Drag-a-drop: a characterization tool for immersion lithography

摘要

In order to quickly and cheaply test candidate fluids and coatings for immersion lithography, we have devised a fluid handling scheme that we call drag-a-drop. We have constructed a prototype tool in order to test materials using this fluid scheme, and conducted several experiments with it. From these tests, we have determined that a hydrophobic topcoat with low contact angle hysteresis on the substrate increases the maximum stable scanning velocity by at least a factor of 2 over a standard 193 nm photoresist. We observed that instabilities on the receding contact line are unaffected by height, but the onset of instability on the advancing contact line occurs when the height of the lens is low. We also examined the drag-a-drop technique for possible use in laser mask writing, and found that by means of a hydrophobic topcoat, the lens can be completely removed from the substrate while keeping the immersion droplet affixed to the lens.