KR20020059313A - Apparatus for optical interconnecting by using optical connection rods - Google Patents

Abstract

PURPOSE: An optical interconnection device using an optical interconnection bar is provided to perform rapidly a signal transmission operation between semiconductor chips by inserting the optical interconnection bar into an optical substrate including a light waveguide. CONSTITUTION: A solder chip(S1) is adhered between the first printed circuit board(10) and the second and the third printed circuit boards(20,30) by using a flip chip solder bonding method. The first and the second semiconductor chips(3,8), a laser drive chip(4), a surface-emitting light source array(5), an optical detector array(6), and an optical receiver chip(7) are adhered on the first printed circuit board(10) by using the flip chip solder bonding method. A plurality of through-hole(50,50-1,51,51-1) is formed on the second and the third printed circuit boards(20,30). A plurality of optical interconnection bar array(52,52-1,53,53-1) is inserted through the through-holes(50,50-1,51,51-1) in order to provide an optical signal of the surface-emitting light source array(5) to optical detector array(6).

Description

Optical connection device using optical connecting rods {APPARATUS FOR OPTICAL INTERCONNECTING BY USING OPTICAL CONNECTION RODS}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical connecting device using an optical connecting rod. In particular, in a board on which a plurality of semiconductor chips are mounted, an optical connecting packaging for transmitting an optical signal using an optical connecting rod to an optical substrate in which an optical waveguide is buried. Relates to a device.

In general, an optical connection packaging apparatus is a system that mounts a plurality of semiconductor chips and provides various signals through electrical wiring, and the system described above in next-generation high-speed parallel computers requiring high wiring density and relatively long wiring. There is some difficulty in applying this.

In other words, as the length of the wire increases, the transmission line effect influences the performance of the electrical wiring, and the transmission line effect not only attenuates the electrical signal through the skin effect, but also causes multiple reflection of the signal if the wiring is not properly terminated.

In addition, in the electrical connection line between the board, the data transfer rate becomes a bottleneck limiting the data processing speed of the entire system, and optical interconnection is applied to solve the shortcomings of the electrical wiring.

Here, the optical connection has a wide bandwidth and is insensitive to crosstalk and inter-signal interference. Therefore, the optical connection enables high-speed signal transmission between chips and increases wiring density. The power consumption of the system, crosstalk, Electromagnetic interference can be reduced, and it is widely used for inter-system data transmission of several meters to hundreds of meters, inter-board connections in systems of tens of centimeters, and data links of several centimeters to tens of centimeters on board.

As such, for the optical connection, an end portion of each transceiver is connected to an optical fiber ribbon or an optical waveguide array. In other words, in order to apply a wide range of optical connections, it is necessary to develop a structure that can be applied to a printed circuit board (PCB) technology. In view of this, optical connections are made using a board in which an optical waveguide is buried in a PCB. Development is needed.

In addition to the manufacturing technology of PCBs with optical waveguides embedded, optical connection packaging technology includes more than 10-channel laser diode array technology, polymer optical waveguide manufacturing technology using lithography or liga process for optical signal transmission in packaging, and optical transmission and reception device. In many cases, such as silicon optical bench, lens, micro-mirror for the signal connection between the optical path and the optical path.

In the optical connection structure using the conventional unit technology described above, a technique using a microlens or the like is used to optically connect light emitted or emitted from an optical transmission / reception element to an optical waveguide embedded in a PCB. Even if a board is used as a substrate, there are difficulties in the process of the optical waveguide embedded in the optical PCB and optical connection and alignment of the optical waveguide embedded in the PCB in the optical transmission and reception device.

In addition, in order to optically connect the light emitted from or received from the optical transmitter and receiver to the optical waveguide buried in the PCB, there is a process difficulty in etching or cutting both ends of the optical waveguide at 45 degrees. In the case of using an optical pin capable of efficiently reflecting light, the optical loss due to the spread of the light emitted from the optical transmitter is increased.

In particular, as the surface emitting laser / light emitting diode of the light transmitting unit spreads the emitted light, inaccuracy and loss of the optical connection due to crosstalk and signal interference occurs. In order to compensate for these disadvantages, a complicated optical connection structure has to be formed due to a process and manufacturing difficulties in which a microlens for condensing light is formed between an optical transmitter and an optical waveguide.

In addition, optical alignment is not easy because the height of the side emitting laser and the optical waveguide must be exactly matched to increase the optical coupling efficiency, and the microlens, the surface emitting laser / light emitting diode, the photodiode, and the 45-degree There was a problem that optical alignment with an optical waveguide was impossible.

Accordingly, an object of the present invention is to solve the above-described problems, and an object thereof is to directly insert an optical connecting rod into an optical substrate in which an optical waveguide is buried so that signals between semiconductor chips can be transmitted at high speed, and a unit optical substrate and an optical There is an advantage in that individual optical parts manufactured based on device manufacturing technology can be used, and optical connection using optical connecting rods can provide an optical connection structure between semiconductor chips with high precision of optical alignment using flip chip bonding. In providing a device.

