基于UV-LIGA技术的微注塑金属模具的工艺研究

介绍了一种新颖的微注塑模具的制作方法———无背板生长法,它是利用负性厚SU-8光刻胶,通过低成本的UV-LIGA表面微加工工艺,直接在金属基板上电铸镍图形而制作完成的。讨论了SU-8胶与基底的结合特性以及几种去除SU-8胶的有效方法,所制作的微注塑模具已用于微注塑加工中。无背板生长工艺的突出优点是微电铸时间短、模具质量高,而且还适合于制作其他微机械组件,是目前MEMS领域中比较有发展前途的加工方法。     

基于UV-LIGA技术的双层微齿轮模具镶块工艺

以氧化铟锡(ITO)玻璃作为基底,采用UV-LIGA技术制作了双层微齿轮型腔模具的镶块。首先,采用正胶(RZJ-304)进行光刻,在ITO玻璃表面电镀镍掩模,通过镍掩模对第一层SU-8光刻胶进行背面曝光。再利用正面套刻的方法对第二层SU-8光刻胶进行曝光,显影得到双层微齿轮的胶模。最后,进行微电铸得到双层微齿轮型腔镶块。通过实验验证了双层微齿轮模具镶块制作的工艺流程,优化了其工艺参数,克服了底部曝光不足引起的问题,并对制作工艺过程中产生的涂胶不平整、前烘时胶层不稳定、热板加热不均以及接触式曝光破坏胶层表面等问题进行了研究。所制得的双层微齿轮胶模垂直度高,表面质量好,且套刻精度高。     

微流控芯片金属模具制备工艺研究

为了解决SU-8光刻胶电铸金属模具中遇到的光刻胶脱落和电铸后去胶难等问题，提出了采用硅橡胶（PDMS）微复制与电铸毛细管电泳芯片金属模具相结合的新工艺。该方法首先用SU-8光刻胶制备微通道阳模，以此为模版浇注PDMS阴模，然后在此PDMS阴模上电镀金属模具。与采用SU-8光刻胶电镀金属模具相比，此方法不存在光刻胶与衬底结合力差以及去胶难等问题，所制备的金属模具侧壁垂直，表面光滑。     

压力加工与铸造、成形工艺

0611622 微流控芯片金属模具制备工艺研究[刊,中]／李建华／／微细加工技术．-2005,(4)．-56-58,75(D) 为了解决SU-8光刻胶电铸金属模具中遇到的光刻胶脱落和电铸后去胶难等同题,提出了采用硅橡胶 (PDMS)微复制与电铸毛细管电泳芯片金属模具相结合的新工艺。该方法首先用SU-8光刻胶制备通道阳     

一种利用PDMS工艺解决SU-8去胶问题的方法

提出了一种解决SU-8去胶难题的方法.该方法首先将SU-8微结构用PDMS进行复制,然后利用复制的PDMS微结构进行下一步的电铸,电铸完成后只要简单地将PDMS揭下即可释放出金属模具.通过该方法制备得到了深宽比达到10的金属模具,而且模具表面光滑,侧壁垂直.     

玻璃纤维增强SU-8胶技术

SU-8胶是一种能够以低成本制作高深宽比微结构的负性光刻胶,在非硅微电子机械系统(MEMS)领域具有广阔的应用前景。针对SU-8胶作为微结构材料时,其弹性模量和断裂强度较低的特性,采用透明度高的微细玻璃纤维作为增强相材料,制备玻璃纤维/SU-8复合材料。开发出一种既能够增强成型后SU-8微结构机械强度,又不影响SU-8可直接光刻成型能力的改性技术。通过光学显微镜和扫描电子显微镜(SEM)对该复合材料的微观结构进行了分析和表征。同时,利用拉伸实验对复合材料的机械性能进行测试。实验结果表明,在不改变紫外光刻电铸(UV-LIGA)的光刻-显影工艺特征的条件下该复合材料的弹性模量(1 613 MPa)、断裂伸长率(1.63%)和断裂强度(26.7 MPa)均比纯SU-8胶材料有较大提升。     

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。     

基于PDMS模具热模压制备微流控通道结构的方法

介绍了一种利用聚二甲基硅氧烷(PDMS)的快速成型来制备模具,再进行热模压制造微流控通道结构的方法。通过在硅片上旋涂SU-8胶进行光刻显影,得到结构模版,在此模版上浇注PDMS,脱模即得到PDMS模具。将PDMS模具进行热压,成功地在聚甲基丙烯酸甲酯(PMMA)基片上复制了特定的微流控通道结构。相对于常规的硅微加工和UV-LIGA工艺制造热模压模具,本方法具有加工周期短、工艺简单、成本低等优点。另外,还对温度、压力、时间等热模压的主要工艺参数进行了初步的优化研究。     

UV-LIGA双层微齿轮加工工艺研究

利用SU-8光刻胶UV—LIGA技术制备了双层微齿轮，齿轮单层的厚度可达450μm。制备中分别采用了三种工艺路线：两次电铸、溅射种子层一次电铸和直接一次电铸，均成功地制备出了双层微齿轮，并讨论了三种工艺路线各自的适用范围，即两次电铸工艺路线适用于对机械强度要求不高的各类多层微结构器件，一次电铸工艺路线适用于对机械强度要求较高的结构，其中溅射种子层工艺适用于深宽比较小的多层微结构模具，而直接电铸工艺适用于深宽比较大且层间直径相差较小的多层微结构器件。     

SU-8胶深紫外光刻模拟

综合了SU-8胶光刻过程中衍射、反射、折射、吸收率随光刻胶深度的变化及交联显影等各种效应,考虑了折射及吸收系数随时间的变化,建立了SU-8化学放大胶的光刻模型.模拟结果显示,该模型比现有的模拟方法结果更精确,与实验结果符合较好,可以在实际应用中对SU-8光刻胶的二维模拟结果进行有效预测.     

