Articles you may be interested inUltralow energy boron implants in silicon characterization by nonoxidizing secondary ion mass spectrometry analysis and soft x-ray grazing incidence x-ray fluorescence techniques High precision measurements of arsenic implantation dose in silicon by secondary ion mass spectrometry AIP Conf.The need to measure depth profiles of ultralow energy ͑ULE͒ ion implants in silicon, required for р180 nm IC device technology, has placed unprecedented requirements of high depth resolution and depth accuracy for the technique of secondary ion mass spectrometry ͑SIMS͒. The classic SIMS approaches to depth profiling ion implants employed in у250 nm device technologies are not valid for characterizing ULE implants. One reason is that the SIMS artifacts, typically observed at р30 nm, now occur in the depth range of the ULE implant. Two approaches have been proposed to overcome this. They are ͑i͒ oblique incidence bombardment, at less than 60°to the surface normal, with oxygen flooding, and ͑ii͒ normal incidence bombardment without oxygen flooding. The principle of both these approaches is the same, and requires the analytical surface to be modified to promote consistent secondary ion yields. Studies show the need to reduce the bombarding angle to Ͻ60°when using oxygen flooding. Depth profiling with this analytical condition is 3ϫ faster than by normal incidence bombardment. When using normal incidence bombardment, a greater shift towards the surface is observed due to a differential sputtering rate in the very near-surface region. With either approach, the depth resolution is the same after this initial sputtering rate increase.Oblique incidence bombardment appears to be the best approach to characterize both ''as-implanted'' and annealed ULE ion implants under ONE instrumental condition.

Techniques and applications of secondary ion mass spectrometry and spreading resistance profiling to measure ultrashallow junction implants down to 0.5 keV B and BF 2 Ultrashallow profiles challenge the capabilities of all characterization techniques. In this article, three diagnostic techniques are tested, secondary ion mass spectrometry ͑SIMS͒, capacitancevoltage (C -V) profiling and spreading resistance analysis ͑SRA͒. SIMS is used to measure the impurity concentration profiles, C -V is used to measure carrier concentration profiles directly and SRA is used to measure resistivity profiles, from which carrier concentrations can be derived. Both SIMS and SRA are calibrated techniques that relate the measured parameter to concentration or resistivity via calibration standards. C -V derives the carrier concentration directly through a mathematical model and calculation. Some of the assumptions, procedures, and limitations of these three techniques for ultrashallow profiles are reviewed and discussed. For this article these diagnostic techniques were used to examine six wafers that had been plasma doped followed by a rapid thermal anneal and three wafers that had been beamline implemented followed by a soak anneal.

Depth profiling of ultrashallow B implants in silicon using a magnetic-sector secondary ion mass spectrometry instrument J.As implant energies get lower and lower, significant errors can be present in junction depth measurements in secondary ion mass spectrometry ͑SIMS͒ ultrashallow depth profiling. Primary beam ion mixing is one of the main sources of errors leading to overestimation of junction depths in SIMS measurements. In this article, we systematically study the correlations between the implant profile trailing edge, junction depth and primary ion beam energy for low energy boron and arsenic implants. Using a mathematical deconvolution model proposed by Yang and Odom ͓Mater. Res. Soc. Symp. Proc. 669, J4.16.1 ͑2001͔͒, we are able to estimate the error of the junction depth and consistently improve the accuracy of junction depth measurements using SIMS.

Scaling metal oxide semiconductor (MOS) technology to the sub-0.1 micrometer regime faces many challenges. Shrinking MOS transistor dimensions requires the junction depth of source/drain extensions (SDEs) to be scaled by the same factor to maintain transistor immunity to short channel effects. The performance requirements, on the other hand, limit the parasitic resistance that can be tolerated in SDEs. Sheet resistance of the SDE profiles, as well as the lateral abruptness of these profiles determine the parasitic resistance. 1-3 Consequently, shrinking transistors requires more abrupt profiles and lower sheet resistances while decreasing junction depths at the same time. 4 Ion implantation has been and is projected to be the dominant technology to introduce dopants in silicon. The scaling of shallow junctions has been performed by reducing the implant energy and increasing the dose to achieve a shallower, more abrupt profile with lower sheet resistance. Secondary-ion mass spectrometry (SIMS) has been the main characterization technique to profile the implants and to measure the junction depth and total dose. However, SIMS profiling of very shallow implants can be challenging because a major fraction of the profile can fall within the surface transient of SIMS. Moreover, shallow implants can be more abrupt than the resolution of SIMS. As a result, that abrupt profiles all appear to have the same slope, is characteristic of the SIMS conditions.Arsenic was implanted in bare <100> silicon wafers at an energy of 1 keV and a dose of 1 x 10 15 /cm 2 . Silicon wafers were cleaned with a dilute HF oxide removal as the final step. Implantation was performed immediately after the clean to minimize native oxide growth. We then used a PHI ADEPT-1010 quadropole SIMS machine to do the profiling. This instrument can provide a stable, low energy primary ion beam. The crater depths were measured with a Tencor P-10 stylus profilometer. Standard grown arsenic samples were used to measure the relative sensitivity factors (RSFs) to convert the secondary-ion count to concentration. These samples are bulk doped with a known concentration of arsenic. We repeated profiling the implanted and standard samples to measure the overall repeatability of the profiling, and to monitor the drift of the machine. Figure 1 shows the SIMS profiles of the 1 keV, 1 x 10 15 /cm 2 sample using different SIMS conditions. We used a Cs primary with energies of 2 keV and 750 eV, as shown in Fig. 1a. A significant por-* Electrochemical Society Active Member. z Secondary-ion mass spectrometry (SIMS) with an ultralow energy primary ion beam was used to profile ultrashallow arsenic implants in silicon. Such shallow profiles are necessary for the formation of shallow junctions in future generations of transistors. A 750 eV Cs primary provides the best resolution in both dosimetry and depth profiling. However, even under these optimal conditions SIMS has limited resolution. We used high resolution X-ray photoelectron spectroscopy and monolayer chemical oxidation an...

No abstract