應用於功率積體電路之700伏特LIGBT元件設計與結構改善

Abstract

功率積體電路即是將高壓功率元件與低壓控制電路整合於同一晶片上之積體電路，提供更完整的功能與較低的成本。由於橫向式絕緣閘雙極性電晶體（LIGBT）為橫向結構，並具有耐高壓與導通大電流的特性，使其適合應用於功率積體電路。元件耐壓方面，主要為利用RESURF的原理來提高耐壓。元件關閉時，內部少數載子殘留的現象使得其關閉延遲，造成較慢的切換速度而限制了應用範圍，關閉時間在10μs的數量級。本論文將針對傳統LIGBT元件結構關閉延遲的缺點，參考採用兩種改善結構，分別為陽極短路結構與間斷式陽極結構，將關閉時間降至200ns的數量級。相對於傳統LIGBT結構，兩種改善結構雖然加快關閉速度，卻也增加導通電阻與Onset voltage。其中，間斷式陽極結構的導通電阻與Onset voltage則低於陽極短路結構，並且在元件使用面積上更是節省20~30%。本論文亦提出元件製程參數設計流程，兩種改善結構的製程與傳統LIGBT結構相同，且配合台灣目前的基本製程，不需再多加額外光罩。模擬方面則使用Medici與Davinci電性模擬軟體，對傳統LIGBT結構以及兩種改善結構進行模擬與分析。

The power integrated circuit (PIC) combines high-voltage power devices with low-voltage circuit on a chip. PICs provide total solutions for the implementation of power systems. The Lateral insulated-gate bipolar transistors (LIGBTs) have the lateral structures that make them the promising power devices for PIC applications due to their high breakdown voltage, high current handling capability, and applicable isolation capability. In the primitive LIGBT, the principle of RESURF (Reduced Surface Field) is applied in the improved LIGBT to obtain high breakdown voltage. However, in the LIGBT the existence of abundant internal minority-carriers injected within the on state will delay the turn-off time about 10μs. The slow switching speed makes the applications of the primitive LIGBTs be limited seriously. Therefore, the improved LIGBT structure are studied and developed in this thesis. Thus, the shorted-anode LIGBT and the segmented-anode LIGBT are utilized for decreasing the turn-off time from 10μs down to 200ns. But they also increase the value of on resistance and onset voltage, where the segmented-anode LIGBT has lower value of on resistance and onset voltage. Furthermore, the segmented-anode can save 20~30% device area from shorted-anode LIGBT. This thesis also presents the design procedures of process parameters. The improved structures and the primitive structure can be used for the fundamental process in Taiwan and do not need any other masks. Through the aid of Medici and Davinci computer aided design tool, the primitive structure and two improved ones are simulated.