JP2001332803A - Method of manufacturing optical integrated module and manufacturing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the degree of coincidence of the height of corresponding positions of plural optical elements on a substrate of an optical integrated module. SOLUTION: The height of an element to be newly installed is determined by setting the upper surface of an element which has been formed on the substrate as reference. By using the determined height, the element is fixed on the substrate. A lower surface of the element to be newly installed is made to abut against with an upper surface of the element which has been installed. The element to be newly installed is made to descend from the abutting height by a regulating amount. In another case, a distance between the lower surface of the element to be newly installed and the upper surface of the element which has been installed is detected. From the height, the element to be newly installed is made to descend by the sum of the detected distance and the regulating amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing an optical integrated module having various optical elements such as a light emitting element, an optical waveguide element and a light receiving element on the same substrate.

[0002]

2. Description of the Related Art In recent years, in the field of optical communication, a dramatic improvement in the manufacturing efficiency of an optical transceiver module serving as a key device has been required. Among them, the mass production of a planar lightwave circuit (PLC) optical integrated device using a planar mounting technology in which optical elements are hybridly arranged on a common substrate has attracted attention. The PLC optical integrated device uses an optical waveguide element made of quartz or a resin-based material as Si.
A small-sized optical integrated module having a plurality of functions by forming active elements such as laser diodes and photodiodes or optical fibers on the same substrate surface.

In an optical integrated module, in order to minimize the loss of light, the corresponding portions of a plurality of optical elements (for example, the emitting portion of a laser diode and the incident portion of an optical waveguide element) must be strictly matched. There have been proposed several alignment techniques for mounting an optical element on the upper surface of a semiconductor device. Above all, alignment using a marker is frequently used because of its high accuracy.

In this method, alignment marks are patterned on both the upper surface of a substrate on which an optical element is formed and the lower surface of an optical element mounted on the substrate, and the optical element to be mounted is arranged so that the two marks overlap. By doing so, the relative position of both elements in the direction (horizontal direction) along the upper surface of the substrate is set. The relative positions of the two elements in the height direction (vertical direction) perpendicular to the surface of the substrate are interposed between the electrodes so as to connect the electrodes provided on the upper surface of the substrate and the electrodes provided on the lower surface of the mounted optical element. It is determined by the thickness of the bump to be formed.

A specific example of a mounting method for aligning an optical waveguide element and a laser diode element (LD) using a marker will be described with reference to FIG. First,
As shown in FIG. 1A, one or more alignment marks 11 and one or more fixing pads 12 are formed on a portion other than the device 20 on the upper surface of the substrate 10 on which the optical waveguide device 20 is formed. Also, on the lower surface of the LD 30 to be mounted, the mark 11 and the pad 12 of the substrate 10 are mirror-symmetrical with each other.
The same number of marks 31 and the same number of pads 32 are formed. The marks 11 and 31 and the pads 12 and 32 are formed using a metal such as Au as a material by a film forming method such as an evaporation method or a sputtering method and a patterning method such as photolithography. At least one set of the pads 12 and 32 is for electrically connecting the LD 30 to a wiring pattern provided on the upper surface of the substrate 10.

Next, bumps 13 are formed on the pads 12. Specifically, a metal film such as AuSn having a relatively low melting point is formed on the upper surface of the substrate 10 to be slightly thicker by an evaporation method or the like, and the metal film is left on the pad 12 by patterning by photolithography or lift-off patterning. And
The substrate 10 is heated so that the metal film left on the pads 12 has a bump shape. The height of the bump 13 is slightly higher than the height of the lower surface of the pad 32 to be set.

After the bumps 13 are formed, the optical waveguide device 2
The LD 30 is fixed to the substrate 10 by aligning the position of the LD 30 with respect to 0. First, the LD 30 is moved in the horizontal direction while observing both the mark 11 of the substrate 10 and the mark 31 of the LD 30 using an infrared expanding optical system or the like, and (b)
As shown in (2), the horizontal position of the center of the mark 31 and the center of the mark 11 are matched.

