功率元件接觸面鋁金屬濕蝕刻製程研究

鋁金屬應用於半導體元件除作為元件內連接線路外，另一用途在接觸面形成歐姆接觸讓封裝後的導線能減少金屬與半導體界面電壓差形成良好的傳導。而鋁金屬接觸面其特性決定於接觸面積與接面處鋁矽合金狀況而對線寬無特殊要求。濕式蝕刻相較於乾式電漿蝕刻能提供高選擇比、高PPH、設備簡單及低成本特性，因此評估金屬接觸面濕式蝕刻能降低生產成本提高產能。本研究透過統計軟體進行實驗設計預期找出理想的鋁金屬濕式蝕刻槽體設計及製程參數。透過部分因子設計及實驗結果分析，當槽體設計為真空系統可以即時移除反應表面氣體減少遮蔽效應，同時加入robot擺動增加表面蝕刻液置換增改善均勻性，而控制蝕刻溫度在較高溫度能增加鋁金屬蝕刻率及表面均勻性。在經過 20 次驗證以統計製程管制(Statistical process control, SPC)手法驗證鋁膜蝕刻的製程能力為1.12 ，其製程呈穩定趨勢可以實際應用於量產。未來利用自動補酸系統可以控制硝酸及磷酸濃度變化，減少蝕刻速率衰減，更進一部延長蝕刻液使用壽命與製程能力提昇。

關鍵字

鋁金屬；歐姆接觸；統計製程管制

並列摘要

Applications of Aluminum are used in semiconductor device as a connection between layout and also as a good ohmic contact between semiconductor surface and metal layer. Aluminum ohmic contact is related with contact area and silicide density, and it has no CD loss (Critical dimension loss) concern. Wet etch method can provide more high selectivity, high PPH (productive per hour), simple equipment design and low cost compare to plasma etch. So the evaluation of aluminum by wet etch can reduce cost and it increases the output for mass production. This approach was applied in D.O.E to analyze and optimize the aluminum wet etch process and equipment design. The obtained result showed that the high vacuum etch tank can remove reacted bubble immediately to avoid masking effect. The installation of robot system and keep tank temperature around 50 °C, which is more stable, uniform and faster etch rate. After 20 wafer mass run, Cpk value shows 1.12 which was confirmed from SPC chart. This result can be implemented to the mass production. In future, the installation of chemical auto spiking system can maintain the concentration as constant and the process capability will be better.

並列關鍵字

Aluminum ； ohmic contact ； SPC

參考文獻

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國際替代計量

功率元件接觸面鋁金屬濕蝕刻製程研究

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