CN106025012A - Preparation method of LED chip and LED chip prepared by adopting method - Google Patents

Abstract

The invention provides a method for preparing an LED chip and the LED chip prepared by the method. The LED chip includes an N-type semiconductor layer, a light-emitting layer, a P-type semiconductor layer, a current blocking layer, and a current blocking layer that are sequentially grown on a substrate. The ITO transparent conductive layer on the barrier layer, the N-type semiconductor layer is made with an N electrode, and the P electrode is made on the ITO transparent conductive layer. _The upper surface of the chip outside the N electrode is deposited with a SiO protective layer, and the upper surface of the chip outside the P electrode is A SiON anti-reflection film and a SiO ₂ protective layer are deposited sequentially. In the present invention, a layer of SiON anti-reflection film is deposited on the surface of the ITO transparent conductive layer and the SiON anti-reflection film is etched with phosphoric acid solution, so that damage and pollution are avoided in the ITO transparent conductive layer in the chip manufacturing process, and the transparency of ITO is improved. The quality of the conductive layer makes the brightness of the LED chip increase while the chip voltage decreases, making the LED more energy-saving and environmentally friendly.

Description

A method for preparing an LED chip and an LED chip prepared by the method

technical field

The invention relates to the field of LED chip manufacturing, in particular to a method for preparing an LED chip and an LED chip prepared by the method.

Background technique

In the process of LED chip production, the production of ITO (Indium Tin Oxide Indium Tin Oxide) film is a very important link. The purpose is to use the conductivity of the ITO film to expand the current, and because the ITO film has good transparency, the LED The light extraction efficiency of the chip.

At present, the process of manufacturing LED chips from evaporation of ITO transparent conductive layer to deposition of SiO ₂ protective layer includes steps: 1. Evaporation of ITO transparent conductive layer; 2. ITO photolithography; 3. ITO etching patterning; 4. ITO 5. ICP photolithography; 6. ICP etching to expose the N region; 7. ICP etching to remove the glue; 8. Deposition of the SiO ₂ protective layer. In the above steps, the ITO transparent conductive layer will be repeatedly corroded by the developer and the glue remover during the process of photolithography, etching and glue removal, which will reduce the quality of the ITO transparent conductive layer, affect the light extraction efficiency, and reduce the The brightness of the chip; and the photoresist on the surface of the ITO transparent conductive layer cannot be completely removed, and the residual impurities will also affect the contact between the ITO transparent conductive layer and the metal electrode, resulting in an increase in the chip voltage.

Chinese patent application 201410596788.7 discloses a method for growing an Al ₂ O ₃ /SiON anti-reflection film structure of an LED chip: put the LED chip after ITO etching into the MOCVD chamber for growing the Al ₂ O ₃ film, and then The MOCVD cavity is heated to 400-680°C, the Al source and the O source are introduced into the cavity, and the Al ₂ O ₃ film is grown as an electrode anti-reflection film; the Al ₂ O ₃ film is subjected to PAD photolithography using a negative photoresist, and the Form a PAD pattern on the photoresist; use ICP equipment to dry-etch the Al ₂ O ₃ film to remove the Al2O3 film in the PAD pattern area; vapor-deposit metal electrodes on the etched anti-reflection film to form P, N electrode structure, and then remove the photoresist, and put the chip after the glue removal into the tube furnace for annealing treatment; put the LED product with the prepared electrode into the cavity of the plasma enhanced chemical vapor deposition PECVD equipment, and pass N ₂ pre Heat, and then feed the mixed gas of diluted silane, nitrous oxide and ammonia to grow SiON anti-reflection film; use wet etching process to etch away the SiON on the surface of P and N electrodes, so far the anti-reflection film grows complete. This patent application is to grow the Al ₂ O ₃ /SiON anti-reflection film structure on the surface of the chip after the ITO etching is completed. The steps before the ITO etching will be damaged and polluted, which will affect the quality of the ITO film layer and affect the light emission of the LED. brightness.

Therefore, how to break through the existing technology and further improve the brightness of LED is still a technical problem to be solved urgently by those skilled in the art.

