| Popis: |
Background: Decomposing an observed variation in critical dimension (CD) into its sources of variation is an important analysis, but it is often tedious and prone to error. For EUV processes, identifying the magnitude of stochastic variations is especially important and relevant. Aim: An automated process for decomposing CD errors into its sources will aid in the analysis of a specific EUV process. Approach: MetroLER offline metrology software has been updated to perform automated sources of variation analysis, including the measurement and subtraction of systematic and random components, such as across-SEM-field signatures and random metrology errors. Results: For a staggered array of 24 nm contacts holes on an 80X46 nm pitch, the total CD uniformity (CDU) of about 3.3 nm included a global CDU across wafer of about 1.0 nm, a systematic mask contribution of 1.7 nm, systematic metrology contribution of 1.0 nm, and a random metrology contribution of 0.67 nm (all 3σ), leaving a stochastics-only CDU of about 2.6 nm. Conclusions: Careful consideration of the systematic and random components in CD measurement variations enables measurement of the stochastic contribution to a state-of-the-art EUV contact printing process. The contribution of metrology error |
