<title>Stencil mask key parameter measurement and control</title>

Abstract

Stencil masks for Ion Projection Lithography (IPL) are manufactured in a SO! wafer flow process [Ii. l'hcy consist of a 3tni thick stencil membrane coated by a O.5f.im thick carbonic protection layer.For mask manufacturing, the key parameters which have to be kept under tight control in order to have a high yield are critical dimensions (CD), image placement and defect density. In order to control critical dimensions, the parameters determining CD have to be known in detail. F-beam writing, resist processing, silicon and carbon etching are main contributors. Their impact will be discussed. For CD measurement. difftrent alternatives of tools, optical CD microscopes, AFM and SEM are discussed. Image placement is one of the most critical parameters for IPL stencil masks, as process-induced distortions occur and are to be corrected by a software using FE calculations. Masks usually are specified to 0 defects. Defect inspection results of IPL stencil masks of optical tools arc presented, as well as results from e-beam inspection. In addition, defect management for stencil masks in general and cleaning techniques are discussed.