KR100524778B1 - Silicon optical bench manufacturing method - Google Patents

Abstract

The present invention relates to a method for manufacturing a silicon optical bench, a conventional method for manufacturing a silicon optical bench using a costly bonding equipment to place a silicon optical bench on top of the heater of the equipment, at the same time to melt the solder formed on each joint at one kind Joining of different parts by joining the parts of the parts, heating the solder again, and then joining the different types of parts, so that the parts are not joined but only the solder is repeatedly heated. In addition to the deterioration of characteristics and electrical properties, there is a problem that the process yield is low because the heating time is long, and the cost is high because expensive equipment is used. In view of the above problems, the present invention is to form a heater through a semiconductor process on an electrode of a silicon optical bench and then apply a solder to the upper part of the silicon optical bench. By providing a method for manufacturing silicon optical benches that can be bonded to each other, the manufacturing cost can be reduced because the bonding can be performed without expensive equipment, and only the desired portion of the solder can be melted selectively, thus not affecting the unselected solder. It is possible to improve the bonding performance and electrical connection characteristics, and in the case of a large number of parts to be bonded, it is possible to increase the yield by connecting all the heater electrodes and applying current at once.

Description

Silicon optical bench manufacturing method {SILICON OPTICAL BENCH MANUFACTURING METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a silicon optical bench, and in particular, to form a heater through a semiconductor process between an electrode and a solder to which a component is applied in order to easily join each component of the silicon optical bench. The present invention relates to a method for manufacturing a silicon photobench, which enables to improve process time and quality without expensive process equipment.

With the spread of wired and wireless Internet and the spread of various information communication terminals, subscribers' access and use of information are becoming a natural everyday. However, in order to use more information and faster information, it is absolutely necessary to disseminate the optical cable, which is a high-speed communication network that exceeds the limitations of the current high-speed communication network.

Along with the necessity of such a high speed communication network, various researches are being conducted to build an optimal backbone communication network by combining various currently installed network services. In other words, the problem of how to build a high-speed information communication network is to provide various narrow-band services and scattered broadband services at the same time and economically, and to implement various subscriber transmission methods and transmissions for constructing a communication network that can flexibly cope with B-ISDN services. Along with the review of devices, research is being actively conducted.

The conversion from the communication network to the optical communication network using the coaxial cable is progressing mainly with the relay network, but the development is progressing with the aim of expanding to the access network reaching the subscribers. Among the optical components used in the construction of the optical network, the most important and expensive optical module is MEMS (Micro-Electro Mechanialc System) technology, which enables mass production, miniaturization, and integration, greatly accelerating the spread of optical networks and expanding subscribers. You can contribute.

In general, a process that occupies the largest portion of the manufacturing price in the process of manufacturing the optical module is a process of bonding a laser diode and a photo diode on a silicon substrate. After precisely arranging optical module components such as optical fiber, laser diode, and photo diode on a silicon substrate, the electrical connection is based on a silicon optical bench using MEMS technology manufactured using a metal process during semiconductor processing. Hereinafter referred to as SiOB). In the SiOB, alignment of the x, y, and z directions between components is performed through an etching process, and a process of three-dimensionally setting the positions of the components through such an etching process (forming a three-dimensional precision etching structure) and The process of arranging and joining the parts to the formed three-dimensional shape is a key process in manufacturing SiOB.

In recent years, an LCD back lighting module has been fabricated by a silicon optical bench that has an electric wiring for accurately aligning a light emitting diode (LED) element in a x, y, z direction and controlling a flashing operation on a silicon substrate. As a core component of the company, the use of the silicon optical bench is gradually diversifying and becoming the core.

FIG. 1 is a perspective view briefly illustrating one type of SiOB, and as shown, an optical fiber 2, a laser diode 3, a photodiode 4, and an electrode for electrical connection on a silicon substrate 1. 5) are formed. An insulating layer (not shown) may be formed on the silicon substrate 1 to insulate the silicon substrate 1 from the electrodes 5.

First, the silicon substrate 1 is wet-etched to form a three-dimensional structure by wet etching the silicon substrate 1 so that the optical fiber 2, the laser diode 3, and the photodiode 4 can be bonded to each other to form a metal electrode 5 thereon. do. The three-dimensional structure formed through such etching is called a groove, and after applying a solder (not shown) to the electrode 5 positioned on the formed groove, the laser diode 3 and the photodiode 4 ) And melt by soldering the solder. The bonding method using such solder is called flip chip bonding.

