A waveguide test structure, a waveguide test wafer and a waveguide test method

Abstract

This application provides a waveguide test structure, a waveguide test wafer, and a waveguide test method. The test structure includes at least two waveguide structures, each waveguide structure comprising a plurality of curved waveguides and a plurality of straight waveguides. The straight waveguides are located between adjacent curved waveguides and connect to them. The curved waveguides have the same shape, but the number of curved waveguides varies in different waveguide structures. This application provides a waveguide test structure and test method that simultaneously incorporates curved and straight waveguides, representing waveguide structures in practical applications and thus enabling accurate testing of light loss through a single curved waveguide.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a waveguide test structure, a waveguide test wafer, and a waveguide test method. Background Technology

[0002] One of the most important characteristics of optical waveguide structures is the attenuation, or loss, that occurs when light waves pass through them. Based on the loss mechanism, this loss is categorized into scattering loss, absorption loss, and radiation loss. Of these three types, scattering loss is usually the dominant form and is the most important aspect to consider in the fabrication of optical waveguide structures.

[0003] Current methods for testing the loss of bent waveguides involve inserting multiple bent waveguide structures sequentially and then measuring the loss of light waves as they pass through these bends. However, such structures do not exist in actual devices. In fact, the continuous bending increases the roughness of the waveguide sidewalls, introducing additional waveguide transmission loss, resulting in the measured loss of the bent waveguide being greater than the actual value in practical applications.

[0004] Therefore, it is necessary to provide a more effective and reliable technical solution for accurately testing the loss of bent waveguides. Summary of the Invention

[0005] This application provides a waveguide test structure, a waveguide test wafer, and a waveguide test method, which can accurately test the loss of light passing through a single bent waveguide.

[0006] One aspect of this application provides a waveguide test structure for testing the loss generated when light passes through a bent waveguide, comprising: at least two waveguide structures, each waveguide structure including a plurality of curved waveguides and a plurality of straight waveguides, the plurality of straight waveguides being located between adjacent curved waveguides and connecting the plurality of curved waveguides; the plurality of curved waveguides having the same shape, and the number of curved waveguides in different waveguide structures being different.

[0007] In some embodiments of this application, the difference in the number of bent waveguides in any two waveguide structures is greater than or equal to 24.

[0008] In some embodiments of this application, the number of bent waveguides in each waveguide structure is greater than or equal to 3 and less than or equal to 100.

[0009] In some embodiments of this application, the length of the straight waveguide between any two adjacent curved waveguides is greater than or equal to 10 micrometers.

[0010] In some embodiments of this application, the total length of the straight waveguide in each waveguide structure is 1 cm to 2 cm.

[0011] In some embodiments of this application, the total length of the straight waveguides in different waveguide structures is the same.

[0012] In some embodiments of this application, the bending radius of the bent waveguide is 2 micrometers to 50 micrometers.

[0013] In some embodiments of this application, the waveguide structure is arranged in a double-helix manner.

[0014] In some embodiments of this application, the waveguide structure is arranged in a single-line reciprocating bending manner.

[0015] One aspect of this application also provides a waveguide test wafer for testing the loss generated when light passes through a bent waveguide, comprising: an SOI substrate including a bottom silicon layer, an insulating layer and a top silicon layer; and a waveguide test structure as described above, located in the top silicon layer and formed by etching the top silicon layer.

[0016] Another aspect of this application provides a waveguide testing method for testing the loss generated when light passes through a bent waveguide, comprising: allowing light to enter the waveguide structure from the incident end of each waveguide structure in the waveguide testing structure as described above, and exit from the exit end of the waveguide structure after passing through the waveguide structure; obtaining the power loss of light passing through different waveguide structures based on the power of light entering the waveguide structure and the power of light exiting the waveguide structure; and obtaining the power loss of light passing through a single bent waveguide based on the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structure.

[0017] In some embodiments of this application, the method for obtaining the power loss of light passing through different waveguide structures based on the power of light entering the waveguide structure and the power of light exiting the waveguide structure is as follows: the power loss is calculated using formula (1), where formula (1) is...

[0018]

[0019] Where IL is the power loss of light passing through the waveguide structure, P0 is the power of light entering the waveguide structure, and P1 is the power of light exiting the waveguide structure.

