大型精密光罩製作兼量測平台其校準方法的創新研究

Abstract

以目前業界情況而言，在大型光罩製作的平台校正方面，絕大部分的大型光罩製造廠商，皆缺乏適合曝光機器平台的尺寸所需之”標準片”，而且亦無合適之量測儀器或機台來量測大型光罩以符合現今工業界客戶的需求。可將原因概略分成兩方面；其一是因為符合現今業界需求之”標準片”得來不易且價格昂貴；另一方面則是因為產業的快速升級、技術的世代交替不斷地加速與每一世代的生命週期愈來愈縮短。以致於在較早期所購置取得的”標準片” ，其尺寸面積已經太小不敷使用與規格需求。 有鑑於此，本研究乃設計一套簡易實用的量測檢驗之法則及計算方法，將可提供給因為礙於經費問題無法購置或租用精密儀器來校正或檢驗大型光罩之平台的情形下，利用此研究所闡述之方法及運用電腦軟體的分析，綜合分析與計算之結果，最終仍可得到所需要、滿意與符合預期規格的解決方案，而且此方法並不受限於”標準片”大小的問題。 本研究方法是先製作ㄧ片小型光罩，在精密度極高的小型量測儀器，先行驗證所運用之量測檢驗的法則及計算方法皆合理且準確後，再將此研究的方法推展到大型尺寸光罩之曝光機兼量測儀器上來分析、驗證和校正機器平台。

Currently, it is very expensive or hard to produce a full stage “golden plate” for large area mask fabricators to calibrate their stage of the exposure tool. Furthermore, it is lack of recessive calibration data or theoretical information for implementing calibration processes for the metrology tool to measure large area mask to meet the requirement of customers in semiconductor industry. Roughly, there are 2 reasons: First, it is very difficult to order or get the suitable “golden plate”. The price is too high. Second, the technology generation is pushed faster and faster. The lifetime of each generation becomes shorter and shorter. The “golden plate” of former generation tool is no lounger larger enough in full stage calibration for current generation tool to meet the requirements of large area mask customers. The research proposes a simple and practical methodology of metrology and calculation for large area mask exposure machine. The proposed innovative methodology was generated by many series of experimental tests and supported by least squcure statistical method. The metrology and verification software has been developed and evaluated based on large amount of measured data from on line metrology machine for about a year. Applying this methodology, the expected calibration performance shows that it is no longer limited by full stage “golden plate” for large area mask exposure machine. The big advantage is that the expensive metrology tool is not necessary the only choice for the calibration of large area mask exposure tool. Several experiment data results demonstrate and prove the methodology is accurate, reasonable and suitable on current higher accuracy exposure and metrology tools for IC masks. The proposed methodology has been applied to on line large area mask fabrication. The practical performance and the customer’s appreciated feed back have also demonstrated the efficiency and usefulness of the innovative metrology and calibration methodology.