2 is a conceptual diagram illustrating flip chip bonding of optical components 14 and 15 onto a silicon substrate on which electrodes are formed using an expensive bonding machine.

The substrate 10 forming the silicon optical bench is placed on the heater 30 provided in the bonding equipment, and the laser diode 14 is moved to the first groove by using the pick-up tip 20. After positioning, the heater 30 is heated above the melting temperature of the solder 13 applied on the electrode 12 of the groove to couple the laser diode 14. Then, the photodiode 15 is positioned on the second groove (right side) by using the pickup tip 20, and the heater 30 is reheated to couple the photodiode 15.

The conventional flip chip bonding method as described above has a problem in that the overall product price increases because the components of the module are combined using expensive bonding equipment, thereby reducing the competitiveness. In addition, if two or more parts need to be joined, during the time of heating the heater to melt the solder of the first groove and join the parts, heat is transferred not only to the solder of the first groove but also to the solder of the other groove, The solder will melt at the same time. As a result, when only the solder is melted and the parts are not bonded, oxidation occurs on the surface of the solder, and the condition of the solder is changed. Therefore, when the parts are joined to the second groove, the bonding tension and electrical characteristics are deteriorated. In particular, when there are many types of parts to be joined, there is a fatal problem in that the change of conditions of solders in which each part is to be placed is large. In addition, since the indirect heating method of heating the external heater to heat the solder through the silicon substrate of the silicon optical bench, the efficiency is lowered, further increasing the cost of energy consumption.

As described above, the conventional silicon optical bench manufacturing method uses an expensive bonding equipment to place a silicon optical bench on the heater of the equipment, and simultaneously melts the solder formed at each junction and then joins one kind of component, and then solders again. Since the bonding of various components is performed by heating different types of components after joining them, the soldering characteristics and electrical characteristics of the solder to which the components are joined later deteriorate as the components are not bonded but only the solder is repeatedly heated. In addition, since the heating takes a long time, the process yield is low, and there is a problem in that the cost is high because expensive equipment is used.

In view of the above problems, the present invention is to form a heater through the semiconductor process on the electrode of the silicon optical bench and then to apply the solder on the upper part, by melting the solder by selectively applying a current only to the heater formed in the desired portion. Since parts can be joined together, it is possible to join without expensive equipment, thereby reducing manufacturing costs and selectively melting only the desired parts of the solder, thereby improving joining performance without affecting unselected solders. In the case of a large number of parts to be connected to all the heater electrodes by applying a current at a time to provide a silicon optical bench manufacturing method that can be quickly bonded to increase the yield.

The present invention for achieving the above object comprises the steps of forming a groove on the component junction on the silicon substrate, and then forming an insulating layer and an electrode; Forming a heater layer having an electrode pad on the formed electrode to enable selective driving; Forming a solder layer on the heater layer that can be melted by the operation of the heater layer; And placing the component on the formed solder layer, and melting the solder layer by selectively applying a current to the heater layer, thereby bonding the component.

The heater layer formed on the electrode has a meander structure to increase efficiency, and the electrode pad extends to the outside of the groove for the convenience of selective driving.

DETAILED DESCRIPTION OF THE EMBODIMENTS Embodiments of the present invention implemented as described above will be described in detail with reference to the accompanying drawings.

3A to 3D are cross-sectional views showing a manufacturing process of an embodiment of the present invention. The present invention is to form a heater layer 43 using a semiconductor process at a component bonding position of a silicon optical bench and a solder layer 44 thereon. ) By applying a current to the heater layer 43 to melt the solder layer 44 to join the parts in a simple manner without expensive bonding equipment. In this embodiment, the parts are joined to the mid-end heater layer 43. It is formed on the electrode 42 of the groove to be.

