A Digital ULSI Inspection Method Using Parallel Scanning Confocal Microscope

In ULSI fabrication, the design rule scaled up to 0.25um and the complex multiple layer structure prevent from applying the traditional optical microscope of which resolution is about 0.4um. Considering the situation, we have developed a ULSI inspection system based on the scanning parallel confocal microscope. In this paper, we present the feature of the computer aided parallel scanning confocal ULSI inspection system. First, we describe the principle of the scanning parallel confocal microscope with the stress on two key points of the semiconductor observation. One is the high resolution capability. We show an image of the resolution test with 0.2um line and space pattern drafted by Electron Beam Lithography to confirm the capability for the ULSI inspection. The other point is optical sectioning imaging. The imaging is very important to examine the ULSI surface of the multiple layer and high aspect ratio without the defocused energy of another area. Considering the optical sectioning capability, we compare the parallel scanning confocal images of the ULSI device with the traditional microscope image in the digital inspection of the high aspect ratio's surface of multiple layer. We submit an interested layer in the digital confocal microscope image. Finally, we summarize the performance of the proposed system as the ULSI inspection.