JPS61292984A - Semiconductor laser element and photoelectronic device into which said laser element is incorporated - Google Patents

Abstract

PURPOSE:To obtain a semiconductor laser element having high reliability by forming a groove, which is shaped in parallel with the main surface of a substrate on both sides of a resonator and divides a P-N junction, and a passivation film coating the surface of the groove. CONSTITUTION:The surface on the side where a resonator 11 is mounted, the main surface, is flattened. Consequently, when a laser chip 1 is fixed to a mounting plate such as a sub-mount 14 through a cementing body 15 such as solder, the main surface as a fixing surface is flattened, thus preventing the inclined fitting of the laser chip 1, then keeping the position of the resonator 11 constant. A double hetero-junction is divided by grooves 12. Since the grooves 12 are formed through etching, the crystallizability of the surfaces of the grooves are made extremely better than that by rupture the due to scribing, etc. The surface is coated with a passivation film 13. Accordingly, the leakage of currents in the double hetero-junction exposed to the surfaces of the grooves 12 is inhibited, thus preventing the generation of the deterioration of characteristics, then improving reliability.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a semiconductor laser device or an integrated optical device (OEIC device) having such a semiconductor laser device section.
The present invention relates to an optoelectronic device incorporating such a device.

[Background technology]

As one of the light sources for information processing devices such as digital audio discs, video discs, optical disc files, and laser beam printers, for example, it is used as a light source for information processing equipment such as digital audio discs, video discs, optical disc files, and laser beam printers.
em1conduc-Lor World)” 198
May 2015 issue, published April 15, 1980, P25-P2
As described in 9, C3P (channeled-s
U-Bstrate-planar) type semiconductor laser devices have been developed.

Furthermore, as described in the above-mentioned literature, the cavity end face of GaAlAs semiconductor lasers is prone to deterioration.

Therefore, in order to prevent deterioration of the resonator end faces, a passivation film made of a dielectric thin film is provided on the resonator end faces.

On the other hand, semiconductor laser devices are not limited to the above-mentioned CSP type semiconductor laser, but also have improved characteristics such as transverse mode stabilization, lower output, and higher reliability, as described in many documents including the above-mentioned document. There is a need for improvements in manufacturing yields.

The present invention was achieved with the aim of improving the reliability of semiconductor laser devices.

[Purpose of the invention]

An object of the present invention is to provide a highly reliable semiconductor laser device.

Another object of the present invention is to provide a semiconductor laser device that can improve bonding accuracy.

Another object of the present invention is to provide a semiconductor laser device that can improve yield.

The above and other objects and novel features of the present invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

That is, according to the present invention, grooves are provided on both sides of the resonator to separate the pn junction in parallel with the resonator on the flat main surface of the laser chip, and a passivation film is provided on the surface of the groove. This prevents current leakage at the side exposed portion of the pn junction and improves reverse breakdown voltage characteristics.In addition, when the laser chip is mounted on the mounting plate, the main surface is flat, so the laser The chip is no longer installed at an angle, and bonding accuracy and retention can be improved.

〔Example〕

FIG. 1 is an enlarged sectional view showing a CSP type semiconductor laser device according to an embodiment of the present invention, FIG. 2 is a perspective view of a semiconductor laser device with a portion cut away, and FIG. An enlarged cross-sectional view showing the bonding state of the chip,
4 to 8 are diagrams showing a method of manufacturing a laser chip, in which FIG. 4 is a cross-sectional view of a wafer with channels formed on its main surface, and FIG. 5 is a cross-sectional view of a wafer with a multilayer growth layer formed. Figure 6 is a cross-sectional view of the wafer with grooves formed on its main surface, Figure 7 is an enlarged cross-sectional view of the wafer with a diffusion layer formed, and Figure 8 is a cross-sectional view of the wafer with a passivation layer formed. FIG. 2 is a cross-sectional view of a wafer with a film formed thereon.

The CSP type semiconductor laser device according to this embodiment has a first
The structure is as shown in the figure.

That is, the semiconductor laser element (laser chip) ■ is n
The structure has a multilayer growth layer 3 on a substrate 2 made of GaAs (GaAs substrate), an anode electrode 4 on the top surface of the multilayer growth layer 3, and a cathode electrode 5 on the bottom surface of the substrate 2. There is. A groove (channel) 6 having both sides inclined is provided in the center of the main surface of the substrate 2 . Further, the multilayer growth layer 3 is made of n-type Ga formed directly on the main surface of the substrate 2.
A cladding layer 7 made of AJIAs, an active layer 8 made of GaAJIAs formed on the top surface of this cladding layer 7, a craft layer 9 made of p-type GaAJIAS formed on the top surface of this active layer 8, and the top surface of this cladding layer 9. The cap layer 10 is made of n-type GaAs and has a four-layer multilayer structure. Further, the striped active layer 8 region corresponding to the groove 6 constitutes a resonator (optical waveguide) 11. On both sides of this resonator 11 are pn junctions, that is, cladding layers 9. Active layer 8. A groove 12 reaching up to the cladding layer 7 is provided so as to divide the double heterojunction made of the cladding layer 7. This groove 12 extends parallel to the resonator 11 . Further, the surface portion of the groove 12 is covered with a passivation film 13.

