KR100610950B1 - Laser diode improved in heat-dissipating structure and fabricating method therefor - Google Patents

Abstract

The present invention relates to a laser diode having an electrode structure capable of increasing heat dissipation efficiency and a method of manufacturing the same.

According to the present invention, in a laser diode having an active layer causing laser oscillation and a p-type electrode and an n-type electrode for injecting current into the active layer, the p-type electrode or the n-type electrode to which the heat sink is attached during packaging Disclosed is a laser diode characterized in that the uneven structure is repeatedly formed.

In addition, the method of manufacturing a laser diode according to the present invention is a method of manufacturing a laser diode having an active layer causing laser oscillation, a p-type electrode and an n-type electrode for injecting current into the active layer, wherein the p-type electrode or The process of forming an n-type electrode includes the steps of: depositing a mask layer on a surface of the substrate on which the p-type electrode or the n-type electrode is to be formed; A second step of forming a mask by removing the deposited film of the mask layer in a predetermined pattern by a photolithography process and a BOE etching process; A third step of forming an uneven structure on the surface of the substrate by etching the portion exposed through the mask; A fourth step of removing the mask; And depositing an electrode material on the uneven structure to form an electrode having a curvature corresponding to the uneven structure.

Description

LASER DIODE IMPROVED IN HEAT-DISSIPATING STRUCTURE AND FABRICATING METHOD THEREFOR}

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to

1 is a perspective view showing the configuration of a conventional laser diode.

2 is a side view of FIG. 1;

3 is a perspective view showing the configuration of a laser diode according to a preferred embodiment of the present invention;

4 is a side view of FIG. 3;

FIG. 5 is a side view illustrating a chip bar breaking process performed in the manufacturing process of the laser diode according to the preferred embodiment of the present invention. FIG.

6 is a configuration diagram for packaging a laser diode according to a preferred embodiment of the present invention.

7 to 11 are side views showing the manufacturing process of the laser diode according to the preferred embodiment of the present invention.

<Description of main reference numerals in the drawings>

91 ... mask layer 100 ... n type electrode

101 ... n-type substrate 102 ... active layer

103 ... p-InP current blocking layer 104 ... n-InP current blocking layer

105 ... Clad layer 106 ... Ohmic contact layer

107 ... insulating layer 108 ... p-type electrode

109 ... Reflective film 110 ... groove

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser diode and a method of manufacturing the same, and more particularly, to a laser diode having an electrode structure capable of increasing a contact area with a heat sink and a method of manufacturing the same.

Recent laser diodes are generally fabricated with a Planar Buried Heterostructure (PBH) structure having a buried active layer and a flat surface.

1 and 2, a conventional laser diode includes an active layer 12, a current blocking layer 13 and 14, a cladding layer 15, and an ohmic contact layer on an n-type substrate 11. 16, the insulating layer 17 and the p-type electrode 18 are stacked, the n-type electrode 10 is formed on the lower surface of the n-type substrate 11, the reflective film 19 is formed on the back of the chip Has Hereinafter, for convenience of understanding, the illustration of the insulating layer 17 partially formed around the p-type electrode 18 will be omitted in the side view of the laser diode.

Typically, the active layer 12 having a multi-quantum well structure is formed in a mesa shape between the optical waveguide structures, and a current blocking layer 13 that blocks injection current from leaking to regions other than the active layer 12. 14 is formed in such a manner that a p-InP current blocking layer 13 and an n-InP current blocking layer 14 are sequentially grown around the active layer 12. In this case, the current blocking layer 14 may be etched in a 'U' shape so as to reduce the parasitic capacitance.

On the other hand, since the laser diode is sensitive to temperature like other semiconductor devices, a heat sink is attached to one surface of the chip through a predetermined submount during packaging. Therefore, heat generated during operation of the laser diode is transferred to the heat sink via the sub-mount and is discharged out of the packaging frame.

In order to increase the heat transfer efficiency of heat generated from the laser diode, the contact area between the laser diode and the heat sink must be increased, and the heat sink must be made of a material having excellent thermal conductivity.

Here, since the heat sink is made of a metal material, the thermal expansion coefficient is so large that a stress problem occurs. Therefore, the heat sink has many problems in selecting a material, such as using a ceramic similar to a semiconductor.

