White Paper posted on Oct 8, 2017

Photoresist Residue Detection in Advanced Packaging

from IMAPS 50th International Symposium on Microelectronics 2017

Semiconductor manufacturers are continuously driving efforts to put more computing power and speed into less volume. At the same time, consumers are demanding devices with more functionality that integrate a variety of interconnected circuit types. The result has been an increasing reliance on advanced packaging technologies that use fab-like processes to integrate multiple chips and to provide the increased I/O capability required. With continued focus on device miniaturization, the rapid detection of trace chemical residue during intermediate processing steps becomes increasingly difficult. In the lithography area, detection of polymer residue on wafer surfaces presents special opportunities. One area of opportunity for the detection of lithographic polymer residue takes advantage of the fact that these materials possess unique optical properties not found in metals or other inorganic materials used in semiconductor manufacturing. Rudolph Technologies has submitted patent applications for a novel defect illumination technique that offers key advantages over traditional white light inspection. This paper will present the results of using this inspection technique for the detection of photoresist residue on test wafers as well as on actual customer devices. Sample data included herein are representative of advanced packaging technology used today by a wide range of semiconductor manufacturers and OSAT facilities. While this novel inspection technique will not be a panacea for all trace residue detection problems, it offers a method complementary with bright field or dark field inspection when these two traditional inspection methods lack the sensitivity required.