Optical waveguide device, optical waveguide manufacturing apparatus and manufacturing method

Abstract

In the present invention, manufacturing processing for manufacturing an optical waveguide has, in a step for manufacturing an optical waveguide, a step for forming a processing information element that corresponds to a waveguide constituent element of the optical waveguide in the same step as the waveguide constituent element, and forming a marker that includes the processing information element.

Description

[Technical Field]

[0001] The present invention relates to an optical waveguide device and an apparatus and method for manufacturing an optical waveguide, and more particularly to a processing technique for elements constituting an optical waveguide. [Background technology]

[0002] Optical devices such as semiconductor lasers, photodiodes, optical wavelength multiplexers / demultiplexers, and optical switches are configured with optical integrated circuits. In optical fiber communications, optical fiber, which serves as a transmission medium, and optical integrated circuits in these optical devices for processing optical signals, play important roles (see, for example, Non-Patent Document 1). Semiconductor lasers function as optical oscillators to generate lightwaves for superimposing signals, and photodiodes function as elements that convert the intensity of optical signals into electrical signals. Optical wavelength multiplexers / demultiplexers, typified by arrayed waveguide gratings, are used in wavelength division multiplexing communications as elements that multiplex and demultiplex different wavelengths of light (see, for example, Non-Patent Document 2). Optical switches, as elements that route optical paths, play an important role in reconfigurable optical add / drop multiplexing (ROADM) systems. These optical integrated circuits are generally configured with optical waveguides formed on a substrate. An optical waveguide consists of a core through which optical signals propagate and a cladding that surrounds it. Semiconductor lasers and photodiodes are made of semiconductor materials such as InP, while arrayed waveguide gratings and optical switches are made of optical waveguide materials, mainly silica glass.

[0003] FIG. 1 is a block diagram illustrating a method for manufacturing an optical waveguide. A silica-based planar lightwave circuit made of silica-based glass will be described as an example. First, in the lower clad deposition process 1, a glass film that will become the lower clad 12 is deposited on a silicon substrate (wafer) 11. The lower clad 12 is made of SiO2 doped with P2O5 or B2O3, for example, deposited by flame hydrolysis deposition (FHD). The soot-like glass particles deposited by the FHD process are heated at a high temperature of 1000°C or higher to obtain the transparent lower clad 12. Next, in the core deposition process 2, a thin-film glass that will become the core 13, having a refractive index higher than that of the lower clad 12, is deposited using the same FHD process. The desired refractive index can be obtained by adding GeO2 to the SiO2 during the deposition of the core 13. As in the lower clad deposition process 1, the transparent core 13 is formed by heating at a high temperature of 1000°C or higher. It should be noted that the formation of the lower clad and core is not limited to the FHD process, and other well-known methods may also be used.

[0004] In a photoresist film formation process 3, a photoresist film 14 is formed on a substrate by spin coating. Next, in a circuit pattern exposure process 4, the photoresist film is irradiated with UV light 16 through a photomask 15 to expose a circuit pattern corresponding to the mask pattern. Then, in a photoresist development process 5, the circuit pattern of the photoresist film is developed to obtain a photoresist pattern 17.

[0005] Next, in an etching step 6, the photoresist pattern 17 is transferred to the core by reactive ion etching (RIE), to obtain a core pattern 18. Then, in a resist removal step 7, the photoresist remaining on the core is removed by ashing. Finally, in an upper cladding deposition step 8, an upper cladding 19 is deposited by the same method as in the lower cladding deposition step 1.

[0006] The optical waveguides obtained through the above manufacturing process are inspected for various characteristics, including optical properties. Conventionally, to reflect these inspection results in the manufacturing process, manufacturing conditions that reflect the inspection results are set for each process after the entire series of processes are completed. This method has the problem that manufacturing errors accumulate in each process, resulting in lower accuracy of inspection results in later processes. On the other hand, by resetting the manufacturing conditions for a process or adjusting the manufacturing conditions for a subsequent process based on the inspection results obtained at the end of a process, it is possible to suppress the accumulation of manufacturing errors. However, this method requires interrupting the manufacturing process after each process, making it difficult to improve the throughput of the manufacturing process.

