Eccentricity detection device of rotating wafer and wafer detection system

Abstract

The utility model provides an eccentricity detection device for a rotating wafer and a wafer detection system, the wafer rotates around a rotation axis perpendicular to the wafer, and the eccentricity detection device comprises an ellipsoidal mirror; the light source is used for emitting a light beam towards the first focus of the ellipsoidal mirror; the sensing unit is arranged at a second focus of the ellipsoidal mirror and is used for sensing the light quantity of a light spot irradiated on a sensing surface of the sensing unit, the part, reflected by the wafer at the first focus, in the light beam forms first reflected light, the first reflected light is reflected by the ellipsoidal mirror to form second reflected light, and the second reflected light is reflected by the ellipsoidal mirror to form the light quantity of the light spot irradiated on the sensing surface of the sensing unit. The light spot is formed by the part, irradiating the sensing surface, of the second reflected light; and the determination unit is used for determining the eccentricity of the wafer relative to the rotation axis of the wafer according to the variation of the light quantity sensed by the sensing unit due to the rotation of the wafer.

Description

Technical Field

[0001] The present disclosure relates to the field of wafer detection technology, and in particular to an eccentricity detection device for a rotating wafer and a wafer detection system. Background Art

[0002] In the field of semiconductor manufacturing, wafers are the basic carriers of integrated circuits, and their quality and precision directly affect the performance of the final product. In all aspects of wafer manufacturing and testing, it is crucial to ensure the centering of the wafer relative to the axis of rotation. For example, during the photolithography process, the eccentricity of the wafer will cause pattern alignment errors, which in turn affects the manufacturing accuracy and yield of the integrated circuit. In addition, during the flatness detection and thickness measurement of the wafer, eccentricity will also lead to inaccurate measurement data, affecting the adjustment and optimization of subsequent processes.

[0003] At present, the technologies for measuring whether the wafer is centered mainly include the following methods: using the principle of optical imaging, capturing the wafer image with a CCD camera, and analyzing specific marks or edges in the image to determine the position and eccentricity of the wafer; using a laser interferometer to measure the eccentricity of the wafer as it rotates. This method has high accuracy but relatively high cost; detecting eccentricity by measuring the change in capacitance between the wafer and the sensor. This method has low cost but relatively poor accuracy and stability.

[0004] The current eccentricity measurement method has problems, especially in real-time online detection. For example, due to the high rotation speed of the wafer during the detection process, the above eccentricity measurement method is often difficult to achieve fast and accurate online detection. Although the optical alignment system can provide more intuitive image information, the complexity of image processing and analysis increases under high-speed rotation, and real-time performance is difficult to guarantee. Although laser interferometry has high accuracy, it is expensive and has strict environmental requirements, making it unsuitable for large-scale online applications. Although capacitive sensors have low costs, their measurement accuracy and stability will be greatly affected under high-speed rotation conditions. In addition, most of the current measurement equipment is offline detection, which cannot achieve seamless integration with the production process, resulting in low detection efficiency and inability to feedback adjustment information in a timely manner, affecting the continuity and stability of the production process. Utility Model Content

[0005] In order to solve the above technical problems, the embodiments of the present disclosure hope to provide a rotating wafer eccentricity detection device and a wafer detection system, which can adapt to real-time online detection technology under high-speed rotation conditions, and are of great significance for improving the efficiency and accuracy of wafer detection.

[0006] The technical solution of the present disclosure is achieved as follows:

[0007] In a first aspect, an embodiment of the present disclosure provides an eccentricity detection device for a rotating wafer, wherein the wafer rotates around a rotation axis perpendicular to the wafer, and the eccentricity detection device comprises:

[0008] Ellipsoidal mirror;

[0009] a light source, the light source being used to emit a light beam toward a first focus of the ellipsoidal mirror;

[0010] A sensing unit, the sensing unit is arranged at the second focus of the ellipsoid mirror and is used to sense the amount of light of the light spot irradiated on the sensing surface thereof, wherein the portion of the light beam reflected by the wafer at the first focus forms a first reflected light, the first reflected light is reflected by the ellipsoid mirror to form a second reflected light, and the portion of the second reflected light irradiating the sensing surface forms the light spot;

[0011] A determining unit is used to determine the eccentricity of the wafer relative to its rotation axis according to the change in the light amount sensed by the sensing unit caused by the rotation of the wafer.

