A method to evaluate explosive crystallization velocity of amorphous silicon films during flash lamp annealing

Abstract

Flash lamp annealing (FLA) of micrometre-order thick amorphous silicon (a-Si) films can induce explosive crystallization (EC), high-speed lateral crystallization driven by the release of latent heat. We develop multipulse FLA system, which emits a quasi-millisecond pulse consisting of a number of subpulses. The emission frequency of the subpulses can be systematically controlled, and the emission of subpulses leads to the periodic modulation of the temperature of a Si film and the resulting formation of macroscopic stripe patterns. The relationship between a subpulse emission frequency and the width of the macroscopic stripe patterns yields EC velocity. Two kinds of EC modes can be observed, depending on the methods of precursor a-Si deposition and (or) a-Si film thickness.Résumé : Le recuit par lampe à décharge (FLA) de films de silicium amorphe (a-Si) peut causer une cristallisation spontanée (explosive) (EC) ou une cristallisation latérale induite, soutenue par le rejet de chaleur latente. Nous développons un système de recuit par lampe à décharge multi-pulse qui émet des impulsions presque milliseconde consistant en un nombre de sousimpulsions. La fréquence d'émission de ces sous-impulsions peut être contrôlée et l'émission de ces sous-impulsions mène à une modulation de la température du film de Si, d'où il résulte la formation d'un patron en bandes macroscopiques. La relation entre la fréquence d'émission des sous-impulsions et la largeur de ces bandes donne la vitesse de EC. Nous observons deux types de modes EC, dépendant de la méthode de déposition du précurseur Si et (ou) de l'épaisseur du film de a-Si. [Traduit par la Rédaction]

Crystallization of catalytic CVD hydrogenated n-a-Si films on textured glass substrates by flash lamp annealing

“…The formation of the macroscopic stripe patterns is related to the modulation of the temperature of Si films during millisecond treatment due to discrete sub-pulses. 18,19) These clear examples of experimental evidence indicate that the crystallization of Cat-CVD a-Si:H films by FLA on SiN x -coated textured glass substrates takes place by EC, lateral crystallization induced by the release of latent heat due to the enthalpy difference between a-Si and c-Si and its diffusion. 28) Figure 4 shows the widths of stripes formed on i-and npoly-Si films as a function of the inverse of the frequency of sub-pulse emission.…”

“…The sub-pulse emission leads to the periodic change of Si temperature during FLA and the resulting formation of macroscopic stripe patterns on a poly-Si surface if EC takes place. 18,19) The velocity of EC (v EC ) was estimated from the width of the macroscopic stripe patterns and inverse of sub-pulse frequency. 18,19) The crystallization and crystalline fraction of Si films were characterized by Raman spectroscopy.…”

“…18,19) The velocity of EC (v EC ) was estimated from the width of the macroscopic stripe patterns and inverse of sub-pulse frequency. 18,19) The crystallization and crystalline fraction of Si films were characterized by Raman spectroscopy. The cross-sectional microscopic image of a poly-Si was observed by transmission electron microscopy (TEM).…”

“…14) We have attempted to use precursor a-Si films formed by various types of deposition methods, such as catalytic chemical vapor deposition (Cat-CVD), sputtering, and electron-beam (EB) evaporation. [15][16][17][18][19][20][21][22][23][24] The crystallization of EBevaporated a-Si films on flat glass substrates is driven by liquid-phase explosive crystallization (EC), which leads to the formation of crystal grains with a size of several tens of μm. 17) A different type of EC occurs for the crystallization of Cat-CVD a-Si:H films, through which two types of regions with different microstructures appear alternately in the direction of crystallization with a period of ∼1 μm.…”

Flash Lamp Annealing Method for Improving Adhesion Strength on the Dielectric Material and Reducing Substrate Warpage

“…The equipment used for surface modification was UV irradiation equipment fitted with low pressure Hg lamp source. The low pressure Hg lamp has wavelengths of 184.9 nm (11.5 mW/cm ) and frequency of 3 Hz by the devising of a particular circuit design of the system [5,9]. ) [2,3].…”