CN105244419A - Preparation method of wafer level thin-film flip LED chip - Google Patents

Abstract

The invention provides a preparation method of a wafer level thin-film flip LED chip. According to the method, conductive columns are prepared so as to lead out electrodes of the chip, and then the periphery of each conductive column is filled with an insulating material so as to carry out insulation. The preparation method provided by the invention is not limited by an epitaxial substrate, a white LED chip can be prepared directly, the production efficiency is high, and the cost is low.

Description

A method for preparing wafer-level thin-film flip-chip LED chips

technical field

The invention belongs to the technical field of semiconductors, and in particular relates to a method for preparing wafer-level thin-film flip-chip LED chips.

Background technique

At present, high-brightness LEDs have become the focus of the development of the LED industry and are widely used in indoor and outdoor lighting. In order to speed up the popularization of LED lighting, reducing its manufacturing cost is the only way. Flip chip (Flip-Chip) has become the development focus of various LED companies due to its good heat dissipation, high light output efficiency and no wiring. The current flip chips are all prepared on transparent substrates (such as sapphire substrates and SiC substrates), but transparent substrates have a certain absorption of light and are five-sided light emitting, which requires higher light distribution. More importantly, the current method of preparing flip chips is not suitable for non-transparent substrate epitaxy technology, such as silicon substrates, and silicon substrate epitaxy technology has been considered to be one of the best options for reducing LED costs in the future . Therefore, there are thin-film flip-chips with the substrate stripped off on the market. In addition to the advantages of flip-chips without wire bonding, thin-film flip-chips also have the advantage of good light-emitting morphology of thin-film chips. However, the manufacturing method of this thin-film flip chip is chip-level single-piece production rather than wafer-level, and the production efficiency is not high, and the waste of the supporting substrate is also large, so it is not a low-cost solution.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for preparing wafer-level thin-film flip-chip LED chips, which is not limited by epitaxial substrates, and can be directly made into white LED chips, with high production efficiency and low cost.

In order to solve the technical problem of the present invention, the present invention provides a method for preparing a wafer-level thin-film flip-chip LED chip. The method includes sequentially growing a buffer layer, an N-type GaN layer, a multi-quantum well layer, a P-type The GaN layer and the reflective metal layer are etched on the surface of the reflective metal layer to expose the N-type GaN layer to form an N electrode hole and a first trench, and a first insulating layer is deposited on the reflective metal layer, The first insulating layer covers the sidewall of the N electrode hole and the first groove, and a plurality of P electrode holes are formed in a partial area of the first insulating layer covering the reflective metal layer, the The depth of the P electrode hole reaches the reflective metal layer, depositing a current diffusion metal layer on the first insulating layer, and the current diffusion metal layer covers the N electrode hole and the P electrode hole, and the method also includes A plurality of first grooves and second grooves are formed in a part of the current diffusion metal layer, the depth of the first grooves and the second grooves reaches the first insulating layer, and a layer is deposited on the current diffusion metal layer. layering a second insulating layer, the second insulating layer covers the first groove and the second groove and communicates with the first insulating layer, and forms a plurality of second grooves in a partial area of the second insulating layer, The depth of the second groove reaches the current diffusion metal layer, and conductive pillars are prepared on the second insulating layer, and the conductive pillars cover the second groove and are isolated from each other, and are filled around the conductive pillars an insulating material layer, the insulating material layer covers the entire wafer, the insulating material layer on the wafer is planarized to expose the conductive pillars, the growth substrate and the buffer layer are peeled off to expose the N-type GaN layer, Slicing is performed along the trenches to form individual chips.

Preferably, the material of the reflective metal layer is one of the following: Ag, Al, Ni, Ni-Ag alloy, Al-Ni alloy, Ag-Ni-Al alloy.

Preferably, the materials of the first insulating layer and the second insulating layer are one or more of the following: SiO ₂ , SiN, Al ₂ O ₃ .

Preferably, the material of the conductive pillar is one or more of the following materials: metal, semiconductor.

Preferably, the method for preparing the conductive pillar is one or more of the following methods: pressure welding, ball planting, electroplating, and electroless plating.

Preferably, the material of the insulating material layer is one or more of the following: silica gel, water glass, epoxy resin, polyimide, photoresist, plastic.

Preferably, the preparation method further includes roughening the surface of the N-type GaN layer.

Preferably, the preparation method further includes placing a fluorescent film on the surface of the N-type GaN layer to form a white LED chip.

Beneficial effects of the present invention:

The invention provides a method for preparing a wafer-level film flip chip, which has high production efficiency and low cost. The thin-film flip-chip prepared by the method of the invention is free of wiring and is easy to produce white light, which provides a solution for reducing the cost of LED lighting.

Description of drawings

1 to 10 are schematic diagrams of the preparation process of an embodiment of the present invention.

Instructions for identification in the figure:

1 is the growth substrate, 2 is the buffer layer, 3 is the N-type GaN layer, 4 is the multi-quantum well layer, 5 is the P-type GaN layer, 6 is the reflective metal layer, 7 is the first groove, 8 is the N electrode hole , 9 is the first insulating layer, 10 is the P electrode hole, 11 is the current diffusion metal layer, 12 is the first groove, 13 is the second groove, 14 is the second insulating layer, 15 is the second groove, 16 17 is a conductive pillar, and 17 is an insulating material layer.

detailed description

As shown in FIGS. 1 to 10 , the present invention provides a method for preparing wafer-level thin-film flip-chip LED chips.

