Light emitting device and package component

A light emitting device includes a light emitting element mounting component, including a cubic package component formed of a silicon member covered with a insulating layer, and the package component including a bottom portion, a sidewall portion provided to stand upright on both ends of the bottom portion respectively, and a backwall portion provided to stand upright on an innermost part of the bottom portion, and the package component in which a cavity is provided in an inner side, and a light emitting element mounted on an inner side surface of the backwall portion of the package component, and including a light emitting surface on an upper end part, wherein a plurality of said light emitting element mounting components are stacked in a depth direction of the cavity to direct toward an identical direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2010-258619, filed on Nov. 19, 2010, the entire contents of which are incorporated herein by reference.

FIELD

It is related to a light emitting device and a package component used for mounting the light emitting element.

BACKGROUND

Recently, the progress in the semiconductor laser technology is remarkable. Such semiconductor laser technology is applied to various electronics equipments used in the recording/playing of the optical disc, or the information communication using the optical fiber, and the like. In recent years, the stacked type semiconductor laser device capable of obtaining the high-power laser by arranging a plurality of semiconductor laser elements to stack them in the horizontal direction has been developed.

In the stacked type semiconductor laser device, the semiconductor laser elements each of which is sandwiched between the copper tungsten members are stacked in the horizontal direction, and the light converging lens is arranged on the semiconductor laser elements respectively.

A related art is disclosed in Japanese National Publication of International Patent Application No. 2009-524223.

The copper tungsten member cannot obtain a sufficient thickness precision and a sufficient surface precision (surface roughness). Therefore, it is difficult to stack a plurality of semiconductor laser elements at a narrow pitch with good precision. For this reason, particularly when an arrangement pitch between the semiconductor laser elements is made narrow, misalignment is easily caused at the time of arrangement of the lens on each semiconductor laser element. As a result, it becomes difficult to construct the stacked type semiconductor laser device with high precision.

SUMMARY

According to one aspect discussed herein, there is provided a light emitting device, which includes a light emitting element mounting component including, a cubic package component formed of a silicon member covered with a insulating layer, and the package component including a bottom portion, a sidewall portion provided to stand upright on both ends of the bottom portion respectively, and a backwall portion provided to stand upright on an innermost part of the bottom portion, and the package component in which a cavity is provided in an inner side, and a light emitting element mounted on an inner side surface of the backwall portion of the package component, and including a light emitting surface on an upper end part, wherein a plurality of said light emitting element mounting components are stacked in a depth direction of the cavity to direct toward an identical direction.

According to another aspect discussed herein, there is provided a package component, which includes a bottom portion, a sidewall portion provided to stand upright on both ends of the bottom portion respectively, and a backwall portion provided to stand upright on an innermost part of the bottom portion, a first conductive joining material provided to an inner side surface of the backwall portion and used for joining a light emitting element, and a second conductive joining material provided to an outer side surface of the backwall portion, wherein the cubic package component is formed of a silicon member covered with a insulating layer, and a cavity is provided in an inner side of the package component.

DESCRIPTION OF EMBODIMENT

An embodiment of the present invention will be explained with reference to the accompanying drawings hereinafter.

Prior to the explanation of an embodiment, the related art (preliminary matter) to be set forth as a basis will be explained hereunder.

As depicted inFIG. 1, in a semiconductor laser device in the related art, a semiconductor laser element100is arranged between copper (Cu) tungsten (W) members200respectively, and the semiconductor laser elements100are stacked in the horizontal direction via the copper tungsten member200. Each semiconductor laser element100has a light emitting surface A on its upper end part.

The each semiconductor laser element100is arranged in such a manner that one side surface of each element100is joined to the copper tungsten member200via a gold (Au) tin (Sn) solder layer120in a state that the light emitting surface A is directed upward respectively. Also, the other side surface of each element100is joined to the copper tungsten member200via an indium (In) solder layer140respectively.

Also, a cylindrical lens300is arranged independently over the semiconductor laser elements100respectively. The copper tungsten members200that stack a plurality of semiconductor laser elements100are mounted on a metal radiation plate (heat block) via an insulating substrate such as an AlN substrate, a BeO substrate, or the like.

The each semiconductor laser element100is connected electrically in series via the copper tungsten member200, and an electric current is supplied from the semiconductor laser element100located to the right side to the semiconductor laser element100located to the left side.

Accordingly, a light is emitted upward from the light emitting surfaces A of the each semiconductor laser element100respectively, and the emitted lights are converged by the cylindrical lens300respectively and then are emitted as a high-power laser to the outside.

