JP2003279777A - Manufacturing method of light guide device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a light guide device that can accurately position a dicing. <P>SOLUTION: In the manufacturing method of the light guide device, V-shaped grooves and positioning marks are formed on a substrate, and diced by utilizing the positioning marks. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical waveguide device. 2. Description of the Related Art With the recent spread of personal computers and the Internet, the demand for information transmission has been rapidly increasing. For this reason, it is desired that optical transmission with a high transmission speed be spread to terminal information processing devices such as personal computers. To achieve this, it is necessary to manufacture high-performance optical waveguides for optical interconnection at low cost and in large quantities. As a material of the optical waveguide, an inorganic material such as glass and a semiconductor material, and a resin are known. When an optical waveguide is manufactured using a resin, the film formation process can be performed at atmospheric pressure by coating and heating, and thus there is an advantage that the apparatus and the process are simple. Various resins are known as the resin constituting the optical waveguide and the cladding layer, but polyimide having a high glass transition temperature (Tg) and excellent heat resistance is particularly expected. When the optical waveguide and the cladding layer are formed of polyimide, long-term reliability can be expected, and it can withstand soldering. An optical device made of a resin, for example, an optical waveguide device, is generally provided with a V-groove for mounting an optical fiber on a substrate such as a silicon wafer, and further comprises a resin-made lower cladding layer and an optical waveguide. And the upper cladding layer,
Further, for example, a light emitting element (LD) is formed by mounting a light receiving element (PD) on a substrate. For example, on a substrate such as a silicon wafer, an optical element such as an optical waveguide, a large number of optical waveguide device units having a light emitting element and a light receiving element are arrayed vertically and horizontally, a dicing tape is attached to the back surface of the substrate, and a blade is attached. To separate into individual optical devices. Thereby, a large number of optical waveguide devices can be mass-produced. [0005] Normally, in the above dicing, the positioning of the dicing is performed with reference to the deposited film or the like of the LD mounting portion. However, as described above, in the step of forming the optical waveguide, after forming the V-groove for mounting the optical fiber, the lower clad layer, the optical waveguide, and the upper clad layer are laminated, and further thereon, the light-emitting element and the like are mounted. There are a number of steps, such as forming electrodes. Therefore, when the positioning of dicing is performed with reference to the deposited film (electrode) formed in the final step or a step close to the final step, there is a problem that positioning accuracy is reduced and reliability is lacking. Although it is possible to use a deposited film (electrode) formed directly on the substrate as a reference,
The thickness of the deposited film is usually 2 to 3 μm, and the positioning accuracy is low and sufficient cutting position accuracy cannot be obtained based on the top (upper side) or the bottom (lower side) of the film edge. There's a problem. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method of manufacturing an optical waveguide device capable of accurately performing dicing positioning. SUMMARY OF THE INVENTION The present invention provides a method for manufacturing an optical waveguide device, comprising forming a V-groove and a positioning mark on a substrate, and dicing using the positioning mark. Things. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an optical waveguide device 100 according to an embodiment of the present invention will be described with reference to FIGS. The optical waveguide device 100 has, on a silicon single crystal substrate 1, a region where the optical waveguide laminate 10 is mounted, a region 20 where the V-groove 21 is disposed, and an electrode 7 for mounting an optical element. Region 30. The optical waveguide laminate 10 includes the optical waveguide 4, and in the present embodiment, the optical waveguide 4 is made of a polyimide resin. The structure of the optical waveguide laminate 10 will be further described. A silicon dioxide layer 2 for protecting the substrate 1 and adjusting the refractive index is provided on the upper surface of the substrate 1, and the optical waveguide laminate 10 is formed on the silicon dioxide layer 2.
