Study of tungsten filament aging in hot-wire chemical vapor deposition with silacyclobutane as a source gas and the H2 etching effect

Abstract

The tungsten filament aging when using silacyclobutane (SCB) as a source gas in a hot-wire chemical vapor deposition reactor was systematically studied by the characterization of surface morphology using scanning electron microscopy and the chemical composition analysis of the filament surfaces using Auger electron spectroscopy. It is shown that filament aging involves the formation of silicides and under more severe conditions, a pure silicon deposit. At low pressures of SCB samples, e.g., 0.06 and 0.03Torr, only Si3W5 alloy was formed. Silicon-rich silicide, Si2W, was found when using a higher pressure of SCB at 0.12Torr. At the high SCB pressure of 0.12Torr and low temperatures, pure silicon was deposited on the W filament surface. It is also demonstrated that H2 can etch the aged filament at high temperatures above 1900°C. The etching products detected by the 10.5eV vacuum ultraviolet laser single photon ionization∕time-of-flight mass spectrometer include SiH4, SiCHx (x=2–5), and SiC2Hy (y=4–7).

Structural Changes in Tungsten and Tantalum Wires in Catalytic Chemical Vapor Deposition Using 1,3-Disilacyclobutane

“…34 However, no other peaks for WC were observed at this temperature. Although the formation of cubic 3C-SiC was not observed in our previous studies using SCB 8 Further LeBail refinement supported this observation and determined the cell parameters as a = 4.785(6) Å, b = 6.074(7) Å, c = 5.245(7) Å, and V = 152.4(6) Å 3 . The observation of crystalline W 2 C is similar to our recent study using TMDSCB 12,20 and other studies.…”

“…In the deposition of Si films using SiH 4 , the growth of a silicide layer on the W or Ta filament was commonly observed. 6,7,9 Recently, our laboratory has studied the structural changes in W wires when they are exposed to different four-membered-ring (di)silacyclobutane molecules, including 1-silacyclobutane (SCB) 8 and 1,1,3,3-tetramethyl-1,3-disilacyclobutane (TMDSCB). 12,20 These organosilicon compounds are potentially useful single-source precursor gases to replace the SiH 4 /hydrocarbon mixtures that are conventionally used for silicon carbide thin film deposition by Cat-CVD.…”

Unraveling the complex chemistry using dimethylsilane as a precursor gas in hot wire chemical vapor deposition

“…However, W filaments suffer from a short lifetime, especially at lower filament temperatures. [15][16][17][18] In contrast, a Ta filament lasts longer since it is less prone to form silicides on its surface. 19,20 Despite this advantage, little is known about the gas-phase chemistry when using these precursor molecules with Ta as a filament.…”

Catalytic decomposition of phosphorus compounds to produce phosphorus atoms

“…13) They explained these results by boron accommodation into the wire, based on secondary ion mass spectroscopic analysis. Similar processes of silicidation [14][15][16][17][18][19][20][21] and carburization [21][22][23][24] of W wires have been observed, although silicidation is less remarkable at high wire temperatures. In the present phosphorus systems, however, phosphorization does not occur at any temperature.…”