[0012] In a second aspect, an embodiment of the present disclosure provides a wafer detection system, wherein the wafer detection system includes an eccentricity detection device for rotating a wafer according to the first aspect.

[0013] The disclosed embodiment provides an eccentricity detection device and a wafer detection system for rotating wafers, which can measure the eccentricity of the wafer in real time when the wafer rotates around the central axis. Specifically, due to the special optical characteristics of the ellipsoid mirror, when the wafer is not eccentric or centered, the light beam emitted by the light source will be reflected by the wafer at the first focus to form a first reflected light, which is then reflected by the ellipsoid mirror to form a second reflected light, all of which converge on the sensing unit at the second focus. On the other hand, even if the eccentricity changes slightly, since the amount of the second reflected light sensed by the sensing unit changes on a larger basis, high-precision measurement can be achieved. In addition, by arranging the sensing unit at the second focus of the ellipsoid mirror, even if the size of the sensing unit is small, all the light emitted from the first focus can be sensed. This design significantly reduces the space required for the sensing unit, making the eccentricity detection device lighter, or in other words, since the sensing unit is located at the second focus, no bulky optical components are required to collect the second reflected light, which can make the design of the eccentricity detection device more compact. The simplified optical system and compact device design help reduce manufacturing costs, because the smaller sensing unit and the reduced optical component requirements reduce material and assembly costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic diagram of an eccentricity detection device for a rotating wafer according to an embodiment of the present disclosure;

[0015] Figure 2 A schematic diagram of a rightward eccentricity produced for the wafer;

[0016] Figure 3 A schematic diagram of a leftward eccentricity produced for the wafer;

[0017] Figure 4 is a graph showing the relationship between the offset of the wafer and the energy of the light sensed by the sensing unit according to an embodiment of the present disclosure;

[0018] Figure 5 is a partial stereoscopic diagram of an eccentricity detection device for a rotating wafer according to an embodiment of the present disclosure;

[0019] Figure 6 Schematic diagram of components of a wafer inspection system according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0020] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0021] In the field of semiconductor manufacturing, the wafer is the basic carrier of integrated circuits, and its quality and precision have a decisive influence on the performance of the final product. In all aspects of wafer manufacturing and testing, it is crucial to ensure the centering of the wafer relative to the rotation axis. The eccentricity of the wafer will not only cause pattern alignment errors during the photolithography process, affecting the manufacturing accuracy and yield of the integrated circuit, but also cause inaccurate measurement data during the wafer flatness detection, thickness measurement and other processes, affecting the adjustment and optimization of subsequent processes. In the prior art, the following methods are mainly used to measure whether the wafer is centered: CCD camera based on optical imaging principle, laser interferometer and capacitive sensor. Although these methods have their own advantages, they also have obvious problems. For example, in real-time online detection of high-speed rotation, the image processing and analysis complexity of the optical alignment system increases, and real-time performance is difficult to guarantee; although laser interferometry has high accuracy, it is costly and has strict environmental requirements, and is not suitable for large-scale online applications; although capacitive sensors have low costs, their measurement accuracy and stability are poor under high-speed rotation conditions. In addition, most of the current measuring equipment is offline detection, which cannot be seamlessly integrated with the production process, resulting in low detection efficiency and inability to provide timely feedback and adjustment information, affecting the continuity and stability of the production process.

