Study of Strain Induction for Metal–Oxide–Semiconductor Field-Effect Transistors using Transparent Dummy Gates and Stress Liners

Self Cite

It is expected to be necessary to measure the stress tensors in Si because the stress field in the channels of metal–oxide–semiconductor field-effect transistors is remarkably complicated. Raman spectroscopy enables us to evaluate the stress precisely, nondestructively, and with relatively high spatial resolution, although its standard implementation fails to resolve the stress tensor. The goal of this study is to establish a procedure for measuring an unknown plane-stress state. In this study, the anisotropic biaxial stress in Si induced by a SiN film was evaluated by Raman spectroscopy with an immersion objective lens with a high numerical aperture.

Section: Introductionmentioning

confidence: 99%

Evaluation of Anisotropic Biaxial Stress by Raman Spectroscopy with a High Numerical Aperture Immersion Objective Lens

Kosemura

Takei

Nagata

et al. 2010

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“…7(a), the compressive strain at the channel edge was larger than that at the channel center in the pMOSFETs. This result indicated that strain enhancement due to the superposition of strain in channel edges, which was often observed for a large gate length by Raman measurement, 10,13,29) occurred even at the 32 nm gate length. However, this U-shape strain profile was not observed in the nMOSFETs [Fig.…”

Section: Resultsmentioning

confidence: 56%

Channel Strain Measurement in 32-nm-Node Complementary Metal–Oxide–Semiconductor Field-Effect Transistor by Raman Spectroscopy

Takei

Hashiguchi

Yamaguchi

et al. 2012

Self Cite

We performed a strain analysis of a 32-nm-node microprocessing unit by Raman spectroscopy in conjunction with transmission electron microscopy. The channel surface was exposed by chemical etching and mechanical polishing for Raman spectroscopy. Some defects and Ge concentration variation were observed in embedded SiGe of a p-channel metal–oxide–semiconductor field-effect transistor (pMOSFET). Uniform defects lying at the same angle were observed in the source and drain regions of an n-channel MOSFET (nMOSFET). From the Raman measurement, the Raman peak from strained Si in the pMOSFET shifted toward a higher frequency at approximately 7.5 cm-1, which corresponds to -3.75 GPa (compressive) under the assumption of uniaxial stress along the channel direction. On the other hand, the Raman peak shift from strained Si in the nMOSFET was -1.7 cm-1 corresponding to 0.85 GPa (tensile) under the assumption of uniaxial stress. From the nanobeam diffraction measurements, the compressive strain at the channel edge was larger than that at the channel center in the pMOSFET. On the other hand, the tensile strain in the nMOSFET was induced uniformly in the channel region. We think that understanding and control of channel strain introduction are indispensable in the state-of-the-art complementary MOSFET technology.

“…Therefore, it is very important to calibrate the simulation including the extraction of stress parameters as well as the fidelity of both the profiles and the boundaries of the materials used in the transistors. In the calibration for stress simulation, ultraviolet (UV) Raman spectroscopy is an attractive technique for measuring local stress [9][10][11][12][13][14][15][16] because Raman signals from Si substrates are restricted to approximately 10 nm from surface regions if an excitation wavelength of 364 nm is used, although the spatial resolution is slightly higher than that of NBD or CBED. Namely, it is sufficient for the calibration that the stress at the surface region, where the normal stress components are relaxed, can be predicted exactly by simulation.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, polarization analysis of Raman spectra can provide information about the stress tensor for calibrating the stress simulation. 15,16) In this paper, we describe the extraction of the stress parameters of materials used in transistors by calibrating them at each process step. We also describe the layout dependences of the Raman shifts from the offset spacer regions of the transistors in conjunction with the simulated ones.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Stress Evaluation of Si Metal–Oxide–Semiconductor Field-Effect Transistor Structure Using Polarized Ultraviolet Raman Spectroscopy Measurements and Calibrated Technology-Computer-Aided-Design Simulations

Satoh

Tada

Poborchii

et al. 2011

The mechanical stresses in Si metal–oxide–semiconductor field-effect transistors (MOSFETs) were evaluated by polarized UV Raman spectroscopy measurements and stress simulations. To calibrate stress parameters of the materials used in the Si MOSFETs, we compared measured and simulated Raman frequency shifts on the cleaved Si(110) surfaces of the MOSFETs. Consequently, we extracted intrinsic stress values of -400 MPa for a SiO2, -200 MPa for polycrystalline Si (poly-Si), 700 MPa for Ni silicide, 1250 MPa for a SiN tensile stress liner, and -3500 MPa for a SiN compressive stress liner by finding good agreement between the measured and simulated Raman shift distributions. To verify our stress simulation, we investigated the source/drain width dependences of Raman frequency shifts near the channel regions of Si MOSFETs by top-view Raman measurements. The calculated Raman frequency shifts agreed well with the results of polarized Raman measurements in terms of not only relative tendencies but also absolute Raman shift values.