Non-Invasive Process Monitoring and Real-Time Control for Semiconducting Manufacturing

这个项目的目标是通过非侵入性监测实现对气相薄膜沉积的新的基本理解，并确定这些信息如何改善气相半导体加工中的化学实时控制。几乎所有的半导体制造都涉及通过气相化学蚀刻或沉积薄膜。人们普遍认为，原位、无创过程监测和实时控制将提高制造成品率和吞吐量，需要更多的研究来开发合适的方法。例如，在最近（1994年8月）的评论中，《半导体国际》的编辑评论说：“实时监控仍然是一个非常理想的目标，但有点遥不可及。”关键是一种可靠的定量技术，可以追踪半导体晶圆表面或其附近发生的化学反应。提出了一种基于紫外光谱的方法。控制策略的同时测试将决定测量是否有足够的信息可供实际使用。实验环境将是一个现有的化学束外溢反应器，具有校准的流量、压力和晶圆温度监测。它支持从超高真空（10-10托）到10-4托压力的加工条件。同一位置的化学气相沉积反应器允许在10-4托至大气压的压力范围内进行额外的实验。实验将确定紫外光谱是否能够在实际操作条件下对多种化学成分进行积极的鉴定和定量。该方法具有足够的灵敏度，可用于气体密度最低的超高真空沉积条件。定量依赖于光信号的精确基线，因此新的无云窗口将与补偿源强度和光学透明度漂移的技术结合使用。力学建模将为未测量参数的估计和反馈控制提供基础。将使用基于模型的线性和非线性控制方法。最初的工作将测试该系统的能力，以跟踪1至3种稀释反应物的过量组成的随时间变化的设定值，并在晶圆表面提供均匀的温度。然后，该系统将用于控制GaAs与Al和In化合物的沉积。实验将确定紫外光束的位置（相对于晶圆片表面），以优化信息内容。控制策略的有效性将通过对沉积膜的独立（离线）化学分析来衡量。＊＊＊

9531816 Pearsall The goal of this project is to achieve new fundamental understanding of thin film deposition from the gas phase through non-invasive monitoring and to determine how this information can improve real-time control of chemistry in gas-phase semiconductor processing. Nearly all semiconductor manufacturing involves etching or deposition of thin films via gasphase chemistry. There is wide agreement that in-situ, non-invasive process monitoring and real-time control will improve manufacturing yield and throughput, and that more research is needed to develop suitable methods. For example, in recent (8/94) review the editor of Semiconductor International remarked, "Real-time monitoring remains a highly desirable, but somewhat distant goal". The key is a robust, quantitative technique that tracks the chemical reactions occurring at or near the surface of a semiconductor wafer. A method based on ultra-violet (UV) spectroscopy is focus of the proposed work. Simultaneous tests of control strategies will determine whether the measurements have enough information to be of practical use. The experimental environment will be an existing chemical beam expitaxy reactor with calibrated flow, pressure, and wafer temperature monitoring. It supports processing conditions from ultra-high vacuum (10-10 Torr) to 10-4 Torr pressure. A co-located chemical vapor deposition reactor allows additional experiments in the pressure range 10-4 Torr to atmospheric pressure. Experiments will determine whether UV spectroscopy can provide positive identification and quantitation of multiple chemical components at realistic operating conditions. This method has sufficient sensitivity to be used in ultra-high vacuum deposition conditions where the gas density is lowest. Quantitation depends on an accurate baseline for the optical signal, so a new nonclouding window will be used in combination with techniques that compensate for drift in source intensity and optical transparency. Mechanis tic modeling will provide the basis for estimation of unmeasured parameters and for feedback control. Linear and non-linear model-based control methods will be used. Initial work will test the system's ability to track time-varying setpoints for compositions of 1 to 3 dilute reactants in an excess of another, and to provide uniform temperature across the wafer surface. The system will then be used to control deposition of compounds of GaAs with Al and In. Experiments will determine where the UV beam should be located (relative to the wafer surface) in order to optimize the information content. The efficacy of the control strategy will be measured by independent (off-line) chemical analysis of the deposited film. ***