JP2006173265A - Semiconductor laser and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser efficiently dissipating a heat generated in a ridgy waveguide to the outside, increasing an upper-limit temperature capable of ensuring the basic characteristics and reliability of an element, and enabling a stable operation under a high-temperature state in an insulating film coating the surface of the semiconductor laser such as the ridgy waveguide and a manufacturing method for the semiconductor laser. <P>SOLUTION: In the semiconductor laser, insulating films containing Al and having excellent heat-dissipating properties are used as the insulating films 103 coating a surface and the side faces of the ridgy waveguides, and the insulating films 103 are further formed in surface shapes having irregularities vertically or in parallel or in a latticed shape to the ridgy waveguides. The ridgy waveguides are formed, and the surface of the semiconductor laser is coated with the insulating films using Al having a thermal conductivity higher than Si as a main material. A surface area is further increased in a groove shape and the latticed shape by working the surfaces of the insulating films using formed Al as the main material, and heat-dissipating properties are improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor laser manufacturing technique, and more particularly to a technique effective when applied to an optical communication semiconductor laser excellent in heat dissipation and a manufacturing method thereof.

  A semiconductor laser is a device that enables high-speed information exchange. In addition, it is a light source for optical communication that requires both low cost and long life. A semiconductor laser needs to have a ridge-shaped waveguide structure for the purpose of enabling a low current operation and suppressing a transverse mode of laser light. An element having a ridge-shaped waveguide structure is formed by embedding and forming both sides of a ridge-shaped waveguide with semiconductors having different electrical conductivities. However, in the case of this structure, since the crystal growth is performed twice, the manufacturing cost becomes high. Therefore, there is a structure in which the manufacturing cost can be reduced by reducing the material cost and the number of processes without embedding the ridge-shaped waveguide with a semiconductor. In the case of the structure, an insulating film formed for the purpose of reducing the operating current coats the surface of a semiconductor laser such as a ridge waveguide, and an electrode is formed thereon.

  By the way, one of the required specifications of a semiconductor laser is a stable operation under a high temperature condition, and there is a need for a structure that efficiently releases the heat inside the element generated by laser oscillation, particularly in the ridge-shaped waveguide. . When the insulating film formed on the surface of the semiconductor laser device is made of a material with low thermal conductivity such as Si, the heat generated in the ridge-shaped waveguide is not easily released to the outside, and the basic characteristics and reliability of the device There is a problem that the upper limit temperature that can guarantee this is limited.

  Therefore, the present invention solves the above-mentioned problems, and an object of the present invention is to efficiently release heat generated in the ridge-shaped waveguide to the outside in an insulating film that coats the surface of the semiconductor laser such as the ridge-shaped waveguide. It is an object of the present invention to provide a semiconductor laser and a method of manufacturing the same that increase the upper limit temperature that can guarantee the basic characteristics and reliability of the semiconductor laser and enable stable operation under high temperature conditions.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  In order to achieve the above object, the present invention uses an insulating film that coats the surface and the side surface of the ridge-shaped waveguide as an insulating film that has excellent heat dissipation including Al, and in addition, this insulating film is applied to the ridge-shaped waveguide. Thus, a semiconductor laser having a surface shape with irregularities in a vertical, parallel or lattice shape is obtained.

  In this semiconductor laser manufacturing method, after forming a ridge-shaped waveguide, the surface of the semiconductor laser is coated with an insulating film mainly made of Al, which has a higher thermal conductivity than Si. In addition, by processing the surface of the formed insulating film mainly made of Al, the surface area is increased as a groove shape or a lattice shape, and the heat dissipation is further improved. In addition, for the formation of an insulating film containing Al as a main material, a CVD method that can be easily formed, or a vapor deposition method that has good film properties on the surface and side surfaces of a ridge-shaped waveguide without impurities in a vacuum state. Is used. Alternatively, a sputtering method that can form a high-quality insulating film with good adhesion and high density is used.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  According to the present invention, the surface of a semiconductor laser such as a ridge-shaped waveguide is coated with an insulating film mainly made of Al with high heat dissipation, so that heat generated in the ridge-shaped waveguide is efficiently released to the outside. In addition, the upper limit temperature at which the basic characteristics and reliability of the element can be guaranteed can be increased, and stable operation under high temperature conditions can be achieved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

(Embodiment 1)
FIG. 1 shows an element structure of a ridge-shaped waveguide type semiconductor laser according to Embodiment 1 of the present invention.

  The ridge-waveguide semiconductor laser according to the present embodiment includes a semiconductor substrate 101, a laser multilayer structure 102, an insulating film 103, a front electrode 104, and a back electrode 105, and the manufacturing method thereof is performed according to the following procedure.

  First, the laser multilayer structure 102 is crystal-grown on the underlying semiconductor substrate 101 by using an organic metal gas layer growth method. Thereafter, a thermal CVD method, a photolithography method, and etching are performed to form a ridge-shaped waveguide. Next, for the purpose of reducing the operating current, a surface of a semiconductor laser such as a ridge-shaped waveguide is coated with an insulating film 103 containing Al as a main material, and a surface electrode 104 is formed thereon by an electron beam evaporation method or the like. Similarly, a back electrode 105 is formed on the back surface of the semiconductor laser.

