濺鍍銅膜之氧化行為研究

因應銅導線晶片封裝打線(wire bonding)之需求，本研究以濺鍍方式於矽晶圓表面鍍著銅薄膜，探討濺鍍銅膜於大氣氣氛中加熱(90-200℃)之氣化機制，以了解銅墊於打線條件下之氣化行為。首先於矽晶圓表面濺鍍鈦膜，再濺鍍銅膜以提昇銅膜與矽晶圓之黏著性，該晶圓經切割、黏晶製程後，置於熱音波打線機之加熱平台並設定不同之加熱溫度與時間，隨後以化學分析電子儀(ESCA)分析氧化膜之組成與生長厚度，藉以判斷氧化物組成。生長厚度與加熱溫度、時間之關係。結果得知，銅膜之氧化物成長厚度與加熱溫度成正比，且氧化膜之表面型態隨加熱溫度提高越顯粗糙，推斷銅膜氧化物之形成機構為銅原子經氧化膜之缺陷處擴散至薄膜表面與大氣之氧離子形成氧化膜，當銅氧化膜表面越顯粗糙時，其形成之缺陷處增加，加速氧化膜之成長。由化學分析電子儀量測銅、氧離子之束縛能(binding energy)偏移，並配合撮合曲線(curve fitting)結果，判定銅膜表面之氧化物型態為氫氣化銅(Cu(OH)2)，因該薄膜置於大氣下進行加熱，銅離子與大氣之氫氣根離子生成該氧化物；而於銅膜表面下方各處，其氧化物型態為氧化銅(CuO)。

關鍵字

銅薄膜；濺鍍；化學電子儀；銅膜氧化物分析

並列摘要

Investigation on the oxidation of sputtered copper film on silicon wafer was conducted in order to understand the oxidation behavior of Cu-film taking place during thermosonic wire bonding process. Cu sputtered blank chips were heated at 90℃-200℃ under atmospheric conditions. Compositions and thickness of the oxide layers were analyzed by using ESCA. Higher oxidation temperature resulted in higher growth rate of the oxide layer. The surface of oxide layer revealed an increasing coarser morphology at higher oxidation temperature. It was proposed that the copper atoms migrated to the surface by passing through the defect sites of the oxide layer and combining with oxygen atoms to form copper oxides. This migration process was facilitated by higher ambient temperature. By evaluating the binding energy of Cu and O ions and through curve fitting, two kinds of oxides could be determined in the oxide layer. Oxide film formed on the top of the surface was identified as Cu(OH)2 while oxide beneath the surface was identified as CuO.

並列關鍵字

Cu film ； Sputtering process ； ESCA ； Oxide analysis ； Wire bonding of Cu-chip

國際替代計量

濺鍍銅膜之氧化行為研究

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