TABLE OF CONTENTS Carbides and silicides are known as high-temperature materials with strong mechanical strength similar to nitrides. For instance, silicon carbide (SiC) shows a high melting point of 2700 C with a Vickers hardness of 4000 kg/mm 2. The growth of single-crystal SiC films has been studied in relation to SiC thin-film devices including high-temperature SiC transistors and blue-laser diodes.[259] Diamond thin films are also of technological interest because of their potential applications in electronic devices capable of operating at high temperatures and under irradiation of cosmic rays.
Several processes have been studied for preparing thin films of high-temperature materials. In general, these thin films include high amounts of lattice defects and also show poor adherence to the substrate due to their hardness.
Various processes for making SiC films are available including vapor-phase reaction,[260] plasma reaction,[261] evaporation,[262] rf sputtering,[263] and ion plating.[264] Among these processes, one of the most convenient is rf sputtering from a SiC target.
The crystalline structure of rf-sputtered SiC films varies from the amorphous phase to the crystalline phase, depending mainly on the substrate temperature during deposition. Typical sputtering conditions are shown in Table 5.45.
| Target | SiC ceramics (80 mm in diameter) |
|---|---|
| Sputtering gas | Argon (purity 99.9999%, 5 Pa) |
| Substrates | Fused quartz, silicon, alumina |
| Substrates temp. | 200 500 C |
| Target RF power (13.56 MHz) | 1 3 W/cm 2 |
| Target-substrate distance | 30 mm |
| Deposition rate | 0.1 1 ?m/h |
| Film thickness | 4 5 ?m |
Figure 5.125...
