EP1252541A2

EP1252541A2 - Production method for an optical transmission assembly

Info

Publication number: EP1252541A2
Application number: EP01909501A
Authority: EP
Inventors: Ralf Dietrich; Mathias Kaempf; Wolfgang Gramann; Martin Weigert
Original assignee: Infineon Technologies AG
Current assignee: Infineon Technologies AG
Priority date: 2000-01-20
Filing date: 2001-01-15
Publication date: 2002-10-30
Also published as: WO2001053868A3; US20030057443A1; WO2001053868A2; DE10002329A1; US6693312B2

Abstract

The invention relates to a photo-optical transmission assembly produced in the following manner: a glass wafer (2) is fixed onto a transparent submount (1) and a V-shaped recess (20) is subsequently created between optical prism elements (2a, 2b) using targeted sawcuts. A rod-shaped element (12) with a reflective coating (9) is inserted into the V-shaped recess (20), in such a way that laser illumination (S) from a semiconductor laser (6) is deflected by 90 DEG on the rod-shaped element (12) with reflective coating and penetrates the submount (1).

Description

description

Manufacturing process for an optical transmitter assembly

The present invention relates to a production method for an optical transmitter assembly with the features of claim 1. Such transmitter assemblies are used, for example, in beam deflection recipes of fiber-optic transmitter components or combined transmitter / receiver components. An output radiation beam is generated by an edge-emitting laser diode in these transmit modules and is preferably deflected by 90 ° in a first deflection. For this purpose, the laser diode is mounted on a so-called submount, on which prism-optical elements made of glass for the deflection of the output radiation beam of the laser diode are also attached.

1 shows an overall view of a fiber-optic transmission component in longitudinal section along an optical glass fiber 23 coupled to the component. It has an assembly platform 25, which is preferably made of metal and has a circular through opening on one longitudinal side. A transmitter module 100 is mounted on one side of this circular through opening and a recess is provided on the other side of the circular through opening, into which a tubular part of a beam deflection recipe 22, which holds a ball lens 26, projects. The beam deflection recipe 22 also has a beveled surface on the inside, on which a deflection mirror 24 is provided. The transmitter assembly 10 is mounted on a silicon submount 1 and essentially consists of an edge-emitting semiconductor laser 6 and glass prismatic elements 2a, 2b and 2c, between which a highly reflective interface is at a 45 ° angle to the laser beam or to the surface of the submount is formed. Thus, one of the semiconductor lasers 6 emitted laser radiation beam at this interface is deflected by 90 ° in the direction of the submount 1 transparent to the laser radiation, passes through the circular through opening of the mounting platform 25 and is bundled by the ball lens 26. The radiation beam then strikes the deflecting mirror 24 and is directed by the latter onto the entry surface of the glass fiber 23.

So far, the transmitter assembly 100 has been manufactured by individually producing the prismatic deflection elements 2a, 2b and 2c, placing them on the submount 1, aligning them with one another and gluing or anodically bonding them. The surfaces of the prism-optical elements were created using grinding and polishing techniques. A mirror coating was applied to the prism surface that contributed to the beam deflection. Such manufacturing processes are known, for example, from DE-A-198 10 624 and EP-A-0 660 467.

This manufacturing process proves to be relatively original, since the prism-optical elements 2a and 2b must first be manufactured individually and then individually attached to the submount in a specific orientation to one another. This means that a relatively large amount of time is required to complete an individual transmitter module.

DE-A-42 11 899 describes a method for producing a microsystem, in which several wafers are connected to form a wafer array. The connection is made after the individual wafers have been structured.

The present invention has for its object to simplify the manufacturing process for an optical transmitter assembly and thus reduce the time required for manufacturing. This object is achieved by the features of patent claim 1.

The present invention thus describes a manufacturing method for an optical transmitter assembly, in which

a) a transparent submount wafer and a glass wafer are first connected to one another on their main surfaces, b) then a recess is formed in the glass wafer, which has at least one side wall which essentially forms a 45 ° angle with the surface of the submount wafer, c) a semiconductor laser is then mounted on the submount wafer in such a way that, during operation, it emits a radiation beam into the glass wafer in the direction of the at least one side wall of the recess, and d) the at least one side wall of the recess is acted on in such a way that it is for the radiation beam becomes highly reflective.

