High resolution backside fault isolation technique using directly forming Si substrate into solid immersion lens

We developed a new backside fault isolation technique based on the concept of the solid immersion lens, which can be applied for the 90 nm technology node. This technique improves spatial resolution by less than 0.18 μm at λ=1.3 μm and also enhances the sensitivity in the infrared-emission microscope (IR-EMS) and the infrared-optical beam induced current (IR-OBIC) technique by directly forming the Si substrate into a hemisphere. The process of "forming the Si substrate into a solid immersion lens" (FOSSIL) will be a fundamental capability necessary to support the analysis of future minimum geometry devices.