  In this embodiment, the main material of the insulating film 103 is Al instead of conventional Si. Since Al exhibits a thermal conductivity of about 5 to 10 times that of Si, heat generated in the ridge-shaped waveguide of the semiconductor laser can be easily released to the surface electrode 104 formed on the insulating film 103 or outside. To do. The insulating film 103 containing Al as a main material is mainly an oxide film, but a nitride film is not a problem as long as the insulating film satisfies the specifications in terms of physical properties.

  As a method for forming the insulating film 103, for example, there is a CVD method using a reactive gas such as triisotyl Al, and it is possible to easily form an insulating film having a high film property under normal pressure. It is. A semiconductor laser substrate having a ridge-shaped waveguide structure (that is, the semiconductor substrate 101 after the formation of the laser multilayer structure 102) is placed on a high-temperature stage, and an insulating film 103 is formed on the surface thereof. At that time, when the stage on which the semiconductor laser substrate having the ridge-shaped waveguide structure is arranged is rotated, the film property on the side surface of the ridge-shaped waveguide is further improved.

  In addition, as a method for forming the insulating film 103, a sputtering method is used. The sputtering method does not require a reactive gas as an impurity, and it is possible to obtain a high-quality insulating film with high adhesion in a vacuum. Further, by using the low damage type ECR sputtering method, damage to the semiconductor laser during film formation by the sputtering method can be reduced, and in addition, a dense insulating film close to a crystalline state can be obtained. Is possible. In addition, for forming an insulating film on the side surface of the ridge-shaped waveguide having a low film property, for example, a stage having an inclination of about 30 to 60 ° is used with respect to the sputtering raw material. By forming them alternately, it is possible to obtain an insulating film having a uniform thickness on both the surface and the side surface.

  In addition, as a method for obtaining an insulating film having a high film property on the side surface of the ridge-shaped waveguide in a vacuum state, for example, an electron beam evaporation method using a stage having an inclination of about 30 to 60 ° is used. There is no problem.

  Therefore, according to the present embodiment, by applying the insulating film 103 made mainly of Al to a semiconductor laser having a ridge-shaped waveguide structure, the upper limit temperature at which the basic characteristics and reliability of the element can be guaranteed is raised. Is possible. In the practical example by the present inventor, the upper limit temperature can be raised by 15 ° C. or more.

(Embodiment 2)
FIG. 2 shows an element structure of a ridge-shaped waveguide type semiconductor laser according to the second embodiment of the present invention.

  In the ridge-shaped waveguide type semiconductor laser according to the present embodiment, after forming the insulating film 103 made of Al as the main material shown in the first embodiment, a photolithography method and etching are performed to form a ridge-shaped waveguide. On the other hand, a concavo-convex-shaped insulating film 106 subjected to concavo-convex processing is formed as a surface shape having concavo-convex in a vertical, parallel, or lattice shape. Thereby, it becomes possible to increase a surface area and to further improve heat dissipation.

  As described above, in the present invention according to the first and second embodiments, the heat inside the semiconductor laser element generated by the laser oscillation is efficiently released to the outside, so that the stable operation can be performed under a further high temperature state.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  INDUSTRIAL APPLICABILITY The present invention is effective when applied to a semiconductor laser for optical communication excellent in heat dissipation and a manufacturing method thereof. In particular, the upper limit temperature at which the basic characteristics and reliability of the element can be guaranteed can be greatly increased, and it can be used as a basic technology indispensable for future semiconductor lasers.

It is a figure which shows the element structure of the ridge-shaped waveguide type semiconductor laser which is Embodiment 1 of this invention. It is a figure which shows the element structure of the ridge-shaped waveguide type semiconductor laser which is Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Semiconductor substrate, 102 ... Laser multilayer structure, 103 ... Insulating film, 104 ... Front surface electrode, 105 ... Back surface electrode, 106 ... Insulating film of uneven | corrugated shape.

Claims (5)

A semiconductor laser having a ridge-shaped waveguide structure,
An insulating film that coats the surface of the semiconductor laser and the side surface of the ridge-shaped waveguide;
2. The semiconductor laser according to claim 1, wherein the insulating film is an insulating film containing Al. The semiconductor laser according to claim 1, wherein
2. The semiconductor laser according to claim 1, wherein the insulating film has an uneven shape perpendicular to, parallel to, or in a lattice shape with respect to the ridge-shaped waveguide. A method of manufacturing a semiconductor laser having a ridge-shaped waveguide structure,
A method of manufacturing a semiconductor laser, comprising: coating a surface of the semiconductor laser and a side surface of the ridge-shaped waveguide with an insulating film containing Al. In the manufacturing method of the semiconductor laser according to claim 3,
A method of manufacturing a semiconductor laser, wherein the insulating film is formed by a CVD method, a sputtering method, or an evaporation method. In the manufacturing method of the semiconductor laser according to claim 4,
A method of manufacturing a semiconductor laser, comprising: forming a concavo-convex pattern on the surface of the insulating film in a vertical, parallel, or grid pattern with respect to the ridge-shaped waveguide by a photolithography method.

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