Microscopy needs for next generation devices characterization in the semiconductor industry

Abstract

In this paper we present the different imaging based techniques used in the semiconductor industry to support both manufacturing and R&D platforms at STMicroelectronics. Focus is on fully processed devices characterization from large structure (3DI, Imager sensors) to advanced MOS technologies (28-20 nm). Classical SEM and TEM (mainly EFTEM) based techniques are now commonly used to characterize each step of the semiconductor devices' process flow in terms of morphology and chemical analysis. However to address specific issues, dedicated imaging techniques are currently being investigated. With the "High-k Metal Gate" stack involved in the more advanced MOS devices (28-20 nm), new challenges occur and therefore advanced characterization is mandatory. Some relevant examples are pointed out through (STEM) EELS and EDX experiments. Analysis of stressors mainly used to improve carrier mobility in next generation devices, is also presented with different approaches (NBD, CBED and Dark-field holography). Advanced STEM and AFM based techniques applied to characterize dopants and junction in MOS devices and also in more relaxed structure such as imager sensors is discussed too. Concerning back-end (interconnects) and 3D integration (3DI) issues, focus is on nano-characterization of defects by classical techniques (EFTEM, STEM EELS-EDX) and with dedicated ones still in development. To illustrate this topic some 3D FD3/SEM and E-beam tomography experiments are presented. Examples of microstructure and texture determination in poly-crystalline materials such as copper line by coupling SEM/EBSD and TEM techniques are also shown.