KR20000065884A - Apparatus and method of fabricating optical transceiver module - Google Patents

Abstract

PURPOSE: An optical reception module and a method for manufacturing the same are provided to arrange simply an optical element and a PLC(Planar Lightwave Circuit) on one substrate. CONSTITUTION: An optical reception module and a method for manufacturing the same comprise an alignment mark, a PLC(23), a solder(27), an optical element(29), and an optical fiber(31). The alignment mark is formed on a predetermined position of an upper face of a silicon substrate. The PLC is formed on a center portion of the upper portion of the silicon substrate by using the alignment mark. The solder is installed within a groove of the silicon substrate located at one side of the PLC. The optical element is located at an upper portion of the solder and one side face of the PLC. The optical fiber is installed at a center portion of other side face of the PLC and a center point of a core of the PLC.

Description

Optical transmitting and receiving module and its manufacturing method {Apparatus and method of fabricating optical transceiver module}

The present invention relates to an optical transmission module and a manufacturing method thereof, and more particularly, to an optical transmission module and a method of manufacturing the optical device, a PLC (Planar Lightwave Circuit) and an optical fiber, etc. on a substrate at the same time in a simple process. It is about.

In general, in order to align an optical element with an optical waveguide, precise alignment between optical axes is required. In order to align an optical element such as a laser diode (LD) in an optical waveguide, a precision of a tolerance within 1 μm is required. Done.

As described above, in order to align the optical elements in the optical waveguide, an optical axis alignment method for precisely aligning the optical axis is used. The optical axis alignment methods include an active alignment method and a passive alignment method. Separated by.

The active alignment method is a method of obtaining an optimal alignment by adjusting the position while observing the light intensity while the optical signal is turned on. This method has excellent alignment ability because the alignment is performed while the optical device is operated, and the process is complicated. There is a disadvantage in that the cost of sorting is high.

On the other hand, the manual alignment method performs the optical axis alignment without operating the optical device, so that the optimal optical axis alignment is difficult, but the process is relatively simple, so the cost is low.

On the other hand, the manual sorting method can be further divided into three methods. The first method is a mechanical alignment method, in which grooves are precisely positioned to accurately position the optical elements on the substrate on which the optical elements are to be mounted, the optical elements are processed to the correct dimensions, and the optical elements are mounted on the substrate. There is a difficult problem of processing optical devices and substrates with accuracy, for example, within 1 μm.

The second method is flip-chip bonding, which uses the surface tension of solder bumps. This method uses a photolithography process on solder bumps on a substrate and solder pads on an optical device chip. It is a method of forming in the correct position by using photolithography. In other words, after roughly aligning the solder pads on the solder bumps and heating, the solder bumps reflow to change the shape to the most stable shape, thereby accurately positioning the optical device. In the method using the solder bumps, there are problems in that the solder pad and the solder bump forming conditions are difficult and the difficulty of suppressing the oxidation of the solder is required.

The third method is a technique to which the present invention pertains, which is a passive mark alignment method in which alignment patterns are formed on a substrate and an optical device, thereby aligning the optical devices. The method of aligning and connecting the optical waveguide and the optical fiber can also be classified into two methods. The two methods are an active alignment method and a passive alignment method.

The active alignment method is an alignment method in which a light source is incident on a PLC having an optical wave block and an optical waveguide on which several optical fibers are placed and connected to meet an optimum condition of the optical output. In contrast, a passive alignment method uses a silicon terrace. It is a method to align PLC and optical fiber by V-groove on the board of the board.

Accordingly, the present invention has been made in view of the above-described conventional problems, and an object of the present invention is to reduce the process steps by reducing the process cost compared to the conventional technology according to a predetermined proper process procedure while reducing the accuracy of the process. The present invention provides a method for manufacturing the optical transmission module.

1 to 9 are a plan view and a cross-sectional view showing a manufacturing process step of the optical transmission module according to the present invention.

