A Low Temperature Poly‐Si TFT with a SMC Poly‐Si Crystallized at 420 °C

Choi, Young Jin; Kwak, Won Kyu; Park, S. J.; Yoon, Sung-Min; Kim, C. O.; Jang, Jin

doi:10.1889/1.1834069

Cited by 4 publications

(2 citation statements)

References 12 publications

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“…Note that the mobility of the needlelike crystallites is much lower than that of disk-shaped grains. 12,13 In this work, the poly-Si having no needlelike grains has a higher mobility. Figure 5 shows the transfer ͑a͒ and output ͑b͒ characteristics of a MICC poly-Si TFT made on the SOG layer with O 2 -plasma treatment time of 90 s. The ratio of channel width to length of the TFT was 8:8 m. Table I summarizes the device performances of the LTPS TFTs on the SOG buffer layer.…”

Section: J156mentioning

confidence: 74%

Effect of Oxygen-Plasma Treatment on Formation of LTPS on SOG by Metal-Mediated Crystallization

Cheon

Bae

Jang

2007

Electrochem. Solid-State Lett.

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We have studied the oxygen-plasma effect on spin-on-glass ͑SOG͒ on the growth of low-temperature polycrystalline silicon ͑LTPS͒ by metal-mediated crystallization. The SOG buffer was coated on glass, and then it was exposed to oxygen plasma before the deposition of amorphous silicon ͑a-Si͒ to turn the SOG surface to hydrophilic. The a-Si on SOG was crystallized by metal-induced crystallization through a cap. The crystalline structure depended on the surface treatment: disk-shaped grains were grown on the O 2 -plasma-treated SOG, but needlelike grains were on the SOG without O 2 -plasma treatment. The p-channel poly-Si thin film transistor using the LTPS on O 2 -plasma-treated surface exhibited a field-effect mobility of 91.1 cm 2 /V s, a threshold voltage of −8.5 V, and a gate voltage swing of 1.2 V/dec. Low-temperature polycrystalline silicon ͑LTPS͒ on glass is of increasing interest for large-area electronics including active-matrix liquid-crystal displays ͑AMLCDs͒, 1 active-matrix organic light emitting diodes ͑AMOLEDs͒, 2 and system-on-glass 3 due to its high field-effect mobility compared to amorphous silicon ͑a-Si͒. Common methods for crystallization of a-Si are solid-phase crystallization ͑SPC͒, 4 excimer laser annealing ͑ELA͒, 5 and metal-induced crystallization ͑MIC͒. 6 Spin-on-glass ͑SOG͒ is an interlevel-dielectric material that is supplied in liquid form. It therefore exhibited planarization and gapfill capabilities. The SOG layer shows a smooth surface, good uniformity, low defect density, and low cost per die. There is no need for hazardous gases as required in chemical vapor deposition ͑CVD͒, and it can be used as the sacrificial planarizing layer. Note that its dielectric constant is 3.1, which is lower than that of plasmaenhanced CVD ͑PECVD͒ SiO 2 .To realize complementary metal-oxide-semiconductor ͑CMOS͒ circuits, Wagner et al. crystallized a-Si on a SOG/metal foil and made n-and p-channel poly-Si thin-film transistors ͑TFTs͒ with the field-effect mobility of 64 and 22 cm 2 /V s, respectively. 7 Shimoda et al. fabricated a coplanar poly-Si TFT exhibiting a field-effect mobility of 12.6 cm 2 /V s by using polysilazane SOG. 8 In this work, we have studied the oxygen plasma effect on SOG before the deposition of a-Si for crystallization. The crystallization depends on the O 2 plasma and disk-shaped grain growth can be achieved. The p-channel poly-Si TFT on SOG buffer layer with O 2 plasma treatment time of 90 s exhibited a field-effect mobility of 91.1 cm 2 /V s, a threshold voltage of −8.5 V, and a gate voltage swing of 1.2 V/dec.The SOG film was spun at a speed of 4000 rpm for 30 s and then cured at 80°C for 2 min, 130°C for 2 min, and 450°C for 1 h sequentially, resulting in a thickness of 220 nm. Then, it was treated by O 2 plasma from 0 to 90 s. The O 2 -plasma conditions were a gas pressure of 50 mTorr, a gas flow of 160 sccm, and a power of 50 W. Figure 1 shows the schematic diagram for the formation of LTPS on glass by MIC through a cap layer ͑MICC͒: ͑a͒ spin coating of SOG, ͑b͒ O 2 plasma...

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Section: J156mentioning

confidence: 74%

Effect of Oxygen-Plasma Treatment on Formation of LTPS on SOG by Metal-Mediated Crystallization

Cheon

Bae

Jang

2007

Electrochem. Solid-State Lett.

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“…The SMC of a-Si in an electric field, a technique compatible with batch process, was developed for the low temperature poly-Si TFTs [10]. The lateral grain size of the SMC poly-Si increase with decreasing the metal thickness.…”

Section: (A) (B)mentioning

confidence: 99%

36.3: High Quality Poly‐Si Crystallized at 400 °C by Field Enhanced SMC

Yoon

Cho

Park

et al. 2000

Symp Digest of Tech Papers

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A-Si layer was crystallized at a temperature of 400 o C in the presence of a modest electric field of 100 V/cm. An accumulation of needlelike crystallites in the crystallized poly-Si has been found after crystallization. This results from the migration of NiSi 2 precipitates through a-Si. The field effect mobility and threshold voltage for a SMC poly-Si TFT using a maximum process temperature of 400 o C were 76 cm 2 /Vs and 0.8 V, respectively. The performance of a SMC poly-Si TFT is comparable to that of an ELA poly-Si TFT.

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