Metrology Challenge for Monitoring Post CMP Pattern Through CD SEM

With the increase in semiconductor design and process complexity, the need for manufacturing process monitor is increasing. Optical critical dimension (OCD) spectroscopy is widely used in measurement and control of chemical mechanical polishing (CMP) process in semiconductor manufacturing because of its nondestructive and high throughput characteristics. However, due to the limitation of the design at test pad and the shortage of evaluating roughness in image, it has encountered some measurement challenges in monitor post-CMP pattern. Therefore, this work overcomes the weakness of conventional electron beam metrology and comprehensively evaluates the feasibility of critical dimension scanning electron microscopy (CDSEM) for post-CMP stage patterns by testing various beam voltage and currents to optimized imaging as well as a special algorithm to optimized the calculation of critical dimensions.