JP2005106861A - High polymer optical waveguide device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce polarization-dependent loss in a high polymer optical waveguide device. <P>SOLUTION: The device has an SiO2 layer 12 as an intermediate layer on the upper face of a silicon substrate 11, and has a Y-branched high polymer optical waveguide 13 on this SiO2 layer 12. Inside the SiO2 layer 12, there is generated a stress 111A reverse to the direction of a stress 102A in the high polymer optical waveguide 13. The stress 102A inside the high polymer optical waveguide 13 is canceled by the stress 111A inside the SiO2 layer 12, with a residual stress inside the high polymer optical waveguide 13 desirably becoming zero. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polymer optical waveguide device and a manufacturing method thereof, and more particularly to a polymer optical waveguide device formed by forming an optical waveguide made of a polymer material using a lamination technique and a photolithography technique, and a manufacturing method thereof.

  The polymer optical waveguide device is manufactured using a lamination technique and a photolithography technique. In this polymer optical waveguide device, stress is likely to remain inside due to a laminated structure of polymer materials and repeated heating in the manufacturing process. When internal stress is present, polymer optical waveguide devices suffer from problems such as large polarization-dependent loss, and cracking and lifetime due to repeated environmental changes such as temperature and humidity cycles. .

  FIG. 4 shows an example of a conventional polymer optical waveguide device 1. The polymer optical waveguide device 1 has a stress relaxation layer 3 made of a silicon-based material on the upper surface of a silicon substrate 2, and has a polymer optical waveguide 4 on the stress relaxation layer 3, and the polymer optical waveguide 4 This is a structure comprising a lower clad layer 5 made of a polymer material, a core 6 made of a polymer material, and an upper clad layer 7 made of a polymer material covering the core.

Since the stress relaxation layer 3 can be deformed within a predetermined range, the lower cladding layer 5 and the upper cladding layer 7 can be distorted with the deformation of the stress relaxation layer 3. Therefore, the stress in the polymer optical waveguide 4 is reduced and relaxed as compared with the configuration in which the stress relaxation layer 3 does not exist.
JP 2001-264562 A

  Although the stress relaxation layer 3 can relieve the stress remaining in the polymer optical waveguide 4, the stress remaining in the polymer optical waveguide 4 cannot be eliminated. Therefore, it was difficult for the polymer optical waveguide device 1 of FIG. 4 to sufficiently reduce the polarization-dependent loss.

  Accordingly, an object of the present invention is to provide a polymer optical waveguide device that solves the above-described problems by canceling out residual stress in the polymer optical waveguide and a method for manufacturing the same.

Therefore, in order to solve the above problems, the present invention provides a polymer optical waveguide device having a polymer optical waveguide made of a polymer material on a substrate.
The present invention is characterized in that an intermediate layer that generates stress in a direction opposite to the stress generated in the polymer optical waveguide is provided between the upper surface of the substrate and the polymer optical waveguide.

  As described above, according to the present invention, the intermediate layer that generates stress in the direction opposite to the stress generated in the polymer optical waveguide is provided between the upper surface of the substrate and the polymer optical waveguide. The stress generated in the molecular optical waveguide is offset by the stress generated in the intermediate layer, and the stress in the polymer optical waveguide is reduced, preferably zero, so that the polarization-dependent loss can be sufficiently reduced. In addition, even in a situation where environmental changes are repeated, such as a temperature and humidity cycle, cracks are less likely to occur and the life can be extended.

  Next, an embodiment of the present invention will be described.

