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1.
Gettering efficiencies for Cu and Ni as a function of size and density of oxygen precipitates in p/p- silicon epitaxial wafers 总被引:1,自引:0,他引:1
We have measured the gettering efficiencies for Cu and Ni in p/p-Si epitaxial wafers. The wafers were pretreated to obtain
oxygen precipitates of different sizes and densities in the bulk. Gettering tests started with a reproducible spin-on spiking
in the range of 1012 atoms/cm2, followed by thermal treatment to drive-in and redistribute the impurities in the wafer. Subsequently, the wafers were analyzed
by a novel stratigraphical layer-by-layer etching technique in combination with inductively coupled plasma mass spectrometry.
Gettering efficiencies for Ni did not depend on oxygen precipitate sizes and densities as long as ΔOi was larger than 0.2×1017 atoms/cm3 and the bulk micro defect densities were detectable by preferential etching (107 cm-3). In these cases, gettering efficiencies were 96–99% for Ni, while wafers not containing any measurable BMDs exhibited no
detectable gettering. Cu exhibited a more complex behavior because the total Cu contamination was found to be divided into
two species, one mobile and the other immobile species. A dependence on BMD size and BMD density of the Cu distributions in
the wafers was also detected. Gettering effects were increased with increasing BMD densities and sizes. For BMD densities
<109 cm-3, Cu was not efficiently gettered by oxygen precipitates. Even for BMD densities >1010 cm-3, gettering effects due to oxygen precipitates were one order of magnitude lower than in heavily boron-doped silicon.
Received: 19 January 2001 / Accepted: 31 January 2001 / Published online: 20 June 2001 相似文献
2.
We performed measurements of gettering efficiencies for Cu in silicon wafers with competing gettering sites. Epitaxial wafers
(p/p+) boron-doped with a polysilicon back side allowed us to compare p+ gettering with polysilicon gettering. We further
measured metal distributions in p+/p- epitaxial test wafers, with the p- substrate wafers pretreated for oxygen precipitation
to compare p+ gettering with oxygen precipitate gettering. Our test started with a reproducible spin-on contamination in the
1012 atoms/cm2 range, followed by thermal treatment in order to redistribute the metallic impurity. Wafers were then analyzed by a novel
wet chemical layer-by-layer etching technique in combination with inductively coupled plasma mass spectrometry. This led to
“stratigraphical” concentration profiles of the impurity, with typical detection limits of 5–10×1012 atoms/cm3. Twenty-five percent of the total Cu contamination in the p/p+/poly wafer was found in the p+ layer, whilst 75% was gettered
by the polysilicon. Obviously, polysilicon exhibits a stronger gettering than p+ silicon, but due to the large distance from
the front surface, polysilicon was less effective in reducing impurities from the front side of a wafer compared with p+ gettering.
An epitaxial layer p+ on top of p- substrates with oxygen precipitates gettered 50% of the total Cu; while the other 50% of
the Cu was measured in the p- substrate wafer with oxygen precipitates. Without oxygen precipitates, 100% of the spiked Cu
contamination was detected inside the p+ layer. Gettering by oxygen precipitates thus occurs in the same temperature range
as that where p+ silicon begins to getter Cu.
Received: 3 September 2001 / Accepted: 17 October 2001 / Published online: 27 March 2002 相似文献
3.
R. Hölzl L. Fabry K.-J. Range R. Pech 《Applied Physics A: Materials Science & Processing》2002,74(4):545-551
We have measured the gettering efficiencies for Cu and Ni of various silicon wafers, such as MeV-boron-implanted p- polished
wafers treated with two different implantation doses of 3×1013 atoms/cm2 B and 1×1015 atoms/cm2 B, respectively. A third kind of wafer was covered with a poly-silicon back side and thermally pretreated before the gettering
test to form oxygen precipitates in the bulk. The gettering test started with a reproducible spin-on spiking on the front
side of the wafers in the range around 1012 atoms/cm2, followed by a thermal treatment to redistribute the metallic impurities in the wafer. Then the gettering efficiencies were
measured by a novel wet chemical layer-by-layer etching technique in combination with inductively coupled plasma mass spectrometry.
This led to “stratigraphical concentration profiles” of the metallic impurities in the wafer with typical detection limits
of (5–10)×1012 atoms/cm3. The concentration profiles were compared with concentration profiles found after testing the gettering efficiency of p/p+
epitaxial wafers. Almost 100% of the total intentional Cu spiking was recovered in the boron buried layer for both implantation
doses. On the front surface and in the region between the front surface and the buried layer a Cu concentration ∼20 times
higher than on/in p/p+ epitaxial wafers/layers was measured for the implanted specimen. The lower implantation dose led to
higher Cu-concentration levels on the front surface compared to the higher implantation dose. The wafer containing a MeV-boron-implanted
layer as well as oxygen precipitates and a poly-silicon back side exhibited a Cu distribution of 30/∼0/70%, respectively.
