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用电子束系统在涂有抗蚀剂的半导体晶片上直接曝制电路图形,在集成电路的生产中得到了日益广泛的使用。这种系统以其固有的绘制图形的高分辨率,且无需通常光刻系统所需的掩模而引人注目。为使生产在经济上有竞争能力,电子束系统必需具有高的晶片加工生产率;为此,系统必须全部自动化,並使诸如各种校准,图形对准和晶片的机械位移等辅助操作的时间减至最小。本文叙述图形对准过程,它把器件生产中某道工序所需的电路图形与前道工序已做好的图形套准。文中讨论了为生产上使用的电子束曝光系统设计一个准确的高速对准过程的基本问题。此自动对准系统化在每个集成电路芯片上的时间为150ms,使系统的生产卑可以达到每小时加工2000个5mm的芯片,而套刻的误差小于0.75μ(3σ)。文中给出了此系统的工作过程,性能指标和图形套准精度的测量结果。
Direct exposure of circuit patterns on resist-coated semiconductor wafers by electron beam systems is gaining increasingly widespread use in the production of integrated circuits. Such a system draws attention at its inherent high resolution of drawing patterns and without the need of the masks typically used in lithography systems. To make the production economically competitive, the electron beam system must have high wafer processing productivity; for this, the system must be fully automated and allow for time-consuming subtraction of auxiliary operations such as various calibration, pattern alignment, and mechanical displacement of the wafer To the minimum. This article describes the process of pattern alignment, which registers the circuit patterns required for a process in a device production with the previous pattern registrations. The basic issue of designing an accurate high-speed alignment process for electron beam exposure systems used in production is discussed. The automatic alignment time of 150ms on each integrated circuit chip enables the system to produce up to 2000 5mm chips per hour, with a tolerance of less than 0.75μ (3σ). The paper gives the working process of the system, performance indicators and graphics registration accuracy measurement results.