基于傅里叶变换红外反射谱的DRAM深沟槽结构测量系统研究

Model-Based FTIR Reflectometry Measurement System for Deep Trench Structures of DRAM

提出了一种基于傅里叶变换红外(FTIR)反射谱的动态随机存储器(DRAM)深沟槽结构测量方法与系统。给出了测量原理与方法,设计了测量系统光路。通过可变光阑调节探测光斑大小并选择合适的入射角,消除了背面杂散光反射干扰的影响,大大提高了信噪比。对DRAM深沟槽样品进行反射光谱图测试与实验研究,表明所述方法与系统能够提取出纳米级精度的深沟槽参数。该技术提供了一种无接触、非破坏、快速、低成本和高精度的深沟槽结构测量新途径,在集成电路制造过程中的在线监测与工艺控制方面具有广阔的应用前景。

A method and system for measuring deep trench structures of dynamic random access memory （DRAM） based on Fourier transform infrared （FTIR） reflectometry is proposed. The principle of the measurement system is presented, along with a detailed description of the optical path design. By regulating the slit aperture to decrease the size of the detection spot and optimizing the incidence angle onto the wafer, the reflection from the backside of the wafer is suppressed, thus the signal-to-noise ratio （SNR） of the measurement is increased significantly. The experiments carried out on the deep trench structures of DRAM demonstrate that the trench geometric parameters can be extracted with a nanometer scale accuracy using the proposed system, thus the technique is proven to provide a non-contact, nondestructive, time-effective, low-cost and high resolution tool for the measurement of deep trench structures. It is expected that the proposed technique will find potential applications in the on-line monitoring and process control for microeleetronics and microeleetromechanical system （MEMS） manufacturing.