TW201813131A - Light emitting diode structure and manufacturing method thereof - Google Patents

Abstract

A light emitting diode (LED) structure includes a substrate, a metal material layer, a first metal film layer, a second metal film layer and a LED chip. The metal material layer is disposed on the substrate and has a first layer region, a second layer region and a third layer region. The second layer region is located between the first layer region and the third layer region. A melting point of the second layer region is higher than 110 DEG C and lower than 280 DEG C. The first layer region and the third layer region are with the melting point higher than 350 DEG C. The second metal film layer is located between the substrate and the third layer region. The LED chip is disposed on the first metal film layer. The first metal film layer is located between the LED chip and the first layer region.

Description

Light-emitting diode structure and manufacturing method thereof

The present invention relates to a semiconductor structure and a method of fabricating the same, and more particularly to a light emitting diode structure and a method of fabricating the same.

The technology of bonding a Light Emitting Diode (LED) wafer to a lead frame has been developed for many years. According to the different solid crystal materials, it can be roughly divided into two types: the first one is a polymer conductive adhesive, and The second type is a metal welding material.

In the case of polymer conductive adhesives, since the colloidal material is used as the solid crystal bonding material of the light-emitting diode wafer, the heat resistance and thermal conductivity of the gel material are not good and the joint strength is insufficient, so that the high temperature or high current is high. Operating in an environment, it is brittle and the lifetime of the LED chip is reduced.

In the case of metal solder materials, it is mainly through a eutectic bonding technique for the solid crystal process. Since the operating temperature of the metal soldering material belongs to a high temperature, that is, between 280 ° C and 320 ° C, the problem that the light emitting diode wafer is susceptible to thermal stress residual or thermal stress concentration during the solid crystal is formed, thereby affecting the subsequent products. Structural reliability. Furthermore, the cost of the metal solder material is high, and when applied to a plastic substrate, the plastic substrate is liable to cause yellowing and light absorption.

The invention provides a light emitting diode structure which has better structural reliability.

The light emitting diode structure of the present invention comprises a substrate, a metal material layer, a first metal film layer, a second metal film layer and a light emitting diode chip. The metal material layer is disposed on the substrate and has a first layer region, a second layer region, and a third layer region. The second layer region is located between the first layer region and the third layer region, wherein the melting point of the second layer region is higher than 110 ° C and lower than 280 ° C, and the melting point of the first layer region and the melting point of the third layer region are higher than 350 ° C. The first metal thin film layer is disposed on the first layer region of the metal material layer. The second metal thin film layer is disposed on the substrate and located between the substrate and the third layer region of the metal material layer. The light emitting diode chip is disposed on the first metal thin film layer, wherein the first metal thin film layer is located between the light emitting diode wafer and the first layer region of the metal material layer.

In an embodiment of the invention, the material of the first metal thin film layer and the material of the second metal thin film layer include silver, gold, nickel or copper.

In an embodiment of the invention, the first layer region of the metal material layer is a first intermetallic layer region, and the third layer region of the metal material layer is a second intermetallic layer region. The material of the first dielectric layer region and the material of the second dielectric layer region include gold iridium, silver tin, nickel iridium, nickel tin or copper tin.

In an embodiment of the invention, the second layer region of the metal material layer comprises at least one alloy layer region, and the material of the second layer region comprises tin antimony, tin antimony silver, tin antimony silver copper or tin antimony silver crucible. .

In an embodiment of the invention, the second layer region of the metal material layer is a metal laminate region, wherein at least one germanium layer is present.

In an embodiment of the invention, the second layer region of the metal material layer is a metal laminate region in which at least one tin layer is present.

In an embodiment of the invention, the substrate comprises a lead frame, a printed circuit board, a ceramic substrate, a plastic substrate, an alumina substrate or an aluminum nitride substrate.

In an embodiment of the invention, the metal material layer has a thickness of between 0.5 micrometers and 5 micrometers.

In an embodiment of the invention, the thickness of the first metal thin film layer and the thickness of the second metal thin film layer are between 0.3 micrometers and 3 micrometers.

In an embodiment of the invention, the light emitting diode chip is a horizontal light emitting diode chip, a vertical light emitting diode chip or a flip chip light emitting diode chip.

