JP2001102670A - Board for mounting semiconductor laser element and semiconductor laser module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly control the temperature of an LD element with high accuracy. SOLUTION: A mounting part 8 for mounting an LD element 4 on an insulating board 7, an exothermic resistor 9 placed around the mounting part 8 are provided to an LD board 6, and it is used for an LD module. The LD element 4 is kept at a high temperature equal to that at operation, during stopping of the operation of the LD element 4, and temperature is controlled with high accuracy at starting operation of the LD element 4, etc.

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 mounting substrate having a semiconductor laser device mounted thereon and having a temperature control function, and a semiconductor laser module for optical communication using the same.

[0002]

2. Description of the Related Art Conventionally, a semiconductor laser (Laser) for optical communication has been used.
It is known that an LD element used in a module changes its oscillation wavelength, optical output, and the like depending on the temperature of the LD element. Therefore, in order to operate the LD element stably, it is necessary to control the temperature of the LD element to a predetermined temperature. Conventionally, LD
The temperature of the element is controlled by a temperature measuring element for measuring the temperature of the LD element and an LD based on the temperature information measured by the temperature measuring element.
This is performed by a Peltier element for cooling or heating the element. The temperature measuring element and the Peltier element are housed together with the LD element in a package that can be hermetically sealed to form an LD module.

Here, a conventional LD module is shown in a sectional view in FIG. A conventional LD module includes a base 21 and a lid 22.
Peltier device 23, L
A D element 24 and a temperature measuring element 25 are housed in an airtight manner. The LD element 24 and the temperature measuring element 25 are arranged on an LD element mounting substrate (subcarrier) 26 for mounting these elements.

[0004] The base 21 constituting the package 20 is made of ceramics such as aluminum oxide (Al ₂ O ₃ ) sintered body, copper (Cu) -tungsten (W) alloy, iron (Fe) -nickel (Ni) -cobalt. It is made of a metal such as a (Co) alloy, and is mainly composed of a flat bottom plate portion 21a and a frame-shaped side wall portion 21b, and has a box shape with an open upper surface. A Peltier element 23 is mounted and fixed on the upper surface of the bottom plate 21a of the base 21, and an LD element is mounted on the upper surface of the Peltier element 23.
24 and a temperature measuring element 25 are mounted in a state of being arranged on an LD element mounting substrate 26.

A pipe 27 as an optical fiber fixing member made of a metal such as an iron-nickel alloy or an iron-nickel-cobalt alloy is attached to a side wall 21b of the base 21. The optical fiber 28 is inserted through
It is fixed in a state of being optically coupled to the D element 24. The optical fiber 28 has a light input / output end at an end thereof facing the LD element 24, so that laser light from the LD element 24 can be transmitted to the outside via the optical fiber 28.

Furthermore, the bottom plate 21a or the side wall of the base 21
A lead terminal 29 is fixed to 21b, and the lead terminal 29 is electrically connected to the Peltier element 23, the LD element 24, and the temperature measuring element 25.

The lid 22 is a flat plate made of a metal such as an iron-nickel-cobalt alloy or an iron-nickel alloy, and is joined to the upper surface of the side wall 21b of the base 21 by, for example, a seam welding method. Thus, a package including the base 21 and the lid 22 is formed, and the Peltier element 23, the LD element 24, and the temperature measuring element 25 are housed therein and hermetically sealed.

An LD element mounting board (hereinafter abbreviated as LD board) 26 used in this conventional LD module will be described in more detail with reference to FIG. FIG. 4 shows FIG.
FIG. 2 is a perspective view showing an LD substrate 26 and an LD element 24 and a temperature measuring element 25 arranged thereon. The LD substrate 26 has a mounting portion 31 made of a metal thin film for mounting the LD element 24 on one end of the upper surface of a substrate 30 made of an electrically insulating material such as an aluminum oxide sintered body. The metal thin film forming the mounting portion 31 is, for example, a titanium (Ti) film, platinum (P)
t) a three-layer metal thin film composed of a film and a gold (Au) film. On this mounting part 31, the LD element 24 is, for example, gold (A
It is fixed via a brazing material made of u) -tin (Sn) alloy. The LD substrate 26 also has a three-layer metal thin film (not shown) composed of, for example, a titanium film, a platinum film, and a gold film deposited on substantially the entire back surface thereof. LD board 26 by brazing
Are bonded and fixed on the Peltier element 23.

