TW201807842A - Electrode structure of LED capable of saving cost by reducing use amount of gold - Google Patents

Abstract

The present invention provides an electrode structure of LED, which is applied onto an LED. The structure comprises an adhesive layer and a welding pad layer stacked in sequence, wherein the adhesive layer is stacked on the LED and the welding pad layer is stacked on the adhesive layer. The welding pad layer of the present invention includes at least two first metal layers and at least two second metal layers that are stacked alternately and sequentially, and a gold layer disposed on the outmost side. The first metal layer is selected from a group consisting of aluminum and aluminum alloy. The second metal layer is selected from a group consisting of titanium, nickel, chromium, platinum, palladium, titanium nitride, titanium tungsten, tungsten, rhodium and copper. Thus, the main body structure of the welding pad layer is a stacked structure of the first metal layers and the second metal layers, wherein the first metal layers can be made by cheap materials, and the second metal layers is used to alleviate the problems of electro-migration and difficult wire bonding due to the first metal layer being too soft, so as to greatly reduce the manufacturing cost thereby satisfying the manufacturing requirements.

Description

Electrode structure of light emitting diode

The present invention relates to a light emitting diode, and particularly to an electrode structure of a light emitting diode.

Light Emitting Diodes (LEDs) are mainly made of multiple epitaxial semiconductor materials, taking blue light emitting diodes as an example. It is mainly composed of gallium nitride-based (GaN-based) epitaxial thin film, stacked to form a light-emitting body with a sandwich structure including a N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer. The light-emitting diode can be based on its structure. Divided into horizontal, vertical and flip-chip light-emitting diodes, etc., its main structure includes an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer. The light emitting diode can convert electric energy into light, and in order to input electric energy into the light emitting body of the light emitting diode, a two-electrode structure needs to be provided on the light emitting body to electrically connect the N-type semiconductor layer and the P-type semiconductor layer, respectively.

Please refer to FIG. 1, which is a conventional electrode structure of a light emitting diode, which mainly includes an adhesion layer 1 and a pad layer 2, wherein the adhesion layer 1 includes a chromium layer 1A (18 angstroms), A first metal layer 1B (2500 angstroms) and a second metal layer 1C (500 angstroms), and the pad layer 2 includes a platinum layer 2A (400 angstroms) and a gold layer 2B (18000 angstroms). The bonding pads Layer 2 is used for wire bonding. In order to meet the requirements of wire hardness and reduce electromigration, the thickness of its gold layer 2B must reach 18000 angstroms. Obviously the amount of gold is quite large. This is because the hardness of aluminum is too soft and it is not easy to wire. In addition, electromigration will occur under high current operation; because the cost of gold is much larger than that of aluminum, its manufacturing cost is high.

In order to reduce the manufacturing cost, without changing the photoelectric characteristics of the light-emitting diode (or achieving similar effects), using other materials instead of gold is the current development direction, such as Taiwan Announcement Patent No. I497767, which uses aluminum The alloy method replaces aluminum to solve the electromigration phenomenon under high current operation. However, the characteristics of aluminum alloy are still quite close to aluminum, which can not really meet the hardness requirements when wire bonding, nor can it really solve the electromigration phenomenon.

That is, the main purpose of the present invention is to disclose an electrode structure, which can reduce the amount of gold and save costs.

The invention is an electrode structure of a light emitting diode, which is applied to a light emitting diode and includes an adhesion layer and a pad layer, wherein the adhesion layer is stacked on the light emitting diode, and the pad layer is stacked on The adhesion layer is characterized in that the pad layer has at least two first metal layers, at least two second metal layers, and a gold layer disposed on the outermost side, which are sequentially and alternately stacked. The first metal layer is selected From the group consisting of aluminum and aluminum alloy, the second metal layer is selected from titanium, nickel, chromium, platinum, palladium, titanium nitride, titanium tungsten, tungsten, rhodium, copper (Ti, Ni, Cr, Pt, Pd, TiN, TiW, W, Rh, Cu).

