Complex destruction of near-surface silicon layers of Si-SiO₂ structure
The structure of near-surface silicon layers of Si-SiO₂ has been investigated. It was observed the complex destruction of these layers caused by relaxation of mechanical stresses. The magnitude of mechanical stresses depends not only on parameters of silicon dioxide and silicon but on presence of...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2010
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irk-123456789-1185782017-05-31T03:07:43Z Complex destruction of near-surface silicon layers of Si-SiO₂ structure Yatsunskiy, I.R. Kulinich, O.A. The structure of near-surface silicon layers of Si-SiO₂ has been investigated. It was observed the complex destruction of these layers caused by relaxation of mechanical stresses. The magnitude of mechanical stresses depends not only on parameters of silicon dioxide and silicon but on presence of initial defects in silicon. We have proposed the defect formation mechanism of near-surface layers in Si-SiO₂ structure, and it has been revealed the influence of impurities on this process. 2010 Article Complex destruction of near-surface silicon layers of Si-SiO₂ structure / I.R. Yatsunskiy, O.A. Kulinich // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2010. — Т. 13, № 4. — С. 418-421. — Бібліогр.: 8 назв. — англ. 1560-8034 PACS 61.05.cm, 61.72.Cc, 68.35.bg http://dspace.nbuv.gov.ua/handle/123456789/118578 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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The structure of near-surface silicon layers of Si-SiO₂ has been investigated. It
was observed the complex destruction of these layers caused by relaxation of mechanical
stresses. The magnitude of mechanical stresses depends not only on parameters of silicon
dioxide and silicon but on presence of initial defects in silicon. We have proposed the
defect formation mechanism of near-surface layers in Si-SiO₂ structure, and it has been
revealed the influence of impurities on this process. |
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Article |
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Yatsunskiy, I.R. Kulinich, O.A. |
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Yatsunskiy, I.R. Kulinich, O.A. Complex destruction of near-surface silicon layers of Si-SiO₂ structure Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Yatsunskiy, I.R. Kulinich, O.A. |
| author_sort |
Yatsunskiy, I.R. |
| title |
Complex destruction of near-surface silicon layers of Si-SiO₂ structure |
| title_short |
Complex destruction of near-surface silicon layers of Si-SiO₂ structure |
| title_full |
Complex destruction of near-surface silicon layers of Si-SiO₂ structure |
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Complex destruction of near-surface silicon layers of Si-SiO₂ structure |
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Complex destruction of near-surface silicon layers of Si-SiO₂ structure |
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complex destruction of near-surface silicon layers of si-sio₂ structure |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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2010 |
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http://dspace.nbuv.gov.ua/handle/123456789/118578 |
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Complex destruction of near-surface silicon layers of Si-SiO₂ structure / I.R. Yatsunskiy, O.A. Kulinich // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2010. — Т. 13, № 4. — С. 418-421. — Бібліогр.: 8 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
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AT yatsunskiyir complexdestructionofnearsurfacesiliconlayersofsisio2structure AT kulinichoa complexdestructionofnearsurfacesiliconlayersofsisio2structure |
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2025-07-08T14:16:05Z |
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2025-07-08T14:16:05Z |
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1837088550766510080 |
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Semiconductor Physics, Quantum Electronics & Optoelectronics, 2010. V. 13, N 4. P. 418-421.
PACS 61.05.cm, 61.72.Cc, 68.35.bg
Complex destruction of near-surface silicon layers
of Si-SiO2 structure
I.R. Yatsunskiy, O.A. Kulinich
I.I. Mechnikov Odessa National University,
2, Dvorianskaya str., 65026 Odessa, Ukraine
E-mail: yatsunskiy@gmail.com
Abstract. The structure of near-surface silicon layers of Si-SiO2 has been investigated. It
was observed the complex destruction of these layers caused by relaxation of mechanical
stresses. The magnitude of mechanical stresses depends not only on parameters of silicon
dioxide and silicon but on presence of initial defects in silicon. We have proposed the
defect formation mechanism of near-surface layers in Si-SiO2 structure, and it has been
revealed the influence of impurities on this process.
Keywords: Si-SiO2 structure, dislocation, defect, mechanical stresses.
Manuscript received 01.09.09; revised manuscript received 17.03.10; accepted for
publication 02.12.10; published online 30.12.10.