Next, as shown in FIG. 1C, the LD 30 is lowered, and the pad 32 of the LD 30 is lightly brought into contact with the bump 13. The contact between the pad 32 of the LD 30 and the bump 13 is determined by a sensor such as a load cell provided on a holder for holding the LD 30. Then, the substrate 10 and the LD 30 are heated to melt the bumps 13, and the LD 30 is further lowered by a predetermined amount from the position where the LDs 30 are in contact with the bumps 13, so that the substrate 10
Then, the LD 13 is cooled to solidify the bump 13.

[0009]

According to the alignment method using a marker, the relative position in the horizontal direction of two optical elements on a substrate can be strictly determined. Therefore, there is almost no displacement of the corresponding portions of the two optical elements in the horizontal direction.

However, it is difficult to precisely determine the relative position of the two optical elements on the substrate in the vertical direction. As described above, the relative position in the vertical direction is determined based on the position at which the mounted optical element abuts on the bump, and the height of the bump is likely to vary.

Further, even if the height of the bump can be made constant, it is not easy to make the corresponding portions of the two optical elements exactly coincide with each other in the vertical direction. This is because errors in the thicknesses of the pads and layers in the element are accumulated and result in errors in the height of the corresponding portions. In the above-described example, in addition to the bump 13, the pad 32, the pad 12, the core 21 which is the waveguide of the optical waveguide element 20, and the lower cladding layer 22 provided thereunder cause errors.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a method and an apparatus for manufacturing an optical integrated module in which the heights of corresponding portions of a plurality of optical elements are high. And

[0013]

According to the present invention, there is provided a method of manufacturing an optical integrated module having a plurality of optical elements on the same substrate. The height of the lower surface of the second optical element is determined with reference to the upper surface of the optical element, and the second optical element is fixed on the substrate at the determined height.

For fixing the second optical element to the substrate, for example,
What is necessary is just to interpose a fixing member which is soft and solidifies later like the above-mentioned bumps between the substrate and the second optical element. In this method, it is possible to avoid the thickness of the fixing member from affecting the height of the second optical element. Therefore, the degree of coincidence of the heights of the corresponding portions of the first optical element and the second optical element Is expensive.
In addition, the error factor of the height of the corresponding part between the first optical element and the second optical element is only the thickness above the corresponding part in the first optical element. Even in a structure having a number of layers below the site, it is not necessary to set the thicknesses of those layers very strictly. Therefore, the first
This facilitates the manufacture of the optical element. Note that the first optical element is
It may be formed directly on the substrate, or may be independently manufactured and fixed to the substrate.

Specifically, the lower surface of the second optical element is brought into contact with the upper surface of the first optical element, and the height difference between the upper surface of the first optical element and the lower surface of the second optical element is equal to a predetermined value. The second optical element is moved relative to the substrate so that the second optical element is fixed on the substrate at the position after the movement.

Alternatively, the height difference between the upper surface of the first optical element and the lower surface of the second optical element is detected, and the height difference between the upper surface of the first optical element and the lower surface of the second optical element becomes a predetermined value. As described above, the second optical element is moved relative to the substrate, and the second optical element is fixed on the substrate at the position after the movement.

In these methods, the amount of vertical movement of the second optical element from a position in contact with the upper surface of the first optical element or a position where the height difference from the upper surface of the first optical element is measured is determined. It can be easily realized only by strict control.

The optical waveguide device is a first optical device, and the light emitting device is a second optical device.
It is preferable that the light emitting portions of the optical elements are opposed to each other. An optical integrated module that can efficiently use light emitted from the light emitting element can be obtained.

According to another aspect of the present invention, there is provided an apparatus for manufacturing an optical integrated module having a plurality of optical elements on the same substrate, comprising: substrate holding means for holding the substrate; An element holding means for holding the element and moving vertically, horizontally, and back and forth relative to the substrate holding means, and holding the upper surface of the optical element on the substrate held by the substrate holding means and the element holding means It is provided with contact detecting means for detecting the contact of the lower surface of the optical element and moving amount detecting means for detecting the amount of vertical movement of the element holding means relative to the substrate holding means.

