Progress in deep-UV photoresists

Higher resolution can be achieved in lithography by decreasing the wavelength of the exposure source. However, resist material and their processing are also important when we move to a shorter wavelength lithography technology. This paper reviews the recent development and challenges of deep-UV photoresists and their processing technology.     

超支化聚合物抗蚀剂的感光性能

通过凝胶率对曝光能量的变化,研究显影液、光敏剂用量等对超支化聚合物光致抗蚀剂感光性能的影响.结果表明:四甲基氢氧化胺水溶液对超支化聚合物光致抗蚀剂的溶解能力比碳酸钠强,对感光性具有较大的影响;当显影液相同时,随着引发剂的量增大,E0,gel减小,反差γgel在引发剂的用量为6%时,可达到8.13,E0,gel达到5.5mJ/cm2.     

Control of magnetic properties in metallo-organic thin films

Magnetic metallo-organic thin films have been prepared at different growth temperatures to characterize the influence of structural properties on the magnetic characteristics. A quantitative analysis of the grain size shows that the growth temperature increases the elliptical grain size considerably. Long grains of planar iron phthalocyanine form quasi one-dimensional iron chains, which are embedded in a carbon matrix along the other two dimensions. The chains are narrowly spaced (1.3 nm) and run parallel to the substrate. Temperature-dependent magnetization curves depend on the structural details of the iron chains. These magnetic properties are tuned with deposition parameters.     

Improvement in gate LWR with plasma curing of ArF photoresists

The line width roughness (LWR) in gate electrodes is one of the most critical issues in obtaining sufficient transistor performance in 45-nm half-pitch (hp 45) node devices. ArF (argon fluoride) photoresists are, however, very fragile and easily deformed during plasma exposure. We evaluated the change in the chemical nature of an ArF photoresist caused by various plasmas and found that “HBr plasma curing” induces the selective detachment of heterocyclic units in the photoresist. We found that the glass transition temperature (T_g) of the photoresist decreased due to this detachment, leading to surface smoothening of the photoresist layer. Finally, we applied this curing process to the fabrication of line patterns and it was demonstrated that the process remarkably improved LWR.     

热压印刻蚀技术

纳米压印技术是一种高分辨率、廉价、高效的纳米结构制备技术。它既继承了传统光刻技术所具有的并行性,又同时拥有传统光刻技术不易达到的纳米结构制备能力,这为今后纳米结构的广泛应用提供了良好的条件。文章介绍了纳米热压印技术中核心工艺流程,包括：模板的制备、抗粘层的制备、压印过程中温度与压力的影响、反应离子刻蚀,并且给出了利用纳米热压印技术制备的光栅结构,最后展望了纳米压印技术的前景。     

Mechanical properties of zirconia-alumina composite ceramics prepared from Zr-Al metallo-organic compounds

The mixture of a Zr-Al metallo-organic compound and Al₂O₃ powder yields dense ZrO₂-Al₂O₃ composite ceramics. The fraction of the tetragonal ZrO₂ phase in as-sintered ZrO₂-Al₂O₃ ceramics is almost 100% and the ZrO₂ grains at about 500 nm in diameter are dispersed in the matrix. The ceramics have high fracture toughness and bending strength.     

Sensitivity study of two high-throughput resolution metrics for photoresists

The resolution of chemically amplified resists is becoming an increasing concern, especially for lithography in the extreme ultraviolet (EUV) regime. Large-scale screening is currently under way to identify resist platforms that can support the demanding specifications required for EUV lithography. Current screening processes would benefit from the development of metrics that can objectively quantify resist resolution in a high-throughput fashion. Here we examine two high-throughput metrics for resist resolution determination. After summarizing their details and justifying their utility, we characterize the sensitivity of both metrics to known uncertainties in exposure tool aberrations and focus control. For an implementation at EUV wavelengths, we report aberration and focus-limited error bars in extracted resolution of approximately 1.25 nm rms for both metrics, making them attractive candidates for future screening and downselection efforts.     

The vapour-phase ultraviolet spectra of metallo-organic precursors to III–V compounds

Vapour-phase UV (ultraviolet) spectra are reported for the trimethyls and triethyls of gallium and indium, aluminium triethyl and indium cyclopentadienyl. Strong absorptions are observed between200 and300 nm; these are adequate for efficient energy coupling in photolysis.     

