Single shot excimer laser crystallization of silicon films deposited by LPCVD

Kis-Sion, K.; Mohammed-Brahim, T.; Briand, D.; Sarret, M.; LeBihan, F.; Fortin, B.; Bonnaud, Olivier; Boher, Pierre; Stehle, M.; Stehle, Jean-Louis P.

doi:10.1016/s0040-6090(96)09382-0

“…Low-temperature polycrystalline silicon (LTPS) is a crucial active layer material for polycrystalline silicon thin-film transistors (poly-Si TFTs) on thermally susceptible glass substrates. LTPS-TFT backplanes are required for fabricating flat panel displays such as active-matrix liquid displays and active-matrix organic light-emitting displays (AMOLEDs) (1)(2)(3)(4)(5). LTPS-TFT backplanes are strongly preferred to amorphous silicon (a-Si)-TFT ones since several devices, AMOLEDs in particular, operate in a currentdriven mode (6).…”

Section: Introductionmentioning

confidence: 99%

Microsecond Crystallization of Amorphous Silicon Films on Glass Substrates by Joule Heating

Hong

¹

,

Ro

²

2016

ECS Trans.

0

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Joule-heating-induced crystallization (JIC) of amorphous silicon (a-Si) films was conducted by applying an electric pulse to a conductive layer located beneath or above the films. Crystallization occurs across the whole substrate surface within few tens of microseconds. The phase-transformation phenomena during the JIC process were detected electrically and optically by the in-situ measurements of input voltage/current and normal reflectance at wavelength of 532 nm. We devised a method for the crystallization of a-Si films while preventing arc generation; this method consisted of pre-patterning an a-Si active layer into islands and then depositing a gate oxide and gate electrode. Electric pulsing was then applied to the gate electrode formed using a Mo layer. JIC-processed poly-Si thin-film transistors were fabricated successfully, and the proposed method was found to be compatible with the standard processing of coplanar top-gate poly-Si TFTs.

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“…LTPS-TFT backplanes are required for fabricating flat panel displays such as active-matrix liquid displays and active-matrix organic light-emitting displays (AMOLEDs). [1][2][3][4][5] LTPS-TFT backplanes are strongly preferred to amorphous silicon (a-Si)-TFT ones since several devices, AMOLEDs in particular, operate in a current-driven mode. 6,7 Methods used for forming LTPS include solid-phase crystallization (SPC), 8,9 metal-induced crystallization, 10 and excimer laser crystallization.…”

mentioning

confidence: 99%

Microsecond Crystallization of Amorphous Silicon Films on Glass Substrates by Joule Heating

Hong¹,

Ro

²

2016

ECS J. Solid State Sci. Technol.

0

View full text Add to dashboard Cite

Joule-heating-induced crystallization (JIC) of amorphous silicon (a-Si) films was conducted by applying an electric pulse to a conductive layer located beneath or above the films. Crystallization occurs across the whole substrate surface within few tens of microseconds. The phase-transformation phenomena during the JIC process were detected electrically and optically by the in-situ measurements of input voltage/current and normal reflectance at wavelength of 532 nm. We devised a method for the crystallization of a-Si films while preventing arc generation; this method consisted of pre-patterning an a-Si active layer into islands and then depositing a gate oxide and gate electrode. Electric pulsing was then applied to the gate electrode formed using a Mo layer. JICprocessed poly-Si thin-film transistors were fabricated successfully, and the proposed method was found to be compatible with the standard processing of coplanar top-gate poly-Si TFTs. The p-channel JIC poly-Si TFT with W/L = 7 μm/7 μm exhibited a field effect mobility of 38.9 cm 2 /V-s, a threshold voltage of −2. Low-temperature polycrystalline silicon (LTPS) is a crucial active layer material for polycrystalline silicon thin-film transistors (poly-Si TFTs) on thermally susceptible glass substrates. LTPS-TFT backplanes are required for fabricating flat panel displays such as active-matrix liquid displays and active-matrix organic light-emitting displays (AMOLEDs).1-5 LTPS-TFT backplanes are strongly preferred to amorphous silicon (a-Si)-TFT ones since several devices, AMOLEDs in particular, operate in a current-driven mode.6,7 Methods used for forming LTPS include solid-phase crystallization (SPC), 8,9 metal-induced crystallization, 10 and excimer laser crystallization. 11Sameshima et al. were the first to report Joule heating crystallization carried out using Cr strips as heating sources in order to rapidly crystallize silicon films.12 They crystallized 50-nm-thick a-Si films via 200-nm-thick SiO 2 intermediate layers by applying an electric field to Cr strips with a power density of ∼10 5 W/cm 2 . Extending this concept further, we have developed a crystallization method for a-Si films called Joule-heating-induced crystallization (JIC). [13][14][15] In this method, an electric field is applied to a conductive layer above or beneath a-Si films to induce Joule heating that in turn leads to crystallization of the films. The film temperature in this method is more uniform than that achieved using other conventional heating methods since the Joule heat is generated uniformly throughout the conductive layer. The optimum processing windows for the JIC process strongly depend on the power density (W/cm 2 ) and pulsing time applied during the process. These process parameters determine the heating rate as well as the depth of thermal penetration from the Joule-heat source. During electrical pulsing the maximum temperature depends on power density and pulsing time. As the power density increases the heating rate increases. Thus in order to obtain a given crysta...

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