CN107527974B - A kind of LED electrode structure conducive to bonding wire - Google Patents

Abstract

The present invention provides a kind of LED electrode structure conducive to bonding wire and using the light emitting diode of the LED structure, wherein the LED electrode structure successively includes ohmic contact layer and welding layer, the ohmic contact layer is arranged on epitaxial layer, the barrier layer is arranged on the ohmic contact layer, the welding layer is arranged on the barrier layer, and the welding layer successively includes thick layer gold, alloy-layer and thin layer gold from bottom to up.LED electrode structure of the present invention is designed using multilayer aluminum alloy anode structure so that Al activity is controlled very well, electrode surface is precipitated without Al element, both production cost is reduced, it ensure that preferable encapsulation bonding wire quality simultaneously, pattern structure is increased in electrode structure, reinforce the cementability between every layer of aluminium alloy and upper and lower layer gold, is conducive to subsequent routing operation.

Description

An LED electrode structure that is beneficial for wire bonding

technical field

The invention belongs to the technical field of LED chips, and in particular relates to an LED electrode structure that is beneficial for wire bonding.

Background technique

Light Emitting Diode (LED for short) has good optoelectronic properties such as low energy consumption, long life, good stability, small size, fast response speed and stable emission wavelength, and is widely used in lighting, home appliances, display screens and indicator lights, etc. field.

Most of the electrode structures of light-emitting diodes use gold as the main evaporation material, and gold is widely used because of its good thermal conductivity, ductility and other advantages. With the large-scale development of the general lighting field, the high cost of gold has gradually become a prominent problem, and it is necessary to find a low-cost metal that can replace gold as the main material of LED electrodes. Metal aluminum is used because of its low production cost and good metal properties, but at the same time, the electrode structure made of metal aluminum is easily oxidized in the air due to its own reasons. It is not easy, and abnormal phenomena such as inability to bond wires, solder balls falling off, and extrusion of aluminum often occur. Therefore, it is urgent to design an improved aluminum alloy electrode structure to overcome the deficiencies in the prior art.

SUMMARY OF THE INVENTION

In view of this, the present invention aims to provide an LED electrode structure that is beneficial for bonding wires, so as to solve the problems of diffusion and oxidation of aluminum electrodes in the LED electrode manufacturing process, and greatly improve the quality of subsequent LED packaging bonding wires.

In order to achieve the above object, the technical scheme of the present invention is achieved in this way:

An LED electrode structure for wire bonding, comprising an ohmic contact layer and a soldering layer, the ohmic contact layer is arranged on the epitaxial layer, the barrier layer is arranged on the ohmic contact layer, and the soldering layer is arranged on the Above the barrier layer, the soldering layer sequentially includes a first gold layer, an alloy layer and a second gold layer from bottom to top, wherein the first gold layer is a thick gold layer, and the second gold layer is a thin gold layer, namely the first gold layer. The thickness of the first gold layer is greater than the thickness of the second gold layer.

Preferably, the LED electrode structure further includes a barrier layer disposed between the ohmic contact layer and the solder layer.

Preferably, the aluminum composition of the alloy layer gradually decreases from bottom to top.

Preferably, the upper surface of the thick gold layer is a patterned structure.

Preferably, the alloy layer includes multiple aluminum alloy layers, and the alloy layer includes at least three aluminum alloy layers.

Preferably, the aluminum content in each of the aluminum alloy layers is greater than 50% wt and less than 100% wt.

Preferably, the aluminum content in each of the aluminum alloy layers gradually decreases from bottom to top.

Preferably, the upper surface of the aluminum alloy layer close to the thin gold layer has a patterned structure.

Preferably, the thickness ratio of the thick gold layer, the alloy layer and the thin gold layer is 1-1.5:6-7:2.5-3, for example, the ratio is 1:6:3.

Preferably, a passivation layer is provided on the periphery of the ohmic contact layer, the barrier layer and the welding layer.

The present invention also provides a light emitting diode structure including any one of the above electrode structures.