1. Introduction
Silicon has long been synonymous with semiconductor
technology. This unique role is largely related to
remarkable properties of the Si-SiO2 interface. Si-SiO2
systems currently are important and still in the lead
position for sub-micrometer electronic devices. That is
why there exist a lot of works dealing with investigation
of this structure.
The main part of electronic processes in Si-SiO2
structure happens in near-surface layers, and it requires
the detailed structural and impurity investigation of these
layers. Understanding the structure of near-surface
layers of silicon in Si-SiO2 systems is serious problem of
great importance for microelectronic applications. The
up-to-date concept represents interface Si-SiO2
originating in the course of thermal oxidation as some
transition layer with a variable chemical and structural
composition. It is supposed that at the boundary surface
of monocrystalline silicon there is a monoatomic layer of
non-stoichiometrical SiOx (1<x<2). Then the
intermediate layer of SiO2 follows with major internal
mechanical stresses that are transfered into amorphous
SiO2 [1, 2]. Also, there is a known model representing
the interface Si-SiO2 in the form of three-layered
structure: silicon dioxide, transition layer of non-
stoichiometrical SiOx with the thickness of 1 to 3 nm and
hard destructed layer of silicon with a thickness close to
few micrometers [3, 4]. However, in some cases the
destruction of near-surface silicon layers and generation
of dislocation structures happen in the form of
dislocation networks [5]. These silicon layers are
expanded from the interface to abnormally long
distances up to 10-30 μm. The real structure and depth of
these layers have not been ascertained yet. It is still not
revealed the correlation between the difference in
parameters of these layers that appear after oxidation
process and characteristics of initial silicon. Therefore,
the aim of this work was to investigate the silicon near-
surface layers in Si-SiO2 structure and to determine the
parameters that influence on generation of complex
defect structure during high-temperature oxidation.
2. Samples and experimental technique
Silicon wafers of n- and p-types with different
orientation and dioxide thickness (range 0.1 – 1.5 μm)
grown in dry oxygen atmosphere at the temperature
1150 °C were researched (oxygen consumption was
about 10 liters per minute). Investigation of silicon
surface after removal of dioxide was carried out by
scanning electronic microscopy (electronic scanning
microscope “Cam-Scan” with “Link-860” X-ray
microanalysis, by using the ZAF program for
calculation), by optical methods (metallographic
microscope MMR-2R), by Auger spectrometer LAS-
3000 (beam diameter – 5 μm), by X-ray technique based
on DRON-2 with silicon grating monochromator
(voltage 16 kV, current 2 mA).
SiO2 was etched off in hydrofluoric acid followed
by washing in deionized water. To detect structural
defects, the silicon surface layer-by-layer etching away
© 2010, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
418
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2010. V. 13, N 4. P. 418-421.
with selective Sacco (for surface 100) and Sirtl (for 111)
etchants with preliminary treatment in Karo intermixture
and peroxide-ammonia solution was performed. This
preliminary procedure improves developing properties
of selective enchants [3].
3. Results and discussion
Fig. 1 shows the typical silicon surface received after
removal of dioxide in HF and 5 min etching of silicon
(the thickness of dioxide was 1 μm) in selective Sirtl
etchant. It is well seen that etch pits typical for
dislocations and stacking faults are absent. The presence
of such pits on silicon surface is usually related with
etched dioxide that appeared at the accelerated
thermodiffusion of oxygen atoms along initial structural
defects of silicon (Fig. 2). The attempt to have an
electron image of the silicon surface was impossible by
reason of charging as a result of dielectric properties of
this one. Therefore, we conclude that these layers consist
of polysilicon, block boundaries of which contain
unsaturated bonds with a small fill factor for charge
carriers. The thickness of this layer depends on the
dioxide thickness and quality of silicon. As shown using
the Auger-analysis, the certain property of these layers is
high amount of dissolved oxygen, and the oxygen
concentration increases with growth of the dioxide
thickness.
Fig. 1. The optical image of silicon surface (magnification is
1000-fold).
Fig. 2. The SEMS image of initial structural defects
(dislocations) in Si.
