Chrome dry etching for 65-nm node mask manufacturing

A new chrome etch system was acquired and implemented to manufacture 65 nm node critical level masks. The etch performance of FEP 171, ZEP 7000, NEB 22, and REAP 200 resist systems in this new chrome etch system was evaluated. The critical dimension (CD) uniformity, etch bias, and etch linearity of this new etch system relative to the older generation etch system is presented. Implementation of the new etch system resulted in a 40-60 nm reduction in etch bias with no degrade in CD uniformity performance. In addition, it was found that the etch contribution to CD linearity was reduced by 50%. Detailed characterization of both macroloading and microloading etch effects was performed and showed substantial improvement relative to the previous generation etch system. The change in chrome etch rate as a function of etch area was reduced by 50%, improving mean to target CD performance on new designs. Implementation of the new etch system has enabled achievement of CD and defect density performance requirements for 65 nm node mask manufacturing. The results presented in this paper were collected during the process development phase and are not necessarily representative of the final optimized process.