Richard B. Irwin

APPLICATIONS OF THE FIB LIFT-OUT TECHNIQUE FOR TEM SPECIMEN PREPARATION

A site‐specific technique for cross‐section transmission electron microscopy specimen preparation of difficult materials is presented. A focused ion beam was used to slice an electron transparent membrane from a specific area of interest within a bulk sample. Micromanipulation lift‐out procedures were then used to transport the electron‐transparent specimen to a carbon‐coated copper grid for subsequent TEM analysis. The FIB (focused ion beam) lift‐out technique is a fast method for the preparation of site‐specific TEM specimens. The versatility of this technique is demonstrated by presenting cross‐sectioned TEM specimens from several types of materials systems, including a multi‐layered integrated circuit on a Si substrate, a galvanized steel, a polycrystalline SiC ceramic fiber, and a ZnSe optical ceramic. These specimens have both complex surface geometry and interfaces with complex chemistry. FIB milling was performed sequentially through different layers of cross‐sectioned materials so that preferential sputtering was not a factor in preparing TEM specimens. The FIB lift‐out method for TEM analysis is a useful technique for the study of complex materials systems for TEM analysis. Microsc. Res. Tech. 41:285–290, 1998.

Probing nanoscale local lattice strains in advanced Si complementary metal-oxide-semiconductor devices

Local lattice strains in nanoscale Si complementary metal-oxide-semiconductor (MOS) transistors are directly measured by convergent beam electron diffraction (CBED). Through both high spatial resolution and high strain sensitivity of the CBED technique, compressive strains on the order of 10−3 from a p-type MOS transistor with a sub-100nm gate length are detected. One-dimensional quantitative strain mapping is demonstrated. The tensile strains from a ⟨100⟩ channel n-type MOS transistor are observed at the ⟨910⟩ zone axis. It is found that the strain increases with the thickness of the silicon nitride-capping layer, which is consistent with the device’s electrical behavior.

Using a zone axis for convergent beam electron diffraction measurements of lattice strain in strained silicon

Convergent beam electron diffraction patterns of silicon from the gate channel region of a complementary metal‐oxide‐semiconductor transistor with recessed Si.82Ge.18 stressors were analysed using three zone axes: <230>, <340> and <670>. Values measured using these axes were compared with each other with regards to strain along the [] and the [001] directions. It was demonstrated that strain measurements made using all three axes showed reasonable agreement with each other: an increase in the [] compressive strain and a switch from compressive to tensile strain in the [001] with decreasing distance below the gate. It was also observed that the strain calculations using the <230> axis had the lowest uncertainty whereas the <670> axis allowed for measurements closest to the gate due to the improved lateral resolution at that tilt angle.

Probing Nanoscale Local Lattice Strains in Advanced Si CMOS Devices by CBED: A Tutorial with Recent Results

The experimental methodology to characterize the nanoscale local lattice strain in advanced Si CMOS devices by using Focused Ion Beam (FIB) system and Convergent Beam Electron Diffraction (CBED) is discussed. Through both high spatial resolution of Transmission Electron Microscopy (TEM) and high strain sensitivity of the CBED technique, compressive lattice strains in the order of 10 -3 from the nanoscale Si PMOS channel region are detected. The one-dimensional quantitative strain-mapping is performed by obtaining and simulating high quality CBED patterns with different zone axes such as and .