Low resistivity tungsten for contact metallization

Smith, Steven W.; Aouadi, Khaled; Collins, Jeff; Vegt, Eric van der; Basso, M.-T.; Juhel, M.

doi:10.1016/j.mee.2005.07.032

Cited by 24 publications

(14 citation statements)

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“…1,2 Schottky diodes have a low capacitance and recovery time and are also being studied as they are found in source drain contacts in silicon based MOSFETs. [3][4][5][6][7] For an n-type semiconductor to metal interface, the potential barrier formed is the energy difference between the Fermi level of the metal and the bottom of the conduction band in the semiconductor. For a p-type semiconductor to metal interface, the potential barrier formed is the energy difference between the Fermi level of the metal and the top of the valance band in the semiconductor.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale mapping of the W/Si(001) Schottky barrier

Durcan

Balsano

LaBella

2014

Journal of Applied Physics

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The W/Si(001) Schottky barrier was spatially mapped with nanoscale resolution using ballistic electron emission microscopy (BEEM) and ballistic hole emission microscopy (BHEM) using n-type and p-type silicon substrates. The formation of an interfacial tungsten silicide is observed utilizing transmission electron microscopy and Rutherford backscattering spectrometry. The BEEM and BHEM spectra are fit utilizing a linearization method based on the power law BEEM model using the Prietsch Ludeke fitting exponent. The aggregate of the Schottky barrier heights from n-type (0.71 eV) and p-type (0.47 eV) silicon agrees with the silicon band gap at 80 K. Spatially resolved maps of the Schottky barrier are generated from grids of 7225 spectra taken over a 1 lm Â 1 lm area and provide insight into its homogeneity. Histograms of the barrier heights have a Gaussian component consistent with an interface dipole model and show deviations that are localized in the spatial maps and are attributed to compositional fluctuations, nanoscale defects, and foreign materials. V C 2014 AIP Publishing LLC. [http://dx

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Section: Introductionmentioning

confidence: 99%

Nanoscale mapping of the W/Si(001) Schottky barrier

Durcan

Balsano

LaBella

2014

Journal of Applied Physics

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“…[7][8][9][10][11] In this study, on B 2 H 6 -based ALD-W film, the resistivity of CVD-W film ͑50 nm in thickness͒ was 18.2-19.4 ⍀ cm, while it was 23.1-25.5 ⍀ cm on the SiH 4 -based one. The resistivity of CVD-W film could be further reduced when we added the B 2 H 6 pretreatment and post-treatment.…”

mentioning

confidence: 93%

“…6,7 In fact, it has been reported that the resistivity of bulk CVD-W film could be reduced by using a B 2 H 6 -based W nucleation layer as compared to a SiH 4 -based one, and even more, the resistivity increase by the size effect could be mitigated. [7][8][9][10][11] It was also reported that the structural properties of the B 2 H 6 -based W nucleation layer, such as its phase ͑amorphous, ␤, and ␣-phase͒, crystallinity, and grain size, could be controlled by varying the B 2 H 6 flow rate and its pulsing time during deposition, which had a significant effect on the final grain size and resistivity of the CVD-W film subsequently grown on it. 7 Thus, all the results show that a B 2 H 6 used for preparing a W nucleation layer seems to play an important role in reducing the resistivity of CVD-W film.…”

mentioning

confidence: 99%

Improvement of Adhesion Performances of CVD-W Films Deposited on B[sub 2]H[sub 6]-Based ALD-W Nucleation Layer

Kim¹,

Rho²,

Kim³

et al. 2009

Electrochem. Solid-State Lett.

