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1.
S. Tsukimoto K. Nitta T. Sakai M. Moriyama Masanori Murakami 《Journal of Electronic Materials》2004,33(5):460-466
In order to understand a mechanism of TiAl-based ohmic contact formation for p-type 4H-SiC, the electrical properties and
microstructures of Ti/Al and Ni/Ti/Al contacts, which provided the specific contact resistances of approximately 2×10−5 Ω-cm2 and 7×10−5 Ω-cm2 after annealing at 1000°C and 800°C, respectively, were investigated using x-ray diffraction (XRD) and high-resolution transmission
electron microscopy (HRTEM). Ternary Ti3SiC2 carbide layers were observed to grow on the SiC surfaces in both the Ti/Al and the Ni/Ti/Al contacts when the contacts yielded
low resistance. The Ti3SiC2 carbide layers with hexagonal structures had an epitaxial orientation relationship with the 4H-SiC substrates. The (0001)-oriented
terraces were observed periodically at the interfaces between the carbide layers and the SiC, and the terraces were atomically
flat. We believed the Ti3SiC2 carbide layers primarily reduced the high Schottky barrier height at the contact metal/p-SiC interface down to about 0.3
eV, and, thus, low contact resistances were obtained for p-type TiAl-based ohmic contacts. 相似文献
2.
The electrical behavior during annealing of copper films with a nominal concentration of 2 at.% boron has been investigated.
The evolution of the resistivity of the film was monitored using an in situ technique, in which the film was rampannealed
at constant ramp rates. At temperature of 150–200°C, the resistivity of the Cu(B) undergoes a first drop. This is followed
by one or two such drops in resistivity, so that after completion of a ramp-anneal from 50°C to 750°C, the room temperature
resistivity decreases from the initial value of 13 μΩ cm to 2.1 μΩcm, close to that of bulk copper. Isothermal annealing of
the film also leads to substantial decreases in resistivity, from 13 μΩcm to 3 μΩ cm after annealing at 350°C for 8 h and
to 2.5 μΩ cm at 400°C for 4 h. These results show that a dramatic reduction in resistivity of Cu(B) alloys takes place at
temperatures below 400°C, suggesting possible applications for silicon device interconnections. 相似文献
3.
The interaction between thin films of hydrogenated amorphous silicon and sputter-deposited chromium has been studied. Following
deposition of the chromium films at room temperature, the films were annealed over a range of times and temperatures below
350°C. It was found that an amorphous silicide was formed only a few nanometers thick with the square of thickness proportional
to the annealing time. The activation energy for the process was 0.55±0.05 eV. The formation process of the silicide was very
reproducible with the value of density derived from the thickness and Cr surface density being close to the value for crystalline
CrSi2 for all films formed at temperatures ≤300°C. The specific resistivity of the amorphous CrSi2 was ≈600 μΩ·cm and independent of annealing temperature. 相似文献
4.
Copper (titanium) [Cu(Ti)] films with low titanium (Ti) concentration were found to form thin Ti-rich barrier layers at the
film/substrate interfaces after annealing, which is referred to as self-formation of the barrier layers. This Cu(Ti) alloy
was one of the best candidates for interconnect materials used in next-generation ultra-large-scale integrated (ULSI) devices
that require both very thin barrier layers and low-resistance interconnects. In the present paper, in order to investigate
the influences of annealing ambient on resistivity and microstructure of the Cu alloys, the Cu(7.3at.%Ti) films were prepared
on the SiO2 substrates and annealed at 500°C in ultra-high vacuum (UHV) or argon (Ar) with a small amount of impurity oxygen. After annealing
the film at 500°C in UHV, the resistivity was not reduced below 16 μΩ-cm. Intermetallic compounds of Cu4Ti were observed to form in the films and believed to cause the high resistivity. However, after subsequently annealing in
Ar, these compounds were found to decompose to form surface TiO
x
and interfacial barrier layers, and the resistivity was reduced to 3.0 μΩ-cm. The present experiment suggested that oxygen
reactive to titanium during annealing played an important role for both self-formation of the interfacial barrier layers and
reduction of the interconnect resistivity. 相似文献
5.
