KR20060075710A - Sub mounting substrate for packaing light emitting diode and method for fabricating the same - Google Patents

Abstract

The present invention relates to a sub-mount substrate for assembling a light emitting device and a method of manufacturing the same, using a silicon substrate as a sub-mount substrate for assembling a light emitting device, and forming two regions having a step on the silicon substrate, and an upper region. By forming an insulating film in the film, and then forming solder in each region, only one wire bonding can be performed when assembling with the light emitting device, thereby simplifying the assembly process and lowering the assembly process cost. .

Light Emitting Diode, Package, Submount, Board, Solder, Assembly, Silicon

Description

 Submount substrate for assembly of light emitting device and method of manufacturing the same {Sub mounting substrate for packaing light emitting diode and method for fabricating the same}             

1A to 1D are cross-sectional views illustrating a manufacturing process of a sub-mount substrate for laser diode assembly according to the prior art.

2 is a schematic cross-sectional view showing a state in which a light emitting device emitting blue violet light according to the prior art is assembled;

3A to 3H are cross-sectional views illustrating a manufacturing process of a sub-mount substrate for assembling a light emitting device according to the present invention.

4 is a schematic cross-sectional view showing a state in which a light emitting device emitting blue violet light according to the present invention is assembled;

5 is a cross-sectional view showing the configuration of the UBM (Under Bump Metallurgy) layer applied to the present invention

<Description of the symbols for the main parts of the drawings>

114: P electrode 115: N electrode                 

130: silicon substrate 131: insulating film

132,133: photoresist 134,134a, 134b, 134c: UBM layer

135a, 135b, 135c: solder 151: Ti layer

152: Pt layer 153: Au layer

200: lead 210: stem

The present invention relates to a sub-mount substrate for assembling a light emitting device and a method of manufacturing the same. More specifically, a silicon substrate is used as a sub-mount substrate for assembling a light emitting device, and two regions having steps on the silicon substrate are formed. By forming an insulating film in an upper region and then forming solder in each region, only one wire bonding can be performed when assembling with a light emitting device, thereby simplifying an assembly process and lowering an assembly process cost. A submount substrate for assembling a light emitting element and a method of manufacturing the same.

In general, light emitting devices such as laser diodes have electrodes on the top and bottom, and are assembled by using a sub-mount substrate on a stem.

However, since the light emitting device emitting blue violet light is manufactured by using a sapphire substrate, two electrodes exist on one surface, and in order to bond the light emitting device to the submount substrate, There should be a bonding metal called solder that corresponds to the electrodes.

1A to 1D are cross-sectional views illustrating a manufacturing process of a sub-mount substrate for laser diode assembly according to the prior art. First, an UBM (Under Bump Metallurgy) layer 31 is formed below the AIN substrate 30. Next, a UBM layer 32 is formed on the AIN substrate 30. (FIG. 1A)

Thereafter, the UBM layer 32 on the AIN substrate 30 is selectively etched and divided into first and second UBM regions 32a and 32b (FIG. 1B).

Subsequently, a first solder layer 33a is formed on the first UBM region 32a, and a second layer having a thickness thicker than the thickness of the first solder layer 33a on the second UBM region 32a. The solder layer 33b is formed (FIG. 1C).

Subsequently, a UBM layer 34 is formed under the AIN substrate 30 (FIG. 1D).

FIG. 2 is a schematic cross-sectional view showing a state in which a light emitting device emitting blue violet light according to the prior art is assembled. And the P-type semiconductor layer 13 are sequentially formed, mesa-etched from the P-type semiconductor layer 13 to a part of the N-type semiconductor layer 11, and the mesa-etched N-type semiconductor layer. (11) An N electrode 15 is formed on the upper portion, and a P electrode 14 is formed on the P-type semiconductor layer 13 to emit blue violet light from the active layer 12.

