Ultraviolet Cleaning Research Articles

P‐12.8: A Vertical Alignment Technology of Proessing ZnO Sputtered with Ozone Applied on Liquid Crystal on Silicon Display Devices

The vertical alignment technology by processing sputtered ZnO film for LCD with ozone is proposed in this paper. The prepared ZnO thin films were treated with ozone in the ultraviolet cleaning machine through polarizer. The wettability of the treated ZnO films switched to hydrophobicity, reaching a contact angle of 92°. With the prepared ZnO film as the alignment layer in the transmissive LCD cell, the vertical alignment (VA) can be realized. The results demonstrated that the test cells not only possessed the photo‐electronic characteristics of traditional VA liquid crystal cells but also had a smaller threshold voltage of 1.95V. In addition, the ZnO films are applied into character display successfully since the VA test cell has a high contrast ratio.

Restoration of absolute diffraction efficiency and blaze angle of carbon contaminated gratings by ultraviolet cleaning

An UV cleaning technique has been used for the removal of carbon contamination from grating surface, using oxygen free-radicals generated by the absorption of UV radiation (172 nm) in atmospheric oxygen. The extent of restoration of absolute diffraction efficiency (ADE) and grating blaze angle of a carbon-contaminated variable line-spaced concave grating (average line spacing of 1200 lines/mm, blaze angle 3.2 deg, and blaze wavelength 10 nm) has been studied over a 5-70 nm wavelength range. The contamination (due to prolonged use in extreme-ultraviolet spectrograph) resulted in a drastic reduction in the diffraction efficiency of grating, along with a change in the blaze angle. The UV cleaning led to the restoration of blaze angle as well as to an increase in the ADE by more than an order of magnitude for the first two diffraction orders (i.e., from ~0.2 to ~7.2%) for the first diffraction order and 0.1 to ~5% for the second diffraction order at the blaze wavelength. The study is useful for the restoration of carbon-contaminated costly optics.

Recycling of surface-enhanced Raman substrates by ultraviolet cleaning

Commercial substrates used for surface-enhanced Raman spectroscopy (SERS) are investigated for their reusability following cleaning with 254-nm UV light from a mercury lamp. SERS of Rhodamine 6G (Rh6G, a dye) and RDX (an explosive) is investigated. It is found that without UV irradiation, the substrate is usable only once, since it is not possible to dislodge the analyte either by prolonged immersion in distilled water or by ultrasonic cleaning. However, prolonged exposure to 254-nm UV followed by immersion in distilled water removes most of the analyte, making the substrate reusable for new SERS measurements. The technique of UV cleaning is demonstrated by recycling the same substrate several times and comparing SERS spectra taken after each cleaning cycle.

Introducing 157 nm Full Field Lithography

157 nm lithography is currently considered as the main technology for the manufacturing of critical 65 nm node layers and beyond. After a number of potential show stoppers of 157 nm have been removed in the last three years, the final phase of development will now start based on the first full-field step and scan exposure systems. This paper describes the status and progress of the IMEC 157 nm program, that is aiming to remove the remaining 157 nm engineering challenges. The first full field scanner (ASML Micrascan VII) is currently under installation at IMEC. The investigation on a number of full-field issues already started. Results on 157 nm resist full field patterning, on reticle handling including vacuum ultra violet cleaning, and on hard pellicle printing are discussed in this paper.

The formation of hydrogen passivated silicon single-crystal surfaces using ultraviolet cleaning and HF etching

We have tried to develop a new procedure to prepare the clean surface of a silicon single crystal. We successfully prepared the contamination free bare silicon surface with ultraviolet cleaning followed by HF dipping with low concentration HF obtained by dilution by organic free ultrapure water, at room temperature under the atmospheric condition. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and ultraviolet photoelectron spectroscopy measurements proved thus prepared surface has a hydrogen monoatomic layer terminating the dangling bonds of silicon. The hydrogen termination was found to have remarkable passivation effect against surface oxidation reaction. A silicon thin-film epitaxially grown on the prepared surface was confirmed to have perfect crystal structure and high-purity level by scanning electron microscopy, reflection high-energy electron diffraction, Raman spectroscopy and secondary ion mass spectroscopy.