Specimen Preparation Method to Dual-Axis TEM Analysis Technique

Tuesday, October 13, 2015
West Hall 1 (Phoenix Convention Center)
S. G. Park (Samsung Institute of Technology) and S. Lee (Sungkyunkwan University)
We usually do Physical Failure Analysis (PFA) to visualize the failure in the semiconductor process. First, we find the site-specific target (or failed cell). And then, we should do de-processing which contains lapping and chemical etch. As the semiconductor gets more complex and multi-layer, we should do multi-de-processing steps. If the failure has the oxide-material, we cannot know the cause of failure. Because the oxide can be removed by Hydrogen Fluoride (HF) chemical, which means the failure will be gone during de-processing step. We should use Focused Ion Beam (FIB) which can make a thin sample to exclude chemical step. High-resolution analytical tools such as Transmission Electron Microscopy (TEM) have become indispensable in PFA. We make a Dual-Axis TEM (DAT) method for PFA. We make a Plan-view TEM (PTEM) sample with FIB first, we can find an exact location of failure through the first step. And then, we make cross-sectional TEM (XTEM) sample with a site-specific target in PTEM sample. Below summarizes the four major steps and its precautions;
1. Making a Planar lamella by FIB
2. Observing a PTEM specimen with TEM
(Precaution : zone axis should be adjusted exactly)
3. Making a cross-section lamella by FIB
(Precaution : Protection layer should be deposited on both sides)
4. Observing a XTEM specimen with TEM
We propose DAT method to improve the problem of artifact in de-processing step. The TEM result with DAT method is shown in figure 4. We can know the exact location of failure with observing a PTEM sample. We can know the cause of failure with observing a XTEM sample. Moreover, we can analysis the chemical and physical information through DAT method. This method is very effective and has a high success rate in analysis.



[1] A.E.M. De Veirman, “3-Dimensional’ TEM silicon-device analysis by combining plan-view and FIB sample preparation”, Materials Science and Engineering: B, 102(1-3), pp. 63-69, 2003.

 [2] Jon C. Lee, David Su, J.H. Chuang, “A Novel Application of the FIB Lift-out Technique for 3-D TEM Analysis”, Microelectronics Reliability Asset, 41(9-11), pp. 1551-1556, 2001.