The light emitting device is inverted and bonded to the sub-mount substrate as shown in FIG. 1D. The P electrode 14 and the N electrode 15 of the light emitting element are formed of the first UBM region 33a and the upper part of the sub-mount substrate 30. Each of the two UBM regions 33b is bonded, the first UBM region 33a is wire bonded to the lead 60, and the third UBM region 33b is wire bonded to the stem 50.

The submount substrate 30 is bonded to the stem 50 by solder 34.

In the packaging process of the related art, an expensive AlN substrate is used for the sub-mount substrate and two wire bonding is performed, which requires a high process cost and a complicated process.

In order to solve the problems described above, the present invention uses a silicon substrate as a sub-mount substrate for the assembly process of the light emitting device, forms two regions having a step on the silicon substrate, and forms an insulating layer on the upper region. Subsequently, by forming solder in each region, only one wire bonding may be performed when assembling with the light emitting device, thereby simplifying the assembly process and lowering the assembly process cost. It is an object to provide a manufacturing method.

A preferred aspect for achieving the above object of the present invention is that a region on the silicon substrate is removed to form a step;

An insulating film is formed on the silicon substrate that is not removed;

A UBM layer is formed over the insulating film, over an area of the removed silicon substrate, and under the silicon substrate;

Provided is a sub-mount substrate for assembling a light emitting device, characterized in that a solder is formed on the UBM layer.

Another preferred aspect for achieving the above objects of the present invention comprises the steps of: forming an insulating film on the substrate, and forming a first photosensitive film only on a portion of the insulating film;

Etching a portion of the substrate on which the first photoresist film is not formed by using the first photoresist film as a mask;

Removing the first photoresist film and forming a second photoresist film on the insulating film and the substrate;

Selectively etching the second photoresist layer to expose an upper portion of the insulating layer and a portion of the upper portion of the substrate;

Forming a UBM layer over the exposed insulating film and the substrate and over the second photosensitive film;

Removing the second photoresist layer and the UBM layer thereon except for the insulating layer and the UBM layer above the substrate, and forming a UBM layer below the substrate;

Provided is a method of manufacturing a submount substrate for assembling a light emitting device, the method including forming solder on each of the UBM layers.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

3A to 3H are cross-sectional views illustrating a manufacturing process of a sub-mount substrate for assembling a light emitting device according to the present invention. First, an insulating film 131 is formed on a silicon substrate 130 (FIG. 3A), and The first photosensitive film 132 is formed only in a portion of the upper portion of the insulating film 131 (FIG. 3B).

Here, the insulating film 131 is preferably formed of a silicon oxide film (SiO ₂ ).

Thereafter, a portion of the silicon substrate 130 on which the first photosensitive film 132 is not formed is etched using the first photosensitive film 132 as a mask (FIG. 3C).

At this time, a step is formed in the silicon substrate 130.

Subsequently, the first photoresist layer 132 is removed, and a second photoresist layer 133 is formed on the insulating layer 131 and the silicon substrate 130 (FIG. 3D).

Subsequently, the second photoresist layer 133 is selectively etched to expose the upper portion of the insulating layer 131 and the upper portion of the silicon substrate 130 (FIG. 3E).

Next, a UBM layer 134 is formed on the exposed insulating film, the silicon substrate, and the second photosensitive film 133. (FIG. 3F).

Subsequently, except for the insulating film and the UBM layer on the silicon substrate, the second photosensitive film and the UBM layer on the silicon substrate are removed, and a UBM layer 134c is formed on the lower portion of the silicon substrate (FIG. 3G).

By the process of FIG. 3G, independent UBM layers 134a and 134b are formed on the insulating film and the silicon substrate.

Finally, solder 135a, 135b, 135c is formed in each of the UBM layers 134a, 134b, 134c (FIG. 3H).

Therefore, as shown in Fig. 3h, the sub-mount substrate for light emitting element assembly of the present invention has a step formed by removing one region of the upper portion of the silicon substrate 130; An insulating film 131 is formed on the silicon substrate that is not removed; UBM layers (134a, 134b, 134c) are formed over the insulating film (131), over the removed silicon substrate region, and under the silicon substrate; Solders 135a, 135b, and 135c are formed on the UBM layers 134a, 134b, and 134c.