In this manner, in the semiconductor laser device in the related art, the copper tungsten members200are used as intermediate members for stacking a plurality of semiconductor laser elements100. Since the copper tungsten members200have an insufficient processing precision, neither an enough thickness precision can be obtained nor an enough surface precision (smoothness) can be obtained.

Therefore, particularly in the case that a thickness of the copper tungsten member200is set in a range from 400 to 100 μm and an arrangement pitch of the semiconductor laser elements100is narrowed, in many cases a variation in the arrangement pitch of the semiconductor laser elements100exceeds a tolerance.

As a result, when the cylindrical lenses300are arranged with a designed arrangement pitch of the semiconductor laser elements100, a misalignment is caused between the semiconductor laser element100and the cylindrical lens300, and thus it becomes difficult to construct the stacked type semiconductor laser device with high precision.

Also, the copper tungsten members200are made of conductive material. Therefore, it is necessary that such copper tungsten members200are mounted on the metal radiation plate via the insulating substrate, and such a problem exists that a component count is increased.

In this way, in the case that the copper tungsten members200are used, in order to arrange the semiconductor laser elements100at a narrow pitch with good precision, any improvement in the thickness precision of the copper tungsten member200, and any devising in the alignment of the cylindrical lenses300, and the like are needed. As a result, it is feared that an increase in cost is brought about.

An embodiment explained hereunder can solve the disadvantages mentioned above.

Embodiment

FIG. 2Ais a perspective view depicting a package component for mounting a light emitting element, according to an embodiment, andFIG. 2Bis a fragmental perspective view depicting a sectional structure taken along I-I in the perspective view ofFIG. 2A.

As depicted inFIG. 2A, a package component of the embodiment is formed of a silicon cubic member, which is shaped into an individual piece by processing three-dimensionally a silicon wafer. The package component5has a bottom portion10, a first sidewall portion12aand a second sidewall portion12bprovided to both ends of the bottom portion10respectively to stand upright, and a backwall portion14provided to the inner part side of the bottom portion10to stand upright and connected to the first and second sidewall portions12a,12b. A height of the backwall portion14is set lower than heights of the first and second sidewall portions12a,12b, and an area located over the backwall portion14constitutes an opening portion9a.

Also, a front wall portion opposing to the backwall portion14does not exist, and a front part of the area where the first sidewall portion12aand the second sidewall portion12bare opposed to each other, constitutes an opening portion9b. Also, a ceiling portion opposing to the bottom portion10does not exist, and the ceiling portion constitutes an opening portion9c. Accordingly, a cavity C (cubic space) that is dug in the silicon substrate is provided to the inner side of the first sidewall portion12a, the second sidewall portion12b, and the backwall portion14.

In this manner, the package component5is formed of the silicon solid member that is constructed by the bottom portion10, the first and second sidewall portions12a,12b, and the backwall portion14, and its surfaces (all exposed surfaces) are covered with an insulating layer20such as a silicon oxide layer, or the like (perspective view inFIG. 2B). After the silicon cubic member having a desired shape is manufactured, the insulating layer20can be formed on the surface of the silicon cubic member by thermally oxidizing the silicon cubic member.

Also, the front parts (parts corresponding to the cavity C) of upper surfaces of the first and second sidewall portions12a,12bare cut downward partially, thus the level difference portion S used for positioning the lens are formed respectively. The level differences like a stair are illustrated as the level difference portion S. But, as the level difference portion S used for positioning the lens, concave portions (U-shaped cutting portion, V-shaped cutting portion, or the like) may be formed in the position where the lens is arranged.

By further reference to the perspective view ofFIG. 2B, a through hole TH which penetrates from the inner surface to the outer surface is provided in the backwall portion14. A penetration electrode TE made of copper (Cu), or the like is filled in the through hole TH via the insulating layer20. The penetration electrode TE is insulated electrically from the backwall portion14(silicon) by the insulating layer20.

A first wiring layer30is formed on the whole of the inner side surface of the backwall portion14, and a second wiring layer40is formed on the whole of the outer side surface of the backwall portion14. The first wiring layer30and the second wiring layer40are connected mutually via the penetration electrode TE.

Furthermore, an indium (In) layer32(first conductive joining material) is formed in an upper part side of the first wiring layer30on the inner side surface of the backwall portion14. Also, a gold (Au) tin (Sn) alloy layer42(second conductive joining material) is formed in an upper part side of the second wiring layer40on the outer side surface of the backwall portion14.

In this case, at least surfaces of the first and second wiring layers30,40may be formed of a gold (Au) layer respectively, and also the first and second wiring layers30,40may be formed of a stacked metal film in which a copper layer, or the like is formed under the gold layer respectively.

