KEYWORDS: Line edge roughness, Line width roughness, Etching, Lithography, Process modeling, Optical lithography, Back end of line, Deposition processes, Spatial frequencies
For the first time, process impact on line-edge roughness (LER) and line-width roughness (LWR) in a back-end-of-line (BEOL) self-aligned quadruple patterning (SAQP) flow has been systematically investigated through predictive 3D virtual fabrication. This frequency dependent LER study shows that both deposition and etching effectively reduce high frequency LER, while deposition is much more effective in reducing low frequency LER. Spacer-assisted patterning technology reduces LWR significantly by creating correlated edges, and further LWR improvement can be achieved by optimizing individual process effects on LER. Our study provides a guideline for the understanding and optimization of LER and LWR in advanced technology nodes.
Self-triggering pulsed laser ranging, a novel pulsed laser ranging method, can ease the trade-off between ranging precision and measurement speed in the traditional laser ranging technique. Theoretical analysis and system design for time-of-flight measurement, which determines both the ranging precision and the measuring speed of self-triggering pulsed laser ranging, is performed. An experiment on self-triggering pulsed laser ranging is reported, in which submillimeter (better than 0.5 mm) precision is achieved over a 20-m range.
A new type of Q-switched pulsed lasers (CPQL, Controllable Passively Q-switched Laser) is presented. The laser is composite of a passively Q-switched laser with a saturable absorber and a controlling LD with a focus system. The performance of the laser output pulses, including the pulse energy, pulse width, pulse generation moment and repetition frequency, can be actively controlled by the operator with the controlling LD. The new type laser is discussed theoretically and the experiment results are present. Compare to the ordinary Q-switched laser, including passively Q-switched lasers and actively Q-switched lasers, CPQL’s have higher performance and will find important applications in many fields.
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