer according to an embodiment of the present invention;

FIG. 4 is a flow chart of steps of a method for manufacturing a Mini LED chip according to an embodiment of the present invention;

Label description:

1. P-type current expansion injection into the metal layer; 2. N-type current expansion injection into the metal layer;

3. Substrate layer; 4. N-type gallium nitride layer; 5. Multilayer quantum well layer; 6. P-type gallium nitride layer; 7. Current spreading layer; 8. First current stabilization layer; 9. P-type current Extended injection metal layer; 10. P-type welding interface metal layer; 11. Buffer insulation layer; 12. Stress release layer; 13. Insulating full-spectrum reflection layer; 14. N-type welding interface metal layer; 15. N-type current Extend the injection metal layer; 16. The second current stabilization layer.

Embodiments of the present invention

In order to describe in detail the technical content, achieved objects and effects of the present invention, the following descriptions are given with reference to the embodiments and the accompanying drawings.

Please refer to FIG. 1 to FIG. 3 , a Mini LED chip structure includes a P-type current spreading injection metal layer and an N-type current spreading injection metal layer. The P-type current spreading injection metal layer and the N-type current spreading injection metal layer include Anti-migration metal ruthenium.

It can be seen from the above description that the beneficial effects of the present invention are: in the N/P type current spreading injection metal layer, metal ruthenium is used to replace the traditional metal platinum as the anti-migration layer, and at the same time, the metal ruthenium has better resistance to overdrive and high temperature Excellent characteristics, can achieve higher anti-electromigration effect, and the process window of metal ruthenium is stable, and the price is comparable to platinum, so it will not cause the cost to rise. Electromigration effect.

Further, the P-type current expansion injection metal layer and the N-type current expansion injection metal layer are both metal structures as follows: from the side close to the bottom of the Mini LED chip to the side away from the bottom of the Mini LED chip in sequence It is chromium-aluminum-titanium-ruthenium-titanium-ruthenium-titanium-ruthenium-gold.

It can be seen from the above description that the composite layer composed of ruthenium and titanium can more effectively cover the metals such as aluminum and chromium in the lower layer, and further strengthen the effect of resisting electromigration.

Further, it also includes a substrate layer, an N-type gallium nitride layer, a multilayer quantum well layer, a P-type gallium nitride layer, a current spreading layer, a first current stabilization layer, a P-type welding interface metal layer, and a second current stabilization layer. layer and N-type solder bonding interface metal layer;

The N-type gallium nitride layer is located in the middle region on one side of the substrate layer, and the first stacking regions on the side of the N-type gallium nitride layer that is not in contact with the substrate layer are stacked in sequence. A quantum well layer, a P-type gallium nitride layer, a current spreading layer, a first current stabilizing layer, a P-type current spreading injection metal layer, and a P-type welding interface metal layer, and the second stack area on the other side is stacked in sequence There are a second current stabilization layer, an N-type current spreading injection metal layer and an N-type welding interface metal layer.

It can be seen from the above description that the substrate layer, N-type gallium nitride layer, multilayer quantum well layer, P-type gallium nitride layer and other structures cooperate with the P-type current expansion injection metal layer and the N-type current expansion injection metal layer to form a complete chip. structure, enabling the production of actual chips.

Further, the cross-sections of the P-type welding interface metal layer and the N-type welding interface metal layer are T-shaped;

the outer side of the first stack region, the side of the current spreading layer not in contact with the P-type gallium nitride layer, between the first stack region and the second stack region, and the second stack region A buffer insulating layer is stacked on the outside of the stacking area;

A stress release layer and an insulating full-spectrum reflection layer are sequentially stacked on the side of the buffer insulating layer away from the substrate layer;

One end of the P-type welding interface metal layer is connected to the P-type current spreading injection metal layer, and the other end passes through the stress release layer and the insulating full-spectrum reflective layer and is located at the insulating full-spectrum reflective layer away from the on one side of the stress release layer;

One end of the N-type welding interface metal layer is connected to the N-type current spreading injection metal layer, and the other end passes through the insulating buffer layer, the stress release layer and the insulating full-spectrum reflective layer and is located in the insulating full-spectrum reflective layer. The spectrally reflective layer is on the side away from the stress relief layer.

It can be seen from the above description that the provision of an insulating buffer layer, a stress release layer and an insulating full-spectrum reflective layer can further improve the performance of the chip, and improve the overall reliability, life, high current resistance and high temperature resistance of the chip.

