High-Rate PECVD of Low Defect Density a-Si:H on Large Areas

1997 ◽  
Vol 467 ◽  
Author(s):  
S. Röhlecke ◽  
O. Steinke ◽  
F. Schade ◽  
F. Stahr ◽  
M. Albert ◽  
...  
Keyword(s):  
Deposition Rate ◽  
Defect Density ◽  
Plasma Reactor ◽  
High Rate ◽  
Limiting Factors ◽  
High Deposition Rate ◽  
Large Area ◽  
Particle Generation ◽  
Wide Range ◽  
Deposition Processes

ABSTRACTIndustrial production of amorphous silicon solar cells, photoreceptors and several opto-electronic devices requires large area, high-deposition-rate plasma reactors and deposition processes. Non-uniformity of die film thickness and particle generation at high power densities as well as the deposition rate are found to be important limiting factors in large area PECVD.The deposition was performed in a capacitively-coupled coaxial diode rf glow discharge with large areas (1000 cm2 and 2000 cm2) at 13.56 MHz and 27.12 MHz. We studied the particle generation in the plasma reactor over a wide range of silane concentration (20 % to 100 %) in the SiH4/He mixture. We will present the opto-electronic properties of a-Si:H films and the influence of the substrate bias. The films are characterized by dark- and photoconductivity and by PDS.It was confirmed through this study that helium dilution is effective in the suppression of powder growth for high-rate deposition up to 18 μm/hr. Special attention was paid to the optimization of reactor design and plasma conditions for the deposition of low density of states a-Si:H (∼1016 cm−3) at deposition rates of up to 18 μm/hr. Darkconductivity was 10−9 S/cm and photoconductivity was about 5.10−4 S/cm.

Study of Large Area a-Si:H and nc-Si:H Based Multijunction Solar Cells and Materials

2008 ◽  
Vol 1066 ◽  
Author(s):  
Xixiang Xu ◽  
Baojie Yan ◽  
Dave Beglau ◽  
Yang Li ◽  
Greg DeMaggio ◽  
...  
Keyword(s):  
Solar Cells ◽  
Deposition Rate ◽  
Plasma Deposition ◽  
Nanocrystalline Silicon ◽  
High Rate ◽  
High Deposition Rate ◽  
Large Area ◽  
Very High Frequency ◽  
Spatial Uniformity ◽  
Double Junction

ABSTRACTSolar cells based on hydrogenated nanocrystalline silicon (nc-Si:H) have demonstrated significant improvement in the last few years. From the standpoint of commercial viability, good quality nc-Si:H films must be deposited at a high rate. In this paper, we present the results of our investigations on obtaining high quality nc-Si:H and a-Si:H films and solar cells over large areas using high deposition rate. We have employed the modified very high frequency (MVHF) glow discharge technique to realize high-rate deposition. Modeling studies were conducted to attain good spatial uniformity of electric field over a large area (15”×1”) MVHF cathode for nc-Si:H deposition. A comparative study has been carried out between the RF and MVHF plasma deposited a-Si:H and nc-Si:H single-junction and a-Si:H/nc-Si:H double-junction solar cells. By optimizing the nc-Si:H cell and the tunnel/recombination junctions, we have obtained an initial aperture-area (460 cm2) efficiency of 11.9% for a-Si:H/nc-Si:H double-junction cells using conventional RF (13.56 MHz) plasma deposition. The deposition rate was 3 Å/sec. Results on solar cells made with MVHF will also be presented.

VHF Large Area Plasma Processing on Moving Substrats

2001 ◽  
Vol 664 ◽  
Author(s):  
J. Kuske ◽  
U. Stephan ◽  
R. Terasa ◽  
H. Brechtel ◽  
A. Kottwitz
Keyword(s):  
Deposition Rate ◽  
Optical Emission ◽  
Plasma Source ◽  
Deposition Process ◽  
Small Scale ◽  
High Deposition Rate ◽  
Plasma Reactors ◽  
Large Area ◽  
Particle Generation ◽  
Deposition Parameters

ABSTRACTThe production of amorphous and microcrystalline silicon, e.g. for solar cells, requires large area, high-deposition rate plasma reactors. Increasing the frequency from the conventional 13.56MHz up to VHF has demonstrated higher deposition and etch rates and lower particle generation, a reduced ion bombardement and lower breakdown, process and bias voltages. But the use of VHF for large area systems leads to some problems. The non-uniformity of deposition rate increases due to the generation of standing waves and evanescent waveguide modes at the electrode surface. One possibility to process large area substrates is the use of a one-dimensional extended, homogeneous plasma source in combination with a moving substrate. The requirements, which result from the deposition process and from the RF-engineering, corresponds with the developed plasma source, using deposition frequencies in the VHF-range (50-100 MHz), almost perfectly.Using a source of 550mm length experiments were done with 81.36MHz at RF power densities of 70-180mW/cm2, silane/ hydrogen pressures of 5-30Pa and flow rates of 10-300sccm. The measured potential distribution error was ±2%. Optical emission spectroscopy delivered discharge intensity errors of ±3-10%. Deposition rates up to 20µm/h for amorphous silicon (60Å/s) and film thickness inhomogenities less than ±5% were achieved (with an area of the moved substrate of 30cm–30cm). Experimental results of the film properties will be discussed in relation to the deposition parameters and compared with complementary experiments, carried out on a small scale equipment with excitation frequencies up to 165 MHz.