Based on the above, since the melting point of the second layer region in the metal material layer of the present invention is higher than 110 ° C and lower than 280 ° C, it is lower than the conventional solid crystal melting point (280 ° C to 320 ° C) of the metal solder material. Therefore, the light-emitting diode structure of the present invention is less prone to thermal stress residual or thermal stress concentration during the die bonding process, and can have better structural reliability. Furthermore, since the metal material layer, the first metal thin film layer and the second metal thin film layer between the light-emitting diode wafer and the substrate are all made of a metal material, the light-emitting diode structure of the present invention can have better heat dissipation. And thermal conductivity. In addition, the first layer region and the third layer region in the metal material layer of the present invention can increase the adhesion between the metal material layer and the first metal film layer and the second metal film layer, so that the light emitting diode structure has better structure. Structural reliability, and since the melting points of the first layer region and the third layer region in the metal material layer of the present invention are higher than 350 ° C, even if the light emitting diode structure of the present invention is used at a high temperature (greater than 90 degrees C) In the environment, the metal material layer does not appear to soften and affect the alignment accuracy of the substrate and the LED wafer.

The above described features and advantages of the invention will be apparent from the following description.

1 is a cross-sectional view showing a structure of a light emitting diode according to an embodiment of the present invention. Referring to FIG. 1 , in the embodiment, the LED structure 100 includes a substrate 110 , a metal material layer 120 , a first metal film layer 130 , a second metal film layer 140 , and a light emitting diode chip . 150.

In detail, the metal material layer 120 is disposed on the substrate 110 and has a first layer region 122, a second layer region 124, and a third layer region 126. The second layer region 124 is located between the first layer region 122 and the third layer region 126. In particular, the melting point of the second layer region 124 is higher than 110 ° C and lower than 280 ° C, and the melting point and the melting point of the first layer region 122 The melting point of the three-layer region 126 is higher than 350 °C. The first metal thin film layer 130 is disposed on the first layer region 122 of the metal material layer 120. The second metal thin film layer 140 is disposed on the substrate 110 and located between the substrate 110 and the third layer region 126 of the metal material layer 120. The light emitting diode chip 150 is disposed on the first metal thin film layer 130, wherein the first metal thin film layer 130 is located between the light emitting diode wafer 150 and the first layer region 122 of the metal material layer 120.

In the present embodiment, the substrate 110 is, for example, a lead frame, a printed circuit board, a ceramic substrate, a plastic substrate, an alumina substrate, or an aluminum nitride substrate. The first metal thin film 130 may be plated on the surface of the light emitting diode wafer 150 by plating, sputtering, or evaporation. Here, the material of the first metal thin film layer 130 includes silver, gold, nickel, copper or a combination thereof, and the thickness D2 of the first metal thin film layer 130 is, for example, between 0.3 μm and 3 μm. The second metal film 140 may be plated on the surface of the substrate 110 by plating, sputtering, or evaporation. Here, the material of the second metal thin film layer 140 includes silver, gold, nickel, copper or a combination thereof, and the thickness D3 of the second metal thin film layer 140 is, for example, between 0.3 μm and 3 μm.

In particular, the second layer region 124 of the metal material layer 120 of the present embodiment is a metal lamination region or an alloy layer region, wherein the material of the second layer region 124 is, for example, tin antimony, tin antimony silver, tin antimony silver copper. Or tin enamel silver enamel. For example, the second layer region 124 may be a layer of tin-bismuth alloy, or a laminated structure of a tantalum layer and a tin-bismuth alloy, or a two-layer metal comprising a tin layer and a tantalum layer. Stack layer structure. When the second layer region 124 is a metal layered layer structure in which a tin layer and a tantalum layer are laminated, the thickness of each metal layer in the metal layer stack is substantially the same. The first layer region 122 of the metal material layer 120 of the present embodiment is a first intermetallic layer region, and the third layer region 126 of the metal material layer 120 is a second intermetallic layer region, wherein the first intermetallic layer region The material of the material and the second metal layer region includes gold bismuth, silver tin, nickel bismuth, nickel tin or copper tin or a combination thereof. Here, the thickness D1 of the metal material layer 120 is between 0.5 μm and 5 μm. In addition, the LED chip 150 of the present embodiment is a horizontal LED chip, a vertical LED chip, or a flip-chip LED chip, which is not limited herein.

