根據蒙地卡羅法之電子軌跡模擬與應用於多電子束微影之電子束位置感測器設計

MONTE CARLO SIMULATION OF ELECTRON TRAJECTORY AND DESIGN OF AN ELECTRON BEAM POSITION MONITOR SYSTEM FOR MULTIPLE ELECTRON BEAM DIRECT-WRITE LITHOGRAPHY

范期翔(Chi-Hsiang Fan)

指導教授 ： 蔡坤諭

共同指導教授 ： 陳永耀

國立臺灣大學/電機資訊學院/電機工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.03195

摘要

在多電子束微影技術中，電子束偏移成為一個越來越需要被重視的議題。造成電子束偏移的原因有很多，如試片表面的電荷殘餘，腔體中溫度的不穩定，污染….等。這些偏移會影響微影技術中的精準度和電子束的對焦，而且這些誤差會隨著操作時間增長而增加。
當一電子束打在試片上時，會產生各種類型訊號，其中一種就是由電子產生，最主要的電子訊號又分成兩類，分別叫做“二次電子”與“背向散射電子”，這兩種電子常常被用來在電子顯微鏡中呈現影像，顯示試片的表面及構造。當電子束打在試片上時，電子會與試片上的原子核產生交互反應，帶負電的電子會被帶正電的原子核吸引，若是電子沒有被原子核“捕捉”，電子行進的方向則會在損失很少能量和速度的狀況下，產生大角度的變化，這些發生角度變化的電子，被稱為“背向散射電子”。在一個電子顯微鏡中，背向散射電子感測器經常被放置在試片的正上方，藉以捕捉這些回彈的電子。
因為背向散射電子移動的速度快，能量高，相較於二次電子，他們比較不容易被外在的電場影響而改變方向，我們將針對背向散射電子彈射的分布進行研究與模擬，並期望分析二次電子分布與入射電子束偏移的關係，近而發展出一套能及時監控電子束位置以及聚焦大小的感測器系統。

關鍵字

電子束微影 ； 電子束偏移 ； 電子束位置感測器 ； 蒙地卡羅

並列摘要

Electron beam lithography is one of the promising candidates for next generation lithography because of the ultra-high resolution and the property of need no mask. In order to improve the problem of slow throughput, miniature electrostatic elements are widely utilized in order to drive large amount of beams at one time.
The electron beam drift problem becomes series and can not be neglected in a multiple electron beam lithography system. Current single electron beam lithography systems utilize periodic recalibration with reference markers on the wafer to achieve beam placement accuracy. But the technique becomes impractical with multiple beams.
In this thesis, architecture of beam position monitor system for multiple electron beam lithography is proposed. It consists of an array of electron detector placed above the wafer, which can detect the distribution of the backscattered electrons for each electron beam. The beam drifts and backscattered electrons distribution relation is simulated by Monte Carlo method using in-house MATLAB code. From the Monte Carlo electron trajectories simulation, it is believed that the change of backscattered electron distribution result from the electron beam drifts can be detected by the detector array. The beam drift can be calculated by using the detector output signals.

並列關鍵字

electron beam lithography ； Monte Carlo simulation ； electron beam drift ； beam position monitor system

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