In the present invention for achieving the above object, an optical connecting device using an optical connecting rod is mounted on a first circuit board, the first semiconductor chip is driven in accordance with an electrical signal; A surface emitting light source array such as a vertical-cavity surface-emitting laser (VCSEL) or surface emitting diode (LED) that is modulated at high speed by a laser drive circuit driven by a first semiconductor chip; 45. As an example of the reflective surface 54 in which the modulated light emitted from the surface-emitting light source array is inserted into the through hole of the second and third circuit boards, respectively, is inclined. An optical connecting rod array reflecting light from an inclined reflecting surface to the optical waveguide array and reflecting light incident through the optical waveguide array from the inclined reflecting surface 54-1 to send light to the photodetector window; A photodetector array configured to independently receive light incident through the optical connecting rod array; And an optical receiver chip for converting the optical signal received from the photodetector array into an electrical signal and providing the second signal to the second semiconductor chip.

1 is a vertical cross-sectional view of an optical connecting device using an optical connecting rod according to the present invention,

2 is a horizontal cross-sectional view of an optical connecting device using an optical connecting rod according to the present invention,

3 is a view showing a through-hole formation of a circuit board according to the present invention,

4 is a diagram illustrating a shape of an optical connecting rod array according to the present invention.

<Description of the symbols for the main parts of the drawings>

10,20,30: 1st, 2nd, 3rd circuit board 3,8: 1st, 2nd semiconductor chip

4 laser driving chip 5 surface emitting light source array

6 photodetector array 7 photoreceiver chip

12: Optical Waveguide Array 13: Cladding of Optical Waveguide

50,50-1,51,51-1: through hole 52,52-1,53,53-1: optical connecting rod array

54,54-1: Reflective surface 70: Epoxy

55,56 Anti-reflective coating 57: Reflective coating

58: focusing lens 59: core layer

60: cladding

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment according to the present invention.

1 is a vertical cross-sectional view of an optical connecting device using an optical connecting rod according to the present invention, Figure 2 is a horizontal cross-sectional view of the optical connecting device, Figure 3 is a through hole (50, 50-) shown in Figures 1 and 2 1, 51, and 51-1 are diagrams showing the formation of flip chip solder bonding techniques between the first circuit board 10 and the second and third circuit boards 20 and 30, like solder bumps S1. After the adhesion process is performed, the first and second semiconductor chips 3 and 8 and the laser driving chip 4 may be formed on the first circuit board 10 through a flip chip solder bonding technique, such as solder bumps S1. The surface emitting light source array 5, the photodetector array 6, and the photoreceiver chip 7 are attached to each other, and the through holes 50, 50-1, and 51 are formed in the second and third circuit boards 20 and 30, respectively. , 51-1, having optical holes, 52, 52 having reflective surfaces 54, 54-1 inclined to one surface through the through holes 50, 50-1, 51, and 51-1. -1, 53, 53-1 are inserted into the surface emitting light source array 5 Is configured to be able to enter the photodetector array 6.

Based on the above-described configuration, the operation principle of the optical connecting device using the optical connecting rod according to the present invention and its operation method will be described in more detail.

First, the surface emitting light source elements constituting the surface emitting light source array 5 are independently driven by a laser driving circuit driven according to an electrical signal of the first semiconductor chip 3 mounted on the first circuit board 10. By emitting modulated light of a predetermined wavelength from the surface emitting light source is modulated at a high speed to provide to the optical connecting rod array (52, 52-1).

Then, the light emitted from the surface emitting light source array 5 is transmitted through the light connecting rod arrays 52 and 52-1, and reflected by the inclined reflecting surface 54 of the light connecting rod arrays 52 and 52-1. And enters the optical waveguide array 12.

Again, light incident through the optical waveguide array 12 is reflected at the inclined reflecting surface 54-1 of the optical rod array 53 and is incident on the photodetector array 6 through the optical rod array 53. .

The photodetector array 6 independently receives the light incident through the optical connecting rod array 53, and then converts the optical signal received by the photoreceiver chip 7 into an electrical signal to convert the second semiconductor chip 8 into an electrical signal. To provide.

Here, the surface emitting light source array 5 uses a general surface emitting light source array, and the photodetector array 6 uses a photodiode.

Further, the surface emitting light source array 5 has a top-emitting structure that emits light in the direction of the circuit boards 20 and 30, and the photodetector array 6 has light in the direction of the circuit boards 20 and 30. It has a top-illuminated structure, the photoreceiver chip 7 and the photodetector array 6 may be composed of one chip, the first and second semiconductor chips (3, 8) are micro A semiconductor chip such as a process (MPU) and a memory.

The optical connecting rod arrays 52, 52-1, 53, and 53-1 are made of a material such as optical fiber, optical plastic, glass, etc., which have low light loss and excellent thermal and chemical stability in light transmission. And inserted into the through holes 50, 50-1, 51, and 51-1 formed in the three circuit boards 20 and 30 and connected to the optical waveguide array 12.

