A low-temperature chemical vapor deposition (CVD) apparatus and a method of synthesizing carbon nanotubes using the CVD apparatus. The thermal CVD apparatus includes: a reaction tube having a gas inlet portion and an exhaust portion, the reaction tube divided into a first region, which is spatially adjacent to the gas inlet portion, for thermally decomposing a gas entering through the gas inlet portion, and a second region, which is spatially adjacent to the exhaust portion, for synthesizing carbon nanotubes using the gas decomposed in the first region; a first resistance heater installed around the reaction tube, for maintaining the temperature of the first region at a first temperature; a second resistance heater installed around the reaction tube, for maintaining the temperature of the second region at a second temperature lower than the first temperature; and an insulator interposed between the first and second resistance heater for insulating the same. The carbon nanotube synthesis method includes forming a first metal catalyst film over a first substrate. The first metal catalyst film is etched with an etching gas to form a number of nano-sized catalytic particles, and a carbon source gas is thermally decomposed using a thermal chemical vapor deposition (CVD) apparatus having a reaction tube divided into first and second regions, maintained at different temperatures, wherein the carbon source gas is decomposed in the first region, which is a relatively high temperature region, of the reaction tube. Then, carbon nanotubes are synthesized over the catalytic particles using decomposed carbon source gas, in the second region whose temperature is lower than the first region.
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