The temperature measuring element 25 is composed of, for example, a thermistor, and is mounted on the upper surface of the substrate 30 on the side opposite to the optical fiber 28, adjacent to the LD element 24. The temperature measuring element 25 changes its electric resistance value depending on the temperature, transmits the change in the electric resistance value to an external control circuit via a lead terminal 29, and drives the Peltier element 23 according to an instruction from the control circuit. Thus, the LD element 24 is controlled to a predetermined temperature.

[0010]

In the above-described conventional LD module, the LD element 24 generates heat during operation and becomes high in temperature, and when the operation is stopped, the temperature drops. Then, L
The LD element 24 must be cooled when the D element 24 is operating, and heated when the operation is stopped. However, the Peltier element 23 has a certain heat capacity and
Since the LD substrate 26 is interposed between the LD element 24 and the element 24, the cooling state and the heating state of the Peltier element 23 do not switch immediately, and the LD element 24 is kept in a constant temperature state, for example, when the operation of the LD element 24 starts. It takes a long time to achieve the above, and it is difficult to quickly and accurately operate and control the temperature of the LD element 24.

The present invention has been completed in view of the above-mentioned conventional problems, and an object of the present invention is to provide an LD substrate and an L substrate capable of performing quick and highly accurate operation and temperature control.
D module.

[0012]

A substrate for mounting a semiconductor laser device according to the present invention comprises a mounting portion for mounting a semiconductor laser device on an insulating substrate and a heating resistor formed around the mounting portion. It is characterized by having.

Further, an LD module according to the present invention comprises a semiconductor laser element mounted on the above-mentioned semiconductor laser element mounting board and accommodated in a hermetically sealed package via a Peltier element. It is characterized by the following.

According to the LD substrate and the LD module of the present invention, since the heating resistor is formed around the mounting portion on which the LD element is mounted, the heating is performed by the heating resistor to stop the operation when the operation is stopped. Can always be kept at the same high temperature as during operation.
Quick and accurate operation start and temperature control can be performed at the start of operation of the D element.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment of an LD substrate of the present invention and an LD module using the same. The LD module of the present invention basically includes a package comprising a base 1 and a lid 2. A Peltier element 3, an LD element 4, a temperature measuring element 5, and an LD substrate 6 are hermetically accommodated therein.

The substrate 1 constituting the package is made of a sintered body of aluminum oxide (Al ₂ O ₃ ), a sintered body of aluminum nitride (AlN), mullite (3Al ₂ O ₃ , 2Si).
O ₂ ) -based sintered body, silicon carbide (SiC) -based sintered body, silicon nitride (Si ₃ N ₄ ) -based sintered body, glass ceramics and other ceramic materials, or a tungsten porous body impregnated with copper or iron The main part of the base 1 is composed of a substantially flat bottom plate 1a and a frame-shaped side wall 1b. The bottom plate 1a and the side wall 1b may be formed of the same material or different materials. However, when the bottom plate portion 1a and the side wall portion 1b are formed of different materials, it is preferable to select a combination that minimizes the difference between the thermal expansion coefficients of the two.

A Peltier element 3 is mounted and fixed on the upper surface of the bottom plate 1a of the base 1. The Peltier element 3 functions as a heat pump for cooling the LD element 4 to a predetermined temperature, and controls the LD element 4 to a predetermined temperature based on temperature information of the LD element 4 measured by the temperature measuring element 5. Cooling. An LD substrate 6 is mounted and fixed on the upper surface of the Peltier element 3, and the LD element 4 and the temperature measuring element 5 are arranged on the LD substrate 6. The temperature measuring element 5 is composed of a thermistor or the like.

