Identification and Characterization of Submicron Defects for Semiconductor Processing
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Identification and Characterization of Submicron Defects for Semiconductor Processing Wei Liu*, Aime Fausz+, John Svoboda+, Brian Butcher#, Rick Williams#, Steve Schauer* *Physical Analysis Laboratory of Advanced Products Research and Development Laboratory, +MOS12 Die Fab, #MRAM, Technology Solutions Organization, Freescale Semiconductor, Inc. Chandler, AZ85224, U.S.A ABSTRACT Auger Electron Spectroscopy (AES) is one of the few techniques that has surface sensitivity and small analysis volume to make it the ideal analytical technique for the compositional characterization of submicron defects. However, the integration of defect inspections at only a few processing steps during device fabrication results in the detection of many buried defects. In order to identify these defects, it is necessary to determine their composition. Combined with Focused Ion Beam (FIB) technique to expose the cross section of the buried defect, Auger analysis provides accurate identification of buried defects that are critical for quickly ramping to higher yields and recovering from yield excursions. This paper reports two examples of the use of AES combined with FIB to diagnose processing problems.
INTRODUCTION As the semiconductor industry strives to decrease device geometries and increase yield, the critical defect size becomes smaller and identification of defects becomes more challenging. Defect analysis is playing an increasing role in process development, process monitoring and yield enhancement. Auger Electron Spectroscopy (AES) is one of the few techniques that has nanometer surface sensitivity and sub-micron analysis volume to make it the ideal analytical technique for the compositional characterization of submicron defects [1, 2]. However, the integration of defect inspection at only a few processing steps during device fabrication results in the detection of many buried defects. In order to identify these defects, it is necessary to determine their composition. Combined with Focused Ion Beam (FIB) cross-sectioning, Auger analysis provides accurate identification of buried defects that are critical for quickly ramping to higher yields and recovering from yield excursions. In CMOS ICs, isolation must exist not only between two transistors within a given well or within the substrate region, but also between p- and n-channel devices to avoid any diffusions [3]. Therefore, the device functions such as leakage and yield directly depends on how well the isolation forms. The first example focuses on characterization and elimination of defects created within the isolation module beginning with the pad oxide growth, nitride deposition, trench etch, trench fill and trench CMP. Fig. 1 (a) shows the schematic of the isolation process to trench etch. Magnetoresistive random access memory (MRAM) is a high-speed low-voltage high-density, nonvolatile memory with unlimited read/write endurance [4]. MRAM is based on magnetic memory elements integrated with CMOS using copper interconnect technology. The copper interconnects are clad wit
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