| 摘要 |
PURPOSE:To improve the precision and yield of wafer for LSI detecting the completion of an etching process by a method wherein the corrected image data are collected in terms of the comparison between the image data on the illumination distribution over background and those on the surface observation of the etched item. CONSTITUTION:When an etching process is started (1), firstly the illuminance distribution is measured (2) from background of observed image (3) to correct the image (4) in terms of these data. Next the crest values of stripe lines with the most conspicuous contrast change value are recorded as data processing (5). The sampling data are successively compared (6) with the preceding data to calculate the P1 point (the point where foundation material starts to be exposed) and the P2 point (the terminal point of etching process) in terms of the change value. The P2 point may be detected (c) by calculating the gradient angle i.e. the change value DELTAy/DELTAt of the sampling cycle DELTAt while alpha is a tabulated constant based on experimental data corresponding to the etching requirements. The image data dynamically collected at the interval of DELTAt and repeatedly processed in (3)-(7) as shown in figure may terminate (9) an etching process by means of cutting off a high frequency power supply subject to detection of the P2 point (c). |
