為了將異質接面雙極性電晶體操作頻率提升至兆赫(THz)等級，則必須將元件尺寸微縮至次微米等級，以降低元件的RC 延遲時間，來達到THz電晶體的目標。本論文主要為討論在元件的微縮過程中 ，將遭遇到的製程 瓶頸及解決方法。我們透過電子束微影技術並利用多層光阻組合結構，成功的將射極金屬線寬微縮至150 奈米，並將射極金屬的外觀形貌由長方體輪廓改為上寬下窄的T 形輪廓以提高基極金屬自我對準的製程良率，且提出一製作射極金屬側壁的製程，能避免次微米元件在濕蝕刻製程時容易遇到的電化學效應發生，使元件在蝕刻至基極材料表面時，射極平台周圍不會殘留多餘的射極材料，導致射極定義線寬失真。除此之外，我們還發展了一套利用苯並環丁烯(BCB)材料，以旋轉塗佈加上回蝕刻的方式，來完成的自我對準基極平台定義製程，相對於利用成長二氧化矽或氮化矽來完成的基極平台定義製程，能避免因利用電漿成長薄膜時所造成的元件增益衰退現象，且更能有效保護射極平台及射極平台與基極金屬間的基極材料表面，使元件能在不傷害特性的條件下以濕蝕刻的方式蝕刻至次集極材料表面。因此，本論文的結果將有助於未來次微米異質接面雙極性電晶體的元件製作，使元件能順利達到THz 之目標。To achieve terahertz operation, the emitter size of heterojunction bipolartransistors (HBTs) must be scaled down to sub-micron meter to minimize theRC delay time. In this work, we focus on solving the bottleneck of fabricatingsub-micron meter HBTs.By using e-beam lithography technology and multi-layer photoresistprocess, an emitter metal with minimum linewidth of 0.15 μm has beendemonstrated. Moreover, a unique T-shape emitter is proposed to improve theyield of self-aligned base metallization process. We have also developed a SiO2dielectric sidewall process to avoid the electrical-chemical effect during theemitter mesa etching while maintain the effective emitter linewidth. Base on theSiO2 sidewall technology, we propose a novel self-aligned base mesa processusing spin-coated Benzocyclobutene (BCB). The use of spin-coated BCB canavoid the ion bombard problem during the plasma etching process and leads to alow damage surface of the device under process. Electrical measurements showthat the cross point of the base and collector currents in the Gummel plot can besuppressed for 2 to 3 orders of magnitude, which indicate that the technologydeveloped in this work will greatly benefit the realization of THz HBTs.
