Specific Process Knowledge/Etch/DRIE-Pegasus/System-description: Difference between revisions
| Line 6: | Line 6: | ||
**the ion bombardment driven by the platen power ''first'' removes the passivation layer on the surfaces directly exposed to the ions (i.e. horizontal surfaces) | **the ion bombardment driven by the platen power ''first'' removes the passivation layer on the surfaces directly exposed to the ions (i.e. horizontal surfaces) | ||
**''then'' as the bottom of the structures are opened the etch of silicon itself starts. | **''then'' as the bottom of the structures are opened the etch of silicon itself starts. | ||
[[Image:boostdelay4b.jpg |400x400px|thumb|The etch cycle may be split into three parts, Boost, Delay and Main, where process parameters such as pressure, gas flows or RF powers have different values.]] | [[Image:boostdelay4b.jpg |400x400px|thumb|The etch cycle may be split into three parts, Boost, Delay and Main, where process parameters such as pressure, gas flows or RF powers have different values. The red curve shows the possible characteristics of the platen power.]] | ||
Here, it is clear that one can distinguish two phases of the etch cycle; one where the ion bombardment removes the polymer and one where the actual etching of silicon takes place. Considering what process conditions are favorable we realize that | Here, it is clear that one can distinguish two phases of the etch cycle; one where the ion bombardment removes the polymer and one where the actual etching of silicon takes place. Considering what process conditions are favorable we realize that | ||
#the ion bombardment requires a low pressure in order for the ions to have a long mean free path and hence good directionality. Also, a high platen power is required to drive the ion bombardment. | #the ion bombardment requires a low pressure in order for the ions to have a long mean free path and hence good directionality. Also, a high platen power is required to drive the ion bombardment. | ||