According to the invention, a submount wafer and a glass wafer are thus connected without there being any structured surfaces on the glass wafer. The glass wafer is only structured after it has been connected to the submount wafer.

The transparent submount wafer preferably consists of a material of relatively high thermal conductivity, so that it has the properties of a heat sink.

In a preferred exemplary embodiment, a V-shaped recess is formed in method step b) and in method step d) at least one of the opposite side walls of the V-shaped recess is acted on in the manner described. For this it proves to be advantageous clinging when the opposite side walls form essentially a 90 ° angle with each other.

It proves to be expedient and advantageous if, prior to method step a), recesses are formed at a suitable point in the main surface of the glass wafer to be connected to the submount wafer, for example by wet chemical etching, so that the glass wafer in the region of these recesses does not subsequently occur in method step a) is connected to the submount wafer. As a result, after process step a) or process step b), the areas of the glass wafer which are located above the recesses and are not required can preferably be removed by sawing.

The V-shaped recess can advantageously be formed in that a V-shaped trench is produced in the glass wafer by means of a V-shaped saw blade, such as a cutting abrasive blade or the like. The V-shaped recess can first be pre-sawn with a coarse-grained cut-off wheel and then sawed-in with a fine-grained cut-off wheel.

In an advantageous exemplary embodiment, which will still be explained, only two prismatic optical glass elements remain on the submount wafer after the sawing steps described have been carried out.

In method step d), a rod-shaped element with a horizontal upper support surface which is essentially rectangular-triangular in cross section can be introduced into the V-shaped recess. Before the rod-shaped element is introduced, one of its equilateral side walls can be provided with a reflective coating. The rod-shaped element can first be shaped as a rod with a rectangular cross-section, with an area of the rod on the surface of the sub-element before or after being introduced into the V-shaped recess. Mountwafer facing away is removed in such a way that a horizontal contact surface is formed. This can serve to arrange a light receiver on it so that the transmitter assembly can be used in a combined transmitter / receiver component.

A rod with a rectangular cross section can be obtained, for example, by providing a glass wafer with a reflective coating on a main surface and dividing it into a number of rods.

The submount wafer is preferably formed by a semiconductor wafer, in particular a silicon wafer, if it is sufficiently transparent for the required wavelength.

As already described, it may be necessary to expose sections of the submount wafer outside of the beam deflecting section to be shaped or the already shaped beam deflection section at any time after carrying out process step a) by removing corresponding areas of the glass wafer, preferably the areas lying above the shaped recesses the semiconductor laser and, if appropriate, a monitor diode can be mounted on these sections of the submount wafer.

The invention is explained in more detail below on the basis of a single exemplary embodiment in conjunction with the figures. Each shows in a cross-sectional representation:

1 shows an overall view of a fiber-optic transmission component;

2 shows a submount wafer and a glass wafer which are connected to one another on their main surfaces;

3 is a V-shaped recess formed in the glass wafer of FIG. 2; Fig. 4 is provided with a reflective coating

Glass wafers as a starting product for the production of reflection-coated rods;

Fig. 5 in the V-shaped recess of Figure 3 inserted reflection coated rod.

Fig. 6 positioned, reflection-coated rod of Fig. 5, which on its top to form a

Mounting surface is flattened;

FIG. 7 arrangement of FIG. 6, in which a light receiver is arranged on the mounting surface and a semiconductor laser and monitor diodes are arranged on exposed sections of the submount wafer.

2, 3 and 5 to 7 show an exemplary embodiment of the method according to the invention for producing an optical transmitter module on the basis of cross-sectional representations of the intermediate products after individual method steps.

FIG. 2 shows how a submount wafer 1 and a glass wafer 2 are first connected to one another on their main surfaces. A semiconductor laser 6 is to be mounted on the submount wafer 1 in a later method step. For this reason, the submount wafer should have the properties of a heat sink, and thus consist of a material with the highest possible thermal conductivity. Silicon is used as the preferred material for the submount wafer 1.

In the main surface of the glass wafer 2, cutouts 3 are preferably formed before the connection to the silicon wafer 1, which make it possible in the subsequent method step to have an area below the V-shaped one to be formed

Recess and certain areas of the glass wafer 2 outside the prismatic beam deflection device to be formed easily separate. These recesses 3 are preferably produced by wet chemical etching.

