Low-temperature Growth of Poly-Si and SiGe Thin Films by Reactive Thermal CVD and Fabrication of High Mobility TFTs over 50 cm2/Vs

2003 ◽  
Vol 762 ◽  
Author(s):  
Jun-Ichi Hanna ◽  
Kousaku Shimizu
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Silicon Germanium ◽  
Film Growth ◽  
Early Stage ◽  
Substrate Surface ◽  
Large Area ◽  
Glass Substrates ◽  
Thermal Cvd ◽  
Technical Requirements

AbstractWe have established a new thermal CVD technique, Reactive Thermal CVD, for polycrystalline silicon (poly-Si) and silicon germanium (poly-SiGe) thin films aiming at thin film transistors (TFTs) applications, in which a low substrate temperature of 450°C enables us to use glass substrates. This technique achieved high crystallinity at very early stage of the film growth, resulting no amorphous incubation layer on the substrate surface. We fabricated bottom and top gate n-and p-channel TFTs with these of 200 nm thick films on SiO2/Si wafers and glass substrates, respectively: the high field effect mobilities as high as 55 cm2/Vs and 25 cm2/Vs were achieved in the bottom-gate and top-gate TFTs, respectively. Here, we discuss the technical requirements in the low-temperature CVD technique for the large-area poly-Si thin films and how they can be achieved in the reactive thermal CVD.

Fabrication and Characterization of Polycrystalline Silicon Thin Films by Reactive Thermal CVD with Si2H6 and F2

2002 ◽  
Vol 715 ◽  
Author(s):  
J. W. Lee ◽  
K. Shimizu ◽  
J. Hanna
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Polycrystalline Silicon ◽  
Gas Flow ◽  
Film Growth ◽  
Early Stage ◽  
High Crystallinity ◽  
Thermal Cvd ◽  
Silicon Thin Films ◽  
Transmission Electron

AbstractLow-temperature growth of polycrystalline Silicon thin films has been investigated to fabricate thin film transistors by a new thermal CVD with the reactive source gases, Si2H6 and F2, resulting in the film growth at a low-temperature less than 500°C. In order to establish the optimal condition, gas pressure, total gas flow rate of Si2H6+F2 and He as a carrier gas, and residence time, τ, were tuned. Deposition rates and film crystallinity were influenced by the gas flow rations. The growth rate was 3.2-4.2[nm/min] and film uniformity was within ±6.5% over 4cm2 area. High crystallinity films showed a sharp peak at 520[cm-1] in Raman spectra whose full width at half maximum was 6-8[cm-1]. The high crystallinity even at the early stage of film growth was confirmed by transmission electron microscopy. The conductivity and activation energy is on the order of 10-5-10-6 [S/cm] and 0.53[eV], respectively, after hydrogenation. We fabricated poly-Si bottom-gate TFT that have field effect mobility as high as 32.3cm2/Vs and on/off current ratio of 104.

A Low Temperature Polycrystalline Si TFT Technology for Large area AMLCD Drivers

1997 ◽  
Vol 472 ◽  
Author(s):  
Krishna C. Saraswat ◽  
V. Subramanian ◽  
S. Jurichich
Keyword(s):  
Low Temperature ◽  
Silicon Germanium ◽  
Liquid Crystal Display ◽  
Amorphous Film ◽  
Economic Modeling ◽  
Film Deposition ◽  
Manufacturing Cost ◽  
Large Area ◽  
Device Structure ◽  
Glass Substrates

ABSTRACTIn this paper we describe a low thermal budget technology to fabricate high performance CMOS thin-film transistors (TFTs) in polycrystalline silicon and silicon/germanium on low cost glass substrates, for active-matrix liquid crystal display (AMLCD) applications. Based on modeling of delay times of the scan and data lines driven by n-channel TFTs we show that for AMLCDs with integrated drive circuits, mobility in excess of 40 cm2/V. sec will be required. Through proper optimization of amorphous film deposition, crystallization (nucleation and grain growth), fabrication process parameters and device structure we have obtained mobility in excess of 50 cm2/V. sec in Si TFTs, using conventional manufacturing technology compatible with glass substrates. Economic modeling suggests that low-temperature poly-TFT LCDs with integrated drivers will have a competitive manufacturing cost to LCDs of an equivalent size and resolution with α-Si pixel TFTs and single crystal drivers.