[0022] In view of the limitations of existing technologies, see Figure 1 The present disclosure proposes an eccentricity detection device 10 for a rotating wafer W, wherein the wafer W rotates around a rotation axis X perpendicular to the wafer W. Figure 1 In the figure, a wafer W having no eccentricity E generated by the central axis relative to the rotation axis X is schematically shown by a solid line, or the wafer W at the position of the solid line is non-eccentric or centered, and a wafer W having an eccentricity E generated by the central axis relative to the rotation axis X is schematically shown by a dotted line, or the wafer W at the position of the dotted line has an eccentricity E relative to the wafer W at the position of the solid line. The eccentricity detection device 10 may include:

[0023] The ellipsoidal mirror 200 can be positioned so that, when the wafer W is not eccentric relative to the rotation axis X, that is, the wafer W is in Figure 1 In the case of the position shown by the solid line, the first focus 210 of the ellipsoidal mirror 200 is located at the edge WE of the wafer W, such as Figure 1 As shown in, but the present invention is not limited thereto, the edge WE of the wafer W here refers to the periphery of the wafer W having a semicircular arc-shaped cross-sectional profile formed after chamfering, and the first focus 210 is schematically shown by a cross;

[0024] A light source 300, the light source 300 is used to emit a light beam IB toward the first focus 210 of the ellipsoidal mirror 200;

[0025] The sensing unit 400 is disposed at the second focus 220 of the ellipsoidal mirror 200 and is used to sense the amount of light of the light spot irradiated on its sensing surface 410, wherein the portion of the light beam IB reflected by the wafer W at the first focus 210 forms a first reflected light RL1, as shown in Figure 1 As schematically shown by the dotted line in FIG. 1 , the first reflected light RL1 is reflected by the ellipsoidal mirror 200 to form the second reflected light RL2. Figure 1 As schematically shown by the dot-dash line in FIG. 4 , the portion of the second reflected light RL2 that illuminates the sensing surface 410 forms the above-mentioned light spot;

[0026] The determining unit 500 is used to determine the eccentricity E of the wafer W relative to the rotation axis X thereof according to the variation of the light amount sensed by the sensing unit 400 due to the rotation of the wafer W.

[0027] Specifically, since the light beam IB is directed toward the first focus 210 and is reflected by the wafer at the first focus 210, Figure 1In the case where the edge WE of the wafer W is at the first focus 210, the light beam IB will be reflected by the edge WE and is reflected at the first focus 210. In this way, according to the elliptical mirror reflection principle, the second reflected light RL2 will converge at the second focus 220, and the amount of light sensed by the sensing unit 400 is equal to the amount of light of the light beam IB emitted by the light source 300. However, for example, Figure 2 When the wafer W shown in FIG. 1 moves rightward from the non-offset position shown by the dotted line to the offset position shown by the solid line to generate an eccentricity E, a portion of the light beam IB cannot be reflected by the wafer W, and thus cannot be reflected at the first focus 210, and therefore cannot be converged at the second focus 220, as shown in FIG. Figure 2 The portion of the light beam IB passing through the ellipsoidal mirror 200 is schematically shown, resulting in a reduction in the amount of the second reflected light RL2 sensed by the sensing unit 400. Figure 3 In the case where the wafer W shown in FIG. 1 moves to the left from the non-offset position shown by the dotted line to the offset position shown by the solid line to generate an eccentricity E, although the light beam IB can be fully reflected by the wafer W, a portion of the light beam IB is no longer reflected by the edge WE of the wafer W, resulting in that the first reflected light RL1 is not entirely emitted from the first focus 210, and therefore no longer propagates toward the second focus 220, as shown in FIG. Figure 3 As schematically shown by the double-dotted chain line in FIG. 4 , the amount of the second reflected light RL2 sensed by the sensing unit 400 is also reduced.

[0028] More specifically, the eccentricity detection device 10 may further include a drawing unit not shown in the drawings, see Figure 2 and Figure 3 It is easy to understand that the drawing unit can draw the following image by continuously shifting the wafer W and continuously obtaining the amount of light sensed by the sensing unit 400 during the continuous shifting of the wafer W. Figure 4 FIG. 1 is a graph showing the relationship between the offset E of the wafer W and the amount of light sensed, wherein Figure 4 In the method, the energy of the light spot is used to characterize the amount of light. Figure 4 In the example, the displacement E is expressed in micrometers and the energy is expressed in milliwatts. Figure 4 As shown in FIG. 1 , the larger the offset E, the smaller the energy of the sensed light. On the contrary, the smaller the offset E, the larger the energy of the sensed light. In addition, the corresponding amount of the second reflected light RL2 sensed by the sensing unit 400 is obtained by rotating the wafer W at different angles, and then compared with Figure 4By comparing the curve graph shown in FIG. 5 , the offset E of the wafer W can be obtained. In addition, it can be known that the above-mentioned variation refers to a variation that is not zero. In addition, in order to facilitate drawing a curve graph of the relationship between the wafer rotation angle and the energy of the sensed light, the determination unit 500 may include a data acquisition card 510, which is used to convert the above-mentioned variation into a continuous signal waveform, that is, the above-mentioned curve graph.

