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Ordered nanoarchitectures have attracted an intense research interest recently because of their promising device applications. They are always fabricated by self-assembling building blocks such as nanowires, nanodots. This kind of bottom up approaches is limited in poor control over height, lateral resolution, aspect ratio and patterning. Here, we break these limits and realize 3D sculpturing of vertical ZnO nanowire arrays (NAs) based on the conventional photolithography approach. These are achieved by immersing nanowire NAs in thick photoresist (PR) layers, which enable the cutting and patterning of ZnO NAs as well as the tailoring of NAs. Our strategy of 3D sculpturing of NAs promisingly paves the way for designing novel NAs-based nanoarchitectures.

Fast marching method is an accurate, extremely fast numerical technique in analyzing and computing moving fronts which can develop sharp corners and change topology. We successfully accomplish this method in two dimensions and the two-dimensional lithography process simulation of SU 8 photoresists has been implemented. The obtained results indicate that the fast marching method can actually accelerate the simulation and be used as an effective method for thick photoresist lithography process simulations.

In this work, the design and fabrication of a low f-number cylindrical microlens array is presented. The lenses were fabricated in thick photo resist of 12 μm thickness, using a contact printer exposure through a mask with a repetitive 6 μm line - 4 μm space pattern. Numerical calculations based on scalar diffraction theory were employed to model the light propagation inside the resist, determining the aerial image as a function of its thickness. Than the resist response characteristics, expressed by its contrast curve, and absorption rate were used to obtain a cross section profile. A good match between numerical and experimental results were found.

This work suggests a simple method to flatten thick layers (similar to 50-200 mu m) of SU-8 photoresist on small substrates (similar to 1 cm). The method sidesteps the edge beads problem and enables photolithography patterns up to the substrates' edges. Moreover, the method can be used even for substrates with large aspect ratios when the spin coating is largely impossible.

Fabrication of tall features using selective electrodeposition is well known process and has several applications in microelectronics packaging. The use of conventional exposure and development processes is limited by the aspect ratio and sizes of the features obtained. This paper describes a novel approach to fabricated tall structures featured in thick photoresist . Tin and copper tall structures were made by selective electrodeposition. Also presented are results from experiments performed to fabricate tall tin and copper pillars with nearly vertical walls on bare dices to form interconnect.

Digital Micromirror Device (DMD)-based grayscale lithography is a promising tool for three dimensional (3D) microstructuring of thick-film photoresist since it is a maskless process, provides possibility for the free-form of 3D microstructures, and therefore rapid and cost-effective microfabrication. However, process parameter determination lacks efficient optimization tool, and thus conventional look-up table (indicating the relationship between development depth and exposure dose value under a fixed development time) approach with manual try-and-error adjustment is still gold standard. In this paper, we firstly present a complete “input target-output parameters” single exposure optimization method for 3D microstructuring utilizing DMD-based grayscale lithography. This numerical optimization based on lithography simulation and sensitivity analysis can automatically optimize a combination of three process parameters for target microstructure; exposure dose pattern, a focal position, and development time. Through a series of experiments using a 20 μm thick positive photoresist, validity of the proposed optimization approach has been successfully verified. Secondly, with the purpose of further advancing accuracy and improve the uniformity of precision for the target area, a multiple exposure optimization method is proposed. The simulated results proved that the multiple exposure optimization method is a promising strategy to further improve precision for thicker photoresist structure.

This research is on the development of a micro variable optics array which employs electrowetting as the working principle. The single pixel of the array has four separated electrodes and each of them is controlled independently giving the device multi-degree of freedom. The separated electrodes are fabricated using a thick photoresist and electroplating. Several formulas showing the relation among the radius of curvature, the prism angle, and electrowetting parameters are provided. The prism angles are measured to be ±30° and compared to the calculated values. The measurement of the radius of curvature is also presented showing that the various radiuses of curvature are achievable from concave to convex.

The high energy retrograde well implants for sub-0.18 microns CMOS are done at a normal or near normal incidence to minimize the shadowing due to the thick photoresist edges. The endstation geometry in a high energy implanter results in an incident angle variation across the wafer, which causes strong spatial variations in the well profile and can negatively impact device performance. We show that the spatial variations can have significant impact on shallow trench isolation (STI), by causing in a deterministic pattern the failure of STI devices on a wafer. These spatial variations are important and need to be taken into consideration for STI design.

