Membranes are in wide use today as microsensors, vacuum windows, and lithography mask substrates. They are fragile and difficult to protect, however. We show that membrane strength, and thus process yield, are increased by a newly designed ‘‘skirted’’ membrane. This structure strengthens the attachment of membrane to support, reinforcing a region where fractures usually originate. The skirt design was applied to polysilicon membranes on glass supports, used for x‐ray lithography mask blanks, and was shown to increase strength three times over polysilicon or silicon‐rich nitride membranes on silicon supports, to anaverageof 1.5 GPa. More significantly, skirted polysilicon membranes exhibit fracture pressure differentials that are six times higher in the same comparison, having tremendous impact on process and application durability.