No abstract

Without the ability to detect potential yield-limiting defects in-line, the yield learning cycle is severely crippled, compromising the financial success of chip makers. As design rules shrink, device yield is seriously affected by smaller size particle and patterned defects that were not important in the past. These mechanisms are becoming more difficult to detect with current defect detection tools and techniques. The optical defect inspection tools that are currently available do not adequately detect defects, while scanning electron microscope (SEM) based inspection tools are too slow. With each successive technology node, optical inspection becomes less capable relative to the previous technology. As sensitivity is increased to detect smaller defects, the nuisance defect rate increases commensurately. Line-edge roughness (LER) and subtle process variations are making it more difficult to detect defects of interest (DOI). Smaller defects mean smaller samples available for energy dispersive x-ray analysis (EDX), necessitating an improved or new methodology for elemental analysis. This paper reviews these and some other challenges facing defect metrology at the 45 nm technology node and beyond. The challenges in areas of patterned and unpatterned wafer inspection, defect review, and defect characterization are outlined along with proposed solutions. It also provides an overview of several ongoing projects conducted at International SEMATECH Manufacturing Initiative (ISMI) to address these challenges.

As Moore's Law indicates, pattern feature sizes have become smaller and smaller, increasing the need for more critical metrology and inspection methodologies in integrated circuit fabrication. Critical methodologies are especially required in the inspection area where more critical defect definition methods are needed for the accurate evaluation of inspection tools.In traditional defect definition, we must use only normal critical dimension (CD) measurement results with manual measurement methods. This one dimensional definition method gives defect size information that is insufficient for accurate evaluation. In addition, a lot of measurement uncertainty, such as human errors, measurement errors, and systematic errors, are included in the data derived from manual measurement methods. Because of these issues, evaluation results will differ from person to person and under other environmental influences.

We developed automated contact inspection system using in-line CD SEM and applied to monitor the contact etching processes. As the design rule shrinks, monitoring of the contact etching, which cannot be detected by the conventional optical inspection systems, are becoming one of the most critical issues in semiconductor process. Though there are e-beam based inspection systenis or manual inspection sequence with in-line SEM (Scanning Electron Microscope), monitoring small and electrical defects has a few fundamental limitations. E-beam inspection systenis have low throughput and the high price as a mass production tool. And in case of the manual inspection system, the inspection result depends on operator and it is dificult to quantify the defect data. We have developed an autoniated contact inspection system to overcome these Limitations. The system is composed of the data processing system arid the in line SEM (Scanning Electron Microscope). Automated in line SEM inspects and stores the images of specified points on the wafer. Data processing system receives and manipulates the images to tell the etching problem. It was shown that scanning electron image of the contact is related with failures such as insuficient etching or residuals inside the contact.