[0007] Therefore, if information on the processing results obtained in a certain process, such as information on the resist pattern width obtained in a photoresist development process, can be known during the development process, a process that reflects the pattern width information can be carried out in a subsequent etching process. Furthermore, if the film thickness and refractive index of the core obtained in the core deposition process can be known during the deposition process, the optical characteristics of the optical waveguide formed in the subsequent process can also be predicted. In this way, if information on the optical waveguide components obtained in a previous process can be acquired during the previous process and reflected in the processing conditions of the subsequent process or used to predict the optical characteristics obtained in the subsequent process, this is advantageous in terms of throughput of the manufacturing process. [Prior art documents] [Patent documents]

[0008] [Non-Patent Document 1] Fundamentals of Optical Waveguides 2nd edition (2010 / 8 / 4), P. 437 [Non-patent document 2] A. Himeno, K. Kato and T. Miya, "Silica-based planar lightwave circuits," in IEEE Journal of Selected Topics in Quantum Electronics, vol. 4, no. 6, pp. 913-924, Nov.-Dec. 1998, doi: 10.1109 / 2944.736076. Summary of the Invention

[0009] As described above, when obtaining information on the processing results (processing information) in a previous process, it is conceivable to image the entire waveguide path, such as the shape of the waveguide formed in the previous process. However, it is relatively difficult to image the entire path along which the optical signal propagates at high magnification and measure the shape. In order to obtain the detailed shape of the waveguide, high-magnification imaging is required. However, with this high-magnification imaging, the imaging range is small, so to obtain information on a wide area, the number of imaging sessions must be increased, which reduces throughput and increases the memory capacity for storing image information.

[0010] An object of the present invention is to provide an optical waveguide device and an apparatus and method for manufacturing an optical waveguide that make it possible to acquire processing information without reducing throughput in one step of optical waveguide manufacturing.

[0011] In one aspect of the present invention, there is provided a manufacturing method for performing a plurality of steps in chronological order to manufacture an optical waveguide, the method comprising the steps of: forming a processing information element corresponding to a waveguide component of the optical waveguide in the same step as the waveguide component, and forming a marker including the processing information element; measuring, while performing the plurality of steps, the processing information element corresponding to the waveguide component formed up to an i-th step in the plurality of steps; and controlling the formation of the waveguide component in a j-th step that follows the i-th step in the chronological order based on the measurement results.

[0012] In another aspect of the present invention, a manufacturing apparatus for executing a plurality of steps in chronological order to manufacture an optical waveguide comprises: a control means for controlling the formation of a processing information element corresponding to a waveguide component of an optical waveguide in the same step as the waveguide component in the plurality of steps, and the formation of a marker including the processing information element; and a means for executing, while executing the plurality of steps, a step of measuring the processing information element corresponding to the waveguide component formed up to an i-th step in the plurality of steps, and a step of controlling the formation of the waveguide component in a j-th step chronologically subsequent to the i-th step based on the measurement result. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram showing a method for manufacturing an optical waveguide. [Figure 2] 1A to 1C are diagrams illustrating a method for manufacturing an optical waveguide according to an embodiment of the present invention. [Figure 3] FIG. 1 illustrates a generalized feedforward system according to an embodiment of the present invention. [Figure 4] 1A and 1B are diagrams illustrating the basic configuration of a waveguide pattern formed on a substrate and a marker formed together with this pattern according to a first embodiment of the present invention. [Figure 5] 10(a) and 10(b) are diagrams illustrating a marker according to another embodiment of the present invention. [Figure 6] 10 is a flowchart illustrating an example of correction using a marker in a manufacturing process of an optical waveguide according to an embodiment of the present invention. [Figure 7] 10A to 10C are diagrams illustrating an example of prediction using markers in a manufacturing process of an optical waveguide according to an embodiment of the present invention. [Figure 8] FIG. 10 is a diagram showing a marker according to a second embodiment of the present invention; [Figure 9] FIG. 10 is a diagram showing a marker according to a third embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0015] A manufacturing method according to an embodiment of the present invention measures the components or characteristics of an optical device formed in one step of the manufacturing process at that time, and adjusts or corrects the manufacturing conditions for subsequent steps based on the measured data (hereinafter, this method is referred to as a "feedforward system"). The feedforward system makes it possible to obtain desired optical characteristics for the final optical device, such as by suppressing variations in the optical characteristics of the optical device.

