JPH1056238A - Semiconductor laser device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin packaged semiconductor laser device and its manufacturing method by which no peeling-off or breakage in the boundary face between an end face breakage prevention layer and a sealing resin is generated and stable electric and optical characteristics can be realized. SOLUTION: In this device, a laser diode chip 1 is fixed on a metallic main board 3 by means of a sub-mount 2 in which a photo diode for monitor is built in, and it is covered with a end face breakage prevention layer 5 adjacent to its light emitting face that prevents a sealing resin 6 from being broken by a laser light, and further the laser diode chip 1, a sub-mount 2, a layer 5, and a board 3 are all packaged with the resin 6. In this case, since a through hole 6a from the surface of the layer 5 to the outer surface of the resin 6 is provided, the thermal stress of the layer 5 can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device having a laser diode chip sealed with a resin, which is used for an optical disk device or the like.

[0002]

2. Description of the Related Art FIG. 9 is a perspective view of a conventional resin-sealed semiconductor laser device. The laser diode chip 1 is bonded to a main plate 3 integrated with a common post 3a via a submount 2 (Si crystal) having a built-in monitor photodiode 2p. Bonding wires 4 are respectively connected between the other two posts 3b separated from the main plate 3 and the laser diode chip 1 and the monitoring photodiode 2p. The main plate 3, the common post 3a and the post 3b are cut and separated from the same lead frame. The laser diode chip 1 is covered with a light-transmitting end face destruction prevention layer 5 and further sealed with a light-transmitting sealing resin 6. The sealing resin 6 holds the main plate 3 and the posts 3 a and 3 b at predetermined relative positions. It is fixed to. The end face destruction prevention layer 5 is provided to prevent the sealing resin 6 near the light emitting end face of the laser diode chip 1 from being broken by laser light. The laser light is emitted along the laser optical axis 1x in an elliptical cone shape having a vertex at the end face of the laser diode chip 1. Both ends of the main plate 3 protrude from the sealing resin 6 as fixed ends 3s for fixing to a jig of an optical applied device on which the semiconductor laser device is mounted. The ends of the posts 3a and 3b also protrude from the sealing resin 6, and are connected by soldering to the lead to the drive power supply of the laser diode chip 1 and the lead to the optical output monitor circuit, respectively.

The end face destruction prevention layer 5 is made of, for example, a silicone resin. After liquid silicone is applied dropwise so as to cover the laser diode chip 1 and the submount 2, it is heated in a furnace at 120.degree. Is cured. Next, the epoxy-based sealing resin 6 is formed by injection molding. The injection molding is performed at a temperature of 150 ° C. or more, and is cooled to room temperature after the injection molding. However, since the end face destruction prevention layer 5 has a larger coefficient of thermal expansion than the sealing resin 6, the surface of the laser diode chip 1 and the sealing resin 6 Tensile stress is exerted by the adhesive force on the surface. FIG. 10 is a sectional view of a conventional resin-encapsulated semiconductor laser device. The cross section is a plane including the laser optical axis 1x and perpendicular to the main plate, and all the cross-sectional views are the same hereinafter. The end face destruction prevention layer 5 has the largest volume behind the laser diode chip 1 and on the upper surface of the submount 2. Since the adhesion between the end surface destruction prevention layer 5 and the sealing resin 6 varies, if the adhesion is smaller than the cutting force of the end surface destruction prevention layer 5, the distance between the end surface destruction prevention layer 5 and the sealing resin 6 is reduced. 5a may occur, and if the adhesive force is greater than the material strength of the end face destruction preventing layer 5, the end face destruction preventing layer 5 may be located at a position located on the monitor photodiode 2p where the volume shrinkage is greatest. Cracks 5b may be formed on the surface.

[0004]

A semiconductor laser device is used by being incorporated in various optical devices such as an optical disk such as a compact disk and a laser beam printer. In these devices, in order to obtain a stable digital signal, highly accurate and stable light intensity is required simultaneously with the position and direction of the light emitting point with high accuracy.