More specifically, the metal material layer 120 is formed of a layer of a solid crystal material having the same material and characteristics as the second layer region 124. The step of forming the metal material layer 120 is as follows. First, a layer of a solid crystal material is formed on the first metal thin film layer 130 or the second metal thin film layer 140 by plating, evaporation, or sputtering. Then, the solid crystal material layer is heated at a first reaction temperature for a reaction time, and a first intermetallic layer region and a second portion are formed between the first metal thin film layer 130, the solid crystal material layer and the second metal thin film layer 140, respectively. Intermetallic layer area. Wherein, the first reaction temperature is, for example, higher than 110 ° C and lower than 280 ° C, and the reaction time is, for example, 60 seconds to 120 seconds, and the heating may be performed by reflow furnace heating, laser heating or infrared heating. The above steps are a pre-fixing process, and the purpose is to form a first dielectric layer region and a second dielectric layer region, and the positional relationship between the LED wafer 150 and the substrate 110 can be preliminarily fixed in advance. Conducive to the subsequent process. Furthermore, since the pre-solid reaction time is short, the light-emitting diode wafer 150 does not cause thermal stress concentration or thermal stress residual. Thereafter, the solid crystal material layer, the first dielectric layer region, and the second dielectric layer region are heated at a second reaction temperature for a curing time to form the first layer region 122, the second layer region 124, and the third layer region. A layer of metallic material 120 of 126. Wherein, the second reaction temperature is, for example, 80 ° C to 120 ° C, and the curing time is 30 minutes to 3 hours, and the heating may be performed by oven heating, hot plate heating or infrared heating. The purpose of the above steps is to allow the metal element or alloying element of the layer of the solid crystal material to diffuse with the elements of the first metal thin film layer 130 and the second metal thin film layer 140. That is, the first layer region 122 and the third layer region 126 of the metal material layer 120 change with the material composition of the first metal film layer 130 and the second metal film layer 140. Therefore, the materials of the first metal film layer 130 and the second metal film layer 140 may be the same or different, and the materials of the first layer region 122 and the third layer region 126 may be the same or different.

The first layer region 122 and the third layer region 126 formed after being heated by the second reaction temperature can increase the adhesion between the metal material layer and the first metal film layer and the second metal film layer, so that the structure of the light emitting diode is relatively The structural reliability is good, and since the melting points of the first layer region 122 and the third layer region 126 of the metal material layer 120 are higher than 350 ° C, the subsequent light emitting diode structure 100 is used in a high temperature (for example, greater than 90 ° C) environment. When the metal material layer 120 is not softened, the alignment relationship between the substrate 110 and the LED wafer 150 can be maintained, so that the LED structure 100 has better light extraction efficiency. Furthermore, the melting point of the second layer region 124 in the metal material layer 120 is higher than 110 ° C and lower than 280 ° C, which is lower than the conventional solid crystal melting point (280 ° C to 320 ° C) of the metal solder material. The light-emitting diode structure 100 of the embodiment is less prone to thermal stress residual or thermal stress concentration, and may have better structural reliability. In addition, since the metal material layer 120, the first metal thin film layer 130, and the second metal thin film layer 140 between the light emitting diode wafer 150 and the substrate 110 are all made of a metal material, the light emitting diode structure 100 of the present embodiment is used. It can have better heat dissipation and heat conduction effects.