Here, the through holes 50, 50-1, 51, and 51-1 may have cylindrical and rectangular shapes, and the optical waveguide array 12 may include optical connection rod arrays 52, 52-1, 53, and 53-1. ) Is formed on the opposite surface of the surface) and the opposite surface has reflective surfaces 54 and 54-1 which are inclinedly cut so as to send light into the optical waveguide, and the reflective surfaces 54 and 54-1 increase reflection efficiency. In order to achieve this, the film is coated with a high reflectance thin film such as a metal thin film of gold (Au), silver (Ag), aluminum (Al), or the like.

In addition, referring to Figure 4, it is a view showing the shape of the optical connecting rod array according to the present invention, having a cylindrical shape of Figure 4a and a square shape of Figure 4b, the light emitted from the surface emitting light source array (5) To the optical waveguide array 12 to form a focusing lens 58 and an anti-reflective coating 55 on the bottom of the optical connecting rod array 52, 52-1, 53, 53-1 to reduce light loss, The antireflective coating 56 is formed on the tops of the optical connecting rod arrays 52 and 53, and the reflective coating is performed on the side of the optical connecting rod arrays 52, 52-1, 53 and 53-1 by using a thin film of high reflectivity such as a metal thin film. 57) to increase the efficiency of the optical connection by forming a core layer 59 for a high refractive index optical waveguide in which the optical connecting rod arrays 52, 52-1, 53, 53-1 are surrounded by the cladding 60. Let's do it.

Meanwhile, the change in refractive index due to the gap between the optical rod arrays 52, 52-1, 53, 53-1 and the optical waveguide array 12 is canceled, and the optical rod arrays 52, 52-1, 53, 53-1 are offset. Refractive index matching epoxy 70 is inserted through the refractive index matching oil or refractive index matching polymer to improve the adhesion of the &lt; RTI ID = 0.0 &gt;

In addition, the optical waveguide array 12 shown in FIG. 1 is a polyimide-based polymer, amorphous Si ₃ N ₄ , SiO ₂ -TiO ₂ glass having low optical waveguide loss and excellent thermal and chemical stability at a laser oscillation wavelength. It is a multimode optical waveguide made of a material such as, and the like, the cladding 13 of the optical waveguide confines the light to the optical waveguide array 12 and simultaneously protects the optical waveguide array 12, It is made of a material having a smaller refractive index than (12).

As described above, the present invention improves the accuracy of optical path alignment between the light source-waveguide and the optical waveguide-photodetector by directly inserting an optical connecting rod having an inclined reflecting surface at one end into an optical substrate in which the optical waveguide is buried. There is no need to make a reflective surface at the end of the optical waveguide, there is a usable effect. In addition, the circuit board and the optical substrate are bonded using flip chip bonding technology to obtain a very precise alignment between the two substrates, and the characteristics of the circuit board can be individually evaluated to yield the light yield of the optical connection module finally made. It is possible to increase the efficiency, thereby optimizing the performance.

Claims (7)

In the optical connection packaging device in the first, second, third circuit board, A first semiconductor chip mounted on the first circuit board and driven according to an electrical signal; A surface emitting light source array for emitting modulated light having a predetermined wavelength from the surface emitting light source which is independently modulated at high speed by driving the surface emitting light sources independently by a laser driving circuit driven by the first semiconductor chip; Inserted into the through holes of the second and third circuit boards, respectively, the modulated light emitted from the surface emitting light source array is reflected on the inclined reflecting surface 54 to be incident on the optical waveguide array, and through the optical waveguide array. An optical connecting rod array for reflecting incident light from the inclined reflecting surface 54-1; A photodetector array that independently receives light incident through the optical connecting rod array; And an optical receiver chip for converting the optical signal received from the photodetector array into an electrical signal and providing the second signal to the second semiconductor chip. The method of claim 1, The surface emitting light source array uses a vertical resonance type surface emitting laser (VCSEL) array, and the photodetector array uses an MSM photodiode or a p-i-n photodiode. The method of claim 1, The optical connecting rod array uses a silica optical fiber or a plastic optical fiber having low optical loss and excellent thermal and chemical stability, and forms an inclined surface at one end to be connected to the optical waveguide array. . The method of claim 1, The connecting rod is coated with a thin film of silver (Ag), gold (Au), aluminum (Al) or a thin film of high reflectivity on the inclined reflective surface formed at the end connected to the optical waveguide. Optical connecting rod. The method of claim 1, The through hole is in the form of a cylinder and a square, the optical connecting rod, characterized in that the optical connecting rod array is inserted into the through hole in the form of a cylinder and a square. The method of claim 1, When the light emitted from the surface emitting LED array is emitted to the optical waveguide array, a focusing lens and an antireflective coating are formed on the bottom of the optical connecting rod array to reduce light loss, and an antireflective coating is formed on the top of the optical connecting rod array. And forming a reflective coating on a side of the optical connecting rod array by using a metal thin film, and forming a core layer for an optical waveguide having a high refractive index surrounded by the cladding of the optical connecting rod array to reduce optical loss. The method of claim 1, The refractive index change due to the gap between the optical rod array and the optical waveguide array, and the refractive index matching epoxy through the refractive index matching polymer to improve the adhesion of the optical rod array.