結合雙載子及場效電晶體的單石積體結構之成長技術研究

Epitaxial technology for the monolithic integration of HBT and PHEMT

曾敏男(Min-Nan Tseng)

指導教授 ： 林浩雄

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.10157

摘要

本研究以有機金屬化學沉積法(Metal Organic Chemical Vapor Disposition, MOCVD )成長雙載子、場效電晶體單石積體結構(BiFET)。我們所使用的BiFET結構，其下層為AlGaAs PHEMT結構，而上層為InGaP HBT結構，其中HBT的次集極層也同時用作PHEMT結構的接觸層。我們在次集極層下成長一層heavily n-doped InGaP，作為etching-stop layer，用以控制gate recess的深度位置。整個完整BiFET結構在同一次磊晶成長中完成。我們使用電容-電壓量測、van der Pauw量測、高解析度二次離子質譜術、光激螢光譜及x-ray diffraction量測分析PHEMT的特性，並發現成長HBT的thermal cycle，會造成heavily n-doped InGaP layer及donor layer中Si原子的外擴散，致使PHEMT的片電子密度(sheet electron density)增加及電子移動率(electron mobility)下降。我們在本研究中降低HBT的成長溫度，成功地減少heavily n-doped InGaP layer及donor layer中Si原子的外擴散，使得PHEMT能夠維持原有的特性，且HBT的直流特性也能維持與較高溫成長HBT時相同的特性。

關鍵字

有機金屬化學沉積法 ； 雙載子電晶體 ； 場效電晶體 ； 片電子密度 ； 電子移動率 ； 外擴散

並列摘要

We have investigated the optimal growth conditions for integrating heterojunction bipolar transistors (HBTs) and pseudomorphic high electron mobility transistors (PHEMTs) together by metal-organic chemical vapor depositon (MOCVD). In the structure of HBT and PHEMT (BiFET), AlGaAs PHEMT is at the bottom, while InGaP HBT is on the top. The HBT and PHEMT share a heavily n-doped GaAs layer that serves as the cap of the PHEMT and the subcollector of the HBT simultaneously. A heavily n-doped InGaP layer under the HBT subcollector layer is used as an etching-stop layer for controlling the deepness of the gate recess during the PHEMT process. Through the investigation using capacitance-voltage measurement, van der Pauw measurement, high resolution secondary ion mass spectrometry, and photoluminescence and x-ray diffraction measurement, we found that the thermal cycle of InGaP HBT results in the out-diffusion of Si in the heavily doped InGaP layer and donor layer, leading to the increment in the sheet electron density and the decrement in the electron mobility, both degrading the performance of the PHEMT. After lowering the growth temperature of the HBT, Si out-diffusion is inhibited, which brings about the performance recovery of the PHEMT. Though the temperature is reduced, the DC characteristics of the HBT are still as good as those of the HBT grown at high temperature.

並列關鍵字

MOCVD ； HBT ； PHEMT ； BiFET ； electron mobility ； sheet electron density ； out-diffusion

參考文獻

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