Biomedical Engineering Reference
In-Depth Information
[170]. When a rutile titanium oxide layer is formed on the surface of a matrix, the blood compat-
ibility can be improved signifi cantly [166,170]. Several techniques to prepare titanium dioxide fi lms
have been reported, such as thermal oxidation [170], anodic oxidation [171], magnetron sputtering
[172-175], cathodic vacuum arc deposition [176-178], and ion beam enhanced deposition (IBED)
[166]. Titanium oxide fi lms used in artifi cial heart valves have also been synthesized using PIIID
technology in City University of Hong Kong and Southwest Jiaotong University, Chengdu, China
[35,133,179].
The PIII system used in this work is schematically shown in Figure 19.46. A Ti cathode
14 mm in diameter was mounted on the metal vacuum arc plasma source. An oxygen plasma was
sustained by RF in the vacuum chamber and at the same time, a titanium plasma was generated
in the metal arc source and diffused into the vacuum chamber via a magnetic duct to eliminate
deleterious macroparticles. The voltage on the sample was
50 V DC and the deposition time
was 60 min. The deposition rate varied from 0.1 to 0.15 nm/s depending on the oxygen gas fl ow
rate. To increase the adhesion between the fi lm and silicon (100) substrate, a
-
3 kV pulse voltage
(10 kHz, 5 μs) was applied to the sample during the fi rst 10 min. Table 19.8 lists the instrumental
-
RF plasma chamber
O inlet
Ar inlet
Titanium source
Cathodic arc source
RF antenna
Ti
+
Sample stage
Substrate
Negative pulsed bias
To vacuum pump
FIGURE 19.46
Schematic diagram of the PIII system applied to prepare the Ti-O thin fi lm.
TABLE 19.8
Instrumental Parameters for Samples #1 to #5
Samples
#1
#2
#3
#4
#5
Vacuum arc
Metal plasma
Source
Pulse repetition rate (Hz)
65
Pulse width (ms)
1
Arc current (A)
180
Oxygen gas fl ow (sccm)
3.1
5
7
10
15
Oxygen partial pressure (
×
10
-2
Pa)
0.63
0.93
1.2
1.7
2.7
RF power (W)
600
