光刻工艺中的焦距异常发生原因分析及解决办法

第一节Ｌｏｃａｌ Ｄｅｆｏｃｕｓ············································３９
第二节Ｅｄｇｅ Ｄｅｆｏｃｕｓ·············································４０
３．２．１机台本身因素造成的Ｅｄｇｅ Ｄｅｆｏｃｕｓ···················－······’４０
３．Ｚｅｒｏ Ｍａｒｋ ａｒｅａ ｄｅｆｏｃｕｓ
经过研究，我们发现Ｚｅｒｏ Ｍａｒｋ ａｒｅａ ｄｅｆｏｃｕｓ是一种特殊的Ｌｏｃａｌ ｄｅｆｏｃｕｓ， 由于其发生在Ｚｅｒｏ Ｍａｒｋ区域，那里没有图形，因此是很难检测到，一旦发生， 通常的ＡＤＩ目检无法发现问题，Ｏｖｅｒｌａｙ会发生较大的ｓｈｉｆｔ，Ｌｏｔ如果继续
２０％３０％ｄｅｆｏｃｕｓ ｉｎ ｔｈｅ ｐｈｏｔｏ ａｒｅａ，ｏｔｈｅｒ ｄｅｆｏｃｕｓ ｗａｆｅｒ ｗｉｌｌ ｂｅ ｓｅｎｔ ｔｏ ｎｅｘｔ ｓｔｅｐ ａｎｄ ｉｔ
ｗｉｌｌ ｉｍｐａｃｔ ｔｈｅ ｐｒｏｄｕｃｔ ｙｉｅｌｄ．
Ｔｂｊｓ ｔｈｅｓｉｓ ｗｏｒｋ ｉｓ ｄｅｄｉｃａｔｅｄ ｔｏ ｓｔｕｄｙ ｔｈｅ ｔｙｐｅ ｏｆ ｔｈｅ ｄｅｆｏｃｕｓ ａｎｄ ｔｈｅ ｒｏｏｔ ｃａｕｓｅ ｏｆ ｔｈｅｍ ｉｎ ｔｈｅ ｌｉｔｈｏｇｒａｐｈｙ ａｒｅａ。刀玲ｔｈｅｓｉｓ ｗｉｌｌ ｇｉｖｅ ｏｕｔ ｓｏｍｅ ｍｅｔｈｏｄｓ ｔｏ ｄｅｔｅｃｔ ｔｈｅ ｄｅｆｏｃｕｓ ｉｎｌｉｎｅ ＡＳＡＰ ｔｈｒｏｕｇｈ ｍｏｎｉｔｏｒｉｎｇ ｔｈｅ ｐｒｏｐｅｒ ｐａｒａｍｅｔｅｒ ｉｎ ｔｈｅ ｂａｔｃｈ ｒｅｐｏｒｔ，ａｎｄ ｗｅ ｃａｌｌ ｍｏｄｉｆｙ ｓｏｍｅ ｐａｒａｍｅｔｅｒ ｉｎ ｔｈｅ ｊ ｓｃａｎｎｅｒ ｏｂ ｉｎ ｏｒｄｅｒ ｔｏ ｄｅｃｒｅａｓｅ ｔｈｅ ｄｅｆｏｃｕｓ ｐｏｓｓｉｂｉｌｉｔｙ．Ｕｓｕａｌｌｙ ｗｅ ｗｉｌｌ ｆａｃｅ ｔｈｒｅｅ ｋｉｎｄｓ ｏｆ ｄｅｆｏｃｕｓ ｉｎ ｏｕｒ ｐｈｏｔｏ ｐｒｏｃｅｓｓ：
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摘 要····························································ｌ
Ａｂｓｔｒａｃｔ·················································－··········３
第一章半导体光刻技术···············································５ 第一节光刻工艺技术发展及展望····································５ 第二节光刻基本原理及成像条件································““６ 第三节光阻化学性质与作用····································“”６ 第四节光刻工艺流程介绍··········································８ １．４．１去水烘烤／ＨＭＤＳ············································９ １．４．２光阻涂布··················································９ １．４．３软烤··················································一·．１３ １．４．４晶边曝光ＷＥＥ（Ｗａｆｅｒ Ｅｄｇｅ Ｅｘｐｏｓｕｒｅ）························１４ １．４．５对准／曝光·············································一“１４ １．４．６曝光后烘烤················································１７ １．４．７显影···········”··”············一·················．．····１８ １．４．８硬烤···················．．”