利用紫外光刻技术进行SU8胶的研究

SU8光刻胶优异的性能在MEMS技术的发展重得到了广泛的应用,已经成为MEMS研究中必不可少的方法之一.SU8光刻胶能够进行厚度达毫米的结构研究工作,另一方面SU8结构具有很好的侧面垂直结构,通过控制工艺参数,能够获得满意的SU8胶结构.SU8光刻胶已应用于LIGA技术的标准化掩模制造工艺和一些器件的研究工作.在SU8胶研究过程中,克服了许多技术难题,使得这一技术能够应用到实际的需要中.     

利用紫外光刻技术进行SU8胶的研究

SU 8光刻胶优异的性能在MEMS技术的发展重得到了广泛的应用 ,已经成为MEMS研究中必不可少的方法之一。SU 8光刻胶能够进行厚度达毫米的结构研究工作 ,另一方面SU 8结构具有很好的侧面垂直结构 ,通过控制工艺参数 ,能够获得满意的SU 8胶结构。SU 8光刻胶已应用于LIGA技术的标准化掩模制造工艺和一些器件的研究工作。在SU8胶研究过程中 ,克服了许多技术难题 ,使得这一技术能够应用到实际的需要中。     

利用紫外光刻技术进行SU8胶的研究

SU8光刻胶优异的性能在MEMS技术的发展重得到了广泛的应用，已经成为MEMS研究中必不可少的方法之一。SU8光刻胶能够进行厚度达毫米的结构研究工作，另一方面SU8结构具有很好的侧面垂直结构，通过控制工艺参数，能够获得满意的SU8胶结构。SU8光刻胶已应用于UGA技术的标准化掩模制造工艺和一些器件的研究工作。在SU8胶研究过程中，克服了许多技术难题，使得这一技术能够应用到实际的需要中。     

新型MEMS可变光衰减器的微磁执行器

探讨了新型可变光衰减器－光纤横向偏移型MEMS可变光衰减器的微磁驱动方式，从理论上分析了微磁执行器设计时应遵从的原理，讨论和设计了微磁执行器的各个参数，新开发了结合使用正胶（AZ－4000系列）和负胶（SU－8系列）的UV－LIGA工艺：在制作了光纤定位槽的基片上溅射Cr/Cu作为电镀种子层，涂布正胶，紫外光刻得到电镀模具，电镀Cu和FeNi分别得到线圈的下层、中层和上层以及铁芯；在完成下层和中层后，分别进行一次负胶工艺以形成电绝缘层和后续结构的支撑平台，即涂布负胶覆盖较下层结构，光刻开出了通往较上一层的通道并使SU－8聚合、交联以满足性能要求。并运用该工艺实现了微磁执行器。     

SU-8胶及其在MEMS中的应用

SU 8胶是一种负性、环氧树脂型、近紫外线光刻胶。它适于制超厚、高深宽比的MEMS微结构。SU 8胶在近紫外光范围内光吸收度低 ,故整个光刻胶层所获得的曝光量均匀一致 ,可得到具有垂直侧壁和高深宽比的厚膜图形 ;它还具有良好的力学性能、抗化学腐蚀性和热稳定性 ;SU 8胶不导电 ,在电镀时可以直接作为绝缘体使用。由于它具有较多优点 ,被逐渐应用于MEMS的多个研究领域。本文主要分析SU 8胶的特点 ,介绍其在MEMS的一些主要应用 ,总结了我们研究的经验 ,以及面临的一些问题 ,并对厚胶技术在我国的应用提出建议和意见     

等离子刻蚀工艺中UV坚膜技术研究

对正性光刻胶进行UV坚膜处理，可有效地保持图形形貌的完整性，并提高抗蚀性能，可消除等离子刻蚀中容易产生的燃胶等现象，但坚膜用起始温度、终点温度、温升速率及UV光照时间等参数对坚膜效果均会产生较大的影响。参数选择不当，同样会产生不良效果。     

UV LIGA技术在毫米波太赫兹器件中的应用进展

采用紫外光刻电铸和微成型(UV LIGA)技术制造太赫兹真空器件的高频结构,频率为94~220 GHz。对于94 GHz高频结构,尺寸误差≤15 μm,采用此高频结构的脉冲行波管输出功率大于100 W;180 GHz高频结构,尺寸误差≤5 μm,采用此高频结构的太赫兹行波管二倍频器输出功率高于100 mW,带宽为11.4 GHz;220 GHz高频结构,尺寸误差≤3 μm,衰减因子为240 dB/m。UV LIGA技术在太赫兹真空器件中的成功应用,不但为毫米波太赫兹器件研制奠定了基础,同时也为UV LIGA技术在设计制造毫米波太赫兹器件领域,包括有源和无源器件,开辟了一番新天地。     

