B Cl 3 based plasmas exhibit promising plasma chemistries to etch high-k materials and, in particular, HfO2, with a high selectivity over SiO2 and Si substrates. The authors report on the mechanisms involved in the etching of HfO2, SiO2, and poly-Si substrates in BCl3 plasmas. X-ray photoelectron spectroscopy analyses help in understanding the mechanism driving the high etch selectivity between HfO2 and silicon-containing substrates. The ion energy plays an important role in the etching mechanisms since it controls a transition between a BCl-like deposition on the substrate and its etching by ionic bombardment. The ion energy threshold above which etching occurs is different from one substrate to another, being lower for HfO2 than for Si substrates. Indeed, BClx deposition forms more easily on poly-Si or SiO2 rather than on HfO2 surfaces, because boron reacts with Si atoms to form Si–B bonds initiating the growth of BClx polymer on Si-containing surfaces, while on HfO2 surfaces, boron is directly involved in the etching and reacts with oxygen to form volatile BOCl etch products.

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Some specific applications, such as optical devices, require non-conventional layouts. In this context, the known OPC solutions developed during decades and optimized for CMOS planar applications are facing significant challenges. Standard design files format as well as OPC algorithms are indeed suitable for 0-45-90° edges (also called Manhattan layouts) and other angle edges can lead to bad OPC results, huge run time, large file size, and even run crashes.While innovative developments are on going from OPC suppliers' side, we have to use smartly the conventional OPC platforms to achieve accurate, fast and cost-effective solutions.Taking the example of optical diffusers application, we will discuss the implementation of such an OPC flow, including rule-based correction, SRAF insertion, model-based correction, and mask sign-off strategy.

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