Improved Electrical Performance and Uniformity of MILC Poly-Si TFTs Manufactured Using Drive-In Nickel-Induced Lateral Crystallization

Chang, Chih-Pang; Wu, Yu‐Chung

doi:10.1109/led.2009.2031130

Cited by 12 publications

(3 citation statements)

References 15 publications

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“…4a), a Raman peak at 480 cm −1 can be clearly identified for the location 25 μm from the Ni bar edge. This peak indicates the presence of amorphous silicon, 21 which is as expected as this location is beyond the crystallization front. In contrast, the Raman spectrum for the location 10 μm from the Ni bar edge shows little evidence of a 480 cm −1 peak.…”

Section: Fabrication Processsupporting

confidence: 65%

Effect of Fluorine on the Lateral Crystallization of Amorphous Silicon Nanowires

Hakim

Gunn

Ashburn

2012

ECS J. Solid State Sci. Technol.

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In this work, we investigate the effect of fluorine on the metal-induced lateral crystallization (MILC) of amorphous silicon nanowires. The MILC is characterized at temperatures in the range 550 to 450 • C using Nomarski optical microscopy and Raman spectroscopy. It is shown that fluorine significantly increases the crystallization length at temperatures of 550 and 525 • C and dramatically improves the uniformity of the crystallization length at temperatures between 550 and 500 • C. A fluorine implant improves the standard deviation of the crystallization length from 39.7% to 5.8% at a temperature of 550 • C, from 35.6% to 5.2% at 525 • C and from 30.6% to 15.9% at 500 • C. This improvement in the uniformity of the crystallization is explained by the suppression of random grain nucleation by the fluorine. A comparison is also made between MILC in α-Si nanowires and larger α-Si ribbons and sheets. The crystallization length is significantly longer in ribbons and sheets, but fluorine is again shown to give a significant improvement in the uniformity of the crystallization.Polycrystalline silicon (poly-Si) has been widely researched for application in flat-panel active-matrix liquid crystal displays, 1 activematrix organic light-emitting diode (AMOLED) displays, 2,3 thin film solar cells, 4 three-dimensional (3D) electronics, 5,6 and nanowire biosensors. 7-9 For low-cost applications such as displays, the use of low cost glass substrates requires polysilicon films to be produced at temperatures significantly lower than the typical deposition temperature of 625 • C. 10 Several techniques have been investigated including solid-phase crystallization (SPC), 11 excimer laser crystallization (ELC) 12-14 and metal-induced lateral crystallization (MILC). 15 MILC is particularly attractive for low cost applications and the typical anneal temperature for MILC is 500 • C to 550 • C. 16,17 Fluorine implantation into amorphous silicon has been shown to significantly increase the lateral crystallization length during MILC 18 and hence enables polysilicon films to be produced at lower temperatures. This behavior was explained by the action of fluorine in suppressing random crystallization in the amorphous silicon film. This mechanism also gave reduced metal contamination in the crystallized film. 18 Other benefits of fluorine have been reported in thin film devices, such as the passivation of grain boundary traps 19 and the improvement of the uniformity of device electrical characteristics. To date, no work has been reported on the effect of fluorine in Si nanowires.Our recent work 20 has demonstrated that poly-Si nanowires can be fabricated by top-down lithography, reactive ion etch and metalinduced lateral crystallization at temperatures down to 450 • C. This approach has the advantage over bottom-up self-assembly of producing nanowires in defined locations on a wafer with excellent control over the nanowire width. In this work, we investigate the effect of fluorine on the metal-induced lateral crystallization of amorphous silic...

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Section: Fabrication Processsupporting

confidence: 65%

Effect of Fluorine on the Lateral Crystallization of Amorphous Silicon Nanowires

Hakim

Gunn

Ashburn

2012

ECS J. Solid State Sci. Technol.

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“…For the unannealed sample, a Raman peak at 480 cm −1 can be clearly identified, indicating that the film is largely amorphous. 10 After an anneal at 550…”

Section: Fig 2 Shows Opticalmentioning

confidence: 99%

“…4 In most published work, the Ni is defined either by a lift-off process [5][6][7][8][9] or by Ni deposition in a window opened in a cap layer, which is normally deposited silicon dioxide. [10][11][12][13][14][15] So far, no work has been reported that compares the effect of these two different Ni definition techniques on the lateral crystallization.…”

mentioning

confidence: 99%

Effect of an Oxide Cap Layer and Fluorine Implantation on the Metal-Induced Lateral Crystallization of Amorphous Silicon

Hakim

Gunn

Ashburn

2012

ECS J. Solid State Sci. Technol.