After etching the silicon surface (up to 5 min),
dislocation networks were revealed (Fig. 3) (with the
dislocation density up to ), which have included
60° as well as partial dislocations and was decorated by
oxygen (Fig. 4). Appearance of typical structural defects
testifies to occurrence of a normal crystalline structure.
After 5 min etching, separate dislocations and glide lines
appear instead of dislocation networks (Fig. 5). This
complex structure of disordered silicon is generated as a
result of non-stoichiometrical SiO
210 m10 −
x origination during
enhanced diffusion of oxygen along initial dislocations.
Non-stoichiometrical SiOx causes an additional strain
and additional glide polygonization of silicon. As a
result, the destructed silicon layer is separated into layers
consisting of disordered silicon and the layer containing
dislocation networks. These layers contain different
energy-level density, capable to capture electrons, i.e.,
between these layers there is a magnitude jump of the
electron trapping level density. This effect is cleared up
in electron microscope investigations of near-surface
silicon layers. Therefore, the near-surface silicon layers
of Si-SiO2 structure could be represented in the
following manner (Fig. 6).
Fig. 3. Image of the dislocation network in p-Si obtained after
selective chemical etching with Sirtle (depth of analysis
L = 15 μm).
Fig. 4. X-ray analysis of the dislocation network (concentration
of oxygen atoms is 6.6%).
© 2010, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
419
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2010. V. 13, N 4. P. 418-421.
Fig. 5. The electron image of separate dislocations
(magnification is 2300-fold).
Fig. 6. The near-surface silicon model of Si-SiO2. 1 – SiO2
layer, 2 – disordered silicon layer, 2′ – internal SiO2 generated
due to accelerated thermodiffusion of oxygen, 3 – dislocation
networks, 4 – silicon.
To confirm this complex structure of silicon near-
surface region, X-ray diffraction method was used.
Rocking curves are presented in Figs 7a and 7b. The
slope of a curve is explained by presence of the second
reflective layer. It can be noted the overlay of “little”
rocking curve in Fig. 7b. By means of Gaussian function
approximation the maximum and the half-width of
“little” curve were determined, which enabled to
calculate other parameters of silicon. The shift of the
maximum and curve broadening as compared to the
ideal standard specimen are determined by some
physical reasons such as macrostress and microstress.
Macrostresses are caused by the interface stress, and
microstresses are caused by the polycrystalline structure.
If we know the curve broadening β1 and β2 of 2 orders in
reflection for the same reflection plane, we can make
qualitative evaluation and determine what parameters
influence on curve broadening [4]. Using the following
expression
1
2
1
2
2
1
ѓЖtg
ѓЖtg
cos
cos
<<
β
β
θ
θ
, (1)
where θ are the angles of reflection, β – half-width of the
rocking curve. We obtained the inequalities
1<1.11<3.35. Therefore, the dispersion in layer
structures has main influence on curve broadening.
a
b
Fig. 7. The rocking curves for oxide thicknesses 0.15 μm (a) and
1.5 μm (b).
According to the expression [4]
θβ
λ
cos
=D , (2)
where λ is the wavelength, we calculated D – the
crystallite size. It was close to 0.5-0.8 μm and
proportional to the oxide thickness. The grain-boundary
angle was in the range 0.005° to 0.008°.
Formation of the given complex defect structure is
possible, if magnitudes of mechanical stresses are higher
than the yield stress for silicon. Calculation shows that it
is observed only at the silicon dioxide – silicon interface
[5]. The abnormally deep mechanical stresses can be
explained by accelerated thermodiffusion of oxygen
atoms along initial structural defects. In this case, the
oxygen diffusivity along structural defects is higher by 3
to 4 orders than that for bulk.
4. Conclusions
Thus, as shown by experimental investigations, the near-
surface layers of silicon at the silicon – dioxide interface
has a complex structure and consist of polycrystalline
© 2010, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
420
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2010. V. 13, N 4. P. 418-421.
silicon region and dislocation network region. The
thickness of layers and the size of crystallites in
disordered layer depend on mechanical stress, which is
related with electrophysical parameters of silicon, the
oxide thickness and presence of initial defects in crystal.
The abnormally high values of stresses passing round
deep into silicon from the interface can be explained by
accelerated thermodiffusion of oxygen atoms along
initial structural defects that are present in silicon before
high-temperature oxidation.
References
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© 2010, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
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