[0005] The laser diode chip is fixed to a submount having a built-in monitor photodiode having a light receiving surface on the upper surface, and the monitor photodiode can monitor emitted light on the rear side of the laser diode chip. . The size of the laser light emitting portion on the light emitting end face of the laser diode chip is about 5 μm × 1 μm, and the emitted monitor laser light has a full width at half maximum of the laser light intensity distribution of about 10 degrees in the horizontal direction (in the main plate plane direction). It radiates at a spread angle of about 40 degrees in the vertical direction (vertical direction of the main plate). When the above-mentioned partial peeling occurs, the peeled part has a higher light reflectance than the unpeeled part, and strongly reflects the laser light emitted from the laser diode chip. Therefore, when the laser diode chip emits light with a predetermined light output, the monitor current value of the monitor photodiode that receives the rear-side emission light increases, and the front-side emission light cannot be accurately controlled. Also,
When a crack occurs in the end face destruction prevention layer, the amount of light entering the monitor photodiode changes due to the multiple scattering of light at the crack or the breakage of the monitor laser beam, and the output monitor current Was also a problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem, and alleviates the thermal stress at the time of forming the end face destruction preventing layer, thereby preventing the end face destruction preventing layer from being directly irradiated with the monitor laser beam. To provide a resin-encapsulated semiconductor laser device having stable electrical and optical characteristics without peeling between the resin and the sealing resin, and without generation of cracks in the end face destruction prevention layer, and a method of manufacturing the same. It is.

[0007]

In order to achieve the above object, a laser diode chip is fixed on a metal main plate via a submount having a built-in monitor photodiode, and the laser diode chip and the submount are fixed to each other. In a semiconductor laser device covered with an end face destruction prevention layer, and further, the laser diode chip, the submount, the end face destruction prevention layer and the main plate are sealed with a sealing resin, an interface between the end face destruction prevention layer and the sealing resin is provided. A gap is provided in a portion irradiated with a light intensity equal to or less than a half value of the peak of the monitor laser light intensity.

[0008] Further, a laser diode chip is fixed on a metal main plate via a submount having a built-in monitor photodiode, and the laser diode chip and the submount are covered with an end face destruction prevention layer.
Further, in a semiconductor laser device in which the laser diode chip, the submount, the end face destruction prevention layer, and the main plate are sealed with a sealing resin, a half value of a peak of a monitor laser beam intensity at an interface between the end face destruction prevention layer and the sealing resin is obtained. Non-adhesion portions that are in contact with each other but are not fixed are provided at portions to be irradiated with the following light intensities.

A laser diode chip is fixed on a metal main plate via a submount having a built-in monitor photodiode, and the laser diode chip and the submount are covered with an end surface destruction preventing layer.
Further, in a semiconductor laser device in which the laser diode chip, the submount, the end face destruction prevention layer, and the main plate are sealed with a sealing resin, a half value of a peak of a monitor laser beam intensity at an interface between the end face destruction prevention layer and the sealing resin is obtained. In the portion where the following light intensity is applied, a notch is formed from the surface of the end surface destruction prevention layer toward the inside.

Preferably, the gap is a through hole extending from the surface of the end face destruction preventing layer to the outer surface of the sealing resin. The through-hole may be formed by a pin provided in a molding die of a sealing resin. It is preferable that the tip of the pin in contact with the end surface destruction prevention layer is separated from the bonding wire connected to the submount.

It is preferable that the surface of the main plate on the side opposite to the submount is supported by a support during resin sealing using a molding die for molding the sealing resin. The non-adhesive portion of the end face destruction prevention layer may be formed by pressing a predetermined ironing face of the end face destruction prevention layer with a hard iron before resin sealing.
The cuts in the end face destruction prevention layer are preferably formed by cutting with a knife.

In any of the above means of the present invention,
Since the end surface destruction prevention layer has a movable portion that can move freely without being in close contact with the sealing resin, strain generated due to a difference in thermal expansion coefficient between the two resins at and around the boundary surface between the two resins is movable. The thermal stress at the contacting portion is reduced by escaping to the portion, and the contacting portion does not have a crack in the end surface breakdown prevention layer or a gap with the sealing resin. Therefore, the reflection of the laser beam at that portion is not disturbed, and
Since the movable part is a part that irradiates only less than half the intensity of the laser light peak, the intensity of light incident on the monitor photodiode due to disturbance of reflection at the movable part is small, and the entire light incident on the monitor photodiode is small. Changes in intensity are small. Therefore, a stable monitor current with respect to the ambient temperature can be obtained.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 1 shows a sectional view of a semiconductor laser device according to an embodiment of the present invention. Only the differences from the prior art will be described. The end surface destruction prevention layer 5 is made of silicone resin, is formed with a thickness of about 300 μm from the surface of the main plate 3 on which the submount 2 is mounted, and the periphery thereof is sealed with a sealing resin 6. Sealing resin 6
An epoxy resin or an acrylic resin having a high light transmittance is suitable for this. In this example, an epoxy resin was used. From the surface of the end surface destruction preventing layer 5 of the sealing resin 6 to the sealing resin 6
A through hole 6a reaching the outer surface of the substrate was made. Further, the opening of the through hole 6a on the surface of the end face destruction prevention layer 5 comes to a portion of the interface between the end face destruction prevention layer and the sealing resin to which a light intensity equal to or less than half the peak of the monitor laser light intensity is irradiated. I did it. For this reason, the area where the end face destruction prevention layer 5 and the sealing resin 6 come into close contact with each other is reduced by the amount of the through hole, and even if the end face destruction prevention layer 5 shrinks after molding the sealing resin, the amount of pulling of the end face destruction prevention layer 5 is small. And the stress generated can be reduced.
In addition, since the opening is located at the position where the irradiation intensity of the laser beam is low as described above, when the ambient temperature of the semiconductor laser device changes during use, the surface of the end face breakdown prevention layer 5 in the opening slightly shifts. However, the influence of the reflected light of the monitor laser light on the monitor photodiode 2p at that portion is small, and the monitor current is stable with respect to the ambient temperature.

