Specific Process Knowledge/Etch/DRIE-Pegasus/System-description: Difference between revisions
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The DRIE-Pegasus | The DRIE-Pegasus tools take the well established Bosch process known from the [[Specific_Process_Knowledge/Etch/ASE_(Advanced_Silicon_Etch)|ASE]] a significant step further. In the ASE the Bosch process has two cycles, etch and passivation. During each cycle the process parameters are kept constant: | ||
*In the passivation cycle, a C<sub>4</sub>F<sub>8</sub> plasma is formed using the RF coil power only and a teflon-like coating is created on all surfaces thus protecting the sidewalls in the subsequent etch cycle. | *In the passivation cycle, a C<sub>4</sub>F<sub>8</sub> plasma is formed using the RF coil power only and a teflon-like coating is created on all surfaces thus protecting the sidewalls in the subsequent etch cycle. | ||
*In the etch cycle | *In the etch cycle | ||
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#a higher pressure during the etch increases the density of reactive species and hence the etch rate. Since a high platen power is no longer necessary to drive the ion bombardement, lowering it will reduce the impact on the masking material thus improving the selectivity. | #a higher pressure during the etch increases the density of reactive species and hence the etch rate. Since a high platen power is no longer necessary to drive the ion bombardement, lowering it will reduce the impact on the masking material thus improving the selectivity. | ||
These conflicting demands are the same on the ASE. However, with hardware improvements on the DRIE-Pegasus such as | These conflicting demands are the same on the ASE. However, with hardware improvements on the DRIE-Pegasus tools such as | ||
*fast response digtal MFC's mounted on top of the process chamber itself to shorten the gas line | *fast response digtal MFC's mounted on top of the process chamber itself to shorten the gas line | ||
*fast APC valve | *fast APC valve | ||
*fast RF power supplies | *fast RF power supplies | ||
the etch and deposition cycles may be split into three separate phases, | the etch and deposition cycles may be split into three separate phases, labelled Delay, Boost and Main. Following the arguments from above, the third phase (Delay) may be thought of as a short delay that ensures a very low pressure (and thus extremely good ion directionality) before the ion bombardment. The standard etches on the Pegasus only make use of up to two phases. | ||
== Processing options on the Pegasus == | == Processing options on the Pegasus == | ||