Bonding/Barrier Layers on Bismuth Telluride (Bi2Te3) for High Temperature Applications

論文發表人：林雯珮（加州大學爾灣分校材料系博士班）

 

http://www.ectc.net/program/2010/session10.cfm

 

在這個研究中，我們識別不同材料並研發了碲化鉍熱電材料在高溫運用上的連接與阻絕層。我們嘗試了以鈀、鎳、鎳/金、銀、鈦/金等不同的材料沈積在碲化鉍上，並以掃描式電子顯微鏡與能量散射X射線光譜儀分析。研究結果顯示，以熱蒸發沈積之100奈米鈦/100奈米金覆合層有最好的功能。這層鈦/金覆合層有良好的階梯覆蓋率且與其下方的碲化鉍有良好的附著性。而且，此覆合層也與其上方的銀接合層有著良好的鍵結能力。在我們進一步的加熱測試分析中也發現，此鈦/金覆合層能夠在250℃下運作200小時候仍維持其作為一個阻絕層的良好效果，禁止其自身與上方的結合材料，銀、鎳、金等擴散進入碲化鉍 。另外，這整個連接層與阻絕層的結構也能承受結合製程過程中因熱膨脹系數差異所造成的應力。因此，此研究成功的研發一個碲化鉍熱電材料高溫運用之有效的連接與阻絕層。

 

In this research, a fundamental study is conducted to identify the materials and processes for producing bonding/barrier composites on Bi2Te3 for high temperature thermoelectric applications. Pd, Ni, Ni/Au, Ag, and Ti/Au were deposited and evaluated using scanning electron microscope (SEM) and energy dispersive X-ray (EDX). A thermal evaporated, 100nm Ti/100nm Au composite gave the most promising result. The Ti/Au thin films have a good step coverage and bonding to Bi2Te3.  They also bond well to a thick electroplated Ag over-layer. No Ti or Au diffusion into Bi2Te3 was observed even after annealing at 250ºC for up to 200 hours. The whole barrier structure also sustains CTE mismatch between the alumina substrate and Bi2Te3 chip during the bonding process.