Alexander Kaya

A novel electron-beam-based photomask repair tool

High-resolution electron-beam assisted deposition and etching is an enabling technology for current and future generation photo mask repair. NaWoTec in collaboration with LEO Electron Microscopy has developed a mask repair beta tool capable of processing a wide variety of mask types, such as quartz binary masks, phase shift masks, EUV masks, and e-beam projection stencil masks. Specifications currently meet the 65 nm device node requirements, and tool performance is extendible to 45 nm and below. The tool combines LEOs ultra-high resolution Supra SEM platform with NaWoTecs e-beam deposition and etching technology, gas supply and pattern generation hardware, and repair software. It is expected to ship to the first customer in October this year. In this paper, we present the tool platform, its work flow oriented repair software, and associated deposition and etch processes. Unique features are automatic drift compensation, critical edge detection, and arbitrary pattern copy with automatic placement. Repair of clear and opaque programmed defects on Cr, TaN, and MoSi quartz masks, as well as on SiC and Si stencil masks is demonstrated. We show our development roadmap towards a production tool, which will be available by the end of this year.

Electron-beam Induced Processes and their Applicability to Mask Repair

The applicability of electron-beam induced chemical reactions to mask repair is investigated. To achieve deposition and chemical etching with a focused electron-beam system, it is required to disperse chemicals in a molecular beam to the area of interest with a well-defined amount of molecules and monolayers per second. For repair of opaque defects the precursor gas reacts with the absorber material of the mask and forms a volatile reaction product, which leaves the surface. In this way the surface atoms are removed layer by layer. For clear defect repair, additional material, which is light absorbing in the UV, is deposited onto the defect area. This material is rendered as a nanocrystalline deposit from metal containing precursors. An experimental electron-beam mask repair system is developed and used to perform exploratory work applicable to photo mask, EUV mask, EPL and LEEPL stencil mask repair. The tool is described and specific repair actions are demonstrated. Platinum deposited features with lateral dimensions down to 20 nm demonstrate the high resolution obtainable with electron beam induced processes, while AFM and AIMS measurements indicate, that specifications for mask repair at the 70 nm device node can be met. In addition, examples of etching quartz and TaN are given.

Vapour supply manifold for additive nanolithography with electron beam induced deposition

Three-dimensional additive nanolithography with electron beam induced deposition (EBID) is very well suited for generating very fine structures at very high resolution for single electron tunnelling (SET) applications. Many applications involving material deposition, etching, and high resolution for two- and three-dimensional structuring of surfaces can benefit from a novel lithography system having material supply in the form of vapours incorporated and inserted into the lithography system. Such a deposition lithography system is developed and applied to construct deposits from nanocrystalline materials in a maskless structure generation process.

Determination of the refractive index of photonic-crystal material from scattering measurements

Summary form only given. The rapid progress of nanotechnology now allows the development of devices based on the properties of photonic crystals, for instance, optical filters, switches and wave guides. Two-dimensional photonic crystals built as arrays of parallel dielectric circular rods by additive nanolithography using a Si-based precursor have been fabricated and investigated. Their dimensions (diameter and spacing of the rods) are defined in the production process, but the determination of the refractive indices of the rod material presents a formidable task. Bulk material measurements would require a costly production of suitable layers and their results probably would not agree with the in situ values for thin rods. An experimental method is proposed based on a rigorous theory of scattering of a Gaussian beam by a finite row of parallel dielectric circular cylinders. The incoming and the diffracted field are represented by Fourier-Bessel expansions and the translation properties of Bessel functions are used. Thus, the scattering problem is reduced to the solution of a large system of complex linear equations.