In-situ devitrification of metallo-organic decomposition solutions in the high voltage electron microscope

The decomposition of metallo-organic compound films to yield ceramic oxides with a composition in the lead lanthanum zirconium titanate (PLZT) phase field has been observed using an environmental cell in the transition electron microscope. Diffraction pattern analysis indicates that the first formed phase is lead oxide but that this is rapidly followed by the formation of an homogeneous PLZT composition. The results are supported by differential thermal analysis (DTA)/thermogravimetric analysis (TGA) of the precursor solutions. These observations indicate that it may be practical to prepare thin films of this important electrooptic material by this route.     

Lithography: rewriting the rules

Dip-pen nanolithography (DPN) is generating significant interest as a means of patterning surfaces with submicron-scale designs. Advocates of DPN, which effectively uses an atomic force microscope (AFM) as a pen, herald its ability both to fabricate and monitor high-resolution, miniaturized molecular arrays. The novel technology is not without its critics, however, who question the utility and practicality of paint-pot-style nanofabrication. Nonetheless, the relative availability and affordability of DPN tools is allowing an increasing number of scientists and engineers to think small.In December 1959, the Nobel prize-winning physicist Richard Feynman gave a lecture to the American Physical Society that outlined his vision of a futuristic nanoscale world. He dismissed reports of fingernail-sized electric motors and devices that could cram text onto pinheads as little more than crude first steps towards true miniaturization. “It is a staggeringly small world that is below,” he advised the assembled throng.     

分步式压印光刻研究

针对微纳制造中光刻环节的光衍射限制，讨论了可能成为下一代光刻技术路线的压印光刻。通过对比热压印、微接触转印及常温压印的技术特点，设计了一套低成本、结构简单的紫外光固化常温压印光刻机构。其大行程纳米级定位、纳米级下压系统消除了压印过程中的机构热变形误差、驱动间隙、蠕动误差等，具有分步式纳米级驱动多场压印及纳米级下压加载能力，可实现多次重复高保真图形复制。     

A comparative study of different thick photoresists for MEMS applications

This work reports on recent advances in microfabrication process technology for medium to high-aspect ratio structures realised by UV photolithography using different kinds of photoresists. The resulting structures were used as moulds and will be translated into metallic structures by electroplating. We used four types of photoresists: SPR 220-7 novalak based (positive), SU8 epoxy based (negative), Ordyl P-50100 acrylate based (negative) dry film photoresist, and Diaplate 132 acrylate based wet photoresist (negative). The motivation for this work was to find an alternative to SU-8 photoresist, which is difficult to process and remove after electroplating. Depending on the application, we found that Ordyl P-50100 dry film photoresist is the best alternative to SU8 for realization of approximately 100 μ m deep moulds for electroplating in acidic electroplating solution. SPR 220-7 is a good alternative to SU8 for fabrication of 50 μ m deep moulds and electroplating in alkaline solutions. The results presented in this paper will open up new possibilities for low-cost processes using electroplating for MEMS applications.     

One Step Lithography of Polypyrrole

Large areas of polypyrrole (PPy) thin films deposited onto inert polymeric substrates are structured by direct laser interference patterning (DLIP). Several square millimeter areas could be produced with one single (10 ns) pulse, at room temperature and atmospheric pressure. Nanometric arrays of lines (>600 nm) or grids of PPy deposited on dielectric polymers polypropilene or polypirrol (PP or PE) are fabricated by DLIP at 355 nm. The period of the lines structures, measured by white light interferometry (WLI), is 3.5 µm. Regular structures are analyzed using scanning electron microscope (SEM) and a focus ion beam (FIB) tomography. It is shown that only the PPy film is structured while the PP or PE substrate remains unaltered. Fourier transform infrared spectroscopy (FTIR) and UV‐vis spectroscopy, permit to ensure that PPy chemical structure remains unaltered after the structuration process. The width of PPy lines can be tailored by controlling the fluence of the laser beam. Contact angle measurement shows that the wettability is affected by the structuring, making the surface more hydrophobic. The structuring technique seems to be suitable for the fabrication of PPy regular structures over various substrates.     

Growth of yttria stabilized zirconia thin films by metallo-organic, ultrasonic spray pyrolysis

Randomly and preferentially oriented thin films of yttria stabilized zirconia (YSZ) have been prepared on fused quartz substrates by ultrasonic spray pyrolysis using zirconium octylate and yttrium octylate as metallo-organic precursors at a substrate temperature of 873–1023 K. The as-deposited films composed of fine columnar grains were found to be crystalline and transparent with a cubic fluorite structure. With increasing substrate temperature the growth rate and diameter of the columnar grains increased and the crystal habit showed a preferential orientation at the (111) plane.