[0016] 2 is a diagram illustrating an example of a method for manufacturing an optical waveguide according to an embodiment of the present invention. The feedforward system performs "measurement" of components of an optical device formed in one process, and then performs "optical property estimation" based on the measurement results using optical property estimation processing 21. Then, based on the estimation results, "control" of subsequent processes is performed using process control processing 22. For example, the refractive index and thickness of the lower cladding film formed in the lower cladding deposition process 1 and the refractive index and thickness of the core layer deposited in the core deposition process 2 are "measured." Based on these measurement results, the final optical characteristics of a device fabricated with standard (nominal) design values ​​are estimated. Then, based on this estimation, the etching strength or time in the subsequent etching process 6 is "controlled."

[0017] Specifically, based on the measured film thickness and refractive index of the core layer and the refractive index of the cladding film, the ideal core width of the pattern for satisfying the performance required for the optical device is estimated (predicted). Then, in the etching step 6, etching is performed based on this predicted value. For example, in the case of prediction information that the waveguide width after core processing is too thick at the standard (nominal) design value and cannot satisfy the desired performance, in the etching step, correction is made to narrow the formed core width. Adjustment methods at this time include methods such as making the etching time shorter / longer or making the etching intensity weaker / stronger to make the core width wider / narrower. Furthermore, the width and step of the core in the waveguide pattern formed in the etching step 6 are "measured", and based on this measurement result, the refractive index of the upper cladding film formed in the upper cladding deposition step 8 is "controlled" to adjust the optical characteristics of the finally obtained optical waveguide.

[0018] As described above, in the feed-forward system of the present embodiment, among a plurality of steps for manufacturing an optical device, during or after a previous step, the shape, characteristics, etc. of the components of the formed optical device are measured, and based on this measurement result, the manufacturing conditions in the subsequent steps are adjusted or corrected so that the performance of the finally completed device satisfies the expected conditions.

[0019] FIG. 3 is a diagram generally showing a feed-forward system according to an embodiment of the present invention. The feed-forward system includes a manufacturing procedure of an optical device consisting of M steps, and the optical device to be manufactured is carried out in the order of step 1, step 2 ···, step i, ··· step j, ··· step M. Here, when i <j, step j is a step later in time than step i. The feed-forward system includes a measurement data processing unit 31 and a control data processing unit 32. The measurement data processing unit 31 executes the optical characteristic estimation process 21 described above with reference to FIG. 2, and the control data processing unit 32 executes the process control process 22. The measurement data processing unit 31 and the control data processing unit 32 can be in the form of a computer configured with a CPU, RAM, ROM, etc.

[0020] In FIG. 3, solid lines indicate the flow of the manufacturing process. Furthermore, dashed lines indicate measurement data obtained by "measurement" in each process, and dashed lines indicate control data for "control" of each process. In this manner, the feedforward system of this embodiment acquires measurement data from the manufacturing equipment or measurement equipment involved in the manufacturing in process i, and transfers it to the measurement data processing unit 31. Based on the measurement data, the measurement data processing unit 31 predicts the shape or characteristics of the components of the optical device formed in process i. Alternatively, based on the measurement data, the optical characteristics of the optical device finally obtained in process i may be predicted.

[0021] The predicted values ​​derived by the measurement data processing unit 31 are passed to the control data processing unit 32. The control data processing unit 32 determines the manufacturing conditions for process j, which is a subsequent process, based on the predicted values. When process j is executed, the control data processing unit 32 supplies control data for process j to be set in the manufacturing equipment according to the determined manufacturing conditions. The control data based on the previous process supplied when executing the subsequent process j may be only control data based on previous process i, or may be multiple types of control data based on several of the previous processes. Naturally, the form of the control data is determined according to conditions such as the actually configured manufacturing equipment and the object to be manufactured.

[0022] A configuration for acquiring processing information in one step of waveguide manufacturing using the above-described feedforward system will be described below.

[0023] (Basic configuration) First, a basic configuration for acquiring processing information according to an embodiment of the present invention will be described below.

[0024] Fig. 4 is a diagram for explaining the basic configuration of an embodiment of the present invention, illustrating a waveguide pattern formed on a substrate and a marker formed together with this pattern. Fig. 4 shows an AWG waveguide pattern 100 as an example of a waveguide, and a marker 200 formed together with this pattern.

