Romain Duru

Combining metrology techniques for in-line control of thin SiGe:B layers

Abstract. A study performed to evaluate the benefits of combining techniques to improve the overall metrology of thin silicon germanium (SiGe) epitaxial layers doped with boron is presented. A specifically designed set of wafers was processed and measured by different in-line metrology tools and characterization techniques. This study describes the best strategy for combining metrology techniques in order to reliably determine dopant concentration and Ge composition measurement of the layers. It demonstrates that combined metrology enables key improvements in manufacturing and engineering environments.

Hydrogen passivation of silicon/silicon oxide interface by atomic layer deposited hafnium oxide and impact of silicon oxide underlayer

HfO2 synthesized by atomic layer deposition (ALD) can be used as a passivation material for photodetectors. This paper shows a significant reduction of density of interface traps at the Si/SiO2 interface using ALD HfO2. This is explained by a chemical passivation effect due to presence of hydrogen from water used in the ALD process. Furthermore, ALD HfO2 layers appear negatively charged which generate an additional field effect passivation. The impact of the SiO2 underlayer is also discussed by comparing a chemical silicon oxide to a standard thermal silicon oxide. It is shown that chemical silicon oxide can act as a reservoir of hydrogen atoms which helps to reduce the density of defects close to the Si/SiO2 interface. This result demonstrates the importance of the surface preparation before the ALD of HfO2 in the passivation scheme. Finally, this work shows the correlation between negatively charged defects and Si–O–Hf bonds at the SiO2/HfO2 interface. A passivation stack composed of chemical oxide perm...

HRXRD for in-line monitoring of advanced FD-SOI technology: Use-cases: AM: Advanced metrology

This paper describes specific applications illustrating the use of High Resolution X-Ray Diffraction (HRXRD) for the inline control of advanced logic technology nodes. More specifically, an innovative strategy based on HRXRD rocking-curve analysis is described for the control of epitaxial SiGe layers on Fully Depleted Silicon On Insulator (FD-SOI) wafers including consideration of the strategy for managing the tilt between the SOI layer and the bulk silicon substrate. Furthermore, the quality of HRXRD Reciprocal Space Maps (RSMs) obtained in an industrial environment is demonstrated and the benefit of RSMs for inline control is discussed.

Benefit of combining metrology techniques for thin SiGe:B layers

This paper presents a study performed to evaluate the benefits of combining techniques to improve the overall metrology of thin Silicon Germanium (SiGe) epitaxial layers doped with Boron. A specifically-designed set of wafers was processed and measured by different in-line metrology tools and characterization techniques. This study describes the best strategy for combining metrology techniques in order to reliably determine dopant concentration and Ge composition measurement of the layers. It demonstrates that combined metrology enables key improvements in manufacturing and engineering environments.

MBIR for in-line doping metrology of epitaxial SiGe:B and SiC:P layers

This paper describes a study performed to evaluate in a manufacturing environment the Model Based Infrared Reflectometry (MBIR) technique for the monitoring of the Boron doping in epitaxial SiGe:B layers and Phosphorus doping in epitaxial SiC:P layers. MBIR correlation to comparative techniques is demonstrated on multiple wafer sets, including product wafers on bulk silicon and FD-SOI (Fully Depleted Silicon On Insulator) substrates. The results obtained demonstrate that MBIR is a suitable measurement technique for the in-line monitoring of doping for epitaxial SiGe:B and SiC:P layers.

Photoluminescence for in-line buried defects detection in silicon devices

In this work, a novel imaging photoluminescence-based metrology method is introduced, with potential application to buried defect detection in silicon devices during semiconductor manufacturing process. The theoretical and practical aspects are both discussed. A new metrology tool was realized and thoroughly tested through real-life semiconductor samples to reveal the capabilities of the suggested method. According to the results, defects down to the sub-micron size range can be optically detected, as confirmed by cross-sectional transmission electron microscopy images.

Oxidation kinetics of Si and SiGe by dry rapid thermal oxidation, in-situ steam generation oxidation and dry furnace oxidation

The fabrication of ultrathin compressively strained SiGe-On-Insulator layers by the condensation technique is likely a key milestone towards low-power and high performances FD-SOI logic devices. However, the SiGe condensation technique still requires challenges to be solved for an optimized use in an industrial environment. SiGe oxidation kinetics, upon which the condensation technique is founded, has still not reached a consensus in spite of various studies which gave insights into the matter. This paper aims to bridge the gaps between these studies by covering various oxidation processes relevant to todays technological needs with a new and quantitative analysis methodology. We thus address oxidation kinetics of SiGe with three Ge concentrations (0%, 10%, and 30%) by means of dry rapid thermal oxidation, in-situ steam generation oxidation, and dry furnace oxidation. Oxide thicknesses in the 50 A to 150 A range grown with oxidation temperatures between 850 and 1100 °C were targeted. The present work shows first that for all investigated processes, oxidation follows a parabolic regime even for thin oxides, which indicates a diffusion-limited oxidation regime. We also observe that, for all investigated processes, the SiGe oxidation rate is systematically higher than that of Si. The amplitude of the variation of oxidation kinetics of SiGe with respect to Si is found to be strongly dependent on the process type. Second, a new quantitative analysis methodology of oxidation kinetics is introduced. This methodology allows us to highlight the dependence of oxidation kinetics on the Ge concentration at the oxidation interface, which is modulated by the pile-up mechanism. Our results show that the oxidation rate increases with the Ge concentration at the oxidation interface.The fabrication of ultrathin compressively strained SiGe-On-Insulator layers by the condensation technique is likely a key milestone towards low-power and high performances FD-SOI logic devices. However, the SiGe condensation technique still requires challenges to be solved for an optimized use in an industrial environment. SiGe oxidation kinetics, upon which the condensation technique is founded, has still not reached a consensus in spite of various studies which gave insights into the matter. This paper aims to bridge the gaps between these studies by covering various oxidation processes relevant to todays technological needs with a new and quantitative analysis methodology. We thus address oxidation kinetics of SiGe with three Ge concentrations (0%, 10%, and 30%) by means of dry rapid thermal oxidation, in-situ steam generation oxidation, and dry furnace oxidation. Oxide thicknesses in the 50 A to 150 A range grown with oxidation temperatures between 850 and 1100 °C were targeted. The present work sho...

Use of X-Ray Techniques for In-Line Control of Epitaxial Layers in Advanced FDSOI Technology

This paper describes specific applications illustrating the use of high resolution X-ray diffraction (HRXRD) for the inline control of epitaxial films for advanced logic technology nodes. More specifically, an innovative strategy based on HRXRD rocking-curve analysis is described for the control of epitaxial SiGe and SiC layers on fully depleted silicon on insulator wafers. This includes consideration in the strategy for managing the tilt between the SOI layer and the bulk silicon substrate. The robustness of such approach is demonstrated for specific use cases. The benefit of combining HRXRD and X-ray reflectometry techniques is also illustrated specifically for the application of Ge composition measurement of ultrathin SiGe films (<10 nm). Finally, examples of HRXRD reciprocal space maps obtained in an industrial environment is demonstrated for the case of both SiGe and SiC materials embedded in periodical structures.

Metal Removal Efficiency in Deep Submicron Trenches by Wet Chemicals

Metal contamination impact on transistors’ degradation has been widely studied. Nonetheless, most of the work has been performed on blanket wafers, or based on punctual yield crisis during the integrated circuits’ manufacturing. This paper proposes a comparison of the contamination and metals removal efficiency between blanket wafers and inside deep silicon trenches.