Thus, the gettering by poly-silicon exceeded both the gettering effects by the buried layer and by the oxygen precipitates.
Ni gettering in MeV-boron-implanted wafers exhibited other characteristics. The gettering efficiency of the buried layer was
65%, while the remaining Ni contamination was equally distributed between the front-side region and the wafer back side. A
wafer containing a buried layer obtained by a 1×1015 atoms/cm3 B dose and oxygen precipitates exhibited 17% of the total Ni contamination in the boron layer, while ∼80% of the total Ni
contamination was gettered by oxygen precipitates. In the case of buried layer/oxygen precipitates/poly-silicon back side
the distribution was found to be 13/37/45%, thus exhibiting equal gettering strengths for oxygen precipitates and the poly-silicon
back side for Ni contamination. The results were discussed in terms of segregation and relaxation-induced gettering mechanisms
including different reaction rates.
Received: 30 May 2001 / Accepted: 16 June 2001 / Published online: 30 August 2001 相似文献
4.
R. Hoelzl K.-J. Range L. Fabry 《Applied Physics A: Materials Science & Processing》2002,75(4):525-534
Based on experimental findings we set up calculations of numerical modeling of gettering efficiencies for Cu in various silicon
wafers. Gettering efficiencies for Cu were measured by applying a reproducible spin-on contamination in the 1012 atoms/cm2 range, followed by a thermal treatment to redistribute the metallic impurity. Subsequently, the wafers were analyzed by a
novel wet chemical layer-by-layer etching technique in combination with inductively coupled plasma mass spectrometry. We investigated
p/p+ and n/n+ epitaxial wafers with different doping levels and different substrate-doping species. We have also investigated
gettering efficiencies of phosphorus-diffused p- and n-type wafers. Heavilyboron doped silicon exhibited a gettering efficiency
of ∼100%, while gettering by n+ silicon occurred for doping levels >3×1019 atoms/cm3 only. In another set of experiments we investigated the dependence of the gettering efficiency of p-type wafers with poly-silicon
back sides for different cooling rates and Cu spiking levels. A strong dependence on both parameters was found. Cu gettering
in p/p+ epitaxial wafers was modeled by calculating the increased solubility of Cu in p+ silicon compared to non-doped silicon
taking into account the Fermi-level effect, which stabilizes donors in p+ silicon, and the pairing reaction between Cu and
B. Calculated gettering efficiencies were in very good agreement with experimental results. Gettering in n+ silicon was similarly
modeled in terms of pairing reactions and the Fermi-level effect. But, for n-type silicon, many experimental uncertainties
existed; thus, we applied our expressions to solubility data of Hall and Racette to obtain the unknown parameters. The empirical
calculations were in good agreement even with results on n/n+ wafers. For phosphorus-diffused wafers we had to consider an
excess vacancy concentration of 1.2–5.5 times the equilibrium concentration to explain the experimental findings by the model.
Gettering by poly-silicon back sides was simulated by solving the time-dependent diffusion equation with boundary conditions
that take into account different surface reaction rates of silicon point defects. Using this advanced model, the experimentally
measured gettering efficiencies were reproduced within the uncertainty of the measurement.
Received: 3 September 2001 / Accepted: 4 September 2001 / Published online: 20 December 2001 相似文献
5.
We have measured the gettering efficiencies for Cr, Mn, Fe, Co, Ni and Cu in p/p+ epitaxial wafers. The gettering test started with a reproducible spin-on contamination on the front side of the wafers in
the 1012–1014 atoms/cm2 range, followed by thermal treatment to redistribute the metallic impurities in the wafer. The gettering efficiencies were
measured by a novel wet chemical stratigraphic etching technique in combination with inductively-coupled plasma mass spectrometry.
The residual bulk metal contamination was also measured by this method. This procedure led to global distributions of the
3d elements on the wafer’s front side, in the bulk of the wafer and on the wafer’s back side. Recovery rates were found to be
34%, 2.3%, 100%, 85%, 100% and 100% for Cr, Mn, Fe, Co, Ni and Cu, respectively. An impurity segregation effect in the wafer
bulk was measured for Cu (100%) and Cr (34%), while no detectable segregation-induced gettering mechanisms were detected for
the other elements in the applied concentration range. The segregation-induced gettering mechanisms were interpreted from
the electronic structure of the metallic impurities. For segregation gettering by increased solubility in p+ silicon, the metallic species must form donors. Only Cu+ (3d
10) and Cr+ (3d
5) can form singly positively charged species that exhibit a spherical electronic distribution. It is well known from spinell
structures that 3d
10 and, to a smaller extent 3d
5, are stable configurations in tetrahedral structures like the silicon lattice. Thus, we link the segregation-induced gettering
mechanism in p/p+ epitaxial wafer to the electronic configuration of the 3d elements.