According to this, the main structure of this pad layer is a laminated structure of a first metal layer and a second metal layer. The first metal layer is selected from the group consisting of aluminum and aluminum alloy, and the cost is low, and The second metal layer is selected from the group consisting of titanium, nickel, chromium, platinum, palladium, titanium nitride, titanium tungsten, tungsten, rhodium, and copper. Its hardness is relatively hard, which can improve the softness of the first metal layer. The problem of not being easy to wire and electromigration can greatly reduce the amount of gold. Compared with the conventional structure, it can reduce the manufacturing cost and meet the manufacturing needs.

The detailed content and technical description of the present invention are further described by examples, but it should be understood that these examples are for illustrative purposes only and should not be construed as limitations of the implementation of the present invention.

Please refer to FIG. 2, the present invention is an electrode structure of a light emitting diode, which is applied to a light emitting diode (not shown), and includes an adhesion layer 10 and a pad layer 20, wherein the adhesion layer 10 is stacked on the light-emitting diode, and the pad layer 20 is stacked on the adhesion layer 10, which is characterized in that the pad layer 20 has at least two first metal layers 21 and at least two first Two metal layers 22 and a gold layer 23 disposed on the outermost side. The first metal layer 21 is selected from the group consisting of aluminum and aluminum alloy. The second metal layer 22 is selected from the group consisting of titanium, nickel, chromium, and platinum. , Palladium, titanium nitride, titanium tungsten, tungsten, rhodium, copper (Ti, Ni, Cr, Pt, Pd, TiN, TiW, W, Rh, Cu).

The pad layer 20 may further have a platinum layer 24. The platinum layer 24 of the pad layer 20 is interposed between the second metal layer 22 and the gold layer 23. The adhesion layer 10 may have a chromium layer 11, and the adhesion layer 10 may further include an aluminum layer 12 and a titanium layer 13 sequentially stacked on the chromium layer 11. The adhesion layer 10 is a light emitting diode for adhesion. N-type semiconductor layer or P-type semiconductor layer, to prevent the electrode structure from falling off. It can be used as an N-type electrode or a P-type electrode of a light emitting diode.

Please refer to "Figure 3", "Figure 4" and "Figure 5" for a comparison chart of the efficacy of the electrode structure of the present invention and the conventional electrode structure, wherein the adhesion layer 10 and the pad layer 20 of the electrode structure of the present invention, The structure is shown in FIG. 2. In an embodiment provided by the present invention, the thickness and material of each layer are as follows. The thickness of the chromium layer 11 of the adhesion layer 10 is 18 Angstroms, the thickness of the aluminum layer 12 is 2500 Angstroms, and the titanium layer is as follows. 13 thickness: 500 angstroms. The first metal layer 21 and the second metal layer 22 are made of aluminum and titanium, wherein the thickness of aluminum is 10,000 angstroms and the thickness of titanium is 500 angstroms. The thickness of the platinum layer 24 of the pad layer 20 is 400 angstroms and the thickness of the gold layer 23 is 2000 angstroms.

For the conventional structure, as shown in FIG. 1, the thickness of each layer is in order: chromium layer: 18 angstroms, aluminum layer: 2500 angstroms, titanium layer: 500 angstroms, platinum layer: 400 angstroms, and gold layer: 18000 angstroms.

In the present invention, the aforementioned electrode structure and the conventional electrode structure are respectively used as the N-type electrode and the P-type electrode of the light-emitting diode, and the power consumption and the forward direction under different forward currents are measured. A comparison chart of the curve of voltage (Forward Voltage) and conversion efficiency (Walplugeficiency; WPE), wherein the electrode structure curve of the present invention is A1, A2, A3, and the conventional electrode structure curve is B1, B2, B3.

It can be seen from "Figure 3" that in the power consumption part, the electrode structure curve A1 of the present invention is almost the same as the conventional electrode structure curve B1 at low forward current. As the forward current increases, the power consumption slightly increases, but the difference is Quite limited.

It can be seen from "Figure 4" that in the forward voltage part, the electrode structure curve A2 of the present invention is almost the same as the conventional electrode structure curve B2 at low forward current. As the forward current increases, the forward voltage slightly increases, but The differences are still quite limited.

It can be seen from FIG. 5 that in the conversion efficiency part, the electrode structure curve A3 of the present invention is almost the same as the conventional electrode structure curve B3.

