改善硅基螺旋电感品质因数的厚铝膜干法刻蚀

提出了一种用于改善硅基螺旋电感品质因数的厚铝膜干法刻蚀技术;这种技术利用氧化硅和光刻胶双层复合掩模来掩蔽厚铝的干法刻蚀,完全兼容于CMOS工艺;应用于双层铝布线,实现了最大厚度达到6μm的顶层铝,显著地减小了螺旋电感的串联电阻,提高了品质因数;该技术同高阻SOI衬底技术相结合,制造的10nH螺旋电感的最大品质因数达到8.6。     

抗蚀剂AZ4562曝光参数的变化趋势分析

针对厚胶曝光参数随不同光刻胶厚度及工艺条件变化的特点,在原有Dill曝光模型基础上,建立了适合于描述厚胶曝光过程的增强Dill模型,并将统计分析的趋势面法引入到厚胶曝光参数变化规律的研究中,给出了厚胶AZ4562曝光参数随胶厚及工艺条件的变化趋势,为开展厚胶光刻实验研究和曝光过程模拟提供指导性依据。     

Fabrication of a 100%fill-factor silicon microlens array

正A simple method has been developed for the fabrication of a silicon microlens array with a 100%fill factor and a smooth configuration.The microlens array is fabricated by using the processes of photoresist(SU8- 2005) spin coating,thermal reflow,thermal treatment and reactive ion etching(RIE).First,a photoresist microlens array on a single-polished silicon substrate is fabricated by both thermal reflow and thermal treatment technologies. A typical microlens has a square bottom with size of 25μm,and the distance between every two adjacent microlenses is 5μm.Secondly,the photoresist microlens array is transferred to the silicon substrate by RIE to fabricate the silicon microlens array.Experimental results reveal that the silicon microlens array could be formed by adjusting the quantities of the reactive ion gases of SF_6 and O_2 to proper values.In this paper,the quantities of SF_6 and O_2 are 60 sccm and 50 sccm,respectively,the corresponding etch ratio of the photoresist and the silicon substrate is 1 to 1.44.The bottom size and height of a typical silicon microlens are 30.1μm and 3μm,respectively. The focal lengths of the microlenses ranged from 15.4 to 16.6μm.     

SiO2 single layer for reduction of the standing wave effects in the interference lithography of deep photoresist structures on Si

We demonstrate that the use of a single SiO₂ film, with thickness corresponding to one standing wave (SW) period allows the recording of deep photoresist structures on silicon substrates by laser interference, without use of any additional antireflecting coating. This condition corresponds just to the opposite thickness (half SW period) previously proposed for using the SiO₂ films for phase-shifting the SW pattern. Theoretical and experimental results demonstrated that for the lithography of deep structures, the contrast of the SW pattern, the minimum light intensity of the SW pattern and the photoresist adhesion are the most important parameters of the process.     

Formation of silver and zinc selenide relief patterns by the lift-off photolithography method

Conducting the lift-off photolithography on silicon wafers with thicknesses of the FP-383 photoresist layers varying from 1.60 ± 0.20 to 4.20 ± 0.20 μm is considered. As a lift-off layer, either a silver layer or zinc selenide layer with a thickness of 80–90 nm was deposited. The edge roughness of the image elements after the lift-off is 5.00 ± 0.20 μm.     

Analysis of an octagonal micromachined horn antenna forsubmillimeter-wave applications

An analysis is presented of a new horn antenna, fabricated by a novel micromachining technique, that uses crystallographic etching of silicon and ultraviolet lithography of an ultra-thick photoresist (SU-8). The horn was found to have low cross-polarized field levels and a predicted Gaussian coupling efficiency of 92.5%. The horn shape is governed by the crystal planes of the silicon substrate and the thickness of the photoresist and has up to four independent design parameters that allow a wide range of antenna patterns. A design for the horn that yields symmetric beam patterns was investigated by computer analysis, microwave scale modeling, and measurements of a micromachined horn at 585 GHz. The major features of the 585-GHz beam patterns agree well with the computer-generated and scaled beam patterns. We have thus demonstrated a new micromachinable horn that has great potential for integration into array structures     

Optical lithography

This is the first in a series of papers describing a theoretical process model for positive photoresist. This model, based upon a set of measurable parameters, can be used to calculate the response of photoresist to exposure and development in terms of image surface profiles. The model and its parameters are useful in many ways, from measuring quantitative differences between different resist materials to establishment of process sensitivities and optimization of the resist process within a manufacturing system. In this paper, the concepts of photoresist modeling are introduced by following the exposure and development of a photoresist film on silicon exposed by a uniform monochromatic light flux. This very simple example provides insight into the complex nature of the photoresist process for reflective substrates. The accompanying paper, "Characterization of Positive Photoresists," gives detail about measurement of the new photoresist parameters. It is supported by "In-Situ Measurement of Dielectric Thickness During Etching or Developing Processes" which discusses automated experimental techniques needed to establish photoresist development rates. These resist parameters provide a complete quantitative specification of the exposure and development properties of the resist. They also allow quantitative comparisons: lot to lot, material to material, and processing condition to processing condition. The fourth paper, "Modeling Projection Printing of Positive Photoresists," applies the process model to one technique of photoresist exposure. This paper contains the detailed mathematics of the model. The model is then used to calculate line-edge profiles For developed resist images.     

