熱電材料與擴散阻障層在電流影響下的界面反應研究

Interfacial Reaction between Diffusion Barrier and Thermoelectric Materials under Current

羅立晨(Li-Chen Lo)

指導教授 ： 吳子嘉

國立中央大學/工學院/化學工程與材料工程學系/碩士(2012年)

摘要

本研究主要討論熱電材料n-Bi2Te3與擴散阻障層無電鍍鎳磷在電流影響下之界面反應。以自製三明治結構Sn/Ni-P/n-Bi2Te3/Ni-P/Sn模擬商用熱電模組通入電流後之界面反應，無電鍍Ni-P用以防止SnTe IMC快速生成於界面處，我們將觀察擴散阻障層的消耗及介金屬化合物(IMC)的生成，這些IMC將會影響熱電模組的機械性質與電性並可能降低熱電模組的可靠度。
首先以不同電流密度和不同基板加熱溫度繪出熱電模組失效表格，並以此表格為依據，設定電流密度100 A/cm2 加熱溫度150 °C為實驗條件進一步觀察通電時間0、50、100、150小時各階段界面形貌，又加入純退火150 °C以釐清電遷移對系統之影響。擴散阻障層Ni-P在150小時通電過後相變化成Ni3P並產生許多柱狀Kirkendall void，Ni-P/n-Bi2Te3界面經過退火和通電後都生成了NiTe和Bi4Te5 IMC，被電遷移所推動之陰、陽極處Ni原子與Te原子反應生成NiTe IMC，Ni-P/n-Bi2Te3界面處的Te被消耗使得Bi2Te3裡Bi與Te兩元素比例改變，因此結構重組成Bi4Te5。電子流幫助了Ni擴散進入n-Bi2Te3，通電後陰極處之NiTe和Bi4Te5 IMC都比陽極厚，原因是電子流推動Ni原子從陰極往陽極方向，在此系統中陰陽極厚度差異是來自於電遷移的影響。

關鍵字

無鉛銲料 ； 擴散阻障層 ； 電遷移

並列摘要

This research investigated the interfacial reaction between the diffusion barrier, Ni, and the thermoelectric materials. Ni is a good barrier between Pb-free solder and n-type bismuth telluride (Bi2Te2.7Se0.3) thermoelectric material to prevent the rapid formation of brittle SnTe intermetallic compound (IMC). We use sandwich structure Sn/Ni-P/n-Bi2Te3/Ni-P/Sn to simulate the interfacial reaction under current. The depletion of diffusion barrier and the formation of intermetallic compound (IMC) will be concerned. Different current densities were applied to the system to investigate the electromigration behavior of the systems at various temperatures. The experiment condition was set at current density 100 A/cm2 and heating temperature 150 °C. The results showed that the Ni-P layer crystallized to Ni3P and left lots of Kirkendall void after current stressing. Instead of SnTe, NiTe and Bi4Te5 formed at the interfaces. These IMCs would affect the mechanical and electrical properties of the thermoelectric module.
The aging sample at temperature 150 °C is prepared to determine the effect from electromigration. The results showed that the thickness of NiTe and Bi4Te5 at the cathode were thicker than at the anode. Due to the electromigration, Ni atoms diffused into thermoelectric material greatly. The Ni atoms diffused from cathode to anode driven by electrical current.

並列關鍵字

diffusion barrier ； electromigration ； lead-free solder

參考文獻

46. A. S. Nowick and J. J. Burton, “Diffusion in Solids: Recent Developments”, J. Mater. Sci., New York, 6, 329 (1976)

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