Precursor design and engineering for low-temperature deposition of gate dielectrics for thin film transistors

2011 ◽  
Vol 1287 ◽  
Author(s):  
Anupama Mallikarjunan ◽  
Laura M Matz ◽  
Andrew D Johnson ◽  
Raymond N Vrtis ◽  
Manchao Xiao ◽  
...  
Keyword(s):  
Thin Film ◽  
Low Temperature ◽  
Thin Film Transistors ◽  
Moisture Absorption ◽  
Silicon Oxide ◽  
Chemical Vapor ◽  
Silicon Oxycarbide ◽  
Process Conditions ◽  
Structure Property ◽  
Oh Groups

ABSTRACTThe electrical and physical quality of gate and passivation dielectrics significantly impacts the device performance of thin film transistors (TFTs). The passivation dielectric also needs to act as a barrier to protect the TFT device. As low temperature TFT processing becomes a requirement for novel applications and plastic substrates, there is a need for materials innovation that enables high quality plasma enhanced chemical vapor deposition (PECVD) gate dielectric deposition. In this context, this paper discusses structure-property relationships and strategies for precursor development in silicon nitride, silicon oxycarbide (SiOC) and silicon oxide films. Experiments with passivation SiOC films demonstrate the benefit of a superior precursor (LkB-500) and standard process optimization to enable lower temperature depositions. For gate SiO2 deposition (that are used with polysilicon TFTs for example), organosilicon precursors containing different types and amounts of Si, C, O and H bonding were experimentally compared to the industry standard TEOS (tetraethoxysilane) at different process conditions and temperatures. Major differences were identified in film quality especially wet etch rate or WER (correlating to film density) and dielectric constant (k) values (correlating to moisture absorption). Gate quality SiO2 films can be deposited by choosing precursors that can minimize residual Si-OH groups and enable higher density stable moisture-free films. For e.g., the optimized precursor AP-LTO® 770 is clearly better than TEOS for low temperature PECVD depositions based on density, WER, k charge density (measured by flatband voltage or Vfb); and leakage and breakdown voltage (Vbd) measurements. The design and development of such novel precursors is a key factor to successfully enable manufacturing of advanced low temperature processed devices.

Pentacene Thin Film Transistors and Circuits: Influence of Processing and Device Design

2002 ◽  
Vol 725 ◽  
Author(s):  
D. Knipp ◽  
R. A. Street ◽  
B. Krusor ◽  
J. HO
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Silicon Oxide ◽  
Chemical Vapor ◽  
Self Assembled Monolayers ◽  
Flexible Substrates ◽  
Thermal Oxide ◽  
Chemical Vapor Deposited ◽  
Structural And Electronic Properties ◽  
Assembled Monolayers

AbstractThe influence of different dielectrics on the structural and electronic properties of pentacene films and TFTs is discussed. The pentacene films were thermally evaporated on inorganic dielectrics compatible with flexible substrates. A strong correlation between morphology and structural properties of the pentacene films and the mobility of the TFTs was observed for all the dielectrics studied. In the case of plasma enhanced chemical vapor deposited (PECVD) silicon nitride and silicon oxide dielectrics the growth of pentacene is mainly determined by the roughness of the dielectric. The roughness inhibits the ordering of pentacene molecules on the surface. However, by optimizing the fabrication process of the dielectrics, we have achieved similar pentacene mobilities on PECVD dielectrics and thermal oxide (0.4 cm2/Vs), without employing self-assembled monolayers like octadecyltrichlorosilane (OTS). An OTS treatment of oxide based dielectrics leads to an increase of the mobility by a factor of 2-3 up to >1cm2/Vs for thermal oxide. Pentacene films on inorganic dielectrics exhibit mobilities from of 0.2-1.2 cm2/Vs and high on/off ratios between 107 and 108.

