我在CERAC上下载的文章，上面还好多 关于镀膜方面的东东，大家可去看看！
好文章，the coating process: requirement to delivery
Introduction Tantalum pentoxide, Ta2O5, is a high-index, low-absorption material usable for coatings in the near-UV (350 nm) to IR (~8 µm) regions. Dense layers can be deposited by electron-beam evaporation or sputtering. Typical applications include near-UV to near-IR antireflection and multilayer filter designs. Tantala can be used in combination with silicon dioxide layers to form high index-contrast multilayer structures. A particular advantage over titanium dioxide layers for near-IR laser and bandpass coatings is the absence of absorption above 900 nm. This makes tantala well suited for Nd:YAG laser applications.
Film Properties Completely oxidized tantala films are absorption-free over the range below 400 nm to at least 8 µm. Evaporation causes some amount of dissociation and oxygen loss and requires a partial pressure of oxygen during deposition. Adhesion is excellent to glass and to most other oxides. The films generally grow with a crystalline microstructure. Under some evaporation conditions, such as low energy resistance-heated evaporation, low substrate temperature, or excessive background pressure, the films grow with low packing density and can exhibit index changes when vented to moist air. Deposition by sputtering, ion assist, or at very high substrate temperatures, improves the packing density and eliminates spectral shifting due to moist air-vacuum cycling, producing very stable layers.
The refractive index responds to high energy deposition techniques and to substrate temperature because both parameters decrease the void volume by increasing the packing density of the microstructure. Post-deposition baking in air can raise the refractive index of electron-beam and resistance-heated depositions.
Refractive Index The refractive indices are dependent on the degree of oxidation and the film density achieved. Approximate values are plotted below.
Material Behavior The starting material form is either tablets or sintered pieces. Recommended preconditioning consists of slowly sweeping a low power electron beam to slowly and uniformly fuse the surfaces of the material and avoid hole drilling by the beam. Monitor the pressure and crucible to minimize outgassing and spitting while slowly increasing the power to just below evaporation temperature.
Evaporation Parameters
| Evaporation temperature | ~2000° C |
| Source Container | Tantalum or graphite liner for E-beam |
| Rate | 2-5 Å/sec. |
| Partial pressure of oxygen | 2-5 x 10-5 Torr |
| Substrate temperature | 175° C to 300° C. |
Physical Properties of Solid Material
| Molecular Weight | 441.89 |
| Melting Point | 1872° C |
| Color | White |
| Crystal Density | 8.2 g/cc |
Applications Because the index below wavelengths 300 nm is greater than 2, tantala can be combined in multilayers with silicon dioxide (n = 1.48) for UV laser applications. Hard, scratch-resistant and adherent coatings can be deposited. Films are also used for dielectrics in film capacitors and as gate insulators in large scale integrated circuits requiring low leakage voltage characteristics.
Forms and Sizes Available
| Item No. | Purity | Description |
| T-1186 | 99.95% | 8-9 mm dia. x 4-5 mm thick sintered tablets |
| T-1202 | 99.95% | 3-12 mm sintered pieces |
| SS-620 | 99.997% | Sputtering Target |
| SS-112 | 99.99% | Sputtering Target |
| 欢迎光临 光电工程师社区 (http://bbs.oecr.com/) | Powered by Discuz! X3.2 |