质子LIGA工艺的探讨

提出采用掩模法的质子LIGA方法,即利用厚胶光刻产生掩模,然后进行质子束深度刻蚀、显影获得微结构。根据TRIM96程序进行模拟计算,该方法可以获得深度达数毫米、深宽比为30以上的微结构。利用通常的LIGA工艺制备了质子束深度刻蚀的掩模。在高能所35MeV质子加速器上进行曝光试验,结果表明,采用PMMA光刻胶具有足够的灵敏度。     

LIGA技术研究现状及工业应用

微型构件不仅可以用硅工艺制造，而且可以通过精密工程、激光烧蚀、微电子放电加工、RIE和LIGA技术等许多其他技术来完成。本文展示了Forschungszentrum Karlsruhe研究中心开发的LIGA技术的研究现状及工业应用，同时对相关技术进行了描述，如牺牲层技术及利用SU-8负性光刻胶进行常规紫外光刻制造铸塑模具的技术等。此外，在LIGA技术的应用方面，对其在微型分光计、光纤连接器、摆线齿轮传动系统、光学外差接收机及微机械陀螺仪等领域的特殊的制造工艺及功能进行了介绍。     

OMR-85光刻胶的研究与应用

在半导体制造中，光刻胶是重要的原材料之一，本文从转速与膜厚，感光灵敏度，图形变化差等方面对ORM-85光刻胶进行了研究，得出了用于大生产的一套工艺，解决了接触式曝光方式粘版的问题及提高了产能。     

Stable superhydrophobic surfaces induced by dual-scale topography on SU-8

SU-8 is a photosensitive resist widely used for the fabrication of MEMS and lab-on-a-chip devices, as well as of model structures for testing wetting theories. In this work, superhydrophobic surfaces are fabricated on SU-8 by combining micro- and nano-sized structures formed by means of lithography and plasma etching, respectively. It is found that nanotexturing of the micropatterned SU-8 surfaces is essential in enhancing surface hydrophobicity and rendering the surfaces water repellent (i.e. minimizing contact angle hysteresis). The proposed method will be shown to be of paramount importance for the fabrication of mechanically stable and robust superhydrophobic SU-8 surfaces with low aspect ratio microstructuring.     

SU-8胶与基底结合特性的实验研究

SU-8胶是一种负性、环氧树脂型、近紫外线光刻胶。它适于制作超厚、高深宽比的MEMS微结构。为电铸造出金属微结构，通常需要采用金属基底。但SU-8胶对金属基底的结合力通常不好，因而限制了其深宽比的提高。从SU-8胶与基底的浸润性、基底表面粗糙度以及基底对近光紫外光的折射特性入手，对SU-8胶与基底的结合力进行分析，首次指出：在近紫外光的折射率高的基底与SU-8胶有很好的结合性。经实验得出经过氧化处理的TI片的SU-8胶的结合性强。这有利于为MEMS提供低成本，高深宽比的金属微结构。     

Three-dimensional SU-8 sub-micrometer structuring by electron beam lithography

We demonstrate electron beam lithography on the negative tone electron resist SU-8 to fabricate self-supporting three-dimensional structures in sub-micrometer range. Applying SU-8 thin films spin cast on glass substrates and forming layers of 1 μm thickness, the structuring is performed in a two step process. First, the SU-8 film is exposed for supporting structures down to the substrate, a second exposure step with accordingly modified parameters leads to elevated structures. Applications as microscale shadow masks for evaporation based deposition processes and microfluidics are discussed.     

Study of X-ray lithographic conditions for SU-8 by Fourier transform infrared spectroscopy

There is growing interest in the use of chemically-amplified resists (CARs) such as SU-8 in the field of microelectromechanical systems (MEMS) research. This is due to its outstanding lithographic performance and its ability for use in the fabrication of stable structures with very high aspect ratio. However, it is important to control the processing conditions for optimum results in the desired application. In this investigation, the thickness (10-25 μm) of SU-8 resist film, due to different spin coating speeds on silicon wafers, was measured using Fourier transform infrared (FT-IR) spectroscopy. The effect of thermal-initiated cross-linking at various temperatures (95-160 °C) for 15 min baking time on the 25 μm SU-8 resist was studied by monitoring the 914 cm⁻¹ absorption peak in the FT-IR spectrum. Results of the experiments showed that the onset of thermal-initiated cross-linking begins at about 120 °C. Furthermore, 25 μm SU-8 resist was optimized for X-ray lithographic applications by studying the cross-linking process of the resist under different conditions of post-exposure bake (PEB) temperatures. The exposure dose of soft X-ray (SXR) irradiation with energies about 1 keV from a dense plasma focus (DPF) device was fixed at 2500 mJ/cm² on the resist surface. Results showed that the optimum processing conditions consisted of an intermediate PEB at 65 °C for 5 min, with the PEB temperature ramped up to 95 °C over 1.5 min and then followed by a final PEB at 95 °C for 5 min. The scanning electron microscopy (SEM) images showed SU-8 test structures successfully imprinted, without affecting the resolution, and with aspect ratios of up to 20:1 on 25 μm SU-8 resist.     