The present invention further provides an optical integrated module manufacturing apparatus having a plurality of optical elements on the same substrate.
Substrate holding means for holding the substrate, holding the optical element fixed on the substrate, the vertical direction relative to the substrate holding means,
An element holding means that moves in the left-right direction and the front-back direction; a height difference detection means for detecting a height difference between an upper surface of the optical element on the substrate held by the substrate holding means and a lower surface of the optical element held by the element holding means; And a moving amount detecting means for detecting a vertical moving amount of the element holding means relative to the substrate holding means.

In these apparatuses, after the lower surface of the optical element to be fixed to the substrate is brought into contact with the upper surface of the optical element on the substrate, or the lower surface of the optical element to be fixed to the substrate and the optical element on the substrate, After detecting the height difference of the upper surface, the height of the lower surface of the optical element to be fixed can be adjusted by moving the element holding means while monitoring the amount of vertical movement of the element holding means. It can be set as a reference, and the above-described manufacturing method can be performed.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a method and apparatus for manufacturing an optical integrated module according to the present invention will be described below with reference to the drawings. Here, a case of manufacturing an optical integrated module in which a laser diode element is mounted on a substrate on which an optical waveguide element is formed will be described as an example. The upper and side surfaces of the main part of the manufactured optical integrated module 3 are shown in FIG.
(B) shows each. In FIG. 1, module 3
Are shown in perspective.

The optical integrated module 3 has a substrate 10, an optical waveguide element 20, and a laser diode element (LD) 30. The optical waveguide element 20 is formed directly on the substrate 10, and the LD 30 is manufactured independently of the optical waveguide element 20 and fixed on the substrate 10. The optical waveguide element 20 and the LD 30 are manufactured by a method well known in the art, and the manufacturing method is not directly related to the present invention, and thus the description is omitted.

The optical waveguide element 20 has a core 21 for guiding light.
And a lower cladding layer 22 located below the core 21 and an upper cladding layer 23 located above the core 21. The upper surface of the upper cladding layer 23 is flat, and this surface is the upper surface 20 a of the optical waveguide device 20.

The LD 30 has a band-shaped light emitting region (not shown) provided in the active layer, and an end face of which is formed in the core 2 of the optical waveguide element 20.
1 and is fixed to the substrate 10 so as to be positioned so that the central axis Ad of the light emitting region coincides with the central axis Ag of the core 21. LD30 and optical waveguide element 2
The alignment of 0 is performed in the horizontal direction by the method using the above-described marker, and in the vertical direction, the upper surface 20a of the optical waveguide element 20 is used as a reference.

A first method for manufacturing the optical integrated module 3 will be described. First, at least one alignment mark 11 and at least one pad 12 are formed on the upper surface 10a of the substrate 10 so that the lower surface 30a of the LD 30 is mirror-symmetrical to the mark 11 and the pad 12 of the substrate 10. To
The same number of marks 31 and the same number of pads 32 are formed. At this time, the horizontal distance from the center of the mark 11 to the central axis Ag of the core 21 is made equal to the horizontal distance from the center of the mark 31 to the central axis Ad of the light emitting region.

Marks 11, 31 and pads 12, 32
Is formed using a metal such as Au as a material and by a film forming method such as an evaporation method or a sputtering method and a patterning method such as photolithography. At least one set of the pads 12 and 32 is for electrically connecting the LD 30 to a wiring pattern (not shown) provided on the upper surface 10 a of the substrate 10. The lower surface 32a of the pad 32 (see FIG. 2) is an LD 30
Of the lower surface 30a.

Next, bumps 13 are formed on the pads 12. Specifically, a metal film such as AuSn having a relatively low melting point is formed on the upper surface of the substrate 10 to be slightly thicker by an evaporation method or the like, and the metal film is left on the pad 12 by patterning by photolithography or lift-off patterning. And
The substrate 10 is heated so that the metal film left on the pads 12 is formed into a bump shape. Although the height of the bump 13 is slightly higher than the height to be set on the lower surface 32a of the pad 32 of the LD 30, the upper end of the bump 13 is not used as a reference for alignment. There is no need to adjust.

