Secondary ion imaging microanalysis

Author(s):  
R. Levi-Setti ◽  
J. M. Chabala ◽  
C Girod-Hallegot ◽  
P. Hallegot ◽  
Y. L. Wang

The goals of high spatial resolution and high elemental sensitivity in the imaging microanalysis of biological tissues and materials have, to a large extent, been attained by using the method of secondary ion mass spectrometry (SIMS) following bombardment of a sample surface by a focused beam of heavy ions. The instrument that we will discuss and which has achieved these goals is a scanning ion microprobe originally developed in collaboration with Hughes Research Laboratories (UC-HRL SIM). It utilizes a 40-60 keV Ga+ probe, extracted from a point-like liquid metal ion source, that can be focused to a spot as small as 20 nm in diameter. During the past five years, much effort has been devoted to a reappraisal of well known SIMS methodologies in regard to their applicability to a range of lateral resolution (20-1000 nm) previously unexplored. Furthermore, of particular concern has been the identification of research areas whose demands could most profitably be matched by the performance of this new class of microprobes. The results of this effort are contained in over 21 topical publications and 14 review articles covering both instrumental aspects of our development and applications to a variety of interdisciplinary problems.

Author(s):  
R. Levi-Setti ◽  
J. M. Chabala ◽  
Y. L. Wang

We have shown the feasibility of 20 nm lateral resolution in both topographic and elemental imaging using probes of this size from a liquid metal ion source (LMIS) scanning ion microprobe (SIM). This performance, which approaches the intrinsic resolution limits of secondary ion mass spectrometry (SIMS), was attained by limiting the size of the beam defining aperture (5μm) to subtend a semiangle at the source of 0.16 mr. The ensuing probe current, in our chromatic-aberration limited optical system, was 1.6 pA with Ga+ or In+ sources. Although unique applications of such low current probes have been demonstrated,) the stringent alignment requirements which they imposed made their routine use impractical. For instance, the occasional tendency of the LMIS to shift its emission pattern caused severe misalignment problems.


1998 ◽  
Vol 4 (S2) ◽  
pp. 650-651 ◽  
Author(s):  
F. A. Stevie ◽  
S. W. Downey ◽  
S. Brown ◽  
T. Shofner ◽  
M. Decker ◽  
...  

The semiconductor industry demands elemental information from ever smaller regions. Two types of information in demand are two dimensional dopant profiles for the MOS transisitor and identification of particles as small as 30 nm diameter. The work of Levi-Setti and others resulted in liquid metal ion source (LMIS) instruments that provided secondary ion mass spectrometry (SIMS) images using Ga+ beams with 20 nm lateral resolution. It is now possible to purchase focused ion beam (FIB) systems with 5 nm beam capability and SIMS detection.The application of LMIS SIMS to meet semiconductor demands has been pursued in our laboratory with a FEI-800 FIB. SIMS imaging of semiconductor patterns after etch has shown the ability to identify boron and carbon contamination. Figure 1 shows boron in a comb structure after a BC13 etch. The boron can be shown to be removed by a cleaning step.


1994 ◽  
Vol 65 (7) ◽  
pp. 2276-2280 ◽  
Author(s):  
Kaoru Umemura ◽  
Hiroyasu Shichi ◽  
Setsuo Nomura

1993 ◽  
Vol 64 (5) ◽  
pp. 1146-1149 ◽  
Author(s):  
Hisayoshi Yurimoto ◽  
Yoshiharu Mori ◽  
Hironori Yamamoto

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
James A. Whitby ◽  
Fredrik Östlund ◽  
Peter Horvath ◽  
Mihai Gabureac ◽  
Jessica L. Riesterer ◽  
...  

We describe the design and performance of an orthogonal time-of-flight (TOF) secondary ion mass spectrometer that can be retrofitted to existing focused ion beam (FIB) instruments. In particular, a simple interface has been developed for FIB/SEM instruments from the manufacturer Tescan. Orthogonal extraction to the mass analyser obviates the need to pulse the primary ion beam and does not require the use of monoisotopic gallium to preserve mass resolution. The high-duty cycle and reasonable collection efficiency of the new instrument combined with the high spatial resolution of a gallium liquid metal ion source allow chemical observation of features smaller than 50 nm. We have also demonstrated the integration of a scanning probe microscope (SPM) operated as an atomic force microscope (AFM) within the FIB/SEM-SIMS chamber. This provides roughness information, and will also allow true three dimensional chemical images to be reconstructed from SIMS measurements.


Author(s):  
Bruno Schueler ◽  
Robert W. Odom

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides unique capabilities for elemental and molecular compositional analysis of a wide variety of surfaces. This relatively new technique is finding increasing applications in analyses concerned with determining the chemical composition of various polymer surfaces, identifying the composition of organic and inorganic residues on surfaces and the localization of molecular or structurally significant secondary ions signals from biological tissues. TOF-SIMS analyses are typically performed under low primary ion dose (static SIMS) conditions and hence the secondary ions formed often contain significant structural information.This paper will present an overview of current TOF-SIMS instrumentation with particular emphasis on the stigmatic imaging ion microscope developed in the authors’ laboratory. This discussion will be followed by a presentation of several useful applications of the technique for the characterization of polymer surfaces and biological tissues specimens. Particular attention in these applications will focus on how the analytical problem impacts the performance requirements of the mass spectrometer and vice-versa.


Author(s):  
Yanhua Huang ◽  
Lei Zhu ◽  
Kenny Ong ◽  
Hanwei Teo ◽  
Younan Hua

Abstract Contamination in the gate oxide layer is the most common effect which cause the gate oxide integrate (GOI) issue. Dynamic Secondary Ion Mass Spectrometry (SIMS) is a mature tool for GOI contamination analysis. During the sample preparation, all metal and IDL layers above poly should be removed because the presence of these layers added complexity for the subsequent SIMS analysis. The normal delayering process is simply carried out by soaking the sample in the HF solution. However, the poly surface is inevitably contaminated by surroundings even though it is already a practice to clean with DI rinse and tape. In this article, TOFSIMS with low energy sputter gun is used to clean the sample surface after the normal delayering process. The residue signals also can be monitored by TOF SIMS during sputtering to confirm the cross contamination is cleared. After that, a much lower background desirable by dynamic SIMS. Thus an accurate depth profile in gate oxide layer can be achieved without the interference from surface.


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