KR20000004926A - Process for the hybrid intergration of at least one opto electronic component,a waveguide and an intergrated electro optical device. - Google Patents

Abstract

PURPOSE: A process for the hybrid integration of at least one opto electronic component(a) and a wave guide provided on a substrate is to be easy a way of producing integrated electro optical devices. CONSTITUTION: The process one or more opto electronic components are provided on a connector piece(6)and the connector piece(6)is placed on the substrate(13) and moved up to the edge of the waveguide(14),with the shape of the connector piece(6)being wholly or largely complementary, and the connector piece (6) when it abuts against the edge of the waveguide(14) having only one degree of freedom in the plane of the substrate(13).

Description

Hybrid integration method of opto-electronic component and waveguide and integrated electro-optical device

The present invention relates to a method of hybrid integration of waveguides provided on at least one optoelectronic component and a substrate.

This method is known from EP 0 617 303 A1. This specification describes a method for removing material from planar waveguides made of a substrate, a bottom deflection layer, a core layer, and a top deflection layer. Thus, semiconductor components obtained by a process known as epitaxial lift-off are disposed in the cavities made.

This process can be used to integrate semiconductor components such as LEDs, laser diodes, and vertical cavity surface emitting laser diodes (VCSELs) into integrated structures that contain polymer or glass to which light is transmitted and, optionally, modulated. . Such integrated structures have many important applications in the field of optical communications (eg, external modulation of light emitted by laser diodes, routing within interconnect networks, optical amplifiers, signal monitoring, wavelength division multiplexing, etc.). In addition to being easier to handle and easier to use than optical structures, there are also non-integrated components such as high-speed interconnects (optical backplanes) and optical sensors in computers. Other advantages of this structure are that it may be possible to integrate a wide range of functionality into one electro-optical device and combine light with improved efficiency in and out of the waveguide.

EP 0 617 303 A1 describes the arrangement of semiconductor components and the waveguide structure in the transverse direction (i.e. perpendicular to the substrate of the waveguide, generally in the z direction), obtained by carefully selecting the height of the stack on which the semiconductor components are provided, The arrangement (ie, the direction parallel to the edge of the waveguide) is obtained by not clarifying the waveguide channel until the arrangement of the semiconductor components is complete. The longitudinal direction (ie, the direction perpendicular to the two directions) is determined by the accuracy of the pick-and-place device for the arrangement of the semiconductor components.

There is a need for an easier way to accurately align the optoelectronic component with the waveguide structure. Appropriately, in this arrangement in the past, all possible uses have to be made as a technique for various procedural steps due to stability.

The present invention seeks to achieve this object by a procedure as described earlier, wherein one or more optoelectronic components are provided on a connector portion, which is placed on the substrate and in the form of a waveguide toward the edge of the waveguide. The connector portion moves and the shape of the connector portion is wholly or mostly complementary and the connector portion has only one free angle within the substrate plane when it is adjacent to the edge of the waveguide.

When the connector portion is placed on the substrate, it has three free angles (one rotation angle and two movement angles) in the substrate surface. Due to their complementary nature, their apparent shape, they can only move in one direction, ie away from the waveguide, when they are adjacent to the edge of the waveguide. Because of this complementary nature, obvious shape, the connector portion can easily move towards the edge of the waveguide so that it is accurately positioned in the expected position. In this form, passive (so low-cost and fast) alignment is possible.

Moreover, the connector portion allows more freedom to select the order of the various processing steps required to obtain an integrated electro-optical device. For example, an optoelectronic component (or components) may be provided on the connector portion prior to coupling to the waveguide. This result makes the module ready to move over the waveguide and mount. Optionally, the optoelectronic component can be moved above the edge of the waveguide and mounted on the connector portion.

The opto-electronic component is mounted on the connector using so-called flip-chip technology (well known to those skilled in the art), which can accurately position the chip against the connector portion. To be. Examples of such flip-chip techniques are solder bump flip-chips and Au-Au thermal compression. Using this technique, the connector portion allows the optical signal emitted by the waveguide to couple into the optoelectronic component or components (if the photo-electronic component is a detector) or vice versa (where the photo-electronic component is the source). Should be provided on the reflective surface.