Interest in thick photoresist applications is steadily growing. Specialised equipment has been developed to cope with the new challenges to process and pattern extremely thick photoresist layers. A decisive step in the preparation of resist layers is the prebaking. The impact of three different prebaking technologies on the resist performance has been investigated. Resist patterns obtained after oven, hotplate or IR prebaking exhibit equal high quality. Compared to oven and hotplate baking the process length and energy consumption is markedly reduced using IR radiation favouring this variant to be the optimum prebaking process for very thick photoresist layers.

Advanced mask aligner lithography (AMALITH) is a holistic approach to improve shadow printing (contact and proximity lithography) in mask aligners. AMALITH is based on two tools, the MO Exposure Optics®, a new illumination system allow shaping the angular spectrum of the illumination light, and LAB, a software tool for full 3D simulation of the shadow printing process. MO Exposure Optics® is provided by SUSS MicroTec AG ( http://www.suss.com ), as an upgrade for all current and older mask aligner models. MO Exposure Optics® decouples the illumination from lamp misplacement (self-calibrated light source), improves the light uniformity, provides telecentric illumination and enables customized illumination in mask aligners. LAB is a software tool provided by GenISys GmbH ( http://www.genisys-gmbh.com ), and allows simulating the complete chain from illumination, mask pattern, photoresist and resist processing. The combination of both tools allows optimizing mask aligner lithography beyond today's limits.

Current photospeed testing methods are based on dose to clear (E 0 ) or resist contrast (γ 10 ). Either method is inadequate for controlling sensitivity to within ±1.5%. We investigated various methods for improving these photospeed tests. Ranked in order of decreasing importance are: (i) controlling standing waves (reflectivity); (ii) choice of developer, (iii) develop time; and (iv) exposure pattern. Reflectiuty can be controlled by careful attention to resist thickness, addition of a bottom antireflective layer, addition of a low refractive index layer (AquaTar), or by using a thick photoresist. Moreover, we can utilize the whole dissolution curve rather than the one-point determination of the E 0 test

A new self-aligned offset staggered polysilicon thin-film transistor (poly-Si TFT) has been proposed and demonstrated to have a suppressed leakage current. For the self-aligned offset structure, planarization with thick photoresist and etchback of photoresist are successfully utilized. The offset length can be easily controlled by the thickness of the gate material without photolithographic limitation. In the self-aligned offset polysilicon TFT's, the leakage current decreases with an increasing offset length.

In this study, a novel packaging structure for open-channel sensor was successfully demonstrated by using the sacrifice-replacement method. This method was patterned JSR THB-151N photoresist to fabricate an open space to contact medium. The sacrificial-barriers of 75 and 150 mum thickness have been fabricated with good reproducibility by using single and double coating processes. Optimized fabrication parameters were achieved straight and nearly vertical sidewall profiles. In addition, after the encapsulation process, JSR photoresist has been stripped clearly and easily without residues in stripper solutions. Finally, the sensing channel was reserved in packaging body resulting from sacrifice-replacement approach.

In this study, we propose and evaluate a novel low-auto-fluorescence photoresist (SJI photoresist) for bio-application, e.g., in gene analysis and cell assay. The spin-coated SJI photoresist has a wide thickness range of ten to several hundred micrometers, and photoresist microstructures with an aspect ratio of over 7 and micropatterns of less than 2 μm are successfully fabricated. The emission spectrum intensity of the SJI photoresist is found to be over 80% less than that of the widely used SU-8 photoresist. To evaluate the validity of using the proposed photoresist in bio-application for fluorescence observation, we demonstrate a chromosome extension device composed of the SJI photoresist. The normalized contrast ratio of the SJI photoresist exhibits a 50% improvement over that of the SU-8 photoresist; thus, the SJI photoresist is a versatile tool for bio-application.

Lithography technology for advanced packaging is quite different from that for other applications. Because the applications of WLP and wafer bumping often require lithography system to define bumping-array patterns across the wafer or to create redistribution a layers or integrated passive devices with resist lagers of thick (20-100/spl mu/m) and feature sizes large (2-150/spl mu/m). At the same time, the package process is extremely cost-sensitive and requires nearly perfect yield with very thick photoresist and photopolymer layers as presented in J. Hermanowski (2004). In this paper, we would like to introduce a lithography system with low-COO and high performance, it can meet and allow the requirements of advanced packaging.

