氫在HBT元件中所造成的穩定度問題之特性研究

Abstract

本論文主要研究的主題是針對金屬有機化學氣相沉積(MOCVD)所磊晶的碳攙雜雜異質接面雙載子電晶體(Carbon-Doped Heterojunction Bipolar Transistor)在元件首次上所造成的基極電流暫態現象做描述與分析討論。由於在磊晶的過程中無可避免會有碳與氫的結合,經由熱分解,釋出部份的氫離子,增加了基極的覆合電流,影響元件的穩定度。在我們的討論中,我們提出四種可能機制,利用其所代表的方程式對量測的基極電流做曲線近似,藉以釐清運作的行為模式。接著,我們討論溫度效應對元件的影響。對於首次量測後的元件,欲使其暫態現像能重覆出現,我們可利用200。C-250。C的溫度加以回火,使氫離子脫離碳的束縛而釋出少許,便可使暫態效應一再產生,並透過不同的溫度回火所造成現象回復比例的差異推算出欲釋出氫離子所需的反應活化能。隨後,我們討論若在元件製程前, 先對材料做高溫的回火,用以驅離基極中與碳結合的氫離子,這樣便可使元件免於暫態效應的產生。

In this thesis,we focus on the transient phenomenon which only show up on virgin device of MOCVD (metal-organic chemical vapor deposition) grown HBT (hetero-junction bipolar transistor). Because there is no way to inhibit hydrogen from incorporating with carbon acceptor,by theraml decomposition,hydrgogen will be released to increase base recombination current and affect the stability of the device.With our analysis and discussion ,we hope that the stability of the device will be improved. We provide some physical model for curve fitting in order to understand the overall physical operating mechanism. And,we use thermal treatment under no bias to look forward to the properly post-annealing temperature for re-initiation. After the transient phenomenon show up,we can anneal device with 200。C-250。C for re-initiation.We can also extract the activation energy by varying the annealing temperature. And then ,we discovery that with a suitable pre-annealing condition before process ,the transient effect will be eliminated .