Compared with the prior art, the LED electrode structure for wire bonding according to the present invention has the following advantages:

(1) The LED electrode structure of the present invention, which is beneficial for wire bonding, utilizes the multi-layer aluminum alloy electrode structure design, so that the Al activity is well controlled, and there is no Al element precipitation on the electrode surface, which not only reduces the production cost, but also ensures a relatively high efficiency. Good package wire quality.

(2) A patterned structure is added to the LED electrode structure for wire bonding according to the present invention, which strengthens the adhesion between each layer of aluminum alloy and the upper and lower gold layers, which is beneficial to subsequent wire bonding operations.

Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the description, claims and drawings.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification, and are used to explain the present invention together with the embodiments of the present invention, and do not constitute a limitation to the present invention. Furthermore, the figures in the figures are descriptive summaries and are not drawn to scale.

FIG. 1 is a schematic diagram of a structure of an LED electrode for wire bonding according to an embodiment of the present invention.

FIG. 2 is a schematic structural diagram of Embodiment 3. FIG.

FIG. 3 is a schematic structural diagram of Embodiment 4. FIG.

Description of reference numbers:

100-epitaxial layer; 101-ohmic contact layer; 102-barrier layer; 103-soldering layer; 104-thick gold layer; 105-alloy layer; 106-thin gold layer; 107-first aluminum alloy layer; 107a-first 107b-second layer; 108-second aluminum alloy layer; 108a-third layer; 108b-fourth layer; 109-third aluminum alloy layer; 109a-fifth layer; 109b-th layer Six layers; 110 - Passivation layer.

Detailed ways

It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict.

In the description of the present invention, it should be understood that the orientations or positional relationships indicated by "up", "down", "front", "rear", "left", "right", etc. are based on the orientations shown in the drawings Or the positional relationship is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the invention. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

Referring to FIG. 1 , the following embodiment discloses an LED electrode structure using bonding wires, and the overall electrode structure can be prepared by evaporation. In a preferred implementation, the LED electrode structure includes an ohmic contact layer 101, a barrier layer 102 and a soldering layer in sequence, and the soldering layer 103 includes a thick gold layer 104, an alloy layer 105 and a thin gold layer 106, wherein the alloy layer 105 is provided with three layers of aluminum The alloy layers are the first aluminum alloy layer 107 , the second aluminum alloy layer 108 and the third aluminum alloy layer 109 respectively. The thick gold layer 104 and the third aluminum alloy layer 109 are all patterned structures, which are beneficial to the thick gold layer 104 , The bonding between the alloy layer 105 and the thin gold layer 106 can effectively reduce the phenomenon that the wire is dropped and the electrode is dropped. The patterned structure can be set into different patterns according to the actual situation, which will have an impact on the firmness of the bonding between metals, and can be designed flexibly.

The material of the ohmic contact layer 101 can be metal Cr, which is beneficial to the bonding between the epitaxial layer 100 and the electrode structure; the material of the barrier layer 102 is one of metals such as Ti/Pt/Ni/W/TiW, which can block the welding layer 103 Diffusion with the ohmic contact layer 101; the welding layer 103 adopts a multi-layer structure, and an aluminum alloy structure is introduced into the original gold electrode, which improves the strength of the electrode, enhances the overall stability, and greatly improves the weldability of the welding layer 103. ; Aluminum alloy can be made of one element or combination of aluminum and copper, magnesium, germanium, and silicon. The content is gradually reduced. The introduction of copper, magnesium, germanium and silicon elements can enhance the strength of aluminum electrodes, reduce the oxidation rate of aluminum metal, and reduce the cost of gold electrodes. The aluminum alloy itself also has good ductility and stability.

The arrangement of the passivation layer 110 can further reduce the oxidation rate of the electrode structure, protect the circumferential side of the electrode structure, effectively reduce the oxidation rate of the aluminum alloy layer, ensure the quality of subsequent wire bonding and prolong the life of the electrode structure. Preferably, the thickness ratio of the thin gold layer 106, the alloy layer 105 and the thick gold layer 104 is 1-1.5:6-7:2.5-3.

