In plasma etching, process gases are used which can convert the material to be etched into the gas phase. Gas enriched with the base material is pumped out and fresh process gas is supplied. Continuous removal is therefore achieved. Resistant masking (e.g. with chromium) can be used to protect areas against the process gas. A surface can be structured by targeting in this way. This structuring is on the nanometer scale.
| Application | Group | Material | Type of gas | Pressure [mbar] | Performance [%] | Time [min] |
|---|---|---|---|---|---|---|
| Etching | Metal | Aluminium | CCl4 | 0.2 - 0.5 | 100 | 30 - 120 |
| Aluminium | BCl3 | 0.2 - 0.5 | 100 | 30 - 120 | ||
| Titanium | NF3 | 0.1 - 0.4 | 100 | 30 - 120 | ||
| Plastic | POM | O2 / O2+CF4 | 0.1 - 0.4 | 100 | 30 - 120 | |
| PPS | (O2) | 0.1 - 0.4 | 100 | 30 - 120 | ||
| PTFE | H2 | 0.2 - 0.5 | 100 | 20 - 120 | ||
| Other | Al2O3 | Cl2+Ar | 0.1 - 0.6 | 100 | 30 - 120 | |
| SiO2 | CF4 | 0.1 - 0.3 | 100 (with RIE) | 30 - 120 |
The etching of metals is possible in principle, but only with highly corrosive gases, which in turn can corrode the metal. To enhance the etching effect, the parts can be preheated, or if a heating chamber is installed at the plasma system, they can be continuously heated.
| Group | Material | Type of gas | Pressure [mbar] | Performance [%] | Time [min] |
|---|---|---|---|---|---|
| Metal | Aluminium | Ar (sputter etching) | 0.2 - 0.5 | 100 | 30 - 120 |
| Silver | Ar | 0.1 - 0.4 | 100 | 30 - 120 | |
| Titanium | NF3 | 0.1 - 0.4 | 100 | 30 - 120 |
(The process parameters including performance and time must be adjusted to take account of the equipment specification (generator type and strength, electrode assembly) as well as the material properties of the workpiece).
Plastic surfaces in particular can be etched with these processes.
Etching is very important for plastics which are difficult to paint and bond such as POM, PPS and PTFE. Better adhesion is achieved by the increased surface area.
Typical etching gases include oxygen, various flourine/chlorine gas combinations, and hydrogen.
| Group | Material | Type of gas | Pressure [mbar] | Performance [%] | Time [min] |
|---|---|---|---|---|---|
| Plastics | POM | O2 / O2 + CF4 | 0.1 - 0.4 | 100 | 30 - 120 |
| PPS | (O2) | 0.1 - 0.4 | 100 | 30 - 120 | |
| PTFE | H2 | 0.2 - 0.5 | 100 | 20 - 120 |
(The process parameters including performance and time must be adjusted to take account of the equipment specification (generator type and strength, electrode assembly) as well as the material properties of the workpiece).
Plasma etching of glass in a vacuum is time-consuming and expensive. The glass is only slowly removed by the ionized gas particles. Glass consists mainly of SiO2 and can therefore in principle be etched with fluorinated hydrocarbons (with the addition of oxygen).
The low erosion rate and the associated long process time are responsible for the high cost of such processes.
Ceramics (such as Al2O3) can be etched with corrosive and non-corrosive gases.
Corrosive gases include all chlorine and fluorine-containing gases. Argon belongs to the non-corrosive gases.
Generally one can say that fluorine-containing gases have a higher erosion rate than other non-corrosive gases, chlorine-containing gases are better than the non-corrosive gases in their etching effect.
Al2O3 is best etched with fluorine-containing gases.
| Group | Material | Type of gas | Pressure [mbar] | Performance [%] | Time [min] |
|---|---|---|---|---|---|
| Other | Al2O3 | CF4 | 0.1 - 0.6 | 100 | 30 - 120 |
| SiO2 | CF4 | 0.1 - 0.3 | 100 (with RIE) | 30 - 120 |
(The process parameters including performance and time must be adjusted to take account of the equipment specification (generator type and strength, electrode assembly) as well as the material properties of the workpiece).
You can find more information under "Applications".