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The resistivity of chemical-vapor-deposited ͑CVD͒-W film was reported to be significantly reduced using a B 2 H 6 -based atomic layer deposited ͑ALD͒-W nucleation layer for continuously shrinking memory devices. But, we found that the adhesion performances of CVD-W films growing on the B 2 H 6 -based ALD-W nucleation layer were poor compared to those on the SiH 4 -based W nucleation layer. Scanning electron microscopy and secondary ion mass spectrometry analysis clearly suggest that the boron penetration into the interface between underlying TiN and SiO 2 during the deposition of W nucleation layer is a possible reason to degrade the adhesion performances of CVD-W films with B 2 H 6 -based W nucleation layers. By rigorous selection of both the deposition conditions for W nucleation layer and diffusion barrier materials, we can demonstrate the successful deposition of CVD-W film with a very low resistivity of ϳ12 ⍀ cm ͑50 nm in thickness͒ without an adhesion failure. Noticeably, the application of 5 nm thick sputter-deposited WN x film as a glue layer was found to present an excellent adhesion performance, which was due to its excellent diffusion barrier performance with amorphous structure.Chemical-vapor-deposited ͑CVD͒-W thin film has a long tradition as a metallization material for fabricating the interconnects of semiconductor devices. Generally, CVD-W film has been used for plugging processes or filling the contact or via plug with a high aspect ratio for multilevel metallization of semiconductor devices 1-3 due to its excellent step coverage. CVD-W is even being considered as a word line and a metal line in the damascene trench structure of memory devices. But, as the metal linewidth in the semiconductor devices shrinks to the sub 50 nm dimensions, the electron mean-free path of W ͑ϳ41 nm͒ 4 becomes comparable with some of its physical dimension such as film thickness, surface roughness, and grain size, resulting in the drastic increase in the resistance of the metal line, which is called "size effect." 5 Thus, to overcome the size effect on the resistivity of W film and realize the excellent speed performance of the circuit, a new process on CVD-W film should be investigated.Generally, CVD-W films are deposited by a two-step process: a deposition of a very thin W nucleation layer and a subsequent growth of relatively thick bulk-W film. This gives the possibility that the properties of the CVD-W film, including its resistivity, can be controlled and improved by controlling the process of the W nucleation layer because the underlying film can have considerable effects on the properties of the metal film growing on it. 6,7 In fact, it has been reported that the resistivity of bulk CVD-W film could be reduced by using a B 2 H 6 -based W nucleation layer as compared to a SiH 4 -based one, and even more, the resistivity increase by the size effect could be mitigated. 7-11 It was also reported that the structural properties of the B 2 H 6 -based W nucleation layer, such as its phase ͑amorphous, ␤, and ␣-phase͒, cr...

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“…The B 2 H 6 -reduced W nucleation layer technology followed by the deposition of CVD-W film using CVD reaction of WF 6 and H 2 has been known to decrease the resistivity of CVD-W film [1,2].…”

Section: Introductionmentioning

confidence: 99%

Integration of Low Resistive CVD-W Interconnects for sub-50nm FEOL application

Kim¹,

Rho²,

Rouh³

et al. 2008

2008 International Interconnect Technology Conference

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Low resistive tungsten (LRW) interconnects using CVD-W films deposited on B 2 H 6 -reduced W nucleation layers have been successfully developed for FEOL application of sub-50nm dynamic random access memory (DRAM). LRW poly-metal gate showed excellent gate oxide integrity, low sheet resistance, low parasitic capacitance, and excellent transistor performances such as ring-oscillator delay comparable to PVD-W based polymetal gate. In the bit line application, as the feature size was decreased, the contact resistance and sheet resistance of LRW bit line were decreased drastically compared to conventional CVD-W process. However, the properties of junction leakage current and saturation drain current (Idsat) of NMOS transistor were degraded due to the penetration of boron into the junction. In order to depress the junction degradation, the improvement of barrier properties of gluelayer and optimization of LRW process were suggested.

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Low resistivity tungsten for contact metallization

Cited by 24 publications

References 0 publications

Nanoscale mapping of the W/Si(001) Schottky barrier

Nanoscale mapping of the W/Si(001) Schottky barrier

Improvement of Adhesion Performances of CVD-W Films Deposited on B[sub 2]H[sub 6]-Based ALD-W Nucleation Layer

Integration of Low Resistive CVD-W Interconnects for sub-50nm FEOL application

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