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More sophisticated corrections of overlay error are required because of the challenge caused by technology scaling faster than fundamental tool improvements. Starting at the 45 nm node, the gap between the matchedmachine-overlay error (MMO) and technology requirement has decreased to the point where additional overlay correction methods are needed. This paper focuses on the steps we have taken to enable GridMapper™, which is offered by ASML, as a method to reduce overlay error.The paper reviews the basic challenges of overlay error and previous standard correction practices. It then describes implementation of GridMapper into IBM's 300 mm fabrication facility. This paper also describes the challenges we faced and the improvements in overlay control observed with the use of this technique.Specifically, this paper will illustrate several improvements:1. Minimization of non-linear grid signature differences between tools 2. Optimization of overlay corrections across all fields 3. Decreased grid errors, even on levels not using GridMapper 4. Maintenance of the grid for the lifetime of a product 5. Effectiveness in manufacturing -cycle time, automated corrections for tool grid signature changes and overlay performance similar to dedicated chuck performance

On-chip ultraviolet (UV) sources are of great interest for building compact and scalable atomic clocks, quantum computers, and spectrometers. However, few material platforms are suitable for integrated UV light generation and manipulation. Of these materials, thin-film lithium niobate offers unique advantages such as sub-micron modal confinement, strong nonlinearity, and quasi-phase matching. Despite these characteristics, its utilization in the UV has remained elusive because of the substantial sensitivity of standard quasi-phase matching to fabrication imperfections, the photorefractive effect, and relatively large losses in this range. Here, we present efficient (197 ± 5%/W/cm2) second harmonic generation of UV-A light in a periodically poled lithium niobate nanophotonic waveguide. We achieve on-chip UV powers of ∼30 µW and linear wavelength tunability using temperature. These results are enabled with large cross section waveguides, which leads to first-order UV quasi-phase-matching with relatively long poling periods (>1.5 µm). By varying the poling period, we have achieved the shortest reported wavelength (355 nm) generated through frequency doubling in thin-film lithium niobate. Our results open up new avenues for UV on-chip sources and chip-scale photonics through compact frequency-doubling of common near-IR laser diodes.