[0048] The invention provides an LED chip and a manufacturing method thereof. The structure of Ag-TiW-Ti (silver-titanium tungsten-titanium) is used in the reflective layer of the LED chip, and the protection of the silver layer is realized by two metals, titanium tungsten and titanium. Prevents silver leaching and flow, and highly adherent metal enables adhesion to subsequent films. The reflective layer metal structure described in the present invention is suitable for LED chips with flip-chip structure or vertical structure.
[0049] like Figure 3 ~ Figure 6As shown, the LED chip with flip-chip structure and its manufacturing method include the following processes:
[0050] like image 3 As shown, a front-end structure is provided, including a sapphire substrate 10, and an N-GaN layer 11, a quantum well layer 12, and a P- GaN layer 13.
[0051] Form the ohmic contact layer 14 on the surface of the front-end structure, and pattern it to expose the P-GaN layer 13; the material of the ohmic contact layer 14 can be ITO (tin-doped indium oxide) and/or AZO ( aluminum-doped zinc oxide). It can be formed by sputtering (Sputter) or plasma assisted deposition (RPD).
[0052] A reflective layer 15 is formed on the ohmic contact layer 14 and patterned to expose the P-GaN layer 13 corresponding to the opening of the ohmic contact layer 14 . The reflective layer 15 further includes a silver layer 151 formed on the ohmic contact layer 14 by sputtering, a titanium-tungsten layer 152 formed on the silver layer 151, and a titanium layer formed on the titanium-tungsten layer 152. 153. The edge of the silver layer 151 can be slightly retracted, so that the area of the titanium-tungsten layer 152 covered on the silver layer 151 is larger than the silver layer 151 itself, and the titanium layer 153 above can cover the edges of the titanium-tungsten layer 152 and the silver layer 151. Wrapped; the titanium-tungsten layer 152 and the titanium layer 153 can effectively prevent silver precipitation and flow, prevent leakage caused by abnormal silver migration, and achieve adhesion to subsequent films. Titanium metal also functions as a metal tie layer.
[0053] The thickness design of the silver layer 151 needs to take into account the optical ability: the thinnest is to consider the problem of light reflection and the uniformity of film preparation; at the same time, because Ag metal has the characteristics of easy aggregation, when the thickness is too thick, it will aggregate into blocks and cause reflectivity. decline. The thickness design of the titanium-tungsten layer 152 and the titanium layer 153 is mainly based on the consideration of the metal Ag wrapping ability, so a certain thickness is required, but when the thickness is too thick, the stress of the film layer will deteriorate and cause peeling off.
[0054] In this embodiment, the thickness of the silver layer 151 is 1200-2500 Angstroms The thickness of the titanium-tungsten layer 152 is 500-1500 Angstroms The thickness of the titanium layer 153 is 500-1500 Angstroms The above examples are not intended to limit the thickness range of the reflective film.
[0055] like Figure 4 As shown, the exposed P-GaN layer 13 and the quantum well layer 12 form the first electrode contact hole 16 by dry etching and other processes, and the bottom of which extends to the N-GaN layer 11 .
[0056] like Figure 5 As shown, an isolation layer 17 is formed, the isolation layer 17 covers most of the reflective layer 15 and the sidewall of the first electrode contact hole 16 , and an opening is formed in the isolation layer 17 to expose the reflective layer 15 . The material of the isolation layer 17 can be, for example, silicon oxide, which is formed by PECVD in combination with photolithography and BOE etching techniques, so as to protect the etched frame.
[0057] like Image 6 As shown, a first electrode 18 is formed in the first electrode contact hole 16; a second electrode 19 connected to the reflective layer 15 is formed at the opening of the isolation layer 17; the first electrode 18 and the second electrode 19 It can be formed by E-beam/sputtering using negative resist removal techniques. The first electrode 18 and the second electrode 19 are used for bonding with a packaging substrate (not shown).
