In order to successfully develop and manufacture semiconductor chips, in-line inspection is extremely important. Optical and e-beam inspection are the two major defect inspection approaches used for semiconductor manufacturing. As critical dimensions continue to shrink with each new technology, killer defects are becoming smaller and smaller, reducing the effectiveness of optical inspection, which is resolution limited. A growing number of defect types are just not detectable with optical inspection. A partial solution is to adjust inspection parameters to run “hot”, but then the few defects of interest that are captured are buried in large numbers of nuisance defects. E-beam inspection (EBI), in addition to it’s unique role of detecting buried defects using voltage contrast (VC), is able to detect these smaller defects, but suffers from throughput constraints. This is because of EBI’s substantially smaller pixel size, which takes much longer to tile across the wafer surface, and a lower sampling frequency, because electrons aren’t as prevalent as photons. In R&D, this is not as much of a limitation, with EBI commonly deployed as a metric for many physical defects beyond optical inspection resolution as well as lithography related use cases such as process window qualification (PWQ) and EUV print check. However, EBI’s adoption during yield ramp and high volume manufacturing (HVM) is limited by these throughput constraints. To address this issue, HMI is developing multi-beam inspection (MBI) systems [1,2]. This latest paper covers three new topics. First, new milestones were achieved in the last year, including simultaneous operation of all beams and defect detection while in this mode, will be reviewed. Second, the importance of minimizing cross-talk between beamlets for MBI and the cross-talk performance of our latest tool is discussed. Finally, simulations of the anticipated throughput gains achievable for a range of physical and voltage contrast inspections for the current system are presented. These throughput gains vary widely and are useful in prioritizing certain inspections over others for practical use, as well as understanding the limiting factors for laggard inspections. Potentially some of these factors can be alleviated. Going forward, the plan is to continue to aggressively increase the number of beamlets while simultaneously further improving the resolution. Overall the HMI MBI program is on track with tool shipments to select customers in the very near future.

EUV lithography has been adopted in most advanced semiconductor manufacture fabs, enabling the next step in design rule scaling. With this progress, minimum critical defect size has become smaller and harder to detect. Defect inspection equipment suppliers must therefore in parallel provide a significant step up in inspection sensitivity at a reasonable throughput. Optical inspection tools are facing an unprecedented challenge because defects less than 10nm are not optically visible. As an alternative, semiconductor manufacturers have turned toward e-beam inspection. E-beam inspection is widely used in R&D to shorten development cycle-time and selectively used in high volume manufacturing (HVM) for process monitoring, however currently it is not fast enough for large-scale replacement of optical inspection. Our approach to address this shortcoming is to combine cutting edge multiple-beam technology with a cutting edge positioning system/computation architecture to create a next generation e-beam inspection system capable of scanning with multiple electron beams at the same time. This paper reports on the progress in developing such a system as well as future multi-beam inspection applications.

Pattern defects and uninvited particles (residuals) probably appear on Mask and Wafer in any manufacturing process of integrated circuits (ICs) and impact the final yield of IC chips. To ensure a high yield, defect inspection of Mask and Wafer has been broadly adopted for monitoring many processes in high volume manufacturing (HVM) and shortening development cycle-times of critical processes in R&D. In HVM optical inspection tools have played a major role, and in R&D e-beam inspection tools have been a critical role. For the 7nm technology node and beyond, minimum size killer defects are going to be invisible for optical inspection tools, and e-beam inspection tools are too slow to capture smaller killer defects in an acceptable throughput. Accordingly, enhancing e-beam inspection tools in throughput has become an issue demanding prompt attention, and one promising solution is multi-beam inspection (MBI) technology. We are developing a MBI tool, which combines our cutting edge technologies in multi-beam electron optics, sample stage, scanning strategy and computational architecture. In this paper we will introduce MBI technology and development progress of our MBI tool, and will discuss future application of MBI technology.