Non-contact wafer stress detector

Abstract

The utility model discloses a non -contact wafer stress detector, including vibration compensation hardware module, stress detection sensor, wafer stage, Z axis positioning module, R axis rotating platform and X axis module, whole structure is based on vibration compensation hardware module, stress detection sensor is fixed on Z axis positioning module, Z axis positioning module drives stress detection sensor moves along perpendicular wafer stage Z direction, wafer stage is fixed on R axis rotating platform, R axis rotating platform is fixed on X axis removes and carries module, and wafer stage moves along X axis and R axis direction, realizes the collection of whole wafer surface data, the utility model discloses through the closed -loop cooperation of three big modules of motion control, optical detection, data processing, avoids wafer damage, realizes from physical deformation to the nondestructive quantitative detection of residual stress.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor manufacturing testing equipment technology, specifically a non-contact wafer stress tester based on the Stoney formula, which is suitable for high-precision online measurement of wafer warpage, thin film stress distribution and surface morphology. Background Technology

[0002] In the semiconductor manufacturing industry, residual stress detection on wafers is a crucial step in ensuring chip yield. Traditional stress detection technologies mainly rely on contact measurement methods, which have the following technical bottlenecks:

[0003] 1) Limitations of contact measurement: Mechanical probes or resistance strain gauges need to contact the wafer surface, which can easily lead to micro-scratches or contamination, and are not suitable for ultra-thin wafers;

[0004] 2) Insufficient efficiency and adaptability: X-ray diffraction equipment is complex and the detection speed is slow, while laser interferometry has poor vibration resistance and low tilt tolerance. Summary of the Invention

[0005] In view of the shortcomings of the prior art, this utility model discloses a non-contact wafer stress detector to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a non-contact wafer stress detector, comprising a vibration compensation hardware module, a stress detection sensor, a wafer stage, a Z-axis positioning module, an R-axis rotation platform, and an X-axis module; the stress detection sensor, wafer stage, Z-axis positioning module, R-axis rotation platform, and X-axis module are all based on the vibration compensation hardware module; the stress detection sensor is fixed on the Z-axis positioning module, and the Z-axis positioning module drives the stress detection sensor to move along the Z-direction perpendicular to the wafer stage; the wafer stage is fixed on the R-axis rotation platform; the R-axis rotation platform is fixed on the X-axis transfer module, and the wafer stage moves along the X-axis and R-axis directions to achieve the acquisition of data from the entire wafer surface.

[0007] Preferably, the vibration compensation hardware module includes a vibration damping base and a mounting bracket, with the lower end of the mounting bracket fixed to the upper surface of the vibration damping base, and the Z-axis positioning module mounted on the inner wall of the mounting bracket.

[0008] Preferably, the vibration damping base is equipped with a piezoelectric accelerometer, which feeds back vibration data to the signal processor in real time, and the environmental vibration interference is eliminated through algorithm correction.

[0009] Preferably, the Z-axis positioning module adjusts the displacement value of the stress detection sensor along the Z direction according to different wafer thicknesses to meet the working distance of the stress detection sensor.

[0010] Preferably, the X-axis module and R-axis rotation platform drive the wafer stage to complete the measurement of the entire surface data of the wafer, and then process the measurement data to calculate the stress data of the wafer.

[0011] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. This utility model has a high degree of integration and can be directly embedded into semiconductor production line equipment. It also achieves high-precision non-contact measurement with a resolution of 0.01nm and a stress detection accuracy of ±0.05MPa, which is superior to X-ray diffraction (±0.5MPa). It avoids wafer damage and is suitable for ultra-thin wafers (thickness <100μm). It also has the characteristics of strong resistance to environmental interference, with a tilt tolerance of ≤15° and vibration suppression of >60dB.

[0012] 2. This utility model constructs an active vibration suppression system through the synergistic effect of hardware anti-vibration base and algorithm correction, which significantly improves the anti-interference ability of the detection system under complex working conditions and ensures the stability of the optical measurement path.

[0013] 3. This utility model is based on a closed-loop linkage mechanism of multi-axis motion control and sensor adaptive adjustment to achieve high-density blind-zone-free scanning of the wafer surface, while automatically adapting to different wafer thickness parameters, which greatly improves the integrity of detection and operational efficiency. Attached Figure Description

[0014] The accompanying drawings are provided to further understand the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.