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.     

An Alternative Method for SU-8 Removal Using PDMS Technique

An alternative method for SU-8 removal is proposed.Instead of directly using SU-8 microstructure as the electroplating mold,a polydimethysiloxane (PDMS) replica is employed.The metallic micromold insert obtained through this method can be easily peeled off from the PDMS replica,meanwhile with high resolution and smooth surfaces.     

Fabrication and application of silicon-reinforced PDMS masters

A new molding process is developed in this work to generate a silicon (Si)-reinforced polydimethylsiloxane (PDMS) master of a 4 in wafer size using an SU-8 mold. The reinforced PDMS master is applied to pattern a conducting polymer, poly-3-hexylthiophene (P3HT), which is normally dissolved by a non-polar solvent. PDMS is usually patterned by a molding process, in which PDMS is first coated on and then peeled off from a rigid mold. However, in the new molding process, the Si-reinforced PDMS master is rigid but the SU-8 mold is flexible, and the SU-8 mold is first placed on and then peeled off from the rigid PDMS master. In such a way, a reinforced PDMS master of a size as large as a 4 in wafer can be produced. Meanwhile, a new way of obtaining free-standing, large SU-8 structures is presented. PDMS swells when it gets exposed to non-polar solvents. This swelling makes PDMS not suitable for patterning materials, which are usually dissolved by non-polar solvents, e.g., P3HT. In this work, we demonstrate that, with the reinforcement of a Si plate, the swelling effect in generating this specific type of materials is much reduced, and good patterns can be produced.     

PDMS多层次蘑菇形微结构的制作

提出了一种基于光刻胶牺牲层技术的用于制作多层次SU-8模具的新方法,并进一步采用浇注成型的方法制作了聚二甲基硅氧烷(PDMS)多层次蘑菇形微结构。在多层次SU-8模具的制作过程中,使用了正性光刻胶BP212作为牺牲层,并采用超声辅助显影的方法使显影的时间大大缩短。通过对多层次SU-8模具预处理,有效减小了多层次SU-8模具与PDMS的结合力,从而提高了PDMS脱模的成功率。对制作的PDMS多层次蘑菇形微结构和PDMS单层次微柱结构进行了接触角测试。结果表明,PDMS多层次蘑菇形微结构的接触角为150.93°±1.6°,PDMS单层次微柱结构的接触角为139.19°±0.1°。由此可知PDMS多层次蘑菇形微结构具有优异的超疏水性能。     

微型薄膜电阻的制备及研究

将具有优异特性的碳纳米管（CNTS）与负性感光胶（SU-8 2002）混合得到复合材料,将不同比例的碳纳米管通过超声工艺分散到SU-8 2002感光胶中,通过UV-LIGA加工工艺,热压处理后实现了微型电阻的快速制备。对复合薄膜电阻的性能进行测试,测试结果表明复合薄膜电阻率随着碳纳米管比例的增加而减小,当碳纳米管的比例为12%时,电阻率减小到0.06 ,复合材料达到逾渗阈值,频率小于1.2GHz时,电阻值的变化范围小于5%,为快速制备微型电阻提供了新的方法。     

Wet releasing and stripping SU-8 structures with a nanoscale sacrificial layer

This paper presents a new method of wet releasing SU-8 structures using very thin Omnicoat^™ as sacrificial layer and NMD-3 developer as releasing solution. Four-inch sized SU-8 structures with different pattern and thickness of 65 μm have been successfully released from silicon substrate by this method. Experiments show that Omnicoat^™ layer is very helpful to strip SU-8 molds in which metal structures are electroplated. SU-8 can be removed directly using remover if there is an Omnicoat^™ layer between the substrate and SU-8 and the electroplated structures is with large dimension. In the case of electroplated structures with small feature size, SU-8 can be removed by combining wet stripping and plasma etching. Nickel micro coils with linewidth of 10 μm and aspect ratio of 4.1 have been fabricated. The analysis about the influence of Omnicoat^™ layer’s thickness on integrity of SU-8 micro coils is also given in our work.     

Soft-lithographic methods for the fabrication of dielectrophoretic devices using molds by proton beam writing

Proton beam writing (PBW) was applied to the fabrication of dielectrophoretic (DEP) devices equipped with high-aspect-ratio pillar arrays. With coupled use of soft lithography for micro-fluidic channels, we successfully fabricated a device equipped with SU-8 pillar arrays produced by PBW, which is covered with a poly-dimethylsiloxane (PDMS) micro-fluidic channel. For more simplified prototyping of the device, we modified a SU-8 mold for simultaneous replication of both pillar arrays and micro-fluidic channel on PDMS. Replication of pillar arrays is limited to the aspect ratio of less than three.