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A cell culture on a scaffold has the advantages of functionality and easy handling, because the geometry of the cellular tissue is controlled by designing the scaffold. To create complex cellular tissue, scaffolds should be complex two-dimensional (2D) and three-dimensional (3D) structures. However, it is difficult to fabricate a scaffold with a 2D and 3D structure because the shape, size, and fabrication processes of a 2D structure in creating a cell layer, and a 3D structure containing cells, are different. In this research, we propose a micropatterning method for porous materials using the difference of the glass transition temperature between exposed and unexposed areas of a thick-photoresist. Since the proposed method does not require a vacuum, high temperature, or high voltage, it can be used for fabricating various structures with a wide range of scales, regardless of the materials used. Additionally, the patterning area can be fabricated accurately by photolithography. To evaluate the proposed method, a membrane integrated scaffold (MIS) with a 2D porous membrane and 3D porous material was fabricated. The MIS had a porous membrane with a pore size of 4 &mu, m or less, which was impermeable to cells, and a porous material which was capable of containing cells. By seeding HUVECs and HeLa cells on each side of the MIS, the cellular tissue was formed with the designed geometry.

This paper presents a fabrication of extremely thick SU-8 photoresist process in a height range Of $\mathbf{1000}\ \mu \mathbf{m}$ to $\mathbf{2000}\ \mu \mathbf{m}$ high-aspect-ratio microstructures. To differentiate conventional high-aspect-ratio tall structures less than $\mathbf{1000}\ \mu \mathbf{m}$, a new term, microtower, was adopted for the microstructure with a height of $\mathbf{1000}\ \mu \mathbf{m}$ or taller. In fabrication process, to avoid a long softbaking process from the thick photoresist and provide uniform film thickness, an SU-8 dry film was adopted. Ultra-violet (UV) light exposure with an acrylic filter was investigated in terms of transparency of the applicable wavelength spectrum. An array of the $\mathbf{1000}-\mu \mathbf{m}$ tall microtower array was fabricated without the acrylic filter resulting in wavy sidewalls. Whereas an array of $\mathbf{2000}-\mu \mathbf{m}$ tall microtower was fabricated with the acrylic filter resulting straight sidewalls. An array of $\mathbf{1500}-\mu \mathbf{m}$ -long inclined V-pillars was also successfully fabricated by adopting the UV exposure with the acrylic filter, and the fabricated microstructures have potential use as a microfilter in microfluidics. A state-of-art 100-turn toroid inductor was successfully fabricated and electrically characterized resulting an average inductance of 950 nH in the frequency range of 0.1 to 10 MHz. A low-frequency resistance of $\mathbf{5.4}\ \Omega$ at 0.1 MHz and a quality factor of 22 at 60 MHz were measured.

A major breakthrough in UV-LIGA (Lithographie, Galvanoformung and Abformung) started with the use of epoxy-based EPON® SU-8 photoresist in the mid-1990s. Using this photoresist has enabled the fabrication of tall and high aspect ratio structures without the use of a very expensive synchrotron source needed to expose the photoresist layer in X-ray LIGA. SU-8 photoresist appeared to be well-suited for LIGA templates, but also as a permanent material. Based on UV-LIGA and SU-8, Mimotec SA has developed processes to manufacture mold inserts and metallic components for various market fields. From one to three-level parts, from Ni to other materials, from simple to complicated parts with integrated functionalities, UV-LIGA has established itself as a manufacturing technology of importance for prototyping, as well as for mass-fabrication. This paper reviews some of the developments that led to commercial success in this field.

Based on a suitable infrared drying system, experimental considerations of photoresist drying during soft bake have been carried out. A simple mono-parametric model for describing drying kinetics of photo resists, derived from Second Fick?s Law, is presented in this paper. The presented model has been used for curve-fitting on the measurements. The resulting plots showing a good correlation to measurements, especially in the diffusion-dominated drying phases at long drying times. The diffusion coefficients (resulting from curve fits) clearly showing a thermal activated process. Subsequently, experimental considerations of drying of multi-layer systems has been carried out.

