Amorphous hydrogenated carbon (a–C:H) is introduced as a constituent of a two–layer resist system for lithography with a scanning tunneling microscope (STM) operating in air. The resist is made up of a thin electron sensitive and chemically amplified top resist (≤50 nm) and a–C:H as a thick conducting and etchable bottom resist. In this setup the bottom resist acts as the counter electrode allowing in principle operation on insulating substrates. We show that it is possible to generate structures with high aspect ratios by transfering the developed top resist patterns by means of oxygen reactive ion etching (RIE) into the bottom resist and halogen RIE into silicon substrates. Linewidths between 100 and 50 nm have been observed in the bottom resist as well as in the substrates.

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Articles you may be interested inComparative evaluation of electron-beam sensitive single layer top surface imaging and bilayer chemical amplification of resist lines process for stencil mask making Negative electron-beam nanofabrication resist using acid-catalyzed protection of polyphenol provided by phenylcarbinol J.Accurate critical dimension control by using an azide/novolak resist process for electron-beam lithography Because of the need of 70 nm structures in the near future, electron-beam ͑e-beam͒ lithography as a means for high resolution lithography is discussed mostly for mask or ASIC fabrication but also for the application in standard lithography. Besides the improvement of new e-beam writing concepts including software and hardware enhancement, the development of new resists and processes is a main objective for a high throughput production. To understand the principal reactions that occur during the patterning process we decided to carry out basic examinations based on chemical amplification of resist lines ͑CARL͒ ͓W.-D. Domke et al., Microlithogr. World 42, 2 ͑1999͔͒ resist materials. The first step was to look at the interaction between the polymer and e-beam. Polymers consisting of chemically identical monomers were synthesized in different molecular ratios and processed as resists without other additives. Detailed investigations of the resists included e-beam patterning with a JEOL JSM-840A/nanobeam pattern generator. The next step was to examine the CAR reaction, i.e., the interaction of the polymer/photoacid generator matrix with the e-beam electrons. Perfluorinated alkysulfonates as PAGs were focused. These compounds generate very strong acids through irradiation. They can be compared, e.g., by their different acid strength, different vapor pressure of the resulting acid, and by their different molecular size. These parameters strongly affect the acid diffusion and consequently the resist resolution as far as the line edge roughness. Within this current article the first complete resist mixtures have been evaluated under process conditions.

With continuously shrinking device structure sizes the photomask suppliers are facing increasing linewidth metrology control requirements. Therefore it is becoming more and more important for equipment suppliers to provide mask metrology tools capable of measuring 0.5 tm and smaller critical dimension (CD) features with high accuracy and repeatability, while offering high throughput for systems to be used in the production environment. CD measurement results obtained on the Leica LWM 250UV will be presented showing not only the considerably improved resolution power and measurement accuracy but also an extension ofthe linearity range to smaller feature sizes using UV light of 365 nm (I-line) instead of white light for illumination in transmitted mode. Results obtained after a system calibration against SEM measurement data show a further extension of the linearity regime. The higher lateral resolution of I-line compared to white light measurements also leads to a CD range value reduction for long term repeatability.