具晶圓級封裝技術之高內部量子效率與低效率下降率之氮化鎵發光二極體開發計畫( I )

Abstract

由於石油價格高漲及石化原料燃燒造成的溫室效應，如何更有效率的使用有限的能源是 目前最重要、最熱門的研究方向。目前在能源的使用上，先進國家在照明上的能源使用比例 都約在20%以上，因此，若是能夠使用更高效率的照明燈具，對節能減碳的實現，有非常顯 著的幫助。 本整合型計畫將以實現高效率的LED 照明系統為主，結合來自交大、成大和台南大學三 所大學共七位教授共同合作，針對整個氮化鎵發光二極體從磊晶、製程到封裝分成三個子計 畫進行完整系統性的研究。在子計畫一的磊晶研發方面，將結合交大和成功大學磊晶設備的 資源，在奈米級結構上利用HVPE 和MOCVD 等磊晶設備進行再磊晶，提升磊晶品質同時減 少GaN LED 效率在高注入下極具降低的情形。在子計畫二的元件製作上，本計畫針對高散 熱、高萃取效率的垂直式發光二極體進行研究，其中包括薄膜式、覆晶式和整合HVPE 的新 式樣元件結構等。除元件本身製程技術的改進外，由於垂直式GaN LED 相較於傳統的元件 結構更容易進行晶圓級製程的整合，因此本整合計畫第三個子計畫便是將垂直式GaN LED 元件與矽基板整合進行晶圓級封裝，導入螢光粉塗佈、晶圓接合，發展低成本的晶圓對晶圓 封裝技術。藉由本整合計畫的整合和發展，將能夠發展出一個高效率、低成本的LED 照明系 統。

Because of the significant increase of petroleum and greenhouse effect caused by the carbon dioxide generated from the burning carbon-related fuel, using the limited nature resource more efficiently becomes the most important and attractive research area. Generally, there was over 20% energy usage for general lighting especially in the developed countries. So, it would contribute to a great help on conserving energy and minimizing the carbon footprint if higher efficiency lighting devices were applied in our daily life. In this project, we combine eight professors from NCTU, NCKU and NUTN for the realization of high efficiency LED lighting system. We would performed a systematic research from epitaxial growth, chip process and device package to improve the device performance entirely. For the epitaxial crystal quality improvement of GaN LED, we would develop a novel method by HVPE and MOCVD overgrowth on nano-patterned substrate. It not only improve the internal quantum efficiency but also well for reduce the droop phenomenon. After we optimized the LED crystal quality and minimize the droop phenomenon, we proceed to use it for the vertical LED process. Three different types, including thin-GaN, flip-chip and HVPE-GaN, of vertical LEDs will be developed in this project. These types of vertical LEDs could solve heat dissipation issues by bonding to a Si or GaN substrate and enjoyed good light extraction efficiency. In addition to the chip fabrication technique improvement, we further applied these devices into a wafer-level package process. Because of the vertical current injection characteristic, these vertical type LEDs are especially suitable for the wafer-level process. We will introduce the phosphor conformal coating and wafer bonding to realize the low cost wafer-level package. All chosen technologies are suitable for mass-production with high productive value. We hope to help Taiwan LED industries built-up self developed techniques to increase international visibility and enhance international competitiveness.