AVS 49th International Symposium
    Electronic Materials and Devices Tuesday Sessions
       Session EL+SC-TuA

Paper EL+SC-TuA9
Analysis of Ion Implantation Damage in Silicon Wafers by a Contactless Microwave Diagnostic

Tuesday, November 5, 2002, 4:40 pm, Room C-107

Session: Semiconductor Characterization
Presenter: R.K. Ahrenkiel, National Renewable Energy Laboratory
Authors: R.K. Ahrenkiel, National Renewable Energy Laboratory
B. Lojek, Atmel Corporation
Correspondent: Click to Email
Rapid thermal annealing (RTA) of ion implantation damage is required to maintain the integrity of submicron integrated circuit devices. A quick, efficient, and contactless diagnostic of the implantation damage is highly desirable. The residual radiation damage drastically reduces the recombination lifetime in the implanted region. Here, we will demonstrate the use of resonance-coupled photoconductive decay (RCPCD) technique allows us to to probe this region in boron and arsenic-implanted silicon wafers. Using a tuneable optical excitation source, we excite electron-hole pairs in the implanted region only. We compare these recombination times with those of the non-implanted bulk of the crystal. The lifetime is independent of excitation wavelength for the as-grown, oxidized wafers with typical values larger than 50 ms in semiconductor-grade silicon. After ion implantation with either arsenic or boron, the near-surface (711 nm) lifetime drops more than two orders of magnitude because of recombination at implantation-produced defects. After an RTA process, the lifetimes increase and again approach the bulk lifetime. One first group of wafers was processed in a standard rapid thermal processing (RTP) system SHS 2000 with a Hotliner. A second set of wafers were exposed to constant wavelength irradiation with maximum photon energy of approximately 1.4 eV for about 5 seconds, which has been called a "spike anneal". Our studies showed that the latter process produces wafers of lower recombination center density that the standard process. We propose some possible models to explain the improved properties of the "spike-annealed" wafers.