In this manner, the gold tin alloy layer42formed on the outer side surface of the backwall portion14is connected electrically to the indium layer32formed on the inner side surface of the backwall portion14, via the second wiring layer40, the penetration electrode TE, and the first wiring layer30.

Then, as described later, a side surface of a light emitting element (a semiconductor laser element, or the like) is joined to the indium layer formed on the inner side surface of the backwall portion14, and is mounted thereon.

Here, in the present embodiment, the indium layer32is illustrated as the first conductive joining material that is used for mounting the light emitting element on the package component5. Besides it, various solder layers, a conductive paste such as a silver paste, or the like may be used as the first conductive joining material.

Also, the gold tin alloy layer42is illustrated as the second conductive joining material which is formed on the outer side surface of the backwall portion14of the package component5. Similarly, various solder layers, the conductive paste such as the silver paste, or the like may be used.

A depth D of the cavity C of the package component5inFIG. 2Ais set to the depth that enables the light emitting element to be stacked on other package component5without clearance, at the time when the package components5on which the light emitting element is mounted, are to be stacked in the horizontal direction (depth direction).

That is, the depth D of the cavity C of the package component5is set so as to correspond roughly to a total thickness of the first wiring layer30and the indium layer32, the light emitting element, and the second wiring layer40and the gold tin alloy layer42.

Also, preferably a thickness T of the package component5should be set in a range from 400 to 100 μm. And when the package components5on which the light emitting element is mounted are to be stacked in the horizontal direction, an arrangement pitch of the light emitting elements is roughly decided by the thickness T of the package component5.

The package components5of the present embodiment can be manufactured with good precision by finely processing the silicon wafer, based on the photolithography and the wet etching or the dry etching. Therefore, a thickness precision and a surface precision can be improved remarkably rather than the case where the copper tungsten member is employed.

Accordingly, a variation of thickness T (FIG. 2A) can be suppressed within the design specifications among a plurality of package components5.

As a result, By stacking the light emitting elements via the package component5of the present embodiment, a plurality of light emitting elements can be arranged at a narrow pitch with good precision.

Next, a method of manufacturing an light emitting device by stacking the light emitting elements in the horizontal direction while using the above-mentioned package component5will be explained hereunder.

As depicted inFIG. 3, the package component5inFIG. 2Adescribed above is prepared. InFIG. 3, a state in which the package component5inFIG. 2Ais turned over in the lateral direction and is arranged, is depicted schematically.

Then, as depicted inFIG. 4, a light emitting element50like a chip is prepared. The light emitting element50is an end surface emitting type optical device including a light emitting surface A on one end part, and a light is emitted outward from the light emitting surface A. As the light emitting element50, for example, a semiconductor laser element having a double heterojunction structure in GaAs/AlGaAs series is used. An electrode (not shown) is provided on both side surfaces of the light emitting element50respectively.

Then, the electrode on one side surface of the light emitting element50is arranged on the indium layer32of the package component5such that the light emitting surface A of the light emitting element50is directed outward. Then, while pushing the light emitting element50toward the indium layer32side, the heating is applied to the light emitting element50in a temperature atmosphere at about 200° C., and thus the light emitting element50is joined to the indium layer32.

At this time, the indium layer32is alloyed with the underlying first wiring layer30(gold layer), and they become an indium gold alloy layer32x. A melting temperature of the indium layer32is relatively low like 180 to 200° C., but a melting temperature of the resultant indium gold alloy layer32xis increased to about 500° C.

Accordingly, a light emitting element mounting component6is obtained by mounting the light emitting element50on one package component5. Then, such light emitting element mounting component6is prepared in predetermined numbers.

As described above, the light emitting element50may be mounted on the package component5by the solder layer or the conductive paste other than the indium layer32.

Then, as depicted inFIG. 5, a plurality of light emitting element mounting components6are stacked on a processing stage8such that the gold tin alloy layer42of the light emitting element mounting component6located to the upper side is arranged on the electrode on the other side surface of the light emitting element50of the light emitting element mounting component6located to the lower side. Respective light emitting element mounting components6are stacked so as to direct toward the identical direction.

Then, a wiring component60is stacked on the light emitting element mounting component6located to the uppermost part. In the wiring component60, the through hole TH is provided in a silicon substrate62, and an insulating layer63is provided on both surfaces of the silicon substrate62and the inner surface of the through hole TH. Then, the penetration electrode TE made of copper, or the like is filled in the through hole TH.