Example 1

An ohmic contact layer 101 and a barrier layer 102 are sequentially prepared on the epitaxial layer 100 by evaporation. The material of the ohmic contact layer 101 is Cr, the material of the barrier layer 102 is Pt, the thickness of the ohmic contact layer 101 is preferably 250-300 angstroms, and the barrier layer 102 The thickness is preferably 300-400 angstroms, and then a thick gold layer 104 is vapor-deposited on the barrier layer 102, and the thickness of the thick gold layer 104 is preferably 600-700 angstroms; on the thick gold layer 104, an aluminum alloy layer is evaporated in stages, and the first aluminum The thickness of the alloy layer 107 is preferably 400-450 angstroms, which is an Al/Si alloy, the Si content is 0.5wt%, and the other is Al; the thickness of the second aluminum alloy layer 108 is preferably 400-450 angstroms, which is an Al/Mg alloy, and the Mg content is The thickness of the third aluminum alloy layer 109 is preferably 400-450 angstroms, which is an Al/Cu alloy, the Cu content is 1.5wt%, and the other is Al; the third aluminum alloy layer 109 is evaporated thinly The gold layer 106, the thickness of the thin gold layer 106 is preferably 200-230 angstroms; finally, the passivation layer 110 is prepared by photolithography and etching.

Example 2

An ohmic contact layer 101 and a barrier layer 102 are sequentially prepared on the epitaxial layer 100 by evaporation. The material of the ohmic contact layer 101 is Cr, the material of the barrier layer 102 is Ti, the thickness of the ohmic contact layer 101 is preferably 270-300 angstroms, and the barrier layer 102 The thickness is preferably 330-400 angstroms, and then a thick gold layer 104 is evaporated on the barrier layer 102, and the thickness of the thick gold layer 104 is preferably 630-700 angstroms; on the thick gold layer 104, an aluminum alloy layer is evaporated in stages, and the first aluminum The thickness of the alloy layer 107 is preferably 420-450 angstroms, which is an Al/Si alloy, the content of Si is 0.5wt%, and the other is Al; the thickness of the second aluminum alloy layer 108 is preferably 420-450 angstroms, which is an Al/Mg alloy, and the content of Mg is The thickness of the third aluminum alloy layer 109 is preferably 420-450 angstroms, which is Al/Ge alloy, the Ge content is 1.5wt%, and the other is Al; The gold layer 106, the thickness of the thin gold layer 106 is preferably 210-230 angstroms; finally, the passivation layer 110 is prepared by photolithography and etching.

Example 3

Referring to FIG. 2 , an ohmic contact layer 101 and a barrier layer 102 are sequentially prepared on the epitaxial layer 100 by evaporation. The material of the ohmic contact layer 101 is Cr, the material of the barrier layer 102 is Ti, and the thickness of the ohmic contact layer 101 is preferably 270- 300 angstroms, the thickness of the barrier layer 102 is preferably 330-400 angstroms, and then a thick gold layer 104 is evaporated on the barrier layer 102, and the thickness of the thick gold layer 104 is preferably 630-700 angstroms; An aluminum alloy layer, the thickness of the first aluminum alloy layer 107 is preferably 420-450 angstroms, the first aluminum alloy layer 107 is evaporated twice, the alloy material is Al/Si alloy, and the Si content in the first layer 107a is 0.3wt %, the other is Al, the Si content in the second layer 107b is 0.5wt%, and the other is Al; the thickness of the second aluminum alloy layer 108 is preferably 420-450 angstroms, the second aluminum alloy layer 108 is evaporated twice, The material is Al/Mg alloy, the Mg content in the third layer 108a is 1wt%, the other is Al, the Mg content in the fourth layer 108b is 1.2wt%, and the other is Al; the thickness of the third aluminum alloy layer 109 is preferably 420 -450 angstroms, the third aluminum alloy layer 109 is vapor-deposited in two times, the alloy material is Al/Ge alloy, the Ge content in the fifth layer 109a is 1.5wt%, and the others are Al, and the Ge content in the sixth layer 109b A thin gold layer 106 is evaporated on the third aluminum alloy layer 109, and the thickness of the thin gold layer 106 is preferably 210-230 angstroms; finally, a passivation layer 110 is prepared by photolithography and etching.