After the formation of the bumps 13, the LD 30 is fixed to the substrate 10 while adjusting the position of the LD 30 with respect to the optical waveguide device 20. This step is shown in FIG. 2, (a), (b) and (d) are side views, and (c) is a plan view. First, as shown in (a), the LD 30 is slowly lowered from above the optical waveguide element 20, and
The lower surface 32a of the pad 32 of D30 is lightly brought into contact with the upper surface 20a of the optical waveguide element 20. Next, as shown in (b), the LD 30 is moved to the left in the drawing so that the mark 31 is located approximately above the mark 11. Then, the position of the LD 30 in the horizontal direction is adjusted while observing both the mark 11 of the substrate 10 and the mark 31 of the LD 30, and as shown in FIG.
The position of the center of 1 is matched.

After adjusting the horizontal position, the LD 30 is slowly lowered as shown in FIG.
The pad 32 is lightly brought into contact with the bump 13. In this state, the LD 30 and the substrate 10 are heated to melt the bumps 13, and the LD 30 is moved until the lowering amount from when the lower surface 32 a of the pad 32 contacts the upper surface 20 a of the optical waveguide element 20 reaches the specified amount L. Lower further. Then, the LD 30 and the substrate 10 are cooled to solidify the bumps 13. with this,
The fixing of the LD 30 to the substrate 10 is completed.

The prescribed amount L for lowering the LD 30 is a distance from the central axis Ag of the core 21 of the optical waveguide element 20 to the upper surface 20a, and a distance from the lower surface 30a of the LD 30 to the central axis A of the light emitting region.
d and the sum of the thickness of the pad 32. That is, if the thickness of the core 21 is A, the thickness of the upper cladding layer 23 is B, and the distance from the lower surface 32a of the pad 32 of the LD 30 to the center axis Ad of the light emitting region is C, L = A / 2 +
B + C. Thus, the center axis Ad of the light emitting region of the LD 30 becomes the same height as the center axis Ag of the core 21.

The above processing is performed by holding the substrate 10 and the LD 30 with separate holders.
However, it is not necessary to move the LD 30 relatively to the substrate 30, and it is not necessary to keep the holder of the substrate 10 at a fixed position and move the holder of the LD 30 in three directions of up, down, left, right, front and back.
When the holding of the LD 30 is stopped early after the bump 13 is solidified, the bump 13 may be cooled to room temperature.
The above-mentioned specified amount L may be corrected in consideration of the contraction of.

FIG. 3 schematically shows the structure of a manufacturing apparatus for carrying out the above manufacturing method. The apparatus 1 includes a substrate holder 41 that holds a substrate 10 and moves in a horizontal (front-rear, left-right) direction, an element holder 42 that holds an LD 30 and moves in a vertical (up-down) direction, and a height of the element holder 42. Length measuring device 43, mark 11 on substrate 10, and LD3
An infrared camera 44 for capturing an image of the 0 mark 31, a monitor 45 for displaying an image captured by the infrared camera 44,
It has a controller 46 that controls the whole, and an operation unit 47 that the user operates while observing the images of the marks 11 and 31 displayed on the monitor 46.

The substrate holder 41 also serves as a heater for heating the substrate 10, and the element holder 42 also serves as a heater for heating the LD 30. The element holder 42 is provided with a load cell sensor 48 for detecting a pressure applied from below, whereby the lower surface 32 of the pad 32 of the LD 30 is provided.
The contact between a and the upper surface 20a of the optical waveguide element 20 and the contact between the lower surface 32a of the pad 32 and the bump 13 are detected.

The controller 46 lowers the element holder 42 holding the LD 30 onto the optical waveguide element 20. When the contact is detected by the load cell sensor 48, the controller 46 stops the lowering. Element holder 42
Memorize the height of Then, the substrate holder 41 is moved in accordance with an instruction given by the user via the operation unit 47. When the horizontal alignment is completed, the user gives an instruction to start lowering. In response to this, the controller 46 lowers the element holder 42, and when the load cell sensor 48 detects contact with the bump 13, the lowering is performed. Stop.

Next, the substrate holder 41 and the element holder 42
Then, the substrate 13 and the LD 30 are heated to melt the bumps 13, and the element holder 42 is lowered until the change in the height of the element holder 42 detected by the laser length measuring device 43 reaches the specified amount L. The controller 46 places the element holder 4 in this position.
2 is temporarily stopped, and after the bumps 13 are solidified, the holding of the LD 30 by the element holder 42 is released.