Then, a first wiring layer64connected to the penetration electrode TE is formed on the upper surface side of the silicon substrate62. A first connection pin70is joined to an indium layer65which is formed on the first wiring layer64on the upper surface side.

Also, a second wiring layer66connected to the penetration electrode TE is formed on the lower surface side of the silicon substrate62. A gold tin alloy layer67is formed on the second wiring layer66on the lower surface side.

Then, the wiring component60is stacked on the light emitting element mounting component6located to the uppermost part such that the gold tin alloy layer67formed on the lower surface side of the wiring component60corresponds to the electrode on the side surface of the light emitting element50of the light emitting element mounting component6located to the uppermost part.

In this state, a stacked structural body inFIG. 5is heated in a temperature atmosphere of about 300° C., while pressing downward by the pressing machine. Accordingly, the light emitting element50of the light emitting element mounting component6located to the lower side and the gold tin alloy layer42of the light emitting element mounting component6located to the upper side are joined together. At the same time, the light emitting element50of the light emitting element mounting component6located to the uppermost part and the gold tin alloy layer67of the wiring component60are also joined together.

At this time, the bottom portion10and the first and second sidewall portions12a,12bof the package component5of the light emitting element mounting component6are put into a simple contact state to other package component5.

At this time, as described above, the depth D of the cavity C (FIG. 2A) of the package component5is also set such that the light emitting elements50are arranged in the depth D direction of the cavity C without clearance. Therefore, a plurality of light emitting element mounting components6and the wiring component60are stacked toward the horizontal direction without inclination.

An arrangement pitch of the stacked light emitting elements50is roughly decided by the thickness T (FIG. 2A) of the package component5. As described above, since the package component5is formed by finely processing the silicon wafer with high precision, a plurality of light emitting elements50can be arranged at a narrow pitch with high precision.

Also at this time, as described above, the indium layer32of each light emitting element mounting component6is also changed into the indium gold alloy layer32xhaving a high melting temperature (about 500° C.) at the time when the light emitting element50is mounted. Therefore, neither the indium gold alloy layer32xis melted again by the heating process (about 300° C.), nor it is possible that a failure of the junction is caused.

As described above, the light emitting element50of one light emitting element mounting component6may be joined to the other light emitting element mounting component6by the solder layer or the conductive paste other than the gold tin alloy layers42,67.

InFIG. 6, such a state is depicted that four light emitting element mounting components6are stacked by the above method and also it is arranged such that the stacking direction is set in the horizontal direction. As depicted inFIG. 6, after the light emitting element mounting components are stacked by the method inFIG. 5, a second connection pin72is joined to the gold tin alloy layer42of the light emitting element mounting component6on the end side opposite to the wiring component60(the lowermost side at the time of stacking inFIG. 5).

Then, an indium layer82is formed on a radiation plate80(heat block) made of metal such as copper, or the like, and the stacked body of the light emitting element mounting components6is pushed toward the indium layer82and is arranged thereon.

The package component5of the present embodiment is formed of the silicon cubic member which is covered with the insulating layer20. Therefore, the stacked body of the light emitting element mounting components6can be mounted on the radiation plate80without intervention of the insulating substrate.

Then, as depicted inFIG. 7, an epoxy resin is coated on the level difference portions S used for positioning the lenses in respective light emitting element mounting components6, then the cylindrical lens84is pushed toward the vertical surfaces of the level difference portions S and is arranged thereon respectively, and then the epoxy resin is cured by the heating process to fix the cylindrical lenses84. At this time, the level difference portion S can be formed in the positions corresponding to the light emitting surfaces A of the light emitting elements50with good precision respectively. Therefore, the cylindrical lenses84are aligned with the light emitting elements50with good precision and are arranged thereon.

As a result, without employment of the complicated alignment mechanism, the cylindrical lenses84can be aligned with the light emitting elements50by the very simple method and can be mounted thereon. Here, in the case that the concave portion is formed as the level difference portion S, the cylindrical lenses84are arranged in the concave portions respectively, thereby the cylindrical lenses84can be aligned with the light emitting elements50and can be mounted thereon.

By the above contents, a light emitting device1of the embodiment is obtained.

InFIG. 8, a perspective view of the structural body, in which the wiring component60and the second connection pin72are omitted from the light emitting device1inFIG. 7to facilitate the explanation, is depicted.

As depicted inFIG. 7andFIG. 8, in the light emitting device1of the present embodiment, a plurality of light emitting element mounting components6having the above-mentioned structure are stacked in the depth direction (horizontal direction) of the cavity C of the package component5. In the example inFIG. 7andFIG. 8, four light emitting element mounting components6are stacked in the horizontal direction. In this case, the stacked number of the light emitting element mounting components6in the horizontal direction can be set arbitrarily.