First, as shown in FIG. 3A, the silicon substrate 41 is wet-etched with KOH solution to form a groove, and an insulating layer 41 is formed on the groove. The etching process for making such a groove requires an etching mask to distinguish between the portion to be etched and the portion to be protected from etching, and the mask to be used must be a material that can be used as a mask during the time of wet etching. Generally silicon nitride film is used a lot. The insulating layer 41 is used to insulate the electrode 42 and the silicon substrate 40 to be formed later. Generally, a silicon nitride film or a silicon oxide film is used. In particular, since the silicon oxide film is grown by heat treatment at a high temperature of about 1100 ° C., its film quality and insulation properties are excellent. In addition, by fabricating a silicon bench using a high resistivity silicon substrate, it is possible to reduce leakage current at high frequencies.

Next, as shown in FIG. 3B, an electrode 42 is formed on the insulating layer 41. The electrode 42 is to provide an electrical connection to the component to be coupled to the silicon bench, and should not only have excellent electrical characteristics, but also have good adhesion with the insulating layer 41. In general, a silicon oxide film, which is an insulating layer 41, titanium (Ti), chromium (Cr), and the like, which have excellent adhesion, and gold (Au), which has good electrical characteristics and can be easily deposited in a semiconductor process, is used. Since the electrode 42 is exposed to high temperatures when joining the components of the module during the post-process, titanium or chromium, which is an adhesion layer, may be diffused into gold, thereby reducing the electrical properties of the gold. A diffusion barrier layer such as platinum (Pt) or nickel (Ni) is used between chromium. The metals forming the electrode have a Ti / Pt / Au or Cr / Ni / Au structure using a sputtering method, which has been proven in the reliability of physical properties in a semiconductor process, or an E-beam deposition method. The electrode 42 of the structure can be deposited in order and a pattern can be formed by a lift-off method.

Next, as shown in FIG. 3C, a heater layer 43 having a selection electrode pad extending outward is formed on the electrode 42. The heater layer 43 may be classified into a heating element and an electrode pad for supplying power to the heating element, and the heating element is positioned below the solder layer to be melted using the heat of the heating element, thereby exhibiting maximum efficiency. Do it. In addition, the size or shape of the heating element and the choice of materials can be used in various ways depending on the solder and the product. When the current to be used is applied, it is configured to dissipate sufficient heat to melt the solder. In this embodiment, as shown in the drawing, the heating element has a meander pattern to generate heat of high efficiency even in a small area.

Precious metals such as platinum and gold, copper, nickel, tungsten, molybdenum, tantalum, and the like are used as the material of the heating element. It is desirable to minimize the stress to further increase the reliability of the product, and when this thermal stress is minimized, it is possible to form a precise heating element having a desired shape and a desired thickness in a desired area using MEMS technology. The most common MEMS techniques include sputtering and two-beam deposition. In addition, physical vapor deposition (PVD) and chemical vapor deposition (CVD) can be used. And, the electrode pad for supplying power to the heating element should be manufactured in a thickness or shape that can sufficiently accommodate the flow of current, it is preferable to be located on the outside of the groove so that the current can be easily applied. The electrode pad may be formed by using a heating material such as platinum, gold, copper, nickel, and the like with the formation of a heating element.

Next, as shown in FIG. 3D, a solder layer 44 is formed on the formed heater layer 43. The solder layer 44 uses indium (In), gold tin (AuSn), red tin (PbSn), etc. having a relatively low melting temperature, and may be formed by an e-beam deposition method. In the case of mixtures such as gold tin or red tin, deposition is carried out using a single target in which gold (Au) / red (Pb) and tin (Sn) are mixed in a desired ratio, or the respective materials are sequentially stacked. It can be deposited in the form of a mixed layer and can also be formed by co-evaporation.

The silicon bench with the heater formed as described above can not only manufacture a module that optimizes the characteristics between devices by placing necessary parts in a passive alignment method, but also apply a current to the heater to melt the solder to join the parts. Therefore, manufacturing costs and time can be significantly reduced compared to the case of joining parts using expensive joining equipment.

4 is a plan view of the heater layer 43 formed in the groove from the top to more clearly explain the shape of the heater layer 43 formed through FIGS. 3A through 3C. The electrode formed in the groove as shown in FIG. (42) The structure of the heater layer 43 formed in the midenda structure at the top can be seen. The electrode 42 is connected to the outside, but is omitted for convenience of description.

As shown in the drawing, a heating element portion of the heater layer 43 may be formed in a meander structure to increase efficiency, and in order to easily apply current to the heating element, electrode pad portions may be extended to the outside of the groove to be disposed on the silicon optical bench surface. do.