Next, an example of a manufacturing method for forming such a through hole will be described. FIG. 2 is a sectional view at the time of injection molding of the semiconductor laser device according to the present invention. By providing a pin 12 in a molding die 11 used for injection molding of the sealing resin 6, the sealing resin 6 having a through hole is formed. The pin 12 of the molding die 11 has a structure in which the end face destruction prevention layer 5 is pressed, but the resin molding pressure is 30 to 5
0 N / cm ² , and the pins 12 are set so that the end face destruction prevention layer 5 is depressed inward by about 40 μm so that the sealing resin 6 does not flow between the pin 12 and the end face destruction prevention layer 5.
The pin 12 is movable in the molding die 11 so that the amount of depression can be adjusted even if the thickness of the end face destruction preventing layer 5 varies. The silicone resin which is a constituent material of the end face destruction prevention layer 5 has a soft rubber shape,
When the pin 12 is recessed by about 40 μm, there is no influence such as cracking. When the pin is removed after molding, the original shape is restored.

A pin 12 for forming the through-hole 6a crushes the end face breakdown prevention layer 5, but when the pin 12 presses just above the bonding wire on the submount 2, the bonding wire 4 is crushed, and the wire breakage or disconnection occurs. Failures such as short circuits may occur. The structure for avoiding this will be described below. FIG. 3 is a perspective view of another semiconductor laser device according to the present invention as viewed from above. A through hole is provided above the light receiving portion of the monitor photodiode 2p, and the shape of the tip of the pin (corresponding to the shape of the opening 5f of the through hole 6a) is on the light receiving surface of the monitor photodiode 2p. In addition, the shape was formed by a polygon or a curve so as not to reach the vertically upper part of the bonding wire 4. As a result, even if the pin was pressed slightly strongly, the disconnection or short circuit of the bonding wire 4 did not occur. Second Embodiment In the first embodiment, since the pins press the silicone resin from above during the injection molding of the sealing resin, the main plate of the lead frame may be bent and the position of the laser diode chip, that is, the laser optical axis may be shifted. In order to avoid this, the following structure was adopted. FIG. 4 is a sectional view of another semiconductor laser device according to the present invention at the time of injection molding. By providing a fixed back pin 13 supported from the back of the main plate 3 (a state not yet cut from the lead frame) on the molding die 11 and performing the injection molding of the sealing resin 6 while supporting the main plate 3. The structure is such that the deformation of the main plate 3 due to the pins 12 pushing down the end face destruction prevention layer 5 during injection molding is prevented. As a result, no deviation of the laser optical axis occurred.

The back pins of the mold can be replaced by rods of the same shape made of resin, in which case the rods become part of the sealing resin. Embodiment 3 FIG. 5 is a cross-sectional view of a semiconductor laser device according to the present invention in which a secondary sealing is performed. FIG.
(B) shows a case where the back surface is supported. After molding the sealing resin 6, an adapter ring 8 is attached to the fixed end 3s of the main plate 3, and the periphery of the sealing resin 6 is secondarily sealed with another secondary sealing resin 7 to integrate the semiconductor laser device. Next, the case where the present invention is applied will be described. As the secondary sealing resin 7, an epoxy resin for semiconductor sealing was used. The secondary sealing resin 7 penetrates into the through holes 6a of the sealing resin 6, but since the secondary sealing resin contains a large amount of a release agent, the secondary sealing resin 7 has no wettability with the end face destruction prevention layer 5,
Does not stick to each other. In addition, since the thermal shrinkage of the end face destruction prevention layer 5 is larger than that of the secondary sealing resin 7, a gap 5c is formed between the end face destruction prevention layer 5 and the secondary sealing resin 7 after cooling. Also in the semiconductor laser device thus secondary-sealed, the end surface breakdown prevention layer 5 has a portion that is not tightly bound similarly to the through hole in the first embodiment, so that a thermal stress relaxation effect can be obtained. Example 4 By modifying the surface of the end face destruction prevention layer 5, the adhesion between the end face destruction prevention layer 5 and the sealing resin 6 can be reduced, and the thermal stress at the time of molding the sealing resin can be reduced.