<Description of the code | symbol about the principal part of drawing>

1: silicon substrate 3: mask pattern for forming V-groove and U-groove

5: V-groove for alignment mark 7: V-groove for solder

9: U-groove for PLC 11: Tapered U-groove for PLC and fiber optic connection

13: U-groove for optical fiber 15: Under-clad layer

17 core layer 19 over-clad layer

21: mask pattern for ICP 23: PLC

25 Ti / Au metal film 27 AuSn solder

29: optical element 31: optical fiber

Optical transmission module of the present invention for achieving the above object,

Alignment marks each formed at a predetermined position on an upper surface of the silicon substrate to facilitate alignment;

PLC installed in the center of the upper portion of the silicon substrate using the alignment mark,

Solder provided in the groove of the silicon substrate located on one side of the PLC,

An optical element mounted on an upper side of the solder and on one side of the PLC;

On the other side of the PLC and, including the optical fiber is installed so that the center and the center of the core of the PLC is aligned, characterized in that aligned on one substrate.

In addition, the optical transmission module manufacturing method for achieving the above object

Forming a mask pattern on the silicon substrate to form an alignment mark V-groove, a PLC U-groove, an optical fiber U-groove, a tapered U-groove for easy connection of the optical fiber with the PLC, and ,

Etching the lower exposed silicon substrate using the mask pattern to form an alignment mark;

Depositing a predetermined thickness of an under-clad layer, a core layer, and an over-clad layer in order on the entire structure,

Depositing a predetermined thickness of a mask pattern forming material for inductively coupled plasma (ICP) on the entire structure, and then patterning the pattern using a pre-formed V-groove alignment mark at the bottom to form an ICP mask pattern;

Etching the lower over-clad layer, the core layer, and the under-clad layer in order using the ICP mask pattern to form a PLC;

Removing the upper mask pattern,

Forming a solder of a predetermined material in an elongated V-groove formed on one side of the PLC;

After completing the manual mark alignment by the alignment mark on one side, reflowing the solder portion to the external heat to install the optical device to be bonded to the electrode pad of the lower surface of the optical device;

It characterized in that the configuration comprising the step of seating the optical fiber on the other side of the PLC.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

Hereinafter, an embodiment of an optical transmission module and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

1 to 9 is a view showing a manufacturing process step of the optical transmission module according to the present invention,

1 is a view showing a silicon substrate 1 used in the present invention,

FIG. 1A shows a (100) plane of silicon in a plan view of the silicon substrate 1,

FIG. 1B is a cross-sectional view taken along the line A-A of FIG. 1A and shows the (110) plane of silicon.

Next, FIG. 2 is a view illustrating a mask pattern 3 formed on the silicon substrate 1 of FIG. 1 to form V-grooves and U-grooves.

FIG. 2A is a plan view and FIG. 2B is a sectional view taken along the line A-A of FIG. 2A.

At this time, in order to form the mask pattern 3, a silicon nitride film (Si ₃ N ₄ ) 3 having a predetermined thickness, for example, 1,000 to 2,000 Å thick, is deposited on the silicon substrate 1, followed by a photolithography process and ion. Patterning is performed by using reactive ion etching (hereinafter, referred to as 'RIE').

Referring to FIG. 3, the entire silicon substrate 1 having the silicon nitride film pattern 3 formed thereon is immersed in a KOH aqueous solution for about 2 to 3 hours at a temperature of 60 to 80 ° C. and used as an alignment mark 5. ), V-groove for soldering (7), U-groove (9) for accommodating PLC, U-groove (13) for accommodating optical fiber, and tapered U for facilitating connection between PLC and optical fiber -To form the groove (11).

In this case, the three U-grooves 9, 11, and 13 have the same depth, and the active layer (not shown) of the LD (29, FIG. 9), the core 17 of the PLC, and the optical fiber core (not shown). ), It is necessary to be around 62.5 μm, which is the radius of the optical fiber cladding, from the surface of the silicon substrate 1 to center the center.