R. Nipoti A. Nath S.B. Qadri Y-L. Tian C. Albonetti A. Carnera Mulpuri V. Rao 《Journal of Electronic Materials》2012,41(3):457-465
Semi-insulating 4H-SiC ⟨0001⟩ wafers have been phosphorus ion implanted at 500°C to obtain phosphorus box depth profiles with
dopant concentration from 5 × 1019 cm−3 to 8 × 1020 cm−3. These samples have been annealed by microwave and conventional inductively heated systems in the temperature range 1700°C
to 2050°C. Resistivity, Hall electron density, and Hall mobility of the phosphorus-implanted and annealed 4H-SiC layers have
been measured in the temperature range from room temperature to 450°C. The high-resolution x-ray diffraction and rocking curve
of both virgin and processed 4H-SiC samples have been analyzed to obtain the sample crystal quality up to about 3 μm depth from the wafer surface. For both increasing implanted phosphorus concentration and increasing post-implantation annealing
temperature the implanted material resistivity decreases to an asymptotic value of about 1.5 × 10−3 Ω cm. Increasing the implanted phosphorus concentration and post-implantation annealing temperature beyond 4 × 1020 cm−3 and 2000°C, respectively, does not bring any apparent benefit with respect to the minimum obtainable resistivity. Sheet resistance
and sheet electron density increase with increasing measurement temperature. Electron density saturates at 1.5 × 1020 cm−3 for implanted phosphorus plateau values ≥4 × 1020 cm−3, irrespective of the post-implantation annealing method. Implantation produces an increase of the lattice parameter in the
bulk 4H-SiC underneath the phosphorus-implanted layer. Microwave and conventional annealing produce a further increase of
the lattice parameter in such a depth region and an equivalent recovered lattice in the phosphorus-implanted layers. 相似文献
6.
We report the effect of steam oxidation at 875° C on the electrical resistivity, crystalline quality (measured by ion channeling),
and Al concentration (measured by secondary ion mass spectrometry) in 0.25 μm thick, Si-implanted and recrystallized, Si-on-sapphire
films. After a deep Si implantation (180 keV, 1.4×l015 Si/cm2) at room temperature, and solid-phase epitaxial regrowth from the non-amorphized, 0.03 μm thick surface region, the initially
undoped SOS films become doped p-type, and their resistivity decreases from (1−5)xl014 ficm to 0.5 Ωcm. The doping is due to electrically active Al, released from the A12O3 by the Si implantation, and present in the recrystallized films at a concentration of ≃2×l016 Al/cm3 . After a 75 min steam oxidation at 875 °C, which consumes 0.06 Μm of Si, the resistivity of the recrystallized films increases
to over 40 Ωcm, but the Al concentration is unchanged. The oxidation also uncovers higher quality material below the non-recrystallized
surface layer. A semi-quantitative model is proposed to explain the electrical data, based on the diffusion of oxygen from
the Si/SiO2 interface into the SOS film during oxidation, and the formation of Al-O-Si neutral complexes. Data on the stability of the
high-resistivity films against high-temperature annealing or re-amorphization and annealing is given. 相似文献
7.
Hwe Jae Lee Soon Jae Yu Hajime Asahi Shun-Ichi Gonda Young Hwan Kim Jin Koo Rhee S. J. Noh 《Journal of Electronic Materials》1998,27(7):829-832
Ohmic contacts with low resistance are fabricated on n-GaN films using Al/Ti bilayer metallization. GaN films used are 0.3
μm thick layers with carrier concentrations of 1 × 1019 cm−3 grown on the c-plane sapphire by ion-removed electron cyclotron resonance molecular beam epitaxy. The lowest value for the
specific contact resistivity (ρc) of 1.2×10−8 Ω·cm2 was obtained with furnace annealing at 500°C for 60 min. This result shows the effectiveness of high carrier concentration
GaN layers and the low temperature annealing for the realization of low resistance ohmic contacts. Sputtering Auger electron
spectroscopy analysis reveals that Al diffuses into Ti layer and comes into contact with the GaN surface. 相似文献
8.
Byung Lyul Park Dae-Hong Ko Young Sun Kim Jung Min Ha Young Wook Park Sang In Lee Hyeon-Deok Lee Myoung Bum Lee U. In Chung Young Bum Koh Moon Yong Lee 《Journal of Electronic Materials》1997,26(2):L1-L5
We have developed tungsten nitride (W-Nitride) films grown by plasma enhanced chemical vapor deposition (PECVD) for barrier
material applications in ultra large scale integration DRAM devices. As-deposited W-Nitride films show an amorphous structure,
which transforms into crystalline, β-W2N and α-W phases upon annealing at 800°C. The resistivity of the as-deposited films grown at the NH3/WF6 gas flow ratio of 1 is about 160 μω-cm, which decreases to 50 μω-cm after an rapid thermal annealing treatment at 800°C.