5 shows the configuration of the heater layer 43 in the case where a plurality of parts are formed, and the joining should be made at different time points (sequentially), respectively. Each heater layer 43a, 43b can be supplied with current by individual selection, so that after placing one type of component, only the heater layer (e.g. 43a) can selectively supply current to join the component. In this case, the other heater layer (for example, 43b) in which no current flows does not generate heat, so that the solder layer (not shown) formed in the other heater layer 43b does not change characteristics.

FIG. 6 illustrates a configuration of a heater layer for simultaneously joining a plurality of components. When the heater layers are connected to each other and current is collectively provided, the connected heater layers generate heat to collectively place parts located in the corresponding grooves. It can be joined.

Therefore, the conventional method of heating an external heater and placing a silicon optical bench on top of it to heat the solder through the silicon substrate portion of the silicon optical bench is to melt all the solders at the same time, so that the solder characteristics of the parts where the parts are not bonded. This change not only causes a fatal problem of changing the bonding properties and electrical properties, but also requires a large amount of time and cost since the heater needs to be heated, and there is a problem of low efficiency due to heat transfer through the silicon substrate. In this case, only the heater layer of the part requiring actual bonding is operated to melt the solder directly adhered to the heater layer, thus enabling efficient use of energy by not applying heat to the entire silicon substrate, and affecting the solder on the non-operating heater layer. It is not possible to prevent the characteristic change. Best of all, no expensive bonding equipment is required, which significantly reduces process time and costs.

As described above, the method for manufacturing a silicon optical bench of the present invention is to form a heater through a semiconductor process on an electrode of a silicon optical bench and then apply solder to the upper part, by selectively applying a current to a heater formed at a desired portion. By melting the solder to join parts, it is possible to join without expensive equipment, thereby reducing the manufacturing cost and selectively melting only the desired portion of the solder, which does not affect the non-selected solder, resulting in joint performance and electrical If the number of parts to be bonded can be improved and the number of parts to be joined is high, the current can be quickly connected by connecting all heater electrodes and applying current at once to increase the yield.

1 is a perspective view showing one type of a general silicon optical bench.

2 is a conceptual view showing a flip chip bonding method of a conventional silicon optical bench component.

3A to 3D are cross-sectional views showing a manufacturing process of an embodiment of the present invention.

Figure 4 is a plan view of one embodiment of the present invention.

5 is a plan view of another embodiment of the present invention.

Figure 6 is a plan view of another embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

40: silicon substrate 41: insulating layer

42: electrode 43: heater layer

44: solder layer

Claims (7)

Forming a groove in the component junction on the silicon substrate, and then forming an insulating layer and an electrode; Forming a heater layer having an electrode pad on the formed electrode to enable selective driving; Forming a solder layer on the heater layer that can be melted by the operation of the heater layer; And placing the component on the formed solder layer and melting the solder layer by selectively applying a current to the heater layer, thereby bonding the component. The silicon optical bench of claim 1, wherein the heater layer formed on the electrode has a meander structure to increase efficiency, and the electrode pad extends outside the groove for the convenience of selective driving. Manufacturing method. The method of claim 1, wherein the heater layer selectively connects the electrode pattern for driving the heater layer according to the position of the components to be bonded at the same time, and collectively bonding the simultaneous bonding parts by driving the connected heater layer at the same time. Method for producing a silicon optical bench, characterized in that. The method of claim 1, wherein the heater layer uses at least one of platinum, gold, copper, nickel, tungsten, molybdenum and tantalum, and is formed so that the thermal expansion coefficient of the silicon substrate and the use temperature range are similar. Silicon photobench manufacturing method. The method of claim 1, wherein the heater layer is formed using one of sputtering, two-beam deposition, physical deposition, and chemical vapor deposition. The method of claim 1, wherein the solder layer formed on the heater layer is a silicon optical bench fabrication, characterized in that using a material of at least one of the low melting temperature indium (In), gold tin (AuSn), red tin (PbSn). Way. The method of claim 1, wherein the solder layer may be formed of gold tin (AuSn) or red tin (PbSn), and may be deposited using a single target in which Au or Pb and Sn are mixed at a predetermined ratio, or each material. Method for producing a silicon optical bench, characterized in that formed by sequentially depositing or co-depositing.