Then the glass wafer 2 is connected to the submount wafer 1 at regions in which no cutouts 3 have been produced. Anodic bonding is preferably used as the connection technique.

3 shows an intermediate product after removal of the areas of the glass wafer 2 that are not required. These areas are preferably removed by sawing. In Fig. 2 two dashed saw cut lines are indicated, through which the outer areas of the glass wafer 2 are separated. Above a central recess 3, a V-shaped trench 20 of a predetermined length is then produced in the glass wafer 2 by means of a V-shaped saw blade, in particular a V-shaped cutting abrasive blade. This sawing is indicated by two dash-dotted lines in FIG. 2. The V-shaped trench 20 has a shape such that its side walls are inclined at 90 ° to one another and their imaginary cutting line lies on the surface of the submount wafer 1 and each form a 45 ° angle with the surface of the submount wafer 1. The resulting side walls 5 thus also form a 45 ° angle with the direction of incidence of the laser beam of the semiconductor laser 6 to be assembled later (see FIG. 7). The mentioned central recess 3 ensures that the V-groove sawing does not have to be carried out up to the surface of the submount wafer 1.

In order to produce surfaces with low roughness, the V-shaped recess 20 can first be pre-sawn with a relatively coarse-grained cutting abrasive sheet and then sawn-in with a relatively fine-grained cutting abrasive sheet.

The sawing steps thus leave two optical prism elements 2a and 2b on the submount wafer 1, between which the aforementioned V-profile 20 was formed. This The method for producing the optical prism elements 2a and 2b represents a simplification compared to the separate manufacture of the individual optical prism elements and placement on the submount wafer 1 known in the prior art.

In Fig. 4 it is indicated how a plurality of so-called reflection rods 7 can be produced, which are intended to be inserted into the V-shaped profile. A glass wafer 16 is provided with a reflective coating 9 and the same along saw cut lines 15 into individual rods 7

Sawn width. The reflection coating 9 can be a metallic coating or a dielectric layer sequence. 5, a single rod 7, which preferably has the same length as the V-shaped trench 20, is inserted into the V-groove and glued therein, the reflective coating 9 being arranged on the side surface of the V-groove on which the laser beam of the semiconductor laser 6 still to be assembled (see FIG. 7) enters the optical prism element 2a. The rod 7 is thus arranged in the V-trench 20 in such a way that the reflection coating 9 forms a 45 ° angle to the direction of incidence of the laser beam.

Subsequently, as shown in FIG. 6, the area of the rod 7 facing away from the submount wafer 1 can be removed in such a way that a flat mounting surface 10 can be formed. The rod 7 is preferably ground down until a flat mounting surface has been achieved. Subsequently, this flat mounting surface is polished in a suitable manner so that it can serve to receive and attach a light receiver 11 (see FIG. 7).

As a result, an elongated, rod-shaped element 12 with a rectangular-triangular cross section is positioned in the V-trench. This rod-shaped element 12 preferably has the same length as the V-shaped trench. The rod-shaped element 12 can also be applied to other than the above standing described manner are made. For example, it can be sawed out of a glass wafer in this form, the glass wafer either already having a reflective coating 9 or only then being applied to one of the side walls of the rod-shaped element 12.

It is also conceivable that no rod-shaped element 12 is used in the V-shaped trench, but that the side surface of the V-shaped trench facing the semiconductor laser 6 to be mounted (see FIG. 7) is provided with a suitable reflection coating.

Finally, FIG. 7 shows how a semiconductor laser 6, preferably an edge-emitting semiconductor laser 6, is mounted on the exposed surface 8 of the submount wafer 1 such that the laser beam S emitted by it falls into the optical prism element 2a and on the Reflective coating 9 of the rod-shaped element 12 is reflected downward at a 90 ° angle and passes through the transparent submount wafer 1. A monitor diode 13 can either be arranged behind the semiconductor laser 6 and thus detects the small proportion of the laser radiation passing through the rear resonator mirror. It can also be arranged beyond the optical prism element 2b and thus detects the small proportion of the radiation passing through the reflection coating 9.

