Dopant segregation in polycrystalline silicon

Mandurah, Mohammad M.; Saraswat, Krishna C.; Helms, C. R.; Kamins, Theodore I.

doi:10.1063/1.327582

Cited by 377 publications

(118 citation statements)

References 24 publications

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“…The measured values for the resistivity and for the temperature coefficient are of the same order of magnitude as those found in the literature [23,24,29,30,321. The strong decrease in resistivity after annealing for 30 s or less, or after annealing at low temperatures, see Fig.…”

Section: Discumionsupporting

confidence: 75%

In situ phosphorus-doped polysilicon for excitation and detection in micromechanical resonators

Bouwstra

Weerd

Elwenspoek

1990

Sensors and Actuators A: Physical

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Low-pressure chemical vapour deposited (LPCVD) in situ phosphorus-Dodd polysilicon films have been grown from a 60:30:300 seem silane:phosphine (2000 ppm):nitrogen mass-flow mixture at 625 "C under varied process conditions. Thickness uniformity, grain size, dopant concentration, resistivity, temperature coefficient of resistivity, longitudinal strain gauge factor and the temperature coefficient of the gauge factor are determined. A growth rate with a non-uniformity (30) of 5% is obtained, yielding films with a grain size of 20-30 nm and a surface roughness of 12 nm (peak-to-valley heights), both before and after annealing, and a dopant concentration of (2-3) x lpcrn3.Resistivities of the order of 1 II-&~ cm can be obtained with a temperature coefficient close to zero after annealing at 900 "C for 30 min, with a longitudinal gauge factor of -20 and a temperature coefficient of the gauge factor of -0.25%/"C. A mechanism incorporating the diffusion of dislocations during annealing is proposed to explain the observed effect. The films are appropriate for application as resistors for thermal excitation and piezoresistive detection in resonating micromechanical devices, Resonating micromechanical structures consist of an element for the excitation and an element for the detection of the vibration of the structure. These elements can be an integral part of the structure, see Fig. 1, with an excitation element for .exerting a bending moment, and a detection element to detect bending strain. One technique makes use of resistive heating for thermal excitation and resistive strain gauges for detection. For our resonating membrane mass-flow sensor [ 191 as well as for our resonating microbridge mass-flow sensor [20], we make use of in situ phosphorus doping of low-pressure chemical vapour deposited (LPCVD) polysilicon for the excitation and the detection resistors, together with a single-crystal silicon substrate. We will first discuss the advantages of polysilicon for this application, and then we will give reasons for our choice of in situ doping with phosphorus.

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Section: Discumionsupporting

confidence: 75%

In situ phosphorus-doped polysilicon for excitation and detection in micromechanical resonators

Bouwstra

Weerd

Elwenspoek

1990

Sensors and Actuators A: Physical

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“…Although the grain boundary barriers are similar for nand p-type polycrystalline silicon layers, dopant segregation can lead to differences in electrical behavior. Mandurah et al 21 have shown that As and P segregate to grain boundaries whereas B does not. This can cause differences in conduction since segregated dopant is electrically inactive and hence cannot reduce the grain boundary energy barrier.…”

Section: Discussionmentioning

confidence: 99%

The role of carbon on the electrical properties of polycrystalline Si1−yCy and Si0.82−yGe0.18Cy films

Anteney

Parker

Ashburn

et al. 2001

Journal of Applied Physics

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A comparison is made of the electrical effects of carbon in n-and p-type in situ doped polycrystalline Si 1Ϫy C y and Si 0.82Ϫy Ge 0.18 C y layers. Values of resistivity as a function of temperature, effective carrier concentration and Hall mobility are reported. The n-type polycrystalline Si 1Ϫy C y and Si 0.82Ϫy Ge 0.18 C y films show dramatic increases in resistivity with carbon content, rising from 0.044 ⍀ cm to 450 ⍀ cm ͑0 and 0.8% C͒ and 0.01 ⍀ cm to 2.4 ⍀ cm ͑0 and 0.6% C͒, respectively. In contrast, the increase in B-doped films is much less severe, rising from 0.001 ⍀ cm to 0.939 ⍀ cm ͑0 and 7.9% C͒ and 0.003 ⍀ cm to 0.015 ⍀ cm ͑0 and 4% C͒ for the Si 1Ϫy C y and Si 0.82Ϫy Ge 0.18 C y layers, respectively. The grain boundary energy barrier, determined from the temperature dependence of the resistivity, is found to vary as the square of the C content in the n-type polycrystalline Si 1Ϫy C y and Si 0.82Ϫy Ge 0.18 C y layers, but linearly in the p-type Si 1Ϫy C y layers. The square law dependence seen in the n-type layers for C contents up to 0.9% is explained by an increase in the grain boundary trap density due to the presence of carbon, whereas the linear relationship seen in the p-type layers for C contents between 2% and 8% is explained by a shift in the grain boundary trap energy toward the valence band. Finally, lower values of grain boundary energy barrier are obtained in p-type Si 0.82Ϫy Ge 0.18 C y layers with a C content of 4% than in equivalent Si 1Ϫy C y layers, which could be explained by a larger shift in trap energy toward the valence band.

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“…This is due to the fact that at the highest hot-pressing temperature of 1050 • C the segregation of P at the surface of Si NCs becomes rather effective. 16 Segregated P may form precipitates, retarding the viscous flow of melt small Si NCs or surface oxide. Clearly, this effect is more serious as the concentration of P is higher.…”

Section: Methodsmentioning

confidence: 99%

Low-resistivity bulk silicon prepared by hot-pressing boron- and phosphorus-hyperdoped silicon nanocrystals

Luan

Koura

et al. 2014

AIP Advances

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Technologically important low-resistivity bulk Si has been usually produced by the traditional Czochralski growth method. We now explore a novel method to obtain low-resistivity bulk Si by hot-pressing B- and P-hyperdoped Si nanocrystals (NCs). In this work bulk Si with the resistivity as low as ∼ 0.8 (40) mΩ•cm has been produced by hot pressing P (B)-hyperdoped Si NCs. The dopant type is found to make a difference for the sintering of Si NCs during the hot pressing. Bulk Si hot-pressed from P-hyperdoped Si NCs is more compact than that hot-pressed from B-hyperdoped Si NCs when the hot-pressing temperature is the same. This leads to the fact that P is more effectively activated to produce free carriers than B in the hot-pressed bulk Si. Compared with the dopant concentration, the hot-pressing temperature more significantly affects the structural and electrical properties of hot-pressed bulk Si. With the increase of the hot-pressing temperature the density of hot-pressed bulk Si increases. The highest carrier concentration (lowest resistivity) of bulk Si hot-pressed from B- or P-hyperdoped Si NCs is obtained at the highest hot-pressing temperature of 1050 °C. The mobility of carriers in the hot-pressed bulk Si is low (≤ ∼ 30 cm-2V-1s-1) mainly due to the scattering of carriers induced by structural defects such as pores.

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Dopant segregation in polycrystalline silicon

Cited by 377 publications

References 24 publications

In situ phosphorus-doped polysilicon for excitation and detection in micromechanical resonators

In situ phosphorus-doped polysilicon for excitation and detection in micromechanical resonators

The role of carbon on the electrical properties of polycrystalline Si1−yCy and Si0.82−yGe0.18Cy films

Low-resistivity bulk silicon prepared by hot-pressing boron- and phosphorus-hyperdoped silicon nanocrystals

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