Heat behavior of extreme-ultraviolet pellicle including mesh support

Abstract

As is well known, a very short wavelength of 13.5 nm EUV is strongly absorbed by the most materials and this might cause huge heat deposition and as a result the pellicle deformation. Previously we have shown that the temperature rising of the thin pellicle membrane is minimal and cooling between the exposures is efficient enough so that we do not have to worry about the pellicle deformation. People still worry about the temperature rising of the mesh structure. We find that the cooling of the mesh was very slow and can pile up and damage the pellicle because thick (∼ 50 μm) mesh structure has much larger mass compared to very thin (∼ 50 nm) membrane. In order to see this heat behavior of the mesh, we intentionally increased the exposure time up to 2000 ms from normal 10 ms for Si, Zr, and Ni mesh. For the case of silicon mesh, the peak temperature rises up with the exposure time initially, but the temperature is not increased any more and is saturated even though more energy is deposited as the exposure time is increased. This result shows again that the heat pile up to pellicle including both membrane and mesh support can be managed and EUV pellicle can be used for EUV high volume manufacturing. © 2013 SPIE.