[0025] As shown in FIG. 4, the AWG waveguide pattern 100 includes components that define the shape of the waveguide, such as a bent portion 101, a tapered portion 102, and a straight portion 103. The components are not limited to these, but can be determined depending on the shape of the target waveguide pattern and how the processing information obtained from the markers (described later) is used. For example, in addition to the bent portions, tapered portions, and straight portions, other components may also be used, such as intersections and directional couplers. In the example shown in FIG. 4, a marker 200 is formed in the approximate center of the AWG waveguide pattern 100 in the same process as the optical waveguide described in FIG. 1. This marker 200 is approximately square, approximately 100 μm × 100 μm in size, as shown on the right side of FIG. 4. In contrast, the waveguide pattern 100, as shown on the left side of FIG. 4, has a size of approximately several tens of mm × several tens of mm (see Non-Patent Document 2).

[0026] Marker 200 is formed by integrating elements having basically the same shape as part of the constituent elements of a waveguide. In the example shown in Fig. 4, for example, tapered portion 102 of the waveguide is shown as a constituent element of the waveguide, and this is formed as processed information element 102M in marker 200. Similarly, straight portion 103 of the waveguide is formed as straight processed information element 103M in marker 200.

[0027] In this way, by forming and imaging the marker 200, which integrates the components of the waveguide, during the manufacturing process of the waveguide, it is possible to represent the processing information of that manufacturing process. The processed shapes of the waveguide components, such as bends, tapers, intersections, and straight lines, affect the optical propagation characteristics of the waveguide. Furthermore, due to manufacturing variations during manufacturing, even if the shape is the same, the processing results may vary across the wafer surface. For this reason, by aggregating information on the processing information elements (hereinafter simply referred to as "processing information") in the marker 200 formed in the same process, corrections in subsequent processes and predictions of optical characteristics can be made based on this processing information.

[0028] The processing information elements formed in the marker 200 are basically the same as the parameter values ​​of the waveguide components in the waveguide pattern 100 to be manufactured. For example, if the component is a "straight line," the straight line in the marker 200 is formed with a width equal to the parameter "width." Similarly, if the component is a "bend," the parameters are "width" and "bend radius," if it is a "taper," the parameters are "taper rate" and "taper start and end width," if it is an "intersection," the parameters are "intersection angle," and if it is a "directional coupler," the parameters are "waveguide width" and "spacing" of the waveguide. In the marker 200, processing information elements are formed with these parameters having the same values ​​as the waveguide pattern. It goes without saying that the parameters for each waveguide component are not limited to the above example. They can be appropriately determined depending on the processing information to be acquired and its intended use.

[0029] In this embodiment, the marker 200 described above is formed and processing information is acquired from it. This allows processing information to be acquired by capturing an image of only the marker. As a result, processing information can be acquired with high throughput. If the marker of this embodiment is not used, for example, when capturing an image of the components of the entire waveguide at high resolution, there are disadvantages such as an increase in the number of images captured and an increase in the memory capacity of the captured data. As a result, in order to determine the processing state, it is necessary to observe and measure the post-processing shape across the entire wafer surface, which makes the process complicated and reduces throughput.

[0030] The size and shape of the marker 200 should be as small as possible so as not to affect the waveguide pattern. On the other hand, the entire marker must fit within the imaging field of view, and the imaging element is generally rectangular. For these reasons, it is desirable for the marker 200 to fit within a rectangular area. For example, if the chip size is 10 mm x 10 mm and the marker 200 is 1 mm x 1 mm, the imaging size required for inspection is 1 / 100th of the original size. If the marker 200 is 100 μm x 100 μm, the imaging size required for inspection is 1 / 10,000th of the original size. This indicates that the throughput when measured at the same microscope magnification is 100 times and 10,000 times greater, respectively. To improve throughput, it is desirable for the length of one side of the marker 200 to be 1 / 10th of the length of the chip, or for the marker 200 to be 1 / 100th of the chip's area. Furthermore, even if the chip size is 500 um x 500 um, if the size of the marker 200 is 100 um x 100 um, the image size required for inspection will be 1 / 25. This means that the throughput will be 25 times higher when measured at the same microscope magnification.

[0031] It should be noted that it is not necessary for all components of the waveguide to have the same parameter value for the processing information element in the marker 200. Examples of such cases will be described below.