In summary, since the melting point of the second layer region in the metal material layer of the present invention is higher than 110 ° C and lower than 280 ° C, the solid crystal melting point (280 ° C to 320 ° C) of the metal welding material is conventionally used. Therefore, the light-emitting diode structure of the present invention is less prone to thermal stress residual or thermal stress concentration, and can have better structural reliability. Furthermore, since the metal material layer, the first metal thin film layer and the second metal thin film layer between the light-emitting diode wafer and the substrate are all made of a metal material, the light-emitting diode structure of the present invention can have better heat dissipation. And thermal conductivity. In addition, since the melting points of the first layer region and the third layer region in the metal material layer of the present invention are higher than 350 ° C, even if the light emitting diode structure of the present invention is used in an environment of high temperature (greater than 90 ° C), The metal material layer also does not appear to soften and affect the alignment accuracy of the substrate and the LED wafer.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

100‧‧‧Lighting diode structure

110‧‧‧Substrate

120‧‧‧Metal material layer

122‧‧‧First floor

124‧‧‧Second floor

126‧‧‧ third floor

130‧‧‧First metal film layer

140‧‧‧Second metal film layer

150‧‧‧Light Diode Wafer

D1, D2, D3‧‧‧ thickness

1 is a cross-sectional view showing a structure of a light emitting diode according to an embodiment of the present invention.

Claims (10)

A method for fabricating a light emitting diode structure, comprising: providing a light emitting unit, the light emitting unit comprising a light emitting diode chip and a first metal film layer, wherein the first metal film layer is disposed on the light emitting diode chip Providing a carrier board, the carrier board includes a substrate and a second metal film layer, the second metal film is disposed on the substrate; and a solid crystal material is disposed on the first metal film layer or disposed on the first metal film layer The die attaching material comprises a metal laminate, wherein the metal laminate comprises at least one tin-containing first metal material layer and at least one second metal material layer containing a metal capable of forming an alloy with tin. And the first metal material layer is different from the second metal material layer, wherein the metal layer has a thickness greater than a thickness of the first metal film layer or the second metal film layer, and a melting point of the metal layer is lower than the a melting point of the first metal thin film layer or the second metal thin film layer; placing the light emitting unit on the carrier plate; heating the solid crystal material at a first reaction temperature; and the solid crystal material and the first Forming a first intermetallic layer between the metal thin film layers; forming a second intermetallic layer between the solid crystal material and the second metal thin film layer, wherein the first reaction temperature is not lower than forming the first intermetallic metal a temperature of the layer or a temperature at which the second metal layer is formed; and heating the layer of the die bond material, the first dielectric layer, and the second dielectric layer at a second reaction temperature. The method for manufacturing a light-emitting diode structure according to claim 1, wherein the first reaction temperature is between 110 ° C and 280 ° C, and the reaction time is between 60 seconds and 120 seconds, and the second reaction temperature is between 80 ° C to 120 ° C, and the reaction time is between 30 minutes and 3 hours. The method for manufacturing a light-emitting diode structure according to claim 1, wherein the material of the first metal layer has at least a first material included in the first metal film layer and the metal layer is included in the metal layer a second material different from the second material, the second metal layer material having at least a third material included in the second metal film layer and a first layer included in the metal layer Four materials, the third material is different from the fourth material. The method for fabricating a light-emitting diode structure according to claim 1, wherein the material of the first metal thin film layer or the second metal thin film layer comprises silver, gold, nickel, copper or a combination thereof. The method for fabricating a light-emitting diode structure according to claim 1, wherein the material of the metal layer comprises a layer of tantalum laminated with a tin-bismuth alloy or a stack of a layer of tin and a layer of tantalum. Layer structure. The method for fabricating a light-emitting diode structure according to claim 1, wherein the metal laminate comprises a laminated structure of a tin layer and an alloy layer. A light emitting diode structure comprising: a light emitting diode chip; a metal layer disposed on the light emitting diode chip; and a metal film layer disposed on the metal layer and the light emitting diode chip Between the metal laminates comprising at least one tin-containing first metal material layer and at least one second metal material layer comprising a metal capable of forming an alloy with tin, and the first metal material layer is different from the second metal The material layer has a thickness greater than a thickness of the metal film layer, and the metal layer has a melting point lower than a melting point of the metal film layer. The light emitting diode structure of claim 7, further comprising a metal layer connecting the metal layer and the metal film layer, wherein the material of the metal layer has at least the metal film layer The first material and the second material included in the metal laminate are different from the second material. The light-emitting diode structure of claim 7, wherein the metal thin film layer comprises silver, gold, nickel, copper or a combination thereof. The light-emitting diode structure according to claim 7, wherein the metal laminate comprises a laminated structure of a tin layer and an alloy layer.