This paper provides details of a novel method developed to cover a tiny epoxy layer as an intermediate buffer on the site-specific surface defect using a micro-bush on the tip of a glass needle in a plucking system without sample surface damage and localization problems. It describes the method and some real cases. The microstructures are investigated using an FEI Tecnai TF20 field emission gun transmission electron microscopy equipped with a high angle annular dark field detector, an energy dispersive X-ray spectroscopy, and Gatan image filter systems. The paper explains the micro-brushes and buffer layer preparation though figures and illustrations.

Electron tomography includes four main steps: tomography data acquisition, image processing, 3D reconstruction, and visualization. After acquisition, tilt-series alignments are performed. Two methods are used to align the tilt-series: cross-correlation and feature tracking. Normally, about 10-20 nm of fiducial markers, such as gold beads, are deposited onto one side of 100 mesh carbon-coated grids during the feature-tracking process. This paper presents a novel method for preparing electron tomography samples with gold beads inside to improve the feature tracking process and quality of 3D reconstruction. Results show that the novel electron tomography sample preparation method improves image alignment, which is essential for successful tomography in many contemporary semiconductor device structures.

One of the approaches to visualize dopant regions is to use SEM dopant contrast. In silicon, the technique is rather more problematical, presumedly because typical pn-junction built-in potentials are three times smaller. Dapor et al. have reviewed the literature, and made Monte Carlo simulations of dopant contrast. This paper shows that a surface insulator can be used to improve the dopant contrast between p- and n-regions obtainable on SEMs equipped with in-lens SE detectors. Based on the experimental results, it is clear that an organic material can enhance the dopant contrast effect by around 10%, provided that it is exposed to the electron beam. It is therefore reasonable to assume that the dopant contrast enhancement is due to charging of the insulator. Dopant contrast is also influenced by imaging position and scanning time. The method is easy, repeatable, and obtains clear results quickly, solving analysis cases which are quite intractable.

It is well known that pursuing the miniaturization of devices to lower the cost and increase high-speed performance are extremely important goals for dynamic random access memory (DRAM). Therefore, electron tomography has a high potential for application to novel generation DRAMs. In this article, several real-case examples of electron tomography on 90 nm technology DRAM, including barrier layer step coverage, via fill process observations and defect analysis are reported. These cases were demonstrated to show the applications of bright field-transmission electron microscope (BF-TEM) and HADDF- scanning transmission electron microscope (STEM) tomography to analyze barrier layer step coverage, defects, and W fill quality in advanced DRAM. By appropriate use of BF-TEM or HAADF STEM tomography, optimal information for failure analysis, root cause clarification, and subsequent process improvements can be obtained. Electron tomography holds significant advantages in comparison to traditional TEM imaging for appropriate cases.

This paper demonstrates a novel method of XTEM sample preparation for site-specific surface defect analysis using backside polishing. Analysis of three different types of site-specific surface defects was demonstrated using a novel backside XTEM sample preparation method. The details of the backside XTEM sample preparation method and some examples are reported in this paper. Comparing to Auger electron spectrometry (AES) results on similar defects, more detailed and precise information is observed using TEM analysis with this method. It is therefore a complementary technique to traditional AES analysis on surface defects for contamination with atomic level concentration. From the results, the sample preparation method can produce a clean, pristine surface that is well characterized and could be reproduced, successfully.

The capabilities of analytical transmission electron microscopy (TEM), such as high spatial resolution, micro-chemical analysis, etc., have led to an increasingly essential role for TEM-based analysis in process development, defect identification, yield enhancement, and root-cause failure analysis with the dynamic random access memory (DRAM) industry. In this article, several examples are reported to carry out the applications of TEM and secondary ion mass spectrometry on crystal defect analysis and electronic characteristics of advanced 512 Mb DRAMs.

This article presents a novel method to provide whole Deep Trench (DT) profile inspection. Bevel angle top-down polishing is used on pre-rotated substrates instead of traditional cross-section cleaving. This method can feedback the precise DT profile shape at specific depths to the production line for process tuning and troubleshooting.

X-ray photoelectron spectroscopy (XPS) is a very popular tool for identification of the chemical state of fluorine contamination on aluminum (Al) bond pads. To date, as far as the authors are aware the detailed microstructures of fluorine corrosion on bond pads have not been reported. This paper reports the microstructure evolution of fluorine corrosion on bond pads in a plastic box under specific environment conditions by using transmission electron microscopy (TEM), optical microscopy, focused ion beam and scanning electron microscopy (SEM). The elemental distributions and chemical bonding were performed by using Gatan Image Filter/TEM, energy dispersive X-ray/Scanning TEM (STEM), Auger electron spectroscopy and XPS, respectively. On Al pads with 35 atomic %, fluorine residual, corrosion was observed after around 10 days of storage and became more severe with time. The corrosion layers consist of nano-crystalline and amorphous for both single and double-layer structures.

A technique is described which allows the precise measurement of the surface area of the dielectric layer of a DRAM deep trench (DT) capacitor. It uses precision FIB sectioning, and allows determination with arbitrary accuracy. It can be used for measuring random DTs in a region of interest for process monitoring, and can also be used for a single target trench in the case of failure analysis.

A systematic approach based on top-down polishing and voltage contrast is reported for DRAM WL-BL leakage analysis. It has the advantage of very low NDF and obtains high quality data for process root cause analysis. It is compared and contrasted with alternative techniques, and future developments are discussed.

A technique for localisation of defects in periodic integrated circuit microscope images is described. It uses a fully automatic and fine tunable algorithm based on Fourier transform spatial filtering with a specially developed algorithm. Applicable to any digital failure analysis imaging tool, it produces fast, automatic results to speed up the FA localisation function.