JP3200924B2 - Multi-beam semiconductor laser device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-beam semiconductor laser device, and more particularly to an independently driven multi-beam semiconductor laser device for independently controlling each laser beam.

[0002]

2. Description of the Related Art In response to demands for high integration and high-speed processing of semiconductor lasers, multi-beam semiconductor lasers having a plurality of independently controllable laser beams in one chip have been developed. In such an independently controlled multi-beam laser, unlike a single element, since a plurality of independent input terminals are required, for example, a method of patterning and forming an independent electrode for each laser beam can be considered.
In a semiconductor laser device having a monolithic structure including a bonding pad for a laser in one chip, a manufacturing problem such as etching for forming a laser end face or a problem of heat generation due to a thermal resistance of a wiring portion occurs. Is difficult to put into practical use.

Therefore, in such an independently driven multi-beam laser, a separation electrode is provided for each laser beam on the laser chip side, and the separation electrode and the laser chip are patterned and formed on a separate substrate. The terminals of each laser beam are led out such that the electrodes face each other and are mounted by fusion of solder or the like. In this case, in order to reduce the size of the laser device itself or increase the density by increasing the number of beams, it is necessary to improve the alignment accuracy of each electrode.

In general, a laser has a light-emitting portion in a stripe structure, and alignment of the stripe in the extending direction is performed by aligning the light-emitting end face of the laser with the edge of the wiring board in consideration of the spread and thermal resistance of the laser light. It is done as follows. on the other hand,
The positioning accuracy in the direction perpendicular to the direction of the light emitting stripe depends on the accuracy of the device for mounting the same.

[0005] In bonding such a laser to a substrate, the accuracy of a chip mounter using image processing generally used is ± 5 considering mechanical accuracy and the thickness of an adhesive material (solder or the like). An error of about 10 to 10 μm occurs. On the other hand, with the increase in the number of beams, the beam interval is becoming narrower in order to reduce the size of the entire semiconductor laser device. For example, if the beam interval is 50 μm or less,
With a high-density multi-beam laser with a very narrow interval of about 0 μm, it is difficult to perform bonding using such a mechanical chip mounter.

[0006]

In view of such a problem of bonding, the present applicant has previously filed Japanese Patent Application No. Hei.
In the No. 5 application, as shown in FIG. 4, a method is provided in which the number of wiring electrodes provided on the wiring board 2 is made larger than the number of electrodes on the side of the laser 1 so that there is a margin in alignment between the laser beam and the wiring board. Suggested. However, in this case,
Than the pitch P _l of the laser 2 of the electrode, when the pitch P _s of the wiring substrate 2 electrode becomes slightly larger, and since the number of wiring lines, even if the pitch is of the same are different, which input terminal is what laser and After connecting or measuring 100% after connection,
It is necessary to determine different wiring for each chip (one beam). Such a method may be unsuitable for mass production as the number of laser beams increases.

Further, the width of the laser electrodes a, when the width of the electrodes of the substrate and b, and the pitch P _s and P _l of each electrode, each electrode by a _{P l = P s = a +} b 1: 1, but the contact width w varies within a range of 0 ≦ w ≦ [a, b] (where [a, b] represents a smaller value of a and b). And the contact resistance varies, and in the worst case, an open failure may occur. Further, in the case of such a 1: 1 correspondence, as shown in FIG. 5, since the alignment margin in the θ direction (rotational direction) is small, a short circuit is likely to occur, which may cause a decrease in yield.

The present invention suppresses the variation in the contact area between a multi-beam semiconductor laser having a large number of lasers arranged at a narrow pitch of about 10 μm as described above and a wiring board, and reduces the alignment tolerance in the rotation direction. In general, alignment is ensured, and electrodes connected to each laser beam can be selected without performing 100% measurement.

[0009]

FIG. 1 is a schematic diagram showing an example of a multi-beam semiconductor laser device according to the present invention.
As shown, in the multi-beam semiconductor laser device having independent control wiring board 2 with respect to the pitch P _l of the laser 1 electrode 1a, the pitch P of the wiring substrate 2 side of the electrode 2a
_s is defined as _Ps = (1 / n) _Pl (n is an integer of 2 or more), and the electrode 1a of the laser 1 is
a is in contact with a certain period .

[0010]

As described above, the multi-beam semiconductor laser of the present invention is used.
According to the laser apparatus, the pitch P of the electrode 1a of the laser is_lTo
And the pitch P of the substrate electrode 2a_sAnd P_s= (1 / n) P
_lThe width of each electrode is set to an appropriate value.
At least one or more wiring board side
The electrode 2a is surely in contact with the electrode 1a on the laser side.
Can reduce open defects and reduce the contact area.
Variation can be suppressed.

