Precision Fabrication of Nanostructures by Optimal Mixed H2/H Control of Microcontact Next Generation Lithography Systems

0000541 Kailath许多不同的所谓NGL（下一代光刻）技术目前开始被探索用于延续迄今为止令人难以置信的成功的光学光刻技术，其可以将PI带到具有70 nm临界尺寸的器件，这是NGL技术的更有趣的类别之一，称为微接触或软光刻，甚至在10纳米特征尺寸的制造和工作集成器件中也表现出优异的图案化保真度。 微接触光刻方法涉及1：1共形掩模或模板，其通过几种不同的方法与衬底的表面直接接触，用于在接触之后完成印刷工艺，包括物理、化学和光子手段。 最近，PI的斯坦福大学半导体制造组开发了一种利用渗透膜材料（PMM）的新型微接触NCL策略。 在这种方法中，图案转移是通过分子运输的反应物种通过可渗透的多孔模板，以形成一个空间选择性的抗蚀刻掩模上的基板surfaces.At微接触NGL技术设想的尺寸，非常精确的定位和对准的掩模和基板将需要在整个印刷轨迹，包括延伸，保持，和收回。 PI的建议，以开发一个最佳的多变量控制系统，为此目的，与他们最近开发的PMM系统作为一个特定的测试车辆。 初步的探索使他们专注于一个双伺服6轴压电驱动的纳米定位弯曲阶段沿着与实时掩模基板间隙检测和激光干涉定位和对准。总体而言，精细平台系统将采用六个压电致动器和十九个高分辨率定位检测器。 虽然控制法律将开发和证明他们的PMM技术和相关的近场直接写入图案化系统，该战略将普遍适用于其他微接触NCL技术，采用弯曲定位方法。 首先，一个状态空间模型的弯曲阶段将确定使用所谓的子空间方法的最新进展，由赵和凯拉特在斯坦福大学。 在计划的方法中，将生成频域数据并计算线性时不变模型。 子空间识别技术提供了一种非迭代方法来生成多变量状态空间模型。 对于它们在传感器组中具有相当大的冗余度的应用，子空间模型识别方法是有用的，因为通过采用位移结构理论的结果，可以获得快速算法。 他们还计划研究使用子空间识别输出来确定控制单元的检测器和致动器的最小集合。使用识别的模型，他们将设计最优混合H2/H控制器。 H2/H控制目标适用于该项目，因为需要优化定位速度以提高产量，同时防止掩模在最坏情况下碰撞到基板表面。 由于振动，以及内部效应，如非线性梁弯矩，滞后，和可变的初始条件和地形的影响，随机和带限干扰，进入工厂，必须补偿沿着所需的定位轨迹。简而言之，这个建议设想的扩展和应用，最近的控制设计理论，设计一个非常高性能的纳米定位控制系统。 一个特定的新的所谓的PMM技术将是测试平台的发展。 然而，这些技术与几种微接触技术相关;它们也应该对特定应用有用，例如在弯曲表面上的制造，以及制造MEMS（微机电系统），微合成和微流体系统。

0000541KailathA number of different so-called NGL (next generation lithography) techniques are currently begin explored for continuation of the so-far incredibly successful optical lithography techniques, which can take the PI's to devices with 70 nm critical dimensions, one of the more interesting classes of NGL techniques, called microcontact or soft lithography, has demonstrated exceptional patterning fidelity in even the fabrication of 10 nm feature sizes and working integrated devices. Microcontact lithography methods involve a 1:1 conformal mask or template, brought into direct contact with the surface of the substrate with several different approaches for completing the printing process subsequent to contact, including physical, chemical, and photonic means. Recently, a novel microcontact NCL strategy utilizing permeable membrane materials (PMM) has been developed in the PI's Stanford semiconductor manufacturing group. In this approach, pattern transfer is achieved by molecular transport of reactive species through a permeable porous template to form a spatially selective etch-resistant mask on the substrate surface.At the dimensions envisaged for microcontact NGL techniques, extremely precise positioning and alignment of mask and substrate will be needed during the entire printing trajectory including extension, hold, and retraction. The PI's propose to develop an optimal multivariable control system for this purpose, with their recently developed PMM system as a specific test vehicle. Preliminary explorations have led them to focus on a dual servo 6-axis piezeo-driven nanopositioning flexure stage along with real-time mask-substrate gap detection and laser interferometry for positioning and alignment. Overall, the fine-stage system will employ six piezoactuators and nineteen high resolution positioning detectors. Although the control laws will be developed and demonstrated on their PMM technology and a related near-field direct write patterning system, the strategy will be generally applicable to other microcontact NCL techniques that employ flexure positioning methods.Some details on their proposed approach follow. First, a state-space model of the flexure stage will be identified using recent advances in the so-called subspace methods developed by Cho and Kailath at Stanford. In the planned approach, frequency domain data will be generated and a linear time invariant model will be computed. Subspace identification techniques offer a non-iterative method to generate multivariable state-space models. For their application which has considerable redundancy in the sensor set, the subspace approach to model identification is useful since, by employing results from displacement structure theory, fast algorithms can be obtained. They also plan to investigate the use of the subspace identification output to determine a minimal set of detectors and actuators to control the unit.Using the identified model, they will design an optimal mixed H2/H controller. The H2/H control objective is applicable to this project because of the need to optimize the positioning speed for an increase in throughput while guarding against worst-case crashes of the mask to the substrate surface. Both stochastic and bandlimited disturbances due to vibrations, as well as internal effects such as nonlinear beam bending moments, hysteresis, and variable initial conditions and topography effects, enter the plant and must be compensated along the desired positioning trajectory.In brief, this proposal envisages the extension and application of recent control design theories to design a very high performance nanopositioning control system. A specific new so-called PMM technology will be the testbed for the development. However the techniques are relevant to several microcontact technologies; they should also be useful for specific applications such as fabrication on curved surfaces, and for manufacturing MEMS (microelectro- mechanical systems), microsynthetic and microfluidic systems.***