The ultra-high density hybrid flip chip integration of an array of detectors and its dedicated readout electronics can be achieved with a variety of solder bump techniques such as pure Indium of Tin alloys, (In, Ni/PbSn), but also conducting polymers, etc. Particularly for cooled applications or ultra-high density applications, Indium solder bump technology (electroplated or evaporated) is the method of choice. The state-of-the-art of solder bump technologies that are to a high degree independent of the underlying detector material will be presented and examples of interconnect densities between 5e4/cm² and 1e6/cm² will be demonstrated. For several classes of detectors, flip-chip integration is not allowed since the detectors have to be illuminated from the top. This applies to image sensors for EUV applications such as GaN/AlGaN based detectors and to MEMS-based detectors. In such cases, the only viable interconnection method has to be through the (thinned) detector wafer followed by a based-based integration. The approaches for dense and ultra-dense through-the-wafer interconnect "vias" will be presented.

When tackling the issue of low cost and enabled mass production for photonic circuits, the application of flip-chip technology creates huge expectations. We report on the results of a European project, in which it was the goal to demonstrate standard packaging technology in combination with specific integrated optics devices, entailing demands and limitations different from IC technology. In integrated optics devices, mainly the fiber attachment, but also some special features as the accessibility of windows at the top-side of the chip (e.g. sensing devices) are prohibiting the positioning of the optical layer stack and the solder pads for the flip-chip processing at the same side of the silicon wafer. Therefore, a feed through technology for the electrical wiring had to be included. Compatibility issues in combining the feed through technology with integrated optics processing have been solved. In this paper, we will demonstrate the successful feed-through metallization and flip-chip assembly in combination with an integrated optical sensor. The sensor, which has been designed for the measurement of relative humidity from 0-100 %RH, has been realized and packaged according to this technology. The feed-through metallization, solder type and chip carrier material have been chosen in a way that the demands of the demonstrator device are fulfilled according to a given specification.

Au/Sn solder bumps are commonly used for flip chip assembly of optoelectronic and RF devices. They allow a fluxless assembly which is required to avoid contamination at optical interfaces. Flip chip assembly experiments were carried out using as plated Au/Sn bumps without prior bump reflow. An RF and reliability test vehicles comprise a GaAs chip which was flip chip soldered on a silicon substrate. Temperature cycling tests with and without underfiller were performed and the results are presented. The different failure modes for underfilled and non-underfilled samples were discussed and compared. Additional reliability tests were performed with flip chip bonding by gold thermocompression for comparison. The test results and the failure modes are discussed in detail.

PLATIMO is a photonic micro devices integration unit set up by the CEA-LETI in the Optronics Department thanks to a contribution of the Rhone-Alpes region. The aim of PLATIMO is to propose to industrial and institutional designers a partnership with the knowledge, experience, and necessary automated equipment to speed up the prototyping process and to develop automated assembly solution. To illustrate the capabilities of PLATIMO, we present three very various achievements using the optobonder. The first realization is a microchip laser assembling with pick-and-placed components. The second onz is an 8-channel V-groove assembling to a planar waveguide splitter by active alignment. The third realization is a highly integrated 10Gbit/s transmitter optical sub-assembly with pick-and-placed optical fiber stub or barrel for multimode VCSEL coupling.

Miniaturization of precision optical components offers the opportunity for highly integrated high performance but lowcost devices for a wide field of applications. An increasing amount of examples could be found in the optical communication market and in sensor technology. Basing on several examples, we discuss actual developments in both fields.

Optical microsystems, which can be fabricated using replication technology and assembled using optical surface mounting techniques, can offer compact, cost-effective solutions for applications in optical communication, metrology, sensors, illumination and displays. Especially adapted to the needs of mid-size volume production of a few hundred to thousands modules is wafer-scale replication. The fabrication of single micro lenses or lenslet arrays on wafer substrates and the wafer-scale replication of such lens arrays for optical microsystems in sol-gel materials is under development as a cost-effective alternative to lens fabrication in glass. For an optical microsystem with a compact module for laser beam forming, wafer-scale, singlesided and double-sided replication has been developed to fabricate refractive or diffractive optical elements onto glass substrates. Combined opto-mechanical modules have been UV-cast-replicated from a sol-gel master in a single step. In addition, step & repeat replication can be employed for the fabrication of large arrays of custom specific lenses. Replication accuracy of better than a wavelength has already been achieved for refractive lenses with 50 μm SAG. Finally, diced optical components from the replicated wafers will be used for the manufacturing of micro-optic systems. A six-axis robot motion, automated optical alignment and laser-reflow soldering method is used to assemble the photonics modules. This method, called TRIMO-SMD (three-dimensional miniaturized optical surface-mounted device), is currently being made commercially available by Leica Geosystems AG.