[0029] For the eccentricity detection device 10 according to the embodiment of the present disclosure, the eccentricity E of the wafer W can be measured in real time when the wafer W rotates around the central axis X. Specifically, due to the special optical characteristics of the ellipsoidal mirror 200, when the wafer W is not eccentric or centered, the light beam IB emitted by the light source 300 will be reflected by the wafer W at the first focus 210 to form the first reflected light RL1, and then reflected by the ellipsoidal mirror 200 to form the second reflected light RL2, all of which are converged on the sensing unit 400 at the second focus 220. On the other hand, even if the eccentricity E changes slightly, since the amount of the second reflected light RL2 sensed by the sensing unit 400 changes on a larger basis, high-precision measurement can be achieved. In addition, by arranging the sensing unit 400 at the second focus 220 of the ellipsoidal mirror 200, even if the sensing unit 400 is small in size, it can sense all the light emitted from the first focus 210. This design significantly reduces the space required for the sensing unit 400, making the eccentricity detection device 10 more lightweight. In other words, since the sensing unit 400 is located at the second focus 220, no bulky optical components are required to collect the second reflected light RL2, which can make the design of the eccentricity detection device 10 more compact. The simplified optical system and compact device design help reduce manufacturing costs, because the smaller sensing unit 400 and the reduced optical component requirements reduce material and assembly costs.

[0030] In some embodiments according to the present disclosure, the light source 300 may be a laser that emits a laser beam.

[0031] The laser beam emitted by the laser as the light source 300 has a very high directivity, which means that the laser beam can maintain a very narrow beam diameter during propagation, which helps to improve the accuracy and repeatability of the measurement of the eccentricity E of the wafer W. The laser beam has a very high monochromaticity, that is, it is composed of light of a single frequency, which is very important for the eccentricity detection device 10 because it can reduce the measurement error caused by different colors or frequencies in the beam. The high coherence of the laser beam enables the laser beam to maintain a good wavefront quality when it is reflected and focused by the ellipsoidal mirror 200, further improving the measurement accuracy. The laser beam emitted by the laser has high brightness and can maintain a high light intensity even after long-distance transmission or passing through an optical system, which helps to improve the signal intensity sensed by the sensing unit 400, thereby improving the signal-to-noise ratio. The high focusing performance of the laser beam enables the beam to be accurately focused on the first focus 210, which helps to improve the illumination accuracy of the eccentricity detection device 10 on the edge WE of the wafer W.

[0032] In some embodiments according to the present disclosure, see Figure 1 , the light beam IB can be perpendicular to the wafer W.

[0033] In this case, the eccentricity of the wafer W can maximize the amount of change in the amount of light, thereby enabling detection of the eccentricity E to be more sensitive.

[0034] In some embodiments according to the present disclosure, see Figure 5 The ellipsoid mirror 200 may be formed with a cross-groove opening 200H, so that the wafer W can be inserted into the ellipsoid mirror 200, and the portion of the light beam IB that is not reflected by the wafer W passes through the ellipsoid mirror 200, such as in combination with Figure 2 Easy to understand.

[0035] In some embodiments according to the present disclosure, see Figure 1 The eccentricity detection device 10 may further include a display unit 800, which is used to display the eccentricity E of the wafer W relative to the rotation axis X.