Further, the metal structures of the P-type welding bonding interface metal layer and the N-type welding bonding interface metal layer are the same, and are chromium-aluminum-titanium-ruthenium-aluminum-titanium-nickel-gold;

The titanium-ruthenium-aluminum in the above metal structure is cycled multiple times.

From the above description, it can be seen that metal ruthenium is added to the P-type soldering interface metal layer and the N-type soldering interface metal layer, and the soldering ability of ruthenium is strong, which makes soldering more convenient and can improve the performance of the Mini LED chip.

Further, the current spreading layer is indium tin oxide, indium tungsten oxide or nickel-gold alloy.

It can be seen from the above description that the provision of the current spreading layer can improve the luminous efficiency.

Further, the buffer insulating layer is silicon oxide, titanium oxide, hafnium oxide or tantalum oxide;

The stress release layer is silicon oxide or titanium oxide.

It can be seen from the above description that the provision of the buffer insulating layer is beneficial to the transport of carriers, and the provision of the stress release layer increases the strength of the chip and makes the chip less likely to be damaged.

Further, the insulating full spectrum reflection layer is silicon oxide or titanium oxide, and the thickness is 3-7um.

It can be seen from the above description that the full spectrum reflection side is conducive to transmitting visible light of each spectrum and improving the display performance.

Please refer to FIG. 4 , a method for manufacturing a Mini LED chip, which can manufacture the above-mentioned Mini LED chip structure, including steps:

S1. The prepared gallium nitride epitaxial material is transferred according to the first preset pattern by the lithography facility, and then the gallium nitride epitaxial wafer is etched by ICP equipment to form an N-type gallium nitride layer on the substrate;

S2. First, a current expansion layer template is made by an evaporation machine or a sputtering machine, and then the current expansion layer template is pattern-transferred according to a second preset pattern by a photolithography facility, and finally the current expansion layer template is subjected to chemical reagents. Corrosion to form a current spreading layer;

S3. The photoresist is transferred according to the third preset pattern by the lithography facility, and then the P-type current expansion injection metal layer and the N-type current expansion injection metal layer are simultaneously formed by electron beam evaporation or sputter evaporation;

S4. After the material is transferred according to the seventh preset pattern by a photolithography facility, a P-type welding bonding interface metal layer and an N-type welding bonding interface metal layer are simultaneously fabricated by electron beam evaporation or sputtering evaporation.

It can be seen from the above description that a method for manufacturing a Mini LED chip is provided, so that the P-type current spreading injection metal layer and the N-type current spreading injection metal layer with ruthenium can be applied in actual production.

Further, between the S3 and the S4, it also includes:

The buffer insulating layer template is made by PECVD equipment or ALD equipment, and then the buffer insulating layer template is pattern-transferred according to the fourth preset pattern by the lithography facility, and then the buffer insulating layer template is etched by chemical reagents to form a buffer Insulation;

The stress release layer template is fabricated by PECVD equipment or optical ion evaporation equipment, and then the stress release layer template is pattern-transferred by the lithography facility according to the fifth preset pattern, and then the stress release layer is formed by chemical etching or ICP etching. Floor;

After the insulating full-spectrum reflective layer template is fabricated by optical ion evaporation equipment, the insulating full-spectrum reflective layer template is pattern-transferred by the lithography facility according to the sixth preset pattern, and then formed by chemical etching or ICP etching. Insulating full spectrum reflective layer.

It can be seen from the above description that by fabricating the buffer insulating layer, the stress release layer and the insulating full-spectrum reflective layer, a chip with higher performance can be fabricated.

Please refer to FIG. 1 to FIG. 3 , the first embodiment of the present invention is:

a Mini LED chip structure, please refer to Figure 1, including:

Substrate layer 3, N-type gallium nitride layer 4, multilayer quantum well layer 5, P-type gallium nitride layer 6, current spreading layer 7, first current stabilization layer 8, P-type current spreading injection metal layer 9, P-type The welding interface metal layer 10, the second current stabilization layer 16, the N-type current spreading injection metal layer 15, the N-type welding interface metal layer 14, the buffer insulating layer 11, the stress release layer 12 and the insulating full spectrum reflection layer 13;