[0032] For example, when the component is a bend, the radius of the formed waveguide pattern is large, on the order of millimeters, for example, in a silica-based waveguide, increasing the range required for imaging. In such a case, a processing information element with a smaller value for the parameter "bend radius" is formed in the marker. When acquiring the processing information element from this marker 200, processing information corresponding to the ratio of the smaller "bend radius" is acquired. Specifically, multiple waveguides with bend radii are prepared in advance according to the "bend radii" values ​​smaller than the actual bend radius of the waveguide pattern, and the resulting formation (e.g., waveguide width) is compared with the actual waveguide pattern. Then, based on the comparison results, the resulting formation (processing information) of the actual bend radius of the waveguide pattern can be extrapolated and estimated according to the ratio of the bend radii. It has been found that, as a characteristic of the "bend" portion, even if the bend radius of the marker 200 differs from the actual bend radius of the waveguide pattern, the estimated shape (processing information) of the bend portion is close to the shape of the actually formed bend portion, even if the bend radius of the marker 200 differs from the actual bend radius of the waveguide pattern. As a result, even if the radius of the waveguide pattern that is actually formed becomes large, it is possible to fit the processing information within the size of the marker 200.

[0033] As another example, only a part of a bend in a waveguide element may be formed as a processing information element in the marker 200. FIG. 5(a) is a diagram showing such a configuration. As shown in FIG. 5(a), only a part of a bend 100 in a waveguide element is formed as a processing information element 100M in the marker 200. In this way, by defining a bent portion corresponding to a part of the angle of the bend as a processing information element 100M, it is possible to fit the processing information within the size of the marker 200. That is, although a partial processing information element 100M does not allow for knowing the difference (angle dependency) depending on the positional relationship with the bent portion in the actual waveguide pattern, it is possible to estimate that the same formation result (processing information) will be obtained at other angles from the formation result of the processing information element 100M at a representative point (angle) of the processing information element 100M.

[0034] As another example, if the waveguide component is a circular arc as a type of bend, equal divisions of the arc may be formed within the marker 200 as processing information elements. FIG. 5(b) illustrates such a configuration. As shown in FIG. 5(b), the circular arc 100 of the waveguide component is divided into four equal parts, 100A, 100B, 100C, and 100D. Corresponding processing information elements 100MA, 100MB, 100MC, and 100MD are then formed within the marker 200. In this case, the orientations or angles of the processing information elements 100MA, 100MB, 100MC, and 100MD are made different. Specifically, they are arranged at equal intervals in the circumferential direction. This allows the area in which they are formed to be more compact. In this way, by equally dividing the bend into processing information elements 100M, it is possible to fit the processing information within the size of the marker 200. In other words, by interpolating the four discrete pieces of information (values) of the formation results (such as core width) for each representative point (angle) of the four processing information elements 100MA, 100MB, 100MC, and 100MD, the formation results (processing information) for the actual waveguide pattern can be estimated.

[0035] As shown in the example of FIG. 5(b), the processing information element 100M may be formed in the marker 200 at a different orientation or angle from the orientation or angle at which the waveguide component 100 is formed. In this case, the effect of so-called angle dependency is taken into consideration. That is, from information on the formation results (such as core width) of the processing information element at different angles in the marker 200, the respective angle dependencies can be calculated, and the formation results (processing information) at other angles can be estimated based on the calculation results. In particular, as long as the processing information elements are mutually orthogonal, they can be expressed for any angle. Specifically, the degree of influence in the manufacturing process may differ depending on the orientation or angle of the waveguide component on the substrate. For this reason, the following configurations can be adopted. First, when the arrangement direction of the same component in the waveguide pattern is constant, it is desirable that the processing information elements formed in the marker be formed in the same orientation. Second, it is desirable that the same component in the waveguide pattern be arranged at multiple different angles, preferably orthogonal angles, in the marker. Third, when the component is an "arc," it is desirable that the marker divide the arc at equal intervals and arrange the divided segments at different directions or angles, as explained in FIG. 5(b).

[0036] In addition, it is sometimes necessary to measure the distribution of a specific pattern in the waveguide pattern to be formed, and for this purpose it is desirable to have multiple identical patterns on the substrate. This makes it possible to calculate the change in the formation result (such as core width) corresponding to the coordinates on the wafer based on the difference in the formation result between markers in each of the multiple patterns.

[0037] The processing information is not limited to the shape information of the waveguide components described above, but may be, for example, the following information: The average value of the actually formed waveguide width compared to the desired waveguide width (design value) of the waveguide pattern, and the waviness and roughness of the waveguide surface and side surfaces. The actual waveguide width formed for each design value of the waveguide width (dependence of the difference between the design value and the actual value on the design waveguide width) The width of the formed waveguide varies depending on the bending radius, or the width of the formed waveguide varies depending on the bending radius and the waveguide angle used. Waveguide width in dense or close proximity (including average, waviness, roughness, etc.) - The brightness distribution and brightness of the captured image of the waveguide pattern. Based on this, information on the roughness of the processed surface and the processing height can be obtained.