In the contact holes with the size of 0.35 μm and aspect ratio of 3.5, the bottom step coverage of the tungsten nitride films
is about 60%, which is about three times higher than that of collimated-TiN films. We obtained contact resistance and leakage
current with the tungsten nitride barrier layer comparable to those with conventional collimated TiN films. The contact resistance
and leakage current are stable upon thermal stressing at 450°C up to 48 h. 相似文献
9.
This study reports the good thermal stability of a sputtered Cu(MoN
x
) seed layer on a barrierless Si substrate. A Cu film with a small amount of MoN
x
was deposited by reactive co-sputtering of Cu and Mo in an Ar/N2 gas mixture. After annealing at 560°C for 1 h, no copper silicide formation was observed at the interface of Cu and Si. Leakage
current and resistivity evaluations reveal the good thermal reliability of Cu with a dilute amount of MoN
x
at temperatures up to 560°C, suggesting its potential application in advanced barrierless metallization. The thermal performance
of Cu(MoN
x
) as a seed layer was evaluated when pure Cu is deposited on top. X-ray diffraction, focused ion beam microscopy, and transmission
electron microscopy results confirm the presence of an ∼10-nm-thick reaction layer formed at the seed layer/Si interface after
annealing at 630°C for 1 h. Although the exact composition and structure of this reaction layer could not be unambiguously
identified due to trace amounts of Mo and N, this reaction layer protects Cu from a detrimental reaction with Si. The Cu(MoN
x
) seed layer is thus considered to act as a diffusion buffer with stability up to 630°C for the barrierless Si scheme. An
electrical resistivity of 2.5 μΩ cm was obtained for the Cu/Cu(MoN
x
) scheme after annealing at 630°C. 相似文献
10.
Pressure and pressureless electrical contacts were evaluated by measuring the contact electrical resistivity between copper
mating surfaces. Pressure electrical contacts with a contact resistivity of 2×10−5 Ω·cm2 have been attained using a carbon black paste of a thickness of less than 25 μm as the interface material. In contrast, a
pressureless contact with silver paint as the interface material exhibits a higher resistivity of 3×10−5 Ω·cm2 or above. A pressureless contact with colloidal graphite as the interface material exhibits the same high contact resistivity
(1×10−4 Ω·cm2) as a pressure contact without any interface material. On the other hand, pressureless contacts involving solder and silver
epoxy exhibit lower contact resistivity than carbon black pressure contacts. 相似文献
11.
In metallization, peeling and oxidation of tungsten silicide are the most serious problems of tungsten rich silicide. In this
study, multilayer-derived silicon rich tungsten silicide with the silicon film on the outermost surface is investigated to
avoid these problems. The dependence of sheet resistance on the annealing conditions is studied. X-ray diffraction results
indicate that silicide formation is nearly completed after 30 min annealing at 750° C. Microstructures of silicide and polycides
are investigated by electron microscopy. Silicide deposited on SiO2 has smaller grains that deposited on poly-Si. A resistivity of 60 μΩ-cm is obtained for multilayer-derived WSi2.3. 相似文献
12.
Masahiro Watanabe Shigeki Muratake Takashi Suemasu Hiromasa Fujimoto Shigenori Sakamori Masahiro Asada Shigehisa Arai 《Journal of Electronic Materials》1992,21(8):783-789
Epitaxial growth of a metal (CoSi2) /insulator (CaF2) nanometer-thick layered structure on Si(111) was demonstrated and the resistivity of CoSi2 epilayer in this structure was investigated. An epitaxial CoSi2 layer on CaF2 was obtained by the two-step growth technique,i.e. solid phase epitaxy with the epitaxial Si layer grown in the first step and Co deposited in the second step. This technique
was shown to be effective to avoid the Co agglomeration on CaF2 layer observed in the co-evaporation of Si and Co. An epitaxial CaF2 layer was formed on CoSi2/CaF2 at low substrate temperature (450°C) with partially ionized and accelerated CaF2 beam, to avoid Co agglomeration in the CoSi2/CaF2 underlayer as well. Obtained results showed a single-crystalline nature in reflection high-energy electron diffraction (RHEED)
and transmission electron microscopy (TEM) observations. The resistivity of a few nm-thick CoSi2 epilayers embedded by CaF2 has been investigated. We studied thickness and annealing temperature dependence of resistivity and showed that a minimum
resistivity of 30 μΩ cm was obtained in a 2 nm-thick CoSi2 sample annealed at 860°C. 相似文献
13.