Micro/nano-heater integrated cantilevers for micro/nano-lithography applications

This paper describes an array of micro/nano-heater-integrated cantilevers for micro- and nano-lithography applications. In the scanning thermal cantilever, as the electrical current flows through the cantilever with a conductive tip, electrical power is dissipated mainly within the tip area, and this dissipation raises the local temperature around the tip area. When the thermal power is applied to a thin photoresist film, spin-coated on silicon wafers or mask substrates, more than 90% of solvents involved in the photoresist starts to evaporate from the layer. Hence, the exposed areas can resist commercial developers during the development process. Patterning speed has been improved by employing an array of heaters with various sizes. The novel concept of the SPM-based nano-lithography has been successfully demonstrated by application on the fabricated cantilevers and a commercial SPM system.     

Characterization of platinum films produced by UV exposure of a novel photosensitive organometallic material

A novel process is presented which produces platinum features using direct UV exposure of the photosensitive organometallic material. The technique reduces the number of process steps involved when creating a metal pattern on a substrate by not requiring photoresist, solvents, or etch processes. In contrast to processes already reported in the literature, the method is compatible with microelectronic processes and does not require costly special equipment. Two test chips with MOS capacitors and resistive structures fabricated using the new organometallic material have been characterized. The results show that the deposited films are metallic and have a good adhesion to silicon dioxide. The work function of the platinum films is in agreement with the value found in the literature, but the measured resistivity and XPS indicate that the metal film contains some remaining organometallic residue after pattern development.     

Acoustically actuated flextensional Si/sub x/N/sub y/ and single-crystal silicon 2-D micromachined ejector arrays

We propose using two-dimensional (2-D) micromachined droplet ejector arrays for environmentally benign deposition of photoresist and other spin-on materials, such as low-k and high-k dielectrics used in IC manufacturing. Direct deposition of these chemicals will reduce waste as well as production cost. The proposed device does not harm heat or pressure sensitive fluids and they are chemically compatible with the materials used in IC manufacturing. Each element of the 2-D ejector array consists of a flexurally vibrating circular membrane on one face of a cylindrical fluid reservoir. The membrane has an orifice at the center. A piezoelectric transducer generating ultrasonic waves, located at the open face of the reservoir, actuates the membranes. As a result of this actuation, droplets are fired through the membrane orifice. Ejector arrays were built with either Si/sub x/N/sub y/ or single-crystal silicon membranes using two different fabrication processes. We show that single-crystal silicon membranes are more uniform in their thickness and material quality than those of Si/sub x/N/sub y/ membranes. The single-crystal silicon membrane-based devices showed thickness and material uniformity across all the membranes of an array. This improvement eliminated nonuniform membrane resonance frequencies across an array as observed with Si/sub x/N/sub y/ membrane-based devices. Therefore, it should be possible to repeatably build devices and to predict their dynamic characteristics. Using the fabricated devices, we demonstrated water ejection at 470 kHz, 1.24 MHz, and 2.26 MHz. The corresponding droplet diameters were 6.5, 5, and 3.5 /spl mu/m, respectively.     

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.     

丙烯酸酯干膜光刻胶曝光特性及其应用

对一种新型的丙烯酸酯干膜光刻胶(DFP)的曝光及显影特性进行了研究,采用该干胶制作出微沟道结构,进行微流道实验研究。在4英寸(1英寸=2.54cm)硅片上实现了厚度为50μm的干胶完好贴敷,从而解决了干胶在硅衬底上的贴敷问题。利用改变曝光时间设定曝光剂量梯度的方法,研究了干胶的曝光特性。采用不同质量分数的显影液,研究干胶的显影特性,获得了优化的结果。采用干胶系统进行了微流体沟道制作,得到了侧壁陡直的微沟道结构。实验发现,65mJ/cm2及以上的曝光剂量可使厚度为50μm的干膜光刻胶充分曝光并获得形貌效果良好的微结构,质量分数为5%的显影液具有最快的显影速度。     

New applications of low temperature PECVD silicon nitride films for microelectronic device fabrication

Silicon nitride has been widely used in microelectronic device fabrication processes for encapsulation, surface passivation and isolation. In this paper we report new applications of plasma-enhanced chemical vapor deposition (PECVD) silicon nitride films that can be deposited at a temperature lower than the soft bake temperature of normal photoresists. Lift-off of the silicon nitride film was carried out using standard positive photoresist. GaAs MESFETs and InP MISFETs with self-aligned gates were successfully fabricated using this lift-off process of low temperature PECVD silicon nitride.     