FIG. 6 is a cross-sectional view at the time of the step of modifying the surface of the end face destruction preventing layer according to the present invention. After the ironing iron 14 heated to about 300 ° C., such as a metal wire or a metal rod, is pressed against the end face destruction prevention layer 5, and a part of the surface of the end face destruction prevention layer 5 is heat-treated. Stopped. FIG. 7 is a cross-sectional view of a semiconductor laser device for modifying the surface of the end face breakdown prevention layer according to the present invention. Since only the heat-treated portion of the end surface destruction prevention layer 5 and the sealing resin 6 do not adhere to each other, the temperature at the time of injection molding is 160.
When cooled from room temperature to room temperature, the end face destruction prevention layer 5 has a larger shrinkage due to a difference in linear expansion coefficient, so that a peeled portion 5a of about 50 μm is generated. The heat-shrinkage stress is absorbed by the peeling portion 5a, and the portion where the monitor laser beam 1b emitted from the laser diode chip 1 is irradiated on the surface of the end face destruction preventing layer 5 is not subjected to heat treatment, so that peeling has occurred. The reflectance is constant, and the monitor photodiode 2
The amount of light monitored by p and the output monitor current were not affected by the ambient temperature, and stable electrical and optical characteristics were obtained.

Also, it is needless to say that the heat treatment applied to the end face destruction preventing layer by the iron in this way is sealed with a sealing resin, and then a secondary sealing with a general semiconductor sealing epoxy resin. It is also possible to stop. Example 5 A structure in which a cut was made in the surface of the end surface breakdown prevention layer 5 to disperse stress was attempted. FIG. 8 is a cross-sectional view of a semiconductor laser device according to the present invention, which has a cut in the end face breakdown prevention layer. A thin knife is inserted into the surface of the end face destruction prevention layer 5 located behind the laser diode chip 1,
After adding d, the sealing resin 6 was injection molded. At the time of cooling after molding, the end face destruction prevention layer 5 tends to shrink, but the interface between the end face destruction prevention layer 5 and the sealing resin 6 is divided into two parts, a front part and a rear part, with the cut as a boundary. , The volume of the end face destruction prevention layer is also divided and reduced, and the generated thermal stress is reduced. In addition, the cut absorbs the tensile stress generated between the end face destruction prevention layer 5 and the sealing resin 6, and the thermal stress generated in the end face destruction prevention layer 5 is reduced. The laser beam 1b emitted from the rear of the laser diode chip 1 has a vertical extent of about 20 degrees on one side, but the cut is made to a depth that does not block the laser beam.

Naturally, a structure in which a notch is cut into the end face destruction prevention layer with a knife and sealed with a sealing resin and then secondary sealed with a normal semiconductor sealing epoxy resin is used. Applicable.

[0020]

According to the present invention, a laser diode chip is fixed on a metal main plate via a submount having a built-in monitor photodiode, and the laser diode chip is formed of a sealing resin near a light-emitting end face. Coated with an end-face destruction prevention layer that prevents destruction by laser light,
Further, in a semiconductor laser device wherein the laser diode chip, the submount, the end face destruction prevention layer, and the main plate are sealed with a sealing resin, the sealing resin includes an outer surface of the sealing resin from a surface of the end face destruction prevention layer. Is provided. Alternatively, the surface of a portion of the end face destruction prevention layer that irradiates only less than half the intensity of the laser beam intensity is modified to reduce the adhesiveness or to have a cut in that part. Has a free part that does not come into close contact with
The strain generated due to the difference in the thermal expansion coefficients of the two types of resin in the portions of the two types of sealing resin that are in contact with each other escapes to the free portion, the thermal stress in the portion in contact is reduced, and the end face in the portion in contact There are no cracks in the destruction prevention layer and no gaps with the sealing resin. Therefore, the reflection of the laser light at that portion is not disturbed, and the free portion is a portion that irradiates only less than half the peak of the laser light intensity, so that the reflection to the monitoring photodiode due to the disturbance of the reflection at the free portion. Is small, and the intensity change of the entire light incident on the monitoring photodiode is small. Thus, a monitor current that is stable with respect to the ambient temperature can be obtained.