  FIG. 1 shows a Y-branched polymer optical waveguide device 10 according to a first embodiment of the present invention. z1-z2 is the longitudinal direction, x1-x2 is the width direction, and y1-y2 is the thickness direction. The Y-branched polymer optical waveguide device 10 has a SiO 2 layer 12 that is an inorganic oxide having a thickness t as an intermediate layer on the upper surface of a long silicon substrate 11. The polymer optical waveguide 13 includes a molecular optical waveguide 13, and the polymer optical waveguide 13 includes a lower cladding layer 14, a Y branch core 15, and an upper cladding layer 16 that covers the Y branch core. The lower cladding layer 14, the upper cladding layer 16, and the core 15 are made of, for example, a fluorinated polyimide resin. The refractive index of the fluorinated polyimide resin of the core 15 is higher than the refractive index of the fluorinated polyimide resin of the lower cladding layer 14 and the upper cladding layer 16. The SiO 2 layer 12 is in close contact with the silicon substrate 11, and the lower cladding layer 14 is in close contact with the SiO 2 layer 12. The SiO2 layer 12, the lower clad layer 14, and the upper clad layer 16 are integral.

  As shown in FIGS. 2A to 2E, the Y-branched polymer optical waveguide device 10 is a matrix in which a large number of branched optical waveguides are formed on a wafer-like silicon substrate 25 using a lamination technique and a photolithography technique. It is manufactured by scribing a wafer-like silicon substrate.

  In the SiO2 layer forming step 20, as shown in FIG. 2B, the SiO2 layer 12 is formed by laminating SiO2 over the entire upper surface of the wafer-like silicon substrate 25 by sputtering. As sputtering conditions, a target having a diameter of 3 inches is used, the input power is 300 W, and the argon gas pressure is 0.3 Pa.

  In the polymer optical waveguide process 21, as shown in FIG. 2C, first, a fluorinated polyimide resin is spin-coated on the SiO 2 layer 12, and the fluorinated polyimide resin is cured by baking, so that a lower cladding is formed on the entire surface. The layer 14 is formed, and then the fluorinated polyimide resin is spin-coated on the lower clad layer 14, the fluorinated polyimide resin is cured by baking, and the Y-shaped core 15 is matrixed by photolithography and RIE etching. Finally, the fluorinated polyimide resin is spin-coated, and the fluorinated polyimide resin is cured by baking to form the upper clad layer 16 on the entire surface. As a result, the polymer optical waveguides 13 are formed in a matrix.

  In the scribe step 22, as shown in FIG. 2D, the wafer-like silicon substrate 25 is scribed in a matrix. As a result, the Y-branched polymer optical waveguide device 10 is cut out as shown in FIG.

  Next, the operation of the SiO2 layer 12 will be described with reference to FIG.

  As shown in FIGS. 3C and 3D, a fluorinated polyimide resin, which is a material of the lower cladding layer 14 and the upper cladding layer 16, is spin-coated on the entire surface of the silicon substrate 100, and the fluorinated polyimide resin is applied by baking. When cured to form the fluorinated polyimide resin layer 101, the fluorinated polyimide resin layer 101 tends to shrink in a state of being in close contact with the silicon substrate 100 and restrained by the silicon substrate 100, and the fluorinated polyimide resin layer 101 has an arrow. A stress in the direction of contraction indicated by 102 is generated, and the silicon substrate 100 is pulled in a direction to prevent it. For this reason, the fluorinated polyimide resin layer 101 is deformed inside.

  On the other hand, as shown in FIGS. 3A and 3B, when the SiO 2 layer 110 is formed on the entire surface of the silicon substrate 100 by sputtering under appropriate conditions, the SiO 2 layer 110 is brought into close contact with the silicon substrate 100 to form the silicon substrate. In the state of being constrained by 100, the SiO 2 layer 110 is expanded so as to expand in a direction to be expanded, and the silicon substrate 100 is pulled in a direction to prevent it. For this reason, the SiO2 layer 110 is deformed with the outside. The stress of the SiO 2 layer 110 is in a direction opposite to the stress in the fluorinated polyimide resin layer 101 and is a direction that cancels out the stress in the fluorinated polyimide resin layer 101. Here, when the thickness of the SiO2 layer 110 is increased, the stress in the SiO2 layer 110 increases. Therefore, when the thickness of the SiO 2 layer 110 is appropriately determined, the magnitude of stress in the SiO 2 layer 110 can be made equal to the magnitude of stress in the fluorinated polyimide resin layer 101.