Received: 19 January 2001 / Accepted: 31 January 2001 / Published online: 20 June 2001 相似文献
6.
C.-H. Chen U.M. Gösele T.Y. Tan 《Applied Physics A: Materials Science & Processing》1999,69(3):313-321
We have mentioned previously that in the third part of the present series of papers, a variety of n-doping associated phenomena
will be treated. Instead, we have decided that this paper, in which the subject treated is diffusion of Si into GaAs, shall
be the third paper of the series. This choice is arrived at because this subject is a most relevent heterostructure problem,
and also because of space and timing considerations. The main n-type dopant Si in GaAs is amphoteric which may be incorporated
as shallow donor species SiGa
+ and as shallow acceptor species SiAs
-. The solubility of SiAs
- is much lower than that of SiGa
+ except at very high Si concentration levels. Hence, a severe electrical self-compensation occurs at very high Si concentrations.
In this study we have modeled the Si distribution process in GaAs by assuming that the diffusing species is SiGa
+ which will convert into SiAs
- in accordance with their solubilities and that the point defect species governing the diffusion of SiGa
+ are triply-negatively-charged Ga vacancies VGa
3-. The outstanding features of the Si indiffusion profiles near the Si/GaAs interface have been quantitatively explained for
the first time. Deposited on the GaAs crystal surface, the Si source material is a polycrystalline Si layer which may be undoped
or n+-doped using As or P. Without the use of an As vapor phase in the ambient, the As- and P-doped source materials effectively
render the GaAs crystals into an As-rich composition, which leads to a much more efficient Si indiffusion process than for
the case of using undoped source materials which maintains the GaAs crystals in a relatively As-poor condition. The source
material and the GaAs crystal together form a heterostructure with its junction influencing the electron distribution in the
region, which, in turn, affects the Si indiffusion process prominently.
Received: 19 April 1999 / Accepted: 3 May 1999 / Published online: 4 August 1999 相似文献
7.
chemical effect on the neutral species; and (ii) a Fermi-level effect on the ionized species, because, in addition to the chemical effect, the solubility of the species also has a dependence
on the semiconductor Fermi-level position. For Zn and Be in GaAs and related compounds, their diffusion process is governed
by the doubly-positively-charged group III element self-interstitials (I2+
III), whose thermal equilibrium concentration, and hence also the diffusivity of Zn and Be, exhibit also a Fermi-level dependence,
i.e., in proportion to p2. A heterojunction consists of a space-charge region with an electric field, in which the hole concentration is different
from those in the bulk of either of the two layers forming the junction. This local hole concentration influences the local
concentrations of I2+
III and of Zn- or Be-, which in turn influence the distribution of these ionized acceptor atoms. The process involves diffusion and segregation
of holes, I2+
III, Zn-, or Be-, and an ionized interstitial acceptor species. The junction electric field also changes with time and position.
Received: 20 August 1998/Accepted: 23 September 1998 相似文献
8.
x Si1-x/Si heterostructures have been obtained. Here the chemical effects seem to be of less importance. The Fermi-level effect determines
the ionized boron solubilities in GexSi1-x and in Si, as well as the thermal equilibrium concentration of the singly-positively-charged crystal self-interstitials I+ which governs the boron diffusion process. The junction carrier concentration affects the concentration of I+ and solubility of B in the region and hence controls B diffusion across the heterojunction.
Received: 20 August 1998/Accepted: 23 September 1998 相似文献
9.
KrF excimer laser dry and steam cleaning of silicon surfaces with metallic particulate contaminants 总被引:3,自引:0,他引:3
P. Neves M. Arronte R. Vilar A.M. Botelho do Rego 《Applied Physics A: Materials Science & Processing》2002,74(2):191-199
KrF excimer laser-assisted dry and steam cleaning of single-crystal silicon wafers contaminated with three different types
of metallic particles was studied. The laser fluence used was 0.3 J/cm2. In the dry process, for samples cleaned with 100 laser pulses the cleaning efficiency was 91, 71 and 59% for Au, Cu and
W particles, respectively, whilst in steam cleaning the efficiency is about 100% after 5 laser pulses, independently of the
type of contaminant.
