KR100277996B1 - Two wavelength light source module and its manufacturing method - Google Patents

Abstract

The present invention relates to a two-wavelength light source module for generating light beams having different wavelengths and a method of manufacturing the same. A first and second laser diodes having different wavelengths, mirror blocks having mirror surfaces on side surfaces, and submounts, respectively, are prepared on the submounts. After forming the first mask material, the predetermined area of the first mask material is patterned to expose the submount, and the exposed submount is first etched to a predetermined depth to site the first and second laser diodes to be aligned. To form. And forming a second mask material on the etched submount, patterning a predetermined region of the second mask material to expose the submount and second etching the exposed submount to a predetermined depth to align the mirror block; and Form a 45 degree mirror. Subsequently, by forming a reflective film on the mirror surface of the 45 degree mirror, aligning the first and second laser diodes on the primary etched sites and the mirror blocks on the secondary etched sites, assembly accuracy and productivity can be improved. It is easy to manufacture and excellent in reproducibility due to the simple manufacturing process.

Description

Two wavelength light source module and its manufacturing method

The present invention relates to a two-wavelength light source module for generating light beams having different wavelengths and a method of manufacturing the same.

As the technology of the optical disc has developed, optical discs for computer auxiliary memory and DVDs, which are about 6 to 7 times larger than the capacity of conventional CD series, have been developed, starting with audio-only CDs.

Optical pickups for reading such optical discs are also being developed, but currently developed optical pickups for DVDs are compatible with CDs and DVDs, but since the laser light source used for pickup is 650 nm, high reflectance at wavelength 780 nm and low reflectance at 650 nm Incompatible with (Write Once Read Many) type CD-R (Recordable) discs.

Accordingly, compatibility with writeable CDs (CD-Rs), which are rapidly increasing in the market, has emerged as an important problem in optical pickup for DVD-ROM or DVD-RAM.

As a method currently available, as shown in FIG. 1, two optical diodes (LDs) having wavelengths of 650 nm and 780 nm are used for one optical pickup, and switching is performed according to the type of disk desired for reading.

As shown in FIG. 1, the structure of the prior art is LD (1) of 650nm wavelength, LD (4) of 780nm wavelength, first collimator (2) for 650nm LD, and second collimator lens for 780nm LD ( 5) the first beam splitter (3), 45 degree reflector (7), objective lens (8), and the beam reflected from the disk, directing the beam from the 780 nm LD to the 45 degree reflector and passing the beam from the 650 nm LD. A second beam splitter 6 facing the multi-segment photodetector 12, a focusing lens 9 for focusing the beam on the multi-segment photodetector 12, an objective lens servo signal and an information signal recorded on the optical disc It consists of a multi-segment photodetector 12 for generating.

Referring to FIG. 1, the operation of the prior art will be described in detail. In the case of reading a DVD, the first collimation lens receives a beam emitted from the 650 nm LD 1 by turning off the 780 nm LD 4 and operating only the 650 nm LD 1. The parallel beams are made by (2), and the parallel beams pass through the first beam splitter 3 and the second beam splitter 6 in turn, and are then incident on the objective lens 8 by the 45 degree reflector 7.

The beam incident on the objective lens 8 is focused on the DVD 10 by the objective lens 8 and then reflected back to the optical path, and the second beam splitter 6 splits a part of the beam into a photodetector. 12) focused on.

The multi-segment photodetector 12 outputs the information signal recorded in the objective lens servo and the disk as the laser beam is incident.

When reading CDs or CD-Rs, only the light source that is operated changes from 650nm LD to 780nm LD and reads information on the same principle.

When the CD or CD-R is read in FIG. 1, the effective diameter incident on the objective lens is smaller than that on the DVD, and when the 780 nm LD is used, the effective diameter of the incident beam of the objective lens is reduced by about This is because a spot of about 1 to 1.2 mu m should be made.

Optical pickup for reading DVD and CD series discs that operate as described above requires additional installation of 780nm LD to read CD-Rs, resulting in an increase in manufacturing price and an increase in assembly difficulty and size of optical pickup. have.

An object of the present invention is to provide a two-wavelength light source module capable of generating light beams having different wavelengths by using a submount capable of passive alignment, and a method of manufacturing the same. .