As mentioned above, the present invention allows the main structure of the pad layer to be a laminated structure of a first metal layer and a second metal layer, which can improve the problem that the first metal layer is too soft to be easily wired and electromigrated. Compared with the conventional structure, as shown in Figs. 3 to 5, the amount of gold is small, and the difference in photoelectric characteristics is not large. As far as the embodiment provided by the present invention is concerned, a gold layer with a thickness of 13,000 Angstroms is saved, and the thickness is increased. The thickness of the titanium layer with a thickness of 1000 angstroms and the aluminum layer with a thickness of 20,000 angstroms, after considering the price of the metal, can reduce the manufacturing cost and meet the manufacturing needs.

However, the above are only preferred embodiments of the present invention, and are not intended to limit the scope of implementation of the present invention. That is, all equal changes and modifications made in accordance with the scope of patent application of the present invention are covered by the scope of patent of the present invention.

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1‧‧‧ adhesion layer
1A‧‧‧chrome layer
1B‧‧‧Aluminum layer
1C‧‧‧Titanium layer
2‧‧‧ pad
2A‧‧‧platinum
2B‧‧‧Gold layer invention
A1, A2, A3, B1, B2, B3‧‧‧ electrode structure curve
10‧‧‧ Adhesive layer
11‧‧‧chrome layer
12‧‧‧ aluminum layer
13‧‧‧ titanium layer
20‧‧‧Solder pad layer
21‧‧‧first metal layer
22‧‧‧Second metal layer
23‧‧‧Gold
24‧‧‧platinum

FIG. 1 is a structural diagram of an electrode of a conventional light emitting diode. FIG. 2 is a structural diagram of an electrode of a light emitting diode of the present invention. FIG. 3 is a comparison diagram of power consumption of the present invention and a conventional electrode structure. FIG. 4 is a comparison diagram of forward voltages of the present invention and a conventional electrode structure. FIG. 5 is a comparison diagram of conversion efficiency between the present invention and a conventional electrode structure.

10‧‧‧ Adhesive layer

11‧‧‧chrome layer

12‧‧‧ aluminum layer

13‧‧‧ titanium layer

20‧‧‧Solder pad layer

21‧‧‧first metal layer

22‧‧‧Second metal layer

23‧‧‧Gold

24‧‧‧platinum

Claims (7)

An electrode structure of a light emitting diode is applied to a light emitting diode and includes an adhesion layer and a pad layer, wherein the adhesion layer is stacked on the light emitting diode, and the pad layer is stacked on the adhesion The layer is characterized in that: the pad layer has at least two first metal layers, at least two second metal layers, and a gold layer disposed on the outermost side, which are sequentially and alternately stacked. The first metal layer is selected from the group consisting of A group consisting of aluminum and aluminum alloy, and the second metal layer is selected from the group consisting of titanium, nickel, chromium, platinum, palladium, titanium nitride, titanium tungsten, tungsten, rhodium, and copper. For example, the electrode structure of a light-emitting diode of item 1 of the patent application, wherein the pad layer further has a platinum layer, and the platinum layer of the pad layer is interposed between the second metal layer of the pad layer and the Between the gold layers of the pad layer. For example, the electrode structure of a light emitting diode according to item 1 of the application, wherein the adhesion layer has a chromium layer. For example, the electrode structure of a light emitting diode according to item 3 of the patent application, wherein the adhesion layer further has an aluminum layer and a titanium layer sequentially stacked on the chromium layer. For example, the electrode structure of a light emitting diode according to item 4 of the application, wherein the thickness of the chromium layer of the adhesion layer is 18 angstroms, the thickness of the aluminum layer is 2500 angstroms, and the thickness of the titanium layer is 500 angstroms. For example, the electrode structure of the light-emitting diode of item 1 of the patent application range, wherein the materials of the first metal layer and the second metal layer are selected from aluminum and titanium, wherein the thickness of aluminum is 10,000 angstroms and the thickness of titanium is 500 angstroms. For example, the electrode structure of a light emitting diode according to item 2 of the patent application, wherein the thickness of the platinum layer of the pad layer is 400 angstroms and the thickness of the gold layer is 2000 angstroms.