The effects of laser irradiation on the Si surface are investigated by scanning electron microscopy (SEM), X-ray photoelectron
spectroscopy (XPS) and atomic force microscopy (AFM). Laser processing at 0.3 J/cm2 does not deteriorate the Si-wafer surface, either in dry or steam cleaning. However, the measured XPS intensity coming from
the metallic component is greater on the cleaned surfaces than in the initial condition. Quantification of the XPS results,
assuming a stratified overlayer model for the detected species and accounting for the presence of the metallic particles on
the surface, showed that the obtained results can be explained by the formation of a fractional metallic monolayer on the
cleaned surfaces, due to partial vaporisation of small particles initially present on the sample surface. This contamination
of the substrate could be considered excessive for some applications and it shows that the process requires careful optimisation
for the required efficiency to be achieved without degradation of the substrate.
Received: 14 January 2001 / Accepted: 19 February 2001 / Published online: 20 June 2001 相似文献
10.
Kögler R. Eichhorn F. Kaschny J.R. Mücklich A. Reuther H. Skorupa W. Serre C. Perez-Rodriguez A. 《Applied Physics A: Materials Science & Processing》2003,76(5):827-835
Nanometer-sized SiC precipitates were synthesized in situ in Si by simultaneous implantation of two ion beams of C+ and Si+ ions. The results of simultaneous dual-beam implantation are compared with those of sequential dual-beam ion implantation
and of single-beam C+ ion implantation. Remarkable differences are observed regarding the content and the crystal quality of SiC precipitates as
well as the defect structure of the Si substrate. The SiC precipitation during dual-beam synthesis is found to depend on the
ion energy of the second beam and on the implantation mode, simultaneous or sequential. For suitable implantation conditions,
simultaneous dual-beam synthesis can improve the in situ SiC formation in comparison to the single-beam synthesis. A higher
density of SiC precipitates with better crystal quality was observed, whereas their size was not changed. The second ion beam
enables a shift in the dynamic equilibrium of constructive and destructive processes for SiC formation. A model is proposed
assuming that SiC precipitation preferentially proceeds in regions with vacancy defects. The implantation process itself creates
vacancy-dominated and also interstitial-dominated regions. The balance of the local point-defect composition is shifted under
the second ion beam. In this way, the conditions for SiC precipitation can be modified.
Received: 18 February 2002 / Accepted: 17 May 2002 / Published online: 17 December 2002
RID="*"
ID="*"Corresponding author. Fax: +49-351/260-3411, E-mail: koegler@fz-rossendorf.de 相似文献
11.
A theory of defect-strain instability with formation of periodic surface relief in semiconductors irradiated by ultra-short
(τp=10-13 s) powerful laser pulses is developed. The period and time of formation of surface relief are calculated. Regimes of multi-pulse
laser ablation leading to formation of either a smooth surface or arrays of surface-relief spikes are pointed out and corresponding
experimental results are interpreted from the viewpoint of the developed theory.
Received: 4 December 2000 / Accepted: 23 July 2001 / Published online: 11 February 2002 相似文献
12.
Oxidation-induced stoichiometric and morphological change of oxide films on stainless-steel surfaces
The oxidation-induced stoichiometric and morphological changes of the oxide film on a stainless-steel surface are observed
by X-ray photoelectron spectroscopy and atomic force microscopy for annealing temperatures in the range 400–500 °C in oxygen
partial pressures of 10-9 to 10-4 Torr With increasing the temperature, a significant shift occurs in the Cr 2p3/2 binding energy towards higher energies, indicating a change in the oxidation state of chromium. It is found that at 450 °C
lower oxygen partial pressures favor the formation of a smooth, pure chromium oxide. At a low oxygen pressure the oxide formed
mainly consists of chromium oxide that shows a markedly smooth surface with no distinct grains, whereas at a high pressure
the oxide formed mainly consists of iron oxide with distinct grains.
Received: 27 January 1999 / Accepted: 18 March 1999 / Published online: 16 September 1999 相似文献
13.
14.
A. Gross 《Applied Physics A: Materials Science & Processing》1998,67(6):627-635
Received: 23 March 1998/Accepted: 21 August 1998 相似文献
15.
S.M. Huang M.H. Hong B. Lukiyanchuk T.C. Chong 《Applied Physics A: Materials Science & Processing》2003,77(2):293-296
Nanostructures on metal film surfaces have been written directly using a pulsed ultraviolet laser. The optical near-field
effects of the laser were investigated. Spherical silica particles (500–1000 nm in diameter) were placed on metal films. After
laser illumination with a single laser shot, nanoholes were obtained at the original position of the particles. The mechanism
for the formation of the nanostructure patterns was investigated and found to be the near-field optical resonance effect induced
by the particles on the surface. The size of the nanohole was studied as a function of laser fluence and silica particle size.