The optical waveguide laminate 10 includes an organic zirconium compound layer 22, a fluorine-free resin layer 23, a lower cladding layer 3, which are sequentially laminated on the silicon dioxide layer 2 as shown in more detail in FIG. The optical waveguide includes an optical waveguide, an upper cladding layer in which the optical waveguide is embedded, a protective layer, and an electrode. The lower cladding layer 3, the optical waveguide 4, and the upper cladding layer 5 are all formed of a polyimide resin containing fluorine. The organic zirconium compound layer 2
2 and the fluorine-free resin layer 23 are arranged to enhance the adhesion between the substrate 1 and the lower cladding layer 3. Lower cladding layer 3 and upper cladding layer 5
Are made of a first polyimide resin film. The thickness of the lower cladding layer 3 is about 6 μm, and the thickness of the upper cladding layer 5 is about 10 μm immediately above the optical waveguide 4 and about 15 μm in other portions. The optical waveguide 4 is made of a second polyimide resin film and has a thickness of about 6.5 μm. Protective layer 9
Is a third polyimide resin film, the thickness of which is about 5 μm at the end remote from the optical waveguide 4. As the compound constituting the organic zirconium compound layer 22, various compounds can be used. Here, tributoxyacetylacetonate zirconium is used. Organic zirconium compound layer 22
It is particularly desirable that the film thickness be within a range of 50 Å to 200 Å.
It is formed uniformly so as to fall within the range of 0 Å to 150 Å. this is,
If the thickness is less than 50 angstroms, the effect of improving the adhesiveness cannot be exhibited, and the lower clad layer 3 may be peeled off from the substrate 1. When the film thickness is 200
If the thickness exceeds angstrom, the film becomes brittle. The range of 50 Å to 200 Å substantially corresponds to a molecular layer (overlap of molecules) of the organic zirconium compound of 5 to 20 molecular layers. The resin layer 23 containing no fluorine is
This is the third polyimide resin layer. Its film thickness is about 0.2
3 μm. V-groove 21 arranged in region 20 on substrate 1
Is for mounting an optical fiber. V groove 21
Is designed to have a depth and width such that the optical fiber is aligned with the optical waveguide 4 when an optical fiber having a predetermined diameter is mounted. Therefore, for example, the electrode 107
When the light emitting element is mounted thereon, the light emitted from the light emitting element is reflected by the reflecting element inserted into the cut 27 and enters the optical waveguide 4, propagates the light, and exits from the optical waveguide 4. Then, the light is incident on the optical fiber mounted in the V-groove 21 with high efficiency. In addition, when a light receiving element is mounted on the electrode 7, the light propagating through the optical fiber enters the optical waveguide 4 with high efficiency when emitted from the optical fiber, propagates the light, and is transmitted to the light receiving element. The light is emitted toward the light receiving element. In the method of the present invention, first, a V-groove 21 and a positioning mark 31 are formed on a substrate 1. The V-groove 21 is for mounting an optical fiber, and one V-groove is usually formed in the area 20 per unit of the optical waveguide device.
The positioning mark 31 is used to determine the position when the optical waveguide device is cut into each unit by dicing, and is used to determine the position of the region 20 or 30 of the substrate 1 before dicing.
In addition, at least two for dicing direction and positioning
At least one positioning mark is formed for positioning in a direction perpendicular to this direction, that is, at least three positioning marks in total. Normally, it is desirable to form at least one horizontal and one vertical positioning mark 31 on each unit of the optical waveguide device. Positioning mark 3
The shape, size, formation position, etc. of 1 are not particularly limited,
Since the blade width of the dicing blade is usually 20 to 150 μm, the size of the positioning mark 31 is preferably 20 to 150 μm, and the position is on or near the line cut by dicing, for example, from the cutting line. It is desirable to be within 300 μm. In addition, the positioning mark 31
Is desirably a square or a rectangle having sides parallel to the V-groove from the viewpoint of easy formation and easy positioning. The formation of the positioning mark 31 is desirably performed simultaneously with the formation of the V-groove 21. That is, for example,
A resist is applied on the silicon substrate 1, exposed and developed through a mask having a pattern of the V groove 21 and the positioning mark 31, and the exposed region corresponding to the V groove 21 and the positioning mark 31 is anisotropically etched. After that, the resist is peeled off, and the V groove 21 and the positioning mark 31 are formed.