The strength of today's deep lithographic micro-machining technologies is their ability to fabricate monolithic building-blocks including optical and mechanical functionalities that can be precisely integrated in more complex photonic systems. In this contribution we present the physical aspects of Deep Lithography with ion Particles (DLP). We investigate the impact of the ion mass, energy and fluence on the developed surface profile to find the optimized irradiation conditions for different types of high aspect ratio micro-optical structures. To this aim, we develop a software program that combines the atomic interaction effects with the macroscopic beam specifications. We illustrate the correctness of our simulations with experimental data that we obtained in a collaboration established between the accelerator facilities at TUM, LNS and VUB. Finally, we review our findings and discuss the strengths and weaknesses of DLP with respect to Deep Lithography with X-rays (LIGA).

A process of UV-induced fabrication of single mode waveguides in a polymer microoptical bench has been realized that offers the unique feature of an inexpensive microstructure replication process for mass fabrication. Instead of using common mask techniques for the realization of the stripe waveguides, a "Self-masking" technique of the polymer by embossing a microoptical bench and a following UV-flood-exposure is used. The mould insert, which is necessary for the replication process was made by the LIGA-technique. The fabrication of the micooptical bench and the waveguides in the same process step assures very good alignment accuracy and guarantees a low cost passive fiber-chip coupling and assembly. The photoinduced chemical reactions of different homo- and copolymers of methylmethacrylate under different environmental condition have been investigated. It was shown that depending on the environmental conditions during photoinduced waveguide generation, the physical and chemical properties of the waveguides can be adjusted in a wide range. The process allows the realization of devices for application in telecommunication and sensor technology.

Integration of optical interconnections on a Printed Circuit Board (PCB) is very challenging, as it should remain compatible with existing PCB manufacturing technology based on laminated FR4-substrates and making use of solder-reflow and well-known placement and assembly techniques. In this paper we will describe different technologies being used for integration of such optical interconnections in PCB's. As we will demonstrate, the use of laser ablation, already used in PCB manufacturing for microvia's, is a suitable technique for the fabrication of multimode waveguides and micromirrors to provide optical coupling. Laser ablation is a very flexible technology that is particularly well suited for structuring of polymers because of their excellent UV-absorption properties and highly non-thermal ablation behavior. One of the most critical problems on the integration of optical interconnections in PCB's is coupling the light in and out of the optical plane. Because in our set-up the excimer laser beam can be tilted, the 45 degrees micromirrors can be easily fabricated using laser ablation. The focus is on ablation of waveguides using a frequency tripled Nd-YAG laser and on ablation of 45 degrees facets using a KrF excimer laser. It is shown that these structures can be defined in one single processing step, resulting in a very accurate alignment.

A significant part of the work in developing micro-optics devices is solving the aspect of the packaging. The optical design requires very often an exact positioning of the optical components along the six degrees of freedom. Numerous techniques are now proposed for aligning (passively or actively) and fixing the optical components in the aligned position for a long-term stability. The Swiss Federal Institute of Technology in Lausanne and Leica Geosystems in Heerbrugg developed a novel automated assembly technique called TRIMO-SMD suited to assemble modules composed of small optical components (maximum diameter of 2mm). The attachment procedure is based on a highly stable laser reflow soldering process between standard metal holders housing the optical components and a metallized transparent mounting plate. The active alignment in all six degrees of freedom of the optical holder is performed with a high stiffness and high-resolution robot system. A test procedure has been developed for quantifying the positioning accuracy after soldering and the thermal stability of the TRIMO mounts. The displacements of the TRIMO holders during the soldering process and during a thermal load have been measured by means of standard laboratory vision sensors along with a 2D least square matching processing. One micron TRIMO assembly precision could be demonstrated.

Hybrid micro-integration of semiconductor devices, micro-optics, fiber-optics and micro-electronics is of growing interest for automotive, computer, telecommunication, business equipment and consumer applications. A large variety of the functions and components within these photonic devices and missing packaging standards make most of them not mass producible and therefore expensive. In addition most of them need reproducible and accurate alignment in the micron or even sub-micron range. Automated processes are necessary to get the accuracy and the reproducibility for high yield fabrication. Expensive production equipment is available mostly especially adapted to the specific product. The machines do need heavy granite bases and a temperature controlled fabrication environment to realize the requirements mentioned above. They appear as dinosaurs compared to the tiny products fabricated. Cost reduction can be achieved by using only partly automated production sequences in a modular desk top factory. Consequently we have miniaturized the robots, the factory framework and the tools for handling, dispensing and inspection. For the first time an exchangeable tool assortment with a standardized mechanical, electrical and fluidic interface between the robot and the end-effector is available. The modularity allows a flexible and re-useable set-up of the production equipment. The fabrication process uses a new technology with a closed loop control of the robot directly correlated to the assembly process to get sub-micron accuracy. The control signals are determined from the deviation of a component relative to the assembly position with miniaturized microscopes integrated to the tools[2]. Solutions with multiple fiber handling and automatic process control for the joining of fibers to micro-optics and microoptics to micro-benches, the assembly of silicon fiber-optical switches and of two-dimensional fiber arrays will be shown. Also a technology for the fabrication of fiber-optic collimator arrays with back reflection losses well above 70 dB will be presented.