1 is a view schematically showing an optical pickup apparatus according to the prior art

2A and 2B are a plan view and a perspective view schematically showing a two-wavelength light source module according to a first embodiment of the present invention

3a to 3d is a cross-sectional view showing a manufacturing process of a two-wavelength light source module according to the present invention

4A shows a grown silicon wafer pillar

4B is a plan view of a wafer cut parallel to the wafer pillar of FIG. 4A and a cross-sectional view of the wafer being etched therefrom.

FIG. 4C is a plan view of a wafer in which the wafer pillar of FIG. 4A is inclined about 9.7 degrees and a cross-sectional view of the wafer

5 is a plan view schematically showing a two-wavelength light source module according to a second embodiment of the present invention;

6 and 7 schematically show an optical pickup apparatus using a two-wavelength light source module according to the present invention.

Explanation of symbols for main parts of the drawings

20: submount 21: 650 nm LD

22: 780nm LD 23: Mirror Block

24: mirror surface 25: mirror

26: reflective film 27: the first mask material

28: second mask material 31: collimating lens

32: beam splitter 33: 45 degree reflector

34: objective lens 35: multi-part photodetector

36: focusing lens

The main features of the two-wavelength light source module according to the present invention are located between the first and second laser diodes, which emit laser beams having different wavelengths, and the first and second laser diodes, respectively, and are incident from the first and second laser diodes, respectively. A mirror block having a mirror surface for reflecting the laser beam in the same direction, first and second grooves formed below them so that the first, second laser diode and the mirror block are aligned, and reflected from the mirror block. The third groove having a mirror surface for rereflecting the laser beam in a predetermined direction is composed of a submount having a predetermined depth.

Features of the method for manufacturing a two-wavelength light source module according to the present invention comprises the steps of preparing a first, a second laser diode having a different wavelength, a mirror block having a mirror surface on the side, a submount, respectively, and a first mask material on the submount Forming a region of the first mask material to expose the submount and first etching the exposed submount to a predetermined depth to form a site where the first and second laser diodes are to be aligned. Forming a second mask material over the etched submount, patterning a predetermined area of the second mask material to expose the submount and second etching the exposed submount to a predetermined depth to align the mirror block. Forming a site and a 45 degree mirror, forming a reflective film on the mirror surface of the 45 degree mirror, and forming the first and second laser beams on the first etched site. Aligning the respective odd and has through interaction step of aligning the mirror block on the secondary site, the etched.

Referring to the embodiment with reference to the accompanying drawings, a two-wavelength light source module and a method for manufacturing the same according to the present invention having the features as described above are as follows.

First, the concept of the present invention is a two-wavelength light source module capable of passive alignment by digging a groove of a predetermined depth in a submount to form a 45 degree mirror and forming a site of a mirror block having a laser diode and a mirror surface. Is in making.

First embodiment

2A and 2B schematically show a two-wavelength light source module according to a first embodiment of the present invention. As shown in FIGS. 2A and 2B, a silicon having a mirror 25 having a 45 degree mirror surface in cross section is formed. A sub-mount, a mirror block 23 having a mirror surface 24 on the side to change the radiation angle of the incident laser beam by 90 degrees, and a 650 nm LD 21 installed so that the laser beam is radiated toward the mirror block 23. And 780nm LD22.

Here, the mirror blocks 23 and the LDs 21, 22 are arranged above the sites below them.

That is, the mirror 25 having the mirror surface of 45 degrees and the site which enables manual assembly of each component (mirror block, LD) are formed in a recessed shape by etching the submount to a certain depth by anisotropic wet etching. do.

The mirror block 23 is formed at an angle of 45 degrees with respect to the LDs 21 and 22 and the mirror 25, and a reflective film (not shown) made of any one of Au and Al is formed on the mirror surface of the mirror 25. do.

Here, the reason for forming the mirror block 23 by 45 degrees with respect to the LD (21, 22) and the mirror 25 is that the distance between the laser beam and the laser beam of two wavelengths in the mirror 25 having a 45 degree mirror surface This is because the laser beams facing each other need to be redirected by 90 degrees to gather within about 60 μm.

The method of manufacturing the two-wavelength light source module according to the present invention having such a structure is as shown in FIGS. 3A to 3D.

First, as shown in FIG. 3A, a silicon wafer is prepared using the submount 20.

Here, the silicon wafer is prepared as a wafer cut at an off axis angle of 9.7 degrees.

This wafer is a wafer cut at an angle of about 9.7 degrees with respect to the plane without cutting parallel to the grown silicon wafer pillar as shown in FIG. 4A.