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In this work, we investigate the effect of oxide cap layer on the metal-induced lateral crystallization (MILC) of amorphous silicon. The MILC is characterized at temperatures in the range 550 to 428 • C using Nomarski optical microscopy and Raman spectroscopy. It is shown that better lateral crystallization is obtained when the oxide cap layer is omitted, with the crystallization length increasing by 33% for a 15 hour anneal at 550 • C. A smaller increase of about 10% is seen at lower temperatures between 525 • C and 475 • C and no increase is seen below 450 • C. It is also shown that the detrimental effect of the oxide cap layer can be dramatically reduced by giving samples a fluorine implant prior to the MILC anneal. Raman spectroscopy shows that random grain growth is significantly less for unimplanted samples without an oxide cap and also for fluorine implanted samples both with and without an oxide cap. The crystallization length improvement for samples without an oxide cap layer is explained by the elimination of random grain crystallization at the interface between the amorphous silicon and the oxide cap layer. Metal-induced lateral crystallization (MILC) has been widely researched as an alternative to solid-phase crystallization (SPC) of amorphous silicon because of its lower process temperature and higher quality polysilicon (poly-Si) film with higher carrier mobility, larger grain size, and lower defect density.1 For MILC, nickel reacts with amorphous silicon (α-Si) to form nickel disilicide and the lateral transport of Ni induces crystallization of the adjacent amorphous silicon, 2,3 creating a crystallized region with low Ni contamination suitable for high performance transistors. 4 In most published work, the Ni is defined either by a lift-off process [5][6][7][8][9] or by Ni deposition in a window opened in a cap layer, which is normally deposited silicon dioxide. 10-15So far, no work has been reported that compares the effect of these two different Ni definition techniques on the lateral crystallization.In this paper, we study the effect of an oxide cap layer on the nickel-induced lateral crystallization of amorphous silicon, and show that an amorphous silicon film without oxide capping gives better lateral crystallization at temperatures between 475• C to 550• C. It is also shown that the detrimental effects of an oxide cap layer can be eliminated using a fluorine implant. Experimental ProcedureThe sample structures are shown schematically in Figs. 1a and 1b for Ni patterning by lift-off and oxide window definition, respectively. A 500 nm thermal silicon dioxide layer was grown on <100> n-type Si wafers, and a 110 nm amorphous silicon (α-Si) layer was then deposited using low pressure chemical vapor deposition (LPCVD) at 560• C. After deposition, some wafers were then implanted with fluorine at a dose of 2.5 × 10 15 cm −2 and an energy of 35 keV. After a short HF dip to remove any native oxide on the α-Si surface, a 20 nm Ni layer was deposited on a F implanted wafer and an unimplanted wafer and ...

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21.4L: Late‐News Paper: Recent Developments of Carbon Nanotube Enabled Vertical Organic Light Emitting Transistors for OLED Displays

Liu

McCarthy

Iheanacho

et al. 2013

Symp Digest of Tech Papers

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A new architecture light emitting transistor combining the drive transistor, storage capacitor and light emitter into a single device promises to greatly reduce AMOLED manufacturing costs by dramatically reducing the backplane circuit complexity. Here we demonstrate device operation at 60 Hz using only a switching transistor and show remarkable stability under bias stress, despite use of an organic channel.

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Improved Electrical Performance and Uniformity of MILC Poly-Si TFTs Manufactured Using Drive-In Nickel-Induced Lateral Crystallization

Cited by 12 publications

References 15 publications

Effect of Fluorine on the Lateral Crystallization of Amorphous Silicon Nanowires

Effect of Fluorine on the Lateral Crystallization of Amorphous Silicon Nanowires

Effect of an Oxide Cap Layer and Fluorine Implantation on the Metal-Induced Lateral Crystallization of Amorphous Silicon

21.4L: Late‐News Paper: Recent Developments of Carbon Nanotube Enabled Vertical Organic Light Emitting Transistors for OLED Displays

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