As a result, the surface on which the resonator 11 is provided, that is,
The main surface is flat. Therefore, as shown in FIG. 3, when the laser chip 1 is fixed to a mounting plate such as a submount 14 via a joint 15 such as a solder, the main surface serving as the fixing surface is flat. Therefore, the laser chip l will not be installed at an angle,
The position of the resonator 11 becomes constant. Further, the double heterojunction is separated by the groove 12. Further, since the groove 12 is formed by etching, the crystallinity of the groove surface is extremely good compared to the case where the groove is broken by scribing or the like. Furthermore, the top surface is covered with a passivation film 13. Therefore, current leakage at the double heterojunction exposed on the surface of the groove 12 is suppressed, so that characteristic deterioration is less likely to occur and reliability is increased.

Further, in the cap layer 10, a p-type diffusion layer 16 (dotted region in the figure) is formed by partial diffusion of zinc (Zn) that reaches halfway into the cladding layer 9. . This diffusion layer 16 is provided to establish ohmic contact with the anode electrode 4.

Next, while referring to Figures 4 to 8 and Figure 1, c.
A method for manufacturing an sp-type semiconductor laser device will be described.

The C3P type semiconductor laser device (laser chip) in this example is manufactured by sequentially performing various treatments on a compound semiconductor thin plate (wafer) as shown in FIGS. 4 to 8, and then as shown in FIG. It becomes a semiconductor laser element.

That is, when manufacturing a laser chip, first, as shown in FIG. 4, a compound semiconductor thin plate (wafer) 17 made of GaAs is prepared. This wafer 17 has a thickness of 20
It consists of a rectangular n-type GaAs substrate (substrate) 2 with a diameter of approximately 0 μm, and a groove (channel) 6 of approximately 40 μm on the main surface (upper surface).
They are provided in parallel at intervals of m. This groove 6 is formed by etching using an insulating film as a mask 18, and has a width of several μm and a depth of several μm.

Next, as shown in FIG.
On the main surface of 7, n-type Ga was deposited by liquid phase epitaxial method.
Cladding layer with AJIAs7. Active layer 8 made of GaAJlAS. Cladding layer of p-type GaAJIAs9.
A cap layer 10 of p-type GaAs is sequentially formed, and a multilayer growth layer 3 is formed. The thickness of each layer constituting the multilayer growth layer 3 does not necessarily correspond to the drawing, but for example, in the case of the cladding layer 7, it is 0.2 to 0.3 μm.
approximately 0.1 μm for the active layer 8, and approximately 0.1 μm for the cladding layer 9.
In the case of , the thickness is about 2 μm, and in the case of the cap layer 10, it is about 1 μm. The active layer 8 forms a heterojunction between the upper and lower cladding layers 7 and the cladding layer 9, forming a double heterojunction structure.

Next, as shown in FIG. 6, grooves 12 are formed in the main surface of the wafer 17 by etching using an insulating film as a mask 19. One groove 12 is provided on both sides of each resonator 11 in parallel to the groove 12. This groove 1
2 is provided so as to reach the surface layer of the substrate 2 and divide a pn junction (double heterojunction).

Next, as shown in FIG. 7, an insulating film 20 is formed on the main surface of the wafer 17 by CVD (chemical vapor deposition), and this insulating film 20 is formed by photolithography.
0, the portion corresponding to the resonator 11 is removed. and,
Using this insulating film 20 as a mask, zinc (Zn) is implanted into the main surface of the wafer 17, forming a diffusion layer 16 (dotted region in the figure) that reaches halfway into the cladding layer 9. . This diffusion layer 16 becomes an ohmic layer of a contact electrode.

Next, the insulating film 20 is removed. Thereafter, the groove 12 and its surrounding area are covered with a passivation film 13.

Next, the back surface of such a wafer 17 is etched so that the thickness of the wafer 17 is about 100 μm. Thereafter, as shown in FIG. 1, an anode electrode 4 is provided on the main surface of the wafer 17, and a cathode electrode 5 is provided on the back surface. The anode electrode 4 is made of cr/Au, and the cathode electrode 5 is made of AuGeNi/Pd/Au, both of which are formed by vapor deposition alloy.

Next, such a wafer 17 is divided into vertical and horizontal directions, and a large number of laser chips 1 as shown in FIG. 1 are manufactured. For example, the laser chip 1 has a width of 400 μm,
The length is 300 μm and the height is 100 μm, and when a predetermined voltage is applied to the anode electrode 4 and the cathode electrode 5, a laser beam is oscillated from the end face (mirror surface) of the resonator 11 having a length of 300 μm. Note that this laser chip 1 is used while being fixed to a support plate via an anode electrode 4 or a cathode electrode 5.

