Qualitative Model for Surface Rippling of Zone Melting Recrystallized Silicon-on-Insulator Layers

1989 ◽  
Vol 157 ◽  
Author(s):  
Paul W. Mertens ◽  
Herman E. Maes

ABSTRACTIn zone melting recrystallization (ZMR) of thin silicon films different mechanisms can lead to thickness variations of the obtained silicon film. In this paper we will concentrate on some of these phenomena. One is the large scale mass transport, which typically leads to a thinned region at the start of the ZMR process. Another one, which is to a certain extent related to the first one, is the typical ripple formation that occurs especially under conditions that are commonly referred to as “low thermal gradient” regime.

1985 ◽  
Vol 53 ◽  
Author(s):  
M. Haond ◽  
D. Dutartre ◽  
R. Pantel ◽  
A. Straboni ◽  
B. Vuillermoz

ABSTRACTIn the preparation of SOI films by Zone Melting Recrystallization (ZMR) a cap layer is necessary to avoid the beading up of a silicon film when it is molten over silicon. This is a consequence of a bad wetting of liquid Si on SiO2. We report the successful application of a plasma nitridation treatment of the capping oxide. We compare the behaviour of the liquid silicon films during ZMR for different capping structures. The modification of the interface is investigated by using Auger analysis. We show that a range of nitrogen accumulation at the interface provides a good wetting.


1984 ◽  
Vol 35 ◽  
Author(s):  
C. E. Bleil ◽  
J. R. Troxell

ABSTRACTLaser processing of thin films of amorphous or polycrystalline silicon on insulator substrates, such as the glass normally used for liquid crystal displays, frequently leads to film thickness variations which are unacceptable for device fabrication. Some thickness variations are caused by the high surface tension of molten silicon and the poor adhesion of the silicon to the substrate. Techniques to reduce this problem by increasing the adhesion of the film to silicon dioxide coated Corning 7059 glass substrates have been investigated. Two different approaches were used. First, silicon ions were implanted into the silicon-glass interface to increase the direct bonding of the silicon to the silicon dioxide. Second, layers of material known to exhibit better adhesion to both silicon and silicon dioxide were introduced between the silicon film and the glass substrate. Both techniques produced films which, after subsequent laser processing, showed significantly reduced thickness variations. These procedures make it possible to laser process thin films of silicon on Corning 7059 glass substrates under conditions which produce large grain polysilicon films without producing unacceptably large thickness variations or film cracking.


1985 ◽  
Vol 53 ◽  
Author(s):  
M. W. Geis ◽  
C. K. Chen ◽  
Henry I. Smith ◽  
P. M. Nitishin ◽  
B-Y. Tsaur ◽  
...  

ABSTRACTSince the introduction of zone-melting recrystallization (ZMR)for silicon-on-insulator (SOI) films, subboundaries (low-angle grain boundaries) have been the major crystalline defects in recrystallized films. By using an improved ZMR procedure, subboundaries have been eliminated over large areas. The improvements include the use of 1-µm-thick polycrystalline-Si films deposited on 2-µm-thick thermal SiO2 film (instead of 0.5-µm-thick Si and SiO2 films), a new encapsulation technique, and improved control of the thermal gradient during ZMR. Recrystallized SOI films without subboundaries contain isolated dislocations with densities <2 × 106 cm−2.


1990 ◽  
Vol 67 (12) ◽  
pp. 7337-7347 ◽  
Author(s):  
P. W. Mertens ◽  
J. Leclair ◽  
H. E. Maes ◽  
W. Vandervorst

2006 ◽  
Vol 912 ◽  
Author(s):  
Justin J Hamilton ◽  
Erik JH Collart ◽  
Benjamin Colombeau ◽  
Massimo Bersani ◽  
Damiano Giubertoni ◽  
...  

AbstractFormation of highly activated, ultra-shallow and abrupt profiles is a key requirement for the next generations of CMOS devices, particularly for source-drain extensions. For p-type dopant implants (boron), a promising method of increasing junction abruptness is to use Ge preamorphizing implants prior to ultra-low energy B implantation and solid-phase epitaxy regrowth to re-crystallize the amorphous Si. However, for future technology nodes, new issues arise when bulk silicon is supplanted by silicon-on-insulator (SOI). Previous results have shown that the buried Si/SiO2 interface can improve dopant activation, but the effect depends on the detailed preamorphization conditions and further optimization is required. In this paper a range of B doses and Ge energies have been chosen in order to situate the end-of-range (EOR) defect band at various distances from the back interface of the active silicon film (the interface with the buried oxide), in order to explore and optimize further the effect of the interface on dopant behavior. Electrical and structural properties were measured by Hall Effect and SIMS techniques. The results show that the boron deactivates less in SOI material than in bulk silicon, and crucially, that the effect increases as the distance from the EOR defect band to the back interface is decreased. For the closest distances, an increase in junction steepness is also observed, even though the B is located close to the top surface, and thus far from the back interface. The position of the EOR defect band shows the strongest influence for lower B doses.