As shown in a perspective view in FIG. 2, the LD substrate 6 is made of a sintered body of aluminum oxide, a sintered body of aluminum nitride, a sintered body of mullite, a sintered body of silicon carbide, a sintered body of silicon nitride. A rectangular flat plate-like insulating substrate 7 made of an electrically insulating material such as a body or glass ceramic is
A mounting portion 8 for mounting the D element 4;
A heating resistor 9 for heating the LD element 4 is attached to the upper surface around the mounting section 8. Further, a bonding metal layer (not shown) for bonding the substrate 6 to the Peltier element 3 is attached to the lower surface of the insulating substrate 7.

When the insulating substrate 7 is made of, for example, an aluminum oxide sintered body, a slurry-like product obtained by adding an appropriate organic binder and a solvent to a ceramic powder of aluminum oxide, silicon oxide, magnesium oxide, calcium oxide or the like is mixed. The ceramic green sheet is prepared by forming the paste of the above into a sheet shape by a known doctor blade method, and the ceramic green sheet is subjected to an appropriate punching process or a cutting process. It is manufactured by firing.

When the insulating substrate 7 is formed of an aluminum nitride sintered body, a silicon carbide sintered body, or a silicon nitride sintered body, these materials have a thermal conductivity of 40 W / m · K or more. As a result, the heat transfer between the LD element 4 mounted on the substrate 6 and the Peltier element 3 can be favorably performed.
The temperature control of the D element 4 can be quickly performed.

The mounting section 8 provided on the upper surface of the insulating substrate 7
Functions as a base metal for joining the LD element 4 to the insulating substrate 7, and the LD element 4 is attached to the upper surface thereof through a low melting point brazing material such as a gold-tin alloy.

The mounting portion 8 is formed of, for example, a metal thin film having a three-layer structure in which a titanium film, a platinum film, and a gold film are stacked in this order from the substrate 7 side. The titanium film is a metal adherent to the insulating substrate 7 and preferably has a thickness of 100 to 2000.
Angstroms (Å). The thickness of the titanium film
If it is less than 100 Å, it tends to be difficult to firmly adhere to the insulating substrate 7. If it exceeds 2,000 Å, peeling is likely to occur due to internal stress generated during film formation. The platinum film is a barrier layer for preventing titanium in the titanium film from diffusing into the gold film, and preferably has a thickness of about 500 to 10,000 angstroms. If the thickness of the platinum film is less than 500 angstroms, it tends to be difficult to sufficiently prevent the titanium in the titanium film from diffusing into the gold film.If the thickness exceeds 10,000 angstroms, the internal stress generated during film formation may cause a problem. Peeling is likely to occur. Further, the gold film is for improving the wettability with the brazing material when attaching the LD element 4 to the mounting portion 8, and the thickness thereof is preferably 1,000 to 5,000.
0 Angstrom. If the thickness of the gold film is less than 1000 angstroms, sufficient wettability with respect to the brazing material tends not to be obtained, and if it exceeds 50,000 angstroms, peeling is likely to occur due to internal stress generated during film formation.

The titanium film, platinum film, and gold film serving as the mounting portion 8 can be formed by using a known thin film forming technique such as a sputtering method, an ion plating method, or a vapor deposition method. Is formed on the upper surface of the insulating substrate 7 and is etched into a predetermined pattern using a known photolithography technique.

The heating resistor 9 arranged around the mounting portion 8 of the insulating substrate 7 is a heating resistor for heating the LD element 4, and is, for example, a two-layer structure in which a titanium film and a platinum film are laminated. It is formed from a metal thin film with a structure. The titanium film is
It is a metal closely adhered to the insulating substrate 7 and preferably has a thickness of about 100 to 2000 Å. If the thickness of the titanium film is less than 100 angstroms, it tends to be difficult to firmly adhere to the insulating substrate 7, and if it exceeds 2000 angstroms, peeling is likely to occur due to internal stress generated during film formation. Further, the platinum film functions as a main resistor, and its thickness is preferably 500 to 10,000.
Angstroms. If the thickness of the platinum film is less than 500 angstroms, defects such as pinholes are likely to occur in the platinum film, and it tends to be difficult to obtain a uniform heating resistor 9. If the thickness exceeds 10,000 angstroms,
Separation is likely to occur due to internal stress generated during film formation. As described above, since the heating resistor 9 is arranged around the mounting portion 8 on the LD substrate 6, when the operation of the LD element 4 is stopped, the heating resistor 9 generates heat and the LD element 4 is operated. It can be kept at a similar high temperature, so that LD
When the operation of the element 4 is started, the operation can be started quickly and accurately and the temperature can be controlled, and the semiconductor laser element 4 can always be operated stably and reliably.