The N-type gallium nitride layer 4 is located in the middle area on one side of the substrate layer 3 , and the side of the Mini LED chip close to the other side of the substrate layer 3 is the bottom of the Mini LED chip; The first stacking region on one side is sequentially stacked with a multi-layer quantum well layer 5, a P-type gallium nitride layer 6, a current spreading layer 7, a first current stabilizing layer 8, a P-type current spreading injection metal layer 9 and P-type welding bonding interface metal layer 10, and a second current stabilization layer 16, N-type current spreading injection metal layer 15 and N-type welding bonding interface metal layer 14 are sequentially stacked in the second stacking region on the other side;

The cross-sections of the P-type welding interface metal layer 10 and the N-type welding interface metal layer 14 are T-shaped; A buffer insulating layer 11 is stacked on the side, between the first stacking region and the second stacking region, and on the outside of the second stacking region; a stress release layer 12 and an insulating full-spectrum reflective layer 13 are stacked on top of the buffer insulating layer 11 in sequence; P One end of the type welding interface metal layer 10 is connected to the P-type current spreading injection metal layer 9 and the other end passes through the stress relief layer 12 and the insulating full spectrum reflection layer 13 and is located in the insulating full spectrum reflection layer 13 away from the stress relief On one side of the N-type welding interface metal layer 14 is connected to the N-type current spreading injection metal layer 15 and the other end passes through the insulating buffer layer 11, the stress relief layer 12 and the insulating full spectrum the reflective layer 13 is located on the side of the insulating full-spectrum reflective layer 13 away from the stress release layer;

A P-type contact surface is formed between the P-type current spreading injection metal layer and the first current stabilization layer; an N-type contact surface is formed between the N-type current spreading injection metal layer and the second current stabilization layer;

Please refer to FIG. 2 , the P-type current spreading injection metal layer 9 and the N-type current spreading injection metal layer 15 are the following metal structures: including chromium, aluminum, titanium, ruthenium, gold and platinum, close to the side of the substrate layer 3 to the side away from the substrate The bottom layer 3 side is arranged in sequence as chromium-aluminum-titanium-ruthenium-titanium-ruthenium-titanium-ruthenium-gold-titanium-platinum-gold-titanium (Cr-Al-(Ti-Ru-Ti-Ru-Ti-Ru) -Au-Ti-Pt-Au-Ti);

The metal structure of the P-type welding interface metal layer 10 and the N-type welding interface metal layer 14 are the same, and the side close to the substrate layer 3 to the side far from the substrate layer 3 is chromium-aluminum-titanium-ruthenium-aluminum-titanium - nickel-gold with multiple cycles of titanium-ruthenium-aluminum therein;

The current spreading layer 7 is indium tin oxide, indium tungsten oxide or nickel-gold alloy; the buffer insulating layer 11 is silicon oxide, titanium oxide, hafnium oxide or tantalum oxide; the stress release layer 12 is silicon oxide or titanium oxide; the insulating full spectrum reflection layer 13 is silicon oxide or titanium oxide, with a thickness of 3-7um.

Please refer to FIG. 4 , the second embodiment of the present invention is:

a Mini LED chip manufacturing method, including:

S1. The prepared GaN epitaxial material is pattern-transferred according to the first preset pattern by a photolithography facility, and then an ICP device is used to etch the gallium nitride epitaxial wafer to form an N-type gallium nitride layer on the substrate;

S2. First, use a vapor deposition machine or a sputtering machine to make a current expansion layer template. The material of the current expansion layer template can be indium tin oxide, indium tungsten oxide, nickel-gold alloy, etc., and then pass the photolithography facility to the current expansion layer template. The pattern transfer is performed according to the second preset pattern, and finally the current spreading layer template is etched by chemical reagents to form a current spreading layer;

Chemical reagents can be hydrochloric acid, oxalic acid, ferric chloride;

S3. The photoresist is transferred according to the third preset pattern by the lithography facility, and then the P-type current expansion injection metal layer and the N-type current expansion injection metal layer are simultaneously formed by electron beam evaporation or sputter evaporation; The metal layer structure is Cr-Al-(Ti-Ru-Ti-Ru-Ti-Ru)-Au-Ti-Pt-Au-Ti, and the excess photoresist is removed by cleaning with a stripper solution;