Contents of the invention

The purpose of the present invention is to provide a method for preparing an LED chip and the LED chip prepared by the method, so as to solve the problem that the ITO transparent conductive layer is easily damaged and polluted in the existing LED chip manufacturing process and thus affects the brightness of the LED. The preparation method of the LED chip is to deposit a SiON anti-reflection film on the surface of the ITO after evaporating the ITO transparent conductive layer, so that the ITO is protected by the SiON anti-reflection film during the chip manufacturing process, and before setting the P electrode, it is etched with a phosphoric acid solution. The SiON anti-reflection coating improves the quality of the ITO transparent conductive layer and can effectively improve the light extraction efficiency of the LED chip.

To achieve the above object, the invention provides a method for preparing an LED chip, comprising the following steps:

Step A, successively forming an epitaxial layer comprising an N-type semiconductor layer, a light-emitting layer and a P-type semiconductor layer and an ITO transparent conductive layer on the substrate;

Step B, depositing a layer of SiON antireflection film on the ITO transparent conductive layer;

Step C, forming steps on the N-type semiconductor layer by photolithography and etching; making the light-emitting layer, P-type semiconductor layer, ITO transparent conductive layer and SiON anti-reflection film on the upper step portion all remain, while the lower step portion The light-emitting layer, P-type semiconductor layer, ITO transparent conductive layer and SiON anti-reflection film are all etched away;

Step D, forming a layer of _SiO2 protective layer on the entire upper surface of the LED including the SiON anti-reflection film and the lower step portion of the N-type semiconductor layer;

Step E, form the groove P for setting the P electrode above the ITO transparent conductive layer by photolithography and etching the _SiO2 protective layer and the SiON anti-reflection film, and by photolithography and etching the _SiO2 protective layer on the lower step A groove N for setting the N electrode is formed above the part; wherein, when forming the groove P, first use BOE solution to etch the SiO ₂ protection layer, and then use phosphoric acid solution to etch the SiON anti-reflection film;

Step F, forming a P electrode at the groove P and an N electrode at the groove N.

In the present invention, step A also includes the following steps before forming the ITO transparent conductive layer:

Step a, depositing a current blocking layer on the entire surface of the LED epitaxial layer;

Step b, using photolithography and etching to remove part of the current blocking layer, and retaining the desired pattern of the current blocking layer structure.

In the present invention, the thickness of the SiON anti-reflection film deposited by plasma-enhanced chemical vapor deposition in the step B ranges from 100 to 1500 angstroms.

In the present invention, in the step C, a BOE solution is used to etch the SiON anti-reflection film.

In the present invention, the etching time of the SiON anti-reflection film by using the BOE solution in the step C is 30-120 seconds.

In the present invention, the volume ratio of phosphoric acid to water in the phosphoric acid solution used in step E is 1-9:1, the corrosion temperature is 80°C-200°C, and the corrosion time is 30-200 seconds.

In addition, the present invention also provides an LED chip prepared by the above method, wherein the LED chip sequentially includes a substrate, an epitaxial layer, and an electrode in the thickness direction, and the epitaxial layer includes an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer. , the N-type semiconductor layer is a stepped structure including an upper step portion and a lower step portion, the light-emitting layer and the P-type semiconductor layer are sequentially arranged above the upper step portion, and an ITO transparent conductive layer is also provided on the P-type semiconductor layer , the electrodes include an N electrode arranged on the lower step portion and a P electrode arranged on the ITO transparent conductive layer, the upper surface of the chip outside the N electrode is deposited with a SiO ₂ protective layer, and the upper surface of the chip outside the P electrode is deposited sequentially There are SiON anti-reflection coating and SiO2 protective layer.

In the present invention, the thickness of the SiON anti-reflection film is 100-1500 angstroms.

In the present invention, a current blocking layer is provided on the P-type semiconductor layer, and the ITO transparent conductive layer covers the current blocking layer.

