Phase Transformation of Co Silicidation in the Co/Ti- and Ti/Co-Si(100) Systems

1993 ◽  
Vol 311 ◽  
Author(s):  
Feng Hong ◽  
Bijoy K. Patnaik ◽  
Bingzong Li ◽  
Ping Liu ◽  
Zen Sun ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Transformation Temperature ◽  
Interfacial Layer ◽  
Vacuum Furnace ◽  
Phase Identification ◽  
Formation Temperature ◽  
Silicide Formation ◽  
Si Substrate ◽  
Si Substrates ◽  
Selective Diffusion

ABSTRACTCo silicide formed via selective diffusion of Co through a Ti interfacial layer has been reported by several groups. In this report, phase identification of the silicide has been further studied for both Co/Ti and Ti/Co multi- and bilayers deposited on p(100)-Si substrates. The samples were either vacuum furnace or RTA annealed from 550°C to 900°C. The Co silicide formation sequence in the Co/Ti-Si systems follows CoSi2→Co2Si→CoSi→CoSi2 with the formation temperature increasing for each phase. The Co/Ti bilayer CoSi to CoSi2 transformation temperature was lower than that for the six layer Co/Ti system. For the multilayer sample with Co as the first layer in contact with the Si substrate, CoSi2 formed at 550°C and then CoSi was observed at higher temperatures due to the effect of Co supply on disilicide phase instability. Epitaxial CoSi2 growth occured at higher temperatures after the removal of the unreacted upper layers. A 15 μΩ-cm film resistivity was obtained from 50 nm epitaxial CoSi2.

Arsenic Diffusion and Segregation Behavior at the Interface of Epitaxial CoSi2 Film and Si Substrate

1993 ◽  
Vol 320 ◽  
Author(s):  
S. L. Hsia ◽  
T. Y. Tan ◽  
P. L. Smith ◽  
G. E. Mcguire
Keyword(s):  
Qualitative Agreement ◽  
Film Formation ◽  
Formation Temperature ◽  
Si Substrate ◽  
Free Surfaces ◽  
Si Substrates ◽  
Segregation Behavior ◽  
P Type ◽  
Physical Reasons ◽  
Source Materials

ABSTRACTArsenic diffusion and segregation properties at the interface of the epitaxial CoSi2 and Si substrate have been studied. Samples have been prepared using Co-Ti bimetallic source materials and two types of (001) Si substrates: n+ (doped by As to ∼2}1019 cm−3) and p. For the n+ Si cases, the lower limit of the CoSi2 film formation temperature is increased by ∼200°C to ∼700°C. SIMS results showed As segregation into Si. For epitaxial CoSi2 film formation at 900°C, the As concentration has increased by a factor of ∼2 within a distance of ∼30nm from the interface, while the incorporated As in the film is ∼30-50 times less than that in Si. For p-type Si substrate cases, the epitaxial CoSi2 film was first grown and followed by As+ implantation (into the film) and drive-in processes. It is observed that As was segregated to the CoSi2-Si interface and diffused into Si. This is in qualitative agreement with our results obtained from the n+ substrate experiments and the results of other authors involving the use of polycrystalline CoSi2 films. In the present cases, all implanted As were conserved at a drive in-temperature of 1000°C for up to 100 s. This is in contrast to the polycrystalline CoSi2 film results which involve a substantial As loss to the film free surfaces. The physical reasons of this difference have been discussed.

Lowering the formation temperature of the C54-TiSi2 phase using a metallic interfacial layer

1997 ◽  
Vol 12 (2) ◽  
pp. 304-307 ◽  
Author(s):  
C. Cabral ◽  
L. A. Clevenger ◽  
J. M. E. Harper ◽  
F. M. d'Heurle ◽  
R. A. Roy ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Interfacial Layer ◽  
Formation Temperature ◽  
Temperature Range ◽  
Nucleation Sites ◽  
Lower Resistivity