In particular, considering that the portion of the laser diode chip having the highest heat dissipation is the electrode portion, it is important to increase the contact area between the electrode and the heat sink in order to increase the heat transfer efficiency. Since the n-type electrode 10 is simply formed in a flat plate structure, there is a limit in increasing the contact area.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object of the present invention is to provide a laser diode having a three-dimensional surface structure and a manufacturing method thereof, so that the contact area with the heat sink is increased.

It is another object of the present invention to provide a laser diode and a method of manufacturing the same having an electrode structure capable of facilitating a chip bar breaking process as well as a heat radiating action.

In order to achieve the above object, the laser diode according to the present invention includes an active layer causing laser oscillation, a p-type electrode and an n-type electrode for injecting current into the active layer, and the heat sink is attached to the packaging. The concave-convex structure is repeatedly formed on the p-type electrode or the n-type electrode.

The uneven structure may be formed to include a groove of a stripe pattern having a cross-section 'V' shape.

The active layer is formed to have a mesa structure, the groove of the uneven structure is preferably formed in a direction perpendicular to the longitudinal direction of the mesa for convenience of chip bar breaking process.

According to another aspect of the invention, in the method of manufacturing a laser diode having an active layer for generating a laser oscillation, and a p-type electrode and an n-type electrode for injecting a current into the active layer, the p-type electrode or n-type electrode Forming process, the first step of depositing a mask layer on the surface of the substrate on which the p-type electrode or n-type electrode will be formed; A second step of forming a mask by removing the deposition layer of the mask layer in a predetermined pattern by a photolithography process and a buffered oxide etch process; A third step of forming an uneven structure on the surface of the substrate by etching the portion exposed through the mask; A fourth step of removing the mask; And a fifth step of depositing an electrode material on the uneven structure to form an electrode having a curvature corresponding to the uneven structure.

Preferably, the active layer is formed to have a mesa structure, and the second step may be performed to obtain a mask having a window of a stripe pattern perpendicular to the longitudinal direction of the mesa.

The third step may be performed such that a groove having a stripe pattern having a 'V' cross section is formed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

3 is a perspective view showing the configuration of a laser diode according to a preferred embodiment of the present invention, and FIG. 4 is a side view of FIG.

3 and 4, a laser diode according to an exemplary embodiment of the present invention includes an active layer 102, a current blocking layer 103, 104, a cladding layer 105, and an ohmic contact layer on an n-type substrate 101. 106, an insulating layer 107, and a p-type electrode 108 are stacked, and an n-type electrode 100 having a concave-convex structure is provided on the bottom surface of the n-type substrate 101, and a reflective film 109 is formed on the back surface of the chip. It has a formed structure.

The active layer 102 converts the current injected through the p-type electrode 108 and the n-type electrode 100 into light, and has a mesa-shaped multi-quantum well structure having a width of about 1 to 1.5 μm, for example. . Here, the active layer 102 has a buried heterostructure, and is preferably interposed between a ridge type optical waveguide structure.

In addition, the active layer 102 has a single mode or multimode spectrum, and has a structure capable of emitting light of a specific wavelength in a wavelength range from visible light to infrared light.

In particular, the n-type electrode 100 provided on the bottom surface of the n-type substrate 101 has a structure in which the uneven structure is repeatedly formed. Here, of course, the present invention may be modified so that the uneven structure is formed on the p-type electrode 108. In addition, although the concave-convex structure is formed so that curvature exists on both sides of the n-type electrode 100 in the drawing, the concave-convex structure may be formed so that the curvature exists only on the exposed surface of the n-type electrode 100. to be.

Preferably, the concave-convex structure is formed by the groove 110 of the stripe pattern having a cross-section 'V' shape. At this time, if the groove 110 is formed in the concave-convex structure so as to extend in a direction perpendicular to the mesa longitudinal direction of the active layer 102, by cutting the portion of the groove 110 (see cutting leader 150 of FIG. 5) during the chip bar breaking process The braking process can be carried out more easily.

6 shows a packaging configuration of a laser diode according to a preferred embodiment of the present invention. As shown in the figure, a heat sink 202 is attached to the n-type electrode surface of the laser diode 200 of the present invention during packaging, for example, via an adhesive member 201 corresponding to metal bonding. . Alternatively, the heat sink 202 may be indirectly attached to the adhesive member 201 via a predetermined submount.

Heat generated in the laser diode 200 is transmitted to the adhesive member 201 and is discharged toward the heat sink 202. At this time, since the concave-convex structure is repeatedly formed on the n-type electrode surface of the laser diode 200, heat may be released through a wider contact surface.

