Enhanced nucleation in solid-phase crystallization of amorphous Si by imprint technology

Abstract

A method to enhance crystal nucleation at controlled sites in solid-phase crystallization of amorphous Si is demonstrated. The method uses imprint with Ni-coated Si tips prior to conventional furnace annealing of amorphous Si films deposited on SiO2 substrates. The incubation time for crystallization is found to be greatly reduced at sites imprinted with the tips. This enhanced nucleation can be used to form large crystal grains up to about 7 μm in diameter at controlled sites. Results obtained from imprint with SiO2-covered Si tips suggest that the enhanced nucleation results not from physical effects of indentation but from a chemical effect of metal transfered from the tip to the film surface.

Grain positioning using metal imprint technology for single‐grain Si thin‐film transistor

“…Therefore, we see the position control of the grains by Ni imprinting. Nucleation was faster when imprinting by a tip array covered with SiO 2 [10], but this was due to the local stress effect by surface indentation. A shortening of the incubation time as when using a metal was not observed.…”

“…We have proposed metal imprint technology as a position control technique when forming a single crystal grain [10,11]. This technique does not demand advanced lithographic techniques or complex processes in order to control the grain position.…”

Control of grain position in Ni-mediated crystallization of amorphous silicon

“…To realize this, we introduced the tip-pressing method onto the a-Si film to form GPs. Although preferential nucleation and grain growth at special sites was already reported in metalinduced crystallization (MIC) of a-Si using Ni [4,10], by the formation of Ni dots at the nucleation sites. We can control nucleation sites not by positioning Ni contact sites but by making GPs on the a-Si without Ni contact.…”

“…In order to produce device-grade poly-Si [1][2][3][4], solid phase crystallization (SPC) using metal catalysts, among the various crystallization methods, has generated considerable interest continuously because of its merits such as low cost and simple process.…”

“…There have been many efforts to control nucleation sites artificially, such as step-induced crystallization [8], SEN-TAXY (by ion implantation [9], selective patterning of metal contact [4], and metal imprint technology [10].…”