The heating value of the heating resistor 9 is 0.1 to 10
About 00 mW is preferable. If it is less than 0.1 mW, it becomes difficult to sufficiently heat the LD element 4, and if it exceeds 1000 mW, there is a risk that the LD element 4 becomes too hot. Generally, the temperature at which the LD element 4 is driven is about 20 to 80.
° C, and the oscillation wavelength can be controlled by changing the temperature within the above range.

If the heating resistor 9 is formed of a two-layered metal thin film in which a titanium film and a platinum film are laminated, for example, the upper surface of the insulating substrate 7 is formed when the mounting section 8 is formed. A part of the titanium film and the platinum film may be used as the heating resistor 9. The titanium film, the platinum film, and the gold film may be sequentially deposited on the upper surface of the insulating substrate 7, and these may be etched to mount the mounting portion. 8 may be formed by etching into a predetermined pattern excluding the uppermost gold layer at the same time.

Then, in the LD substrate 6 of the present invention,
A heating resistor 9 is provided so as to surround the mounting portion 8.

The heating resistor 9 is formed so as to go around the mounting portion 8 substantially at a substantially constant interval of preferably 0.01 to 1 mm with the mounting portion 8, thereby forming an LD element. 4 can be heated almost uniformly over a short distance, and temperature control can be performed quickly and accurately. As described above, since the heating resistor 9 is arranged so as to make a round around the mounting portion 8 with a substantially constant interval of 0.01 to 1 mm between the heating resistor 9 and the mounting portion 8, it occupies a large area on the insulating substrate 7. Never do. As a result, the size of the substrate 6 does not increase.
When the distance between the heating resistor 9 and the mounting portion 8 is less than 0.01 mm, there is a risk that an electrical short circuit may occur between the heating resistor 9 and the mounting portion 8. Since the distance from the LD element 4 mounted on the mounting section 8 to the heating resistor 9 is too large, it tends to be difficult to quickly heat the LD element 4.

The width of the heating resistor 9 is 0.01 to 1 mm.
The degree is preferred. If the width of the heating resistor 9 is less than 0.01 mm, the risk of disconnection of the heating resistor 9 increases. On the other hand, if it exceeds 1 mm, the electric resistance value of the heating resistor 9 becomes too small, and the heat generation efficiency decreases.

The length of the heating resistor 9 is 0.5 to 50 m.
m is preferable. If the length of the heating resistor 9 is less than 0.5 mm, it tends to be difficult to obtain a sufficient electric resistance value as the heating resistor, and if it exceeds 10 mm, such a long heating resistor 9 is mounted. Since the substrate 6 is provided around the portion 8, the size of the substrate 6 increases.

Further, terminal electrodes 9a electrically connected to an external control circuit and the like are formed at both ends of the heating resistor 9. The terminal electrode 9a is formed by depositing, for example, a gold thin film on both ends of the heating resistor 9. Such a terminal electrode 9a is formed by sequentially depositing a thin film of titanium, platinum, and gold on the upper surface of the insulating substrate 7, etching these, and mounting the mounting portion 8a.
When the heating resistor 9 is formed, it is formed by leaving a gold film covering both end portions of the heating resistor 9.

The bonding metal layer adhered to the lower surface (back surface) of the insulating substrate 7 may be formed from a metal thin film having the same configuration as the metal thin film forming the mounting portion 8.