Next, the substrate 1 on which the V groove 21 and the positioning mark 31 are formed
The lower clad layer 3, the optical waveguide 4 and the upper clad layer 5 are sequentially laminated thereon, a protective layer 9 is provided if necessary, an electrode 107 is formed thereon, and an electrode 7 is formed on the region 30 and diced. After the optical waveguide device has been cut out, the light emitting element (LD) is mounted on the electrode 107 and the light receiving element (PD) is mounted on the electrode 7, thereby producing the optical waveguide device. The V-groove 21 has a depth of about 100 formed by anisotropically etching the silicon single crystal substrate 1.
The groove is μm, and the cross section is V-shaped. The positioning mark 31 is a recess formed by anisotropic etching at the same time as the formation of the V-groove 21, and its planar shape is preferably a square or a rectangle having two sides parallel to the V-groove as described above. In the case of a square, the concave portion formed by anisotropic etching has an inverted pyramid shape. At the boundary between the region 20 where the V-groove 21 is arranged and the optical waveguide laminate 10, as shown in FIGS.
There is a notch 25 formed when cutting the end face of. Similarly, the region 30 of the electrode 7 and the optical waveguide laminate 1
A notch 26 also exists at the boundary with 0. EXAMPLE The method of manufacturing an optical waveguide device according to the present invention will be described in more detail. Here, the substrate 1 has a diameter of about 12.
A 7 cm silicon wafer is prepared, and a large number of the structures shown in FIG. 1 are arranged on the substrate 1 in a matrix, and are separated by dicing in a later step to obtain individual optical waveguide devices 10.
Separate to zero. Thereby, many optical waveguide devices 100 of FIG. 1 can be mass-produced. Therefore, film formation, patterning, and the like are performed at once on the entire wafer-shaped substrate 1. (1) Step of Forming V Groove 21 for Mounting Optical Fiber and Positioning Mark 31 on Substrate 1 First, a silicon dioxide layer 2 is formed on the entire upper surface of wafer-like substrate 1.
Is formed by a thermal oxidation method, a vapor deposition method or the like, and then the V groove 21 and the positioning mark 31 are formed by photolithography and wet etching utilizing the anisotropy of silicon single crystal.
Are arranged and formed as shown in FIG. 5 and FIG. In this embodiment, two positioning marks having a length of 50 μm and a width of 12 μm are formed at an interval of 28 μm per unit of the optical waveguide device. In this embodiment, the position at which the positioning mark is formed is the intersection of the horizontal cutting line 41 and the vertical cutting line 51, but is not limited to this. Next, an organic zirconium compound layer 22 is formed on the entire wafer-like substrate 1 shown in FIG. First, an organic zirconium compound solution is applied to the entire substrate 1 by spin coating, and the obtained coating film is dried by heating at 160 ° C. for about 5 minutes to form an organic zirconium compound layer 22. As the organic zirconium compound solution, for example,
A solution prepared by dissolving zirconium tributoxyacetylacetonate in butanol to prepare a 1% by weight solution is used. Next, a composition for forming a resin layer containing no fluorine is spin-coated on the organic zirconium compound layer 22, and the obtained coating film is heated to evaporate the solvent, and further heated to be cured. Thereby, the resin layer 23 containing no fluorine is formed. The spin coating conditions are controlled so that the thickness of the fluorine-free resin layer 23 is 0.23 μm. Next, a portion of the upper surface of the wafer-like substrate 1 which is to be the regions 20 and 30 where the optical waveguide laminate 10 is not arranged in the completed optical waveguide device, the fluorine-free resin layer 23 and the organic zirconium The compound layer 22 is removed. Since the optical waveguide devices are arrayed vertically and horizontally on the wafer-like substrate 1, the regions 20 and 30 on the upper surface of the wafer-like substrate 1 are, as shown in FIG. It is a strip-shaped part on both sides. The resin layer 23 containing no fluorine and the organic zirconium compound layer 22 are removed from the band-like portion. Since the lower clad layer 3 is easily peeled off from the substrate 1 in this band-like portion, The optical waveguide laminated body 10 can be stripped and removed from the regions 20 and 30 of the first region. A method for removing the fluorine-free resin layer 23 and the organic zirconium compound layer 22 from the regions 20 and 30 on the substrate 1 will be specifically described. First, a resist solution is spin-coated on the entire surface of the wafer-like substrate 1,
