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The leakage current of p-n junctions is one of the important parameters that degrades the performance of devices such as transistors, photodiodes, etc. It is well known that excess leakage current of p-n junction diodes can be caused by the presence of crystalline defects 1 or metal contamination, 2 introduced during device processing. However, decades of defect engineering studies have provided semiconductor manufacturing with powerful tools for defect and contamination control, e.g., internal and external gettering. 3 Finally, the presence of high mechanical stress levels at the field isolation regions of the junctions can lead to the generation of extended defects 4,5 and yield-related problems, as recently demonstrated in Ref. 5. In this paper the impact of specific processing steps compatible with a 0.35 m complementary metal-oxide semiconductor (CMOS) process on the diode leakage and yield are studied and discussed. Infrared light scattering tomography (IR-LST) is used wherever applicable for analyzing the diodes. ExperimentalDevice fabrication.-In these experiments 6 in. (150 mm) Si<100> oriented, Czochralski-grown p-type wafers with a resistivity of 16-24 ⍀ cm were used. The n ϩ p diodes were formed in a p-type substrate or in a p-well. The boron doping density in the p-type substrate is less than 10 15 cm Ϫ3 and in the p-well about 2 ϫ 10 17 cm Ϫ3 . Device isolation is made using two isolation techniques, namely, conventional local oxidation of silicon (LOCOS) (60 nm pad oxide/120 nm Si 3 N 4 ) and poly buffered locos (PBL) (20 nm pad oxide/50 nm amorphousSi/200 nm Si 3 N 4 ). After nitride etch, field implantation was performed (1.5 ϫ 10 13 cm Ϫ2 B at 120 keV) for diodes in p-type substrates with LOCOS and PBL isolations to counter substrate inversion at the isolation-substrate interface, followed by an anneal in N 2 ambient at 975ЊC. The field implantation dose was not varied because it had no influence on the effects studied in this work. The field oxide was grown at 975ЊC in H 2 /O 2 to a thickness of 500 nm. After LOCOS and PBL etchback removal of the active-region blocking layers, a sacrificial oxide of 50 nm was grown at 950ЊC in H 2 /O 2 . The p-well was made using boron with doses in the range 10 12 to 10 13 cm Ϫ2 implanted at several energies. n ϩ p diodes were formed using As ϩ implantation at 75 keV with doses of about 10 15 cm Ϫ2 , followed by a furnace anneal (FA) at 900ЊC or rapid thermal anneal (RTA) at 1100ЊC. Ramp-up and ramp-down rates for RTA are 50ЊC/s and have been kept constant. The carrier concentration of the n ϩ layer after activation is about 10 20 cm Ϫ3 . After FA the junctions are 0.2 m deep and after RTA the depth is 0.17 m, as obtained from spreading resistance profiling (SRP) and secondary ion mass spectroscopy (SIMS) measurements. The diodes are directly contacted by AlSiCu metal with a Ti/TiN barrier layer. Finally, a sintering treatment at 420ЊC in H 2 /N 2 was performed.Device characterization and parameter extraction.-Automatic measurements of the leakage current at 5...

This paper presents the NORMAN/DEBORA TCAD system developed at IMEC to design and optimize sub-micron IC technology using process and device simulators. The versatility of the TCAD system will be shown for two important problems encountered in IC technology design and optimization.

In this work the Deal-Grove (DG) oxidation model, being the key ingredient in many current oxidation models, has been examined in detail from the physical and numerical point of view. It is clearly proven that for a rather broad range of (B/A, B) combinations the fitting error is smaller than the experimental error. So there exists a wide range of allowable parameters of the Deal-Grove model to satisfy different physical explanations. This means that a good fit alone is not a sufficient criterion to validate a possible physical model. It is also demonstrated that the existence of breakpoints in the temperature behavior could be seen as an artifact of the model parameters extraction procedure normally used. Therefore, a new and efficient parameter extraction strategy, which carefully considers the influence of experimental errors, is suggested in this work. As an example, a physically acceptable expression for the parameters in the HCl-oxidation is found as a substitute for the look-up table used in SUPREM-3.The Deal-Grove model (1) has been used over more than twenty years to describe the silicon oxidation process. This model is based on an equilibrium process between the. diffusion of the oxidizing species through the oxide layer and the reaction of this species at the interface, resulting in both a parabolic and a linear growth rate component.Although th!s model is widely being used to describe the oxidation process, it suffers from a lack of accuracy mainly for the description of the growth of thin layers. To modify this model in the initial phase of dry oxidation, a lot of models were proposed over the last decade: e.g., oxide charge effects (2), chemisorption (3), structural channels (4), stress effects (5), parallel independent diffusion mechanisms of the oxidizing species in the oxide film (6, 7), and interface potential effects (8).Nearly all of these models exhibit a quite good data fitting, although they are based on some different physical assumptions and in most cases exclude each other implicitly. The .data fitting and the observations of the variation of the linear-rate constant B/A and the parabolic-rate constant B of the Deal-Grove model as a function of some factors (e.g., temperature, 02 pressure, HCI%...), are the usual way to provide evidence for the proposed models. For example, some authors have observed breakpoints in the In (B/A) vs. 1/KT and in (B) vs. 1/KT plots, and to explain these breakpoints the stress effect has been proposed (5).However, in this work, it will be indicated that there exists an inherent problem with the Deal-Grove model parameters (linear-parabolic law) which may raise some questions about a number of physical phenomena which are used to explain some observed effects. In effect, it turns out that the "exact" values of the parameters B/A and B are quite insensitive to the Deal-Grove model, especially when the oxide fitting range is getting smaller. Namely, by allowing a domain of sets of (B/A, B) values, the fitting error for many (B/A, B) combinations is less than th...

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