Finding the true on-product hot spots (patterning defects) by High Volume Manufacturing (HVM) inspection tools is increasingly challenging as the process window margin shrinks. It is a common practice nowadays to use Optical Rule Check (ORC) results by computation lithography to provide “care areas” to increase the signal to noise level of the inspection tool, thus improving the detection accuracy. The care area defined by the traditional method of contour-based process window checks may not be good enough. There are cases where real yield killers were not caught by contour-based checks, resulting in missing errors during wafer inspection as well. In this paper, we expand the traditional process window checks to a broader lithographic spectrum. The method allows us to utilize additional limiters such as max intensity, contrast, and NILS checks in combination with normal CD-based checks such as bridge, pinch, or process window bands to achieve higher accuracy in failure locations. This compound check will be trained using existing on product failure data obtained from low and high resolution wafer inspection as well as eTest and yield data. The combination of contour and intensity-based checks is demonstrated to be more effective in capturing the wafer hot spots for new products. The various usage models of such enhanced ORC will also be discussed.
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