By drying at 00 ° C., a resist film is formed. Thereafter, the image of the photomask is exposed with a mercury lamp. The photomask is formed such that the resist film remains only in the portion where the optical waveguide laminate 10 is to be formed. After that, the resist film is developed. Thus, not only the resist film but also the fluorine-free resin layer 23 is wet-etched, and both of them can be substantially removed. At this time, V
Since the groove 21 and the positioning mark 31 have a concave shape, the resist film and the fluorine-free resin layer 23 partially remain at the bottom. So, in this state,
Exposure is performed using the photomask described above, and development is performed. Thus, the resist film and the fluorine-free resin layer 23 remaining in the V-groove 21 and the positioning mark 31 can be completely removed. This method has an advantage that the fluorine-free resin layer 23 can be completely removed from the V-groove 21 and the positioning mark 31 by a simple process of repeating exposure and development of the resist film. After that, by wet etching using hydrofluoric acid or reactive ion etching,
The organic zirconium compound layer 22 is removed. Since the organic zirconium compound layer 22 is very thin,
The layer inside 1 and the positioning mark 31 can also be removed by wet etching or reactive ion etching. Finally, the resist film is removed. (2) Step of Forming Lower Cladding Layer 3 on Substrate 1 Next, the above-described first polyimide resin film forming composition (ie, lower cladding layer 3 formation) is formed on the entire upper surface of wafer-like substrate 1. Is spin-coated to form a material solution film. Then, it is 30 minutes at 100 ° C in a dryer, and then 2
The solvent is evaporated by heating at 00 ° C. for 30 minutes and then cured by heating at 370 ° C. for 60 minutes to form the lower cladding layer 3 having a thickness of 6 μm. (3) Optical waveguide layer 4 on lower cladding layer 3
On the lower cladding layer 3, the above-mentioned second polyimide resin film forming composition for an optical waveguide layer is spin-coated to form a material solution film. Then, at 100 ° C in a drier
The solvent is evaporated by heating at 0 ° C. for 30 minutes and then at 200 ° C. for 30 minutes, and then cured by heating at 350 ° C. for 60 minutes to obtain a light guide 4 having a thickness of 6.5 μm.
m of the second polyimide resin film is formed. (4) Step of Forming Optical Waveguide 4 Next, a second polyimide resin film (namely, optical waveguide layer 4)
A silicon-containing resist film (generally, about 1 μm thick) is provided thereon, and the resist film is exposed and developed through a photomask having a desired optical waveguide pattern to form a resist pattern. Exposure is carried out using ultraviolet rays, usually 30
It may be performed for about seconds to 120 seconds. The development is performed sufficiently by spraying an alkaline developer at room temperature (about 23 ° C.) for about 90 seconds. Using the resist pattern as an etching mask, the optical waveguide layer is etched to form a desired optical waveguide 4. The etching is performed by reactive ion etching (O ₂ -RIE) using oxygen ions using the resist pattern as an etching mask. Thereby, as shown in FIG. 6, a number of optical waveguide devices can be arranged on the substrate 1 and formed at one time. (5) Step of Forming Upper Cladding Layer 5 Next, the optical waveguide 4 and the lower cladding layer 3 are covered with
The first composition for forming a polyimide resin film is spin-coated. The obtained material solution film is heated in a dryer at 100 ° C. for 30 minutes, then at 200 ° C. for 30 minutes to evaporate the solvent in the material solution film, and then heated at 350 ° C. for 60 minutes to form the first polyimide. An upper clad layer 5 of a resin film is formed. (6) Step of Forming Protective Layer 9 Furthermore, a fluorine-free composition for forming a polyimide resin film is spin-coated on the upper surface of the upper cladding layer 5 and dried at 100 ° C. for 30 minutes at 200 ° C. in a drier. For 30 minutes to evaporate the solvent, and then heated at 350 ° C. for 60 minutes to obtain a fluorine-free polyimide resin having an approximately flat upper surface and a thickness of about 5 μm at an end portion away from the optical waveguide 4. A protective layer 9 of the film is obtained. (7) Step of Exposing Part of the Substrate 1 Next, since the layers from the lower cladding layer 3 to the protective layer 9 are also arranged in the unnecessary regions 20 and 30, these layers are peeled off. To remove. That is, as shown in FIG. 6, cuts 25 and 26 are made by dicing at the boundary between the region 20 and the optical waveguide laminate 10 and at the boundary between the optical waveguide laminate 10 and the region 30 to protect the lower cladding layer 3. Cut each layer up to layer 9. At this time, the depth of the cut by the dicing is set so that the optical waveguide laminate 10 is cut but the substrate 1 is not cut. Since the organic zirconium compound layer 22 and the fluorine-free resin layer 23 are removed from the upper surface of the substrate 1 in the regions 20 and 30 in the previous step, the regions 20 and 3
At 0, the adhesion between the lower cladding layer 3 and the substrate 1 is small.