As shown in FIG. 1, a pipe 10 made of a metal such as an iron-nickel alloy or an iron-nickel-cobalt alloy is formed on the side wall 1b of the base 1 so as to penetrate the side wall 1b.
Is fixedly attached. The pipe 10 is for fixing the optical fiber 11 to a package, and the optical fiber 11 is inserted and fixed therein. The optical fiber 11 is disposed so that the tip thereof faces the LD element 4, whereby laser light generated from the LD element 4 is
11 can be transmitted to the outside.

Further, a lead terminal 12 made of a metal such as an iron-nickel alloy or an iron-nickel-cobalt alloy is provided on the bottom plate 1a or the side wall 1b of the base 1 so as to protrude outside the package. This lead terminal 12
Is provided so as to penetrate the bottom plate portion 1a or the side wall portion 1b of the base 1, or is connected to a wiring conductor extending from the inside of the base 1 to the outside, thereby electrically connecting the inside and the outside of the package. Enable connection. The lead terminals 12 are electrically connected to the Peltier element 3, the LD element 4, the temperature measuring element 5, and the heating resistor 9 inside the package.

On the other hand, the lid 2 is made of iron-nickel alloy or iron-nickel.
It is a substantially flat plate made of a metal such as a nickel-cobalt alloy, and is joined to the upper surface of the side wall 1b of the base 1 by, for example, seam welding. Then, the Peltier device 3 and the LD are placed inside a box-shaped package including the base 1 and the lid 2.
The element 4 and the temperature measuring element 5 are hermetically sealed. When the lid 2 is joined to the side wall 1b by seam welding, and when the side wall 1b is made of a porous tungsten material impregnated with a ceramic material or copper, the side wall 1b is formed.
It is necessary to previously attach a metal frame made of an iron-nickel alloy or an iron-nickel-cobalt alloy as an underlying metal member for seam welding.

Thus, according to the LD substrate and the LD module of the present invention, when the operation of the LD element 4 is stopped, the LD element 4 is heated to the same high temperature as that during the operation, so that quick and accurate temperature control is possible. Become.

The LD substrate and the LD module of the present invention are not limited to the above embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in one example of the above-described embodiment, the LD substrate 6
The mounting portion 8 and the heating resistor 9 used titanium as the adhesion metal and platinum as the barrier layer and the main resistor, but chromium (Cr) and tantalum (T
a), niobium (Nb), nichrome (Ni—Cr), tantalum nitride (Ta ₂ N), etc., and nickel (Ni), palladium (Pd), Rhodium (Rh), ruthenium (R
u), a titanium (Ti) -tungsten (W) alloy or the like may be used.

Further, an LD is provided on the upper surface of the mounting portion 8 of the LD substrate 6.
A brazing material made of, for example, a gold-tin alloy for attaching the element 4 may be applied to a predetermined thickness by employing a sputtering method or the like. In this case, the LD element 4
This eliminates the need for arranging the brazing material when mounting the device.

[0039]

As described above, the LD substrate and the LD module of the present invention are operated by being heated by the heating resistor since the heating resistor is provided around the mounting portion of the substrate on which the LD element is mounted. The LD element at the time of stop can be kept at the same high temperature as that at the time of operation, whereby the operation of the LD element can be started quickly at the time of the start of operation of the LD element, etc., and high-precision temperature control can be immediately performed. Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of an LD module according to the present invention.

FIG. 2 shows the L of the present invention used in the LD module of FIG. 1;
It is a perspective view of D board.

FIG. 3 is a cross-sectional view of a conventional LD module.

FIG. 4 is a perspective view of an LD substrate used in the LD module of FIG. 4;

[Explanation of symbols]

 1: Base 2: Lid 3: Peltier element 4: LD element 5: Temperature measuring element 6: LD substrate 7: Insulating substrate 8: Mounting part 9: Heating resistor

Claims (2)

[Claims] 1. A semiconductor laser device mounting substrate, comprising: a mounting portion for mounting a semiconductor laser device on an insulating substrate; and a heating resistor formed around the mounting portion. . 2. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is mounted on the substrate for mounting the semiconductor laser device, and the semiconductor laser device is accommodated in a hermetically sealed package via a Peltier device. Semiconductor laser module.