No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Increase of Beam Current Mass-Separated by Long Gap Dipole Sector Magnet for S/D Process in FPD manufacturing
Abstract
A mass analyzing ion implantation system (called Ion Doping iG4) was developed for FPD
manufacturing. One of most important concept of iG4 is to transport a sheet ion beam maintaining its current density profile from the ion source to the target, which leads good mass resolution and simple control of the beam profile. The system has a bucket type ion source which provides a sheet ion beam whose longer dimension of the cross section is 800 mm the 4th generation FPD glass substrate generally sized 730mm × 920mm. The sheet ion beam is mass‐analyzed with a dipole sector magnet with a long pole gap. In order to enhance through‐put for Source Drain implantation processes, we modified the ion source to increase high beam currents and obtained 300μA/cm for Boron
ion beams and 500μA/cm for Phosphorus ion beams. Better uniformity and higher mass resolution were achieved by optimizing shape of the analyzing magnet pole faces.
... For implantation at high doses and over large surface areas, it is advantageous in many cases to utilize simplified acceleration strategies that do not use mass selection or multiple stage acceleration (Fig. 2). One version of this approach is to use a large area ion source in an "ion shower" system with the ion acceleration coming from a DC-bias at the ion source and target at ground (Dohi 2006). An alternative method is to "immerse" the target in or at the boundaries of a plasma and to extract ions from the plasma with short pulses of negative bias voltages applied to the target, called "plasma immersion ion implantation" (PIII) (Anders 2000). ...
... For acceleration energies above 10 keV, generation of x-rays arising from acceleration of secondary electrons from the target surfaces becomes a problem. Many ion shower systems incorporate large-area magnetic mass analysis that isolates the secondary electrons from the source extraction potentials (Dohi 2006). For PIII systems that use high voltage pulsing, the target surface can be enclosed with an assembly at the target potential and linked to a remote plasma source through a small-area aperture (Fig. 2, right) (Matossian 1996). ...
Accelerator and plasma-based ion implantation continues to be the dominant method for doping of semiconductor materials for fabrication of microelectronics. In recent years, ion implantation has also been increasingly used for fabrication advanced forms of semiconductor materials, in particular, various types of silicon-on-insulator (SOI) substrates for high-performance logic and memories as well as photonic waveguides and detectors. The combination of high voltages and high energy ions, toxic dopant materials, high vacuum environments and high electrical and mechanical stored energies call for high level of rigor in the design, operation and maintenance of ion implantation equipment and support facilities. The requirements for doping of semiconductor device layers continue to push the boundaries of accelerator operations, for example, with the use of >5 MeV energies for fabrication of optical sensory arrays. The proliferation of ion types used for doping, in particular, the commercialization of large dopant-containing molecules containing 10 to several thousand dopants, has extended the useful dose range of ion implantation at the high end and improved wafer throughputs for 200 eV equivalent dopant energies for shallow junction formation. These and other developments have led to new ion implantation systems designs that will be examined in terms of the new challenges for radiation and toxic materials exposures.
For the manufacturing process of display for mobile devices using Low Temperature Poly-crystalline Silicon Thin Film Transistor (LTPS-TFT), ion doping processes have been required. Nissin developed ion doping systems which were referred as iG series and they have already been used in production lines of many panel makers. In these systems, the basic concept of ion source and beam line has been unchanged. We use a multi-cusp ion source with hot cathodes to produce source plasma. Ribbon shaped ion beams extracted through a large area plasma electrode system are introduced into an analyzing magnet and only the dopant ions are transported to the target. In our ion source, the ratio of B+ in BF3 plasma can be increased by applying positive potential to a plasma electrode with respect to plasma chamber, whereas that of BF2+, BF+, F+ can be selectively decreased. This allows obtaining higher B+ beam currents from the ion source efficiently. In addition, the position of the filaments inside the plasma chamber is optimized for B+ beam extraction. However, for PHx+ beam extraction, the position was not switched. We developed a new mechanism which could adjust the position of the filaments without breaking high vacuum. The filament position can be changed by using the metal bellows expansion joint attached to the plasma chamber. By this mechanism, the filament position can be optimized for both of B+ and PHx+ beam extraction. For example, in iG6, if we inserted the filaments 30 mm deeper than original filament position into the plasma chamber, we could decrease arc current by 40% to obtain the same PHx+ beam current.
We have developed an ultra-high current ion implantation system for high throughput wafer processing. The ion source is designed based on implanters used in the flat panel display industry to produce 80 cm high beams which exceed 80 mA. Multiple wafers are processed at a time with the large-sized beam. The implantation tool exhibited throughput of 107 and 38 wafers per hour for 1E16 and 1E17 ions/cm2, respectively. Successful InP layer transfer with smooth surface was demonstrated using Smart Cut™ technology.
Ion beam instabilities on a wide ribbon beam which cross-section is 150 cm × 10 cm are discussed. At low energy conditions, we detected two kinds of instabilities on the ion beam extracted from BF3 plasmas. One kind of the instabilities is that onset of the instability is dependent on the extraction current from the ion source. This instability occurred when the extraction current exceeded 300 - 350 mA at the energy of 15keV. Another is that the onset is dependent on the BF2+ beam current. The BF2+ beam current became unstable when it exceeded about 20 μA/cm2 at 15keV. Energy dependence of these instabilities is also discussed.
ResearchGate has not been able to resolve any references for this publication.