在鹼性雙氧水系統中過硫酸銨與奈米級二氧化矽對銅/釕之化學機械研磨研究

Study of Copper / Ruthenium Chemical Mechanical Polishing in alkaline hydrogen peroxide system with ammonium persulfate and nanoscale silica

陳伯瑋(Po-Wei Chen)

指導教授 ： 顏溪成

國立臺灣大學/工學院/化學工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201600453

摘要

本研究分三部份進行。首先探討由氫氧化鉀所調整的pH9之鹼性雙氧水系統之下之銅/釕之腐蝕電化學，接著模擬銅與釕同時在化學機械研磨情形搭配不同比例之過硫酸銨以及未添加/添加2wt%之15nm-20nm之奈米級二氧化矽在雙氧水系統之下對於表面性質之交互影響；最後觀察其表面性質；實驗中除了利用直流極化技術了解基本腐蝕電化學性質，也使用五位數的數位電子秤量測銅與釕同時經由化學機械研磨處理前後之重量差了解其研磨移除率(Material Removal Rate, MRR)進而比較銅/釕之移除選擇率，並藉由原子力學顯微鏡(Atomic Force Microscope, AFM)了解其表面粗糙度(Rq)以及使用掃描式電子顯微鏡(Scanning Electron Microscopy, SEM)觀察其表面型態。
實驗結果顯示，藉由氫氧化鉀所調整的pH 9之鹼性雙氧水系統之下，透過電化學測量得知 7wt%的雙氧水比例可以有最大的腐蝕速率；以此為基礎進行不同比例之過硫酸銨測試，發現在7wt%的雙氧水與3wt%過硫酸銨可以有最接近1的移除選擇率，約為0.926，銅移除率約為2.305nm/sec，而釕移除率則約為2.488nm/sec；表面粗糙度的部份，銅由原先約55.8nm下降至9.12nm，釕則由約42.5nm下降到7.78nm。接續探討加入2wt%之15-20nm之奈米級二氧化矽觀察其對於移除率與表面型態之影響，發現7wt%的雙氧水與1wt%過硫酸銨搭配2wt%的15-20nm之奈米級二氧化矽可以擁有較接近1的的移除選擇率，約為0.811，銅移除率為3.457nm/sec，釕移除率為4.265nm/sec，表面粗糙度分別降為則下降至1.01nm與6.97nm；然而，若權衡所有的需求，則7wt%的雙氧水與2wt%過硫酸銨搭配2wt%的15-20nm之奈米級二氧化矽，擁有較好之成果，其選擇比為0.709，銅移除率為4.115 nm/sec，釕移除率為5.805nm/sec，其銅與釕之表面粗糙度分別能下降至6.54nm與2.06nm。

關鍵字

銅 ； 釕 ； 電沉積 ； 化學機械研磨 ； 表面粗糙度 ； 移除選擇率

並列摘要

The study can be separated to three parts. The first part focus on probing the electrochemical factors when copper and ruthenium film reacting in different concentration of hydrogen peroxide slurries, adjusting to pH9 by sodium hydroxide. For the second part, we mimiced the real situation when copper and ruthenium film are processed during the CMP by using different concentration of ammonium persulfate in hydrogen peroxide slurries, which is adjusting to pH9 by sodium hydroxide, and then we probe the variation of their surface patterns. For the last part, we add fixed amount of 15-20nm nanoscale silica to investigate its surface patterns. In the experiment, not only we use DC polarization technique to find out its electrochemical factors, but we also use Atomic Force Microscope and Scanning Electron Microscopy to probe its root mean square surface roughness and the surface patterns.
For the results of the experiments, the first part showed that when the slurries adjusting to pH9 with sodium hydroxide, could have the best corrosion rate with 7wt% hydrogen peroxide for either copper or ruthenium film. Based on the results of the first part, we could find out that slurries with 7wt% hydrogen peroxide and 3wt% ammonium persulfate, adjusting to pH9 with sodium hydroxide, could demonstrate a better removal rate ratio, 0.926 ,of the copper/ruthenium removal rate, with the copper one was about 4.115 nm/sec and the ruthenium one was 5.805nm/sec. For the surface roughness, the copper one was declined from about 55.8nmto 9.12nm while the ruthenium one was declined from 42.5nm to 7.78nm. After adding 2wt% 15-20nm nanoscale silica, we found out that pH9 slurries with 7wt% hydrogen peroxide, 1wt% ammonium persulfate and 2wt% 15-20nm nanoscale silica, with removal rate ratio was 0.811. The copper removal rate was 3.457nm/sec and the ruthenium removal rate was 4.265nm/sec. The surface roughness was declined to 1.01nm and 6.97nm respectively. For requesting a proper result for the use of industries, the pH9 slurries with 7wt% hydrogen peroxide, 1wt% ammonium persulfate and 2wt% 15-20nm nanoscale silica would be the best choice, which removal rate ratio is 0.709, of the copper/ruthenium removal rate, with the copper one was about 4.1153nm/sec and the ruthenium one was 5.80493nm/sec. For the surface roughness, the copper one 6.54nm while the ruthenium one was 2.06nm.

並列關鍵字

copper ； ruthenium ； electrochemical deposition ； CMP ； removal rate ratio

參考文獻

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