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.

We report a new type of negative-tone photoresist in this paper. The resist is based on a composite of EPON resins 154 and 165 (both from Hexion Specialty Chemicals, Inc., Columbus, OH 43215). These two epoxy-based resins were mixed in an optimal ratio and dissolved in gamma-butyrolactone (GBL) solvent. The mixture was then photosensitized by adding a given amount of triaryl sulfonium salt to obtain a new negative-tone photoresist that can be used in for ultra-high-aspect-ratio microstructure fabrication with UV lithography. Preliminary studies have found that microstructures with heights of more than 1000 μm and feature sizes down to 10 μm (aspect-ratios of more than 100) can be obtained using the new resist film with ultraviolet lithography. The microstructures have excellent sidewall quality. In this paper, both the material properties and lithography properties of this new type of UV resist will be presented. The potential applications of the new resist in microfabrication and MEMS systems are also discussed.

A giant magnetoimpedance (GMI)-based biosensor was developed for detection of Escherichia coli (E. coli) O157: H7. The GMI sensor involving the sensing elements of Cr/Cu/NiFe/Cu/NiFe was fabricated by Micro Electro-Mechanical system (MEMS) technology, including thick photoresist lithography and electroplating. A separate Au film substrate as immunoplatform was used to capture E. coli O157:H7. The monoclonal mouse anti-E. coli antibody was immobilized on Au film substrate surface with a self-assembled layer. The different concentration E. coli O157:H7 (100, 300 and 500 cfu/ml) were combined with Dynabeads-antibody conjugates (DAC) respectively. DAC were prepared by conjugating streptavidin-coupled Dynabeads with biotin-labeled polyclonal mouse anti-E. coli antibodies. The classical sandwich assay was used for detection of E. coli O157:H7 targeted with Dynabeads by using antibody-antigen pair combination of biotin-streptavidin. The fundamental principle for detection of E. coli O157:H7 based on GMI sensor was that Dynabeads were employed as magnetic labels of E. coli O157:H7, and E. coli O157:H7 can be monitored by detecting the fringe field of Dynabeads using magnetic sensing elements. We observed that the GMI ratio were significantly improved due to the presence of E. coli O157:H7 combined with Dynabeads. The GMI ratio increased as the E. coli O157:H7 concentration increased. A lower detectable concentration of 100 cfu/ml was achieved in present work. The GMI-based biosensor provides a new method to rapid and sensitive detection E. coli O157:H7, which has a large potential for bio-application.

本研究は, UV厚膜レジストによるフォトリソグラフィと電鋳の組み合わせによりマイクロコネクタを作製し, その特性評価を行った。作製したマイクロコネクタは100ピンで, 厚さ50μm, 最小幅15μm, 最大アスペクト比3.3であり, 端子間のピッチは80μmである。特性評価として接触力, 接触抵抗, ヤング率, 許容電流値の測定を行った。ソケット端子の変位量が5μmのときの接触力は3.3mNであった。四探針法により測定した端子間の接触抵抗は50mΩ以下であった。SPM法などにより端子を構成するNi構造体のヤング率を測定したところ180GPaであった。また, 環境試験を実施した結果, 設計したマイクロコネクタはAuめっきを施すことで安定した電気的接触が得られる見通しを得た。

The use of SU-8 high aspect ratio, thick, photoresist as a functional material for MEMS applications is described in this paper. SU-8 processing is developed to implement low-stress SU-8 structures as permanent and functional material incorporated with silicon-on-insulator technologies. Silicon micromachined cantilevers were fabricated with SU-8 structures on the cantilevers as added masses. Separation of material function can be achieved in this way. Silicon provides excellent mechanical properties, while SU-8 is used as extra mass to adjust the mechanical behaviour. The resonance behaviour of the cantilever structure with SU-8 is characterized through measurement, simulation and calculation, and the strength of the SU-8 material for this purpose is evaluated. The results show that SU-8 is well suited as a permanent material in mechanically active MEMS devices, and several applications are suggested. 3D MEMS architectures can also be achieved in this manner.