Impact of Deposition Rate on the Structural and Magnetic Properties of Sputtered Ni/Cu Multilayer Thin Films

2017 ◽  
Vol 73 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Ali Karpuz ◽  
Salih Colmekci ◽  
Hakan Kockar ◽  
Hilal Kuru ◽  
Mehmet Uckun
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Deposition Rate ◽  
High Rate ◽  
Cubic Phase ◽  
High Deposition Rate ◽  
Multilayer Thin Films ◽  
Face Centered Cubic ◽  
Deposition Rates ◽  
Cu Films

AbstractThe structural and corresponding magnetic properties of Ni/Cu films sputtered at low and high deposition rates were investigated as there is a limited number of related studies in this field. 5[Ni(10 nm)/Cu(30 nm)] multilayer thin films were deposited using two DC sputtering sources at low (0.02 nm/s) and high (0.10 nm/s) deposition rates of Ni layers. A face centered cubic phase was detected for both films. The surface of the film sputtered at the low deposition rate has a lot of micro-grains distributed uniformly and with sizes from 0.1 to 0.4 μm. Also, it has a vertical acicular morphology. At high deposition rate, the number of micro-grains considerably decreased, and some of their sizes increased up to 1 μm. The surface of the Ni/Cu multilayer deposited at the low rate has a relatively more grainy and rugged structure, whereas the surface of the film deposited at the high rate has a relatively larger lateral size of surface grains with a relatively fine morphology. Saturation magnetisation, Ms, values were 90 and 138 emu/cm3 for deposition rates of 0.02 and 0.10 nm/s, respectively. Remanence, Mr, values were also found to be 48 and 71 emu/cm3 for the low and high deposition rates, respectively. The coercivity, Hc, values were 46 and 65 Oe for the low and high Ni deposition rates, respectively. The changes in the film surfaces provoked the changes in the Hc values. The Ms, Mr, and Hc values of the 5[Ni(10 nm)/Cu(30 nm)] films can be adjusted considering the surface morphologies and film contents caused by the different Ni deposition rates.

High rate growth of device grade silicon thin films for solar cells

2001 ◽  
Vol 664 ◽  
Author(s):  
M. Kondo ◽  
S. Suzuki ◽  
Y. Nasuno ◽  
A. Matsuda
Keyword(s):  
Growth Rate ◽  
Solar Cells ◽  
Defect Density ◽  
Chemical Vapor ◽  
High Growth ◽  
Ion Bombardment ◽  
High Rate ◽  
Limiting Factors ◽  
Material Quality ◽  
Deuterium Dilution

ABSTRACTWe have developed a plasma enhanced chemical vapor deposition (PECVD) technique for high-rate growth of µc-Si:H at low temperatures using hydrogen diluted monosilane source gas under high-pressure depletion conditions. It was found that material qualities deteriorate, e.g. crystallinity decreases and defect density increases with increasing growth rate mainly due to ion damage from the plasma. We have found that deuterium dilution improves not only the crystallinity but also defect density as compared to hydrogen dilution and that deuterium to hydrogen ratio incorporated in the film has a good correlation with crystallinity. The advantages of the deuterium dilution are ascribed to lower ion bombardment due to slower ambipolar diffusion of deuterium ion from the plasma. Further improvement of material quality has been achieved using a triode technique where a mesh electrode inserted between cathode and anode electrodes prevents from ion bombardment. In combination with a shower head cathode, the triode technique remarkably improves the crystallinity as well as defect density at a high growth rate. As a consequence, we have succeeded to obtain much better crystallinity and uniformity at 5.8 nm/s with a defect density of 2.6×1016cm−3. We also discuss the limiting factors of growth rate and material quality for µc-Si solar cells.

Problems of Power Feeding in Large Area PECVD of Amorphous Silicon

1999 ◽  
Vol 557 ◽  
Author(s):  
U. Stephan ◽  
J. Kuske ◽  
H. Grüger ◽  
A. Kottwitz
Keyword(s):  
Amorphous Silicon ◽  
Deposition Rate ◽  
Standing Waves ◽  
Plasma Source ◽  
High Deposition Rate ◽  
Plasma Reactors ◽  
Power Losses ◽  
Large Area ◽  
Power Coupling ◽  
Reactor Types