In this embodiment, the user performs the horizontal alignment while observing the images of the marks 11 and 31 displayed on the monitor 45. However, the controller 46 automatically performs the horizontal alignment. It is also possible to perform it. For this purpose, the controller 46 may be provided with an image recognition function and the video signal of the infrared camera 44 may be provided to the controller 46. In this case, an extremely efficient manufacturing apparatus can be obtained. Further, the monitor 45 and the operation unit 47 become unnecessary.

A second method of manufacturing the optical integrated module 3 will be described. This manufacturing method is applied to the lower surface 32 of the pad 32.
a, the lower surface 32a of the pad 32 and the upper surface 20a of the optical waveguide device 20 are separated from each other, and the distance between the lower surface 30a of the LD 30 and the upper surface 20a of the optical waveguide device 20 is changed. Is different from the first manufacturing method in that This step is shown in FIG. LD
30 is positioned at an arbitrary height above the optical waveguide element 20 and, for example, a bidirectional laser length measuring device 49 is advanced between them, and the distance D between the lower surface 32a of the pad 32 and the upper surface 20a of the optical waveguide element 20 is increased. Is measured.

The subsequent processing is as described in the first manufacturing method. However, the amount L ′ of lowering the LD 30 from the state of FIG. 4 is L ′ = A / 2 + B + C + D by adding the measured distance D to the above-mentioned specified amount L.

FIG. 5 schematically shows the structure of a manufacturing apparatus for performing the second manufacturing method. This device 2 is shown in FIG.
Is a device in which a bidirectional laser length measuring device 49 is added to the device 1 shown in FIG. The bidirectional laser length measuring device 49 is movable in the horizontal (front-rear, left-right) directions, and includes the substrate holder 41 and the element holder 4 located above the substrate holder 41.
2 and can escape from it. The controller 46 includes a bidirectional laser length measuring device 49.
Is moved to the upper surface 20 of the LD 30 and the optical waveguide element 20.
Find the distance of a. Thus, the distance between the lower surface 30a of the LD 30 and the upper surface 20a of the optical waveguide device 20 is detected.

In the apparatus 2, since the load cell sensor 48 is omitted, the descent of the element holder 42 is stopped shortly before the above-described amount L 'is reached, and heating is performed at that position to melt the bumps 13. .

In each of the above examples, the manufacture of an optical integrated module having two optical elements, an optical waveguide element and a laser diode element, on a substrate has been described.
The present invention can be applied to an optical integrated module having the above-described optical element, and there is no limitation on the type of the optical element. Also, here
Although one of the optical elements is formed directly on the substrate, both may be manufactured independently of the substrate and fixed to the substrate.
In this case, even if an error occurs in the height of the optical element fixed first, the height of the other optical element is determined based on the height of the upper surface of the optical element. The height error has no effect on the coincidence of the heights of the two elements.

In each of the above examples, the height of the bump 13 is slightly higher than the height to be set, but it is not always necessary to make it higher. The bumps 13 may be lower than the height to be set, and the LD 30 may be fixed while being pulled up when the LD 30 is fixed.

The infrared camera 44 is connected to the substrate holder 41.
May be arranged below. This is effective when the LD 30 does not transmit infrared light. Further, the length measuring device 43 may be configured integrally with the element holder 42 so as to measure the distance to the substrate 10. Since there is no support column, the distance to be measured can be measured accurately.

[0045]

According to the method of manufacturing an optical integrated module of the present invention, it is possible to prevent the thickness of the fixing member from affecting the height of the optical element newly fixed to the substrate. The heights of the parts can be accurately matched. Moreover, as for the optical element provided on the substrate, the only factor of the height error is the thickness above the corresponding portion, and the thickness below the corresponding portion does not become a factor of the height error. Therefore, it is possible to accurately match the height of a new optical element to an optical element having a number of layers below the corresponding portion, and it is easy to manufacture the optical element.

The optical integrated module manufacturing apparatus of the present invention
A manufacturing method that achieves the above effects can be implemented with a relatively simple configuration.