We demonstrate that the formation temperature of the C54 TiSi2 phase from the bilayer reaction of Ti on Si is lowered by approximately 100 °C by placing an interfacial layer of Mo or W between Ti and Si. Upon annealing above 500 °C, the C49 TiSi2 phase forms first, as in the reaction of Ti directly on Si. However, the temperature range over which the C49 phase is stable is decreased by approximately 100 °C, allowing C54 TiSi2 formation below 700 °C. Patterned submicron lines (0.25−1.0 μm wide) fabricated without the Mo layer contain only the C49 TiSi2 phase after annealing to 700 °C for 30 s. With a Mo layer less than 3 nm thick between Ti and Si, however, a mixture of C49 and C54 TiSi2 was formed, resulting in a lower resistivity. The enhanced formation of the C54 TiSi2 is attributed to an increased density of nucleation sites for the C49-C54 phase transformation, arising from a finer grained precursor C49 phase.

In-Situ Studies of Silicide Formation in Ti-Ta Bilayer Thin Films on Poly-Si

2002 ◽  
Vol 721 ◽  
Author(s):  
A. S. Özcan ◽  
K. F. Ludwig ◽  
C. Lavoie ◽  
C. Cabral ◽  
J. M. E. Harper
Keyword(s):  
Volume Fraction ◽  
Formation Temperature ◽  
Silicide Formation ◽  
X Ray Diffraction ◽  
Template Effect ◽  
Elastic Light Scattering ◽  
Time Resolved ◽  
X Ray ◽  
Si Substrates

AbstractWe have studied the formation of titanium silicides in the presence of an ultra-thin layer of Ta, interposed between Ti and Si. In-situ x-ray diffraction (XRD), resistance measurements and elastic light scattering were used to study the thin film reactions in real time during ramp anneals to 1000°C. On poly-Si substrates the Ta thickness was varied from 0 to 1.5 nm while the Ti thickness was held constant at ∼27 nm. The time-resolved XRD shows that the volume fraction of C40 and metal-rich silicide phases grows with increasing Ta layer thickness. Increased Ta layer thicknesses also delay the growth of the C49 disilicide phase to higher temperatures. Among the Ta thicknesses we examined, 0.3 nm is the most effective in lowering the C49-C54 transformation temperature. Films with Ta layers thicker than 0.5 nm do not completely transform into the C54 phase. The texture of the C54 phase is also sensitive to the Ta thickness. The C54 disilicide film is predominantly (010) textured for the Ti / 0.3 nm Ta sample. The final C54 texture is significantly different for Ta layers thinner or thicker than the optimal 0.3 nm. This suggests that the most effective thickness for lowering the C54 formation temperature is related to the development of a strong (010) texture. The possibility of a template effect by the C40 or metal-rich Ti5Si3 phases is also discussed on the basis of texture considerations.

Phase Transformation of Titanium Disilicide Induced by High-Temperature Sputtering

1995 ◽  
Vol 402 ◽  
Author(s):  
K. Fujii ◽  
R. T. Tung ◽  
D. J. Eaglesham ◽  
K. Kikuta ◽  
T. Kikkawa
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Phase Transformation ◽  
Interfacial Layer ◽  
Nucleation Density ◽  
Si Substrate ◽  
Titanium Disilicide ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Apparent Reduction

AbstractThe reaction between sputtered Ti thin films and heavily arsenic doped Si(100) is studied. The use of an arsenic implantation to pre-amorphize the Si substrate and the choice of the substrate temperature during Ti sputtering are both found to have a significant effect on subsequent TiSi2 reactions. Cross-sectional transmission electron microscopy reveals that an amorphous TiSix layer is formed at the interface between Si and as-sputtered Ti. The thickness of this interfacial layer increases with the sputtering temperature. After rapid thermal anneals in nitrogen, the sheet resistances of TiSi2 thin films grown with the pre-amorphization step and a high sputtering temperature (450°C) are generally lower than films processed under other conditions. This apparent reduction in the temperature for the polymorphic C49 to 54 phase transformation in TiSi2 is shown to originate from a higher nucleation density of the C54-TiSi2 phase. These dependencies of the silicide reaction are ascribed to the interfacial amorphous TiSix layer. In increasing the nucleation density of the C54-TiSi2 phase, the amorphous TiSix layer is speculated to either act as a direct nucleation source for the C54-TiSi2 phase, or lead to more defective C49-TiSi2 structures which facilitate the C54-TiSi2 nucleation.

