A pattern collapse occurs during the fabrication process when the liquid surrounding the semiconductor pattern dries up. To prevent this, NTT-AT has developed the PCO-4SC to conduct supercritical drying operations.
Fine structures can collapse when a previously used rinse solution remains between the structure’s lines. This is because a liquid/gas interface is created during the drying out process when 1) alcohol or water is used in rinsing, and 2) when conventional nitrogen blow is used for drying.
The PCO-4SC can be used to prevent pattern collapse by making the liquid used in the rinsing process supercritical. In this region, liquid and gas are indistinguishable. Thus, there is no liquid/gas interface and no subsequent surface tension or capillary force. The release of the fluid used for rinsing to the atmosphere at a constant temperature dries the sample pattern without crossing the vapor-liquid curve.
For information on how you can use the PCO-4SC supercritical dryer to prevent pattern collapse, download the datasheet. You can also visit NTT-AT’s webpage.