[0038] The processing information elements in the mark 200 described above can be formed and acquired during the manufacturing process and used for correction in a later process. Furthermore, the optical characteristics of the optical waveguide that is finally manufactured can be estimated and predicted based on the acquired processing information. Note that the estimation and prediction of characteristics based on the acquired processing information described above is not limited to the optical waveguide that is finally manufactured, and it is also possible to estimate and predict the characteristics of resist patterns and the like that are formed during the manufacturing process, as will be clear from the following description. Next, their basic configurations will be described.

[0039] (correction based on processing information) In one embodiment of the present invention, a marker is formed in one step of the waveguide manufacturing process, processing information is acquired from the marker, and the processing information is used to correct the processing in the subsequent step.

[0040] For example, if processing information that "the resist pattern is thicker than the predetermined value" is acquired from the processing information element of the mark 200 formed in the same process in the photoresist development process, a correction of "lengthening / strengthening the etching time / strength" is made in the subsequent etching process to set the width of the waveguide formed in the etching process to the desired value (design value). Conversely, if processing information that "the resist pattern is thinner than the predetermined value" is acquired, a correction of "shortening / weakening the etching time / strength" is made.

[0041] As another example, after the etching process of a waveguide, the core width is measured based on the processing information element of the mark 200 formed during that process. Furthermore, the measured value can be used to estimate the width of the waveguide pattern through which the optical signal actually propagates. During the etching process, etching can be performed as an additional process based on the measured core width. For example, if the information indicates that the waveguide width after etching is wider than the ideal value, additional etching can be performed to correct the core width. If the core width is narrower than the desired value, this can be addressed by, for example, designing the waveguide to be wider than the desired width, or by performing etching twice and acquiring intermediate results. The ideal value of the waveguide width here may be a design value, or it may be an ideal waveguide width calculated from the predicted characteristics described below.

[0042] When determining etching conditions based on processing information, it is desirable to determine the etching time and the like taking into consideration the circulation of the etching gas.

[0043] Fig. 6 is a flowchart illustrating an example of correction using markers in the manufacturing process of an optical waveguide according to an embodiment of the present invention. Steps S1 to S8 in Fig. 6 represent the respective steps of manufacturing the optical waveguide described above in Fig. 1. Furthermore, the dicing step shown in step 9 is a step of cutting the wafer of optical waveguides manufactured up to that point into chips.

[0044] In the above manufacturing process, in this example, a waveguide pattern is formed in the photoresist development process of step S5, and a marker 200 is also formed (see FIG. 1). As described above in FIG. 4, this marker 200 has processing information elements formed thereon corresponding to the components of the waveguide pattern. Then, in the next step S201, an image of the marker 200 is captured, processing information is obtained from the captured processing information elements, and etching conditions for the subsequent etching process (S6) are calculated based on this processing information. Thereafter, the etching process is performed in step S6. As a result, as described above, for example, if the formed resist pattern is thicker than a predetermined value, the etching conditions for the etching process are calculated (corrected) to "increase the etching time / strength." As a result, the width of the waveguide formed in the etching process can be set to the desired value (design value).

[0045] (Optical property prediction based on processing information) In one embodiment of the present invention, a marker is formed during one step of the waveguide manufacturing process, processing information is acquired from the marker, and the optical properties of the optical waveguide that is finally obtained are estimated and predicted using the processing information.

[0046] FIG. 7 is a diagram illustrating an example of prediction using markers in the manufacturing process of an optical waveguide according to an embodiment of the present invention. This example utilizes the fact that the optical characteristics of an optical waveguide are determined according to the shape (width and thickness) and refractive index of the core through which light propagates. As shown in FIG. 7, the film thickness and refractive index of the core are obtained after the core film deposition process. After the etching process, the width of the core pattern is obtained as processing information from the formed marker 200. The optical characteristics of the finally manufactured optical waveguide are predicted based on the obtained core pattern width, core film thickness, and refractive index. Note that, as shown in FIG. 7, the processing information is obtained (imaged) after the etching process by imaging and measuring the width and refractive index of the core pattern in the area of ​​the core film 18 formed in this process that corresponds to the marker 200 (this area is also referred to as the "marker" in this specification).