[0020] In some embodiments of this application, the method for obtaining the power loss of light passing through a single bent waveguide based on the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structures includes: creating a fitted linear graph of the relationship between the absolute value of the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structures, wherein the slope of the fitted linear graph is the power loss of light passing through a single bent waveguide.

[0021] In some embodiments of this application, the method for obtaining the power loss of light passing through a single bent waveguide based on the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structures includes: establishing a relationship between the absolute value of the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structures based on the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structures; and combining the length ratio of straight waveguides in different waveguide structures to solve for the power loss of light passing through a single bent waveguide.

[0022] This application provides a waveguide test structure, a waveguide test wafer, and a waveguide test method. The test structure has both a bent waveguide and a straight waveguide, which can represent the waveguide structure in practical applications, and thus can accurately test the loss of light passing through a single bent waveguide. Attached Figure Description

[0023] The following accompanying drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals denote similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting and exemplary, and the drawings are for illustrative purposes only and are not intended to limit the scope of this application. Other embodiments may similarly fulfill the inventive intent of this application. It should be understood that the drawings are not drawn to scale.

[0024] in:

[0025] Figure 1 This is a schematic diagram of the waveguide test structure described in some embodiments of this application;

[0026] Figure 2 This is a schematic diagram of the waveguide test structure described in other embodiments of this application;

[0027] Figure 3 This is a fitted line graph of the waveguide testing method described in some embodiments of this application. Detailed Implementation

[0028] The following description provides specific application scenarios and requirements for this application, intended to enable those skilled in the art to make and use the content of this application. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this application. Therefore, this application is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.

[0029] The technical solution of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0030] Figure 1The accompanying drawings are schematic diagrams of waveguide test structures according to some embodiments of this application. The waveguide test structures according to some embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0031] refer to Figure 1 As shown, this application provides a waveguide test structure 100 for testing the loss generated when light passes through a bent waveguide. The waveguide test structure 100 includes at least two waveguide structures. Embodiments of this application use two waveguide structures as an example, see reference... Figure 1 As shown, the two waveguide structures are a first waveguide structure 110 and a second waveguide structure 120. It should be noted that, depending on testing needs and to further improve testing accuracy, the number of waveguide structures can be greater; this application only uses two waveguide structures as an example.

[0032] In the waveguide test structure of this application, each waveguide structure includes several curved waveguides in an arc shape and several straight waveguides in a straight line. The several straight waveguides are located between adjacent curved waveguides and connected to the several curved waveguides. The several curved waveguides have the same shape, and the number of curved waveguides in different waveguide structures is different.

[0033] Specifically, please refer to Figure 1 As shown, the first waveguide structure 110 includes a plurality of curved waveguides 112 and a plurality of straight waveguides 111. The plurality of straight waveguides 111 are located between adjacent curved waveguides 112 and connect the plurality of curved waveguides 112; the plurality of curved waveguides 112 have the same shape. The length of a single straight waveguide 111 is not fixed. The straight waveguides 111 are used to connect the plurality of curved waveguides 112 in series to solve the problem in the current technology where directly connecting curved waveguides to curved waveguides leads to test results that do not conform to actual processes.

[0034] Specifically, please refer to Figure 1 As shown, the second waveguide structure 120 includes several curved waveguides 122 and several straight waveguides 121. The straight waveguides 121 are located between adjacent curved waveguides 122 and connect the curved waveguides 122. The curved waveguides 122 have the same shape. The length of a single straight waveguide 121 is not fixed. The straight waveguides 121 are used to connect the curved waveguides 122 in series to solve the problem in current technology where directly connecting curved waveguides to each other results in test results that do not conform to actual manufacturing processes.

[0035] The difference between the first waveguide structure 110 and the second waveguide structure 120 lies in the number of bent waveguides. Specifically, taking this embodiment as an example, the first waveguide structure 110 has 6 bent waveguides 112, while the second waveguide structure 120 has 62 bent waveguides 122.

[0036] Continue to refer to Figure 1 As shown, each waveguide structure (first waveguide structure 110 and second waveguide structure 120) has a light input end and a light output end. The light input end and the light output end can be connected to a grating or an optical fiber.

[0037] Continue to refer to Figure 1 As shown, in some embodiments of this application, the waveguide structures (first waveguide structure 110 and second waveguide structure 120) are arranged in a single-line reciprocating bending manner.

