LED chip preparation method and LED chip

Abstract

The application provides an LED chip preparation method, which comprises the following steps: providing a semi-finished LED chip with an epitaxial layer; coating a negative photoresist on the surface of the semi-finished LED chip, and then performing exposure and development by using a photoetching plate provided with an N-type electrode pattern and a P-type electrode pattern respectively; and performing evaporation and photoresist removal on the corresponding regions of the semi-finished LED chip surface where electrodes are to be made, so as to obtain an N-type electrode and a P-type electrode. The application solves the problem of high chip voltage caused by poor ohmic contact in the prior art.

Description

Technical Field

[0001] This invention relates to the field of semiconductor chip technology, and in particular to a method for preparing an LED chip and an LED chip. Background Technology

[0002] As is well known, in the structure of an LED chip, the metal in contact with the semiconductor must form a good ohmic contact and also require good adhesion. Furthermore, the formation of an ohmic contact between the metal and semiconductor requires a matching work function between the two components.

[0003] Currently, the mainstream P and N electrode structures are generally identical, meaning the metal in contact between the N electrode and the N-type semiconductor is the same metal as the metal in contact between the P electrode and the P-type semiconductor or current spreading layer. It is known that when the semiconductor doping concentration remains constant, a metal with a higher work function is needed to form an ohmic contact with the P-type semiconductor, while a metal with a lower work function is needed to form an ohmic contact with the N-type semiconductor. The fact that the metal in contact between the N electrode and the N-type semiconductor is the same metal as the metal in contact between the P electrode and the P-type semiconductor or current spreading layer inevitably leads to poor ohmic contact, resulting in high chip voltage. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide an LED chip manufacturing method and an LED chip, which aims to solve the problem of high voltage caused by poor ohmic contact in existing LED chips.

[0005] The embodiments of the present invention are implemented as follows: On one hand, the present invention proposes a method for manufacturing an LED chip; Provide a semi-finished LED chip with a pre-fabricated epitaxial layer; Negative photoresist is applied to the surface of the semi-finished LED chip, and then exposed and developed using photomasks with N-type electrode patterns and P-type electrode patterns, respectively. After vapor deposition of the corresponding contact metal layer on the corresponding area of ​​the electrode to be manufactured on the surface of the semi-finished LED chip, the adhesive is removed to obtain N-type electrode and P-type electrode.

[0006] Furthermore, in the above-mentioned LED chip fabrication method, the contact metal layer of the N-type electrode is made of Ti.

[0007] Furthermore, in the above-mentioned LED chip fabrication method, the material of the contact metal layer of the P-type electrode is either Ni or Cr.

[0008] Furthermore, in the above-mentioned LED chip fabrication method, the thickness of the contact metal layer is 10 Å to 100 Å.

[0009] Furthermore, in the above-mentioned LED chip fabrication method, the step of performing at least the corresponding contact metal layer evaporation and then removing the adhesive on the corresponding areas of the electrodes to be fabricated on the surface of the semi-finished LED chip to obtain N-type electrodes and P-type electrodes includes: After vapor deposition of corresponding contact metal layers, reflective metal layers, transition metal layers, and protective metal layers on the corresponding areas of the electrodes to be manufactured on the surface of the semi-finished LED chip, the adhesive is removed to obtain N-type electrodes and P-type electrodes.

[0010] Furthermore, in the above-mentioned LED chip fabrication method, the reflective metal layers of the N-type electrode and the P-type electrode are made of either Al or Ag, the transition metal layers of the N-type electrode and the P-type electrode are made of either or a combination of Ti, Pt, and Ni, and the protective metal layers of the N-type electrode and the P-type electrode are made of Au.

[0011] Furthermore, in the above-mentioned LED chip fabrication method, after the step of vapor-depositing at least the corresponding contact metal layer and removing the adhesive in the corresponding areas of the electrodes to be fabricated on the surface of the semi-finished LED chip to obtain N-type electrodes and P-type electrodes, the method further includes: A protective layer is created to cover the surface of the epitaxial layer except for the portion of the wire bonding section that is exposed.

[0012] Furthermore, in the above-mentioned LED chip fabrication method, the step of providing a semi-finished LED chip with a fabricated epitaxial layer includes: Provide a patterned substrate; A buffer layer, an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer are sequentially grown on the patterned substrate. The exposed areas of a partial N-type semiconductor layer are etched using photolithography, and then current blocking layers are deposited on the N-type semiconductor layer and the P-type semiconductor layer, respectively. A transparent conductive layer is deposited on the P-type semiconductor layer after the current blocking layer is deposited.

[0013] Furthermore, in the above-mentioned LED chip fabrication method, the transparent conductive layer is either indium tin oxide or indium zinc oxide.