Also, the wiring component60having the above structure is connected electrically to the light emitting element50of the light emitting element mounting component6located to the endmost part and is stacked thereon (FIG. 7).

Also, the cylindrical lens84is arranged on the level difference portions S used for positioning the lenses in the light emitting element mounting components6respectively. The cylindrical lens84is pushed toward the level difference portion S, thereby the cylindrical lens84is aligned with the light emitting surface A of the light emitting element50and is arranged thereon.

Then, the light emitting device1is mounted on the radiation plate80made of metal via the indium layer82via the indium layer82.

In the light emitting device1of the present embodiment, as depicted inFIG. 7, a plurality of light emitting elements50which are arranged side by side in the horizontal direction are connected electrically in series. An electric current which is supplied from the second connection pin72located to the right side is supplied to the light emitting element50via the gold tin alloy layer42, the second wiring layer40, the penetration electrode TE, the first wiring layer30, and the indium gold alloy layer32x. Also, the electric current is supplied sequentially to the subsequent light emitting elements50via the similar current path, and finally the electric current flows to the first connection pin70side of the wiring component60.

Accordingly, a light is emitted from the light emitting surfaces A of the light emitting elements50respectively, and the emitted lights are converged by the cylindrical lens84respectively and are emitted to the outside as the high-power laser. A heat generated from the light emitting elements50is radiated to the radiation plate80via the underlying indium layer82.

In the present embodiment, since the insulating substrate does not exist in the radiation path, the good radiating characteristic can be obtained. Accordingly, reliability of the light emitting device1can be improved, and the light emitting device1is advantageous from such a viewpoint that a component count can be reduced.

Here, in the present embodiment, based on that the penetration electrode TE is provided in the backwall portions14of the package components5respectively, the adjacent light emitting elements50are connected electrically in series and the electric current is supplied through there. But there is no necessity that the penetration electrode TE should always be provided to the package component5.

In case that the penetration electrode TE is not provided to the package component5, a lead terminal, or the like connected to the light emitting elements50is fitted to the package components5respectively, and the electric current is supplied individually.

In the light emitting device1of the present embodiment, a plurality of light emitting elements50are stacked in the horizontal direction via the package component5which is formed of the silicon cubic member. Since the silicon cubic member is manufactured with high precision by the fine processing, a sufficient thickness precision and a sufficient surface precision can be obtained. Therefore, the light emitting elements50can be stacked at a narrow pitch with good precision, and thus the stacked type light emitting device which is made small size can be constructed with good precision.

Further, the level difference portion S used for positioning the lens can be provided in the package component5so as to align with the position of the light emitting surface A of the light emitting element50which is to be mounted. Accordingly, without employment of the complicated aligning mechanism, the cylindrical lens84can be arranged while easily aligning with the light emitting element50, and thus a reduction in cost can be achieved.

FIG. 9is a fragmental enlarged sectional view of a light emitting device1aaccording to a first variation of the embodiment. As depicted inFIG. 9, in the light emitting device1aof the first variation, in the outer side surface of the backwall portion14of the package component5, a concave portion14xused to pour the melted gold tin alloy layer42is provided in the lower side of the gold tin alloy layer42.

InFIG. 9, a state obtained after a plurality of light emitting element mounting components6are stacked in the horizontal direction, is depicted. The gold tin alloy layer42which is melted at the time of joining step flows into the concave portion14xof the backwall portion14, and is collected there.

Accordingly, the excessive gold tin alloy layer42flows into the concave portion14xand is collected there. As a result, a variation in the thickness of the gold tin alloy layer42for joining the light emitting element50can be suppressed, and a precision of the arrangement pitch of the light emitting elements50can be improved further more.

Also,FIG. 10is a fragmental enlarged sectional view of a light emitting device1baccording to a second variation of the embodiment. As depicted inFIG. 10, in the light emitting device1bof the second variation, a concave portion10xused for the fitting is provided in the outer side surface at the rear of the bottom portion10of one package component5. Then, a convex portion10yused for the fitting is provided on the outer side surface at the front of the bottom portion10of the other package component5so as to protrude along the horizontal direction.

When a plurality of light emitting element mounting components6are stacked in the horizontal direction, the convex portion10yof the bottom portion10of the other package component5is fitted into the concave portion10xof the bottom portion10of one package component5. Accordingly, when the light emitting element mounting components are arranged in the horizontal direction, a misalignment in the vertical direction between a plurality of light emitting element mounting components6can be prevented, and reliability of the light emitting device can be improved further more.