Further, since two or more electrodes 2a on the wiring board correspond to the electrodes 1a on the laser side, a part of the electrodes 2a on the wiring board is used as an unused electrode, so that the displacement in the rotational direction is reduced. , It is possible to adopt a configuration in which a short circuit hardly occurs.

Further, since the electrode 1a of the substrate corresponds to the electrode 2a of the laser at a constant period, that is, the substrate-side electrode 2a is in periodic contact, so that one laser beam is provided regardless of the number of laser beams. By measuring the continuity of the electrode 2a on the wiring side corresponding to at least one location, which input terminal should be selected is determined for the entire laser beam. That is, it is possible to select the wiring of each beam without performing the total measurement.

Therefore, according to the multi-beam semiconductor laser device of the present invention, when the beam interval is as narrow as about 10 .mu. Variations in the contact area between the electrodes can be significantly suppressed, open defects and short circuits can be suppressed, and the yield can be improved.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a multi-beam semiconductor laser device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a multi-beam semiconductor laser made of a compound semiconductor or the like.
Are provided and separated. 1a is a predetermined pitch P
Each of the electrodes has an independent width _l , a width a, and an interval d, and is formed, for example, as a stripe pattern extending in a direction orthogonal to the plane of FIG. Reference numeral 1b denotes an electrode which is entirely deposited on the back surface of the substrate. Reference numeral 2 denotes a wiring board made of, for example, Si having good thermal conductivity,
The electrode 2a is patterned and formed at a predetermined pitch P _s , width b, and interval c as a stripe pattern in the same manner as the electrode 1a on the laser 1 side. The pitch P _s of the substrate side electrode 2a, 1 / n of the pitch P _l of the laser electrodes 1a (n is an integer of 2 or more) is formed as a.

FIG. 2 is a plan view of each of the laser 1 and the wiring board 2. The multi-beam semiconductor laser 1 has a stripe-shaped electrode 1a formed along its light emitting portion. On the surface of the wiring substrate 2, a wiring pattern of a laminated metal such as Au / Ti is formed via an insulating layer such as SiO ₂ or SiN _X. For example, on one side, a stripe-shaped electrode 2a is formed with a selected pitch corresponding to the electrode 1a of the laser 1 as described above, and each electrode 2a is connected to a terminal pad 2d. As shown in FIG. 2, in this case, the alignment allowance in the extending direction of the striped electrodes 1a and 2a indicated by the arrow y becomes relatively large, but is orthogonal to the direction (x
Direction) or rotational direction (θ direction).

First, the alignment in the x direction will be described. In this case, the width a of the electrode 1a of the laser 1 shown in FIG. 1 is set to be (n-2) b + (n-1) c <a <(n-1) b + nc (where n is an integer of 2 or more). , The electrode 1a of each laser beam is continuously (n−
1) It can be electrically connected to the n or n electrodes 2a on the substrate 2 side.

In this example, for example, n = 3, P _l
= 12 μm, P _s = 4 μm, b = 3 μm, c = 1 μm If 5 μm <a <9 μm is selected, two or three electrodes 1 a on the laser 1 side are respectively provided on the wiring substrate 2 side. 2a. If a = 7 μm, the contact width w is 5 μm <w <6 μm. In the conventional semiconductor laser device in which P _l : P _s = 1: 1, the contact width w is 0 ≦ as described above.
Since w ≦ [a, b], when the electrode width is set as described above, the contact width of the electrode is 0 ≦ w ≦ 3 μm. Therefore, according to the semiconductor laser device of the present invention, the contact width w can be made larger than that of the conventional configuration, and the variation can be suppressed.

At this time, by making the number of laser beams different from the number of substrate electrodes corresponding to n times the number of laser beams, the number of usable laser beams fluctuates due to displacement in the x direction. Can be avoided. For example, if the total width corresponding to the number of the electrodes 1a on the laser side is W ₁ as shown in FIG. 2, the total width corresponding to the number of the wiring electrodes 2a is W _2, and the maximum error of the mount is Δx, then W ₁ −W ₂ > Δx, (where W ₁ > W ₂ ) or W ₂ −W ₁ > Δx, (where W ₁ <W ₂ ). W ₁ and W ₂ are set, that is, the number of laser beams and By making the number of substrate electrodes corresponding to this different, it is possible to avoid the occurrence of variation in the number of laser beams finally obtained due to positional displacement in the x direction.

For example, in the case of W ₁ > W ₂ , the number of laser beams is formed to be larger than the number of finally used beams, and the number of laser beams corresponds to the number of electrodes 2a on the wiring board 2 side. The number of the laser electrodes 1a connected thereto becomes the number of laser beams in the entire semiconductor laser device.

On the other hand, when W ₁ <W ₂ , only the electrode 2a on the substrate side connected to the laser beam corresponds to the number of laser beams and serves as a terminal of the laser beam. In this case, the number of beams of the laser chip is the number of laser beams of the entire semiconductor laser device.

