基于白光三角法的芯片封装凸点高度测量

Bump height measurement of chip packaging based on white light triangulation

为了实现芯片封装凸点(Bump)高度的测量,建立了基于白光三角法的测量系统,并提出了一种复杂背景下Bump高度的测量方法。根据提出的测量模型搭建了Bump高度测量系统,利用U-Net深度学习模型进行光条图像的分割并结合灰度重心法和插值法提取完整的光条中心,以克服复杂背景的干扰。然后,对测量系统进行标定以确定像素值与实际高度值的对应关系。最后,通过函数拟合的方式确定Bump的高度。实验结果表明:Bump高度的测量重复性平均值为0.21 μm,标准差为0.095 μm;测量平均误差为-0.04 μm,标准差为0.408 μm。该方法在复杂背景下对Bump高度的测量精准度高、稳定性好,可满足芯片封装中晶圆Bump共面性在线检测的要求。

To measure the bump height of chip packaging,a measurement system based on white-light tri-angulation was established,and a method for measuring the bump height in a complex background was pro-posed.First,the bump-height measurement system was built according to the proposed measurement model.Next,the U-Net deep learning model was used to segment the light stripe image,and the gray-scale barycenter method and interpolation method were combined for extracting the complete light stripe center to overcome the interference of the complex background.Subsequently,the measurement system was calibrated to determine the corresponding relationship between the pixel value and the actual height value.Finally,the height of the bump was determined via function fitting.The experimental results indi-cate that the average repeatability of bump-height measurement is 0.21μm,with a standard deviation of 0.095μm;the average measurement error is-0.04μm,with a standard deviation is 0.408μm.In this study,bump-height measurement with high accuracy and robustness in a complex background was real-ized,which can satisfy the requirements of online detection of wafer bump coplanarity in chip packaging.