As shown in FIG. 1 , a buffer layer 2 , an N-type GaN layer 3 , a multi-quantum well layer 4 , a P-type GaN layer 5 and a reflective metal layer 6 are sequentially grown on a growth substrate 1 .

As shown in FIG. 2 , the first groove 7 and the N electrode hole 8 are formed by etching the surface part of the reflective metal layer 6 to expose the N-type GaN layer.

As shown in Figure 3, a layer of first insulating layer 9 is deposited on the reflective metal layer 6, the first insulating layer 9 covers the side walls of the first groove 7 and the N electrode hole 8, and on the reflective metal layer covered A plurality of P electrode holes 10 are formed in a partial area of the first insulating layer 9 on the 6 , and the depth of the P electrode holes 10 reaches the reflective metal layer 6 , as shown in FIG. 4 .

As shown in Figure 5, a current spreading metal layer 11 is deposited on the first insulating layer 9, and the current spreading metal layer 11 covers the N electrode hole 8 and the P electrode hole 10, and the current spreading metal layer 11 A plurality of first grooves 12 and second grooves 13 are formed in some areas, and the depths of the first grooves 12 and second grooves 13 reach the first insulating layer 9 .

As shown in FIG. 6, a second insulating layer 14 is deposited on the current spreading metal layer 11, and the second insulating layer 14 covers the first groove 12 and the second groove 13 so as to communicate with the first insulating layer 9. Part of the second insulating layer 14 forms a second groove 15 , and the depth of the second groove 15 reaches the current diffusion metal layer 11 .

As shown in FIG. 7 , conductive pillars 16 are formed on the second insulating layer 14 by a ball planting method, and the number of conductive pillars 16 matches the number of the second grooves 14 and covers the second grooves 14 .

As shown in FIG. 8 , an insulating material 17 is filled around the metal pillar 16 , and the insulating material 17 covers the entire wafer. As shown in FIG. 9 , the insulating layer material 17 is planarized to expose the metal pillars 15 . The growth substrate 1 and the buffer layer 2 are peeled off to expose the N-type GaN layer, and cut along the trench to form a single chip, as shown in FIG. 10 .

The above is only a specific implementation mode in the present invention, but the scope of protection of the present invention is not limited thereto. Anyone who is familiar with the technology can easily think of changes or replacements within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (8)

1. A method for preparing a wafer-level thin-film flip-chip LED chip, comprising Growing a buffer layer, an N-type GaN layer, a multi-quantum well layer, a P-type GaN layer and a reflective metal layer sequentially on the growth substrate; It is characterized in that an N-electrode hole and a first trench are formed by etching a part of the surface of the reflective metal layer until the N-type GaN layer is exposed; Depositing a first insulating layer on the reflective metal layer, the first insulating layer covers the sidewall of the N electrode hole and the first groove; Forming a plurality of P electrode holes in a partial area of the first insulating layer covering the reflective metal layer, the depth of the P electrode holes reaching the reflective metal layer; Depositing a current spreading metal layer on the first insulating layer, the current spreading metal layer covers the N electrode hole and the P electrode hole; forming a plurality of first grooves and second grooves in a partial region of the current diffusion metal layer, the depth of the first grooves and the second grooves reaching the first insulating layer; Depositing a second insulating layer on the current diffusion metal layer, the second insulating layer covers the first groove and the second groove and communicates with the first insulating layer; forming a plurality of second grooves in a partial region of the second insulating layer, the depth of the second grooves reaching the current diffusion metal layer; preparing conductive pillars on the second insulating layer, the conductive pillars cover the second groove and are isolated from each other; filling an insulating material layer around the conductive pillars, and the insulating material layer covers the entire wafer; performing planarization treatment on the insulating material on the wafer to expose the conductive pillars; Peel off the growth substrate and buffer layer to expose the N-type GaN layer; Slicing is performed along the trenches to form individual chips. 2. A method for preparing a wafer-level thin-film flip-chip LED chip according to claim 1, wherein the material of the reflective metal layer is one of the following: Ag, Al, Ni, Ni-Ag alloy , Al-Ni alloy, Ag-Ni-Al alloy. 3. A method for preparing a wafer-level thin-film flip-chip LED chip according to claim 1, wherein the material of the first insulating layer and the second insulating layer is one or more of the following: SiO _2. SiN, Al ₂ O ₃ . 4. A method for preparing a wafer-level thin-film flip-chip LED chip according to claim 1, wherein the material of the conductive pillar is one or more of the following materials: metal and semiconductor. 5. A method for preparing a wafer-level thin-film flip-chip LED chip according to claim 1, wherein the method for preparing conductive pillars is one or more of the following methods: pressure bonding, ball planting, Electroplating, chemical plating. 6. A method for preparing a wafer-level thin film flip-chip LED chip according to claim 1, wherein the material of the insulating material layer is one or more of the following: silica gel, water glass, epoxy Resins, polyimides, photoresists, plastics. 7 . The method for preparing a wafer-level thin-film flip-chip LED chip according to claim 1 , wherein the method further comprises roughening the surface of the N-type GaN layer. 8. A method for preparing a wafer-level thin-film flip-chip LED chip according to claim 1 or 6, characterized in that the preparation method further comprises placing a fluorescent film on the surface of the N-type GaN layer to make a white LED chip.