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

1. The present invention deposits an ITO transparent conductive layer on the LED epitaxial layer and then deposits a layer of SiON anti-reflection film on the ITO surface, so that the ITO transparent conductive layer is subjected to SiON in the process of photolithography, etching and photolithography. The protection of the anti-reflection film prevents the ITO transparent conductive layer from being damaged and polluted, improves the quality of the ITO transparent conductive layer, and reduces the voltage while increasing the brightness of the LED chip;

2. The present invention uses phosphoric acid solution to etch the SiON anti-reflection film when forming the groove P of the P electrode, reduces the contact time between the LED chip and the BOE solution, and further reduces or avoids damage to the ITO transparent conductive layer during the preparation of the LED chip; In addition, this also reduces the risk of the BOE solution permeating through the ITO transparent conductive layer and corroding the current blocking layer under the ITO transparent conductive layer, further ensuring the light extraction efficiency of the LED chip.

In addition to the objects, features and advantages described above, the present invention has other objects, features and advantages. Hereinafter, the present invention will be described in further detail with reference to the drawings.

Description of drawings

The accompanying drawings constituting a part of this application are used to provide further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

Fig. 1 is the cross-sectional structure schematic diagram of a kind of LED chip of the present invention;

Among them, 1. Substrate, 2. N-type semiconductor layer, 21. Upper step part, 22. Lower step part, 3. Light emitting layer, 4. P-type semiconductor layer, 5. ITO transparent conductive layer, 6. SiON antireflection Membrane, 7, _SiO2 protective layer, 8, N electrode, 9, P electrode, 10, current blocking layer.

detailed description

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in various ways defined and covered by the claims.

Referring to Fig. 1, a kind of LED chip of the present invention, this LED chip comprises substrate 1, epitaxial layer and electrode successively in thickness direction, and epitaxial layer comprises N-type semiconductor layer 2, light-emitting layer 3 and P-type semiconductor layer 4, N The P-type semiconductor layer 2 is a stepped structure including an upper step portion 21 and a lower step portion 22. The light-emitting layer 3 and the P-type semiconductor layer 4 are sequentially arranged above the upper step portion 21, and the P-type semiconductor layer 4 is also provided with ITO. Transparent conductive layer 5, electrode comprises the N electrode 8 that is arranged on the lower step portion 22 and the P electrode 9 that is arranged on ITO transparent conductive layer 5, and the chip top surface outside N electrode is deposited with SiO ₂ protective layer 7, the outside of P electrode A SiON anti-reflection film 6 and a SiO2 protective layer 7 are sequentially deposited on the upper surface of the chip.

In a specific implementation manner, the thickness of the SiON anti-reflection film 6 is 100˜1500 angstroms.

In a specific embodiment, the P-type semiconductor layer 4 is provided with a current blocking layer 10, and the ITO transparent conductive layer 5 covers the current blocking layer.

The method for preparing the above-mentioned LED chip according to the embodiment of the present invention includes the following steps:

Step A, grow N-type semiconductor layer 2, light-emitting layer 3 and P-type semiconductor layer 4 sequentially on substrate 1 to form LED epitaxial layer; and vapor-deposit ITO transparent conductive layer 5 on the epitaxial layer; specifically, metal The luminescent epitaxial layer is grown by organic chemical vapor deposition, molecular beam epitaxy or hydride vapor phase epitaxy. In the present invention, the metal organic chemical vapor deposition technology is preferably used to grow the epitaxial layer.

Step B, depositing a layer of SiON anti-reflection film 6 on the ITO transparent conductive layer 5; in the present invention, preferably adopting the plasma enhanced chemical vapor deposition method to deposit the SiON anti-reflection film on the surface of the ITO transparent conductive layer.

Step C, forming steps on the N-type semiconductor layer 2 by photolithography and etching; so that the light-emitting layer 3, the P-type semiconductor layer 4, the ITO transparent conductive layer 5 and the SiON anti-reflection film 6 on the upper step portion 21 are all retained, The light-emitting layer 3 , the P-type semiconductor layer 4 , the ITO transparent conductive layer 5 and the SiON anti-reflection film 6 on the lower step portion 22 are all etched away. Specifically include: using photoresist to perform ITO photolithography on the SiON antireflection film, forming an ITO layer on the photoresist layer; using the ITO layer as a mask to etch the SiON antireflection film for 30 to 120 seconds, Remove the SiON antireflection film; use the ITO layer as a mask to perform ITO etching on the ITO transparent conductive layer, and then remove the photoresist after ITO photolithography; use photoresist on the P-type semiconductor layer for MESA photolithography, A MESA layer is formed on the photoresist layer, and the P-type semiconductor layer 4, the light-emitting layer 3 and the N-type semiconductor layer 2 are sequentially etched from top to bottom with the MESA layer as a mask to make the N-type semiconductor layer 2 A stepped structure with an upper stepped portion 21 and a lower stepped portion 22 is formed to expose the N-type semiconductor layer; and then the photoresist after MESA photolithography is removed.

