Metal-silicide-nitridation for stress reduction

A method of controlling a change in transmissivity of a pellicle, the method comprising:

• providing an initial pellicle that shows a change in transmissivity upon exposure of the initial pellicle to EUV radiation;
• and
• providing the initial pellicle with at least one compensation layer which has increased transmissivity upon exposure to EUV radiation and/or with at least one compensation layer which has decreased transmissivity upon exposure to EUV radiation, so that an updated pellicle is obtained which comprises the initial pellicle and the at least one compensation layer and which counteracts the change in transmissivity of the initial pellicle upon exposure to EUV radiation.

A method of designing a pellicle for a lithography apparatus, the method comprising:

• measuring a change in transmissivity of an initial pellicle upon exposure to EUV radiation;
• and
• using the measured change in transmissivity to select one or more materials having a change in transmissivity upon exposure to EUV radiation which most closely mirrors the change in transmissivity of the initial pellicle for inclusion in an updated pellicle.