Mechanical stress analysis of an LDD MOSFET structure

Journal of Applied Physics

Armigliato

Wolf

et al. 2003

100

Articles you may be interested inConvergent beam electron diffraction measurements of relaxation in strained silicon using higher order Laue zone line splitting J. Appl. Phys. 105, 063526 (2009); 10.1063/1.3093693 Convergent beam electron diffraction investigation of strain induced by Ti self-aligned silicides in shallow trench Si isolation structures J. Appl. Phys. 99, 064504 (2006); 10.1063/1.2179136 Strain analysis in silicon substrates under uniaxial and biaxial stress by convergent beam electron diffraction J. Vac. Sci. Technol. B 23, 940 (2005); 10.1116/1.1924583Determining the relationship between local lattice strain and slip systems of dislocations around shallow trench isolation by convergent-beam electron diffraction Test structures consisting of shallow trench isolation ͑STI͒ structures are fabricated using advanced silicon ͑Si͒ technology. Different process parameters and geometrical features are implemented to investigate the residual mechanical stress in the structures. A technology computer aided design homemade tool, IMPACT, is upgraded and optimized to yield strain fields in deep submicron complementary metal-oxide-semiconductor devices. Residual strain in the silicon substrate is measured with micro-Raman spectroscopy ͑-RS͒ and/or convergent beam electron diffraction ͑CBED͒ for large ͑25 m͒ and medium size ͑2 m͒, while only CBED is used for deep submicron STI ͑0.22 m͒. We propose a methodology combining CBED and technology computer aided design ͑TCAD͒ with -RS to assess the accuracy of the CBED measurements and TCAD calculations on the widest structures. The method is extended to measure ͑by CBED͒ and calculate ͑by TCAD͒ the strain tensor in the smallest structures, out of the reach of the -RS technique. The capability of determining, by both measurement and calculation, the strain field distribution in the active regions of deep submicron devices is demonstrated. In particular, it is found that for these structures an elastoplastic model for Si relaxation must be assumed.

Section: Introductionmentioning

confidence: 99%

Strain determination in silicon microstructures by combined convergent beam electron diffraction, process simulation, and micro-Raman spectroscopy

Journal of Applied Physics

Armigliato

Wolf

et al. 2003

100

“…As the film and the substrate thermal expansion coefficients are different, there is a thermal mismatch due to the differences of the strains in the materials: (1) where and are the linear thermal coefficients of the film and the substrate, respectively.…”

Section: Thermal Stressesmentioning

confidence: 99%

“…We have developed a tool (IMPACT [1][2][3]) for the design of micro-technologies. Its capabilities represent a clear innovation with respect to conventional finite element methods for the study of mechanical stresses in micro-technologies.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of the process-induced stresses in silicon microstructures

Hoffmann²,

Armigliato

et al. 2004

SPIE Proceedings

Residual stresses can significantly affect the performances of silicon micro-structures. The understanding of the residual stress growth during their processing is of great importance. However, the experimental tracing of the stresses at the various stages of the machining is still almost impossible. Quantitative modelling of these problems is the alternative to provide guidelines for the minimization of the residual stresses. In this paper, we describe a technology computer aided design homemade tool, IMPACT. The mechanical models and the numerical implementation are presented. We give details about our methodology to calibrate and validate our implementation. The originality of this study lies in i) the capability to simulate almost all the sources of stress taking into account of the complex rheological behaviours of the materials, ii) the experimental determination of the mechanical properties of various thin film materials and iii) the validation of the calculations by direct comparisons with measured deformations in the micro-structures.

“…where ⌬S is the film surface change ͑positive for absorption and negative for evaporation͒, ⌬Q the water dose variation (cm Ϫ1 ), and H 2 O is the density of water (g/cm 3 ). This quantity can then be converted into a mechanical strain load:…”

Section: Mechanical Modelsmentioning

confidence: 99%

“…A few years ago we began the development of a homogeneous and advanced stress simulation system included in our homemade software tool IMPACT. [3][4][5] Our most recent study concerns the introduction of the rheological behavior of polycrystalline microelectronic materials exhibiting elastoplastic properties during large stress solicitation. 6 A simple elastic perfectly plastic model has been implemented.…”

Section: Introductionmentioning

confidence: 99%

Mechanical analysis of interconnected structures using process simulation

Journal of Applied Physics

Hoffmann

Duc

et al. 2003

An elastoplastic model has been implemented in a technology computer-aided design (TCAD) program with the aim of predicting the mechanical behavior of polycrystalline materials used in silicon-based technology in microelectronics. In order to analyze microstructures combining both nonlinear viscoelastic and elastoplastic materials, we propose a computational process with quick convergence. This model is now included in a stress simulation system, thus allowing the prediction of variations in stress according to the stage of the process. The modeling takes into account not only thermal stress but also intrinsic/extrinsic stresses and etching-related stress. The stress evolution of aluminum copper (Al–Cu) periodic lines embedded within silicon dioxide has been examined. The tensile and compressive yield strengths of thin-film Al–Cu have been characterized using the von Mises criterion for various film thicknesses. Comparisons with experimental results, based on passivated and unpassivated line structures, show that von Mises yield stress is independent of linewidth. It was also found that the correct prediction of the principal stresses strongly depends on the accurate characterization of thin-film yield strength. The use of incorrect values can lead to large errors in the determination of the line aspect ratio giving the maximum principal stresses. Finally, the analysis of an industrial back end of line process is performed to demonstrate what we can now carry out with TCAD to solve stress-related reliability problems in interconnects.