Poly-SiGe TFTs Fabricated by Low Temperature Chemical Vapor Deposition at 450°C

2001 ◽  
Vol 686 ◽  
Author(s):  
Kousaku Shimizu ◽  
Jianjun Zhang ◽  
Jeong-woo Lee ◽  
Jun-ichi Hanna
Keyword(s):  
Thin Film ◽  
Chemical Vapor Deposition ◽  
Low Temperature ◽  
Vapor Deposition ◽  
Thin Film Transistors ◽  
Gas Flow ◽  
Chemical Vapor ◽  
Polycrystalline Materials ◽  
Si Substrates ◽  
Vapor Deposition Technique

AbstractLow temperature growth of poly-SiGe has been investigated by reactive thermal chemical vapor deposition technique, which is a newly developed technique for preparing polycrystalline materials with using redox reactions in a set of source materials, Si2H6 and GeF4.. In order to prepare high uniformity and reproducibility of Si-rich poly-SiGe, total pressure, gas flow ratio, and residence time are optimized at 450°C of substrate temperature. Through optimizing the conditions, poly-Si1−xGex (x<0.04) films have been prepared in the reproducibility more than 90% and uniformity more than 88%. Bottom gate type of n-channel thin film transistors has been fabricated in various grain size of poly-Si1−xGex on SiO2 (100nm)/Si substrates. 5-36 cm2/Vs of field effect mobility of thin film transistors (L/W = 50μm/50μm) have been achieved after hydrogenation, whose threshold voltage is around 2±0.5V, and on/off ratio is more than 104.

Nanocrystalline Silicon by Microwave CVD for Thin Film Transistors and Solar Cells

2000 ◽  
Vol 638 ◽  
Author(s):  
Young J. Song ◽  
Hak-Gyu Lee ◽  
Lihong Teng ◽  
Wayne A. Anderson
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Thin Film Transistors ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Dark Conductivity ◽  
Antireflection Coating ◽  
Process Conditions ◽  
Hydrogen Dilution ◽  
Partial Pressures

AbstractMicrowave chemical vapor deposition (MCVD) is utilized to deposit nanocrystalline silicon (nc-si) thin films onto a variety of substrates for application to thin film transistors (TFT's) and solar cells. It is especially important to gain reproducible control of the processing. Thus, an in-situ mass spectrometer (MS) records the plasma conditions with variation of process conditions such as gas selection, pressures, partial pressures, and substrate temperature. These data are correlated with electrical and optical properties of the films. Raman spectra show a FWHM of 11/cm with position at 522/cm as desired for crystalline Si. Typical film thickness is 100nm with grain size of 20-30 nm, using standard deposition, and 50-80 nm when the substrate is intensely optically illuminated during deposition, called photon assist (PA). Hydrogen dilution serves to increase the crystallinity of the films. The ratio of photo-to dark conductivity exceeds 10+5 with dark conductivity as low as 1.5 × 10-10 S/cm. Thin film transistors have been fabricated with Ion/Ioff of 10+7. Hetrojunction solar cells were fabricated using amorphous Si/ nc-Si/ crystlline Si giving a conversion efficiency of above 10.5%, without an antireflection coating. The use of MS in device design will be emphasized.

Characteristics of SiO2 Film Grown by Atomic Layer Deposition as the Gate Insulator of Low-Temperature Polysilicon Thin-Film Transistors

2007 ◽  
Vol 124-126 ◽  
pp. 247-250 ◽  
Author(s):  
Won Jun Lee ◽  
Min Ho Chun ◽  
Kwang Su Cheong ◽  
Kwang Chol Park ◽  
Chong Ook Park ◽  
...  
Keyword(s):  
Thin Film ◽  
Low Temperature ◽  
Atomic Layer Deposition ◽  
Thin Film Transistors ◽  
Chemical Vapor ◽  
Atomic Layer ◽  
Gate Insulator ◽  
Sio2 Films ◽  
Layer Deposition ◽  
Better Than

SiO2 films were prepared by atomic layer deposition (ALD) technique, and their physical and electrical properties were characterized for being applied as a gate insulator of low-temperature polysilicon thin-film transistors. ALD SiO2 films were deposited at 350–400 oC using alternating exposures of SiH2Cl2 and O3/O2, and the characteristics of the deposited films were improved with increasing deposition temperature. The ALD films deposited at 400 oC exhibited integrity, surface roughness and leakage current better than those of the conventional plasma-enhanced chemical vapor deposition (PECVD) films.

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