[0036] The display unit 800 can intuitively display the eccentricity E of the wafer W relative to the rotation axis X, so that the operator can quickly understand the measurement results, and can update and display the eccentricity E of the wafer W in real time, which is convenient for monitoring the dynamic changes of the wafer during the production process. Matching the high-precision measurement capability of the eccentricity detection device 10, the display unit 800 provides accurate eccentricity readings to ensure the accuracy and reliability of the data. User-friendly interface design: The display unit 800 may have a user-friendly interface design, including a clear digital display, a graphical interface or a trend chart, making the information easy to interpret. In addition, the display unit 800 can not only display the eccentricity E, but also display other related parameters as needed, such as wafer rotation speed, measurement time, etc., to provide comprehensive detection information. When the eccentricity E of the wafer W exceeds the preset tolerance range, the display unit 800 can provide a visual or auditory alarm to promptly remind the operator to take measures.

[0037] In some embodiments according to the present disclosure, see Figure 1 The eccentricity detection device 10 may further include a first adjusting unit 600, which is used to adjust the position of the ellipsoidal mirror 200 to adapt to wafers W of different sizes.

[0038] By setting the first adjustment unit 600, the eccentricity detection device 10 can adjust the position of the ellipsoidal mirror 200 to adapt to wafers W of different sizes. This design significantly improves the adaptability of the eccentricity detection device 10, so that it can flexibly respond to the detection requirements of wafers of various specifications, especially as described in detail below, the rotation of the wafer W occurs in the wafer detection system 1, and it is inconvenient to move the rotation axis X of the wafer W due to the need to perform other main inspections (such as defect inspection) on the wafer W. The first adjustment unit 600 allows the eccentricity detection device 10 to measure the eccentricity E of wafers W of larger or smaller sizes, effectively expanding the scope of application of the eccentricity detection device 10. The design of the first adjustment unit 600 enables the eccentricity detection device 10 to measure wafers W of different sizes without replacing the main components, optimizes the equipment configuration, and reduces additional equipment investment. Since the eccentricity detection device 10 can adapt to wafers W of various sizes, the need for customizing equipment for wafers of specific sizes is reduced, thereby reducing production costs.

[0039] In some embodiments according to the present disclosure, see Figure 1 The eccentricity detection device 10 may further include a second adjustment unit 700 , and the second adjustment unit 700 is used to adjust the position of the light source 300 to adapt to the position of the ellipsoidal mirror 200 .

[0040] The design of the second adjustment unit 700 provides the function of adjusting the position of the light source 300, which enables the eccentricity detection device 10 to adjust the light source 300 accordingly according to the position change of the ellipsoidal mirror 200, ensuring that the light beam always accurately irradiates the predetermined focus. Through the adjustment of the second adjustment unit 700, the light source 300 can adapt to the measurement requirements of wafers W of different sizes, and the accuracy and consistency of the measurement can be guaranteed regardless of how the size of the wafer changes. The second adjustment unit 700 allows the position of the light source 300 to be dynamically adjusted according to the adjustment of the ellipsoidal mirror 200, thereby providing greater flexibility when measuring wafers W of different sizes. The addition of the second adjustment unit 700 enables the eccentricity detection device 10 to be quickly reconfigured when facing different measurement tasks without replacing or redesigning the entire system.

[0041] See also Figure 6 The embodiment of the present disclosure further provides a wafer detection system 1, which may include an eccentricity detection device 10 for measuring the eccentricity E of a wafer W according to the aforementioned embodiments of the present disclosure.

[0042] By accurately measuring the eccentricity E of the wafer W through the eccentricity detection device 10, the wafer detection system 1 can ensure the centering of the wafer relative to the rotation axis X during the detection process, thereby significantly improving the accuracy of the detection result. The precise eccentricity data provided by the eccentricity detection device 10 can be used for feedback control, automatically adjusting the position of the wafer W or adjusting the equipment parameters, and realizing more precise process control.

[0043] In some embodiments according to the present disclosure, see Figure 6 The wafer detection system 1 may further include a resetting device 20 for resetting the wafer W relative to the rotation axis X when the eccentricity E measured by the eccentricity detection device 10 is not less than 500 μm.