Deposition of Si Thin Films by Reactive CVD

1995 ◽  
Vol 377 ◽  
Author(s):  
Jun-Ichi Hanna
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Gas Phase ◽  
Film Growth ◽  
Chemical Deposition ◽  
Gas Phase Reactions ◽  
Temperature Growth ◽  
Low Temperature Growth ◽  
Thermal Cvd

ABSTRACTA new concept of Reactive CVD is proposed for the low-temperature growth of thin films by CVD and discussed in terms of general features of such film growth. One demonstrated example of the reactive CVD, called Spontaneous Chemical Deposition, features gas phase reactions of silane with fluorine is outlined in terms of the general characteristics of the film growth and properties.In addition, a second example of reactive CVD, called Reactive Thermal CVD and involving thermal CVD of poly-SiGe from germanium fluoride and disilane, is discussed and low-temperature growth using this method is reviewed.

Photo-induced Large Area Growth Of Dielectrics With Excimer Lamps

2000 ◽  
Vol 617 ◽  
Author(s):  
Ian W. Boyd ◽  
Jun-Ying Zhang
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Low Temperature ◽  
Leakage Current ◽  
Sol Gel ◽  
Low Dielectric Constant ◽  
Large Area ◽  
Excimer Lamp ◽  
Low Dielectric ◽  
Current Densities

AbstractIn this paper, UV-induced large area growth of high dielectric constant (Ta2O5, TiO2and PZT) and low dielectric constant (polyimide and porous silica) thin films by photo-CVD and sol-gel processing using excimer lamps, as well as the effect of low temperature LW annealing, are discussed. Ellipsometry, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), UV spectrophotometry, atomic force microscope (AFM), capacitance-voltage (C-V) and current-voltage (I-V) measurements have been employed to characterize oxide films grown and indicate them to be high quality layers. Leakage current densities as low as 9.0×10−8 Acm−2 and 1.95×10−7 Acm−2 at 0.5 MV/cm have been obtained for the as-grown Ta2O5 films formed by photo-induced sol-gel processing and photo-CVD. respectively - several orders of magnitude lower than for any other as-grown films prepared by any other technique. A subsequent low temperature (400°C) UV annealing step improves these to 2.0×10−9 Acm−2 and 6.4× 10−9 Acm−2, respectively. These values are essentially identical to those only previously formed for films annealed at temperatures between 600 and 1000°C. PZT thin films have also been deposited at low temperatures by photo-assisted decomposition of a PZT metal-organic sol-gel polymer using the 172 nm excimer lamp. Very low leakage current densities (10−7 A/cm2) can be achieved, which compared with layers grown by conventional thermal processing. Photo-induced deposition of low dielectric constant organic polymers for interlayer dielectrics has highlighted a significant role of photo effects on the curing of polyamic acid films. I-V measurements showed the leakage current density of the irradiated polymer films was over an order of magnitude smaller than has been obtained in the films prepared by thermal processing. Compared with conventional furnace processing, the photo-induced curing of the polyimide provided both reduced processing time and temperature, A new technique of low temperature photo-induced sol-gel process for the growth of low dielectric constant porous silicon dioxide thin films from TEOS sol-gel solutions with a 172 nm excimer lamp has also been successfully demonstrated. The dielectric constant values as low as 1.7 can be achieved at room temperature. The applications investigated so far clearly demonstrate that low cost high power excimer lamp systems can provide an interesting alternative to conventional UV lamps and excimer lasers for industrial large-scale low temperature materials processing.

Direct Nucleation of Crystalline SiGe on Substrates by Reactive Thermal CVD with Si2H6 and GeF4

1997 ◽  
Vol 467 ◽  
Author(s):  
Fumio Yoshizawa ◽  
Kunihiro Shiota ◽  
Daisuke Inoue ◽  
Jun-ichi Hanna
Keyword(s):  
Growth Rate ◽  
Gas Phase ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Film Growth ◽  
Early Stage ◽  
Gaseous Mixture ◽  
The Other ◽  
Thermal Cvd ◽  
Initial Deposition

ABSTRACTPolycrystalline SiGe (poly-SiGe) film growth by reactive thermal CVD with a gaseous mixture of Si2H6 and GeF4 was investigated on various substrates such as Al,Cr, Pt, Si, ITO, ZnO and thermally grown SiO2.In Ge-rich film growth, SEM observation in the early stage of the film growth revealed that direct nucleation of crystallites took place on the substrates. The nucleation was governed by two different mechanisms: one was a heterogeneous nucleation on the surface and the other was a homogeneous nucleation in the gas phase. In the former case, the selective nucleation was observed at temperatures lower than 400°C on metal substrates and Si, where the activation of adsorbed GeF4 on the surface played a major role for the nuclei formation, leading to the selective film growth.On the other hand, the direct nucleation did not always take place in Si-rich film growth irrespective of the substrates and depended on the growth rate. In a growth rate of 3.6nm/min, the high crystallinity of poly-Si0.95Ge0.05in a 220nm-thick film was achieved at 450°C due to the no initial deposition of amorphous tissue on SiO2 substrates.

