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.     

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。     

铁芯和空芯螺线管型微电感器的性能比较

为了满足RF电路、电源电路、微执行器和微传感器等领域对高性能和工艺简单的电感器的广泛需求，用正、负胶结合的微加工工艺，在硅基片上制作了有坡莫合金铁芯的和在玻璃基片上没有铁芯的、其它结构和参数均相同的两种螺线管型微电感器，测试了它们在1－40MHz频率范围的电感、电阻和Q因子，并进行了比较和讨论。其结果与现有理论知识相一致。实验证明了具有坡莫合金铁芯的螺线管型微电感器在低于30MHz的频率下使用更有意义。而无铁芯螺线管型微电感器还可以用于更高频率的场合。     

用SU-8胶制高深宽比微结构的试验研究

SU-8胶是一种负性、环氧树脂型、近紫外线光刻胶，它适于超厚、高深宽比的MEMS微结构制造。但SU-8胶对工艺参数很敏感。采用正交试验设计方法对其工艺进行分析。采用三个因素进行试验，对试验进行了分析。以200μm厚的SU-8为例进行试验研究，得到光刻胶图形侧壁陡直，分辨率高，与基底附着性能，深宽比大于20。     

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。     

多层复杂结构准LIGA一体化加工工艺的研究

准LIGA加工工艺通常只能加工单层准三维体。本研究采用SU-8胶准LIGA技术，解决了多层套刻、种子层和表面活化等技术难题，加工出了三维五层一体化复杂结构。实践证明，所提出的工艺实际可行，进一步拓展了准LIGA工艺的应用。     

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。     

间歇悬浮式厚胶显影工艺研究

介绍了一种间歇悬浮式厚胶显影工艺,采用该种显影工艺,对使用SU-8光刻胶进行涂胶,胶层厚度大于30μm的晶片进行显影。显影后的晶片进行电镀工艺,经过对显影后晶片上图形的观察和对电镀凸点的分析,证明该种显影工艺具有很好的效果。     

射频同轴传输线的设计仿真与加工工艺

基于SU-8和BPN紫外负性感光胶,结合微电镀工艺加工制作射频同轴传输线,以实现射频器件信号的传输与耦合。首先确定在阻抗匹配情况下同轴传输线特性阻抗为50Ω的同轴传输线的具体尺寸,然后通过HFSS仿真软件对设计的结构进行模拟仿真。通过仿真结果验证设计的可行性,采用紫外光刻技术利用SU-8光刻胶做出内导体支柱,并用BPN光刻胶做出结构,对结构进行电镀。最后将BPN光刻胶剥离,即可得到射频同轴传输线。此方法制得的同轴传输线具有介质损耗小、辐射损耗小、无色散、带宽大和抗干扰强的优点,适用于高性能射频和微波电路。另外,它的制作工艺能与其他射频和微波器件及集成电路工艺兼容,便于与射频和微波电路集成。     

Development of RF/microwave on-chip inductors using an organic micromachining process

The design and development of a micromachined spiral inductor using an organic micromachining process are presented. The process utilizes an ultra-thick negative photoresist SU-8 to elevate an inductor structure above a substrate. The micromachined inductors have been designed and fabricated on solid and hollow ground planes to, investigate the feasibility for achieving high Q-factors. The experimental results demonstrate that a micromachined inductor integrated on a Si substrate achieves a Q-factor of 19.3 at 2.1 GHz.     

Intermediate wafer level bonding and interface behavior

The paper presents a new silicon wafer bonding technique. The high-resolution bonding pad is defined through photolithography process. Photosensitive materials with patternable characteristics are served as the adhesive intermediate bonding layer between the silicon wafers. Several types of photosensitive materials such as SU-8 (negative photoresist), AZ-4620 (positive photoresist), SP341 (polyimide), JSR (negative photoresist) and BCB (benzocylbutene) are tested and characterized for their bonding strength. An infrared (IR) imaging system is established to examine the bonding results. The results indicate that SU-8 is the best bonding material with a bonding strength up to 213 kg/cm² (20.6 MPa) at bonding temperature less than 90 °C. The resolution of bonding pad of 10 μm can be achieved. The developed low temperature bonding technique is particularly suitable for the integration of microstructures and microelectronics involved in MEMS and VLSI packaging processes.     