Author(s):  
Keiya Ishiyama ◽  
Ryo Koike ◽  
Yasuhiro Kakinuma ◽  
Tetsuya Suzuki ◽  
Takanori Mori

Additive manufacturing (AM) for metals has attracted attention from industry because of its great potential to enhance production efficiency and reduce production costs. Directed energy deposition (DED) is a metal AM process suitable to produce large-scale freeform metal products. DED entails irradiating the baseplate with a laser beam and launching the metal powder onto the molten spot to produce a metal part on the baseplate. Because the process enables powder from different materials to be used, DED is widely applicable to valuable production work such as for a dissimilar material joint, a graded material, or a part with a special structure. With regard to parts with a special structure, directional solidification can prospectively be used in the power plant and aerospace industries because it can enhance the stiffness in a specific direction via only a simple process. However, conventional approaches for directional solidification require a special mold in order to realize a long-lasting thermal gradient in the part. On the other hand, from the viewpoint of thermal distribution in a produced part, DED is able to control the gradient by controlling the position of the molten pool, i.e., the position of the laser spot. Moreover, unlike casting, the thermal gradient can be precisely oriented in the expected direction, because the laser supplies heat energy on the regulated spot. In this study, the applicability of DED to directional solidification in Inconel® 625 is theoretically and experimentally evaluated through metal structure observation and Vickers hardness measurements. Furthermore, the effect of two different cooling processes on directional solidification is also considered with the aim of improving the mechanical stiffness of a part produced by DED. The observations and experimental results show that both the cooling methods (baseplate cooling and intermittent treatment with coolant) are able to enhance the hardness while retaining the anisotropy.


Author(s):  
Slobodan Mitric

A recent study requested by a group of mayors representing the largest Polish cities is summarized. The study was to be used as input into local and national debates about future directions of urban transport development in the country. The wider context is that of a major political and economic reform, begun in the late 1980s, involving no less than a rapidpaced transition from socialism to capitalism, featuring large-scale downsizing of the public sector, privatization, and a redistribution of political and resource powers from the state to local governments. Among the downstream effects of these changes has been an increase in private car ownership and use and a reduction in the market share of urban mass transit modes from between 80 and 90 percent of nonwalk daily trips to 70 percent or less. For transit operators, now owned by local governments, this has meant an added financial pressure coming after a decade of underinvestment in infrastructure, rolling stock, and other equipment. Large numbers of unemployed, retired, or otherwise low-income travelers, another consequence of restructuring the economy, have made it difficult to improve cost recovery by increasing fares. Traffic growth has generated congestion, since the structure and size of urban road networks were predicated on low car use. An urban transport strategy is proposed to respond to these problems. Its main short-term objective is to have an affordable and socially and environmentally acceptable modal split. In the longer term, the objective is to use the demand response to a much-reformed price system as the principal guide to how infrastructure and services should evolve. The key features of the strategy are as follows: ( a) evolution toward market-supplied services by a mixed-ownership mass transport industry; ( b) treatment of urban road networks as public utilities, focusing on cost recovery through pricing; ( c) linkage of pricing policies for mass transport and individual transport modes, in line with second-best thinking, aiming to reduce and even eliminate subsidies for both modes; and ( d) reliance on internally generated revenue leveraged by long-term borrowing to finance sectoral investments. It is therefore a counterpoint to a strategy wherein mass transport is a state-owned monopoly, the use of urban roads is subsidized as is mass transport, infrastructure investment is the instrument of preference as opposed to pricing, and sectoral investments and operating subsidies are financed from tax-generated budgets.


1993 ◽  
Vol 316 ◽  
Author(s):  
H. H. Hosack

Silicon-On-Insulator (SOI) technology [1-4] has been shown to have significant performance and fabrication advantages over conventional bulk processing for a wide variety of large scale CMOS IC applications. Advantages in radiation environments has generated significant interest in this technology from military and space science communities [5,6]. Possible advantages of SOI technology for low power, low voltage and high performance circuit applications is under serious consideration by several commercial IC manufacturers [7,8].


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