Phase transformation and preferred orientation in carboxylate derived ZrO2 thin films on silicon substates

1992 ◽  
Vol 7 (11) ◽  
pp. 3065-3071 ◽  
Author(s):  
Peir-Yung Chu ◽  
Isabelle Campion ◽  
Relva C. Buchanan
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Phase Transformation ◽  
Heating Rate ◽  
Tetragonal Phase ◽  
Monoclinic Phase ◽  
Preferred Orientation ◽  
Si Substrate ◽  
Interfacial Diffusion ◽  
Deposited Films

Phase transformation and preferred orientation in ZrO2 thin films, deposited on Si(111) and Si(100) substrates, and prepared by heat treatment from carboxylate solution precursors were investigated. The deposited films were amorphous below 450 °C, transforming gradually to the tetragonal and monoclinic phases on heating. The monoclinic phase developed from the tetragonal phase displacively, and exhibited a strong (111) preferred orientation at temperature as low as 550 °C. The degree of preferred orientation and the tetragonal-to-monoclinic phase transformation were controlled by heating rate, soak temperature, and time. Interfacial diffusion into the film from the Si substrate was negligible at 700 °C and became significant only at 900 °C, but for films thicker than 0.5 μm, overall preferred orientation exceeded 90%.

scholarly journals Surface Texturing of Si with Periodically Arrayed Oblique Nanopillars to Achieve Antireflection

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 380
Author(s):  
Jun-Hyun Kim ◽  
Sanghyun You ◽  
Chang-Koo Kim
Keyword(s):  
Aspect Ratio ◽  
Plasma Etching ◽  
Surface Texturing ◽  
Light Reflection ◽  
Si Substrate ◽  
Weighted Mean ◽  
Optical Reflectance ◽  
Si Substrates ◽  
Aspect Ratios ◽  
Shadowing Effect

Si surfaces were texturized with periodically arrayed oblique nanopillars using slanted plasma etching, and their optical reflectance was measured. The weighted mean reflectance (Rw) of the nanopillar-arrayed Si substrate decreased monotonically with increasing angles of the nanopillars. This may have resulted from the increase in the aspect ratio of the trenches between the nanopillars at oblique angles due to the shadowing effect. When the aspect ratios of the trenches between the nanopillars at 0° (vertical) and 40° (oblique) were equal, the Rw of the Si substrates arrayed with nanopillars at 40° was lower than that at 0°. This study suggests that surface texturing of Si with oblique nanopillars reduces light reflection compared to using a conventional array of vertical nanopillars.

scholarly journals Formation and Evaluation of Silicon Substrate with Highly-Doped Porous Si Layers Formed by Metal-Assisted Chemical Etching

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Yijie Li ◽  
Nguyen Van Toan ◽  
Zhuqing Wang ◽  
Khairul Fadzli Bin Samat ◽  
Takahito Ono
Keyword(s):  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Contact Resistance ◽  
Power Factor ◽  
Chemical Etching ◽  
Porous Si ◽  
Si Substrate ◽  
Si Substrates ◽  
Output Performance ◽  
Metal Assisted Chemical Etching

