Jozef Petrus Henricus Benschop

Comparison of Extreme Ultraviolet Sources for Lithography Applications

The source is one of the critical factors for the success of Extreme Ultraviolet Lithography (EUVL). Various possibilities to generate EUV radiation exist. The Laser Produced Plasma (LPP), the Synchrotron Wiggler and the gas discharge sources (Z-pinch, Plasma Focus and Capillary discharge) all have the potential to be used for EUV Lithography. EUV sources have to be evaluated as an integral part of the lithography tool, using criteria such as cost of ownership (CoO), wafer throughput, debris contamination issues and dose repeatability. Such a comparison, based on published data and known plans for these sources, has been performed. Although none of the currently known plans for the sources is compliant with requirements for an EUVL production tool, significant further improvement of their performance seems feasible. The LPP and the Synchrotron Wiggler are identified as having a high technical maturity but a relatively high CoO. On the other hand the gas discharge sources have a potential to become low cost and efficient EUVL sources provided a number of technical problems are solved.

Experimental results of the stochastic Coulomb interaction in ion projection lithography

Throughput and resolution are connected in ion and electron projection lithography (IPL and EPL) because of the space charge and Coulomb interaction between the particles in the beam. Due to the lack of experimental data it was not possible to estimate this effect accurately. Therefore an experiment setup has been developed which has the most significant parameters close to planned IPL exposure tools. These parameters are the linear particle density and the crossover shape and size. The stochastic Coulomb interaction blur, depending on the total beam current, has been measured in about 100 settings of the beam current, beam energy, and crossover shape. The results show that the stochastic Coulomb interaction blur scales to the power of 0.587±0.101 (1σ) of the linear particle density in a system with a uniform crossover of 400 μm. To decrease the current density in crossover IPL systems can have an aberrated crossover. In case of this type of crossover of 670 μm the current dependency is 0.820±0.072 (1σ). ...

EUCLIDES: the European EUVL program

A new European research program named EUCLIDES (Extreme UV Concept Lithography Development System) has been started in August 1998. The program headed by ASM Lithography (ASML), partnered by Carl Zeiss and Oxford Instruments, is evaluating EUVL as a viable lithographic solution for resolutions of 70 nm and below. This paper gives an overview of program objectives and status, including a summary of recent highlights.

A model for pressurized hydrogen induced thin film blisters

We introduce a model for hydrogen induced blister formation in nanometer thick thin films. The model assumes that molecular hydrogen gets trapped under a circular blister cap causing it to deflect elastically outward until a stable blister is formed. In the first part, the energy balance required for a stable blister is calculated. From this model, the adhesion energy of the blister cap, the internal pressure and the critical H-dose for blister formation can be calculated. In the second part, the flux balance required for a blister to grow to a stable size is calculated. The model is applied to blisters formed in a Mo/Si multilayer after being exposed to hydrogen ions. From the model the adhesion energy of the Mo/Si blister cap was calculated to be around 1.05 J/m2 with internal pressures in the range of 175-280 MPa. Based on the model a minimum ion dose for the onset of blister formation was calculated to be d = 4.2*10^18 ions/cm2. From the flux balance equations the diffusion constant for the Mo/Si blister cap was estimated to be D_H2 = (10+-1) *10^18 cm2/s.

Fabrication of open stencil masks with asymmetric void ratio for the ion projection lithography space charge experiment

For the ion projection lithography space charge experiment [P.W.H. de Jager et al., J. Vac. Sci. Technol. B 17, 3098 (1999)] a suitable stencil test mask has been realized and used. This article addresses the stress engineering and fabrication process of this specific test mask with openings in the range of some few 100 nm up to some 100 μm. This large difference in stencil pattern dimensions causes reactive ion etching (RIE) lag (dependence of the etch rate on feature size and pattern density) during the fabrication process and considerable stress variations across the membrane field. The solution to these problems was by (i) implementing novel doping technologies to create variable thickness areas on the membrane serving as reinforcement and stress relief structures, and (ii) adjusting the design to feature sizes and pattern densities to the same order of magnitude for the e-beam lithography and RIE processing steps. The etching of the openings through the 3 μm thick Si membrane was done by inductively ...