CHEMICAL VAPOR DEPOSITION OF THIN FILM MATERIALS FOR ...

dried by ultra high purity N2 gas. The as prepared hydrogen terminated Si(100) wafer was loaded
into the reaction chamber for thin film deposition or underwent further thermal oxidation in a
tube furnace (Lindberg) to form a SiO2 layer with thickness of 100 nm to 120 nm. In a typical
PEALD reaction, the bubbler filled with TDMAH was heated to 60˚C by an oil bath heater and
the TDMAH delivery line from the bubbler to the reaction chamber was heated to around 75˚C
to minimize precursor vapor condensation on the tubing walls. Hydrogen gas is introduced into
the reaction chamber by passing through a quartz tube where it is ionized into hydrogen plasma.
As shown in Fig.29, the quartz tube is wrapped by a copper solenoid, which is connected to the
RF power generator (coupled with matching network). In our case, 13.56 MHz RF power is used
to generate inductively coupled plasma (ICP) in the quartz tube. Since the generation of plasma
is out of the reaction zone, the effect of substrate surface bombardment by powerful ions can be
minimized. The introduction of TDMAH and hydrogen plasma was separated by flowing inert
gas (Ar) between them. A typical ALD cycle is composed of the following four sequential steps:
5s TDMAH vapor, 35s Ar purging, 25s hydrogen plasma, 5s Ar purging. The pulsing of the
reactants and inert gas and the pulsing of the plasma are synchronized in a self written LabVIEW
program (Fig.31). Through serial communication (RS232/RS485) with a PC, the RF power
generator and a programmable relay controlling all the pneumatically controlled valves can be
controlled simultaneously by this LabVIEW program. In this way, the plasma was turned on
exactly at the time range of hydrogen pulse through the quartz tube, as shown in Fig.32.
62