EUV mask image placement management in writing, registration, and exposure tools

Compensation of overlay errors due to mask bending and non-flatness for EUV masks

“…A significant fraction of overlay errors for EUV masks is from bow which can be reduced by stress compensation layers [19]. We have developed an analytical model for thin film stress induced bow in EUV masks and demonstrated compensation, during the e-beam write process, of bow induced overlay errors.…”

“…Since the FEM was not calibrated, the predictability of the model will be known only after the initial overlay data is analyzed for the BS figured mask. Reference [19] provides an illustration of the error budget in reticle level pattern placement techniques. Besides any potential errors in the accuracy of the FEM, there are other errors in EWOC that will impact the precision of pattern placement error compensation.…”

Assessment of EUV reticle blank availability enabling the use of EUV tools today and in the future

“…The third item is related to the change in reticle bow occurring when patterning the absorber affects the balance between the stress in the absorber layer and multilayer on the front-side on one hand, and that of the back-side coating on the other hand (See also Ref. 23). …”

The first full-field EUV masks ready for printing

“…Mask writer nm ±12 current writer performance including all data preparation Patterning and etch deformation nm ±4 Upper limit for layer stress, see also [6] Substrate On the short range (high spatial roughness, which leads to frequencies in the order of the structure dimensions) the local slope leads to non-telecentricity, which shifts the image in combination with defocus terms [7]. The local slope information will be transferred only by imaging of dense structures but not in case of isolated lines.…”