The reason for using this wafer is as follows.

4B is a plan view of a wafer cut parallel to the wafer pillar of FIG. 4A and a cross-sectional view of the wafer, and FIG. 4C is a plan view of a wafer cut diagonally to the wafer pillar of FIG. 4A and a cross-sectional view of the wafer.

In the case of wafers cut in parallel as shown in FIG. 4B, when anisotropic wet etching is performed, an inclined surface of 45 degrees cannot be obtained and an inclined surface of 54.74 degrees is formed due to the selectivity of etching rates with respect to the (100) and (111) surfaces. .

However, using a wafer cut at an off axis angle of about 9.7 degrees as shown in FIG. 4C, a 45 degree mirror surface of the (111) surface having good surface roughness can be easily obtained.

In this case, only one side can obtain a 45 degree mirror surface, and neither can produce a 45 degree mirror surface, but in this invention, since only one mirror surface is needed, there is no big problem.

Subsequently, as illustrated in FIG. 3B, a first mask material 27 made of any one of silicon oxide, silicon nitride, and Au is formed and patterned on the submount 20 to expose the submount 20 of a predetermined region.

The exposed submount 20 is then etched by primary anisotropic wet etching to form LD sites where the 650 nm LD 21 and the 780 nm LD 22 are to be located.

Here, the etching solution used is a widely used KOH solution, wherein the LD site is formed in a <110> direction parallel to the primary flat of the wafer.

Subsequently, a second mask material 28 identical to the first mask material 27 is formed and patterned on the etched submount 20 as shown in FIG. 3C to expose the submount 20 in a predetermined region. The exposed submount 20 is etched by secondary anisotropic wet etching to form a mirror block site on which the mirror 25 and mirror block 23 having a 45 degree mirror surface in cross section will be located.

Here, as the etching solution, a KOH solution was used as the primary etching, wherein the mirror 25 having a 45-degree cross-sectional mirror surface is formed in a <110> direction parallel to the preliminary flat of the wafer, and the mirror block site is a wafer. It is formed in the <100> direction making 45 degrees with the preliminary flat.

At this time, the 45 degree mirror surface of the mirror 25 is formed in the (111) surface as shown in FIG. 2A.

As shown in FIG. 3D, a reflective film 26 made of any one of Au and Al is formed on the 45 degree mirror surface of the mirror 25.

The reason for forming the reflective film 26 is that the reflectivity of the mirror surface can be increased and the surface roughness can be reduced.

Here, the coating method of the reflective film 26 can be both a vapor deposition method and an electroplating.

Next, although not shown, a two-wavelength light source module is manufactured by arranging the LD and mirror blocks on each site.

Here, the mirror block serves to send a laser beam of two wavelengths facing each other to be redirected by 90 degrees to a 45 degree mirror in cross section.

The mirror block is made of any one of ceramic, glass, metal, and silicon, and a mirror is formed at a side thereof to reflect the laser beam.

Second embodiment

5 is a view schematically showing a two-wavelength light source module according to a second embodiment of the present invention. The structure is the same as that of the first embodiment, but the manufacturing method is somewhat different.

The manufacturing process of the second embodiment will be described briefly. In the second embodiment, first, a wafer cut in parallel as shown in FIG. 4B is used as a submount.

Using this wafer, anisotropic wet etching in the <100> direction forming 45 degrees with the wafer flat head as shown in FIG. 4B forms a mirror 25 having a 45 degree mirror surface.

That is, the LD site and the mirror 25 are anisotropic wet etched in the <100> direction forming 45 degrees with the wafer's front flat, and the mirror block sites between the LD sites have a <110> direction parallel to the front flat of the wafer. By anisotropic wet etching.

At this time, the 45 degree mirror surface of the mirror 25 is formed in the (110) surface.

Here, EDP solution was used to produce a 45 degree mirror plane of the (110) plane.

The EDP solution was prepared under the conditions of increasing the amount of water to increase the amount of oxidizing agent, and the ratio of ethylenediamine to water was set between 20% and 40%.

In this case, the etching rate difference between the (100) and (110) planes was about 4: 1, and the undercut ratio was measured within about 10%.

Other processes are the same as those of the first embodiment described above.

Such a fabrication process of the present invention is compatible with CMOS processes so that the photodetector can be integrated at an appropriate location on the submount prior to subsequent etching operations.