[Brief description of the drawings]

FIG. 1 is a top view and a side view showing a main part of an optical integrated module manufactured by first and second manufacturing methods of the present invention.

FIG. 2 is a diagram showing a part of a manufacturing process in a first manufacturing method.

FIG. 3 is a diagram schematically showing a schematic configuration of a manufacturing apparatus for performing a first manufacturing method.

FIG. 4 is a view showing a part of a manufacturing process in a second manufacturing method.

FIG. 5 is a diagram schematically showing a schematic configuration of a manufacturing apparatus for performing a second manufacturing method.

FIG. 6 is a view showing a part of a manufacturing process in a conventional method for manufacturing an optical integrated module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 2 Optical integrated module manufacturing apparatus 3 Optical integrated module 10 Substrate 10a Substrate upper surface 11 Mark 12 Pad 13 Bump 20 Optical waveguide device 20a Optical waveguide device upper surface 21 Core 22 Lower cladding layer 23 Upper cladding layer 30 Laser diode 30a Laser diode lower surface 31 Mark 32 pad 32a pad lower surface 41 substrate holder 42 element holder 43 laser measuring device 44 infrared camera 45 monitor 46 controller 47 operation unit 48 load cell sensor 49 bidirectional laser measuring device

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H01L 33/00 H01L 31/02 D 5F088 F term (reference) 2H037 AA01 BA02 BA11 DA03 DA06 DA18 DA22 2H047 KA03 MA07 RA08 TA05 TA31 TA43 TA44 5F041 AA38 AA39 DA04 DA09 DA19 DB09 EE25 FF14 5F044 PP17 QQ01 QQ09 RR01 5F073 AB25 FA06 FA16 FA22 FA23 5F088 BA16 BA18 BB01 JA03 JA09 JA14

Claims (6)

[Claims] 1. A method of manufacturing an optical integrated module having a plurality of optical elements on the same substrate, wherein a lower surface of a second optical element is defined with reference to an upper surface of the first optical element already provided on the substrate. A method of manufacturing an optical integrated module, comprising determining a height and fixing a second optical element on a substrate at the determined height. 2. A lower surface of a second optical element is brought into contact with an upper surface of the first optical element so that a height difference between an upper surface of the first optical element and a lower surface of the second optical element becomes a predetermined value. The method according to claim 1, wherein the second optical element is moved relative to the substrate, and the second optical element is fixed on the substrate at a position after the movement. . 3. A height difference between an upper surface of the first optical element and a lower surface of the second optical element is detected, and a height difference between an upper surface of the first optical element and a lower surface of the second optical element becomes a predetermined value. Move the second optical element relative to the substrate as described above, and move the second optical element to the second position at the position after the movement.
2. The optical element according to claim 1, wherein the optical element is fixed on a substrate.
3. The method for manufacturing an optical integrated module according to item 1. 4. The first optical element is an optical waveguide element, the second optical element is a light emitting element, and a light emitting part of the second optical element is opposed to a light incident part of the first optical element. The method for manufacturing an optical integrated module according to any one of claims 1 to 3, wherein: 5. An apparatus for manufacturing an optical integrated module having a plurality of optical elements on the same substrate, comprising: a substrate holding means for holding the substrate; and an optical element for fixing the optical element on the substrate. Relatively up and down direction,
Element holding means for moving in the left-right direction and front-back direction; contact detection means for detecting contact between the upper surface of the optical element on the substrate held by the substrate holding means and the lower surface of the optical element held by the element holding means; An optical integrated module manufacturing apparatus, comprising: a moving amount detecting means for detecting a vertical moving amount of the element holding means relative to the substrate holding means. 6. An apparatus for manufacturing an optical integrated module having a plurality of optical elements on the same substrate, comprising: a substrate holding means for holding the substrate; and an optical element for fixing the optical element on the substrate. Relatively up and down direction,
An element holding means that moves in the left-right direction and the front-back direction; a height difference detection means for detecting a height difference between an upper surface of the optical element on the substrate held by the substrate holding means and a lower surface of the optical element held by the element holding means; An optical integrated module manufacturing apparatus, comprising: a moving amount detecting means for detecting a vertical moving amount of the element holding means relative to the substrate holding means.