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.

A new low-cost UV LIGA process using photoresists as sacrificial layers has been developed to fabricate micromechanical components and systems. Commonly used photoresists are spun on a substrate and patterned by a mask aligner. Free-standing metal structures are built by patterning a second layer of thick photoresist and electroplating upon the photoresist sacrificial layer. Compared with all the existing sacrificial layer techniques, photoresists are easy to coat, easy to dissolve and fewer process steps are involved. The process is compatible to most of the materials and processes used in existing microfabrication technology. The precision issue of UV LIGA technique is also discussed.

Three-dimensional (3D) UV microforming delivers promising results for advanced surface micromachining. This low-cost technology, a combination of UV patterning of very thick photoresist layers and moulding of the resulting patterns by electrodeposition, opens a wide range of applications. It allows the use of materials with interesting properties that could not be provided by standard processes. Furthermore, this method can be carried out directly on pre-processed chips. The practical application of the technology is demonstrated by planar and 3D microcoils.

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

International audience; This work deals with recent advances in the microfabrication process technology for medium to high-aspect ratiostructures fabricated by UV photolithography using different kinds of photoresists. The resulting structures were used asmolds and will be transformed into metal structures by electroplating. Two types of photoresists are compared: epoxybased(negative) SU-8 and acrylate-based (negative) Intervia BPN. This work was prompted by the need to find analternative to SU-8 photoresist which is difficult to process and remove after electroplating. The results presented in thispaper open up new possibilities for low-cost processes using electroplating in MEMS applications.

International audience; The roughness of etched SiC surfaces must be minimized to obtain surfaces with a smooth aspect, avoiding micromasking artifacts originating from re-deposited particles during the etching process. Four varieties of masks, Al, Ni, Si and C, were deposited on the SiC surface by photolithographic process. The C structures were formed by annealing conversion of patterned thick photoresist. On these surfaces, dry etching was performed with an SF6/O2 plasma produced in a Reactive-Ion-Etching (RIE) reactor. Although a better aspect of the surface is obtained with Ni in comparison with Al mask, micromasking could also occur even with Ni if the mask design was not enough spaced out. With C and Si masks, which produce fluorides species with negative boiling temperature, smooth etched surface was obtained without micromasking, even for tight masks covering up to 90% of the SiC surface.

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.

In this work, the flip-chip method was used for packaging an RF-MEMS switch on a quartz substrate with low losses. 4-inch Pyrex glass was used as a package substrate and was airblast punched with 250 /spl mu/m diameter holes. A Cr/Au seed layer was deposited on it and the vias were filled by plating with gold. After forming molds on the holes with thick photoresist, bumps were plated on holes. The package substrate was bonded with a quartz substrate using B-stage epoxy. The loss of the overall package structure was tested with a network analyzer and was within -0.05 dB. This structure can be used for wafer level packaging of both RF-MEMS and other MEMS devices.

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).

High-energy well implants for advanced 0.18mm CMOS technologies are performed at normal incidence angles for minimizing the shadowing caused by the thick photoresist and the STI dimensions. Under these conditions (high-energy, normal incidence), even a small variation in angle can cause a significant variation on the well profile and can negatively impact the device performances. In this article both batch-to-batch variation and cone effect on batch implanter are discussed and analyzed. The analysis was done using Thermo-Wave (T.W.) and Secondary Ion Mass Spectrometry (SIMS) analysis. A good correlation between T.W. and SIMS, which can help predicting the distribution profile with T.W. results, was found. Some possible solutions are suggested.