Referring to the operation of the optical pickup device using the two-wavelength light source module of the present invention manufactured as described above are as follows.

First, when reading a DVD, as shown in FIG. 6, the 780 nm LD 22 is turned off and only the 650 nm LD 21 is operated so that the laser beam emitted from the 650 nm LD 21 is reflected on the mirror block. Again reflected by the 45 degree mirror changes the direction of travel of the beam, and enters the collimation lens 31.

The laser beam incident on the collimation lens 31 becomes parallel light, passes through the beam splitter 32, and then enters the objective lens 34 by the 45 degree reflector 33, and then enters the objective lens 34. By focusing on the DVD.

Subsequently, when the laser beam focused on the DVD is reflected from the DVD and travels back through the optical splitter 32 and passes through the beam splitter 32, a part of the laser beam is changed toward the photodetector 35 to be divided into the focusing lens 36. By focusing on the multi-segment photodetector 35.

The operation principle of the multi-segment photodetector 35 thereafter is the same as before.

On the other hand, when reading a CD, as shown in FIG. 7, the 650 nm LD 21 is turned off, and only the 780 nm LD 22 is operated to be reflected from the mirror block, and then to the 45 degree mirror to reflect the beam to the optical axis. The principle of operation is the same as that of 650nm LD.

In the two-wavelength light source module and its manufacturing method according to the present invention has the following effects.

In the present invention, by implementing a two-wavelength light source module by forming a 45-degree mirror and LD site and a mirror block site by anisotropic etching technology, the assembly precision and productivity can be increased, and the manufacturing process is simple, easy to manufacture and excellent reproducibility. .

In addition, since the laser beam of two wavelengths can be emitted from one module, the configuration of the optical pickup device using the module can be simplified and the volume and the like can be minimized.

Claims (10)

First and second laser diodes emitting laser beams having different wavelengths from each other; A mirror block positioned between the first and second laser diodes, the mirror block having a mirror surface for reflecting laser beams incident from the first and second laser diodes in the same direction; A third groove having a first groove and a second groove formed below them so that the first and second laser diodes and the mirror block are aligned, and a mirror surface for reflecting the laser beam reflected from the mirror block in a predetermined direction; Two-wavelength light source module, characterized in that consisting of a submount groove is formed to a predetermined depth. The two-wavelength light source module according to claim 1, wherein in the submount, the mirror surface of the third groove is an inclined surface at an angle of 45 degrees. The two-wavelength light source module according to claim 1, wherein in the submount, a reflection film made of any one of Au and Al is formed on the mirror surface of the third groove. The two-wavelength light source module according to claim 1, wherein the submount is one of a wafer cut at an off axis angle of 9.7 degrees and a wafer cut in parallel. The method of claim 4, wherein the first groove and the third groove of the submount made of the wafer cut to the off axis angle of 9.7 degrees are formed in a <110> direction parallel to the primary flat of the wafer, The second wavelength light source module, characterized in that the second groove is formed in the <100> direction to form a 45 degrees to the front flat of the wafer. 6. The two-wavelength light source module according to claim 5, wherein the mirror surface of the third groove is formed on the (111) surface. 5. The wafer of claim 4, wherein the first groove and the third groove of the submount of the parallel cut wafer are formed in a <100> direction forming a 45 degree angle with the front flat of the wafer, and the second groove is the wafer. A two-wavelength light source module, characterized in that formed in the <110> direction parallel to the flat head of the. The two-wavelength light source module according to claim 7, wherein the mirror surface of the third groove is formed on the (110) plane. Preparing first and second laser diodes having different wavelengths, mirror blocks having mirror surfaces on side surfaces, and submounts, respectively; Forming a first mask material over the submount; Patterning a predetermined region of the first mask material to expose the submount, and first etching the exposed submount to a predetermined depth to form a site on which the first and second laser diodes are to be aligned. ; Forming a second mask material over the etched submount; Patterning a predetermined region of the second mask material to expose the submount, and second etching the exposed submount to a predetermined depth to form a site and a 45 degree mirror to which the mirror block is to be aligned; Forming a reflective film on the mirror surface of the 45 degree mirror; And, And aligning the first and second laser diodes on the primary etched sites, and aligning the mirror blocks on the secondary etched sites. 10. The method of claim 9, wherein the first and second mask materials are made of any one of silicon oxide, silicon nitride, and Au.