N. Inoue A. Itoh T. Kimoto H. Matsunami T. Nakata M. Inoue 《Journal of Electronic Materials》1997,26(3):165-171
N+ implantation into p-type a-SiC (6H-SiC, 4H-SiC) epilayers at elevated temperatures was investigated and compared with implantation
at room temperature (RT). When the implant dose exceeded 4 × 1015 cm−2, a complete amorphous layer was formed in RT implantation and severe damage remained even after post implantation annealing
at 1500°C. By employing hot implantation at 500~800°C, the formation of a complete amorphous layer was suppressed and the
residual damage after annealing was significantly reduced. For implant doses higher than 1015 cm−2, the sheet resistance of implanted layers was much reduced by hot implantation. The lowest sheet resistance of 542Ω/ was
obtained by implantation at 500 ~ 800°C with a 4 × 1015 cm−2 dose. Characterization of n+-p junctions fabricated by N+ implantation into p-type epilayers was carried out in detail. The net doping concentration in the region close to the junction
showed a linearly graded profile. The forward current was clearly divided into two components of diffusion and recombination.
A high breakdown voltage of 615 ∼ 810V, that is almost an ideal value, was obtained, even if the implant dose exceeded 1015 cm−2. By employing hot implantation at 800°C, the reverse leakage current was significantly reduced. 相似文献
14.
The silicide reaction in co-deposited TiSix layers on single crystal and pre-amorphized Si has been studied in detail. Both the co-deposition ratio and the co-deposition
temperature were found to have a strong effect on the formation of the C54-TiSi2 phase in these films. An unusual dependence of the sheet resistance on the co-deposition ratio was observed for films deposited
at room temperature and those deposited at 400°C: the C54-TiSi2 phase forms more easily for layers deposited at 400°C in the co-deposition ranges x∼0 and x>1.5, while it forms more easily
for layers deposited at room temperature in the co-deposition ratio range of x∼0.2–1.5. These dependencies are explained by
the formation of crystalline silicide phase(s) with composition close to the co-deposition ratio. With a Si rich ratio, the
C49-TiSi2 phase forms at 400°C with very small grain size, which facilitates the C54-TiSi2 phase formation. The initial reaction of Ti-rich layer deposited at 400°C involves the formation of metal rich silicide,
which impedes the formation of the C54-TiSi2 phase. An ultra-thin MoSi2.0 layer (<0.5 nm) was found to promote the formation of the C54-TiSi2 phase in layers co-deposited at room temperature, but it showed little effect on layers co-deposited on pre-amorphized substrates
at elevated temperature. 相似文献
15.
Jong Kyu Kim Jung Ho Je Jae Won Lee Yong Jo Park Taeil Kim In-Ok Jung Byung-Teak Lee Jong-Lam Lee 《Journal of Electronic Materials》2001,30(2):L8-L12
Electrical properties of Ni/Au ohmic contacts on p-type GaN were interpreted with the change of microstructure observed under
transmission electron microscopy. The contact resistivity was decreased from 1.3×10−2 to 6.1×10−4 Ωcm2 after annealing at 600°C. The reduction is due to the dissolution of Ga atoms into Au−Ni solid solution formed during annealing,
via the generation of Ga vacancies. Thus, net concentration of holes increased below the contact, resulting in the reduction
of contact resistivity. At 800°C, N atoms decomposed; reacted with Ni, and forming cubic Ni4N. Consequently, N vacancies, acting as donors in GaN, were generated below the contact, leading to the increase of contact
resistivity to 3.8×10−2 Ωcm2. 相似文献
16.
Electrically nonconductive thermal pastes have been attained using carbon (carbon black or graphite) as the conductive component
and ceramic (fumed alumina or exfoliated clay) as the nonconductive component. For graphite particles (5 μm), both clay and alumina are effective in breaking up the electrical connectivity, resulting in pastes with electrical resistivity
up to 1013Ω·cm and thermal contact conductance (between copper surfaces of roughness 15 μm) up to 9 × 104 W/m2·°C. For carbon black (30 nm), clay is more effective than alumina, providing a paste with resistivity 1011 Ω·cm and thermal contact conductance 7 × 104 W/m2·°C. Carbon black increases the thermal stability, whereas either graphite or alumina decreases the thermal stability. The
antioxidation effect of carbon black is further increased by the presence of clay up to 1.5 vol.%. The addition of clay (up
to 0.6 vol.%) or alumina (up to 2.5 vol.%) to graphite paste enhances the thermal stability. 相似文献
17.
