... in the temperature of the mask plate during alignment, the mask plate will expand or contract. The amount that the mask plate expands or contracts will be determined by the above equation. All of the features on the mask plate will also expand or contract in accordance with the above equation. I have solved this question with the assumption that a 1:1 exposure system, such as a vacuum hard contact, soft contact or proximity system, was used. Therefore, a change in length of one of the features on the mask plate will create an identical change in the pattern that the mask creates on the silicon substrate. In order to ensure that alignment accuracy across the silicon substrate is maintained from one layer to the next within 0.5 um, none of the features on the mask plate must expand or contract more than 0.5 um. Therefore, the change in length ...

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