Therefore, each layer between the lower cladding layer 3 and the protective layer 9 mounted on the region 20 and the region 30 can be easily stripped from the wafer-like substrate 1 in a strip shape by making the cuts 25 and 26. Can be. As a result, FIG.
In the wafer-like substrate 1, the substrate upper surface (silicon dioxide layer) is exposed in the regions 20 and 30. (8) Process for Forming Electrodes 7 and 107 On the regions 20 and 30 of the substrate 1 and on the upper cladding layer 5
Is spin-coated with a positive type novolak phenol resin to form a resist film. Next, the electrodes 7 and 1
The resist film is exposed and developed through a mask having a pattern 07, and the patterns of the electrodes 7 and 107 are exposed. Next, a Cr layer is formed to a thickness of 0.05 μm, an Au layer is further formed to a thickness of 0.5 μm, and the resist film is peeled off to form the region 30 of the substrate 1 and the upper clad layer 5.
The electrodes 7 and 107 are respectively formed on the surface of the substrate. In addition,
Here, an electrode having a two-layer structure in which an Au layer is overlaid on a Cr layer is formed as an electrode, but the present invention is not limited to this. Other electrodes, for example, a Ti layer, a Pt layer, and an Au layer are sequentially formed. A stacked three-layer electrode or the like may be used. In addition, although an electron beam evaporation method is employed as a film formation method, the invention is not limited to this method, and a vacuum evaporation method using resistance heating, a sputtering method, or the like may be used. Also, the electrodes 7 and 107
Is not limited to the lift-off method of forming a resist film in advance and forming the electrodes 7 and 107 over the entire surface and then removing the resist film.
May be formed on the entire surface, a resist film is formed, and unnecessary regions are processed and removed by ion milling or reactive dry etching to form the electrodes 7 and 107 in desired regions. (9) Dicing Step Next, a cut 27 is made in the optical waveguide laminate 10 by dicing while keeping the wafer-like substrate 1. The direction of the cut is 30 degrees with respect to the normal line of the substrate 1. 20 thickness
If a dicing blade of μm is used, a high-precision cut having a width of 23 μm can be obtained, and this cut surface is optically smooth, and polishing or the like for finishing is not required. By inserting an optical element such as a reflecting member into the cut 27, the direction of light from the light emitting element can be changed and emitted to the optical waveguide 4. Next, as shown in FIGS. 7 (a) and 7 (b), the wafer-like substrate 1 is cut by dicing to be cut into strips, and further as shown in FIGS. 7 (c) and 7 (d). 1 is cut out into individual optical waveguide devices 100 by dicing, and the optical waveguide device 100 is completed. The procedure of the dicing step for cutting the substrate 1 is not limited to this procedure, and the optical waveguide device 100 is diced vertically and horizontally in the step of FIG. It is also possible to form Here, when dicing was performed with reference to the positioning marks 31 formed on the substrate 1, the dicing accuracy 3σ was 3.96 μm. On the other hand, the electrode 7
When dicing is performed on the basis of
Was 6.61 μm. Therefore, it is understood that the dicing accuracy is remarkably improved by performing the dicing based on the positioning mark 31 formed on the substrate 1 of the present invention. In the optical waveguide device of the present embodiment, the optical waveguide 4 has a linear shape, but the optical waveguide 4 of the optical waveguide laminate 10 has a linear shape in accordance with the function required as the optical waveguide device. Not only that, but also a desired shape such as a y-branch or an x-shape can be obtained. It is also possible to adopt a configuration having a plurality of V-grooves 21 and a plurality of electrodes 7 and 107 according to the shape of the optical waveguide. The optical waveguide device 100 manufactured in this embodiment