Negative UV–NIL (NUV–NIL) – A mix-and-match NIL and UV strategy for realisation of nano- and micrometre structures

This paper presents a novel strategy for aligning patterns created with nano-imprint lithography (NIL) and UV lithography, similar to a mix-and-match process, which allows for the fabrication of large and small features in a single layer of resist. The resin used to demonstrate this new imprinting scheme is SU-8, a very widely used negative photoresist. Rapid stamp manufacturing using ma-N 2405 photoresist is also demonstrated. The processing scheme is a promising candidate for patterning of sensors featuring nanometre sized electrodes.     

先进封装和MEMS应用的超厚抗蚀剂光刻技术(英文)

微电子机械系统(MEMS)制造和先进的封装技术更需要厚抗蚀剂层。在MEMS应用领域包括体硅微机械加工、表面微机械加工和有源器件结构的实际制作。对先进的封装技术,应用再分布和蚀化层以及金属焊凸微成型。各种用途要求抗蚀剂厚度能达到和超过1000μm。为适当地获得这些厚度,制造商开发了适当的涂层材料。这些材料包括AZP4620.ShipleySPR220\AIPLP100XT、JSRTHB611P和SU-8。最终开发了处理这些材料的设备,制作了专用的涂胶设备和接触?接近式曝光机。     

Experimental study on ultrasonic stress relief for cured SU-8 photoresist layer

The purpose of this work is to reduce the internal stress in cured SU-8 photoresist layer by ultrasonic stress relief technology. The stress relief mechanism of SU-8 photoresist layer was presented. Based on improved Stoney’s formula, a theoretical calculation model for SU-8 internal stress was proposed. Profile method was used to measure the curvature radius of substrate. The effect of ultrasonic stress relief on SU-8 layers was studied by experiments. Meanwhile, some important factors, such as amplitude of vibration, power input and relief time, have been discussed. The values of internal stress before and after the ultrasonic stress relief process were compared. The experimental results show that the internal stress in cured SU-8 layers can be effectively reduced if the proper experimental parameters are chosen.     

Fabrication and characterization of a planar interleaved micro-transformer with magnetic core

This paper presents the design, the fabrication and the characterization of a planar interleaved micro-transformer with an Yttrium Iron Garnet (YIG) core. The design of this micro-transformer and the manufacturing steps are presented. HFSS software is used for the conception and the simulation of the interleaved magnetic micro-transformer. It is composed of two identical windings. A bottom magnetic core is used to improve the integrated transformer performances. To form the windings, we have used a surface micromachining process. We have also used a negative photoresist (SU-8) as an insulating layer and as support for the fabrication of a bridge to connect the central end of the coils to the ground shield. The micro-transformer have been characterized with impedance meter up to 100 MHz, and completed to 1 GHz using vector network analyzer.     

Pattern transfer of microstructures between deeply etched surface for MEMS applications

Photolithography plays a vital role in micromachining process however; coating a thin and uniform resist layer on a non-planar surface is a challenging task for micro-electro-mechanical system (MEMS). Conventional spin coating of photoresist (PR) over an un-even surface would deliver streaks all over the wafer surface. Spray coating of PR is a promising technique when compared to other candidates. This paper presents an efficient pattern transfer of microstructures between the bulk micromachined cavities over silicon and glass wafers using an uncommon photoresist mixture being spray coated. The method is simple and highly cost effective. Finally we implemented this technique for a MEMS application to prove the feasibility of spray coating for microstructure fabrication.     

Development of low loss organic-micromachined interconnects on silicon at microwave frequencies

We present the design and development of an ultra-violet (UV) LIGA (a German acronym for electroplating, lithography and molding) micromachining process on silicon substrates at microwave/millimeter wave frequencies. The process employs an ultra-thick negative photoresist SU-8 that can be spin-coated and processed using conventional lithography techniques. Using this process, we have developed micromachined coplanar waveguide (CPW) interconnects on Si substrates. The conductor-backed micromachined CPW on Si (7.2 /spl Omega/-cm) achieves a measured attenuation of 0.18 dB/cm at 20 GHz.