The light receiver 11, preferably a receiver diode, such as a PIN diode, can detect a received beam arriving in the optical fiber 23 (see FIG. 1), for example a small proportion passing through the reflective coating 9 and striking the light receiver 11. In a combined transmitting / receiving component, however, it can also be provided that the reflective coating 9 exhibits a wavelength-dependent reflectivity and transmissivity. points so that, for example, a transmission beam experiences a high reflectivity at a first wavelength, while a reception beam experiences a high transmissivity of the reflection coating 9 at a second wavelength.

Finally, the fully processed transmitter assembly shown in FIG. 7, as already described in connection with FIG. 1, can be connected to an assembly platform 25 to form a complete transmit component or combined transmit / receive component by the transparent submount wafer 1 is glued to a surface of the mounting platform 25. An optical beam guiding device, such as a beam deflection recipe with a fiber connection, can be mounted on the opposite surface of the mounting platform 25.

Claims

claims

1. Manufacturing method for an optical transmitter assembly, wherein b) first a transparent submount wafer (1) and a

Glass wafers (2) are connected to one another at their main surfaces, b) a recess (20) is then formed in the glass wafer (2), which has at least one side wall (5) which is essentially at a 45 ° angle with the surface of the submount wafer (1), c) then a semiconductor laser (6) is mounted on the submount wafer (1) in such a way that it operates a radiation beam in the glass wafer (2) in the direction of the at least one side wall (5) Emits recess (20), and d) the at least one side wall (5) of the recess (20) is acted on in such a way that it becomes highly reflective for the radiation beam.

2. The method according to claim 1, so that the recess (20) formed in method step b) is V-shaped and the opposite side walls (5) act on at least one as in method step d).

3. The method of claim 2, d a d u r c h g e k e n n z e i c h n e t that - the opposite side walls (5) of the V-shaped recess (20) form a 90 ° angle with each other substantially.

4. The method according to claim 1, characterized in that before step a) in the submount wafer (1) to be connected to the main surface of the glass wafer (2) recesses (3) are formed so that the glass wafer (2) in the region of the recesses (3) is not connected to the submount wafer (2) in method step a), and - after method step a) or method step b) the areas of the glass wafer (2) located above the recesses (3) are preferably removed by sawing.

5. The method according to claim 2, characterized in that in step b) the V-shaped recess (20) is formed in that by means of a V-shaped saw blade, such as a cutting disc or the like, a V-shaped trench in the glass wafer (2nd ) is produced.

6. The method according to claim 5, so that the V-shaped recess (20) is first sawn with a coarse-grained separating abrasive sheet and then is sawn-in with a fine-grained separating abrasive sheet.

7. The method according to any one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that - in method step d) in the V-shaped recess (20) a cross-section essentially rectangular-triangular rod-shaped element (12) is introduced with a horizontal upper contact surface.

8. The method according to claim 7, so that one of its equilateral side walls is provided with a reflective coating (9) before the rod-shaped element (12) is introduced.

9. The method according to claim 7 or 8, characterized in that the rod-shaped element is first shaped as a rod (7) with a rectangular cross-section and then before or after it is introduced into the V-shaped recess (20), a region of the rod (7) is removed in this way on the side facing away from the submounter (1) is that a horizontal bearing surface (10) is formed.

10. The method of claim 9, d a d u r c h g e k e n n z e i c h n e t that - a light receiver (11) is arranged on the support surface (10).

11. The method according to claim 9 or 10, characterized in that - the rod (7) is obtained in that a glass wafer (16) is provided on a main surface with a reflective coating (9) and is divided into a 7 number of rods (7) ,

12. The method according to claim 9, so that the rod (7) is ground to form the horizontal bearing surface (10) and the surface formed is then polished.

13. The method according to any one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the submount wafer (1) is formed from a semiconductor, in particular silicon.

14. The method according to any one of claims 7 to 12, that the rod-shaped element (12) or the rod (7) is glued into the V-shaped recess (20).

15. The method according to any one of the preceding claims, characterized in that At any time after performing step a), sections of the submount wafer (1) outside of the beam deflection section to be shaped or already shaped are exposed by removing corresponding areas of the glass wafer (2), and on these sections the semiconductor laser (6) and, if appropriate, a monitor diode (13) can be installed.