In addition, the role of the tapered U-groove 11 between the U-groove 9 for the PLC and the U-groove 13 for the optical fiber is that the depth of the under-clad 15 of the PLC and the optical fiber ( It is to maintain the same depth of the U-groove 13 for the optical fiber 31 is placed, and also to keep the center of the PLC core (17) and the optical fiber 31 core to be consistently the same. If the U-groove 13 for the optical fiber is directly connected to the U-groove 9 for the PLC without the tapered U-groove 11, the etching by the KOH aqueous solution is not performed properly at the boundary portion.

4 is a cross-sectional view illustrating a process of forming an optical waveguide by FHD (Flame Hydrolysis Deposition).

Referring to FIG. 4A, after depositing the under-cladding layer 15 to a predetermined thickness, for example, a thickness of 60 to 70 μm, the polishing is performed to maintain a constant thickness.

Referring to FIG. 4 (b), after the core layer 17 is deposited to a predetermined thickness, for example, 6 to 8 μm, on the entire structure, a photolithography process is performed after depositing Cr to a predetermined thickness by a sputtering method. Then, the core 17 of the PLC is patterned by the ICP using the V-groove alignment mark 5 already formed.

Referring to (c) of FIG. 4, an over clad 19 is again deposited on the entire structure at a predetermined thickness, for example, 20 to 30 μm.

As a result, the under-clad layer 15, the core layer 17, and the over-clad layer 19 are sequentially deposited to form an optical waveguide, as shown in FIG.

In the above example, the thicknesses of the under-clad layer 15, the core layer 17, and the over-clad layer 19 deposited in this order may be 62 μm, 6 μm, and 20 μm, respectively. This is when the height of the LD 29 active layer is 5 占 퐉 from the surface of the silicon substrate 1.

Next, referring to FIG. 6, an ICP mask pattern forming material is deposited on the entire structure, and then patterned using a pre-formed V-groove alignment mark 5 at the bottom to form an ICP mask pattern 21.

In this case, Cr is used as a material for forming the ICP mask pattern 21, and a sputtering method is used during Cr deposition, and an area where the ICP mask pattern 21 is formed is only in a region where the PLC 23 is to be formed. To form (see FIG. 9).

Next, referring to FIG. 7, the over-clad layer 19, the core layer 17, and the under-clad layer 15 are sequentially etched using the ICP mask pattern 21 to form a PLC 23. After that, the mask pattern 21 is removed.

As shown in the cross-sectional view in FIG. 7B, all SiO ₂ films outside the PLC 23 region are removed and the height from the surface of the silicon substrate 1 to the upper side of the over-cladding layer 19 is 20 to 35 μm. To be.

Next, referring to FIG. 8, the Ti / Au base metal thin film 25 and the AuSn solder 27 are sequentially formed in the solder V-groove 7 formed on one side of the PLC 23. At this time, an ultra-thick photoresist film (not shown) is applied when the solder 27 is formed, and in consideration of the depth of the solder V-groove 7, the coating film is applied to a thickness higher than 28 μm, and the coated photoresist film is flattened. After optimizing the thickness, pattern work is performed by photolithography process. In this case, the pre-formed V-groove alignment mark 5 is used.

Next, referring to FIG. 9, after the manual mark alignment is completed by the V-groove alignment mark 5 on the left side, the LD 29 reflows the solder 7 portion to an external column and is located on the bottom surface of the LD 29. The electrode (not shown) and the V-groove solder 7 are bonded together, and the optical fiber 31 is seated in the U-groove 13 for the optical fiber on the right side, and then the epoxy is filled into the tapered U-groove 11 to cure. This completes the optical transmission / reception module of the LD-PLC-optical fiber.

As described above, the optical transmitting and receiving module and its manufacturing method according to the present invention align the optical elements such as LD or PD (photo diode) and PLC type optical waveguides by manual mark alignment method using V-groove, The alignment marks for the optical waveguide pattern, ICP and solder alignment also take advantage of the formation of the V-grooves in advance and the use of the V-grooves as the alignment marks for each process, and also for easy attachment of LD on the silicon substrate. A groove-type long solder is used, and the ultra-thin photoresist film is used to form the silicon V-groove solder pattern, which makes the manufacturing process simpler than the conventional technology, and optical devices such as LD or PD and WDM ( wavelength division multiplexing) Three types of PLCs, such as couplers and optical fibers, can be passively aligned at the same time, which greatly reduces the cost of manufacturing optical transmission modules. There is.