The experimental results show a good agreement with those of the relevant theoretical calculations of the near-field light
intensity distribution. The method of particle-enhanced laser irradiation allows the study of field enhancement effects as
well as its potentialapplications for nanolithography.
Received: 10 December 2002 / Accepted: 20 January 2003 / Published online: 28 May 2003
RID="*"
ID="*"Corresponding author. Fax: +65-777/1349, E-mail: HUANG_Sumei@dsi.a-star.edu.sg 相似文献
16.
E.K. Wheeler P.K. Whitman T.A. Land J. De Yoreo C.B. Thorsness J.H. McWhirter M.L. Hanna E.L. Miller 《Applied Physics A: Materials Science & Processing》2002,74(6):813-823
We have investigated etch-pit formation on potassium dihydrogen phosphate (KDP) crystals with porous anti-reflective coatings.
Etch pits develop beneath the sol–gel coatings after exposure to ambient humidity. The etch pits are homogeneously distributed
with a density and an average size governed by the relative humidity and the coating thickness. Furthermore, the etch pits
are self-similar in shape and possess facets corresponding to low-energy planes of KDP. Results from optical microscopy, light
scattering, and atomic force microscopy support the following model for etch-pit formation in this system. Water adsorbed
from the environment into the porous sol–gel coating contacts the crystal surface, causing etch-pit nucleation at high undersaturation.
The plume of KDP rising from an etch pit slowly diffuses laterally, reducing the undersaturation and shutting off nucleation
in the surrounding area. Because surface kinetics are rapid compared to mass transport through the sol–gel, etch pits continually
undergo equilibration to maintain a low-energy geometry and generate an average spacing. Growth continues until the reservoir
of water in the sol–gel is saturated with KDP. Coarsening is only observed in high relative humidity environments.
Received: 13 Juni 2001 / Accepted: 30 July 2001 / Published online: 30 October 2001 相似文献
17.
Y. Isshiki J. Shi H. Nakai M. Hashimoto 《Applied Physics A: Materials Science & Processing》2000,70(4):395-402
Laser surface alloying (LSA) with silicon was conducted on austenitic stainless steel 304. Silicon slurry composed of silicon
particle of 5 μm in average diameter was made and a uniform layer was supplied on the substrate stainless steel. The surface
was melted with beam-oscillated carbon dioxide laser and then LSA layers of 0.4–1.2 mm in thickness were obtained. When an
impinged energy density was adjusted to be equal to or lower than 100 W mm−2, LSA layers retained rapidly solidified microstructure with dispersed cracks. In these samples, Fe3Si was detected and the concentration of Si in LSA layer was estimated to be 10.5 wt.% maximum. When the energy density was
equal to or greater than 147 W mm−2, cellular grained structure with no crack was formed. No iron silicate was observed and alpha iron content in LSA layers
increased. Si concentration within LSA layers was estimated to be 5 to 9 wt.% on average. Crack-free as-deposited samples
exhibited no distinct corrosion resistance. The segregation of Si was confirmed along the grain boundaries and inside the
grains. The microstructure of these samples changed with solution-annealing and the corrosion resistance was fairly improved
with the time period of solution-annealing.
Received: 2 September 1999 / Accepted: 6 September 1999 / Published online: 1 March 2000 相似文献
18.
The azimuthal angle dependence and the temperature dependence of terahertz (THz) radiation generated from n-type (111) InSb and n-type (111) InAs surfaces irradiated with ∼80 fs near-infrared laser pulses are investigated. The azimuthal angle dependence
shows that the contribution of the difference-frequency mixing (DFM) is not dominant for both materials at the excitation
density of ∼1 GW/cm2. At an appropriate azimuthal angle, the radiation due to DFM is excluded from the total THz radiation and the temperature
dependence of THz radiation due to the surge current is observed. The increase of THz radiation with decrease of the temperature
is found to be much more pronounced for InSb than for InAs. The different temperature dependence can be attributed to the
different radiation mechanisms dominant for both materials. Especially, the temperature dependence of the THz radiation from
InSb is well explained by the photo-Dember effect.
Received: 9 May 2000 / Revised version: 17 August 2000 / Published online: 5 October 2000 相似文献
19.
20.
M. Feuerhake J.-H. Klein-Wiele G. Marowsky P. Simon 《Applied Physics A: Materials Science & Processing》1998,67(5):603-606
Received: 27 July 1998/Accepted: 28 July 1998 相似文献