AbstractPorous silicon (Si) is a low thermal conductivity material, which has high potential for thermoelectric devices. However, low output performance of porous Si hinders the development of thermoelectric performance due to low electrical conductivity. The large contact resistance from nonlinear contact between porous Si and metal is one reason for the reduction of electrical conductivity. In this paper, p- and n-type porous Si were formed on Si substrate by metal-assisted chemical etching. To decrease contact resistance, p- and n-type spin on dopants are employed to dope an impurity element into p- and n-type porous Si surface, respectively. Compared to the Si substrate with undoped porous samples, ohmic contact can be obtained, and the electrical conductivity of doped p- and n-type porous Si can be improved to 1160 and 1390 S/m, respectively. Compared with the Si substrate, the special contact resistances for the doped p- and n-type porous Si layer decreases to 1.35 and 1.16 mΩ/cm2, respectively, by increasing the carrier concentration. However, the increase of the carrier concentration induces the decline of the Seebeck coefficient for p- and n-type Si substrates with doped porous Si samples to 491 and 480 μV/K, respectively. Power factor is related to the Seebeck coefficient and electrical conductivity of thermoelectric material, which is one vital factor that evaluates its output performance. Therefore, even though the Seebeck coefficient values of Si substrates with doped porous Si samples decrease, the doped porous Si layer can improve the power factor compared to undoped samples due to the enhancement of electrical conductivity, which facilitates its development for thermoelectric application.

Heteroepitaxial Growth of 3C-SiC on Si (111) Substrate Using AlN as a Buffer Layer

2008 ◽  
Vol 600-603 ◽  
pp. 251-254 ◽  
Author(s):  
Yong Mei Zhao ◽  
Guo Sheng Sun ◽  
Xing Fang Liu ◽  
Jia Ye Li ◽  
Wan Shun Zhao ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Chemical Vapor ◽  
Heteroepitaxial Growth ◽  
Si Substrate ◽  
Si Substrates ◽  
Good Crystallinity ◽  
Aln Film ◽  
Pressure Chemical ◽  
Aln Buffer ◽  
Sic Film

Using AlN as a buffer layer, 3C-SiC film has been grown on Si substrate by low pressure chemical vapor deposition (LPCVD). Firstly growth of AlN thin films on Si substrates under varied V/III ratios at 1100oC was investigated and the (002) preferred orientational growth with good crystallinity was obtained at the V/III ratio of 10000. Annealing at 1300oC indicated the surface morphology and crystallinity stability of AlN film. Secondly the 3C-SiC film was grown on Si substrate with AlN buffer layer. Compared to that without AlN buffer layer, the crystal quality of the 3C-SiC film was improved on the AlN/Si substrate, characterized by X-ray diffraction (XRD) and Raman measurements.

Amorphous Phase Formation of Titanium Silicide on The 4° off-Axis and on-Axis Si(100) Substrates

1996 ◽  
Vol 427 ◽  
Author(s):  
Hyeongtag Jeon ◽  
Sukjae Lee ◽  
Hwackjoo Lee ◽  
Hyun Ruh
Keyword(s):  
Layer Thickness ◽  
Amorphous Layer ◽  
Film Deposition ◽  
Titanium Silicide ◽  
Atomic Scale ◽  
Phase Identification ◽  
Atomic Steps ◽  
Si Substrates ◽  
Annealing Temperatures ◽  
Scale Roughness

AbstractTwo different Si(100) substrates, the 4°off-axis and the on-axis Si(100), were prepared. Ti thin films were deposited in an e-beam evaporation system and the amorphous layers of Ti-silicide were formed at different annealing temperatures. The Si(100) substrates before Ti film deposition were examined with AFM to verify the atomic scale roughness of the initial Si substrates. The amorphous layer was observed by HRTEM and TEM. And the chemical analysis and phase identification were examined by AES and XRD. The Si(100) substrate after HF clean shows the atomic scale microroughness such as atomic steps and pits on the Si surface. The on-axis Si(100) substrate exhibits much rougher surface morphologies than those of the off-axis Si(100). These differences of atomic scale roughnesses of Si substrates result in the difference of the thicknesses of amorphous Ti-silicide layers. The amorphous layer thicknesses on the on-axis exhibit thicker than those of the off-axis Si(100) and these differences inamorphous layer thicknesses became decreased as annealing temperatures increased. These indicate that the role of the atomic scale roughness on the amorphous layer thickness is much significant at low temperatures. In this study, the correlation between the atomic scale roughness and the amorphous layer thickness is discussed in terms of the atomic steps and pits based on the observation with using analysis tools such as AFM, TEM and HRTEM.

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