As described above, since the electrically independent UBM layer is formed on the insulating film and the silicon substrate, one UBM layer is electrically connected to the silicon substrate in the assembling process with the light emitting device, and the other UBM layer is wired. Bonding only requires one wire bonding.

4 is a schematic cross-sectional view showing a state in which a light emitting device emitting blue violet light according to the present invention is assembled, the light emitting device is inverted and bonded to a sub-mount substrate, and the P electrode 114 of the light emitting device is connected to the sub-mount substrate. It is bonded to the first UBM region 134a on the insulating layer 131 formed on the silicon substrate 130, which is a mount substrate, and the N electrode 115 is the second UBM on the sub-mount substrate 130 on which the step is formed. Bonded to region 133b.                     

In addition, since the first UBM region 134a and the lead 200 are wire bonded, the P electrode 114 of the light emitting device is in electrical communication with the lead 200, and the N electrode 115 is the sub-mount substrate 130. It is electrically connected to the stem (210) through the ().

The stem 210 is electrically connected to other leads not shown in FIG. 4.

Therefore, when the light emitting device is packaged using the sub-mount substrate according to the present invention, the P electrode 114 and the N electrode 115 of the light emitting device can be electrically and independently packaged by a simple structural design.

Accordingly, the present invention uses a silicon substrate as a sub-mount substrate, forms two regions having a step on the silicon substrate, an insulating film in an upper region, and then forms solder in each region, thereby providing a light emitting device. When assembling with only one wire bonding can be performed to simplify the assembly process, it is possible to lower the assembly process cost.

Here, AlN substrates conventionally used as sub-mount substrates are expensive, while silicon substrates used in the present invention are inexpensive.

FIG. 5 is a cross-sectional view illustrating a structure of an under bump metallurgy (UBM) layer applied to the present invention. The UBM layer 134 sequentially stacks a Ti layer 151, a Pt layer 152, and an Au layer 153. To form.

As described above, the present invention uses a silicon substrate as a submount substrate for the assembly process of the light emitting device, forms two regions having a step on the silicon substrate, and forms an insulating film on the upper region, By forming solder in each region, only one wire bonding can be performed when assembling with the light emitting device, so that the assembly process can be simplified and the assembly process cost can be lowered. Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (5)

A region on the silicon substrate is removed to form a step; An insulating film is formed on the silicon substrate that is not removed; A UBM layer is formed over the insulating film, over an area of the removed silicon substrate, and under the silicon substrate; Submount substrate for light emitting device assembly, characterized in that the solder is formed on the UBM layer. Forming an insulating film on the substrate, and forming a first photosensitive film only on a portion of the insulating film; Etching a portion of the substrate on which the first photoresist film is not formed by using the first photoresist film as a mask; Removing the first photoresist film and forming a second photoresist film on the insulating film and the substrate; Selectively etching the second photoresist layer to expose an upper portion of the insulating layer and a portion of the upper portion of the substrate; Forming a UBM layer over the exposed insulating film and the substrate and over the second photosensitive film; Removing the second photoresist layer and the UBM layer thereon except for the insulating layer and the UBM layer above the substrate, and forming a UBM layer below the substrate; A method of manufacturing a sub-mount substrate for assembling a light emitting device comprising the steps of forming solder on each of the UBM layers. The method of claim 2, The substrate, It is a silicon substrate, The manufacturing method of the sub-mount substrate for light emitting element assembly. The method of claim 2 or 3, The insulating film, A method of manufacturing a sub-mount substrate for assembling a light emitting element, characterized by forming a silicon oxide film (SiO ₂ ). The method of claim 2 or 3, The UBM layer, A Ti layer, a Pt layer, and an Au layer are formed by laminating them sequentially.

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