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Membranes for a lung assist device must permit the exchange of gaseous O₂ and CO₂ while simultaneously acting as a liquid barrier, so as to prevent leakage of blood and its components from passing from one side to the other. Additionally, these membranes must be capable of being integrated into microfluidic devices possessing a vascular network. In this work, uniform, large-area, ultra-thin, polymeric free-standing membranes (FSMs) and composite membranes (CMs) are reproducibly fabricated by initiated Chemical Vapor Deposition (iCVD). The 5 μm thick FSMs remained intact during handling and exhibited a CO₂ permeance that was 1.3 times that of the control membrane (8 μm thick spun-cast membrane of silicone). The CMs consisted of a dense iCVD skin layer (0.5-3 μm thick) deposited on top of a polytetrafluoroethylene (PTFE) support membrane (20 μm thick, 100 nm pores). The CMs exhibited CO₂ and O₂ permeance values 50-300 times that of the control membrane. The FSMs were subjected to mechanical testing to assess the impact of the absence of an underlying support structure. The CMs were subjected to liquid barrier tests to ensure that while they were permeable to gases, they acted as barriers to liquids. Both FSMs and CMs were integrated into silicone microfluidic devices and tested for bond integrity.

Vapor based polymer deposition methods have evolved to address the limitations of solution polymerization. However this field of vapor based polymerization suffers from varied nomenclature and would benefit from a review article that brought together the different approaches to vapor based polymerization with an effort to present existing nomenclature, clearly identify the various approaches within this field and summarize recent results. This review article is written with the purpose of compiling recent advances in vapor based deposition methods of polymers with a focus on applications that will continue to drive research in this field. We hope that this article encourages researchers engineering novel polymer applications to give vapor based polymerization a serious consideration apart from solution polymerization methods.

Segmented CVD reactor designs enabling spatial control of across-wafer gas phase composition were evaluated for depositing graded films suitable for combinatorial studies. Specifically, two reactor designs were constructed and evaluated with experiments and response surface model (RSM) based analysis to quantify the reactor performance in terms of film thickness uniformity, sensitivity to adjustable reactor operating conditions, range of thickness over which uniformity could be achieved and each reactor's ability to control the thickness gradient across the wafer surface. Design features distinguishing the two reactor systems and their influence on gradient control vs. deposition rate performance are summarized. RSMs relating wafer state properties to process recipes are shown to be effective tools to quantify, qualify and compare different reactor designs.

Mass spectrometry has proven valuable in understanding and controlling chemical processes used in semiconductor fabrication. Given the complexity of spatial distributions of fluid flow, thermal, and chemical parameters in such processes, multipoint chemical sampling would be beneficial. The authors have designed and implemented a multiplexed mass spectrometric gas sampling system for real-time, in situ measurement of gas species concentrations at multiple locations in a spatially programmable chemical vapor deposition (SP-CVD) reactor prototype, where such chemical sensing is essential to achieve the benefits of a new paradigm for reactor design. The spatially programmable reactor, in which across-wafer distributions of reactant are programmable, enables (1) uniformity at any desired process design point, or (2) intentional nonuniformity to accelerate process optimization through combinatorial methods. The application of multiplexed mass spectrometric sensing is well suited to our SP-CVD design, which is unique in effectively segmenting the showerhead gas flows by using exhaust gas pumping through the showerhead for each segment. In turn, mass spectrometric sampling signals for each segment are multiplexed to obtain real-time signatures of reactor spatial behavior. Here the authors report results using inert gases to study the spatial distributions of species, validate SP-CVD reactor models, and lead to an understanding of fundamental phenomena associated with the reactor design. This forms the basis for using real-time mass spectrometry to drive process sensing, metrology, and control in such reactor systems.

A new chemical vapor deposition (CVD) reactor design was developed to intentionally induce spatially nonuniform film thickness deposition patterns on a single wafer. A segmented showerhead design allows individual regions of a wafer to be exposed to different precursor concentrations simultaneously during a run resulting in different thickness profiles on the wafer and a thickness gradient at the boundaries between segment regions. Different recipes were cycled through each of the segments in a sequence of deposition experiments to develop a model relating precursor concentration to film thickness in each segment region. As a demonstration of spatial programmability, the system was reprogramed using this model to produce uniform thickness amongst the segments; intersegment uniformity approaching 0.60% (thickness standard deviation) was demonstrated. Potential applications of this reactor design to combinatorial CVD are discussed.