[0047] Corrections may be made in subsequent processes based on the processing information obtained as described above with reference to FIG. 7. For example, processing information on the core film thickness and refractive index in the core film deposition process and the core pattern width in the etching process is obtained. Then, etching conditions for additional processes in the etching process are determined. This may result in cases where, for example, the optical characteristics estimated from the core film thickness, refractive index, and core width measured after the etching process, assuming a narrower core width, are closer to the design value. In other words, as described above, if the processing information indicates that "the core width of the waveguide pattern is wider than the ideal value," a correction can be made in the etching process to narrow the core width formed, taking into account the leakage of etching gas.

[0048] As mentioned above, a similar correction is also possible when capturing an image of the marker 200 during the resist pattern formation stage. For example, when the optical characteristics estimated from the core film thickness, refractive index, and resist pattern width measured after the resist pattern formation process are closer to the design values ​​than the optical characteristics estimated when the resist pattern width is assumed to be narrower. In other words, when the processing information indicates that the "resist pattern width is wider than the ideal value," a correction can be made in the etching process to narrow the core width formed, taking into account the leakage of etching gas.

[0049] As described above, the marker 200 is formed in the same process as the process for manufacturing the optical waveguide shown in Fig. 1. The timing for acquiring the processing information from the processing information element of the marker 200 varies depending on the intended use. As shown in the above example, the processing information may be acquired after the etching process and the photoresist development process, or after the upper cladding deposition process. In this case, processing information close to the final waveguide pattern can be acquired.

[0050] Furthermore, instead of acquiring the processing information in some of the steps, the processing information may be acquired from the marker 200 in all of the steps shown in FIG.

[0051] It is more preferable to perform the process after the core deposition step and up to the upper cladding deposition step, because in an optical waveguide structure, most of the light passes through the core, and the shape of the core has the greatest effect on the characteristics, and also because after the upper cladding is deposited, it is necessary to image the structure inside the upper cladding, which may introduce noise into the acquired data.

[0052] A specific example of the marker described above will be described below.

[0053] (First Example) As a first embodiment of the present invention, the waveguide components used in manufacturing an AWG waveguide and the corresponding processing information elements of a marker will be described with reference to Fig. 4, which was mentioned above in the explanation of the basic configuration. The bend 101, taper 102, and straight line 103, which are the waveguide components that make up the AWG waveguide, correspond to processing information elements 101M, 102M, and 103M of marker 200, respectively.

[0054] The parameters of the waveguide component are: bend 101 is the waveguide width, bend radius, and spacing; taper 102 is the taper rate and taper start / end waveguide width; and straight line 103 is the waveguide width. With regard to these parameters, in marker 200, processing information elements 102M and 103M are formed with the same values ​​(taper rate, taper start / end waveguide width, and waveguide width) as the corresponding taper 102 and straight line 103, respectively. In addition, processing information elements 102M and 103M are formed in at least two orthogonal directions or angles.

[0055] On the other hand, in the marker 200, the processing information element 101M can have parameter values ​​different from those of the corresponding bend 101. Specifically, as described above in FIG. 5(b), the bend radius is set to a smaller value than that of the actual waveguide component. The waveguide width and spacing have the same parameter values ​​as those of the corresponding bend 101. In addition, the processing information element 101M is formed in four locations with different orientations or angles. This allows the processing information element 101M corresponding to the bend 101 to be formed within the size of the marker 200.

[0056] If the taper 102 has a small taper rate and a large difference in the taper start / end waveguide width, the taper becomes longer and the size of the processing information element 102M becomes larger. In this case, the parameter values ​​are not made the same, but, for example, the difference in the taper start / end waveguide width is made smaller. As described above, it is not necessary for all parameter values ​​of the waveguide components and the processing information elements to be the same.

[0057] (Second Example) 8 is a diagram showing a marker according to the second embodiment, and shows the waveguide components used in manufacturing the waveguide that constitutes the MZI switch and the corresponding processing information elements of the marker. The waveguide components that constitute the MZI switch waveguide, namely, the bend 101, the straight line 103, the intersection 104, and the directional coupler 105, correspond to the processing information elements 101M, 103M, 104M, and 105M of the marker 200, respectively.