In addition, this invention is not limited only to the above-mentioned embodiment, It can implement by modifying and modifying within the range which does not deviate from the summary of this invention.

Claims (13)

In the optical transmission module, Alignment marks each formed at a predetermined position on an upper surface of the silicon substrate to facilitate alignment; PLC installed in the center of the upper portion of the silicon substrate using the alignment mark, Solder provided in the groove of the silicon substrate located on one side of the PLC, An optical element mounted on an upper side of the solder and on one side of the PLC; And an optical fiber installed on the other side of the PLC and in such a manner that the center of the core of the PLC and the center of the PLC coincide with each other, aligned on one substrate. The method of claim 1, The alignment mark is formed in the region where the optical device on the silicon substrate is to be formed, the optical transmission module characterized in that the V-groove is formed to a depth of 15㎛ ~ 20㎛ The method of claim 1, The solder is formed in the V-groove having a depth of 35 ~ 45㎛ and the optical transmission module, characterized in that the Ti / Au / AuSn solder The method of claim 1, The PLC and the optical fiber are placed in the U-groove of 60 ~ 65㎛ depth, optical transmission module, characterized in that to form a tapered U-groove between the PLC and the optical fiber The method of claim 1, The PLC is an optical transmission module, characterized in that formed in the order of the under-clad layer, core layer, over-clad layer In the manufacturing method of the optical transmission module, Forming a mask pattern for forming an alignment mark on the silicon substrate; Etching a lower exposed silicon substrate using the mask pattern to form a silicon terrace for placing alignment marks, solders, PLCs, and optical fibers; Depositing a predetermined thickness of an under-clad layer, a core layer, and an over-clad layer in order on the entire structure, Depositing a predetermined thickness of the ICP mask pattern forming material on the entire structure, and then patterning the pattern using a pre-formed V-groove alignment mark at the bottom to form an ICP mask pattern; Etching the lower over-clad layer, the core layer, and the under-clad layer in order using the ICP mask pattern to form a PLC; Removing the upper mask pattern, Forming a solder of a predetermined material in a V-groove formed at one side of the PLC; After completing the manual mark alignment by the alignment mark on one side, reflowing the solder portion to the external heat to install the optical device to be bonded to the electrode pad of the lower surface of the optical device; The optical transmission module manufacturing method comprising the step of seating the optical fiber on the other side of the PLC. The method of claim 6, Alignment mark and solder formed on the silicon substrate is V-groove, PLC and optical fiber is U-groove shape, characterized in that formed in the U-groove shape. The method of claim 6, Method for manufacturing an optical transmission module comprising using a silicon nitride film (Si ₃ N ₄ ) as a material for forming the mask pattern for the V-groove and the U-groove The method of claim 6, Method for manufacturing an optical transmission module, characterized in that the deposition thickness of the silicon nitride film is 1,000 ~ 2,000Å. The method of claim 6, In order to form a V-groove and a U-groove on the silicon substrate, the entire silicon substrate on which the silicon nitride film pattern is formed is immersed in a KOH aqueous solution at a temperature of 60 to 80 ° C. for about 2 to 3 hours. Optical transmission module manufacturing method The method of claim 6, Method of manufacturing an optical transmission module characterized in that the tapered U-groove is formed between the PLC and the optical fiber U-groove. The method of claim 6, The SiO ₂ film outside the PLC region is removed and the height from the surface of the silicon substrate to the upper side of the over-cladding layer is 20 to 35 μm. The method of claim 6, Solder formed in the long V-groove formed on one side of the PLC is made of a light transmission module, characterized in that formed of a material of Ti / Au / AuSn