From Cyclopentasilane to Thin‐Film Transistors

Abstract

Cyclopentasilane (CPS) has been studied as an liquid precursor for the deposition of thin silicon films for printed electronics and related applications. The processing involves a UV‐induced prepolymerization of CPS followed by liquid deposition and low‐temperature thermolysis. An insight into the oligomer and polymer formation including crosslinking in solution using 29Si NMR spectroscopy and electron spin resonance spectroscopy is reported. Formation of SiH (T‐units) and SiH3 (M‐units) is observed as well as short‐lived paramagnetic species. Additionally, the polymerization is followed by Raman spectroscopy. Reactive molecular dynamics simulations are applied to develop a theoretical model for the CPS‐ring‐opening and crosslinking steps. The experimental and computational data correspond well to each other and allow insight into the mechanism of polymer formation. The processing steps include spin‐coating, thermal drying, and conversion to amorphous silicon, H‐passivation, and fabrication of a CPS‐derived thin‐film transistor (TFT), without intermediate silicon crystallization. Further improvement is gained by using tetralene as a solvent, leading to a reduction of the time‐consuming polymerization step by one order of magnitude compared to cyclooctane. The overall quality and characteristics of the CPS‐derived spin‐coated silicon thin films correspond to standard plasma enhanced chemical vapor deposition‐derived devices with respect to performance levels.

Syntheses and Molecular Structures of Liquid Pyrophoric Hydridosilanes

“…Cyclopentasilane (10) shows a very similar behaviour compared to 9 during irradiation. [16] The compounds 6, 7, and 8 were filled in quartz capillaries and treated with UV-light at 365 nm. The liquids remained unchanged.…”

“…We recently reported a detailed study about the polymerization of CPS by irradiation. [16] Here we investigated the irradiation of 9.…”

“…However, the chemistry of hydridosilanes has received a considerable revival in recent years due to their potential use as precursors for liquid phase deposition of silicon films. [4][5][6][7][8][9][10][11][12][13][14][15][16] This approach promises significant reduction of processing costs in the manufacture of semiconductor devices. [4,17,18,19] Printing techniques have been applied to produce silicon thin-film transistors (TFT).…”

“…[4,17,18,19] Printing techniques have been applied to produce silicon thin-film transistors (TFT). [4,16,20] The production of other devices like light-emitting diodes, [17,19] large area flexible solar cells, [21] or ultrafine silicon patterns (10 nm or less) [22] have been forebode on the basis of this new technology.…”

Linear Phenylsilanes with PSi4P, PSi5P, and Si7 Backbones

“…Liquid hydridosilanes (e. g. cyclopentasilane Si 5 H 10 ) are considered as promising precursors for the deposition of silicon layers. [1][2][3][4][5][6][7][8][9][10][11][12] Doping is necessary for the production of components for microelectronics. [13] This can be achieved by introducing boron or phosphorus compounds.…”