High-performance thin-film transistors in large grain size polysilicon deposited by thermal decomposition of disilane

Kouvatsos, Dimitrios N.; Voutsas, Apostolos T.; Hatalis, Miltiadis K.

doi:10.1109/16.535325

Cited by 43 publications

(14 citation statements)

References 12 publications

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“…One way of achieving this is through the replacement of silane with disilane, allowing for more optimized low-temperature, high-deposition rate (and therefore more amorphous) films. This will result in a lower density of defects through a reduction in the nucleation rate and also in an increased average grain size [14]. The increase in average grain size will result in improved uniformity for smaller devices.…”

Section: Discussionmentioning

confidence: 99%

High-performance germanium-seeded laterally crystallized TFTs for vertical device integration

Subramanian

Saraswat

1998

IEEE Trans. Electron Devices

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Abstract-Increasing chip complexity and area has resulted in interconnect delay becoming a significant fraction of overall chip delay. Continued scaling of design rules will further aggravate this problem. Vertical integration of devices will enable a substantial reduction in chip size and thus in interconnect delay. We present a novel technique to achieve vertical integration of CMOS devices. Germanium is used as a seeding agent at the source and/or drain of thin film transistors (TFT's) to laterally crystallize amorphous silicon films, resulting in high-performance devices. This is achieved through the formation of large grain polysilicon with a precise control over the location of the grain. TFT's have been demonstrated offering substantial performance improvement over conventional unseeded polycrystalline TFT's, with demonstrated mobilities as high as 300 cm 2 /V-s. The process is fully CMOS compatible and has a low thermal budget. It is highly scalable to deep-submicron technologies and, with suitable optimization, should enable the production of high-performance, high density, vertically integrated ULSI.

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Section: Discussionmentioning

confidence: 99%

High-performance germanium-seeded laterally crystallized TFTs for vertical device integration

Subramanian

Saraswat

1998

IEEE Trans. Electron Devices

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“…The Si films used in this experiment were deposited by LPCVD using a silane (SiH 4 ) chemistry. A further performance improvement can be achieved by using disilane (Si 2 H 6 ), which will increase the incubation time, increasing the extent of lateral crystallization and reducing the number of defects within the crystallized film (2).…”

Section: E-12mentioning

confidence: 99%

A Novel Technique For 3-d Integration: Ge-seeded Laterally Crystallized TFTs

Subramanian

Saraswat²

1997

Symposium on VLSI Technology

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With increasing chip size and complexity, interconnect delays are becoming limiting factors in increasing performance. 3-D device integration will result in a reduction in chip size and interconnect delay. We present a novel technique for achieving high-performance MOS devices for vertical integration.Poly-Ge is used as a seeding agent to laterally crystallize amorphous Si films into the channel of poly-TFTs, resulting in a substantial performance improvement through a simple, CMOS-compatible process. The technology is scaleable, and should enable near-single crystal performance in deep sub-micron devices.

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“…As an example, the transition from an amorphous to a polycrystalline semiconducting film upon annealing is essential for processing electronic materials, such as thin film transistors [1,2] and solar energy converters [3]. Other examples are the formation of polycrystalline bulk Si material solidified via supercooling of a Si melt [4] or the deposition of polycrystalline Si films from the vapor phase [5].…”

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confidence: 99%

Noncoarsening Origin of Logarithmic-Normal Size Distributions during Crystallization of Amorphous Thin Films

Bergmann¹,

Shi²,

Krinke³

1998

Phys. Rev. Lett.

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It is demonstrated that the formation of logarithmic-normal crystallite size distributions during crystallization of amorphous thin films can be a consequence of the dynamics of random nucleation and growth without the involvement of coarsening. Our analytical result is supported by experimentally observed crystallite size distributions during the crystallization of amorphous Si thin films obtained from transmission electron microscopy. [S0031-9007(97)05141-7] The phase transformation from the amorphous and liquid to the crystalline state, leading to the formation of polycrystalline materials, is of fundamental scientific and technological importance. As an example, the transition from an amorphous to a polycrystalline semiconducting film upon annealing is essential for processing electronic materials, such as thin film transistors [1,2] and solar energy converters [3]. Other examples are the formation of polycrystalline bulk Si material solidified via supercooling of a Si melt [4] or the deposition of polycrystalline Si films from the vapor phase [5]. All of these processes establish nonmonotonic crystallite size distributions that can be well approximated by a logarithmic-normal (log-normal) distribution [4]. The size distribution within a polycrystalline semiconductor material can have a significant impact on device performance. This is especially true for minority carrier devices with highly recombination-active grain boundaries [6].A fundamental understanding of the transition from an amorphous phase to the crystalline state is still far from complete. Previous studies concerned themselves merely with the understanding of the earliest stages of nucleation and growth. In this case, the amorphous phase can be treated to be infinite; size distributions thus monotonically decrease with grain size [7]. The depletion of the amorphous phase, however, significantly influences the dynamics of nucleation and growth and determines the subsequent development of the size distribution.In this Letter, we describe the time evolution of the cluster size distribution beyond the early stages of nucleation and growth. We demonstrate that the interplay between the dynamics of nucleation and growth results in a transition from monotonic size distributions in the early stages to nonmonotonic size distributions as a function of the grain radius r in the later stages similar to the log-normal distribution L͑ln r͒~exp͓2͑ln r 2 m͒ 2 ͞2s 2 ͔, where m and s represent the median and width of the distribution, respectively [8]. Our results thus reveal an alternative origin for the development of lognormal size distributions. This recognition is essential, since the formation of log-normal size distributions have generally been attributed to the coarsening process [9,10]. The physical concept described here has recently been proposed by the authors on an intuitive basis [11], and is here analytically established for the first time.The dynamic evolution of the crystallite size distribution in the early stages of random nucleation and gro...

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High-performance thin-film transistors in large grain size polysilicon deposited by thermal decomposition of disilane

Cited by 43 publications

References 12 publications

High-performance germanium-seeded laterally crystallized TFTs for vertical device integration

High-performance germanium-seeded laterally crystallized TFTs for vertical device integration

A Novel Technique For 3-d Integration: Ge-seeded Laterally Crystallized TFTs

Noncoarsening Origin of Logarithmic-Normal Size Distributions during Crystallization of Amorphous Thin Films

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