If one of the aforementioned techniques is used to mount the opto-electronic component onto the connector portion after the connector portion is above the edge of the waveguide, a material having good thermal conduction for the connector portion may be used. It is good to choose. In this case, the very local heating for making the connection between the opto-electronic component and the connector part can quickly dissipate over the whole connector part and, if required to do so, is transferred to the substrate (heat sink ) Function). This prevents the waveguide material from being affected by heat.

In this problem, when using a material having good thermal conductivity, any heat generated by the opto-electronic component is dissipated quickly.

The waveguide may be planar, suitably polymeric; Optionally, it may be a row of parallel optical fibers (fiber ribbons) such as grooves in the substrate.

Planar waveguides generally consist of one or more layers of polymeric material provided on a substrate. The waveguide is usually a complete waveguide when it consists of a bottom deflection layer, a core layer (when the waveguide channel is evident), and an upper deflection layer, the structure being incomplete, such as only a bottom deflection layer and a core layer. It may be.

The polymer material may be provided on the substrate in the form of a polymer solvent or the like, suitably by spincoating after solvent evaporation. Depending on its natural properties, the polymer may be formed using molding, injection molding or other known processing techniques.

Suitable substrates include silicon wafers or composite laminates, such as based on reinforced or weakened epoxy resins. This substrate is not essential for carrying out the procedure according to the invention.

The planar waveguide (on a fiber ribbon) is preferred because its edge (at least complementary to the connector portion at this point) can be easily complementary to the connector portion by removal of the waveguide material. A further advantage of the planar waveguide on the optical fiber is in the direction of expansion, and the waveguide channel in the planar waveguide does not depend on the substrate on which the waveguide is provided. On the other hand, the optical fiber is usually fixed in the V-groove and the direction of such V-groove is obtained mostly by wet-chemical etching, represented by the crystal lattice of the substrate (generally silicon).

The waveguide material (at least complementary to the connector portion) may be removed by suitable etching techniques, such as techniques well known in the manufacture of integrated circuits (ICs). As a technique conceivable in this case, as a wet-chemical etching technique, one made of an organic solvent or a strong base is used. However, photolithographic etching techniques such as sputter etching (non-reactive plasma etching), laser ablation, reactive ion etching (RIE) or reactive plasma etching are preferred. Such techniques are well known to those skilled in the art and are not described further herein.

Alternatively, the etching may be performed mechanically, for example grinding, cutting, drilling or impact through particles such as alumina, silica and especially pumice. It is expected that one skilled in the art can select an appropriate etching method for the polymer without experimenting.

It is particularly expected that the polymer material be removed by etching to have a smooth surface (wear surface). Moreover, the surface etched should be free of any foreign material or roughness.

In order to remove the desired portion of the polymer when using a non-mechanical etching technique, a mask is used to cover the portion that should not be corroded by etching. This mask is essential for having the resistance of etching action that is well known in IC technology. Such masks are made of metal or metal alloy or the like; Alternatively, it can be made by applying a photosensitive resin (photoresist) and fully epoxy and developing the resin according to a desired pattern.

When planar waveguides are used, the waveguide channels can be provided by removing portions of the flat waveguide, such as by wet-chemical etching or dry etching techniques, to fill a cavity formed of a material having a low refractive index (thus the deflection layer material in all respects). To form channels of near core layer material). Alternatively, it is possible to use photosensitive materials that can be developed after radiation; For example, it is a negative photoresist material that is resistant to certain solvents (developers) after spinning. In this case, the developer may be used to remove the unspun material. On the other hand, in the case of a positive photoresist, the portion not radiated is removed by the developer.

According to the present invention, a waveguide pattern made of a core material may be used, in which no material may be provided without being removed by etching. For example, it is a core layer material that has been chemically converted to a material with a different refractive index under the influence of heat, light or UV radiation. In the case of increasing the refractive index, the treated material can be used as the core material. This may be in the form of performing the above treatment using a mask with holes in the same mask as the desired waveguide pattern. In contrast, if a decrease in refractive index is involved, the treated material will be suitable for use as a cladding material. In this case, the problematic process may be performed using a mask in which the closed portion is the same as the desired waveguide pattern.

Planar waveguides are also used in which the core layer has a polymer that is bleachable under the influence of radiation. This is a particular type of core layer material that is sensitive to light or UV. The use of chemically rearranged reactions, radiation, and generally blue light, lowers the refractive index of materials that do not necessarily affect the remaining physical and mechanical properties. Suitably, the flat waveguide is provided with a mask covering the desired pattern of channels so that the surrounding core layer material can have low refractive index ("bleached") by radiation. Thus, if desired, the waveguide channel is formed to be closed on all periphery (bottom and upper deflection layers and surrounding bleached core layer material) of the low refractive index material. Such bleachable polymers are described in EP 358 476.