[0058] The parameters of the waveguide components are: bend 101 is the waveguide width and bend radius, and straight line 103 is the waveguide width. Furthermore, intersection 104 is the intersection angle, and directional coupler 105 is the straight line of the coupling section and the distance between them. With regard to these parameters, in marker 200, these processed information elements 103M, 104M, and 105M are formed with the same values ​​as the corresponding straight line, intersection, and directional coupler 105, respectively. In addition, processed information elements 103M and 105M are formed in at least two different orthogonal directions or angles, and processed information element 104M is formed in two different directions or angles.

[0059] On the other hand, in the marker 200, the processing information element 101M has a parameter value different from that of the corresponding bend 101. More specifically, as described above in FIG. 5(b), the bending radius is set to a smaller value than that of the actual waveguide component. In addition, the processing information element 101M is formed in four locations with different orientations or angles. This allows the processing information element 101M corresponding to the bend to be formed within the size of the marker 200.

[0060] (Third Example) Fig. 9 is a diagram showing a marker according to the third embodiment, showing the waveguide components when manufacturing the waveguide that constitutes the MZI switch and the corresponding processing information elements of the marker. It is almost the same as the marker according to the third embodiment described above in Fig. 8, and the following will explain the differences.

[0061] In an MZI switch, for example, as in a PILOSS configuration, the MZI waveguides and intersections 104 are often arranged along the same direction. Therefore, it is desirable that the processing information elements of the marker 200 also be arranged in the same direction as the actual arrangement. This is because the characteristics of the MZI switch, such as the ON / OFF extinction ratio and its wavelength dependency, and light leakage to other ports, can be determined by the MZI configuration and intersections.

Claims

1. A manufacturing method for manufacturing an optical waveguide, comprising: In a process of manufacturing an optical waveguide, a process of forming a processing information element corresponding to a waveguide component of the optical waveguide in the same process as the waveguide component, and forming a marker including the processing information element; A step of acquiring processing information in the step by capturing an image of the marker, a step of correcting an etching time or an etching intensity in a subsequent step based on the processing information; A manufacturing method comprising the steps of:

2. A manufacturing method for manufacturing an optical waveguide, which comprises carrying out a plurality of steps in time series, In the plurality of steps, a step of forming a processing information element corresponding to a waveguide component of an optical waveguide in the same step as the waveguide component, and forming a marker including the processing information element; While performing the plurality of steps, capturing an image of a marker including a processing information element corresponding to a waveguide component formed up to an i-th step in the plurality of steps, and controlling the formation of the waveguide component in a j-th step chronologically subsequent to the i-th step based on the processing information obtained by the capturing; and the controlling step further includes correcting an etching time or an etching intensity in forming the waveguide component in the jth step based on the processing information. A manufacturing method characterized by:

3. The manufacturing method according to claim 1 or 2, wherein the waveguide component and the processing information element have the same parameter values.

4. The method of claim 1 or 2, wherein the waveguide component and the processing information element have different parameter values.

5. The method of claim 4 , wherein the waveguide component and the processing information element have different parameter values ​​that result in different sizes of the elements to be formed.

6. The method of claim 4 , wherein the waveguide component and the processing information element have parameter values ​​that differ in the orientation of the formed element.

7. 3. The manufacturing method according to claim 1, wherein a plurality of the processing information elements are formed corresponding to one of the waveguide components.

8. The marker is The length of one side of the marker is 1 / 10 or less of the length of one side of the optical waveguide chip, or The area of ​​the marker is 1 / 100 or less of the area of ​​the tip of the optical waveguide. The manufacturing method according to claim 1 or 2, which is configured as follows.

9. A manufacturing apparatus that performs a plurality of steps in time series to manufacture an optical waveguide, a control means for controlling the steps so that a processing information element corresponding to a waveguide component of an optical waveguide is formed in the same step as the waveguide component, and a marker including the processing information element is formed; a means for executing, while executing the plurality of steps, a step of imaging the marker including a processing information element corresponding to a waveguide component formed up to an i-th step in the plurality of steps, and a step of controlling the formation of the waveguide component in a j-th step chronologically subsequent to the i-th step based on the processing information obtained by the imaging; and the controlling step further includes correcting an etching time or an etching intensity in forming the waveguide component in the jth step based on the processing information. A manufacturing apparatus characterized by:

10. The marker is The length of one side of the marker is 1 / 10 or less of the length of one side of the optical waveguide chip, or The area of ​​the marker is 1 / 100 or less of the area of ​​the tip of the optical waveguide. The manufacturing apparatus according to claim 9 , configured as follows:

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