Crystallization of Si in Millisecond Time Domain Induced by Thermal Plasma Jet Irradiation

Abstract

Investigations on the temperature profiles and formation of crystalline Si in rapid thermal annealing induced by thermal plasma jet (TPJ) irradiation have been reviewed. Substrate surface temperature during annealing has been measured by an optical probe method which has an accuracy of 30 K and a time resolution of millisecond. By changing the annealing conditions such as scan speed (v), plasma-substrate gap (d) and Ar gas flow rate (f), maximum surface temperature (T max) is controlled in the ranges of 960 to 1860 K with a typical annealing duration (t a) of $3 ms. On the basis of temperature measurement and in-situ reflectivity measurement techniques, the phase transformation of amorphous Si (a-Si) films has been investigated. When the a-Si films are heated to a temperature higher than the melting point, solid phase crystallization (SPC) followed by melting and resolidification of the films have been observed. It was found that SPC temperature increased from 1096 to 1284 K with decreasing crystallization time from 1.4 to 0.12 ms. Thin-film transistors (TFTs) fabricated using the SPC films show good electrical characteristics with an average field effect mobility of 61 cm 2 ÁV À1 Ás À1 and a threshold voltage of 3.4 V. By annealing SiO x films at temperatures higher than 1430 K using a TPJ, the precipitation of nanocrystalline Si with a size ranging from 10 to 250 nm has been observed.

Nanomaterials synthesis at atmospheric pressure using nanosecond discharges

“…Indeed, nanosecond DBDs have already been used to improve the hydrophilic properties of polymer thin films at relatively high efficiency (Walsh et al 2007;Zhang et al 2010). Also, the crystallization of amorphous Si thin films using plasma-induced thermal annealing at the millisecond time scale has been developed as a practical alternative to laser thermal annealing, albeit at much slower rates of heat transfer (Higashi et al 2006). However, as mentioned previously, NRP spark discharges are capable of heating and cooling on much shorter time scales that may be competitive with some laser annealing techniques.…”

High Speed Lateral Crystallization of Amorphous Silicon Films on Glass Substrates by Micro-Thermal-Plasma-Jet Irradiation and Its Application to Thin Film Transistor Fabrication

“…N-type top gate TFTs were fabricated on glass using -TPJ crystallized Si films by the following process steps. 4) Phosphorus doped a-Si film with a thickness of 20 nm was deposited on a 500-nm-thick buffer SiO 2 layer by PECVD and then patterned into islands to form source and drain regions by chemical dry etching (CDE). Intrinsic Non-doped a-Si film with a thickness of 20 nm was deposited on source and drain islands by PECVD at 250℃.…”

Pulse Thermal Processing for Low Thermal Budget Integration of IGZO Thin Film Transistors

“…Additionally, PTP allows roll-to-roll processing of materials with cost effective and large scale. Although micro plasma jet has been explored for crystallization and improvement of a-Si TFTs [18], [19] as an alternative short time thermal processing, the small treatment size of few mm is a major limitation for the high throughput and large area roll-to-roll manufacturing as similar as ELA process.…”