A novel in-line automated metrology for photolithography

Novel metrology has been developed for measuring in situ film thickness and absorption coefficient simultaneously. Designed specifically for photolithography processes, this metrology if applied to photoresist films, can measure thickness and photoactive compound concentration in situ, which are important parameters for photolithography process control and diagnosis     

Investigation into the processes of plasmachemical etching of a photoresist with the help of in situ optical monitoring

The peculiarities of photoresist etching in inductively coupled plasma in various modes, including the mode using to etch the GaN-based structures are investigated. The continuous in situ monitoring of the photoresist thickness, surface morphology, and substrate temperature was performed with the help of the optical reflectometry and low-coherent interferometry. It is shown that the etch rate of photoresist is not constant but decreases in the course of the process, which is in addition associated with the substrate heating. It is revealed that the pulsed etching mode makes it possible to exclude the development of the roughness observed in the continuous mode. The comparison of the new data with the etch rates of the photoresist with the characteristic rates of GaN etching performed under the same conditions made it possible to determine the process parameters and photoresist thickness necessary to perform the mentioned etching process in the optimal mode.     

全息光栅掩模制备中的光刻胶薄膜特性控制研究

本文对全息光栅掩模制备中光刻胶薄膜的应力与厚度均匀性问题进行了研究。应用干涉法及Stoney公式计算的分析结果,对SiO2基底上光刻胶薄膜的应力进行了研究。对膜厚的均匀性采用干涉显微镜在同一样品,不同直径上多点测量的方法,初步得出光刻胶薄膜膜厚均匀性的分布规律。分组变换加速度,转速,匀胶时间等参数,并对结果进行比较,发现在匀胶转速相同的前提下,光刻胶薄膜应力值随加速度的降低面减小,光刻胶薄膜的均匀性随加速度的增加而变好。在3000rpm至4000rpm的低转速时,光刻胶薄膜样品的膜厚均匀性好。出此,在全息光栅匀胶工艺中,要选择适当的转速的加速度,以得到应力较小和均匀性较好的光刻胶薄膜。与此同时,薄膜膜厚均匀性呈现出中间薄,边缘较厚的规律。     

Polymeric silicon-containing resist materials

Silicon-containing bilayer and trilayer photoresist technology is reviewed. Multilayer resist processes of this type rely on pattern generation in a thin imaging layer followed by pattern transfer to the thick planarising underlayer by oxygen reactive ion etching (RIE). The review concentrates on materials in which the silicon is an integral part of the polymer and does not specifically address photoresists where silicon is incorporated in a post-imaging process step (Such as top-surface-imaging resists). The review is not exhaustive but emphasizes instead specific examples of representative resist chemistry.     

Properties of a high resolution negative photoresist

The recent advantages in designing large and very large integrated circuits have imposed stringent requirements on the processes used in the production of semiconductor devices. The requirements on photoresists have been increased not only with regard to improved exposure tools but also in view of other process steps such as plasma etching, ion implantation, etc. A new developed negative photoresist, Selectilux N, combines the well-known advantages of a cyclized polyisoprene-based resist with the capability to resolve features in the 1 to 2 micron range and a high thermal stability. The main properties are: high photospeed to reduce the influence of oxygen and to prevent thickness loss, high contrast to achieve good resolution in projection exposure, low flow distortion up to 240 C to ensure good image stability, low swelling during the development to prevent reduction of the resolution. Photospeed and contrast can be derived from the characteristic curve of Selectilux N which is obtained by the determination of the remaining thickness of the resist vs exposure energy.     

基于制作COF精细线路的液态光致抗蚀液性能研究

卷对卷丝网印刷机在超薄挠性覆铜箔层压板上丝网印刷液态光致抗蚀液,实现COF精细线路的制作。研究了液态光致抗蚀液的感光性能与分辨率力等性能,考察了制作出COF的线路效果。实验结果表明,液态光致抗蚀液网印的针孔数随厚度的减小而增加,液态光致抗蚀剂曝光级数随曝光能量的变化趋势与干膜是一致的,11μm厚液态光致抗蚀剂分辨的最小线路宽达到25μm,满足COF精细线路制作的要求。     

AFM investigation of thin post-baked photoresistive films for microsystem technology application

In this paper, we discuss the application of photoresist films as the sacrificial layers for “bridge” working elements in microsystem technology. Different regimes and conditions of post-baking and plasma chemical etching processes for the formation of sacrificial layers with precise thickness and roughness are investigated. The photoresist surface morphology was observed with the help of atomic force and scanning electron microscopy. The text was submitted by the authors in English.