紅外線影像應用之影像讀取電路設計及矽化鉑偵檢元件研製

Abstract

本論文主要研究紅外線影像擷取應用之影像讀取電路設計及高量子效率矽化鉑偵檢元件研製。針對紅外線影像技術在國防科技尋標系統低雜訊、可調變影像輸出頻率及隨機讀取影像的性能需求下，我們成功的研製出512´512像素矽化鉑隨機讀取電荷集積式電荷耦合焦平面陣列元件( Random Line-selected Charge Accumulation CCD readout PtSi SBD focal plane array)，此一影像讀取電路不僅改善傳統電荷耦合傳輸元件(CCD)的限制，同時並俱備MOS multiplexer 隨機讀取訊號的優點，提供紅外線影像系統在設計上的空間。為獲得高品質的紅外線影像，如何提昇偵檢元件的性能是一重要課題。在本論文中，我們利用電穿透式電子顯微鏡的分析將矽化鉑薄膜在不同成長條件下的結構特性及成長機制加以界定，並根據光電特性的量測結果配合偵檢元件光電反應模型，成功的將受激載子在響應過程中的散射機制加以量化，並與薄膜結構特性獲得一致性的結論。根據量化結果，我們得到為獲得高量子效率矽化鉑偵檢元件，矽化鉑薄膜在成長過程中必須俱備(1 1)的成長相位、大的矽化鉑晶粒，以及適當的薄膜厚度。在此一條件下，我們研製出量子效率為1.3%的矽化鉑偵檢元件。

The PtSi Schottky Barrier Detector (SBD) has been found applications in the detection window of 3 to 5 mm. Due to its compatible fabrication process with standard silicon wafer process, large two-dimensional PtSi arrays combined with Charge Coupled Devices (CCD) readout structure have been able to be achieved. However, for tactical defense application, high frame rate and random access readout requirements are hard to be fulfilled in the conventional CCD design. Also, the microstructure effects on the detector performance have not been fully understood yet. These motivated the studies of both design a novel CCD readout structure and discover a thin PtSi film on its microstructure versus performance relationship. Those studies can govern the potential for increasing the quantum efficiency of the detector through process optimization. In this dissertation, a 512 ´ 512-element Random Line-selected Charge Accumulation (RLCA) charge coupled device readout structure has been proposed to fulfill high frame rate and random accessable readout format for infrared image application. The design concepts, merits, and image processing of this readout architecture are addressed. Since this unique readout structure, a frame rate of up to 240 frames/second can be achieved for 128 ´ 128 of the SBD array under 5 MHz of clock frequency. This architecture not only maintains the advantages of conventional CCD structure but also provides the capability to readout any portion of the array. A formation window for high quantum efficiency PtSi film with different growth condition also developed. Through High-Resolution Transmission Electron Microscopy (HRTEM) and electron diffraction analysis, the thin PtSi formation mechanism with different formation conditions has been identified. Furthermore, it has been very successfully to discover a correlation on the microstructural characterization of PtSi film to its electrical and optical performance. A physical explanation theory has been proposed to describe the film quality versus its internal photoemission mechanism on each growth condition. Finally, the published theoretical models of the internal photoemission have been applied to characterize the microstructure of silicide film for different formation conditions. Based on this investigation, a quantum efficiency of higher than 1.3% at 4 mm wavelength can be obtained under the condition on the elimination of native oxide effect and short anneal time.