Further, according to the present invention, the through hole of the sealing resin for relaxing the thermal stress is made by using a mold, the surface modification of the end face destruction prevention layer is made by using an iron, or the cut is made by inserting a knife. As a result, the stability of the monitor current is improved and the production yield is high.

[Brief description of the drawings]

FIG. 1 is a sectional view of a semiconductor laser device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the semiconductor laser device according to the present invention during injection molding.

FIG. 3 is a perspective view of another semiconductor laser device according to the present invention as viewed from above.

FIG. 4 is a cross-sectional view of another semiconductor laser device according to the present invention during injection molding.

FIG. 5 is a cross-sectional view of a secondary sealed semiconductor laser device according to the present invention, in which (a) no backside support is provided, and (b) backside support is provided.

FIG. 6 is a cross-sectional view at the time of modifying the surface of the edge-breakdown prevention layer according to the present invention.

FIG. 7 is a cross-sectional view of a semiconductor laser device for modifying the surface of an end surface breakdown prevention layer according to the present invention.

FIG. 8 is a cross-sectional view of a semiconductor laser device according to the present invention, which has a cut in the end face breakdown prevention layer.

FIG. 9 is a perspective view of a conventional resin-encapsulated semiconductor laser device.

FIG. 10 is a cross-sectional view of a conventional resin-encapsulated semiconductor laser device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laser diode chip 1 b monitor laser light 1 x laser optical axis 2 submount 2 p monitor photodiode 3 main plate 3 a common post 3 b post 3 s fixed end 4 bonding wire 5 end surface break prevention layer 5 a peeling portion 5 b crack in end surface break prevention layer 5 c Gap 5d Cut 5f Opening 6 Sealing resin 6a Through hole 7 Secondary sealing resin 7p Secondary sealing resin pin 8 Adapter ring 11 Mold 12 Pin 13 Back pin 14 Ironing iron

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiromi Mengagawa 1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Inventor Yoichi Shindo 1, Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa # 1 Fuji Electric Co., Ltd. Company Chichibu Fuji

Claims (9)

[Claims] 1. A laser diode chip is fixed on a metal main plate via a submount having a monitor photodiode built therein. The laser diode chip and the submount are covered with an end face destruction prevention layer. In a semiconductor laser device in which the submount, the end face destruction prevention layer and the main plate are sealed with a sealing resin, the light intensity is equal to or less than half the peak of the monitor laser light intensity at the interface between the end face destruction prevention layer and the sealing resin. A semiconductor laser device having an air gap in a portion to be irradiated. 2. A laser diode chip is fixed on a metal main plate via a submount containing a monitor photodiode. The laser diode chip and the submount are covered with an end face destruction prevention layer. In a semiconductor laser device in which the submount, the end face destruction prevention layer and the main plate are sealed with a sealing resin, the light intensity is equal to or less than half the peak of the monitor laser light intensity at the interface between the end face destruction prevention layer and the sealing resin. A non-contact portion that is in contact with each other but is not fixed to a portion to be irradiated with a laser beam. 3. A laser diode chip is fixed on a metal main plate via a submount containing a monitor photodiode. The laser diode chip and the submount are covered with an end face destruction prevention layer. In a semiconductor laser device in which the submount, the end face destruction prevention layer and the main plate are sealed with a sealing resin, the light intensity is equal to or less than half the peak of the monitor laser light intensity at the interface between the end face destruction prevention layer and the sealing resin. A semiconductor laser device having a notch from a surface of an end surface destruction prevention layer toward an inside at a portion irradiated with a laser beam. 4. The semiconductor laser device according to claim 1, wherein the gap is a through hole extending from the surface of the end surface destruction preventing layer to the outer surface of the sealing resin. 5. A method of manufacturing a semiconductor laser device according to claim 4, wherein said through hole is formed by a pin provided in a molding die of a sealing resin. 6. The method of manufacturing a semiconductor laser device according to claim 5, wherein a tip portion of said pin which is in contact with an end surface destruction preventing layer is separated from a bonding wire connected to a submount. 7. The main plate is supported by a support on the opposite side of the main plate at the time of resin sealing using a mold for molding the sealing resin. 3. The method for manufacturing a semiconductor laser device according to 1. 8. The non-adhesive portion of the end face destruction prevention layer according to claim 2, wherein the non-adhesion part is formed by pressing a predetermined ironing surface of the end face destruction prevention layer with an iron before resin sealing. A method for manufacturing a semiconductor laser device. 9. A method for manufacturing a semiconductor laser device according to claim 3, wherein the notch in the end face destruction preventing layer is formed by cutting with a knife.