In practice, the channel can be established either before or after the connector portion is connected to the waveguide. In practice, however, it is easiest to determine the connector portion before contacting the waveguide.

Each longitudinal section of the waveguide channel (in the planar waveguide as well as the optical fiber) is suitably angled with the optical axis of the waveguide channel. This greatly reduces the back reflection of the combined or uncoupled signal. Such back reflections can have a very detrimental effect on the signal through the termination finish in the "laser cavity" of the laser diode. This results in a particularly reduced back reflection when the angle is above 8 degrees.

If a planar waveguide is used, this oblique angle can be determined photolithographically with the shape of the edge of the waveguide in contact with the connector portion. In this case, a mask is sufficient for both purposes.

One way to make the shape of the connector part very effective to suit the use of the process according to the invention is to etch a rectangular hole therein. When the connector portion is made of one crystal, a hole having three oblique angles is formed. In one embodiment, opto-electronic component (s) are provided on the connector portion and one of these edges serves as the reflective surface of the desired case mentioned above.

A further advantage of the reflective surface thus obtained is that it extends the overall height of the connector part. This means that no transverse or z-direction alignment is necessary.

By etching and cutting rectangular or rectangular holes in a wafer, multiple connector portions can be made simultaneously on a wafer. This will be described in more detail with reference to the following examples.

The invention also relates to an integrated electro-optical device which can be obtained by one of the several procedures described above. Suitably, the opto-electronic component (or components) is mounted on top of the connector portion, the connector portion capable of coupling and uncoupling an optical signal from the optoelectronic component or components to the waveguide. It is equipped with a mirror.

Due to the use of such a mirror, the present invention is not only limited to the component which detects or emits, but also can be used as a detector (and source) which performs surface-detection (emission).

If the angle between the substrate of the waveguide and the mirror is less than 40 degrees or greater than 50 degrees, the longitudinal reflection of the waveguide channel or the back reflection on the surface of the opto-electronic component may be reduced or the reflection may be avoided. .

The invention also relates to the module and the connector part itself which is equipped with at least one opto-electronic component and which has a connector part suitable for use in the invention. Suitably, the connector portion has one or more grooves below it (this example will be described in detail in the following embodiments).

It should also be noted that EP 420 029 A1 discloses a device for reflecting and focusing light emitted from a laser chip. Light is reflected in the angled face within this body in the direction of the device that is coupled to and focused on the silicon body. No mention is made of the silicon body and the aligned laser chip.

Furthermore, EP 607 524 discloses a device having a silicon body with a V-groove in which an optical fiber is placed. Light emitted by the optical fiber is coupled to the silicon body and reflected at an angled surface in this body in the direction of the receiving element. The document does not describe opto-electronic components integrated into waveguides provided on a substrate.

Regarding this problem, according to the present invention, an embodiment is provided in which the light is reflected on the portion, not coupled to the connector portion. First of all, such coupling allows for additional losses and reflections. Secondly, the connector portion material (generally silicon) is always transparent only within the limited waveguide range.

Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings. Of course, the present invention is not limited to this embodiment.

1 is a top view of a silicon wafer with several square holes etched away.

2 is a side view of a cross section of an integrated electro-optical device according to the invention;

3 is a top view showing the integration of a connector portion of a detector array with a planar waveguide;

4 is a perspective view of an embodiment according to the present invention,

5 is a perspective view of an embodiment according to the present invention.

Example

Both sides of the polished Si (crystal type silicon 100) wafer 1 are coated with a layer of SiNx (thickness 250 nm) by PECVD (Plasma Enhanced Chemical Vapor Deposition). A metal (Au) pattern is made on one side of the wafer 1 (electric path 3; Fig. 3). This metal pattern is thickened by an electrolyte deposition method after coating a second SiNx layer on the metal pattern. Next, the SiNx is removed (by RIE) along the holes 2 and lines 4 and 5. The wafer 1 is then immersed in a hot KOH-IPA solution and the exposed silicon is etched to remove the anisotropy. Once the silicon is sufficiently removed (which completely disappears from the site 2), the wafer 1 is taken out of the electrolytic cell and cleaned. At that point the electrical path 7 must be in contact with the other components and the SiNx is removed by RIE.