[0038] Figure 2 This is a schematic diagram of the waveguide test structure described in some other embodiments of this application.

[0039] refer to Figure 2 As shown, in some other embodiments of this application, the waveguide structures (first waveguide structure 110 and second waveguide structure 120) are arranged in a double-helix configuration. The number of curved waveguides can be increased by increasing the number of helical turns.

[0040] The principle of the waveguide test structure described in this application is: the total loss of light passing through the waveguide test structure = the loss of light passing through the bent waveguide + the loss of light passing through the straight waveguide.

[0041] Furthermore, the total loss of light passing through the waveguide test structure = the loss of light passing through a single bent waveguide × the number of bent waveguides + the loss of light passing through a straight waveguide.

[0042] Using a function, it can be expressed as: y = ax + b (1)

[0043] Where y is the total loss of light passing through the waveguide test structure; a is the loss of light passing through a single bent waveguide; x is the number of bent waveguides; and b is the loss of light passing through a straight waveguide.

[0044] Based on the relational function (1), the loss of light passing through a single curved waveguide can be obtained by finding the slope a of the relational function (1).

[0045] Specifically, y represents the total light loss through the waveguide test structure, which can be directly measured in the experiment. x represents the number of bent waveguides, determined by the different waveguide structures in the waveguide test structure. Therefore, what needs to be calculated are a (the light loss through a single bent waveguide) and b (the light loss through a straight waveguide).

[0046] Each waveguide structure (e.g., the first waveguide structure 110 and the second waveguide structure 120) can correspond to a set of equations about function (1). By setting a sufficient number of waveguide structures (i.e., setting at least two waveguide structures as described in this application), a sufficient number of equations can be obtained. Then, the equations can be solved to obtain a (the loss of light passing through a single bent waveguide). It should be noted that the test principle is explained first here, and the calculation details will be explained in detail later.

[0047] In some other embodiments of this application, due to unavoidable data errors during the testing process (e.g., errors caused by measuring optical loss, errors caused by the fabrication process of the waveguide test structure), the acquired data may not be able to solve the equations described above, or the calculation results may have large errors. Therefore, a scatter plot can also be drawn based on the acquired data. According to function (1), the scatter plot can be fitted into a straight line, and the slope of the straight line is a (the loss of light passing through a single curved waveguide).

[0048] In some embodiments of this application, the difference in the number of bent waveguides in any two waveguide structures is greater than or equal to 24.

[0049] In some embodiments of this application, the number of bent waveguides in each waveguide structure is greater than or equal to 3 and less than or equal to 100.

[0050] In some embodiments of this application, the length of the straight waveguide between any two adjacent curved waveguides is greater than or equal to 10 micrometers.

[0051] In some embodiments of this application, the total length of the straight waveguide in each waveguide structure is 1 cm to 2 cm.

[0052] In some embodiments of this application, the bending radius of the bent waveguide is 2 micrometers to 50 micrometers.

[0053] The detailed settings for the waveguide test structure described above are all aimed at improving test accuracy. As mentioned earlier, this application can obtain the light loss passing through a single curved waveguide by plotting a scatter plot and then fitting it to a straight line to calculate the slope. Therefore, the number and distribution of scatter points in the scatter plot are crucial. According to the applicant's experimental analysis, the above settings can ensure the concentration of the scatter plot, improve the accuracy of fitting the scatter plot to a straight line, and thus improve test accuracy.

[0054] In some embodiments of this application, the total length of the straight waveguides in different waveguide structures is the same. In function (1), b is also an unknown, and different values ​​of b will increase the difficulty of fitting. Therefore, this application sets the total length of the straight waveguides in different waveguide structures to be equal, that is, b in the equation system is equal, which can reduce the computational difficulty.

[0055] This application provides a waveguide test structure that includes both a curved waveguide and a straight waveguide, which can represent the waveguide structure in practical applications and thus can accurately test the loss of light passing through a single curved waveguide.

[0056] Embodiments of this application also provide a waveguide test wafer for testing the loss generated when light passes through a bent waveguide, comprising: an SOI substrate including a bottom silicon layer, an insulating layer, and a top silicon layer; and a waveguide test structure as described above, located in the top silicon layer and formed by etching the top silicon layer.

