臺灣博碩士論文加值系統

　　MOSFET元件小型化的演進過程，用來檢測「臨界電壓(VT)」及「有效通道長度(Leff)」的傳統方法，面臨到重大的考驗。關於VT的萃取法，本文的研究重點為：檢定「最大斜率的線性外插法（LE）」及「轉導變動法（TC）」的準確性。為達此一目的，以調變汲極偏壓、試片溫度、通道長度、及外加串聯電阻等四種實驗參數，將產生的相關效應作為評判的依據。獲得的主要結果有三：(1)在相同的實驗條件下，LE與TC法萃取臨界電壓值的差異小於50mV；(2)在低溫的範圍，TC法感受溫度的效應較為靈敏；(3)針對長通道元件而言，臨界電壓之溫度係數(TCTV)值在-1.01至-1.29mV/K的範圍。以計算長通道元件的TCTV值而言，與文獻發表的理論預測值-1.13mV/K 相當吻合，據此可肯定本文萃取的臨界電壓值頗為準確。關於Leff的萃取法，本文提出的改良方案為：考量漂移率函數u(VG)受到元件尺寸不同產生臨界電壓變化的影響，而變成為受超越電壓調變的函數u(VG-VT)。為了驗證此一構想的可行性，選取最簡略的β-1法，配合準確的臨界電壓值來進行檢定；並將之應用到不同製程及各式通道長度的實驗試片上。據以證實本文提出的構想，確實可提高有效通道長度的準確度。

　　In the progress of MOSFET device miniaturization, accurate determination of threshold voltage (VT) and effective channel length (Leff) by conventional methods is becoming difficult. To evaluate the accuracy of threshold voltages that will be extracted by maximum slope linear-extrapolation (LE) method and transconductance change (TC) method. We carried out a series of experiments with different conditions. The main results are summarized as follows: (1) In the same experimental conditions, the difference of threshold voltages extracted by LE and TC methods are less than 50mV. (2) In the low temperature range, TC method is more sensitive than LE method. (3) For long channel devices, the temperature coefficients of threshold voltage (TCTV) are in the range of -1.10 to -1.29mV/K. However, the results of TCTV are very closely the theoretical value of -1.13mV/K. These observations are able to prove that our experimental results of threshold voltage are accurate. For the Leff extraction, we applied the following idea: The degraded characteristics of carrier mobility is considered as a function of gate overdrive uoltage, u(VG - VT), instead of u(VG). The feasibility of this idea is examined by the β-1 method. We find that the accuracy of Leff has been improved.