Damage-free mask repair using electron beam induced chemical reactions

Substrate damage from Ga ions is a fundamental problem of using focused ion beam (FIB) for mask defect repair. One way to avoid substrate damage from repair is to replace Ga ions with electrons. In this paper, we describe our efforts and present some promising results that demonstrate the feasibility of using e-beam induced processes for mask repair. We employ e-beam induced chemical etching for opaque defect removal and metal deposition for clear defect repair. The examples will include Pt deposition, quartz etch for phase-shift mask and TaN etch for EUV mask. High-resolution electron beam technology is relatively mature, so the infrastructure for building an e-beam system suitable for mask repair exists today. This makes the development of an e-beam based damage-free repair technology attractive. E-beam also offers superior spatial resolution for high edge placement precision and image quality for small defects on ever shrinking mask features.