Defect structure of silicon with an impurity of tungsten under the influence of external factors

 
DEFECT STRUCTURE OF SILICON WITH AN IMPURITY OF TUNGSTEN UNDER 
THE INFLUENCE OF EXTERNAL FACTORS 
 
Sh. Daliev, A. Paluanova, J. Ergashev, A. Rakhimov 
 
Institute of Semiconductor Physics and Microelectronics at the NUUz, 
Tashkent, Uzbekistan 
e-mail: [e-mail] 
Abstract. Tthe influence of external factors on the defective structure of silicon doped with 
tungsten has been studied using IR absorption and x-ray topography. A correlation was found 
between a decrease in the concentration of interstitial optically active oxygen and deep levels 
associated with tungsten atoms with a change in the size of large clusters of defective particles of 
various shapes in Si during annealing. 
Keywords: silicon, tungsten, oxygen, annealing, deep level, ionization energy, isothermal 
annealing 
 
Recently, refractory metals and their silicides began to be actively used in microelectronics, 
which is due to a number of their thermodynamic features, promising electrophysical properties, and 
stability at high temperatures [1-2]. It is known that the manufacturing process of semiconductor 
devices includes various heat treatment cycles. In addition, the process of operating semiconductor 
devices is often accompanied by their heating up to 100
0
C, and sometimes up to 400
0
C [3]. 
In this regard, it is of interest to study the influence of various external factors on the defect 
structure of Si with specially introduced impurities of refractory elements (RE). 
In work [4], we previously found that in the upper half of the band gap Si , 3 deep levels 
(DL) w
ith fixed ionization energies are formed: Е
с
-
0.22 eV, Е
с
-
0.30 eV and Е
с
-0.39 eV, and in the 
lower one - 2 DL 
with ionization energies Е
v
+ 0.31 eV and Е
v
+ 0.35 eV. It was also found that, upon 
isothermal annealing, the concentrations N
t
of the DLs E
c
-0.30 eV and Ec-0.39 eV change 
nonmonotonically with the annealing time: the concentrations of both DLs increase at short times, 
then the concentration of the E
c
-0.30 eV level sharply drops, and 0.39 eV is much slower. The change 
in the concentration E
c
-0.22 eV, which is also observed in the control samples (without W), is 
opposite to the change in the concentration of W levels in Si. 
In this work, we studied the effect of low-temperature annealing (LTA) on the state of the defect 
structure in Si doped with tungsten. Isothermal annealing was carried out in the temperature range 
150
–
400
0
C in air with subsequent cooling of the samples in water. 
Comparison of the kinetics of annealing of DL in Si  with a change in the content of the 
technological impurity (oxygen) in silicon after LTA shows that the initial increase in the 
concentration of DL occurs synchronously with an increase in the concentration of interstitial 
optically active oxygen (Fig. 1) during isothermal annealing for 10 min. (curve 3), upon further 
annealing for 30 minutes, the concentrations of DL and interstitial optically active oxygen decrease. 
The results obtained above confirm the assumption made in [4] about the role of oxygen atoms 
in the decomposition of the silicon-tungsten solid solution. Analysis of the DLTS and IR absorption 

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Semiconductor Physics 
and Microelectronics 
Volume 2, Issue 3 
2020 
Semiconductor
Materials Science 
41 
spectra shows that there is a good correlation between the behavior of the tungsten and oxygen levels 
upon annealing.