以LPE法在Si(111)基板上進行高Ge組成低缺陷密度GexSi1-x橫向磊晶研究

Study on the epitaxial lateral overgrowth of high Ge composition/low defect density GexSi1-x on Si(111) substrate by liquid phase epitaxy

林修銘(Shiou-Ming Lin)

指導教授 ： 温武義

中原大學/電機資訊學院/電子工程研究所/碩士(2019年)

https://doi.org/10.6840/cycu201900246

摘要

SiGe(矽鍺)材料在國內外的研究已行之有年，但結合Si與Ge二者良好材料特性於一身的SiGe至今仍然無法在應用端上有著廣泛的使用，其原因為欲將SiGe 材料製備於目前在應用上至為成熟的Si基板上時，由於Ge與Si間晶格不匹配達4.2%會導致SiGe磊晶層中隨著Ge成分的增加會有愈多缺陷產生，嚴重影響利用此磊晶基板所研製元件效能。
為解決上述問題，一般磊晶法需經由繁複Ge組成漸變緩衝層（每μm增加Ge組成0.1至0.2）來獲致高組成SiGe表層。本研究採用簡易LPE(Liquid phase epitaxy, 液相磊晶)法搭配使用SiO2選擇性開窗罩膜形式來進行橫向磊晶 (Epitaxial lateral overgrowth, ELO) 的技術直接求取低缺陷密度(Etch pit density, EPD)高Ge組成SiGe層。具體而言，首先在Si(111)基板表面鍍上一層約200nm SiO2後，使用設計好的光罩圖案進行微影蝕刻，由於SiGe僅會在開窗部分進行成長，因此能有效侷限晶格不匹配所致缺陷上傳至磊晶層表面，而橫向磊晶部分則可期待無缺陷產生，如此一來將可降低整體SiGe磊晶層EPD。本研究分別使用方格、圓形陣列以及平行線條三種形式窗罩進行磊晶實驗，優化其各項生長參數，並探討其磊晶成長機制，完成後樣品利用微分干涉顯微鏡(Nomarsky differential interference contrast microscopy, NDIC) 以及掃描式電子顯微鏡(Scanning electron microscopy, SEM)觀察表面結構，並使用能量散佈X射線光譜分析儀(Energy dispersive spectroscopy, EDS)確認SiGe層元素組成。

關鍵字

矽鍺 ； 橫向磊晶 ； 液相磊晶系統

並列摘要

Silicon-germanion (SiGe) materials have been studied at home and abroad for many years, but SiGe, which combines the specific material properties of Si and Ge, is still not widely used on the application side. The reason is that when one expects to fabricate SiGe on Si substrate and simultaneously use the mature Si technology, the 4.2% lattice mismatch between Ge and Si would lead to many defects in the SiGe epitaxial layer. These defects seriously affect the device performance developed by using such an epitaxial substrate. In order to solve the above problems, complicated buffer layers with gradually modulated Ge composition (10 – 20% per micrometer) are required by using conventional epitaxial methods. In this study, we used simple LPE (Liquid phase epitaxy) method in combination with SiO2 patterned film to perform directly the epitaxial lateral overgrowth (ELO) of lattice-mismatched SiGe on Si and purposed to achieve low etch pit density (EPD)/ high Ge composition SiGe layer. Specifically, after depositing a layer of about 200 nm SiO2 film on the Si (111) substrate, the lithography is performed using the designed mask pattern. Since SiGe is only grown in the window portion, the distribution of lattice mismatch defects can be effectively confined. In particular, the lateral epitaxial portion can be expected to be free of defects, so that the overall EPD of SiGe epitaxial layer can be lowered. The epitaxial experiments were carried out on three types of window coverings: square, circular and parallel-line window. The growth parameters were optimized and the epitaxial growth mechanism was discussed. After the samples were prepared, the Nomarski differential interference contrast (NDIC) microscope and Scanning electron microscopy (SEM) were used to observe their surface structure, and also the elemental composition of SiGe layer was confirmed by energy dispersive spectroscopy (EDS).

並列關鍵字

SiGe ； ELO ； LPE

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