Use of layout automation and design-based metrology for defect test mask design and verification
This paper studies the impact of shape and local environment (pattern layout) on the ability to detect defects on the reticle and the extent to which they affect the dimension of the printed image on the wafer. The authors have made extensive use of design information to perform a thorough evaluation. OPC software was used to generate mask data that was comparable to product mask data. Defects were placed on the post-OPC layout and OPC software was also used to simulate the dimension of the defective features as printed on the wafer. "Design Based Metrology" was used to create accurate metrology recipes to support wafer and mask metrology. Ultimately the procedures described in this paper allow a direct correlation to be made between reticle inspectability and the impact of the same defects on wafer CD. Data is presented for the case of the Contact Hole layer of a "65nm" Logic technology, though the methods described in the paper are applicable to all layers.
Production evaluation of automated reticle defect printability prediction application
The growing complexity of reticles and continual tightening of defect specifications causes the reticle defect disposition function to become increasingly difficult. No longer can defect specifications be distilled to a single number, nor can past simple classification rules be employed due to the effects of MEEF on actual printing behavior. The mask maker now requires lithography-based rules and capabilities for making these go/no-go decisions at the reticle inspection step. We have evaluated an automated system that predicts the lithographic significance of reticle defects using PROLITHTM technology. This printability prediction tool was evaluated and tested in a production environment using both standard test reticles and production samples in an advanced reticle manufacturing environment. Reference measurements on Zeiss AIMSTM systems were used to assess the accuracy of predicted results. The application, called the Automated Mask Defect Disposition System, or AMDD, models defective and non-defective test and reference images generated by a high-resolution inspection system. The results were calculated according to the wafer exposure conditions given at setup such that the reticle could be judged for its 'fitness-for-use' from a lithographic standpoint rather than from a simple physical measurement of the film materials. We present the methods and empirical results comparing 1D and 2D Intensity Difference Metrics (IDMs) with respect to AIMS and discuss the results of usability and productivity studies as they apply to manufacturing environments.
Review of Literature on Probability of Detection for Magnetic Particle Nondestructive Testing
Abstract : A critical review of the available literature concerning the minimum reliably detectable defect size aNDI for magnetic particle testing (MPT) in aerospace applications is presented. Four probability of detection (POD) studies relevant to detection of fatigue cracks in aircraft components were found over the period 1968 to 2011. As the statistical methods used in these four previous studies were either outdated or otherwise deficient, the original data were reanalysed using currently accepted techniques. A meta-analysis of the results is presented, with emphasis on statistical inferences for the defect size expected to be detected with 90% POD. It is shown that the minimum reliably detectable defect size aNDI = 2.0 mm currently specified by the Royal Australian Air Force for wet fluorescent magnetic particle inspection using the continuous method is consistent with estimates of the average performance of MPT derived from the reanalysis of the literature.