Plasma-assisted atomic layer deposition of alumina and Parylene-C bi-layer encaps

描述（由申请人提供）：目前正在研究或治疗一系列神经系统疾病，使用完全植入式电子系统来记录或调节人类的大脑活动。目前，这些植入物被聚合物涂层保护着，聚合物涂层包裹着植入物，帮助体液远离敏感的电子设备。具有复杂三维几何形状的大脑植入物，如图中所示的犹他电极阵列（UEA），对当前的封装技术提出了挑战。由于其生物相容性、电学性能和化学惰性的完美结合，聚对二甲苯一直是神经和生物医学植入物封装的金标准。然而，用聚二甲苯包埋的长期神经植入物（bbb6个月）的记录能力显示出退化的迹象。为了解决这个问题，贝莱德微系统公司提出了一种新的双层封装方案，将等离子辅助原子层沉积（PA-ALD）氧化铝层结合在聚二甲苯层下面。这种封装方案在生物医学领域是新颖的，它将保留聚对二甲苯的所有优点，同时利用底层ALD氧化铝层的优越介电特性来创建更持久和更电稳定的生物医学植入物。这种双层封装方案可以无缝地整合到我们现有的旗舰产品UEA的制造工艺流程中。具有集成电子封装方法的UEA可以在不同的表面（金属，半导体，聚合物，陶瓷）和具有集成无线组件的设备上工作，这使得它非常适合用于长期植入的任何复杂医疗设备的涂层。该项目有4个具体目标：具体目标1：优化ALD氧化铝/聚对二甲苯双层封装方案，并在测试设备上与仅聚对二甲苯封装进行性能比较。具体目标2：开发蚀刻方法，选择性地暴露具有优化ALD氧化铝/聚对二甲苯双层涂层的uea上的活性电极位点。具体目标3：评估ALD氧化铝/聚对二甲苯双层涂层uea的电荷注入/阻抗特性。具体目标4:ALD氧化铝/聚对二甲苯双层涂层uea与仅聚对二甲苯涂层uea的体内性能比较。我们对聚对二甲苯和氧化铝涂层的平面交叉电极（IDE）测试结构的初步结果非常有希望支持所提出的工作。我们已经证明，双层封装产生更稳定的泄漏电流，并且在67℃下稳定阻抗（变化<5%）约5个月（大约相当于在37℃下40个月）。这种优异的双层包封性能表明其在具有复杂表面几何形状的慢性种植体中具有潜在的用途。在第一阶段“从实验室到市场”的SBIR项目结束时，贝莱德预计将制定出协议和标准，将这项研究从目前的早期实验室环境转变为商业级制造工艺。

DESCRIPTION (provided by applicant): A range of neurological diseases are now being researched or treated using fully implantable electronic systems to either record or modulate brain activity in humans. These implants are currently being protected using polymer coatings that envelop the implant and help keep body fluids away from the sensitive electronics. Brain implants with complex three-dimensional geometries, like the Utah Electrode Array (UEA) shown in the figure, provide a challenge for current encapsulation techniques. Parylene has been the gold standard for encapsulation of neural and biomedical implants in general due to its well-suited combination of biocompatibility, electrical properties and chemical inertness. However recording capabilities of long-term neural implants (>6 months) encapsulated with Parylene show signs of degradation. To combat this problem Blackrock Microsystems proposes a novel bi-layer encapsulation scheme that combines Plasma Assisted Atomic Layer Deposited (PA-ALD) alumina layer underneath the Parylene layer. This encapsulation scheme, novel to biomedical field, will retain all the advantages of Parylene while utilizing vastly superior dielecric properties of underlying ALD alumina layer to create a much longer lasting and more electrically stable biomedical implants. This bi-layer encapsulation scheme may be seamlessly incorporated into our existing fabrication process flow for our flagship product, the UEA. The bi-layer The UEA with integrated electronics encapsulation method will work on different surfaces (metal, semiconductor, polymer, ceramic) and on devices with integrated wireless components making it ideal for coating any complex medical device intended for long term implant. The project has 4 specific aims: Specific Aim 1: Optimize an ALD alumina/Parylene bi-layer encapsulation scheme and compare performance with Parylene-only encapsulation on test devices. Specific Aim 2: Develop etch methods to selectively expose active electrode sites on UEAs coated with optimized ALD alumina/Parylene bi-layer. Specific Aim 3: Evaluate charge injection/impedance characteristics of ALD alumina/Parylene bi-layer coated UEAs. Specific Aim 4: Comparison of in vivo performance of ALD alumina/Parylene bi-layer coated UEAs to Parylene-only coated UEAs. Our preliminary results with Parylene and alumina coated planar interdigitated electrode (IDE) test structures are very promising in support of the proposed work. We have shown that the bi-layer encapsulation yields more stable leakage current, and stable impedance (with <5% change) at 67 �C for about 5 months (approximately equivalent to 40 months at 37 �C). This superior performance of bi-layer encapsulation suggests its potential usefulness for chronic implants with complex surface geometries. At the end of the Phase I 'Lab to Marketplace' SBIR project, Blackrock expects to have developed protocols and standards to transform this research from its current early-stage lab setting into a commercial-grade manufacture process.