Characterization of a new polarity switching negative tone e-beam resist for 14nm and 10nm logic node mask fabrication and beyond

The critical layer masks for 14 nm and 10 nm logic nodes are typically bright field, and the key features are opaque structures on the mask. In order to meet the tight critical dimension (CD) requirements on these opaque features the use of a high quality negative tone chemically amplified e-beam resist (NCAR) is required. Until very recently the only negative tone e-beam resists available for use by the mask industry were the traditional cross linking type in which ebeam exposure cross links the material and makes it insoluble in developer. In this paper we will describe the performance of a new polarity switching type of NCAR resist that works by changing the solubility of the exposed resist without cross linking. This has the advantage of significantly reduced swelling and scumming and resulted in major improvements in the resolution of heavily nested features and small clear features on the mask. Additional detailed characterization results will be described.