Step D, forming a layer of SiO ₂ protective layer 7 on the entire upper surface of the LED including the SiON anti-reflection film 6 and the lower step portion 22 of the N-type semiconductor layer;

Step E, form the groove P for setting the P electrode 9 above the ITO transparent conductive layer 5 by photolithography and etching SiO ₂ protective layer 7 and SiON anti-reflection film 6, and by photolithography and etching SiO ₂ protective layer 7 A groove N for setting the N electrode 8 is formed above the lower step portion 22; wherein, when forming the groove P, the SiO ₂ protective layer 7 is first etched with a BOE solution, and then the SiON anti-reflection film 6 is etched with a phosphoric acid solution. In the present invention, use photoresist to carry out PAD lithography to _SiO2 protection layer, form PAD layer on photoresist layer; To etch PAD layer, use BOE solution earlier to _SiO2 of PAD layer area The protective layer is corroded, and then the SiON anti-reflection film in the PAD layer area is etched with phosphoric acid solution, and the SiO protective layer ₂ and the SiON anti-reflection film in the PAD layer area are removed respectively to form grooves P and grooves N; In this step, the volume ratio of phosphoric acid to water in the phosphoric acid solution used is 1-9:1, the corrosion temperature is 80°C-200°C, and the corrosion time is 30-200 seconds.

Step F, forming a P electrode 9 at the groove P and an N electrode 8 at the groove N.

In a specific embodiment, step A also includes the following steps before forming the ITO transparent conductive layer 5:

Step a, depositing a current blocking layer 10 on the entire surface of the LED epitaxial layer;

Step b, using photolithography and etching to remove part of the current blocking layer, and retaining the desired pattern of the current blocking layer structure.

In a specific embodiment, the thickness of the SiON anti-reflection film 6 deposited by plasma enhanced chemical vapor deposition in step B ranges from 100 to 1500 angstroms.

In a specific implementation manner, in step C, the SiON anti-reflection film 6 is etched with a BOE solution.

In a specific embodiment, the etching time of the SiO ₂ protective layer by using the BOE solution in step E is 30-120 seconds.

In the present invention, choose six epitaxial wafers with the same furnace and circle (the epitaxial wafers with the same furnace and the same circle are to ensure the consistency of the photoelectric parameters of the epitaxial wafers and ensure the accuracy of the experimental conclusions. Among the six epitaxial wafers, three adopt existing Some methods are made, that is, it does not involve setting up SiON anti-reflection film and using phosphoric acid solution to etch SiON anti-reflection film, and the other three are made by the method of the present invention) to prepare chips. The appearance inspection shows that the appearance of the experimental chip is normal, and the electrical properties are measured The parameters are shown in Table 1:

Table 1

From the parameters in the above Table 1, it can be known that the LED chip structure prepared by the method of the present invention, since a layer of SiON anti-reflection film is deposited after the evaporation of the ITO transparent conductive layer, and the SiON anti-reflection film is etched with phosphoric acid solution before the P electrode is set. film, so that the ITO transparent conductive layer will not be corroded and stained during the entire manufacturing process of the chip, and the quality of the ITO transparent conductive layer will be improved. Compared with the chips prepared by the existing method, the voltage VF1 of the chip prepared by the method of the present invention is reduced by 0.042V, the brightness LOP1 is increased by 1.8mw, and the ratio of brightness improvement is 0.91%. The purpose of increasing the brightness of the LED while reducing the voltage is achieved.