S4. The buffer insulating layer template is made by PECVD equipment or ALD equipment, and the material of the buffer insulating layer template can be silicon oxide, titanium oxide, hafnium oxide, tantalum oxide, etc. Four preset patterns are patterned, transferred to the surface of the processed part of the entire chip, and the buffer insulating layer template is etched by chemical reagents to form a buffer insulating layer;

The chemical reagent can be hydrofluoric acid, ammonium fluoride, etc.;

S5, using PECVD equipment or optical ion evaporation equipment to make a stress release layer template, the material of the stress release layer template can be silicon oxide, titanium oxide, etc., and then use the photolithography facility to make the stress release layer template according to the fifth preset pattern After the pattern transfer is performed, it is transferred to the surface of the processed part of the entire chip, and a stress release layer is formed by chemical etching or ICP etching;

If it is chemical etching, the etching solution can be hydrofluoric acid, ammonium fluoride, etc.; if it is ICP etching, the etching gas can be trifluoromethane, carbon tetrafluoride, sulfur hexafluoride, etc.;

S6. After the insulating full-spectrum reflective layer template is made by optical ion evaporation equipment, the insulating full-spectrum reflective layer template is transferred to the processed part of the entire chip after the pattern is transferred according to the sixth preset pattern by the lithography facility. On the surface, an insulating full-spectrum reflective layer is formed by chemical etching or ICP etching;

The material of the insulating full-spectrum reflective layer template can be silicon oxide, titanium oxide, etc., with a thickness of 3-7um; if it is chemical etching, the etching solution can be hydrofluoric acid, ammonium fluoride, hydrochloric acid, etc.; if it is ICP etching, etching The etching gas can be trifluoromethane, carbon tetrafluoride, sulfur hexafluoride, etc.;

S7. After the material is transferred according to the seventh preset pattern by the photolithography facility, the P-type welding bonding interface metal layer and the N-type welding bonding interface metal layer are simultaneously fabricated by electron beam evaporation or sputtering evaporation. The metal layer The structure is Cr-Al-(Ti-Ru-Al) structure in brackets after several cycles of Ti-Ni-Au, and the excess photoresist is removed by cleaning with a degumming solution;

The above-mentioned photolithography facility may be a photolithography machine or a photoresist.

In summary, the present invention provides a Mini LED chip structure and a manufacturing method thereof, using metal ruthenium as the metal material of the anti-migration layer in the P/N type current spreading injection metal layer, and utilizing the better current spreading of metal ruthenium , overdrive resistance, high temperature resistance and environmental corrosion resistance, to achieve the improvement of the above-mentioned aspects of the Mini LED chip, and the cost of metal ruthenium is comparable to the metal platinum used in the anti-migration layer of the prior art, the cost is appropriate, and the improvement The chip performance will not significantly increase the manufacturing cost, and the metal ruthenium is innovatively applied to the P/N type welding interface metal layer. The performance of the welding interface metal layer, the P/N type current expansion injection metal layer and the P/N type welding interface metal layer are all enhanced with metal ruthenium, which improves the strength of the Mini LED chip in many ways and reduces the cost of the Mini LED chip. The probability of failure in use; and, a Mini LED chip manufacturing method provided by the present invention can manufacture a Mini LED chip with the above structure, making it possible to apply ruthenium metal to the actual production of Mini LED chips.

The above descriptions are only examples of the present invention, and are not intended to limit the scope of the present invention. Any equivalent transformations made by using the contents of the description and drawings of the present invention, or directly or indirectly applied in related technical fields, are similarly included in the within the scope of patent protection of the present invention.

Claims

A Mini LED chip structure includes a P-type current expansion injection metal layer and an N-type current expansion injection metal layer, characterized in that the P-type current expansion injection metal layer and the N-type current expansion injection metal layer include anti-migration metal ruthenium .
The Mini LED chip structure according to claim 1, wherein the P-type current expansion injection metal layer and the N-type current expansion injection metal layer are both the following metal structures: The order from one side to the side away from the bottom of the Mini LED chip is chromium-aluminum-titanium-ruthenium-titanium-ruthenium-titanium-ruthenium-gold-titanium-platinum-gold-titanium.
A Mini LED chip structure according to claim 1, further comprising a substrate layer, an N-type gallium nitride layer, a multilayer quantum well layer, a P-type gallium nitride layer, a current spreading layer, a first current a stabilization layer, a P-type welding interface metal layer, a second current stabilization layer, and an N-type welding interface metal layer;