By doing so, the number of finally obtained laser beams is selected without causing a variation due to a positional shift in the x direction, and a semiconductor laser device having a predetermined number of beams can be reliably obtained. it can.

The semiconductor laser chip can be formed without increasing the number of manufacturing steps if the number of lasers is slightly increased or decreased. Therefore, when W ₁ > W _{2 and the} number of laser chips is set to be larger than the number of laser beams to be finally obtained, an unnecessary terminal after connecting this to the wiring board 2 is selected. This saves time and effort. That is, in this case, the number of measurement terminals required for selecting terminals to be used is n, and the number of measurement terminals can be minimized.

Next, the displacement in the θ direction will be described with reference to FIGS. 3A and 3B. First, the electrode 2 on the wiring board 2 side
In the case where all of a are used, as shown in FIG. 3A, if the length of the wiring electrode 2 or the laser electrode 1a, which is a small length, that is, the substantially contacting length is L, a short circuit can be avoided. The maximum rotation angle θ _max is represented by θ _max = tan ⁻¹ (c / L).

On the other hand, n corresponding to the laser electrode 1a
When one of the electrodes 2a on the substrate side is not used, as shown in FIG. 3B, the maximum rotation angle θ _max that can avoid the short circuit is θ _max = tan ⁻¹ ((b + 2c) / L), and the positioning margin in the rotational direction is larger than when all the electrodes are used. In this case, the allowance is increased, but since the unused electrode 2b is provided, there is a disadvantage in that the contact area of the electrodes 1a and 2a as a whole decreases. Therefore, θ of the mounting device as described above
It is desirable to perform an appropriate design in consideration of the direction accuracy.

In the above embodiment, the case where n = 3 has been described. However, n may be an integer of 2 or more. However, when n becomes extremely large, the width and pitch of the electrode 2a on the substrate side become small, which may cause inconvenience such as complicated assembly process due to an increase in the number of terminals, and n = 2 to 2 It is desirable to be about 3.

Further, it goes without saying that the multi-beam semiconductor laser device of the present invention is not limited to the above-described embodiment, but can be variously modified.

[0027]

[Effect of the Invention] As described above, according to the present invention, with respect to the pitch P _l of the laser electrodes 1a, the pitch P _s of the substrate electrodes 2a, be _{P s = (1 / n)} P l Therefore, in a multi-beam semiconductor laser device having a narrow beam interval, for example, a beam interval of about 10 μm pitch of 50 μm or less, even if it is not possible to obtain a sufficiently small alignment accuracy compared to the beam interval, connection of the electrode terminals can be easily performed. And the yield of the multi-beam semiconductor laser device can be improved.

That is, since at least one or more electrodes 2a on the wiring board side surely come into contact with the electrodes 1a on the laser side, the contact area between the electrodes can be increased and its variation can be suppressed. Can be reduced.

When a plurality of electrodes 2a on the wiring board correspond to the electrodes 1a on the laser side, for example, a part of the electrodes 2a on the wiring board is used as an unused electrode, so It is possible to adopt a configuration in which a short circuit is unlikely to occur even with a shift.

Further, since the electrode 2a of the substrate comes into contact with the electrode 1a of the laser periodically, the terminal 2a is measured irrespective of the number of laser beams, so that the input terminal Sorting can be performed.

Furthermore, by making the number of laser beams different from the number of electrodes on the substrate side corresponding to the number of laser beams, it is possible to avoid variations in the number of laser beams finally obtained. By configuring the number of beam beams of the chip to be larger than the required number of beam beams, it is possible to suppress an increase in the number of defective products, and to minimize the number of input terminals required for selecting input terminals to n. A multi-beam semiconductor laser device suitable for mass production can be obtained by improving the productivity by simplifying the process.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part of an example of a multi-beam semiconductor laser device of the present invention.

FIG. 2 is a schematic plan view of a main part of an example of the multi-beam semiconductor laser device of the present invention.

FIG. 3 is an explanatory diagram of a positioning margin of the multi-beam semiconductor laser device of the present invention.

FIG. 4 is a schematic diagram illustrating an example of a conventional multi-beam semiconductor laser device.

FIG. 5 is a schematic plan view of a main part of an example of a multi-beam semiconductor laser device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multi-beam semiconductor laser 1a electrode 2 Wiring board 2a electrode

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01S 5/00-5/50

Claims (1)

(57) [Claims] 1. A multi-beam semiconductor laser device having an independently controlled wiring board, wherein a pitch P _s of electrodes on the wiring board is P _s = (1 / n) P _l (pitch P _l of electrodes of the laser). n is an integer of 2 or more), relative to the electrodes of the laser, photoelectric of the wiring board side
A multi-beam semiconductor laser device wherein the poles are brought into contact with a constant period .