AbstractThe production of amorphous silicon, e.g. for solar cells, requires large area, high-deposition rate plasma reactors. Increasing the radio frequency from the conventional 13.56MHz up to VHF has demonstrated higher deposition and etch rates and lower particle generation, a reduced ion bombardement and lower breakdown, process and bias voltages.But otherwise the use of VHF leads to some problems. The non-uniformity of deposition rate increase due to the generation of standing waves (TEM wave) and evanescent waveguide modes (TE waves) at the electrode surface.Increasing the frequency and/or the deposition area the plasma impedance, the capacitic stray impedance of the RF electrode and other parasitic capacitive impedances decrease. Increasing the frequency and/or the RF power, the phase angle of the discharge and of the impedance at every point at the lines between the RF matching network an the RF electrode tends more and more towards -90°. This results in increasing currents and standing waves with extremly high local current maximas. Increasing resistances of lines and contacts due to the skin effect and loss-caused heating up of the lines the power losses increase extremely, up to 90% and more. In spite of the increasing of the coupled power, the plasma power does not increase. Thermal destructions of the lines due to extreme expansion or melting are possible.Some solutions to reduce the non-uniformity of the deposition rate like multipower feeding, central backside power feeding, electrode segmentation, use of load impedances, published in former publications, will be discussed in connection with several reactor types (coaxial, large area, long plasma source) in view of the efficiency of power coupling and the practical realization. Solutions to minimize the power losses at the lines will be presented.

Defect Density of a-Si: H(B) Prepared at High Deposition Rate with Triethylboron

1992 ◽  
Vol 134 (1) ◽  
pp. 167-181 ◽  
Author(s):  
J. Schmal ◽  
G. Kluge ◽  
A. Kottwitz ◽  
R. Bindemann ◽  
K. Schade
Keyword(s):  
Deposition Rate ◽  
Defect Density ◽  
High Deposition Rate

scholarly journals Targets for High Rate Reactive Sputtering. Propose of Reactive Sputtering using Solid Oxygen Source for Low-Temperature and High Deposition Rate Fabrication of Pb(Zr,Ti)O3 Thin Film.

Shinku ◽  
2000 ◽  
Vol 43 (8) ◽  
pp. 785-789
Author(s):  
Shinya KAWAGOE ◽  
Je-Deok KIM ◽  
Yukio YOSHIDA ◽  
Kimihiro SASAKI ◽  
Tomonobu HATA
Keyword(s):  
Thin Film ◽  
Low Temperature ◽  
Deposition Rate ◽  
Reactive Sputtering ◽  
High Rate ◽  
High Deposition Rate ◽  
Solid Oxygen

TFT Performance - Material Quality Correlation for a-Si:H Deposited at high Rates

1995 ◽  
Vol 377 ◽  
Author(s):  
S. Sherman ◽  
P-Y. Lu ◽  
R. A. Gottscho ◽  
S. Wagner
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Urbach Energy ◽  
Defect Density ◽  
High Rate ◽  
Linear Regime ◽  
Large Area ◽  
Film Properties ◽  
Deposition Power

ABSTRACTWe evaluated the characteristics of a-Si:H/a-SiNx:H thin film transistors (TFTs), and of separately deposited a-Si:H films, as functions of the a-Si:H deposition power in a high-rate, large-area, 40 MHz PE-CVD system. TFT performance and a-Si:H film properties improve with decreasing power density and deposition rate. However, low defect density a-Si:H material was deposited at rates as high as 1500 Å/min. TFTs with gate nitride deposited at 1000 A/min show excellent I-V characteristics when the a-Si:H deposition power is low enough. The TFT electron mobility in the linear regime correlates well with the Urbach energy of the a-Si:H films, suggesting that the quality of the a-Si: H controls the performance of our TFTs.

High-Deposition-Rate a-Si:H Through VHF-CVD of Argon-Diluted Silane

1997 ◽  
Vol 467 ◽  
Author(s):  
H. Meiling ◽  
J. Bezemer ◽  
R. E. I. Schropp ◽  
W. F. Van Der Weg
Keyword(s):  
Deposition Rate ◽  
Thin Film Transistors ◽  
Hydrogenated Amorphous Silicon ◽  
High Rate ◽  
High Deposition Rate ◽  
Rf Power ◽  
Bonding Configuration ◽  
Before And After ◽  
Configuration Changes ◽  
Hydrogenated Amorphous

ABSTRACTWe discuss various ways to produce hydrogenated amorphous silicon, a-Si:H, at a high deposition rate. We also present results of our recent study on the structural properties of a-Si:H films deposited at high rates using argon (Ar) dilution of silane in a 50-MHz glow discharge. The results of the depositions with Ar dilution are compared to films deposited from pure silane, SiH4. The deposition rate rd is changed by varying the rf power Prf into the discharge. We focus on the Prf-dependence of the hydrogen (H) bonding configuration and total H content in the film. It is observed that rd saturates at 14 Å/s for pure SiH4, and at 22 Å/s for Ar-diluted SiH4 deposition. Upon increase of Prf the H bonding configuration changes from mostly isolated H to mostly clustered H, and back to mostly isolated H. It is argued that Ar* metastable atoms play an important role in the growth mechanism at intermediate Prf, whereas at high Prf ion bombardment through Ar+ and ions becomes crucial. Two high-rate a-Si:H films are incorporated in thin-film transistors, TFTs. We present their characteristics before and after illumination with calibrated light. It is shown that a-Si:H TFTs with a saturation mobility of 0.7 cm2/Vs can be fabricated, with the complete intrinsic layer deposited at 20 Å/s.

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