Research On The Key Technology Of Detection For The Defects Of Chip Substrate Based On Phase Shifting Interferometry

The 3D Measurement based on Phase Shifting Interferometry has many advantages including automation, high-precision, non-touching and high-speed. In fact, the purpose of phase shifting is to control the precision stepper to get the multi-frame figures with different phase distribution interference. Then we can get the wrapped phase based on the corresponding mathematical formula. After giving the wrapped phase effective unwrapping operation,the 3D surface of the unwrap phase by combined it with the Phase-Height relations could be reconstructed. In these processes such as the packaging process of chip, this technology could be applied in product failure detection to get the detection and analysis of its 3D morphology. In this way, we can filter these substandard products rapidly.In this paper, we build a hardware platform to measure 3D surface topography of the chip substrate by analyzing the basic requirements in the detection. And we made a detailed analysis of these major problems including how to remove the noise of the wrapped phase and reconstruct an ideal one then unpack it, how to judge the wrapped phase phenomenon, and the surface of the chip qualification test program, etc. The main content of this work includes the followings:1) By analyzing the actual industrial production, we built the suitable hardware platform, and completed the calibration to make it meet the requirement of basic needs of 3D Measurement with high precision, non-touching and high-speed qualities;2) After completed the multi-frame interference collection experiments, we get the wrapped phase by calculating, and combining the value of the phase to analyze the distribution of noise briefly;3) By choosing several typical unwrap algorithm, we discussed the practicability of applying the algorithm to unwrap phase on the chip samples, and compared the pros and cons of these algorithms;4) Combined with line scanning method, we analyzed the phase noise sources in detail. Then according to the image filtering, least squares fitting and the spline interpolation theory, we put forward an ideal wrapped phase reconstruction scheme. With the help of the ranks of integral method, we can realize the rapid unwrapping calculates.5) In light of the foregoing, we present the method to test the existing of phase wrapped phenomenon, and then to test the eligibility of chip surface topography rapidly by calculating the roughness parameters.The experimental test results show that the techniques of defect detection on chip substrate surface based on phase shifting interferometry has the advantages of high-precision and high-accuracy. At the same time, it can satisfy the test requirements such as it can achieve non-touching, automation, high-precision, and high-speed in chip packaging process.