has a high Tg and excellent heat resistance because all layers from the lower cladding layer 3 to the upper cladding layer 5 are formed of polyimide resin. ing. Therefore, the optical waveguide device of the present embodiment can maintain the propagation characteristics even at a high temperature. Further, since the polyimide resin can withstand a high-temperature process such as soldering, it is possible to solder another optical waveguide device, an electric circuit element, or a light emitting element on the optical waveguide device. In the present invention, the term “optical waveguide device” means an inorganic material such as glass or quartz; a semiconductor such as silicon, gallium arsenide, aluminum or titanium; a metal material; a polymer material such as polyimide or polyamide; Or, using a material obtained by compounding these materials, an optical waveguide is provided on these substrates, and further,
Optical multiplexers, optical demultiplexers, optical attenuators, optical diffractors, optical amplifiers,
It refers to an optical interferometer, an optical filter, an optical switch, a wavelength converter, a light-emitting element, a light-receiving element, or a combination thereof formed. On the above substrate, a light emitting diode, a semiconductor device such as a photodiode or a metal film may be formed, and a silicon dioxide film may be formed on the substrate as described above to further protect the substrate and adjust the refractive index. Alternatively, a film of silicon nitride, aluminum oxide, aluminum nitride, tantalum oxide, or the like may be formed. According to the method for manufacturing an optical waveguide device of the present invention, dicing is performed by using the positioning marks formed on the substrate, so that the dicing accuracy is improved. Therefore, the optical waveguide device 10 manufactured by the manufacturing method of the present invention can be used.
By using 0 to manufacture an optical communication device, alignment between the optical fiber and the optical waveguide 4 is easy, and a high-performance optical communication device with high coupling efficiency can be manufactured at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a schematic optical waveguide device 100 according to an embodiment of the present invention. FIG. 2 is a sectional view of the optical waveguide device of FIG. 1 taken along the line AA '; FIG. 3 is a sectional view of the optical waveguide device of FIG. 1 taken along line BB '; FIG. 4 is a plan view of the optical waveguide device of FIG. 1; FIG. 5 is a plan view of a wafer-like substrate 1 for describing a method of manufacturing an optical waveguide device according to one embodiment of the present invention. FIG. 6 is a plan view of a wafer-like substrate 1 for describing a method of manufacturing an optical waveguide device according to one embodiment of the present invention. FIGS. 7A to 7D are explanatory views showing steps of cutting out a wafer-like substrate 1 in the method for manufacturing an optical waveguide device according to one embodiment of the present invention. FIG. 8 is a partially enlarged view of FIG.
It is an explanatory view showing a formation position. [Description of Signs] 1: silicon substrate, 2: silicon dioxide layer, 3: lower cladding layer, 4: optical waveguide, 5: upper cladding layer, 7: electrode,
9: protective layer, 10: optical waveguide laminate, 20: optical fiber mounting area, 21: V groove, 22: organic zirconium compound layer, 23: fluorine-free resin layer, 25, 26, 2
7: notch, 30: electrode mounting area, 31: positioning mark, 107: electrode

Continuation of front page    (72) Inventor Toshihiro Kuroda             48 Wadai, Tsukuba, Ibaraki Prefecture Hitachi Chemical Co., Ltd.             Company Opto Business Promotion Department F-term (reference) 2H047 KA04 MA05 PA02 PA21 PA24                       PA26 PA28 QA02 QA04 QA05

Claims (1)

Claims: 1. A V-groove and a positioning mark are formed on a substrate,
A method for manufacturing an optical waveguide device, wherein dicing is performed using the positioning mark.