Semiconductor complexity continues to increase as the industry pushes the limits of 2D logic and DRAM scaling using EUV lithography and transitions to intricate 3D architectures including Gate-All-Around (GAA) transistors, high-aspect ratio DRAM, and 3D NAND memories & advanced interconnects. This complexity creates significant challenges. Defects become more critical and difficult to detect as chip patterns shrink, as 3D structures proliferate. The ability to detect and characterize tiny, buried defects is surpassing the imaging capabilities of conventional eBeam technology. Three Ebeam Technologies come in. One, for high wafer coverage at leapfrog resolution is cold field emission (CFE) technology. CFE operates at room temperature, resulting in narrower, higher-energy electron beams that produce higher resolution and faster imaging speed compared to conventional thermal field emission (TFE) technology. CFE eBeam systems are tuned for resolution or they can lower the resolution to match that of TFE, with significantly faster imaging speed. Second, for high aspect ratio etch control at very low imaging signal, leveraging on advanced Back Scattered Electrons (BSE) imaging innovations. Third, ultra-thin features sensitive EUV litho control. As Industry’s CD SEM and Optical CD workhorses struggle with contrast to measure the ultra- thin EUV resist features, and not damage them with dose. New low energy, low dose, high resolution CD SEM technology is introduced. Until recently, use of CFE, BSE, and lower energy systems has been limited to lab environments. In CFE, the stability of the eBeam column was insufficient for the stringent requirements of high-volume semiconductor manufacturing. Two innovations solved the stability challenge. One, an extreme ultra-high vacuum inside the eBeam column, nearly the vacuum level found in outer space! The second is a cyclical self-cleaning process that continuously removes contaminants from the CFE source, enabling stable and repeatable performance for high-volume manufacturing . For high aspect ratio, innovations in BSE efficiency take place, and for ultrathin EUV resist imaging, high resolution, low landing energy, low signal collection efficiency modes were introduced.
By enabling chipmakers to discover defects and measure features they’ve never been able to see before, these eBeam innovations help accelerate development and production of advanced process nodes.