Direct observation of local strain field for ULSI devices

Hashikawa, N.; Fukumoto, K.; Kuroi, T.; Ikeno, Masahiko; Mashiko, Y.

doi:10.1016/s0026-2714(98)00135-8

Cited by 5 publications

(2 citation statements)

References 2 publications

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“…TEM observations were performed using an HF-2210 transmission electron microscope (Hitachi High-Technologies). Moreover, convergent beam electron diffraction (CBED) [5][6][7][8] analysis was applied to analyze the mechanical strain at some local points of interest on cross-sectional TEM samples. CBED analysis was carried out on two samples with oxide recess amounts of 0 nm (measured value: 8 nm) and 50 nm (measured value: 60 nm).…”

Section: Contact Plugmentioning

confidence: 99%

Evaluation of the Strain around an Isolated Shallow Trench and the Impact of Stress on LSI Device Performance

Fukumoto

Kudo

Ota

et al. 2010

Jpn. J. Appl. Phys.

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We propose a stress-controlled fabrication process for shallow trench isolation (STI) that can reduce stress-originated leakage current. In this paper, the relationships between the electrical characteristics of a transistor and the STI fabrication process parameters were obtained by measurement. Direct measurements of mechanical strain around an STI structure were executed by convergent beam electron diffraction (CBED) analysis, and mechanical strain was simulated by the finite element method (FEM). Transmission electron microscopy (TEM) analysis was also performed. It was revealed that the undesirable leakage current in a transistor was caused by a dislocation in crystal silicon, which was induced by tensile strain perpendicular to the silicon surface. We also found that the mechanical strain is controllable by optimizing the amount of recess of the gap-fill oxide in the STI structure after chemical mechanical polishing (CMP).

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Section: Contact Plugmentioning

confidence: 99%

Evaluation of the Strain around an Isolated Shallow Trench and the Impact of Stress on LSI Device Performance

Fukumoto

Kudo

Ota

et al. 2010

Jpn. J. Appl. Phys.

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“…CBED is shown to be a powerful technique to investigate local stress fields in small devices in a quantitative way. [3][4][5] CBED uses a convergent incident electron beam, resulting in a diffraction pattern consisting of disks rather than spots, as is the case for diffraction with a parallel incident beam. The central disk of the CBED pattern contains a fine structure: deficiency lines corresponding with reflections at higher order Laue zones ͑HOLZ lines͒.…”

mentioning

confidence: 99%

Investigation by Convergent Beam Electron Diffraction of the Stress around Shallow Trench Isolation Structures

Stuer

Landuyt

Bender

et al. 2001

J. Electrochem. Soc.

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Convergent beam electron diffraction ͑CBED͒ is used in this study to investigate the stress distribution around shallow trench isolation ͑STI͒ structures. Attention is given to the influence of the different processing parameters and the width and spacing of the structures. The use of a wet or a dry pregate oxidation is found to have a strong influence on the stress behavior. Isolated lines show more stress, leading to the formation of defects in the silicon substrate if a wet pregate oxidation is used. The CBED analyses are compared with micro-Raman and bright-field transmission electron microscopy measurements.Shallow trench isolation ͑STI͒ is most frequently used as a lateral isolation module in deep submicrometer technologies. 1 The various processing steps cause stress fields in the STI structures, which can lead to defect formation in the silicon substrate. In their turn, stress fields affect the electrical parameters and the reliability of devices. The stress depends in addition to the processing parameters, in a large measure on the width and spacing of the STI structures.Micro-Raman spectroscopy has been a routine tool for stress evaluation of microelectronic structures 2 but fails for the currently fabricated, highly integrated 0.18 m ULSI ͑ultralarge scale integration͒ devices because of its spatial resolution, which is limited by its probe size to about 1 m. Convergent beam electron diffraction ͑CBED͒, on the contrary, has a very high spatial resolution ͑limited by its probe size and the necessary specimen tilt͒. In this study, a resolution of 30 nm is obtained. CBED is shown to be a powerful technique to investigate local stress fields in small devices in a quantitative way. [3][4][5] CBED uses a convergent incident electron beam, resulting in a diffraction pattern consisting of disks rather than spots, as is the case for diffraction with a parallel incident beam. The central disk of the CBED pattern contains a fine structure: deficiency lines corresponding with reflections at higher order Laue zones ͑HOLZ lines͒. These lines are very sensitive to lattice parameter and electron-beam voltage variations and can therefore be used for stress evaluation.In this study, stress analyses with CBED are performed around nonoptimized STI structures with various processing conditions and linewidths. ExperimentalSTI processing.-The STI structures 1 are processed on 200 mm ͑100͒-oriented p-type silicon substrates. After the deposition of a 150 nm low-pressure chemical vapor deposited ͑LPCVD͒ nitride film on a 15 nm thermal pad oxide, the active area is defined by a standard photolithography step. Subsequently, the nitride/oxide stack is etched and 0.4 m deep trenches are etched in the silicon substrate. After cleaning, a cavity etch in the pad oxide and a sidewall oxidation of 40 nm are performed. 6 The trenches are refilled using a 450 nm high-density plasma ͑HDP͒ oxide and a 100 nm LPCVD nitride. This second nitride layer is again defined by a photolithographic step as a field protecting nitride and is etched sel...

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Study of strain fields caused by crystallization of boron doped amorphous silicon using scanning transmission electron microscopy convergent beam electron diffraction method

Nakanishi

Arie

Kunimune

et al. 2012

Journal of Applied Physics

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Study of strain fields around boron doped silicon electrodes in silicon devices was carried out with scanning transmission electron microscopy convergent beam electron diffraction. Leak current, which was one of the crucial failures of this kind of structure, depends on boron concentration in the electrodes. Transmission electron microscopy and diffraction analysis showed that the electrodes consist of epitaxial phase and poly-Si phase, and the proportion of these phases depends on the boron concentration in the electrode. Strain distribution obtained with scanning transmission electron microscopy convergent beam electron diffraction revealed that the origin of the strain is volume shrinkage of the epitaxial phase in the electrode, and the poly-Si phase acts as buffer against this strain. Electron energy-loss spectroscopy analyses revealed that boron segregation occurred in samples having a higher boron concentration, and prevented epitaxial growth in the electrodes. As a result, the core of the electrode remains as poly-Si or amorphous Si and acts as strain buffer. Our analysis concluded that boron concentration in the electrodes is one of the most important factors enabling high production yield for the structure.

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Direct observation of local strain field for ULSI devices

Cited by 5 publications

References 2 publications

Evaluation of the Strain around an Isolated Shallow Trench and the Impact of Stress on LSI Device Performance

Evaluation of the Strain around an Isolated Shallow Trench and the Impact of Stress on LSI Device Performance

Investigation by Convergent Beam Electron Diffraction of the Stress around Shallow Trench Isolation Structures

Study of strain fields caused by crystallization of boron doped amorphous silicon using scanning transmission electron microscopy convergent beam electron diffraction method

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