N型非晶矽薄膜電晶體數位電路之極低電壓與靜態電流測試

Abstract

此論文提出包括極低電壓與靜態電流的可靠性篩選策略來針對工研院所製作之8μm 製程非晶矽薄膜電晶體數位電路，並且利用burn-in 來驗證極低電壓與靜態電流所篩選的結果。由於非晶矽薄膜電晶體的可靠度不如傳統矽晶片電晶體，以burn-in 來作為傳統的可靠度測試方法可能會因提高電晶體的門檻電壓而降低良好晶片的效能，甚至破壞晶片。極低電壓與靜態電流測試因為無破壞性且成本較低而成為取代burn-in 的常用方式。在實驗中此論文使用pseudo-NMOS 的NOR-NOR 以及用pseudo-NMOS 的邏輯陣列所設計之乘3 器作為測試用電路，而正常操作電壓與極低電壓分別為10V 與7V。實驗結果顯示出極低電壓可從58 片非晶矽薄膜電晶體電路中篩選出2個通過正常電壓測試的不可靠電路，相對地靜態電流則無法有效篩選出通過正常電壓測試的不可靠電路。

This thesis presents a strategy, including very-low-voltage (VLV) and quiescentpower supply current (IDDQ) testing, for reliability screening of amorphous silicon thin-film transistor (a-Si TFT) digital NMOS circuits manufactured with 8μm a-Si process by Industrial Technology Research Institute. In addition, 200 seconds and 30V stress is applied for burn-in to verify the experimental results of VLV and IDDQ testing. Because the reliability of a-Si TFT is not as good as traditional Si-process,burn-in may reduce the performance of good circuits due to threshold voltage shift.Even burn-in destructs good circuits. VLV and IDDQ testing are well-known alternatives to burn-in because they are non-destructive and low cost. In our experiments, pseudo-NMOS NOR-NOR and multiplied-by-3 NOR-NOR programmable logic array are the circuits under test (CUTs), and the nominal voltage and VLV are 10V and 7V, respectively. Our experimental results show that VLV can screen out 2 unreliable circuits passing nominal voltage testing from 58 a-Si TFT circuits. Relatively, IDDQ is not effective in screening out unreliable circuits passing nominal voltage testing.