使用閂鎖比較器快速量測臨界電壓變異數之 WAT測試電路

Abstract

隨著先進製程進步元件縮小導致製程變異影響越來越嚴重。臨界電壓是一個普遍用來量測製程變異的元件參數，在傳統的測試電路需要大量待測元件才能分析統計出臨界電壓的分布藉以此得知製程變異量。但在傳統測試電路會存在操作電流導致的壓降與周邊電路的漏電流而讓臨界電壓量測值失準並且因需要量測大量的待測元件而使得整體量測時間非常耗時。在本篇論文中提出了使用閂鎖比較器快速量測臨界電壓變異數的測試電路，測試晶片包含兩種型態各一百二十顆待測元件並使用聯華電子二十八奈米製程生產量測。

As the process technology continually scaling down, the process variation is more and more serious than before. Threshold voltage (Vt) is a commonly used for characterization process variation. To statistically characterize local process variation, threshold voltage (Vt) must be measured for a sufficiently large number of device-under-test (DUTs) in traditional array-based test structure. However, the drawback of array-based test structure like IR drop or leakage current due to large number of DUTs may affect the testing accuracy and it requires extremely long testing time for measured Vt. In this paper, we present a novel latch-based test structure that could rapidly obtain the Vt variation and without complex compensation circuit for the mentioned drawbacks. A test-chip containing 120 NMOS and 120 PMOS DUTs has been fabricated in 28nm bulk CMOS process technology.