The present study provides a novel carrier fabrication method for biomedical application. The SU-8 thick photoresist fabrication process is used to produce the /spl mu/-carrier of 200 /spl mu/m/spl times/200 /spl mu/m with various thicknesses. These /spl mu/-carriers will be used for the purpose of biomedical inspection after proper surface modification by chemicals. To quantify and qualify the immersed /spl mu/-carriers in the inspected solution, specific marker is designed and fabricated on every /spl mu/-carrier as identification according to the application. Hence, a precise control on the marker feature dimension will be crucial for the application. In addition, the thick resist layer uniformity is very important in defining the marker pattern on the surface of carrier. Besides, the sidewall profile is also crucial especially for the fabrication of 10 /spl mu/m through-hole markers on the carriers of 50 /spl mu/m to 100 /spl mu/m thick. The orthogonal array experimental design method is employed to optimize the process parameters, including the soft bake, exposure, postexposure bake, and development parameters. Moreover, the effect of development with ultrasonic agitation is also investigated.

Combination of plasma and wet etching was done in developing a new silicon depth-probe type microelectrode array. The plasma etch uses low temperature oxide (LTO) mask instead of thick photoresist mask, and enables the thickness of the probe shank to be defined more freely and in wider range. The entire probe shaping process was performed only at low temperature, and is CMOS compatible. A probe with 30 /spl mu/m shank thickness was successfully used in recording from rat's somatosensory cortex. A four-channel simultaneous neural recording shows signal-to-noise ratio performance comparable with that obtained using conventional microprobes.

The retrograde well implants for sub-0.18 /spl mu/m CMOS are done at a normal or near-normal incidence to minimize shadowing due to the thick photoresist edges. The endstation geometry in the high energy implanter results in an incident angle variation across the wafer, which causes strong spatial variations in the well profile and can negatively affect device performance. We show that the spatial variations can have significant impact on shallow trench isolation (STI), latchup immunity, well resistance and capacitance. The spatial variations can cause in a deterministic way the failure of a large number of isolation structures on a single wafer.

The design and biocompatibility testing of batch fabricated micromachined pipette arrays is described. The process used to fabricate the metallic micromachined pipette arrays (MPA) includes p/sup +/ etch-stop membrane technology, anisotropic etching of silicon in potassium hydroxide, sacrificial thick photoresist micromolding technology, and micro electroforming technology. Arrays of one to ten pipettes have been fabricated using nickel as the structural material and gold as the biocompatible coating of inside walls. The inner dimensions of the individual pipettes fabricated to date range from 30 /spl mu/m to 1.5 mm in width, 0.5 mm to several cm in length, and 5 /spl mu/m to 50 /spl mu/m in thickness. The micromachined pipettes have many advantages over current micro pipette technology, including: (a) highly parallel manipulation of samples/reagents, (b) the capability to precisely define the pipette dimensions allowing for small volumes (in pL to /spl mu/L range), and (c) a wide range of pipette center-to-center spacings (from centimeters to approximately 20 /spl mu/m).

The feasibility of controlling the sidewall angle of thick benzocyclobutene (BCB) etched in a CF4∕O2 plasma using thick photoresist as an etch mask has been investigated. Sidewall angle, BCB etch rate, and BCB to photoresist selectivity as functions of chamber pressure and CF4 to O2 ratios are reported. Through the use of postdeveloped reflown photoresist, an optimum sidewall angle of less than 60° was achieved at 33mT chamber pressure and a 19% CF4∕O2 ratio. The method presented here achieves deep, residue-free etching of thick BCB with a sidewall profile suitable for e-beam evaporated and lifted metal for use in vertical interconnects.

The fabrication of photoresist gratings is considered. A solution to the problem of ‘transversal standing waves’ is given and appears simple and versatile.

Description de la gravure reactive par ions oxygene en technologie planaire d'une couche de photoresist dans un systeme de resist a 3 couches. Vitesses d'attaque verticale et laterale et degre d'isotropie du profil. Les spectres d'emission optique du plasma d'oxygene revelent la presence d'atomes O et de molecules ionisees O 2 + . Le degre d'isotropie resultant de variations de la puissance RF et de la pression d'oxygene peut etre determine en controlant le rapport des intensites d'emission de O/O 2 +