···”·······”················．１８ 第五节光阻涂布与显影设备····························一·····“·１９ １．５．１ Ｔｒａｃｋ机台及构造··········································１９ １．５．２涂布机台及构造···········································＂２０ １．５．３显影机台·················································Ｑ１ 第六节曝光设备·········一······一一·“”一···””····一．．·一一２１ １．６．１ ｌｅｖｅｌｉｎｇ系统··············································Ｑ２ 第七节解析度与聚焦深度································“····“２３ 第八节光罩相关技术············································２４ 第九节显影后的检查·····················“·····一“············２５ １．９．１显影后检查步骤···········································．２５ １．９．２显影后目检（ＡＤＩ．Ａｆｔｅｒ Ｄｅｖｅｌｏｐ Ｉｎｓｐｅｃｔｉｏｎ）····················．２５ １．９．３ ＡＤＩ的常见缺陷···········································．２６
Ｗｅ ｗｉｌｌ ｕｓｕａｌｌｙ ｍｅｅｔ ａ ｋｉｎｄ ｏｆ ｄｅｆｅｃｔ ｃａｌｌｅｄ ｄｅｆｏｃｕｓ ｉｎ ｔｈｅ ｐｈｏｔｏ ｐｒｏｃｅｓｓ．Ｄｅｆｏｃｕｓ ｍｅａｎｓ ｍａｔ ｔｈｅ ｆｏｃｕｓ ｏｎ ｔｈｅ ｓｐｅｃｉｆｉｃ ｌｏｃａｔｉｏｎ ｏｆ ｔｈｅ ｗａｆｅｒ ｉｓ ｏｕｔ ｏｆ ｔｈｅ ＤＯＥ Ｇｅｎｅｒａｌ ｓｐｅａｋｉｎｇ，ｄｅｆｏｃｕｓ ｗｉｌｌ ｍａｋｅ ｔｈｅ ｐｒｏｆｉｌｅ／ＣＤ ａｂｎｏｒｍａｌ ａｆｔｅｒ ｔｈｅ ｐｈｏｔｏ ｐｒｏｃｅｓｓ，ａｎｄ ｔｈｅｎ ｉｔ ｗｉｌｌ ａｌｓｏ ｉｍｐａｃｔ ｔｈｅ ｐｒｏｆｉｌｅ／ＣＤ ａｆｔｅｒ ｔｈｅ ｅｔｃｈｉｎｇ ｐｒｏｃｅｓｓ．Ｐｈｏｔｏ ｃａｌｌ ｄｅｔｅｃｔ ｏｎｌｙ
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摘要
在摩尔定律的指引下，半导体工艺的发展经历了从０．３５微米到Ｏ．２５微米， ０．１８微米，０．１３微米，直到现在国内大量生产的最先进的工艺０．０９微米和０．０６８ 微米，同时０．０４５微米也正处在积极研发试验当中。而国际上英特尔等公司正在 将技术节点向０．０３２微米，０．０２２微米推进。
第二章典型焦距异常现象及其原因分析································２８ 第一节如何确定光刻参数········································２８ ２．１．１光阻的选择···············································２８ ２．１．２光阻厚度曲线（Ｓｗｉｎｇ Ｃｕｒｖｅ）·······························Ｑ９ ２．１．３最佳焦距与曝光能量·······································＂２９
半导体集成电路制作过程中，光刻工艺是非常重要的一道工序。它的重要性 在于准确定义集成电路的图形形态，尺寸，以及前后层之间的对准。光刻工艺的 好坏，对后道制程中蚀刻，离子注入等工艺的准确进行至关重要。
在光刻工艺过程中，我们经常会碰到一个缺陷，那就是焦距异常，焦距异常 就是曝光机在晶圆的某些特定的位置上的曝光焦距超出了该层次的焦深，通常焦 距异常会导致光刻工艺后得到的光阻ｐｒｏｆｉｌｅ异常及ＣＤ值异常，从而进一步导致 刻蚀后得到的图形异常。我们通常在ＡＤＩ阶段可以拦下来的焦距异常最多只能占 焦距异常晶圆中的２０％’３０％，其他的晶圆被放下去之后都会对最终良率造成不同程 度的不良影响。