Dependence of Film Thickness on Properties of Al Doped ZnO Thin Films

2011 ◽  
Vol 194-196 ◽  
pp. 2305-2311
Author(s):  
Ying Ge Yang ◽  
Dong Mei Zeng ◽  
Hai Zhou ◽  
Wen Ran Feng ◽  
Shan Lu ◽  
...  
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Electrical Parameter ◽  
Substrate Surface ◽  
Rf Magnetron Sputtering ◽  
Thickness Effect ◽  
Visible Range ◽  
Glass Substrates ◽  
Doped Zno

In this study high quality of Al doped ZnO (ZAO) thin films were prepared by RF magnetron sputtering on glass substrates at room temperature in order to study the thickness effect upon their structure, electrical and optical properties. XRD results show that the films are polycrystalline and with strongly preferred (002) orientation perpendicular to substrate surface whatever the thickness is. The crystallite size was calculated by Williamson-Hall method, while it increases as the film thickness increased. The lattice stress is mainly caused by the growth process. Hall measurements revealed electrical parameter very dependent upon thickness when the thickness of ZAO film is lower than 700 nm. The resistivity decreased and the carrier concentration and Hall mobility increases as the film thickness increased. When film thickness becomes larger, only a little change in the above properties was observed. All the films have high transmittance above 90% in visible range. Red shift of the absorption edge was observed as thickness increased. The optical energy bandgap decreased from 3.41eV to 3.30 eV with the increase of film thickness.

Low Temperature (≤550°C) Fabrication of CMOS TFT's on Rapid-Thermal CVD Polycrystalline Silicon-Germanium Films

1997 ◽  
Vol 36 (Part 1, No. 3B) ◽  
pp. 1389-1393 ◽  
Author(s):  
Seo-Kyu Lee ◽  
Seong-Min Choe ◽  
Chang-Geun Ahn ◽  
Wook-Jin Chung ◽  
Young-Kyu Kwon ◽  
...  
Keyword(s):  
Low Temperature ◽  
Silicon Germanium ◽  
Polycrystalline Silicon ◽  
Thermal Cvd ◽  
Germanium Films

CuxSbySz THIN FILMS PRODUCED BY ANNEALING CHEMICALLY DEPOSITED Sb2S3-CuS THIN FILMS

2001 ◽  
Vol 15 (17n19) ◽  
pp. 667-670 ◽  
Author(s):  
Y. RODRÍGUEZ-LAZCANO ◽  
M. T. S. NAIR ◽  
P. K. NAIR
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Optical Band Gap ◽  
Deposition Method ◽  
Photovoltaic Devices ◽  
Large Area ◽  
Electrical And Optical Properties ◽  
Ternary Compounds ◽  
Glass Substrates ◽  
Different Temperatures

The possibility of generating ternary compounds through annealing thin film stacks of binary composition has been demonstrated before. In this work we report a method to produce large area coating of ternary compounds through a reaction in solid state between thin films of Sb2S3 and CuS. Thin films of Sb2S3 -CuS were deposited on glass substrates in the sequence of Sb2S3 followed by CuS (on Sb2S3 ) using chemical bath deposition method. The multilayer stack, thus produced, of approximately 0.5 μm in thickness, where annealed under nitrogen and argon atmospheres at different temperatures to produce films of ternary composition, CuxSbySz . An optical band gap of ~1.5 eV was observed in these films, suggesting that the thin films of ternary composition formed in this way are suitable for use as absorber materials in photovoltaic devices. The results on the analyses of structural, electrical and optical properties of films formed with different combinations of thickness in the multilayers will be discussed in the paper.

scholarly journals Effect of Halogen on the Structure of Low Temperature Polycrystalline Silicon Thin Films Fabricated on Glass Substrates.

1999 ◽  
Vol 107 (1251) ◽  
pp. 1099-1104 ◽  
Author(s):  
Toshio KAMIYA ◽  
Yoshiteru MAEDA ◽  
Kouichi NAKAHATA ◽  
Takashi KOMARU ◽  
Charles M. FORTMANN ◽  
...  
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Polycrystalline Silicon ◽  
Glass Substrates ◽  
Silicon Thin Films
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