A method is described for continuous observation of isolated single cells that enables genetically identical cells to be compared; it uses an on-chip microculture system and optical tweezers. Photolithography is used to construct microchambers with 5-microm-high walls made of thick photoresist (SU-8) on the surface of a glass slide. These microchambers are connected by a channel through which cells are transported, by means of optical tweezers, from a cultivation microchamber to an analysis microchamber, or from the analysis microchamber to a waste microchamber. The microchambers are covered with a semi-permeable membrane to separate them from nutrient medium circulating through a "cover chamber" above. Differential analysis of isolated direct descendants of single cells showed that this system could be used to compare genetically identical cells under contamination-free conditions. It should thus help in the clarification of heterogeneous phenomena, for example unequal cell division and cell differentiation.

Interest in thick photoresist applications is steadily growing. Specialised equipment has been developed to cope with the new challenges in the field of preparing extremely thick photoresist layers and the process to pattern these thick resists. A new technology called 3D UV-Microforming consisting of an advanced resist preparation process, UV lithographic steps, resist development, moulding procedures by electrodeposition, and finally stripping and cleaning for finishing the structures was developed. It enables the low-cost fabrication of a wide variety of micro components for many different users.

This paper proposes a new SU-8 fabrication process to simultaneously remove edge bead and tiny air bubbles by spraying out edge bead removal (EBR) fluid over the entire surface of photoresist. In particular, the edge bead and air bubbles can cause an air gap between a film mask and a photoresist surface during UV exposure. The diffraction effect of UV light by the air gap leads to inaccurate and non-uniform SU-8 patterns. In this study, we demonstrate a simple method using EBR treatment to simultaneously eliminate the edge bead at the edge of wafer and tiny air bubbles inside SU-8. The profiles of thickness variation of SU-8 films with/without the EBR treatment are measured. The results show that the proposed EBR treatment can successfully remove the edge bead and air bubbles over the entire SU-8 films. The average pattern uniformity of SU-8 is improved from 50.5% to 11.3% in the case of 200 µm thickness. This method is simple and inexpensive, compared to a standard EBR process, because it does not require specialized equipment and it can be applied regardless of substrate geometry (e.g. circular wafer and rectangular slide glass).

An important module of the packaging based on flip-chip is the formation of solder or Cu bumps. Solder bumps are usually defined lithographically with a thick photoresist mask. After the solder bump is built up, the photoresist needs to be stripped. Solder bumps are not compatible with photoresist ashing and FEOL strip chemistries. Hence, traditionally, photoresist strip with solder bumps exposed has been carried out with solvent strip chemistries. Over the last decade, there has been a lot of research on the use of ozone for photoresist stripping. However, no real breakthrough has happened because of the limited solubility of ozone in aqueous solution and hence it's extremely slow strip rates. In this work, we are describing a novel way of using ozone in solvent chemistries that have very high strip rates. This process is widely applicable, but is extremely useful for stripping photoresist with solder bumps exposed.

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.

Photoresist patterns with a thickness of 2 μm–16 μm are often applied in selective electroplating processes. We will treat some problems concerning the generation of such thick photoresist patterns and especially discuss the obtainable accuracy and edge definition of these patterns. We have investigated several positive photoresists which have been deposited by spraying or roller coating. The obtainable accuracy has been established with the aid of a test pattern. Gap widening and strip narrowing are dependent on u.v. exposure time and developing time; both relationships have been investigated. Postbaking of some kinds of photoresist is necessary, because the patterns must be suitable for selective electroplating. Deviations of the patterns due to postbaking are also discussed. Before dealing with the photolithographic procedures, we will briefly discuss some properties of positive photoresists.

In this paper, we describe a culture-based biochip for detecting microorganisms in environmental samples in an improved, timesaving, and cost-efficient manner. The biochips use the paraffinophilic nature of microorganisms to rapidly detect and differentiate them in sewage samples collected from wastewater treatment plants. A new method of depositing paraffin was developed to fabricate the biochips. The developed technique uses butanol solvent to keep paraffin liquid during spin-coating and thick photoresist for patterning. Using this approach, paraffin layers of 5-70 /spl mu/m have been successfully fabricated and patterned. These biochips were used to demonstrate rapid, 5-min detection of microorganisms responsible for reactor foaming in wastewater treatment.