Ｆｏｒ ｔｈｅ ＩＣ ｍａｎｕｆａｃｔｕｒｉｎｇ，ｔｈｅ ｌｉｔｈｏｇｒａｐｈｙ ｉｓ ａ ｋｅｙ ｐｒｏｃｅｓｓ ｂｅｃａｕｓｅ ｉｔ ｄｅｆｉｎｅｓ
ｐａｔｔｅｒｎｓ ｗｉｔｈ ｐｒｅｃｉｓｅ ｄｉｍｅｎｓｉｏｎｓ ａｎｄ ｌｏｃａｔｉｏｎｓ，ａｓ ｗｅｌｌ ａｓ ｇｏｏｄ ｏｖｅｒｌａｙ ｐｅｒｆｏｒｍａｎｃｅ． ｎｅ ｑｕａｌｉｔｙ ｏｆ ｔｈｅ ｌｉｔｈｏｇｒａｐｈｙ ｐｒｏｃｅｓｓ ｉｓ ａｌｓｏ ｃｒｉｔｉｃａｌ ｆｏｒ ｓｕｂｓｅｑｕｅｎｔ ｅｔｃｈｉｎｇ ｍａｄ ｉｍｐｌａｎｔａｔｉｏｎ ｐｒｏｃｅｓｓｅｓ．
３．２．２晶圆本身边缘的拓扑形态与中央的差异性引起的Ｅｄｇｅ Ｄｅｆｏｃｕｓ··．４１ 第三节Ｚｅｒｏ ｍａｒｋ ａｌｅａ Ｄｅｆｏｃｕｓ·····································４３
结｛仑···························································４６
２．Ｅｄｇｅ ｄｅｆｏｃｕｓ
Ｅｄｇｅ ｄｅｆｏｃｕｓ就是发生在晶圆边缘的焦距异常现象，据统计，Ｅｄｇｅ ｄｅｆｏｃｕｓ对良 率的影响大概在Ｏ．５％’２％之间，虽然不是很大，但是几乎所有的晶圆都有发生， 从总数来看，这种焦距异常对良率的影响是很大的。本文针对Ｅｄｇｅ ｄｅｆｏｃｕｓ发生 的两种根本原因进行研究，从而找到在曝光机程式中可以改善该现象的方法。
２工４制程窗口。Ｐ∞ｃｅｓ 讹ｄ。ｗ）．．．．．．．．．．．．．．．．．｛ＩＹＩ Ｉ Ｉ Ｉｌ ｌ ｌ ｌ ９１ １ １ ６１ ＬＩｌ７ＩＩＩｌ５ＩＩＩＬ５ｔｌｌｌ攀
第二节光刻中三种典型的焦距异常现象及原因分析··················３３
２．２．１ Ｌｏｃａｌ ｄｅｆｏｃｕｓ·············································３３
关键词：光刻，缺陷，焦距异常，参数监测 中图分类号：ＴＮ４７
Ａｂｓｔｒａｃｔ
Ｄｒｉｖｅｎ ｂｙ ｔｈｅ Ｍｏｏｒｅ’Ｓ Ｌａｗ，ｔｈｅ ｍｉｎｉｍｕｍ ｆｅａｔｕｒｅ ｓｉｚｅ ｈａｓ ｂｅｅｎ ｓｃａｌｅｄ ｄｏｗｎ ｆｒｏｍ Ｏ．３ ５ｕｒｎ ｔｏ ０．２５ｕｒｎ ａｎｄ ｔｏ ９０ｎｍ ａｔ ｐｒｅｓｅｎｔ，ｗｈｉｃｈ ｈａｖｅ ｂｅｅｎ ａｐｐｌｉｅｄ ｉｎ ｍａｓｓ ｐｒｏｄｕｃｔｉｏｎ ｉｎ Ｃｈｉｎａ，ａｎｄ ｔｈｅ ６５ｎｍ ａｎｄ ４５ｎｍ ｔｅｃｈｎｏｌｏｇｉｅｓ ｉｓ ｕｎｄｅｒ ｄｅｖｅｌｏｐｍｅｎｔ ａｓ ｗｅｌｌ． Ｍｅａｎｗｈｉｌｅ，Ｉｎｔｅｌ ｉｓ ｃｕｒｒｅｎｔｌｙ ｌｅａｄｉｎｇ ｔｈｅ ｗａｙ ｔｏ ｐｕｓｈ ｔｈｅ ｔｅｃｌｍｏｌｏｇｙ ｔｏ ３２ｎｍ ａｎｄ ２２ｎｍ．
２．２．２ Ｅｄｇｅ ｄｅｆｏｃｕｓ。············－····３４ ２．２．３ Ｚｅｒｏ ｍａｒｋ ａｒｅａ ｄｅｆｏｅｕｓ·····································３７
第三章典型焦距异常现象及其原因分析································３９
ｐｒｏｃｅｓｓ，轻则影响量率，重则需要报废。本文的研究在于寻求能够在曝光过程 中实时监测Ｚｅｒｏ Ｍａｒｋ ａｒｅａ ｄｅｆｏｃｕｓ的方法，尽量将其影响减４，Ｎ最小的范围。
我们发现了这三种焦距异常现象发生的根本原因，并且发现它们都是可以通 过对制程参数进行监测以及在曝光机程式中进行一定特殊设定便可以减少其发生 概率的。
本课题的研究主要着重于分析焦距异常的种类及其形成的根本原因，同时我 也致力于研究如何在制程中对焦距异常现象进行监测并在曝光程式中加以调整以 预防的方法。目前常见的焦距异常大致可以归为以下三类：
１．Ｌｏｃａｌ Ｄｅｆｏｃｕｓ
Ｌｏｃａｌ ｄｅｆｏｃｕｓ是非常常见的一种焦距异常现象，它一旦发生就将会影响数量不等的 一系列晶圆，而这些晶圆都需要进行返工。本文的研究在于寻找发生ｌｏｃａｌ ｄｅｆｏｃｕｓ 的根本原因，并寻求能够在曝光过程中实时监测的方法，尽量将其影响减小到最 小的范围。