Microcontact printing of biomolecular gratings from SU-8 masters duplicated by Thermal Soft UV NIL

Thermal Soft UV nanoimprint lithography (NIL) was performed to replicate nanostructures in SU-8 resist. The SU-8 resist was structured with a PDMS stamp molded against an original silicon master which comported gratings of lines (500 nm width/1 μm pitch). The patterns obtained in SU-8 were used in a second step as a template for PDMS molding of daughter stamps. Pattern transfer quality and dimension control were achieved on these second generation PDMS stamps using AFM measurements. As a final validation of the whole duplication processes, these second generation PDMS stamps were finally employed to perform μCP of streptavidin molecules on a glass slide activated by plasma O₂ treatment. AFM observation and fluorescence microscopy reveal that molecular patterns produced with SU8-molded PDMS stamps are not discernable from those obtained with a PDMS stamp directly molded on the original silicon master. Coupling Thermal Soft UV NIL and microcontact printing opens a new method for generating a large quantity of SU-8 templates on which functional PDMS stamps can be replicated in a reduced time. We thus propose a functional duplication process for soft-lithography implementation which may further reduce the cost of this technology for industrial development.     

Microstructuring of SU-8 photoresist by UV-assisted thermal imprinting with non-transparent mold

In this study, we explored a rapid and low-cost process for patterning in a SU-8 photoresist by thermal imprinting with a non-transparent mold such as Ni mold. One of major obstacles in the process is that the extremely good formability of uncured SU-8 even near room temperature causes the collapse of imprinted patterns during and after de-molding because a sample cannot be exposed to UV light during imprinting owing to the non-transparency of a mold. To overcome this problem, un-cured SU-8 resists were pre-treated with UV light, heat, and O₂ plasma for controlling their formability, and applied to thermal imprint tests to be compared each other in terms of the replication fidelity. As a result, a SU-8 sample pre-treated with UV light for 8 s resulted in the best replication quality for given imprint conditions and mold dimensions, and we could successfully replicate micro patterns in SU-8 resist without a quartz mold. As compared with conventional UV-imprint processes, this process has potential merits such as a lower mold cost, an easier mold release and a less air-entrapment.     

Exposure parameters for MeV proton beam writing on SU-8

Proton beam writing was performed on a lithographic resist to determine the main parameters required to achieve the minimum feature size, maximum pattern lateral density and maximum aspect ratio. A 2.5 MeV proton beam focused to sizes between 1.5 and 2.5 μm was used to expose SU-8 negative resist. The number of protons per pixel was varied in the exposure of SU-8 with thicknesses between 5 and 95 μm. Patterns consisting of single pixels, single-pixel lines and multi-pixel areas with different densities were fabricated. The smallest structures achieved were posts 1.5 μm in diameter with 4:1 structure-space ratio in 15 μm thick resist and the highest aspect ratio structures of 20:1 in 40 μm resist were produced. It was found that the minimum feature size depended only on the beam size, and ±10% post size accuracy could be achieved within 40-70% variation of the number of protons. MeV proton beam allows a direct fabrication of complex shapes without a mask in single-step irradiation and, in addition, no proximity correction is needed. We present examples of MeV proton beam written single and multi-pixel microstructures with easily reproducible high aspect ratios and densities.     

High density patterns fabricated in SU-8 by UV curing nanoimprint

We present results on the nanofabrication of high density patterns in SU-8 resist, based on nanoimprinting combined with UV curing. The temperature dependence of the imprinted depth was investigated. The SU-8 gratings were well resolved with high density, good uniformity and high aspect ratio. This was achieved at low temperature and low pressure. Some issues and possible solutions are discussed. The process should find broader applications such as in the manufacture of nanofluidic channels and nanophotonic structures.     

SU-8胶曝光衍射效应的模拟及丙三醇补偿方法

基于SU-8胶的UV-LIGA技术是MEMS中制备高深宽比结构的一种重要方法,但由于衍射效应会使结构的侧壁不再垂直，根据菲涅耳衍射模型,考虑了丙三醇/SU-8界面的反射和折射现象,模拟了丙三醇填充在掩膜版和光刻胶之间时的刻蚀图形。计算结果与已有的实验进行了比较,模型基本可以描述这种光刻过程,可在设计时作为参考。     

SU-8 nanocomposite photoresist with low stress properties for microfabrication applications

A new nanocomposite photoresist based on SU-8 epoxy resin has been developed. It consists in a homogeneous dispersion of nano-silica particles in the negative tone photosensitive SU-8. The nanocomposite photoresist is more sensitive than the SU-8 photoresist and the photopatterned composite structures show low stress and less cracks than pure SU-8 structures. No significant resolution difference has been observed for both materials.