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0912-C03-11

PN Junction Formation for High-Performance Insulated Gate Bipolar Transistors; Double-Pulsed Green Laser Annealing Technique Toshio Joshua Kudo, and Naoki Wakabayashi R & D Center, Sumitomo Heavy Industries Ltd., 19 Natsushima-cho, Yokosuka-shi, Kanagawa-ken, 237-8555, Japan ABSTRACT In order to form the deep PN junction demanded for the next generation IGBTs, the double-pulsed laser annealing technique as the low-thermal budget heat treatment has been introduced to activate a B-implant layer and a P-implant layer within the wafer surface to the depth 2µm. The double-pulsed laser annealing is characterized by the deep penetration depth due to a green wavelength of DPSS lasers and precisely and widely controlling of the annealing temperature and time. In the IGBT’s structure the deep PN junction at a collector (the rear face) should be formed without damaging thermally circuit elements made of low melting point materials at a gate and an emitter (the front face). Ion-implant samples using eight-inch (100) Si wafers were prepared as follows: Boron (B) implant was performed at a dose of 1E+15/cm2 at an energy of 40keV and/or phosphorus (P) implant at 1E+13/cm2 at an energy of 400keV. The double-pulsed laser irradiation was carried out at the constant first and second pulse energy density E1=E2=1.8J/cm2 at the delay time td= 0-500ns and the overlap ratio OR=67-90%. The melt depth was up to about 0.3µm. The electrical activation ratio of the B-implant layer within the depth of about 0.6µm was improved from 91% to about 100% with the delay time increase of 0ns to 500ns. The activation ratio of the P-implant layer within the depth of about 2µm was drastically improved from 48% to 82% with the same delay time increase and the carriers in the P-implant layer were distributed deeply from the depth 1.1µm to 1.8µm. Furthermore, with the overlap ratio increase of 67% to 90% the carriers in the P-implant layer were distributed deeply from the depth 1.8µm to 1.9µm and the high activation ratio of 82% was maintained. The high ratio of electrical activation is supported by the defect-free epitaxial regrowth where the majority of the B dopants was diffused in the liquid phase and that of the P dopants in the solid phase. INTRODUCTION From the standpoint of low electric power consumption of electronic equipments, power semiconductor devices used as power amplifiers, converters, and inverters play an important role, in which insulated gate bipolar transistors (IGBTs) are a major device. The IGBT characteristics have been improved with the shrink of the chip size and the wafer thickness, replacing epitaxial wafers with cost-effective FZ wafers [1-3]. In order to implement the characteristics improvement with the further chip volume reduction, it needs to overcome a technical challenge to the PN junction formation, that is, the wafer backside implant and the low-thermal budget activation. In the IGBT’s structure the deep PN junction at a collector (the rear face) should be formed without damaging thermally circuit elements m