SBIR Phase I: Advanced Two-Color Interferometer for Turbulence Correction

这个小型企业创新研究第一阶段项目的重点是减少可以平版写入集成电路（芯片！）的最小特征尺寸。小于0.1 um的关键尺寸需要改进精度的干涉测量来测量容纳晶圆片的平台的位置。虽然目前的激光测量仪的稳定性可以提高到在恒定密度的空气中达到小于1纳米的精度，但这些测量仪不能校正空气密度的变化（湍流）。因此，湍流目前将覆盖精度限制在20-30纳米。对于0.1 um设计规则光刻来说，这种不精度是不可接受的，因为缩放估计表明，舞台位置测量对覆盖误差预算的贡献不应超过~2.5 nm。我们建议开发一种双色独立激光测量仪，可以同时测量湍流校正和绝对舞台位置。一个主要的优点是，其中一种颜色可以是He-Ne 633nm线，这是目前几乎所有商用激光测量仪中使用的。这项研究将带来一种低成本（约6万美元）、超紧凑的仪器，它将把激光测量仪对覆盖误差的贡献降低到2纳米。第一阶段将证明双色技术的可行性，第二阶段将是一个原理验证演示。由于消除湍流对激光测量精度的影响将变得越来越重要，因为步进器必须覆盖连续光刻晶圆曝光所需的分辨率提高了，因此步进制造商对拟议仪器的商业需求肯定会很强劲，预计到2004年市场将达到6000万美元。所提出的仪器将促进最小特征尺寸小于0.1 um的步进器的开发，并提高其分辨率。

9861111 This Small Business Innovation Research Phase I project focuses on reducing the minimum feature size that can be written lithographically to integrated circuits (chips!). Critical dimensions below 0.1 um require improved-precision interferometry to measure the position of the stage that holds the wafer. Although the stability of current laser gauges can be improved to attain a precision of less than 1 nm in constant-density air, these gauges cannot correct for air-density variations (turbulence). As a result, turbulence presently limits overlay precision to 20-30 nm. This imprecision is unacceptably large for 0.1 um design-rule lithography, for which scaling estimates show that the stage-position measurement should contribute no more than ~2.5 nm to the overlay error budget. We propose to develop a two-color stand-alone laser gauge that measures both the turbulence correction and the absolute stage position simultaneously. A major advantage is that one of the colors can be the He-Ne 633-nm line, which is used in nearly all current commercial laser gauges. This research will lead to a low-cost ( ~$60,000), ultra-compact instrument that will decrease the contribution of the laser gauge to the overlay error to 2 nm. Phase I will prove the feasibility of the two-color technique, and Phase II will be a proof-of-principle demonstration. Since the elimination of turbulence effects on laser-gauge precision will become progressively more critical as the required resolution with which steppers must overlay successive lithographic wafer exposures improves, commercial demand for the proposed instrument by stepper manufacturers is certain to be strong, with an anticipated market of $60 million by the year 2004. The proposed instrument will then facilitate the development of steppers with sub-0.1 um minimum feature sizes and improve their resolution.