[0015] In the attached diagram: Figure 1 This is a schematic diagram of the overall structure of the non-contact wafer stress detector of this utility model;

[0016] The following numbers are labeled in the diagram: 101, anti-vibration base; 102, mounting bracket; 2, stress detection sensor; 3, wafer stage; 4, Z-axis positioning module; 5, R-axis rotary platform; 6, X-axis module. Detailed Implementation

[0017] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0018] Example: Figure 1As shown, a non-contact wafer stress testing instrument includes a vibration compensation hardware module, a stress detection sensor 2, a wafer stage 3, a Z-axis positioning module 4, an R-axis rotation platform 5, and an X-axis module 6. The stress detection sensor 2, wafer stage 3, Z-axis positioning module 4, R-axis rotation platform 5, and X-axis module 6 are all based on the vibration compensation hardware module. The vibration compensation hardware module includes a vibration-damping base 101 and a mounting bracket 102. The lower end of the mounting bracket 102 is fixed to the upper surface of the vibration-damping base 101. The Z-axis positioning module 4 is mounted on the inner wall of the mounting bracket 102. A piezoelectric accelerometer is installed inside the vibration-damping base 101. Vibration data is fed back to the signal processor in real time through the piezoelectric accelerometer. An algorithm is used to correct and eliminate environmental vibration interference. The algorithm includes... Kalman filtering algorithm and adaptive filtering algorithm, etc.; The stress detection sensor 2 is fixed on the Z-axis positioning module 4. The Z-axis positioning module 4 drives the stress detection sensor 2 to move along the Z direction perpendicular to the wafer stage 3. The Z-axis positioning module 4 adjusts the displacement value of the stress detection sensor 2 along the Z direction according to different wafer thicknesses to meet the working distance of the stress detection sensor 2; The wafer stage 3 is fixed on the R-axis rotating platform 5; The R-axis rotating platform 5 is fixed on the X-axis transfer module. The wafer stage 3 moves along the X-axis and R-axis directions to realize the acquisition of data of the entire wafer surface. The X-axis module 6 and the R-axis rotating platform 5 drive the wafer stage 3 to complete the measurement of the data of the entire wafer surface. Then, the measurement data is processed and calculated to obtain the stress data of the wafer.

[0019] The specific testing process is as follows: The wafer is placed on the wafer stage 3 by a robotic arm or manually. The stage is moved to the working position by the X-axis, and the stress detection sensor 2 is moved to the working distance by the Z-axis module. The stress detection sensor 2 emits a measuring beam to the wafer surface. At this time, the R-axis rotating platform 5 rotates, and the stress detection sensor 2 performs radial step scanning to collect data. Then, the radius of curvature is calculated, and the stress value is converted using the Stoney formula, which is as follows: Where σ represents the stress value of the wafer, E t It is the elastic modulus of the wafer material, ν t Here, R is the Poisson's ratio of the wafer material, h is the radius of curvature of the wafer after bending, and h is the thickness of the wafer. This formula can accurately calculate the stress value of the wafer by measuring the radius of curvature of the wafer and combining the material properties and thickness of the wafer.

[0020] This process achieves non-destructive quantitative detection of physical deformation and residual stress through the closed-loop collaboration of three major modules: motion control, optical detection, and data processing. Based on the Stoney formula, this invention utilizes a non-contact detector with a rotary + radial composite scanning motion mechanism to achieve full wafer coverage scanning. It also employs an integrated design of the piezoelectric sensor and vibration-damping base within the vibration compensation hardware module, resulting in high integration. This allows for direct embedding into semiconductor production line equipment and achieves high-precision non-contact measurement with a resolution of 0.01nm (height) and a stress detection accuracy of ±0.05MPa, superior to X-ray diffraction (±0.5MPa). This avoids wafer damage and is suitable for ultra-thin wafers (thickness <100μm). Furthermore, it exhibits strong resistance to environmental interference, with a tilt tolerance ≤15° and vibration suppression >60dB.

[0021] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A non-contact wafer stress testing instrument, characterized in that: The system includes a vibration compensation hardware module, a stress detection sensor, a wafer stage, a Z-axis positioning module, an R-axis rotation platform, and an X-axis module. The stress detection sensor, wafer stage, Z-axis positioning module, R-axis rotation platform, and X-axis module are all based on the vibration compensation hardware module. The stress detection sensor is fixed to the Z-axis positioning module, which drives the stress detection sensor to move along the Z-direction perpendicular to the wafer stage. The wafer stage is fixed to the R-axis rotation platform. The R-axis rotation platform is fixed on the X-axis transfer module, and the wafer stage moves along the X-axis and R-axis directions to acquire data from the entire wafer surface. The vibration compensation hardware module includes a vibration-damping base and a mounting bracket. The lower end of the mounting bracket is fixed to the upper surface of the vibration-damping base, and the Z-axis positioning module is installed on the inner wall of the mounting bracket. A piezoelectric accelerometer is installed inside the vibration-damping base. Vibration data is fed back to the signal processor in real time through the piezoelectric accelerometer, and environmental vibration interference is eliminated through algorithm correction.

2. The non-contact wafer stress testing instrument according to claim 1, characterized in that: The Z-axis positioning module adjusts the displacement value of the stress detection sensor along the Z direction according to different wafer thicknesses to meet the working distance of the stress detection sensor.

3. The non-contact wafer stress testing instrument according to claim 1, characterized in that: The X-axis module and R-axis rotating platform drive the wafer stage to complete the measurement of the entire surface data of the wafer, and then process the measurement data to calculate the stress data of the wafer.

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