The central sidewall 3 (since the Si (100) crystal naturally angles 54.7 degrees with the bottom surface of the wafer 1) is coated with an Au layer to optimize reflection characteristics (Au is applied to IR light). Is a good reflector).

Next, a solder array 8 with eight detectors is mounted on the connector portion 6 using solder bump 8 flip-chip technology, which is well known to those skilled in the art, each of which is a It is electrically connected with one of the paths 7. The other end of the path 7 can be electrically connected with other electrical components via Tape Automated Bonding.

Finally, the wafer 1 on which the connector part 6 is realized is cut along the lines 4 and 5 to form small individual connector parts.

Simultaneously with the manufacture of the connector part 6 several waveguide channels 14 are realized in a known manner, in which a planar waveguide structure having two deflection layers 11 and one core layer 12 is formed on the substrate 13. Is provided. The RIE process is then used to remove the planar waveguide portion to a portion complementary to the shape of the connector portion 6 provided on the edge of the waveguide. Each end face of the waveguide channel 14 has an angle of 10 degrees with the optical axis of the channel. The waveguide channel 14 passes through the planar waveguide at a slight angle. The 10 degree angle causes the optical signal to be very slightly deflected on the exit. This can be balanced by the presence of a waveguide channel that itself operates at an angle.

Next, it is smoothly fitted with the waveguide and firmly glued to provide the module (the connector portion 6 provided with the array 9) on the substrate 13 of the waveguide.

FIG. 5 shows a particular embodiment of the device according to the invention as connector part 15 with a groove 16 (for example sawing or etching) through which the waveguide channel 17 passes. . The waveguide channel 17 has a branch 18, which leads to a cavity 19 in the waveguide structure that matches the lower portion of the connector portion 15 between the grooves 16. The waveguide structure also has a relatively large cavity 20 that fits with the rest of the bottom of the connector portion 15. The surface of the cavities 19, 20 is slightly larger than the bottom surface of the connector portion 15, allowing for easy and quick insertion of this connector portion.

The portion of the signal passing through one of the waveguide channels 17 will reach the connector portion 15 through the corresponding branch 18 and will be reflected by the opto-electronic component (not shown). In this way, the connector part according to the invention can be used to monitor the state of one or more waveguides, so that breakdown can be quickly found. The value of the optical component or optical network in which this component is a part is greatly improved. Such control mechanisms are very demanding for high quality components and networks (and all future networks).

Claims (14)

A method of hybrid integration of waveguides provided on a substrate with at least one optoelectronic component, wherein one or more optoelectronic components are provided on a connector portion, the connector portion lying on the substrate and in the form of the waveguide of the waveguide. Hybrid to the edge, wherein the shape of the connector part is complementary in whole or in most, and the connector part has at least one free angle in the plane of the substrate when it is adjacent to the edge of the waveguide Integration method. The method of claim 1, And the waveguide is a planar waveguide. The method of claim 2, And the edge of the waveguide is at least complementary to the connector portion and photolithographically defined. The method of claim 2 or 3, And wherein the waveguide has one or more waveguide channels, the end faces of each of which are angled with the optical axis of the channel. The method of claim 4, wherein Wherein said angle is greater than eight degrees. The method according to any one of claims 1 to 5, And the hole is etched on a surface of the connector adjacent to the waveguide. The method according to any one of claims 1 to 6, And said connector portion is made of a single crystal. The method according to any one of claims 1 to 7, At least one groove in the lower portion of the connector portion. An integrated electro-optical device, which can be obtained by the integration method according to any one of claims 1 to 8. The method of claim 9, A device wherein an optoelectronic component is mounted on top of the connector portion and the connector portion has a mirror capable of coupling and releasing optical signals from the opto-electronic component or components to the waveguide . The method of claim 10, Wherein the angle of the mirror with respect to the substrate provided with the waveguide is less than 40 degrees or greater than 50 degrees. A module comprising a connector portion suitable for use of the integration method according to any one of claims 1 to 8, wherein At least one optoelectronic component mounted on the module. A connector part, which is suitable for the use of the integration method according to any one of claims 1 to 8. The method of claim 13, And at least one groove in the lower portion of the connector portion.