[0057] SOI substrates (silicon-on-insulator substrates) are a common type of substrate in the semiconductor field; therefore, for the sake of brevity, their detailed structure and formation methods will not be described in detail here. Furthermore, the method of etching silicon waveguides on SOI substrates is also a conventional technique in this field and will not be elaborated upon here either. Those skilled in the art should understand that the first and second waveguide structures in the waveguide test structures described above can both be silicon waveguides, and are formed by etching the top silicon layer on the SOI substrate.

[0058] Embodiments of this application also provide a waveguide testing method for testing the loss generated when light passes through a bent waveguide, comprising: allowing light to enter the waveguide structure from the incident end of each waveguide structure in the waveguide testing structure 100 as described above, and exit from the exit end of the waveguide structure after passing through the waveguide structure; obtaining the power loss of light passing through different waveguide structures based on the power of light entering the waveguide structure and the power of light exiting the waveguide structure; and obtaining the power loss of light passing through a single bent waveguide based on the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structure.

[0059] In some embodiments of this application, the method for obtaining the power loss of light passing through different waveguide structures based on the power of light entering the waveguide structure and the power of light exiting the waveguide structure is as follows: the power loss is calculated using formula (1), where formula (1) is...

[0060]

[0061] Where IL is the power loss of light passing through the waveguide structure, P0 is the power of light entering the waveguide structure, and P1 is the power of light exiting the waveguide structure.

[0062] In some embodiments of this application, the method for obtaining the power loss of light passing through a single bent waveguide based on the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structures includes: creating a fitted linear graph of the relationship between the absolute value of the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structures, wherein the slope of the fitted linear graph is the power loss of light passing through a single bent waveguide.

[0063] Example 1: Power loss of light passing through a single curved waveguide is obtained by solving equations. Based on the structure of the first waveguide, equation (1) is obtained: y1=ax1+b1

[0064] Where y1 is the total loss of light passing through the first waveguide structure; a is the loss of light passing through a single bent waveguide; x1 is the number of bent waveguides in the first waveguide structure; and b1 is the loss of light passing through the straight waveguides in the first waveguide structure.

[0065] Based on the second waveguide structure, equation (2) y2=ax2+b2 is obtained.

[0066] Where y2 is the total loss of light passing through the second waveguide structure; a is the loss of light passing through a single bent waveguide; x2 is the number of bent waveguides in the second waveguide structure; and b2 is the loss of light passing through the straight waveguides in the second waveguide structure.

[0067] By combining the two equations above, we can derive 'a' (the loss of light passing through a single curved waveguide). Specifically, y1 and y2 can be directly measured; x1 and x2 are also known; and the loss of light passing through a straight waveguide is proportional to the length of the straight waveguide. Therefore, since the lengths of the straight waveguides in both the first and second waveguide structures are known, the ratio of b1 to b2 can be obtained. In the two equations above, only 'a' and b1 are unknowns (b2 can be expressed using b1), and these two unknowns can be solved by combining the two equations.

[0068] Example 2: Obtaining the power loss of light passing through a single bent waveguide using a fitted straight line method.

[0069] Based on the first waveguide structure, the total light loss y1 and the number of bent waveguides x1 in the first waveguide structure are obtained; based on the second waveguide structure, the total light loss y2 and the number of bent waveguides x2 in the second waveguide structure are obtained. The total lengths of the straight waveguides in both the first and second waveguide structures are the same, i.e., b1 and b2 are equal, both denoted by b.

[0070] Figure 3 This is a fitted line graph of the waveguide testing method described in some embodiments of this application.

[0071] refer to Figure 3 As shown, the horizontal axis represents the number of bent waveguides, and the vertical axis represents the total light loss through the waveguide structure. By plotting the number of bent waveguides and light loss for different waveguide structures as a scatter plot and then fitting it to a straight line, the slope of this line is 'a', and its intersection with the y-axis is 'b'.

[0072] This application provides a waveguide test structure, a waveguide test wafer, and a waveguide test method. The test structure has both a bent waveguide and a straight waveguide, which can represent the waveguide structure in practical applications, and thus can accurately test the loss of light passing through a single bent waveguide.

[0073] In summary, after reading this application, those skilled in the art will understand that the foregoing content is presented by way of example only and is not restrictive. Although not explicitly stated herein, those skilled in the art will understand that this application is intended to encompass various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are all within the spirit and scope of the exemplary embodiments of this application.