A low cost packaging method, based on aluminium layered laminate sealing technology, is presented in this paper for the environmental hardening of planar waveguide splitters, filter WDM assemblies and other non-robust passive devices. Since the former two passive components will play a prominent role in PON networks and their upgrading scenarios, we questioned their long term reliability in uncontrolled outside plant environments by investigating their behavior in environmental testing as defined by Telcordia 1221. In particular, the optical performance of planar splitters and filter WDM assemblies from randomly chosen suppliers was monitored during temperature cycling and long term damp heat testing. A comparison was made between devices as packaged by the supplier and devices packaged in our Al laminate packaging. Although the packaging of planar waveguides has improved over the last years, our study convincingly demonstrates failure modes in the non-laminate packaged planar splitters. In addition, dramatic failures were also observed in filter WDM's assembled in modules for wide WDM, coarse WDM and dense WDM, which raise serious concerns about their long term environmental reliability. The laminate packaged devices however all pass the severe test conditions, exhibiting a better stability. This favors the use of our packaging method for the integration of planar splitters and filter WDM based assemblies in outside plant network elements.

This paper describes an alternative way of sealing an optical fiber at a much lower cost than soldering, with an equal to or lower susceptibility to creep and misalignment of the fiber, and higher reliability. It involves the use of a low temperature (320C) glass preform which seals directly to the bare fiber without the need for the costly metallization required for soldering. Various processing methods are outlined, along with cross sections of the sealed fiber in a ferrule. The key variables of the seal length, inside diameter of the tube, and the tube material itself are discussed in reference to their impact on designing a reliable, stress controlled hermetic seal. Reliability information is presented to demonstrate the viability of this technique for hermetically sealing optical fibers in a package feed-through tube.

In this study, polymeric microlens arrays, well suited for high-volume and low-cost production, were developed for efficiently coupling the light from vertical-cavity surface emitting lasers (VCSELs) to multi-mode fiber ribbon. They were fabricated by microinjection molding with Ni-electroplated mold insert. Modified LIGA processes and the Ni-electroplating are used to make the master and the metallic mold insert, respectively. In this study, microinjection molding with metallocene based cyclic olefin copolymer (mCOC) was chosen to replicate microlenses. Good surface profile and high dimensional accuracy are achieved. Coupling efficiency of 55 +/- 3 % with a working distance of 400 +/- 60 micrometer is obtained. To verify its applications on high-speed interconnections, we also designed the evaluated board and set up an opto-electronic measurement platform. The high-speed measurement shows that the electrical-to-optical conversion 3dB-bandwidth is above 1.8 GHz, and the eye diagram at 2.488 Gbps is acceptable for the SONET OC-48 eye mask.

Structuring surfaces on a microscopic scale allows to modify their optical properties. The exact tailoring of these properties requires very precise manufacturing techniques. On large areas, mainly replication techniques allow competitive production cost. This paper addresses the challenge of originating and replicating microstructures with optical functions with dimensions between 200nm and 50μm on areas of up to half a square meter. The whole experimental process chain is described and discussed. For the microstructure origination, interference lithography was used. An argon ion laser was chosen as a coherent light source at a wavelength of 364nm. Periodic and stochastic interference patterns were recorded in positive photoresist by using large interferometer set-ups. Structures with good homogeneity were originated on areas of up to 4800 cm2 by optimizing the set-up and the photoresist processing. By carefully modeling resulting resist profiles it was possible to originate a wide variety of surface-relief profiles including prismatic ones. Different replication techniques like hot compression molding and UV casting are discussed. Some applications of large-area micro-structured films and sheets are presented.

The results of ellipsometric investigations of surfaces of glassceramic samples with ultra low coefficient of thermal expansion are presented. These glassceramic samples are used in manufacturing of precision parts of optical instruments, for instance for telescope mirrors manufacturing. The aim of these investigations was to study the influence of the surface damaged layer and elastic deformations on the residual ellipticity of polished surfaces of glassceramic samples with ultra low temperature expansion coefficient. It was shown that with increasing of the surface layer polished depth damaged by grinding, the residual ellipticity decreases up to the value that remains a constant. Its value is determined by the material structure and stresses in the surface layer.

From the analysis of the known data and the results of investigations carried out, advantages and limitations of different methods of unglue bonding of glass-ceramic parts like Zerodur with ultra low coefficient of thermal expansion (CTE), are presented. It seems that by (quality-cost) criterion the solid-phase bonding of polished parts (SBPP) with the use of thin layer aluminum or its alloys to bond the ceramic optical parts is favorable. In optimal case the metal coatings for glass-ceramics bonding should be multilayer. The examples of SBPP bonding of glass-ceramic parts are presented which are close to strength characteristics of a monolith. It is shown that for bonding quality control the optical methods, including thermo-vision, can be applied.