[0014] In another aspect, the present invention proposes an LED chip, which is prepared by any of the LED chip preparation methods described above.

[0015] This invention, by separately exposing, developing, and then separately vapor-depositing the N-type and P-type electrodes, allows for the selection of contact metals that achieve optimal ohmic contact between them, rather than a compromise. Both the N-type and P-type semiconductor layers achieve their respective optimal ohmic contact, effectively reducing chip voltage. This solves the problem of high voltage in existing LED chips due to poor ohmic contact. Attached Figure Description

[0016] Figure 1 This is a flowchart of an LED chip fabrication method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the exposed area where a portion of the N-type semiconductor layer is formed in an LED chip fabrication method according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the formation of a current blocking layer in an LED chip fabrication method according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the formation of a transparent conductive layer in an LED chip fabrication method according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the formation of electrodes in an LED chip fabrication method according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the formation of a protective layer in an LED chip fabrication method according to an embodiment of the present invention.

[0017] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0018] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0019] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] This invention addresses the problem that existing LED chips, when selecting contact metals for P-type and N-type semiconductors, cannot separately choose the metal with the most suitable work function, requiring a trade-off that results in suboptimal ohmic contact and high chip voltage. This invention proposes an LED chip fabrication method and an LED chip, wherein: Please see Figure 1 The diagram shows a flowchart of an LED chip fabrication method according to an embodiment of the present invention, which includes steps S10 to S12.

[0022] Step S10: Provide a semi-finished LED chip with a fabricated epitaxial layer.

[0023] For a good ohmic contact to be formed between a metal and a semiconductor, their work functions need to be matched. The metal in contact with the semiconductor mainly refers to the metal in contact with the electrode, i.e., the metal in the electrode structure. Therefore, it is necessary to improve the metal in contact with the electrode. First, it is necessary to obtain a semi-finished LED chip with a fabricated epitaxial layer. Specifically, in the embodiments of the present invention, the preparation of a semi-finished LED chip with a fabricated epitaxial layer can be carried out in the following manner: Provide a patterned substrate; A buffer layer, an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer are sequentially grown on the patterned substrate. The exposed areas of a partial N-type semiconductor layer are etched using photolithography, and then current blocking layers are deposited on the N-type semiconductor layer and the P-type semiconductor layer, respectively. A transparent conductive layer is deposited on the P-type semiconductor layer after the current blocking layer is deposited.

[0024] First, an epitaxial layer is prepared as the basis for subsequent electrode fabrication. Specifically, the epitaxial layer may include a substrate, an N-type semiconductor layer deposited on the substrate, a light-emitting layer, and a P-type semiconductor layer. In some optional embodiments of the present invention, the epitaxial wafer may also include other structures besides the above-mentioned structures. Furthermore, after the epitaxial layer is prepared, such as Figure 2 As shown, the exposed area of ​​the partial N-type semiconductor layer is then etched using photolithography, forming what is called the MESA platform. Then, as... Figure 3As shown, a current-blocking layer is fabricated to reduce the recombination of charge carriers directly below the metal electrode. Radiated photons are absorbed and blocked by the metal. Finally, a transparent conductive layer is fabricated, as shown... Figure 5 As shown, it is formed on a P-type semiconductor layer to increase the lateral current spread capability. The transparent conductive layer is generally indium tin oxide (ITO) or indium zinc oxide (IZO).

[0025] Step S11: Apply negative photoresist to the surface of the semi-finished LED chip, and then expose and develop it using photomasks with N-type electrode patterns and P-type electrode patterns respectively.

[0026] Specifically, after applying negative photoresist to the surface of the semi-finished LED chip, photomasks with N-type and P-type electrode patterns are used for exposure and development so that metal evaporation can be performed on the surface of the semi-finished LED chip.

[0027] Step S12: After vapor deposition of the corresponding contact metal layer in the corresponding area of ​​the electrode to be manufactured on the surface of the semi-finished LED chip, the adhesive is removed to obtain N-type electrode and P-type electrode.

[0028] In this process, the surface of the semi-finished LED chip has corresponding areas for electrode fabrication. After depositing a contact metal layer in these areas and removing the adhesive, the corresponding N-type and P-type electrodes are obtained. Specifically, for example... Figure 5 As shown.

[0029] Understandably, by exposing, developing, and then evaporating N-type and P-type electrodes separately, contact metals that achieve optimal ohmic contact can be selected according to actual needs, rather than a compromise. Both N-type and P-type semiconductor layers can achieve their respective optimal ohmic contact, effectively reducing chip voltage.