7 to 11 sequentially illustrate a process of forming the n-type electrode 100 during the manufacturing process of the laser diode according to the preferred embodiment of the present invention. Here, other processes for manufacturing the laser diode can be performed by conventional laser diode manufacturing techniques.

First, after the process of forming the p-type electrode 108 on the upper surface of the wafer is completed, the process of polishing the lower surface of the wafer corresponding to the surface of the n-type substrate 101 described above and then depositing the mask layer 90 is performed. Is performed (see FIG. 7). The mask layer 90 is formed of a silicon nitride (SiNx) film, and any material may be used as the etching mask of the n-type substrate 101 to be described later.

방향인 것을 감안할 때, 그 수직방향인

방향으로 연장된 스트라이프 형상의 창(92)이 반복적으로 형성된 구조를 갖는 것이 바람직하다.After the deposition process, a mask 91 is formed by removing the mask layer 90 in a predetermined pattern by a photolithography process and a buffered oxide etching (BOE) etching process (see FIG. 8). Mask 91 has a mesa longitudinal direction of active layer 102 typically

In terms of the direction,

It is preferable to have a structure in which the stripe-shaped window 92 extending in the direction is formed repeatedly.

After the mask 91 is formed, the surface of the n-type substrate 101 exposed through the window 92 of the mask 91 is etched by using a hydrochloric acid-based solution to form a cross-section having a 'V' shape on the surface of the substrate. The process of forming the groove 110 is performed (see FIG. 9).

Subsequently, when the mask 91 is removed using a BOE etching process, a pattern having a concave-convex structure is repeated on the surface of the n-type substrate 101 as shown in FIG. 10.

Finally, as shown in FIG. 11, when the electrode material is deposited on the uneven structure to maintain the curvature corresponding to the uneven structure, the n-type electrode 100 having the uneven structure is formed on the surface of the n-type substrate 101.

After the n-type electrode 100 formation process is completed as described above, the chip bar breaking process is performed along the groove 110 of the uneven structure, and a predetermined optical coating process for the chip bar cross section is performed.

Subsequently, a process of packaging the divided laser diode chip with a heat sink using a normal TOCAN or the like is performed. In this case, the heat sink is preferably made of a material having a similar thermal expansion coefficient and excellent thermal conductivity, such as silicon carbide (SiC), boron nitride (BN), aluminum nitride (AlN), and the like, and a heat sink and a laser diode. The bonding between the chips is preferably performed by eutectic bonding using an alloy of gold (Au) and tin (Sn).

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

According to the present invention, since the contact area between the electrode and the heat sink of the laser diode is widened by the uneven structure, the heat dissipation characteristic is improved, so that the laser diode can be operated more stably.

In addition, during the chip bar braking process of the laser diode manufacturing process, the groove portion of the uneven structure may be simply cut, thereby improving workability.

Claims (6)

In a laser diode having an active layer that causes laser oscillation, and a p-type electrode and an n-type electrode for injecting current into the active layer, And a concave-convex structure is repeatedly formed on the p-type electrode or the n-type electrode to which the heat sink is attached during packaging. The method of claim 1, The uneven structure is a laser diode, characterized in that it comprises a groove of the stripe pattern having a cross-section 'V' shape. The method of claim 2, The active layer is formed to have a mesa structure, The groove of the uneven structure is a laser diode, characterized in that formed in a direction perpendicular to the longitudinal direction of the mesa. In the method of manufacturing a laser diode having an active layer for generating a laser oscillation, and a p-type electrode and an n-type electrode for injecting current into the active layer, The step of forming the p-type electrode or n-type electrode, Depositing a mask layer on a surface of the substrate on which the p-type electrode or the n-type electrode is to be formed; A second step of forming a mask by removing the deposited film of the mask layer in a predetermined pattern by a photolithography process and a BOE etching process; A third step of forming an uneven structure on the surface of the substrate by etching the portion exposed through the mask; A fourth step of removing the mask; And And depositing an electrode material on the concave-convex structure so that an electrode having a curvature corresponding to the concave-convex structure is formed. The method of claim 4, wherein The active layer is formed to have a mesa structure, And wherein said second step is performed to obtain a mask having a window of a stripe pattern perpendicular to the longitudinal direction of the mesa. The method of claim 5, The third step is a laser diode manufacturing method, characterized in that the cross-section is formed to form a groove of the stripe pattern of the 'V' shape.

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