一种能提高DRC友好性和CMP形貌的冗余金属填充方法

化学机械研磨(CMP)被广泛用于铜镶嵌工艺,研磨后铜的厚度和表面形貌对65纳米以下的工艺显得越来越重要,厚度和形貌的变动会对芯片良率和性能造成恶劣影响,所以必须在设计时就进行慎重的考虑。众所周知,插入冗余金属是提升CMP形貌的一个好方法,通常基于规则的方法广泛用于65纳米及以上工艺中,但是该技术在比较先进制程中显示不出其优越性。本文阐述了一种基于模型的冗余金属填充方法,它是根据设计版图中的周围环境用计算机算法来填充。这一方法的优点有以下几方面:在设计规则检查(DRC)中更少的违规数量,更密集的图形密度分布和更少的填充图案数量,更小的密度和周长梯度。在使用40纳米工艺的晶圆上,基于模型方法得到的表面平坦度与基于规则的填充方法相当,但是比公开的其它填充方法要好。

A Model Based Dummy Fill Method for Improving Design Friendliness to DRC and CMP topography

Chemical Mechanical Polishing（CMP） has been used in copper（Cu） damascene process.The inherent thickness and topography variations become an increasing concern for today＇s designs running through advanced process below 65 nm.Excessive thickness and topography variations can have major impacts on chip yield and performance,so they need to be considered during the design stage.It is well known that dummy pattern insertion is a good method to improve CMP topography.Normally rule based dummy fill approach is used for 65 nm technology and above,but it becomes less effective for advanced technologies.In this paper,we will demonstrate a model based fill approach of dummy fill,which insert dummy with a computer algorithm according to adequate windows of layout context.Our new method shows advantage over rule based one on the following aspects：less density rule violation in DRC sign off,more concentrative density distribution and less fill amount,smaller density and perimeter gradient.Surface flatness measured on 40 nm silicon wafers is comparable between the two methods,but our method is better than other published dummy fill methods.