複晶矽薄膜電晶體特性與應用的探討

Abstract

以傳統標準的互補式金氧半(CMOS)與雙極性互補式金氧半(BiCMOS)製程技 術製造複晶矽薄膜電晶體,元件的特性及電性參數已被完整的觀察並研究, 包括小尺寸效應和漏電流現象在內.同時被閘極電壓控制的載子移動率亦 將探討之.這種與CMOS/BiCMOS製程相容的複晶矽薄膜電晶體可應用在縮小 電路面積成為非常重要考量的情況,因為它可以實現三度空間的電路集積. 基本的理念在於如果薄膜電晶體可在任何製程被製造,則它的應用價值會 大大提高.另外,它的光敏感性很顯著,光電流與閘極電壓,汲極電壓,與通 道參雜濃度的相關性皆被研究,其牽涉到的物理機制也已闡明.這種對光敏 感的現象可被應用在光感測器或光激發元件的設計上,而且可集積在晶片 上. In this thesis, the poly-Si TFTs devices are fabricated by conventional standard CMOS and BiCMOS processes. The char- acteristics and electrical parameters of the devices have been obsreved and studied, including small dimension effect and off- current behavior. And the gate-controlled mobility is also characterized and explained. These CMOS/BiCMOS com- patible poly-Si TFTs can be used in the situation where chip area reduction of circuits is a very important concern, be- cause of its ability of three-dimensional integration. The basic application idea is that if the TFTs can be realized by any process, it will become more applicable in more situ- ation. It has also been shown that the photosensitivity of the poly- TFTs is significant. The dependences of the photocurrent on gate voltage, drain voltage and channel doping are studied, and the physical mechanisms are given.The excellent photosen- sitivity may be applied to the design of light sensor or light trigger elements and integrated on CMOS/BiCMOS chip.