The laser chip 1 is used as a light emitting source of a semiconductor laser device, as shown in FIG. Laser chip 1
is fixed via a submount 14 to one side of a copper heat sink 22 provided at the center of the upper surface (principal surface) of a rectangular copper stem 21 . For fixing, as shown in FIG. 3, a bonding body 15 such as solder is used. At this time, since the main surface of the laser chip 1 serving as the connection surface is flat, the laser chip 1 will not be installed at an angle, and the position of the resonator 11 will be constant. That is, although the laser chip 1 is required to have a rotational deviation of the light emitting axis of 1 degree or less, this condition can be satisfied with a margin. Furthermore, a light receiving element 23 is fixed to the main surface of the stem 21 before the laser chip 1 is fixed. The light receiving element 23 serves as a monitor element that receives the laser beam 24 emitted from the lower end of the laser chip 1 and detects the optical output. The stem 21 has three leads 2.
5 is installed. One lead 25 is also electrically connected to the stem 2, and the other two leads 25 are connected to the stem 2.
and is insulatively fixed to the stem 2 via an insulator 26. Next, connect the upper ends of these two through-holes 25 to the laser chip l and the light receiving element 2.
The three electrodes are electrically connected via wires 27, respectively.

Next, a transparent glass plate 28 is attached to the ceiling of the stem 21.
A metal cap 30 having a circular window 29 is hermetically fixed to the heat sink 22.
, the laser chip 1, the light receiving element 23, the upper end of the lead 25, the wire 27, etc. are hermetically sealed. Therefore, the laser beam 24 emitted from the upper end of the laser chip 1 passes through this window 2.
9 and is emitted outside the package formed by the stem 21 and the cap 30. Incidentally, the stem 21 is provided with a mounting hole 31 that is used when mounting this semiconductor laser device on various types of equipment.

〔effect〕

(11 According to the present invention, a groove is provided on the main surface of the laser chip to divide the pn junction, and the groove is covered with a pansivation film, so current leakage at the exposed end of the pn junction can be reduced, and the characteristics The effect is that deterioration can be prevented.

(2) According to the present invention, the groove provided in the main surface of the laser chip in order to reduce current leakage at the exposed pn junction portion is partial, and the main surface of the laser chip is flat. When this laser chip side is bonded to the mounting plate, since the laser chip does not tilt, the positional shift of the light emitting axis, that is, the rotational shift is less likely to occur, and the bonding accuracy of the laser chip is improved.

(3) According to the above (1), according to the present invention, it is possible to easily and accurately align the optical axes of a laser chip and an optical system such as an optical fiber.

(4) According to the above (2) and (3), according to the present invention, the yield of chip bonding and optical axis alignment in the production of optoelectronic devices is improved.

(5) According to the above (1) to (4), according to the present invention, a synergistic effect is obtained in that highly reliable laser chips and optoelectronic devices can be provided at low cost.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor.

[Application field]

The above explanation has mainly been about the case where the invention made by the present inventor is applied to the technology for manufacturing semiconductor laser devices for information processing, which is the field of application that forms the background of the invention.
The present invention is not limited thereto, and can be applied to, for example, semiconductor laser element manufacturing technology for optical communications.

At least the present invention provides a laser chip having a flat surface on the side where a resonator is present, or an 0EIC chip having a flat main surface and a flat surface having a laser emitting part as described above, and a photoelectronic device incorporating these chips. Applicable to equipment.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is an enlarged sectional view showing a CSP type semiconductor laser device according to an embodiment of the present invention, and FIG. 2 is the same (a perspective view of the semiconductor laser device with a portion cut away). Figure 3 is an enlarged cross-sectional view showing the bonding state of the laser chip, Figure 4 is a cross-sectional view of the wafer with channels formed on the main surface, and Figure 5 is a cross-sectional view of the wafer with channels formed on the main surface. Figure 6 is a cross-sectional view of the wafer with grooves formed on its main surface; Figure 7 is an enlarged cross-sectional view of the wafer with a diffusion layer formed; Figure 8 1 is a cross-sectional view of a wafer with a passivation film formed thereon. 1... Semiconductor laser element (laser chip), 2...
Substrate, 3...Multilayer growth layer, 4...Anode electrode, 5
... Cathode electrode, 6... Groove, 7... Clad layer, 8... Active layer, 9... Clad layer, IO... Cap layer, 11... Resonator (optical waveguide) , 12...
Groove, 13... Passivation film, 14... Submount, 15... Joined body, 16... Diffusion layer, 17...
... compound semiconductor thin plate (wafer), 18... mask,
19... Mask, 20... Insulating film, 21... Stem, 22... Heat sink, 23... Light receiving element, 2
4... Laser light, 25... Lead, 26... Insulator, 27... Wire, 28... Glass plate, 29...
・Window, 30...Cap, 31...Mounting hole. Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. A semiconductor laser element having a resonator in a surface layer of a flat main surface, comprising: a groove provided parallel to the main surface of the substrate on both sides of the resonator and dividing a pn junction; A semiconductor laser device characterized by having a passivation film covering the surface of the groove. 2. A semiconductor laser device in which the main surface side of a semiconductor laser element is fixed to a mounting plate via a bonded body, and the semiconductor laser element has a flat main surface and a resonator on a surface layer of the main surface. and a groove having a passivation film on the surface dividing the pn junction is provided in parallel on both sides of the resonator.