In the present invention, the chips made by the existing method and the chips made by the method of the present invention near the average value of the full measurement data are respectively selected for packaging, and the Blu-ray packaging data are shown in Table 2:

Table 2

From the data in the above table 2, it can be seen that the voltage of the LED chip packaged LED prepared by the method of the present invention is reduced by 0.042V compared with the LED chip packaged LED prepared by the existing method, and the optical power is increased by 1.9mw, and the increase ratio is 0.78%, and the luminous efficiency increased by 1.1%.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. A method for preparing an LED chip, comprising the steps of: Step A, successively forming an epitaxial layer comprising an N-type semiconductor layer (2), a light-emitting layer (3) and a P-type semiconductor layer (4) and an ITO transparent conductive layer (5) on the substrate (1); Step B, depositing a layer of SiON antireflection film (6) on the ITO transparent conductive layer (5); Step C, form the step on the N-type semiconductor layer (2) by photolithography and etching; Make the light-emitting layer (3), P-type semiconductor layer (4), ITO transparent conductive layer (5) on the upper step portion (21) ) and SiON anti-reflection film (6) are retained, and the light-emitting layer (3), P-type semiconductor layer (4), ITO transparent conductive layer (5) and SiON anti-reflection film (6) on the lower step portion (22) are etched away; Step D, forming a layer of _SiO2 protection layer (7) on the entire upper surface of the LED including the SiON anti-reflection film (6) and the lower step portion (22) of the N-type semiconductor layer; Step E, form the groove P for setting the P electrode (9) above the ITO transparent conductive layer (5) by photolithography and etching SiO ₂ protective layer (7) and SiON anti-reflection film (6), and pass light Engraving and etching the SiO ₂ protection layer (7) forms a groove N for setting the N electrode (8) above the lower step portion (22); wherein, when forming the groove P, first use BOE solution to etch the SiO ₂ Protective layer (7), after using phosphoric acid solution to etch SiON anti-reflection film (6); Step F, forming a P electrode at the groove P and an N electrode at the groove N. 2. the preparation method of LED chip according to claim 1, is characterized in that, in step A, also comprises the following steps before forming ITO transparent conductive layer (5): Step a, depositing a current blocking layer (10) on the entire surface of the LED epitaxial layer; Step b, using photolithography and etching to remove part of the current blocking layer, and retaining the desired pattern of the current blocking layer structure. 3. The method for preparing an LED chip according to claim 1, characterized in that, in the step B, the thickness range of the SiON anti-reflection film (6) deposited by plasma-enhanced chemical vapor deposition method is 100-1500 angstroms. 4. The preparation method of the LED chip according to claim 1, characterized in that, in the step C, adopt BOE solution to etch the SiON anti-reflection film (6). 5 . The method for preparing an LED chip according to claim 4 , characterized in that, in the step C, the etching time of the SiON anti-reflection film ( 6 ) with BOE solution is 30-120 seconds. 6 . 6. The method for preparing LED chips according to claim 1, characterized in that the volume ratio of phosphoric acid to water in the phosphoric acid solution used in the step E is 1-9:1, and the corrosion temperature is 80°C-200°C , The corrosion time is 30-200 seconds. 7. The LED chip prepared by the method according to any one of claims 1 to 6, characterized in that, the LED chip sequentially comprises a substrate (1), an epitaxial layer and an electrode in the thickness direction, and the epitaxial layer comprises N type semiconductor layer (2), light-emitting layer (3) and P-type semiconductor layer (4), the N-type semiconductor layer (2) is a stepped structure including an upper step portion (21) and a lower step portion (22), and the light-emitting layer (3) and the P-type semiconductor layer (4) are sequentially arranged above the upper step portion (21), the P-type semiconductor layer (4) is also provided with an ITO transparent conductive layer (5), and the electrodes include The N electrode (8) on the lower step (22) and the P electrode (9) arranged on the ITO transparent conductive layer (5), the upper surface of the chip outside the N electrode is deposited with SiO ₂ protective layer (7), A SiON anti-reflection film (6) and a SiO2 protective layer (7) are sequentially deposited on the upper surface of the chip outside the P electrode. 8. A high-brightness LED chip according to claim 7, characterized in that the thickness of the SiON anti-reflection film (6) is 100-1500 angstroms. 9. A high-brightness LED chip according to claim 7, characterized in that, the P-type semiconductor layer (4) is provided with a current blocking layer (10), and the ITO transparent conductive layer (5) covers the above the current blocking layer.