Detection of a New Surface Killer Defect on Starting Si Material using Nomarski Principle of Differential Interference Contrast

End of line device failure analysis and inline defectivity investigations revealed a previously undetected surface killer defect that was generated during a front side polish process of integrated circuit Si substrate starting material. A surface defect impacting over 20% of the wafer was found to exist prior to Si Epitaxial growth. This surface defect was discovered by using the Surfscan SP1 TBItrade inspection tool and evaluated using the Leica INS 3000trade and the KLA-Tencor EV300 SEMItrade. A Bright Field inspection based upon the Nomarski principle of Differential Interference Contrast (DIC) was employed and revealed this previously undetected polish defectivity mechanism and this inline detection allowed the Si supplier to implement root cause fixes for the issue. These newly detected defects have a very low surface profile and were below the detection range of typical inspection methodologies currently in use for starting Si substrates. The implementation and use of Nomarski DIC inspection principles were highly manufacturable with regard to tool to tool sensitivity matching and the portability of inspection recipes. The new DIC inspection method enabled the Silicon supplier to identify the root cause of a new defect mechanism and extend the defect detection capability of an existing tool set.