Neutron Activation Analysis of Epitaxial Silicon

Abstract

A neutron activation analysis technique has been developed for the analysis of epitaxial silicon. The technique is described in detail along with a table of detection limits. Impurity and dopant concentrations have been profiled through epitaxial films on boron‐ and antimony‐doped substrates. These data along with experience in routine analyses show a factor of 10 to 40 higher impurity concentrations in the outer layer of silicon epitaxial films. Autoradiography combined with profiling has been shown to be a powerful tool for studying doping uniformity.

Impurity Profiling in Mixed Diffusion by Neutron Activation Analysis

“…Ductility is believed to be an important property which determines the reliability of electroless copper deposits on printed circuit boards manufactured by using the so-called additive processes (1,2). Factors which have been reported to influence the ductility include grain size (3,4), lattice strain (3), voids (5,6), and impurities (5)(6)(7)(8). A previous work using transmission electron microscopy (TEM) (5,6) shows that small voids are present both within grains and at grain boundaries, and that the deposit contains a significant amount of hydrogen.…”

“…Obtaining impurity and carrier profiles is of paramount importance to understanding device performance, therefore, many techniques have been developed to determine impurity/carrier profiles. According to the physical parameters measured, these techniques can be grouped into four categories, namely: (i) spreading resistance (1-3), four-point probe (4,5) measurement with layer stripping, (ii) capacitancevoltage measurement (6) using Schottky barrier or metaloxide-semiconductor structure, (iii) secondary ion mass spectroscopy (7) with ion sputtering, and (iv) radiotracer (8,9) or neutron activation analysis (NAA) (10)(11)(12) with layer stripping. Among these groups of techniques, the first two are electrical measurements and, hence, the profiles obtained are free carrier profiles, while the other two groups are impurity profiles.…”

Wafer and bulk high-purity silicon trace element analysis at the Texas A&M University Nuclear Science Center

“…This packing scheme results in a "wafer sandwich" physically isolated from contamination sources. Since no Si is removed from the water's surface during surface contamination analysis and not enough Si is removed during epitaxial layer analysis to use as an internal standard as in bulk Si analysis, a neutron fluence rate monitor must be included in the quartz dish for irradiation (3). When analyzing wafer pieces, unpolished Si wafers are used as fluence rate monitors.…”

Microdefect Elimination in Reduced Pressure Epitaxy on Silicon Wafer by Back Damage ‐ Si3 N 4 Film Technique

“…In general, a variety of defects such as stacking faults, slip dislocations (6,7), and microdefects correlated with impurities (8,9) is introduced in epilayer during epi-processing. The stacking fault density can be obtained less than ,~i0 cm -2 by gas etching prior to epitaxy and slip dislocations can be decreased to negligible extent by a radiant heating technique.…”