以細微結構與光學系統調變誘發側向結晶

Abstract

在平面顯示器中，多晶矽薄膜電晶體的效能會被元件通道中的晶粒邊界劇烈地影響。這些晶粒邊界會降低載子遷移率並讓漏電流上升，為了減少這個效應，我們使用側向結晶的方式來控制通道中的晶粒邊界。在我們的研究中，使用三種側向結晶方式來控制晶粒大小，結晶方向與成核點位置，預期會得到較大的晶粒大小，晶粒排列方向一致性高以及成核點位置的精準控制。

第一種方式是金屬層反射層，它能有效的讓結晶方向垂直於金屬側邊。第二種方式是奈米洞結構，它能有效的將成核點控制於奈米洞側壁邊緣，並且在晶粒成長的過程中，讓晶粒互相碰撞，有效的把晶粒邊界控制在兩個奈米洞之中間區域。第三種方式，單狹縫繞射，這可以調變雷射光的空間強度來誘發側向結晶，並將側向結晶長度拉長至1.3微米，配合熱儲存槽結構，更可以將側向結晶長度拉長到2微米，這會是原本的1.5倍。在論文中，我們將三種雷射誘發側向結晶方法的熱流模擬結果與實驗結果還有熱儲存槽效應做討論與比較。

The performance of poly-Si TFT devices in panel display is severely influenced by grain boundaries in the channel region. The boundaries would decrease the mobility and increase the leakage current. In order to reduce these effects in poly-Si TFTs, the grain boundaries would be controlled by lateral laser crystallization methods. In our research, there are three methods to control grain growth direction, lateral grain size and nucleation positions. We expect to obtain larger grain growth length, well-aligned crystallization direction and more precise nucleation position by lateral laser crystallization methods.

The first method metal is reflection layer, which could well arrange the grain growth direction perpendicular to edges of metal patterns. The second method is nano-hole structure, which could control the nuclei at the sidewall of nano-holes and the grain boundaries would exist in the middle region between nano-holes due to grain growth colliding to each other. The third method single-slit diffraction, which modulates the laser intensity distribution to induce lateral grain growth could enlarge lateral grain growth size to 1.3μm without any additional structural design. With a SiO2 capping layer lateral grain length would be enlarged to 2μm, which is about 1.5 times that without a heat reservoir layer. The relationship between heat flux simulations, and experimental results of three lateral crystallization methods and the effect of heat reservoir layer would be discussed and compared.