This investigation prepares a low-resistivity and self-passivated Cu(In) thin film. The dissociation behaviors of dilute Cu-alloy
thin films, containing 1.5–5at.%In, were prepared on glass substrates by a cosputter deposition, and were subsequently annealed
in the temperature range of 200–600 °C for 10–30 min. Thus, self-passivated Cu thin films in the form In2O3/Cu/SiO2 were obtained by annealing Cu(In) alloy films at an elevated temperature. Structural analysis indicated that only strong
copper diffraction peaks were detected from the as-deposited film, and an In2O3 phase was formed on the surface of the film by annealing the film at an elevated temperature under oxygen ambient. The formation
of In2O3/Cu/SiO2 improved the resistivity, adhesion to SiO2, and passivative capability of the studied film. A dramatic reduction in the resistivity of the film occurred at 500 °C,
and was considered to be associated with preferential indium segregation during annealing, yielding a low resistivity below
2.92 μΩcm. The results of this study can be potentially exploited in the application of thin-film transistor–liquid crystal display
gate electrodes and copper metallization in integrated circuits. 相似文献
18.
S.I. Maximenko J.A. FreitasJr. N.Y. Garces E.R. Glaser M.A. Fanton 《Journal of Electronic Materials》2009,38(4):551-556
The influence of postgrowth high-temperature anneals between 1400°C and 2400°C on the behavior of the D1 center in semi-insulating 4H-SiC was studied by photoluminescence. The optical signature of D1 was observed up to 2400°C with intensity maxima at 1700°C and 2200°C. It was also found that changes in the postannealing
cooling rate drastically influence the behavior of the D1 center and the concentrations of the VC, VSi, VC–VSi, and VC–CSi lattice defects observed from electron paramagnetic resonance experiments. The change in intensity of the D1 defect has some correlation with the intensity change of the VC–VSi pair defect at temperatures above 1900°C. In addition, infrared photoluminescence spectroscopy studies showed that changes
in the intensity of the D1 defect at 2100°C to 2400°C annealing temperatures and variable cool-down rates have close correlation with intensity changes
of the UD2 defect. 相似文献
19.
In this study we observed significantly improved properties, over a pure copper (Cu) film, for a copper-silver alloy film
made with a pure copper film co-sputtered with a minute amount of either Ag0.3N0.4 or Ag1.2N0.7 on a barrierless Si substrate. In either case, no noticeable interaction between the film␣and the Si substrate was found
after annealing at 600°C for 1 h. The Cu(Ag0.3,N0.4) film was thermally stable after annealing at 400°C for 240 h. The film’s resistivity was ∼2.2 μΩ cm after annealing at 600°C, while its leakage current was found to be lower than that of a pure Cu film by three orders
of magnitude. The adhesion of the Cu(Ag1.2,N0.7) film to the Si substrate was approximately seven times that of a pure Cu film to a silicon substrate. Hence, a Cu film doped
with Ag and N seems to be a better candidate for both barrierless metallization and the making of superior interconnects. 相似文献
20.
Eun-Ha Kim Dae-Hong Ko Siyoung Choi Bong-Young Yoo Hyeon-Deok Lee 《Journal of Electronic Materials》1999,28(10):L20-L23
We investigated the low temperature reactions between the Ti films created by the ionized sputtering process and the (001)
single crystal silicon wafers using high resolution transmission electron microscopy and x-ray diffractometry. We observed
that the amorphous Ti-Si intermixed layer is formed at the Ti-Si interface whose thickness increased with the thickness of
the deposited Ti films. The amorphous interlayer grew upon annealing treatments at the temperatures below 450°C. We also observed
that the crystallization of the amorphous interlayer occurred upon annealing at 500°C. The first formed phase is Ti5Si3 in contact with Ti films, which is epitaxial with Ti films. Upon further annealing at 500°C, the Ti5Si4 phase and C49 TiSi2 phase formed in the regions close to Ti films and Si substrates, respectively. 相似文献