The N-type gallium nitride layer is located in the middle region on one side of the substrate layer, and the first stacking regions on the side of the N-type gallium nitride layer that is not in contact with the substrate layer are stacked in sequence. A quantum well layer, a P-type gallium nitride layer, a current spreading layer, a first current stabilizing layer, a P-type current spreading injection metal layer, and a P-type welding interface metal layer, and the second stack area on the other side is stacked in sequence There are a second current stabilization layer, an N-type current spreading injection metal layer and an N-type welding interface metal layer.
The Mini LED chip structure according to claim 3, wherein the cross-sections of the P-type welding-bonding interface metal layer and the N-type welding-bonding interface metal layer are T-shaped;

the outer side of the first stack region, the side of the current spreading layer not in contact with the P-type gallium nitride layer, between the first stack region and the second stack region, and the second stack region A buffer insulating layer is stacked on the outside of the stacking area;

A stress release layer and an insulating full-spectrum reflection layer are sequentially stacked on the side of the buffer insulating layer away from the substrate layer;

One end of the P-type welding interface metal layer is connected to the P-type current spreading injection metal layer, and the other end passes through the stress release layer and the insulating full-spectrum reflective layer and is located at the insulating full-spectrum reflective layer away from the on one side of the stress release layer;

One end of the N-type welding interface metal layer is connected to the N-type current spreading injection metal layer, and the other end passes through the insulating buffer layer, the stress release layer and the insulating full-spectrum reflective layer and is located in the insulating full-spectrum reflective layer. The spectrally reflective layer is on the side away from the stress relief layer.
The structure of a Mini LED chip according to claim 3, wherein the metal structure of the P-type welding interface metal layer and the N-type welding interface metal layer are the same, and are chromium-aluminum-titanium-ruthenium - aluminum-titanium-nickel-gold;

The titanium-ruthenium-aluminum in the above metal structure is cycled multiple times.
A Mini LED chip structure according to claim 3, wherein the current spreading layer is indium tin oxide, indium tungsten oxide or nickel-gold alloy.
A Mini LED chip structure according to claim 4, wherein the buffer insulating layer is silicon oxide, titanium oxide, hafnium oxide or tantalum oxide;

The stress release layer is silicon oxide or titanium oxide.
A Mini LED chip structure according to claim 4, wherein the insulating full-spectrum reflective layer is silicon oxide or titanium oxide, with a thickness of 3-7um.
A method for manufacturing a Mini LED chip, capable of manufacturing a Mini LED chip structure as claimed in claim 3 or 4, characterized in that it includes the steps of:

S1. The prepared gallium nitride epitaxial material is transferred according to the first preset pattern by the lithography facility, and then the gallium nitride epitaxial wafer is etched by ICP equipment to form an N-type gallium nitride layer on the substrate;

S2. First, a current expansion layer template is made by a vapor deposition machine or a sputtering machine, and then the current expansion layer template is pattern-transferred according to a second preset pattern by a photolithography facility, and finally the current expansion layer template is processed by chemical reagents. Corrosion to form a current spreading layer;

S3. The photoresist is transferred according to the third preset pattern by the lithography facility, and then the P-type current expansion injection metal layer and the N-type current expansion injection metal layer are simultaneously formed by electron beam evaporation or sputter evaporation;

S4. After the material is transferred according to the seventh preset pattern by a photolithography facility, a P-type welding bonding interface metal layer and an N-type welding bonding interface metal layer are simultaneously fabricated by electron beam evaporation or sputtering evaporation.
The method for manufacturing a Mini LED chip according to claim 9, wherein, between the S3 and the S4, further comprising:

The buffer insulating layer template is made by PECVD equipment or ALD equipment, and then the buffer insulating layer template is pattern-transferred according to the fourth preset pattern by the lithography facility, and then the buffer insulating layer template is etched by chemical reagents to form a buffer Insulation;

The stress release layer template is fabricated by PECVD equipment or optical ion evaporation equipment, and then the stress release layer template is pattern-transferred by the lithography facility according to the fifth preset pattern, and then the stress release layer is formed by chemical etching or ICP etching. Floor;

After the insulating full-spectrum reflective layer template is fabricated by optical ion evaporation equipment, the insulating full-spectrum reflective layer template is pattern-transferred by the lithography facility according to the sixth preset pattern, and then formed by chemical etching or ICP etching. Insulating full spectrum reflective layer.