[0074] It should be understood that the term "and / or" as used in this embodiment includes any or all combinations of one or more of the associated listed items. It should also be understood that the terms "comprising," "containing," "including," or "comprises," as used in this application, indicate the presence of the described features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.

[0075] It should also be understood that although the terms first, second, third, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Therefore, without departing from the teachings of this application, a first element in some embodiments may be referred to as a second element in other embodiments. The same reference numerals or the same reference signs denote the same elements throughout the specification.

[0076] Furthermore, this application specification describes exemplary embodiments by referring to idealized exemplary cross-sectional views and / or plan views and / or perspective views. Therefore, differences from the illustrated shapes are foreseeable due to factors such as manufacturing techniques and / or tolerances. Therefore, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but should include deviations in shape caused, for example, by manufacturing processes. Thus, the regions shown in the figures are substantially schematic, and their shapes are not intended to illustrate the actual shapes of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.

Claims

1. A waveguide test structure for testing the loss generated when light passes through a bent waveguide, characterized in that, include: At least two waveguide structures, each waveguide structure including a plurality of curved waveguides and a plurality of straight waveguides, wherein the plurality of straight waveguides are located between and connected to adjacent curved waveguides, and the straight waveguides and the curved waveguides are alternately arranged such that adjacent curved waveguides are not directly connected. The several curved waveguides have the same shape, the number of curved waveguides in different waveguide structures is different, and the total length of the straight waveguides in different waveguide structures is the same.

2. The waveguide test structure as described in claim 1, characterized in that, The difference in the number of bent waveguides in any two waveguide structures is greater than or equal to 24.

3. The waveguide test structure as described in claim 1, characterized in that, The number of bent waveguides in each waveguide structure is greater than or equal to 3 and less than or equal to 100.

4. The waveguide test structure as described in claim 1, characterized in that, The length of the straight waveguide between any two adjacent curved waveguides is greater than or equal to 10 micrometers.

5. The waveguide test structure as described in claim 1, characterized in that, The total length of the straight waveguides in each waveguide structure is 1 to 2 centimeters.

6. The waveguide test structure as described in claim 1, characterized in that, The bending radius of the bent waveguide is from 2 micrometers to 50 micrometers.

7. The waveguide test structure as described in claim 1, characterized in that, The waveguide structure is arranged in a double-helix configuration.

8. The waveguide test structure as described in claim 1, characterized in that, The waveguide structure is arranged in a single-line reciprocating bending pattern.

9. A waveguide test wafer for testing the loss generated when light passes through a bent waveguide, characterized in that, include: SOI substrate, including bottom silicon layer, insulating layer and top silicon layer; The waveguide test structure as described in any one of claims 1-8 is located in the top silicon layer and is formed by etching the top silicon layer.

10. A waveguide testing method for testing the loss generated when light passes through a bent waveguide, characterized in that, include: Light is made to enter the waveguide structure from the incident end of each waveguide structure in the waveguide test structure as described in any one of claims 1 to 8, pass through the waveguide structure, and exit from the exit end of the waveguide structure; The power loss of light passing through different waveguide structures is obtained by measuring the power of light entering the waveguide structure and the power of light exiting the waveguide structure. The power loss of light passing through a single bent waveguide is obtained by considering the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structures.

11. The waveguide testing method as described in claim 10, characterized in that, The method for obtaining the power loss of light passing through different waveguide structures based on the power of light entering the waveguide structure and the power of light exiting the waveguide structure is as follows: The power loss is calculated using formula (1), where formula (1) is... ， Where IL is the power loss of light passing through the waveguide structure, P0 is the power of light entering the waveguide structure, and P1 is the power of light exiting the waveguide structure.

12. The waveguide testing method as described in claim 10, characterized in that, The method for obtaining the power loss of light passing through a single bent waveguide based on the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structures includes: creating a fitted linear graph of the relationship between the absolute value of the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structures, wherein the slope of the fitted linear graph is the power loss of light passing through a single bent waveguide.

13. The waveguide testing method as described in claim 10, characterized in that, The method for obtaining the power loss of light passing through a single bent waveguide based on the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structures includes: establishing the relationship between the absolute value of the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structures based on the power loss of light passing through different waveguide structures and the number of bent waveguides in the corresponding waveguide structures; and combining the length ratio of straight waveguides in different waveguide structures to solve for the power loss of light passing through a single bent waveguide.

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