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High throughput ion implanter for environmentally beneficial products with III-V compound semiconductor
Abstract
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 sources are a key part of the experimental base of charged particle beam physics. These are devices capable of generating beams of positive and negative gas and metal ions, which are used: in radiation materials science [1] to modify the structure of structural steels in order to increase their resistance to negative processes (increased brittleness, swelling, loss of strength, etc.) that develop under the influence of constant neutron irradiation; in the production of multicomponent semiconductors [2] to create various types of modern materials for electronics; in medicine [3] for proton and carbon therapy, boron-neutron therapy, for the production of a wide range of isotopes; at research accelerator complexes and etc. ...
Ion implantation processing of electronic materials and devices uses a wide variety of accelerator systems and end station designs as well as many special techniques. After a concise outline of the basics of accelerator components (ions sources, ion acceleration, beam and wafer scanning), examples of commercial ion implantation systems for medium and high current, high energy, plasma immersion as well as special tools for doping of large-area flat-panels and photo-voltaic cells are described in a tutorial fashion for their component layout, accelerator, beam/wafer scanning mechanisms and performance characteristics in terms of ion energy range and beam current and special capabilities.
Ion doping tools which have ability to process large size glass substrate with high productivity are briefly described. Such tools might develop new fields that utilize ion implantation technology. So far we tried several applications. In this study, three applications for which large area treatment will be essential to commercial production are reported.
Triple‐junction solar cells from III–V compound semiconductors have thus far delivered the highest solar‐electric conversion efficiencies. Increasing the number of junctions generally offers the potential to reach even higher efficiencies, but material quality and the choice of bandgap energies turn out to be even more importance than the number of junctions. Several four‐junction solar cell architectures with optimum bandgap combination are found for lattice‐mismatched III–V semiconductors as high bandgap materials predominantly possess smaller lattice constant than low bandgap materials. Direct wafer bonding offers a new opportunity to combine such mismatched materials through a permanent, electrically conductive and optically transparent interface. In this work, a GaAs‐based top tandem solar cell structure was bonded to an InP‐based bottom tandem cell with a difference in lattice constant of 3.7%. The result is a GaInP/GaAs//GaInAsP/GaInAs four‐junction solar cell with a new record efficiency of 44.7% at 297‐times concentration of the AM1.5d (ASTM G173‐03) spectrum. This work demonstrates a successful pathway for reaching highest conversion efficiencies with III–V multi‐junction solar cells having four and in the future even more junctions. Copyright © 2014 John Wiley & Sons, Ltd. In this work, a GaAs‐based top tandem solar cell structure was bonded to an InP‐based bottom tandem cell with a difference in lattice constant of 3.7%. The result is a GaInP/GaAs//GaInAsP/GaInAs four‐junction solar cell with a new record efficiency of 44.7% at 297‐times concentration of the AM1.5d (ASTM G173‐03) spectrum. This work demonstrates a successful pathway for reaching highest conversion efficiencies with III‐V multi‐junction solar cells having four and in the future even more junctions.
In a multi-cusp ion source, magnetic boundaries, together with the difference between plasma potential and plasma chamber potential, functioned as a mass filter which filters out heavier ions in multi-component plasmas. This method was applied to mixed inert gas plasmas and hydrogen plasmas and found to be very effective for general purposes which require to decrease unwanted heavier ions. Using this method to the ion source of iG4, target boron current above 80 mA and proton current above 120 mA were obtained.
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.
We describe a new technique which allows a large dimension III-V
thin film to be transferred on a full silicon wafer. The potential
applications of this technology to InP are: spatial solar cells and
integration of optic functions on silicon. This original process,
developed at the LETI and called IMPROVE or Smart-CutR, is based on
proton implantation and wafer bonding. Proton implantation enables
delamination of a thin monocrystalline layer from a thick substrate to
be achieved whereas the wafer bonding enables the transfer of the
delaminated layer onto a second substrate. The thickness of the film to
be transferred is directly determined by the hydrogen ion implantation
energy. The implanted substrate can be reclaimed after transfer. Today,
one of the best known applications of Smart-CutR is the Silicon On
Insulator structure. The Smart-CutR process is suitable for different
kinds of applications and the principle of this process can be applied
to various materials (Si, SiC, GaAs, ...). Application of this process
to transfer of thin InP films onto silicon is presented here
Enabling InP based high efficiency CPV cells through substrate engineering and direct wafer bonding
- E Guiot
- B Ghyselen
- F Dimroth
- T Signamarcheix