多孔材料的低温刻蚀技术

Cryogenic etching of porous material

随着半导体芯片特征尺寸的持续减小,低介电常数的多孔材料在微电子领域得到广泛应用.然而,多孔材料在等离子体刻蚀工艺中面对严峻的挑战.等离子体中的活性自由基很容易在多孔材料内部扩散,并与材料发生不可逆的化学反应,在材料内部造成大面积损伤.本文介绍了业内比较前沿的低温刻蚀技术,通过降低基片台的温度,使得刻蚀产物或者刻蚀前驱气体在多孔材料内部凝结成液态或者固态,进而在等离子体刻蚀过程中,阻止活性自由基在材料内部的扩散,保护多孔材料免受损伤.刻蚀完毕后,再通过升高基片台的温度,使凝结物挥发,得到完整无损的刻蚀结构.这一刻蚀技术只需要控制基片台的温度,无需增加工艺的复杂度以及调整等离子体状态,在半导体工艺中具有较好的应用前景.

With the shrinkage of chip feature sizes,porous materials are widely used in microelectronics.However,they are facing severe challenges in plasma etching,as the reactive radicals can diffuse into the interior of material and damage the material,which is called plasma induced damage.In this paper,we review two kinds of etching processes based on low chuck temperature,i.e.cryogenic etching.By lowering the chuck temperature,either the etching by-products or the precursor gas can condense in the porous material,and thus preventing the radicals from diffusing and protect the material from being damaged by plasma.The technology of cryogenic filling inside the porous material is simple but effective,which allows it to have a good application prospect.