Example 4

Please refer to FIG. 3 , which is a light emitting diode including the electrode structure of the present invention, an epitaxial layer 100 is formed on a substrate 1 by epitaxial growth, and the substrate 1 can be a common substrate material in the prior art such as sapphire or gallium arsenide, The epitaxial layer 100 includes an N-type layer, an active layer and a P-type layer. An ohmic contact layer 101 and a barrier layer 102 are sequentially prepared on the epitaxial layer 100 by evaporation. The material of the ohmic contact layer 101 is Cr, and the material of the barrier layer 102 is Ti. , the thickness of the ohmic contact layer 101 is preferably 270-300 angstroms, the thickness of the barrier layer 102 is preferably 330-400 angstroms, and then a thick gold layer 104 is evaporated on the barrier layer 102, and the thickness of the thick gold layer 104 is preferably 630-700 angstroms; On the thick gold layer 104, multiple layers of aluminum alloy layers are evaporated in stages, the thickness of the first aluminum alloy layer 107 is preferably 420-450 angstroms, the first aluminum alloy layer 107 is evaporated in two steps, and the alloy material is Al/Si alloy. The Si content in the first layer 107a is 0.3wt%, the other is Al, the Si content in the second layer 107b is 0.5wt%, and the other is Al; the thickness of the second aluminum alloy layer 108 is preferably 420-450 angstroms, the second aluminum The alloy layer 108 is evaporated twice, the alloy material is an Al/Mg alloy, the Mg content in the third layer 108a is 1wt%, the others are Al, the Mg content in the fourth layer 108b is 1.2wt%, and the others are Al; The thickness of the third aluminum alloy layer 109 is preferably 420-450 angstroms, the third aluminum alloy layer 109 is evaporated twice, the alloy material is Al/Ge alloy, the Ge content in the fifth layer 109a is 1.5wt%, and the others are Al, the Ge content in the sixth layer 109b is 2.0wt%, and the others are Al; a thin gold layer 106 is vapor-deposited on the third aluminum alloy layer 109, and the thickness of the thin gold layer 106 is preferably 210-230 angstroms; finally, by photolithography and etching to prepare the passivation layer 110 .

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the within the scope of protection of the present invention.

Claims (9)

1. An LED electrode structure conducive to wire bonding, comprising an ohmic contact layer, a barrier layer and a soldering layer, characterized in that: the ohmic contact layer is arranged on the epitaxial layer of the LED, and the barrier layer is arranged on the ohmic layer On the contact layer, the soldering layer is arranged on the barrier layer, and the soldering layer sequentially includes a first gold layer, an alloy layer and a second gold layer from bottom to top, wherein the thickness of the first gold layer is greater than that of the second gold layer The thickness of the gold layer, the aluminum component of the alloy layer gradually decreases from bottom to top. 2 . The LED electrode structure according to claim 1 , wherein the upper surface of the first gold layer is a patterned structure. 3 . 3 . The LED electrode structure of claim 1 , wherein the alloy layer comprises multiple layers of aluminum alloy, and the alloy layer comprises at least three layers of aluminum alloy. 4 . 4 . The LED electrode structure according to claim 3 , wherein the aluminum content in each aluminum alloy layer is greater than 50% wt and less than 100% wt. 5 . 5 . The LED electrode structure of claim 3 , wherein the aluminum content in each of the aluminum alloy layers gradually decreases from bottom to top. 6 . 6 . The LED electrode structure of claim 3 , wherein the upper surface of the aluminum alloy layer close to the second gold layer is a patterned structure. 7 . 7 . The LED electrode structure according to claim 1 , wherein the thickness ratio of the second gold layer, the alloy layer and the first gold layer is 1-1.5:6. 8 . -7:2.5-3. 8 . The LED electrode structure according to claim 1 , wherein a passivation layer is provided on the periphery of the ohmic contact, the barrier layer and the welding layer. 9 . 9. A light emitting diode, comprising an LED electrode structure according to any one of claims 1-8.