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In traditional 3D NAND design, peripheral circuit accounts for 20-30% of the chip real-estate, which reduces the memory density of flash memory. As 3D NAND technology stacks to 128 layers or higher, peripheral circuits may account for more than 50% of the overall chip area. On the contrast, the XtackingTM technology arranges array and logic parts on two different wafers, and connects the memory arrays to the logic circuit by metal VIAs (Vertical Interconnect Accesses) to achieve unprecedented high storage density as well as DRAM level I/O speed. As a consequence, it becomes increasingly significant to monitor metal VIAs depth before wafer bonding process as to ensure reliability of array-logic connections. Currently, AFM (Atom Force Microscopy) is the main stream method of VIA depth monitoring. Apparently, AFM wins the battle of precision, however the low throughput limited its usage in mass production. In order to accomplish the requirement of VLSI production, a WLI (White Light Interference) metrology is revisited and a novel WLI method was developed to monitor VIAs depth. Basically there are two major limitations that keep WLI tools from wider use, transparent film impact and diffraction limitation. In this work, the engineering solutions are illustrated and inline dishing measurement is achieved with high accuracy and precision.

Evaluating the effects of users' demand response (DR) accurately has been increasingly important with the promotion of demand response. However, there exists a relatively large error in the generic baseline calculation method because it ignores the operating characteristics of air conditioning. This paper establishes an air conditioning's DR effects evaluation model and proposes a baseline calculation method based on the difference between indoor and outdoor temperature. It is shown in case study that the method proposed in this paper can improve accuracy of baseline calculation effectively.