Minute variations in advanced VLSI manufacturing processes are well known to significantly impact device performance and die yield. These variations drive the need for increased measurement sampling with a minimal impact on Fab productivity. Traditional discrete measurements such as CDSEM or OCD, provide, statistical information for process control and monitoring. Typically these measurements require a relatively long time and cover only a fraction of the wafer area.Across array across wafer variation mapping ( AWV) suggests a new approach for high throughput, full wafer process variation monitoring, using a DUV bright-field inspection tool. With this technique we present a full wafer scanning, visualizing the variation trends within a single die and across the wafer. The underlying principle of the AWV inspection method is to measure variations in the reflected light from periodic structures, under optimized illumination and collection conditions. Structural changes in the periodic array induce variations in the reflected light. This information is collected and analyzed in real time.In this paper we present AWV concept, measurements and simulation results. Experiments were performed using a DUV bright-field inspection tool (UVision ™ , Applied Materials) on a memory short loop experiment (SLE), Focus Exposure Matrix (FEM) and normal wafers. AWV and CDSEM results are presented to reflect CD variations within a memory array and across wafers.

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The 22nm Spacer Self Aligned Double Patterning (SADP) process developed at Applied Materials' Maydan Technology Center was used to characterize small particle defects in the four critical steps of the process flow: Lithography, APF Etch, Spacer Deposition, Spacer Open. Small Particle defect contamination poses a risk to yield in each of the SADP process steps (Lithography, Deposition and Etch) and requires an understanding of their sources and impact on each subsequent step. The defect inspection was carried out using two different inspection platforms; DFinder TM which is designed for detection of 3D defects and UVision TM 3 which is designed for detection of 2D defects. Small particle defects (smaller than 60nm), in the Lithography and APF Etch process steps were shown to become "killer" defects at the Spacer Open step. More study is needed to develop inspection strategies based on a wider range of defect types.

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