[0044] When the eccentricity E measured by the eccentricity detection device 10 is not less than 500μm, the reset device 20 can, for example, be automatically started to correct the wafer W to ensure that its position relative to the rotation axis X is accurate. Through the automated reset process, manual intervention and waiting time are reduced, and the production efficiency of wafer detection is improved. The reset device 20 ensures that only wafers W with eccentricity E within the allowable range can continue the subsequent detection process, thereby ensuring product quality and consistency. By timely resetting wafers W whose eccentricity exceeds the standard, unnecessary material waste and cost increase caused by further processing are avoided. The integration of the reset device 20 reflects the high intelligence and automation of the wafer detection system 1, which can autonomously respond to measurement results and take corresponding measures.

[0045] In some embodiments according to the present disclosure, the wafer inspection system 1 may further include: Figure 1The driving unit 100 shown in FIG. 1 is used to rotate the wafer W around a rotation axis X perpendicular to the wafer W, as shown in FIG. Figure 1 This is schematically illustrated by an arrowed curve around the axis of rotation X.

[0046] More specifically, see Figure 1 The driving unit 100 may include a rotating platform 110 , and the rotating platform 110 is configured to carry a wafer W so that the wafer W rotates together with the rotating platform 110 .

[0047] The drive unit 100 easily realizes the rotation of the wafer W by including a rotating platform 110. The rotating platform 110 is specially designed to carry the wafer W, ensuring that the wafer W can maintain a stable and accurate position during the rotation process. Using the rotating platform 110, the rotation speed and direction of the wafer W can be easily adjusted, providing operational flexibility to adapt to different measurement requirements. As a part of the drive unit 100, the rotating platform 110 simplifies the structure of the entire eccentricity detection device 10 and reduces complex mechanical components, thereby reducing the complexity of the equipment and potential failure points.

[0048] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present disclosure should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. An eccentricity detection device for a rotating wafer, wherein: The wafer rotates around a rotation axis perpendicular to the wafer, and is characterized in that the eccentricity detection device comprises: Ellipsoidal mirror; a light source, the light source being used to emit a light beam toward a first focus of the ellipsoidal mirror; A sensing unit, the sensing unit is arranged at the second focus of the ellipsoid mirror and is used to sense the amount of light of the light spot irradiated on the sensing surface thereof, wherein the portion of the light beam reflected by the wafer at the first focus forms a first reflected light, the first reflected light is reflected by the ellipsoid mirror to form a second reflected light, and the portion of the second reflected light irradiating the sensing surface forms the light spot; A determining unit is used to determine the eccentricity of the wafer relative to its rotation axis according to the change in the light amount sensed by the sensing unit caused by the rotation of the wafer.

2. The eccentricity detection device for a rotating wafer according to claim 1, characterized in that: The light source is a laser that emits a laser beam.

3. The eccentricity detection device for a rotating wafer according to claim 1 or 2, characterized in that: The light beam is perpendicular to the wafer.

4. The eccentricity detection device for a rotating wafer according to claim 3, characterized in that: The ellipsoidal mirror is formed with a cross-groove opening, so that the wafer can be inserted into the ellipsoidal mirror and the part of the light beam that is not reflected by the wafer passes through the ellipsoidal mirror.

5. The eccentricity detection device for a rotating wafer according to claim 1 or 2, characterized in that: The determining unit comprises a data acquisition card, and the data acquisition card is used to convert the variation into a continuous signal waveform.

6. The eccentricity detection device for a rotating wafer according to claim 1 or 2, characterized in that: The eccentricity detection device further includes a display unit, and the display unit is used to display the eccentricity of the wafer relative to the rotation axis.

7. The eccentricity detection device for a rotating wafer according to claim 1 or 2, characterized in that: The eccentricity detection device further comprises a first adjusting unit, and the first adjusting unit is used to adjust the position of the ellipsoidal mirror to adapt to wafers of different sizes.

8. The eccentricity detection device for a rotating wafer according to claim 7, characterized in that: The eccentricity detection device also includes a second adjustment unit, which is used to adjust the position of the light source to adapt to the position of the ellipsoidal mirror.

9. A wafer inspection system, characterized in that: The wafer detection system comprises the eccentricity detection device for rotating wafers according to any one of claims 1 to 8.

10. The wafer inspection system according to claim 9, characterized in that: The wafer detection system further includes a resetting device for resetting the wafer relative to the rotation axis when the eccentricity measured by the eccentricity detection device is not less than 500 μm.

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