[0058] Obtain the flip-chip LED chip of the present invention, comprising:
[0059] A sapphire substrate 11, an N-GaN layer 11, a quantum well layer 12, and a P-GaN layer 13 formed sequentially on the front surface of the sapphire substrate 11; an ohmic contact layer 14 formed on the P-GaN layer 13; A reflective layer 15 formed on the ohmic contact layer 14; the reflective layer 15 further includes a silver layer 151, a titanium-tungsten layer 152, and a titanium layer 153; through the reflective layer 15, the ohmic contact layer 14, and the P-GaN layer 13 and the first electrode contact hole 16 of the quantum well layer 12; the first electrode 18 is formed in the first electrode contact hole 16, and is connected with the N-GaN layer 11; the second electrode 19 is connected to the reflective layer 15 connected.
[0060] like Figure 7 ~ Figure 9 As shown, the vertically structured LED chip and its manufacturing method include the following processes:
[0061] like Figure 7 As shown, a front-end structure is provided, and the front-end structure includes a growth substrate 20-1, usually a sapphire substrate, a Si (silicon) substrate, a SiC (silicon carbide) substrate or a patterned substrate; A UID (unintentionally doped)-GaN buffer layer 20 is formed on the bottom 20-1.
[0062] An epitaxial layer is formed on the UID-GaN buffer layer 20 , and the epitaxial layer includes an N-GaN layer 21 , a quantum well layer 22 and a P-GaN layer 23 which are sequentially formed.
[0063] An ohmic contact layer 24 is formed on the P-GaN layer 23, and the ohmic contact layer 24 is a transparent conductive film made of AZO, ITO or ZnO (zinc oxide).
[0064] A reflective layer 25 is formed on the ohmic contact layer 24 , and the reflective layer 25 further includes a silver layer 251 , a titanium-tungsten layer 252 , and a titanium layer 253 sequentially formed by sputtering. The edge of the silver layer 251 can be slightly retracted, so that the area of the titanium-tungsten layer 252 covered on the silver layer 251 is larger than that of the silver layer 251 itself, and the titanium layer 253 on the top can cover the edges of the titanium-tungsten layer 252 and the silver layer 251. Wrapped up; the titanium-tungsten layer 252 and the titanium layer 253 can effectively prevent silver precipitation and flow, and achieve adhesion to subsequent films.
[0065] In this embodiment, the thickness of the silver layer 251 is 1200-2500 Angstroms The thickness of the titanium-tungsten layer 252 is 500-1500 Angstroms The thickness of the titanium layer 253 is 500-1500 Angstroms The above examples are not intended to limit the thickness range of the reflective film.
[0066] A metal bonding layer 26 is formed on the radiation layer 25, and its material is Au-Au (gold-gold) or Au-Sn (gold-tin).
[0067] Form bonding substrate 27 on described metal bonding layer 26; The material of described bonding substrate 27 is Si, WCu (tungsten copper alloy) or MoCu (molybdenum copper alloy), described metal bonding layer 26 and The bonded substrates 27 are bonded using a high temperature bonding method.
[0068] like Figure 8 As shown, the growth substrate 20 - 1 is removed by laser lift-off, exposing the UID-GaN buffer layer 20 .
[0069] like Figure 9 As shown, the UID-GaN buffer layer 20 is etched entirely or patterned to expose the N-GaN layer 21 . A first electrode 28 is formed on the surface of the N-GaN layer 21 by evaporation process, which is in ohmic contact with the N-GaN layer 21 and used for conducting electricity. Wherein, the material of the first electrode 28 is Ni (nickel), Au, Al (aluminum), Ti, Pt, Cr (chromium), Ni/Au alloy, Al/Ti/Pt/Au alloy or Cr/Pt/ Au alloy.
[0070] Obtain the vertical structure LED chip of the present invention, comprising:
[0071] Bonding substrate 27 , metal bonding layer 26 , reflective layer 25 , ohmic contact layer 24 , P-GaN layer 23 , quantum well layer 22 , and N-GaN layer 21 . The reflective layer 25 includes a silver layer 251 , a titanium-tungsten layer 252 , and a titanium layer 253 . The first electrode 28 is connected to the N-GaN layer 21 .
[0072] The present invention does not limit the existing processing technology of flip-chip structure and vertical structure LED chips, and can be combined with the present invention according to actual application conditions. For example, surface roughening treatment is performed on the light-emitting surface to increase its surface area and improve light-emitting efficiency.
[0073] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as limiting the present invention. Various modifications and alterations to the present invention will become apparent to those skilled in the art upon reading the above disclosure. Therefore, the protection scope of the present invention should be defined by the appended claims.