  As shown in FIG. 3E, a fluorinated polyimide resin layer 101 is formed by spin-coating and baking a fluorinated polyimide resin on an SiO2 layer 110 having an appropriate thickness on a silicon substrate 100 to form a fluorinated polyimide resin. The stress in the direction of shrinkage indicated by the arrow 102 in the layer 101 is canceled by the stress in the direction of spreading indicated by the arrow 111 in the SiO 2 layer 110, and the internal stress of the fluorinated polyimide resin layer 101 is zero. Come to be.

  In FIG. 1, the thickness t of the SiO2 layer 12 is determined so that the magnitude of the stress 111A in the SiO2 layer 12 is equal to the magnitude of the stress 102A in the polymer optical waveguide 13. Therefore, the stress 102 </ b> A in the polymer optical waveguide 13 is desirably canceled by the stress 111 </ b> A in the SiO 2 layer 12, and no stress remains in the polymer optical waveguide 13. Even if it is not completely canceled out, the residual stress in the polymer optical waveguide 13 is smaller than that in the prior art.

  As a result, the polymer optical waveguide device 10 of FIG. 1 has good optical characteristics with reduced polarization-dependent loss compared to the prior art. In addition, the polymer optical waveguide device 10 of FIG. 1 has a long life as compared with the conventional case, even if environmental changes such as a temperature and humidity cycle are repeated, cracks are less likely to occur.

  Note that SiO2 is an inorganic oxide and has an advantage that the film thickness can be easily controlled as compared with an organic substance.

  Further, instead of the SiO2 layer 12, it is possible to utilize a layer using inorganic substance such as DLC (Diamond-Like-Carbon), SiC, inorganic nitride Si3N4, or inorganic fluoride. An effect is obtained.

  Furthermore, an organic material layer can be used instead of the SiO 2 layer 12.

  The intermediate layer can also be formed by a vacuum deposition method, a CVD method, or the like.

  Further, by appropriately selecting the lower cladding layer 14, a structure in which the lower cladding layer serves as the intermediate layer can be achieved.

It is a figure which shows the Y branch polymer optical waveguide device which becomes Example 1 of this invention. It is a figure explaining the manufacturing method of the Y branch polymer optical waveguide device of FIG. It is a figure for demonstrating the role of a SiO2 layer. It is a figure which shows the conventional polymer optical waveguide device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Y branch polymer optical waveguide device 11 Silicon substrate 12 SiO2 layer 13 Y branch polymer optical waveguide 14 Lower clad layer 15 Y branch core 16 Upper clad layer

Claims (4)

In a polymer optical waveguide device having a polymer optical waveguide made of a polymer material on a substrate,
A polymer optical waveguide comprising an intermediate layer that generates stress in a direction opposite to the stress generated in the polymer optical waveguide between the upper surface of the substrate and the polymer optical waveguide device. A polymer optical waveguide device having an optical waveguide comprising a lower clad layer made of a polymer material, a core made of the polymer material on the lower clad layer, and an upper clad layer made of a polymer material covering the core on the substrate In
A polymer comprising an intermediate layer that generates stress in a direction opposite to the stress generated in the lower clad layer and the upper clad layer between the upper surface of the substrate and the lower clad layer Optical waveguide device. The polymer optical waveguide device according to claim 1 or 2,
The polymer optical waveguide device, wherein the intermediate layer is an inorganic oxide, an inorganic nitride, or an inorganic fluoride. A large number of optical waveguides are formed on a wafer-like substrate by using a lamination technique and a photolithography technique, and finally a lower clad layer made of a polymer material and the lower clad are formed on the substrate by scribing the wafer-like substrate. In a method of manufacturing a polymer optical waveguide element having an optical waveguide comprising a polymer material core on a layer and a polymer material upper clad layer covering the core,
Before forming the lower cladding layer on the wafer-like substrate, the method includes a step of forming an intermediate layer that generates stress in a direction opposite to the stress generated in the lower cladding layer and the upper cladding layer. A method for producing a polymer optical waveguide device.

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