A Non-Thermal Annealing Process Applied to Neutron Transmutation Doped Silicon

该项目旨在研究和开发一种新的退火技术，该技术既可以修复晶体损伤，又可以在不使用热能的情况下电激活硅中的掺杂剂。退火是通过将高能激光脉冲聚焦在样品表面的一个小点上来完成的。实验表明，即使在远离激光焦斑的区域，整个样品也被退火。据推测，激光在样品中发射了一个激波，而这个激波使晶体退火。由于激光脉冲很短（纳秒级），因此与热过程相比，该过程的扩散要少得多。扩散是下一代高密度低功耗器件设计和制造中的限制因素之一。正如SIA所说，半导体行业的“关键需求”是开发低漏浅结的“最小退火”。上面提到的非热过程显然是这个“最小退火”的候选。虽然这一过程对设备制造的一步很有吸引力，但有一些基本问题必须首先得到回答。两个最紧迫的问题涉及退火的最佳参数和退火发生的实际机制。最佳参数的确定将使该技术应用于各种不同的材料，并最终应用于图案化器件。对退火机制的理解将进一步加深对项目材料科学方面的理解，也将有助于将该技术应用于不同的材料。这些问题的答案将通过进一步的实验得到，这些实验将改变退火过程中涉及的参数，通过研究在不引入热能的情况下实现退火的替代方法，以及通过模拟冲击波通过损坏晶格的通道。＊＊＊

9732092 Donnelly The project seeks to investigate and develop a new annealing technique that is able to both repair damage to a crystal and electrically activate dopants in silicon without the use of thermal energy. The annealing is accomplished by focusing a high energy laser pulse onto a small spot on the surface of the sample. Experiments have shown that the entire sample is annealed, even in regions far from the laser focal spot. It is speculated that the laser launches a shock wave in the sample, and that this wave causes the crystal to anneal. Because the laser pulses are short (nanoseconds), the process is expected to be accompanied by much less diffusion than occurs in thermal processes. Diffusion is one of the limiting factors in the design and fabrication of next-generation high density low power devices. A "critical need" for the semiconductor industry, as stated by SIA, is the development of a "minimum anneal" for low leakage shallow junctions. The above mentioned non-thermal process is clearly a candidate for this "minimum anneal". While the process is attractive for a step in device fabrication, there are fundamental questions that must first be answered. The two most pressing questions involve the optimum parameters for annealing, and the actual mechanism by which the annealing occurs. Determination of optimum parameters will allow the technique to be applied to a variety of different materials, and eventually to patterned devices. Understanding of the annealing mechanism will further understanding of the materials science aspects of the project, and will also assist in the application of the technique to different materials. The answers to these questions will be obtained by further experiments which vary the parameters involved in the annealing process, by investigating alternated methods of achieving annealing without the introduction of thermal energy, and by modeling the passage of a shock wave through a damaged crystal lattice. ***