[0030] Specifically, the contact metal layer of the N-type electrode is made of Ti. Metal Ti has strong adhesion to semiconductors, low stress, and a low work function (4.33 eV), making it a good contact metal for N-type semiconductors. Therefore, metal Ti is used as the contact metal for N-type semiconductors. The contact metal layer of the P-type electrode is made of either Ni or Cr. Cr and Ni have work functions of 4.5 eV and 5.15 eV, respectively. Using metal Ni as the contact metal for P-type semiconductors can achieve better ohmic contact.

[0031] More specifically, the thickness of the contact metal layer is 10 Å to 100 Å. In some preferred embodiments of the present invention, to further improve the quality of the electrode structure, a corresponding contact metal layer, a reflective metal layer, a transition metal layer, and a protective metal layer are deposited on the corresponding areas of the electrodes to be fabricated on the surface of the semi-finished LED chip, followed by adhesive removal, to obtain N-type electrodes and P-type electrodes. Specifically, the reflective metal layer is made of any one of Al or Ag, the transition metal layer is made of any one or more combinations of Ti, Pt, and Ni, and the protective metal layer of the N-type and P-type electrodes is made of Au.

[0032] In addition, in some optional embodiments of the present invention, after the step of evaporating and removing the adhesive from the corresponding areas of the electrodes to be fabricated on the surface of the semi-finished LED chip to obtain N-type electrodes and P-type electrodes, the method further includes: A protective layer is created to cover the surface of the epitaxial layer except for the portion of the wire bonding section that is exposed.

[0033] After the electrodes are fabricated, such as Figure 6 As shown, a protective layer is created, exposing the wire bonding section and covering the rest of the LED chip to protect it.

[0034] On the other hand, the LED chip proposed in the embodiments of the present invention is prepared by any of the LED chip preparation methods described above.

[0035] In summary, the LED chip fabrication method and LED chip proposed in the above embodiments of the present invention, by separately exposing, developing, and then evaporating the N-type and P-type electrodes, allows for the selection of contact metals that achieve optimal ohmic contact with each other according to actual needs, rather than a compromise. Both the N-type semiconductor layer and the P-type semiconductor layer can achieve their respective optimal ohmic contact, effectively reducing the chip voltage.

[0036] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for fabricating an LED chip, characterized in that, The method includes; Provide a semi-finished LED chip with a pre-fabricated epitaxial layer; Negative photoresist is applied to the surface of the semi-finished LED chip, and then exposed and developed using photomasks with N-type electrode patterns and P-type electrode patterns, respectively. After vapor deposition of the corresponding contact metal layer on the corresponding area of ​​the electrode to be fabricated on the surface of the semi-finished LED chip, the adhesive is removed to obtain N-type and P-type electrodes, specifically including: After vapor deposition of corresponding contact metal layers, reflective metal layers, transition metal layers and protective metal layers on the corresponding areas of the electrodes to be manufactured on the surface of the semi-finished LED chip, the adhesive is removed to obtain N-type electrodes and P-type electrodes. The thickness of the contact metal layer is 10 Å to 100 Å.

2. The LED chip fabrication method according to claim 1, characterized in that, The contact metal layer of the N-type electrode is made of Ti.

3. The LED chip fabrication method according to claim 1, characterized in that, The contact metal layer of the P-type electrode is made of either Ni or Cr.

4. The LED chip fabrication method according to claim 1, characterized in that, The reflective metal layers of the N-type and P-type electrodes are made of either Al or Ag, the transition metal layers of the N-type and P-type electrodes are made of either or a combination of Ti, Pt, and Ni, and the protective metal layers of the N-type and P-type electrodes are made of Au.

5. The LED chip fabrication method according to claim 1, characterized in that, The step of vapor-depositing at least the corresponding contact metal layer on the corresponding area of ​​the electrode to be manufactured on the surface of the semi-finished LED chip and then removing the adhesive to obtain the N-type electrode and the P-type electrode further includes: A protective layer is created to cover the surface of the epitaxial layer except for the portion of the wire bonding section that is exposed.

6. The LED chip fabrication method according to any one of claims 1 to 5, characterized in that, The step of providing a semi-finished LED chip with a fabricated epitaxial layer includes: Provide a patterned substrate; A buffer layer, an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer are sequentially grown on the patterned substrate. The exposed areas of a partial N-type semiconductor layer are etched using photolithography, and then current blocking layers are deposited on the N-type semiconductor layer and the P-type semiconductor layer, respectively. A transparent conductive layer is deposited on the P-type semiconductor layer after the current blocking layer is deposited.

7. The LED chip fabrication method according to claim 6, characterized in that, The transparent conductive layer is either indium tin oxide or indium zinc oxide.

8. An LED chip, characterized in that, The LED chip is prepared by any one of claims 1 to 7.

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